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I. Why Aquaculture? Author: Prof. Dr. Ergün Demir

What is aquaculture and why is it important? Aquaculture is one of the fastest way to produce animal protein for growing population in the World. Aquaculture is the art, science, and business of producing aquatic plants and animals useful to humans. Fish farming is an ancient practice and date back as far as 2500 BC. In Europe, fish raised in ponds became a common source of food during the Middle Ages. Today, aquaculture plays a major role in global fish supply. Today, the global community faces financial and economic crisis, climatic changes and the pressing food and nutrition needs of a growing population with finite natural resources. As the world’s population continues to increase over the coming decades, and global living standards rise, demand for fish is set to keep on growing. With most wild capture fisheries already fully exploited, much of that new demand will have to be met from aquaculture. According to FAO estimates, more than 50 % of all fish for human consumption now comes from aquaculture. Aquaculture is one of the most resource-efficient ways to produce protein. Fish come out well because, in general, they convert more of the feed they eat into body mass than livestock animals. Salmon is the most feed-intensive farmed fish to convert feed to body weigt gain and protein followed by chicken. Aquaculture is the controlled cultivation and harvest of aquatic organisms. Most commonly grown are finfish and shellfish, but other aquatic organisms are also cultivated such as seaweed, microalgae, frogs, turtles, alligators, and endangered species. There are many similarities between aquaculture and agriculture, but there are some important differences as well. Aquaculture, like agriculture, is necessary to meet the food demands of a growing global population with diminishing natural fisheries stocks. Aquaculture and agriculture are both farming. However, aquaculture is farming in the water and therefore requires a different set of knowledge, skill, and technology. The word “aquaculture” breaks down to “aqua” (water) and “culture” (to grow). Aquaculture takes place in four general aquatic environments: 1

Warmwater aquaculture is the culture of plants and animals, such as catfish, tilapia, and most ornamental fish, that thrive in o warm (>30 C), fresh water. Coldwater aquaculture is the culture of plants and animals, o such as trout, salmon, char, that thrive in cold (<20 C), fresh water. Coolwater aquaculture is the culture of plants and animals, such as yellow perch. Walleye, black bass, that thrive in cool o (between 20-30 C), freshwater. Mariculture is the culture of plants and animals, such as seaweed, bivalve mollusks, salmon, that are acclimated to marine or brackish waters.

Nutritive value of aquaculture products As with many animal products, fish and fishery products contain water, proteins and other nitrogenous compounds, lipids, carbohydrates, minerals and vitamins. However, the chemical composition of fish varies greatly from one species and one individual fish to another depending on age, sex, environment and season. Proteins and lipids are the major components whereas carbohydrates are detected at very limited levels (less than 0.5 percent). Vitamin content is comparable to that of mammals except for vitamins A and D which are found in large amounts in the meat of fatty species, especially in the liver of species such as cod and halibut. As for macro minerals and trace minerals, fish meat is a particularly valuable source of calcium and phosphorus as well as iron, copper and selenium. In addition, saltwater fish contain high levels of iodine. Lipid and fatty acid contents of aqua foods are the first important nutrient. Depending on their lipid content, which varies greatly from 0.2 percent to 25 percent, fish are classified as lean, semi-fatty or fatty. Bottom-dwelling ground fish such as cod, saithe and hake are common lean species. Fatty species include pelagics such as herring, mackerel and sprat. Some species store lipids in limited parts of their body tissues only or in smaller quantities than typical fatty species, and are consequently termed semi-fatty. Fish lipids contrast greatly from mammalian lipids in that they include up to 40 percent of longchain fatty acids that are highly unsaturated and contain five or six double bonds. 2

Table 1. Chemical composition of fillets of various fish species ( Species Blue whiting Cod Eel Herring Plaice Salmon Trout Tuna Norway lobster Pejerrey Carp

Scientific name Micromesistiu poutassou Gadus morhua Anguilla anguilla Clupea harengus Pleuronectes platessa Salmo salar Salmo trutta Thunnus spp. Nephrops norvegicus Basilichthys bornariensis Cyprinus carpio

Lipid (%)

Protein (%)

Energy value (kJ/ 100 g)
















0.3-14.0 1.2-10.8 4.1

21.5 18.8-19.1 25.2











Aquatic products are well known for they high content of omega-3 (n-3) polyunsaturated fatty acids (PUFA). PUFA have anti-thrombotic activity in blood circulation system. PUFA of the omega-3 series are responsible for prevention of cardiovascular diseases associated with the regular consumption of aquatic products. Others benefits such as prevention of cancers have also been associated with regular omega3 PUFA intake. It is generally recommended to eat aquatic products at least one meal per week. Aquatic products are also a source of animal protein. Fish proteins contain all the essential amino acids and, like milk, eggs and mammalian meat proteins, have a very high biological value. In addition, fish proteins are an excellent source of lysine, methionine and cysteine, and can significantly raise the value of cereal-based diets, which are poor in these essential amino acids. These proteins and their amino acids are very important for young and elderly people to meet their essential amino acids reguirements. Fish also has a nonprotein nitrogen (NPN) fraction. This NPN-fraction constitutes from 9 to 18 percent of the total nitrogen, including trimethylamine oxide (TMAO), free amino acids, creatine and carnosine. Despite their low levels, the constituents of the NPN fraction play a major role in fish quality. 3

Aquaculture sector in the World Aquaculture is the fastest growing animal food producing sector in the world and is an increasingly important contributor to global food supply. Moreover, aquaculture has become something more than an alternative to wild capture fisheries for food production. FAO estimates than in the year 2030, 65 % of all seafood consumption will come from aquaculture. Production from world capture fisheries has been fluctuating around 90.4 million tonnes per year during the last two decades. On the other hand, aquaculture production shows an increasing trend that led to a production of 63.6 million tonnes globally (Table 2). It should also be noted that around 23.2 million tonnes of the capture production were used for nonâ&#x20AC;?human consumption activities (feeds as fish meal and fish oil). Therefore, aquaculture is the main seafood source for human consumption worldwide. World per capita food fish supply increased from an average of 9.9 kg (live weight equivalent) in the 1960s to 18.8 kg in 2011. Fish consumption was lowest in Africa with 9.1 kg per capita, while Asia accounted for two-thirds of total consumption, with 20.7 kg per capita. The corresponding per capita fish consumption for Europe is 24.6 kg. Aquaculture represented 41 % of the total seafood production in the world, valued in 95 billion Euros. In the last three decades, world food fish production of aquaculture has expanded by almost 12 times, at an average annual rate of 8.8% (Table 3). The growth rate in farmed food fish production from 1980 to 2010 far outpaced that for the world population (1.5%), resulting in average annual per capita consumption of farmed fish rising by almost seven times. Table 2. World fisheries and aquaculture production and utilization (FAO, 2012) PRODUCTION (million tonnes) Total Capture Inland Marine Total Aquaculture Inland Marine TOTAL WORLD FISHERIES UTILIZATION Human consumption Non-food uses Population (billions) Per capita food fish supply (kg)


2006 90.0 9.8 80.2 47.3 31.3 16.0 137.3

2011 90.4 11.5 78.9 63.6 44.3 19.3 154.0

114.3 23.0 6.6 17.4

130.8 23.2 7.0 18.8

The top ten producing countries accounted for 87.6% by quantity and 81.9 % by value of the worldâ&#x20AC;&#x2122;s farmed food fish. Asia accounted for 89 % of world aquaculture production by volume, and this was dominated by the contribution of China, which accounted for more than 60% of global aquaculture production volume. Other major producers in Asia are India, Viet Nam, Indonesia, Bangladesh, Thailand, Myanmar, the Philippines and Japan. Aquaculture production uses freshwater, brackish water and fullstrength marine water as culture media. In terms of quantity, the percentage of production from freshwater rose to almost 62 %, with the share of marine aquaculture production declining to just above 30 %. Freshwater fish farming has been a relatively easy entry point for practising aquaculture in developing countries, particularly for smallscale producers. Table 3. Aquaculture production by region: quantity and percentage of world total production (FAO,2012) aREGION Africa tonnes percentage America tonnes percentage Asia tonnes percentage Europe tonnes percentage European Union tonnes percentage Non-European-Union countries tonnes percentage Oceania tonnes percentage WORLD (tonnes)



10.271 0.40

1.288.320 2.20

173.491 6.80

2.576.428 4.30

1.799.101 70.10

53.301.157 89.00

575.598 22.40

2.523.179 4.20

471.282 18.40

1.261.592 2.10

26.616 1.00

1.265.703 2.10

8.421 0.30 2.566.882

183.516 0.30 59.872.600

Livelihoods in aquaculture sector In recent years, fisheries and aquaculture make crucial contributions to the worldâ&#x20AC;&#x2122;s wellbeing and prosperity. In the last five decades, world fish food supply has outpaced global population 5

growth, and today fish constitutes an important source of nutritious food and animal protein for much of the world’s population. In addition, the sector provides livelihoods and income, both directly and indirectly, for a significant share of the world’s population. Fish and fishery products are among the most traded food commodities worldwide. While capture fisheries production remains stable or decreases, aquaculture production keeps on expanding. Aquaculture is set to remain one of the fastest-growing animal food-producing sectors and, in the next decade, total production from both capture and aquaculture will exceed that of beef, pork or poultry. However, in a world in which almost a billion people still suffer from hunger, it is the poor, especially those in rural areas, who are most vulnerable to the combination of threats outlined above. Millions of people around the world find a source of income and livelihood in the fisheries sector. The most recent estimates indicate that there were 54.8 million people engaged in the primary sector of capture fisheries and aquaculture. Of these, an estimated 7 million people were occasional fishers and fish farmers (of whom 2.5 million in India and 1.4 million in China). More than 87.3 percent of all people employed in the fisheries sector were in Asia, followed by Africa with 7 percent. Approximately 16.6 million (about 30 percent of all people employed in the fisheries sector) were engaged in fish farming, and they were even more concentrated in Asia (97 percent). Although 87.3 percent of the world’s fishers and fish farmers were in Asia, the region accounted for only 68.7 percent of global production with an average of 2.1 tonnes per person per year in 2010, compared with 25.7 tonnes in Europe. Table 4. Fishery production per fisher or fish farmer (tonnes/year) by region (FAO, 2012) Region Africa Asia Europe Latin America and the Caribbean North America Oceania World



2.0 1.5 25.1 6.8

8.6 3.3 29.6 7.8

Capture + aquaculture 2.3 2.1 25.7 6.9

16.3 17.0 2.3

183.2 33.3 3.6

18.0 18.2 2.7

The 54.8 million fishers and fish farmers represented 4.2 percent of the 1.3 billion people economically active in the broad agriculture sector worldwide. However, the relative proportion of those engaged 6

in capture fisheries within the sector actually decreased from 87 percent to 70 percent in last 10 years, while the proportion of those engaged in fish farming increased from 13 to 30 percent. Europe experienced the largest decrease in the number of people engaged in capture fishing with a 2 percent average annual decline between 2000 and 2010, and almost no increase in people employed in fish farming in the same period.

Aquaculture sector in Europe Europe is a good example in aquaculture for production systems and the product quality parameters. Europe represents the largest market for fish in the world. Althought aquafoods and seafoods consumption have increased in Europe over the past decades, own production of farmed and captured fish have not increased. However, net fish imports have increased, and self sufficiency has decreased. There are many reasons that have lead to an increase in demand for fish:  Population size has increased.  Overall the real price of fish has come down, making the product more attractive to consumers.  Real incomes have increased, causing greater demand for fish.  Consumers have become more health conscious for the effects of omega-3 fatty acids on heart diseases, causing a positive shift in demand as fish consumption is known to have important health benefits. World aquaculture production is led by Asia with 91 % of the production in quantity and 81 % in value. In contrast, the EU is only a minor player in aquaculture production. The EU contribution to world aquaculture production has been decreasing significantly over time in both volume and value terms, representing 2 % and 3 % of global production. Successful development of aquaculture presupposes control with the biological production process. Beyond that, what may be called economic sustainability, namely profitable production over time, is required. This depends not only on the ”sale” price, but also on the cost of production. Considering the fierce competition (foreign but also internal) and high labour and capital costs that the EU aquaculture sector bears, high value species are most relevant for EU producers. More than that, in view of the high costs, species of interest are those where productivity improvements can be achieved over time, giving 7

rise to lower costs of production. This is an absolute necessity, because as production expands, price is bound to come down. Moreover, governance takes on an important responsibility in the future of aquaculture. Positive important roles for governments include expediting the planning process for new farms (and farm extensions), as well as makings sites available. 20 Table 5.Top ten European aquaculture producers (FAO,2012) Country Norway Spain France United Kingdom Italy Russian Federation Greece Netherlands Faroe Islands Ireland Other Total

Tonnes 1.008.010 252.351 224.400

Percentage 39.95 10.00 8.89

201.091 153.486 120.384 113.486

7.97 6.08 4.77 4.50

66.945 47.575 46.187 289.264 2.523.179

2.65 1.89 1.83 11.46 100

The EU aquaculture represents 16 % of the total EU seafood production. Marine capture fisheries represented 79 % and inland capture fisheries 5 %. In 2010, marine fishes accounted for 28 % of the EU aquaculture production in weight, freshwater fishes accounted for 22 % and shellfish for 50 %. EU aquaculture production is mainly concentrated in 5 countries: France, Greece, Italy, Spain and United Kingdom (Table 5). Spain, with 20 % of the total EU production in volume, is the largest aquaculture producer in the EU, followed by France (18 %), United Kingdom (16 %), Italy (12 %) and Greece (9 %). These five countries account for 75 % of the total EU aquaculture production in weight. Per Economic performance of the EU aquaculture sector is shown in Table 6. In aquaculture, there were almost ten thousand companies. The majority of the companies in the EU aquaculture sector are micro窶親nterprises with less than 10 employees. These comprised 90 % of all aquaculture enterprises in the EU. The total sales volume for the EU aquaculture sector is estimated to be 1.36 million tonnes. The total value of sales, or turnover, from the EU aquaculture sector is estimated to have reached 3.58 billion Euros. It is estimated that the EU aquaculture sector directly employs more than 85,000 people. 8

Table 6. Economic Indicators for the EU aquaculture sector (Guillen and Motova, 2013) Number of enterprises, (number)


Total sales volume, (thousand tonnes) Turnover, (million €) Employment, (number)

1.361 3.580 61.478

Full time equivalents (FTE), (number)


Total employment in full time equivalents (FTE) of 29.038 FTEs. The EU aquaculture sector has an important component of part‐time work. This evident from the proportion of employment measured in FTE and total employment. Women accounted for the 29 % of the EU aquaculture sector employments, the 23 % measured in FTE. The average wage (per FTE) for the EU aquaculture sector was about 19.400 Euros per year. There is a lot of variability on the salaries paid in each country and subsector. The salaries varied from about 1.900 Euros per year in Bulgaria to 73.500 Euros per year in Denmark. Gross value added for the EU aquaculture sector would had been near 1.5 billion Euros. The EU aquaculture sector is an significant player, with a turnover today of roughly 3.5 billion Euros, which generates some 65.000 jobs. EU production remained more or less constant since 2005, so EU countries imports aguaculture products mostly from developing countries. Europe has a number of key strengths in aquaculture. The greatest asset is the rigorous quality standards they have set, to ensure that:  aquaculture products are good for human consumption,  good for the environment in which they are raised,  and respectful of the health of the animals themselves. Yet these strengths also bring with them challenges. High standards inevitably mean higher costs, and make it more difficult for European fish farmers to compete in markets both at home and abroad. Increasing demands on both coastal and inland environments lead to increasing competition for space with other activities, including residential housing and tourism. The European Fisheries Fund specifies sustainable aquaculture as one of its priority axes. Shellfish aquaculture is a labour intensive segment in Europe, which faces limited environmental concerns. This sector contributes actively to external trade and has a very important social dimension given the high number of employed persons. Total sales volume for the EU aquaculture shellfish sector is estimated to be 0.72 million


tonnes and the total value of sales (turnover) is estimated to be 1.12 billion Euros. Marine fish aquaculture is characterised by being generally capital intensive, with high input and high labour productivity. This segment has potential to compete on the increasingly globalised market but it faces constrains which hinder further expansion. Its environmental impacts are also generally higher than those of other aquaculture segments. The total sales volume for the EU marine aquaculture sector is estimated to be 0.51 million tonnes and the total value of sales (turnover) is estimated to be 1.57 billion Euros. Freshwater aquaculture is often characterized by low labour productivity and low capital intensity, serving mainly local markets (e.g. carp). In this category limited demand and strong international competition is limiting the profitability and growth of production. However, the extensive and artisanal production may play a role in environmental and recreational aspects (e.g. regarding biodiversity and preserving cultural landscapes). The total sales volume for the EU freshwater aquaculture sector is estimated to be 0.31 million tonnes and the total value of sales (turnover) is estimated to be 0.91 billion Euros. The main aquaculture species in the EU are mussels (471 thousand tonnes, 37 % of all production), rainbow trout (193 thousand tonnes, 15 % of all production), Atlantic salmon (171 thousand tonnes, 14 %), Pacific cupped oysters (104 thousand tonnes, 8 %), gilthead seabream (88 thousand tonnes, 7 %), common carp (66 thousand tonnes, 5 %) and European seabass (54 thousand tonnes, 4 %). This species constituted more than 85 % of the total EU aquaculture production in value.

Overview of the aquaculture FISHFARM partnersâ&#x20AC;&#x2122; countries



Turkey Turkey produced 703.545 tonnes fishery products and imported 65.698 tonnes. Per capital consumption is 6.32 kg per year per person. Captured sea production is 477.658 tonnes and aquaculture production is 188.890 tonnes Inland water production is 100.446 tonnes and saltwater production is 88.344 tonnes. Distribution of aquaculture production by types in Turkey is 53 % trout, 25 % sea bass, 17 % sea bream and 5 % others. 10

Poland Aquaculture in Poland consists only of land‐based freshwater farms. The total weight of aquaculture production for human consumption is 30.8 thousand tonnes and the turnover amounted to 67.5 million Euros. The biggest sector is the production of carps. Carps stand for 49 % of the whole aquaculture turnover and for 50 % of the production weight. Carp farms are widespread all over the country but the largest facilities are located in central and southern Poland. Carp production is carried out in the traditional land‐based farms in earth ponds. The next species is trout, which contributed for 42 % to both turnover and production weight. Most of aquaculture farms produce more than one species, mainly African catfish, grass carp, silver carp, bighead carp, crucian carp, pike, European catfish, tench and sturgeon. Other species constituted 9 % of turnover in aquaculture and have 8 % share in volume of production. There are about 1,000 aquaculture land‐based farms in Poland.. A legal form called “natural person” is dominating (76 % of all aquaculture entities), next were legal persons (22 %) and “other” (2 %). That means that the aquaculture farms are managed mainly by small family enterprises or small to medium companies. The number of people employed in them is estimated to be 5,500.

Hungary The Hungarian aquaculture sector produce 14.2 thousand tonnes. This production is valued 28.1 million Euros. All aquaculture production is freshwater, because it is a landlocked country. Common carp is the main species produced, with 70 % of the total production in weight and 69 % in value. Other relevant species are north African catfish, silver carp and grass carp.

Italy The Italian aquaculture sector produce 153.4 thousand tonnes. This production is valued 333.2 million Euros. Japanese carpet shell is the main species produced in value terms, with 28 % of the total production in value and 23 % in weight. Followe by rainbow trout representing 24 % and 22 %, European seabass with 13 % and 4 %, Mediterranean mussel with 12 % and 42 %, and seabream with 12 % and 4 % of the total weight of production and value, respectively. Other important species are European eel, sturgeons, sea trout, etc. Italy is one of the fifth largest aquaculture producing states in Europe. Total legal entities in the aquaculture sector numbered 754. Up to 11

2008, the Italian aquaculture sector was represented by small size enterprises, dominated by family run business with no more than 5‐10 employees. More recently, the number of small size enterprises has decreased and, in many cases, larger firms have taken over these smaller ones.

Iceland Iceland is far away from other countries. Freshwater fish–native species are Atlantic salmon, Brown trout, Arctic charr, European eel, American eel and Sticklebacks. Salmon and charr are still most the important aquaculture fish speces in Iceland, but a lot of experiments with new species have not resulted in significant production. Production in 2012 estimated 7.400 tonnes. Environmental conditions in the sea around Iceland limit production in cages (temperature, and lack of shelter). Temperatures have now increased because of global warming which could lead to increased production. A lot of suitable areas for fish farming are banned for production due to possible negative effect on production of natural Atlantic salmon which is a very valuable resource in Iceland. There are now 11 cage rearing companies operating in Iceland. Value of fisheries exports is around 2.0 billion USD per year.

Lithuania Lithuanian aquaculture sector produce 3.2 thousand tonnes. This production is valued about 6.3 million Euros. The sector is mostly represented by carp ponds. Lithuania produces no marine aquaculture. The total employment in the aquaculture sector is 348 employees, mostly men, representing about 82 % of total number of employees. The common carp is the main specie produced by Lithuanian aquaculture sector, representing 86 % of value and 92 % of value of total production. Other important fish species are Northern pike, trouts and sturgeons.

References Anonymous, 2011. Fisheries Statistics 2011.Turkish Statistical Institute ( Anonymous, 2012. The State of World Fisheries and Aquaculture 2012. Food and Agriculture Organisation of The United Nations, FAO Fisheries and Aquaculture Department, Rome, 2012. Anonymous, 2012. Bremerhaven Declarations on aquaculture product quality and consumer demands. Workshop 2, October 15 – 16, 2012, Bremerhaven, (


Anonymous, 2013. Bremerhaven Declarations on devel opmental trends and diversi fication in European Aquaculture New species and -or new products from established aquac ulture species. . Workshop 4, September 23–24, 2013, Bremerhaven, ( Anonymous, 2013. Commission calls for cooperation to boost sustainable aquaculture in Europe. ( Anonymous, 2013. The Economic Performance of the EU Aquaculture Sector–2012 exercise (STECF-13-03) Scientific, Technical and Economic Committee for Fisheries (STECF). European Commission JRC Scientific and Policy Report, Edited by Jordi Guillen, Arina Motova Edited by Guillen, J. and Motova, A. Buttner, J.K., 2011. What is Aquaculture and Why is it important? Flotsam&Jetsam, Aquaculture, Winter 2011,, 39(3): 1-8. Green, K., 2012. The global picture - world aquaculture. FAO: The State of World Fisheries and Aquaculture 2012 ( is documentation/publications/pcp2008_en.pdf ture_en.pdf 9_en.pdf 0004:EN:PDF 0015:0034: EN:PDF 189:0001:0023: EN:PDF FIN:EN:PDF FIN:EN:PDF

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II. Fish Biology and Fish Species in Europe and Partners’ Countries Authors: Assoc. prof. dr. Anželika Dautartė

Fish biology With more than 26.000 named species, 44 % or more of them inhabits fresh water. Ray-finned fishes constitute about half of all vertebrates and more than 95 % of all the organisms we call fishes. As a group, they are so diverse that no single characteristic separates them from other vertebrates. Most forms, however, can be characterized by the presence of a swim bladder, fin rays, bony skeleton, bony scales embedded in the skin, a terminal mouth, and an operculum that covers the gills and protects them. We can divide ray-finned fishes (class Actinopterygii) into two major groups according to tail and scale type. Scales are usually considered a fundamental part of a fish, yet not all fish have them! In fact, fish can have large, bony plates, small, fine scales, modified scales, or no scales at all. The size and type of scales which a fish possesses is indicative of its lifestyle. Active fish that live in fast moving streams, such as trout, often have many, fine scales. In contrast, perch and sunfish, which live in quiet water and have, fewer, larger scales. Ray-finned fish scales can be classified into three different types: ganoid, cycloid, ctenoid. The first (the Chondrostei) contains forms such as marine sturgeons that possess heterocercal tails similar to those of sharks, a skeleton made primarily of cartilage, and ganoid scales. This scale type is typically found on gars (family Lepisosteidae). This is the ancestral scale of the bony fishes. These heavy scales are covered with a hard enamel. Members of the second group (the Neopterygii) typically have homocercal tails, cycloid or ctenoid scales (Figure 1), and more maneuverable fins. Cycloid scales are round, flat and thin, with a smooth rear edge. They are smooth to the touch. Trout, minnows and herrings have this type of scale. Ctenoid scales have a toothed rear edge which makes the fish rough to the touch. These are common on the spiny finned, bony fishes such as the sunfishes (family 15

Centrarchidae). Homocercal tails have dorsal and ventral flanges that are nearly equal in size, and the vertebral column usually does not continue into the tail. Cycloid and ctenoid scales are thinner and more flexible than ganoid scales and are less cumbersome for active swimmers.




Figure 1. Fish scales: a- thick, heavy, ganoid scales are characteristic of primitive bony fishes such as sturgeons; lighter, more flexible scales such as b- cycloid scales; c- ctenoid scales Ray-finned fish have median fins and paired fins (Figure 2). The median fins consist of one or more dorsal fins, a caudal fin, and usually one anal fin. Median fins help fishes maintain stability while swimming. The paired fins consist of pectoral and pelvic fins, both of which are used in steering. Pectoral fins also help to stabilize the fish.


Figure 2. The general internal and external anatomy of a ray-finned fish

Figure 3. Some basic fish tail shapes The fins of modern fish come in an amazing array of shapes and forms, however many of them can be related to the seven basic patterns depicted in Figure 3. The world's great fisheries are associated with the taking of rayfinned fishes. They are of commercial importance for food, fertilizer, 17

aquarium pets, sport, and many other products. Many species are overexploited and in danger of collapse. Climatic and other environmental changes have detrimentally affected fish stocks in certain areas.

Body shape The shape of a fish's body is mainly determined by the characteristics of its habitat. Fishes that are very active swimmers, such as tuna (Thunnus) have a fusiform body shape (Picture 4) with a very high and narrow tail. This streamlined body form allows these fish to move through the water with great efficiency. Fishes that live in sea-grass or on coral reefs, such as butterflyfish (Chaetodon) and angelfish (Pomacanthus), have a laterally compressed or deep body that helps them to navigate through their complex environment (Figure 4). Bottom-dwelling fishes, such as the left-eye flounders (family Bothidae), have depressed or flattened bodies (Figure 4). Flounders begin life looking like normal fish, but early in the juvenile stage, they begin to swim on their side and an eye migrates from what will become the bottom side to the upper side.

Figure 4. Fish shapes: a â&#x20AC;&#x201C; fish that are active swimmers such as this marlin have a fusiform body, b- reef fish, such as this butterfly fish, that swim among the corals have laterally compressed or deep bodies, c â&#x20AC;&#x201C; bottom dwellers such as this flounder have horizontally compressed or depressed bodies, d sedentary fish such as this anglerfish have globular bodies, e â&#x20AC;&#x201C; burrowing fish and fish that live in tight crevices, such as this moray eel, have snakelike bodies.


Body designs Fish are amazingly diverse in their morphology. They come in all shapes and sizes, from the expected, to the bizarre. Form and function work together and examination of basic body shapes give us insight to fish lifestyles. Most fish fall into one of six basic body forms: the rover predator, lie-in-wait predator, surface oriented, bottom dweller, deep-bodied or eel like. Rover predator. A streamlined body, pointed head, narrow caudal peduncle and a forked tail are the characteristics of this typical fish. In fact, this is the shape most people think of when they think of a fish! Their evenly distributed fins provide stability and maneuverability, which is important for endurance swimming and actively seeking prey. This body type is typical of stream dwellers, which forage in fast water. Common examples of this body form are the trouts (family Salmonidae), some minnows (family Cyprinidae), tuna (family Scombridae). Lie-in-wait predator. These are typical ambush predators on fast moving prey. Their bodies are streamlined and elongate, with a flattened head and a mouth full of pointy teeth. In some families with this body plan, such as the pikes, the dorsal and anal fins are inserted far toward the rear, very near the caudal fin. This fin arrangement allows the normally still fish to generate rapid acceleration when the large muscle mass of the cylindrical body pushes against the water with the combined area of the dorsal, caudal and anal fins. In this way, they are able to thrust forward at high speeds to attack a passing fish. Their cryptic colouration and secretive behaviour helps to conceal them from suspecting prey. The pikes (family Esocidae) have this body plan. Surface oriented. The upward turned mouths of these fish allow them to exploit plankton and small fish at the surface of the water. These fish are typically small in size, with a dorsoventrally flattened head, large eyes, streamlined body and a dorsal fin that occurs far back on the body. In stagnant water, this body design is ideal for taking advantage of the rich oxygen supply at the air-water interface. The Arctic cod (family Gadidae) has this body form. Bottom oriented. This body plan is suited for living in benthic habitats. Many body shapes accomplish this goal, but generally fish with this body plan have a reduced or absent swim bladder and are flattened. Bottom rovers have a shape similar to the rover-predator, 19

but have a flattened head, humped back and enlarged pectoral fins. These fish often possess barbells or "whiskers" with taste buds to locate prey in muddy water. The mouth shapes of these fish vary to exploit different food sources found on the bottom. Catfishes (family Ictaluridae) have large, terminal mouths, while sturgeons (family Acipenseridae) have fleshy, protrusible lips to suck plant and animal material off the bottom. Eel-like. Elongate bodies, rounded heads and rounded tails allow these fish to explore a diversity of habitats including crevices and holes in rocky and reefed areas, soft muddy bottoms and densely vegetated areas. Long dorsal and anal fins allow these fish to exploit open water habitats as well. Eels (family Anguillidae), loaches (family Balitoridae) and gunnels (family Pholidae) have this body plan.

Fish coloration and patterning Fish coloration and patterning can serve many functions. Because most ray-finned fishes use vision as their primary sense in food finding and communication, appropriate coloration can help prey blend into their environment and become more difficult for predators to find. Likewise, predators can use coloration and patterning to conceal themselves from their prey. Coloration may also be useful to fishes as advertising to attract potential mates or to warn other species that they taste bad or are dangerous. Fish colors are of two basic types, pigments (biochromes) and structural colors. Pigments are colored compounds found in chromatophores, irregularly shaped cells usually appearing as a central cell body with radiating processes. Fish are able to alter their color by moving pigments between the central core and these processes. The flounder, for example, is well known for its ability to alter body color and pattern to match its immediate environment. The control of pigment movement is complex but appears to be under both hormonal and nervous influence. The most common pigments found in fishes are the melanins and carotenoids. Structural colors are produced by light reflecting from crystals located in specialized chromatophores called iridophores. Unlike pigments, these crystals are colorless and relatively immobile within the cells.


The biology of fish The following illustration of a largemouth bass shows some of the common internal features that are used to describe the differences between fish that are described in more detail below. Spine. The primary structural framework upon which the fish's body is built; connects to the skull at the front of the fish and to the tail at the rear. The spine is made up of numerous vertebrae, which are hollow and house and protect the delicate spinal cord. The skeleton of bony fishes is made of bone and cartilage. The vertebral column, cranium, jaw, ribs, and intramuscular bones make up a bony fish's skeleton (Figure 5). The skeleton of a bony fish gives structure, provides protection, assists in leverage, and (along with the spleen and the kidney) is a site of red blood cell production.

Figure 5. Sceleton of a fish ( Nervous system. The nervous system of fishes is poorly developed compared to that of other vertebrates. A bony fish's brain is divided into three sections: the forebrain, the midbrain, and the hindbrain. The forebrain is responsible for the bony fish's ability to smell. Bony fishes that have an especially good sense of smell, such as eels, have an enlarged forebrain. The midbrain processes vision, 21

learning, and motor responses. Blind bony fishes, such as blind cavefishes in the family Amblyopsidae, have a reduced midbrain. The hindbrain (medulla oblongata and cerebellum) coordinates movement, muscle tone, and balance. Fast-swimming bony fishes usually have an enlarged hindbrain. The spinal cord and a matrix of nerves serve the rest of the body and connects the brain to the rest of the body and relays sensory information from the body to the brain, as well as instructions from the brain to the rest of the body. The brain is a control center of the fish, where both automatic functions (such as respiration) and higher behaviors ("should i eat that critter with the spinning blades?") occur. All sensory information is processed here. Cardiovascular system. A bony fish's heart has two chambers: an atrium and a ventricle. The venous side of the heart is preceded by an enlarged chamber called the sinus venosus. The arterial side of the heart is followed by a thickened muscular cavity called the bulbus arteriosus.

Blood flow. The sinus venosus receives oxygen-depleted blood from the body. A valve at the end of the sinus venosus opens into the atrium. The atrium has thick, muscular walls. The atrium receives oxygen-depleted blood and pumps it into the ventricle. The ventricle is the largest and most muscular chamber of the heart. When filled with blood, it constricts, forcing the blood through the bulbus arteriosus. Blood flows through the bulbus arteriosus into the ventral aorta. A valve or series of valves in the bulbus arteriosus controls blood flow into the ventral aorta. From the ventral aorta, blood flows to the gill filaments, where it is oxygenated. Oxygenated blood flows from the gill filaments to the organs of the head and body. A complex system of arteries, veins, and capillaries circulates blood through the body and returns the blood to the sinus venosus. Digestive system. The esophagus in bony fishes is short and expandable so that large objects can be swallowed. The esophagus walls are layered with muscle. Most species of bony fishes have a stomach. Usually the stomach is a bent muscular tube in a "U" or "V" shape. Stomach and intestines break down (digest) food and absorb nutrients. Fish such as bass that are piscivorous (eat other fish) have fairly short intestines because such food is easy to chemically break down and digest. Fish such as tilapia that are herbivorous (eat plants) require longer intestines because plant matter is usually tough 22

and fibrous and more difficult to break down into usable components. A great deal about fish feeding habits can be determined by examining stomach contents.

Figure 6. Internal stucture of bony fish Gastric glands release substances that break down food to prepare it for digestion. At the end of the stomach, many bony fishes have blind sacs called pyloric caeca (Figure 6). The pyloric caeca are an adaptation for increasing the gut area; they digest food. This organ with fingerlike projections is located near the junction of the stomach and the intestines. Its function is not entirely understood, but it is known to secrete enzymes that aid in digestion, may function to absorb digested food, or do both.The pancreas secretes enzymes into the intestine for digestion. Liver has a number of functions. It assists in digestion by secreting enzymes that break down fats, and also serves as a storage area for fats and carbohydrates. The liver also is important in the destruction of old blood cells and in maintaining proper blood chemistry, as well as playing a role in nitrogen (waste) excretion. Most food absorption takes place in the intestine. The length of the intestine in bony fishes varies greatly. Plant-eating bony fishes generally have long, coiled intestines. Carnivorous bony fishes have shorter intestines. The digestive system terminates at the anus. Respiratory system. Water enters the gill chamber through a fish's mouth and exits through gill openings under the operculum. Blood flowing through the gill filaments absorbs oxygen from the 23

water. Some fish have adaptations for getting oxygen from air. Lungfish must return to the surface to breathe air. A lungfish swallows air to fill up an air sac or "lung". This lung is surrounded by veins that bring blood to be oxygenated. Its gills alone can't keep a lungfish supplied with enough oxygen to live. Other species such as tarpon (family Elopidae) can gulp air at the surface to supplement their oxygen demand. Some species of bony fishes can absorb considerable amounts of oxygen through their skin. Swim (or air) bladder: a hollow, gas-filled balance organ that allows a fish to conserve energy by maintaining neutral buoyancy (suspending) in water. Apparently the swim bladder originally developed in fish as an organ of respiration, as evidenced by the "lung" of the lungfishes. Fish caught from very deep water sometimes need to have air released from their swim bladder before they can be released and return to deep water, due to the difference in atmospheric pressure at the water's surface. Species of fish that do not possess a swim bladder sink to the bottom if they stop swimming. In some fishes the swim bladder has adapted to function as a sound amplifier. Osmoregulation. Both marine and freshwater fishes regulate the movement of water across their body surfaces. The tissues of marine fishes are less salty than the surrounding water, so water continually leaves the body of a marine fish through its skin and gills. To keep from becoming dehydrated, a marine fish drinks large amounts of water and produces a small amount of concentrated urine. In addition, its gills are adapted to secrete salt. The tissues of a freshwater fish are saltier than its surrounding environment, so water is continually entering the body of a freshwater fish through its skin and gills. Kidney filters liquid waste materials from the blood; these wastes are then passed out of the body. The kidney is also extremely important in regulating water and salt concentrations within the fish's body, allowing certain fish species to exist in freshwater or saltwater, and in some cases (such as snook or tarpon) both.Freshwater fishes do not drink water, and they produce large amounts of dilute urine. Gonads (reproductive organs). In adult female bass, the bright orange mass of eggs is unmistakable during the spawning season, but is still usually identifiable at other times of the year. The male organs, which produce milt for fertilizing the eggs, are much smaller and white but found in the same general location. The eggs (or roe) of


certain fish are considered a delicacy, as in the case of caviar from sturgeon. Muscles. Fish require a large muscle mass for swimming and maintaining activity for sustained periods of time. In fact, the muscles of the body and tail make up a significant portion of their total body mass. The body muscles can be divided into red and white muscle fibre, each serving a different purpose. Red muscle fibre is best suited for prolonged, slow contractions and endurance swimming. Fish that are active for long periods at a time typically have a lot of this muscle tissue. In contrast, white muscle fibre is best suited for short-term, rapid contractions. These are thicker than red fibre, have a poorer blood supply and lack an oxygen carrying pigment like myoglobin. These muscles are most useful for short bursts of swimming and are most common in sluggish fish. Otoliths. Otoliths are calcified structures found in the inner ears of fishes. These structures have layers, much like an onion. Using microscopy to count the layers and measure their width, allows fish biologists to age a fish, as well as assess its rate of development in relation to other individuals. For young fish, the layers can represent daily growth increments. Senses. Acoustic senses. The ears of a bony fish function in equilibrium, detecting acceleration, and hearing. There are no external openings to the ears. Sound waves travel through soft tissue to the ears. (A fish's soft body tissue has about the same acoustic density as water). There is great variation in hearing sensitivity, bandwidth, and upper frequency limit among bony fish species. Lateral line. Like the ear, the lateral line senses vibrations. It functions mainly in detecting low-frequency vibrations and directional water flow, and in distance perception. The lateral line system is a series of fluid-filled canals just below the skin of the head and along the sides of a bony fish's body. The canals are open to the surrounding water through tiny pores. Lateral line canals contain sensory cells. Tiny hairlike structures on these cells project out into the canal. Water movement created by turbulence, currents, or vibrations displaces these hairlike projections and stimulates the sensory cells. Eyesight. Bony fishes have a basic vertebrate eye, with various structural adaptations. A bony fish's eye includes rods and cones. 25

Bony fishes, especially those that live in shallow-water habitats, probably have color vision. Certain visual cells are specialized to particular wavelengths and intensitiesThe pupils of some species of bony fishes, such as eels, contract and dilate depending on light conditions. In most species of bony fishes, however, pupils can't contract or dilate. The water's surface can reflect up to 80% of light that strikes it. Bony fishes have large lenses to make the most of available light. In some species, the eye has a reflective layer called the tapetum lucidum behind the retina. The tapetum lucidum reflects light back through the retina a second time. Taste. Bony fishes have taste buds in their mouths. Some species have taste buds along the head and ventral side of the body. Taste perception hasn't been extensively studied in bony fishes. Some species can detect some sensations, such as salty, sweet, bitter, and acid stimuli. Taste may be responsible for the final acceptance or rejection of prey items. Smell. Olfactory cells in the nasal sac detect tiny amounts of chemicals in solution. In general, the sense of smell is well developed in fishes. The nasal areas and extent of the sense of smell vary among species. Species of freshwater eels (family Anguillidae) may detect chemicals in extremely low dilutions. Eels may detect a substance when only three or four molecules have entered the nasal sac. Studies suggest that smell guides at least some species of salmons (family Salmonidae) to their home streams during the breeding season. Some species can detect pheromones, chemical substances released by an animal that influence the behavior of members of the same species. Fishes may release pheromones during the breeding season or when alarmed. Electroreception. Some bony fishes in the families Electrophoridae, Gymnotidae, and Mormyridae produce a low-voltage electric current that sets up a field around the fish. Tiny skin organs on the fish detect disruptions in the electric field that are caused by prey or inanimate objects. Electric organs are made up of cells called electrocytes that have evolved from muscle cells. Electrocytes typically are thin and stacked on top of one another. Electroreception is an adaptation for detecting prey and for navigation in murky water. Some other fishes produce stronger electric currents for stunning prey


Reproduction. Sexual maturity. Age, gender, and size influence sexual maturity mainly. Fishes become sexually mature at various ages, depending on species. In general, small species begin reproducing at an earlier age than large species. Some bony fishes are sexually mature at birth. Males of the dwarf perch (Micrometrus minimus) can spawn immediately after birth. Although female dwarf perch receive sperm soon after they're born, they do not bear young for up to a year. Some bony fishes become sexually mature shortly after birth. The western mosquitofish becomes sexually mature within a year. Most bony fishes become sexually mature between one and five years. It may take ten years or more for some bony fishes to become sexually mature. The eels (family Anguillidae) become sexually mature at 10 to 14 years of age, and the sturgeons (family Acipenseridae) may take up to 15 years to mature. Reproductive modes. In most species of bony fishes, sperm and eggs develop in separate male and female individuals. Males and females may look similar, or they may look very different. Male/female differences may include size, coloration, external reproductive organs, head characteristics, and body shape. Some bony fishes are hermaphrodites: a single individual produces both sperm and eggs.Sequential hermaphrodites are born one sex and change sex sometime during the course of life. Reproductive behavior. Various factors may influence bony fish breeding: changes in the duration of sunlight; temperature change. Other factors that may affect reproduction are presence of the opposite sex, currents, tides, moon stages, and presence of spawning areas. Reproduction is generally cyclic in bony fishes. Some species spawn continuously throughout the spring and summer. Some bony fishes may spawn many times a year. Many bony fishes reproduce once a year until they die. Other bony fishes may reproduce only once during their lifetime. Pacific salmon (family Salmonidae) reproduce only once during their five-year lifespan, then die soon after. Diadromous fishes must have access to both marine and freshwater systems to complete their life cycle.


Fish species countries





There in EU, according the date of European commission, the freshwater fish (including trout and eels farmed in fresh water) took 22 % from EU aquaculture production. The biggest part is taken by molluscs and crustaceans (50 %) and seawater fish (including salmon and trout farmed in sea water) - 28 %. According to Eurostat data, there is a six species of fish among the top 10 species (Table 1) produced in aquaculture in the European Union:  Rainbow trout,  Atlantic salmon,  Gilthead seabream,  Common carp,  European seabass,  Turbot Table 1. The top 10 species produced in aquaculture in the European Union Fish species

Mediterranean mussel Rainbow trout Blue mussel Atlantic salmon Pacific cupped oyster Gilthead seabream Common carp European seabass Japanese clam Turbot

Volume in tonnes (live weight) 315 171 199 905 179 041 157 647 106 065 96 278 70 761 57 478 34 406 9019

Volume percentage of total 24 % 15 % 14 % 12 % 8% 7% 5% 4% 3% 3%

Traditionally, gilthead seabream were cultured extensively in coastal lagoons and brackish ponds, particularly in valliculture in northern Italy and in esteros in southern Spain. In the 1980s, however, gilthead seabream were reproduced successfully in captivity and intensive rearing systems were developed, especially in sea cages. Most sea bream come from aquaculture. The EU is by far the biggest producer worldwide, followed by Turkey. Within the EU, Greece is the largest producer, followed by Spain. Trade between the EU and third countries is very limited. On the other hand, intra-EU trade is 28

substantial, Greece being the major exporter towards Italy, Portugal, France and Spain. Table 2. The top species produced in aquaculture in partner countries (volume in percentage of total value) Country

Aquacultural fish species Atlantic cod Atlantic salmon Arctic char Common carp Bighead carp Silver carp Catfish European seabass Gilthead seabream Trout












35 14






47 -



11 12 -

2 -

3 -














Carp is very common fish for Europe, having a special role Christian religion. Genetic selection gave us a robust, fleshy, longlived fish. Carp took 5 % of total volume (live weight), majority of production comes from aquaculture. Within the EU, the two biggest producers are Poland and the Czech Republic. Aquaculture is the major production method for seabass, but fishing still accounts for more than 10 % of the total seabass production worldwide. The EU is the largest producer of seabass with a share of 80 %. Within the EU, Greece is the first producer, followed by Spain. There are very few exports outside the EU, while imports from third countries are significant, coming mainly from Turkey. Italy, Greece and the Netherlands are the main importers of seabass from Turkey. As far as Italy is concerned, these imports supply local demand, but Greece and the Netherlands tend to re-export seabass to other EU countries.


Table 3. Aquaculture species in partner countries (partners interview data) Cultivation Countries TR

Aquacultural fish species in Europe Arctic char Salvelinus alpinus Atlantic cod Gadus morhua Atlantic salmon Salmo salar Sturgeon Acipenser baerii





Bighead carp Aristichthys nobilis


Crucian carp Carassius carassius Grass carp Ctenopharyngodon idella


Silver carp Hypophthalmichthys molitrix


Common carp Cyprinus carpio



Common barbel Barbus barbus







+ + +







+ + +


+ +

Eel Anguilla anguilla


European catfish Silurus glanis



North African catfish Clarias gariepinus



Northern Pike Esox lucius


Gilt-head sea bream Sparus aurata



Peled Coregonus peled Perch Perca fluviatilis Brown trout Salmo trutta m. fario Rainbow trout Oncorhynchus mykiss


















Sea trout Salmo trutta Sea bass Dicentrarchus labrax



Senegal flounder Solea Senegalensis


Tench Tinca tinca



Tilapia Oreochromis spp.

+ +

Turbot Psetta maxima


Wels catfish Silurus glanis

+ +




Analysis of fish species composition in project partner countries according to Eurostat data (2009) shows, that the most popular was trout â&#x20AC;&#x201C; grown in Italy, Lithuania, Poland and Turkey, the second place was taken by common, bighead and silver carp. Carp was the most popular specie in Hungary, Poland and Lithuania (Table 2). The species produced in aquaculture in partner countries in 2013 are presented in Table 3. There is necessary to underline, that from 17 aquaculture fish species: arctic char, atlantic cod, atlantic halibut, 30

atlantic salmon, basa catfish, beluga sturgeon, common carp, common barbell, common pandora, gilt-head sea bream, north African catfish, rainbow trout, sea trout, sea bass, sole, tilapia, turbot, white sea bream, announced as a major ones by Directorate of Maritime affairs and fisheries, 11 (marked in bold) are grown in partner countries (Table 3). The most popular aquaculture specie is rainbow trout, it is grown almost in all partner countries. The second place takes cyprinids: common and bighead carp, as well as crucian and grass carp. Hungary, Poland and Lithuania has almost same composition of species, more specific species are grown in Iceland and Turkey. The species produced in aquaculture in partner countries in 2013 are presented in Table 3. There is necessary to underline, that from 17 aquaculture fish species: arctic char, atlantic cod, atlantic halibut, atlantic salmon, basa catfish, beluga sturgeon, common carp, common barbell, common pandora, gilt-head sea bream, north African catfish, rainbow trout, sea trout, sea bass, sole, tilapia, turbot, white sea bream, announced as a major ones by Directorate of Maritime affairs and fisheries, 11 (marked in bold) are grown in partner countries (Table 3). The most popular aquaculture specie is rainbow trout, it is grown almost in all partner countries. The second place takes cyprinids: common and bighead carp, as well as crucian and grass carp. Hungary, Poland and Lithuania has almost same composition of species, more specific species are grown in Iceland and Turkey. More information regarding mentioned species biology, nutrition facts ect., can found visiting webpage of Directorate of Maritime affairs and fisheries ( index_en.htm).

References Aquaculture. Retrieved from Bony fishes. Retrieved from Fish Body Forms and Lifestyles. Retrieved from Fish and shellfish species. Retrieved from index_en.htm Ontario,B.(2011).Fish morphology. Retrieved from 152776 The fish anatomy. Retrieved from


III. Water Quality and Treatments Authors: Valdimar Ingi Gunnarsson, SigurĂ°ur MĂĄr Einarsson


Water quality parameters

Water quality parameters criteria Water quality criteria for aquaculture systems have typically considered parameters such as temperature, dissolved oxygen, carbon dioxide, total gas pressure, ammonia and nitrite. Other parameters can also be important such as acidity of the water, salinity and total dissolved solids. The value of a given water quality criteria may depend strongly on the species, size, and culture objectives. The complexity of the criteria Each individual parameter is important, but it is the aggregate and interrelationship of all the parameters that influence the health and growth rate of the fish. Each water parameter interacts with and influences other parameters, sometimes in complex ways. Concentrations of any given parameter that would be harmless in one situation can be toxic in another. For example, when aeration and degassing problems occur, carbon dioxide levels will generally become high while at the same time dissolved oxygen levels become low. The result of this particular situation is that not only is there less oxygen available to the fish, but the fish is also less able to utilize available oxygen levels.. The high carbon dioxide level of the water affects the fishâ&#x20AC;&#x2122;s blood capacity to transport oxygen, aggravating the stress imposed by low dissolved oxygen levels. Dissolved oxygen Of all the water quality parameters, dissolved oxygen is the most important and most critical parameter, requiring continuous monitoring in intensive production systems. When the oxygen content reach 75% saturation this level marks the lower limits for many species, but the limits differ between species, and factors like fish size and environmental conditions also need to be taken into account. A continual low oxygen concentration is likely to reduce appetite, growth 32

and inhibiting or suppressing its immune system decreasing disease resistance (Table 1). One can expect substantial or heavy losses of fish if the oxygen content is as low or lower than 40% for an extended period. Apparent signs of low oxygen content are when the fish swims desperately to the water surface, gulps in air and/or gathers towards the water inlet where oxygen levels are higher. Table 1. Guidelines for oxygen levels for salmonids (e.g. salmon, trout and arctic charr), sea bream and sea bass. Oxygen saturation 85% 75% 60% 40% 30%

Effect on fish No indication of negative effect Reduction in appetite Reduced appetite, possible mortality No appetite and high mortality Massive mortality

Temperature Water temperature is second only to dissolved oxygen in importance and impact on the economic viability of a commercial aquaculture venture. Each species has its own optimal temperature for growth and development and upper and lower temperature limit for survival. Table 2. Recommended parameters for production planning for Atlantic salmon. Variable Mean oxygen consumption from feed consumed Mean carbon dioxide produced from oxygen consumption Mean total ammonia produced from oxygen consumption

Parameter 0.25-0.45 kg oxygen/ kg feed consumed 1.1 kg carbon dioxide / kg oxygen consumed 0.04-0.06 kg total ammonia / kg oxygen consumed

Carbon dioxide As a rule of thumb, 1.1 g of carbon dioxide (CO 2) is produced for every 1 gram of oxygen consumed by fish (Table 2). The safe or accepted levels of carbon dioxide in water depend upon fish species, the developmental stage of the fish and the water quality. For Atlantic salmon when carbon dioxide contents exceed 10 mg/L level, the growth rate starts to reduce and especially when 30 mg/L. is reached.


Ammonia Ammonia is present in slight amounts in natural waters. When fishes become more intensively cultured, ammonia can reach harmful levels. Ammonia is a waste product of protein metabolism by aquatic + animals. In water, ammonia occurs either in the ionized (NH 4 ) or unionized (NH3) form depending on pH level. Un-ionized ammonia is considerably more toxic to fish and occurs in greater proportion at high pH and warmer temperatures. Increasing pH by only one unit, i.e., from 6.5 to 7.5, increases the concentration of toxic unionized ammonia concentration by factor of ten (Figure 1). In general, warm water fish is more tolerant to ammonia toxicity than cold-water fish and freshwater fish are more tolerant than seawater fish. Un-ionized ammonia concentrations should be held below 0.05 mg/L and total + ammonia (ionized (NH4 ) and un-ionized (NH3)) concentrations below 1.0 mg/L for long-term exposure.

Figure 1. Percentage of free ammonia (as NH3) in freshwater at varying pH and water temperature. Nitrite Nitrite (NO2-) is formed at the intermediate step in the nitrification process and is toxic to fish at levels above 2 mg/L. If the fish is gasping for air, although the oxygen concentration is fine, a high nitrite concentration may be the cause. At high concentrations, nitrite is transported over the gills into the fish blood, where it obstructs the oxygen uptake.


Water quantity The oxygen contents of the water The oxygen contents in water decreases with increasing temperatures (Figure 2). Oxygen content of saline waters is less than freshwater at the same temperature. So more seawater than freshwater is needed to meet the oxygen needs of the fish, with other factors being constant.

Figure 2. Increasing the water temperature/ salinity reduces itâ&#x20AC;&#x2122;s oxygen-holding capacity. The oxygen content is measured in the units of milligrams per kg water (mg O2/kg water), which is also numerically and physically equivalent to parts per million or ppm (1 mg O 2/kg water = 1 ppm O2 in water). Often the content is given in mg oxygen per liter or mg O 2/L. As 1 L water is approximately 1 kg, the units are often used interchangeably. Oxygen consumption Oxygen consumption in fish is related to many factors, such as the species. The main factors affecting the oxygen needs are: ď&#x201A;ˇ

Fish size: The proportional use of oxygen is less, the larger the fish. As an example, one kg of 50 g sized fish uses 150 mg 35

   

oxygen per hour, but one individual one kg sized fish only uses 56 mg oxygen per hour. Temperature: The oxygen use increases with higher temperature. Added to that, the solubility of oxygen in water is less at higher temperature. Growth rate: Oxygen consumption increases with increasing growth rate. Feeding: When the fish is fed and begins to digest the food, its oxygen use increases. Swimming velocity: Oxygen consumption increases with increasing swimming velocity. Stress: Every kind of strain or stress, such as size grading or bathing against disease, increases the oxygen use of the fish.

Flow requirements Water quantity required for the fish is determined by:  Oxygen consumption of the fish  Oxygen contents of the water

Figure 3. Flow requirement for post-smolt Atlantic salmon, threshold for carbon dioxide and total ammonia and water treatments methods to improve the quality of water. The oxygen demands of fish, is the primary determinant of water exchange in fish tanks. When water exchange is reduced and water 36

oxygen levels are supplemented by injecting pure oxygen, the concentration of carbon dioxide may exceed acceptable levels (Figure 3). In a flow-through system where oxygen is injected, the minimum required flow for Atlantic salmon to prevent excessive carbon dioxide accumulation is 0.2â&#x20AC;&#x201C;0.3 L /min/kg fish. Action must be taken to remove carbon dioxide at lower water flow rates with degasser. The minimum flow rate to maintain acceptable levels of un-ionized (NH3) is 0.05 L/min/ kg fish. When water exchange is reduced further in recirculation system, ammonia may be a limiting factor and thus the use of bio filter is needed.

Overview of land-based aquaculture systems a. Flow-through aquaculture systems One of the main factors influencing the complexity of an aquaculture facility is the water use strategy. Traditionally, facilities were designed as Flow-through aquaculture systems (FTAS) using a single-pass water use strategy (Figure 4). This is a well known culture method that is widely practiced in Europe.

Flow-through aquaculture systems using a single-pass water use strategy.

Re-use relative to flow-through is often between 50 and 75%.

Recirculation systems normally range of 95-99% re-use compared to the water consumption in a flow through system.

Figure 4. Flow-through aquaculture systems, Partial reuse aquaculture systems and Recirculating aquaculture systems. The green arrow stands for fresh clean water. The red arrow stands for used water passing tank effluents. Yellow stands for re-used water (Drawing: V.I.Gunnarsson). 37

The principles of the systems In traditional flow-through aquaculture systems, water is passed through the culture system only once and then it is discharged back to the aquatic environment. The flow of water through the culture system supplies oxygen to the fish and carries dissolved and suspended waste out of the system. The water quality within the culture system is maintained by flushing of contaminants and furthermore by replacing all system water before dissolved oxygen concentrations drop below minimum acceptable limits or contaminate concentrations (i.e. ammonia, solids, and carbon dioxide) can accumulate to above maximum acceptable limits. High water use Flow-through systems became a popular and cost effective approach for aquaculture when water sources were plentiful and competing uses for water resources were low. However, sustainability principles, increasing competition for limited supplies of high quality water, and the need for improved control of culture conditions are generally causing aquaculture facilities to consider partial reuse or recirculation technologies as alternatives to traditional methods (Table 3).

b. Partial reuse aquaculture systems Water recycle systems, involving water treatment processes, provide an alternative to traditional systems. Recycle systems are usually classified as either Partial reuse aquaculture systems (PRAS) or Recirculating aquaculture systems (RAS) which primarily differ in the magnitude of the portion of the water that is recycled, and the complexity of the water treatment processes used (Figure 4). The principles of the systems Partial reuse Aquaculture Systems (PRAS) use water treatment processes to allow a portion of the culture discharge water to be recycled and supplied back into the culture tanks (Figure 5). For aquaculture facilities faced with limited water resources, sustainability issues, or a requirement for improved control over culture conditions, reuse technology is the next step in the technological evolution of modern aquaculture systems. 38

Partial reuse aquaculture systems focus on the use of a few, simple treatment technologies to provide significant reductions in water use. These technologies typically include gas balancing and oxygenation, moreover they may also include solids removal and disinfection, but do not normally include ammonia removal through bio filtration. Table 3. Advantages and disadvantages of flow-through aquaculture systems, partial reuse aquaculture systems and recirculating aquaculture systems (Based on Anon. 2010). Advantages


Flow-through aquaculture systems

Culture systems are relatively simplistic and easy to operate Typically lower capital investment compared to more advanced culture systems

 


Site placement is limited by water availability Requires high flow rates of high quality water of the appropriate temperature Temperature is fully dependant on intake water conditions Control of temperature and water quality is difficult and usually cost prohibitive Facilities are susceptible to disease ingress with intake water and disinfection of intake water is very costly Produces high volumes of dilute effluent which may be difficult and costly to treat

Partial reuse aquaculture systems

  

 

Significantly reduced water consumption and effluent volumes (50%75% typical) Reductions in energy consumption are possible when influent pumping costs are high Allows for significant production expansion without increasing water use Typically lower capital investment compared to recirculation systems but higher than flow-through systems Site placement is less dependent on water availability More economical influent treatment and temperature control Disinfection of influent water for biosecurity protection is more economical Much less mechanical and operational complexity than recirculation systems but higher than flow-through systems Control of culture conditions is improved Reduced volumes result in more economical effluent treatment


Recirculating aquaculture systems

Significantly reduced water consumption and effluent volumes (95%99.9%). Minimal influent water consumption allows for cost effective treatments to improve water quality and prevent the ingress of disease Minimal effluent volumes result in the ability to treat both effluent water and sludge to meet sustainability objectives Full control of culture temperature is possible, allowing for an all yearround production independent of fluctuating environmental or influent water conditions A high degree of control over culture conditions enables operators to optimize fish growth and feed conversion, increased production, and improve product quality Facilities can be located almost anywhere; site selection is not tied to the access to large volumes of water

Generally more mechanically and operationally complex than other types of culture systems. Initial capital investment is typically higher but the cost of production is typically lower than in other culture systems.

Water use The maximum reuse rate that may be achievable without the addition of more advanced treatment processes will depend on the biomass and feed load on the system, and on the specific water quality requirements of the fish species in culture. Partial reuse rates from 50% to 75% are common, depending primarily on fish sensitivity to unionized ammonia concentrations.


Figure 5. Partial reuse aquaculture systems with aeration and oxygenation (Drawing: V.I.Gunnarsson).

c. Recirculating aquaculture systems The principles of systems Recirculating aquaculture systems incorporate additional treatment technologies beyond those used in PRAS, allowing for significantly greater quantities of water to be reused. Recirculation systems afford a level of control well beyond any other technology application in aquaculture and provide significant production and economic benefits. Recirculating aquaculture systems maximize water re-use by employing a comprehensive water treatment system. Water treatment processes typically include solids removal, bio-filtration, gas balancing, oxygenation, and disinfection (Figure 6). By addressing each of the key water quality concerns through treatment, rather than flushing as is used in flow-through and partial reuse systems, ultimate control over culture conditions and water quality is provided. Water use A typical recirculation system will provide a maximum recirculation rate of 95% - 99% of the system flow rate while maintaining optimal 42

water quality for the fish. However, with the addition of denitrification technologies, and by capturing water extracted from sludge thickening processes, some systems may become effectively â&#x20AC;&#x153;closedâ&#x20AC;? with very little to no exchange of water. A balance must be achieved in design, between water quality objectives and treatment system complexity and cost.

Figure 6. The principle of a recirculation system. The basic water treatment system consists of mechanical filtration, biological treatment, degassing, oxygen enrichment, UV disinfection and pump (Drawing: V.I.Gunnarsson and photo from manufacturers).

d. Aeration and oxygenation Gas transfer Principle As air comes in contact with water the dissolved gases approach equilibrium with atmospheric partial pressures. Typical aquaculture water with low dissolved oxygen and high dissolved carbon dioxide and nitrogen and when exposed to atmospheric air has the tendency to approach equilibrium and will transfer oxygen in and carbon dioxide and nitrogen out of the water (Figure 7).


Figure 7. Gas transfer in air and water (Drawing: V.I.Gunnarsson) The aeration process of water will add some oxygen to water through simple exchange between the gases in the water and the gases in the air depending on the saturation level of oxygen content in the water. The equilibrium of oxygen in water is 100% saturation. When the water has been through the fish tanks, the oxygen content has been lowered typically down to 70%. Aeration of this water will typically bring saturation up to approximately 90% and in some systems 100% levels can be reached. To reach more than 100% oxygen saturation, water and oxygen are mixed under pressure whereby the oxygen is forced into the water. Apart from water temperature and salinity that we will consider constant, three main factors control oxygen dissolution into water:   

pressure exchange surface contact time

Pressure Under atmospheric pressure and for instance 20°C and 30 ppt salinity, the maximum quantity of oxygen that can be dissolved into 3 water (saturation value) is 7.6 g/m . This value can be greatly increased since the dissolution power of each gas rises as the pressure increases. But when using air under pressure this also results in a very dangerous situation for the fish due to increase in nitrogen concentration in the water, such as aeration in deep water. However, when using pure oxygen, this problem will not arise since 44

with oxygenation, dissolved nitrogen will reduce to or below saturation for purposes of controlling gas bubble disease. Exchange surface Gas diffusion into water is also a function of the amount of contact surface between the two phases. For a certain water volume, the larger this exchange surface, the higher and the quicker would be the gas transfer. For example, a large gas bubble has a smaller surface than a number of fine bubbles containing the same gas volume.

Contact time Transfer of a gas into water is also a function of time. Methods and devices which maximize contact time are to be preferred, such as counter current mixers and mixers with water velocity lower than that of rising bubbles. Shape of tanks may also influence oxygen diffusion as fine bubbles of oxygen take more time to reach the surface in deeper than in shallower tanks.

Aeration systems Types of aerators Each aeration device can be classified as either surface, gravity or submerged. Surface aerator spray or splash water into the air and thus transfer oxygen from the air into the water. Submerged aerator mixes water and air together in an aeration basin and transfers oxygen from air bubbles into the water. Gravity aerators are a special type of surface aerator that uses gravity rather than mechanical power to transfer oxygen (Figure 8). Gravity aerators Gravity aerators utilize the energy released when water loses altitude to increase the air-water surface area. Regardless of the aerator design the aerator efficiency will be directly related to its ability to increase the surface area to volume ratio and the amount of turbulence. Typically gravity aerators are packed column and splash screen (Figure 8). If the source of oxygen is enriched or pure oxygen gas rather than air, the units are called pure oxygen aerators (Figure 8). 45

Carbon dioxide stripping tower One of the most common ways to strip carbon dioxide out of the water is with a stripping tower (Figure 8). Here influent water from the culture tank with high carbon dioxide enters at the top of a tower and is distributed for uniform loading. The tower internals may have water breakup of some sort of plastic packing. As the water passes through the tower, air is blown through the tower and it exits having picked up carbon dioxide from the water. Typical air volumes blown are five to ten times the water volume pumped through the tower.

Typical gravity aerator with splash screen.

Carbon dioxide stripping tower.

Low head oxygenator (pure-oxygen aerators).

Figure 8. Simple drawing of gravity aerator, stripping tower for degassing carbon dioxide and pure oxygen aerators (Drawing: V.I.Gunnarsson) Surface aerator Surface aerator spray or splash water into the air and the most typical aerators are vertical pump aerator and paddlewheel aerator. A vertical pump aerator consists of submersible electric motor with an impeller attached to its shaft. The motor is suspended by floats and the impeller jets water into the air to affect aeration (Figure 9). The rotating paddle wheel of the paddlewheel aerator splashes water into the air to affect aeration. The device consists of floats, a frame, motors, speed reduction mechanism, coupling, paddlewheel and bearings (Figure 9). 46

Figure 9. Paddlewheel aerator (left) and vertical pump aerator (right) (Drawing: V.I.Gunnarsson and photo from manufacturers). Submerged aerator The submerged aerator mixes water and air together in an aeration basin. Since bubbles rise in a water column there is relative motion between water and bubbles. This causes water circulation and renewing of surface area in contact with the bubble which increases oxygen transfer. There are several types of submerged aerators for instance propeller-aspirator-pumps and diffused-air systems (Figure 10).

Figure 10. Diffused-air system aerators (left) and propelleraspirator-pump aerator (right) (Drawing: V.I.Gunnarsson and photo from manufacturer).

The primary part of a propeller-aspirator-pump aerator is an electric motor, a hollow shaft wich rotates, a hollow housing inside 47

where the rotating shaft fits a diffuser and an impeller attached to the end of the rotating shaft (figure 10). With this operation the impeller accelerates the water to a velocity high enough to cause a drop in pressure with the hollow, rotating shaft. Then the air is forced down the hollow shaft by atmospheric pressure and as a result, fine bubbles of air exit the diffuser and enter the turbulent water around the impeller.

Figure 11. Airlift pumps lift the water a few cm in order to induce water movement by gravity and simultaneously aerate/degas the water (Photo: J.Geirsson). Diffused-air system aerators use a low pressure, high volume air blower to provide air to diffusers positioned on tank/pond bottom or suspended in the water (Figure 10). A variety of types of diffusers have been used, for example ceramic dome diffuser, porous ceramic tubing and carborundum air stones. One version of diffused-air system aerators are airlift pumps. There are two functions of the airlift pumps (also called mammoth pumps): To lift the water a few cm in order to induce water movement by gravity and simultaneously aerate/degas the water (Figure 11).

Pure oxygen systems Pure oxygen Pure oxygen is often delivered in tanks in the form of liquid oxygen, but can also be produced on the farm in an oxygen generator. 48

Pure oxygen is relatively expensive compared to air and only systems with high absorption efficiencies are generally economical. Oxygen diffusers Pure oxygen diffuser generally has a low absorption efficiency and has been used in transport systems and deep fish tanks. Diffusers are simply placed on the bottom of the tanks and oxygen is fed directly to them under pressure from the bulk storage facility. Diffusers introduce pure oxygen into water as cloud of very small bubbles (Figure 12). Some recently developed fine-bubble diffusers have absorption efficiencies in the range of 40 to 60% when submerged at 1-2 m or more. In deeper tanks the use of pure oxygen diffusers will be more economical.

Figure 12. Pure oxygen diffusers in a fish tank (Drawing: V.I.Gunnarsson and photo from manufacturers). Low head oxygenator The units consist of a distribution plate positioned over few rectangular chambers (Figure 8). Water flows over the dam boards through the distribution plate and then falls through the rectangular chambers. All of the pure oxygen is introduced into the outer or first rectangular chamber. The mixture of gases in the first chamber, which now has diluted oxygen concentration, pass sequentially through the remaining chambers. The gaseous mixture will decrease in oxygen concentration from chamber to chambers while the oxygen is continued to be absorbed. Finally the gaseous mixture will exit from 49

the last chamber. This gas is referred to as off-gas. Each of the rectangular chambers are gas tight and orifices between the chambers are constructed to reduce back-mixing between the chambers. Super saturation There are several ways of making super-saturated water with oxygen contents reaching 200-300%. Typically oxygen cones or deep shafts (Figure 13) are used. The principle is the same. Water and pure oxygen are mixed under pressure whereby the oxygen is forced into the water.

Figure 13. Water and pure oxygen are mixed under pressure in the oxygen cone (A) and the deep shaft (B) (Drawing: V.I.Gunnarsson and photo from manufacturer). Oxygen cone are sealed columns that increase in diameter with depth. They are either cone-shaped or are constructed by pipe sections of increasing diameter from top to bottom. Oxygen and water are introduced at the top of the column where the column diameter is narrow and water velocity and mixing is the greatest. As the water flows downward, the buoyancy of oxygen bubbles struggle to rise against the current and thus the contact time between oxygen and water is maximized, increasing absorption efficiency. To enable supersaturation, oxygen cones are operated under moderate pressures. Disadvantage of oxygen cones is that pumping water under pressure consumes a lot of electricity. In the deep shaft the pressure is reached by digging a pipe loop down few meters depth and injecting the oxygen at the bottom of the 50

loop. The pressure from the water column above will force the oxygen into the water. The advantage of the deep shaft is that pumping costs are low but the installation is troublesome and more expensive.

2. Water treatments a. Solids capture Solids capture methods Important methods for removing suspended solids are sedimentation, filtering and flotation. Suspended solids settle relatively easy because of their weight and the settlement can for instance take place in settling tanks with low water velocities that also stimulate settlement. Filtration can occur in sieves or spongy material. In flotation, particles are adsorbed by air bubbles due to the surface tension of the particles and they can be removed again when bubbles reach the water surface (foam fractionation). Sedimentation Sedimentation occurs as a result of gravity forcing particles heavier than water to â&#x20AC;&#x153;settleâ&#x20AC;? to the floor. Since the wet density of solid wastes 3 from trout farming operations ranges averages 1.07 g/cm , settling chambers must provide for quiescent conditions for effective sedimentation at the end of raceways (Figure 14). In turbulent flow conditions, such light solids will be easily re-suspended in the water column and removal efficiency will be compromised.

Figure 14. Schematic diagram of a raceway (Drawing: V.I.Gunnarsson) Sludge traps are positioned at the bottom of the production units (Figure 15). 51

Figure 15. Sludge traps (Drawing: V.I.Gunnarsson) Sludge traps can remove a great deal of the particulate matter before it starts to dissolve and then becomes more difficult to trap. Once particles are trapped, short flushes, automatically or manually, will transport the particles away from the production units without removing too much water. Swirl separator With double drain it is possible effectively to separate settleable solids from suspended solids. After being concentrated in a double drain the settleable solids are transported to a swirl separator in which water is hurled against the sides and is removed at the top of the swirl separator. The heavier particles are accumulating in the middle of the vortex in the swirl separator and are moved towards a conical bottom where they are discharged separately (Figure 16). Mechanical filtration Some effective methods for removal of particulate matter involve drum filters (Figure 16) and disc filters. The principle involves that water is sieved and the particles are trapped and flushed off when the drum reaches a certain point in its rotation. Water and particles are then transported away from the filter. Band filters are similar to drum filter in that they employ fine mesh screens to trap particulate wastes. The band filter is typically positioned in a small angle in relation to the water surface. This is to ensure that particles floating to the filter can be trapped firmly by the band. The particles are then flushed of the band at the very top and led to central sludge collection elsewhere. Band filters are effective for thickening sludge and are commonly used to de-water the backwash flow from drum filters. 52

Figure 16. Operational principles of a rotary drum filter and swirl separator (Drawing: V.I.Gunnarsson and photo from manufacturers).

b. Biological treatment Nitrification process The primary aim of biological treatment is to eliminate dissolved substances. To some extent biological treatment can also remove small particles that have passed through the mechanical treatment. In recirculated systems the biological treatment mostly occurs in bio filters. Bio-filters are filled with elements that provide a huge surface and thus allow for large colonisations of bacteria that are responsible for degrading the excretory products. In order to facilitate the nitrification process (oxidation of ammonia to nitrate) it is necessary to eliminate most of the organic matter. Bio-filter â&#x20AC;&#x201C; High surface area: Bio-filters are typically constructed using plastic media giving a high surface area per mÂł of bio-filter. The bacteria will grow as a thin film on the media thereby occupying an extremely large surface area. The aim of a well-designed bio-filter is to reach as high a surface area as possible per mÂł without packing the bio-filter so tight that it will get clogged with organic matter under operation. It is therefore important to have a high percentage of free 53

space for water to pass through and to have a good overall flow through the bio-filter together with a sufficient back-wash procedure. Back-wash procedures Back-wash procedures must be carried out at sufficient intervals depending on the filter. Compressed air is used to create turbulence in the filter whereby organic matter is ripped off. The bio-filter is shunted while the washing procedure takes place and the dirty water in the filter is drained off and discharged before the bio-filter is connected to the system again. Fixed and moving bed bio-filter Both fixed bed filter and moving bed filters are submerged units under water. In fixed bed filters plastic media is fixed and not moving (Figure 17). The water runs through the media as laminar flow to make contact with the bacterial film. In the moving bed filter, the plastic media is moving around by a current created by pumping in air (Figure 18).

Figure 17 Fixed bed bio-filter (Drawing: V.I.Gunnarsson and photo from manufacturer). Filters with a moving media (moving bed) have better selfcleansing abilities, and larger cleansing capacity since the surface area of the media is very large. However the disadvantage is that those tiny particles may dissociate from the moving media and create poor water quality in the production units, unless they are trapped by subsequent filtering. Moreover, the energy consumption in moving bed filters is rather high.


Figure 18. Moving bed bio-filter (Drawing: V.I.Gunnarsson and a photo from manufacturer).

c. Water disinfection Disinfection Disinfection can be described as the reduction of microorganisms such as bacteria, viruses, fungi and parasites to a desired concentration. The aim of disinfection of water in fish farming is to reduce to an acceptable level the risk of transfer of infectious disease from the water to the fish. Disinfection of water actually occurs at several places in an aquaculture plant. Usually the water is disinfected, whether it is sea water or fresh water. At the larval stage it is particularly important to reduce the number of microorganisms because larvae are more vulnerable to infection. In a recirculating aquaculture system the water may also be disinfected before being used again to avoid increasing microorganism burden. The most common treatments for water disinfection are ultraviolet light (UV light) and ozone. Ultraviolet light UV lamps are usually placed in a chamber in the water supply. UV disinfection works by applying light in wavelengthâ&#x20AC;&#x2122;s that destroy DNA in biological organisms. In aquaculture both pathogenic bacteria and 55

one-celled organisms are targeted. The UV light does not impact the fish as UV treatment of the water is applied out of the fish’s production area. Ozone Ozone is used in recirculating aquaculture systems as a disinfectant, to remove organic carbon, and also to remove turbidity, algae, colour, odour and taste. Ozone can effectively inactivate a range of bacterial, viral, fungal and protozoan fish pathogens. But the effectiveness of ozone treatment depends on ozone concentration, length of ozone exposure (contact time), pathogen loads and levels of organic matter. In spite of the fact that ozone is a very effective oxidizing agent, higher ozone concentrations are a risk to cultured fish stocks causing gross tissue damage and stock mortalities. This also ivolves a risk to the bacterial films on the bio-filters. When adding ozone gas to water, a special injection system has to be used to ensure good gas-water mixing. The retention time must be long enough for two processes:  To enable the ozone to destroy the microorganisms  To remove residual ozone toxic to the fish before entering the fish tank.

3. System monitoring and control a. Cage farms Oxygen – an important factor for growth and fish welfare The most important water quality parameters in sea cage farms are dissolved oxygen and temperature. Ideally, measurements of dissolved oxygen should be made continually. Many sea cage farms have an oxygen sensor on the camera used to control feed rate and fish welfare (Figure 19). It is possible to move cameras in sea cages and measure oxygen contents in different parts of the cage. When measured daily it is important to choose the time of the day when dissolved oxygen contents are at the lowest value. At most sites the dissolved oxygen content of surface waters approximates saturation levels and as long as cages are maintained relatively free from fouling there should be few problems. High fouling and high density of fish in cage especially when current rates are 56

slow, can cause low oxygen contents in the sea water, low fish growth rate and even mortality. High temperatures reduce the absolute amount of oxygen that water can hold in a solution and increases the oxygen demands of the fish. In critical situations farmers monitor dissolved oxygen levels by reducing the feeding rate and by avoiding the handling of fish. This will keep the oxygen consumption to a minimum. Dissolved oxygen levels can fall far below saturation in natural water bodies under blooming conditions where the phytoplankton night-time respiration can cause a marked decline in dissolved oxygen reaching minimum around dawn. Temperature â&#x20AC;&#x201C; the foundation for all feeding regimes and growth models: The temperature of the seawater at the fish farm must be monitored closely, because this affects the health and the welfare of the fish. Fishes are cold-blooded vertebrates and their body temperature is the same as their surroundings. High temperatures will increase their metabolic rate, resulting in increased feed intake and oxygen consumption. The optimal temperature for growth and fish welfare differs between fish species. A fish has also upper and lower temperature limits for survival and in extreme situations it can be necessary to stop the feeding and wait with handling of the fish.

Figure 19. Movable camera in sea cage with oxygen and temperature sensor (Drawing: V.I.Gunnarsson and photo from manufacturer). 57

b. Land-based farms Alarms systems important Intensive fish farming has the potential for a significant increase in production per volume of water, however it has the increased risk of loss due to equipment or management failures. Furthermore it requires close monitoring and a control of the production in order to maintain optimal conditions for the fish at all times. Technical failures can easily result in substantial fish loss, thus alarms are a vital installation for securing the operation. Murphyâ&#x20AC;&#x2122;s Low states simply states that: if anything can go wrong, it will. Parameters to monitor Determining what can go wrong and generating a list of worst-case scenarios is a never-ending quest. Common monitoring parameters in intensive fish farms, are tank water level, water flow and water quality (Table 4). Table 4. A short list of potential parameters to monitor in intensive fish farm Type/system Tank water level Water flow Water quality

Causes Drain valve opened, standpipe fallen or removed, leak in system, overflowing tank. Valve shut or opened too far, pump failure, loss of suction head, intake screen plugged, pipe plugged. Low dissolved oxygen, high carbon dioxide, supersaturated water supply, high or low temperature, high ammonia, nitrite or nitrate, low pH.

In many modern farms, a central control system can monitor and control oxygen levels, temperature, pH, water levels and motor functions. If any of the parameters moves out of the desired value limits, a stop/start process will try to solve the problem. If the problem is not solved automatically, an alarm will start. Monitoring system No system will work without the surveillance of the personnel working on the farm. The control system must therefore be fitted with an alarm system, which will call the personnel if any major failures are about to occur. A monitoring system comprises of three major components (Figure 20). 58

 

Sensors and measuring equipment which control the conditions. A monitoring centre that receives signals from the sensors and measuring equipment interprets them and eventually sends out alarm signals or signals to regulators. Equipment for warning when something is failing and emergency equipment that is started and stopped by regulators.

Figure 20. Sensors in fish farms, monitoring centre, emergency equipment and warning equipment.

References and further information Anonymous. 1998. Idaho waste management guidelines for aquaculture operations. Idaho Department of Health and Welfare, Division of Environmental Quality, Twin Falls, ID. 80 p. ( Anonymous, 2010. Feasibility assessment of freshwater Arctic charr & rainbow trout grow-out in New Brunswich. ReThink Inc. and Canadian Aquaculture Systems Inc. 104 p. ( %20Study%20-Final%20Report%20_Ev_-1.pdf). Aquatreat, 2007. Manual on effluent treatment in aquaculture: Science and practice. Aquatreat - Improvement and innovation of aquaculture effluent


treatment technology. 162 p. ( Bregnballe, J. 2010. A guide to recirculation aquaculture. Eurofish, Copenhagen, Denmark. 66 p. Boyd, C. E. 1998. Pond water aeration systems. Aquaculture Engineering 18: 9-40. Colt, J. 2000a. Aeration systems. pp. 7-17. In, Stickney, R.R. (eds.) Encyclopedia of aquaculture. John Wiley & Sons Inc. Colt, J. 2000b. Pure oxygen systems. pp. 705-712. In, Stickney, R.R. (eds.) Encyclopedia of aquaculture. John Wiley & Sons Inc. Colt, J. 2006. Water quality requirements for reuse systems. Aquaculture Engineering 34: 143-156. ( Ebeling, J.M. & Vinci, B. 2011. Solids capture. Recirculating Aquaculture Systems Short Course. 20%20&%20Misc%20Papers%20Adobe%202006/5%20Solids%20Capture/S olids%20Control.pdf Heldbo, J. (ed.) 2013. Bat for fiskeopdræt i norden. Beste tilgængelige teknologier for Akvakultur i Norden (english abstract). TemaNord 2013:529. 406 p. ( Thorarensen, H. & Farrell, A.P. 2011. Review: The biological requirements for post-smolt Atlantic salmon in closed-containment systems. Aquaculture 312:114. ( Lekang, O.-I. 2013. Aquaculture Engineering. Willey-Blackwell. 415 p. Losordo, T.M. Masser, M.P. & Rakocy, J.E. 1999. Recirculating Aquaculture Tank Production Systems. A Review of Component Options. SRAC Publication No. 453. 12 p. ( Moretti, A., Pedini Fernandez-Criado, M., Vetillart, R. 2005. Manual on hatchery production of seabass and gilthead seabream. Volume 2. Rome, FAO. 152 p. ( Reid, G.K., Liutkurs, M., Robinson, S.M.C., Chopin, T.R., Blair, T., Lander, T., Mullen, J., Page, F. & Moccia, R.D. 2008. A review of the biophysical properties of salmonids faeces: inplications for aquaculture waste dispersal models and integrated multi-trophic aquaculture. Aquaculture research 40(3): 257-273. Timmons, M.B. & Ebeling, J.M. 2007. Recirculation Aquaculture. Cayuga Aqua Ventures, LLC. 975 p. Further information – Website Nuts & Bolts - The PR Aqua Team contributes articles to Hatchery International Magazine: SRAC Fact Sheets: Simple methods for aquaculture:


IV. Fish Farming Methods and Equipments Autors: Valdimar Ingi Gunnarsson, Sigurður Már Einarsson

1. General principles In aquaculture there are differences in the structures used, the intensities of culture, the degree of water exchange and the factors to be considered in selecting suitable species and farm sites for aquaculture. Choosing a site for an aquaculture venture will be strongly influenced by:   

Intensity of culture, Water exchange required, Biological characteristics of the selected species.

Owing to the great diversity of aquaculture operations, the description of types of aquaculture systems may be complex. Usually culture systems are classified according to three criteria.

Intensity of culture Intensity of culture reflects the number or biomass of aquaculture organisms per unit area or volume and also productivity of the systems. Broadly, intensity of culture can be classified as intensive, semi-intensive or extensive. In intensive aquaculture systems all the nutrition for culture stock comes from introduced feeds with no utilisation of natural diets. Intensive system may be culture of rainbow trout in ponds and raceways, salmon in sea cage and river eels in tanks. Extensive aquaculture systems are part of natural ecosystem, with low rearing density and technology. Food source is natural food organisms, often some input of animal and plant wastes (Table 1). Extensive aquaculture systems are not common in Europe. Semi-intensive culture applies to ponds and allows for an increase in the stocking density within the pond. There is more supplementation of the natural system than in extensive aquaculture. 61

Table 1. Comparison of the general characteristics of extensive and intensive aquaculture systems Extensive aquaculture

Intensive aquaculture

Culture system used

Natural water bodies and simple containment structures

Fabricated culture systems, tanks, cages, raceways, etc.

Technology level



Degree of control, nutrition, predators, environment, disease

Very low


Food source for cultured animals

Natural food organisms; often some input of animal and plant wastes

Pelletized, fabricated feeds which must be nutritionally complete

Production (kg/ha/year)

Low (per unit area or volume) (< 500 kg)

High; maximizing output of product in minimal surface area, water volume and time

Water exchange Water exchange describes the amount of water exchanged or the control of water to the system (Figure 1). In general, the levels of water exchange are static, open, semi-closed and recirculating (closed). Fish farms are typically constructed as flow-through systems, supplying fresh and oxygen rich water to the fish and by removing contaminated water. Energy consumption is relatively low in flowthrough systems. This is due to low cost water transport that occurs entirely by gravity in land-based farms and flow through net cages in addition to the low technological level that requires little energy. All systems loose water through evaporation, leaks, and in water accumulating in fish during growth. This means that all systems must supply water to some extent. Fully recirculated systems are defined by having a water consumption that is below 10% of the total volume on a daily basis. Fully recirculated systems are costly to establish and they also carry extra costs due to high energy consumption. 62

Figure 1. Aquaculture systems classified in relation to water exchange (Drawing: V.I. Gunnarsson) Structure used for aquaculture Culture structures describe what encloses or supports the aquaculture organisms. Broadly, aquaculture structures in Europe for finfish production include ponds, tanks, raceways, pens and cages (Figure 1). One type of structure is rarely used for the whole lifespan of a cultured species, except in some extensive culture. For instance, the intensive culture of a particular fish species from gametes to harvest may successively involve the following structures:  A small tank or box for roe  An embryonic development tank with gentle flow-through of water  A larval tank with gentle flow-through of water  A pond for growth of fingerlings to large juveniles  A cage for on-growing to harvesting




Figure 1. Three different structures used for aquaculture in Europe (Photo: V.I. Gunnarsson and J. Geirsson)


2. Structure for on-growing of fish Ponds Widely used and inexpensive Ponds are more widely used than any other type of culture unit in the world. In general, ponds are cheaper to construct per unit area than tanks and cages and may be inexpensive to run, depending on pumping costs. Ponds tend to have the lowest stocking densities of culture structures; however, density varies according to whether the system is extensive, semi-intensive or intensive. Four types of ponds Four types of ponds are natural, impoundment, excavated and levee. Natural ponds are located in low areas that fill with water or act as catch basins for runoff. An impoundment pond is built by constructing a dam across a ravine or stream bed retaining the water behind the dam. The simplest and most common type of constructed pond in Europe is the excavated pond, which is made by digging a pit. Levee-type ponds are constructed by pushing up dikes on flat land and filling them with water.

Figure 2. Small earthen excavated ponds for rainbow trout in Iceland (Photo: V.I. Gunnarsson) 64

Size and layout of ponds Fish can be grown in ponds of any size. Fish ponds range in size and are up to 10 ha. Ponds are usually rectangular to allow for the maximal utilization of land. Typically the length/width ratio is 2-3:1.The factors governing the size of the pond are access to pond for husbandry. The site conditions, limitations of construction equipment will also determine the pond size. Pond less than 0,5 ha are easier to manage and harvest. In large pond farms there is a carefully planned layout of ponds to include channels between ponds for inflow of water and outflow of effluent water. There may be tens to hundreds of ponds on a large farm. Water supply and drainage system Inlets and outlets are important component of ponds and need to be secure and easy to operate. The exchange of water through a pond is controlled via the inlet. Inlets may be pipes or channels. Flow through the inlets can be regulated by valves or boards or by the use of pumps. Outlets are usually pipes or weir gates, which are also known as monks.

Tanks and raceways Fish rearing units Flow-through fish units come in many shapes, depths and operational modes. Two flow patterns are commonly used: Plug-flow and circular flow (figure 4). In plug- flow mode, water enters at one end and travels in a direct line, at a uniform velocity to outflow at the opposite end. The rectangular raceway is the most common example. In a circulating mode, water enters a unit at a selected location and travels in a circular motion towards a center outlet. The circular or round tanks are the most common representative of this design (Figure 3).


Figure 3. Linear raceway and round tank flow pattern (Drawing: V.I. Gunnarsson) Raceway design Size and materials: Raceways are basically elongated tanks in wich water enters at one end and flows out at the other end (Figure 4). They generally consist of elongate, narrow and shallow systems with continuous water flow. The limited cross-section of the raceway together with strong flow rate is designed to keep continuous unidirectional flow along the raceway. Raceways are typically less than 50 m in a length, a depth < 1.5 m and require a high waterexchange rate. Raceways usually have a length to width ratio of 1:10. Most raceways are made of concrete (figure 6), but a few and especially small tanks are constructed of other materials such as plastic, fiberglass and geomembrane (Figure 4).

Figure 4. Schematic diagram of a raceway (Drawing: V.I. Gunnarsson) Raceway inlet: Water enters the raceway at one end and then flows through the raceway in plug-flow matter, with minimal backmixing. In raceways this is often achieved by delivering water at multiple points along the input end of raceway either by perforated pipes or over spillways (Figure 5). Maintaining uniform water quality may also be assisted by having multiple inlets along the length of the raceway. 66

Raceway outlet: A quiescent zone devoid of fish is usually placed at the end of a raceway tank to collect solids that are swept out of the fish-rearing area. Outlets of raceways are usually over spillways (Figure 5).

Figure 5. Raceway made of concrete in (Photo: V.I. Gunnarsson)

Figure 6. Land-based farms in Italy. Tanks of concrete, geomembrane and wood (Photo: V.I.Gunnarsson) Round tanks Size and materials: Round tanks used for on-growing of salmonids are generally large, usually between 10 and 30 m in diameter. 67

Smaller tanks are used in hatcheries, flatfish farms and on smaller farms. Diameter to depth ratio typically range from 3:1 to 10:1. The most common tank materials are concrete, steel and corrugated steel for bigger tanks and plastic and fibreglass for small tanks.

Figure 7. Round tanks in Islandsbleikja, land-based farm at Iceland. The water flowing through the tunnel between tanks (Potho: V.I. Gunnarsson) Tanks inlet: Design of inlet is important to achieve optimal water quality and self-cleaning of tanks. Open-end pipe inlets create nonuniform velocity profiles in the tanks, e.g., much higher velocity profiles along the tank wall; poor mixing in the central zone, resuspension of solids throughout all tanks depth, and poor flushing of solids from bottom (Figure 8). Horizontal submerged pipe inlets improve water mixing effectively throughout the tanks, but create a weaker and less stable bottom current (for solids cleaning). Vertical submerged inlet distribution pipes provide better self-cleaning than when injecting the water flow through an open-ended pipe or a horizontal distribution pipe, but the stronger bottom current (responsible for particle removal) also results in poorer mixing in central zone and therefore less efficient use of the flow exchange. Maximum uniformity in tank water conditions can be obtained by using an inlet flow distribution pipe that combines both vertical and horizontal branches.


Figure 8. Vertical (a) and horizontal (b) submerged pipe inlets and combines both vertical and horizontal branches (c) (Drawing: Valdimar Ingi Gunnarsson)

Figure 9. Open-end pipe inlets and vertical submerged inlets (Photo: V.I. Gunnarsson) Tank outlet: Round tanks concentrate settleable solids, e.g., fecal matter and uneaten feed at their bottom and center. The tank center is then logical location for bottom drain. The bottom center drains continuously remove the concentrated settleable solids and for the intermittent removal of dead fish that are captured at bottom center drain. The bottom center drain structure is also used for water level control by connecting it to a weir, either on inside or the outside of tanks (Figure 10). Round tanks can be managed as swirl settlers, i.e., settling basins with two effluents, because of their capability to concentrate solids at their bottom and center. Solids that concentrate at the bottom center drain, while the majority of flow (80-95%) is withdrawn at a elevated drain (Figure 10). 69

Figure 10. Standpipe inside (a), outside (b) tanks and dual-drain design (c) (Drawing: V.I. Gunnarsson) Differences between tanks Raceways require 1.5-2.0 times as much wall area as do round tanks (Table 2). Also less wall thickness is required for round tanks. Raceway are operated far below recommended water velocities for many fish species, generally velocities do not exceed 5 cm/s. Feces and excess feed settle quickly and accumulate on the bottom. This is a distinct disadvantage since fish activity resuspends these material, breaking them into finer fractions wich take longer to settle out. With high density of fish raceway can turn to be self-cleaning but with more breaking of feces than in round tanks. Table 2. Major differences between raceways and round tanks Criteria


Round tank


Inflow dependent Inadequate for solid removal Inadequate for fish exercise

Independent of inflow Self â&#x20AC;&#x201C; cleaning

Water quality

Distinct gradient Pass peak metabolites out

Uniform Mixes metabolites and allows some to remain

Wall area

Requires 1.5 to 2.0 times as must wall per water volume

Most efficient shape in water volume to wall area


Easy to crowd an harvest fish Difficult to equip with feeders

Difficult to crowd fish

Can meet fish requirements of exercise

Easy to equip with feeders

Round tanks can create optimum velocities through proper design of the inlet and outlet structures and velocities are largely independent of intake volume. Optimal water velocities in round tanks provide for fish health conditioning and tanks can be self-cleaning. Raceways have a distinct water quality gradient from inlet to outlet. Dissolved oxygen level decrease downstream, while metabolic 70

byproducts, such as ammonia and carbon dioxide increase. Round tanks have a more or less homogeneous water quality environment. Management is easier in raceways in relation to crowding fish and harvesting. Round tanks are more difficult to manage for fish handling, since fish cannot be cornered as in raceways. In cases where fish can be pumped through outlets, is easy to empty the fish out of the round tank. Round tanks lend themselves more readily to automatic feeding systems, requiring fewer feeding stations than raceways to distribute fees throughout the rearing unit, since water currents will distribute the feed more uniformly.

Cages Type of cages Cages consist of a fish-net bag which is open at the top, where it is hung from a floating framework. The cages may by square, rectangular or round (Figure 11). Cages are generally used in groups, either individually or linked together and anchored to the substrate. In these groups, they can be serviced and the fish fed and managed from a base facility on adjacent shore or from a proximate floating facility.

Figure 11. Square steel cages (left) or round plastic cage (right) (Photo: V.I. Gunnarsson)

The design of cages varies depending upon their use and location. Small cages are usually used in lakes but in open seas the cages are 71

very large to withstand the rigour of oceanic swells and high winddrive waves. In some instances, farmers use submersible cages especially in the Mediterranean Sea and in lakes where ice covers the surface in winter time. A submersible cage concept reduces and solves problems as rough weather conditions, icing on cages and drifting ice. Cage farming systems specially adapted for flatfish have also been developed. These systems consist of several layers of shelves on which the fish can lie.

Collar The collar maintains the shape of the cage in the horizontal plane. Shape of cage is usually round or square. The perimeter of sea cage are up to 160 meters for salmonids in Europe and even bigger for tuna farming. High density polyethylene (HDPE) cages are the most popular ones used in Europe (Figure 11). The HDPE pipes can be assembled in various ways in order to produce collars of different sizes and shapes. These cages are often composed of 2-3 rings of HDPE pipe 15-50 cm in diameter, and held together by the base of several stanchions disposed throughout the entire circumference. The rings can be either floating (filled with polystyrene) or sinkable (i.e. provided with flooding water/air hoses). Steel cages are available in a wide range of models, single- or double string systems. Steel collars are hinged to allow some wave conformation between connecting cage units. Steel collars also offer stable work platforms by providing a walkway along their sides that might be used by workers for feed and equipment storage and a stable platform to manage the farm operations (Figure 11). This is not the case for HDPE collar cages where 2-3 flotation rings are at the water surface. Many other types of cage collar are available on the market with difference in shape and material for instant polyvinyl chloride (PVC) or galvanized steel and rubber.

Main net The net hangs loose in the sea, but it is kept taut by the weight of sinkers. The main nets are usually 10-30 meters deep, but nets more 3 than 40 meters deep and more than 60.000-80.000 m are available. The main net holds the cultured stock (Figure 12a). It must resist ripping by objects and predators. The mesh is designed to prevent cultured fish from escaping. Besides holding the fish this net must also 72

permit adequate water flow through the cages to maintain water quality.

Figure 12. Simple drawing of main net in cage (a), predators nets (b), bids net (c) and dead fish collectors (d) (Drawing: V.I. Gunnarsson) A net is either stretched or an extra net is attached to rise up out of water for about a meter all-round the top of main net in order to prevent fish from jumping out. There are several types of nets for cages, but nylon nets are most popular.

Covering net Bird net is placed over top of the cages to prevent birds scavenging and preying, especially on small fish (Figure 12c). In some instances predators nets are used to keep predators (for instance seals) away from the cultured stock to reduce predation (Figure 12b). It is placed outside the main net. Jump net projects vertically out of the water around the water around the main net, preventing fish from escaping. Dead fish collector Parts of the net are also dead fish collector (figure 13d). A number of dead fish collector designs have been developed for cage farms. The dead fish collector is located in centrum of main net bottom (Chapter 4). Moorings Cages must be anchored to prevent them from drifting away. They can be arranged in three possible ways: 1. Single-point moorings 2. Several cages grouped together 3. Moored to either side of a floating walkway which reaches out from shore. 73

Several cages grouped together are most common and involves securing in one particular orientation while with the cage(s) moored from one point allowing them to move in a complete circle. Singlepoint moorings tend to be used with rigid collar designs. When several cages are grouped together the orthogonal mooring geometry is most popular.. The cages are moored onto the steel plates. The grid is moored with anchors through several orthogonal mooring lines (Figure 13). Submersible cage is moored by its framework which controls the depth of submersion. This is obtained by filling the buoyancy with water to submerge. To get the cage to rise the, buoyancy are filled with air.

Figure 13. Three-dimensional representation of a four-cage and orthogonal mooring system (Drawing: V.I. Gunnarsson)

Recirculating aquaculture systems (RAS) Advantages of RAS These are land-based systems in which water is re-used after mechanical and biological treatment. These systems present several advantages, such as: water saving, a rigorous control of water quality, high biosecurity levels and an easier control of waste production as compared to other production systems. They have however high capital and high operational costs. Recycling becomes an option when the water is expensive, limited, and needs to be heated. RAS is still a small fraction of Europeâ&#x20AC;&#x2122;s aquaculture production. The recirculation system step by step Recycling means cleaning the water and using it again in the same tank or tanks (Figure 14).


Recirculating aquaculture systems Oxygenation


Temperature and pH adjustment Biofiltration Aeration

Solids removal

Figure 14. Principle of a recirculation systems (Drawing: V.I. Gunnarsson) From the outlet of the fish tanks the water flows to mechanical filter and further on to a biofilter to decrease levels of ammonia and nitrite. The water is aerated and stripped of carbon dioxide, pure oxygen is added and treated with UV-light (or ozone disinfection) to keep the bacteria levels down. Some RAS has also automatic pH regulation and heat exchanging.

3. Equipment for handling live fish Fish transport Crowding fish Fish handling can be more problematic in large round tanks than in raceway. In a shallow raceway, staff in waders can use a crowding screen to push all of the fish to one end. It is also easier to use screen in a deep raceway than in round tanks (Figure 15).

Figure 15. Screen used to crowd fish in raceway (Photo: J. Geirsson)

Figure 16. Seine nets used to crowd fish in big tank in landbased farm in Iceland (Potho: V.I. Gunnarsson) 75

Hydraulically operated crowding fences are now being used in some larger raceway systems. Round tanks are frequently too deep to enter. Clam-shell crowders or seine nets (Figure 16) operated outside of the round tanks are most frequently used to concentrate the fish but it can be more difficult and may require more staff. In a cage, only seine nets are used to crowd fish. Fish pumps There are on the market few types of pumps; vacuum pumps, centrifungal pumps (centrifugal fish pumps), screw elevator, venturi pump and air lift pumps. Vacuum pump usually consists of an inclined tank with a separate inlet and outlet housing check valves. The tank is supplied alternately with vacuum and pressure generated by a pump. Under vacuum the exit valve closes and fish and water are drawn into the tank through a suction hose attached to the inlet. When the tank is full, the inlet valve closes and pressure is applied to the tank. The pressure causes the exit valve to open and the fish and water are forced through the discharge hose attached to the outlet. When the tank is empty the cycle is repeated. Vacuum pumps are available in both single and double chamber styles (Figure 17). The heart of centrifungal pumps is a special adjustable wheel, that controls pumping speed (Figure 17). The pump head can be positioned either directly in the tank/cage or connected to tank outlet. Screw elevators use a slowly rotating auger bonded within a cylinder to gently lift the fish in individual pools of water to the top where fish are dewatered and drop by gravity. In a venture pump, water is drawn by the primary water pump and propelled through the flow head creating a venture which creates a continuous jet suction effect. The fish suction hose is attached to the suction line of the flow head drawing fish and water into the suction hose in a smooth and continuous fashion. An air lift fish pump consisting of tube, an air spreader, and a compressor or blower. The sparger is placed on the tube near the bottom on the exit side of the tube and air is introduced into the pipe through the sparger. As the air moves towards the surface it forces water along with it creating a suction at the inlet. Fish are crowded towards the inlet and are drawn into the tube by the suction.


Vacuum fish pump

Centrifungal pumps

Figure 17. Vacuum fish pump and centrifungal pumps (Drawing: V.I. Gunnarsson and photo from manufacturer)

Fish grading Why grading? Total biomass and size variations among populations increase with time: if ignored, growth, food conversion and water quality may suffer. Most fish farmers are accustomed to grading their stock at various stage of the life cycle. Regular grading helps to avoid discrepancies in fish size and consequent bullying of smaller fish which can result in runting, i.e., poor growth induced by stress. Separation of stock into different size classes also facilitates production planning and reduces post-harvest grading. Also the market will generally pay a higher price for larger fish. The simplest method of assessing fish size is by eye; however at most intensive operations, much of the routine grading is mechanized. Grading methods Normal grading procedure either involves passive grading grids, which the smaller fish can swim through or pumping fish across a grading grid (Figure 18). Sweep net with screen are used in cage farms and underwater bar graders in land-based farms. 77

Figure 18. Fish pump and machine grader (Photo: J. Geirsson) Grading and moving of fish is stressful and time consuming. Incage grading systems grades fish are much less stressful and are for instance used in salmon industry (Figure 19). These methods of grading are not very accurate. The problem with this technique is that the smaller fish can and do move freely back and forth through the grader.

Figure 19. In-cage grading system. The screen is pushed in the direction of the arrow, fish larger than the mesh size of the screen becoming separated from the smaller fish (Drawing: V.I. Gunnarsson) 78

Many types of automatic graders are available on the market; bar graders, roller graders, belt graders and revolving graders. Machines typically consist of a hopper, into which the fish are loaded, mounted above a sloping set of bar that is designed so that the gaps between adjacent bars increase from top to bottom is common. Fish fall from hopper, slide along the bars and fall through into tanks whenever the gaps are wide enough. Roller graders look like bar graders but with the paired bars rotate in opposite directions. These graders use a pair of powered belt conveyors set at an incline to each other and adjustable at both ends. The fish are introduced to the moving belt from a hopper at the inlet end and travel along supported by the belts until the gap becomes too wide.

Figure 20. Fish pumped with impeller pumps, size grading in revolving graders and last counted in fish counter (source: Revolving graders have a number of boxes that rotate around the grader (Figure 20). As each box passes over an outlet, the opening in the bottom of the box is increased to a preselected size. The length of the grader box determines the maximum size of fish that can be graded. Revolving graders are fish friendly due to the fact that the fish are in the grader box for less than 10 seconds and in water the whole time. Mostly the fish is graded in three sizes, the smallest fish is separated out first, then the medium size, but the big fish are carried along towards the outlet of the grader. During grading, a lot of water is pumped through the grader, immersing the fish most of the time. From the grader the fish is carried through a pipeline to its destination tank or to a transport box, used for moving the fish towards the destination tank.


Fish weight and counting Fish weight and size distributions Samples of fish should be taken at regular intervals and weighed so that the growth of stock can be monitored. The information is needed to determine stocking and feeding policies and to decide time of harvesting. Information from sample weighing is stressful and inaccurate method in which fish are crowed and samples are netted, lift up or pumped and weighed.

Figure 21. The Biomass Counter in sea cage ( Simple method to weigh fish is when a known number of fish are placed in a pre-measured amount of water. The volume of water that is displaced is divided by the number of fish, and from this the average weight of each fish can be calculated. Automatic equipment for measuring length and estimation of fish weight is available as biomass counter (Figure 21). These are frames of special design, which are immersed in the tank/cage, connected to a sensory apparatus and a computer system. The fish is supposed to swim through the frame, and when it does, the sensory apparatus assesses its size and weight and the information is then processed and stored by the computer system. By keeping the frame in the cage for some time, information on the average weight and biomass is collected and the size distributions as well, as individual fish are the basis of the measurement. Information on size distribution can be extremely useful, especially at slaughtering, but also in regard of feeding practice. Fish counting It is important to know the number of fish in the beginning, or when the fish are split up between tanks/cags, e.g. at size grading. When 80

buying or selling fry, information regarding the number of fry has to be available, as usually they are sold by number. Knowing how many fish are in any particular tank/cage is vital when determining feed requirements, biomass calculations, and mortality rates. One of the main advantages of fish counters, besides the saving of labour, is that the fish is spared/not subjected to harsh treatment during the counting (Figure 21). Many fish farmers are familiar with and are still using this type of â&#x20AC;&#x2DC;Vâ&#x20AC;&#x2122; channel counter. They count fish one at a time as they pass over the infrared scanner. The data are relayed to a control unit that displays how many fish have been counted. Infrared counters are ideally suited for use with grading machines and vaccination stations where a simple numerical count is required of relatively low throughput over short time spans. Optical Sensor Counters were developed to gently count small fish and do not require the fish to be taken from the water. They are commonly used with graders and for splitting, and are easily attached to the side of a rearing tank. The fish enter the counter and are in water all the time as they pass under a bridge that houses an optical sensor. Pipe Digital Camera Counters is specifically designed for counting fish being transported in pipes. The fish pass a camera, which measures the size and speed of each fish. They can accurately count large numbers of fish being delivered rapidly from a fish pump. Line scanning video camera counters is accuracy, with high speed counting capability and ability to verify the counting data. A line scanning video camera sees each fish as it passes over the counting surface and this image is stored in a computer so that the results can be checked for accuracy at a later date. This feature can be very useful if discrepancies in the number of fish counted and the number delivered are suspected.

Other equipment a. Dead fish collector system Why remove dead fish? Disease outbreaks apart, unexplained deaths always occur at fish farms. Any dead fish should be removed, as its body will quickly rot especially in warm water. A corpse will pollute water, risking the health of other fish in the tank/cage. If it died from disease the last thing you 81

want is other fish consuming its body parts, so remove immediately. Removal of dead fish is not only a precaution against the spread of disease. Another reason is that dead fish attract undesirable animals to the vicinity of the cage farm. Seals, spiny dogfish and other animals may be attracted to dead fish and attempt to eat them. Thus leaving dead fish in the cage can increase the chances of predator attacks that can result in holes in the net. In land-based farms dead fish can also block screen in outlet with the result that water flows over tank wall edge.

Dead fish collector in cage In cage farming, removal of dead fish is done by netting out fish floating on the surface and by daily lifting of nets and removal of dead fish lying on the cage bottom. A number of dead fish collector designs have been developed for cage farms. The dead fish collector is located in centrum of main net bottom (Figure 22). A mechanical winch helps to lift dead fish collector. When dead fish collector reach sea surface at the same time center of main net bottom are lifted up and if the dead fish are remanding in the cage it runs out the side. The collector is then emptied and lowered down to main net centrum and dead fish runs again into the collector.

Figure 22. Dead fish collector on the bottom of main net in cage (a) and collector lift up to remove dead fish (b) (Drawing: V.I. Gunnarsson) In automatic system for collection of dead fish the collector-cone is located in centrum of main net bottom. A compressor delivers compressed air into the collector-cone. As the air moves towards the 82

surface forces water along with it creating a suction at the inlet and drawn dead fish and feed into the tube by the suction up into the bin on cage collar for inspection and separation.

Dead fish collector in tank Daily removal of dead fish from the bottom center drain is important. Netting dead fish especially in the bigger fish tanks with dip net is difficult for fish farmer. Some innovative ideas have been employed to make dead fish removal easier. Bottom-drain screens are normally used to prevent fish from escaping from the culture tank. To get the dead fish into the dead fish collector system, the bottom-drain screen will need to open to permit entry. A variety of mechanical, hydraulic, and pneumatic methods have been employed to open the screens. Mechanical complexity should be minimized, as anything mechanical will fail at some point, and usually when it is least convenient. Simple methods are to lift up the screen and flus out dead fish via effluent into dead fish collector (Figure 23).

Screen lift up

Figure 23. Screen in round tank lift up and dead fish flus out via effluent (Drawing: V.I. Gunnarsson)

b. Feeding technology Importance of feeding An essential element in successful farming is that fish feeding must be easy and uncomplicated. This results in fast growing, unstressed 83

fish and a good feed conversion ratio. At its core, fish farming is about converting the minimum amount of expensive fish feed into them maximum amount of quality fish flesh in the shortest possible time. The cost of feeding fish is the single biggest operating overhead and a major concern in this regard is matching the rate of feed as closely as possible to appetite so as to eliminate waste. Fish feed storage facilities Since feeds are usually delivered in bulk, most fish farmer requires a storage facility that is usually silos for single feeders or part of centralized feed distribution systems (Figure 24). Feed barges are a widespread use in sea cage farms and can hold in some cases more than 500 tonnes of feed. Many feed barges are delivered with silos, generator(s), control room, living quarters, safety equipment and all other optional equipment installed, such camera- and sensor systems. The have centralized feed distribution systems that deliver food directly to the cages.

Figure 24. Land-based fish feed storage silos in centralized feed distribution systems for sea cage farms (left). Single feeder on sea cage (right) (Photo: V.I. Gunnarsson)

Feed delivery methods Feeding can be done with hand or by one of three types of feeders: ď&#x201A;ˇ Automatic feeders, sometimes referred to as fixed feed ration systems ď&#x201A;ˇ Demand feeders triggered by the fish themselves ď&#x201A;ˇ Feedback-based feeding systems 84

Automatic feeders There are a large number of automated feeders available on the market and most of these feeding systems are volume-based – that is feed is measured in volume rather than weight. Automatic feeders can be classified according to their energy supply as being electric and pneumatic feeders. Electrically operated automatic feeders consist of three main designs (Figure 25):  Revolving plate placed under the container moves slowly and the feed falls directly down into the water.  A horizontal shaft screw and belt is used for discharging and portioning the feed into the fish tank.  Revolving plate rotates quickly, the feed is spread over a large surface of the water.

Figure 25. Automatic feeder with revolving plate (A), horizontal belt (B) and revolving plate rotates (C). (Drawing: V.I. Gunnarsson) The electric automatic feeders are controlled by a timer with which the length of the feeding time and the time interval between two feedings can be adjusted. A single control unit can be used for one individual feeder or a central control unit can operate more feeders. Pneumatic-type automatic feeders shoot the feed by means of compressed air, spreading it over the water surface (Figure 26). The mechanism that releases the feed is based on a screw that is turned a given numbers of turns (or for a set period of time) to dosage a certain amount of feed. The amount of feed is released during a given period of time/turns of the screw is weighted and this information is entered into computer-based steering system. The center steering computer then uses this information to adjust feeding based on the feeding protocol programmed in for that particular facility. Selectors are used to select cages/tanks and when air is released from air chamber, pellets in the delivery pipe are blown out into cages. In some 85

instances rotor spreader is used to spread feed over larger surface area in tanks/cage. Dosers

Inter coolers Selectors

Feed pipes to cages


Figure 26. A simple drawing of pneumatic-type automatic feeders systems ( Demand feeders Demand feeders are activated by fish within tank/pond (Figure 27).

Figure 27. Simple demand feeder (Drawing: V.I. Gunnarsson) A trigger mechanism mounted on a thin wire is located in the water below a feed hopper. The fish knock or bite the trigger wich is connected to a feeder and a supply of feed drops from the feed hopper into the tank. While a number of fish are known to be able to learn how to operate demand feeder and this type of feeder are for instance used in rainbow trout farms in Europe. 86

Feedback-based feeding systems Here the feeding system automatically registers pellets that are not eaten with the help of funnel that is suspended under the water surface (Figure 28). One version feedback-based feeding system is a hose leads from funnel up to unit that registers the numbers of pellets that accumulate.

Figure 28. Feedback-based feeding systems in sea cage with funnel to accumulated feed and counting units (Drawing: V.I. Gunnarsson) The system works in the following way: ď&#x201A;ˇ Fish are provided with a meal. ď&#x201A;ˇ If some of the pellets are not consumed they will sink and accumulate in the funnel and be pumped up to the counting unit, where the pellets are optically registered. ď&#x201A;ˇ If no feed is returned from the funnel to the counting unit the system automatically releases a new dose of feed and continues to do so until excess pellets once again are registered.

c. Appetite monitoring systems Submerged camera There are many systems available for monitoring the amount of feed that fish consume and the most popular is submerged camera. In a cage farm the camera is located beneath the feed delivery outlet allowingthe operator to observe feeding behavior and feed wastage via a boat or barge-mounted monitor (Figure 29). The disadvantages of using the camera systems is that proper application requires a high 87

level of operator diligence and a reasonable level of visibility in the water column.

Figure 29. The monitoring amount of feed that fish consume with submerged camera in sea cage (Drawing: V.I. Gunnarsson and photo from manufacturer) Other appetite monitoring systems for sea cage The feed pellet counting systems reduce the need for operator diligence by automatically counting uneaten feed pellets and adjusting the feeding rate accordingly (figure 29). A potential drawback with funnel-based systems is that they can be clumsy and difficult to deploy and operate in exposed conditions for cage farms. This technology is today still not widely used. Appetite monitoring systems for land-based farms In land-based farms there it is simple to place a screen over the tank outflow pipe to collect uneaten feed or use collector for instant external swirl separator. There are commercial system using an ultrasound probe placed in the effluent pipe that detects uneaten food without confusing it with fish faeces. The probe is connected to a controller that automatically turns off feeders after a predetermined amount of uneaten feed has passed the sensor. This technology is today still not widely used. The disadvantage of controlling feed waste in tank effluent is response time and overfeeding may occurr at some time before feeding is stopped. It is more convenient to place it beneath the feed delivery outlet in the tank. 88

d. Equipment for cleaning Sea cage In cage farms nets can be fouled with marine growth; seaweeds, hydroids, mussels etc. The ensuing clogging of the meshes impedes the passage of water through the cage and this reduction in water exchange can result in depleted oxygen level. If this situation remains unchecked, the fish can become so stressed that growth decreases and mortalities can occur. Heavy fouling can also increase currentinduced forces on all submerged equipment, potentially resulting gear failure, because of overloading. As to eliminate fouling, nets must be cleaned on regular basis. The process is accomplished by washing, drying and proofing with copper containing substances on land. While on land, nets are also inspected for defects and repaired. In some cage farms net cleaning is also undertaken in the water. Cleaning is carried out either by divers or by personnel who work with specialized equipment from walkway at the edge of cages. In net cleaning, filtered high pressure sea water is used to remove marine fouling on the nets. A net cleaner uses rotating cleaning discs monted on cleaning rigs in various shapes and combinations. Highpressure washers are used to drive the cleaning discs. The cleaning process starts with submerging the rig on the inside of the net, using only sea water under high pressure (Figure 30).

Figure 30. Net cleaning rings on the top of high pressure washers (Photo: V.I. Gunnarsson) ROVs (remotely operated vehicles) are being developed for cleaning of nets. ROV are vacuum cleaning system that reduces cleaning times, single person remote-controlled machine that crawls 89

all over the sides and base of your nets, removing the fouling and discharging it away from the net. Land-based farms Fish tanks are usually not cleaned until they are emptied of water. On regular basis standpipes are lift up and solids flushed out via fish tank effluent. When emptied the tanks are cleaned with brush and/or high pressure pump. In some instances especially raceways are cleaned when in operation with vacuum to remove feces and uneaten feed.

References and further information Aquafarmer: Beveridge, M.C.M. 2004. Cage aquaculture. Blackwell Publishing. 368 p. Heldbo, J. (ed.) 2013. Bat for fiskeopdræt i norden. Beste tilgængelige teknologier fora Akvakultur i Norden (englis abstract). TemaNord 2013:529. 406 p. ( Lekang, O.-I. 2013. Aquaculture Engineering. Willey-Blackwell.415 p. Lucas, J.S. & Southgate, P. C. (eds.) 2012. Aquaculture: Farming Aquatic Animals and Plants. Wiley – Blackwell. Pillay, T.V.R. (ed.) 1984. Inland aquaculture engineering. - Lectures presented at the ADCP Inter-regional Training Course in Inland Aquaculture Engineering, Budapest, 6 June-3 September 1983. ADCP/REP/84/21. FAO, Rome, 591 p. ( Summerfelt, S.T., Timmons, M.B. & Watten, B.J. 2000a. Tank and raceway culture. pp. 921-928. In, Stickney, R.R. (eds.) Encyclopedia of aquaculture. John Wiley & Sons Inc. Summerfelt, S.T., Davidson, J., Wilson, G. &Waldrop, T. 2009. Advances in fish harvest technologies for circular tanks. Aquacultural Engineering 40: 6271. Timmons, M.B., Summerfels, S.T. & Vinci, B.J. 1998. Review of circular tank technology and management. Aquacultural Engineering 18: 51–69. ( _and_management.pdf). Timmons, M.B. & Ebeling, J.M. 2007. Recirculation Aquaculture. Cayuga Aqua Ventures, LLC. 975 p. Timmons, M.B. & Ebeling, J.M. Culture tank design: 20%20&%20Misc%20Papers%20Adobe%202006/4%20Culture%20Tank%20 Design/Culture%20Tank%20Design.pdf Further information – Website Simple Methods for Aquaculture: Nuts & Bolts - The PR Aqua Team contributes articles to Hatchery International Magazine: Further information – Video AQUATOUR:


V. Brood Stock and Larval Stage Management Authors: Valdimar Ingi Gunnarsson, Sigurรฐur Mรกr Einarsson

Work in the hatchery includes the choosing of suitable broodfish, stripping and fertilization, incubation of eggs and rearing of fry. There is also a great structural difference regarding hatchery work on freshwater fishes like salmonids and marine fishes. Furthermore there are great differences in the biology and life cycle of marine fishes and freshwater fishes (salmonids) (Table 1). To represent salmonids, we use Atlantic salmon as a model fish, which has similar culture methods and rainbow trout, brown trout and charr. For marine fish the European sea bass is used as a model fish and the culture methods are similar to sea bream and Atlantic cod. Sea bass is a highly prized fish species in the Mediterranean and the south European Atlantic seas, and is considered a delicacy in many of the southern European countries. Table 1. Difference between marine fish and salmonids for hatchery operation Spawning Egg diameter Egg properties Size of larvae at hatching Start feeding

EeEuropean sea bass Free spawning in tank 1.2 - 1.4 mm Semi-buoyant eggs 4.0 mm

Atlantic salmon Hand stripping 5.0 - 6.0 mm Non-buoyant eggs 15.0 - 25.0 mm

Live feed

Dry feed

The main farming areas of Atlantic salmon are in North Europe, especially in Norway. Salmon farming has become a large industry with exports to all major countries around the world.

1. Freshwater fish a. Broodstock Broodstock management In many cases, the broodstock is kept in tanks in land-based farms with a possibility to control heat, salinity and light (Figure 1). Sexual 91

maturity in salmon is controlled by light exposure and fish start to mature when they reach a minimum size, usually greater than 8-10 kg. Once salmon reach critical size and have been through a period of short day length (winter), they are exposed to an increase in day length, inducing gonad maturation. Some fish farms manipulate the light exposure with the aim to induce spawning several times a year.

Figure 1. The Stofnfiskur fish farm, largest producer of eyed salmon eggs in Iceland (Photo: V.I.Gunnarsson).

Selective breeding Genetically selected stocks will play an important role in development and ensure the best use of the environment and at the same time improve production cost-efficiency. Within the salmon farming business, broodfish are selected based on a specific set of criteria (Figure 2). The most important criteria for broodfish selection include:  Faster growth  Later sexual maturity  Higher resistance to diseases (higher survival)  Good feed utilization  Better flesh quality (lower fat-content, colour, texture etc.) Sexual maturity Fish alter appearance as they begin to reach sexual maturity, with changes in both skin and flesh colour. In salmon, pigment from the flesh is transferred to colour both skin and roe. Changes in head and jaw shape occur, particularly in the lower jaw of the males, which forms a characteristic hook. Mature fish show a decreased appetite and become more aggressive and territorial. 92

Figure 2. A production circle takes 12-18 months from fertilization of Atlantic salmon eggs to smolt (Photo from different sources from internet) Stripping When fish are mature, they can be stripped of eggs and sperm (milt) (Figure 3). Stripping should be done in a room maintained at 210°C. The ideal temperature is the same as the water from which fish is taken, in order to prevent temperature shock to the gametes. Direct sunlight should be avoided; gametes are susceptible to damage from strong light. For optimal results the fish must be stripped at the right time. This requires the individual fish to be followed closely to monitor when they become mature. The egg should flow easily and continuously out of the female, without the use of excessive force. If stripping of eggs occurs too late, the overripe eggs pigments become unevenly distributed and eggs loose the uniform yellow/orange color characteristic of perfectly ripe roe. Prior to stripping the fish must be anesthetized. Itâ&#x20AC;&#x2122;s imperative that the fish is washed thoroughly with clean water after anesthesia and before stripping in order to ensure that no anesthetic residue contaminates the stripped eggs or sperm. The first squirt of sperm from male should be discarded, as it may contain residual anesthetic. Three to five ml of dry sperm per liter egg is sufficient and 2-4 males are used in fertilization eggs from one female. This is to ensure that 93

there is sufficient sperm of high quality. Thick and white sperm is preferred rather than watery sperm which is often of poor quality.

Figure 3. Stripping, fertilization and swelling of Atlantic salmon eggs Fertilization The female produces around 1,000-2,000 eggs per kg of body weight. After stripping, eggs and sperm should be gently mixed without adding water and left for about 2-3 minutes in order to let them be fertilized. When the eggs are fertilized a little fresh water should be added to the eggs. The addition of water activates the sperm and helps to fertilize any remaining unfertilized eggs. Rinsing and swelling After fertilization, the eggs can be rinsed by carefully adding water. The eggs are gently stirred and the water poured in order to remove excess sperm and ovarian fluid. Great care must be taken when washing the eggs, as they are extremely delicate at this stage. Eggs should sit undisturbed until swelling has occurred. Swelling takes 2-3 hours depending on temperature and increase up to 40% in size. When swelling is complete, the eggs are once again robust enough to tolerate careful handling.

b. Egg storage and hatching equipment Incubation systems Several incubation systems have been developed for farming of salmonids and it is possible to divide them into three different systems (Figure 4): 94

ď&#x201A;§ ď&#x201A;§ ď&#x201A;§

A system where the eggs remain in the same unit for the whole process up to fry ready for first feeding. A system where the eggs lie in thick layers and must be moved before hatching. A system where storage, hatching and first feeding is carried out in the same unit.

Figure 4. Egg storage and hatching equipment (Photo from manufacturers).

Hatching troughs A common unit is the hatching trough with trays inside (Figure 5). The trays have a perforated bottom and one of sidewalls is also perforated. Water is supplied at one end of the trough and flows out from the opposite end. A level outlet controls the water level in the trough. Inside the trough the tray is installed so that undercurrent of water is forced to flow up through the perforated bottom, through the layers of eggs lying in the tray and then out through the perforated side of the tray.

Figure 5. Hatching trough with trays inside (Drawing: V.I. Gunnarsson) 95

Artificial substrate Artificial substrate can be placed in the bottom of the trays to improve the results (Figure 6). When hatching occurs the yolk sac fry (alevins) will move down through the perforations. The substrate creates small spaces where the yolk sac fry can stay in an upright position. In this way yolk sac fry save energy and use it for growth.

Figure 6. Artificial substrate (Photo from manufacturers)

Hatching cabinet In the hatching cabinet the eggs are placed in drawers or on racks on top of each other (Figure 4). There are two different designs of hatching cabinet: 1. Either water droplets fall from the top. 2. Or there is an individual water inlet and outlet in each drawer. Each drawer has a perforated bottom where the water flows up through the layers of eggs. This system maximizes the space utilization in relation to hatching trough and tray, but is more difficult to control. Eggs must be removed before hatching in this system. Cylinder The most commonly used incubation system for rearing large numbers of eggs is the hatching cylinder (Figure 7). The eggs must however be transferred to other units before hatching when this type of incubator is used. Water is taken in at the bottom and a distribution plate ensures that it is distributed evenly trough the layers of eggs via an underflow. The water will then flow up through the layers of eggs and over top edge of cylinder to the outlet.


Figure 7. Cylinder to storage salmonids eggs (Drawing: V.I. Gunnarsson) Combi-tank These systems consists of specialized hatching trays that are inserted into tanks where fry will later be held for start- feeding. On the market a combi-tank is also available that is a complete “hatchery system” designed for hatching eggs, first feeding fry and rearing larger fry. The system is comprised of an egg tray, first feeder tanks, and a main tank (Figure 4). When the eggs hatch, the sac-fry move by gravity through the slotted screen of the egg tray into the first feeder tank below. When the fry start eating, they can be moved into the main tank.

c. Eggs incubation Incubation – Eggs development’s The age of fertilized eggs and fish is calculated in degree days, by multiplying the age of salmon roe in days by the average temperature during the same time period. Eying of eggs occurs after approximately 250 degree days and hatching after 500 degree days. The eggs start to develop immediately after fertilization. The eggs are pink or orange in colour and the embryo is clearly visible inside the egg. An eyed egg means that one can see clearly the eyes of the embryo. The embryo develops quickly and will hatch out of the egg – as an alevin.


Figure 8. Hatching troughs in small hatchery room (Photo: V.I.Gunnarsson)

Environmental conditions Regardless of the storage methods used, the water requirements for eggs are a minimum 0.5 liter/minutes per liter of eggs. The flow may have to be increased by a factor of three at hatching and during the alevin stage. Incubation temperatures between 4째C and 8째C to the eyed stage give the lowest mortalities. Temperature should not exceed 8-10째C and maintained as stable as possible, avoiding all sudden fluctuations. Eggs and alevins should be incubated in total darkness mimicking conditions in the wild where they are buried in gravel. Ideally individual batches should be covered in a dimly lit hatchery and only illuminated when it is necessary to inspect them. Prolonged exposure to light particularly ultra-violet radiation is harmful. Eyed-egg stage Eggs that have reached this stage are now more robust and can better tolerate rough treatment such as sorting and transport. This is the stage at eggs are usually shocked. The eggs are agitated by pouring them from one bucket into another filled with water from a height of 30-40 cm (Figure 9). This mechanical stress causes the yolk in these blank eggs to coagulate and turn white. Using this technique we can more easily sort out most of the unfertilized egg before they are transferred to hatchery systems. 98

Removal of dead eggs During the first fragile period of eggs the only prevention against saprolegnia is the use of formalin or other chemical. Since saprolegnia develops on dead and decaying eggs and can spread to healthy ones, it is very important to remove damaged and dead eggs as soon as they can be touched, regardless if they are infected with saprolegnia or not. The dead eggs can be removed by manual picking with a suction pipette or egg- picking machine (Figure 9). Sorting and counting eggs There are several types of machines that are capable of sorting out the dead (white) eggs (Figure 9). Many of these rely on photo-optic systems and many also simultaneously count the eggs. The machines are useful after the eggs have reached the eyed stage and have become more robust. Older methods to count eggs are count number of eggs that are placed one after the other in a distance of 25 cm. On can then refer to a table and estimate the number of eggs per liter.

Figure 9. Eggs shocked and manual picking or machine used to sorting out white dead eggs (Photo from different sources from internet).

d. Alevins and first feeding Alvins requirements Newly-hatched fish are called alevins or yolk-sac fry, since they still have a nutrient-rich yolk sac attached to their bodies which they feed from until they can search for food. The orange yolk sac contains a completely balanced diet, a small lunchbox full of goodies. Because they neither can swim very easily nor take food, alevins are provided with matting or stony substrates to mimic the natural gravel redd, and 99

are usually maintained in darkened conditions. To give them the sheltered conditions needed in culture, the bottom of the alevin trays are lined with artificial substrate. Environmental conditions During the period following hatching, temperature should be maintained at 8-10째C and gradually increased to 12째C as fry approach the primary feeding stage. Light levels are critical and should be low, certainly less than 50 lux at the water surface. The pattern should be diffuse with no shadows or bright spots. For as long as the lights are on, the fry remain properly distributed over the floor of the first feeding tank. Alevins require only shallow water and water depth can maintained quite low, in order to facilitate daily care of the alevins. At the beginning, depth of water may be 0.2 meters which gradually can be increased to 0.5-0.8 meters or more.

Figure 10. Methods to sorting live alvins from dead eggs and alvins (Photo: V.I.Gunnarsson). Fish density in tanks for first feeding is calculated in units of surface area as the fry lie on the bottom of the tank and require a 2 sufficient amount of space. The rule of thumb is 10,000 fry/m in first feeding stage. When fish are past the first-feeding stage, fish density 3 is measured in m . 100

First feeding First feeding begins approximately 240-300 days after hatching, at 8°C. As alevins advance in development their yolk-sack is gradually consumed and they start to feed externally. Once all the yolk has been consumed, the alevins has become a fry. They also start to move until finally they swim up to the water surface and gulp air from the atmosphere. A swim-up fry refers to those that have absorbed nearly all of their yolk, have become buoyant and are ready to consume food. At this point, the young fry are transferred to larger tanks as the time for first-feeding approaches. Placing artificial substrate on tank bottoms provides a safe place for fry to hide (Figure 11). Figure 11. First-feeding tank with artificial substrate (Photo: V.I.Gunnarsson)

Fry remain on the bottom of the tank as long as they possess a yolk sac. Only when the fry start to actively swimming in the water column above the bottom, the resources in the yolk sac are nearly gone and fry is ready for first feeding. First feeding is a very critical period for the fryâ&#x20AC;&#x2122;s development and the farmer will feed by hand, small quantities at regular intervals, and keep a close watchful eye on them. As the fry begin to utilize the whole tank for swimming the artificial substrate can gradually be removed.


e. On-growing Feed The taste, size, shape, colour, dust content and sinking speed of fish feed, as well as the time it takes before feed loses these qualities in water, are all items that will affect fish welfare and growth. The first feed given, consists of very small pellets or crumbs but their size will increase gradually, adapting to the size of the mouth and the throat (oesophagus). Up to four different feed sizes will be used before the bodyweight of 5 grams is reached. The feed must also be free of dust. One reason for this is that the fish cannot eat small dust particles and dust is thus a waste of good nutrients. Another even more important reason is that dust particles can directly irritate the gills, either by physical irritation or acting as a support for bacterial growth, increasing the risk of infection. Feeding The amount of feed given to fish is expressed as a percentage of their weight. The daily feeding percentage of the body weight of small fish can be up to 7 or 8% but the specific amount of feed required depends on the actual size of the fish and the water temperature - the smaller the fish and the higher the temperature means that the farmer will give a larger amount of feed as a percentage as opposed to a larger fish in cold water.

Figure 12. Small raceways used for first feeding and on-growing of parr (Photo: V.I.Gunnarsson).


Keep in mind than smaller fish have a small stomach and a short intestine for feed digestion; they have to be fed very regularly – several times a day. Regardless of type of feeder used it should provide the correct amount of feed at the correct time, and feed should be well distributed to allow all fish in tank to feed. When changing feed type there should be a transition period when the fish are gradually introduced to the new feed by mixing it with the feed type that is being replaced. Fish density and growth phase It is difficult to set an exact limit for maximum density for fish held 3 in tanks, but generally densities are up to upper limit of 60-80 kg/m . Sorting starts when fish has reached few grams in weight. Sorting is very stressful to fish but starving fish prior to sorting (1-2 days depending of size) will help to reduce the stress. Most important to keep in mind during the rapid-growth phage:  Oxygen level greater than 80%.  Check numbers, mean weight, biomass and fish density in the tanks.  Optimal feeding strategy for fish in relation to size, biomass and temperature.  Optimal size of fish feed.  Optimal current patterns and water circulation in tanks, adapted to fish size and self-cleaning of tanks.  Sorting at the appropriate time.  Sanitation and water quality.  Light regime.

Smoltification Smoltification is a process in which fish in freshwater undergo a number of morphological, physiological and behavioral changes that enable them to migrate to and then survive and grow in marine conditions. These changes include:  Obscured lateral parr marks.  Darkened fin margins.  Silvering and easy removal of scales.  Decline in condition index.  A preference to swim with rather than against the current.  Tolerance of high salinities.


Figure 13. Cleaning and dead fry removed out of tanks (Photo: V.I. Gunnarsson)

Light regime Continuous lights are often used in the hatchery until the fish reach 8-10 cm in length. Light is also important in the smoltification process. Salmon smolts must reach a critical size of 25-30 g before they are capable of transforming into smolt. At this point the fish must experience a period of summer (long day length) followed by winter period (short days) again following by a period of long days. A common regime used on smolt farms is the following:  Salmon parr are exposed to a 6 week period of long days (for example 16 h light, 8 h dark).  Following 6 weeks of short day (8h light, 16h dark) allowing fish to experience artificial autumn and winter light regimes.  At the end fish are exposed to a second 6 weeks period of long days (similar to the first) that mimics spring. This will trigger smoltification in fish that are physiologically ready when the artificial light treatment began. Under farming conditions smoltification occurs at the size 50-100 g. 104

Smolt production In Norway the broodfish are stripped for eggs in the autumn. The producer has the possibility to speed up the growth of the juveniles with light manipulation to accelerate the smoltification process by up to 6 months. The light manipulated juveniles are called S0’s and the normal grown juveniles are called S1’s. In Norway, smolt is mainly released into seawater twice a year. S0’s are released in autumn/spring within 12 months after ova inlay, and S1’s about 18 months after ova inlay. A very small part of the production is produced as S1½, which are only put to sea 2 years after the ova inlay. Weights of smolt in Norway are commonly 60-100 grams when transported to sea cage for on-growing to market size.

2. Marine fish a. Broodstock management Broodstock Domestication of the European sea bass was initiated in the mid 1980’s by some pioneering companies and some strains are now kept in captivity and fish has been selected for a few generations. However, some hatcheries are still using wild broodstocks. Sea bass culture would undoubtedly benefit from selective breeding for productivity traits. As in almost every farmed species, growth is the first trait for which selection is desired. This is particularly critical for the sea bass, as its growth rate is slow: it is not exceptional to need 24 months from hatching to produce a commercial size (400 g) sea bass. In captivity, first sexual maturation occurs in 1-2 years in males and in 3-5 years in females. Females are 10 to 40 % larger than males. The optimal age for female parent fish is between 5 and 8 years, whereas for males this range is lowered to 2-4 years. Fecundity and egg quality improve after first spawning. Photo and thermal cues control reproduction in sea bass. The fish respond to the shortened length of the day and to a reduction in water temperature, the latter being critical for egg quality. Optimal temperature for broodstock is 13-15 °C in the spawning season which helps in obtaining maximum quality eggs.


Figure 14. A production circle takes 4-5 months from fertilization of European sea bass eggs to 2-5 g fingerlings (Photo from different sources from internet).

Spawning In the wild the females spawn in the winter in the Mediterranean Sea (December to March) and up to June in the Atlantic Ocean. They present a high fecundity (on average 200,000 eggs / kg of female). In the hatchery the eggs are produced all year around using suitable temperature and photoperiod. Sea bass spawn naturally in tanks and buoyant eggs are collected at the water outlet of the spawning tanks. Eggs and sperm can also be collected by a gentle pressure on the flanks of anaesthetized fish. At the onset of the spawning season it is necessary to move selected batches of breeders from their long term holding facilities to the spawning tanks, where they can be better treated and their performance can be easily monitored. The male:female ratio in the spawning tanks is kept at 2:1. Whereas males are chosen when they release sperm spontaneously or on stripping, the female maturation stage has to be ascertained by extracting oocytes from the ovary with the use of a catheter: only females with oocytes in the late-vitellogenic stage, i.e. with a diameter larger than 650 Âľm are selected. If spontaneous reproduction does not occur in sea bass, then hormone treatment either by injection, controlled-release implants or 106

microcapsules can be used to trigger maturation, with ovulation and spawning in 54-68 hour. The hormonal treatment is intended to trigger the last phases in egg maturation, if eggs have reached the latevitellogenic (or post-vitellogenic) stage. Out of season spawning The strong influence of photoperiod on sea bass reproduction makes this fish a candidate for extending its reproductive season throughout the year. Providing groups of parent stock sea bass with artificial lighting that mimics changes in the length of the day and that shifts the shortest day, coupled with reduced water temperature allows year-round spawning. The broodstock is for instance divided to four groups including both males and females: three groups are exposed to environmental regimes that are shifted by 3, 6 and 9 months respectively compared to the natural environmental regime, which is left for the fourth group. In this way, the hatchery will have a group of fish ready to spawn on each season: in winter the parent fish exposed to natural environmental conditions, in spring, summer and autumn the other three groups. Shifting should start when fish are still in the resting phase of their sexual cycle. If breeders are properly managed, eggs produced out of season with shifted cycles do not differ significantly in quality and quantity from the in-season eggs.

b. Eggs incubation Egg collectors Eggs are collected with automatic egg collectors. The overflow collector is placed outside the spawning tank (Figure 15). It consists of a screened container that receives the water of the spawning tank by overflow and is placed inside another container. The airlift collector is a device placed inside the spawning tank. It is basically a screened box or bucket equipped with floaters and small airlifts. These airlifts are PVC pipes that transfer the surface water of the spawning tank into the collector by means of an air flow.


Figure 15. The overflow egg collector is placed outside the spawning tank (Photo: V.I. Gunnarsson). Egg harvest If egg collectors are well dimensioned and properly placed, these devices harvest only the floating eggs, while the dead or unfertilized ones sink to the bottom. A few important precautions should be taken into consideration. ď&#x201A;§ The presence of eggs in the collectors should be checked rather frequently, as its spawning produces a large amount of eggs in a very short time and there is risk of clogging the collectors or of mechanical stress to the eggs. ď&#x201A;§ Due to the waste produced by spawners in their tanks, egg collectors have to be kept properly cleaned and should be replaced at least daily with sterilized ones. ď&#x201A;§ The water flow should be adjusted to gently transfer eggs from the spawning tank into the egg collector without harmful mechanical shocks. To remove the eggs from both types of collectors, the aeration and water flow have to be stopped. Viable eggs are allowed to float freely in still water. In this way a first separation between sinking dead eggs and viable ones takes place. To minimize the presence of poor-quality eggs, which usually float deeper in the water, it is advisable to collect only the eggs floating at the water surface. Quality control and stocking eggs A reliable egg control quality needs usually just a few dozens of eggs, which are placed under a microscope or a transmitted-light 108

stereomicroscope. With a pipette they should be taken from the floating egg layer in the temporary container, and should be placed on a watch-glass or on a Petri dish, making sure that the eggs form a single layer. As a general rule, good egg batches have usually less than 10% abnormal eggs. Any batch containing more than 20% abnormal eggs should be discarded. Prior to stocking eggs, either into the hatching facilities or directly into the larval rearing tanks, three more steps are required: weighing, estimation of their quantity and disinfection. Egg incubator The eggs are spherical with a diameter range of 1.1 - 1.25 mm. The traditional shape of an incubator for storage and a hatching of pelagic eggs is a cylinder with a conical bottom (Figure 16). With this shape it is easier to achieve a good flow pattern in the unit. Having a conical bottom makes it possible to remove the dead eggs easily by trapping them out through an outlet in the bottom of the cone. In practice, several methods are used: for instance, stopping the water flow or adding a plug with higher salinity and thereafter stopping the water flow. In both systems, dead eggs will sink to the bottom, while live eggs will remain in suspension due to their greater buoyancy.

Figure 16. Cylinder with a conical bottom for pelagic eggs (Drawing: V.I. Gunnarsson) 109

Incubation of eggs Incubation temperatures are between 14°C and 15°C. Fertilized eggs float in water with 35 to 37 ppt salinity. With lower salinity egg buoyancy decreases and a strong aeration is advisable to prevent their sinking to the bottom, which would pose a big risk in terms of physical stress and bacteriological contamination. Hatching starts approximately 72 hours after spawning at 13 - 14 °C. After hatching, only the hatched larvae are moved to the clean larval tanks.

c. Larval rearing Larva The newly hatched larva is microscopic, being only 4 mm long, and has a yolk sac almost half its size. The yolk contains a range of nutritive reserves that are contained within the yolk sac, which is an integral part of the young larva. Until the sac is fully absorbed, they fish are known as yolk-sac larvae. Before being stocked in the larval rearing tanks, the newly hatched larvae are checked to assess their viability and condition. The larval motion is a sort of passive floating with sudden and infrequent body movements without assuming any clear posture. Typically they sink slowly, head first, and then, every few seconds, swim upwards for two to three seconds. Larva development and feed As the larva grows, the eyes, teeth and stomach develop so that the larva can start to feed itself only 6 days after hatching. In the hatchery, young fish are fed on algae and microscopic zooplankton called rotifers until they can eat Artemia. Rotifers are maintained at a certain density in the ‘first feeding’ tanks, so that food is available to the fish at all times. As the young fish grow larger, the rotifers are replaced with live brine shrimp (Artemia). Larval culture covers the entire larval development stages starting with the newly hatched larvae and ending with metamorphosis. The latter starts on day 30 post hatch and completed on days 40-45.


Culture conditions Larvae are very sensitive and it is very important to control environmental conditions:  Temperature is kept at 15-16°C in the prelarval period and slowly increased (0.5°C/day) to reach 17°C at the stage of complete swimbladder inflation. Afterward it is increased to 1920°C.  Usually the same salinity as at spawning (35-38 ppt). Salinity is th th reduced to 25-26 ppt between 4 and 17 days to enhance survival rate.  Low levels of light intensity (20 lux) are used at the beginning of feeding period. It’s kept under 100 lux by day 13 and increased to 500 at day 17.  Photoperiod is 8 hour light at the beginning, and then it is increased to 16 hour light at day 17.  The skimmers used to clean the water surface allow the larvae to inflate the swimbladder and are used at least three times a day from day 4 to day 17 (Figure 17).  Initial stocking density larval unit: 200 hatched larvae per liter.

Figure 17. The skimmers used to clean the water surface allow the larvae to inflate the swimbladder (Photo: V.I.Gunnarsson). Feeding protocol Feeding of postlarvae may be started with Artemia nauplii. However, because Artemia nauplii are very expensive, some hatchery uses rotifers as the initial food. 111

Under farming conditions, following the mouth opening (days 3 to 5 post-hatch), the larvae are fed live prey such as rotifers with or without algae, and Artemia, which are also normally enriched using different enrichment media before weaning onto formulated commercial feeds (Figure 18). The feeds distributed at this stage are extremely small particles, corresponding to the mouth opening: 50–250 μm for larvae of 8–10 mm, 180–400 μm for larvae of 20 mm and 315–600 μm for juveniles of 25 mm.

Figure 18. The rough scheme for production of larvae; feed and time for feeding different diet (Photo from difference sources from internet). Efforts over the years have been towards reducing some sequences, such as feeding rotifers and reducing the duration of total feeding with live prey through co-feeding or weaning to dry particulate feeds at an early date. It is not uncommon these days to have the whole sequence reduced to less than 40 days instead of more than two months, which was prevailing earlier. The proximate/nutrient composition of live prey can vary considerably, and both rotifers and Artemia are enriched with different enrichment media to improve their nutritional values.

d. Weaning Juveniles Metamorphosed fish (40-45 mg, around 45 days old) are transferred to a weaning sector. At this stage they are named 112

fingerlings or juveniles and must have assumed the adult aspect. The young fish are gently weaned off live feed and onto specially formulated commercial fish food of a very fine particle size (Figure 19).

Figure 19. Larval rearing units (Photo: V.I.Gunnarsson) Rearing parameters After metamorphosis fish are more tolerant to small environmental variations than post- larval, but the rearing parameters in the weaning/nursery sector still require close monitoring:  Initial stocking density in the weaning unit is 20 fry per liter.  The temperature is kept within 18-22°C.  Better feed conversion and survival rates can be achieved by using slightly brackish water at 20-25 ppt salinity.  Photoperiod should be shortened by two hours in relation to the larval sector, i.e. 14 hours light and 10 hours dark. At 80-90 days of age the natural photoperiod can be set. Feeding Feeding procedures in the weaning section differs from those of the larval rearing unit. Main changes are the end of the live feed supply and the setting up of truly intensive rearing system based on automatic distribution of dry food. Strictly speaking, weaning commences during the larval rearing. The young fish actually receive the first feeding with inert feed at the very early age, but it is much later, after the transfer into the weaning sector, that dry compounded feed become their only nutritional source. 113

Growth characteristics In the hatcheries, growth of larvae can vary considerably depending upon hatchery practices as well as upon the time of weaning onto compound feeds. The time normally required to produce 2 g fry starting from viable larvae, at a water temperature of 18 to 20째C is about four months. Transfer When a size of 2 to 5 g is reached, weaned fry leave the hatchery to be stocked in the fattening facilities, either pre-growing tanks or floating cages. The transport within the farm where the hatchery is located is very short and does not require any special equipment. Transport becomes a more complicated matter when fish are sold or when the on-growing facilities of the farm are far from the hatchery. Due to the vigorous handling to which fish are subjected while being loaded into the transport containers, they become hyperactive and increase their respiration rate and metabolic excretion. To minimize oxygen consumption and ammonia production, as well as to decrease the amount of faeces and regurgitated food in the transport container, fry are usually starved at least 24 hour prior to shipping.

Figure 20. Counting marine fish larvae (Photo: V.I. Gunnarsson).


References and further information Büke, E. 2002. Sea bass (Dicentrarchus labrax L., 1781) seed production. Turkish Journal of Fisheries and Aquatic Sciences 2: 61-70. ( Haffray P., Tsigenopoulos C. S., Bonhomme F., Chatain B., Magoulas A., Rye M., Triantafyllidis A. and Triantaphyllidis C. 2006. European sea bass Dicentrarchus labrax. In: “Genetic effects of domestication, culture and breeding of fish and shellfish, and their impacts on wild populations.” D. Crosetti, S. Lapègue, I. Olesen, T. Svaasand (eds). GENIMPACT project: Evaluation of genetic impact of aquaculture activities on native populations. A European network. WP1 workshop “Genetics of domestication, breeding and enhancement of performance of fish and shellfish”, Viterbo, Italy, 12-17th June, 2006, 6 pp. ( n). Hoitsy, G., Woynarovich, A. and Moth-Poulsen, T. 2012. Guide to the small scale artificial propagation of trout. The FAO Regional Office for Europe and Central Asia. ( ut/propagation_en.pdf). Leitritz, E. and Lewis, R.C. 1976. Trout and Salmon Culture (Hatchery Methods). Fish Bulletin 164. ( Lekang, O.-I. 2013. Aquaculture Engineering. Willey-Blackwell. 415 p. Moretti, A., Pedini Fernandez-Criado, M., Cittolin, G. and Guidastri, R. 1999. Manual on hatchery production of seabass and gilthead seabream. Volume 1. Rome, FAO. 1999. 194 p. ( Moretti, A., Pedini Fernandez-Criado, M. and Vetillart, R. 2005. Manual on hatchery production of seabass and gilthead seabream. Volume 2. Rome, FAO. 2005. 152 p. ( Stutvik, A. 2007. From broodstock to first feeding. FishfarmingXpert 2007(1): 23-34. Stutvik, A.2007. Growth and smoltiffication. FishfarmingXpert 2007(3):35-47. Woynarovich, A., Hoitsy, G. and Moth-Poulsen, T. 2011. Small-scale rainbow trout farming. FAO Fisheries and Aquaculture Technical Paper 561. 81 p. ( Further information – Website Search Aquaculture Fact Sheets. Cultured Aquatic Species. 64 Cultured Aquatic Species Fact Sheets are available: Cultured Aquatic Species Information Programme: Atlantic salmon: Cultured Aquatic Species Information Programme: Dicentrarchus labrax European seabass - Dicentrarchus labrax:

115 Further information â&#x20AC;&#x201C; Video AQUATOUR:


VI. Fish Nutrition, Feeding and Feed Additives Authors: Prof. Dr. Kemal Çelik, Baver Coşkun, Dr. Ahmet Uzatıcı

General approaches to fish nutrition In culturing fish in captivity, nothing is more important than sound nutrition and adequate feeding. If there is no utilizable feed intake by the fish, there can be no growth and death eventually results. Under nourished or malnourished animals cannot maintain health and growth, regardless of the quality of the environment. Therefore, before any attempt at fish culture it would be wise to ask a fundamental question, “What and how should I feed my fish? Good nutrition in animal production systems is essential to economically produce a healthy, high quality product. Generally in fish farming, nutrition is critical because feed represents 40-50% of the production costs. Fish nutrition has advanced dramatically in recent years with the development of new, balanced commercial diets that promote optimal fish growth and health. The development of new species-specific diet formulations supports the aquaculture industry as it expands to satisfy increasing demand for affordable, safe, and high-quality fish and seafood products. Today, aquacultural production is a major sea industry in many countries in Turkey as well, and it will continue to grow as the demand for fisheries products increases and the supply from natural sources decreases. As in more traditional forms of animal production, nutrition plays a critical role in intensive aquaculture because it influences not only production costs but also fish growth, health and waste production. To develop nutritious, cost-effective diets we must know a specie’s nutritional requirements and meet those requirements with balanced diet formulations and appropriate feeding practices. Research over the last two decades has expanded our knowledge of the nutritional requirements of cultured fishes. Major nutrient groups energy-yielding nutrients. Proteins, carbohydrates and lipids are distinct nutrient groups that the body metabolizes to produce the energy it needs for numerous 117

physiological processes and physical activities. There is considerable variation in the ability of fish species to use the energy-yielding nutrients. This variation is associated with their natural feeding habits, which are classified as herbivorous, omnivorous or carnivorous. Thus, there is a relationship between natural feeding habits and dietary protein requirements. Herbivorous and omnivorous species require less dietary protein than some carnivorous species. Carnivorous species are very efficient at using dietary protein and lipid for energy but less efficient at using dietary carbohydrates. The efficient use of protein for energy is largely attributed to the way in which ammonia from deaminated protein is excreted via the gills with limited energy expenditure. The foods carnivorous species eat contain little carbohydrate, so they use this nutrient less efficiently. In terms of energy density, proteins, carbohydrates and lipids have average caloric values of 5.65, 4.15 and 9.45 kilocalories per gram (kcal/g), respectively. These gross energy values are obtained by fully oxidizing the nutrients and measuring their heat of combustion in a calorimeter, with the energy released expressed as kcal/g or kiloJoule (kJ)/g (1 kcal = 4.185 kJ). Not all of the gross energy from nutrients is utilized because some of it is not digested and absorbed for further metabolism. Thus, the amount of digestible energy (DE) provided by a feed or feed ingredient is commonly expressed as a percentage of gross energy. A smaller fraction of the DE absorbed by the fish will be lost in metabolic wastes, including urinary and gill excretions, but these losses are relatively minor compared to the dietary energy excreted in the feces. Because it is hard to collect fish urinary and gill excretions, it is much more difficult to determine metabolizable energy (ME) values for aquatic organisms than for terrestrial animals. Therefore, ME values are not commonly reported for fish feeds or ingredients.

Proteins in fish nutrition As well known protein is the most expensive part of fish feed, it is important to accurately determine the protein requirements for each species and size of cultured fish. Proteins are formed by linkages of individual amino acids. Although over 200 amino acids occur in nature, only about 20 amino acids are common in animal nutrition. Of these, 10 are essential (indispensable) amino acids that cannot be 118

synthesized by fish. The 10 essential amino acids that must be supplied by the diet are: methionine, arginine, threonine, tryptophan, histidine, isoleucine, lysine, leucine, valine and phenylalanine. Of these, lysine and methionine are often the first limiting amino acids. Fish feeds prepared with plant (soybeanmeal) protein typically are low in methionine; therefore, extra methionine must be added to soybean-meal based diets in order to promote optimal growth and health. It is important to know and match the protein requirements and the amino acid requirements of each fish species reared. Protein levels in aquaculture feeds generally average 18-20% for marine shrimp, 28-32% for catfish, 32-38% for tilapia, 38-42% for hybrid striped bass. Protein requirements usually are lower for herbivorous fish (plant eating) and omnivorous fish (plant-animal eaters) than they are for carnivorous (flesh-eating) fish, and are higher for fish reared in high density (recirculating aquaculture) than low density (pond aquaculture) systems. Protein requirements generally are higher for smaller fish. As fish grow larger, their protein requirements usually decrease. Protein requirements also vary with rearing environment, water temperature and water quality, as well as the genetic composition and feeding rates of the fish. Protein is used for fish growth if adequate levels of fats and carbohydrates are present in the diet. If not, protein may be used for energy and life support rather than growth. Proteins are composed of carbon (50%), nitrogen (16%), oxygen (21.5%), and hydrogen (6.5%). Fish are capable of using a high protein diet, but as much as 65% of the protein may be lost to the environment. Most nitrogen is excreted as ammonia (NH3) by the gills of fish, and only 10% is lost as solid wastes. Accelerated eutrophication (nutrient enrichment) of surface waters due to excess nitrogen from fish farm effluents is a major water quality concern of fish farmers. Protein structure is well known nowadays, proteins consist of various amino acids and the composition of which gives individual proteins their unique characteristics. Many of the biochemicals required for normal bodily functions are proteins, such as enzymes, hormones and immunoglobulins. Fish, like other animals, synthesize body proteins from amino acids in the diet and from some other sources. Amino acids that must be provided in the diet are called “essential” or “indispensable” amino acids. Quantitative dietary requirements for the ten indispensable amino acids have been determined for several fish species. There are also ten “nonessential” or “dispensable” amino acids that the body can synthesize from other sources. These dispensable amino acids also


may be found in dietary protein and used for synthesizing body proteins. Table 1. Major classes of amino acids Essential amino acids

Nonessential amino acids

Arginine Histidine Isoleucine Leucine Lysine Methionine Phenylalanine Threonine Tryptophan Valine

Alanine Asparagine Aspartic acid Cystine Glutamic acid Glutamine Glycine Proline Serine Tyrosine

Fishâ&#x20AC;&#x2122;s minimum dietary requirement for protein, or a balanced mixture of amino acids, is critical for adequate growth and health. However, providing excessive levels of dietary protein is both economically and environmentally unsound because protein is the most expensive dietary component and excess protein increases the excretion of nitrogenous waste. Most of the herbivorous and omnivorous fish evaluated to date require a diet with 25 to 35 percent crude protein; carnivorous species may require 40 to 50 percent crude protein. Commercial feeds are carefully formulated to ensure that protein and amino acid requirements are met.

Carbohydrates in fish nutrition Carbohydrates (starches and sugars) are the most economical and relativelly inexpensive sources of energy for animal diets. The situation is similar to the fish nutrition. Although not essential, carbohydrates are included in aquaculture diets to reduce feed costs and for their binding activity during feed manufacturing. Dietary starches are useful in the extrusion manufacture of floating feeds. Cooking starch during the extrusion process makes it more biologically available to fish. Fish do not have a specific dietary requirement for carbohydrates, but including these compounds in diets is an inexpensive source of energy. The ability of fish to utilize dietary carbohydrate for energy varies considerably; many carnivorous 120

species use it less efficiently than do herbivorous and omnivorous species. Some carbohydrate is deposited in the form of glycogen in tissues such as liver and muscle, where it is a ready source of energy. Some dietary carbohydrate is converted to lipid and deposited in the body for energy. Carbohydrates of various size (carbon chain length) and complexity (one to several units bonded together) are synthesized by plants via photosynthesis. Cellulose and other fibrous carbohydrates are found in the structural components of plants and are indigestible to monogastric (simple-stomach) animals, including fish. In fact, the amount of crude fiber in fish feeds is usually less than 7 percent of the diet to limit the amount of undigested material entering the culture system. Soluble carbohydrates such as starch are primary energy reserves found in seeds, tubers and other plant structures. Animal tissues such as liver and muscle contain small concentrations of soluble carbohydrate in the form of glycogen, which is structurally similar to starch. This glycogen reserve can be rapidly mobilized when the body needs glucose. Prepared feeds for carnivorous fish usually contain less than 20 percent soluble carbohydrate, while feeds for omnivorous species usually contain 25 to 45 percent. In addition to being a source of energy, soluble carbohydrate in fish feed also gives pellets integrity and stability and makes them less dense.

Lipids in fish nutrition Lipids are high-energy nutrients that can be utilized to partially spare (substitute for) protein in aquaculture feeds. Lipids supply about twice the energy as proteins and carbohydrates. Lipids typically comprise about 15% of fish diets, supply essential fatty acids (EFA) and serve as transporters for fat-soluble vitamins. A recent trend in fish feeds is to use higher levels of lipids in the diet. Although increasing dietary lipids can help reduce the high costs of diets by partially sparing protein in the feed, problems such as excessive fat deposition in the liver can decrease the health and market quality of fish. This nutrient group consists of several different compounds. Neutral lipids (fats and oils), in the form of triglycerides, provide a concentrated source of energy for aquatic species. Dietary lipid also supplies essential fatty acids that cannot be synthesized by the organism. Fatty acids of the linolenic acid (n-3) family are generally more essential to fish than those of the linoleic acid (n-6) family. The 121

n- or “omega” nomenclature is used to describe fatty acids by the general formula X:Ynz, where X is the carbon chain length, Y is the number of ethylenic/double bonds, and n-z (or ωz) denotes the position of the first double bond relative to the methyl end of the fatty acid. Thus, 16:0 denotes a saturated fatty acid containing 16 carbons and no double bonds (all carbons saturated with hydrogen), and 18:1n-9 (18:1ω9) designates a monounsaturated fatty acid with 18 carbon atoms and a single double bond that is nine carbon atoms from the methyl end. Many freshwater fish can elongate and desaturate 18-carbon linolenic acid with three double bonds to longer chains (20 and 22 carbons) of more highly unsaturated fatty acids (HUFAs) with five or six double bonds. In contrast, most marine fish must have HUFA in the diet. In the body, HUFAs are components of cell membranes (in the form of phosphoglycerides, or phospholipids), especially in neural tissues of the brain and eye. They also serve as precursors of steroid hormones and the highly active eicosanoids produced from 20-carbon HUFAs. Eicosanoid compounds include cyclic molecules such as prostaglandins, prostacyclins and thromboxanes produced by the action of cyclo-oxygenase, as well as linear compounds such as leukotrienes and lipoxins initially formed by lipoxygenase enzymes. Eicosanoids are responsible for blood clotting, immunological and inflammatory responses, renal function, cardiovascular tone, neural function, and other functions. A diet deficient in essential fatty acids reduces weight gain, but usually after an extended period. This is due to mobilization of essential fatty acids from endogenous tissue lipids.

Minerals As known, minerals are inorganic elements necessary in the diet for normal body functions. Minerals can be divided into two main groups (macro-minerals and micro-minerals) based on the quantity required in the diet and the amount present in fish. Common macrominerals are sodium, chloride, potassium and phosphorous. These minerals regulate osmotic balance and aid in bone formation and integrity. Micro-minerals (trace minerals) are required in small amounts as components in enzyme and hormone systems. Common trace minerals are copper, chromium, iodine, zinc and selenium. Fish can absorb many minerals directly from the water through their gills


and skin, allowing them to compensate to some extent for mineral deficiencies in their diet. Micronutrients consists of inorganic elements the body requires for various purposes as mentioned up. Some reserachers indicated that fish require the same minerals as terrestrial animals for tissue formation, osmoregulation and other metabolic functions. However, dissolved minerals in the water may satisfy some of the metabolic requirements of fish. Minerals are typically classified as either macro- or microminerals, based on the quantities required in the diet and stored in the body. Macrominerals are calcium, phosphorus, magnesium, chloride, sodium, potassium and sulfur. Dietary deficiencies of most macrominerals have been difficult to produce in fish because of the uptake of waterborne ions by the gills. However, it is known that phosphorus is the most critical macromineral in fish diets because there is little phosphorus in water. Because excreted phosphorus influences the eutrophication of water, much research has been focused on phosphorus nutrition with the aim of minimizing phosphorus excretion. Phosphorus is a major constituent of hard tissues such as bone and scales and is also present in various biochemicals. Impaired growth and feed efficiency, as well as reduced tissue mineralization and impaired skeletal formation in juvenile fish, are common symptoms when fish have diets deficient in phosphorus. Chloride, sodium and potassium are important electrolytes involved in osmoregulation and the acidâ&#x20AC;&#x201C;base balance in the body. These minerals are usually abundant in water and practical feedstuffs. Magnesium is involved in intra- and extracellular homeostasis and in cellular respiration. It also is abundant in most feedstuffs. Table 2. Trace minerals and some of their prominent functions Trace mineral Copper Cobalt Chromium Iodine Iron Manganese Molybdenum Selenium Zinc

Function metalloenzymes vitamin B12 carbohydrate metabolism thyroid hormones hemoglobin organic matrix of bone xanthine oxidase glutathione peroxidase metalloenzymes

The microminerals (also known as trace minerals) include cobalt, chromium, copper, iodine, iron, manganese, selenium and zinc. Impaired growth and poor feed efficiency are not readily induced with 123

micromineral deficiencies, but may occur after an extended period of feeding deficient diets. The trace minerals and their metabolic functions in fish are shown in Table 2. The quantitative dietary requirements for some fish species have been established. Copper, iron, manganese, selenium and zinc are the most important to supplement in diets because practical feedstuffs contain low levels of these microminerals and because interactions with other dietary components may reduce their bioavailability. Although it is not usually necessary to supplement practical diets with other microminerals, an inexpensive trace mineral premix can be added to nutritionally complete diets to ensure an adequate trace mineral content.

Vitamins Fifteen vitamins are essential for terrestrial animals and for several fish species that have been examined to date. Vitamins are organic compounds required in relatively small concentrations to support specific structural or metabolic functions. Vitamins are divided into two groups based on solubility. Fat-soluble vitamins include vitamin A (retinol), vitamin D (cholecalciferol), vitamin E (alpha-tocopherol) and vitamin K. These fat-soluble vitamins are metabolized and deposited in association with body lipids, so fish can go for long periods without having these vitamins in the diet before they show signs of deficiency. Water-soluble vitamins include ascorbic acid (vitamin C), biotin, choline, folic acid, inositol, niacin, pantothenic acid, pyridoxine, riboflavin, thiamin and vitamin B12. They are not stored in appreciable amounts in the body, so signs of deficiency usually appear within weeks in young, rapidly growing fish. Most of these water-soluble vitamins are components of coenzymes that have specific metabolic functions. Detailed information about the functions of these vitamins and the amounts fish need have been established for many cultured fish species. Vitamin premixes are now available to add to prepared diets so that fish receive adequate levels of each vitamin independent of levels in dietary ingredients. This gives producers a margin of safety for losses associated with processing and storage. The stability of vitamins during feed manufacture and storage has been improved over the years with protective coatings and/or chemical modifications. 124

This is particularly evident in the development of various stabilized forms of the very labile ascorbic acid. Therefore, vitamin deficiencies are rarely observed in commercial production. Table 3. Vitamins and some of their major functions as established in fish Fat-soluble vitamins Vitamin A, Retinol vision Vitamin D, Vitamin E, Vitamin K Water-soluble vitamins Thiamin, B1 Riboflavin, B2 Pyridoxine, B6 Pantothenic acid Niacin Biotin Choline Folic acid Cyanocobalamin, B12 Inositol Ascorbic acid, vitamin C

Function Epithelial tissue maintenance, Cholecalciferol bone calcification, parathyroid hormone Tocopherol biological antioxidant Blood clotting Function Carbohydrate metabolism Hydrogen transfer Protein metabolism Lipid & carbohydrate metabolism Hydrogen transfer Carboxylation & decarboxylation Lipotrophic factor, cell membranes Single-carbon metabolism Red blood cell formation Component of cell membranes Blood clotting, collagen synthesis


Digestion and metabolism of fish The nutrients fish ingest in prepared feeds are broken down by digestive fluids and enzymes and then absorbed from the gastrointestinal (GI) tract into the blood. The digestion process in fish is similar to that in other monogastric animals; it involves physical, chemical and physiological processes within the GI tract. There is a wide range in the sizes and shapes of GI tracts in fish, but they all generally consist of the same basic structures - the esophagus, acidproducing stomach and intestine (though some fish, such as cyprinids, do not have an acidic stomach). The GI tract also includes pyloric ceca, which are protrusions posterior to the stomach that increase the absorptive area of the GI tract. Accessory organs that interface with the GI tract include the pancreas, which produces a variety of digestive enzymes, and the liver and gall bladder, which produce and store bile salts for emulsification of lipids in the GI tract. Protein digestion begins in the 125

stomach, a low-pH environment resulting from hydrochloric acid secretion and the proteolytic enzyme pepsin. Upon exiting the stomach, the ingesta (chyme) is neutralized by fluids in the intestine and further acted upon by enzymes from the pancreas and intestine. These enzymes aid in the breakdown of complex proteins, carbohydrates and lipids into small molecules that are eventually absorbed into the blood Intermediary metabolism. The liver plays a major role in directing the various nutrients to specific organs and tissues to be metabolized for energy. The same basic metabolic pathways for converting amino acids, carbohydrates and lipid into energy have been observed in fish as in terrestrial animals. It is preferable for dietary carbohydrates or lipid to be metabolized for energy so that protein (amino acids) can be used for tissue synthesis. To ensure this, there must be a proper balance of dietary protein to energy to optimize fish growth and lean tissue accretion. Energy-toprotein ratios ranging from 8 to 10 kcal of DE/g of protein (33 to 42 kJ/g) are optimal for various fish species.

Nutrient and energy utilization The fractions of dietary nutrients or energy that are eliminated in the feces represent undigested components that do not contribute to the nutrition of the fish. So it is generally desirable to use feeds that have a high level of digestibility. Coefficients of nutrient and energy digestibility for complete feeds or specific ingredients can be used to assess the relative percentage of ingested nutrients that are retained by the fish. Digestibility coefficients for specific feedstuffs can help producers more precisely formulate feeds to meet the nutrient requirements of the cultured species. This information is now available for many common feedstuffs and established fish species. Feed ingredients, formulation and manufacture

Feed ingredients Products for human foods are the primary ingredients available for fish feeds. Most of these ingredients have limited levels of nutrients, or even anti-nutritional factors, and are included in diet formulations only within specific limits. However, complementary ingredients can be combined to meet the nutritional requirements of fish. The major 126

ingredients in prepared fish feeds are protein supplements and energy supplements. Protein supplements contain more than 20 % crude protein, while energy concentrates have less than 20 % crude protein and less than 18 % crude fiber. Plant feedstuffs in the protein supplement category include oilseed meals such as soybean meal, cottonseed meal and canola meal, as well as other protein concentrates from cereal grains, including corn gluten, distillers dried grains with soluble, and wheat gluten. Animal feedstuffs in the protein category include cattle and swine byproducts such as blood meal, meat meal, and meat and bone meal; poultry byproduct meal and feather meal; and fishmeal from various reduction fisheries or processing byproducts. Energy concentrates include feed-grade cereal grains such as corn, wheat, sorghum and milling byproducts such as wheat middlings and rice bran. Fats and oils are the other source of concentrated energy for fish diets. These include feed-grade plant products such as soybean, safflower and canola oils, and animal fats such as beef tallow, poultry fat and fish oil. Blends of animal and vegetable oils also may be used in fish diets. Two other classes of feedstuffs are the mineral supplements and vitamin supplements, which are commonly purchased as premixes and added to nutritionally complete feeds to ensure that all nutrient requirements are met. A final class of feedstuffs is additives. These are compounds such as antioxidants, binding agents, enzymes, immunostimulants, palatability enhancers, prebiotics and probiotics that may be added to fish feeds at relatively low concentrations to confer specific benefits. The major feedstuffs used routinely in commercial feed mills are produced in large quantities and are usually available throughout the year. Most feed mills have fewer than ten bulk storage units, so only a limited number of feedstuffs are purchased and stored in bulk. The nutrient compositions of commonly used feedstuffs are well established and regularly updated based on routine analyses conducted by feed mills and feedstuff suppliers. These average values can be found in reference publications NRC publications and databases and can be used for diet formulation. Feed mills regularly inspect feedstuffs before accepting them, and samples may be chemically tested to ensure that they meet specifications. All aspects of feed production, from the initial acceptance of feedstuffs through the many steps in the manufacturing process to the final inspection of the finished feed, are guided by wellestablished quality control measures. These measures ensure the 127

production of high-quality feeds with the desired physical characteristics and nutrient composition to meet the needs of the targeted fish species.

Feed formulation and feed manufacturing The actual formulation of feeds for various fish species takes into account the specific nutrient requirements of the targeted species, the nutrient composition and availability of nutrients in various feedstuffs, and the cost and processing characteristics of ingredients. Many feed formulations are considered “open” because their ingredient compositions have been published. These formulatused as guides for feed manufacturers or fish producers. Some feed manufacturers use “least-cost” or “precision” formulation computer software to arrive at the most cost-effective formulations based on the cost of available ingredients, their nutrient concentrations and availability to the fish, the nutrient requirements of the targeted species, and any restrictions. These restrictions may include maximum or minimum limits for specific nutrients or ingredients because of nutritional and/or nonnutritional reasons. Nutritional reasons generally relate to satisfying the needs of the fish, while nonnutritional factors may include those which constrain the manufacturing process or alter the physical characteristics of the manufactured feed in an undesirable way. During manufacturing, feed ingredients are converted into a physical form that can be fed to fish. Fish feed can be manufactured as finely ground meals, crumbles and pellets of various size and density. Most diet forms are sold as dry products with 10 percent moisture or less so that they do not have to be stored refrigerated or frozen. Some semi-moist diets (20 to 35 percent moisture) are available primarily for feeding early life stages of carnivorous species. These feeds must be refrigerated or frozen for long-term storage. Manufacturing processes include grinding feedstuffs to reduce the particle size, mixing the feedstuffs, subjecting them to moisture (water and/or steam), and applying heat and pressure to produce a particular product form. The most common types of manufacturing for aquatic feeds are compression pelleting, which makes sinking pellets, and cooking extrusion, which produces pellets that sink or float. Pellet mills use steam to moisten and heat the feed mixture to approximately 160 to 185 °F and 15 to 18 percent moisture in a preconditioning chamber before passing it through a pellet die to produce a compressed pellet of the desired size. Although some cooking of the ingredients and 128

gelatinization of starch occurs during the pre-conditioning and pelleting process, a pellet binder is typically included in the mixture to increase pellet durability. Extrusion processing also uses a preconditioning chamber to subject the feed mixture to heat and moisture from steam, but it subjects the feed mixture to higher moisture (~25 percent) and much higher temperatures (190 to 300 °F) as it passes down the extruder barrel until it is forced out the end through a die. Considerable amounts of heat and pressure develop as the mixture passes along the extruder barrel. A rapid reduction in pressure when the mixture exits the die results in vaporization of some moisture in the mixture so that the pellets expand, reducing their density. Extruded pellets must be dried in a dryer to reduce moisture levels to 8 to 10 percent so they can be stored without refrigeration. There are limits to the amount of lipid that can be included in pellets because of frictional losses during processing. One of the advantages of the extrusion process over pelleting is that expanded pellets will absorb more lipid, which is applied with a fat coater. Fat is usually applied after drying and just before the feed is directed to storage bins. The fat coating adds energy to the diet and may improve palatability and reduce feed dust. The finished feed is taken from storage bins to be either bagged or loaded into trucks for bulk delivery. Diet forms for small fish can be produced by various methods. Microbinding, microcoating and microencapsulation procedures will produce larval feeds ranging in size from 25 to 400 microns. Traditional meals and crumbles are produced by reducing the particle size of pellets and screening them into specific size ranges. The processing procedures and diet forms selected for feeding small fish of a given species may depend not only on the fishâ&#x20AC;&#x2122;s nutritional needs but also on matching the dietâ&#x20AC;&#x2122;s physical characteristics to those of the culture system for best distribution.

Natural foods in aquaculture In certain culture systems (e.g., ponds), the food that is naturally available can make a valuable contribution to the nutrition of some life stages of fish. Producers should promote the growth of natural food when possible, using prepared feeds as a supplement. As fish grow older, they will need more nutrition than their environment can provide, especially under intensive production conditions, and should be given nutritionally complete prepared feeds. In culture systems such as raceways, cages/net pens and recirculating systems, where natural 129

food is minimal, the use of nutritionally complete prepared feeds is critical. Feeding schedules based on water temperature and/or fish size for a number of fish species that have been cultured for several decades, such as rainbow trout and channel catfish, various feeding schedules have been empirically developed that take into account the effects of water temperature and fish size on the relative feed intake of the fish expressed as a percentage of body weight. Such schedules specify that prescribed amounts of feed be given at certain intervals. In general, the feeding frequency and feed quantity (expressed as a percent of body weight) are reduced as fish size increases and water temperature departs from optimum. Feed manufacturers may provide such feeding schedules as general guides. Feeding to apparent satiation In certain culture systems, such as large ponds, it may be difficult to maintain an accurate estimate of fish biomass, in which case fish can be fed to â&#x20AC;&#x153;apparent satiation.â&#x20AC;? This feeding method can be rather subjective because it depends on the feeding activity of the fish and the experience of the feeder. Ideally, feed should be provided in small amounts over the course of 20 to 30 minutes or until feeding activity slows. This approach gives all fish sample opportunity to obtain some feed, especially after the most aggressive fish have consumed all they want. However, this method does require considerable amounts of time when multiple culture systems are being managed. Generally, it is better to underfeed than to feed too much because the uneaten feed will not only be wasted but also might degrade water quality. And if water quality is not good (especially dissolved oxygen levels and total ammonia nitrogen concentrations) it might not be possible to feed fish all they will consume. Demand feeders can be used under certain circumstances. These allow fish to consume feed whenever they desire. A demand feeder has a feed storage container with a conicalshaped bottom and a disc located slightly below the conical bottom. A metal rod extends into the water. When fish touch the rod, feed is dropped into the water. The quantity dispensed can be adjusted. This type of feeder is commonly used in the production of rainbow trout in raceways. Demand feeders should be checked regularly to make sure they are working properly and to refill with feed.


Feeding frequency and distribution The frequency with which feed is distributed is primarily determined by fish size and the characteristics of the culture system. Young fish grow faster and have better feed efficiency when fed several times a day. Older fish do not exhibit the same benefits from frequent feeding. Feeding can be done by hand or with automatic feeders. These feeders come in many different designs such as belt conveyers or vibrating dispensers, but generally can be adjusted to provide specific amounts of feed at set intervals. In hatcheries and other small systems, fish are often fed several times a day. In larger culture systems such as ponds, this practice is more time consuming and the fish may not benefit as much because they have access to natural food. Adequate distribution of the feed is another important consideration. Feed is easy to distribute in relatively small culture systems such as raceways, cages, net pens or intensive flow-through or recirculating water systems. Distributing feed in large ponds is more difficult. Feed blowers mounted on or pulled behind trucks are commonly used to dispense feed in ponds. It is generally recommended that feed be distributed down one or more sides of the pond to make it accessible to as many fish as possible. If feeding must be limited to one levee, as on large facilities where numerous ponds must be fed daily, feed should be distributed from the upwind levee so it will disperse out into the pond. All nutrients required for the well-being and normal growth of the fish must be supplied in formulated diets as available (digestible) nutrients. Otherwise, the fish cannot utilize the nutrients present in the feed ingredients. The formulated diets also must be pelleted and processed in such a manner that they are durable and water stable with a minimum amount of fines. Proper feeding of a quality diet should be considered as a high priority in the daily routine on fish culture stations. Reliable estimates of nutrient requirements have been established for major cultured fish species. These estimates are rather similar among species whose natural feeding habits and environmental requirements are comparable. There is also information about the nutritional value and suitability of common feedstuffs used in fish feeds. This knowledge has guided the development of diet formulations and feed management practices that promote efficient and cost-effective production while maintaining the health of the cultured species. 131

References Gatlin, D.M., III. 2002. Nutrition and fish health. In: Fish Nutrition. J.E. Halver and R.W. Hardy (eds.), 3rd edition. London: Academic Press. pp. 671-702. Gatlin, D.M., III and Li P. 2008. Use of diet additives to improve nutritional value of alternative protein sources. In: Alternative Protein Sources in Aquaculture Diet. C. Lim, C. D. Webster and C.S. Lee (eds.). New York: Haworth Press. pp. 501-522. Halver, J.E. 2002. The vitamins. In: Fish Nutrition. Halver and R.W. Hardy (eds.), 3rd edition. London Academic Press. pp. 61-141. Hardy, R.W. and F.T. Barrows. 2002. Diet formulation and manufacture. In: Fish Nutrition. J.E. Halver and R.W. Hardy (eds.), 3rd edition. London Academic Press. pp. 505-600. Lall, S.P. 2002. The minerals. In: Fish Nutrition. J.E. Halver and R.W. Hardy (eds.), 3rd edition. London Academic Press. pp. 259-308. re/ucm2954.htm Lovell, R.T. 2002. Diet and fish husbandry. In: Fish Nutrition. J.E. Halver and R.W. Hardy (eds.), 3rd edition. London Academic Press. pp.703-754. National Research Council. 1993. Nutrient Requirements of Fish. Washington, D.C. National Academy Press. Sargent J.R., Bell J.G., Bell M.V., Henderson R.J. and Tocher D.R. 1995. Requirement criteria for essential fatty acids. Journal of Applied Ichthyology, 11:183-198. Wilson, R.P. 1994. Utilization of dietary carbohydrate by fish. Aquaculture, 124:67-80.


VII. Fish Diseases and Treatment Methods Authors: Prof. Dr. Imre Mucsi, György Lódi, János Sztanó

Healthy fish are lively; they react well to environmental stimuli. No visible disorders or injuries can be seen on their body. They search for their food vigorously. Sick fish swim about sluggishly, or float in the water turning to their side or back, or swim round, or gather at the water inflow, or they gasp for air near the surface of the water. Also, they do not have appetite; they do not bite the bait. There may be typical, visible disorders on sick fish, e. g. distorted spine, abdominal lesions, excessive thinness, bulging eyes, broken fins, raised scales, discolouration of the skin, irregular skin disorders, parasites and tumours on the surface of the skin, etc. Fish live a hidden life so we can study their health status only by thorough observation, and by knowing the fish pond and its environment. Biotic fish diseases are all the disorders caused by viruses, bacteria, fungi and parasites. Abiotic fish diseases are caused by irregular environmental factors, e. g. conditions of lack of oxygen, bad quality water, presence of toxic materials, feeding problems, feeding bad, mouldy materials, etc.

1. Biotic Fish Diseases Viral diseases Spring viremia of carp (Virus septicaemia infectiosa cyprinorum) - a disease which affects mainly one or two year old carp, caused by RNS virus. The disease begins in spring when the temperature of the lake exceeds 13-15 °C. The abdomen of the dead or sick fish is enlarged, the eyes bulge, the rectum protrudes, the scales are raised, and haemorrhaging can be seen on the skin. The dissected fish have accumulated fluids in the abdominal cavity, 133

bleeding all over the body, swollen internal organs. Survival chances of the fish are minimal, especially if secondary bacterial infection complicates the viral disease. Earlier the disease of the dead fish infected by the two germs was called ascites. The viral disease can be prevented by the strong resistance of the body while the bacterial disease can be prevented by feeding antibiotic food. The spring viremia has to be reported to the animal health authority. Quarantine has to be introduced in the area of the disease. The quarantine can only be lifted by the animal health authority.

Fish pox â&#x20AC;&#x201C; carp herpes (Epithelioma myxomatosa cyprinorum) â&#x20AC;&#x201C; a disease of the carp, rarely of the catfish, caused by the herpes virus. Greyish white, scattered or merged lumps of jelly-like touch appear on the head, fins and often on the body of the sick fish, which are attached to the skin tightly and if they are removed, haemorrhaging area remains there. The fish rarely die of this but because the taste of the flesh changes, it cannot be eaten by humans.


Koi herpesvirus disease - was first described in Israel where 80 % of the common carp and koi carp was killed in a few month time by this disease caused by the herpes virus. Later the disease appeared in Indonesia, as well. Koi herpes usually occurs in summer when the water temperature is about 22-27 °C. The dead fish have gills with white spots, necrosis, haemorrhaging; their eyes are hollow; there are pale marks, blisters on the surface of the body.

Viral disease of the salmon type fish – includes the viral haemorrhaging septicaemia (VHS), the infectious haematopoietic necrosis (IHN) and the infectious pancreatic necrosis (IPN) of the trout. The fish with VHS become dark, inflamed areas appear on the skin and in the muscles, bleeding and degeneration occur in the liver and kidneys, and inflammatory fluid accumulates in the abdominal cavity. The mortality rate can be as high as 50%. IPN makes the young fish sick. The evidence for this illness is – besides the isolation of the virus – the necrosis of the pancreas and the hyaline degeneration of the muscles. These diseases must be reported to the authorities, and in case of mortality, designated laboratories must be contacted for investigations. Pike Fry Rhabdovirus Disease (Virus septicaemia infectiosa esocium) – also known as the red disease of the pike. Redness on the body, skin and gill bleeding, bulging eyes and hydrocephalus appear in the 4-5 cm long pike fry. The disease is transmitted by gold fish and water. 135

Lymphocystis in ornamental fish – appears in fish tanks and in ponds with ornamental fish. Pearl-like growths appear on the fins, skin and gill of the infected fish which become ulcerated later. The sick fish feed badly and their development slows down. Cauliflower disease in the eel (Papillomatosis anguillarum) - a viral disease that appears in older fish. Greyish white, irregular surfaced cauliflower-like growths, the size of a peanut or walnut appear on the area of the upper jaw. These fish are not suitable for eating by humans, which has an economic consequence.

Diseases caused by bacteria Ascites caused by Aeromonas hydrophila (Septicaemia haemorrhagia cyprinorum) – It is a disease of different species in cases of low resistance, which causes death with abdominal ascites, internal inflammations and bleeding. The symptoms are similar to those of spring viremia. The factors that make the fish susceptible to the disease are: wrong feeding, great fluctuation of the water temperature, transportation and packing that causes stress, and it may develop as a complication of other diseases. The germ is a facultative pathogen bacterium, which is always present in water, in the environment of the fish and even in the intestines, and it breaks into the bloodstream if the resistance in the fish becomes weak, starts to multiply and causes bacteraemia. The treatment in pond farms could be feeding the fish with antibiotic supplement, bathing the fish in a solution containing antibiotic, or individual vaccination. Ulcerative dermatitis (Erythrodermatitis) – is caused by a type of Gram-negative bacterium mainly in carp but it occurs in other fish species as well. Round ulcers develop on the body of the diseased fish except on the head, which penetrate deep into the tissues. The ulcers cause degeneration of the cells of the epidermis, dermis and muscles but the organs in the abdominal cavity are not affected.


The disease, which lasts for a long time, often occurs among fish stock of low resistance in the spring months, so previously it was believed to be a chronic form of ascites. The disease is known by anglers as wounded carp. Mortality is usually less than 20 %. The disease can develop in two year old carp as well which are introduced into fresh water in spring if the fish have become weak during winter time. The chance of recovery is favourable if antibiotic feed is given to the fish or they are bathed in antibiotic solution in the fish pond. Columnaris – occurs mainly in carp but also in any other fish species in ponds, fish tanks where the chemical composition differs from the optimal values or if feeding problems rise, i. e. lack of plankton. The disease got its name from the column-shaped Gramnegative bacteria. White, cloudy patches appear on the body – often on the gills - of the fish, which is followed by the necrosis of the skin and the gill filaments. Clinical sign of the disease is the fragmentation and discolouration of the gill filaments. The disease may often appear when rearing catfish. It appears in both fish ponds and angling lakes if the resistance of the fish becomes weak when the otherwise facultative pathogen bacteria multiply excessively. A successive treatment could be bathing the fish in salty water but eliminating the unfavourable environmental conditions is equally important. Fish tuberculosis (Tuberculosis piscium) – It is mainly a disease of tank fish. All fish species are susceptible to the disease but 137

it poses no danger to humans. Different Mycobacterium strains cause it. The abdominal volume of the listless, weak fish grow, fluid accumulates in the abdominal cavity, and pea sized tubercles appear in the guts. The disease cannot be treated, the infected fish have to be destroyed and the fish tank has to be disinfected thoroughly. Ulceration in pike (Morbus maculosus esocium) â&#x20AC;&#x201C; Its pathogen is not clarified. Mainly spawning and older pike get the disease in spring. The diseased fish stay close to the shore and near the surface of the water. In the beginning redness and inflammation appears on some later more scales on different parts of the body. Later the scales fall out, the skin dies and the tissues and muscles beneath infiltrate with blood and fluids. These parts are surrounded by a red ring. Later the dead skin falls off and a deep ulcer remains in the muscle. The ulcer will not heal and the fish die. Dissection reveals the weak condition of the fish and sometimes liver degeneration and intestinal inflammation can occur. The treatment of the fish is not possible. It is advisable to collect and destroy the dead fish. Red mouth disease in trout - is caused by Gram-negative bacteria belonging to the Salmonella strain. The most significant symptoms are the bleeding and inflammation around the moth and on the lips and later on the gills. The colour of the skin becomes darker and the eyes bulge. The diseased fish lose the9ir appetite and swim about listlessly. There are bleedings everywhere inside the body, revealed after dissection. The disease last for 3-4 weeks and 30-50% of the younger trout and 15-20% of the older may die. The treatment could be vaccination or sulphonamide or antibiotic. In some countries it is a disease that has to be reported to the authorities. Septicaemia in silver carp - is caused by Pseudomonas fluorescens bacteria. It appears during or one or two months after harvesting. Bleedings appear on the skin, the fins, on mucous membrane of the mouth and the gill cavity and in the eye cavity. Similarly, bleedings, infiltrations with mucous can be found in the internal organs with liver and kidney degeneration. Treatment is not possible in winter time, the disease can be prevented by observing the technology strictly.


Mucophilosis – is caused by the similarly named organism. Formulae of 60-70 µm diameters can be seen in the gill epidermis of the infected fish, which are the accumulated mass of the germs in the cells. It is a disease of mainly the carp and the grass carp. There is no treatment for this disease at present. It is advisable to dry the pond and treat the soil with lime.

Diseases caused by fungi and algae Fungi multiply with spores, their cells contain no chlorophyll, thus their nutrition is heterotrophic and they need organic materials to survive. The fungi that cause fish diseases all belong to the groups of Archimyteses and Phycomycetes. They can only cause diseases if the biological balance of the pond is disrupted (lack of oxygen, change in pH of the water, etc.). Saprolegniasis – one of the oldest known fish diseases. The disease is caused by the fungi living on rotting, decaying organic material. The fish develop different sized, whitish greyish cotton-like growths on the skin. Fungi create these growths, whose one end penetrates the skin and the other floats in water on the fish. The growth can cover the whole body.

It occurs on the injuries as well in angling ponds after the introduction of the fish. In pond farms, the growths appear on the sites of injuries caused by cormorants, gulls or carnivorous fish. The scales 139

are usually missing under the fungi, the skin is necrotized, fin rays are fragmented, and the cornea is bright. The diseased fish swim about in the water listlessly. The very ill fish can hardly be cured. If the disease is recognized early, a favourable result can be reached by bathing the fish in malachite green solution of 4 ppm concentration (1:250,000 dilution) for 20 minutes. Gill rot (Branchiomycosis) â&#x20AC;&#x201C; can develop in any reared fish species. It mainly occurs in angling ponds where the abundant organic material promotes the overpopulation of algae and plankton. It is caused by an alga fungus which parasitizes in the blood vessels of the gill. The spores of the fungus are spread by the fish but they can be transferred with contaminated water as well. The fungi in the blood stream get into the blood vessels of the gill where they block the capillaries and cause the necrosis of the gill. The diseases can be separated from other similar gill problems by identifying the alga. The acute form appears in the end of summer or the beginning of autumn and lasts for 2-3 days. The semi-acute form occurs in spring or in the beginning of summer and lasts for 1-2 weeks. The chronic type appears in spring or late autumn and lasts for months, which manifests itself by sporadic mortality. The seriously infected gill has a marble colour showing a disorder in circulation and causes the death of the fish. After identifying the disease, feeding has to be cancelled immediately and the pond has to be refreshed with a large quantity of oxygen rich water. The quantity of the accumulated plankton can be decreased by adding lime (200 kg/hectare) but the pH of the water should not be higher than 9. The disease can be attacked by adding copper sulphate (8-12 kg/ hectare). The agent must be sprayed in a 1% solution from May to August monthly. The disease can be prevented if infected fish are not purchased. The rotting plants in the lake have to be eliminated quickly and if roast ducks are reared in the pond, 100 ducks are placed in the lake per hectare at most. If the disease is suspected, the animals have to be moved from the lake. Ichthyosporidiosis â&#x20AC;&#x201C; is a disease of tropical fish living in fish tanks. It is caused by a fungus of the same name. The diseased fish become thin, the fins break off, lose their scales, and ulceration appears on the skin. After dissection, necrotic nodules will be found in


the spleen and the liver. The fish soon die because the disease cannot be cured. In order to postpone the death of the fish we can add 5 g/100 l Chlorocid antibiotic into the water of the fish tank. The disease can only be eliminated by strict disinfection by destroying the fish and the plants as well and the cleaned tank should also be sterilized when it is dry. The other equipment should be disinfected by hydrochloric acid. Diseases caused by algae â&#x20AC;&#x201C; The algae which stick to the skin and gill obstruct gas exchange, their toxins cause poisoning, when they overpopulate, they disturb the balance of the wet environment. Algal poisoning is caused by some green and blue algae species by their toxin production. The toxicosis will affect fish farms that use a lot of manure and fertilizer. Algal blooms appear in summer in ponds rich in nutrition, which leads to the biotope imbalance of the lake. The overpopulated algae form a blocking layer on the surface of the water and obstruct the oxygen from getting into the water. They themselves use oxygen and they also consume the nutrition in the water. After overpopulation they die, which fastens the rotting process and this leads to even less oxygen in the water. During rotting, hydrogen sulphide and methane are produced, which causes the death of the fish in large quantities with drowning symptoms. Significant changes in the pH lead to gill damage as well. Algal bloom should be prevented by keeping the level of the use of fertilizers at an optimal level. If the algae have started to overpopulate in a pond, we can hinder it by adding copper sulphate or quicklime to the water. Rearing ducks in ponds that tend to have algal blooms should be carried out with great care and complying to the technology. Mucophilosis (epitheliocystis) â&#x20AC;&#x201C; causes disease in the carp and grass carp. A similarly named unicellular germ multiplies in the ephitelial cells of the gill. The gills of the diseased animals are full of tiny round patches. The disease will occur in June or July. It often occurs in ponds where the water contains a lot of organic materials that tend to decompose. The diseased fish gather at the inflow, they become listless and swim about near the shore. The best method of fighting against this disease is maintaining the hygienic conditions of the pond


Diseases caused by parasites Most fish diseases are caused by parasitic lower organisms. Fish parasites are commonly protozoa or worms but some species of arthropods and molluscs can also parasitize on fish. A number of parasites move on the body of the fish freely and after detaching from it finds another fish. Some groups of parasites specialize on one fish species, e. g. gill worms, blood parasites and coccodia. Because of the special features of the wet environment, fish will probably never be reared without parasites. A small scale parasite infestation does not mean disease. When parasite infestation becomes a disease depends on the kind and number of parasites, the age, development and condition of the fish, and on the duration of the infestation, etc. The natural resistance of well fed, well conditioned fish is usually enough to prevent the development of the disease. However if conditions get weaker, severe diseases can occur. Parasites can harm the gills so much that they cannot perform gas exchange and fish drown. Another significant harm occurs because of the mechanic and toxic effect of the parasites. The gill necroses because of the parasites adhere and feed on it, and the epithelial starts to proliferate. Weather the fish dies from the damage of the gill depends on the temperature and oxygen level of the water. Fish in waters of higher temperatures die sooner than in colder waters. The oxygen content of the water is another important factor. Ichthyophthiriasis â&#x20AC;&#x201C; is the most well-known and one of the most economically significant fish diseases. It occurs in ponds of both cold and warm water and in tanks too. It is caused by a uniformly ciliated protozoan, which is visible to the naked eye because of its 1 mm size. The seemingly external parasite develops as an internal parasite under the outer layer of the epithelial and feeds on host organismâ&#x20AC;&#x2122;s cells and tissues. After detaching from the fish, the parasite reproduces outside and the swarming new individuals search new hosts. Because of this type of development, an intensive infestation may occur among fish kept in crowded waters, e. g. in angling lakes or intensive fish farms. The damage to the gill and the skin can cause 100% mortality. The fish whose skin is affected look as if they were covered with grist, hence the Hungarian name of the disease is grist disease.


The affected fish leave deeper waters, look for waters with higher oxygen content, or they gasp on the surface. If possible, they try to rub their side and abdomen, which become red and sores may develop. Greyish white, sharply defined, a bit protruding nodules of 0.3-1 mm in diameter appear on the skin and the gill, which cannot be brushed off with hand. For the treatment, malachite green is recommended. 400 g 3 malachite green is diluted in lukewarm water and added to 1000 m water of the pond evenly. It is very important to mix the agent evenly in the water because malachite green is toxic to fish. After 24 hours it is recommended to change the water of the pond the treatment should continue with ne solution. The other possibility is putting the infected fish stock in flowing water and the swarming protozoa are drifted away by the current. The same is recommended for fish in tanks. Fish sleeping sickness (Trypanoplasmosis) â&#x20AC;&#x201C; is caused by a flagellate protozoan living the blood of the fish. The infection is carried from one fish to the other by fish leeches. The parasites that float freely in the blood, whipping with their flagellums, and multiplying by fission make the fish weak by eating their blood plasma and damaging the red blood cells. The fish are languid and move little; the very ill fish lie on their sides on the bottom of the water and fish leeches are abundant on their body. These fish become thin, their skin and gill are pale, and their eyeballs are hollow. No specific treatment is known. It can be prevented by keeping good conditions and giving the fish abundant feed. 143

Chilodonellosis – is caused by the similarly named protozoa. It mainly occurs in crowded fish stocks, fry rearing ponds and wintering ponds. The parasite is spread by water. It reproduces well in colder waters, too. The diseased animals are listless, and swim about near the surface. Several times they show constrained movement with their abdomen upwards. The fish that become apathetic can be caught with hands. The skin of the fish has a milky colour, the epidermis is frayed, the gills are pale, and their structure is blurred, covered by a lot of mucus and epidermis fragments. The main possibility of preventing the disease is decreasing the crowdedness of the fish or medicine can be administered, too, e. g. tripaflavine, malachite green, copper sulphate, rivanol, methyl blue, etc. Ichtyobodosis or Costiosis – is the disease of densely introduced carp and trout of a few weeks of age. It is caused by a flagellate protozoan. The sick fry eat little food or do not eat at all. The fish stay near the surface of the water and they gasp. Their movement become slow and they do not react to stimuli from the environment. They can be caught easily. A veil-like greyish coating can be seen on the fins, skin and gills. In severe cases the fins lose their transparency, they become unclear, and injuries and deformations appear on them. The skin becomes frayed and its tatters float in the water. This disease occurs mainly in ponds with acidic water inflow and where the fish are introduced densely. For treatment, older carps can be bathed in a 5% common salt solution, which has beneficial effect. In case of other species and fry, bathing in a 2.5% common salt solution for 15-20 minutes is recommended. Trichodinosis – is caused by ciliated parasites, which cover the gills, the skin and fins of the fish in big masses. The severe epidermis injury leads to death. Mainly herbivorous fish are affected in fish farms. The gills of the dead fish are pale and coated by mucus and tissue fragments. The recommended treatment is bathing in malachite green. Fish Coccidiosis – is a very common infestation but only common carp and silver carp coccidiosis have significance. Diffuse intestinal coccidiosis is caused by Eimeria carpelli. The whole development of Coccidium takes place in the fish. The oocysts bore themselves into the epidermis of the intestines, where they harm the intestinal cells 144

mechanically and with toxic metabolites and disturb the secretion and absorption mechanism of the intestines. As a result the mucous membrane peels off at some places where bacteria start to accumulate. This disease happens at the end of winter among one summer old fish and during summer among the fry in rearing ponds. In case of severe coccidiosis, a great number of lutea are formed on the mucous membrane of the intestines. The infected fish become weak; they lie on the bottom of the pond and by the shore in masses. Their heads are usually in a downward direction. Their eyes are hollow, their backs and abdomens are retracted. The intestinal mucous membrane is covered by thick, reddish mucous layer, which contains the developmental forms of the oocyst. The individuals showing the clinical signs cannot be cured. The fight against the disease can only be prevention. The spring stock should only be introduced into a pond that has been dried and disinfected with lime. Diseases caused by myxosporeans – Several types of myxosporeans occur in fish and some of them can cause significant harm. The sign of the infestation is the development of white lumps the size of a pinhead in the fins, on the skin and the gills and in the internal organs of the fish. These cysts are full of spores. Gill myxobolosis (Myxobolosis disparum) – The protozoa form cysts, the size of a millet-seed in the connecting tissue of the central and outer parts of the gill. If the fish are strong enough, they do not die. The infestation can be decreased if the ponds can be dried up and the upper layer gets frozen during winter. Reliable decontamination can be achieved by disinfecting the soil of the pond by lime and chloride of lime. Muscle myxobolosis (Myxobolosis cyprinorum) – The protozoa develops in the skeletal muscles of the carp but its spores are detectable in all internal organs. Watery infiltrations develop in the capillaries of the internal organs because of the spores, the scales stand away from the body, and eyes bulge. The kidneys and the muscles are easy to be torn; besides anaemia is visible. Trout whirling disease (Myxobolosis salmonum) – It mainly causes economic harm among rainbow trout. It damages the 145

cartilages of the skull and the spine. Its symptom is the fish turning round and round because of the damage to the balance centre. The back third of the body is darker than the front part. Because of the damage to the cartilage tissues, the spine may become slanted, the gills become uneven, the nose becomes “pug nose”, the mouth stays open, etc.. Fumagillin DCH pulvis is suitable to treat the disease, and the bottom soil of the pond should also be disinfected. Thelohanellosis – It can make the carp fry ill in the summer, while the fin rays get distorted and break off. The disease does not cause significant economic damage. To fight and prevent the disease, it is recommended to dry and disinfect the pond. Gill sphaerosporosis– The protozoa develop without cysts in the support providing multilayer epidermis of the gill, or rarely in the skin. So the disease cannot be diagnosed by simple observation. The infection has a special epidemiology; the spores can only be found in summer and autumn. At the onset of the disease the rate of the infected fish is 80-100 % in some ponds and another pond next to it might be free of infection. We can only find severely infected on or non-infected fish in a stock. The ill fish show the signs of drowning: they swim about near the surface of the water, and they become weak and thin. Mortality rate is very high when the spores ripe. The gill of the dead fish is pale, has a blurred structure and damaged tissue fragments can be found. In case the fish are fed optimally they can survive the infection and by the end of autumn the infection ends. Swim bladder disease (Aerocystitis) – is a disease of carp in pond farms. One of the most significant fry diseases. It is caused by a protozoon that develops in the wall of the swim bladder. The disease can be divided into five stages: 1: the swim bladder becomes rich in blood and tiny bleedings appear; 2: the level of blood in the swim bladder decreases and distinct, brown or black patches, the size of a lentil seed, appear on the wall of the swim bladder; 3: the swim bladder becomes thick, inflammatory products appear; 4: the disorder becomes more serious, some layers of the wall of the swim bladder die; 5: cysts are formed in the wall of the swim bladder and its cavity is filled with serous, purulent fluid. From stage 3, the appearance of bacterial complication is likely. As for the signs, in the first two stages the disease is asymptomatic. In the chronic form of the disease (from stage 3), the ill 146

fish swim on their back losing their balance, or on or their sides, or head down. Their tail fin sticks out of the water, they flutter them without success trying to sink. The symptoms start suddenly, when the water level in the pond or tank sinks a lot in a short time and the ill swim bladder cannot function normally in its hydrostatic role. The belly of individual fish becomes very large and its touch is rippling.

About 10-20 % of the fish reach the most severe stages from the initial slight disorder and death is sporadic, too. It is worth noting that other fish living together with carp do not become ill seemingly. The course of the illness in fry is rapid, the parasite form tends to heal, and the swim bladder regenerates. In case of complications, a high proportion of the stock may die in a short time. Treatment has not been resolved, the only effective medication for prevention is Fumagillin DCH pulvis.

Diseases caused by worms Usually external parasites, characterized by their strict host specificity. They usually colonize the gills, fins and skin of the fish, and in the nose cavity. Gill fluke disease of the cyprinids (Dactylogyrosis) Dactylogyrus are the tiny worms with elongated body, their body length is rarely more than 1mm. These parasites are hermaphrodites, and they produce eggs to multiply. The worms living on gills constantly empty the eggs, which sank to the bottom of the lake. The eggs become embryos on the bottom of the lake, and the larvae swim to find a host fish. The larvae settled on the gills start developing, losing 147

their cilia. The worms which have settled in the gills gill fix themselves with their anchors latched onto the gills. They damage the epithelium with their side anchors and to feed on detached epithelial cells, tissue fluids, mucus, sometimes with blood. If the worm invasion occurs within a few days, a large number of gill worms settle, the fish die before the typical gill damages. The mortality rate depends on the size of the fish, the number of settled worms and the water temperature. The ill fish are restless, looking for more oxygen rich water. The agonizing fish float on the surface with their bellies turned up. By definition, the gills are covered by pale, mosaic-like, abundant mucus.

To control the disease, it is important to avoid the direct contact of the fry with the older, for example mother fish, which could be parasite carriers. The perfect separation is facilitated by artificial propagation. The overwintering eggs can be eliminated by drying and disinfection of the soil. Another effective method is filling the ponds with water a few days before introducing the fish, and the hatching worm larvae die in the absence of a suitable host. In case of appropriate feeding, the fry soon reach 5-6 cm in size, and they outgrow the harm of the parasites. The parasites are harder to find host fish in less crowded populations. The ill juveniles can be cured with bathing in 2.5% saline or ammonia a solution. The older fish can be bathed in 5% saline solution for 5 minutes. Equally favourable results can be reached by bathing in 0.1% ammonium hydroxide solution for a half minute as well. 148

Gill worm disease of the catfish (Ancylodiscoidosis) - The parasite specializes on catfish, it clings to the tissues of the gills with its middle anchors, and it damages the gills with side anchors and digestive fluids. The epidermis of the gill decays, tissue damage and bleeding occur. An acute gill worm disease develops in the fry and in older fish a subacute or chronic disease develops. The sick fish show signs of hypoxia and asphyxia, they move towards the inlet of the lake and they can be caught by hand. Some of the fish float upright in a vertical manner on the water surface. During the autopsy we observe similar disorders as in other fish species with the company of a large number of worms. As for the medical treatment of disease, good results will follow the use of organic phosphoric acid esters, and bathing in a 0.1% ammonium hydroxide solution for half a minute. The main requirement for preventing the disease is to prevent the mothers from contaminating the fry, or even it is advisable to bathe the mothers before spawning in the lake. Gyrodactylosis â&#x20AC;&#x201C; The parasites live on the body surface, fins and gills of the fish. It is a viviparous species where successive generations can be found in the worm's body at a time. The parasite feeds on carp in pond farms in particular (and on the crucian carp). The sick fish are listless; the fry are slow to develop and show symptoms of shortness of breath. The worm can be killed in salty, ammonia baths, and with organic phosphoric acid ester. The preventive measure is avoiding big fish density. Fluke worms (Trematodes) â&#x20AC;&#x201C; are parasites that reproduce with intermediate hosts. Some of them are adult worm parasites in fish, in their intestines or vasculature. In this case, the first intermediate host are aquatic snails or mussels. The second intermediate host are organisms which is a food source of the fish, such as crabs, snails, insects, etc. If they do not need intermediate hosts, the developmental stages of the flukes (cercaria) find the fish with active swimming and get into their bodies. Blood fluke disease of the fish (Sanguinicolosis) â&#x20AC;&#x201C; The flukes, which are not more than 1 mm long and have an elongated body, parasitize in the blood vessels of carp gills. The intermediate hosts are snails. The flukes lay their eggs into the bloodstream of the carp


where they parasitize; the miracidiums hatch there, which penetrate the tissues, and getting into the water they swim to find a snail. There they continue to evolve, and later leave the intermediate hosts and finding a fish they penetrate it, where they become sexually mature, the process begins again. The eggs, which are produced in large quantities, are capable of blocking the blood vessels, and on their impact congestion and necrosis occur. When the gill becomes ill, due to clogged capillaries, some sheets of the gill die off and are destroyed. The gills become pale, sometimes mottled, dotted with haemorrhage. This form of disease is mainly characterized by the fry. When the kidney becomes ill, the Malphigi bodies die due to clogged capillaries and because of the loss of kidney function, fluid accumulates in the abdominal cavity, the scales pockets and the eye cavity. The abdomen becomes enlarged, the scales turn outwards, and the eyes are bulging. This form of disease is characterized by the older carps. The control of the disease is based on the extermination of snails, which can occur by freezing the pond bottom, resting the pond in summer, and by disinfecting with lime. A suitable snail disinfectant is a 5 mg / l copper sulphate solution. Diseases caused by fluke larvae (Diplostomosis) - a widespread disease. The fluke larvae parasitize in fish eyes (eye lens), their mature form live in the guts of water birds (gulls, terns). The miracidiums that hatch from the eggs that fell in the water with faeces develop into cercaria after penetrating the snails. The cercarias leave the snail, and finding they fish penetrate their skin, and through the bloodstream they enter the eyeball, where they will remain for years without encysting in a viable state. The larvae migrating in the body of the fish or being present in the lens may cause the death of the fish, because the visual deterioration of the fish impedes food acquisition. During the migration of the cercarias, the fish are restless, they perform forced movements, the skin darkens, and in the abdominal area small hemorrhages are visible. At the time of the eye disease, its indicator is that the animals become thin, and their blurred lenses appear as milky balls. Elimination of infection is possible if we eliminate the two host, snails and birds. The intermediate host can be eliminated by the above described pond bottom treatment, the host animals - by scaring the birds. 150

Fish tape worm disease Khawiosis - the unsegmented tapeworm occurs in the intestine of carp and grass carp. The adult individuals are of 170 mm length, 4 mm wide. The Khawia reproduces with intermediate hosts (Tubifex tubifex), they reach the infective stage there and they get into the fish intestinal system by consuming the intermediate hosts, they adhere to the front section and become sexually mature there. The entire development cycle lasts for one year. Coracidiums are formed on the soil from the eggs excreted in the spring and early summer. This is consumed by the intermediate host, where the next developmental stage occurs, which is the feed of the fish with the tubifex.


The disease has no typical symptoms, the fish are lean, their growth is retarded, do not feed properly. The intestinal epithelial lesions, ulcers are formed, but severe intestinal inflammation can also develop. The gut mucous production increases, the mucosa is swollen, marked in streaks, minor bleedings are also formed. Controlling the disease includes drying and freezing the pond bottom, together with the treatment of infected individuals. The diseased fish can be treated with 3-5-fold higher than usual amount of mixed Devermin drug in spring before the egg production begins. Bothriocephalosis of the common carp and the grass carp The tapeworm can reach a length of 150-200 mm, a width of 2.5-3 mm. The worm's body has several segments that widen in the rear. The coracidium is formed on the bottom of the lake after the eggs left the fish with the faeces, and floating in the water they remain infectious for 4-6 days. They then enter the lake crabs, in which they form into infectious forms in 1-3 weeks. The intermediate hosts gets into the intestinal track of the fish as food, colonizing the front part of the intestines and thus cycle is repeated. The disease occurs most often in pond farms, intensively used ox-bow lakes and reservoirs. The most commonly diseased fish among the farmed fish are the common carp and the grass carp. Among the wild spawning fish, the crucian carp and the red-eyed carp are infected. On the site in the intestine where the tapeworm attaches, catarrhal enteritis, excess serum, hyperaemia, haemorrhages, necrosis and due to the toxicity liver and kidney degeneration may occur. The settled worms clog the intestinal lumen, prevent its normal operation and a significant amount of food is withdrawn from the host, which results in the fact that weight gain is significantly reduced. The disease symptoms are not typical; at first only the poor feed conversion is apparent. In case of severe infestation, the fish swim about on the surface of the water, do not consume the feed, become thin and die off. During the autopsy the yellowish-white worms are clearly visible in the gut. Controlling the disease is very difficult because all the conditions for the development of the worm in the lake are given. To prevent the disease, it is important to separate the fry from the adult individuals strictly, and also to dry and freeze the nursery ponds or treat them with lime for disinfection in every season. The worms in the water can be destroyed in different developmental stages with organic phosphorus acid ester, but at the same time the re-introduction of the plankton has to be ensured. The tapeworms living in the fish can be killed by adding a product called Devermin (0.1-0.3 g / kg body weight). The drug is fed 152

in the lake after it is mixed thoroughly into homogenized feed. General, full recovery proves difficult for severely infected individuals consume the least from the feed, and will continue to be a source of infection. Ligulosis - the adult worms parasitize in the gut of waterfowl, they stay until maturity. The first intermediate hosts are Cyclops, the second the cyprinoids. The worms need to be in the abdominal cavity of the fish for at least 425 days to become infectious. The infection of the fish can persist for over 3 years. The most common places of the infection are natural waters, lakes and ox-bow lakes. The ligulosis is capable of destroying a great proportion of the bream, roach and bleak stock. In the fish ponds, there may be significant infection among the carp and bighead carp populations. The tapeworms cause such serious changes in the abdomen that 1-2 items colonizing the fish can lead to mortality.

The worm can weigh up to one-third of the weight of the fish, so the abdominal wall expands, relaxes, the internal organs are compressed, blockages, adhesions are formed in the gut, there is a continuous peritoneal inflammatory status, and the cavity is filled with the effusion. The ill fish swim hard, staying close to the surface of the water, forced movements are carried out, and float turning up. They do not consume the feed placed into the lake, rather the plankton. Pond farms can be fairly effectively protected from ligulosis by scaring the waterfowl away, and terminating their nesting opportunities. Ligulosist in natural waters can be decreased by removing the ill fish by propagating predators. 153

Diseases caused by Nematodes - the sterlet, eel, bream, pike can be infected with the various types of nematodes. In general, no major economic injury is caused.

Fish diseases caused by Leeches â&#x20AC;&#x201C; Fish leech â&#x20AC;&#x201C; Its body is cylindrical, the front and rear end has a suction cup, ca. 3 cm in length. Leeches are hermaphrodites. In summer they attach egg sacs on the lake vegetation, the soil or on the wet shore. The hatched leeches are instantly able to suck blood. The leeches filled with blood detach from the fish and sink to the bottom. The hungry ones creep on stones, plants and they attach to a fish if possible, their sucker adhering to the surface of the body and piercing the skin to suck blood. The salivary glands of the leeches contain anticoagulant (hirudin) and, therefore, after the leeches have come off, blood trickles for a while. Damaged skin is invaded by secondary fungi, bacteria, so the anaemia is accompanied by other diseases. The disease most often occurs in the wintering ponds, where it is the easiest to attack the fish for blood, whose life functions are decreased. Another favourable environment is the areas densely covered by plants. The disease is maintained by the older and wild fish. The fish living with leeches are restless, fiercely toss themselves. In the winter lake, they interrupt their winter dormancy and swim to the inlet water. In case of severe infestation, the fish become thin; their skin is ulcerated from which blood may ooze. The disease can be significantly reduced or eliminated if we remove the aquatic plants in the lakes, or we introduce grass carp fish in the lakes. It is also important to keep away wild fish from farmed 154

fishes. In winter, the dry lake bed should be disinfected with 25003000 kg lime per hectare. For the sake of introducing a leech-free stock, it is recommended to bathe the fish in 2.5% saline solution for 15 minutes, during which time the dazed leeches fall off the fish. The leeches can be destroyed by treating them with organic phosphoric acid esters as well.

Diseases caused by crustaceans (Lernaeosis) A rare parasitic disease. Females are permanently attached to the fish; they fall off only after they die. The ones settled on the body of the fish penetrate their protrusion into the skin so deeply that they reach the muscle layer. At the site of the attachment, deep, inflammatory ulceration occurs; the edges are bright red, sharply demarcated from the normal tissue. Bacteria can colonize the ulcer, resulting in its growth, and tissue granulation begins. The granulation tissue rises above the plane of the body surface. The parasitosis most frequently occurs in fish living in channels of fish farms, on crucian carp, on sunfish, but pike and herbivorous fish have also been affected. First the ill fish are restless and avoid movement, do not feed, are emaciated. The young fish also die off. Organic phosphoric acid esters are suitable for medical treatment.


â&#x20AC;&#x153;Fish Liceâ&#x20AC;? (Argulosis) - Carp of every age can become infected and ill. The crab having attached to the fish becomes sexually mature with a complex transformation. The parasite survives the winter on the skin of the fish surrounded by mucus. The fish lice have a broad host range, they can colonize not only each fish species but amphibians too. They approach the fish with swimming actively, and adhere to the skin with suction cups and mandibular legs. They sink their boring organ into the skin, and feed on the blood sucked from the inflamed skin and on tissue fluids. On the site of the excess fluid discharge, a depression and later ulcer develops. The fish lice frequently change its location, and prick the skin in several places. Fungi and bacteria colonize the pricked areas. The fish lice play the role of the intermediate host of some parasite nematodes, and promote their spread. Younger fish are more sensitive to the presence of fish lice, they often die, too. The first summer old fish can be killed by 20-25 fish lice. The sick fish are restless; they reduce their food intake, and are emaciated. The infection can be established with the naked eye. The mass of lice is easily visible in the abundant mucus that covers fish body and fins.In order to control the disease, the older fish should be kept separate from young ones and the other fish species and frogs should be exterminated from the lake. Drying and freezing the pond bed is also recommended. The lake bed can be disinfected with chloride of lime or quick lime. The fish lice can easily be destroyed 156

with organic phosphoric acid ester. A solution of potassium permanganate can be used as well.

Diseases caused by mussel larvae There is a relatively brief period in the development of mussels when the larvae colonize the fish gills, skin or fins and engage in a typically parasitic lifestyle. Parasites feed on tissue fluids, emigrated white blood cells, and epithelial cells. Fish are most commonly infected with mussel larvae in natural waters.

Diseases of unknown origin Gill necrosis - mainly occurs in carp populations. The gills of the ill fish swell, their structure becomes blurred, a large amount of mucus can be found on them. Some gill sheets are greyish-white; others are bright red due to the stagnant blood. The gills become fragmented due to the chipping of the ends of the gill sheets. The disease is thought to be autointoxication developed as a result of high free ammonia content, or it could be the combination of ammonia poisoning and a columnaris disease that followed it. The ill fish are restless, they gather around the inlet, while others exhibit spinning motion that appears to be a neurological symptom. The disease is detected in newly introduced fish in natural waters. Winter skin disorder â&#x20AC;&#x201C; An illness of a few year old carp occurring during the winter time. On the back and fins of the ill fish, milk glass coloured mucous can be observed initially, under which the skin pigmentation changes. Later, the skin has a map-like pattern and becomes dry. Scratching the skin of the ill fish, one can notice unknown one-celled creatures. It is likely that the flowing water supercooled to 1-2 C° contribute to the onset of the disease.


Granulomatosis of goldfish - The infection can be detected in all aged goldfish and usually the best, few year old individuals are killed. External clinical symptoms include abdominal volume enlargement, confused swimming, tilting to one side or floating on the water bellyup. In autopsy the symptoms resemble tuberculosis infection in every aspect.

Diseases caused by fish pests Bird cuts - Longitudinal injuries transverse to the body are frequently observed on body of the fish. These are the so-called gull cuts that arise when a bird lifts a fish from the water, and then drops it. The injuries mostly extend into the outer layer of the integument, but it is possible to have deeper, bleeding injuries, too. Secondary fungal and bacterial complications can develop. The cormorants proliferated in the last decade, damage a lot more fish than they eat. The wounds have little chance of recovery in autumn, winter and early spring. The waterfowl can be controlled by scaring them. It is more difficult to defend the fish from damages caused by protected animals in the pond: the bullfrog and the marsh frog. In particular, the bullfrog can consume a large number of fry each day. Invertebrate fish enemies - Particularly in natural waters, the diving beetles, the lesser water boatmen, the backswimmer bugs and the water scorpions and their larvae are often able to inflict more damage than actual diseases. In natural waters, biological balance exists between the fish and their enemies, but in nurseries it is 158

necessary to fight against them. These pests are quite sensitive to organic phosphoric acid esters.

2. Abiotic Fish Diseases Diseases caused by environmental factors Lack of oxygen (Anoxemia) - the most common cause factor that cases the death of the fish. The oxygen saturation of the water may drop below the optimum level for a number of reasons. In summer, the decrease is due to high water temperature, or a decomposition process, rotting that takes place in the water, or it may be due to the presence of a more than optimal, large amount of fish. In winter, the ice directly prevents oxygen from penetrating into water, and the snow and cuts off light from the water, so water plants cannot produce oxygen. Absolute oxygen deficit occurs when the oxygen content of the water is reduced to an extent that is not enough for the fish. The relative lack of oxygen causes damage to the gills. Then even there is enough oxygen in the water, the fish cannot utilize it. If the lack of oxygen occurs in the fish or in the water, the fish die. It is therefore necessary to monitor the oxygen content of the water and the fish gills continuously. Anoxic conditions always develop during the technical operations of rearing, e. g. when harvesting, transportation, introducing, etc. when the fish are in a crowded space. This relatively short period of time does not cause mortality but the stress has an effect and reduces resistance to disease, and promotes the development of diseases. In case of absolute oxygen deficiency, large amounts of oxygen rich water should be provided for fish (pumping). It is also suitable to have a motorboat run on the lake. In winter, holes are cut in the ice and the snow is ploughed off the ice for oxygen supply. In case of relative lack of oxygen, besides raising the oxygen content of the water, the gill disease should be treated and eliminated as soon as possible. To stop the rotting, decaying processes in the lake, the vegetation is removed from the water to prevent algal blooms. We should repeat this for wintering as well. Poisoning (Intoxicationes Piscium) - Today, not only drinking water but also good quality water for fish farming, free from contamination is becoming less and less available. The wastewater 159

and water contamination cause problems around the world. In the fight against water contamination the fish play an indicator role. The water in which the living conditions of the fish are present can be used as drinking water after proper cleaning procedures. With the development of industry and the use of chemicals in agriculture, the waters are increasingly contaminated. Therefore, when massive fish mortality occurs, we can think of intoxication caused by water. Two thirds of the instances of immense fish mortality are caused by the industry, and one-third has agricultural origin. Toxins of organic origin are poisonous either because of their own chemical nature (pesticides, phenol, etc.) or they may be harmless themselves (food industry waste water) but their decomposition absorbs a large amount of oxygen, and it causes asphyxiation of the fish. Inorganic compounds (heavy metal salts, ammonia, hydrogen sulphide, etc.) exert their effects directly, and the death of the fish is caused by the toxins themselves. The poisoning is characterized by the fact that same or different species of fish die in large numbers at one time without preliminary signs. Mortality is often unnoticed; the result is visible only. When trying to find out the causes of deaths, the first step is to exclude oxygen deficiency. The lack of oxygen in the rivers does not happen usually even in the summer heat, but it usually occurs in pond farms of high density (perhaps as a side effect). Mortality due to lack of oxygen usually occurs in the early morning hours, which is shown by the fact that the morning feed is still there in the water in midday. Test samples (and water sample) should be sent to the institution of animal health from the dead fish and the still alive fish as well in order to rule out the presence of viral / bacterial and parasitic diseases. It is not always possible to detect the toxin from the body of the fish. By the time the fish die and they are examined, the potential toxins in water e.g. sewage water have already become diluted to an extent that they not show toxic quantities. Therefore, in case of the rivers, samples should be taken from downstream as well and be submitted to the laboratory. The diagnosis can be established by the experience of experts at site visits and from the laboratory test results. Autogenous poisoning â&#x20AC;&#x201C; is usually caused by hydrogen sulphide and ammonia that is produced in the water and in the bed of the lake due to rotting vegetation or abnormal degradation in the mud. The hydrogen sulphide is formed by the decomposition of sulphate ions in bound, acidic soils. The gas accumulates in the mud first, then the water too. Mainly in summer, less often in winter, hydrogen sulphide is 160

release due to the drop of air pressure and it causes poisoning. Hydrogen sulphide is toxic even at a quantity of 0.5-4 mg / l. If the oxygen content in the water is low, the toxic effect is even stronger. Hydrogen sulphide is toxic because it inactivates the enzymes containing heavy metals and it inhibits the oxygen uptake and metabolism. The bream are the most sensitive to the presence of hydrogen sulphide, followed by predatory fish and carp. Ammonia â&#x20AC;&#x201C; In alkaline water, over 20°C, the ammonium ion is converted into free ammonia, and cause massive fish mortality slowly at 0.2-0.5 mg / l and rapidly above 0.5 mg / l. Due to the neurotoxic effects of ammonia the fish are restless, swimming desperately in the water. The gill cover and the mouth of the dead fish are open, and the blood oozes from the gills. Some types of the agricultural water contamination cause a deficiency of oxygen. Decaying organic matter, organic waste material originating from plants or animals may come from pig farms, distilleries, sugar refineries and breweries or hospitals. To break down the large amount of organic material, such a great amount of oxygen is used up that it may lead to a massive death of fishes. When using lime for disinfection, the water pH should be monitored continuously and if the reading exceeds 9, the epidermis of the gills of the fish may be damaged severely, which leads to death. Among the pesticides, primarily chlorinated hydrocarbons, ones that contain organic phosphoric acid ester, as well as the herbicidal, algicidal and fungicidal substances are poisonous. These toxic substances may get into the environment of the fish out of negligence, or by the water flowing from the area which was treated with them, or by accident. The toxic dose of the most commonly used pesticides is LD 50 (50% of the fish die within 24 to 96 hours in the water containing a certain amount of poison). From these data, it can be concluded that each species has a varying degree of sensitivity to pesticides. The most dangerous ones are the chlorinated hydrocarbons which are capable of cumulation. The pesticides are neurotoxins for the fish. Therefore, the symptoms of poisoning are manifested in excitement, writhing, convulsive swimming, jumping out of the water. The cause of death is usually respiratory centre paralysis. In case of acute poisoning, no disorders can be explored even in the histological examination. In chronic cases, degenerative condition can be found in hepatocytes; the chemical can be detected in the fish and the water. In order to avoid poisoning, the organic phosphoric acid ester, which is used for 161

treatment, has to be added in very accurate doses in spite of its rapid degradation. When using this chemical it should be considered that the zooplankton is also destroyed, so the treatment should not take place in the pond but in the winter pond or in a designated pool. Among the fertilizers, primarily those containing phosphorus and ammonium nitrate are harmful to fish. If large amounts get into the water, they change the ion balance of it, and by damaging the epidermis of the gills of the young fish gills, massive death of the fish may occur. In case of industrial water contaminations, a great variety of inorganic substances, heavy metal salts, acids, bases, mineral oils, detergents, etc. may occur so that their examination requires special analysis. Their composition and concentrations vary significantly within a short period of time, they usually have a strong impact, but they can quickly become diluted and their damage does not extend to a large area relatively. The detergents (surfactant washing agents produced synthetically, which contain soaps or surfactants) get in the environment of the fish with household and industrial waste waters. The benzene sulphate and its derivatives do not only destroy the fish but also their eggs in a concentration of 5-10 mg / litre. The poison attacks the gills and skin of the fish; it stimulates mucus production and damages blood cells. Detergents are detected from the water. Among the metals, the various compounds of iron, copper, lead and zinc are the most dangerous. These materials get into the water mainly from factories, mines and vulcanizing plants. Especially the fish populations of trout ponds and artificial hatcheries are vulnerable to these metals and their compounds. The free chlorine can get into the water from industrial plants and swimming pools after disinfection. Poisoning can be caused by water containing 0.1-0.2 mg / l free chlorine in a few days. As a result of the poisoning, the respiratory epithelium of the gills dies; the fish die quickly with drowning symptoms. In chronic cases, the dead fish show the signs of liver degeneration. Phenol is the most common toxic product among the derivatives of mineral oils. The symptoms of poisoning include the excitement of the nervous system. Even 5 mg / l phenol is toxic to carps. In chronic cases liver degradation may develop. Although only 0.02-0.1 mg / l phenol present in water does not induce mortality, the flavour of the fish becomes disgusting. If the fish are placed in clean water for about 6 weeks, the taste becomes normal again.


Temperature as a cause of disease - Fish have a very good heat tolerance. The trout can survive 25 °C, the carp 35 °C, and the crucian carp 40 °C without damage to any of their organs. If the water temperature rises above normal and the fish die, the cause of death is not due to the heat but to the biological imbalance in the lake and the lack of oxygen. Fish suffer most from sudden changes in temperature of 10-15 °C. The fish that suddenly get into waters of temperature under +6 °C develop shock-like symptoms - the movements of the gill cease, inability of swimming develops and they lose their ability to keep balance. Excessive cold water of about 0-1 °C is the most dangerous. Then the skin and gills are covered with greyish white membrane and emaciated fish die. Feed-induced intestinal inflammation (Enteritis) - is due to either a sudden change in feed or poor quality feed. The biggest threat is caused by the feeding of treated or dressed feed. The consumed dressing mostly does not cause death, but it builds up in the fish's body and it poses a human health hazard when the fish is eaten. Those feeds are dangerous that contain Escherichia coli or salmonella bacteria or their toxins. The bacteria and fungi, and their toxins and metabolites, for example aflatoxin, F 2, T2 toxins, which accumulate in musty, mouldy feed, pose a threat. The pathogens produce toxic compounds (amines, peroxides) and as they get in the intestine, they alter the normal intestinal bacterial flora. In carp, bacteria and fungal spores remain intact in the absence of gastric acid, and in the favourable, slightly alkaline pH environment they exert their effects easily. Therefore, it may happen that the healthy fry introduced as usual do not develop sufficiently and remain small and weak. The retarded fish may have diseases such as enteritis, intestinal inflammation and varying degrees of liver degeneration. After the illness caused by feed, the fish regain their appetite after only a few weeks, so if 3-4 of these cases occur during the summer, the development of the fry may be reduced to a minimum. The fry with low resistivity can resist the external and internal parasites and infectious diseases to less extent. In the summer, the fish harvested with feed bait for market sales have a full digestive tract, and if the delivery and new introduction goes together with stress, their digestion stops, the feed begins to decay, abnormal breakdown products are formed in the intestines, and the large amounts of gaseous decomposition products bring about enteritis and inflammation. The dead fish typically have bloated 163

bellies. Such carp are unable to dive under the water, turning on their belly they struggle on the surface. The disease cannot be cured but can be prevented by resting the fish for 24 hours prior to delivery.

Diseases of not well understood etiology Intestinal inflammation in grass carp â&#x20AC;&#x201C; It is a disease of 3-4 summer old grass carp (rarely silver carp) kept in lakes with little green vegetation, and fed intensively (hard fodder). The intestinal inflammation is always acute. The ill fish are clustered near the shore edge, they can be easily caught. The colour of their skin darkens, and lack of some scales can be observed. The gills are pale or blackishred, covered with mucous and algae. At necropsy, the liver is a light brown oily to the touch, and easy to tear. The bowels are empty, their linings are inflamed on fields of various sizes, and the diseased fish soon die. The treatment is usually unsuccessful. The disease is preventable by ensuring optimum environment and providing natural plant food. Gill necrosis - a disease of fishes of two summer of age. Its etiology is unclear. The disease occurs in spring and summer, especially in intensively reared fish. In acute cases, it is completed in 10-15 days and the mortality rate can be between 50-60%. In chronic cases of the disease it can persist for 3-4 months, and mortality is minimal. The disease starts in the gill with the proliferation of amoeboid cells, and the infiltrated part breaks off in tatters. The epithelial cells of the breathing sheets degenerate and their place is occupied by granulation tissue containing acidophyl cells. The proliferating tissue sticks together the adjacent folds, and later the plates also, making them unfit for breathing. Because of the disorder in blood supply, necrosis comes about in some parts accompanied by extensive haemorrhaging. The dead plates come off, thus forming typically serrated gills. First a lack of appetite calls attention to the presence of the disease, and later the animals start swimming restlessly on the surface of the water and they are clustered near the inflow or the coast. The die even if sufficient fresh water is provided for them. In less severe cases, the gills are pale, its structure is blurred, the plates are covered with large amounts of mucus. In severe course of the disease, the gills are torn, the ends of the plates are toothed (serrated). 164

Methods of medical treatment are not known, but if the disease is detected in time, the damage can be reduced by providing natural feed, improving the quality of the water, making it richer in oxygen. Tumours â&#x20AC;&#x201C; are only sporadic. They are seen more frequently in ornamental aquarium fish. The fish may have both benign and malignant tumours. Therapeutic care is not possible and it is most appropriate to dispose of the ill fish.

References _ferenc.pdf mon/Series4_FishDiseasePrevention.pdf al_diseases_of_fish.html

165 Kocylowski – Miaczynski (1963): Halbetegségek. Mezőgazdasági Kiadó. Budapest. p. 56–323. Molnár K. – Szakolczai J. (1980): Halbetegségek. Mezőgazdasági Kiadó. Budapest. p. 59–242. Molnár K. (2003): Halbetegségek. MOHOSZ. p. 10-90. Sorces of picturesájékoztató%20a%202013% 20évi%20halegészségügyi%20helyzetről%202013%20Agárd.pdf Molnár K. (2003): Halbetegségek. MOHOSZ. p. 10–90.


VIII. Contaminants and Residue Problems in Aquaculture, and EU Legislations Author: Prof.Dr. Erg端n Demir

Type and aquaculture





Aquaculture products are the most important source of polyunsaturated fatty acids, proteins, phosphorous, iron, selenium, iodine and vitamins. They are well known for their effects on human health. However, there are specific risk of contamination by chemicals. Consumers must be able to profit from these quality nutrients while being assured that aquaculture products are hygienic and safe. The products attract stricter controls in international trade especially in the markets within EU and other developed countries. Aquaculture area are distributed on coastal area, in estuaries and pond. Fish are thus especially directly exposed to industrial, agricultural and municipal dumping or indirectly through contamination of sediments by these different activities. The risk of mobilisation of pollutants from environmental reservoirs such as sediments by dredging or bad weather is also higher in coastal area. The risk of contamination of pollutants originated from atmospheric pollution is the same as that of wild products. Finally, coastal areas are characterised by their multi-activity. Fish reared in the coastal area could thus be contaminated by multiple contaminants. Furthermore fish could also be exposed to a higher risk of accidental pollution. The most severe risk of contamination is for chemical compounds such as organic chemicals (chlorinated pesticides, PCBs, dioxins & furans, polycyclic aromatic compounds), heavy metals, veterinary drugs (antibiotics, chemicals) and toxins (natural and from foodstuffs). The severity of risk of disease related to contaminants is generally minor to severe and could even induce death. The acceptability of chemical risk for aquatic products is lower than that of the classic hygienic risk for which large progress have been realised in its control. The specificity of chemical contamination for aquaculture products as compared to wild aquatic products is related to the origin of the 167

contaminants. Environment, feeding and rearing practice could lead to the accumulation of specific compounds in the flesh of fish. For some aquaculture products (molluscs) the environment and feeding origin of contaminants are however intermingled so that it is not easy to dissociate the relative contribution of each of the source. Aquaculture products seems thus combined the classical risk of contamination of animal products (feeding and rearing practice) and those of plant products (environment and crop practice). The environmental contaminants have different sources:    

Agriculture, Industry, By-products of industrial and human activities and others such as municipal and industrial effluents.

The important chemical contaminants and toxins in fish and fish products are: 

  

Contaminants: Mercury, arsenic, lead, fluoride, dioxin, DDT and metabolites (DDD and DDE), polychlorinated biphenyls (PCBs), piperonyl butoxide, other agricultural chemicals or their derivatives (pesticides), Toxins: Histamine (Scombroid poisoning), saxitoxins (PSP), domoic acid (ASP), okadaic acid (OA), pectenotoxins; Non-permitted additives: Nitrites, nitrates, sulphites, phosphates Drugs and feed additives: Drugs, veterinary medicines, feed additives as antyoxydants, antimicrobial growth factors (antibiotics), e.t.c.

Many of the chemicals are essential for life at low concentration but become toxic at high concentration. While minerals such as copper, selenium, iron and zinc are essential micronutrients for fish and shellfish, other elements such as mercury, cadmium and lead show no known essential function in life and are toxic even at low concentrations when ingested over a long period. These elements are present in the aquatic environment as a result of natural phenomena such as marine volcanism and geological and geothermal events, but are also caused by anthropogenic pollution arising from intensive metallurgy and mining, waste disposal and incineration, and acidic rain caused by industrial pollution. This is in contrast with organic 168

compounds, most of which are of anthropogenic origin brought to the aquatic environment by humans.

Type of contaminants a. Organic contaminants This is a very diverse group with a wide range of industrial uses and a chemical stability that allows them to accumulate and persist in the environment. The chlorinated organic pollutants such as PCBs, dioxins and pesticides are especially important organic contaminants. They used in:

Agriculture:  DDT which is now banned,  toxaphene,  hexachlorobenzene (HCB), Chemical industry:  PCBs,  HCB By-products:  Dioxins  and Furans (produced by fossil fuels, wood, municipal and industrial wastes). These compounds are accumulated in the food and at the end of the food chains, relatively high concentration are observed in fish.


Contamination is often higher in freshwater than in seawater fish species. The source and pathways of contamination of the aquatic environment depends on the origin but for most of these compounds contamination is related to direct release in water except for dioxin and furan for which there is an indirect contamination by global cycling of these compounds in the atmosphere. One of the characteristics of these compounds illustrated for pesticides is related to their persistance in the environment (half live up to more than 20 years for DDT and toxaphène) and their high bioconcentration in aquatic organism. Due to their long half-life in the environment, there are environmental reservoirs of these contaminants especially in the sediments. Thus even if some of these compounds are not used (DDT) or close to be banned (PCB) there are still present in the environment and risks of mobilisation of these contaminants from the sediments. The mobilisation process is however low and regular except in some exceptional conditions such as flooding and dredging. Most of these contaminants represent a mixture of different compounds (670 for toxaphene, 200 for PCBs, 210 for dioxins and furans) which correspond to different degrees and localisation of chlorination of a skeleton based on cyclic (benzene) or polycyclic (biphenyl, napthalene, dibenzofuran, etc.). These compounds are highly lipophilic and this explain the high bioconcentration in aquatic organisms. The bioconcentration depends on the degree and localisation of chlorination. All consumers of fresh fish and fish products are thus exposed. These compounds once there are consumed accumulates in adipose tissues and the retention is with long half live. As for the accumulation in the aquatic organisms, the accumulation in fatty tissues depend on chemical structure of these compounds. These compounds have non specific biological effects which are mainly related to induction of cancer and mutagenic effects. However due to their chemical structure dioxins and furan bind with a high affinity Ah receptors involved in control of development and reproduction. Some other chlorinated persistant compounds such as PCBs whose conformation mimic that of dioxin could also bind these receptors but with much less affinity. Combined accumulation of different persistent organic pollutants in fatty tissues could occurred but although interaction between these compounds are suspected the effects of these compounds are supposed to be additive.


b. Inorganic chemicals (heavy metals and elements) Heavy metals such as arsenic, cadmium, lead, mercury, selenium and copper are present in water by direct release of effluents from mining activities, from some specific chemical industries, from animal production and from municipal wastewater treatment. Heavy metals are concentrated in farm animal effluents, they accumulated in the soils and are progressively released in water. Heavy metals are also indirectly concentrated during wastewater treatment. The efficiency of removal for most of the heavy metals during wastewater treatment is not high and consequently there is a regular release in water. Consequently aquatic products are more specifically contaminated by heavy metals compared to other food products. The mercury is especially very dangerous for human. The contamination of aquatic environment by mercury is both direct in surface waters and indirect from global atmospheric pollution. The elementary or inorganic mercury is specifically transformed by aquatic anaerobic bacteria in methyl mercury which is a developmental toxicant, mutagenic and carcinogen. The contamination of freshwater predator fish is higher than that of bottom feeders. Sea water predator fish such tuna, swordfish, skate, sea bass are also especially contaminated. The maximum concentration accepted is 1 μg/g fish for USA FDA but EU has fixed a lower maximum threshold 0,5 μg/g except for 20 sea water fish species especially contaminated for which the maximum contamination have been adapted to 1 μg / g. The maximum weekly intake is only 200 μg/week (FAO, OMS) and thus fish consumers are especially exposed.

c. Feed based contaminants Cereals, oilseeds, oilseed meals, fish meals and different kinds of feed additives are used by feed manufacturers to formulate the aquafeeds. The fish could be contaminated by compounds found in these foodstuffs used in aquaculture. The major animal feed contaminants that have been reported to date have included Salmonellae, mycotoxins, veterinary drug residues, persistent organic pollutants, agricultural and other chemicals (solvent residues, melamine), heavy metals (mercury, lead, cadmium) and excess mineral salts (hexavalent chromium, arsenic, selenium, flourine), and transmissible spongiform encephalopathies. The direct negative effect of these possible contaminants on the health of the cultured target 171

species cause a risk that the feed contaminants may be passed along the food chain, via contaminated aquaculture produce, to consumers. In recent years, public concern regarding food safety has increased in Europe as a consequence of the increasing prevalence of antibiotic residues, persistent organic pollutants, and chemicals in farmed seafood. Fish and crustacean are fed on feeds containing a high proportion of fish meals and fish oils which contains specific contaminants. The fish are however fed more and more on plant meals and plant oils as substitute of fish meals and fish oils. Thus fish are exposed to the same risks of contamination as those of farm animals fed on these foodstuffs.

Fish meals, fish oils and animal protein sources - The different environmental chemical contaminants such as persisting organic pollutants, polycyclic aromatic hydrocarbons and heavy metals could be accumulated in products used for fish meals and fish oils foodstuffs. As these fish originated from open sea the contaminants are rather those from global atmospheric pollution such as dioxins and furans for POP and methyl-mercury for heavy metals. These compounds accumulated in the food webs, and thus aquaculture could be considered as a further step of accumulation of environmental contaminants compared to wild products. Fish meals and fish oils is even the main source of contamination of farmed fish for these compounds. Adversely, the fish used in fish meals are not high value fish as there are not at the top of the food web and thus their contamination could be limited compared to that of fish used for human consumption. However the data collected recently on dioxin, furans demonstrating the contamination of fish meals and fish oils do not support such possibility. 172

Steps in fish meal storation can induce production of oxidative compounds which are ingested by farmed fish and accumulated in fatty tissues. The compounds produced by oxidative process induce specific flavors (cardboard, rancidity) and only few of these compounds are toxic for man. The specific risk of contamination of aquaculture products by prion compounds has to be considered. These compounds have not been detected in fish. The use of animal foodstuffs in fish feeding is now banned in EU (except for aquatic products) and is not practice in many other countries. Thus the risk of contamination is very limited. The contamination by prion of aquatic environment could also be emphasized but there are not yet any data in this field of research. Plant meals and plant oils - In addition to fish meal, soybean meal and other oilseed meals, and their oils are important protein and intensive energy sources for aquaculture diets. Different chemical contaminants from environment (atmospheric pollution, soils contamination) or used for plant production (pesticides, herbicides) could accumulate in plant meals and plant oils. These compounds present in these foodstuffs ingested by fish could accumulate in the flesh. The risks of contamination is however similar than for other farmed animals and even lower if the low proportion of plant foodstuffs in the feed of fish is considered. The plants meals and plant oils could also contain some anti nutritional and phyto-oestrogenic compounds which have adverse effect on fish. It is also obvious that soybean and rapeseed are genetically modified plants. Mycotoxins in aqua feeds - In recent years there is a trend to replace fish meal in aguaculture diets as a source of protein by less expensive sources of protein from plant origin such as DDGS. As a result of this trend, aquaculture feeds have a higher risk of being contaminated with one or more types of mycotoxins. Mycotoxins are toxins produced by fungi. They are secondary metabolites of Fusarium sp., Aspergillus sp., Penicillium sp., Alternaria sp. Claviceps sp., etc produced under favourable environmental conditions on almost all agricultural commodities worldwide. More than 400 mycotoxins identified. Mycotoxins are chemically stable, resistant against high temperatures, resist storage and processing conditions. Many factors such as weather conditions (temperature, humidity), variety of grain, insect manifestation, crop density, fertilization, crop maturity and moisture content, insect control and preservation, 173

shipping conditions and processing influence mycotoxin formation in feedstuffs. There is a great concern about mycotoxins in Europe because some mycotoxins are deadly at very small dosages. Some mycotoxins are carcinogenic and cause huge losses in productivity in aquaculture. The most susceptible feeds to fungi-producing mycotoxins are manufactures feeds, corn, wheat, oats, barley, recently sorghum, cottonseed meal, peanut meal, other oil seed meals and rye. Mycotoxins decrease growth rate and cause health poroblems in aquaculture. This might also effect human health because certain aflatoxin levels were recorded in the muscles of fish fed contaminated diets. There are evidences that mycotoxins can cause several pathologies problems in fish liver, kidney and pancreas.

The pathological signs of mycotoxin poisoning in fish and shrimp species include poor growth, anemia, impaired blood clotting, damage to liver and other organs decreased immune responsiveness. The effects of mycotoxins on aquaculture are:  Death,  Poor performance from low feed intake and body weight gain,  Respiratory problems,  Reproductive problems,  Liver, kidney or other organ damage,  Cancer in human. The main risks for plant meals is related to toxins produce during their storage mycotoxins such as aflatoxins. The occurrence of such toxins in foodstuffs used in fish feeding is limited and the main risks is rather for fish than for the product. 174

The most important mycotoxins are: 

  

Aflatoxins: They are the most common mycotoxins. Aflatoxins are hepatotoxins. Prolonged feeding of low concentrations of aflatoxin B1 (AFB1) causes liver tumors, which appear as pale yellow lesions and can spread to the kidney in fish. AFB 1 toxicity to shrimp results in the modification of digestive processes and abnormal development of the hepatopancreas. It cause abnormalities such as poor growth, low apparent digestibility and physiological disorders. AFB1 is also toxic and cargiogenic for human. Ochratoxins: Ochratoxin A is the most important form. Very few studies have done on the effect of ochratoxins in fish species. Pathological signs of ochratoxicosis include liver necrosis, pale, swollen kidneys and high mortality. Trichothecenes: There are two forms of trichothecenes: Type A-Trichothecenes (T-2 toxin, T-2, Diacetoxyscirpenol) and Type B-Trichothecenes (Deoxynivalenol, Nivalenol, Fusarenon X). T-2 toxin and deoxynivalenol are more toxic for aquaculture than others. Fumonisins: Fumonisin B1 is considered the major toxic component both in corn culture and in naturally contaminated corn. In fish, the role of fumonisins as toxic agents remains unclear. To prevention mycotoxin formation: Use clean procedures, Prevent contamination, Inhibit mold growth o Drying o Refrigeration o Mold inhibitors

d. Veterinary medicines/drugs A veterinary medicine is a product designed for administration to animals for a medicinal purpose. This is defined as:  Treating or preventing disease  Diagnosing disease  Contraception 175

 Anaesthesia  Otherwise preventing or interfering with normal operation of a physiological function. Therapeutants Therapeutants are chemical substances used on fish farms or aquaculture operations when necessary to keep aquatic animals healthy while they are being raised. Therapeutants could be drugs or pesticides. Certain therapeutants (such as some antiparasitic products) are added to the water to specifically control only external parasites (i.e. topically applied to fish by submersion in a bath). MRL and AMRL Maximum Residue Limit (MRL) is an amount of drug residue present in treated aquatic animals that will not pose adverse human health effects if the food is consumed daily over a lifetime. A MRL applies to a specific tissue for a specific species. For example, sulfadiazine, a drug approved for use in salmonids, could be administered to salmonids and the residual level in the edible tissues of fish offered for sale cannot exceed the MRL of 0.1 µg/g. The definition of an Administrative Maximum Residue Limit (AMRL) and a MRL are basically the same since the process and rigour that the Veterinary Drug Directorate (VDD) uses to assess the safety and risk of a veterinary drug are the same. Banned drugs Use of some of drugs are banned in aquaculture and also in anaimal production by national and international legisletions. Banned drugs are those drugs which are prohibited for sale for administration to animals that produce food or that are intended to be consumed as food because the drug contains one of the following:  Chloramphenicol or its salts and derivatives,  A 5-nitrofuran compound,  Clenbuterol or its salts and derivatives,  A 5-nitroimidazole compound or,  Diethylstilbestrol or other stilbene compounds. The evidences in aquaculture and animal production have shown that exposure to these substances is unsafe for consumers. Fish and crustaceans containing any residue from these drugs are in violation 176

of the Food and Drug Regulations and the Fish Inspection Regulations and would not be permitted for sale in the market. Apparoved drugs Fish farmers have to use approved drugs to prevent residue risks in aquafoods. Drugs that have a Drug Identification Number (DIN) on the label are drugs that are approved. Any drug residue present in the food must not exceed the MRL or AMRL for that drug set by Regulations.

Therapeutants which are accepted to be used in aquaculture

A therapeutant accepted to be used in aquaculture can be a drug authorized for sale to be used specifically in aquatic animals. Any therapeutants which are not considered accepted to be used are essentially unapproved and their residues should not be present in fish offered for sale. All importers should be aware that there could be a food safety risk associated with therapeutants in the aquaculture products they import. To help ensure that consumers are not exposed to non-compliant products, importers are responsible for discussing the potential of therapeutant use and residues in aquaculture products with their suppliers. Domestic processors should discuss the potential for therapeutant use and residues with their suppliers of aquaculture products when establishing drug residue controls under their Quality Management Program (QMP) plan.

Manufacture of veterinary medicanal product Within the EU such veterinary medicinal products may only be manufactured and supplied by the holders of a Marketing Authorisation. Applications for veterinary medicine are assessed in the EU, and in most other regulatory regimes, against three basic scientific criteria. These are: ď&#x201A;ˇ ď&#x201A;ˇ ď&#x201A;ˇ

Quality, Efficacy and Safety.


The requirements for satisfying each of these criteria are presented in detail in the relevant volumes of "The Rules Governing Medicinal Products in the European Union" published by the European Commission. These three regulatory criteria apply equally to veterinary pharmaceuticals and veterinary immunologicals. Manufacture of veterinary pharmaceuticals: For pharmaceutical products, quality criteria principally concern the chemistry and pharmacy of all components of the medicanal product, details of the processes of manufacture, packaging and stability under storage, especially in relation to formulation and intended route of application (i.e. bath or in feed). This includes details of the chemical nature and identity of excipients and, especially for medicated premixes, details of particle size and distribution. With bacterial and viral diseases, effective laboratory challenges can normally be developed, thus enabling the demonstration of comparative relative percent survivals between protected and unprotected animals, although with some agents field challenges may be essential. For therapeutants, efficacy studies need to demonstrate that the drug concerned is effective against the target pathogen and that an appropriate dose regimen has been demonstrated. Studies of this type can be difficult and costly to carry out and there has been a tendency to use a standard therapeutic period. For fish, the great majority of therapeutants are supplied by the oral route which leads to additional requirements for medicated premixes and manufacture of medicated feeds. Applicants are required to demonstrate that the product is:  Safe to the consumer,  Safe to the user–farm staff during feed medication on farm or in the feed mill,  Safe to the target species (fish),  Safe to the environment. Safe to consumer: Withdrawal periods of manufactured veterinary products have to be followed by the fish farmers. For the consumer, the primary safety aspects concern the prevention of hazards of consuming unsafe residues in the edible tissues of farmed animals. Primary control is exercised via Maximum Residue Limits (MRL), established by Council Regulations. The MRL defines the maximum level of residues of any component of a veterinary medicine that may be present in foodstuffs of animal origin without presenting any harm 178

to the consumer. The establishment of an MRL allows the setting of a withdrawal period for the product. The withdrawal period is a set time between last medication and earliest date of slaughter-harvest and must be sufficient to ensure that veterinary residues have depleted to levels below the MRL. Safe to the user: Medicines' legislation requires that user safety be assessed in the safety package and that the product label must include advice and warnings to the user giving guidance for safe use. Hazards associated with feed medication, whether in feed mill or on farm, must be considered, as must any hazards to the final user (fish farm staff). Such hazards include dust, the need for use of gloves, masks and other protective clothing for volatile liquids and for most formulations, the risks of skin absorption and hand contamination. Safe to the target species: Tolerance levels of the pveterinary products must be carried out to determine the safety of the product to the target fish species. Safe to the environment: Requirements to assess environmental safety of the use of any veterinary medicine product passing through the authorisation process formed part of the original harmonisation legislation. Immunologicals As with pharmaceuticals, the basic information required in support of applications for immunologicals concerns quality, safety and efficacy. In the case of immunologicals, quality additionally includes quality of any excipients and adjuvants plus the microbiological aspects of the master and seed cultures, fermentation facilities and inactivation or attenuation procedures, etc. In practical terms, for fish, these requirements do not differ from the requirements for other veterinary vaccines. A full list of substances to be monitored for under Directive 96/23 is shown in Table 1. This is a third country Directive, and would be exporting states must satisfy the European Commission that they have in place a residue monitoring programme equivalent to that in place in EU member states.


Table 1. Directive 96/23 list of substances Group Aâ&#x20AC;&#x201C; Substances having anabolic effect and unauthorised substances (A1) Stilbenes, stilbene derivatives, and their salts and esters (A2) Antithyroid agents (A3) Steroids (A4) Resorcylic acid lactones including zeranol (A5) Beta-agonists (A6) Compounds included in Annex IV to Regulation (EEC) 2377/90 Group B â&#x20AC;&#x201C; Veterinary drugs and contaminants (B1) Antibacterial substances, including sulphonamides, quinolones (B2) Other veterinary drugs (B2a) Anthelmintics (B2b) Anticoccidials, inc. nitroimidazoles (B2c) Carbamates and pyrethroids (B2d) Sedatives (B2e) Non-steroidal anti-inflammatory drugs (NSAIDs) (B2f) Other pharmacologically active substances (B3) Other substances and environmental contaminants (B3a) Organochlorine compounds including PcBs (B3b) Organophosphorus compounds (B3c) Chemical elements (B3d) Mycotoxins (B3e) Dyes (B3f) Others

e. Other chemicals used in aquaculture Chemical compounds used in aquaculture are mainly antibiotics, antiseptics and anaesthetics. Steroid hormones are not used in fish which have to be fed but only to raised broodstock for monosex populations. Many aquaculture chemicals are by metabolites and degradation products of intentionally their nature biocidal when released to the surrounding added chemicals. There are few antibiotics specifically developed or adapted for fish treatments and thus only few are accepted : sulfonamides, tetracyclin, quinolones, macrolides, enamectin (for sea lace) in Europe. The fish farmers can use the antibiotics do not demonstrate any probiotic effects in fish, for only limited to therapeutic treatments. The main risks of the use of antibiotics in aquaculture is however related to their release in the environment. This could induce the contamination of aquatic organisms but it is rather the risk of development of antibiotics resistance that have to be considered. 180

Antiseptic compounds such as formol, malachite green, chloramine T could be used to eliminate ectoparasites. There are specific risks of accumulation of these compounds which limited their use. Anesthetics are only used during rearing period and not during period close to slaughtering. Furthermore anesthetics based on natural compounds start to be used. Pesticides and piscicides present a risk to human health and their use has to intoxication with the chemicals. Triphenyls (PCBs), dioxins, methane, cyanide, methylmercury, zinc and ozon gases are also other hazardous for aquaculture and for human. Various chemical compounds used in agriculture industry (herbicides, pesticides ) are also released in the aquatic environment. The level of contamination of water could be high and as they are soluble in water they are present in fish or mollusc (atrazine). Detergents are also hazardous for aquaculture. Fish as especially sensitive to some compounds such as detergent. They have specific effects on fish reproduction because they have ostrogenic effects. However for most of these compounds there is no accumulation in the food web and no specific accumulation in fish. As compared to persisting organic pollutants there are no environmental reservoirs of these compounds. Thus the risk of contamination of fish is mainly determined by the threshold given for tap water contamination. The contamination of fish and mollusc by chemicals from the oil industry is often pointed out due to accidental dumping of oil on the coast. The toxic compounds Poly-cyclic Aromatic Hydrocarbon (PAHs) share some of the characteristics of persisting organic pollutants as they are lipophilic and accumulated in aquatic organism of the food web up to fish. These compounds could be easily detected in fish products as they induce off-flavors. However oil and derivates “off flavors” could also be related to native compounds (petroleum-like odor due to dimethyl beta sulphate). The tainting of fish by some native compounds of aquatic environment such as geosmin or dimethyl isoborneol which induce “earthy”, musty flavors help to illustrate how soluble compounds when present in water could accumulate rapidly into fish and thus could contaminate fish products for relatively long periods. Other tainting of fish products by native compounds have been reported: iodoform, iodine flavor related to bromophenol and antiseptic like taint related to chlorophenol. Process and handling induced chemical hazards include contamination of product due to improper use of chemicals and 181

pesticides during processing or improper labeling of products containing compounds such as bisulfites and other allergenic food additives. Histamine can also form in scombrotoxic fish if procedures are not in place during processing and handling to ensure proper temperature control. Several polycyclic aromatic sometimes reached levels at which it may be adequate to PAHs are known to be potential human carcinogens including benzo anthracene, chrysene, flouranthene. Aquaculture demonstrated in association with spoilage included operations and the farms that often adjoin them are carbon dioxide, sulphur dioxide and ammonia. Awareness usually dependant on properly used chemicals to minimize of the health hazards involved in the handling of problems and maximize harvests. Serious threats to industrial fish is important, particularly for those working aquaculture water come from herbicides used to control in the vicinity of fishing communities. The aquatic vegetation in fish ponds, runoff of pesticides, unintentionally added chemicals may include herbicides and fertilizers from fields adjoining aquaculture organochlorine pesticides, PCBs and other persistent ponds; and aquifer contamination due to pollution of the chemicals in feed, chemicals in construction materials and recharge water.

f. Microbial contaminats, Salmonella and transgenic fish Microbial contaminants are mostly bacteria and also virus and fungus that can infect both the aquatic animal and humans. Salmonella spp., Escherichia coli, Vibrio cholerae, Listeria monocytogenes and Streptococcus are well known microbial risks for aquaculture foods. Streptococcus iniae has caused infections in the hands of fish. Vibrio spp. from handling live tilapia Mycobacterium marinum found on both cultured and wild fishery products has caused severe wound infections in fishery workers. Edwarsiella tarda and Aeromonas spp. can be found in aquaculture ponds and have been associated with infections in both fish and employees. Leptospira spp. can be transmitted to aquaculture operations through the urine of rodents. Hepatitis and norovirus can be found in raw molluscan shellfish and also in foods cross-contaminated during processing through sick workers and by improper employee sanitation practices. Salmonella spp. and Listeria monoctytogenes are found in aquaculture ponds and on many raw fishery products. In addition, products can also be 182

contaminated with these organisms during processing through poor sanitation and improper employee hygiene practices. Vibrio spp. are naturally occurring pathogens found in the growing waters associated with molluscan shellfish, and Vibrio spp. can also contaminate the outside surface of other fishery products posing health problems for employees who handle and process these fishery products. Table 2. Biological and chemical hazards associated with aquaculture products (Karunasagar, 2008) Known or potential hazard Biological agents Bacteria Vibrio vulnificus V. parahaemolyticus V. cholerae Salmonella Viruses Norovirus Hepatitis A virus Parasites Fish-borne trematodes (Opisthorchis viverrini, Clonorchis sinensis) Biotoxins Paralytic shellfish poisoning (PSP) Diarrhetic shellfish poisoning (DSP) Amnesic shellfish poisoning (ASP) Neurotoxic shellfish poisoning (NSP) Chemical agents Polychlorinated biphenyls (PCBs) Pesticides

Product likely to be affected

Epidemiologi cal evidence

Molluscan, shellfish Shellfish Fish and shellfish Fish and shellfish

Strong Strong Very weak Very weak

Molluscan, shellfish Molluscan, shellfish

Strong Strong



Molluscan, shellfish


Molluscan, shellfish


Molluscan, shellfish


Molluscan, shellfish


Finfish and shellfish


Finfish and shellfish

Data lacking

Transgenic fish is another hazardous materials for human. The most common and hazardous transgenic fish have been classified as hazardous in cyanobacteria terms of food safety because of their potential are the producers of microcystins. Considering the levels of growth hormone (GH) and insulin-like growth factor (IGF) high toxicity of anatoxin-a to humans and vertebrates in transgenic salmon. Discussion of the beside the potential harm to ecosystems, the presence of safety of the consumption of transgenic salmon 183

cyanobacteria should always be considered as a potential potentially containing elevated levels of GH and IGF. Allergenicity is probably the most common indication. Organisms such as Clostridium botulinum are a potential public health issue primarily for refrigerated fishery products stored and packaged under reduced oxygen conditions. Staphylococcus aureus can contaminate fishery products during processing due to improper employee hygiene practices. S. aureus can form a heat stable toxin during refrigerated storage of the finished product. Salmonella are the most important hazards for aquaculture products. Aquatic environments are the major reservoirs of Salmonella. Therefore, fishery products have been recognized as a major carrier of food-borne pathogens. They effects fresh fish, fish meal, oysters, farmed and imported frozen shrimp and froglegs can carry Salmonella sp., particularly if they are caught in areas contaminated with faecal pollution (prior to harvest and during harvest) or processed, packed, stored, distributed under unsanitary conditions and consumed raw or slightly cooked. Some reasons for contamination of aquaculture systems with Salmonella are: 

Non-point water run off: During rainfall events, increased run off of organic matter into ponds may occur and can contaminate the aquaculture system. Animals (domestic animals, frogs, rodents, birds, insects, reptiles, etc.): A variety of animal waste has been shown to be potential sources of Salmonella. Fertilization of ponds: In some aquaculture systems animal manures are used in ponds to stimulate the production of algae. The use of non-composted manures can lead to production systems being contaminated with Salmonella. Contaminated feeds: Improperly stored feed or feed prepared on a farm under poor hygienic conditions can be a source of Salmonella. Contaminated source water: The water used in growout ponds, cages or tanks can be contaminated with Salmonella through wildlife runoff, untreated domestic sewage, discharge from animal farms, etc. On farm primary processing: Aquaculture products can become contaminated with Salmonella through the use of unsanitary ice, water, containers, and poor hygienic handling practices. 184

Main control procedures of Salmonella in fish and fishery products are:  Control of the aquaculture farm which is the first link in the food safety,  Good hygienic practices during aquaculture production,  Biosecurity measures. Some control measures to minimize the risk of Salmonella contamination of aquaculture products according to FAO (2011): Farm location:  Farms should be secured from the entry of wild and domestic animals that may lead to the contamination of aquaculture products with Salmonella. Farm layout, equipment and design: Farm design and layout should be such that prevents cross contamination Equipment such as cages, nets and containers should be designed and constructed to allow for adequate cleaning and disinfection.  Septic tanks, toilet facilities and bathrooms/showers should be constructed and placed so drainage does not pose a risk of contamination of farm facilities. 

Source water:  Farm source water should be free from sewage contamination and suitable for aquaculture production.  Farms should have settling ponds or waste water treatment in place to condition the output water prior to discharge. Ice and water supply:  Potable or clean water is available and used in sufficient amount for harvest, handling and cleaning operations.  Ice should be manufactured using potable water and produced under sanitary conditions.  Ice should be handled and stored under good sanitary conditions which precludes the risk for contamination. Harvesting:  Harvesting equipment and utensils easy to clean and disinfect and kept in clean condition. 185

  

Harvesting is planned in advance to avoid time/temperature abuse. Aquaculture products should be hygienically handled. Records on harvesting are maintained for traceability.

On farm post-harvest handling:  Utensils and equipment for handling and holding of aquaculture products is maintained in a clean condition.  Aquaculture products are cooled down quickly and maintained at temperatures approaching that of melting ice.  Operations such as sorting, weighing, washing, drainage, etc., are carried out quickly and hygienically.  All additives and chemicals (disinfectants, cleaning agents, etc) used in post-harvest aquaculture products should be approved by the national competent authority. Transport of aquaculture products from farm:  Transport is carried out in easy to clean and clean facilities (boxes, containers, etc.).  Conditions of transport should not allow contamination from surroundings (e.g. dust, soil, water, oil, chemicals, etc.).  Aquaculture products are transported in containers with ice or with, in sufficient amounts to ensure temperature around 0ºC in all products and during the whole period of transport. Employee health:  Staff should be medically fit to work and should be screened regularly to determine carriers of Salmonella.

Methods have been developed to control contamination of proceed fishery products with Salmonella are: 1. Physical control: Cooking: Application of heat is one of the simplest and most effective methods of eliminating pathogens from food. Heat application of 90°C for 1.5 minutes. in the center for mollusc and 99– 100°C for 3–4 min. for shellfish are accepted as safe processes before consumption. These temperatures are sufficient for the destruction of vegetative forms of the pathogens. Refrigeration: Refrigeration and freezing are well-known techniques for extending the shelf-life of food products. These processes lower the temperature to levels at which bacterial metabolic 186

processes are stopped and the rates of chemical and biochemical reactions reduced. Although most Salmonella serotypes are unable to grow at refrigeration temperatures, the organismis can be prevented holding chilled fishery products below 4.4°C. Worldwide, the most common cause of foodborne salmonellosis is Salmonella typhimurium. The minimum growth temperature reported for this species is 6.2°C. Thus, proper refrigeration will prevent growth of S. Typhimurium. Irradiation: The irradiation of fishery products is a physical treatment involving direct exposure to electron or electromagnetic rays, for their long time preservation and improvement of quality and safety. Irradiation of food has been legally allowed in many countries and the WHO has sanctioned radiation of up to 7.0 kilo Gray (kGy) as safe. This process is one of the most effective methods for decontaminating both the surface and deep muscle of fresh meat. The alteration in pathogen population as a result of irradiation depends on the dose of irradiation, storage temperature, packaging conditions and fish species. It was shown that Salmonella on frozen shrimp copletely eliminated when irradiated at 4.0 kGy. Similarly it is also reported that doses of 4.0–5.0 kGy were required to reduce the numbers of S. typhimurium on shrimp by 6.0 log cycles. Low-dose gamma irradiation (especially 3 kGy) can be applied for microbial control and the safety of rainbow trout and shelf life extension in frozen state. The irridation doses are also reported in the range 1.5–2.0 kGy effectively control all pathogenic bacteria tested in shellfish except Salmonella spp., particularly, S. enteritidis, which requires 3.0 kGy. Similarly to achieve safety levels against Salmonella spp., particularly S. enteritidis, in raw oysters, a dose of 3.0 kGy is recommended. As a results although irradiation appears to be effective in eliminating pathogens in fishery product, there is an unsubstantiated view amongst the public that food irradiation is unsafe and undesirable. There is also evidence some that irradiation may reduce the nutritional value of some foods by the destruction of aromatic amino acids and producing rancidity and offodours Modified atmosphere packaging (MAP): Modifed atmosphere packaging (MAP) has been widely used for extending the shelf life of a wide variety of food, including fish and fish products since 1980. Packages are injected with carbon dioxide, nitrogen, and very small (0.4 percent) amounts of carbon monoxide. The effciency of MAP in eliminating pathogens from fish depends on the gas mixture in MAP and, most importantly, the storage temperature. It was reported that modified atmosphere storage using 50% carbon dioxide/10% oxygen dose effectively reduce the growth rate of S. typhimurium, but it 187

cannot, in the absence of proper refrigeration, be relied upon to prevent salmonellosis. High-pressure processing (HPP) and superheated steam drying (SSD): High-pressure processing is an emerging non-thermal process that can be used to destroy pathogenic microorganisms in seafood without greatly affecting the quality of the product. In addition to improving the safety of shrimp, HPP has also been demonstrated to extend shrimp shelf-life. Shrimp are generally spoiled by Gramnegative bacteria, which tend to be relatively pressure sensitive due to their cell wall structure and HPP may therefore prove to be a valuable processing technology for shrimp.

2. Chemical control: The use of antimicrobial agents: Chlorine is the decontaminating agent most widely used to kill pathogenic microorganisms in the seafood industry. It is used to disinfect water used in the process (such as thawing frozen products), washing raw materials and in making ice for chilling fishery products. Commonly used chlorine compounds are liquid chlorine solution and hypochlorite. More recently chlorine dioxide (ClO2) and electrolyzed oxidizing (EO) water have also been used for this purpose. Specifically, chlorine dioxide has been recognized as a bactericidal, viricidal and fungicidal agent and is widely used in Europe and US as an alternative to chlorine and hypochlorite. In addition, EO water has also been shown to possess strong bactericidal activity against various foodborne pathogens. Both gaseous and dissolved forms of ozone are approved to be used as antimicrobial agents by the food industry, including the seafood industry. There are investigations on the effect of 2% ozonated saline (5.2 mg ozone/L, 5째C) on the inactivation of nine bacterial strains (including S. typhimurium) in shrimp meat. Findings showed that S. typhimurium was the most resistant of the species tested, with only 0.1 log cycle reductions. Lactate is considered to be an effective additional hurdle against the growth of contamination flora and pathogens such as Salmonella and it is used in the further processed fish industry. Storage and processing: Apart from microbial contamination, storage of aquatic products is associated with production of oxidative compounds. However, farmed fish for which storage and distribution could be easily controlled do not share the same risks as wild fish. Some process such as smoking induce specific risk of contamination of products. The composition of smoke contained poly-cyclic aromatic 188

hydrocarbon compounds such as benzopyrenes. The level of contamination is however low with industrial smoking for which smoke composition and smoking condition are controlled compared to artisanal smoking. There are however higher risk of contamination with electrolytic smoking, new methods of smoking.

Risks from fish contaminants to human Aquafoods could be contaminated as wild aquatic products by organic persistent pollutants and heavy metals coming from the environment. The risk of contamination depends on origin of the contaminants and on the fish species. There is however an increase incidence with heavy metals and new pesticides and a decrease incidence with classical environmental contaminants such as DDT and PCBs. The incidence of contamination by dioxins compounds could be considered as stable. There is also a risk of combined contamination by different classes of pollutants. Aquaculture products are especially exposed to contamination as aquaculture is concentrated on the sea shore, on lakes or on river which collect contamination from all the source. Contamination of aquaculture products could be limited by the control of foodstuffs and the control of environment. In the open seas, which are still almost unaffected by pollution, fish mostly carry only the natural burden of these inorganic chemicals. However, in heavily polluted areas, in waters that have insufficient exchange with the Worldâ&#x20AC;&#x2122;s oceans (e.g. the Baltic Sea and the Mediterranean Sea), in estuaries, in rivers and especially in locations that are close to industrial sites, these elements can be found at concentrations that exceed the natural load. The levels of these chemicals in fish intended for human consumption are low and probably below levels likely to affect human health. Nevertheless, they can be of potential concern for populations for whom fish constitutes a major part of the diet and for pregnant and nursing women and young children who consume substantial quantities of oily fish. These concerns can only be clarified if updated and focused risk assessments are conducted. These elements are present naturally in fish and seafood, some consumers regard their presence even at minimal levels as a hazard to health. The health value of aquaculture product is determined primarily by contaminants from biological origin and by pathogens organisms and secondarily by chemical contaminants. However for aquaculture 189

product the acceptability of this chemical risk is low compared to that of the classic hygienic risk. Hazard is a biological, chemical, or physical agent with the potential to cause an adverse health effect. Fish grown in excreta-fertilized or wastewater ponds may be contaminated with pathogens. Transgenic fish is hazardous because of their potential allergenicity and toxicity. Fish muscle can hold different concentration of mercury representing health risk to fertile women. Cadmium and lead concentrations are higher in fish scales and vertebral column than in the other parts of the fish. The major sources of food safety challenges in aquaculture are:  Environmental, chemical and microbial contaminations,  Veterinary drugs for fish infection and diseases,  Improper use of chemicals,  Use of genetically modified organisms (GMOs), and improper husbandry and hygiene practices. Regulation EC 1881/2006 sets maximum levels for contaminant in food to be placed on the EU market. The aim of the Regulation is to quarantee food safety in the EU by setting acceptible levels of contaminants in food. The fallowing contaminants are covered by the legislation and further divided into the subgroups:  Nitrates,  Mycotoxins (aflatoxins, ochratoxin A, patulin, Fusarium mycotoxins: Deoxynivalenol (DON), zearalenon,fumonisins, and T-2 and HT-2 toxins),  Metals (lead, cadmium, mercury, inorganic tin),  3-Monochloropropane-1,2-diol (3-MCPD),  Dioxin and PCBs,  Polycyclic aromatic hydrocarbons (PAH),  Melamine and its structural analogues.

FAO and WHO revised the guideline for mercury in fish to 1.6 micrograms of methyl mercury intake per day per kilogram of body weight, nearly half the original guideline of 3.3 micrograms in 2003. For organic pollutants in salmon, concentrations of 14 chlororganic compounds in farmed and wild salmon were examined. Each of these compounds is thought to cause cancer. The study revealed that all the substances tested were present in higher concentrations in farmed salmon than wild salmon. This applied in particular to fish produced on European farms. 190

Legislations for food safety in major prime markets of fish in EU are aimed at regulating against these challenges. However, these food safety issues may have not applied in developing countries. Inspection and certification of aquaculture farms and application of Hazard Analysis and Critical Control Points (HACCP) and Good Aquaculture Practices (GAqPs) have been recommended as good approaches to decrease the potential food hazards in aquaculture feeds and products. These approaches are as well incorporated in international regulations and those applying to producers and traders in EU to prevent production and trade of unsafe food products. The developing countries that plan to export their aquaculture products to developed countries have to comply with the requirements in importing countries.

List and address of EU decisions, directives, regulations and useful links for the legislations on aquaculture and aquaculture products ď&#x201A;ˇ

Decisions: Decision 97/747, Decision 2002657, Decision 2003/181, Decision 2004/25, Decision 2005/34/EC, Decision 2011/690


Directives: Directive 91/67/EEC, Directive 93/53/EEC, Directive 95/70/EEC, Directive 96/22, Directive 96/23, Directive 2006/88/EC, Directive 2008/53/EC  Regulations: Regulation 1831/2003, Regulation 136/2004, Regulation 396/2005, Regulation 1881/2006, Regulation 708/2007, Regulation 156/2008, Regulation 470/2009, Regulation 710/2009, Regulation 37/2010.  Useful links-web sites: pdf 2013_229_en.pdf nts_non_eu.pdf and_packaging/ htm ster_feed_additives_1831-03.pdf 20100701: EN:PDF

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IX. Sanitation, Biosecurity, and Applying HACCP for Fish Farming to Product Safety Authors: Prof. Dr. Imre Mucsi, György Lódi, János Sztanó Food safety means that it is guaranteed that consumers’ health will not be endangered during the whole process of the production and distribution of food, if it is prepared and consumed according to its purpose. Food safety is a system made by several creators and always refers to a given operation or action specifically. There are no factories with the same food safety. Food hygiene is a requirement system that corresponds to the fitness for human consumption in all stages of production, processing and distribution of food. It also refers to the control of infections and other diseases spread by foodstuffs. Food production places can be established where the protection of workers, products and the environment is provided. Furthermore, the architectural, technical, technological, environmental, sanitarian, animal health and food hygienic conditions should be provided relating to the place/room and the operation of applied machines, instruments, equipment. The prevention and control of food originated diseases are the basis of food safety. The ingredients of food are its quality features. When food starts spoiling, its natural ingredients begin to release some decomposition products that may be harmful for human health, so they probably endanger food safety. Food cannot be accepted if food safety or food quality differs from the standards. Previously, the control tended towards the technological progress and process of food production. As a result of this, defective producing process may exist for a long time so consumers might get some defective or unsafe products. That is why a requirement has been created that says: those technologies and working processes are not acceptable in the aspect of food hygiene in which the contamination of pathogens, their survival or proliferation occurs. A working process with the appropriate control system could provide such food production that does not endanger human health and suitable for human consumption. It can be applied best with the help 197

of “Good Hygienic Practice”. Applying Good Hygienic Practice provides to observe the appropriate operational and technological rules. The appropriate operation means the suitability of the installation, the buildings and the equipment. It also means that when technologies are being developed and run the required rules should be used in order to create safe products. The “Good Manufacturing Practice” rules include these activities. Based on the Good Manufacturing Practice and the Good Hygienic Practice and observe the sanitarian and food hygienic rules, a producing system can be developed that results food safety. This producing system is called “Hazard Analysis and Critical Control Point-system – HACCP” The HAACP defines, evaluates and controls those hazards that would be significant in the aspect of food safety.

HACCP in aquaculture Elements of HACCP       

Identifying and considering hazards, classifying them based on their risk. Selecting critical control points where hazard can be prevented or decreased. Specifying critical limits. Selecting and using methods for monitoring control of critical limits. Corrective actions at the control points. Verifying the effective operation of the system. Documentation that provides the actions and reports suitable for system rules.

Logical sequence of HACCP analysis Forming HACCP groups – it should consist a technologist who has the knowledge of the given technology, a specialist who is experienced in economics, a member who is expert in food microbiology, food hygiene and sanitation and a chemist. Application field, product description – it should be determined what products or product groups is HAACP system applied for. On 198

one hand – in the aspect of profession - , it is expedient, on the other hand – concerning the perspicuity of the system – it is necessary to separate the primary production and product production. The analysis of HACCP application should be carried out for a given operation, technology or product. The product description should contain the exact name of the product, its outside characteristics and its planned usage. Definition for application – in primary product production of food, it is important to evaluate during hazard analysis whether pathogen transaction occurs through primary materials, or not. Drawing and confirming a flow chart – it is drawn by the HACCP team. Each step of the action must be represented in it. The flow chart gives information about fish, materials, feeds etc. introduced into the factory until the final product leaves it. A schematic diagram of the factory completes the flow chart. Make sure that each action has been determined. List of hazards, their analysis – the list should be compared to the technological steps and the flow chart. The analysis of hazards should be carried out and the method of the control should be determined. The hazard analysis is the first element in HACCP. The satisfactory hazard analysis requires scientific background. That accepted level of hazard prevention or reduction should be analyzed which are inevitable for food safety. Potential hazards should be grouped together such as biological, chemical and physical hazards. The groups should be summarized separately after having examined and evaluated of the possible occurrence of potential hazards. Definition for critical control points – this is the second element of HACCP. The actions by the critical points have dominant significance in prevention, elimination or reduction to an acceptable level of food safety hazard. Critical points and technological steps should be examined whether they are able to preserve safety or not. If one of the steps is unsuitable for overwhelming hazards, the process (or the product itself) must be changed, or an earlier or a later technological point must be changed. Setting up a “decision tree” that can be changed depending on the activity, may be helpful. The decision tree contains four questions and the answers for them in a systemized sequence.


“Are there any control methods?” is the first question that refers to whether it is possible to perform an analysis in the specific technological stage or somewhere else in the process in order to determine the hazard, or not. If the answer is “yes” the decision tree shows the reference to the prevention methods that can be used and evaluated in the second question. If the answer is “no”, there are no control or preventive methods in the given step. It indicates that the analysis should be performed in the previous or the next step of the process to prevent hazards in the technology. The second question refers to whether it is possible to eliminate or reduce hazards to an acceptable level in the given step, or not. If the answer is “yes”, hazard can be eliminated or reduced to an acceptable level, so this step becomes a critical control point. If the answer is “no”, proceed to the next question. The third question is: may some contamination occur that can cause hazard or disorder for which the answer should be given carefully? In order to answer this question, it is required to collect data and perform a risk analysis. If increase in hazard detected in the result, so the answer is “yes”, then proceed to the next question. If the answer is “no”, the process is not a critical point. The fourth question is: whether the next step will eliminate the hazard, or not? This is very important according to the final result because if it was unsuccessful to eliminate hazard in the technological steps so far and there is no action expected in the future with which it can be carried out and the answer is “no”, so hazard should be controlled and eliminated in the present stage of process. Accordingly, the given place counts as a critical control point. Determination of critical end values at control points – threshold limit values should be determined at each control point. Threshold limit values separate the acceptable things from the unacceptable ones. The critical threshold limit value means a frame or a limit that can be used to determine or confirm that a process produces a safe product. Critical threshold limit values should meet the requirements of the public authority regulations, the standards and other scientific data. Monitoring system at the control points – basically, it means the analysis and monitoring of the critical threshold limit values. This activity should be able to reveal the absence of control. The monitoring can be continuous and periodical, however, the latter one should be sufficient for the control of HACCP. The HACCP plan 200

should contain the names of those personnel who are responsible for monitoring. They need to have the required skills, the knowledge of CCP monitoring methods, the knowledge of the objectives and tasks concerning HACCP and the required authority to carry out the control of the HACCP plan. The responsible person must report the deviations from the critical threshold limit values in order to ensure the correctional action in time. Definition for correctional action â&#x20AC;&#x201C; it serves the improvement of the detected deficiencies of the critical control points. The correctional actions concerning the deviations should be specified in the HACCP plan and the work manager is responsible for it. The correctional action must be performed by an expert. Make sure of the efficiency of the correctional action and verify it. The correctional action should be documented and a report should be drafted about it. The report should contain: the name of the product, the time when the correction happened, the reason of deviation, the characteristics and the number of the examinations and the nature of the deviation. Verifying action, documentation and reports â&#x20AC;&#x201C; verifying and auditing methods, procedures, tests include the randomly selected samples and examinations that determine whether the HACCP system works properly, or not. During the validation of HACCP plan, the hazard analysis, the determination of critical control points, the verification of critical end values, their adequacy with the level of science and the requirements are reviewed. The HACCP plan specifies the periodical verifying action, but it becomes important especially when changes occur in food safety conditions. A report must be drafted about the verifying action and its results. There are four major types of documents concerning HACCP: 1. Documents that support performing HACCP, 2. Documents made in the HACCP system, 3. Documents of the applied methods and actions, 4. The employee educating program. The HACCP system is consisted of the total number of documents and reports that contains the success of effectiveness and the action and fact of verification at the same time.


Hazard analysis in fish breeding, production and table fish production


The validity of the HACCP system spreads over every area of the fish farm such as the breeding-, producing-, storage- and wintering ponds. If the water supply of the ponds is not equal, the fish farm consists of several different epidemiologic pond units. In this case, the validity of the requirements spreads over all of the epidemiologic pond units. Critical points (CCP) that have been found real during identifying hazards in the fish farm are the following:  The quality of the incoming water (chemical and microbiological adequacy),  Do the ingredients of feeds that get into the water during feeding suitable for the safe food basis production (does the ingredients of feeds contain heavy metals, chemical foreign matters?),  Do some residues remain in the organism of fish when using drugs and chemicals to avoid or treat possible diseases?  Does the manure used for fertilizing ponds contain chemical materials? In order to avert hazard, the received manure should be controlled. The water quality and the possible feed contamination with foreign matter are controlled by a monitoring system. The medicinal treatment should be performed under control and in a specified way. Applying HACCP system is a help to the official food control that ensures the confidence for foods of the customers in the domestic trade and the healthy nourishment.


Table 1. Hazard analysis in fish breeding, fish production and table fish production Operation

Contingen cy

Origin of contingenc y Bird scar Environment Water birds Environment

Control action

Pond environment

Infection Parasites Feces Hook

Machineries, equipments /boat engine, pond mower/

Chemical pollution of the pond

Engine-oil or fuel flow



Wrong personal hygiene

Taking over feed

Presence of chemical foreign matter (CCP) Presence of mould, mycotoxin Microbe and mould proliferatio n

Cultivation of plants Storing or soil contaminatio n

Supplier declaration about the applied chemicals Quality certificate

Quality date expiration Wrong storage

Granary keeper, Pond unit manager

Taking over veterinary drugs and chemicals

Change in the ingredients Change in the ingredients

High temperature during transportatio n Quality date expiration

Appropriate marking and documenting Providing storage conditions Providing the required temperature Expiration date control

Storage of veterinary drugs and chemicals

Change in the ingredients Change in the ingredients Misusage

Wrong storage temperature Quality date expiration Combination of chemicals

Providing the required storage temperature Expiration date control Marking chemicals, their

Veterinaria n, Storekeep er, Pond unit manager

Storage of feeds


Bird scaring Pond disinfection with lime Bird scaring Bottom scan of ponds Permanent maintenance Use of environmentfriendly engineoils Pay attention to hygiene

Responsi ble people Pond unit manager

Technician engineer

Employee s, Pond unit manager, Factory doctor Pond unit manager, Feeding manager

Veterinaria n, Storekeep er

Incoming water

Taking over manure

Animal health control intervention

Disinfection of ponds, wintering places, nursery ponds

Waterfill Disinfection of fish containers

Chemical foreign matter (CCP) Microbiolo gical contaminat ion Presence of foreign chemical matter (CCP) Microbiolo gical contaminat ion Medicine and chemical residues (CCP)

Cultivation of plants, industrial pollution Pathogens in the incoming water

Chemical residue /lime hydrate, calcium hypochlorit e/ No hazard identified Contamina tion

Ignoring the safety and technological awaiting time /2 days/ after disinfection

Soaking fish in saline solution before transportation


Plankton selection

Chemical residue

Outplacement of spawns, transportation of table fish to

Hazard cannot be identified above

appropriate storage Continuous monitoring with laboratory tests Providing continuous waterflow and monitoring

Pond unit manager

Animal farms Animal farms

Supplierâ&#x20AC;&#x2122;s declaration about applied chemicals, monitoring Safe and controlled supplier sources

Pond unit manager, Veterinaria n

Ignoring awaiting time, Overdose

Keeping the required awaiting time, Appropriate registration of treatments Keeping safety and technological time

Veterinaria n, Pond unit manager

Residues from cleaning supplies Significant overdose of salt

Regular disinfection

Wrong dosage outside of the nursery pond

Treatments performed as required

Vehicle owner, Veterinaria n Pond unit manager, Vehicle owner, Veterinaria n Pond unit manager


Treatment performed by the requirements

Veterinaria n, Pond unit manager

the wintering place Outplacement of spawn sample Pond mowing


Bird scaring

Pond drainage Mud harrowing Harvest of advanced fries and one summer old spawns Harvest and selection of tablefish


Pondside sale

Hazard cannot be identified See machines above See machines above Hazard cannot be identified Contamina tion See machines above Hazard cannot be identified

Appearanc e of chemical substances

Technician engineer Technician engineer

Bird scar

Bird scaring

Pond unit manager Pond unit manager

Harvest, stress caused by mistreatment

Fast and careful harvest, Keeping the animal protection rules

Pond unit manager, Veterinaria n

See machines above Hazard cannot be identified

Transportation to fish processing factory

Appearanc e of stress hormones in the blood and the muscles

Wintering fish breeding

See incoming water

Pond unit manager, Technician

Oxygen shortage, stress

Keeping the rule of the temperature dependent maximum quantity of fish that can be transported to container, reducing the transportation time. Keeping the animal protection rules

Pond unit manager

Pond unit manager


References Biró G. – Biró Gy. (2000): Élelmiszer-biztonság. Táplálkozás-egészségügy. AGROINFORM Kiadó. Budapest. p. 124-204. Szegedfish Kft. (2002): HACCP Kézikönyv. Szeged. p. 2-24. Szegedfish Kft. (2002): HACCP Dokumentációk I-VI. Fejezet. Szeged. p. 292.


X. Fish Farming and Impact on Sustainable Environment / Ecosystem and Water Author: Luciana Levi Bettin, Gianluigi Rago, Dalmar Mohamed Ali

Despite the undeniable benefits of aquaculture such as the provision of good quality and accessible food for population, the activity is one of the most criticized worldwide, mainly because of the environmental impacts that have been and can be caused. Thus, the predominant and unavoidable question is: could aquaculture be a truly sustainable activity? Understanding sustainability as â&#x20AC;&#x153;the ability to meet the needs of the present without compromising the ability of the future generations to meet their own needsâ&#x20AC;?, many researchers, aquaculturists, and governmental instances have considered that a sustainable aquaculture is possible, but it depends on the way that the activity will be managed.

Why aquaculture is nonsustainable activity?



With or without valid arguments, aquaculture has been accused to be the cause of many environmental, social, economic, and inclusively esthetic problems. Ecosystems are not always as fragile as could be considered, instead, they have remarkable capacity of resiliency, and as long as basic processes are not irretrievably upset, ecosystems will continue to recycle and distribute energy. However, irreversible damages have been already caused due to inadequate management of the activity. The main negative impacts attributed to the activity are as follows: Destruction of natural ecosystems, in particular mangrove forests to construct aquaculture farms: The mangrove forests are 207

important ecosystems considered as the main source of organic matter to the coastal zone; they are also nursery areas for many aquatic species ecologically and/or economically important, as well as refuge or nesting areas for bird, reptiles, crustaceans, and other taxonomic groups. Mangroves are additionally accumulation sites for sediments, contaminants, nitrogen, carbon and offer protection against coastal erosion. Salinization/acidification of soils: Aquaculture farms are sometimes abandoned by multiple problems (operative, economic, sanitary, and etc.), and the soil from those former farms remain hypersaline, acid and eroded. Therefore, those soils cannot be used for agricultural purposes and are unusable for long periods. In addition, the application of lime and other chemicals used in aquaculture to treat the soil can also modify its physicochemical characteristics, which could aggravate the problem. Pollution of water for human consumption: Although few studies have been conducted in relation with such topic, there are some signs indicating that inland aquaculture has been responsible for the deterioration of water bodies used for human consumption. For instance, preliminary calculations revealed that an intensive aquaculture system farming three tons of freshwater fish can be compared, in respect to waste generation, to a community of around 240 inhabitants. Although most of the aquaculture farms produce marine species, there is a growing sector of aquaculture farms producing freshwater species, which is a point of concern considering the above information. Eutrophication and nitrification of effluent receiving ecosystems: The eutrophication or organic enrichment of water column is mainly produced by nonconsumed feed (especially due to overfeeding), lixiviation of aquaculture feedstuffs, decomposition of died organisms, and overfertilization. It is well documented that from the total nitrogen supplemented to the cultured organisms, only 20 to 50% is retained as biomass by the farmed organisms, while the rest is incorporated into the water column or sediment, and eventually discharged in the effluents toward the receiving ecosystems, causing diverse impacts such as phytoplankton blooms (sometimes of toxic microalgaes, such as red tides), burring, and death of benthic organisms, as well as undesirable odors and the presence of pathogens in the discharge sites. 208

The impact may be more or less severe depending on some factors such as the intensification of the system (density of organisms), which is directly related to the amount of feed supplied. Ecological impacts in natural ecosystems because of the introduction of exotic species: The main reported problems concerning the negative impacts of the â&#x20AC;&#x153;biological contaminationâ&#x20AC;? for the introduction of exotic aquacultural species on the native populations are the displacement of native species, competition for space and food, and pathogens spread. To cite an example, recent reports have revealed a parasite transmission of sea lice from captive to wild salmon. Ecological impacts caused by inadequate medication practices: Farmers usually expose their cultured organisms to medication regimes, for different purposes such as avoiding disease outbreaks and improving growth performance. However, monitoring studies have detected low or high levels of a wide range of pharmaceuticals, including hormones, steroids, antibiotics, and parasiticides, in soils, surface waters, and groundwaters. These chemicals have caused imbalances in the different ecosystems. In particular, the use of hormones in aquaculture and its environmental implications have been scarcely studied. Changes on landscape and hydrological patterns: The agricultural and aquacultural activities have contributed to the degradation of ecosystems including important modification on landscape. The construction of shrimp farms in the river beds has modified the hydrological patterns in many regions of the world with the consequent impacts on the regional ecosystems and the local weather. Trapping and killing of eggs, larvae, juveniles, and adults of diverse organisms: It has been estimated that, for each million of shrimp postlarvae farmed, four to seven millions of other organisms are killed by trapping in the nets of farms inlet. Negative effect on fisheries: Although aquaculture has been proclaimed as a solution to avoid overfishing, it has contributed in more or less proportion to the fisheries collapse. Fishermen who work in places near to aquaculture farms argue that the contamination produced by farms has decreased the population of aquatic 209

organisms and in consequence their volume captures. Additionally, another problem of similar magnitude is the extremely high aquacultureâ&#x20AC;&#x2122;s dependence of fishmeal and fish oil, which could be another nonsustainable practice in aquaculture. Some other accusations: Some other accusations for aquaculture include the production of fish and shellfish with high concentrations of toxins and/or heavy metals; genetic pollution and infestation of nondesirable phytoplankton and/or zooplankton species.

What to do for a sustainable aquaculture? Many strategies have been suggested, evaluated, and/or proven in order to advance in the sustainability of aquaculture. Basically, all of them respond to the criticisms and are possible solutions to the problems attributed to the activity. The main aspects that have to be performed to advance toward such goal are the correct selection of the farming sites and species; the implementation of the most adequate culture system; use of the best feed and feeding practices; the use of bioremediation systems; decreasing the dependence of fishmeal and fish oil; adequate management of the effluents; achieving certification of compliance with sustainability; improving research and legislation related to evaluation and solutions for aquaculture impacts. Since supplemental feed is considered the main source of contamination of aquaculture systems and effluent receiving ecosystems, the improvement of these feed, as well as the feeding, strategies could be considered as an important part of the solution for a sustainable aquaculture. A common practice of world aquaculture is the use of diets with protein contents higher than those required, thus affecting not only the price of the feed but also increasing the pollution potential, considering that protein catabolism produces ammonium nitrogen as the main metabolite. Regarding nutrient quality, it is important to use ingredients with high digestibility; the low digestibility of ingredients (protein, lipid, carbohydrate) is partially the responsible for a low retention of those nutrients in the farmed organisms and their increase in the water column and sediment, augmenting the polluting potential. One of the most important causes of nutrient losses of aquafeeds is the low hydrostability, which provoke fast disintegration and lixiviation, 210

decreasing the nutrient incorporation efficiency by the farmed organisms and increasing the concentration in the water column. Fishes are faster swimmers and can consume a formulated feed within minutes, but crustaceans are usually less active and can consume the formulated feed within minutes or even hours. The hydrostability of feedstuffs can be improved by incorporation of effective binders and/or for the use of special fabrication processes. It is necessary to produce feeds which can be consumed as soon as possible to avoid nutrient losses. This is possible with the incorporation of effective attractants and improving the palatability with ingredients such as fish oils and others. Many of these ingredients have been sufficiently proven. Regarding to the feeding strategies some important advances have been achieved but there are yet much more to advance in aspects such as forms to supply the feed, adjustment of the ration, and frequency of feeding. The use of feeding trays and the increase of feeding frequency have been demonstrated to diminish the pollution potential of the effluents in shrimp farms; however these strategies are suitable only for high-intensity systems (intensive or superintensive), but not economically feasible for extensive, semiextensive of semiintensive systems. The promotion, management, and rational utilization of natural feed, including microorganisms (biofilm, biofloc), are considered as a promising strategy for the culture of shrimp, fishes, and mollusks. Some authors have successfully enhanced the production of zooplankton and benthos in shrimp ponds and demonstrated their great contribution not only in the production response, but also in the nutritional, sanitary, and immune condition of the farmed organisms. Additionally, the use and contribution of microorganisms associated to biofilms and bioflocs for the nutrition of farmed organisms have been also documented. Such practice may also decrease the dependence of fishmeal and fish oil; however other strategies such as the use of plant ingredients and the use of bioflocflour have been tested and proposed to substitute at different rates the fishmeal in formulated feeds. The practice of subfeeding or intermittent-feeding regimes is a strategy aimed to achieve average growth performances in aquatic organisms, but supplying significantly lower amounts of formulated feed. Such alternative takes advantage of the compensatory growth process of shrimp and crustaceans. The adequate management of effluents is indubitably one of the central aspects to consider for a sustainable aquaculture. Diverse 211

strategies have been proven or suggested to minimize the environmental impacts of effluents. The most promising are settling lagoons, treatments with septic tanks, the implementation of systems with low or zero water exchange, the utilization of recirculation systems, the use of mangrove forests as sinks for nutrients, organic matter, and contaminants, the polyculture or integrated multitrophic aquaculture systems, and the bioremediation.

Possible solutions Experience has shown that improved coordination and management of development initiatives at sectoral, eco-regional and local levels can contribute to more environmentally sustainable development of aquaculture. Precautionary approaches are advocated for many aquaculture practices, particularly as regards the introduction and use of alien species. Special consideration must be given to better management of aquaculture developments affecting sensitive habitats, such as, for example, estuaries, mangroves, wetlands, riparian fauna and vegetation, or specific breeding and nursery grounds. The benefits of applying and promoting precautionary approaches become more evident where environmental data and related information on farming performance and environmental effects have been generated. Development and application of Environmental Impact Assessments and regular environmental monitoring can help provide the information needed for effective environmental management measures targeting individual farms, farm clusters, or a given sector producing a particular commodity, for example, shrimp, salmon, mussels, etc. Given that particular attention should be given to the collection of wild seeds, there continues to be significant scope for the development and improvement of hatchery techniques and broodstrock management, and related application of genetic and biotechnological methods, for safe reproduction and supply of aquaculture seeds. Generally, improved husbandry is very important, and better onfarm practices are required, particularly with regard to the selection


and use of feeds and fertilizers, and the safe and effective application of drugs and chemicals. Very often there are significant opportunities to better manage the water resources utilized as well as the wastes generated. Better use of available resources, emphasizing technical and economic efficiency, will help improve farm management. Particular attention should be given to large-scale, intensive, high-input systems. More intensive production systems actually can help reducing environmental and resource use problems. For example, extensive systems require large areas (space) of land (or water), potentially contributing to degradation of habitat in some areas. More intensive systems require less area, and can be more efficient in terms of resource use and production. A good example is shrimp farming: the majority of shrimp farms are extensive or semi-intensive, and the highly publicized problems of wetland degradation are often associated with extensive systems. Intensive systems obviously may create pollution problems due to high inputs and high outputs (wastes), but this very much depends on the very site-specific characteristics of a given location, and, in particular, of the assimilative or environmental capacity of the recipient water body. In practice, effectiveness of measures and efficiency in management at the production level may well be very important criteria for consideration.

Action taken Above issues have been recognized in the past, and significant information on environmental interactions of aquaculture is available or continues to be generated. A number of conferences, expert workshops and policy meetings, have been held to address the issues, and to develop technical guidelines and policy advice. A variety of projects have been implemented to provide assistance in the promotion of environmental assessment and management of aquaculture development. Besides technological advances, there have also been efforts to develop and improve legal and institutional frameworks in support of sustainable aquaculture. Increasingly, there are also initiatives by associations and organizations of the private aquaculture sector aiming at improved environmental performance and better public image.


Outlook Development and improvement of legal and institutional frameworks will continue, but issues of enforcement and monitoring of compliance with environmental regulations, especially requirements for EIA and regular environmental monitoring, are still to be addressed in many countries. Planning and management for environmentally-sustainable development of aquaculture will continue to require a substantial input of expertise in environmental assessment and management, including land and water use management, participatory consensus-building involving environmental and consumer advocacy groups and private sector representation, and policy development, based on analyses of institutional, economic and market issues. National as well as international private sector associations and organizations involving aquaculture producers, but sometimes also suppliers, retailers, etc, are developing, with common interests focussing on specific commodities, or markets. There are private sector initiatives promoting the development of selfregulatory voluntary codes of practice, guidelines for good or best practices, etc. These private sector groups are promoting better environmental performance within their respective sectors and membership, often with a view to improve public perception of their profession, and to diversify opportunities for marketing their products. There are trends of focusing environmental management measures on the performance of the farming process itself, which aim to reduce the generation and release of wastes, especially in form of effluent loadings, sludge, deposits, potentially harmful substances. While these efforts are extremely important, it is likely that in future calls will be growing for environmental assessment and monitoring of outcomes or effectiveness of the measures taken, i.e. the need to show that the measures put in place actually did have a tangible effect in the environment. Environmental indicators reflecting the actual ecological response (for example, by habitats, communities or populations) will likely be considered more regularly to achieve the environmental quality objectives set. Issues of food safety of aquaculture products, which concern public health authorities and affect consumer acceptance in general, are receiving growing attention. It can be expected that there will be increasing concerns wit regard to issues of environmental impacts by aquaculture farms affecting the products of neighbouring farms, selfpollution, and environmental impacts by non-aquaculturists affecting 214

the quality and safety of both aquaculture products as well as of aquaculture supplies, especially feeds and feed ingredients.

References World Aquaculture: Environmental Impacts and Troubleshooting Alternatives, Marcel Martinez-Porchas and Luis R. Martinez-Cordova, The Scientific World Journal, Volume 2012 (2012), Article ID 389623, 9 pages., Review Article:, Creative Commons Attribution Licence.


XI. Fisheries Products and Human Health: a) Fish and Heart Author: Dr. Serkan Saygı

b) Fish (Omega-3 Fatty Acids) and Eye Health Author: Dr. Arzu Taşkıran Çömez

a) Fish and Heart Deaths related to cardiovascular diseases vary from country to country; however, it is the primary death reason to be encountered all around the world. It has been analyzed that death rates related to cardiovascular diseases especially in developing countries are much more than total deaths related to other reasons. Prospective projections being made indicate that deaths related to cardiovascular diseases continue to be the most considerable death reason in 2020, too. Although remarkable developments in medical treatment extend lifetimes of patients, they are not able to make a significant contribution into incidence reduction of heart diseases. At this point, it has gained significance within years to develop measures preventing occurrence of the diseases, which has been defined as primary prevention. Relationship between foods consumed by person and cardiovascular diseases has been primary subject that medicine has dealt with mostly for many years. Especially fat content in diet and relationship between progress of cardiovascular diseases and death have always engaged researchers. Many analyses and studies made for many years related to heart diseases and its mostly observed type; coronary artery disease have indicated that fat contents of foods in personal diet, daily taken fat content and fat content of foods consumed may play role in occurrence and progress of coronary artery disease. These studies put forth negative effects of fat content in diet; on the other hand, other analyses indicate that not all animal fats may be harmful. In 1970s, two researchers have proved that incidence rates of cardiovascular diseases are too low in Greenland Eskimos consuming fatty fishes in great content. Especially, it has been observed and understood that fish content to be consumed is related to occurrence 216

of coronary artery disease and deaths connected to this. It has also been indicated in randomized observations and studies that on the contrary to red meat consumption; complications and deaths related to cardiovascular diseases decrease as long as consumed dietary fish content consumed increases. Herein, the most significant question coming to mind is which dietary part of consumed fish reflects protective effects. Particularly, it provides a clue for answer of this question that fish types having been consumed have been sea mammals rich in omega-3 fatty acid (FA) in studies and observations about Greenland Eskimos. Nowadays, it is known that protective effect referred to fish consumption about decreasing cardiovascular diseases is related to fat and FA content in fish. It will be very useful to tell primarily of fats and FAs in this text which we will examine and deal with relationship between fish consumption and heart diseases.

Fats and fatty acids Fats have been defined as soluble materials in organic solvents before; but now, this definition is unsatisfactory. Nowadays, fats are defined as small hydrophobic or amphipathic molecules that are formed by concentration of thioester and/or isoprene units partially or completely. Definition of fatty acids contains more complex chemical definitions. International Union of Pure and Applied Chemistry (IUPAC-IUB) has submitted a systemic definition for FAs. Accordingly, FAs are classified as per carbon atom numbers and number and position in accordance with carboxyl group of unsaturated FAs. However, more well-known and simplified definitions are used in dietary FAs instead of this complex definition. Cis FAs are defined by â&#x20AC;&#x2DC;n-minusâ&#x20AC;&#x2122; system in practice. In this definition, FA is named according to closeness of double bond to the last methyl area of its molecule. This situation expresses us how FAs such as n-3, n-6, n-9 are named and classified, which we use in practice. N- system is also named as omega- system in practical application. Additionally, another classification is the definition made according to double bond number of FA molecules, which is well-known in practice and provides us great convenience in defining fat content of foods. Definitions of FAs in this system are made like this: FAs not containing double bond are saturated, FAs containing single double bond are monounsaturated, FAs containing two or more double bonds are polyunsaturated. Source of saturated FAs is generally animal food 217

in diet and ruminant mammals. Sunflower seed oil, olive oil, vegetable oils, fish oil and various animal fats are rich in monounsaturated FAs. Polyunsaturated FAs are separated into 12 groups according to nsystem. However, two of the most remarkable ones for human nutrition are n-3 and n-6 FAs. Linoleic acid (LA, C18:2n-6) and alpha linoleic acid (ALA, C18:3n-3) are two significant n-3 and n-6 for human nutrition. Studies have indicated that mammals do not have enzymes to synthesize double bond on n-3 and n-6 positions of carbon chain. For this reason, humans are obliged to get these FAs within diet. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are formed by extension and desaturation of ALA. Despite the fact that they are not included in classification systematic mentioned above, omega-3 FAs statement that we use in practice are used especially in order to define these two significant n-3 FAs (EPA, DHA) obtained from fatty fishes in diet by humans. Fish oil is very rich in EPA and DHA that we will define as omega-3 FAs beginning from this part of the text. Well then, by which mechanisms do omega-3 FAs reflect positive biochemical actions referred to themselves? As we will mention shortly below, mechanisms of action belonging to omega-3 FAs have been enlightened considerably despite there are still unclear points.

Mechanism of actions of Omega 3 fatty acids on cardiovascular system Despite the fact that numerous researches and analyses have been made about possible positive cardio metabolic effects of Omega3 FAs, this subject still attracts researchersâ&#x20AC;&#x2122; attention. Disorders in blood lipid level, endothelial functions, low-grade inflammation, aggregation of platelets, and increase in blood pressure have great role in occurrence of coronary artery disease, heart attacks and ischemic strokes. It is thought that omega-3 FAs are responsible for many positive effects such as; Anti-inflammatory action, positive effect on blood lipid parameters, decrease in blood pressure, improvement of endothelial functions, decrease arrhythmia, decrease aggregation of platelets. As seen herein, omega-3 FAs are thought to prevent all of these mechanisms. Evidences manifest that omega-3 FAs reduces activation of low-grade inflammation in vessel. It is also thought that Omega-3 FAs perform this action by reducing arachidoric acid in platelet membrane and also reducing the levels of inflammation mediators to get synthesized related to arachidoric acid. 218

Embolism, heart attacks and strokes occur in accordance with aggregation of platelets in vessel. Evidences exist for the fact that Omega-3 FAs prevent aggregation of platelets, reducing synthesis of thromboxane A2 that plays role in aggregation of platelets. Sudden death is one of death reasons we often encounter in our daily lives. It has been known for a long time that heart attacks are the main cause of sudden deaths. Clinically known or unrecognized coronary heart disease already existing in humans causes a sudden arrhythmia (ventricular tachycardia/fibrillation) which causes to death if not treated in a short time. It is one of significant positive actions of Omega-3 FAs that it reduces sudden death rates. It is considered that Omega-3 FAs reduce arrhythmias to be occurred by acting functions of ion channels in cell membrane such as Ca, Na and K. Nowadays it is already known that vessel wall named as endothelium not only is tubule in which blood is circulated but also plays a significant role in occurrence of cardiovascular diseases and coronary artery disease. There are evidences for the fact that reduction in nitric oxide synthesis can be recovered by EPA, which is one of important indicators of endothelial dysfunction. Apart from all of these useful actions referred to Omega-3 FAs, actions of these molecules on blood lipid parameters are maybe the most evident and observable concrete positive action of Omega-3 FAs. This positive action has been reflected into our daily practise and also provided these molecules to be used as therapeutic agents. Omega-3 FAs does not make any change in total cholesterol and LDL cholesterol level which also named as bad cholesterol; on the other hand, it reduces blood level of triglyceride and very small lipoprotein remnants playing role in coronary artery disease pathogenesis. Cardio metabolic positive effects of Omega-3 FAs have been submitted in considerable part of researches made up to now. Nevertheless, some published researches have also existed, in which results are neutral or negative. These researches will be explained and mentioned below.

Studies about fish and heart diseases There are many studies related to fish consumption and cardiovascular diseases. Extensive studies and meta-analyses having been made have indicated that dietary omega-3 FAs in fish oil reduce coronary artery disease and sudden death. When studies are 219

reviewed, it is perceived that dietary omega-3 FAs have positive action for cardiovascular health. It is mentioned about different contents in studies, however dietary fish content is at least 1-2 portions per week or daily average is 20-30 grams fatty fish. Besides, it has also been observed and perceived to be an inverse relationship between fish consumption and risk factors for heart diseases depending on dose amount in some studie. It has been determined that the more weekly fish consumption increases the less risk factor occurs. Despite all of these positive results, there are also considerable studies suggesting that omega-3 diet or support capsules do not have any positive action on heart diseases. In a study which it is analyzed whether fish consumption has an action on fatal complications of coronary heart disease such as sudden death, coronary bypass, heart attack , it has been observed that intake of dietary sea origin omega-3 FA does not have any positive action on the last mentioned points. Dietary fish consumption does not have any significant action on death rates during 25 years-monitoring in EURAMIC (European Multicenter Case-Control Study on Antioxidants, Myocardial Infarction and Breast Cancer) study in which data from 7 different countries have been assessed. Additionally, it has also been observed that DHA content in adipose tissue that is an indicator for long-term fish consumption does not have any positive effect to prevent occurrence of heart attack. Considerable meta analyses have been published in recent years. Results of 20 studies have been assessed and action of omega-3 FA preparations on event risk has been analyzed, which may be occurred due to cardiovascular diseases in 68680 cases. It has been understood that Omega-3 FA preparations do not have any considerable action on death rates, cardiac death, heart attack, sudden death and stroke occurrence at the end of the study. Is omega-3 FA support useful in secondary prevention, in other words, in preventing heart attack complications that may occur again in cases with cardiovascular diseases? 20845 cases with cardiovascular disease have been analyzed in a new meta analysis. All of cases have gotten support of 1.7 grams/day EPA/DHA in average and they have been monitored for 2 years. But results are not satisfactory. It has been perceived in the study that omega-3 supportive therapy could not prevent complications that may occur due to cardiovascular disease. Some points are obliged to be mentioned particularly in assessing negative results arising in studies. First of all, we must know that each fish type does not contain DHA and EPA, in other words, omega-3 FA in same rates. In some 220

studies, it has been determined that positive action arising after fatty fish consumption cannot be observed within lean fish consumption in same content. Fish species rich in Omega-3 FAs EPA/DHA are defined as fatty fish and it is a necessity to prefer fish species rich in omega-3 FAs in diet especially such as; salmon, trout, sardine, anchovy, herring, tuna, mackerel. One of considerable points herein is the fact that omega-3 rates of fishes may vary in accordance with geographical conditions, aquaculture (farm, natural), seasons and cooking methods (Table 1). It is one of remarkable points in studies that studies made within fish diet have produced more positive results than supportive preparations containing omega-3 FA when the results are analyzed retrospectively. These results suggest that preparations containing fish oil cannot get metabolized so effectively as omega-3 FAs taken by dietary fish. Some researches made also support this idea. It has been indicated that intake of omega-3 FA by fish consumption is superior in accordance with supportive therapy. It has also been indicated that Serum EPA and DHA levels are higher within natural fish consumption per 1,2 gr/day than fish oil per 3 gr/day in supportive therapy. For this reason, it seems rational that intake of omega-3 FA is to be made by dietary fatty fish consumption method. Table 1. Fat Contents included in various fish species (Agricultural Research Service, 2012). Species

Total fat content, g

EPA*+DHA**, g

Salmon-farm Salmon-natural

2,359 1,723

1,966 1,436

Salmon-canned Herring

1,166 1,830

1,017 1,658

Sardine Anchovy-Europe

1,457 -

1,369 2,055

Mackerel-canned Trout-farm

1.334 0,824

1,230 0,733

*EPA: Eicosapentaenoic acid, **DHA: Docosahexaenoic acid

Is it possible if fish and fish oil consumption are harmful? There are numerous scientific and magazine articles about positive actions of fish and fish oil support on human health. However, we do not have enough data about possible harmful actions of extensive fish 221

consumption content and omega-3 FA supports. The greatest problems we may encounter in dietary fish consumption are toxic metals and materials cumulated in especially large volume fishes. Toxic materials such as methyl mercury, dioxin, and polychlorinat biphenyl may be cumulated in fish species that we can define such as large volume, fatty, old and predator. Polychlorinat biphenyl can be removed considerably by taking fish skins apart and cropping fatty parts. However, mercury cannot be removed since it cumulates in muscles. Fortunately, it is obtained and suggested as the result in common by many studies making harm-benefit comparison related to fish consumption that fish to be consumed at least twice a week is much more useful for human health than risks that may occur related to fish consumption. Herein, there is an exception for some groups. United States Food and Drug Administration (US FDA) and Environmental Protection Agency recommends that pregnant women, breastfeeding mothers and children whose cardiovascular disease risk is low are to consume canned tunny fish and salmon â&#x2030;¤ 2 times a week; on the other hand they are to avoid consuming fishes such as shark and tuna. Omega-3 supportive preparations are also used in daily practise beside dietary fish consumption. Possible serious and mild side effects have been assessed during omega-3 supportive therapies and particularly it has attracted attention to bleeding complication that may be clinically considerable. Except 1 study, fortunately, any evidence cannot be obtained suggesting omega-3 FA supportive therapy to cause bleeding. Nevertheless, gastrointestinal side effects may occur as soon as supportive therapy does increases. The question whether fish oil supportive preparations can be used in treatment of arrhythmia or not has been researched in a kind of arrhythmia named as atrial fibrillation that is often encountered and observed in society and it has also been perceived that results are very confusing. Some symptoms even have been discovered about the fact that supportive therapy within outer fish oil preparations may make situation worse. However, studies on this subject are still very limited and inadequate. When all of these evidences are considered, neither fish nor fish consumption create a considerable risk for human health.

Recommendations They are among primarily objectives of many national and international healthy organizations nowadays to prevent 222

cardiovascular diseases and reduce rates of complications that may occur due to this disease in populations whose cardiovascular diseases have already occurred. For example, European Society of Cardiology defines its mission as ‘’to reduce the burden of cardiovascular disease in Europe’’. Cardiovascular diseases cause considerable loss of qualified man power in developed and developing countries. World Health Organization specifies that more than three fourths of deaths related to cardiovascular diseases can be prevented by life-style changes. Healthy nutrition constitutes one of the most important steps of life-style changes. It is already agreed by almost all world that increase in fish consumption has a protective effect on cardiovascular health. Is it possible if fish oil has a therapeutic effect beside its protective effects? At this point, it will be useful to review suggestions of international health organizations and associations. European Society of Cardiology specifies in 2012 Cardiovascular Disease Prevention in Clinical Practice Guidelines that even a mild increase in fish consumption provides considerable reductions in death rates related to heart diseases. From this point of view, the association suggests fish consumption at least twice a week of which 1 is fatty fish. It is recommended by all organizations and associations in common to add fish in diets at least twice a week. Evidences are not clear if it is about fish oil preparations containing Omega-3 (DHA-EPA). For example; treatment within omega-3 (1gr/day) preparations does not reduce deaths or complications of cardiovascular diseases in a study which 12513 patients having risk factors for cardiovascular disease. For this reason, suggestions related to fish oil preparations are not very strong. At this point, it is useful to classify patients such as the ones who have or do not have proven cardiovascular disease. The cases that do not have heart diseases can be given fish oil preparations containing EPA/DHA in 1gr/day dose as protector, but it must be recommended these groups preferably to get omega-3 FAs within dietary fish due to the fact that there are not enough evidences. Both European and Northern American guidelines specify that the cases that have cardiovascular diseases and heart failure may get omega-3 fish oil preparations daily in 1gr/day dose (45). However, it should not be forgotten that these suggestions are not strong. Recommendations are stronger in patients whose blood triglyceride levels do not get lowered by pharmacological treatment. It is recommended to give omega-3 FA preparations in > 2gr dose beside dietary and medical treatment in these groups. Australia Heart Foundation (AHF) specifies that patients having coronary artery disease can be given omega-3 support in 1gr/day 223

dose and they can also be given omega-3 support in 2-4gr/day dose in order to lower triglyceride. It can be deduced related to fish and fish oil consumption by us that we do not have enough evidences about protective use of fish oil preparations, yet. However, observational data and positive results of researches related to fish consumption make us think that supportive preparations may have positive actions on cardiovascular health. Researches made for many long years have indicated positive action of fish consumption rich in polyunsaturated omega-3 FAs EPADHA on human cardiovascular health. In the light of evidences, it will reduce cardiovascular diseases and related deaths to consume fatty fish species such as at least 2 portions of salmon, sardine, canned tuna a week. Additionally, it is also considered that preparations containing omega-3 may have positive actions even though results are contradictory. For this reason, supportive preparations containing omega-3 can be used in some special patient groups. But, as far as possible, omega-3 FAs should be preferred to get taken by fish consumption as food. Geographical, economical and social differences cause everybody not to be able to consume fish in desired level. Fish industry all over the world is not enough to meet the demand. Furthermore, differences in eating habits of societies restrict fish consumption considerably. Cardiovascular diseases cause a considerable loss of man power as many international healthy organizations determine. Small changes in diet will prevent this loss of man power considerably. For this reason, it will be a rational strategy for society health to develop policies on the basis of ministries, governments and countries in order to increase fish consumption.

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Bang HO, Dyerberg J. Fat content of the blood and composition of the diet in a population group in West Greenland. Ugeskr Laeger. 1975;137(29):16411646. Dyerberg J, Bang HO, Stoffersen E, Moncada S, Vane JR. Eicosapentaenoic acid and prevention of thrombosis and atherosclerosis? Lancet. 1978; 2(8081):117-119. Billman GE, Kang JX, Leaf A. 1999. Prevention of sudden cardiac death by dietary pure omega-3 polyunsaturated fatty acids in dogs. Circulation;99:2452–2457. Burr ML. 2000. Lessons from the story of n-3 fatty acids. Am J Clin Nutr.71(Suppl. 1):397S–398S. Calder PC. 2003. N-3 polyunsaturated fatty acids and inflammation: from molecular biology to the clinic. Lipids;38:343–352. Cheng X, Chen S, Hu Q, Yin Y, Liu Z. 2013. Fish oil increase the risk of recurrent atrial fibrillation: Result from a meta-analysis. Int J Cardiol. 2013 Jul 23. doi:pii: S0167-5273(13)01152-2. 10.1016/j.ijcard.2013.06.096. [Epub ahead of print]. de Winther MP, Kanters E, Kraal G, Hofker MH.2005. NF-kB signaling in atherogenesis. Arterioscler Thromb Vasc Biol.;25:904–914. Dolecek TA, Granditis G. 1991. Dietary polyunsaturated fatty acids and mortality in the Multiple Risk Factor Intervention Trial (MRFIT). World Rev Nutr Diet.;66:205–216. EFSA Panel on Contaminants in the Food Chain (CONTAM). 2005. Opinion of the scientific panel on contaminants in the food chain (contam) related to the safety assessment of wild and farmed fish. EFSA J. 2005, 236, 1–118; doi:10.2903/j.efsa..236. Elvevoll, E.O.; Barstad, H.; Breimo, E.S.; Brox, J.; Eilertsen, K.E.; Lund, T.; Olsen, J.O.; Osterud, B. 2006. Enhanced incorporation of n-3 fatty acids from fish compared with fish oils. Lipids, 41, 1109–1114. European Guidelines on cardiovascular disease prevention in clinical practice (version 2012). The Fifth Joint Task Force of the European Society of Cardiology and Other Societies on Cardiovascular Disease Prevention in Clinical Practice (constituted by representatives of nine societies and by invited experts). Eur Heart J. 2012 Jul;33(13):1635-701. Fahy, E., Subramanium, S., Brown, A.H., Glass, C.K., Merril Jr., A.H., Murphy, R.C., Raetz, C.R.H., Russell, D.W., Seyama, Y., Shaw, W., Shimizu, T., Spener, F., van Meer, G., VanNieuwenhze, M.S., White, S.H., Witztum, J.L. & Dennis, E.A. 2005. A comprehensive classification system for lipids. J. Lipid Res., 46: 839-861. Foran, J.A.; Good, D.H.; Carpenter, D.O.; Hamilton, M.C.; Knuth, B.A.; Schwager, S.J. 2005. Quantitative analysis of the benefits and risks of consuming farmed and wild salmon. J. Nutr., 135, 2639–2643. GISSI Investigators. 1999. Dietary supplementation with n-3 polyunsaturated fatty acids and vitamin E after myocardial infarction: results of the GISSIPrevenzione trial. Gruppo Italiano per lo Studio della Sopravvivenza nell’Infarto miocardico. Lancet 1999;354:447–455. Hallaq H, Smith TW, Leaf A. 1992. Modulation of dihydropyridine-sensitive calcium channels in heart cells by fish oil fatty acids. Proc Natl Acad Sci USA;89:1760–1764. He K, Song Y, Daviglus ML, Liu K, Van Horn L, Dyer AR, Greenland P. 2004.Accumulated evidence on fish consumption and coronary heart disease mortality: a meta-analysis of cohort studies. Circulation;109:2705–2711


Kris-Etherton PM, Harris WS, Appel LJ; 2003. Nutrition Committee. Fish consumption, fish oil, omega-3 fatty acids, and cardiovascular disease. Arterioscler Thromb Vasc Biol. 2003 Feb 1;23(2):e20-30. Kromhout D, Feskens EJ, Bowles CH. 1995.The protective effect of a small amount of fish on coronary heart disease mortality in an elderly population. Int J Epidemiol.;24:340–345. Kwak SM, Myung SK, Lee YJ, Seo HG. 2012. Efficacy of omega-3 fatty acid supplements (eicosapentaenoic acid and docosahexaenoic acid) in the secondary prevention of cardiovascular disease: a meta-analysis of randomized, double-blind, placebo-controlled trials.Meta-analysis Study Group. Arch Intern Med. 2012 May 14;172(9):686-94. Kromhout D, Bloemberg BP, Feskens EJ, et al. 1996. Alcohol, fish, fibre and antioxidant vitamins intake do not explain population differences in coronary heart disease mortality. Int J Epidemiol.;25:753–759. Mizushima S, Moriguchi EH, Ishikawa P, et al. 1997. Fish intake and cardiovascular risk among middle-aged Japanese in Japan and Brazil. J Cardiovasc Risk.;4:191–199. Nakamura N, Hamazaki T, Ohta M, Okuda K, Urakaze M, Sawazaki S, Yamazaki K, Satoh A, Temaru R, Ishikura Y, Takata M, Kishida M, Kobayashi M. 1999. Joint effects of HMG-CoA reductase inhibitors and eicosapentaenoic acids on serum lipid profile and plasma fatty acid concentrations in patients with hyperlipidemia. Int J Clin Lab Res;29:22–25. National Heart Foundation of Australia. 2008.Review of the evidence: fish, fish oils, n−3 polyunsaturated fatty acids and cardiovascular health; p. 1-7. Neaton JD, Blackburn H, Jacobs D, Kuller L, Lee DJ, Sherwin R, et al. 1992. Serum cholesterol level and mortality findings in the Multiple Risk Factor Intervention Trial. Arch Intern Med; 152:1490–1500. Oken, E.; Choi, A.L.; Karagas, M.R.; Marien, K.; Rheinberger, C.M.; Schoeny, R.; Sunderland, E.; Korrick, S. 2012. Which fish should I eat? Perspectives influencing fish consumption choices. Environ. Health Perspect, 120, 790– 798. Oomen CM, Feskens EJ, Rasanen L, et al. 2000. Fish consumption and coronary heart disease mortality in Finland, Italy, and The Netherlands. Am J Epidemiol.;151:999–1006. Oomen CM, Ocke MC, Feskens EJ, van Erp-Baart MA, Kok FJ, Kromhout D. 2001. Association between trans fatty acid intake and 10-year risk of coronary heart disease in the Zutphen Elderly Study: a prospective population-based study. Lancet; 357:746–751. Raatz SK, Silverstein JT, Jahns L, Picklo MJ. 2013 Issues of Fish Consumption for Cardiovascular Disease Risk Reduction. Nutrients, 5, 10811097. Risk and Prevention Study Collaborative Group et al. 2013. n-3 fatty acids in patients with multiple cardiovascular risk factors.N Eng J Med 2013 May 9;368(19):1800-8. Rizos EC, Ntzani EE, Bika E, Kostapanos MS, Elisaf MS. 2012. Association between omega-3 fatty acid supplementation and risk of major cardiovascular disease events: a systematic review and meta-analysis. JAMA. 2012 Sep 12;308(10):1024-33. Shipley MJ, Pocock SJ, Marmot MG. 1991. Does plasma cholesterol concentration predict mortality from coronary heart disease in elderly people? 18 year follow up in Whitehall Study. BMJ; 303:89–92. SIGN (Scottish Intercollegiate Guidelines Network). 2007. Risk Estimation and the Prevention of Cardiovascular Disease. A National Clinical Guideline. Report No. 97.


Stone NJ. 1996.Fish consumption, fish oil, lipids, and coronary heart disease. Circulation;94:2337–2340. Swann PG, Venton DL, Le Breton GC.1989. Eicosapentaenoic acid and docosahexaenoic acid are antagonists at the thromboxane A2/prostaglandin H2 receptor in human platelets. FEBS Lett;243:244–246. Sioen, I.; de Henauw, S.; Verbeke, W.; Verdonck, F.; Willems, J.L.; van Camp, J. 2008. Fish consumption is a safe solution to increase the intake of long-chain n-3 fatty acids. Public Health Nutr.,11, 1107–1116. Smith SC, Benjamin EJ, Bonow RO, et al. 2011. AHA/ACCF secondary prevention and risk reduction therapy for patients with coronary and other atherosclerotic vascular disease: 2011 update: a guideline from the American Heart Association and American College of Cardiology Foundation. Circulation; 124: 2458–73. Streppel MT, Ocke´ MC, Boshuizen HC, Kok FJ, Kromhout D. 2008. Longterm fish consumption and n-3 fatty acid intake in relation to (sudden) coronary heart disease death: the Zutphen study. Eur Heart J;29:2024–2030. Tagawa T, Hirooka Y, Shimokawa H, Hironaga K, Sakai K, Oyama J, Takeshita A. 2002. Long-term treatment with eicosapentaenoic acid improves exercise-induced vasodilation in patients with coronary artery disease. Hypertens Res.,25:823–829. United States Department of Agriculture; Department of Health and Human Services. 2010. Dietary Guidelines for Americans, 2010; US Government Printing Office: Washington, DC, USA. Villani AM, Crotty M, Cleland LG, James MJ, Fraser RJ, Cobiac L, Miller MD. 2013. Fish oil administration in older adults with cardiovascular disease or cardiovascular risk factors: Is there potential for adverse events? A systematic review of the literature. Int J Cardiol. 2013 Jun 3. doi:pii: S01675273(13)00963-7. 10.1016/j.ijcard.2013.05.054. What do you need to know about mercury and in fish and sellfish: EPA and FDA advice for women for women who might become pregnant, nursing mothetrs. Availible online. Whelton SP, He J, Whelton PK, Muntner P. 2004. Meta-analysis of observational studies on fish intake and coronary heart disease. Am J Cardiol, 93:1119–1123.


b) Fish (Omega-3 fatty acids) and Eye Health Omega-3 fatty acids, are long-chained, polyunsaturated fatty acids (PUFAs) and are essential to maintain the normal human biological function. These long-chain PUFAs have 2 forms: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Diet is our only source of omega-3 fatty acids, because the human body has a very limited ability of converting shorter-chain omega-3 fatty acid Îą-linolenic acid (ALA) to EPA and then to DHA. Also this ability becomes more impaired in the older ages. The PUFAs play a crucial role, especially in brain function, memory, and they help to lower the incidence of chronic diseases such as heart disease, arthritis, cancer, depression, skin, eye and circulation problems. Cold water oily fish and fish oil are the best source of long-chain, omega-3 PUFAs: EPA and DHA, which are essential for proper fetal development and healthy aging. DHA is 6 found in all cell membranes, mostly in the brain and retina. EPA and DHA are also the precursors of several lipid mediators, which are 7 important in in the prevention and treatment of many diseases. The retina is highly enriched with DHA and other omega-3 fatty acids, which are believed to play an important role in maintaining normal retinal function and macular health. Adequate amount of omega-3 is crucial, not just for preventing or treating the diseases, also for retinal and macular function to maintain the eye health. Proliferative retinopathies are a leading cause of blindness. These diseases, such as diabetic retinopathy and retinopathy of prematurity, are caused by abnormal blood vessel growth, or neovascularization, in the retina, the part of the eye that detects the light and then converts it into electrical signals and sent to the brain. An other common cause of blindness is age related macular degeneration (AMD) and is becoming prevalent due to aging of populations especially in industrialized countries. Omega-3 fatty acids supplementation is believed to have beneficial effects in prevention and treatment of AMD. EPA has vasoregulatory and anti-inflammatory properties; and inflammation appears to play a major role in AMD. Long-chain omega3 PUFAs may slow down the progression of this degenerative and angiogenic disease with its antiangiogenic, antivasoproliferative, and neuroprotective properties. Several epidemiologic studies have suggested inverse correlations of AMD risk with dietary long-chain omega-3 PUFA and fish intake. The protective effect of dietary fish consumption, from retinal degeneration has notably been attributed to its high content of long-chain omega-3 PUFA, that is the EPA and DHA contents in it. New treatments for AMD are developed in order to 228

stabilize the vision, to stop or slow down the progression, but they are not curative and are mostly for the neovascular type of the disease. Epidemiological studies suggest the effects of smoking and nutritional factors. So the potential preventative role of long-chain omega-3 PUFAs, such as DHA and EPA, found in fish, are in common interest recently. Nutrient supplementation is becoming increasingly important as an alternative approach to prevent development and progression of age-related macular degeneration (AMD), and a number of observational studies have found that regular dietary intake of omega3 fatty acids and fish is associated with lower risks of vision loss from early and late AMD. In a study about eye health and eating habits of 38,022 women with 10 years of follow-up, 235 were diagnosed with AMD, women who consumed one or more servings of fish per week, and those who regularly consumed the omega-3 fatty acids DHA and EPA, had a 35 to 45% reduced risk of clinically significant AMD compared with women who consumed the lowest amounts of fish and omega-3s. These preventative modalities are certainly more attractive than the treatments. They are cheaper, easily attainable, they donâ&#x20AC;&#x2122;t need retina specialists or even ophthalmologists for administration, they are free from intraocular injection complications, and they are healthy. Dietary deficiency of omega-3 fatty acids has also been associated with the development of AMD. Chong and colleagues performed a meta-analysis of data pooled from nine clinical studies (including the Age-Related Eye Disease Study [AREDS]). Although the authors concluded that there was insufficient data from prospective and clinical studies to support routine supplementation of omega-3 fatty acids for prevention of AMD in the general population, they did find a 38% reduction in the likelihood of late AMD with high dietary intake of omega-3 fatty acids.

Dry Eye Syndrome Dry eye syndrome (DES) is one of the most prevalent ocular conditions in the world and a frequent reason for seeking eye care. Ocular discomfort is the most prominent patient complaint. In addition, DES commonly leads to decreased functional visual acuity, and problems such as burning, itching, stinging, and redness whie reading, using a computer, watching TV, driving at night and carrying out professional work. The most common therapy for DES, is artificial tears, but this therapy provides only temporary and partial symptomatic relief. More recently, due to the chronic irritation and the 229

inflammation nature of this disease, omega-3 fatty acid supplementation has emerged as a novel treatment for the dry eye. Miljanovic et al assessed the diets of 32,470 women in the Womenâ&#x20AC;&#x2122;s Health Study, and found that women with higher omega-3 consumption had decreased risk for dry eye. Essential fatty acid supplementation has been shown to have an anti-inflammatory effect on dry eye symptoms. Oral omega-3 fatty acids, 1.5 grams per day, may be beneficial in the treatment of meibomius gland disease that effects the lipid composition of the tear of the eye, mainly by improving tear stability. An association between a higher dietary intake of omega-3 fatty acids and a decreased presence of dry eye has been established.

Sources of Omega-3 Omega-3s are found mainly in fish and green leafy vegetables, legumes, and flax. The types found in fish, called DHA and EPA, have been studied most extensively and appear to have the strongest health benefits. Omega-3 fatty acids help to fight with the disease by reducing inflammation in the blood vessels and joints. Top choices are salmon, mackerel, herring, lake trout, sardines, anchovies and tuna. Eating more fish would be a healthy choice, but freshwater fish throughout the world is essentially inedible due to widespread contamination with mercury and carcinogens like polychlorinated biphenyls (PCBs). Ocean fish are more variable, with some species typically safe and others highly contaminated. However, there is not a widely accepted consensus for safety of eating how much and what kind of fish. So fish farms seems a very rational and healthy choice by supplying fishes without the risk of contamination with mercury and PCBs, and supplying a natural form of omega-3 source. Omega-3 fatty acids are very important for eye health, not only for the treatment of the disease or to protect against the disease, also to maintain the normal eye metabolism. Two servings of oily fish per week, decreases the risk of age related macular degeneration and dry eye and shows you the horizon till the end of your life.

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associations with neovascular age-related macular degeneration. Am J Clin Nutr.;88:398–406. Brignole-Baudouin F, Baudouin C, Aragona P, et al. 2011. A multicentre, double-masked, randomized, controlled trial assessing the effect of oral supplementation of omega-3 and omega-6 fatty acids on a conjunctival inflammatory marker in dry eye patients. Acta Ophthalmol.;89(7):e591–e597. Calder PC, Yaqoob P. 2009. Omega-3 polyunsaturated fatty acids and human health outcomes. Biofactors. 2009 May-Jun;35(3):266-72. doi: 10.1002/biof.42. Cho E, Hung S, Willett WC, et al. 2001. Prospective study of dietary fat and the risk of age-related macular degeneration. Am J Clin Nutr.;73:209–218. Chong EW, Robman LD, Simpson JA, et al. 2009. Fat consumption and its association with age-related macular degeneration. Arch Ophthalmol.;127:674–680. Chong EW, Kreis AJ, Wong TY, et al. 2008. Dietary omega-3 fatty acid and fish intake in the primary prevention of age-related macular degeneration: a systematic review and meta-analysis. Arch Ophthalmol.;126(6):826-33. Christen WG, Schaumberg DA, Glynn RJ, et al. 2011. Dietary ω-3 fatty acid and fish intake and incident age-related macular degeneration in women. Arch Ophthalmol.;129(7): 921-9.doi:10.1001/archophthalmol Chua B, Flood V, Rochtchina E, Wang JJ, Smith W, Mitchell P. 2006. Dietary fatty acids and the 5-year incidence of age-related maculopathy. Arch Ophthalmol.;124:981–986. Dunstan JA, Mitoulas LR, Dixon G, Doherty DA, Hartmann PE, Simmer K, Prescott SL. 2007. The effects of fish oil supplementation in pregnancy on breast milk fatty acid composition over the course of lactation: a randomized controlled trial. Pediatr Res.;62:689–94. Freemantle, E.; Vandal, M. N.; Tremblay-Mercier, J.; Tremblay, S. B.; Blachère, J. C.; Bégin, M. E.; Thomas Brenna, J.; Windust, A.; Cunnane, S. C. 2006. "Omega-3 fatty acids, energy substrates, and brain function during aging". Prostaglandins, Leukotrienes and Essential Fatty Acids 75 (3): 213. doi:10.1016/j.plefa.2006.05.011. Gao, F.; Taha, A. Y.; Ma, K.; Chang, L.; Kiesewetter, D.; Rapoport, S. I. 2012. "Aging decreases rate of docosahexaenoic acid synthesis-secretion from circulating unesterified α-linolenic acid by rat liver". AGE. doi:10.1007/s11357012-9390-1. PMID 22388930. Goto E, Yagi Y, Matsumoto Y, Tsubota K. 2002. Impaired functional visual acuity of dry eye patients. AmJ Ophthalmol;133:181–6. Jager RD, Mieler WF, Miller JW. 2008. Age-related macular degeneration. N Engl J Med.;358:2606–2617. Krauss-Etschmann S, Shadid R, Campoy C, Hoster E, Demmelmair H, Jimenez M, Gil A, Rivero M, Veszpremi B, Decsi T, et al. 2007. Effects of fish-oil and folate supplementation of pregnant women on maternal and fetal plasma concentrations of docosahexaenoic acid and eicosapentaenoic acid: a European randomized multicenter trial. Am J Clin Nutr.;85:1392–400. Lemp MA. 1998. Epidemiology and classification of dry eye. Adv Exp Med Biol;438:791–803. Lubniewski AJ. 1990. Diagnosis and management of dry eye and ocular surface disorders. Ophthalmol Clin North Am;3:575–594. Mares-Perlman JA, Brady WE, Klein R, VandenLangenberg GM, Klein BE, Palta M. 1995. Dietary fat and age-related maculopathy. Arch Ophthalmol.;113:743–748. Miljanovic, B.; Dana, R.; Sullivan, DA.; Schaumberg, DA. 2004. Association for Research in Vision and Ophthalmology (ARVO). ARVO 2004; Fort


Laudrerdale, Florida: Impact Of Dry Eye Syndrome On Vision-related Quality Of Life Among Women Oleñik A, Jiménez-Alfaro I, Alejandre-Alba N, Mahillo-Fernández I. 2013. A randomized, double-masked study to evaluate the effect of omega-3 fatty acids supplementation in meibomian gland dysfunction. Clin Interv Aging.;8:1133-8. doi: 10.2147/CIA.S48955. Epub 2013 Aug 30. Pilkington S.M., Watson R.E., Nicolaou A., Rhodes L.E. 2011. Omega-3 polyunsaturated fatty acids: Photoprotective macronutrients. Exp. Dermatol.;20:537–543. doi: 10.1111/j.1600-0625.2011.01294.x. Resnikoff S, Pascolini D, Etya'ale D, et al. 2004. Global data on visual impairment in the year 2002. Bull World Health Organ.;82:844–851. SanGiovanni JP, Chew EY. 2005. The role of omega-3 long-chain polyunsaturated fatty acids in health and disease of the retina. Prog Retin Eye Res.;24:87–138. Sangiovanni JP, Agron E, Meleth AD, et al. 2009. Omega-3 long-chain polyunsaturated fatty acid intake and 12-y incidence of neovascular agerelated macular degeneration and central geographic atrophy: AREDS report 30, a prospective cohort study from the Age-Related Eye Disease Study. Am J Clin Nutr.;90:1601–1607. SanGiovanni JP, Chew EY, Agron E, et al. The relationship of dietary omega3 long-chain polyunsaturated fatty acid intake with incident age-related macular degeneration: AREDS report no. 23. Arch Ophthalmol. 2008;126:1274–1279. SanGiovanni JP, Chew EY, Clemons TE, et al. 2007. The relationship of dietary lipid intake and age-related macular degeneration in a case-control study: AREDS Report No. 20. Arch Ophthalmol.;125:671–679. Saravanan P, Davidson NC, Schmidt EB, Calder PC. 2010. Cardiovascular effects of marine omega-3 fatty acids. Lancet;376:540-50. Seddon JM, Rosner B, Sperduto RD, et al. 2001. Dietary fat and risk for advanced age-related macular degeneration. Arch Ophthalmol.;119:1191– 1199. Seddon JM, George S, Rosner B. 2006. Cigarette smoking, fish consumption, omega-3 fatty acid intake, and associations with age-related macular degeneration: the US Twin Study of Age-Related Macular Degeneration. Arch Ophthalmol.;124:995–1001. Serhan CN, Chiang N, Van Dyke TE. 2008. Resolving inflammation: dual antiinflammatory and pro-resolution lipid mediators. Nat Rev Immunol.;8:349–61. Schweigert F.J., Reimann J. 2011. Micronutrients and their relevance for the eye—Function of lutein, zeaxanthin and omega-3 fatty acids. Klin. Monbl. Augenheilkd.;228:537–543. doi: 10.1055/s-0029-1245527. Tan JS, Wang JJ, Flood V, Mitchell P. 2009. Dietary fatty acids and the 10year incidence of age-related macular degeneration: the Blue Mountains Eye Study. Arch Ophthalmol.;127:656–665. Thornton J, Edwards R, Mitchell P, Harrison RA, Buchan I, Kelly SP. 2005. Smoking and age-related macular degeneration: a review of association. Eye.;19:935–944.


XII. Slaughtering and Processing Methods Autors: Valdimar Ingi Gunnarsson, Sigurður Már Einarsson

1. Slaughtering and packing whole fish Preparing fish for slaughtering Aquaculture gives more possibilities to influence quality and yield. Aquaculture makes it possible to alter the size and shape distribution, chemical composition, texture and pigmentation of farmed fish prior to harvest. It is therefore possible to produce a fish which is specially designed to satisfy certain criteria with the aim to give optimal yield and quality (Figure 1). In comparison with fisheries, aquaculture gives better control over number of factors which affect stress level of the fish, including handling, crowding in the nets and the use of anaesthetics. This gives the processor a greater control and the ability to at least predict and maybe influence the development of rigor mortis. Several of the factors which influence yield and total quality of the primary products including:     

Breeding, for instance to increase condition factor of fish Feed and feeding Farming conditions Harvest handling And the option of harvesting before maturation.

The process The harvesting of fish can be split into five stages: grading, starving, crowding, transport and killing (Figure 1).  

Grading occurs on a number of occasions throughout the life of fish, to ensure they are kept in groups of similar size. Starving for 1-3 days or over a longer period serves to clear food and waste materials from the fish gut. 233

  

Crowding of fish reduces available area and enables to lift fish more easily out of the water. Transports live fish to slaughtering facility. Different methods to kill the fish.

Culture ⁻ Feed, feeding and culture environment effect fish quality






⁻ Correct fish size - Improve quality - Stressfull - Stressfull - Many methods - Improve storage - Decrease quality - Decrease quality with differance and quality time impact on fish welfare and quality

Figure 1. Culture and harvesting methods can affect fish quality (Drawing: G. Jóhannsson). Grading Separation of stock into different size classes reduces post-harvest grading. Also the market will generally pay a higher price for larger fish. Normal grading procedure either involves passive grading grids, which the smaller fish can swim through or pumping fish across a grading grid. Sweep net with screen are used in cage farms and underwater bar graders in land-based farms (Chapter 4). Starving Before handling, transport and slaughtering, it is important to starve the fish for as long as necessary to ensure that gut contents are evacuated. During feeding periods, the digestive tract of the fish contains many bacteria that produce digestive enzymes capable of causing intense post mortem autolysis, resulting in strong odours and flavours, especially in the abdominal area. By reducing the amount of faeces in the intestines, spoilage is delayed, and digestive enzyme activity is reduced. Starving time depends on fish size and temperature. In general, the starvation period is 1 to 3 days depending on temperature. For large fish like Atlantic salmon and rainbow trout starving prior to slaughter, lasts for one to two weeks and even a longer period. Starvation over longer periods increases the quality of meat. 234

Crowding In order for fish to be lifted out of the water effectively they need to be brought together: this is known as crowding (Figure 2). As crowding brings fish very close together it can be an extremely stressful and physically damaging to fish, as they try to escape from each other. Hence the time in which fish are crowded should be limited and should never exceed two hours. The typical crowding start with calm fish and then escalates in intensity as the net is tightened. At the end of the crowding the activity often decreases, most likely because the fish are exhausted. Air gasping and lateral side up are the typical signs of the crowding. Such behaviour is inevitable, but those signs should be seen as the end of the crowding rather that at the beginning. Intense crowding (increased fish exercise) accelerates the onset of rigor mortis.

Figure 2. Crowding and pumping of cod from cage on board the well boat (Photo: V.I.Gunnarsson).

Figure 3. Arctic charr pumped with vacuum pump into tank of truck (Drawing: V.I. Gunnarsson).

Fish transport Fish are farmed at either onshore or offshore cages; therefore slaughtering locations vary considerably, but will either be at central killing stations on the mainland or at the farm where the fish are grown. Historically, fish were always slaughtered at the site where they were grown. However, following transport improvements and business mergers, some of the larger companies in fish farming use a harvest station to which all the fish are transported for slaughter. The farmed fish are usually transported in a well boat (Figure 4) or in a truck with tanks (Figure 3). Fish are transferred directly into slaughtering or are kept alive for few days in a pre-slaughter tank or cage (Figure 5). When farmed fish are handled or transported it is important to avoid damage that affects quality of fish. Injured skin 235

reduces marketability of the product and micro-organism transfer from skin to flesh, which may accelerate spoilage.

Figure 4. Pumping fish with vacuum pump from well boat direct into slaughtering house or into pre-slaughter cage for storage for days before slaughtering (Photo: V. I. Gunnarsson).

Figure 5. Farmed fish stored in a pre-slaughter cage in Norway and slaughtering house in background (Photo: V. I. Gunnarsson).

Stun/kill methods and fish welfare Two-stage process Slaughter is generally a two-stage process. The animal is first stunned to make it insensible to pain. Death is then induced by various methods that include bleeding, stopping the heart, or preventing access to oxygen. These two stages can occur together but where they are distinct operations, the stun-to-kill time must be minimized to prevent any recovery of consciousness before death occurs. Slaughtering methods, quality and welfare In farmed fish, quick slaughtering and minimal stress in handling leads to a more humane death and the product will have better quality and a longer storage life. Numerous methods have been used to stun and/or kill farmed fish, but research has found most to be inhumane. Methods such as asphyxiation on ice or air, carbon-dioxide stunning, gill-cutting without 236

prior stunning, and live chilling do not cause immediate insensibility, and studies on the physiological and behavioural responses of fish show that these slaughter practices are likely to cause suffering as animals respond with highly aversive behaviour. Both percussive and electrical stunning, if applied correctly, can induce immediate and irreversible insensibility, thereby subjecting the animals to less pain, stress, and undue suffering as compared to other methods.

Live chilling tank

Electrical stunning

Cutting the gills




Figure 6. Typical processing line for slaughtering of salmonids (Drawing: V.I. Gunnarsson and photo from manufacturer). Percussive stunning With percussive stunning, fish are rapidly struck on the head, resulting in violent movement of the brain within the skull, causing concussion and cerebral dysfunction. This method renders fish unconscious immediately and irreversibly if sufficient force is applied to the correct part of the head. In the occasion that a fish regains consciousness due to an improper stun or there is any uncertainty whether the stun was effective, the fish should be re-stunned immediately. 237

Percussive stunning may be done by a hand-held club for small numbers of fish or by a machine when large numbers are killed. This method is suited to large round fish such as large trout and salmon. Percussive stunning devices are becoming widespread within the salmon industry. One type of percussive stunning system is activated when the nose of the fish contacts a stainless steel retracting trigger plate. This in turn activates a sensor and allows either a pneumatic or electrical pulse to activate a circuit which mobilizes the striker piston which hits the fishâ&#x20AC;&#x2122;s head at high speed causing it to be instantaneously and irreversibly stunned. Electrical stunning and killing Stunning by use of electricity is known as electronarcosis, whereas killing by using electricity is known as electrocution. Depending on the electrical parameters, such as voltage, frequency and duration, either outcome can be induced. Electric stunning is reversible as normal brain function is disrupted for a short period only; hence electronarcosis must be immediately followed by bleeding before the animal can recover from the stun and regain consciousness. Electrocution, on the other hand, completely destroys brain function and therefore renders the animal unconscious while stopping the breathing reflex from functioning. Electrical stunning has also been shown to be effective for eels, salmonids, and catfish if promptly slaughtered (Figure 6). With the electrical system, large numbers of fish can be slaughtered and processed with minimal handling. Electrical stunning is not a method without drawbacks, fish have been reported to show violent behavioural reactions, muscle blood spots and fractured vertebrae when subjected to electricity.

Chilling and bleeding Chilling live fish In some slaughter houses farmed fish are chilled a live before slaughtering (Figure 6). Live chilling is considered by the aquaculture industry to offer benefits to carcass quality since reducing muscle temperature close to 0ÂşC eliminates significant thermal energy that would otherwise begin the muscle degradation process that begins soon after death and also increases both the time for the onset of rigor mortis and the resolution of rigor.


Rapid drops in body temperature can be very stressful to fish. For those who are transferred from warm water, the temperature reduction and impacts on welfare may be more dramatic, as is the case with some Atlantic salmon farms where fish are taken from seawater of temperatures as high as 15ºC. Farmed fish need therefore to be slowly chilled down. Chilling in processing Decreasing the temperature of the fish to about 0° C slows down the microbiological, chemical and biochemical decomposition processes and extends fish stability. Thus the raw material is chilled quickly after killing and kept at low temperature throughout processing line.

Bleeding From the animal welfare perspective, fish must be unconscious or dead before bled out. Bleeding is only practically applicable to medium to large species. Large farmed fish need to have the blood removed from the muscle and it is recommended to cut the gills with a sharp knife (Figure 7 and 8). In some cases farmed fish are cut in bleeding machines (Figure 6). Fish should be bled as soon as possible for a minimum of 20-30 min.

Figure 7. Cutting the gills with a sharp knife for bleeding (Photo: V. I. Gunnarsson).

Figure 8. Cutting gill of arctic charr and bleeding tank (Photo: V. I. Gunnarsson).


Gutting and cleaning Gutting area In a advanced slaughter house, farmed fish enters the gutting area where quality inspectors feed them into a grader. The grader weighs fish with high accuracy, and then directs the right size and quality of fish to the optimal gutting machines based on fixed-rate function, which ensures the optimal performance of gutting machines. The feeding into the gutters is fully automatic. By combining the optimized distribution of fish with automatic feeding into the gutting machines, overall performance of the gutting process is considerably improved (Figure 9) Palletizing Box packing Up to four quality inspectors feeding fish into grader

Chilling tank

Ergonomic infeed

Whole fish grader

Manual gutting Automatic gutting Grading Ergonomic infeed Up to four quality inspectors feed fish into gutting grader

Dynamic weighing

Figure 9. Advanced distribution system for farmed Atlantic salmon with grading, gutting, chilling, packing and palletizing (

Gutting Gutting, like bleeding, is also applicable to medium and large species. The main reason for gutting is to prevent autolytic spoilage rather than bacterial spoilage. Gutting machines for processing salmon, trout, eel and a couple of other species, have been constructed in several countries. The cutting of the body cavity, 240

removal of guts and kidney tissue with brushes and vacuum suction can be performed in these multi-application machines (Fgure 10).

Figure 10. Gutting of salmon in machine (Photo: V.I. Gunnarsson).

Figure 11. Gutting and cleaning of salmon (Photo: V.I. Gunnarsson).

Cleaning The fish should be washed thoroughly with clean, cold running fresh water or sea water. This cleans the surfaces of tissue digestive enzymes, spoilage organisms, blood and remaining visceral matter (Figure 11).

Clean fish and keep moist.

Keep fish on ice.

Protect fish from external heat.

Figure 12. Three important steps to preserve the quality of fish (Drawing: G. J贸hannsson).


Slaughter yield The increasing cost of producing fish means that it is important to recover as must valuable flesh as possible and this has encouraged greater attention for improving the yield of edible portions. The slaughter yield differs between species, but there are also differences in slaughter yields also within species. Excess energy is deposited differently in different species. In cod energy is mainly stored in the liver and the liver can be up to 15-20% of the body weight of heavily fed fish. In rainbow trout and salmon, on the other hand, excess energy is deposited to a large extent as fat in the muscle and also surrounding the intestines, especially in trout. Slaughter yield for cod are around 80%, 85% for rainbow trout and 90% for Atlantic salmon (Figure 13).

Figure 13. Slaughter yield, as gutted weight/ungutted weight*100 for farmed Atlantic cod, rainbow trout and Atlantic salmon (Drawing: V.I.Gunnarsson).

Sorting and grading Grading The processing sequence starts from grading the fish by size. Sorting on the basis of freshness and physical damage are still manual processes, but grading of fish by size is easily done with mechanical equipment. Mechanical graders yield better sorting precision for fish before or after rigor mortis than for fish in a state of rigor mortis. Size grading is very important for fish processing (i.e., 242

smoking, freezing, heat treatment, salting, etc.) as well as for marketing. Sorting Standards establish the characteristics and acceptable defaults which permit fish to be sorted into categories of equal market value. Today farmed fish is manually sorted into quality classes, in order to ensure a uniform and high quality. Farmed Norwegian salmon are sorted in three quality classes: 

Superior: A first class product with characteristics which make it suitable for all purposes. The product is without substantial faults, damage or defects and provides a positive overall impression. Ordinary: A product with limited external or internal faults, damage or defects. The product is without substantial faults, damage or defects which would make further use difficult. Production: Salmon that not satisfy the requirements to Superior or Ordinary because of faults, damage or defects are to be sorted into the Production category. The fish are supplied as head off.

Grading area In a advanced slaughter house, farmed fish go from gutted area into packing area (Figure 9). Fish pass through quality control where they are examined for any defects in appearance, before entering the whole-fish packing and distribution grader. The highly advanced grading and distribution system automatically controls the distribution of each fish, directing it to the optimum process, for example freezing, filleting, or to the automatic box filling station for whole gutted fish. The distribution is based on weight and quality, and it is also possible to apply the condition factor (K-factor) to direct specially designated fish to pre-determined processing stations. This can be of great value for the filleting process where fish of similar condition (size) will provide improved yield and quality of finished products.

Packing and whole fish Refrigerants The desired objective of refrigerants is to keep the fish at an approximate temperature of about 0°C. This necessitates proper pre243

chilling of the fish as refrigerants can only maintain the temperature of this fish and will not lower it. Finely chopped ice has been the traditional refrigerant in the industry and is still generally the preferred method, especially for transport in ship and truck. Under ice minimal melt water is generated during transport, the fish will arrive at the market still at 0째C and process a clean, fresh appearance unequalled by other refrigerants. This is due to the moisture level generated by ice. It is recommended that the ices distributed evenly in the box to ensure that all parts of the fish are well chilled. Refrigerant gel packs have the advantage of being able to absorb heat energy over a long period of time providing the packs are well refrigerated. They have been used extensively and are preferred by most airlines. Another advantage is that gel pack will not contribute to leakage even if punctured. The two disadvantages are desiccation (i.e. drying out) of the skin of the fish as a result of lack of moisture during transport and lack of uniform chilling of the fish due to noncontact with gel pack. Packing materials Quality assurance is essential in each technological process, and suitable packaging materials and methods are of great importance. Packaging should protect the product from contamination and prevent it from spoilage, and at the same time it should extend shelf life of a product. Polystyrene boxes are extensively used for farmed fresh fish (Figure 14). Its major advantage from a quality viewpoint is its high insulation capacity. Polystyrene protects and maintains the interior temperature of the box from the exterior temperature fluctuations better than many other packing materials. Polystyrene boxes are also manufactured with perforated false bottoms witch allow the melt water to be separated from the fish. The main disadvantage of polystyrene fish boxes is their lack of strength. They are easily damaged or broken by rough handling. This limits their size and use. Polystyrene is difficult to clean. Polystyrene boxes are difficult to re-use, and are usually non-returnable. They may cause disposal problems due to their bulk. Absorbent pad Blood water/melt water should be taken up by an absorbent pad approved for food stuffs. The absorbent pad is to be placed on the


bottom of the polystyrene box. False- bottom boxes will allow the absorbent pad to go below the perforated false-bottom.

Figure 14. Grading, sorting and packing of Atlantic salmon (Photo: V.I. Gunnarsson).

Figure 15. Dressed fish should be placed belly down and un-dressed fish should be placed with belly up (Drawing: G. J贸hannsson).

Packing The pre-chilled fish are usually placed in the box with heads facing either end, tails meeting in the centre. Dressed fish should be placed belly down to prevent dirty melt water from puddling in the belly cavity. Un-dressed fish should be placed with belly up (Figure 15). Polystyrene boxes are weighed and labelled (Figure 16) and boxes placed on the pallet transported in cold storage (Figure 17).

Figure 16. Weighing and packing of whole Atlantic salmon (Photo: V.I. Gunnarsson).


Figure 17. Polystyrene boxes on pallets in cold storage ready for export (Photo: V.I. Gunnarsson).

2. Processing Quality is important Important steps in processing Primary processing is the term used to describe the first steps of converting fish into food items that is attractive to the consumers. Primary processing has a number of functions:  

Its main function is to enhance hygiene and in this way extend the shelf-life of the final product. Further, primary processing decreases the mass of the raw material and increases the cost-effectiveness of transportation of semi – processed or final products. Another factor is the desire of producers to add product value and increase product differentiation. These are becoming increasingly important to secure current markets and to penetrate new ones. Primary processing also allows the separation of edible parts from inedible ones, securing optimal quality of the parts that are going to be used and minimizing waste.

Rigor mortis Rigor mortis can influence result of filleting and processing farmed fish. It’s characterized by muscle contraction, seen externally as progressive body stiffness (Figure 18). Right after death, the muscle is soft and limp (called pre rigor), then it becomes stiff and hard (in rigor), where after the muscle regain softness (post rigor). The longer the onset of rigor starts (time before stiffness) the better meat quality. The duration of the rigor progression is mainly influenced by stress pre mortem (severe exercise, rough crowding, long distance pumping, transport and improper stunning method) and high storage temperature (Figure 19). Rigor mortis can be measured by changes in muscle contraction in whole fish by tail bending, also called rigor index (Figure 18). The sag of the fish tail is measured when half of the fish body is placed on a horizontal table and measurements are repeated several times during fish storage. Another possibility is to follow rigor through fillet contraction (Figure 20).


Figure 18. Rigor index (Drawing: G. J贸hannsson).

Post rigor

In rigor

Pre rigor


Rigor status

4 Anaesthetized

3 2 1 0 0



40 50 30 Hours post mortem



Figure 19. Rigor status of anesthetized and stressed Atlantic salmon during ice storage.


Post rigor

Pre rigor

Figure 20. Post and pre rigor of cod fillet (Photo: V.I.Gunnarsson).

Filleting Filleting adds value to product A fillet which is a piece of meat consisting of the dorsal and abdominal muscles has been a most sought-after fish product in the retail market. Filleting is important for logistics, economics, the addition of value along the marketing chain, and for the separation of edible parts from inedible ones. In general, filleting adds value to the product, although this depends very much on the type of market. Filleting Filleting can be performed either by machine or by hand. A skilled worker can achieve a very high yield by hand- filleting, but is very labour intensive. Therefore, most companies which fillet large quantities of fish use machines (Figure 21). The basic operations of machine filleting are: cutting along the upper and lower appendices on spine, cutting over the ribs and cutting along the vertebrate.


Figure 21. Filleting machine (Photo: V.I. Gunnarsson).

Figure 22. Grading fillets in grader (Photo: V.I. Gunnarsson).

Filleting machines are composed of three basic parts: ď&#x201A;ˇ The internal handling system (linear or rotary holders handling the fish), grippers, saddle-shaped holders, conveyer belts or chains with holding bite or needles ď&#x201A;ˇ The control- adjustment system ď&#x201A;ˇ The filleting tool units, typically disk knives. Post rigor filleting Filleting is traditionally performed after the onset of rigor mortis, but this should be weighed against loss of freshness and the cost of storage. If fish is processed in rigor, the yield will be poor and it may cause gaping. Large farmed species like Atlantic salmon are usually filleted once rigor has been resolved, normally 3 to 4 days after death. Pre rigor filleting Pre rigor filleting has several advantages, one being that it ensures very fresh processed fish with little or no fillet gaping, although it changes the shape and pre rigor fillets are significantly thicker. Also, the texture is softer than in rigor and certain operations such as the removal of pin bones are more difficult. Filleting before pre rigor may lead to extensive loss of weight and proteins during subsequent storage. Pre rigor processing then presents problems, but there are obvious advantages to processing immediately after slaughter: the products can be shipped to market 3 to 5 d earlier and a prolonged shelf life is a major economic benefit.


Fillet gaping Fillet gaping is a serious problem for the filleting industry. Fillet with gaping are difficult to process and unattractive to the consumer. Following factors decrease the amount and the severity of gaping:    

Harvesting fish in a rested state Rapid cooling, including pre-mortal chilling Minimal harvest handling Optimal feeding strategy.

Fillet yield Different standards of trimming are used, from removing only the backbone to removing visible fat, pin bones, and skin, and these different produce different yields (Table 1). Fillet yield depends on the species, sex, size, and its structural anatomy. Fish with large heads and frames relative to their musculature give a lower yield than those with smaller heads and frames. In farmed fish, yields can also be affected by farming conditions (feeding, water temperature, and so on). Of commercially farmed fish species, tilapia has the lowest fillet yield (33%) as compared to Atlantic salmon (>50%) and freshwater eel (60%). Table 1. Weight conversion ratios Live fish Loss of blood/starving Harvest weight Round bled fish (wfe) Offal Gutted fish, approx. (HOG) Head, approx. Head off, gutted Fillet skin on Fillet skin off

Atlantic salmon 119% 8% 111%



11% 14% 100% 100% 9% 9% 91% 91% 67 ‐ 77% (C‐trim approx. 70%) 56 ‐ 68%

Trimming, pinboning and skinning Trimming Difference standards of trimming are used, ranging from just removing the backbone to full removal of all visible fat, pinbones and the skin. Some customers require that all intramuscular bones are 250

removed, to produce what is known as a â&#x20AC;&#x2DC;V-cutâ&#x20AC;&#x2122; fillet. For salmonids pinbones are pulled out (Figure 23). Trim A

Trimming salmon fillets Backbone, bellybone off

Trim C

The future, machine trimmig of fillet

Backbone, bellybone off, back fins off, belly fat off and pinbone out

Trim E Pull out the pin bones

Hand skinning salmon fillets

Fully trimmed and skin off

Figure 23. Processing methods for salmon fillets and trimming guide (Photo from Marel and other manufacturer). 251

Pinboning If you properly fillet for instance trout, the only bones that should remain are the bones that stick out of the sides of the fish. These are called the pin bones and are present in all trout, salmon and other related species. With large trout or salmon you can actually pull out the pin bones with a pair of pliers. That provides a wide range of pinbone removers for salmon and other species, extending from simple stand-alone machines to advanced units that integrate easily into new or existing production lines (Figure 24). The objective is to take out as many bones as possible without damaging the structure of the meat in any way, and to achieve maximum possible yield.

Figure 24. Pinboning fillets of arctic charr with pinbone remover (Photo: V.I. Gunnarsson).

Figure 25. Freezing and packing of arctic charr fillets (Photo: V.I. Gunnarsson).

Fish preservation Fresh chilled fish Most of the farmed fish are sold fresh, whole fish, fillets or in portions. To slow down the spoilage process fish are chilled with ice or other cooling media. Spoilage bacteria and lipid oxidation in fresh fish need oxygen, so reducing the oxygen around fish can increase shelf life. This is done by controlling or modifying the atmosphere around the fish, or by vacuum packaging. Controlled or modified atmospheres have specific combinations of oxygen, carbon dioxide and nitrogen, 252

and the method is combined with refrigeration for more effective fish preservation. Freezing of fish For storage of weeks or months, fish are frozen as whole gutted fish, fillets or in portions. Even when the most effective chilling methods and further chilled storage of raw fish and fish products are applied, shelf life is limited. As a result of rapid refrigeration free water content of raw materials is frozen to tiny ice crystals which are smaller than the cell wall, therefore, though they strain the cell wall they do not split it. When fish are frozen it strongly limits the microorganic activity while raw materials remain able to retain their biological value and taste. The fresher the product, the more satisfactory the frozen product will be. Freezing cannot improve the flavor or quality of food. Freezing temporarily stops the growth of spoilage organisms, but do not kill them. Once frozen foods thaw, surviving organisms grow. Smoking of fish Fish curing includes drying, salting, smoking, and pickling, or by combinations of these processes and have been employed since ancient times. For farmed fish smoking is most common especially for salmonids, but also involves drying and salting of fish. Traditional smoking: Salting and drying indoors in a smoky atmosphere has been one of the principal methods of processing fish for many centuries. In the past, salting fish was following by heavy smoking in simple chambers or chimneys in which the fish was suspended over fires. The smoke and heated air resulted in drying of product and absorption of smoke particles and vapours. Smoke components (phenols, acids, formaldehydes, creosotes) have antigerm and antioxidative impacts on the products. Traditional smoked fish tended to be very salty, dry and heavily smoked. Modern smoking techniques: Most modern fish-smoking systems maintain some traditional aspects, bur the smoking and drying periods are far shorter, and processors use much less salt. Salt and smoke are nowadays used primarily to flavour the products. It is therefore important to keep in mind that these milder processes result in only a small extension of shelf-life compared to that of raw fish. Difference in smoking techniques: Smoking techniques can vary widely from one region to another and are highly dependent of taste preferences. They are used with different temperature; cold smoking (< 30째C), warm smoking (30-80째C) and hot smoking (90-120째C). The different techniques use different type of wood, mostly hardwood 253

shavings or sawdust. In addition to wood smoke, liquid smoke can also be used. In liquid smoking, fish is dipped into a concentrate of liquid that has been used to absorb smoke.

References Borderías, A.J. and Sánchez-Alonso, I. 2011. First processing steps and the quality of wild and farmed fish. Journal of Food Science 76(1): R1-R5. ( Bykowski, P. and Dutkiewicz, D. 1996. Freshwater fish processing and equipment in small plants. FAO Fisheries Circular. No. 905. Rome, FAO. 1996. 59p ( Hoitsy, G., Woynarovich, A., Moth-Paulsen, T. and Avento, R. 2012. Guide to small scale trout processing methods. The FAO Regional Office for Europe and Central Asia. 22p. ( ut/processing_en.pdf) Humane Slaughter Association’s (HSA). Humane Harvest? ( Kestin, S.C. and Warriss, P.D. (eds.) 2001. Farmed fish quality. Fishing News Books. 430 p. Marine harvest 2013. Salmon Farming Industry. Handbook 2013 ( ok%2027-04-13.pdf). Valdimar Ingi Gunnarsson 2001. Meðhöndlun á fiski um borð í fiskiskipum. Sjávarútvegsþjónustan ehf. 139 bls. (In Icelandic). ( Yue, S. An HSUS Report: The Welfare of Farmed Fish at Slaughter. ( Further information – Webside and video Harvesting and processing Whole-Salmon Grading and Distribution ( Farmed whitefish processing (


XIII. Managing, Marketing and Cost Management of Fish Farming Authors: Wioletta Czernatowicz, Maciej Dymacz, Assoc. Prof. Dr. Halis Kalmış, Batuhan Demir

Marketing is needed to make your company increase the amount of customers and profit. How far you will take your company to develop is also determined by marketing staff.

Successful marketing strategy can give your business plenty of benefits as follow.  Marketing strategy can help your company to focus on what your customers need and want from your product. Aiming target market to be your permanent customers is not an easy task; therefore, you should focus in making a good connection between the company and the target.  Make people know about your product is what marketing strategy can do. It will be wasteful if you has brilliant product but no one knows it. Consequently, the growth of your company can be done through promotion or advertisement of the products in various media.  Customers are king and should be treated as good as possible. Here, the marketing strategy can help you to make good relationship with them. Hire professional employees is



necessary so new customers come and the previous customers will come again to buy your product. Marketing strategy can assist you to reach the companyâ&#x20AC;&#x2122;s goal. All the things above can be evaluated monthly to make a better strategy for the next expected result.

Marketing management Marketing management is a complex process that includes: strategic and operational planning and implementation phase. Strategic planning (strategic marketing) should include long-term objectives (strategic) and the framework guidelines, defining the way of arriving at them, or identifing marketing strategies. This stage is often called strategic management. Its basic elements is to determine: the mission (as it defines the business and sets out the basis of its philosophy), a strategic vision (a picture of the future and the market position), the aims and objectives for future operations and strategies (guidelines, rules and instruments of the market). In this phase there is a choice of action or market segments. The basic tools of strategic planning are: SWOT analysis (strengths, weaknesses, opportunities and threats), portfolio analysis and analysis of the relationship: the product - the market. Operational Planning (marketing mix) includes the specific expression of the arrangements accepted. The accomplishment of this operative is a marketing plan. It specifies the short-term goals. The plan also indicates product policy, distribution, promotion and pricing. The diagram of marketing management is in practice far from the idealized model. The differences indicate particularly in the sequence and, prior to the implementation phase. The complexity of the marketing management process results from the specific kind of marketing decisions. They are usually taken on the basis of incomplete information on market processes, which mutually interact.

1. Marketing strategy The starting point in determining the marketing strategy is to seek opportunities at the market. An opportunity for fish farmers is to find or identify the group of buyers, whose needs can be best satisfied by a fishers. Opportunities must be confronted with the mission of the fish farm, with his objectives and the resources, with a particular emphasis 256

on its strengths. Only on this basis the formulation of marketing strategies, defining the activities in the area of products, pricing, distribution channels and promotion can be done. The concept of marketing strategy includes therefore:  Internal factors: strengths and weaknesses of the farm;  Environmental condition: opportunities and threats;  Strategic objectives;  Specific decisions related to the intentions in the sphere of products, pricing, distribution and promotion process;  Ways of practical implementation of the earlier establisments;  Systematic monitoring and analysis of the effects of strategic actions in the sphere of marketing. The elements of marketing strategy are:  Product – “ the right product” must be closely related to the customer’s needs and desires.  Price - must be at an appropriate level, taking into account both the income opportunities of customers and their aspirations about the quality, prestige, etc.  Place - the product must be delivered precisely to the consumers (target market) in order to be accessible and achievable.  Production - communication messages must be sent to consumers (buyers) to learn about the values of the product, price, place and conditions for its acquisition, and why you should buy exactly this product, and not the other one.


Consumers should be-if it is possible – similar in their response to the marketing elements. They should be grouped due to such criteria as(age, family, education level, interests, life styl, life values ). Marketing strategies define markets that should be supported, as defined in terms of types of needs, consumer groups and product groups, which are to be produced on the basis of environmental features, resources and objectives. World fish supply and demand The wild fishery isn’t able to meet demand of population due to a decreasing global catch. As a result, consumers are looking towards aquaculture to provide healthy food choices and a product that is available year round. The global demand for healthy food is increasing and aquaculture is a key factor in keeping people fed. Strategies due to the type of dominance These strategies shall be adopted if we consciously aim to fight with the competition. They are differentiated by a type of competitive dominance in conjunction with the field of the activities in which you want to achieve an advantage:  A strategy of leadership in terms of costs;  A strategy of leadership in terms of diversification;  The strategy of focusing on selected market segments. At the same time it must be remembered that the idea of competitive advantage is the root of any competitive strategy. Strategies due to market participation There are four main strategies: market leader (40%), challenging the company (30%), forgery strategies (20%), or strategies that look for market gaps (10%). Leadership strategies are characterized by high market shares, pricing or cost-leadership. It requires a lot of effort to maintain the leader posistion. Strategies for challenging, require a clear definition of strategic objectives, such as increasing market share, identifing an opponent whose weaknesses are attacked frontally (in terms of quality, price, etc.) or avoiding competition. Forgery strategies, rely on the adaptation of offers for those products or companies that imitate, if there is no competitive between companies. This strategy can be well tolerated by the leader. Strategies for searching market gaps (niches), are characterized by action on a small section of the market, they help to avoid 258

confrontation with stronger competitors. This strategy requires a high degree of specialization, which refers to specific markets, purchasing groups, products.

2. Marketing mix In every business in every country that allows free competition, it is necessary to pay attention to marketing strategy. It is because that the success or failure on the market depends on the results in comparison with competitors. For this reason, the ingredients of mix marketing product, price, promotion and place - are crucial.

Product strategy The product has many features, these are:  Physical characteristics,  Brand names,  Product and company image,  Social and cultural associations with the product. All of these features influence the perception of the product by customers. This is important and will affect their decision regarding the purchase of the product. The product can be analyzed in three levels of existence (functioning). The first level of the product is called "root",


the second level is a real product, and the third level – is the "improved” product. Pricing policy Pricing policy is another important element of the marketing mix. Price that is required for the offered product must meet the following requirements:  Cover all costs associated with delivering a product to a consumer (from production to consumption),  Provide a profit,  Approximately reflect consumer’s perception to the value of the product,  Have a relationship with other elements of the marketing mix so that pricing is not the only way to compete with other products. Establishing the price One of the most difficult decisions faced by each fisher is to determine the price for the products offered for sale. In making this decision such factors should be taken into consideration:  The extent to which the product is known in the market,  Position of the product on the market,  The potential and practical competition for the product,  Production costs,  Distribution channels. Among these factors, one of the most important activities are usually competitors actions. Many factors affect the way we set prices for products. In normal conditions, when there is an intense competition for the product, a price must be very similar if not identical, to the price of competitor's product. Fishermen work exactly in such situation. The market sets the price for their products and they all get a very similar price for manufactured goods. In order to distinguish our product from the competitor's product, you can enter the business name (brand). If the branded products will have a positive mark of clients, as a result the price can be raised. The entrepreneur who has set the best branded product can operate on the "price leader. " He sets the price conditions, to which the competition set its prices. Pricing strategy When establishing the price several different factors play an important role. One of the most basic, is to set prices based on production costs. It consists in adding the margins to the cost of the 260

product. You can also set a price, taking into account the price in the competitive company. The third approach is pricing based on demand. It consists in estimating the demand for the product at different prices and setting a price to achieve the target level of sales.

Promotion strategy The aim of the promotion is to influence attitudes and behaviors of potential customers. The promotion, strengthen existing attitudes and change existing attitudes and behavior. Promotion should reinforce favorable attitudes and views of customers about our products and change their negative attitude. There are many ways of promotion. The most important of these include:  Individual sale;  Advertising;  Gaining notoriety;  Forming a favorable image of the company (public relations).

Distribution strategy The last aspect of the marketing mix, which should be considered is the category of space. This element is very important for the development of marketing strategy, because the product should reach the target market at the right time and in good condition. Decisions regarding the distribution, generally are long-term and have a significant influence on the management of all other elements of marketing mix. In developing the distribution strategy the most important issue is to identify the distribution channels and selecting the most suitable markets for the product. Very important matter is also transport what means delivering products to the markets. One of the important decisions that we must take is to determine whether to use the service of the intermediaries, or do it yourself. There are many advantages and disadvantages of both of these options. Therefore, in deciding on the best method of distributing the product, you must thoroughly analyze the individual characteristics of the particular product. Locating it near recreation centers or major roads passing through the tourist areas, usually provides a large number of customers. It is vital to have an pond or boat near the place of the purchase. Such an arrangement also allows better use of the other elements of marketing mix.


1. Promotion tools in fish farming For many years, there have been various ways of raising the customers and strengthening ties with them. Some of them are presented below:

Advertising Frequently definition says that it is a mass, charge and impersonal form of presenting the offer for sale by a particular sender. The essence of such advertising is to persuade potential customers to action. However, with the development of the economy, it appears that advertising can also apply for social purposes, non-commercial use, so there are attempts to modify the definition and classification to avoid advertising as a tool for commercial sphere. What are the goals of the advertising? The answer will depend on whether the advertisement will apply to the company or a specific offer. In the first case, this ad's image, which is aimed at creating a positive image, image of the subject. In the second - advertising in the traditional sense, to promote a particular brand / product. It is worth noting that in both cases, the message could be called advertising, it must contain two elements: information and persuasion. Information should be understood here as a measure to increase knowledge about a specific event, as the art of persuasion to convince someone because (through appeals, suggestions or rational reasons).

Public relations The term public relations (PR) comes from the English this approach is used to determine Fiction. Clearest definition of public relations is saying that PR is soliciting the favor of the environment through actions and words. From a practical point of view, such 262

classifications are irrelevant. Because it is important to PR in general use, so organize press conferences, create their own means of communication (eg website, reports on the functioning of the company or even paper crafts with your company logo), engage in lobbying, initiate publicity (events of interest to the general, which are free informed media), enable the environment with direct contact (open days, providing pens eg conferences). The PR is also a crisis management so image management, information, a situation threatening the continued functioning of the company. The essence of PR is to organize some positive actions (deeds) and then informing them about the environment, so as to be well adjusted to the company. In the future, this may lead to greater employee loyalty, and a better understanding of the difficulties of the company. Currently, the most widely used tool for PR seems to be a web page, it probably is any company. Although well-described in the company's offer, you can even download the logo, but there is no information about any good works, sponsoring efforts to ambient, etc. and what is prepared for the press, is vague and devoid of reliable facts. Thus, the function gaining favor and understanding of the company is by no means done. In this, and in other cases, this is probably due to the fact that the company does not have to be proud. Marketing & Public relations Email Marketing – 2x per month  Daily: monitor HARO, Reporter Connection, Source Bottle to ID media opportunities  Submission of content to applicable requests  Use social media and social analytic tools to identify online influencers in the female entrepreneurial community  Find appropriate online articles and blogs  Comment  Follow on Twitter  Note in database  Create targeted Twitter lists of influential bloggers and reports  Follow  Retweet  Use LinkedIn to connect with influential bloggers and reports  Follow 263

 

Comment on posts Cultivate and maintain relationships with reporters and bloggers  Build and manage targeted lists on ZOHO  Find guest blogging opportunities  Create press releases and media alerts  Member success stories  Women in business trends  Data from member surveys  Female entrepreneurship trends  Coworking trends   

Write and distribute regional press releases for HUB openings in the U.S. and international markets Track media responses and interviews Update and maintain press page on

Merchandising The word comes from the English merchand - merchant and merchnidise - product and marketing practice refers to the promotional activities at point of sale. Using a merchandising deal with margin, as the price for the service trade, commodity, communications stores, technology services and shaping the object. Visual merchandising is to create original and functional interior design and architecture point of sale outside. It will be so setting sales of furniture in the room, the other rooms are available for customers, air conditioning, adequate lighting, placement of signboards and other media, distribution of plants, selected colors, "visual" prepare staff. Exterior facade of the store, clear logo ( sign ), functional input, land designated for parking and roads, green areas. Of course, merchandising developed their own rules, rules that sellers should follow. Often administered a ' righthand rule ', which says that a customer entering the store at first looks to the right side, so as to arrange the goods for what was to come down from the shelves was in sight. In addition, you still need to organize a path through the aisles to the client was forced to go around the room as the largest area of sales. You can create blocks of goods - thematic of " one manufacturer " or functional type of " like products side by side." This way we get the full effect of the shelf, the effect of abundance, the called called facing - placing the greatest number of individual packages on the shelf. Furthermore it is known that 75 % of consumers in grocery stores and dairy buys bread, and therefore this particular range is placed as far away from the entrance, 264

etc. As regards the range of fish it is evident principle that the fish is not mixed with other articles and should be provide separate shelves/cold, mainly because of the spread of the odor. Merchandising also says that it should be put information about the product, such as the product, rather than above. Fairs and exhibitions Traders may (and should) communicate setting their achievements through various actions, including the presence at trade fairs and exhibitions. These events have their own distinctive features that allow to distinguish one from the other: trade is an organized form of the market (so focused supply and demand), in which the purchase is made on a large scale. Trade shows usually held regularly at the same time and same place. The essence of the fairs is to allow the transaction, or to establish contacts that would later lead to these transactions. For more information about the event for the fishing industry can be found in the 'event'. Exhibitions (which is 'economic') but are characterized by the fact that last longer, can be organized in different places and promote different countries / industries / companies. The most famous exhibit is the Expo, which runs from 3 to 6 months. Telemarketing Until recently, only telemarketing associated with the phone and definitions referring to this option are common. However, it should be noted that the prefix tele-comes from Greek and means 'at a distance'. Thus, telemarketing is not only "advertising of a product over the phone," according to W. Ĺ mid the "Lexicon Manager" (p. 368), but all that is associated with the marketing carried out at a distance and using different types of media. This concept seems more logical. Thinking about the telemarketing company can therefore consider sale / promotion directory (mail order), the sale of television and telephone, and trade in cyberspace. Personal sales Personal selling takes place wherever observed contact the seller and the buyer, so the broad sense of detail, often in wholesale and acquisitions. Such sales may also take place at the premises of the manufacturer, although it is certainly less frequent than in other cases. Function, personal selling, or task is: to inform customers, to obtain information from them, selling to buy the courteous and professional assistance, as well as create a good image of the company. Sale of 265

personal gains importance in a number of situations, namely when the product is complicated and you have to explain his action, the price of the product may vary (negotiable), as well as existing customers with product knowledge is low (for example, because it is new). Promotion materials (promotion or activation of additional sales) aims to change the perception of money - usually in a short time, the company offers something unique to the potential customer to say that now this offer is particularly attractive. Actions of this kind are common in many industries from various holidays, when, for example, before the mother show up on store shelves packed sweets referring to the feast, and it's still in assets (eg, metal) containers, so you can use them repeatedly rather than discarded. The same happens on the occasion of Christmas, Easter, Valentine's Day .... Although the manufacturers of fish also use metal containers, it is not seen to have adapted their aesthetics and symbols to come - not just religious festivals and events (such as the 100th anniversary of the company). At the end of the discussion on the promotion should probably point out that in practice the word is overused to describe 'price cut'. Anyone who has read the prepared material, may determine that it is wrong - although this option is the promotion of additional, when for a short time reduced price, but it does not authorize the conversion of the expression 'price cut' to 'promotion', because that would be huge reduction of the tools used within it.

4. Business plan The idea and importance of business plan A business plan is a special type of plan. It is a form of concrete goals and ways to market their implementation, both for the company itself, as well as to raise funds for starting a business, enter the company, issuing shares, attempts to bank credit, etc. A business plan is a good model to develop any plans, because the objectives, measures, resources, strategy and results of the project must be presented to demonstrate the skills and entrepreneurial skills and build up trust, necessary for obtaining a loan or increase a capital. A business plan is one of the modern techniques of management, making a preliminary condition for success in the market. A success will not be achieved without the knowledge of the market and the ability to predict and plan. 266

A business plan should be drawn up for each major project. It is an internal plan, setting out the intended actions, measures and methods and its implementation strategy, estimated costs and expected profits.

A business plan is necessary to:  Determine if a project is worth making and if it is worthwhile to devote time, labor and capital.  Verify the possibility of taking up the project.  Estimate the necessary resources and means and ways to generate them.  Examine the benefits and possible risks to the project.  Develop strategies for its implementation.  Point out the tasks for the participants of the project. The degree of formalization of the business plan depends on the nature of the project and the purpose for which it will serve. In any case, both the object and its form, must satisfy the requirements of objectivity throughout the development, pricing, the expected risk and the probable company's profit. The structure of a business plan Here are a few practical observations and an example of the structure of a business plan together with a number of questions, which should facilitate the process of planning and to taking appropriate decisions on strategy and effective management. 267

Preparing a business plan requires:  defining the tasks and the recipient,  drawing the preliminary plan,  preparation of the next part of the plan including: the aim of the plan, the profile of the farm and its characteristics, market analysis, marketing strategy, staff qualifications and financial situation. The basic layout of the content might look like this:  Front page of a business plan should include: company name, address, logo, name of the owner's, address and telephone number, date of preparation of the plan, company name (s), person who make the plan,  Summary of the plan from which the recipient usually begins to present a plan, a preliminary feasibility assessment of plans and benefits of participation. It also contains the key elements to develop a business plan,  Characteristics of a product (products),  Characteristics of the customer and market analysis market size, trends and development - the potential growth of the market (it is recommended that the business plan includes analysis of the last three years and predictions for the next 5 years), the company's position in the market,  Sales and distribution – kind of sales (direct sales, agents, other solutions), keys customers and percentage of the purchase of products,  Promotion – methods and instruments of the promotion and advertisement, annual spending on promotion, seasonality of sales and production,  Price - pricing policy for all product groups, price sensitivity to changes in the cost, cost of sales as a percentage of earned income and their variability depending on sales volume,  Competition (how the company will compete with others) the most important competitors and their: name, address, size of their sales, market share, strengths and weaknesses of the competition, type of competition: image, location, product, services, pricing, advertising, sales methods,  Project location – where production is located, the economic base in this area, distance from the market,  Management skills - age and education of the owner (s), the financial status of the owner (s), professional experience, management structure and division of competences, the use of counseling and consultation, 268

 

Staff - qualifications, skills, salaries, Investments and loans - a plan for the necessary investment, the time of their implementation and their cost, the projection of loan needed to complete the planned investments, Timetable for project development - a list of objectives divided into foreground, short-term and long term strategies, target market, product features, price, promotion, distribution, and the necessary resources and relevant factors affecting the success, Financial plan is the most difficult but also the most important stage of the planning process. It is usually drawn up for the next 5 years. The first step should be a monthly or quarterly analyze.

Balance sheet assets This is a summary of financial assets and liabilities drawn up on a given day.

4. Production costs calculation The precise knowledge of the level and cost structure is one of the conditions for success. What is need is a detailed calculation of all variable and fixed costs, as well as the determination of the frontier point of production volume at which there is an equality of the total cost of revenues (the threshold of profitability). 269

Table 1. Balance sheet assets Specification


Liabilities in EUR

Assets A. Fixed assets 1. Land 2. Buildings 3. Machines and equipment 4. Means of transport B. Current assets 1. Stores 2. Charges 3, Cash (in hand, in bank) C. Other Assets together: Liabilities A. Equity B. Loans and credits C. Current liabilities D. profit left E. Private capital Liabilities together:

Income statement. Shows the profits and losses in a certain period. The above information allows potential investors and lenders to determine the risks and determine the acceptable conditions on which there will be an agreement (contract). Calculation of income and expenses is as follows: Expected revenue from the sale of goods and services - the expected cost of revenue (variable costs + fixed costs) = expected profit from operations - f - extraordinary gains, extraordinary losses = gross profit income tax = net profit. Cash Flows Calculation: Cash inflows and outflows The summary of projected cash flow gives a dynamic picture of the incoming streams and outflow of cash from the farm. The list shall also 270

provide information on cash needs, the need to take a loan to cover current expenses, the repayment capacity of the surplus cash available in subsequent periods. It also helps to plan the best use of liquid cash and prepare for investment decisions. It should be noted that by making statements of cash receipts and expenditure in each month only the receipts and payments made in cash are taken into consideration. To prepare an overview of the planned cash flows in individual months, quarters and years, it is essential to plan the volume of sales in subsequent periods, including the sale of cash and deferred payment. The same should be done with expenses. Table 2. Financial flows scheme Month, year


Opening balance (cash)EUR Cash sales Proceeds of the current receivables Growth in equity Sale of personal assets Investment Credits Working capital loans Other income Total receipts Total cost of revenues (excluding amortization) Repayment of loans Repayment of interest Investments Taxes Dividends Discretionary fund Total cash expenditures Cash balance at the end of the month of the year The cumulative cash balance at the end of the month of the year






Cash balance at the end of the month, shows our cash resources, which we have in the next month or estimated deficiency to be remedied (external financing such as loans) to meet all the needs of cash during the month. Balance at end of each month is the sum, the volume of cash accounting opens next month. Transferring the balance from month to month, we get the total balance of cash resources in the long run so called cumulative flows. Evaluation of the investment efficiency Investing is buying certain goods such as machinery and equipment, buildings, land or a whole company. This process has its economic base. We buy, we commit capital in the hope that in the future, we will not only recover invested (interest) money, but also get surplus (profit). Future benefits will outweigh the initial capital outlay. The analysis of the efficiency of investment should answer the question: "Are the benefits gained in the future higher than the cost of investment? "The most common methods of evaluation are: - WAN - Net Present Value - Indicator B / C -Benefits to Costs Ratio - WSZ - IRR Internal Rate of Return Net Present Value + RVA PPO - the initial outlay PPN - expected net benefits q - the discount rate (cost of capital) n - the expected payback RVA - residual (final) If the WAN is positive, meaning that the discounted (expressed in today's U.S. dollars) future benefits are higher than the initial investment outlay, the investment makes sense and should be implemented. If the WAN is negative the project should be rejected. If two projects are mutually excluded, the one that has a higher WAN should be chosen. Indicator B/C It is based on the same assumptions as the Net Present Value method. It defines the relationship between the benefits and the initial effort. If the discounted benefits are greater than the initial cash outlay, the rate of B / C> 1, then the investment makes sense, at a ratio B / C <1 investment should not be implemented. 272

Internal Rate of Return Internal rate of return is the discount rate at which the Net Present Value is zero and B / C is equal to one. With such a discount rate (cost of capital) outlay will be paid to the assumed period of time. Comparison of interest rate with the Internal rate of Return indicates whether the investment makes sense. If the Internal Rate of Return is greater than the cost of capital (interest rate, which we have to pay), an investment makes sense.

Financial reporting and cost management of fish farming Fish farming, also known as aquaculture, involves the planned growth and cultivation of fish for harvesting as food, as opposed to catching fish in the wild, according to the environmental. Aquaculture, the farming of aquatic animals and plants, is one of the worldâ&#x20AC;&#x2122;s fastest growing food production sectors. Today, almost half of all seafood we eat comes from this source. Fish farming is the process of raising fish in an enclosed area for commercial purposes. A fish farm can be built on land or over naturally occurring water bodies. Many fish farms are highly technological and man made facilities have been incorporated to control every aspect of aquatic life. Fish farming is a agricultural activity. Agricultural activity is the management by an entity of the biological transformation and harvest 273

of biological assets for sale or for conversion into agricultural produce or into additional biological assets. Agricultural produce is the harvested product of the entityâ&#x20AC;&#x2122;s biological assets. A biological asset is a living animal or plant. A biological asset shall be measured on initial recognition and at the end of each reporting period at its fair value less costs to sell, if the fair value can be measured reliably. Fair value is the amount for which an asset could be exchanged, or a liability settled, between knowledgeable, willing parties in an armâ&#x20AC;&#x2122;s length transaction. A gain or loss arising on initial recognition of a biological asset at fair value less costs to sell and from a change in fair value less costs to sell of a biological asset shall be included in profit or loss for the period in which it arises. The process of production in fish farming is not much different when compared with other manufacturing companies. Aquaculture companies calculate the cost to produce fish with a view of the amount of fish feed consumed by fish that are kept. Basically the production costs are all the expenses incurred during the production process and, subtracted from the turnover (sales), they determine the income before taxes. Their amount results from a combination of technical and commercial choices. Technical choices (production process) determine the needs for the inputs (quantities of feed, juveniles, labour, loans, ...) and the commercial choices the amount of money to be spent on it according to the price of each item, including the interest which is the price of money. In the same manner technical choices determine the level of production and commercial strategy the value of the production. The total cost per unit produced (kg of fish), and the breakdown of this total cost are good criteria, among others, to compare the production from different systems, different scales or different areas, and thus judge their competitiveness. In the case of combined productions (two or more different species and/or sales at different stages) the accounting of the costs and income must be analytical, i.e. divided according to the contribution in each production. So, fish farms must provide information about the costs, income, the financial position, financial performance and cash flows that is useful to a wide range of users in making economic decisions.

Financial reporting of fish farming The objective of Financial reporting is to provide information about the financial position, financial performance and cash flows of an 274

entity that is useful to a wide range of users in making economic decisions. Financial reporting is done by financial statements. Financial statements are a structured representation of the financial position and financial performance of an entity. Financial statements also show the results of the management’s stewardship of the resources entrusted to it. To meet this objective, financial statements provide information about an entity’s assets, liabilities, equity, income and expenses, including gains and losses, contributions by and distributions to owners in their capacity as owners, and cash flows. A complete set of financial statements acording to IAS’s comprises: (a) a statement of financial position as at the end of the period; (b) a statement of comprehensive income for the period; (c) a statement of changes in equity for the period; (d) a statement of cash flows for the period; When preparing financial statements, management shall make an assessment of an entity’s ability to continue as a going concern. An entity shall prepare its financial statements, except for cash flow information, using the accrual basis of accounting. When the accrual basis of accounting is used, an entity recognises items as assets, liabilities, equity, income and expenses. An entity shall present separately each material class of similar items. An entity shall present separately items of a dissimilar nature or function unless they are immaterial. Financial statements result from processing large numbers of transactions or other events that are aggregated into classes according to their nature or function. The final stage in the process of aggregation and classification is the presentation of condensed and classified data, which form line items in the financial statements. An entity shall not offset assets and liabilities or income and expenses. An entity shall present a complete set of financial statements (including comparative information) at least annually. Normally, an entity consistently prepares financial statements for a one-year period. an entity shall disclose comparative information in respect of the previous period for all amounts reported in the current period’s financial statements. An entity shall include comparative information for narrative and descriptive information when it is relevant to an understanding of the current period’s financial statements.


Identification of the financial statements The statement of financial position ( Balance sheet): Balance sheet is a report that shows financial position of an anttity in a given time. As a minimum, the statement of financial position shall include line items that present the following amounts: (a) Property, plant and equipment; (b) Investment property; (c) Intangible assets; (d)Ffinancial assets (e) Investments accounted for using the equity method; (f) Biological assets; (g) Inventories; (h) Trade and other receivables; (i) Cash and cash equivalents; (j) Trade and other payables; (k) Provisions; (l) Financial liabilities (m) Liabilities and assets for current tax, (n) Deferred tax liabilities and deferred tax assets, (o) Issued capital and reserves attributable to owners of the parent. An entity shall present current and non-current assets, and current and non-current liabilities. Statement of income: An entity shall recognise all items of income and expense in a period in profit or loss These elements provide users of financial statements with information about some of the changes in an entity’s resources and obligations. This helps users to understand the return the entity has produced on its economic resources.This information in turn helps users to assess the entity’s prospects for future net cash inflows. It does this not only directly but also, by helping users to assess how efficiently and effectively the entity’s management have discharged their responsibilities to use the entity’s resources, indirectly. Thus, information about income and expenses is useful to users of financial statements for decisions about providing resources to the entityThey are subtotals or totals derived by summing items of income or expense.An entity shall present an analysis of expenses recognised in profit or loss using a classification based on either their nature or their function within the entity, whichever provides 276

information that is reliable and more relevant. Expenses are subclassified to highlight components of financial performance that may differ in terms of frequency, potential for gain or loss and predictability. An entity shall disclose the aggregate gain or loss arising during the current period on initial recognition of biological assets and agricultural produce and from the change in fair value less costs to sell of biological assets. Consumable biological assets are those that are to be harvested as agricultural produce or sold as biological assets. The fair value less costs to sell of a biological asset can change due to both physical changes and price changes in the market. Separate disclosure of physical and price changes is useful in appraising current period performance and future prospects, particularly when there is a production cycle of more than one year. Costs to sell are the incremental costs directly attributable to the disposal of an asset, excluding finance costs and income taxes. Statement of changes in equity: An entity shall present a statement of changes equity as the residual interest in the assets of the entity after deducting all its liabilities. equals total assets, less total liabilities. Total equity at the end of a period generally equals total equity at the start of the period, plus contributions to equity in the period, minus distributions of equity in the period, plus comprehensive profit or loss for the period; plus capital maintenance adjustments. Statement of cash flows: The objective of this statement is the presentation of information about the historical changes in cash and cash equivalents of an entity by means of a statement of cash flows, which classifies cash flows during the period according to operating, investing, and financing activities. Cash flow information provides users of financial statements with a basis to assess the ability of the entity to generate cash and cash equivalents and the needs of the entity to utilise those cash flows. Cash flows must be analysed between operating, investing and financing activities. Operating activities are the main revenueproducing activities of the entity that are not investing or financing activities, so operating cash flows include cash received from customers and cash paid to suppliers and employees. Investing activities are the acquisition and disposal of long-term assets and other investments that are not considered to be cash equivalents. 277

Financing activities are activities that alter the equity capital and borrowing structure of the entity. Interest and dividends received and paid may be classified as operating, investing, or financing cash flows, provided that they are classified consistently from period to period. Cash flows arising from taxes on income are normally classified as operating, unless they can be specifically identified with financing or investing activities. For operating cash flows, the direct method of presentation is encouraged, but the indirect method is acceptable. The direct method shows each major class of gross cash receipts and gross cash payments. The indirect method adjusts accrual basis net profit or loss for the effects of non-cash transactions.

Cost management of fish farming Purpose of a business is to earn financial returns by serving a targeted all buyers in a market. At the present day, businesses generally compete both in domestic and foreign markets. Primary condition of competition is effectively and efficiently to accomplish components such as superior quality, low cost and speed that acquire competitive force to businesses. The way of accomplishing these components is possible by managing activities which are necessary to produce products and services in a more effective and efficient way. Managing activities depends on that they can be measured. Cost management makes the measurement of activities possible and supplies to managers the information needs to be relevant results of activities. Measuring the cost and performance of activities and resources, businesses can improve the value received by the customer and the profit achieved by providing this value. When a business carries on its activities in a more cost-efective way than its competitors do, it will also have a competitive advantage. Cost management identifies the true link between costs and revenues, and can reveal hidden costs as well as profits in providing products and servicing customers. Thus, cost management becomes an important decision-making tool for businesses.

Cost management In releted issues of cost management, instead of directly definition of cost management, it has been given goals and objectives of cost 278

management by expaining factors that make it necessary. Cost management provides possible of measuring a business’ performance in topics such as quality, flexibility, service, timing and cost by combining financial and non-financial indicators.. Within this context, as a system, cost management aims to provide information to help businesses use resources profitably and effectively to produce products and services that are competitive in terms of cost, quality, functionality and timing in the market, by identifing the cost of resources consumed in performing significant activities of the business, determining the efficiency and effectiveness of the activities performed, and identifing and evaluating new activities that can improve the future performance of the firm. Cost management begins with an awareness of what events cause costs. This awereness is the prerequisite for a full understanding of costs. Cost management uses cost information to evaluate how effectively a business consumes resources to create products or services that have value to customers. Therefore, the philosophy of cost management offers an appropriate framework to identify causes (activities) and effects (costs). Approaches based on cost management are as follows according to the needs of businesses.

Cost containment The cost containment is an approach focused the covering or avoiding the increases in the fixed and per unit variable cost in the future. The philosophy of this approach bases on performing in basis of same productivity and efficiency, in future, activities performed by businesses. In terms of the businesses, it must be known well the nature and formation of costs in order to acquire expected utility. Fixed costs are the cost that doesn’t change in total even though changes in activity capacity realized. These costs are also a part of the total of products so that any reduction in the activity increases in the total cost of per unit. Fort he reason, business administration should take into consideration the structure of such costs in case of making a decision. Reasons causes increases in fixed costs that are: activities performed inefficient and sources that are not used effective and productive, operating in the low level of production capacity for reasons such as small market share, not being capable of taking advantage of scale economies or not producing product or services that creates added value and meets customers’ needs and has quality. Business’ managers can avoid these costs by making decision in direction of the


correct information that they can acquire from cost management system. On the other hand, variable costs are the costs that do not change for per unit but change in total though activity volume can change. These costs are the costs of activities that are performed related with the products produced. Therefore, performing of these activities at the same effective level and usage of reseources to perform the activities in the same level of effective and productivity, it will ensure to cover the cost at the same level.

Cost avoidance: Cost avoidance is an approach for eliminating of the activities that can not explain its benefit on the bases of cost-benefit analysis are removed. The philosophy of this approach depends on eliminating of the activities that doesnâ&#x20AC;&#x2122;t creat added value and performing in costeffective way of the activities that creates added value. Therefore, managers of business should classify the activities as value added and not value added by determining activities firstly and it is required that they should seek and apply the way of those with a participatory approach of how them to be eliminate or to be reduce as possible as activities that not have value added, and how them to perform in the cost-effective way of activities that have value added later.

Cost reduction Cost reduction is an approach that focuses cost reduction on variable and fixed costs relating to activities that is essential in term of a business in current period. The philosophy of this approach depends on reduction in costs relating to activities that is essential in term of a business in current period. It is possible with that managers would provide to be use in effective and productive way the resources consumed to perform activities and perform activities.

Costs and cost management in fish farming Fish farming is a business that it has different features. Cost management are directly related with the business of industry. The experience from the industry is also possible for the fish firmng. Notwithstanding, cost management can principally implement for 280

every business, including fish farming. Fish farmers can benefit from cost management practices and require to know them.

Costs and cost classifications: Cost are a measure of the resources consumed to provide a product or service. A fish farmer have to also compute costs on a total or on a per unit basis such as every organization. Total costs represent the aggregate resources consumed by the a product, a work area or an activity. Total costs are generally summarized by major cost categories (e.g., labor, material, and facility costs) or by functional areas (e.g., manufacturing, sales, management). A unit cost is the cost of one unit of measure of a product or service. The unit cost is simply the average cost, which is the total costs divided by the total volume in units. Unit of measure is important and should identify the output of organization in a meaningful manner- for example, units of products, units of fish, kg of fish. The unit costs are useful to measure productivity or detect significant cost trends. Costs must be classified according to the purpose for which they will be used â&#x20AC;&#x201C;for decision-making purposes. Different costs have different purposes. Costs that are classified and recorded for one purpose may not be appropriate for another. Here, it will be focused on cost classifications of which are useful and valid for fish farmers. Fixed and variable costs: In this classifying cost, it is established a relationship between the cost of an item (the cost object) and how it reacts to changes in volume or usage levels. The cost object is the item being measured; activity levels are measures of volume or usage that vary according to the cost object. Costs are classified as fixed or variable with respect to the cost object and how it behaves with changes in volume or usage. So cost classification is important for decision-making purposes. Fixed costs do not change in total with changes in volume or activity levels- for example, depreciation on building, machinery and equipment, property taxes, rent, administrative expenses. Fixed costs are considered fixed only in the short run, a brief period of time in which the quantities of the available resources cannot be varied. In


the long run, all costs are variable. However, fixed costs are varied on per unit basis. Variable costs change proportionately with increases or decreases in activity levels. Variable costs vary directly in total with changes in sales or production volume or some other measure of activity; however, they remain constant on per unit basis. Some costs are semivariable; they have a fixed and a variable component. Maintenance and repairs cost is an example of semivarible cost. Costs are also classified according to the functional area in which they are incurred (e.g., administrative, marketing and selling, research and development,and manufacturing). Manufacturing (production) costs are the costs required to produced a product. Manufacturing costs are composed of three major elements: Direct labor, direct material, and overhead. Direct material cost includes the costs of all raw materials that are used to manufacture the finished product. Direct labor costs are composed of all labor costs related to the time spent manufacturing a product. Overhead costs consist of all other manufacturing costs that are not included as direct labor or direct material. For example: indirect labor and materials, depreciation, utilities (electricity, water, gas, fuel, and telephone), rent, and maintenance. Overhead costs are usually incurred in a production department or unit and are related to more than one product or product family. Therefore, overhead costs must be assigned in some meaningful and systematic way to individual products. This process is called overhead allocation.

Calculating the cost of product for fish farmers Costing is not simple and many times, not straightforward. It can be produced a lot of product in fish farming activities. We can recommend to fish farmers the general costing guidelines that can be applied in any company or industries. This approach will result in the availability of more accurate cost information for management decision-making purposes. Step 1. Define the Item to Be Costed: Item or object to be costed can be almost anything in an organization; a product (fish), a business 282

process. A clear definition of the cost object defines the scope of the costing exercise. The scope and the availability of information will determine the organizational resources required to develop the desired costs. Step 2. Understand the Purpose of the Costing exercise: An organization uses different costs for diffirent purposes- for example, determine product profitability and cost, making decision, capacity utilization. Step 3. Determine the Cost Basis: Costs can be estimated on an actual or projected basis. Actual costs show what has happened in the past based on historical data; therefore, they may provide a more accurate representation of the business. Projected costs are estimated future costs that are based on historical data, industry forecasts. Projected costs are used in the preparation of budgets, capital investment analysis, and other key management decisions. Step 4. Identify the Major Cost Components: As explained above, there are three cost components in any cost analysis: Direct labor, direct materials, and overhead. Step 5. Calculate the Cost: Based on the information gathered in step 2-4, it can be calculated the product costs. Individual costs are calculated for each key cost components and then added together to obtain the total cost of a product.

Cost-volume-profit analysis for fish farmers By studying the relations of costs, sales, and net income, fish farmers better able to cope with many planning decisions. CostVolume-Profit (CVP) analysis is a tool using for planning decisions. It looks at the effects on profits of changes in such factors as variable costs, fixed costs, selling prices, volume, and mix of products sold. Break-even analysis, a branch of CVP analysis, determines the breakeven sales. Break-even point is point where revenues exactly match costs. This analysis can be useful for fish farmers. So, fish farmers will be able to calculate the sales necessary to break-even or to achive a target income. The break-even point represents the level of sales revenue that equals the total of the variable and fixed costs for a given volume of output at a particular capacity use rate. The break-even point can be calculated in units and amount. The break-even point in units = Fixed Costs / (Unit selling price- Unit variable cost)


in amount = Fixed Costs / ((Unit selling price- Unit variable cost)/ Unit selling price) or in amount = Fixed Costs / ((Total Tales- Total variable costs)/ Total Sales) If a fish farmer will calculate to achive a target income, target income amount is added the fixed costs.

References Berliner, C., and Brimson, J.A., (1988), Cost Management for Today’s Advanced Manufacturing (The CAM-I Conceptual desing), Boston: Waren, Gorham and Lamont. Groth, K., (1994), Cost Management and Value Creation, Management Decision, Vol. 4., No. 4, pp. 1-6. Guziur, S.,1997. “Chów ryb w małych stawach” Wyd. Oficyna Wydawnicza HOŻA; Warszawa İnternational accountanting Satandards 1, IAS 7, Johnson, H.T.,(1990), The Decline of Cost Management: A Rrinterpretation of 20 ʰ Century Cost Management History, Emerging Practices in Cost Management, Ed.: Ed.: B.J. Brinker, Boston: Waren, Gorham and Lamont, pp. 137-144. Advantages of Marketing Strategy for Your Business - article Buisness next door). aquaculture awareness) (articles in Marketing) (article - Full-time Marketing Coordinator Position) Kalmış, H., (2003), Cost Management as a Decision-Making Tool for Managers in the Global Competitive Environment, Journal of Naval Science and Engineering, July, pp. 115-122. Lewandowski, K.D., 1992. “Krainy jezior w Polsce” Wyd. Państwowe Wydawnictwo Rolnicze i Leśne; Warszawa. Napitupulu, Ilham Hidayah and Widyo Nugroho, Cost of Production at Business Unit in Aquaculture Industry: Study at Aquafarm Nusantara Company, Journal of Modern Accounting and Auditing, ISSN 1548-6583, May 2012, Vol. 8, No. 5, 671-678. Oliver, L., (2000), The Cost Management Toolbox, New York: Amacom. Player, S., (1996), Insight in Cost Management, Controller Magazine, August, pp. 55-56. Shim, J.K., and Siegel, J.G., Modern Cost Management & Analysis, New York: Barron’s Business Library. Stópkiewicz, S., 2009. “Ryby nasze” Wyd. Klub dla ciebie; Warszawa. Weil, R. L., and Maher M.W., (2005), Handbook of Cost Management, New Jersey: John Wiley & Sons, Inc.


XIV. The Future of European Aquaculture Authors: Prof. Dr. Ergün Demir, Dr. Hüseyin Eseceli, Dr. M.Akif Özcan, Metin Akbulut, Batuhan Demir, Mesut Yıldız, Hasan Azak

Trends and triggers of the European Union aquaculture There are new trends in aquaculture production in the world. The main route of the the trends is to keep environment, biodiversity and human health. Aquaculture provides huge opportunities and raises considerable challenges, particularly in relation to environmental sustainability of production as well as to the quality and safety of the products. The main function of aquaculture is to provide safe food of the highest nutritional benefit and quality, supplying a broad range of products adapted to consumer preferences and lifestyles. Seafood is a key component of the diet of many European citizens and supports societal health and a high quality of life. In Europe, aquaculture also generates jobs for an estimated 100,000 people in production, 60,000 in processing and 3,000 in the wider research community. In addition, service companies provide many additional jobs. Globally, aquaculture provided 43% of aquatic animal food for human consumption. The world population is increasing. In order to maintain at least the current level of per-capita consumption of aquatic foods, the world will require an additional 23 million tonnes thereof by 2020. This additional aquatic foods will have to come from aquaculture. FAO estimates than by year 2030, 65% of all seafood consumption will come from aquaculture. However, the EU aquaculture production, according to reports and based on FAO data, represents only 1.6 % of the world aquaculture production in volume and 3.3 % in value. It shows that the EU contribution to world aquaculture production has been decreasing significantly over time. European aquaculture is an extraordinarily diverse sector, predominantly devoted to fish and shellfish production, which is 285

present, in different forms and scale, throughout the continent. While climate and location influence the choice of species and production technology, changing consumer preferences and market demands continue to provide new challenges and opportunities for product development and diversification. Highly skilled personnel are active within each component of the value chain that, aside from professional producers, includes equipment and feed suppliers, veterinary and health services, and processors. European technological advances, obtained through institutional, academic and industrial research efforts, have allowed new species to be produced, using high performance feeds, in innovative farming facilities. The farming of existing species has also been revolutionised through advancements in, amongst other inputs, diet, veterinary treatments, stock selection, farming technologies and the consequent improvements in husbandry. This led to 7-fold production growth in 40 years. On the other hand, European aquaculture has always faced competition from fisheries and imports to establish its place in the market. Strategically, aquaculture has been linked traditionally to fisheries, within the scope of the Common Fisheries Policy and related instruments, mainly because its markets are similar to those for the wild products. Aquaculture is also seen as an integral component of Europe bioeconomy. The aquaculture in future has taken the following guiding principles for the role of European aquaculture:  Providing the European consumer with desirable products of the highest quality and at an affordable price.  Respecting the conditions of optimal livestock health and welfare,  Developing and integrating new technologies within the entire value chain,  Improving economic performance at each level of the value chain,  Guaranteeing the training and skill development of those working in the sector,  Providing clear contributions and benefits to society, European aquaculture needs dynamic European research and innovation that links to a responsible and competitive aquaculture value-chain, which is fully accountable to society. Successful innovation will also require extensive public/private cooperation, creating an innovation friendly environment for the sustainable development of the sector. Achieving the goals of European 286

Aquaculture requires moving from ideas and concepts to realisation. These need the generation of new knowledge that leads to innovation and competitiveness, supported by resource efficient activities.

Vision of aquaculture in future Aquaculture in the EU developed well in the last two decades, and this was partly allowed by the many Community initiatives that have been taken to support this sector. The Union has a vast legal armoury on aquaculture, and activities to enhance the legal framework are progressing. However, there is still room for further improvement, and the recent slowdown of growth must be addressed. While the overall framework shows a positive potential for further development, aquaculture in the EU has still to cope with some problems, in particular in the context of health protection requirements, environmental impact, and market instability. In the next ten years aquaculture must reach the status of a stable industry which guarantees long term secure employment and development in rural and coastal areas, providing alternatives to the fishing industry, both in terms of products and employment. To secure employment and well-being, European aquaculture must be an economically viable and self-sufficient industry. The market has to be the driving force of aquaculture development; production and demand are finely balanced and any increase in production in excess of the likely evolution in demand should not be encouraged. The range of products must be enlarged, better marketing strategies have to be implemented. Private investors are, and have to remain, the leading force to put progress in practice, while a key role of the public powers will be to guarantee that the economic viability be paralel to the respect of the environment and the good quality of the products. The fundamental issue is therefore the maintenance of competitiveness, productivity and durability of the aquaculture sector. Further development of the industry must take an approach where farming technologies, socio-economics, natural resources use and governance are all integrated so that sustainability can be achieved. The strategic goals of research and innovation agenda for aquaculture in future will be: ď&#x201A;ˇ Maximise the health benefits of aquaculture products, ď&#x201A;ˇ Ensure the continuing safety of aquaculture products, 287

 Deliver high quality European aquaculture products - fully meeting consumer expectations including appearance, taste, texture, nutrition and provenance claims,  Understand the dynamics of European seafood markets.

Important problems in aquaculture sector The aquaculture production faces to many problems. These include:  Poor governance,  Weak fisheries management regimes,  Over the use of natural resources,  The persistent use of poor fishery and aquaculture practices,  Small-scale fish farms and fishing communities,  Injustices relating to gender discrimination and child labour,  Infected wild breeders,  Ddisplaced wild populations in areas where intensive farming has been implemented,  Increases in demand of aqua feed, fishmeal and fish oil,  Uncontrolled aquaculture productions,  Diseases transmissions due to escapes of infected specimens and vice‐versa when infected wild breeders are incorporated to farming activities,  Environmental impacts and the use of coastal areas,  Residue problems in aquatic foods affects human health,  Biodiversity and preserving cultural landscapes,  Sustainability in aquaculture.

The challenges and aquaculture in Europe



1. Challanges The Council of the European Union observed that the EU strategy for sustainable aquaculture led to significant progress in ensuring the environmental sustainability, safety and quality of EU aquaculture production but the need exists to ensure a sustainable and more competitive European aquaculture sector that meets consumer demands. Europe, in common with the rest of the world, must respond to major environmental, economic and social challenges to assure that 288

future generations can enjoy a safe, prosperous and healthy life. To achieve this: Sustainable management of natural resources: Ensuring responsible stewardship of the aquatic resource, feed components particularly ingredients gained through forage fisheries and the wider environmental impacts on the ecosystem, habitats and biodiversity. Sustainable production: Assuring the sustainability of the entire aquaculture value chain by optimising the role of aquaculture with regard to food security and the global food system, maximising efficiency within the supply chain, improving animal husbandry, achieving optimal conditions for fish health and welfare, increasing productivity, minimising human environmental foot print and avoiding unnecessary waste, satisfying market led demand to deliver long term profitability and ensuring investment in new technologies, research and innovation. Improving public health: Ensuring the safety and quality of feeds and the final product, accompanied by transparent traceability measures, quaranteeing that production takes place in a clean and safe environment, increasing consumption and promoting the benefits of aquaculture products across Europe and integrating the positive health benefits of consumption into public health and education policies. Mitigating climate change: Climate change will have significant effects on European aquaculture through changes to water temperature, ocean currents, weather patterns, frequency of extreme weather; this imposes the need to facilitate new working conditions, and production environments. Integrating and balancing social developments: Fulfilling the potential in further developing an industry based already within rural and coastal economies/communities, providing dynamic and flexible career opportunities, addressing skills and knowledge gaps within a fast developing industry, addressing the very wide disparity within the aquaculture industry across different regions and cultures within the EU and improving communication of the benefits and risks of aquaculture to ensure our place in society.


Global sustainable development: Optimising EU position closely within the global food system. European aquaculture will assist in further increasing the percentage of fish and shellfish that is farmed for human consumption, both through cultivation in Europe and also by the export of technology and skills, knowledge and expertise. Many of the challenges described affect the developing world more than Europe and aquaculture should aim to contribute to global sustainable development.

2. Oppurtunities The market: There is a growing market demand for European products. Europe has a well developed and integrated aquaculture value chain. There is an increasingly sophisticated and demanding market, both within the EU and increasingly in third countries. Product quality and safety: There is wide-ranging recognised health benefits of fish and shellfish. The quality and safety of products of European aquaculture is assured by strong legislation and responsible value chain, demonstrating full traceability. Reseach potential: Europe has a historic advantage in pioneering aquaculture research and development. The research infrastructure provides top class facilities for both basic and applied research tasks. Social : There is a highly educated workforce with multi disciplinary skills in Europe. It provides long term economic contributions and employment in coastal and rural areas. These opportunities provide a strong base for driving the sustainable growth of the sector.

Fish projections of OECD and FAO for 2012â&#x20AC;&#x201C;2021 1. Growth in fisheries and aquaculture sector Stimulated by higher demand for fish, world fisheries and aquaculture production is projected to reach about 172 million tonnes in 2021, a growth of 15%. The increase should be mainly driven by aquaculture, which is projected to reach about 79 million tonnes, rising 290

by 33% over the period 2012–2021 compared with the 3% growth of capture fisheries.

2. Slowing in aquaculture growth However, a slowing in aquaculture growth is anticipated, from an average annual rate of 5.8% in the last decade to 2.4% during the period under review. This decline will be mainly caused by water constraints, limited availability of optimal production locations and the rising costs of fishmeal, fish oil and other feeds. Notwithstanding the slower growth rate, aquaculture will remain one of the fastest growing animal food-producing sectors. Products derived from aquaculture will contribute to an increasing share of global fishery production, growing to 46% in 2021. Aquaculture production is expected to continue to expand on all continents, with variations across countries and regions in terms of the product range of species and product forms. Asian countries will continue to dominate world aquaculture production, with a share of 89% in 2021, with China alone representing 6% of total production.

3. Fishmeal use The portion of capture fisheries used to produce fishmeal will be about 17% by 2021, declining by 6% owing to the growing demand for fish for human consumption. In 2021, fishmeal production should be 15% higher, but almost 87% of the increase will derive from improved use of fish waste, cuttings and trimmings. Fishmeal produced from fish waste should represent 43% of world fishmeal production in 2021.

Bremerhaven declarations on the future of aquaculture In Aquaculture Forum held in Bremerhaven on March 26-27,2012 and on February 18 – 19, 2013 to make recommendations and justifications on the future of Global Open Ocean Aquaculture and Fish Nutrition and Aquaculture Technology declarated recommendations on subject areas and justifications ( Important recommendations for the future of aquaculture are: 

The aquaculture industry should be seen as an equal right resource user that also needs protection from the externalities of other aquatic and land-based resource users and industries 291

competing for the same resources. In this context there is also an urgent need to simplify regulatory frameworks for aquaculture systems, which are presently highly regulated in many countries within the EU. This can be done without compromising environmental objectives and targets while removing unnecessary bureaucratic barriers that distort the competitiveness of European aquaculture. There is an urgent need to invest in research and development of alternatives for fish-meal and fish oil resources, incorporated with appropriate quality control measures to maintain the quality level of the final products. Specific research being undertaken when exploring alternatives for fish meal and fish oils in feeds. There is an urgent need to plan for the comprehensive development of land- and water-based infrastructures needed for the technical and logistical support and supply of Open Ocean Aquaculture that incorporates the multi-dimensional interacting factors for successful operations. There is an urgent need for more predictable and cost-effective production of high-quality larvae, fry and fingerlings for stocking aquaculture grow-out facilities. Hatchery rearing strategies are urgently needed for endangered species to produce progeny with the fitness for survival in a highly competitive and harsh outside environment. Such methods and strategies must be designed to avoid outbreeding depression (maintaining the natural genetic integrity of the species of concern).su The potential to apply modern approaches in recirculating aquaculture systems (RAS) should be greatly enhanced with due consideration of the economy of the scale. RAS design must take species-specific requirements into considerations, the design and layout of which must serve the specifically targeted products while increasingly employing process control technology.b There is a need to develop technology standards for RAS and its operational components (including materials) while also improving our knowledge base to more accurately predict production capacity (including safety margins) as well as appropriate risk assessment methodologies (including sound contingency planning). There is an urgent need to improve education on principles and on operational practices for all modern aquaculture systems (in


particular for RAS) at a multi-disciplinary, trans-disciplinary, and a fairly standardized level including appropriate certification. Land-based integrated agriculture-aquaculture systems need to be assessed and tested in light of modern biotechnological, socio-economic, and environmental criteria to define practical combinations of various species suited for local markets. The development of integrated farming systems that employ a mix of species of various trophic levels, thereby enhancing environmental compatibility of aquaculture, should be promoted in suitable coastal areas. New and extended criteria for area licences are needed to accommodate various system components to better utilize natural resources and to protect the environment. As new Integrated Multi-Trophic Aquaculture (IMTA) systems are designed, there is an urgent need to develop carrying capacity models based on mass balance models for such systems while also the ecology of diseases in these simple ecosystems must be fully investigated to avoid unforeseen impacts of disease outbreaks that limit the development of this technology and jeopardize economic benefits. If protein and lipid sources from IMTA systems are to be used in aquaculture production a framework must be developed to ensure that these products are free of aquatic pathogens with a view to avoiding biomagnification of pathogens within the food chain. It is strongly recommended to support research and development projects on the potential of greenhouse crop production with aquaculture production (e.g. hydroponics / aeroponics) to elucidate mass flows between the compartments of such systems as well as to enhance bio-economic resource use, particularly when contributing to rural economy.

The future for aquaculture: What will the sector look like in 20 years? By 2030, European aquaculture will have achieved the following position:  Produce more from less,  Minimise waste and be waste neutral,  Be as close to carbon neutral as possible, 293

 Adapt to the implications of climate change,  Be an integral part of the food supply chain, contributing to health, nutrition and lifestyle,  Cater for both mass and niche markets, with products tailored for demand,  Possess a developed understanding of the implications of aquaculture processes and influencing factors,  Assuring knowledge transfer to consumers,  Established and understood in the consciousness of society at large,  Play a high role in the international food system,  Skill development and lifelong learning,  Adoption of new technology and operating conditions,  Effective and resourceful scientific and professional Networks,  Efficient technology transfer and innovation mechanisms,  National and European strategic and policy priorities,  Interrelated research agendas and funding precedence, The visions and key goals of the thematic areas: The 8 thematic areas in aquaculture now and in future will be: 1. Product quality, consumer safety and health: Public awareness of a healthy diet and a more sophisticated understanding of nutritional science will continue to increase. 2. Technology and systems: As aquaculture moves from being a new industry to an evolving industry, it is crucial that technology and systems are used to maximum advantage to fully exploit the potential of the European aquaculture industry. Contributions to automation, monitoring and analysis are key to increasing operational efficiency. 3. Managing the biological lifecycle: European aquaculture in 2030 will produce larger volumes and contribute to a decrease of imports through a significant improvement of its competitiveness. It will also focus on being a commercial stakeholder in aquaculture worldwide. 4. Sustainable feed production: It is noted that globally the role of aquaculture as contributor to socio‐economic development, food supply and food security is constantly increasing and is predicted to increase further. Meeting the future demand for food from aquaculture will largely depend on the availability of quality feeds in the requisite quantities.


5. Integration with the environment: Aquaculture in 2030 will produce nutritious food with less environmental footprints than any other type of food production for humans, and this production will, to a greater extent, be based on feed resources taken from outside the human food chain. When addressing the interaction between food production and the environment it is necessary to take a holistic approach. 6. Knowledge management: Economic and socially sustainable activity will be more important. Knowledge and innovation will be competitive advantages for the European aquaculture industry. The aquaculture sector will be attractive to a wide range of highly educated people, with positive growth and employment opportunities. 7. Aquatic animal health and welfare: By 2030, further improvement in aquatic animal health and welfare in European aquaculture will produce high quality, robust animals resulting in increased productivity that builds on environmental and welfare standards. The extremely high standards of fish health and welfare observed in European aquaculture are a credit to the different production sectors and indicative of the investment made in fish health and welfare research and sectoral education. 8. Socioeconomics & management: European aquaculture operates within a commercial globally influenced market. As world economic trends move from state intervention, subsidies and centralised planning towards deregulated free trade, it is vital that aquaculture is not disadvantaged through legislation, regulation or arbitrary intervention and interference.

References Anonymous, 2002. A Strategy for the Sustainable Development of European Aquaculture COM (2002) 511 final. Anoyymous. Committee on Fisheries, European Parliament DT\ 796008EN.doc Anonymous, 2009. Building a sustainable future for aquaculture: A new impetus for the Strategy for the Sustainable Development of European Aquaculture. Commission of The European Communities, Brussels, 8.4.2009 COM(2009) 162 final. Anonymous, 2009. Council of the European Union; 2nd June 2009 Anonymous, 2010. Europe 2020 COM(2010) 2020. Anonymous, 2010. FAO Fisheries and Aquaculture statistics (2010) Anonymous, 2011.The future of European aquaculture. The Vision and Strategic Research &Innovation Agenda of the European Aquaculture Technology and Innovation Platform.


Anonymous, 2012. The Future of European Aquaculture: The Strategic Research and Innovation Agenda. The Future of European Aquaculture EATiP 2012 ( Anonymous, 2012. Bremerhaven Declarations on future of global openocean aquaculture. Part II, Workshop 1, March 26-27, 2012, Bremerhaven, ( Anonymous, 2013. Bremerhaven Declarations on future of fish nutrition and aquaculture technology. Part II, Workshop 3, February 18-19,2013, Bremerhaven, ( Anonymous, 2013. The Economic Performance of the EU Aquaculture Sector –2012 exercise (STECF-13-03). ( Buttner, J.K., 2011. What is Aquaculture and Why is it important? Flotsam&Jetsam, Aquaculture, Winter 2011,, 39(3): 1-8. Committee on Fisheries, European Parliament DT\ 796008EN.doc Council of the European Union 10917/06 Green, K.,2012. OECD–FAO Agricultural Outlook: Chapter on Fish Projections 2012– 2021( esustainablefoodsystemwillimproveglobalfoodsecurity oecdandfaopublishnewagriculturaloutlook.htm)‐platforms/about_en.html


XV. Best Practice Models in Partners’ Countries 1. Best practice in fish farm “Durmaz Alabalık” in TURKEY Authors: Prof. Dr. Ergün Demir, Prof. Dr. Kemal Çelik, Mesut Yıldız Turkey has a 8 333 km coastal line and 177 714 km rivers. Marine and inland waters suitable for fisheries and aquaculture cover approximately 25 million hectares. Aquaculture has been increasing very rapidly, representing now for 25% of the total Turkish fishery production. Turkey has one of the fastest growing aquaculture sector in the world and aquaculture is playing an increasingly important role in the Turkey economy. Fishery products are the only products of animal origin that can be exported to the EU. However, Turkey also exports milk and chicken meat to the EU In Turkey, the aquaculture sector has started with carp and trout farming in the 1970s and developed with gilthead sea bream and sea bass farming in the Aegean and Mediterranean seas, followed by cage culture of trout in the Black Sea and recently tuna rearing in the Aegean Sea and the Mediterranean Sea. “The Durmaz Trout Company” was established in 1992 in İvrindi, Balikesir. It was served as seasonally at beginning. Hüseyin Durmaz, who is boss of the Company planned to improve the Company. He first redocorated the restaurant and rebuilt the trout ponds. He planted many kinds of trees and grasses on the farm. He din’t prefer to use much concrete on the restaurant area. He used wooden materials for tables, chairs and sofas. He also built a kindergarden for kids. He thought the kids would like birds so he built small houses for poultry, such as ducks, chickens, quails and dogs. The company discovered a few good quality cold water sources in other places near the main farm to grow best quality trouts. It also started to grow vegetables and fruits in their gardens as organic fort he restaurant.


The Durmaz Trout Company is a family company. His family and also more than 10 staff work in the trout farming, at the restaurant and marketing. The restaurant of the trout farm is very famous in Balikesir and also the travellers from İstanbul to AyvalĹk and Akçay visit the farm and taste different meals containing trout that cooked with different methods. It also serve salads, drinks and a very tasty baked dessert made from sesame. In spring and summer seasons, the company organise the wedding ceremonies in the restaurant. The kindergarden, tramplens and nature are ready for kids. They can also fed the chickens, ducks, quails and fishes. The aim of the company to supply a clean nature, fresh air and good quality natural foods to the people. The Company has a website ( You can also watch them on youtube (


References Deniz, H., 2010. Turkey: Best practices in aquaculture management and sustainable development. Advancing the Aquaculture Agenda, Workshop Proceedings, OECD- 2010.


2. Best practice in fish farm “Ostróda” POLAND


Author: Maciej Dymacz Restocking resort in Warlity Wielkie was built in 1980 and until 1994 it belonged to the State Farm Fisheries Olsztyn. In 1994, as a result of the allocation and lease founded a company called Fish Farm Ostróda. The leased property includes 6,000 ha of lakes and pond stocking center with an area of 90 hectares and hatchery fish , which gives us the ability to produce stocking material for greater larger scale . The main task is the production of stocking material of different species of fish, carp are the dominant species whose annual production is in the range of 100 tons fry of the fall in the range of 50 250g piece .Other species is produced whitefish , pike, perch, catfish As we leased our lakes are in 60% of the lakes type whitefish have laid emphasis on the development of the genre. By increasing the stocking fry and fry the summer whitefish felt the effects obtained in the form of increased catches of this species. Whitefish population growth is based on developing its lair in the lake Szeląg Wielki, in which whitefish catches represent 70% of the trapping of this species in the farm. Average annual catches of whitefish in the lake are 7 tons record yield is 12 tons. This lake is stocked every year for decades only summer whitefish fry which is breeded earlier in joints. Size caught whitefish varies between 10-12 units per kilogram . By stocking lakes walleye fry years have brought an increase in population of this species in lakes where environmental conditions generally deteriorated , but conducive to such species as walleye . Intensive and systematic restocking zander resulted in an increase in its yield. Apart from whitefish and walleye pike is a species which quickly pays elevated curbing the stocking . In a string of 3-4 years of successful restocking of increasing catches of this species . With this in mind we conduct intensive stocking of pike lakes to increase its economic catchers attractive fishery for anglers and cause a reset pike fish species very valuable for which there is no market and the way depleting the lakes of surplus biomass. The value of the current restocking with us often exceeds 30% of the harvested fish . Our preferred species are carp, whitefish , pike , walleye , catfish . For the production of the above-mentioned species of fish use our hatchery and ponds in Warlity Wielkie . As one of the few fishing water users in this part of the country have mastered the 300

method of artificial spawning and egg incubation pike ( 80-95 % hatching from eggs acquired ) . This allows us to stocking lakes pike in large volumes of lakes, especially where there is an excess of small roach, bream and white bream small . Through intensive stocking pike catches have increased its economic and largely fishing Evidence that the lakes are more and more pike anglers are organized numerous nationwide competitions Spinning and buying licenses for anglers to fish long distance Spinning . In cooperation with local organizations selected several lakes for fishing in the area Ostr贸da that particular stocking for angling. These lakes stocking tench, pike, zander and perch .


3. Best practice in fish farm “Szegedfish LTD” in HUNGARY Author: Janos Palotas The Szegedfish Ltd. is located to the Northeast from the city Szeged. Its total area is 2100 hectares. Different kind of fishes are bred here such as: carp, white bighead carp, grass carp, pike and catfish. The main result of the staff’s research is the mirror carp of Szeged what is officially registered and accepted as a landrace animal. The mirror carp is a low-fat fish with excellent taste, easily adapts to the local environment and genetically resistant. The company produces fishes for breeding, sporting and eating purposes at the same time. Their annual fish production is about 1800 tons. Approximately 30-40% of the produced fish is marketed in the EU countries and the remaining quantity is sold inland for angler associations, restorants and associated holdings. The main inland market of the company is the South Plain region. According to the definition of the national standard „A pond farm is a farm unit consisting of artificial ponds where the fish breeding is planned and intensive. In a pond farm, the technological conditions of water management should be provided.” The „sodium carbonated” fishponds were created especially in regions with plain fields between the years of 1932-1982. These ponds are surrounded by embankments, so their water management can be controlled. The ponds belong to the „warm water” type ones (their 0 temperature is above 20 C in summer). The company produces the table fish as a final product in a three-year time period. In order to reach a higher fish production, the evaporated water loss is being compensated by some water from the river Tisza. Different sizes of fish screens are used when filling up the ponds. 8-9 3 million m water is classified as ecological water out of the annually 3 used 10-15 million m . The optimal oxygen content of the water that provides living space for the fishes is 5 mg/l in summer and 3-4 mg/l in winter. (Mass fish decay occurs if the oxygen content of the water is decreased to 0.7 mg/l in summer or 0.5 mg/l in winter.) 2.0-2.4 tons/hectare livestock manure (60 % cow manure and 40 % pig manure) is used per year to improve the natural nutrient supply of the ponds. The pond fertilization is finished till the end of July in every year. After having harvested all the fish from the ponds in autumn, the beds are kept dry and bleach-powder is spread if needed, so they become suitable for permanent use. The dry beds of the ponds are 302

loosen up with a disk-harrow. The shore is examined and restored if required at this time. The control of the pond-side plants is mechanized, but grass carps are also introduced for this reason. Carp rearing is performed by artificial fertilization after having selected the parents with good characteristics. Female fish are treated with hormone then their eggs are collected. After it, the male semen is added to the eggs. During the process the mixture should be stirred continuously. In order not to become adherent, some fertilizing solution is added to the roes. Roes are taken to special pre-raising ponds for one month. In order to get 2.5 – 2.8 million spawns in the ponds until autumn, 40–50 million roes should be collected from female fish in the hatchery. Herbivorous fishes (white bighead carp, grass carp) and catfish are also bred artificially. Only those healthy fishes can be transfered to the ponds rich in oxygen, which are equal in age. Plastic containers are used when selecting and weighing the fishes in order not to injure them. Carps and herbivorous fishes are usually introduced together. The ratio between them should be 10:1. After the introduction, the health and development of the stock of the ponds is being controlled continuously by using casting nets. Only good quality forage or nutriment should be used for feeding 0 purposes. The feeding starts when the water temperature is at +10 C. The feed brought into the water is usually consumend within 5 – 6 hours time by fishes. Fishes are being fed until the end of June – July, then the quantity of their feed is determined based on the control fishing performed twice a month at least. The individual treatment of the fish stock is impossible, so the solution for this is prevention. If required, the medicine should be mixed into the fish feed or added into the water of the pond. The most problematic fish diseases are the white spot disease (Ichthyophthiriosis), the Asian tapeworm (Bothriocephalosis) and the swim bladder inflammation. Interventions always cause stress to fishes that can be harmful for their health, so the continuous control or – in some cases – laboratory tests (for example: virus indication) are inevitable. The veterinary specialist of the company performs constant controling of the farm and introduces some medical treatment if necessary. Only the small ponds are fished in summer, if the water quantity is appropriate. Special attention is required for this process. After having estimated the fish crop, the harvest starts with the drainage of the ponds using the necessary tools. Driftnets are used for manual 303

harvest, while moving fish screens and mammoth pumps for the mechanical harvest. The basic principle is that fishes should be transferred without any injury as soon as possible. The examination of the pond, the drainage of the remaining water, removal of rough fishes and making perfect order are the last steps of the harvest. The wintering of the crowded harvested fishes can only be provided by continuous water supply (0.5 l water rich in oxygen is required for 1 ton of fish stock per secundum). The snow is cleared away quickly from the surface of the ponds. After the upper layer of the water of the fishpond has been congealed, a leak with a size of 8m*3m is cut in the ice per every 3 hectares. Mechanical leak drilling should be performed when the thickness of the ice reaches the 25 cm. The four corner of the leak are always marked that is visible enough from a distance. The winter season is good for repairing or exchanging of the deteriorated tools.

References Horváth L. – Pékh Gy. (1984): Haltenyésztés. Mezőgazdasági Kiadó. Budapest. p. 5-171. Horváth L. (2000): Halbiológia és haltenyésztés. Mezőgazda Kiadó. Budapest. p. 344-432. Szegedfish Kft. (1998): Halastavak üzemeltetése, a haltermelés. Szeged. p. 1-22.;jsessionid= 226F4F57237AEE6B6310080416E95449 _ PracticesAquaculture_Practices


4. Best practice in the “Eels’ Project” of Cesenatico, ITALY Author: Luciana Levi Bettin

The experts of the degree course in Aquaculture and Hygiene of fish production of Cesenatico, which is headed by the School of Agriculture and Veterinary Medicine of the University of Bologna, have conducted a research that have received a broad interest even at the international level. The research started in 2010, when the number of living specimens of eels in the world was dramatically decreased. The IUCN, the international Institute for nature’s conservation, inscribed European eel in the “red list”: just a little step before extinction. “Between the juveniles - explains Doctor Oliviero Mordenti – the reduction was at 99%”. The same eternal and mysterious eels’ habits was putting them to a deadly risk. This snake-like fishes spend their lives in fresh or brackish water, like for example the ones in the Valleys of Comacchio. When it reaches sexual maturity, it embarks on a journey of 11000 Km towards the Sargasso Sea, where it lays its eggs, fertilizes them and then dies. The newborns undertake the return journey, it takes 3 years, and they end their trip exactly where their parents started; this happens if overfishing and pollution does not stop them before. Just a step from extinction, several research centers have started studying how to avoid it. The European Union had already raised the alarm, financing management plans implemented in Italy by the Ministry of Agriculture and by the Emilia Romagna region. In Cesenatico the team headed by Mordenti has managed to reproduce the eel in captivity, firstly studying the most comfortable environment for the animal. "In 2010 - explains Dr. Michaela Mandelli were first analyzed the parameters of light and dark, identifying the most favorable alternation in order to increase eel’s weight and fertility." The following year, the research had focused on fertilization, comparing two populations: the one of the valleys of Comacchio and the one of the Marano-Grado lagoon.


In 2011 the experts have been able to ensure that, with repeated hormonal induction, eels would lay down their eggs in the captivityâ&#x20AC;&#x2122;s tanks, and that fecundation would take place in the same tanks. Results far more positive, even in percentage terms, of those obtained from similar research teams in different countries around the world. When the larvae born an even more difficult problem arose: how to feed them? Professor Albamaria Parmeggiani has developed a secret recipe that resulted very popular within newborns. So, just before summer, there were the first weaning's successful tests. The results obtained in Cesenatico will change the face of eel's breeding in Europe, where, according to the FEAP (the European association of Aquaculture Producers), over the past 10 years the production of European eel decreased for nearly 40%.

References Bellocchi, L.,2013. The Eelsâ&#x20AC;&#x2122; Project of Cesenatico., 16/10/2013


5. Best practice at the “Laxeyri Fishfarm” in ICELAND Author: Sigurður Már Einarsson

The first experiments in fish farming in Iceland began at the end of the nineteenth century when the first attempts were made to fertilize and hatch salmonid ova and to release the emerging fry for enhancement in Icelandic salmon rivers. Aquaculture in Iceland involved mainly hatching of salmonids and restocking of rivers until 1950. In the 1960s a small scale rearing of salmonids to a size ready for consumption began with the introduction of rainbow trout farming. During the period 1985-90 many salmonid farms were built to produce salmon smolt for use in ocean ranching ventures and cage rearing of salmon both in Iceland and Norway. In the nineties, Icelandic scientist and farmers worked on developing aquaculture of species such as Atlantic halibut, turbot, abalone and Atlantic cod. From 2000 onwards, the main increase has occurred in the production of Atlantic salmon and Arctic char.

Figure 1. The Laxeyri fish farm. The Laxeyri fishfarm was built in 1983 in the upper reaches of the Hvítá in Borgarfjörður river (Fig. 1). Abundance and quality of water are the fundamental factors for land-based farms such as Laxeyri which have to be located close to a reliable water source providing a stable flow of water, suitable for farming all year round, in sufficient quantity to sustain a viable farm. Natural disease free spring water with stable temperatures from 3,5 – 4,0°C from a nearby lava field is used as a water source and with the addition of geothermal water, it is 307

possible to control the temperatures for the maximum benefit of the farming practice.

Figure 2. Angling for salmon in Grimsa, Iceland. The main product of the Laxeyri fishfarm are salmon smolts produced at Laxeyri and the nearby farm at Húsafell and the production is mainly used for releases into nonproductive rivers such as the West Ranga to create angling opportunites, where none existed before. Angling tourism in Icelandic rivers (Fig. 2) is a very valuable resource creating income and job opportunites in the rural areas of Iceland.

References Ísaksson, Á., and S. Óskarsson. 2002. Icelandic salmon ranching: problems and policy issues—a historical perspective. ICES Annual Science Conference, Copenhagen, Denmark.


6. Best practice at JSC “Išlaužo žuvis” in LITHUANIA Author: Judita Kasperiuniene

Lithuania, as well as other parts of the central and eastern European countries has a long tradition of pond aquaculture. Declining natural water fishery resources has enabled the aquaculture to become meaningful for economy. However, due to the changing economic conditions, cyprinid farms hardly weathered the pressure of Norwegian salmon, pangasius from Indochina or intruded African catfish.

A medium - sized (500 ha) in 1965 established pond farm JSC “Išlaužo žuvis” has faced the challenges. There in Lithuania are 20 ponds farms with a total area of over 10,000 ha, growing about 3.5 thousand tons of fish, mostly carp. “Išlaužo žuvis” in 2003 stood on the verge of bankruptcy, and then only 5 tons of carp was harvested. The farm is one of the leading in Lithuania, and annually harvests and sells more than 500 tons of ponds fish now. Carp pond is reared semiintensively in policulture with grass carp, bighead carp, crucian carp, tench, European catfish, pike, perch, peled. Balanced policulture gives a maximum advantage to use all ecological niches and facilitated the growth conditions. This is the best alternative to replenish fish stocks and allow the recovery of endangered rare natural water fish. Water quality indicators, water self-purification potential is much better than the polluted river lowlands, the Curonian Lagoon and the Baltic Sea.


Carp in our ponds policulture account for over 75 % of farmed fish. The ponds are fertilized with high quality organic fertilizer, we manage to achieve that one-third of the carp feed is zoobenthos and zooplankton, and two -thirds - in addition given different types of grains, coming from small extensive farms. We carefully check purchased grain quality. In this way we can achieve that naturally feeded fish meet the highest quality and taste requirements. This criterion cannot be guaranteed in recirculating aquaculture system (RAS). Farmed fish could be alternative option burgeoning fast, fake food cult. There in Lithuania is quite good both natural conditions and installed hydro facilities, state of the technology that we refuse to grow fish in more natural way. Both fish farmers and customers have the right to choose which way to turn. JSC „Išlaužo žuvis” revived recreational fishing for the whole family, in order make people try to go back to 25 years ago would love to fish ponds, re-discover taste of carp. We have proposed and sold as many as 18 fish species for stocking of private and public water bodies in recent years. We opened a branded fish store that constantly busy housewives do not bother working on live fish, and made sure to give her dressed.


Shop sells live fish in aquariums, gutted and chilled fish and fillet on ice, smoked fish and culinary products, processes in farm processing plant. Our advantage is that we can supply the day or fresh caught fish and made products. We avoid use of product stabilizers and flavor and smell enhancers in food production. We strive to produce the most natural food, take the best of local food traditions, and not afraid to look around and adjust the edges and other technologies.

It seems the set goal gives expected results. Previously has been difficult to sell the harvested ponds fish, now we see real opportunities to grow fish in ponds twice as intensive. We have experienced that in 311

the legal competition we can successfully compete with the urged fish from URS. We withstood competition with legal and frozen marine fish, which is common in Lithuania. However, here we see a glimmer. Challenging, but we are moving forward in promoting a clean and healthy pond production in various Lithuanian and international exhibitions.

References Darius Svirskis, director of JSC “Išlaužo žuvis


Handbook on European Fish Farming  

Ergün Demir et al.: Handbook on European Fish Farming. Balıkesir, 2014, Balıkesir University.