seeks to reduce the number of fish that escape from European aquaculture through research to improve fish farming techniques and technologies.
PREVENT ESCAPE is financially supported by the Commission of the European Communities, under the 7th Research Framework Program.
7. Recommendations and guidelines of fish farms, management and
for the design operation of
equipment Cite this article as: Fredheim A (2013) Recommendations and guidelines for the design of fish farms, management and operation of equipment. In: PREVENT ESCAPE Project Compendium. Chapter 7. Commission of the European Communities, 7th Research Framework Program. www. preventescape.eu ISBN: 978-82-14-05565-8
authors: Arne Fredheim1, Ă˜sten Jensen1 and Tim Dempster1 1
SINTEF Fisheries & Aquaculture, Norway
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The Prevent Escape project has estimated that more than 9 million fish have escaped from European fish farms between 2007 and 2009, with a range of ecological and genetic consequences possible. In addition, the direct cost, at the point of first-sale, was estimated to be as high as â‚Ź47.5 million per year in Europe. The environmental and economic costs of escape provide clear justification for a greater focus on development and implementation of methods to prevent escapes in European countries where fish farming is a significant industry in coastal waters. Here, we present the case for technical standards and other measures to prevent escapes, summarise the technologies currently used by the sea-cage farming industry, and outline a range of implementable measures that can be taken by various stakeholders to better prevent escapes.
The
need for technical standards for sea-cage fish farms and
current status across
Europe
Once implemented, technical standards for the design, management and operation of fish farms are a demonstrated, powerful, industry-wide tool to prevent escapes (Jensen et al. 2010). Technical standards used to regulate industry performance should be subject to frequent updates and improvements. The technical standards also need to keep pace with changes in technology, the types of physical environments in which farms are located and
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practical aspects related to use of equipment of ever-increasing size. For technical standards to be applied and enforced consistently across the industry, legislative support is required. For example, a recent spate of escapes in Scotland has led to calls for a technological overhaul of the industry; to support such an overhaul, legislation will be required to ensure the standards. Technical standards, codes of practice, legislation and legislative support, and the reporting of escapes vary between countries across Europe. Norway is the only European country with legislation (NYTEK), certification bodies (accredited by Norwegian Accreditation) and a technical standard (NS9415.E:2009) specifying the requirements for fish farms in terms of their component technologies, design and engineering. The introduction of the NS9415 technical standard is believed to have significantly reduced the volume of escapes to the current level; ~0.1-0.3% of the approximately half a billion salmon held in sea-cages in Norway each year (Jensen et al. 2010). Although other countries have voluntary codes of conduct and best practice guides for marine fish farm management, mooring procedures and the manufacture of net cages in situ (Table 7.1), these fall short of the regulatory power of technical standards backed by legislation. A movement towards development of technical standards in other major aquaculture producing countries appears to be gaining momentum. For example, in Scotland, a proposal for a technical standard (SARF073 2012) is in progress. Furthermore, an international technical standard is under development (ISO 2012), and the various results from the Prevent Escape project have proved valuable input.
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Country/ region
Norway
Existing industry codes
• NS 9415
• Code of conduct
Scotland
Ireland
Canada
• The Code of practice for the prevention of stock escapes of Irish farmed salmonids
Legislation and certification System.
The Aquaculture & Fisheries (Scotland) Act 2007 came into force in August 2007 and makes relevant legal powers and provisions in relation to fish farms for containment and fish farm escapes. The Code of Conduct is mandatory for all members of the Scottish Salmon Producers Organisation (SSPO).
Industry voluntary
• Code of containment for the culture of salmonids in Newfoundland and Labrador Industry voluntary • Code of containment for culture of Atlantic salmon in marine net pens in New Brunswick
• FEAP Code of Conduct http://www. aquamedia.info/ consensus/
Voluntary
International
• NASCO Guidelines on Containment of Farm Salmon; CNL(01)53 (http://www.nasco.int/pdf/ ag reements/williamsburg.pdf)
Industry voluntary
International
• ISO Standard (ISO)
Industry voluntary
Europe
Chile
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• Draft technical standard published (SARF0732012)
Level of enforcement
None
Reporting of escapes
Required to report all incidents, number of escaped fish, how handled and what happened.
Other escape reducing actions/efforts
Comments
Directorate of fisheries do inspections and follow-up on escape incidents. Official Escape Commission with experts who surveyed escape incidents existed from 20062011.
Legislation concerning the reporting of fish farm escapes has been in place since 2002 and requires that Marine Scotland must be notified of an escape or suspected escape immediately by phone and in writing by completing an Initial Notification Form.
Marine Scotland established ‘The Improved Containment Working Group’ in 2009 to make proposals and a strategic Framework for Scottish Aquaculture to reduce escapement.
A Final Notification Form is required within 28 days of the Initial Form. Escapes must be reported to the Department of Communications, Marine and Natural Resources (DCMNR). An escape incident must be reported by phone within 24 hours, and in writing within 1 week. Atlantic Salmon Watch (Fisheries and Oceans Canada) must be informed. Farmers will, in the event of escapes, take immediate action, co-operate and inform the respective authorities to ensure that the appropriate actions are taken.
Focus on management. Technical requirements for net cage design and manufacturing.
Farmers will seek to minimize the potential risks that are presented by farmed fish escapes to wild fisheries.
No mention of standards for technical equipment or counting of escaped fish.
Under development based on the Norwegian standard NS 9415 and the Scottish draft technical standard Initial work started to develop a technical standard for fish farming equipment.
Table 7.1 Status of reporting requirements, legislation, technical standards and codes of practice/ conduct in major finfish producing countries.
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Technical
equipment
Most floating fin-fish farms are based on the same general principles and component technologies; a floating collar, a net cage and a mooring system (Fredheim & Langan 2009). The floating collar acts as an attachment point for the net cage, helps maintain its shape, distributes forces to the mooring system, and provides a working platform for daily operations. The floating collar is the main structural component of a floating fish farm, integrating the other parts. The two most common set-ups are circular plastic fish farms, made of high density polyethylene (HDPE) pipes, and interconnected hinged, steel farms (hereafter known as steel fish farms) (Figure 7.1).
Figure 7.1. A circular high density polyethylene pipe (HDPE) fish farm (left) and a typical interconnected hinged steel fish farm with attached feed blowers and a storage barge next to it (right) (Photos by SINTEF Fisheries and Aquaculture).
The circular plastic fish farm is constructed by welding the pipes together into preferred lengths. The complete pipe length is then forced into a circle and the two free ends are welded together. These fish farms systems are delivered as single, double or triple rim systems. The rims are connected together using clamps, made either of HDPE or steel. A HDPE fish farm will normally be moored with a grid mooring system of ropes, connector plates and floats. The steel fish farm is made up of steel bridges, and their flotation devices, connected with hinges. Each bridge is normally 12 m and they are connected in various configurations to make up the fish farm. The flotation devices are generally made of expanded polyester, covered with a protective material, and attached underneath the steel bridges. The hinges allow for rotation around one axis in the horizontal plane, but not around the vertical axis. Steel fish
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farms are relatively stable, with large areas for walking and equipment. The flotation can be controlled and this allows for heavy auxiliary equipment such as feed blowers, and the equipment required to handle net cages and fork lifts on board. Net cages serve as the containment system to keep the fish in place and, in traditional fish farms, are suspended inside the floating collar. The netting material (most commonly polyamide) is attached to a frame of ropes that distributes the resultant forces. Weights are attached to the netting, to maintain the correct shape and volume (see Fridman 1992 for more information about materials and Moe et al. 2007a for net cages in particular). Modern high strength materials such as “ultra-high molecular weight polyethylene� (UHMWPE) are used in some new fish farm and net cage designs. These materials have different market brand names like Dyneema and Spectra (Moe et al. 2005). Fish farm mooring systems primarily consist of ropes, floats and anchors. Several smaller components; shackles, connection plates, chains, rings etc., are used in the mooring system to connect together the primary parts. The purpose of a mooring system is to secure the fish farm in the desired position. Mooring requirements are determined by the size and characteristics of the fish farm and conditions like bottom topography and weather conditions at the specific site. There are two main methods for mooring a fish farm; either by independent lines attached directly to the floating collar, or, by a grid mooring system to which one or several floating collars are connected (Figures 7.2 and 7.3).
Figure 7.2. Illustration of a HDPE collar fish farm with a grid mooring system (left) and of an steel fish farm with moorings (right) (Illustrations by SINTEF Fisheries and Aquaculture).
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Figure 7.3 Illustration of a grid mooring system for HDPE collar fish farms (Illustration by Aqualine AS).
Mitigating
and preventing escapes
A wide range of measures are available to better prevent fish escapes, many of which have been identified during the Prevent Escape project, from other relevant work, and general experience dealing with fish escapes in Norway over the past decade. The biggest contributors to both the number of fish escaping and the number of escapeincidents are mooring system failures and hole formation after failures in the net cage. The main mechanisms to prevent mooring system failure are: 1) detailed site surveys; 2) rigorous implementation of technical standards for equipment; and 3) proper requirements for mooring system analysis. To reduce the incidence of hole formation in net cages, measures include: 1) implementation of technical standards; and 2) implementation of operational measures to prevent fish from biting the net and predators attacking the net cage. The operation and regulation of the fish farming industry encompasses a number of diverse stakeholders, from fish farming companies to equipment manufacturers, and local, regional and national governments. Recommendations relevant to all of these stakeholders are presented here, but, not all of the recommendations are directed to all of the stakeholders (see Table 7.2 for an overview).
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Principles for sea-cage design Risk is a product of probability and consequence; some measures that reduce consequence might increase probability. Further, is it not possible to have zero probability, so it is always necessary to define what the acceptable consequences of an event occurring are in relation to the likelihood of occurrence. Risk awareness can be applied at several levels; the probability for a failure and consequence for that failure can be assessed at the individual incident level (sea-cage), or on a more aggregated level (farm site or industry as a whole). Failure of components, operational errors and human mistakes cannot be completely prevented, so it is important to design equipment in such a way that failures of individual components, or human error, do not lead to total equipment breakdown. For example, a mooring component failure should not lead to the failure of the whole mooring system or farm, and furthermore, should not lead to fish escaping. This should be the key design principle for fish farms and is the basis used here to formulate the design and operational guidelines outlined in this report.
General
recommendations
1) Mandatory reporting of all escape events, including: • The number of fish that escaped, their age, size and health status. • A description of the sea-cage technology involved, including the age of the equipment, manufacturer and whether or not the equipment is designed or certificated according to any technical standards. • Description of site and relevant environmental data including water depth, maximum current, wind and waves. Estimate of current, wind and wave conditions at time of escape if relevant to escape cause. • Categorization of the operational circumstances. • An estimated cause of escape.
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A specific form for reporting should be developed for each country. Existing forms exist in Scotland and Norway and could be used as guidelines. 2) Evaluation. Introduction of a defined procedure to collate, analyse and learn from the data collected during mandatory reporting. The information should be provided to equipment suppliers and fish farmers so that equipment and operational improvements can be made. This could be a government service, a joint industry effort, or a combination of both. 3) Risk evaluation and identification. Risk analyses should be completed for the planning, design, production, delivery, installation and operation of the fish farm. Each risk analysis should be broken down into the probability and consequences of an incident occurring, and be based on approved procedures (e.g. according to requirements laid down in the ISO manual). The analyses should be clearly documented to facilitate review. 4) Operational procedures. Some fish farming operations are likely to pose a higher risk of an escape event occurring if they are done incorrectly, for example; correct anchoring and mooring of the net cage, connecting net cages to floaters, and correctly weighting the net cages in currents. These critical operations should be identified through a risk evaluation (see above) and risk reduction strategies employed. Copies of operational procedures should be readily available at all sites. Relevant personnel should be aware of the procedures and receive appropriate training before commencing duties. 5) Training. A large percentage of escape incidents are due to operational errors. Fish farming is a complicated, multi-disciplinary activity, and expertise in several different areas is required. Until now, education has focused mainly on the biology of fish farming, with less attention paid to the technical aspects. The industry should consider mandatory training of all relevant personnel concerning the environmental consequences of fish escapes, as well as the relevant operations and technical measures required to reduce escape incidents. A training course could be a joint industry effort. 6) Technical standards. Detailed technical standards should be introduced. There are relevant standards, such as NS 9415 (NS 9415.E:2009, 2009) and the preliminary Scottish standard (SARF 073, 2012), and also plans to develop an ISO standard for aquaculture technology similar to these. There are also general purpose standards for the design and dimensioning of constructions, such as the EN Eurocodes (EUROCODE), which are relevant to fish farm. The same constructional design principles apply, independent of construction type, and our recommendation is to use the Eurocodes standards as the basis for the design of floating fish farms. The structure that is unique to fish farms is the net cage. It has distinctive properties, both in terms of construction and with respect to its behaviour and handling of loads subject to currents and waves. There are several relevant design standards and codes of conduct for the use of net cages (Table 1) and methods and procedures for calculation of behaviour and loads (Løland 1992; Lader et al. 2008; Moe et al. 2010; Kristiansen and Faltinsen, 2012). The latter is also described in NS 9415 and the preliminary Scottish standard.
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7) Hand books/User manuals. The manufacturers of fish farm equipment should supply a detailed handbook describing the product, including: • the design capacity relative to current, wind and wave levels; • inspection and maintenance plans; • integration and installation with other main components. These handbooks should be available at all fish farms and all personnel should be familiar with their content. 8) Certification system. A certification system should be introduced for equipment approvals, based on technical standards and requirements for construction design: • Certification of products and relevant service providers for procedures such as anchor handling and site survey, the main components of the fish farm, such as the mooring system, net cage and floating collar, and the feeding barge and relevant auxiliary equipment such as the feed pump. • Equipment integration should be documented, for example attaching the net cage to the floating collar. • Service providers should to be certified according to specific standards to ensure competence and safety in procedures and the reduction of fish escape incidents. • Site approval – checking that the components and equipment used in all fish farms meets technical standards and is installed according to approved procedures and instructions. Site approval should be sought prior to fish being introduced to the farm. The comprehensive system that exists in Norway may not be relevant or feasible for other countries. Rather than focusing on such an extensive system, which might lead to opposition from other countries, prioritising those elements that have the greatest impact on the reduction of fish escapes would be prudent. For instance the introduction of site specific farm certificates incorporating: • A site survey stating the environmental conditions and bottom topography. • A mooring analysis. • Control of the interconnection and coupling of the main components according to the relevant handbook.
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Specific recommendations - fish farm: 1) Site surveys. Currents, wind and wave characteristics should be determined for all of the sites to enable the design and selection of suitable equipment for the site-specific weather conditions. The net cage and floating collar need to withstand variable environmental loads, but will not necessary be designed specifically for each site, rather they could be categorized into classes suitable for conditions up to a maximum current and wave force. Mooring systems, on the other hand, need to be specifically dimensioned for each site, due to differences in farm layout, water depth and bottom topography. 2) Weight system. The weight systems need to be designed and installed so that it does not introduce unnecessary loads onto the netting material or make direct contact with the netting, causing abrasion. The weight system is an integrated part of the complete fish farm and its interactions with other components of the farm must be considered both by the manufacturer of the floating collar and of the net cage.
Specific recommendations - farming equipment: 1) Design. Products and components should be designed according to a technical standard, with an independent body to enforce the standard. Manufacturers should provide data supporting the strength and capability of their product and a third party should then control of the presented data. 2) Risk based design. Farms should be designed so that an individual failure will not lead to larger failures and fish escapes.
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Specific recommendations - mooring system: 1) Dimensioning. The design should be based on the bottom topography and environmental loads at each site. The procedure should follow accepted standards and protocols. A proper numerical mooring analysis should be performed. 2) Redundancy. The design should allow for breaks in individual mooring lines, without the loss of integrity of the mooring system. 3) Connector plates. Connector plates should be handled with care and the design and use allow for damage, fracture or rupture of a connector plate to occur without the loss of integrity of the mooring system. 4) Anchors. The holding power of all anchors should be tested and documented after installation. Accepted procedures should be followed. 5) Mooring system components. Only certified steel mooring components should be used. Shackles need to have reliable safety pins installed. Care should be taken when steel components of different quality are attached to each other to avoid galvanic corrosion. Mooring chains in the surface zone are at risk of corrosion. In addition, metal components in the surface part of the mooring system may damage the netting and their use should be minimised. 6) Ropes and knots. Ropes used in the mooring system are subject to UV degradation and knots generally reduce the strength of a rope by 50%.
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Specific recommendations - net cage systems: 1) Fish biting. Fish biting is a major cause of escape incidents, but certain preventative measures are possible (Moe et al. 2007b; Høy et al. 2012) and these may also reduce the effect of predator attacks: • Stronger net cage constructions. • Avoid minor damage to nets from handling and abrasion. • Inspect the net cage frequently for holes. • Ensure net repairs are of a good quality. • Keep the cage nets clean - biofouling may attract the fish. • Make sure that cage nets are taut. • Check that the mesh width is suitable for the fish size. • Make sure that the fish are fully fed at all times. • Frequently grade fish for size. • Provide a stimulating cage environment to distract the fish from biting. 2) Abrasion and wear. The formation of holes, due to wear and tear, and net abrasion, due to contact with other components such as the weight system, are a major problem. Contact between vertical chains or other hanging components of the fish farm and the net cage should be prevented. A well-designed weight system that remains taut at all times is highly beneficial. The weight system and net cage need should be designed/selected together. The manufacturers of the net cage and floating collar should provide detailed instructions on how to attach, inspect and use the weight system in order to avoid contact with the netting. 3) Predator attacks. It is difficult to prevent predator attacks completely; however, it is possible to reduce the number of attacks and the effect of the attacks: 1) remove dead fish daily, or even more frequently at sites with high predation risk; and 2) introduce a double net around the dead fish removal system to avoid wear. A well-designed weighting system which keeps the sea-cage net taut will also reduce the capacity of predators to make holes.
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Recommendation
Government Fish farmer (legislation)
Equipment producer
Relevant towards cause of escapement
1
Mandatory reporting
X
X
X
All
2
Evaluation
X
X
X
All
3
Risk evaluation and identification
X
X
All
4
Operational procedures
X
X
All
5
Training
X
X
All
6
Certification system
X
X
X
All
7
Technical standards
X
X
X
All
8
Hand books/User manuals
X
X
Operational failure and human errors
9
Site surveys
X
X
Structural failure, Mooring failure
10
Weight systems
X
X
Hole in net
11
Design farm system
X
X
Structural failure
X
Operational failure, Structural failure, Mooring failure and human errors
X
Mooring failure
12
Risk based design
X
13
Dimensioning
14
Redundancy mooring
X
X
Mooring failure
15
Connector plates
X
X
Mooring failure
16
Anchors
X
X
Mooring failure
17
Mooring system components
X
X
Mooring failure
18
Ropes and knots
X
Mooring failure
19
Fish biting
X
Hole in net
20
Abrasion and wear
X
21
Predator attacks
X
22
Research and development
X
X
X
Hole in net Hole in net
X
All
Table 7.2 Overview of recommendations and their relevance to different stakeholders and major cause of escapement.
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Recommendations for further research and development As technological development in the industry is ongoing, a focus on improving the quality of fish farm equipment is constantly required. Much relevant knowledge and competence has been developed through Prevent Escape and other national and international research projects specifically related to escapes. Significant future gains may also be made by drawing upon and integrating developments and discoveries in other industrial sectors and scientific disciplines. Net cage failures are the most common causes of escape, both with respect to the number of incidents and the number of fish escaping. Thus, improvements to net design, and/or netting material would be of great value in reducing escapes. A large number of new materials and net cages have been proposed, but there are challenges in updating systems in terms of cost and difficulty in replacing single components within operational systems. The netting materials developed for other industries have very different properties to those currently used in fish farms, therefore, the use of new net cage materials would involve a major change in fish farming operations, accessory equipment and staff training. If these new materials are to be properly integrated, research and development on their properties and correct use will be required.
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cited
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