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Study on population parameters of 5(five) indigenous fish species in the Shitalakhshya river Chapter I Introduction Bangladesh is a country rich in biological heritage and fish plays a very important role in our day-to-day life. Fish constitutes an essential and often irreplaceable staple food for the people of Bangladesh and the fisheries sector plays a vital role in the economy through employment generation, nutrition supply and poverty alleviation. Many rivers were originated from the Himalayans and criss-crossed on the plain land of Bangladesh and falls on the Bay of Bengal. Three sides of Bangladesh are geographically surrounded by India, which borders the country to the west, north and east, and the Bay of Bengal guards the southern frontier. More than half of the lands are very low, has a slope towards the Bay of Bengal on the south and during monsoon, this vast quantity of lands got flooded. The three big rivers, i.e. the Padma, the Meghna and the Jamuna (Brahmaputra) and their innumerable tributaries and distributaries carry huge amount of water and silt every year that spreads all over the country and finally ends up in the Bay of Bengal. The rate of water flow through these river systems is second only to the Amazon River system in South America (Khan, 2008). The major river systems and their criss-crossing branches make Bangladesh one of the richest areas in this subcontinent in respect to freshwater fishery (Rahman, 1989). Rivers tend to eliminate irregularities and form a smooth gradient from its source to its base level. As it approaches base level, downward cutting is replaced by lateral cutting, and the river widens its bed and valley and develops a sinuous course that forms exaggerated loops and bends called meander. A river can open up a new channel across the arc of a meander, thereby cutting off the arc and creating a lake. River velocity determines quantity and size of rock fragments and sediment carried by the river. Whenever velocity is checked by changes of flow of gradient, by meeting the water mass of lakes or ocean, or by the spreading of water when a stream overflows its banks, part of the load carried by the stream is deposited in the riverbed or beyond the channel. Landforms produced by deposition include the Delta, the flood plain, the channel bar, and the alluvial fan and cone. Traditionally, river systems have been classified according to their stage of development as 'young', 'mature', or 'old'. The young river is marked by steep sided valley, steep gradients, and irregularities in the bed; the mature river by a valley with a wide floor and flaring sides, by advanced head ward erosion by tributaries, and by a more smoothly gradient bed; and the old river by a course graded to base level and running through a pen plain, or broad flat area. Most of the rivers of Bangladesh are at their old stage and enter into the Bay of Bengal. River valleys have been important centers of civilization, they afford travel routes, and their alluvial soils form good agricultural lands. Navigable rivers are important in commerce and have influenced the location of cities. In Bangladesh, almost all the major cities/towns and commercial centers are located on the banks of rivers, e.g., Dhaka on the bank of Buriganga, Narayanganj by the side of Shitalakhshya, Chittagong by the side of Karnaphuli and Mymensingh by the side of Brahmaputra. Rivers with sufficient water volume, velocity and gradient can be used to produce hydroelectric power. At Kaptai the river Karnafuli of Chittagong region is being utilized for producing hydroelectricity.


Rural Bangladesh is blessed with innumerable seasonal impoundments such as small ponds, tanks, ditches, canals etc. In Bangladesh, inland fisheries production is an integrated system in the rivers, floodplains and haors, all connected by khals (canals). The floodplains act as nutrient-rich nurseries for a large number of larval and juvenile fish species. All these resources contribute to a rich assemblage of freshwater species that become an integral part of our food culture. From the time immemorial, people of Bangladesh have been harvesting fish. Fishing in every available water resources here is a kind of hunting activity. Indeed, fishing is even older than agriculture itself and always has a major role to play in the supply of delicious and high quality protein food to people. Fisheries have been integrated in such an extent to our life and heritage that Bangladeshis have traditionally been identified with fish and rice, which constitute the major items of their daily diet. The Bengali expression “Mache Bhate Bangali”, “Fish and Rice make a Bengali” expresses this importance (Graff et al., 2001). Bangladesh possesses a wide range of fishes, prawns, lobsters, mollusks, turtles and other fishery resources inhabiting its extensive marine and inland open waters. Inland open water fisheries contributed 73% of the total fish production. In 1987, Bangladesh became third in world inland fish and shrimp production after China and India and produced 5, 81,827 m tons of fish and shrimp. Fisheries play an important role in the national economy and account for 4.7 percent of GDP, 9.1 percent of the export earnings (1995 - 1996), 6 percent of the supply of protein and about 80 percent of the animal protein intake of its population (FAO, 1987). The fisheries sector is vibrant and contributed about 20% of agricultural GDP. The sector contributed 4.05% to GDP and 4.90% of the national export earnings. The growth rate in the fisheries sector has increased from 2.33% in 2002-03 to 4.11% in 2007-2008 (Karim et al., 2010). Presently the sector contributes 22% to agricultural sector and 58% to animal protein supply. About 12.8 million people are involved in fisheries for their livelihood (DoF, 2009). Annual growth rate of fish production is about 7%. The growth is largely from inland open water fisheries and pond fish production. Fish production in the inland open water, particularly in the rivers and flood plains has declined significantly during the last three decades due to degradation of water bodies. The fisheries sector provides full-time employment for about 2 million people, equivalent to 7 percent of total employment, of whom about 1.4 million people are engaged in fishing and fish farming while the rest work in fish transportation, packing and processing. Another 11 million people are involved in seasonal or part-time fishing or other ancillary activities. Shitalakhshya River originates from the old Brahmaputra and bifurcates into two courses at Toke in Gazipur district. One of the courses named the Banar flows southwest and at Lakpur is renamed as the Shitalakshya. It then flows east of Narayanganj town. The Shitalakhshya falls into the DHALESHWARI near Kalagachhiya. The length of the river is about 110 km and the width near Narayanganj is about 300 m but reduces to about 70 m in the upper reach. Its highest discharge has been measured at 2,600 cumec at Demra. The river is navigable throughout the year and shows little erosion tendency. In the past, the famous MUSLIN industry of the country flourished along the Shitalakhshya. At present, a number of heavy industries including the Adamjee jute mills, stand on the banks of Shitalakhshya. There are three thermal powerhouses located at Palash, north of Ghorashal, and one at Siddhirganj, on the bank of the river. The important river port of Narayanganj is also situated on its bank. The river was once famous for its clear and cool water. The river goes under tidal effect for about five months of the year but never overflows its banks (Banglpedia).


Information about fish age, development and growth is a cornerstone in fishery research and management. By development we mean the sequencing of life history stages while growth is a measure of size change of the whole body or some body part; growth rate is also a measure of size change as a function of time. Growth depends upon the quantity and quality of food ingested, with inadequate nutrition delaying both growth and developmental transitions, such as the timing of onset of sexual maturation. When food is limited, the onset of maturation may be delayed for months or years until good feeding conditions arise. In other words, the timing of sexual maturation appears to be more closely associated with size than age, leading to the concept that maturation is achieved once a “critical size� has been reached. Furthermore, during adulthood, fecundity or gamete production may be related to body size, and alterations in nutrition can lead to either depression or enhancement of the reproduction. Thus, food availability, size increase, accumulation of energy reserves and timing of sexual maturation and reproduction are closely linked. These factors, in turn, relate to production, that is determined by the reproduction and growth rates of individuals within the population and by their mortality rate. These functional rates determine the population dynamics over time, as well as the structural elements of the population, such as biomass, density and sizefrequency distribution, at any point in time. As such, information about age and growth is extremely important in almost every aspect of fisheries (Jobling, 2002). Organisms grow because greater body size confers a number of advantages that can ultimately result in higher lifetime reproductive output. Larger individuals are subjected to lower predation mortality: the faster they grow the more rapidly their mortality rate decreases. Larger individuals can also store more energy and thus become less susceptible to fluctuations in food supply and environmental extremes. Fecundity and ability to compete for mates and resources also increase with size. Large size can be attained by hatching at a large size, growing fast or growing for a long time. Furthermore, delaying the age at maturity provides more energy for growth (Jennings et al., 2001). Excessive fishing pressure at a global level has reduced, and continues to threaten, endemic fresh water and marine fish populations. In many parts of the world, exploitation spanning several generations of top predators has shifted ecological equilibrium to an unknown extent (Jackson et al. 2001, Carr et al. 2003). The effectiveness of management actions, however, requires reliable information to compare population parameters under unexploited conditions with those from exploited populations. Unfortunately, pre-exploitation fish population parameters such as natural mortality (M) and catch per unit effort (CPUE), important abundance indices in measuring fishing-induced changes, are lacking. This lack of baseline information has frustrated attempts to assess exploited fish populations using conventional catch rate or per-recruit (PR) methods. In particular, PR methods can be biased, mainly on account of the difficulty in obtaining reliable estimates of M (Hilborn and Walters 1992, Bohnsack 1993, Ludwig et al. 1993, Hutchings 2000, Pinnegar et al. 2000). Inland fishery management has to account for changes in terrestrial environment especially within the catchments area. Alterations in the surrounding area can cause changes in the physico-chemical properties of the aquatic environment which in turn can lead to changes in the biotic system as well. To this end, water quality monitoring has been practiced and used for fish protection. However, chemical analysis most often needs sophisticated equipment especially with increasing industrial discharge of organic compounds. For this reason, biological monitoring has been used as an indicator of pollutant loading (Hawkes, 1977; Bryce et al., 1978). A more recent development is the direct monitoring of fish population. Accurate estimates of population structure of fish communities in a pollution free area and monitoring changes in the parameters at population level are very important. The parameters,


which are potentially useful for detecting changes in the fish population, include analysis of community composition, relative species abundance, changes in species composition and diversity indices. A pollution-free environment is needed so that these inventories can be regarded as the normal population and used as reference. Overexploitation and habitat loss are believed to be responsible for declines in many fresh water fish populations in almost all the rivers of Bangladesh. In Shitalakhshya River, fish populations of different species exhibit heavy mortality rates that result in very few individuals in the population living past the age of recent years. In recent years, different organizations and NGO’s have become increasingly concerned about the status of fresh water fish populations. Data on population dynamics of indigenous fish species in Bangladesh perspective is very scarce. What is more to be mentioned is that such study in reverie species is nearly unavailable. It is very important to assess population parameters of both floodplain and river species for the sake of base line data to be used in further applied research. Considering all, the present study has been initiated to be focused on determination of abundance and population dynamics of the five small native species in Shitalakhshya River, Narayanganj. The objectives of the present study are as follows: 1. To determine the present status and important fisheries resources of Shitalakhshya river. 2. To determine the population parameters of selective species 3. To determine the present exploitation rate of the studied species 4. To determine the mortality rate of the studied species 5. To determine the management options based on fishing and natural mortality 6. To provide suggestions for sustainable management Chapter II Review of Literature Martínez et al.(2011) did research on Population parameters of the Pacific flagfin mojarra Eucinostomus currani (Perciformes: Gerreidae) in the Gulf of California and identified minimum lengths was 4.5cm and the maximum was 21.0 cm of wide variety of non-target species of fish, crustaceans, and mollusks that are relatively unknown. They also concluded that survivals of those caught species were ensured because reproduction is indirectly protected. Karimzadeh (2011) studied on natural and fishing mortality and exploitation rate of common Kilka (Clupeonella cultriventris) in southeast part of the Caspian Sea (Babolsar). He obtained natural and fishing mortality up to 0.671 per year and 0.849 per year, respectively of selected species. The total mortality of common kilka has been estimated up to 1.52 per year. .He also estimated the annual survival rate of common kilka up to 0.218/year. Arshad et al. (2010) observed growth, mortality and recruitment of the sergestid shrimps Lucifer intermedius, in Johor, Peninsular Malaysia and found extreme length of shrimp 10.42 mm. They also estimated natural and fishing mortality was 2.99 yr-1 and 2.33 yr-1, respectively. Abowei and Davies (2009) did research on Some Population Parameters of Clarotes Laticeps from the Fresh Water Reaches of Lower Nun River, Niger Delta Nigeria and found the


largest specimen measured 60.1cm and weighed 492g and the natural mortality (M) value was 0.87; fishing mortality (F) value was 0.33. Alaş and Akif (2007) investigated of Some Population Parameters of the Tench (Tinca tinca L., 1758) Inhabiting Beyşehir Lake (Konya-Turkey) and identified that specimens ranged from 14.9 to 38.5 cm in fork length, and 48.5 to 967.10 g in weight. Silvestre and Garces (2004) measured population parameters and exploitation rate of 25 species of demersal fishes in Brunei Darussalam during 1989–1990. They found relatively high K (and low L∞) values, typical of short-lived tropical fishes, were obtained for most (22) of the species. Combined with the high exploitation rate (Z), (0.85–3.40) and natural mortality rate, (M) (0.73–3.10) estimates, these results imply low annual survival and high turnover rates. Jayawardane et al., (2002) measured Population parameters of Penaeus indicus, Penaeidae of the artisanal shrimp fishery in the Negombo lagoon and the associated coastal ecosystem on the west coast of Sri Lanka. They calculated asymptotic length growth of selected fish species was 19.2 cm for males and 19.9 cm for females. The natural mortality coefficient was estimated at 1.73 per year. Devadoss (1998) did experiment on Growth and population parameters of the spade nose shark, Scoliodon laticaudus from Calicut coast and he obtained average growth value for nose shark, which was 715 mm per year. He also observed that the average estimated annual catch was 14.4 tonnes at the existing mortality value of 0.73%. Miah et al. (1997) estimated the growth and mortality parameters of hilsa Tenualosa ilisha (Ham.) population in the Meghna river of Bangladesh and smallest length at first capture (L) of hilsa was 3.65 cm and the largest length was identified was 57 cm. They also observed Hilsa population is presumed to be suffering from natural and fishing mortality since the age at recruitment is affected by recruitment over fishing. The total mortality (Z) was 2.03 year and thus it was found that 13.13 % T. ilisha survives only in the Meghna river. MacCali (1973) calculated the annual mortality rate for the northern anchovy, Engraulis mordm, is estimated to be 66.5% in southern California waters. Chapter III Materials and Methods The experiment was a preliminary research work which was conducted in order to identify population parameters of given fish species. The experiment was carried out in the Shitalakhshya river, Narayanganj, Bangladesh. The study was conducted for a period of six months starting from June, 2010 to November, 2010. The relevant data were collected on a monthly basis at a regular interval for the specified time frame. 3.1

Sampled Fish species


Total five fish species were selected for the current study to investigate the required information. They were: 1) 2) 3) 4) 5) 3.2

Tengra (Mystus tengra), Punti (Puntius sarana), Taki (Channa punctatus), Foli (Notopterus notopterus) and Kholisha (Colisa faciatus) Study area

The present study was conducted on Shitalakhshya river which originates from the old Brahmaputra and bifurcates into two courses at Toke in Gazipur district. One of the courses named the Banar flows southwest and at Lakhpur is renamed as the Shitalakhshya. It then flows east of Narayanganj town. The Shitalakhshya falls into the Dhaleshwari near Kalagachhiya. The length of the river is about 110 km and the width near Narayanganj is about 300 m but reduces to about 70 m in the upper reach. The study area was selected near from the main Shitalakhshya steel bridge to Nitaiganj market, approximately four kilometers of the river area and total 3 (three) different sites were chosen and accordingly encircled with nets and bamboo poles of which each site had an area of 400 square meter (20 meter in length and 20 meter in width). The selected sites were looking like fish sanctuaries and the distance between two sites was around 1 (one) kilometer.

Fig 1.1 Study area map


Fig 1.2 Study area (Satellite view) 3.3

Recruitment and growth

Before recruitment of fingerlings of fish species, a standard length for each selective fish species were determined. Then live fingerlings of standard size (or very close to standard length) were collected directly from the river sources with the help of fishermen and those were recruited in May, 2011 and the total growth rate was observed throughout the aforesaid period (from June, 2011 to November, 2011). Prior to stocking, the standard lengths for the selected fish fingerlings were as follows: Selected Fish Species

Standard length of fingerlings (in cm)

Tengra (Mystus tengra),

2.1 ± 0.2

Punti (Puntius sarana),

3.0 ± 0.2

Taki (Channa punctatus),

4.2 ± 0.2

Foli (Notopterus notopterus) and

5.2 ± 0.2

Kholisha (Colisa faciatus)

1.9 ± 0.2


Plate 1. Experiment area (Site-1).

Plate 2. Experiment area (Site-2).

Plate 3. Experiment area (Site-3). Using fine ber jal and monofilament gill nets, fishing was performed repeatedly from each enclosed area to ensure that no naturally available fish was there which may interrupt with the recruited fish species. In each enclosed area, 50 fingerlings of each type of chosen fish species of standard length were recruited and thus a total of 250 fish fingerlings were recruited in each enclosed area. For each species total 150 fingerlings were collected and recruited equally in three enclosed sites. No artificial food was provided for the recruited fingerlings and they were allowed to grow naturally in the river water. Measures were taken so that no emigration and immigration of fish took place between inside and outside the sites. The bamboo poles were interconnected with the help of additional bamboo frames and each enclosed area was supplied with water-hyacinth to provide shelter for the recruited fish. A regular and constant vigilance was made available so that no unwanted catching of fish took place from the enclosed sites. Recruitment of selective fish fingerlings were done at the beginning of experiment and further no more recruitment was done. 3.5

Sampling and data collection


Sampling and data collection were done by catch and re-catch method. From each enclosed area at least 10 fish individuals were caught for data assessment by random sampling inside the selected fenced area and the gears which were used to harvest fish were seine net, push net, gill net and traps. In case of length measurement of selected fish fingerlings, standard length (from the tip of the snout up to fork) were measured with the help of a centimeter scale or length tape by placing the species dorso-ventrally on the measuring board. To measure weight, an electric balance meter was used to obtain accurate weight. Total harvesting was done in November; 2011and total live fish individuals were counted to calculate the survival and mortality rate. To observe the present status of fish availability in the studied river, fish data were also collected from the areas between sites as caught by the fishermen.

Plate 4. Punti (Puntias sarana)

Plate 5. Foli (Notopterus notopterus)


Plate 6. Tengra (Mystus tengra)

Plate 7. Taki (Channa punctatus)

Plate 8. Kholisha (Colisha faciatus)


Plate 9. Net used to enclose the sites (site 1, 2 and 3).Plate 10. Net used to collect samples from sites (site 1, 2 and 3). Chapter IV Results A total 5 different indigenous fish species i.e., tengra (Mystus tengra), punti (Puntius sarana), taki (Channa punctatus), kholisha (Colisa faciatus) and foli (Notopterus notopterus) were recruited in each of the study area inside a 20mĂ—20m square enclosed experimental zone to monitor different parameters of the recruited fish population. Table 1.1 Average increase of length during observation period in site 1. Sl. no .

Fish species

Average increase of Average length of fish before (cm) recruitment No of fish observed in each month (cm) June July August

1 2 3 4 5

M. tengra P. sarana C. punctatus N. notopterus C. faciatus

2.1 3 4.2 5.2 1.9

10 10 10 10 10

0.1 0 0 0.1 0

During observation period (from June, 2011 to November, 2011), taki (Channa punctatus) has shown the highest average growth (1.73 cm per month) in length in site 1 followed by foli (Notopterus notopterus) having 1.57 cm/month. The lowest count on average growth in length per month was exhibited by kholisha (Colisa faciatus) having 0.75 cm followed by punti (Puntius sarana) having 0.9 cm. In site 1, tengra (Mystus tengra) indicated moderate average growth in length having 1.12 cm per month (Table 1.1).

2.2 1.3 2.2 2 1.1

1.7 1.2 2.4 3.4 1.0


Total growth in length of 5(five) fish species in site 1 16

Length (cm)

14 12

tengra

10

punti

8

taki

6

foli

4

kholisha

2 0 June

July

August

September

October

November

Month

Fig 2.1 Total growth in length of 5(five) fish species in site 1. In fig. 2.1, foli (Notopterus notopterus) displayed highest total growth in length followed by taki (Channa punctatus) while the lowest total growth was represented by kholisha (Colisa faciatus). In site 2, foli (Notopterus notopterus) has displayed the maximum average growth (1.78 cm per month) in length followed by taki (Channa punctatus) having 1.77 cm/month during study period. The minimum average growth in length per month was exhibited by kholisha (Colisa faciatus) having 0.67 cm followed by punti (Puntius sarana) having 0.83 cm. Moderate average growth in length was shown by tengra (Mystus tengra) having 1.40 cm per month in site 2 (Table 1.2). Table 1.2 Average increase of length during observation period in site 2. Sl. no .

Fish species

Average increase of Average length of fish before (cm) recruitment No of fish observed in each month (cm) June July August

1 2 3 4 5

M. tengra P. sarana C. punctatus N. notopterus C. faciatus

2 3 4.1 5.1 2

10 10 10 10 10

0 0 0.1 0.1 0

2.1 1.1 2.3 2.6 1

2.7 1.3 2.5 3.4 1.1


Length (cm)

Total growth in length of 5(five) fish species in site 2 18 16 14 12 10 8 6 4 2 0

tengra punti taki foli kholisha

June

July

August

September

October

November

Month

Fig 2.2 Total growth in length of 5(five) fish species in site 2. It is revealed in fig. 2.2 that foli (Notopterus notopterus) displayed highest total growth in length followed by taki (Channa punctatus) while the lowest total growth was represented by kholisha (Colisa faciatus). During the period of experiment, foli (Notopterus notopterus) has indicated the maximum average growth (1.85 cm per month) in length in site 3 followed by taki (Channa punctatus) having 1.80 cm/month. The minimum count on average growth in length per month was displayed by kholisha (Colisa faciatus) having 0.72 cm followed by punti (Puntius sarana) having 0.85 cm. In site 3, tengra (Mystus tengra) exhibited moderate average growth in length having 1.15 cm per month (Table 1.3). Table 1.3 Average increase of length during observation period in site 3.

1 2 3 4 5

Fish species M. tengra P. sarana C. punctatus N. notopterus C. faciatus

Average length of fish before recruitment (cm) 2 3.1

No of fish observed in each month 10 10

Average increase of length during observation period (cm)

4

Avg. growth in length (cm/month)

June

July

August

September

October

November

0.1 0

1.7 1.1

2.2 1.2

1.3 1

0.9 1

0.7 0.8

1.15 0.85

10

0.1

2.4

2.7

2.3

1.8

1.5

1.8

5

10

0.2

2.5

3.6

2.3

1.4

1.1

1.85

2.1

10

0

1

1.2

0.9

0.7

0.5

0.72

Total growth in length of 5(five) fish species in site 3

Length (cm)

Sl. no .

18 16 14 12 10 8 6 4 2 0

tengra punti taki foli kholisha

June

July

August

September Month

October

November

Fig 2.3 Total growth in length of 5(five) fish species in site 3.


It is evident in fig. 2.3 that Foli (Notopterus notopterus) displayed highest total growth in length followed by taki (Channa punctatus) while the lowest total growth was represented by kholisha (Colisa faciatus). Table 2.1 Average increase of width during observation period in site 1.

Sl. no .

Fish species

Average width of fish before recruitment (cm)

1

M. tengra

0.4

No of fish observe d in each month 10

2

P. sarana C. punctatus N. notopterus C. faciatus

0.4

4 5

Avg. growth in width (cm/month)

June

July

August

September

October

November

0.1

0.2

0.4

0.2

0.1

0.1

0.18

10

0.1

0.5

0.7

0.4

0.2

0.2

0.35

1

10

0

0.4

0.5

0.2

0.2

0.1

0.23

2.8

10

0.2

0.7

1.1

0.7

0.6

0.4

0.62

1.4

10

0.1

0.4

0.6

0.4

0.4

0.2

0.35

Table 2.1 indicates that foli (Notopterus notopterus) has shown the largest average growth (0.62 cm per month) in width in site 1 followed by punti (Puntius sarana) and kholisha (Colisa faciatus) having 0.35 cm/month. The lowest count on average growth in width per month was exhibited by tengra (Mystus tengra) having 0.18 cm followed by taki (Channa punctatus) having 0.23 cm (Table 2.1). Total growth in width of 5(five) fish species in site 1 7 6 tengra

5 Width (cm)

3

Average increase of width during observation period (cm)

punti

4

taki

3

foli

2

kholisha

1 0 June

July

August

September

October

November

Month

Fig 3.1 Total growth in width of 5(five) fish species in site 1. It is seen in fig. 3.1 that foli (Notopterus notopterus) displayed highest total growth in width followed by kholisha (Colisa faciatus) while the lowest total growth was represented by tengra (Mystus tengra).


Table 2.2 Average increase of width during observation period in site 2.

1 2 3 4 5

Fish species M. tengra P. sarana C. punctatus N. notopterus C. faciatus

Average width of fish before recruitment (cm) 0.5 0.5

No of fish observed in each month 10 10

Average increase of width during observation period (cm)

0.9

Avg. growth in width (cm/month)

June

July

August

September

October

November

0.1 0.1

0.3 0.4

0.3 0.7

0.2 0.5

0.2 0.3

0.2 0

0.22 0.33

10

0.1

0.5

0.7

0.4

0.3

0.2

0.37

3

10

0.2

0.8

1.2

1.1

0.8

0.6

0.78

1.5

10

0.1

0.2

0.3

0.2

0.1

0

0.15

In site 2, foli (Notopterus notopterus) has displayed the maximum average growth (0.78 cm per month) in width in site 1 followed by taki (Channa punctatus) having 0.37 cm/month during study period. The minimum average growth in width per month was exhibited by kholisha (Colisa faciatus) having 0.15 cm followed by tengra (Mystus tengra) having 0.22 cm. In site 2, moderate average growth in width was showed by punti (Puntius sarana) having 0.33 cm per month (Table 2.2). Total growth in width of 5(five) fish species in site 2

Width (cm)

Sl. no .

9 8 7 6 5 4 3 2 1 0

tengra punti taki foli kholisha

June

July

August

September

October

November

Month

Fig 3.2 Total growth in width of 5(five) fish species in site 2. In fig. 3.2 it is revealed that foli (Notopterus notopterus) displayed highest total growth in width followed by taki (Channa punctatus) while the lowest total growth was represented by tengra (Mystus tengra). Table 2.3 Average increase of width during observation period in site 3.

Sl. no . 1 2 3

Fish species

M. tengra P. sarana C. punctatus

Average increase of width during observation period (cm)

0.4 0.4

No of fish observe d in each month 10 10

1

10

Average width of fish before recruitment (cm)

Avg. growth in width (cm/month)

June

July

August

September

October

November

0.1 0

0.3 0.2

0.4 0.4

0.3 0.1

0.2 0.1

0.2 0

0.25 0.13

0.1

0.6

0.7

0.4

0.3

0.2

0.38


N. notopterus C. faciatus

4 5

2.8

10

0.2

0.7

1.2

0.8

0.6

0.4

0.65

1.4

10

0

0.3

0.4

0.3

0.2

0.1

0.22

During the study period, it was seen that foli (Notopterus notopterus) has shown the maximum average growth (0.65 cm per month) in width in site 1 followed by taki (Channa punctatus) having 0.38 cm/month. The minimum average growth in width per month was exhibited by tengra (Mystus tengra) having 0.13 cm followed by kholisha (Colisa faciatus) having 0.22 cm. In site 3 it was seen that punti (Puntius sarana) exhibited moderate average growth in width having 0.25 cm per month (Table 2.3). Total growth in width of 5(five) fish species in site 3 8

Width (cm)

7 6

tengra

5

punti

4

taki

3

foli

2

kholisha

1 0 June

July

August

September

October

November

Month

Fig 3.3 Total growth in width of 5(five) fish species in site 3. As per fig. 3.3, foli (Notopterus notopterus) displayed highest total growth in width followed by taki (Channa punctatus) while the lowest total growth was represented by punti (Puntius sarana). It was revealed that, foli (Notopterus notopterus) has shown the maximum average increase (14.4 gm per month) in weight in site 1 followed by taki (Channa punctatus) having 13.4 gm/month. The lowest average gain in weight per month was exhibited by kholisha (Colisa faciatus) 6.68 gm/month followed by tengra (Mystus tengra) having 7.8 gm/month. In site 1, punti (Puntius sarana) indicated moderate average growth in weight 10.6 gm per month (Table 3.1).


Sl. no .

Fish species

Average weight of fish before recruitment (gm)

1

M. tengra

10.5

No of fish observe d in each month 10

2

P. sarana

15.2

10

0.5

22.1

10

0.4

26.9

10

0.2

9.8

10

0.2

3 4 5

C. punctatus N. notopterus C. faciatus

Average increase of weight during observation period (gm) June

July

August

September

October

November

Avg. weight gain (gm/month)

0.3

8.5 14. 1 16. 1 16. 6 10. 5

12.6

10.3

8.5

6.6

7.8

16.3

11.8

11.3

9.7

10.6

22.4

17.7

12.5

11.1

13.4

22.4

17.8

17.2

12.4

14.4

10.6

7.7

6.5

4.6

6.68

Table 3.1 Average increase of weight during observation period in site 1.

Total growth in weight of 5(five) fish species in site 1 120

Weight (gm)

100

tengra

80

punti

60

taki

40

foli kholisha

20 0 June

July

August

September

October

November

Month

Fig 4.1 Total gain in weight of 5(five) fish species in site 1. It has been shown in fig. 4.1 that foli (Notopterus notopterus) displayed highest total gain in weight followed by taki (Channa punctatus) while the lowest total gain was represented by kholisha (Colisa faciatus). In site 2, foli (Notopterus notopterus) has displayed the maximum average increase (15.1 gm per month) in weight followed by taki (Channa punctatus) having 14 gm/month during study period. The minimum count on average gain in weight per month was exhibited by kholisha (Colisa faciatus) having 5.58 gm/month followed by tengra (Mystus tengra) having 7.88 gm. Moderate average growth in weight was found to be shown by punti (Puntius sarana) having 10.8 gm per month in site 2 (Table 3.2). Table 3.2 Average increase of weight during observation period in site 2.


Sl. no .

Fish species

Average weight of fish before recruitment (gm)

1

M. tengra

10.5

No of fish observe d in each month 10

2

P. sarana

15.2

10

0.4

22.1

10

0.5

26.9

10

0.3

9.8

10

0.1

C. punctatus N. notopterus C. faciatus

3 4 5

Average increase of weight during observation period (gm) June

July

August

September

October

November

Avg. weight gain (gm/month)

0.3

8.8 14. 2 16. 3 18. 8 8.5

12.7

10.2

8.6

6.7

7.88

16.8

11.9

11.5

9.8

10.8

24

17.4

13.5

12.1

14

22.4

17.7

16.6

14.5

15.1

8.8

7.7

6.1

2.3

5.58

Total growth in weight of 5(five) fish species in site 2 140 120 tengra

Weight (gm)

100

punti

80

taki

60

foli

40

kholisha

20 0 June

July

August

September

October

November

Month

Fig 4.2 Total gain in weight of 5(five) fish species in site 2. It has been displayed in fig. 4.2 that foli (Notopterus notopterus) displayed highest total gain in weight followed by taki (Channa punctatus) while the lowest total gain was represented by kholisha (Colisa faciatus). Table 3.3 Average increase of weight during observation period in site 3.

Sl. no .

Fish species

Average weight of fish before recruitment (gm)

1

M. tengra

10.5

No of fish observe d in each month 10

Average increase of weight during observation period (gm)

2

P. sarana

15.2

10

0.2

3

C. punctatus

22.1

10

0.4

June

July

August

September

October

November

Avg. weight gain (gm/month)

0.3

9.4 12. 2 16. 2

13.1

10.6

9.9

8.8

8.68

14.9

10

9.1

7.9

9.05

23.4

18.6

13.1

12.1

14


N. notopterus C. faciatus

4 5

26.9

10

0.3

17. 7

23.4

19.9

18.1

14.1

15.6

9.8

10

0.2

8.1

9.9

6.6

5.2

4

5.67

During the period of experiment, foli (Notopterus notopterus) has indicated the maximum average gain (15.6 cm per month) in weight in site 3 followed by taki (Channa punctatus) having 14 gm/month. The minimum count on average gain in weight per month was displayed by kholisha (Colisa faciatus) having 5.67 gm per month followed by tengra (Mystus tengra) 8.68 gm. In site 3, punti (Puntius sarana) exhibited moderate average gain in weight having 9.05 gm per month (Table 3.3).

Total growth in weight of 5(five) fish species in site 3 140 120 tengra

Weight (gm)

100

punti

80

taki

60

foli

40

kholisha

20 0 June

July

August

September

October

November

Month

Fig 4.3 Total gain in weight of 5(five) fish species in site 3. It is shown in fig. 4.3 that foli (Notopterus notopterus) displayed highest total gain in weight followed by taki (Channa punctatus) while the lowest total gain was represented by kholisha (Colisa faciatus). Table 4.1 Percentage (%) of survival rate during observation period in site 1. Sl. no . 1 2 3 4 5

Fish species

Total recruited Total survived Percentage (%) of individuals individuals survival rate

M. tengra P. sarana C. punctatus N. notopterus C. faciatus

50 50 50 50 50

42 20 41 32 21

84 40 82 64 42

During observation period, tengra (Mystus tengra) has shown the highest survival rate (84%) in site 1 followed by taki (Channa punctatus) 82%. The lowest count for survival rate was


exhibited by punti (Puntius sarana) having 40% followed by kholisha (Colisa faciatus) having 42%. In site 1, foli (Notopterus notopterus) indicated moderate survival rate having 64% (Table 4.1). Table 4.2 Percentage (%) of survival rate during observation period in site 2. Sl. no . 1 2 3 4 5

Fish species M. tengra P. sarana C. punctatus N. notopterus C. faciatus

Total recruited individuals 50 50

Total survived individuals 43 22

Percentage (%) of survival rate 86 44

50

39

78

50

33

66

50

21

42

In site 2, tengra (Mystus tengra) has displayed the maximum value for survival rate (86%) followed by taki (Channa punctatus) having 78% during the study period. The minimum survival rate was exhibited by kholisha (Colisa faciatus) having 42% followed by punti (Puntius sarana) having 44%. Moderate survival rate was shown by foli (Notopterus notopterus) having 66% in site 2 (Table 4.2). Table 4.3 Percentage (%) of survival rate during observation period in site 3. Sl. no. 1 2 3 4 5

Fish species M. tengra P. sarana C. punctatus N. notopterus C. faciatus

Total recruited individuals 50 50 50 50 50

Total survived individuals 43 23 40 37 24

Percentage (%) survival rate 86 46 80 74 48

of

During the period of experiment, tengra (Mystus tengra) has indicated the maximum value for survival rate (86%) in site 3 followed by taki (Channa punctatus) having 80%. The minimum count for survival rate value was displayed by punti (Puntius sarana) having 46% followed by kholisha (Colisa faciatus) having 48%. In site 3, foli (Notopterus notopterus) exhibited moderate survival rate having 74% (Table 4.3). Table 4.4 Average Percentage (%) of survival rate during observation period in all sites (site 1, 2 and 3). Percentage (%) of survival rate

Sl. no.

Fish species

1 2 3 4 5

M. tengra P. sarana C. punctatus N. notopterus C. faciatus

site 1

site 2

site 3

84 40 82 64 42

86 44 78 66 42

86 46 80 74 48

Avg. percentage (%) of survival rate 85.33 43.33 80 68 44


Overall, in all sites (site 1, site 2 and site 3), tengra (Mystus tengra) displayed the maximum value for survival rate (85.33%) followed by taki (Channa punctatus) having 80% during study period. The minimum count for survival rate was exhibited by punti (Puntius sarana) having 43.33% followed by kholisha (Colisa faciatus) having 44%. Moderate survival rate was showed by foli (Notopterus notopterus) having 68% (Table 4.4). Table 5.1 Percentage (%) of mortality during observation period in site 1. Sl. no. 1 2 3 4 5

Fish species M. tengra P. sarana C. punctatus N. notopterus C. faciatus

Total individuals 50 50 50 50 50

recruited

Total survived individuals 8 30 9 18 29

Percentage mortality 16 60 18 36 58

(%)

of

During observation period, punti (Puntius sarana) having shown the highest rate of mortality (60%) in site 1 followed by kholisha (Colisa faciatus) having 58%. The lowest mortality count was exhibited by tengra (Mystus tengra) having 16% followed by taki (Channa punctatus) having 18%. In site 1, foli (Notopterus notopterus) indicated moderate mortality value having 36% (Table 5.1). Table 5.2 Percentage (%) of mortality during observation period in site 2. Sl. no. 1 2 3 4 5

Fish species M. tengra P. sarana C. punctatus N. notopterus C. faciatus

Total individuals 50 50 50 50 50

recruited

Total survived individuals 7 28 11 17 29

Percentage mortality 14 56 22 34 58

(%)

of

In site 2, kholisha (Colisa faciatus) has displayed the maximum mortality rate having 58% followed by punti (Puntius sarana) having 56% during study period. The minimum mortality count was exhibited by tengra (Mystus tengra) having 14% followed by taki (Channa punctatus) having 22%. Moderate mortality rate was shown by foli (Notopterus notopterus) having 34% in site 2 (Table 5.2). Table 5.3 Percentage (%) of mortality during observation period in site 3. Sl. no. 1 2 3 4 5

Fish species M. tengra P. sarana C. punctatus N. notopterus C. faciatus

Total recruited individuals 50 50 50 50 50

Total survived individuals 7 27 10 13 26

Percentage mortality 14 54 20 26 52

(%)

of

During the period of experiment, punti (Puntius sarana) has indicated the highest mortality (54%) in site 3 followed by kholisha (Colisa faciatus) (52%). The minimum mortality rate was displayed by tengra (Mystus tengra) having 14% followed by taki (Channa punctatus)


having 20%. In site 3, foli (Notopterus notopterus) exhibited moderate mortality rate having 26% (Table 5.3). Table 5.4 Average percentage (%) of mortality during observation period in all sites (site 1, 2 and 3). Avg. percentage (%) of mortality 14.67 56.67 20 32 56

Percentage (%) of mortality

Sl. no.

Fish species

1 2 3 4 5

M. tengra P. sarana C. punctatus N. notopterus C. faciatus

site 1

site 2

site 3

16 60 18 36 58

14 56 22 34 58

14 54 20 26 52

Considering all sites (site 1, site 2 and site 3), it is evident that punti (Puntius sarana) displayed the maximum mortality rate (56.67%) followed by kholisha (Colisa faciatus) having 56% during study period. The minimum mortality rate was exhibited by tengra (Mystus tengra) having 14.67% followed by taki (Channa punctatus) having 20%. Moderate mortality rate was shown by foli (Notopterus notopterus) having 32% (Table 5.4). Table 6.1 Comparison of different population parameters of tengra (Mystus tengra) in site 1, 2 and 3. Sl. no. 1 2 3 4 5

Parameters Length Width Weight Survival rate Mortality

Average growth/ month

Avg. growth range/month

Unit

1.12 – 1.40 0.18 – 0.25 7.80 – 8.68

cm/month cm/month gm/month

site 1 1.12 0.18 7.8

site 2 1.4 0.22 7.88

site 3 1.15 0.25 8.68

84

86

86

84 – 86

%

16

14

14

14 - 16

%

tengra) were observed. The average growth in length of this selected fish species lies in between 1.12 cm/month to 1.40 cm/ month, while the growth in width stands in between 0.18 to 0.25 cm per month and the average weight gain per month was ranged from 7.80 gm to 8.68 gm. During observation, tengra showed a wide range of survival rate (84% - 86%) and it displayed lowest possible range of mortality (14% to 16%) in all sites (site 1, site 2 and site 3) (Table 6.1) Throughout the study period, different population parameters of tengra (Mystus

Table 6.2 Comparison of different population parameters of punti (Puntius sarana) in site 1, 2 and 3. Sl. no.

Parameters

1 2 3 4 5

Length Width Weight Survival rate Mortality

Average growth/ month site 1 0.9 0.35 10.6 40 60

site 2 0.83 0.33 10.8 44 56

site 3 0.85 0.13 9.05 46 54

Avg. growth range/month

Unit

0.83 – 0.90 0.13 – 0.33 9.05 – 10.8 40 – 46 54 – 60

cm/month cm/month gm/month % %


Throughout the experiment, several population parameters of punti (Puntius sarana) were identified. The average growth in length of this selected fish species was ranged in between 0.83 cm/month to 0.90 cm/ month, while the growth in width was ranged from 0.13 to 0.33 cm per month and the average weight gain in per month was found to be ranged in between 9.05 gm to 10.8 gm. During study period, punti showed a moderate range of survival rate (40% - 46%) and on the other hand, it also displayed an intermediate range of mortality (54% to 60%) in all sites (site 1, site 2 and site 3) (Table 6.2) Table 6.3 Comparison of different population parameters of taki (Channa punctatus) in site 1, 2 and 3. Sl. no.

Parameters

1 2 3 4 5

Length Width Weight Survival rate Mortality

Average growth/ month site 1 1.73 0.23 13.4 82 18

site 2 1.77 0.37 14 78 22

site 3 1.80 0.38 14 80 20

Avg. growth range/month

Unit

1.73 – 1.80 0.23 – 0.38 13.4 – 14 78 – 82 18 - 22

cm/month cm/month gm/month % %

Throughout the observation period, different population parameters of taki (Channa punctatus) were detected. The average growth in length of this selected fish species has been found to be in between 1.73 cm/month to 1.80 cm/ month, while the growth in width stood in between 0.23 to 0.38 cm per month and the average weight gain per month was ranged from 13.4 gm to 14 gm. Like tengra, taki also showed a wide range of survival rate (78% - 82%) and it displayed lowest possible range of mortality (18% to 22%) in all sites (site 1, site 2 and site 3) (Table 6.3) Table 6.4 Comparison of different population parameters of foli (Notopterus notopterus) in site 1, 2 and 3. Sl. no.

Parameters

1 2 3 4 5

Length Width Weight Survival rate Mortality

Average growth/ month Site 1 1.57 0.62 14.4 64 36

Site 2 1.78 0.78 15.1 66 34

Site 3 1.85 0.65 15.6 74 26

Avg. growth range/month

Unit

1.57 – 1.85 0.62 – 0.78 14.4 – 15.6 64 – 74 26 – 36

cm/month cm/month gm/month % %

Throughout the experiment, several population parameters of foli (Notopterus notopterus) were identified. The average growth in length of this chosen fish species stood in between 1.57 cm/month to 1.85 cm/ month, while the growth in width was ranged from 0.62 to 0.78 cm per month and the average weight gain per month was ranged between 14.4 gm to 15.6 gm. During study period, foli showed high range of survival rate (64% - 74%) but it displayed, low range of mortality (26% to 36%) in all sites (site 1, site 2 and site 3) (Table 6.4). Table 6.5 Comparison of different population parameters of kholisha (Colisa faciatus) in site 1, 2 and 3.


Sl. no.

Parameters

1 2 3 4 5

Length Width Weight Survival rate Mortality

Average growth/ month Site 1 0.75 0.35 6.68 42 58

Site 2 0.67 0.15 5.58 42 58

Site 3 0.72 0.22 5.67 48 52

Avg. growth range/month

Unit

0.67 – 0.75 0.15 – 0.35 5.58 – 6.68 42 – 48 52 – 58

cm/month cm/month gm/month % %

Throughout the study period (from June 2011 to November 2011), different population parameters of kholisha (Colisa faciatus) were observed. The average growth in length of this selected fish species was ranged in between 0.67 cm/month to 0.75 cm/ month, while the growth in width stood in between 0.15 to 0.35 cm per month and the average weight gain per month was ranged from 5.58 gm to 6.68 gm. During observation kholisha showed a moderate range of survival rate (42% - 48%) and it also displayed moderate range of mortality (52% to 58%) in all sites (site 1, site 2 and site 3) (Table 6.5) Chapter V Discussion Martínez et al.(2011) did research on population parameters of the Pacific flagfin mojarra Eucinostomus currani (Perciformes: Gerreidae) in the Gulf of California and identified minimum lengths of 4.5 cm and the maximum length of 21.0 cm among wide variety of nontarget species of fish, crustaceans, and mollusks that are relatively unknown. They also concluded that survivals of those caught species were ensured because reproduction is indirectly protected. In the current study, the maximum length was represented by Foli (Notopterus notopterus) 16.1 cm in site 3 and the lowest length was represented by 6 cm by Kholisha (Colisa faciatus) in site 2. Tengra (Mystus tengra) showed the maximum average survivality value (85.33%) in all sites (site 1, site 2 and site 3) and the lowest count for survivality value shown by Punti (Puntius sarana) which was 43.33%. Karimzadeh (2011) studied on natural and fishing mortality and exploitation rate of common Kilka (Clupeonella cultriventris) in southeast part of the Caspian Sea (Babolsar). He obtained natural and fishing mortality up to 0.671 per year and 0.849 per year, respectively of selected species. The total mortality of common kilka has been estimated up to 1.52 per year. .He also estimated the annual survival rate of common kilka up to 0.218/year. In the current observation, the highest value for mortality was notified by Punti (Puntius saran) which was 56.67% (11.2 per year) while the lowest count for mortality was represented by Tengra (Mystus tengra) 14.67% (2.9 per year) and for both species, the mortality rate is too high comparison o the study of Karimzadeh. Arshad et al. (2010) observed growth, mortality and recruitment of the sergestid shrimps Lucifer intermedius, in Johor, Peninsular Malaysia and found extreme length of shrimp 10.42 mm. They also estimated natural and fishing mortality was 2.99 year and 2.33 year, respectively. According to the author, the maximum length was represented by Fali (Notopterus notopterus) 16.1 cm in site 3 and the lowest length was represented by 6cm by Kholisha (Colisa faciatus) in site 2. In case of mortality, current observation indicates that the highest value for mortality was notified by Punti (Puntius saran) which was 56.67% (11.2 per year) while the lowest count for mortality was represented by Tengra (Mystus tengra) 14.67%


(2.9 per year) and for both species, the mortality rate is too high comparison o the study of Arshad and his colleagues. Abowei and Davies (2009) did research on some population parameters of Clarotes Laticeps from the Fresh Water Reaches of Lower Nun River, Niger Delta Nigeria and found the largest specimen measured 60.1cm and weighed 492g and the natural mortality (M) value was 0.87; fishing mortality (F) value was 0.33. In the present experiment, the maximum length was represented by Fali (Notopterus notopterus) 16.1 cm in site 3 and the lowest length was represented by 6cm by Kholisha (Colisa faciatus) in site 2 and the largest value for weight represented by Fali (Notopterus notopterus) 120.4 gm (site 3) and on the other hand, the lowest count for weight represented by Kholisha (Colisa faciatus) 43.3 gm (site 2). Alaş and Akif (2007) investigated of some population parameters of the Tench (Tinca tinca L., 1758) Inhabiting Beyşehir Lake (Konya-Turkey) and identified that specimens ranged from 14.9 to 38.5 cm in fork length, and 48.5 to 967.10 g in weight. In the current observation, the maximum length was represented by Fali (Notopterus notopterus) 16.1 cm in site 3 and the lowest length was represented by 6cm by Kholisha (Colisa faciatus) in site 2 and the largest value for weight represented by Fali (Notopterus notopterus) 120.4 gm (site 3) and on the other hand, the lowest count for weight represented by Kholisha (Colisa faciatus) 43.3 gm (site 2). Silvestre and Garces (2004) measured population parameters and exploitation rate of 25 species of demersal fishes in Brunei Darussalam during 1989–1990. They found relatively high K (and low L∞) values, typical of short-lived tropical fishes, were obtained for most (22) of the species. Combined with the high natural rate (Z), (0.85–3.40) and natural fishing mortality rate, (M) (0.73–3.10) estimates, these results imply low annual survival and high turnover rates. In the present observation, the highest value for mortality was notified by Punti (Puntius saran) which was 56.67% (11.2 per year) while the lowest count for mortality was represented by Tengra (Mystus tengra) 14.67% (2.9 per year) and the current findings is similar to that of silvestre and Garces’s findings. Jayawardane et al., (2002) measured Population parameters of Penaeus indicus, Penaeidae of the artisanal shrimp fishery in the Negombo lagoon and the associated coastal ecosystem on the west coast of Sri Lanka. They calculated asymptotic length growth of selected fish species was 19.2 cm for males and 19.9 cm for females. The natural mortality coefficient was estimated at 1.73 per year. In the current observation, the maximum length was represented by Fali (Notopterus notopterus) 16.1 cm in site 3 and the lowest length was represented by 6cm by Kholisha (Colisa faciatus) in site 2 and the highest value for mortality was notified by Punti (Puntius saran) which was 56.67% (11.2 per year) while the lowest count for mortality was represented by Tengra (Mystus tengra) 14.67% (2.9 per year). In case for mortality value, both the findings are similar with each other. Devadoss (1998) did experiment on growth and population parameters of the spade nose shark, Scoliodon laticaudus from Calicut coast and he obtained average growth value for nose shark, which was 715 mm per year. He also observed that the average estimated annual catch was 14.4 tones at the existing mortality value of 0.73%. According to the author, the highest value for average growth in length was represented by Fali (Notopterus notopterus) which was 2220 mm per year (1.85 cm per month in site 3) which is higher than the findings of Devadoss and the lowest count for the average growth in length was shown by Kholisha (Colisa faciatus) 804 mm per year (0.67 cm per month in site 2) which is similar with that of


Devadoss’s findings. According to the current study, a total of 109.4kg fish was caught in the river of Shitalakhshya in 6(six) months i.e. annually 218.8 kg which very small in comparison with the observation of devadoss. In case of mortality, the highest value for mortality was notified by Punti (Puntius saran) which was 56.67% (11.2 per year) while the lowest count for mortality was represented by Tengra (Mystus tengra) 14.67% (2.9 per year) and in both cases (highest and lowest count of present study), the observations are higher than that of Devadoss’s findings. Miah et al. (1997) estimated the growth and mortality parameters of hilsa Tenualosa ilisha (Ham.) population in the Meghna river of Bangladesh and smallest length at first capture (L) of hilsa was 3.65 cm and the largest length was identified was 57 cm. They also observed Hilsa population is presumed to be suffering from natural and fishing mortality since the age at recruitment is affected by recruitment over fishing. The total mortality (Z) was 2.03 year and thus it was found that 13.13 % T. ilisha survives only in the Meghna river. In the present study, the maximum length was represented by Fali (Notopterus notopterus) 16.1 cm in site 3 and the lowest length was represented by 6cm by Kholisha (Colisa faciatus) in site 2. The highest value for mortality was notified by Punti (Puntius saran) which was 56.67% (11.2 per year) while the lowest count for mortality was represented by Tengra (Mystus tengra) 14.67% (2.9 per year) MacCali (1973) calculated the annual mortality rate for the northern anchovy, Engraulis mordm, is estimated to be 66.5% in southern California waters. According to the current study, the highest value for mortality was notified by Punti (Puntius sarana) which was 56.67% (11.2 per year) while the lowest count for mortality was represented by Tengra (Mystus tengra) 14.67% (2.9 per year). Comparing both studies, only highest mortality count of current study is similar to the findings of MacCali’s findings. Chapter VI Summary The experiment was conducted to identify population parameters of 5(five) indigenous fish species. Since Bangladesh is a country rich in biological heritage and fish plays a very important role in our day to day life, fish constitutes an essential and often irreplaceable staple food for the people of Bangladesh and the fisheries sector plays a vital role in the economy through employment generation, nutrition supply and poverty alleviation. Data on population dynamics of indigenous fish species in Bangladesh perspective is very scarce. What is more to be mentioned is that such study in riparian species is nearly unavailable. It is very important to assess population parameters of both floodplain and riparian species for the sake of base line data to be used in further applied research. The experiment was carried out in the Shitalakhshya river, Narayanganj, Bangladesh. The study was conducted for a period of six months starting from June, 2010 to November, 2010. A total 5 different fish species i.e., tengra (Mystus tengra), punti (Puntias sarana), taki (Channa punctatus), kholisha (Colisa faciatus) and foli (Notopterus notopterus) were recruited in the study area inside a 20m×20m square enclosed experimental zone to identify different parameters of the studied population. During observation period (from June, 2011 to November, 2011), taki (Channa punctatus) has shown the largest average growth (1.73 cm per month) in site 1 and in other sites (site 2 and site 3), foli (Notopterus notopterus) has displayed the maximum average growth (1.78 cm per month) in length in site 1 and (1.85 cm


per month) in length in site 3. On the other hand, the lowest count on average growth in length per month was exhibited by kholisha (Colisa faciatus) having 0.75 cm/month, 0.67 cm/month and 0.72 cm/month in site 1, site 2 and site 3, respectively. foli (Notopterus notopterus) has shown the largest average growth value of 0.62 cm per month in width in site 1, 0.78 cm per month in site 2 and 0.65 cm per month in site 3. While the lowest count on average growth in width per month was exhibited by tengra (Mystus tengra) having 0.18 cm/month in site 1, kholisha (Colisa faciatus) 0.15 cm/month in site 2 and tengra (Mystus tengra) 0.13 cm/month in site 3. During observation period, foli (Notopterus notopterus) has shown the largest average growth 14.4 gm per month in weight in site 1, 15.1 gm per month in site 2 and 15.6 gm per month in site 3. While, the lowest average growth in weight per month was exhibited by kholisha (Colisa faciatus) 6.68 gm/month in site 1, 5.58 gm/month in site 2 and 5.67 gm per month in site 3. In overall, in all sites (site 1, site 2 and site 3), tengra (Mystus tengra) displayed the maximum value for survivality (85.33%) and the minimum count for survivality was exhibited by punti (Puntius sarana) 43.33%. On the other hand, punti (Puntius sarana) displayed the maximum value for mortality (56.67%) and The minimum count for survivality was exhibited by tengra (Mystus tengra) 14.67%. The present study was a preliminary research work to find out the average growth in length, weight and width and to monitor survival and mortality rate of selected 5(five) indigenous fish species of Shitalakhshya river and the obtained data could have been more authentic if the water quality, physical and chemical parameters etc. could have been evaluated. This baseline information will help researchers to do more applied research in the same study area or other rivers to enlighten fish population parameter data in Bangladesh perspective.


Study on population parameters of 5(five) indigenous fish species in the Shitalakhshya river