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A Comparison of Silver Carp ( Hypopthalmichthys molitrix ) by bim75537

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									A Comparison of Silver Carp (Hypopthalmichthys molitrix) Hatchery Strains

                                and the role of

           Silver Carp on Livelihoods in Northwest Bangladesh




                              Anthony O Shafer




                           Institute of Aquaculture
                            University of Stirling
                              Stirling FK9 4LD
                              Stirling, Scotland




         Dissertation submitted in partial fulfillment of the degree of
                   Master of Science in Aquaculture at the
                            University of Stirling

                                  June, 2000
ACKNOWLEDGEMENTS

I would like to thank every one who assisted me with the thesis. Firstly to my supervisor

Dr. David Little for his valuable suggestion during the experiment and revision of the

writing. I would also like to thank Paul Bulcock with his help and suggestion and

Malcolm Beveridge for his help while I was in Bangladesh.

To all the NFEP-2 staff in Bangladesh. Thank you for all your help, assistance and

hospitality during my stay. To the project director, for allowing me to carry out my

research at the hatchery. Special thanks to Topan Dar and Mezzain Rahman for their

friendship and assistance in the hatchery and hapa construction. To A.Z.M Chowdhury

and Gazze for your assistance in the questionnaires. To Nagas and Purvis for their

friendship, hospitality, and assistance. To Nick Mardall and Don Griffiths for their

hospitality and help.

Other members of the project staff that I would like to thank are: Mehrul, Faruque,

Bilash, Mahmudu, Habiba, Sultana, Bepul, and special thanks to Babul, Mokbul, Ojean.

I like to thank the drivers Idris and Alom. Thank you very much for your hospitality and

friendship during the stay.

I would like to thank my parents for the financial help and the support they have given

me.




CONTENTS                                                                      PAGE

Acknowledgements                                                                     i

Table of Contents                                                                    ii

List of figures                                                                      vi
List of Tables                                                      viii

Abstract                                                            x

1. Introduction                                                     1

1.1 General Background on Bangladesh                                1

1.2 Resources and the Economy                                       2

1.3 Agriculture in Bangladesh                                       2

1.4 Aquaculture in Bangladesh                                       4

1.4.1 Role of Fisheries in the National Economy                     4

1.5 Northwest Fisheries Extension Project, Second Phase (NFEP -2)   6

1.6 Constraints to Aquaculture                                      8

1.7 Aquaculture Production Potential                                8

1.7.1 Fish Species in Bangladesh                                    9

1.7.2 Nutrition Related to Fish in Bangladesh                       9

1.7.3 The Fish – Seed Trading Network in NW Bangladesh              10

1.8 The Perceived Quality of Seed                                   12

1.9    Objectives                                                   15

2     Material and Methods                                          18

2.1 Experimental fish                                               18

2.1.2 Stocking of Broodstock                                        18

2.2 Experimental procedure                                          22

2.2.1 Feeding                                                       24

2.2.2 Hapa construction                                             24

2.2.3 Pre-stocking of hapas and simulated transfer bag              25
2.2.4 Commercial hatcheries and stocking of simulated transfer bag              25

2.2.5 Treatments                                                                26

2.2.5 Stocking                                                                  26

2.2.6 Data Analysis                                                             27

2.3 Questionnaires                                                              27

3 Results                                                                       28

3.1 Reproductive performance in incubators                                      28

3.2 Analysis of Hapa trial                                                      31

3.3 Results of social survey questionnaires                                     32

3.3.1 The level of experience of nursers interviewed                            32

3.3.2 Species of fish cultured by nursers in relation to the species produced   32

3.3.3 Species of fish considered the least problem to nurse                     34

3.3.4 The reason why nursers perceive some species as being least problem       34
to nurse and also comprise a large proportion of their production

3.3.5 Assessment of hatchling quality by nursers                                34

3.3.6 Species that are considered by nursers to have the best survival rate     35

3.4 Results Traders Questionnaire                                               36

3.4.1 The level of experience of traders interviewed                            36

3.4.2 The fish species considered by traders to make up a large proportion      36
of fish trade and why

3.4.3 Fish species considered by trader the best for transferring and why       37

3.4.4 Indicators used to assess hatchling quality by traders                    38


3.4.6 Assessment of silver carp quality in the past five years by traders       39
with over five years experience
3.5 Questionnaire Results for Male Aggregate Workers                      39

3.5.2 Male aggregate worker fish purchasing results                       42

3.5.3 The percent of species most frequently bought buy                   42
male aggregate workers

3.5.4 Prices of the most frequently purchased table fish by male          42
aggregate workers

3.5.5 The species that are consider by male aggregate workers to be       43
the most available in markets

3.5.6 The percent of species most frequently bought in the                44
household of female road builders

3.5.7 Prices of the most frequently purchased table fish by female        44
road builders

3.5.8 The species that are consider by female road builders to            45
be the most available in markets

3.6 Market Survey Results                                                 46

3.6.1 The proportion of species observed at Dinajpur market in            46
relation to the most quantities observed

3.6.2 The species retailers sell the most quantities at Dinajpur market   47

3.6.3 The average price in taka/kg in Dinajpur market of species          47
by weight per kilogram

4 DISCUSSION                                                              49

4.1 Hatchery trials                                                       49

4.1.2 Commercial Hatcheries                                               51

4.2.1 Hapa trial                                                          52

4.3 The assessment of the importance of silver carp to the                55
 livelihoods to the people of Northwest Bangladesh


4.3.1 Nursers                                                             55
4.4.1 Traders                            58

4.5.1 Consumers                          60

4.6.1 Markets                            63


5.1 CONCLUSION                           63


5.2.1 Strain comparison trial            64

6.1 Bibliography                         66


7.1 Appendix                             69

7.1.1 Test Questionnaire for Nursers     69

7.1.2 Filled Questionnaire for Traders   70

7.1.3 Blank Form for Market Sampling     71
FIGURES                                                                    PAGE

Figure 1.5.1 Map of NFEP Command Area                                       7

Figure 2.2.1 Flow Chart of Protocol of Experiment One                       19

Figure 2.2.2 Flow Chart of Protocol of Experiment Two                       20

Figure 2.2.3 Flow Chart of Protocol is the same for Experiment One          21
and Experiment Two

Figure 3.3.1 The level of experience of nursers interviewed                 32

Figure 3.3.2 Species of fish cultured by nursers in relation to the         33
species produced

Figure 3.3.3 Species of fish considered the least problem to nurse          33

Figure 3.3.5 Indicators used to assess hatchling quality by nursers         35

Figure 3.3.7 Fish species that are considered to have the best survival     35
rate during transfer from hatchery to nursery pond

Figure 3.4.1 The level of experience of traders interviewed                 36

Figure 3.4.2 The fish species considered by traders to make up a large      37
proportion of fish trade and why

Figure 3.4.5 Indicators used to assess hatchling quality by nursers         38

Figure 3.4.7 Assessment of silver carp quality in the past five years by    39
traders with over five years experience

Figure 3.5.3 The percent of species most frequently bought buy male         42
aggregate workers

Figure 3.5.5 The species that are consider by male aggregate                43
workers to be the most available in markets

Figure 3.5.6 The percent of species most frequently bought in the           44
household of female road builders
Figure 3.5.8 The species that are consider by female road builders to             45
be the most available in markets


Figure 3.6.1 The proportion of species observed at Dinajpur market                47
in relation to the most quantities observed




TABLES                                                                    PAGES

Table 1 A simplified outline of the main actors, produce and                11
locations in the fish production and trading network

Table 2.1 The mean weight and size of silver carp stocked in                18
broodstock pond

Table 2.2.1 The seven treatments used for the hapa experiment               26

Table 3.1 Reproductive traits of two silver carp strains                    29

Table 3.1.1 Size comparison of three day old post hatch NFEP                30
New and Old hatchery strain and commercial hatcheries

Table 3.1.2 Silver Carp, survival, weigh, length and production             30
from 20 day post hatching

Table 3.1.3 Gain in fork length in Silver Carp from 20 days post            30
Stocking

Table 3.3.4 The reason why nursers perceive the following species           34
as being le ast problem to nurse and also comprise a large proportion
of their production

Table 3.4.3 Fish species considered by trader the best for transferring     38
and why

Table 3.5.1 Background information on Male aggregate                        41
workers/ Female road builders

Table 3.5.4a The average price in taka per kilogram of the most          43
frequently purchased table fish by male aggregate workers

Table 3.5.4b Current currency in Taka                                    43

Table 3.5.7 The average price in taka per kilogram of the most           45
frequently purchased fish in female road builder households.


Table 3.6.3 The average price in taka/kg in Dinajpur market of species   48
By weight per kilogram

Table 4.1.2 Background information of commercial hatcheries used         51
for the hapa trial

Table 4.2.1 A summary of the amount of fingerlings produced for          57
1k of hatchling used by nursers, and the survival rates for 1994
and 1995

Table 4.3.1 The number and percent composition of fry and                59
fingerlings of silver carp and rui/mrigel/catla entering Parbatipur
Railway Station for 1993 to 1996

Table 4.4.1 Sums of quantity in kg of table fish at                      62
Rangpur market survey done in 1997
ABSTRACT


Questionnaires were used to determine the impact that silver carp (Hypopthalmichthys
molitrix) has on the livelihoods of people living in Northwest Bangladesh. Strain and
hatchery comparison trials were conducted to assess the current performance of silver
carp being used in aquaculture in the northwest. The comparison trials were conducted at
the Northwest Fisheries Extension Project (NFEP), Parbatipur, Dinajpur Hatchery, with
two strains of silver carp being investigated. The old strain (OS) was acquired from the
existing stocks at the NFEP hatchery. The new strain (NS) was obtained from imported
pure wild riverine fingerlings from the Yangzte River China in June 1994. Broodstock
from each strain were stocked together in earthen ponds for six months. They were then
spawned and seed production, fertilization rates, hatchability rates, and larvae survival
were determined.
Results indicate that the only significant difference between the strains was hatchability
rates and fork length of larvae, which NS had the highest values. Larvae from NS and
OS were then compared to three commercial hatcheries (CM-1,CM-2,CM-3) in a hapa-
base trial. A further trial was created to mimic the effects of the transfer conditions the
three commercial hatcheries larvae would experience before stocking into the hapas refer
to as simulated transfer of new strain, (STN) and simulated transfer of old strain, (STO).
Twenty day after stocking in hapas, survival, weight, length and total weight were
determined for the 7 treatments. A significant difference in survival rate was observed,
for STN, CM-2, CM-3 having greater survival rates than CM-1, STO, OS, and NS. The
results did not indicate a clear difference between the seven treatments.
The questionnaire survey ascertained that silver carp is a relatively important species to
the people of Northwest Bangladesh, because it is one of the least expensive and most
available cultured fish in the markets.
1. INTRODUCTION


1.1 General Background on Bangladesh


The world community has identified Bangladesh either by its rampant poverty, over

population, and tropical fertility. Among nations of significant size, Bangladesh probably

has the highest number of people in absolute poverty per square kilometer. It is also one

of the most densely populated areas in the world, with a population of 122.2 million

people in a land area of 55,598 square miles. About a third of its population suffers from

moderate to severe starvation during much of the year, and nearly close to another third

of the population have an inadequate intake of calories during significant parts of the

year. This persistent poverty within Bangladesh is often attributed to its limited resources

for its growing population, but, it has also been suggested that it is not the lack of

resources but the lack of governance of resources that is responsible for the persistence of

poverty.



Banglade sh gained independence in 1971, but despite the long struggle for democracy,

the people of the country was politically oppressed at least until 1991, until the

Bangladesh Nationalist Party (BNP) won its elections. Despite the fact that long absence

of political stability tends to threaten governance and in turn impair development and

poverty alleviation efforts, there are many non-government organizations (NGO’s) at

work in Bangladesh. Their aim is to help develop the country and alleviate poverty. The

Bangladesh Rural Advancement Committee (BRAC) is the largest of these NGO’s and
has targeted the landless, marginal farmers, and women, and has tried to improve the

livelihoods of these groups through aquaculture.



1.2 Resources and the Economy

Bangladesh is still heavily aid dependent and is currently receiving approximately $1.5

billion per annum ($12 per head). Bangladesh does not have any productive natural

mineral resource besides natural gas. Its industrial base is extremely narrow accounting

for only 13% of the Gross Domestic Product GDP and 6% of employment, with the

readymade garments industry and semi- intensive shrimp farming being the two major

exported items (BBS 1998). Shrimp farming earns an estimated US$225 million each

year, but is unsustainable due to environmental pollution and fishing methods, destroying

the natural spawning grounds of the shrimp. However both these exports have recently

taken off in the last decade due to the opening of the economy and easy access to the

global market. Conversely, jute, the main export crop, is diminishing in its importance,

due to the replacement of jute fiber with synthetic fiber on the global market and the

replacement of jute cultivation with the growing of rice. Tea and leather are traditional

but minor export crops that have been steadily contributing to the foreign exchange, but

only make up a small portion.



1.3 Agriculture in Bangladesh

Agriculture still remains the main component of the economy. However, its contribution

to the GDP has fallen over the years from 46% in 1987 to 37% in 1998, but it still

provides the most income and employment to currently 80% of the population (BBS,
1998). The main crops in Bangladesh are rice and jute, with other important crops being

tea, sugarcane, oilseeds, fruits, vegetables, spices, wheat, potatoes, tobacco and cotton

(NFEP-2, 2000). Rice makes up a large component of the Bengali diet with an average

per capita consumption of 153.4 kg per year (BBS, 1998), supplying an average per

capita consumption of 1,450 Kcal per day (NSP, 1998). In 1991 and 1992 Bangladesh

had produce a near self sufficient rice crop, but it will continue remaining an importer of

rice up to the year 2010. High Yield Variety (HYV) rice cultivation has been established

as a mono-crop regime, which has replaced other food crops with rice, which has lead to

a serious implication for food security and nutritional imbalance, especially for the poor

households. The irrigation practices and chemical input used for HYV cultivation also

has had an effect on depleting the capture fisheries. Additionally the change in cropping

pattern has had an impact on the employment and food intake of rural Bangladeshi’s

(Nabi, Datta, Chakrabarty, Begum, and Chaudhury, 1999).



Land can be considered as an important income-generating asset especially for

agriculture and aquaculture; therefore land ownership is closely linked to poverty.

Landless households are not only income poor, but they also lack education and access to

credit and other services, which prevent them from switching to non-farming occupations

(NSP, 1998). The average per capita of land is very low (0.25 acres) and the amount of

land is decreasing every decade with no scope for expansion.             The disparity in

landholding is also alarming, with only 10% of the rural households owning about 50

percent of the cultivable land and half of the rural population being completely landless.

The landless depend exclusively for their sustenance on wages they usually earn from
agriculture day labour and unskilled labour (NSP, 1998). A recent report from NSP

Nutritional Surveillance Project, Annual Report 1998 showed that the average male

landless agriculture earns 50Tk per day, which equates to just less than one US dollar.



1.4 Aquaculture in Banglades h

Bangladesh has vast resources of water. It has many ponds, haors (natural depressions),

baors (oxbow lakes), beels (swamps) and rivers. Approximately 34% of the country’s

surface area is flooded with nutrient-rich water for nearly six months of the year, supplied

by the seasonal flooding from the three major rivers Ganges, Brahmaputra and Meghna.

Inland water bodies can be highly productive and contribute 73% of the country’s total

fish production (14,920,000mt in 1997-98). The total inland water area of the country is

4.308m ha. Out of this 4.047 million ha are floodplains, 87,300 ha are brackish water

and 0.114 million ha are natural depressions including beels and haors. Beels and haors

produced 58,298 metric tons of fish during 1994-95. This represented 4.9% and 9.8% of

the total country and capture fishery production. About 1.36 million ponds in the country

cover a total area of 1.47 million ha, which makes up 5% of total surface are covered by

                                                l
perennial water bodies, but it is believed that ess than half of these perennial water

bodies are presently under any form of fish culture (World Bank, 1991).



1.4.1 Role of Fisheries in the National Economy

The contribution of fisheries to the economy of Bangladesh is substantial, particularly

with reference to food consumption, nutrition, employment and export.             Fisheries

contribute 4.7% to the national gross domestic product (GDP), 10 per cent of agricultural
GDP and 10% of the export earnings (BBS, 1998). The average annual rate of growth of

the fisheries sector over the years is 4.6%.          Fisheries sectors provide full-time

employment for 1.2 million professional fishermen, most of whom are landless, and 11

million part-time fisher folk, which is about 10% of the total population. Seasonal

fishing in flooded areas is a vital component to the marginal and landless household’s

subsistence activities. It is estimated that 8 per cent of the population depend upon

fishing as their principal livelihoods with 75 per cent of the population engaging in

subsistence fishing (New, Tacon, and Csavas, 1993).



Fish is a cheap source of animal protein and constitutes 70% of animal intake for the

population.    However there have been considerable disparities in fish consumption

between rich and poor households and this is believed to be widening (Gupta and Shah,

1992). A recent Northwest Fisheries Extension Project Baseline Survey in the Northwest

Bangladesh demonstrated this disparity when they found that the average total intake of

fish purchased from markets by relatively wealthily families (18 kg of market fish per

year) was more than double the intake of poor families (8 kg of market fish per year)

(Ali, 1998).



The availability of wild fish in Bangladesh is declining. Inland capture fisheries declined

from 63%(472,000Mt) of the total catch in 1983-84 to 50%(425,000Mt) in 1988-89. The

per capita consumption of fish fell from 11.7 kg in 1972 to 7.5 kg in 1988, although

recently increased slightly to 8.8kg per annum in 1995 (World Bank, 1991). There

previously existed greater opportunities for capture fisheries for the poor in rivers, lakes
and seasonally – flooded waterbodies. It has been reported that the average yield of

major carps from rivers has declined from 13.3 kg/ha/year to 4.6/kg/ha/year during the

period of 1970-80 (Nuruzzaman, 1990).         Several factors have since reduced the

availability of fish from inland capture fisheries. These include the steady decline in

aquatic resources from increasing population, flood control, drainage and irrigation

interventions, and a decline in stocks from over fishing and environmental degradation.



The decline of capture fisheries has attracted considerable attention from government,

international donors and NGO’s in Bangladesh to promote aquaculture. Some of these

NGO’s have focused on aquaculture as a source of income generation for the poor or

marginal households, while others have looked at local waterbody access rights for

landless and poor women for both generating income and for household protein

consumption.



1.5 Northwest Fisheries Extension Project, Second Phase (NFEP -2)

The Northwest Fisheries Extension Project, Second Phase (NFEP-2) is jointly funded by

the Department of Fisheries (DoF) of the Government of Bangladesh and the Department

for Internationa l Development (DFID) of the United Kingdom. Since 1995, the main

goal of NFEP-2 has been to increase aquaculture production and incomes of poor farmers

in northwest Bangladesh.    The project area covers eight divisions in the northwest of

Bangladesh, which are Dinajpur, Gaibandha, Kurigram, Lalmonirhat, Nilphamari,

Panchagar, Rangpur and Thakurgaon (Figure 1.5.1). These eight divisions cover an area
MAP OF NFEP-2 PROJECT AREA
of 16,058 square kilometers with a population of 9.8 million people and 88,941 ponds.

The northwest region is considered one of the poorest areas in Bangladesh because of its

low agricultural and fish production as a result of low fertility soils, extremes of climate,

a six month dry period and sandy soils ( NFEP-2, 2000).


1.6 Constraints to Aquaculture

Despite all the attention towards fish culture in Bangladesh, commonly existing

aquaculture practices are not yet geared to meet the perceived shortfall in fish production.

One of the major constraints to the improvement of the level of fish culture is lack of

finance. As the farmers are the rural poor, they cannot afford to buy inputs that are not

currently part of their on-farm resource base. Such items include lime, organic and

inorganic fertilizers. Another major constraint to the development of fish culture is the

low level of technical knowledge concerning optimum stocking levels, species mix, pond

condition, disease prevention and fish feeding remain relatively low among many rural

people (Lewis, Wood, and Gregory, 1996). Some of these constraints are being addressed

by the NFEP-2 fry trader program, in which fry traders are trained to disseminate pond

culture knowledge to the farmers.



1.7 Aquaculture Production Potential

Currently the cultured ponds which make up 52% of the ponds in Bangladesh are

producing 1.16 t/ha/year and culturable ponds 31% of the ponds in Bangladesh are

producing .34 t/ha/year and derelict ponds comprising 17% of the ponds are producing

0.15 t/ha/year (New et al, 1992; Hoque 1995).           The present mean production is

.74t/ha/year in Bangladesh, which is low compared to China and India. Production has
been achieved as high as 3.5 t/ha/year with an improved system of multi-species carp

culture and low-quality supplementary feed. It has been suggested that if semi- intensive

aquaculture was applied the potential yield could be as high as (0 .7 –1.4mt) per year in

the existing water bodies alone.



1.7.1 Fish Species in Bangladesh

The major species under culture in Bangladesh are the Indian major carp, which is

                                       C
comprised of Rui (Labeo rohita), Catla ( atla catla ) and Mrigel (Cirrhinus mrigala).

Indian major carps together with Chinese carps contribute about 47 percent of the total

aquaculture production (New et al, 1992). The other main species being cultured are

Silver carp (Hypophthalmichthys molitrix), Silver barb (Puntius gonionotus), Common

carp (Cyprinus carpio), Mirror carp (Cyprinus carpio var. Specularis), Grass carp

(Ctenopharyngodon idella), Bighead carp (Aristichthys nobilis), African catfish (Clarias

gariepinus), and Tilapia (Oreochromis niloticus) and indigenous fish.



1.7.2 Nutrition Related to Fish in Bangladesh

Fish play an integral part of the culture and tradition in the life of the people of

Bangladesh. It is considered to be the cheapest source of animal protein, and provides 70

to 80% of the total animal protein intake for the resource-poor rural farmer. They are

also an important source of calcium, fats, and vitamins and make up 8% of the total

protein intake of the average Bengali diet. The average per capita per day caloric intake

is 2251 Kcal in rural areas and 2209 Kcal in the urban areas (BBS, 1998). This is slightly

under the FAO recommended intake of 2310 calories per day. The average per capita
daily protein intake is 64 gm in rural areas and 67 gm in urban areas (BBS, 1998). The

average fat content of the Bangladesh diet is 7 percent compared to the FAO

recommended intake of 20-30 percent (Ali, 1998).            Therefore, the promotion of

aquaculture has the potential to increase the availability of fish, which can maintain or

improve its affordability to the landless and the marginal poor.



1.7.3 The Fish – Seed Trading Network in NW Bangladesh

The typical production cycle in Bangladeshi aquaculture follows a simple pattern. Fish

seed, also known as hatchlings, are collected either from the wild in rivers or obtained

from government or private hatcheries, where spawning is induced under artificial

conditions. These hatchlings are then placed in nursery ponds, where they grow within a

few days into fry and within a few weeks into fingerlings, which are several inches in

length. The availability of fingerlings at the farmer’s pond side is dependent on some

kind of transportation. There is a well-established fish seed transportation network in the

Northwest part of Bangladesh (Lewis, Gregory, and Wood, 1993). The main fingerling

market in the Northwest Bangladesh is located at night during the summer on the

platforms of Parbatipur railway station, which forms the main rail junction for the

Northwest and has been playing a vital role as a seed-trading center since 1930. Fish

seed traders in the Northwest often procure fingerling from sources as far away a Jessore,

Bogra and Rajshahi. Between 200 to 100 million fingerlings are usually traded there

every year (Chowdhury and Mardall, 1997). There are two main types of fish-seed

traders khuchra beparis, who transport fingerlings from nursery ponds distances of up to

100 miles by train for sale directly to pond-owners, or pikars, who transport large amount
of seed from the nursery ponds to the commission agents (Lewis et al. 1993).

Commission agents also known as arotdars who buy seed from traders in specialized

markets such as the Parbatipur railway station. Fry traders still prefer the traditional

methods of transportation of seed, which are namely patils (aluminum or earthen

containers) and oil drums.             Seed can also be transported in polyethylene bags with

oxygen but the most preferred way is the patils, because it is relatively cheap, simple and

materials are locally available.

Once pond-owners purchase fingerlings they are stocked into larger ponds where they

mature into food fish in between eight months and two years, depending on pond

management and species. Some of the fish may be consumed at home or distributed

through urban and rural markets for consumption. They can also be kept on as brood

stock and sold to hatcheries, where they are spawned to produce more hatchlings to start

the cycle again. Through out this process from hatchling source to food fish in ponds

there is an elaborate network of relationships between different actors linked by a series

of transactions (Table 1) (Lewis et al. 1993).

Table 1. A simplified outline of the main actors, produce and lo cations in the fish
production and trading network (After Lewis et al. 1993)
   Actors                                       Produce              Location

   Collectors                                   Hatchlings           River/hatcheries
   Fishermen
   Middlemen

   N u r s e r y p o n d-o w n e r s            Fingerlings          Nursery ponds
   Fingerling traders
   Wholesalers
   Local fingerling traders

   V i l l a g e p o n d -o w n e r s           Food fish            Food fish ponds
   C o m m e r cial pond operators
   Fishermen

   Food fish traders                                                 Rural and urban markets
Currently the falling per capita consumption of fish and the declining availability of wild

fish seed which the aquaculture sector has traditionally depended upon to stock their

ponds, has put a greater reliance on cultured fish to meet this demand by both rural and

urban people. For aquaculture to meet this demand fish seed has to be readily available.

Currently there are over 700 hatcheries established in the private and public sectors in

Bangladesh (Ali, 1998). These hatcheries have been breeding 13 endemic and 13 exotic

fish species and contributing more than 98% (about 117 000kg) of the total hatchling

production, the rest coming from natural river sources (Hussain and Mazid, 1999).



1.8 The Perceived Quality of Seed

At present fish seed is currently abundant and cheap, but there has been an emerging

concern that it is deteriorating in quality. Fish seed that has a poor growth performance

and suffers high mortalities undermines the attempt to promote fish farming to new

adopters and raises the cost of production, which in turns raises the price to the consumer

making fish less available to the poor.



The poor performance observed in pond stock fish can be due to sub-optimal seed quality

or inadequate management by the farmer after stocking.         If there is a decrease in

performance in seed it could be genetic or management related. There are several stages

and actors that are involved in the seed production and trading system, so this reduction

in quality could occur at any stage. It also could be genetic, due to inbreeding and

negative selection. This too can lead to a reduction in growth and reproductive

performance (Kincaid, 1983).
The rapid expansion of carp culture in Bangladesh has taken place as the controlled

breeding and spawning of fish using the hypophysation technique has spread to the

private sector. Hypophysation has allowed the life cycle of silver and other riverine carps

being culture under static pond water conditions to be controlled. The closing of the life

cycle requires little to no input of outside founder stock. Most hatcheries in Bangladesh

rear their own broodstock and usually do not recruit broodstock from other farms or

obtain them from natural sources. A study done by NFEP-2 showed that several districts

in the Northwest region Thakurgaon, Panchagar, and Noagaon reared their own

broodstock with no input of outside founder stock. Only one district Gaibandha collected

some of its broodstock form the wild (Gaghat and Brahmaputra river). It can therefore

can be considered that each hatchery is an isolated, self- sustaining genetically closed unit

(Eknath and Doyle, 1990).       Doyle (1983) has suggested that in genetically closed

systems, the potential selective pressures exerted on small cultured population by various

farm management practices such as choice of founder stock, the number of breeders

maintained, the method of replenishing broodstock, stocking density and feeding regime,

can result in indirect or negative selection, inbreeding and genetic drift. It has been well

established in the scientific literature that inbreeding affects traits associated with

reproductive and physiological performance (Falconer, 1981; Kincaid 1983).



It has been suggested that in India fish hatcheries there have been a substantial variation

in growth and reproductive performance of aquaculture stocks. Typically, what has been

observed is a continue decline in the rate of fertilization, hatching, and fry survival.

There is also has been a decrease in milt volume in silver carp and grass carp. Eknath
and Doyle (1985, 1990) have related this decrease in performance from the inadvertent

breeding of slow-growing and late maturing individuals.



Hussain and Mazid (1997) showed that majority of hatcheries operators located in

Jessore, Comilla and Mymensingh lacked knowledge of simple broodstock management

practices and did not follow any principles or guidelines in selecting adequate sized

breeders, injecting hypophysation dosage and mating unrelated male and female

spawners.



Not having a good understanding of appropriate hatchery procedures increases the

inadvertent chance of negative selection due to the use of fish of undesirable size and

leftover broodstock, and the mating of breeders’ generation after generation from closely

related individuals. Inadvertent inbreeding in Bangladesh has in recent years led to a

reduction in growth and reproductive performance, an increased incidence of diseases

and morphological deformities and mortality of hatchery produced seeds of carps and

silver barb (Hussain and Mazid, 1999).

There has been a widespread concern that silver carp stocks have been deteriorating in

Bangladesh through inbreeding and hybridization with other fish species. This has led to

a reduction in both growth and reproductive performance. Silver carp is an economically

important species in Bangladesh, especially in the Northwest. A hatchling production

survey conducted by NFEP –2 in the Northwest region of Bangladesh found that silver

carp was the species most produced by hatcheries during 1995 (Morrice, 1997). Silver

carp is also the second most abundant seed being traded at Parbatipur railway station after
the Indian major carps (Chowdhury and Mardall, 1998). Silver carp fingerling produced

from nurseries in the NFEP –2 command area comprise 42 percent of the total production

(Morrice, 1997). A market survey showed that silver carp was the most represented

species in three regional markets in the Northwest (Thankurgaon, Dinajpur and Rangpur)

during 1997 to 1998 (NFEP-2, market data). Silver carp generally has the lowest market

price of the major cultured species (Morrice 1997).



1.9 Objectives

The aim of the study is to not only assess the importance of silver carp to people of NW

Bangladesh, but also to determine the quality of silver carp currently being used in

aquaculture in NW Bangladesh. The combination of social surveys and technical on-

farm trials will reveal a more complete “holistic” picture of the potential role silver carps

might have in poverty alleviation in NW Bangladesh.



Questionnaires were used to determine the importance of silver carp to the livelihoods of

people in northwest Bangladesh and also the perceived quality of silver carp.           This

focused on interviewing nursers, traders, male and female unskilled labourers and market

sampling.



Technical Trials

Trial 1

Compare the performance in hatchery incubators of hatchlings from existing silver carp

stocks at the NFEP-2 farm at Parbatipur (old strain, OS) with the hatchling from imported
pure Yangtze River silver carp (new strain, NS), by observing fertilization rates, hatching

rates, and larvae survival and growth.

The objective of the trial is to determine if there is any difference in performance

between the new and old strain during early rearing in the hatchery.



Trial 2

Compare the performance in hapas of larvae from the old strain with the larvae from the

new strain, by determining percent survival, length, weight, and production at the end of

20 days.

The objective of the trial is to determine if there is any difference in performance

between the new and old strain during the nursing period in hapas.



Trial 3

Compare the performance in hapas of larvae from the old and new strain with an induced

period of stress (simulated transfer) before stocking in hapas with larvae transported from

three commercial hatcheries, by determining the percent survival, length, weight, and

production at the end of 20 days.

The objective of the trial was to determine if government hatchery larvae perform better

than larvae from commercial hatcheries, which might be less knowledgeable of

broodstock management practices. Additionally, the performance of the new strain under

conditions of simulated stress compared to the old strain was evaluated.
Chapter 2 Material and Methods

2.1 Origin and maintenance of broodstock

For the growth comparison trial, conducted at the Northwest Fisheries Extension Project

(NFEP), Parbatipur, Dinajpur Hatchery, two strains of silver carp (Hypopthalmichthys

molitrix) were investigated. The old strain (OS) was acquired from the existing stocks at

the hatchery.     The new strain (NS) was obtained from imported pure wild riverine

fingerlings from a sanctuary found in the northern reaches of the Yangzte River China in

June 1994. The new strain was tagged, isolated from the old strain and grown-on as

broodstock.

On October 15 th 1999, one 1600m2 decimal earthen pond was stocked with a total of 80

fish (twenty pairs of new stra in and twenty pairs of old strain silver carp) at a density of 2

fish 40m-2 . Table 2.1 summarizes the mean weight and size of the old and new silver

carp.

Table 2.1 The mean weight and size of silver carp stocked in a broodstock pond at NFEP

Strain        Weight (kg)   Size (cm)

New Strain    1.60          48.20
              (0.30)        (2.66)

Old Strain   1.40         47.10
             (0.28)       (2.83)
Standard errors of the means are in parentheses.

The earthen pond was fertilized monthly using 100gm urea 40m-2 and 50gm TSP 40m-2 .

and in addition was occasionally fertilized with cow manure to promote detritus. The

broodstock feed was comprised of a dry ration of 40% mustard oil cake and 60% rice

bran and fed at 1% of the stocked total biomass six times per week.
               10/15/1999                              2.2.1 Flow Chart
                                                       Experiment    one
               20 Pairs of NS + 20 Pairs of OS         Protocol
               Stocked in 40 decimal pond

               Experiment 1
               4 Commercial Hatchery in
               Adamdigi is contacted to
               coordinate hypothesiation and
               pick up of larvae on 7/4

               2/4/1999
               Hormonal induction
               5 Females NS + 5 Males NS
               5 Females OS + 5 Males OS

               3 Females NS + 3 Females OS
               Used for the comparison trial

1 Female NS    3/4/2000                                3 Males NS
               Fertilization
Eggs striped                                           Pooled semen

               5mls of pooled semen used to
               fertilize each female within a strain

               Fertilized eggs are divide into three
               equal parts than stocked
               in three separate incubators

               3 Females NS use 9 incubators
               3 Femal es OS use 9 incubators
               Total 18 incubators

2:30 PM        Percent Fertilization Determined



9:30 AM        4/4/2000
               Hatching Rate I Determined

4:00 PM        6/4/2000
               First Feed

11:00 AM       7/4/2000
               Total wet weight of larvae determined
               for each incubator


                   10/15/1999                                   Flow Chart 2.2.2
                   20 Pairs of NS + 20 Pairs of OS              Protocol for
                      Stocked in 40 decimal pond              Experiment Two

                      Experiment 2
                      20/4/2000
                      4 Commercial Hatchery in
                      Adamdigi is contacted to
                      coordinate hypothesiation and
                      pick up of larvae on 22/4

                      22/4/1999
                      Hormonal induction
                      5 Females NS + 5 Males NS
                      5 Females OS + 5 Males OS

                      3 Females NS + 3 Females OS
                      Used for the comparison trial

1 Female NS/OS        23/4/2000                               3 Males NS/OS
                      Fertilization
Eggs striped                                                  Pooled semen

                      5mls of pooled semen used to
                      fertilize each female within a strain

                      Total fertilized eggs from one
                      Female is stocked
                      in one separate incubators

                      3 Females NS use 3 incubators
                      3 Females OS use 3 incubators
                      Total 6 incubators

2:30 PM               Percent Fertilization Determined


9:30 AM               24/4/2000
                      Hatching Rate I Determined

          2:30 PM     Hatching Rate II Determined

4:00 PM               26/4/2000
                      First Feed

11:00 AM              27/4/2000
                      Total wet weight of larvae determined
                      for each incubator
                    Flow Chart 2.2.3
                    The Protocol is the same for
                    Experiment 1 and Experiment 2
11:00 AM           1 incubator out of each strain
                   is made to contain equal amounts
                   of larvae from the three females
                   which will be used to stock the hapas

12:00 PM           Simulated transfer bags are stocked
                   with 150 gm of each strain, bags are
                   filled with 1/4 water and 3/4 O2
                   bags are agitated for the next 4:30 hrs

                   7/4/2000 Stocking of Hapas
                   Experiment 1
                   27/4/2000 Stocking of Hapas
                   Experiment 2
                   Hapas stock in
                   random block design

                   Old strain (OS) and New Strain (NS)
                   are stocked in the hapas at 1000 fish
2:30 PM            per hapa which is determined
                   volumemetrically
                   4 replicas of each strain

                   Simulated transfer of new strain (STN)
                   Simulated transfer of old strain (STO)
                   are stocked in hapas at 1000 fish
                   per hapa which is determined
4:30 PM            volumemetrically
                   4 replicas of each strain

                   Three commercial hatchery larvae
                   arrive and are stocked at 1200 fish
                   per hapa which is determined
                   volumemetrically
5:00 PM            4 replicas of each strain
                   13/4/2000
                   Storm comes through and overturns
                   all hapas
                   Experiment 1 ends

                   17/5/2000
10:00 AM           Harvest of hapas
                   Experiment 2 ends
2.2 Experimental procedure
Background

The initial trial was conducted on April 2, 2000 and ended on April 13, 2000 due to a

storm that came through and overturned all the hapas, releasing the experimental fish.

The initial trial is referred to as experiment one (refer figure 2.2.1).           a
                                                                             The tri l was

reinitiated on April 22, 2000 and ended on May 17, 2000 and is referred to as experiment

two (refer figure 2.2.2). The hapa procedure is described in figure 2.2.3.

Selection of broodfish and induced breeding

Broodstock were netted in the morning and examined immediately at the pond side to

reduce the amount of stress.     Ripe female broodstock were then determined by the

presence of a swollen abdomen, soft post abdominal region and swollen genital papilla.

Ripe male broodstock were identified by the presence of free running milt when pressure

was applied to the abdomen. Following this the broodstock were scanned with a Trovan

transducer to determine the new strain from the old, because only the new strain were PIT

taged. Strains were placed in separate cotton sacks and transported to the hatchery and

placed in one concrete holding tank, consisting of six NS females, 5 NS males and 6 OS

females, 5 OS males.      Fish were first measured for fork length, scanned and weighed

then separated by sexes and placed into separated antechambers. The total weight of the

broodstock was needed to determine the amount of hormone required for hypophysation

later that evening. The primary injection of female broodstock occurred at 5:20 P.M. in

the evening. Final gamete maturation was induced intraperitoneally through injecting at

the base of the pectoral fin with human chorionic gonadotrophin hormone (HCG),

obtained from Funda Hormone Factory in Xiamen, China, administering 200IU Kg-1

using 0.4mls of injected solution per Kg of fish. The resolving dose was administered at
12:30 A.M. The hormone was whole acetate dried pituitary gland (PG), obtained from

Bangladesh. The homogenized PG resolving dose was also administered intraperitoneally

through the base of the pectoral fin with females received 5mg in 0.4ml of water kg-1 . In

contrast to the females, males received only a single dose of PG (2mg PG in 0.4ml of

water kg-1 of fish) at the time of the primary female dose.        Eight hours after the

resolving dose was given, new strain and old strain were differentiated by scanning with

the Trovan transponder, and stocked in different antechambers. Three males from each

strain were then checked for the presence of free running milt. The milt was then hand

stripped into a dried plastic weighing boat and the volume was determined volumetrically

by surgical syringe and recorded for each male. Pooled semen from three males was used

in doses of 5mL to fertilize the eggs from each female within a strain. Females were

gently dried and eggs stripped into a dry bowl to prevent any water contamination. Eggs

were then weighed on an analytical balance and a small sample was removed for a

subsequent egg quality determination. Milt was mixed into each batch of eggs using a

feather. A batch of fertilized eggs was divided into three equal weights and placed into

three separate 800L concrete incubators during the first experiment.       In the second

experiment incubators were limited so all the eggs from one female were placed in one

incubator s. Well water 26.5 o C flowed through the incubators. For the first experiment

(refer to table 2.2.1) each female occupied three incubators, 9 incubators per strain, and

18 in total; for the second experiment one female per incubator, 3 incubators per strain,

and 6 in total. The number of incubators and amount of eggs of each strain was recorded.

Three hours after fertilization fecundity and egg weight was determined by counting five

replicates of weighed batches of eggs. Fertilization rate was determined six and half
hours after fertilization volumetrically, based on counting the number of eggs fertilized

and the total number of eggs in three to five random 400mL samples. Egg hatchability

was determined 24 hours after fertilization volumetrically, based on counting the number

of larvae in three to five random 400mL samples over the total number of fertilized eggs.

Hatching survival was determined by measuring the total weight of wet fish five days

after fertilization over the weight of eggs initially stocked in each incubator.



2.2.1 Feeding

First feeding began when hatched fish absorbed their egg yolk sac. This occurred

approximately 52 hours after hatching at an incubator water temperature of 26.5         o C.


They were then fed an egg solution of a half boiled egg blended and strained and brought

to a final volume of 1 liter in water. Fish were fed at a rate of 1ml of egg solution g-1 of

fish hatched every three hours. The initial feeding regime in hapas consisted of egg
                                                             -1
solution twice a day once at 9:30 and again at 16:30 at 1ml g stocked for the first two

days then switched to rice bran husk at 5% body weight twice a day at 9:30 and 16:30.

Water temperature in hapas ranged from 28 – 33 o C.



2.2.2 Hapa construction

Hapas were placed in a 5600m2 earthen pond (borrow pit). Twenty-eight hapas were

constructed from fine mesh monofilament nylon cloth; each measuring 2m2 (2m x 1m)

sewn together with nylon thread and lined with nylon tape. Hapas were fixed to a

bamboo poles, by the corners at the top and bottom of hapa in the second experiment.

Cones were then placed on bamboo in order to deter crabs from climbing up the poles
and damaging the hapas. The base of the hapa was tied down above the cone. Extra

bamboo was tied down to the hapa bamboo frame and extended to the bank and was fixed

to a post for extra frame support in case of high winds and waves during the second trial.

During the first experiment the bottom of the hapa was not fixed to the bamboo post (it

was weighed down with bricks) and there was no extra support for the frame.



2.2.3 Pre-stocking of hapas and simulated transfer bag

Before hapas and simulated transfer bags were stocked, one incubator from each strain

was made to contain an equal number of larvae by weight from each female, so each

contributing female will be equally represented in the treatments. Each incubator was let

to settle for one hour before stocking of treatments.



2.2.4 Commercial hatcheries and stocking of simulated transfer bag

Four commercial hatcheries were first contacted in Adamdigi, one week prior of stocking

of hapas to coordinate hypophysation and stripping of females. Six hours before hapas

were stocked commercial fish were purchased and had a four to five hour deliver time in

a Land Rover to NFEP hatchery and were stocked at 150gm per bag. Five hours before

commercial hatchery larvae arrived the simulated transfer bags were assembled. Fish

were simulated transferred in a plastic bag filled with 1/4 water and containing ¾ pure

oxygen and agitated regularly (every 15 – 20 minutes). Simulated transferred bags were

stocked with 150 gm of fish and were placed inside the hatchery.         There was one

simulated transfer bag per strain.

2.2.5 Treatments
The trial composed of seven treatments (New strain, Old strain, New strain with 5 hr

simulated transfer time in bag, Old strain with 5 hr simulated transfer time in bag,

Commercial hatchery 1,2,3) with four replicates of each treatment (refer to table 2.2.1).

Fish were assigned to hapas laid out in a random blo ck design.

Table 2.2.1 The seven treatments used for the hapa experiment

Treatment 1           2        3                  4                 5           6           7

Description New strain Old strain Simulated transfer Simulated transfer Commercial Commercial Commercial
                                  of new strain      of old strain      hatchery 1 hatchery 2 hatchery 3

Replicates 4          4        4                  4                 4           4           4



2.2.5 Stocking

New strain simulated transferred, old strain simulated transferred, and new strain and old
                                                          -2
strain silver carp were stocked at a density of 500 fish m , while commercial hatchery

silver carp were stocked at a density of 600 fish m-2 . The densities for stocking the hapas

were initially determined volumetrically using the NFEP hatchery raised silver carp,

which were larger than the commercial hatchery silver carp, thus giving a higher stocking

density for the commercial hatchery silver carp. After the hapas were initially stocked

the density actually stocked for the commercial hatchery silver carp was later determined

volumetrically.

Silver carp were stocked in hapas for 20 days, at which point the trial was concluded and

weight, fork length, survival rate and production was determined.




2.2.6 Data Analysis
Strain and female differences were compared using a one-way analysis of variance

(ANOVA) followed by Tukey’s multiple comparison tests to determine significant

                            P
differences among the means ( <0.05). Percentage survival data was normalized if

required by transformation to angular degrees.



2.3 Questionnaires

Several structured questionnaires were used to ascertain the importance of silver carp to

the livelihoods of the people in northwest Bangladesh.        The questionnaires targeted

several different ‘actors’ in the fish production cycle. The ‘actors’ that were interviewed

were nursers n=15, fry traders n=15, male aggregate workers n=12, female aggregate

workers n=12, and retail market stalls n=15. The interview followed a checklist of open-

ended questions designed to gather qualitative data. All questionnaires were pretested in

the field and necessary changes made before the full-scale interviews were undertaken.

After several interviews with ‘actors’ a different location was used so respondents would

not standardize their answers to previous given answers.        Females were interviewed

separately away from the public with a female interpreter present, to prevent intimidation.




Trial 4

Compare the performance in hapas of larvae from the old and new strain with an induced

period of stress (simulated transfer) before stocking in hapas with larvae from the old and

new strain without a period of induced stress (no-simulated transfer).
The objective of the trial was to determine if there was a decline in performance from

larvae with simulated transfer than without simulated transfer. As there are many ‘actors’

in the seed trade the decline in seed quality might not only be associated with inbreeding

depression but could also be due to the many handlers in the seed trade trading networks.
CHAPTER 3 RESULTS
3.1 Reproductive performance in incubators

Within the hatchery, significant strain differences were seen in the following reproductive

trait1) female broodstock length, 2) hatching percentage 1 and 2 as described in Table

3.1. There was a significant difference between the strains in the female length used,

with the new strain being significantly larger than the old strain. There were no

differences in average relative fecundity (number of eggs produced per kilogram of fish)

between the strain in both experiments this proved to be insignificant.           Hatching

percentage 1in the new strain (80.58, 51.44%) in both experiments was significantly

higher than the old strain (42.46, 33.08%) respectively (ANOVA, F=11.140, P=0.001,

df=3). The same was noted for hatching percentage 2, the new strain (70.20%) was

significantly higher than the old strain (41.16%) (ANOVA, F=33.315, P=0.001, df=1).

In hatching percentages one and two in the second experiment, the percent hatching for

the new strain was almost double that of the old strain. The fertilization percentage in the

old strain in the second experiment ranked higher than the new strain, which was in

contrast to the first experiment where the new strain was higher than the old strain.

However, the differences among the four values are not significant (ANOVA, F=1.058,

P=0.371, df=3). There was a significant difference between strains for wet weight of

three-day post hatch fish/ total amount of egg stocked in incubator when analysed by

simple ANOVA but post-hoc analysis with Tukey’s test proved to be insignificant

(ANOVA, F=3.22, P=0.047, df=3).
Table 3.1 Reproductive traits of two silver carp strains

                                                 New Strain 2       Old Strain 2    New Strain1         Old Strain1

                                                           a               a               a                   a
Female weight (kg)                                   2.00             1.57             1.92               1.57
                                                     (0.12)           (0.03)           (0.30)             (0.23)

                                                           a               a               a                   a
Male weight (kg)                                     1.88             2.03             1.98               1.83
                                                     (0.07)           (0.12)           (0.13)             (0.08)

                                                           a                 b              a                  c
Female length (cm)                                  52.67             44.67           53.83               46.4
                                                    (1.33)            (0.33)          (1.30)              (1.22)

                                                           a                 a              a                  a
Male Length (cm)                                    48.83             49.33           48.50               48.17
                                                    (0.83)            (1.76)          (1.26)              (0.77)

                                                           a               a               a                   a
Weight of eggs (g)/g of body weight                  0.10             0.10             0.14               0.10
                                                     (0.01)           (0.01)           (0.02)             (0.03)

                                                           a               a               a                   a
Milt Volume (ml)                                     5.67             7.33             4.17               4.93
                                                     (0.17)           (2.33)           (1.23)             (0.64)

                                                           a                 a              a                  a
Percent Fertilization                               78.43             86.97           80.51               77.55
(6.5hr post fertilization)                          (0.04)            (0.02)          (0.04)              (0.03)

                                                           a                 b             bc                  bd
Hatching percentage 1                               80.58             42.46           51.44              33.08
(24hr post fertilization)                           (0.06)            (0.04)           (0.05)             (0.04)

                                                           a                 b
Hatching percentage 2                               70.20             41.16
(29hr post fertilization)                           (0.25)            (0.29)

                                                           a               a               a                   a
Wet weight of 3 day post hatch fish (gm)/            1.15             1.10             0.95               0.79
total amount of eggs stocked (gm)                    (0.10)           (0.11)           (0.07)             (0.08)

Values with different alphabetical superscript were significantly different from each other (P<0.05).
Standard errors of the means are in parentheses.
1
  Experiment 1
2
  Experiment 2


   Table 3.1.1 Mean fork length of three-day-old larvae for NFEP new and old

                        hatchery strain and commercial hatcheries
Description                  CM-1     CM-2      CM-3           NS       OS
                                 a            a            a             b            c
Fork length (mm)           6.46           6.37         6.32          7.21         6.95
                           (0.03)         (0.04)       (0.03)        (0.06)       (0.03)

                                                      -3
CM-1(Bai Bai Hatchery), CM-2 (Sagar Hatchery), CM (Star Matshya Khamar hatchery)
NS (New strain), OS (Old strain)
Values with different alphabetical superscript were significantly different from each other (P<0.05).
Standard errors of the means are in parentheses.

 Table 3.1.2 Mean survival, weight, length and production for silver carp from 20 days

Description                 CM-1          post
                                          CM-2 stocking in
                                                    CM-3           hapas
                                                                      STN         STO           NS             OS

                                 a             b            b               b           a            a              a
Survival %                 55.62         87.71        76.31          91.36       62.63        68.62          65.6
                           (0.05)        (0.05)       (0.05)         (0.03)      (0.02)       (0.05)         (0.04)

                                     a            b            a             a            a              a              a
Weight (gm)               0.0651         0.0346       0.0472        0.0499       0.0648       0.0605         0.0672
                           (0.01)         (0.00)       (0.00)        (0.01)       (0.00)       (0.00)         (0.01)

                                 a            b            a             a            a              a              a
Fork length (cm)           1.52           1.21         1.33          1.40         1.51        1.50           1.51
                           (0.06)         (0.03)       (0.05)        (0.04)       (0.04)      (0.03)         (0.06)

                  -2             a             a            a               a           a            a              a
Production (g m )          42.25         41.50        43.00          46.50       40.50        45.33          41.00
                           (1.32)        (0.96)       (2.88)         (4.35)      (2.06)       (3.53)         (1.29)

                                                      -3
CM-1(Bai Bai Hatchery), CM-2 (Sagar Hatchery), CM (Star Matshya Khamar hatchery)
STN (Simulated transfer new strain), STO (Simulated transfer old strain), NS (New strain), OS (Old strain)
Values with different alphabetical superscript were significantly different from each other (P<0.05).
Standard errors of the means are in parentheses.


Table 3.1.3 Mean fork length gain for silver carp from 20 days post stocking in hapas
Description                 CM-1          CM-2         CM-3          STN          STO           NS             OS


                                 a            b            a             a            a              a              a
Fork length gain (cm)      1.45            1.15        1.27          1.32         1.44        1.43           1.44
                           (0.06)         (0.04)       (0.05)        (0.04)       (0.04)      (0.03)         (0.06)

                                                      -3
CM-1(Bai Bai Hatchery), CM-2 (Sagar Hatchery), CM (Star Matshya Khamar hatchery)
STN (Simulated transfer new strain), STO (Simulated transfer old strain), NS (New strain), OS (Old strain)
Values with different alphabetical superscript were significantly different from each other (P<0.05).
Standard errors of the means are in parentheses.




The fork length of larvae before stocking in hapas is summarized in Table 3.1.1 The new

strain (7.21mm) was significantly greater in size than the old strain (6.95) followed by
CM-1 (6.46), CM-2 (6.37) and CM-3 (6.32mm).             Both new and old strains were

significantly different from the commercial hatchery fish (ANOVA, F=72.22, P=0.001,

df=4).


3.2 Analysis of Hapa trial

Table 3.1.2 summarizes the data obtained for the 20-day hapa trail, it can be seen that

there were significant differences in survival rate with STN (91.36%), CM-2 (87.71%),

and CM-3 (76.31%), having a significant higher survival rate compared to NS (68.62%),

OS (65.6%), and CM-1 (55.62%) (ANOVA, F=10.72, P=0.001, df=3).                  Statistical

analyses showed that CM-1 (.065g), STO (.065), NS (.061), OS (.067) had a significantly

higher mean weight than CM-2 (.0346g) (ANOVA, F=4.49, P=0.005, df=6). This same

ranking was also noted with respect to fork length where CM-2 was smaller in size

(1.21cm) compared to CM-1 (1.52), STO (1.51), NS (1.50), OS (1.51cm) (ANOVA,

F=6.235, P=0.001, df=6). ). For production STN (46.5) and NS (45.33gm-2 ) had the

highest mean value although there was no significant differences between the seven

treatments (ANOVA, F=.768, P=0.604, df=6).

Table 3.1.3 shows the mean fork length gain after 20 days of the trail period. Statistical

analyses revealed that CM-1 (1.45cm), STO (1.44cm), NS (1.43cm), OS(1.44cm) had a

significantly greater mean fork length than CM-2 (1.15cm) (ANOVA, F=6.03,

P=0.001,df=6)



3.3 Results of social survey questionnaires

3.3.1 The level of experience of nursers interviewed
Of the thirteen respondents surveyed the nursery questionnaire at NFEP hatchery, 4 (31

percent) had 1 to 5 years experience, 4 (31 percent) had 6 to 10 years experience, and 5

(38 percent) had over 10 years experience (refer to figure 3.3.1).




                      40
   % of respondents




                      30

                      20

                      10

                      0
                           1-5      6 - 10      > 10
                                    Years

Figure 3.3.1 The level of experience of nursers interviewed

3.3.2 Species of fish cultured by nursers in relation to the species produced

Responding to the question “what species did you nurse in your last production cycle and

what species makes up a large proportion of what is produced”, 14 (100 percent) nurse

silver carp and 12 (85.7 percent) replied it is the greatest proportion of fish cultured, 12 (

85.7 percent) nurse rui/mrigel and 10 (71 percent) replied it is the greatest proportion of

fish cultured, 8 (57 percent) nurse catla, 6 (43 percent) nurse grass carp, 11 (78 percent)

nurse shorputi and 2 (14 percent) replied it is the greatest proportion of fish cultured, 3

(21 percent) nurse mirror carp, 6 (43 percent) nurse bighead carp, and 4 ( 28 percent)

nurse common carp and 2 (14 percent) replied it is the greatest proportion of fish

cultured (refer to figure 3.3.2).
3.3.3 Species of fish considered the least problem to nurse
Respondents reported that silver carp was the least problem to nurse11 (79 percent)

followed by rui/mrigel, 2 (14 percent) shorputi, 2 (14 percent) common carp, and 1 (7

percent) respondent catla was easy to nurse (refer to figure 3.3.3).


           3.3.4   The reason why nursers perceive some species as being least problem to
nurse and also comprise a large proportion of their production

Of the fourteen respondents to the question why they considered some species the least

problem to nurse and which also ha ve the highest production, silver carp had the highest

number of responses 11 (79 percent) with demand receiving the most responses.

Rui/mrigel had the second highest response 9 (64 percent) as being easy to produce and

                                  or
has a high demand. The lowest was f shorputi and common carp with 2 (14 percent)

each (refer to table 3.3.4).

Table 3.3.4 The reason why nursers perceive the following species as being least
problem to nurse and also comprise a large proportion of their production

                   High
Species            survival    Demand   Fast growing Easy to produce Profit   Total Row %

Silver Carp             2         5           2              2                 11     79

Rui/Mrigel              1         3           2              3                 9      64

Shorputi                          1                                      1     2      14

Common Carp             1                                    1                 2      14




3.3.5 Assessment of hatchling quality by nursers

Of the fourteen respondents asked how they assess hatchling quality, 9 (65 percent)

reported that they assessed quality by how strong they swim against the current. 3 (21

percent) relies on the judgment of the hatchery manager. 1 (7 percent) answered quality
by colour and another 1 (7 percent) by tapping on the container and seeing the hatchlings

response (refer to figure 3.3.5).



                                                                     Strong swimmer/movement against
                                             7%                      the current
                                        7%
                                                                     Relies on hatchery manager

                                                                     colour
                               21%
                                                                     reacts to stimulus
                                                          65%




Figure 3.3.5 Indicators used to assess hatchling quality by nursers


3.3.6 Species that are considered by nursers to have the best survival rate

The eleven respondents to the question what species has the best survival rate during

transfer from hatchery to nursery pond, 8 (73 percent) rui/mrigel, 2 (18 percent) catla, 2

(18 percent) shorputi, 3 (27 percent) silver carp, and 1 (9 percent) common carp (refer to

figure 6). But overall it was suggested that silver carp had the lowest survival rate

compared to other major cultured species except for shorputi.



                      80
   % of respondents




                      70
                      60
                      50
                      40
                      30
                      20
                      10
                       0
                           Siver Carp        Rui/mrigal   Shorputi   Common Carp     Catla


Figure 3.3.7 Fish species that are considered to have the best survival rate during transfer from
hatchery to nursery pond
3.4 Results Traders Questionnaire


Trader Background

Traders were interviewed at the Parbatipur railway station in the evening. Two different

locations on the railway platform were used to interview the traders.          All traders

interviewed sell directly to the pond farmer and the average travel time to the farmer was

six hours traveling by using all forms of transportation (train, rickshaw, van, bike,) and

all transferred fish by patil.



3.4.1 The level of experience of traders interviewed

Of the fifteen respondents interviewed in the trader questionnaire at the Parbatipur

railway station, 9 (60 percent) had less than five years experience, 4 (27 percent) had six

to ten years experience and, 2 (13 percent) had over ten years experiences (refer figure

3.4.1).



               80
   % traders




               60
               40
               20
                0
                    1-5          6 - 10        >10
                                 years


Figure 3.4.1 The level of experience of traders interviewed

3.4.2 The fish species considered by traders to make up a large proportion of fish trade
and why

Of the fourteen respondents asked what is the most traded species and why are they

traded the most 11 (73 percent) responded shorputi because they are fast growing (3 ) and

demand is high (1). 14 (100 percent) for common carp because they are fast growing (2).
For rui/mrigel 11 (73 percent) because the demand is high (3) and are fast growing (1).

Bighead carp 4 (27 percent) was considered fast growing (1) by one respondent. Silver

carp on the other hand 14(100 percent) was traded the most because of it fast growth (6)

and high demand (5). Grass carp 6 (40 percent), catla 9 (60 percent) and African Catfish

1 (7 percent) had no response for why they were considered being traded the most.




                      250

                                                        Demand is high
                      200
   % of respondents




                                                        Fast Growing
                      150                               Percent response


                      100

                       50

                        0
                                                           tla
                                      uti




                                      al




                                      p
                                     rp




                                   arp
                                     rp




                                                                       h
                                                         Ca
                                   rig




                                    ar
                                  orp




                                                                   tfis
                                  Ca




                                  Ca


                                 rC


                               sC
                                i/m




                                                                 Ca
                               Sh


                              on




                              ad


                             lve
                            Ru




                            as
                            m




                                                               an
                           he


                           Si


                          Gr
                          m




                        Big




                                                            ric
                       Co




                                                          Af




Figure 3.4.2 The fish species considered by traders to make up a large proportion of the
fish trade and why


3.4.3 Fish species considered by trader the best for transferring and why

The fifteen traders asked what fingerling is the best to transfer and why the most response

was for common carp 14 (93 percent) because it is considered to be strong and hardy 10

(100 percent).              Rui/mirgel and shorputi had the lowest response receiving 1 (7 percent)

for transferring and 1 (10 percent) because it is strong hardy (refer to table 3.4.3).
Table 3.4.3 Fish species considered by trader the best for transferring and why

Species        Number of responses   Strong/Hardy Total
                     n = 15              n =10      t

Silver Carp                 2              1         3

Rui/Mrigel                  1              1         2

Shorputi                    2              1         3

Common Carp                14             10         24

Grass Carp                  4              3         7

Bighead Carp                2              2         4




3.4.4 Indicators used to assess hatchling quality by traders

Traders were asked how they judge seed quality, the majority replied by movement 11

(59 percent). 4 (26 percent) assessed quality by strength. They judge strength by putting

the fingerling in their hand and making a fist and see how hard it squirms. A small

percent judge quality by eye colour and size 1 (5 percent), 2 (10 percent) respectively

(refer to figure 3.4.4).



                           10%

                                                               Movement
                 26%                                           eye color
                                                               strength
                                       59%
                                                               size

                       5%




Figure 3.4.5 Indicators used to assess hatchling quality by nursers
3.4.6 Assessment of silver carp quality in the past five years by traders with over five
years experience

Traders with over five years experience were ask the quality of silver carp over the last

past five years. Most traders felt the quality of silver carp declined 8 (62 percent), while

some felt it increased 2 (25 percent) or remained the same 1 (13 percent)(refer to figure

3.4.7).




                    13%
                                   25%

                                                            Increase
                                                            decrease
                                                            same


                     62%




Figure 3.4.7 Assessment of silver carp quality in the past five years by traders with over
five years experience




3.5 Questionnaire Results for Male Aggregate Workers

Male Aggregate Workers Background


Male aggregate workers consisted of 12 males breaking bricks in various locations.

Brick breaking involved breaking bricks throughout most of the day, by squatting or

sitting on a brick and using a small hammer (head of the hammer the size of a 50 pence

coin) and breaking large pieces of brick into smaller pieces close to pebble size. Brick

breakers get paid by the amount of bricks they break or the amount of broken bricks they
produce. Breaking brick is considered an unskilled labour and pay could range from 63 –

50 taka per day for males, while females might receive 40 to 46.6 taka per day (NSP

1998). Male aggregate workers were interviewed in three different locations, Dinajpur,

Biral, and Rangpur. The youngest age was 12 and the oldest 70 (the average age was

41.5). The average days worked was 4.5 days a week and 80 percent of the respondents

were landless (refer to table 3.5.1).



Female Road Builder Background

Female road builders consisted of 12 females doing different types of road construction.

They were interviewed in two different locations but on the same road in Biral. The main

labour the women were performing was carrying crushed rocks in baskets (weight 7-

10kg) on top of their heads and walking 10 meters and dumping it on the road. Other

tasks involved filling the baskets or sweeping the road. The women were paid a set rate

by the day, approximately 40 taka (personal communication, NFEP-2). The youngest age

was 22 and the oldest was 50 and the average age was 32 (refer to table 3.5.1).
Table 3.5.1 Background information on Male aggregate workers/ Female road builders

                                                           Number of             Number of
Characteristics                                              Male                 Female
                                                          Respondents   Male    Respondents   Female

Average age                                                   12        41.50       12        32.00

Average family size                                           12        4.90        12         5.00

The percent that own land                                    3/12        25        9/12         75

The average amount of land owned (decimals)                   3          19         9          9.70

The percent landless (lives on government land)              9/12        75        3/12         25

Average worked days/week                                      12         4.5        12         4.40

The amount of times fish is consumed per year                 9         63.6        12        26.88

The amount of times chicken is consumed per year              9         5.16        12         3.90

The amount of times other meat is consumed per year           9         37.92       12         3.80

Who buys the fish in the family
Respondent                                                                         6/12         50
Husband                                                                            8/12         67

The percent of who consumes the most fish in the family
Respondent                                                                         1/12         8
Husband                                                                            5/12         42
Mother                                                                             1/12         8
Daughter                                                                           2/12         17
Son                                                                                2/12         17
Equal                                                                              1/12         8




3.5.2 Male aggregate worker fish purchasing results

3.5.3 The percent of species most frequently bought buy male aggregate workers
Of the twelve respondents the majority went to bazaars 10 (83 percent) and haats 5 (42

percent) to purchase fish. Of the twelve respondents asked what fish species is most

frequently bought, 2 (17 percent) mrigel, 2 (17 percent) rui, 7 (58 percent) silver carp, 1

(8 percent) catla, 1 (8 percent) tengra, 1 (8 percent) mola, 1 (8percent) darika, 5 (42

percent) shorputi, and 2 (17 percent) sharti (refer to figure 3.5.3).



                      70
                      60
   % of respondents




                      50
                      40
                      30
                      20
                      10
                      0
                                          i




                                                         ola




                                                                             ti
                                       Ru




                                                  ra
                                                  tla
                          el




                                                                            ti
                                                                    a
                                                                          Pu

                                                                          ar
                                        p




                                                                 rik
                       rig




                                                ng
                                               Ca
                                      ar




                                                        M




                                                                        Sh
                                                               Da
                      M



                                    rC




                                              Te
                                 lve
                               Si




Figure 3.5.3 The percent of species most frequently bought buy male aggregate workers


3.5.4 Prices of the most frequently purchased table fish by male aggregate workers

Male aggregate worker were asked what are the prices per kilogram of the most

frequently bought fish. The results are summarized in table 3.5.4. The most expensive

fish was rui 53 taka kg-1 the least expensive was darika 23 taka kg-1. Silver carp was the

least expensive of the cultured fish 30 taka kg-1 compared to rui. Price convergence is

listed in table 3.5.4a.



   Currency                        Taka
1 US dollar                         51
1 Pound                             72
Table 3.5.4a Taka/currency

Table 3.5.4b The average price in taka per kilogram of table fish purchased most
frequently by male aggregate workers

                                         -1
Species                       Taka kg

Silver Carp                         30
Rui                                 53
Mrigel                              47
Puti                                24
Sharti                              30
Tengra                              40
Mola                                36
Chanda                              30
Darika                              23

3.5.5 The species that are consider by male aggregate workers to be the most available in
markets

Of the twelve respondent that were asked which fish species is the most available in the

markets, 2 (17 percent) rui, 2 (17 percent) catla, 2 (17 percent ) ilish, 1 (8 percent), and 9

(75 percent) for silver carp (refer to figure 3.5.5).



                      80
   % of respondents




                      70
                      60
                      50
                      40
                      30
                      20
                      10
                       0
                           Silver        Boal   Rui   Catla   Ilish
                           Carp

Figure 3.5.5 The species that are consider by male aggregate workers to be the most
available in markets



Female road builder fish purchasing results
3.5.6 The percent of species most frequently bought in the household of female road
builders

Of the twelve respondent 10 (83 percent) purchase fish from bazaars, 3 (25 percent)
purchase from hats, and 3 (25 percent) from roadside market.

When asked what fish is bought most frequently 4 (33 percent) replied sharti, 9 (75
percent) puti, 1 (8 percent) ilish, 3 (25 percent) silver carp, 1 (8 percent) rui, and 1 (8
percent) bata (refer to figure 3.5.6).


             80
             70
             60
   percent




             50
             40
             30
             20
             10
              0
                  Rui   Bata   Sharti   Puti   Ilish   Silver
                                                       carp

Figure 3.5.6 The percent of species most frequently bought in the household of female
road builders


3.5.7 Prices of the most frequently purchased table fish by female road builders


Female road builders were asked what are the prices per kilogram of the most frequently

bought fish. The results are summarized in table 3.5.7. The most expensive fish was

chingri and ilish 80 taka kg-1 the least expensive was puti 19 taka kg-1 . Silver carp was

the least expensive of the cultured fish 38 taka kg-1 compared to rui 40 taka kg-1 .




Table 3.5.7 The average price in taka per kilogram of the most frequently purchased fish
in female road builder households.
                          -1
Species           Taka kg

Silver Carp          38
Rui                  40
Ilish                80
Chingri              80
Puti                 19
Sharti               26
Darika               12



3.5.8 The species that are considered by female road builders to be the most available in
markets

Of the twelve female respondent that were asked which fish species is the most available

in the markets, 2 (17 percent) rui, 1 (8 percent) catla, 2 (17 percent) puti, 1 (8 percent)

mola, 8 (67 percent) silver carp, and 1 (8 percent) sharti (refer to figure 3.5.8).




             80
             70
             60
   percent




             50
             40
             30
             20
             10
              0
                  Shol      Puti   Silver   Mola   Rui   Sharti   Catla
                                   carp

Figure 3.5.8 The species that are consider by female road builders to be the most
available in markets




3.6 Market Survey Results

Background
Dinajpur

Dinajpur has three fish markets, with Bahadur Bazaar being the largest. The two other

are Gudara Bazaar (Chalk ma rket) and Rail Bazaar that only opens on Thursday and

Sunday. Bahadur Bazaar was sampled close to the end of the peak hours of fish buying

which is early in the morning and evening.

Rangpur Pour (Municipal) Market

Is one of the biggest fish markets (in terms of supply and demand) in the northwest area

and was established in 1962. On average throughout the year it is estimated that 5,000

consumers visit the fish market daily. There are 10 smaller markets within Rangpur,

which are supplied from the Pour Market (NFEP, market data). Only a few retailers were

interviewed at Pour market.

Table Fish Market Questionnaires

Dinajpur

3.6.1 The proportion of species observed at Dinajpur market in relation to the most
quantities observed


Of the 10 retailers stalls examined there were ten different species being sold. Rui and

mrigel were the most prevalent species observed at the retailer stalls, 8 (21 percent) and 9

(24 percent) respectively. Silver carp was the third most prominent species observed at

the retailer stalls 7 (18 percent). Silver carp might have been the third most prevalent

species observed, but it had the highest quantities sold per retailer stall 6(50 percent)

followed by mrigel 4 (33 percent) and rui 2 (17 percent). The lowest frequency of

species observed was grass carp, tilapia, african magur, and common carp 1 (3 percent)

(refer to figure 3.6.1).
  60
                                                         Percent observed
  50                                                     Most quantities

  40

  30

  20

  10

    0
          i
        Ru




                                            tla
                  el




                                                                ia




                                                                          uti
                                  arp




                                   rp
                                  arp




                                          Ca
               rig




                                                             ap




                                                                       orp
                                                             ur
                                 Ca
              M




                                                           Til


                                                          ag
                               rC


                               sC




                                                                     Sh
                                                        nM
                              on
                             ve


                            as


                           m
                          Sil


                          Gr




                                                     ica
                         m




                                                  Afr
                       Co




Figure 3.6.1 The proportion of species observed at Dinajpur market in relation to the
most quantities observed


3.6.2 The species retailers sell the most quantities at Dinajpur market

Of the ten retailers asked which fish species do you sell the most of, 8 (80 percent)

replied silver carp while 2 (20 percent) replied rui.


3.6.3 The average price in taka/kg in Dinajp ur market of species by weight per kilogram

Average prices of table fish were assessed from the ten different retailer stalls; the results

are summarized in Table 3.6.3. Silver carp had the lowest cost per kilogram at all

weights, compared to rui, which was the most expensive table fish sampled.




3.6.3 The average price in taka kg- in Dinajpur market of species by weight per kilogram

Species                < 250g 251 – 500g 501 – 1000g
Silver Carp     38   40    54
Rui             65        100
Mrigal          56   60
Catla           52        70
Grass Carp                70
Tilapia         60
African Magur        50
Shorputi        50
                                      4 DISCUSSION


4.1 Hatchery trials

Reproductive performance of strains

The new strain showed no difference in fertilization rate when compared to the old strain,

being the case for both experiment one and two. There was however, a significant

difference in hatching rate with the new strain having a higher rate of hatching than the

old strain at 24 hr and 29 hr post fertilization for the second experiment. The same was

seen in the first experiment at 24 hr post fertilization.

Overall the old strain showed a significantly lower hatching rate than the new strain,

which could be an effect of inbreeding.          Several investigators have suggested that

inbreeding can cause a decline in fertilization rates and other reproductive performances

(Kincaid, 1983; Falconer, 1981).



Despite the low hatching rate found in the old strain, the amount of grams of wet weight

of larvae produced at the end of the larval rearing period divided by the amount of grams

of eggs stocks there found to be no significant differences between the old strain and new

strain. This could be attributed to the difficulties in obtaining an accurate estimation in

the incubators. Five to six replicates were carried out for hatching percentage one and ten

replicates was conducted for hatching percentage two. Ten replicates were studied for

hatching percentage two to determine if there were any differences.         There was no

significant difference between hatching percentage 1 and 2 for the new strain or for

hatching percentage 1 and 2 for the old strain in the second experiment. The ineffective

estimation is a result of the large volume of the incubator and the low stocking density.
The incubators were 800l concrete funnels with the water coming up from a screenless

bottom and leaving from the top. The flow rate was slightly different for each incubator

and changed daily depending on the volume of the header tank. It was observed that a

higher flow rate would have a denser pop ulation of eggs/larvae in the center of the

incubator while a slightly lower flow rate will have a low density in the center of the

incubator. The flow effect in the incubators could of influence the sampling results, by

not giving a true estimation of what was being measured.



At the completion of the hatchery trial there was found to be a significant difference in

fork length between three day old larvae of the new and old strain, with the new strain

being significantly larger than the old strain. This difference in size could be due to

strain or parental differences.    The old strain might have shown a reduction in size

compared to the new strain due to inbreeding depression. It has been suggested by

Hussain and Mazid (1999) that this depression due to inbreeding has led to a decline in

the growth performance in carps in Bangladesh. In fact an earlier study by Moav and

Wohlfarth (1976) showed that a single full sib mating of broodstock might result in 10 –

20% depression growth in progenies, exhibiting the potential “strength” of this factor.



Alternatively the size and weight of the female could have an influence on the difference

in size between the new and old strain larvae. The average weight of the new female

(2.00kg) was larger than the old strain (1.57kg) but not significant. Larger fish tend to

have a lower relative fecundity and bigger eggs than smaller fish.          Thus the size
difference could also be correlated to the fact that larger females tend to produce larger

larvae compared to smaller females.

4.1.2 Commercial Hatcheries

The general background of the three commercial hatcheries is summarized in Table 4.1.2

Table 4.1.2 Background information of commercial hatcheries used for the hapa trial
Characteristics               CM -1          CM -2            CM-3

Hatchery established          1990           1988             1989

No. of brood fish ponds         4              5                1

No. of circular tanks           4              2                2

No. of hatching jars           13              20               0

Source of broodfish       Outside source   Rear own         Rear own

Production last year         500 kg         1000 kg          250 kg

Source NFEP-2 hatchery survey 1999
CM-1 (Bai Bai Hatchery), CM-2 (Sagar Hatchery), CM-3 (Star Matshya Khamar hatchery)


  The size of the broodstock used is unknown from the three commercial hatcheries, but

   looking at the background data it can be suggested that CM-2, CM-3 have more of a

   chance of inbreeding depression in broodstocks used than CM-1, who brings in new

  founder stock for breeding purposes. When interviewing CM-1, it was found that the

   owner brought in new broodstock to prevent inbreeding problems. The owner would

 then spawn three females from an outside source with two males on farm or vice/versa.

   By this recruitment of new breeders into the stock at regular intervals the chances of

       inbreeding depression, are reduced as is the risk of a reduction in growth and

reproductive performance, increased incidence of diseases and morphological deformities

                                 (Eknath and Doyle 1990).
    With the growing concern about genetic deterioration in hatchery stocks, several

    scientists from the Bangladesh Fisheries Research Institute conducted a survey of

 hatcheries in Jessore and Commilla in 1994 to assess hatchery practices and found that

  the average weight of broodstock used for silver carp was 0.800kg – 1.00kg. Hussain

 (1998) suggesting that using undesirable sized breeders can results in early maturation

   and ultimately artificial seed production effort leads to stock deterioration problems

              because of poor growth and survival in the grow-out systems.



   The decrease in size in broodstock could be due to the effects of inbreeding or the

     unconscious ‘negative’ selection in hatcheries. Negative selection occurs when

hatcheries collect fish from grow-out ponds after larger individuals (faster growing) have

     been sold and the smaller (hence slower growing) fish are used for broodstock

   replacement. Negative selection has been suggested as one of the major reasons of

reducing the growth and other performance traits of farmed fish in Bangladesh (Hussain,

1998). There is evidence for this observation in India, where in small hatcheries younger

 individuals are exhibiting relatively slower growth rates, late maturity and also smaller

   size at first spawning, which has been related to the inadvertently breeding of slow-

            growing and late-maturing individuals (Eknath and Doyle, 1990).



4.2.1 Hapa trial

There were significant differences in survival rates after 20 days of nursing. STN, CM-2,

CM-3 had significantly higher survival rates when compared to NS, OS, and CM-1. STN

had the highest value for survival rate (91.36) but the difference was not significant
compared to CM-2, and CM-3. It would be expected that the non transferred larvae

would have a higher survival rate than the simulated transferred fish and commercial

hatchery fish, as the non-transferred fish were subjected to less stress. Handling, netting,

and transportation are the most common causes of acute stress in fish, which can have

detrimental effects on both survival and health (Barton and Iwama 1991)



A possible explanation for higher survival observed in STN, CM-2, and CM-3 could be

due to the samples taken from the transferred polyethylene bag. Simulated transfer fish

and commercial hatchery fish were stocked at 150 gm of larvae per bag. The bag was

then emptied over a fine mesh net to co llect the larvae. Stressed, dead or dying fish tend

to inhabit the surface of the water, by emptying the bag it is possible that the overly

stressed fish will tend to be located at the bottom of the fine mesh net while the stronger

and healthy fish will tend to be at the surface of the strained fish. A beaker was used to

collect a proportion of the fish. If the majority of the sample was taken near the surface

of the pile it might contain a higher percentage of healthy and stronger larvae than if the

sample was a cross section of the pile of fish containing a true representative of the

distribution of fish in the bag. This might explain the observed differences in survival

rate. But it was noted in experiment one there was a noticeably higher percentage of

dead, dying and severely stressed fish at the water surface in STO then STN. This might

suggest that the old strain is more sensitive to stress than the new strain, but further

investigation is required to determine this effect. There was no difference in survival rate

between NS and OS, which might suggest that the perceived quality difference might

occur later on in rearing.
The significant differences in weights and fork lengths after 20 days can be accounted for

by the hapa survival/weight relationships, where low survival rates in hapas tend to

produce larger size fish than hapas with high survival rates. This was observed with CM-

1 and CM-2.      CM-2 (87.71%) had a significantly higher survival rate than CM-1

(55.62%), but CM-2 (1.21) had a significantly lower fork length than CM-1 (1.52). For

production STN (46.5) and NS (45.33gm-2 ) had the highest mean values although there

were no significant differences between the seven treatments.      It might be that the new

strain is more productive than the old strain but in the first twenty days it is too early to

show a significant difference. A longer trial period might determine these effects.

A comparison trail was done previously at NFEP-2 Parbatipur hatchery, where silver carp

fingerlings produced from the existing old strain were compared to the new strain and a

cross between the new and old strain. At the end of the trial period, lasting 271 days, the

results showed that there was 21.6 percent increase in mean net production from the new

strain of silver carp compared to the old strain. This suggest that the new strain does

indeed perform better than the old strain in the NFEP-2 strain comparison, but

unfortunately the strains were raised in different ponds and stocked at different initial

weights which could have had an influence on the results.



There are many factors which could have an impact on the overall performance of silver

carp seed, such as maintenance of proper stocking density of broodfish and their balanced

feeding, selecting broodfish of a desirable size and quality, injecting adequate

hypophysation dosage, mating unrelated female and male breeder, basic disease control,

and transport/handling stress. Some of these factors could of influence the performance
of silver carp during the hatchery and hapa trial but there was no significant evidence

except for the fact that the new strain produced larger size larvae than the old strain and

commercial hatcheries, which could be caused by inbreeding depression and negative

selection.   The hapa trial period was to short too ascertain these effects on silver carp

seed quality. Significant differences may be observed later in the rearing period, or the

variety of actors (nursers, traders, farmers) potentially could have an impact on the

quality of silver carp seed as it passes through their hands.



4.3 The assessment of the importance of silver carp to the livelihoods to the people of

Northwest Bangladesh



4.3.1 Nursers



The importance of silver carp and the assessment of seed quality can be observed through
nursers. The nursers in northwest Bangladesh generally acquire hatchlings from private,
government or NGO’s within the region. Questionnaire results found that 30 percent go
to private hatcheries, 79 percent government, and 42 percent NGO’s. It has been
suggested that experience nursers go to government hatcheries to buy hatchlings because
the hatchery managers are more knowledgeable about the quality of seed (SOS,
Bangladesh, 1999). Questionnaire results determined that majority of nursers judge
hatchling quality by movement against the current or being a strong swimmer (65
percent). These findings are similar to the results from the SOS for Bangladesh. This
might suggest that the majority of nursers are aware of the importance of initially having
good quality seed before stocking in their nursery ponds. This finding is consistent with
the data from the SOS report for Bangladesh, which determined that nursers are
concerned with seed quality, and are willing to pay more to obtain good quality
hatchlings to nurse. Nursers tend to nurse silver carp for 15 to 30 days before selling with
the average stocking density being 40g 40m-2 . Some nursers kept these high stocking
densities throughout the nursing period while some lower the densities after 15 days. By
keeping the silver carp at high stocking density throughout the nursing period nurseries
can produce fry that will be smaller than average size that will be sold to the traders. The
use of high stocking densities to maximize water usage has been shown to exert severe
adverse effects on growth (Kebus, Collins, Brownfield, Amundson, Kayes, and Malison
1992). Farmers than would be stocking ponds initially with smaller size seed that might
be of lesser quality. In the SOS for Bangladesh it was determined that the Northwest
produces a greater range of seed size through different stocking densities to meet the
requirement of local traders as well as direct sales to the farmers. Through the
questionnaire it was determined that nursers considered rui/mrigel to have a better
survival rate than silver carp. The majority of the nursers interviewed felt that silver carp
had one of the lowest survival rates other than shorputi compared to all the species they
commonly nurse. This finding is consistent with the findings of the NFEP survey on
fingerling production in NFEP command area (1997). Table 4.2.1 summarizes these
findings. The NFEP results demonstrate that rui/mrigel have a higher survival rate than
silver carp followed by shorputi, which supports the perceived survival rate by nursers.




Table 4.2.1 A summary of the amount of fingerlings produced from 1k of hatchling used
by nursers, and the survival rates for 1994 and 1995

              Number of fingerlings    Mean number of       Percent Survival
              produced/kg of hatchling hatchlings in 1 kg

Species          1994         1995                          1994      1995

Silver Carp     63,299       61,171         200,000         31         31

Rui/mrigel      80,719       75,927         175,000         46         43

Shorputi        33,133       54,967         550,000          6         10
Source NFEP fingerling production 1997
Even though silver carp has a low survival rate it is still one of the predominant species
being produced. Results show that 100 percent of the respondents interviewed nursed
silver carp in their production cycle and 86 percent replied it was the species that was
produced the most of by weight. It was also assessed in the questionnaire that over 50
percent of production was silver carp. A survey done by NFEP from 1994 to 1995 in the
NFEP command area showed that 62,000 silver carp fingerlings were sold, which was
second in amount to rui/mrigel where 78,000 fingerlings were sold, but one has to
consider that two different species are being compared to one species. This would
suggest that silver carp is probably the highest traded species.


Results indicate that silver carp is considered the least problem to nurse by 70 percent,
which was the highest species considered by the respondents. There were several reasons
why nursers perceived silver carp the least problem to nurse and makes up a large
proportion of their production. One of the main reasons was demand; some of the other
reasons were high survival, fast growing and easy to produce.


Mid -season and early season silver carp hatchling are perceived by nursers to be of good
quality. These results are similar to the finding in the SOS for Bangladesh. However, late
season seed is considered poor quality. This might be due to the effect of hatcheries
selling off the large broodstock early in the season as table fish, which would require
using undersized (possibly slow growing) individuals as breeders late in the season.
Another possibility for poor quality seed late in the season is the repeated use of
hormonal induction on the same broodstock through out the spawning season, which
might be detrimental to ooycte development, thus effecting larval quality.


4.4.1 Traders
The major aim of the trader questionnaire was to determine the quality of silver carp and
its importance to the people in the northwest. Traders are the last link in the network
linking hatcheries to farmers; they bear some of the greatest risk in the network and yet
receive marginal benefits, that is why it is important to them to assess the quality of the
seed before making the journey to the farmers pond side. The results determined that 59
percent of traders assess fingerling quality by movement and another 26 percent by
strength. Strength is assessed by making a fist around the fingerling and feeling how
strong it wiggles. It is important to the trader to start off with good quality seed, because
low quality seed not only affects the farmer but also affects the trader’s livelihood.
Traders transport many different species. The species they consider that makes up a large
proportion of the trade are silver carp and common carp, which received a 100 percent
response. There were several reasons why the trader considered silver carp as a high
volume species, because of the demand by the farmer and it is fast growing. A study
done by NFEP -2 showed a steady increase of silver carp entering Parbatipur railway
station from 1993 to 1996, however they are the second most abundant species with
rui/mrigel/catla being the most abundant in numbers and percent composition (refer to
table 4.3.1)
               Silver Carp      Rui/Mirgel/Catla
  Year     Numbers Percent Numbers         Percent

1993           12,895   20.50   27,395      43.50

1994           21,622   15.70   69,015      50.20

1995           37,878   14.00   143,982     53.00

1996           49,438   22.80   80,387      38.20

Source NFEP-2 Paper 20
Table 4.3.1 The number and percent composition of fry and fingerlings of silver carp and
rui/mrigel/catla entering Parbatipur Railway Station for 1993 to 1996


The table illustrates the steady increase of fry and fingerlings of silver carp into
Parbatipur Railway Station. Overall rui/mirgel/catla have higher numbers (in 1996 it
they were close to double that of silver carp), but one has to consider that three different
species are being compared to one species. This reasoning would suggest that silver carp
might have close to the highest values in numbers and percentages during 1996 which
would reflect the results that were seen in the questionnaire where silver carp made up
one of the highest proportion of species being traded.
Although the fry traders perceive silver carp as a dominant species being traded, it is
considered one of the least favorites to transfer due to its low survival. Common carp
was the species of preference due to its hardiness during transfer. These results agree
with the results from the nursers that silver carp has a low survival rate compared to the
majority of other species. It also demonstrates the importance of silver carp as a species,
because in spite of its low survival rate it makes up a large proportion of the species
being nursed and traded.


Results for the questionnaire showed that 62 percent of the respondents perceived the
quality of silver carp has declined in the past five years, while 25 percent thought it had
increased due to better management, and the remainder 13 percent felt it has not change.
One trader with ten years experience suggested that the decline in silver carp was due to
hatcheries using undersized broodstock. This suggestion is consistent with the findings
of Hussain and Mazid (1997) where the average size broodstock being used for
production for silver carp was 0.8 – 1.0 kg, and their suggested minimum size is 1.5kg.
The use of undesirable sized breeders can result in seed with poor growth and survival in
the grow-out system.


4.5.1 Consumers
The results indicate that the average days worked per week were approximately the same
4.4 for females road builders and 4.5 for males aggregate workers. There was a large
difference between the amount of fish consumed per year with males eating fish 63.6
times per year (5.3/month) and females eating 26.88 times per year (2.24/month).
Females responded 42 percent in the questionnaire that their husbands eat the most fish in
the house. It is obvious that females within the household get far less fish than males.
This is consistent with the finding of the IFPRI study, which found that adult women
received a lower proportion of preferred foods (IFPRI, 1999). The women road builders
also responded that after the husband the children eat the most fish in the house.
Chicken was eaten 5 times per year by males aggregate workers and 4 times by females
road builders. Males also ate a disproportionate amount of meat compared to females,
consuming meat 38 times per year and females 4 times per year. The low numbers for
meat consumption of the women might be influenced by their religious background.
The questionnaire demonstrates that fish is the main source of protein for unskilled
laborers who tend to be landless especially in the case for the men interviewed, and
depend exclusively for their sustenance on their wages earned. These people walk on a
thin line, ready to plunge down to severe malnutrition when any imbalance between their
daily wages and the price and availability of fish occurs.
The results indicate that silver carp was the most frequently bought table fish by male
aggregate workers followed by puti then sharti. This was contrary to the female road
builder response. They considered puti being the most frequently purchased table fish
followed by sharti and silver carp. Although male aggregate workers purchased silver
carp most frequently it is not dependent on the price. On the other hand female response
to most frequently purchase table fish did follow a trend with price, where the least
expensive table fish is the most purchased. The least expensive table fish quoted by male
aggregate workers was puti and darika costing 24 taka kg-1 and 23 taka kg-1
respectively. Silver carp, shati, and chandra all were given the same price of 30 taka kg-1 .
Silver carp was the least expensive of the culture species, with rui and mrigel being the
most expensive. It was also determined that 50 percent of the female workers
respondents purchase the fish while 67 percent were their husbands. This might reflect
the discrepancy in table fish prices observed between the male and female workers.


Availability might have more of an influence on purchasing factors for silver carp. 75
percent of the male worker respondent that silver carp was the most available table fish in
the markets, while female road builders had a 67 percent response. This is consistent
with NFEP sampling marketing data, of which a brief account is summarized in Table
4.4.1 It can be seen in Table 4.4.1 that silver carp has proportionally higher quantities
than both tangra and mola, which confirm the perception that silver carp is the most
available table fish in the market. Male and female workers responded that the reason
why they purchase silver carp was because of the price, which received a 100 percent
response.
Table 4.4.1 Sums of quantity in kg of table fish at Rangpur market survey (1997)
Species      Rangpur
Silver Carp     8,350

Tangra          797

Mola             80

Shorputi        3,930

Rui             5,830
Source NFEP-2 market data




4.6.1 Markets
The results of the market questionnaire demonstrated that silver carp is the most frequent
species occurring in the retailer stalls. It is the least expensive of the cultured fish, and
the most purchased. The questionnaire also supported the dichotomy in size of silver
carp observed in the market. Large and small silver carp appear to be for the rich and
poor consumers respectively. 100 percent of the retailers confirmed this observation by
responding that small size silver carp is purchased by the labours and the marginal poor,
while large size silver carp is purchased by professionals, government workers, and the
wealthy.


5.1 CONCLUSION
Questionnaires were used to determine the impact that silver carp has on the livelihoods
to the people of northwest Bangladesh. Strain comparison trials were used to assess the
current quality of silver carp being used in aquaculture. The combination of social
surveys and technical farm trials is a powerful tool to determine the importance and
quality of silver carp in northwest Bangladesh.
The questionnaires determined several main points:
Nursers and Traders assess the quality of seed before purchase to ensure a better return
on final sell

One of the greatest proportions of species traded and nursed is silver carp

Silver carp is considered by traders and nursers to have a low survival rate compared to
other species
Traders perceived that the quality of silver carp has deteriorated in the last five years

Silver carp and small self recruiting species are purchased most frequently by unskilled
workers with silver carp being the species frequently bought by male aggregate workers

Silver carp is the most available in the markets sampled and is the least expensive of the
cultured species

The size of silver carp in the markets is purchased by different people: landless and
marginal poor purchase the small sizes, while the large sizes are bought by the wealthy

Silver carp was the most sold species in the markets sampled

Through the survey it can be determine that silver carp is a relative important species to
the people of northwest Bangladesh especially to the rural resource poor. It is one of the
least expensive of the cultured species and is readily available. It is considerably one of
the highest traded and nursed species next to rui/mrigel.

5.2.1 Strain comparison trial

Hatchery trial

There were no significant difference in fertilization rate between old strain and new strain

A significant difference were seen however, in the hatching rates with the new strain
having higher values then the old

There were no significant differences observed in total wet harvest weight/amount of
eggs stocked between the strains but there was significant difference in larvae fork
length, with new strain being greater in size than old strain and commercial hatchery
strain.

In summary there was no clear difference between the new and old strain during the
hatchery performance comparison. The new strain was significantly larger in size then
the old strain and this could be related to inbreeding depression in the old strain or
maternal differences in sizes between the strains

The old and new strain from the NFEP hatchery was significantly larger in size than the
commercial hatchery larvae and this could be the result of a lack of knowledge in
commercial hatcheries on the subject of broodstock/hatchery management practices.
Such fundamental knowledge includes the need for recruitment of new breeders into the
broodstock at regular intervals, proper stocking densities of broodfish/hatchings and their
balanced feeding. Further principles include the selection of broodstock of a desirable
size, injecting adequate hypophysation dosage, and mating unrelated female and male
breeders. These can all have an effect on seed quality.
Hapa trial

A significant difference in survival rate was observed, with two of the commercial
hatcheries and the simulated transfer of new strain having greater survival rates than the
commercial hatcheries one, simulated transfer of old strain, new strain, and old strain.
Differences in survival rates might be due to stocking procedure.

Commercial hatchery two had the significant lowest fork length and weight out of the
seven treatments, but there was no significant difference in final harvest production

In summary there were no clear difference between the seven treatments, which could be
due to inadvertently stocking the hapas with ‘stronger’ larvae from the commercial and
simulated transfer bags (CM-1, CM-2, CM-3, STN, STO).

There were no differences between the old and new strain, which suggest that differences
in performance could occur later on in the rearing cycle.
6.1 BILIOGRAPHY


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Week ’98 compendium. Department of Fisheries and Ministry of Fisheries and
Livestock, Dhaka, Bangladesh.

Ali, Md. M. (28 Aug, 1998) Desirable Dietary Patterns for Bangladesh People, The
Bangladesh Observer

Bangladesh Bureau of Statistics (BBS) (1998) Statistical Pocket Book of Bangladesh,
1998. Statistics Division, Ministry of Planning, Government of the People’s Republic of
Bangladesh. Department of Fisheries, Bangladesh.

Barton B.A., and Iwama G.K. (1991) Physiological changes in fish from stress in
aquaculture with emphasis on the response and effects of corticosteroids. Annual
Reviews of Fish Diseases 10, 3-26.

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railway station 1989, and 1992 to 1996. Northwest Fisheries Extension Project (Second
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Doyle, R.W. (1983) An approach to the quantitative analysis of domestication selection
in aquaculture. Aquaculture, 33: 167-185.

Eknath, A.E. and Doyle, R.W. (1985) Maximum likelihood estimation of
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aquaculture in India. Aquaculture, 49: 55-71

Eknath, A.E. and Doyle, R.W. (1990) Effective population size and rate of inbreeding in
aquaculture of Indian major carps. Aquaculture, 85: 293-305.

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340pp.

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7.1.1 Revised Questionnaire for Nursers
Nursery                       Name                 Owner
Location
Length of time in business?
What types of fish do you nurse?
What fish do you produce more than the others?                     Why?
What fish do you considered the least problem to nurse?            Why?
What do you look for in performance?
What is the size of your ponds?
How long do you nurse SC before selling?
How much produce a yr?
What % is SC.
Is SC polycultured?
What is the stocking density for SC?
How much of the fish do you sell compare to keeping?
Who do you usually sell too?
       Farmers
       Traders
       Market
       Others
How much do you sell for?
Where do you buy your hatchlings?
       Private
       Government
       Other Source
When the best time to buy SC?
How do you transport the fish?
       Walk
       Rickshaw
       Motor
       Other
Do you add any chemicals?
How do they compare to other fish in survival and quality during transportation?
What is SC survival rate?
                              7.1.2 Trader Questionnaire

Traders

Name

Location

How many years experience do you have?

What months do you trade fingerlings from?

What type of seed do you trade the most?
Why?

What do you think is the best fry to transfer?
Why?

What is the size of fingerling of silver carp you generally trade?

What size of silver carp gives the best survival?

What prices do you sell silver carp fingerlings?

What fish are more expensive?

What fish is cheaper?

Where do you buy your seed?

Do you usually buy from the same place?

What do you look for when buying fingerling?

What form of transportation do you use to transport your fish?

Who do you usually sell to?

How long do you usually travel?

What container do you use to transfer fish?

Do you use chemicals?

Quality of seed?
                                 7.1.3 Market Sampling

Name of Market

Union                 Thana                District


Species observed


Which one has the most quantities?

Amount of SC

Size and price

What dose he sells the most of

Who buys SC?

								
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