Abstract
Investigation on the reasons that affect the livelihood standard of community fishers is an increasing concern in Bangladesh. Haor- the famous natural repository is losing its abundance of fish due to over-exploitation and environmental degradation and whereby threatens the livelihoods of haor dwellers. Besides this, there is still unveiled the huge haor resources that have yet not come under aquaculture activities. The livelihood of fishers is not up-to the satisfactory level, which needs to be increased steadily to certain the economic security of the community fishers. The purpose of this research is to investigate the connection between socio-economic factors and the critical livelihood condition with all possible combination of cage aquaculture strategies. Community based cage aquaculture approaches by cage aquaculture aiming at increasing fish production of haor waters by developing the culture and nursing method of tilapia (Oreochromis niloticus) climbing perch (Anabas testudineus) and common carp (Cyprinus carpio) as a livelihood alternative may prevent over-exploitation and improve the livelihood of fishers. A
reconnaissance survey- through informant interviews, semi-structured interviews, questionnaire survey using Likert Scale, FGD (focus group discussions); was conducted to obtain an overview of the socio-economic factors and community perceptions about new alternative livelihood activity. Eight field and two lab based experiments were conducted maintaining appropriate statistical design (CRD) and data were analyzed using suitable methods (ANOVA, Individual Samples T test, regression). First objective investigated that changing attitude towards cage aquaculture activities was higher in fishers' groups those had more inclination in fishing activities. Simultaneously, non-economic factors such as tradition and personal thinking played an important role in decisions on whether to fish or not. Second objective comprises of eight sub experiments to determines the best stocking density and fingerling size where: 1) the stocking density at the rate of 35, 50 and 27fish m-3 for tilapia, Climbing perch and common carp table fish production in caged condition respectively; 2) rate of stocking 177, 250, 150 and 200 fish m-3 for tilapia normal nursing, tilapia overwintering nursing, Climbing perch nursing and common carp nursing in hapa
cum caged condition respectively and 3) tilapia fingerling size of 40g in caged condition showed best results. Water quality parameters (temperature, DO, pH, ammonia) were within the suitable ranges during the experiment but not for wave length, wave crest and current. The best outputs for stocking density and fingerling size for first year were further verified to drawn the inference about the technical and financial feasibility of cage aquaculture in case of stocked fry-to-fingerling and fingerling-to-table-fish production. The best final average body weight (FABW) for tilapia, climbing perch and common carp table fish production were 426, 101 and 612g. The stocked 40g size of tilapia was found the best stocked size where FABW was 409g during cage aquaculture. For nursing, the best FABW
were found 32.84, 54, 26.25 and 27.33 g for tilapia nursing, tilapia overwintering nursing, Climbing perch nursing
and common carp nursing respectively during first trial. The subsequent culture showed significantly (p<0.05) higher FABW (g) in all sub experiments for table fish and fingerling production but not significant (p>0.05) in case of tilapia and common carp table fish production. Third objective unearth the excellent findings for minimizing the
cost of feed formulation by BDT 3-4 kg-1 where diet comprised of only plant protein sources added with limiting essential amino acid (DL-Methionine) at the rate of 2.5g kg-Ifeed for two crude protein (CP) level 28% and 32% respectively with a view to complete replacement of fish meal (FM) with SBM (Soybean meal). Forth objective highlighted the effects of feed additive (commercial probiotic) in growth performance of tilapia fry. Probiotics comprised of bacteria, yeast and mold used to formulate six tests diet and used in the rearing of fish for 60 days containing 0.5 to 1.5 g kg-1 feed (total viable count 2×10cfu) along with no supplementation in control diet. A
polynomial regression (R2=0.912) was observed in weight gain where best output was observed in diet 5 (1.25 g kg- 1).Remarkable improvement in reducing the pathogenic microbe Escherichia coli content in the gastrointestinal tract
was observed in treated groups over the control. Fifth objective reported on the output of introduction of cage aquaculture through the assessment of growth performance, production and profitability of three selected fish species (tilapia, common carp and Climbing perch) for table fish and fingerling production adopting best management practices (BMP). Data collected from first year, started year of cage aquaculture (before BMP), to the second and third year (after BMP). A statistical analysis executed to compare between the performance, production and profitability of the first year and at the end of third year. The feed conversion ratios were observed in fry nursing and table fish production showed significant at 10% and 1% level in case of tilapia and Climbing perch rearing. Although the average variable cost increased in subsequent cultures but resulted in significantly higher
selling price for all experiments. Taking into account the financial analysis, the break event price to cover operating cost and total cost were significant for for fry production but not for table fish production. The livelihood condition of
community fishers were increased by 18.34, 13.93 and 18.75 % for table fish production of tilapia, climbing perch and common carp respectively. The livelihood condition of community fishers were increased by 18.93, 44, (-)7.79 and 48.25 % for fingerling production of nursing of tilapia, overwintering of tilapia, Climbing perch nursing and common carp fry nursing respectively. These results suggest that community based cage aquaculture system can do well and significantly alter the poor livelihood condition. This research demonstrates distinct improvements in the economic status of fishers in Bangladesh.