Effect of Stocking Density on Survival, Growth and Production of Mud Crab Juvenile by Pen Culture System of Bangladesh

Effect of stocking densities on the growth, survival and production of mud crab juvenile, genera Scylla was tested in a pen culture rearing system. Physico-chemical parameters were at the suitable level for culture period. The experiment was conducted for a rearing period of 135 days in nine pen culture earthen ponds having an area of 0.121 ha with an average depth of 0.90±0.13 meter each. Juvenile of mud crabs stocked at 0.025, 0.035 and 0.45 million.ha-1 were designated as treatment T1, T2 and T3. At stocking, all juveniles were with an initial mean carapace length, carapace width and weight of 2.80±0.02cm, 4.10±0.04 cm and 45.80±0.80 g respectively. Highest mean carapace length, carapace width and weight gain was recorded in treatment T1 and lowest in treatment T3. Survival of juvenile followed the same trends as weight gain. Juvenile of mud crab in treatment T1 produced significantly higher specific growth rate than treatment T2 and T3. Feed conversion ratio was significantly lower in treatment T1 followed by treatment T2 and T3 in that order. Significantly higher number of juveniles was produced in treatment T3 than in treatment T2 and T1, respectively. In despite of this, consistently higher net benefits were found from treatment T1 than from treatment T3 and T2, and also significant (P<0.05). Overall, highest growth, survival and net benefits of mud crab juvenile was found at a density of 0.025 million juvenile.ha-1. Identification of mud crab species were Scylla serrata and Scylla olivacea and percentage of Scylla serrata was 44.82, 29.40 and 26.77% from treatment T1, T2 and T3 and significantly lower than Scylla olivacea. Therefore, of the three stocking densities, 0.025 million juvenile.ha-1 appears to be most suitable stocking density for rearing of mud crab juvenile pen culture system.