Diet and harvesting regimen for the production of mud crab Scylla olivacea in brackish water ponds

Abstract

The effects of diet (fish bycatch or a mixed diet of 75% brown mussel flesh and 25% cooked cracked corn) and harvesting regimen (bimonthly selective harvesting, or single terminal harvesting) on growth, survival and production of mud crab Scylla olivacea (Herbst) in brackish water ponds were determined in a replicated factorial experiment. The crabs were stocked at 0.6 individuals per m² for 118 days. There was no significant interaction (P > 0.05) between the diet and harvesting regimen treatments. Regardless of diet, the survival rate and net production of mud crabs were significantly higher (P < 0.05) when crabs were subjected to bimonthly selective harvesting than at single terminal harvest. Comparative cost–return analysis showed that bimonthly selective harvesting and mixed diet treatments attained higher net return and return on investment, and lower cost of production than the other treatments. Partial budgeting analysis showed that bigger profits can be earned by using a bimonthly selective harvesting and a mixed diet of 75% fresh or fresh-frozen brown mussel flesh and 25% cooked cracked corn.