Wetland Economics: 2. Crab Production in Brackishwater Ponds of Sundarban, West Bengal

Mud crab (Scylla serrata and S. tranquebarica) fishing in Sundarban, West Bengal is an old practice while its farming is a recent one dating back to 1990s. Herein, farming denotes fattening of crabs. Crab fattening locally called chamber chas relates to rearing of discarded adult mud crabs unft to attract export market. This recent enterprise involves rearing of discarded crabs (eggless female crabs and male water crabs) fed with trash fish, mollusks meat, etc., in brackishwater ponds (ranging from 2 to 10 cottahs, i.e., 0.01 ha to 0.06 ha, larger ones often partitioned into 3-4 ponds with bamboo-split screen and nylon net) for period of 15-20 days in different areas like Gosaba, Basanti, Minakhan, Hingalganj, Hasnabad and Sandeshkhali, nearer to mangrove forest to meet the demand of gonad developed female crabs and larger sized male meat crabs. Field surveys and observations revealed that crab farmers use to stock discarded crabs @ 20-40 (30) kg crabs per cottah (katha) of pond and supply fresh fish and mollusk feed @ 7-8 kg per 100 kg of crabs, i.e., @ 7-8 % of their body weight. It has also been revealed that a crab farmer earns Rs. 1,200-2,000 per month per cottah (katha), using his own brackishwater pond and household man-powers.

Crab catching in the Sundarban though remains in its traditional form even today still the existing wild estuarine stock is increasingly exploited/over-exploited. There is also increasing demand of live crabs in the export market and hence the need for farming. However, it is necessary to standardize the crab fattening technique using simple scientific methods of water quality monitoring in addition to size and sex-wise segregating of crabs, reducing mortality rate and escape of crabs, and also need for pond management and provision of cost effective feed supplement to augment the production potentials and to reduce the dependency on mangrove forest.