Trend of soft fattening of mud crab in south-east coast of bangladesh

Abstract:

Mud crab (Scylla serrato) soft shell fattening in Bangladesh is a quite new technology mainly practiced in the south-east and south-west coastal floodplain of Bangladesh. The fattening and culture technique of mud crab fattening in Bangladesh has a strong track record in research and development. To fill in the knowledge gap on about the soft shell fattening which experienced many issues within a short time, the current piece of research was undertaken. The case study was executed in the south-east coastal area where the soft shell fattening has started in 2011. Only 2 farms were found to operate during the study period September 2017 to Jacuary 2018, therefore the ongoing activities were observed in the pioneer farm “Irwan Crab Project”. Both current and previous soft shell fatteners were interviewed to get an overview and understand the causes of shut-down in many places of Cox’s Bazar. Stakeholders mainly fisheries officials from GO and NGO’s, fattemers, middlemen and exporters were in viewed accordingly. Both primary and secondary data were used in this study to draw a holistic scenario of soft shell fattening in Bangladesh context. The study revealed that mud crab seeds were sourced from the nature alike the hard shell fattening practice as there is not hatchery developed yet in Bangladesh to supply mud crabs. About 80% of stocked mud crab for the soft shell fattening is within 51 to 80 g in weight. Plastic cage with adequate holes are used for fattening where the male (1.20 g/day) grown faster than the female one (0.80 g/day) in average carb attained 25% body weight to the initial. Crabs are generally checked in every three hours interval and fed with trash fish (@5-8% body weight for 3 days. Water exchange, water quality parameters such as salinity, temperature were within the optimum level and similar to the hard shell fattening. The total yield of soft shell fattening was 20 mt/ha which is 6 times higher from the hard shell fattening. The mortality rate ranged 10-15% while certain change of salinity and higher temperature causes the major crop loss. After harvesting soft shell crabs passes number nodes of supply chain like the other finfishes and shellfish marketing. The crabs are graded into 3 grades (A, B, C) and sub-graded (XXL, XL. L, S) on the basis of their shell quality and body weight. From the total volume of harvest only 70% are exported and the rest discarded in different nodes of supply chain on quality ground. The molted shell also a significant by-product and the co-produced fish in the water column and bottom area which accounted 5 ton/ha are the major outcomes from the system. About two-third of mud crab in volume are exported in South Korea and the rest of the destinations are Japan, Malaysia, Hong Kong, Australia etc. The study also identified that soft shell fattening in the Cox’s Bazar region enjoyed a golden period during 2014-15 when the export volume raised up to about 150mt and gradually decreasing and the last year it was worst case scenario when export volume was one sixth of the peak years. Power asymmetry of export market which is controlled by the buyers is the main reason for the market collapse. Marginal profits, less availability of seeds from the nature are the reasons of shut downing of the majors soft shell farm in the Cox’s Bazaar region. A proper monitoring, enhance freezing technique like IQF, crab hatchery establishment and market control could minimize these damages. This study brought a shot of the soft shell mud crab fattening and compared with the existing hard shell fattening practices and provide some insights for the pragmatic actions within the limited time and budget constraints.