Biology and Fishery of Blue Swimming Crab in Thailand

Abstract

            The data on biology and stock status of target species is necessary for fishery management planning. Blue swimming crab (BSC) is one of the most economic species of Thai industrial fishery. Thailand had been recorded as a main exporter, the 4^th largest exporter in the world, shipping BSC to other countries. Recently, the precarious status of BSC, Portunus pelagicus, stocks in Thailand is widely acknowledged. This documentary research aimed therefore to gather previous research documents providing basic knowledge for restoration of BSC stock in Thailand. Previous findings indicated that BSC stock have become depleted and fishery status is now overfishing. Exploitation rate in several areas was higher than 0.5. The first maturity size of BSC have also become smaller related to the reduction of BSC fecundity. This is possibly because the adaptation of the crab to prevent stock collapse resulted to less fisheries income. Spawning season of BSC varies with locations and period of studies. Biological data indicates that optimum landing size of BSC should be bigger than 9.5 cm in order to follow precautionary management. Environmental factors especially salinity, water temperature and dissolved oxygen are limiting factors on survival rates of juvenile crabs. Moreover, the restoration of relevant ecosystems such as seagrass habitat, water current and sandy seafloor will also increase survival rates and create the chance of enhanced success.