Assessing the pomfret stock for setting catch limits in the northern Bay of Bengal, Bangladesh

Abstract

Pampus argenteus and Pampus chinensis form the high-value demersal Pomfret fishery of Bangladesh. But, due to a monotonic decline in catches over the last five years, it is essential to explore the current stock status concerning the removal rate to ensure the sustainability of this fishery. Therefore, given the reliability and minimal data requirements, this study employed an extended Bayesian State-Space Surplus Production Model, JABBA (Just Another Bayesian Biomass Assessment), to assess the stock rigorously. The results revealed that the stock biomass of the Pomfret fishery in the final year of the time series is significantly lower than BMSY, the biomass required to produce MSY. Consequently, this study recommends a yearly catch limit (TAC) of 10,000 metric tons to prevent further depletion of the stock biomass. Furthermore, to avoid growth overfishing by allowing all immature fishes to reproduce at least once before being caught, this study also calculated the optimum length (Lopt) for catch for both species at which biologically maximum yield and revenue can be obtained. The estimated Lopt is 25 cm for P. argenteus and 30 cm for P. chinensis, and not to capture fishes with lengths lower than these limits, this study further calculated the minimum mesh size limits for gill and set bag nets is 7.5 cm. Though the mesh size regulation was estimated using length-based reference points derived from an empirical equation, this regulation can be used as an associate reference point when TAC is applied to assure the sustainability of this fishery.

Keywords

• Pomfret fishery
• Stock assessment
• JABBA
• TAC
• Lower length limits for catches
• Mesh size regulation