Guessimation of the Maximum Sustainable Yield for the Pasur River Fishery in Khulna Region by Using Surplus Production Model

Abstract

Maximum sustainable yield (MSY) was estimated for the two major groups of fishery (inland fish and small shrimp) of the Pasur River based on four years (from 2011 to 2014) fishery dependent data of catch and effort records following the unit of effort as 200m² SBN/day from the Department of Fisheries. Surplus production model (Fox model) was used to estimate the MSY. Sustainable yield of approximately 4.61 kg of fish taken by 13.51 units effort of inland fish and 4.46 kg of fish taken by 9.48 units effort of small shrimp. The obtained MSY were smaller than the recent catch which indicates that this fishery was overexploited and require some effective management and should maintain sustainable exploitation of the stocks by reducing fishing effort in the area. The relationship between the estimated and observed Catch per unit effort (CPUE), Ratio of estimated yield (Cₜ) and MSY (Cₜ/MSY) and Ratio of estimated fishing effort (fₜ) and fmsy (fₜ/fmsy) for inland fish and small shrimp were estimated by deterministic approach and it suggested that there were overfishing in few months of January, February, March, June, July and December for inland fish and February, March, June, October and December for small shrimp. Furthermore, the mean of MSY and total allowable catch (TAC) with 95% Confidence interval (CI) for inland fish were 4.53 (4.52-4.54) kg and 4.08 (4.07-4.09) kg with a corresponding effort of 13.22 (13.15-13.29) units of fmsy and for small shrimp were 4.43 (4.42-4.44) kg and 3.99 (3.98-4.00) kg with a corresponding effort of 9.40 (9.39-9.41) units of fmsy respectively from the stochastic models. The results suggest that the TAC should be included in current management measures to ensure a long-term sustainable utilization of these stocks.