Length Based Stock Assessment of Five Fish Species from the Marine Water of Pakistan

Abstract

The marine fisheries resources of Pakistan have been drastically affected in the past few decades. Considering the limitations of previous studies and the data poor condition of the marine fisheries of Pakistan, this study employed the length-based Bayesian biomass (LBB) estimation method for analyzing the fisheries’ representative length-frequency data of five exploited marine fish stocks (Nemipterus japonicus, Nemipterus randalli, Parascolopsis aspinosa, Saurida tumbil, and Lepturacanthus savala). The estimates of relative fishing mortality (F/M) are higher than unity in four stocks except for S. tumbil, indicating overfishing. However, the current values relative to unexploited biomass (B/B0) are below 0.4, which indicates that the stock biomass is deficient in delivering maximum sustainable yield. Overfishing and the mass exclusion of small and older fish from stocks threaten to deplete the biomass of all species. Therefore, this study recommended that increasing the mesh size in commercial fisheries would increase both the catch and biomass of these species. The existing number of boats should be reduced to reduce fishing mortality and bring it back to the ratio of relative fishing mortality (F/M) equal or less than unity, for a sustainable level.