Assessing recent gradual upsurge of marine captured Hilsa stock (Tenualosa ilisha) in Bangladesh

Abstract

The anadromous Hilsa shad (Tenualosa ilisha) fishery is the prime single species fishery of Bangladesh that driven by open access system which was selected for this study. Key purpose of this study was to assess the MSY (Maximum Sustainable Yield) in order to review the effectivity of the ongoing management policy of this fishery. For this reason, time series maritime or downstream catch-effort data of the Bay of Bengal were assembled from the Department of Fisheries, Bangladesh. MSY, CPUE and other population parameters were estimated through Surplus Production Models (SPMs) using computer software packages of CEDA, ASPIC and TropFishR. Assessed biological reference points of MSY from the best fitted CEDA package was 282,100 t (R2 = 0.822) for the normal assumptions of the Schaefer and Pella-Tomlinson models. MSY values from the ASPIC packages (324,100 t and 263,500 t; for Fox and Schaefer model) and Schaefer model from TropFishR (345,486t) were larger than the catch in 2017 (278,948 t). The values of F ratio (F/FMSY) for all SPMs were found less than 1 and B ratio (B/BMSY) were greater than 1 that clearly indicate the gradual upsurge of the Hilsa stock. Based on the above findings of BRPs, it also proves the effectivity of the current “Hilsa fishery management action plan” by the authorities. Keywords: Tenualosa ilisha, SPM (surplus production model), CEDA (catch and effort data analysis), ASPIC (A surplus production model incorporate covariates), TropFishR