Estimating Fisheries Reference Points for Five Data-Limited Fish Stocks in Kaptai Reservoir, Bangladesh

Abstract

The Kaptai reservoir is one of the important fisheries hubs in Bangladesh for its significant role in the national economy and socio-economic sector. However, easy accessibility to the reservoir along with other human-driven disturbances are pushing the stocks at risk. The sustainable fishery management depends on estimating a stock's total allowable catch (TAC), therefore, a recently developed Monte Carlo method (CMSY) was used for five data-limited stocks (catfish, Sperata aor; snakehead, Channa marulius; carp, Labeo rohita; cichlids, Oreochromis mossambicus and featherback, Notopterus notopterus) to estimate their fishery reference points using their catch, resilience and exploitation record at the first and last catch of the year. A Bayesian state-space implementation of the Schaefer surplus production model (BSM) was also used to compare and justify the output of the CMSY. CMSY estimated the maximum sustainable yield (MSY) to be 378, 110, 74.5, 432 and 99 mt for S. aor, C. marulius, L. rohita, O. mossambicus and N. notopterus, respectively. The result suggests that C. marulius, L. rohita and O. mossambicus fisheries were rebuilding naturally and at underfishing and underfished state according to the values of F/F_MSY and B/B_MSY as per BSM (value < 1). Value of B_MSY greater than present biomass estimated by BSM for L. rohita and O. mossambicus predicts that the stock's overexploitation state seeking serious attention. Although the S. aor fishery seemed to be sustainable and had the potential to produce more, F/F_MSY and B/B_MSY values close to 1 recommend strict management actions for further sustainability. However, F/F_MSY 1.31 for N. notopterus reveals that the stock depleted remarkably making this fishery unsustainable. The study reveals that Kaptai reservoir fisheries require intensive care to maintain sustainable resources. Strict implication of allowable catch limit, mesh size regulation, maintaining water quality, and protection of breeding and nursery ground is highly recommended.