Application of Length-Based Assessment Methods to Elucidate Biological Reference Points of Black Pomfret Stock in the Bay of Bengal, Bangladesh

Abstract

The black pomfret (Parastromateus niger) is one of the high-income-generating carangid fish species and the only known member of its genus. This study aims to identify existing gaps in stock status and population demography of this species and provide viable management recommendations to enhance the sustainability of this fishery. Therefore, three methodological approaches have been used in this study; TropFishR to present the current exploitation status, the length-based spawning potential ratio (LB-SPR) to quantify stock spawning biomass, and Froese’s sustainability indicators (LBI) to establish a basic standard for sustainable management of the fishery. In the length-weight relationship of black pomfret, an allometric growth pattern (b = 2.19) was found. The VBGF life history parameters for black pomfret were L∞ = 55.25 cm, K = 0.54 year−1, and based on LCCC analysis, the total mortality (Z = 1.61 year−1), natural mortality (M = 0.69 year−1) and fishing mortality (F = 0.91 year−1) are calculated. The result reveals that this fishery is currently suffering from overexploitation and the stock’s spawning biomass (SPR = 13%) is below the limit reference point because most of the catch (82%) was found to be under the maturity level. Based on the results, this study recommended strictly maintaining the mesh size of the net to ensure not to catch immature fish with a length smaller than 30.63 cm, recommended the length to catch be between 29 and 35 cm, and reducing fishing pressure by one-third to ensure the sustainability of the black pomfret fishery.

Keywords

• Bay of Bengal
• <i>Parastromateus niger</i>
• spawning potential ratio
• length-based indicators
• overexploitation
• mesh size regulation