Estimation of key population parameters of Penaeus indicus H. Milne Edwards, 1837 (Crustacea: Penaeidae) in the Andharmanik River, southern Bangladesh: implications for sustainable management

Abstract This study was conducted to estimate the key population parameters to understand both the current status and the yield of Penaeus indicus H. Milne Edwards, 1837 in the Andharmanik River, southern Bangladesh, using monthly samples collected from July 2019 to June 2020. We found that the size at first sexual maturity of P. indicus is 15.5 mm CL. The spawning season was August - December with a peak in September. Recruitment occurred at ~8.4 mm CL for an extended period of the year with two pulses: one in November (minor recruitment pulse) and another in February (major recruitment pulse). The von Bertalanffy growth equation gave the following results: CL∞ = 31.9 mm and K = 1.14 year-1. The overall growth performance index was 3.37 and the longevity was 2.6 years. The estimated total, natural, and fishing mortalities were 3.53, 2.15, and 1.38 year-1, respectively. Therefore, the exploitation rate was 0.39 and the maximum sustainable yield was 0.42, indicating that the stock is almost optimally exploited. Hence our work should help improve decisions to (i) conserve the stock, (ii) maximize economic returns from the stock, and (iii) continue ensuring that the stock is exploited in an ecologically sustainable way.

摘要 本研究旨在通过2019年7月至2020年6月采集的月度样本，估算孟加拉国南部安达尔马尼克河（Andharmanik River）印度明对虾（Penaeus indicus H. Milne Edwards, 1837）的关键种群参数，以明确其当前资源现状与渔获产量。研究结果显示，印度明对虾的初次性成熟头胸甲长（carapace length，CL）为15.5 mm。其产卵期为8月至12月，产卵高峰出现在9月。补充群体发生于头胸甲长约8.4 mm时，全年均存在补充现象，且具有两个补充峰：11月为小幅补充峰，2月为主要补充峰。运用冯·贝塔朗菲（von Bertalanffy）生长方程分析得到如下结果：渐近头胸甲长CL∞=31.9 mm，生长参数K=1.14 年⁻¹。整体生长性能指数为3.37，种群寿命为2.6年。经估算，总死亡率、自然死亡率与捕捞死亡率分别为3.53 年⁻¹、2.15 年⁻¹与1.38 年⁻¹。据此计算的资源开发率为0.39，最大可持续产量为0.42，表明该种群资源正处于最优开发状态。因此，本研究可为以下三方面的决策优化提供支撑：（i）种群资源保护，（ii）最大化种群资源的经济收益，（iii）持续保障种群资源以生态可持续的方式开展开发利用。