Rouf Muhammad Abdur, Shahriar Sheik Istiak Md, Antu Al-Hasan, Siddiqui Md Noman
Fisheries and Marine Resource Technology Discipline, Khulna University, Khulna, 9208, Bangladesh.
Department of Aquaculture, Hajee Mohammad Danesh Science and Technology University, Dinajpur, 5200, Bangladesh.
Heliyon. 2021 Feb 12;7(2):e06223. doi: 10.1016/j.heliyon.2021.e06223. eCollection 2021 Feb.
Population parameters of orange mud crab () were estimated, aiming to determine sex ratios, carapace width-body weight (CW-BW) relationships, asymptotic width (CW), growth coefficient (K), mortality (Z, M, and F), recruitment and level of exploitation (E) in the Sundarban mangrove forest, located in the south-western part of Bangladesh. Year-round samples were collected using hook-lines and baited traps, the population parameters were measured from CW frequency data using FiSAT-II analyzer. The study showed that the overall male and female sex ratio was 1:0.66, revealing a male domination in the study area. The CW-BW relationship indicated that the increment rate in the BW of the male crabs (b = 3.06, R = 0.98) were higher than that of female (b = 2.62; R = 0.98) . The b value differed significantly (P < 0.006) from isometric growth (b = 3) where males exhibited positive and females exhibited negative growth allometry. Estimated CW for male and female were 164 mm and 152 mm along with K values 0.90 yr and 0.76 yr, respectively. Total mortality (Z) was 2.67 yr and 1.57 yr, natural mortality (M) was 0.98 yr and 0.90 yr and fishing mortality (F) was 1.69 yr and 0.67 yr for male and female, accordingly. Recruitment of both sexes exhibited a bimodal recruitment pattern where young population occurs continuously throughout the year and a major peak of recruitment for males was observed from November to January and for female it was from February to April. The estimated exploitation rate (E) for male (0.63) was higher than the female (0.43) where the E for male exceeded the maximum permissible limit (E = 0.50). A remarkable range of fishing pressure at lower size classes was revealed in this study and thus framing minimum legal size is crucial for effective management of the population.
对橙色泥蟹（）的种群参数进行了估计，旨在确定位于孟加拉国西南部的孙德尔本斯红树林中的性别比例、头胸甲宽度与体重（CW-BW）关系、渐近宽度（CW）、生长系数（K）、死亡率（Z、M和F）、补充量和开发水平（E）。使用钓线和诱饵陷阱全年采集样本，使用FiSAT-II分析仪从CW频率数据中测量种群参数。研究表明，总体雌雄性别比例为1:0.66，显示出研究区域内雄性占主导地位。CW-BW关系表明，雄性螃蟹体重的增长率（b = 3.06，R = 0.98）高于雌性（b = 2.62；R = 0.98）。b值与等速生长（b = 3）有显著差异（P < 0.006），其中雄性表现出正生长异速生长，雌性表现出负生长异速生长。雄性和雌性的估计CW分别为164毫米和152毫米，K值分别为0.90年和0.76年。雄性和雌性的总死亡率（Z）分别为2.67年和1.57年，自然死亡率（M）分别为0.98年和0.90年，捕捞死亡率（F）分别为1.69年和0.67年。两性的补充量均呈现双峰补充模式，幼蟹全年持续出现，雄性补充量的主要高峰出现在11月至1月，雌性则出现在2月至4月。雄性的估计开发率（E）（0.63）高于雌性（0.43），其中雄性的E超过了最大允许限度（E = 0.50）。本研究揭示了较小规格等级的显著捕捞压力范围，因此设定最小合法尺寸对于有效管理种群至关重要。
