Regional Studies in Marine Science ( IF 2.1 ) Pub Date : 2021-03-20 , DOI: 10.1016/j.rsma.2021.101753 Vettath Raghavan Suresh , Sandhya Kavitha Mandhir , Aliyamintakath Muhammadali Sajina , Ranjan Kumar Manna , Jayanta Mukherjee , Surajit Kangsa Banik , Tara Maity , Rupam Samanta , Rohan Kumar Raman , Jayasankar Jayaraman , Bijoy Kumar Behera
The anadromous shad, Tenualosa ilisha is a fish of high economic importance in countries flanking the Bay of Bengal (BoB). Its fishery in the northern BoB bordering India and the associated Bhagirathi–Hooghly river system has been declining. Scientific explanations on the existing fishery management recommendations, especially the length at first maturity (), minimum legal size (MLS), minimum mesh size for fishing nets and stock status were limited, raising serious concerns on the sustainability of its fisheries. Through the examination of its reproductive cycle, using histological maturity identifiers, the of males and females were redefined at 265 mm TL/ 1.0 year age and 305 mm TL/ 1.2 year age, respectively. The size-based fecundity, sex ratio and abundance revealed that females of 281–360 mm TL/ 1.0–1.6 year of age have maximum reproductive potential. In the catch, 45%–65% of males and females were below . The temporal progression of mean length in the catch (MLC) and female length at maturity showed declining trend. Application of length-based indicators (LBI) and stock assessment models showed the fishery in near full exploitation, less optimal and undergoing multi-generation, indiscriminate, size-selective overfishing. The spawning stock biomass (SSB) has declined to 26.8% of the virgin SSB, while the yearly spawning potential ratio (SPR) ranged from 0.04 to 0.29, which is lower than the SPR threshold (0.3) suggested for sustaining a fishery. The species is both growth and recruitment overfished. Though the mean annual catch is marginally lower than the estimated maximum sustainable yield (MSY) of 32,953 t, any increase in fishing effort would further impact the SSB. Based on the results, a MLS of 360 mm TL, minimum mesh size of 110 mm for fishing gear and a precautionary annual catch limit of 30,000 t suggested for management, and the potential impact of implementing these on fishers’ catches discussed.
中文翻译:
淡水d鱼(Tenualosa ilisha)的繁殖潜力和种群状况(汉密尔顿,1822年):对管理与印度接壤的孟加拉北部湾北部渔业下降的影响
在孟加拉湾(BoB)侧翼的国家中,这种顽固的sha鱼Tenualosa ilisha是一种具有重要经济意义的鱼。它在与印度接壤的北部BoB和相关的Bhagirathi-Hooghly河系中的渔业正在减少。对现有渔业管理建议的科学解释,尤其是首次成熟期的长度(),最小法律尺寸(MLS),最小的网眼尺寸和种群状况受到限制,这引起了对其渔业可持续性的严重关注。通过使用组织学成熟度标识符检查其生殖周期,男性和女性的重新定义分别为265 mm TL / 1.0岁和305 mm TL / 1.2岁。基于大小的繁殖力,性别比和丰度表明,281–360 mm TL / 1.0–1.6岁的雌性具有最大的繁殖潜力。在渔获物中,男性和女性的45%–65%以下。渔获物平均长度(MLC)和雌性成熟期随时间的推移呈下降趋势。基于长度的指标(LBI)和种群评估模型的应用表明,该捕捞业已接近全面开发,不是最理想的,并且经历了多代,不加区分,大小选择的过度捕捞。产卵生物量(SSB)已降至原始SSB的26.8%,而年产卵潜力比(SPR)在0.04至0.29之间,低于为维持渔业而建议的SPR阈值(0.3)。该物种被过度捕捞的生长和募集。尽管平均年渔获量略低于估计的最大可持续单产(MSY)32953吨,但捕捞努力的任何增加将进一步影响SSB。根据结果,MLS为360 mm TL,