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大青鲨是金枪鱼延绳钓渔业中最主要的兼捕鱼种,在海洋食物网中属于顶端物种,在海洋生态系统中处于重要地位.由于数据限制,传统的资源评估方法很难准确描述大青鲨的资源动态.本研究基于大青鲨的生活史参数,应用种群统计分析法评估大青鲨的种群参数和资源状态,并探讨了内禀增长率为0时对应的临界捕捞死亡系数F_c与开捕年龄t_c的关系.结果表明:未开发状态下,大青鲨存活率为0.719~0.820;大青鲨的内在瞬时增长率(r_0)为0.250~0.381,种群倍增时间(t_(x2))为1.819~2.773年,种群的净繁殖力(R0)为6.600~22.255,世代间期时间(G)为8.498~10.162年,种群资源状态良好.生活史参数的敏感性检验显示,大青鲨初始年龄的自然死亡系数、种群性成熟年龄及寿命的不确定性对种群统计参数的意义影响不大;临界捕捞死亡系数伴随开捕年龄的增大而增大,当tc≥5时,F_c值与t_c无显著相关关系.
Big blue shark is the most important by-catch of tuna longline fisheries, which belongs to the top species in marine food web and plays an important role in marine ecosystem.Due to data limitations, traditional resource assessment methods are difficult to accurately describe large Based on the life history parameters of the great blue sharks, population statistics and resource status of the great blue sharks were estimated by population statistical analysis method, and the critical fishing mortality coefficient F_c The results showed that under the undeveloped condition, the survival rate of O. chinensis was between 0.719 and 0.820, the intrinsic instantaneous growth rate (r_0) of A. sativa from 0.250 to 0.381 and the population doubling time (t_ (x2) ) From 1.8197.273 to 2.773, the net fertility (R0) of the population ranged from 6.600 to 22.255, and the intergenerational period (G) ranged from 8.949 to 10.262.The population resources were in good condition.The sensitivities of the life history parameters showed that the green shark The natural death coefficient, population mature age and life uncertainty of the initial age had little effect on the significance of statistical parameters of the population. The critical fishing mortality increased with the increase of the catching age. When tc≥5, the value of F_c No significant correlation with t_c.