区域渔业管理组织中的鲨鱼养护管理问题研究

镰状真鲨属大型中上层鲨鱼，是东太平洋地区金枪鱼延绳钓和围网兼捕渔获最多的鲨鱼种类，近年来资源衰退严重，被世界自然保护联盟 (IUCN)评估为易危物种，并列入《濒危物种国际贸易公约》 (CITES)附录 II。开展鱼类年龄与生长研究，是评估其资源状况的基础，可为制定有效的物种保护政策提供理论依据。以东太平洋金枪鱼延绳钓兼捕记录的802尾 (雌性 316尾，雄性 486尾)镰状真鲨为研究对象，实验随机采集67尾 (雌性 35 尾，雄性 32 尾)脊椎骨样本，通过切片法和草酸铵结晶紫染色法鉴定年龄，建立最适生长模型。结果显示，延绳钓兼捕的东太平洋镰状真鲨以全长160~220 cm，年龄9~15龄个体为主，雌、雄最大观测全长分别为222.58和233.47 cm，最大年龄分别为18龄和17龄，雌、雄逆推全长的最适生长模型均为Logistic模型，其中雌性

Perspectives on elasmobranch life-history studies: a focus on age validation and relevance to fishery management

As a pelagic shark species, the silky shark, Carcharhinus falciformis, in the Eastern Pacific has been overfished in the tuna purse-seine and longline fishery and requires improved assessment to enable planning of recovery actions. The present study examined the life history of 802 silky sharks (67 individuals were sampled, 35 females and 32 males) from the Eastern Pacific. Age was analyzed using sectioned vertebrae, and a multimodel approach was applied to the length-at-age data to fit growth models. Silky sharks ranged in dominant length from 160 to 220 cm total length (L), while ranged in dominant age from 9 to 13 years. Females the longest was 222.58 cm total length, with the oldest estimated at 18 years. Males the longest was 233.47 cm total length, with the oldest estimated at 17 years. The Logistic growth model provided the best fitting growth model. Parameter estimates for females were: asymptotic length (L_∞) = 231.51 cm; growth coefficient (g) = 0.19/a; and length at age 0 (L₀) = 68.89 cm. For males, the parameter estimates were: (L_∞) = 251.96 cm; (g) = 0.15/a; and (L₀) = 68.71 cm. Females matured at (13.50±0.43) years and (207.60±2.43) cm, whereas males mature at (13.42±0.46) years and (200.67±3.60) cm. The growth parameters and late ages of sexual maturation for silky sharks in the Eastern Pacific suggest a significant risk from fisheries exploitation without careful population management.