印度洋西南部海域大青鲨生物学特性初步研究

根据我国金枪鱼延绳钓科学观察员2012年10月至2014年9月3个航次在印度洋西南部海域(1°~33°S,40°~75°E)采集的336尾大青鲨的数据,对其生物学特性进行了初步研究。结果表明:雌、雄大青鲨的优势叉长组分别为150~229.9 cm和150~250 cm,雌雄性比符合1∶1,且雌、雄大青鲨叉长无显著性差异;马达加斯加岛北部热带海域兼捕的大青鲨群体组成以大型性成熟个体为主[x=(207.6±30.6)cm],马达加斯加岛东南部温带海域兼捕的群体以中小型未成熟个体为主[x=(170.9±47.1)cm];50%雌性与雄性性成熟个体对应的叉长分别为183.6 cm与182.3 cm;胃含物中以鱿鱼和帆蜥出现频率最高。本文的研究结果可为区域渔业管理组织评估大青鲨种群资源状态提供数据参考。

Preliminary analysis of biology for the blue shark, Prionace glauca, in the southwest Indian Ocean

In this study, we described and analyzed the fisheries biology of blue shark based on the total of 336 samples collected by China''s national tuna long-line fishery observers in the Indian Ocean (1°-33°N, 40°-75°W) from October 2012 to September 2014.The results indicated that the dominant fork length of males and females was 150-229.9 cm and 150-250 cm. The captured female-male ratio was near 1:1 and there were no significant differences between the mean fork lengths of male and female. The larger individuals were mainly distributed in the northern Madagascar waters (x=207.6 cm), while the smaller individuals were mainly captured around the southeast Madagascar waters (x=170.9 cm). The mature individuals of bycatch blue shark were much more dominant in northern Madagascar waters than in the Southeast Madagascar waters. Fork length at 50% maturity was estimated to be 183.6 cm for females and 182.3 cm for males. Squid and long-nose lancetfish had the highest occurrence in stomach contents of the blue shark. This study contributed to a better understanding of fisheries biology of the blue shark in the Indian Ocean and would be useful for evaluating the shark''s resources.