中部大西洋大青鲨胃含物组成及其多样性研究

Composition and diversity of stomach content of blue shark(Prinace glauca)in the central Atlantic Ocean

利用2010年10月-2011年2月、2011年10月-2012年3月期间由科学观察员采集的热带大西洋北部海域(5°N^15°N,25°W^40°W)大青鲨的胃含物样品,研究其摄食特点。结果表明,摄食强度以1级为主,幼鲨与成熟鲨鱼的摄食强度组成有显著差异(P<0.1),但雌性与雄性摄食强度组成无显著差异(P>0.1)。硬骨鱼类是最主要的饵料种类,头足类次之。雌、雄大青鲨摄食的优势种类相同,均为鱿鱼、沙丁鱼、帆蜥鱼和福氏粗鳍鱼。随着大青鲨长度的增加,饵料中头足类的比率和出现频率总体呈下降趋势,硬骨鱼类的比率和出现频率大多呈上升趋势。饵料种类组成的总体Shannon-Weiner多样性指数H=1.70,Simpson优势度集中指数C=0.23。指数H有随着长度增加而升高的趋势,指数C则呈相反的下降趋势。

Based on stomach content samples of blue shark Prionace glauca in the Atlantic Ocean（5°N -15° N, 25 °W - 40° W） during October - February 2010 and October - March 2011, stomach content of blue shark was analyzed. The feeding intensity of blue shark was dominated by level one. The feeding intensities of juveniles and adults were significantly different （ P 〈 0. 1 ） ; while the feeding intensities of females and males were not significantly different （P 〉 0.1 ）. Teleosts were the main preys, followed by cephalopods. Dominant prey species （category） of females was squid, sardine, Longnose lancetfish Alepisaurus ferox and tapertail ribbonfish Trachipterus fukuzakii, same as those of males. Overall, the proportion and frequency of cephalopods in stomach content tended to decrease with blue shark size; while those of teleosts tended to increase with blue shark size. The Shannon-Weiner diversity index （H） of prey item was 1. 7, and the Simpson diversity index （C） of prey item was 0.23. The index H increased with blue shark size, and the index C showed a contrary trend.