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

Abstract:

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.