Preliminary analysis on the composition of fish and cephalopod in diet of Dosidicus gigas in the high sea of Eastern Pacific Ocean

Abstract

Dosidicus gigas is widely distributed in the Eastern Pacific Ocean and plays an important role in the marine ecosystem. In this study, we identified and analyzed 4131 otoliths and 75 beaks from the stomach content residuals of 62 D. gigas samples, which were collected by Chinese squid jigging vessels in the high sea of Eastern Pacific Ocean from June to December 2019. The results showed that the preys of D. gigas included 10 fish species and 4 cephalopod species. Judging from the frequency of appearance and percentage of amount, Vinciguerria lucetia, Diogenichthys laternatus, and Triphoturus mexicanus were the dominant myctophidae prey of D. gigas. Among those preys, V. lucetia was the most important one, as it was found in all D. gigas with different mantle lengths. D. gigas, Sthenoteuthis oualaniensis, and Onychoteuthis banksii were the dominant cephalopod prey. With the growth of mantle length of D. gigas, the number of prey species, the percentage of cephalopod and myctophidae preys, and the size of preys increased, and thus the trophic level of preys increased as the trophic pattern of preys changed. Our results could provide basic information for evaluating the contribution of different preys in the preying transformation of D. gigas.