东太平洋公海茎柔鱼饵料中鱼类和头足类组成初步分析

茎柔鱼(Dosidicus gigas)广泛分布于东太平洋海域,在海洋生态系统中扮演着重要角色。本研究根据2019年6—12月我国鱿钓生产船在东太平洋公海采集的62尾茎柔鱼样本,对其胃含物残留的4131个耳石和75个角质颚样本进行鉴定分析。结果表明: 茎柔鱼主要摄食鱼类10种、头足类4种。从摄食饵料的出现频率和数量百分比来看,主要摄食的鱼类饵料为荧串光鱼、朗明灯鱼和墨西哥尾灯鱼,荧串光鱼在不同胴长组的茎柔鱼胃内均有出现,是茎柔鱼最重要的饵料;摄食的头足类主要有茎柔鱼、鸢乌贼和爪乌贼。随着胴长的增大,茎柔鱼摄食的饵料种类不断增加,头足类和灯笼鱼饵料比例增加,且摄食的饵料尺寸增大,摄食营养结构发生改变,摄食营养水平随之提高。研究结果可为评估不同饵料生物在茎柔鱼食性转变过程中的食物贡献提供基础资料。

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

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.