2019年夏季西白令海狭鳕胃含物组成及其影响因素

基于西白令海外陆架水域的狭鳕(Gadus chalcogrammus)样本，分析了西白令海夏季狭鳕胃含物组成，采用广义狄利克雷多项分布模型(generalized dirichlet-multinomial model, GDM)分析了胃含物组成的影响因素。研究结果显示，狭鳕胃含物主要由5种浮游动物类群组成，即磷虾类、端足类、桡足类、毛颚类和甲壳动物幼体。其中，磷虾类和桡足类数目最多，占狭鳕胃含物浮游动物数量的85%。狭鳕存在同类相食的现象，约占29%,同类相食的狭鳕个体胃含物中浮游动物的数量明显减少，且体长大于50 cm的狭鳕个体胃含物中几乎仅摄食同类。GDM模型结果表明，狭鳕性腺指数(gonadosomatic index, GSI)与胃含物质量对胃含物组成具有较为显著的影响，胃含物中端足类、桡足类和磷虾类3种浮游动物的数量占比随性腺指数增加逐渐减少，随胃含物质量增加而增加。研究结果可为进一步探讨白令海食物网结构提供基础数据。

Composition of stomach contents and its influencing factors of walleye pollock (Gadus chalcogrammus) in the western Bering Sea in summer 2019

In order to understand the factors influencing feeding habit of walleye pollock (Gadus chalcogrammus) in the Western Bering Sea, the stomach content composition of walleye pollock collected from the western Shelf of the Bering Sea during summer2019 were analyzed, and the factors influencing stomach contents composition were analyzed using the generalized Dirichlet multiple distribution model (GDM). A total of five zooplankton taxa, Euphausiacea, Amphipods, Copepods, Chaeteognths, and Crustacean larvae, were identified in the stomach content of walleye pollock, of which Euphausiacea and Copepods accounted the most for 85% of the zooplankton. Cannibalism was prevalent in 29% walleye pollock, in which the number of zooplankton in the stomach reduced with increasing of cannibalism, and walleye pollock with standard length over 50 cm almost only preyed on walleye pollock. The results of GDM showed that gonadosomatic index (GSI)and stomach content weight of walleye pollock had a significant effect on the stomach content composition. The proportion of Amphipods, Copepods and Euphausiacea in stomach content of walleye pollock decreased with the increasing of GSI, while it increased with the increasing of stomach content weight. The results of this study can provide basic data for further study of the food web structure in the Bering Sea.