Trophic Guilds of the Eastern Chukchi Sea Demersal Fish Community

Fishes are an important link in Arctic marine food webs, connecting production on lower trophic levels to apex predators. There are few studies examining the trophic ecology of demersal fishes in the Chukchi Sea. We analyzed 1,607 stomach samples from 21 fish species collected during a trawl survey of the eastern Chukchi Sea in the summer of 2012. A convenient method for summarizing food habits data for a large number of species is grouping those species exploiting the same resources into trophic guilds. We identified four distinct trophic guilds using cluster analysis of diet similarities: gammarid amphipod consumers, benthic invertebrate generalists, fish and shrimp consumers, and zooplankton consumers. The trophic guilds reflect dominant prey types in predator diets. We used constrained analysis of principle coordinates (CAP) to determine if any variation within the composite guild diets could be explained by a suite of non-diet variables. All CAP models explained a significant proportion of the variance in the diet matrices, ranging from 5 to 19% of the total variation. Important explanatory variables included bottom temperature, latitude, longitude, and predator length. These results indicate a trophic guild structure is present during summer within the demersal fish community of the eastern Chukchi Sea.