Estimating the Diets of Fish Using Stomach Contents Analysis and a Bayesian Stable Isotope Mixing Models in Sendai Bay

Food web structures are well-studied, central theme of fisheries science that depicts the pathways of energy flow. Researchers have long been studied on the importance of quantitative estimation of the relative contribution of prey animals in fish by stomach contents analysis. However, this analysis requires experienced technique, and it only reflects recent diets. On the other hand, carbon and nitrogen stable isotope ratios representing average feeding habits and trophic position have become a powerful tool in food web analyses. In this study, to clarify the main resources (feeding habits) and contribution rate of prey animals using these two analyses in Sendai Bay. As a result, the feeding habits by stomach content analysis of dominant ten fish species were classified into four groups; fish feeders, crustacean feeders, benthic feeders and plankton feeders. A dual isotope plot of δ13C and δ15N values supported the classification by stomach content analysis. Most of fish feeders depended on bait fishes (mainly feeding on plankton feeders), and crustacean and benthic feeders depended on crustacean and/or benthos. The contribution rate of prey animals by mixing models for δ13C and δ15N within Bayesian framework, Paralichthys olivaceus in June 2012 was 67% Engraulis japonicus, and 32% Ammodytes personatus. The results of stable isotope analysis were well consistent with the stomach contents analysis.