Feeding Composition of Grayling Thymallus sp. in the Middle Reach of the Yenisei River

Abstract

In 2004 and 2009-2010 we studied the composition of the grayling stomach content from the middle reach of the Yenisei River. The food composition included insect larvae, pupae and adults, centipedes, crustaceans, oligochaetes, gastropods, fish eggs, plant seeds, stones and trees segments. In terms of mass, the ration consisted mostly of amphipods (Philolimnogammarus viridis, Philolimnogammarus cyaneus; Pallasea cancelloides), caddisfly larvae and pupae (Apatania crymophila), and chironomids (Cricotopus bicinctus, Diamesa baicalensis, Prodiamesa olivacea, Chironomus sp.). During a year the ratio of major food components changed considerably. Amphipods were the main food of grayling in summer and autumn, while in winter and spring the fish generally fed caddis fly larvae and pupae. Relatively high fullness of graylings intestines proves the sufficient availability of nutrition sources for this representative of fish fauna in the middle reach of the Yenisei River and coincides with modern condition of the food sources.

Keywords

• Thymallus
• Apatania
• Philolimnogammarus
• grayling
• Thymallus
• food composition
• zoobenthos
• amphipods
• cadisflies
• Apatania
• Philolimnogammarus