The Food of the Grayling (Thymallus thymallus), Flounder (Platichthys flesus), Roach (Rutilus rutilus) and Gudgeon (Gobio fluviatilis), with Special Reference to the Tweed Watershed

Abstract

In the stomach contents of grayling taken in Sept., Chironomid larvae and pupae constituted half the total number of individuals; Baetis nymphs, Elmidae larvae, and Simulium pupae and imagines were important groups. Bottom foods comprised 94.5% of the food eaten and surface foods the rest. Fish taken in other localities in other mos. had consumed similar foods with some variation. The food of flounders consisted almost entirely of the inactive Chironomid larvae and pupae, being so restricted by the small size of their mouths, their feeding habits, and their inability to move rapidly. Roach in Sept. and in May, when they occur in shallow weedy regions of the river, had consumed mostly plants, chiefly Oedogonium, Cladophora, and diatoms. Gudgeon taken in the River Till in May were feeding to a limited extent on these same kinds of plants and on some bottom-living animals. Feeding in these last 2 spp. probably decreases with the approach of the spawning period.