文摘
Feeding of different-age juveniles of Salmonidae with a long freshwater period of life (coho salmon Oncorhynchus kisutsch, cherry salmon O. masou, king salmon O. tschawytscha, Dolly Varden char Salvelinus malma, East Siberian char S. leucomaenis, and Kamchatka steelhead Parasalmo mykiss) in the basin of the Kol River (western Kamchatka) in the summer-autumn period was studied. Comparative analysis of their foraging in tributaries of different types, off-channel habitats, and the mainstem of the river in the period of July to September is provided. Spectra of consumed foods, indices of stomach fullness, and degree of food similarity between juveniles of different species and age classes at different sites of the river system were estimated. At each concrete river site and in each concrete period of time, juveniles of the studied species exhibit low selectivity and feed on highest mass and easily accessible groups of food objects. Biotopical determination of feeding is typical of juveniles of all species. In the course of the vegetation period in juveniles of Salmonidae in the basin of the Kol River, frequent change of the consumed food and increase in indices of stomach fullness occur. The results obtained indicate dynamic mosaicism of trophic relations of juveniles of salmonids that formed in the ecosystem of the Kol River.