Feeding of juvenile Atlantic Salmon Salmo salar L. and its trophic relations with other fish species in rivers of the Barents and White sea drainage basins (Kola peninsula)

Abstract

The feeding patterns of the young Atlantic salmon (salmon) and its trophic relations with members of the resident fish fauna – brown trout, grayling, perch, pike and mature min66 now were investigated in a variety of their shared habitats in rivers of theKola Peninsula. At the same time, the food resources were studied, the hydrological characteristics of selected areas were assessed, and the overall fish distribution density was determined. The species and age compositions of the fish fauna were found to vary among habitats. Underyearlings of Atlantic salmon and brown trout, as well as of the minnow prefer to aggregate (in a mosaic pattern) in large numbers in shallow water areas with low current. Juvenile salmon, brown trout and grayling of older age classes occupy the deeper and fast-flowing part of the watercourse, with a differentiation among horizons – trout and salmon closer to the bottom, and grayling in the pelagic layer. The greatest similarity of the feeding spectra was observed between young Atlantic salmon and brown trout. No cases of competition for food or predation on juvenile salmon by brown trout, perch and pike have been observed. The division of food items, owing to rheophilic species preferring to live separately in relatively isolated hydrological niches, can be considered as a manifestation of adaptation aimed at a more complete exploitation of the food resource in a situation where several species coexist at fairly high densities