Distribution of Fish and the Biotopic Structure of the Basin of the Small Salmon River (the Nachilova River, Western Kamchatka)

摘要

For one of the small Western Kamchatka rivers, according to the combination of several characteristics (watershed, channel slope, water abundance of the flow, pattern of bottom sediments), the classification of channel processes was performed, and on its basis, six biotopes successively replacing each other from the effluents to the mouth were separated. It was shown that against the background of relatively stable conditions of the summer-autumn period, an independent population of Salmonoidei, an assembly, is formed within each biotope. This is manifested in specific features of species composition, size and age structure, and the density of populating biotopes. The stability of the distribution of fish population is supported by constant species composition in particular biotopes over three years and by a comparatively high level of residence of the dominant salmon species.