Reproduction of mykiss Parasalmo mykiss in the Kol river (Western Kamchatka) and its controlling factors

For the first time, special traits of the reproduction of mykiss Parasalmo mykiss in Kamchatka are studied: dates of spawning, localization, topography and hydrology of spawning grounds, structure and fractional composition of ground of redds, duration of incubation and larval period, and thermal conditions. Possibilities of reproduction of mykiss are constrained by a narrow range of variation of spawning conditions. Spawning occurs only in tundra rivers and tributaries. The principal factor limiting reproduction of mykiss is temperature, namely a rapid warming of water in May and attaining of a necessary sum of degree-days (over 500, from the middle of May until the middle of July) during spawning and the period of incubation. Presence of water bodies of the tundra type with their special thermal conditions predetermine a possibility of reproduction of mykiss in Kamchatka and its present-day comparatively narrow area in Asia.