Age structure and growth of resident kokanee Oncorhynchus nerka of natural and introduced populations in lakes of Kamchatka

The analysis of growth of kokanee Oncorhynchus nerka demonstrated that there are differences in several indices between the natural population of Kronotskoe Lake and artificial populations of Tolmachevskoe and Klyuchevoe lakes. The highest specific rate of growth was recorded for individuals in Kronotskoe Lake; the lowest, in Tolmachevskoe and Klyuchevoe lakes (in 2006). For the Tolmachev kokanee, a multiyear tendency for a decrease in the gain of scales in generations was found, which is determined by the persisting formation of the population and the depletion of food resources. A considerable effect on the process of formation of the Tolmachev population of kokanee is made by commercial activity and the related transformation of the lake into a reservoir.