Downstream migration of Kamchatkan mykiss's juvenilies, Parasalmo mykiss (Walbaum) from the tributaries of Utkholok and Kol rivers, Western Kamchatkaстатья
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Дата последнего поиска статьи во внешних источниках: 29 мая 2015 г.
Аннотация:Downstrem migration patterns in Kamchatkan mykiss juveniles were studied in tributaries of the Utkholok and Kol rivers in western Kamchatka: the seasonal and daily dynamics of downstrem migration, the size, age and sex composition of downstrem migrating fish. In both tributaries, the downstrem migration of juvenile mykiss begins when the water temperature rises above 9oC and proceeds as it gradually increases. Juvenile mykiss migrate predominantly in the dark period of the day. Two groups are identified among the downstrem migrants: (1) smolts arriving from tributaries which pass through the principal (mainstream) river to the sea; (2) parr which leave the spawning grounds in tributaries and distribute themselves throughout the freshwater system. Parr are represented predominantly by individuals of junior age, while smolts by older-aged individuals. The downstrem migration of mykiss underyearlings was also recorded. The data from a quantitative census of the downstrem migration of mykiss juveniles and of other salmonids are presented here. Also discussed are the characteristics of downstrem-migrating juveniles of mykiss from tributaries in rivers of different types, including consideration of the ptoblem of diversifying the life strategy.