Hydroacoustic Studies of the Migration of Anadromous Rainbow Trout Parasalmo mykiss (Salmonidae) in the Kvachina River (Western Kamchatka)

The NetCor research hydroacoustic system has been used to study the anadromous migration of the rainbow trout Parasalmo mykiss (Walbaum, 1792) in the Kvachina River (Western Kamchatka) during its autumn entry from the sea. The intensity of the fish movement increases in similar periods of the neighboring years (2010–2011), which indicates the cyclical migration of the species associated with changes in temperature and water level in the river. The daily dynamics of the movement is characterized by two periods of increased intensity of migration: the first is timed to dawn, while the second begins in the evening hours. The extrapolation of the obtained data provides the estimated numbers of the rainbow trout abundance in the river: 9832 and 2855 individuals in 2010 and 2011, respectively. The difference in the abundance of anadromous rainbow trout in the neighboring years probably results from the peculiarities of the geomorphology and hydrological regime of the river.