Variability of biological indices and abundance dynamics of the Ozernaya River sockeye salmon Oncorhynchus nerka (Walbaum) stock in the modern period (1971–2020)

Abstract

Results of analyzing the spawning sockeye salmon age structure, length-weight composition and absolute fecundity are demonstrated for the Ozernaya River stock. In the course of maturation the sockeye salmon individuals can return into the Ozernaya River for spawning in the ages 3+, 4+, 5+, 6+ or 7+. A positive trend has been figured out for relative abundance of the 5+ and 6+ sockeye salmon individuals and generation abundances, a negative trend – for the 4+ individuals. Negative dynamics has described for the averaged length-weight indices and the mean absolute fecundity of sockeye salmon of the Ozernaya in the research period. Patterns of changes in biological indicators of the fi sh depending on density factors in the period1971–2020 have been identified.