Heterogeneity of Biochemical Parameters of Non-Native Pink Salmon Oncorhynchus gorbuscha Spawners at the Beginning of Up-River Movements

In the last decades, non-native pink salmon Oncorhynchus gorbuscha successfully spread and occupied the rivers of the White Sea basin. We studied twenty-two blood parameters characterizing lipid metabolism, osmoregulation, energy exchange, and steroidogenesis at the crucial time point of pink salmon spawning migration: the passage of the critical salinity barrier in the estuary, preceding the migration upstream of the Umba River. The heterogeneity of biochemical parameters of non-native pink salmon predominantly was demonstrated in sexual dimorphism. We attributed this result to two main processes: maturation features and different timings of fish running from seawater to freshwater. Maturation features were characterized by differences between females and males in concentrations of estradiol-17β, triglycerides, and alanine aminotransferase. Both sexes had increased levels of cortisol due to changes in fish osmoregulation. Females had higher levels of cortisol, total protein, and calcium in comparison with males, which indicated that pink salmon females run to the river later than males.