Interannual variability in the age composition, body size, and growth rate of the spawning stock of the Anadyr nelma Stenodus nelma from 2000 to 2022 has been studied. The obtained data have been compared with the results of previous studies. The length and body weight of individuals in all age groups significantly decreased in the 2000s compared to 1972–1997, while the age composition shifted toward a higher proportion of younger individuals. One of the most important mechanisms maintaining high production rates of freshwater fish in the rivers of Russian Northeast is allochthonous organic matter introduced from the ocean by salmon (Oncorhynchus) and utilized in the river ecosystem. The abnormally high temperatures observed in northern latitudes over the past decade positively affect the growth of immature nelma. During the research period, a steady decline in the abundance of nelma spawning stock along with its juvenation, a reduction in the age range, and a predominance of first-time spawners, have been revealed.
A. V. Shestakov (Sun,) studied this question.