Abstract Spawners of sockeye salmon caught near the coast of the northern Iturup Island and in the Prostor and Kurilsky bays in July–August, 2021 were investigated. Almost all fish were 1.2+ and 1.3+ years of age, with the former age group being predominant both in females (88.9%) and males (80.0%); the occurrence of other age groups was negligibly low. Older individuals of both sexes were significantly larger. Since Iturup Island sockeye spend only 2 years at sea, both females and males have lower weights than sockeye spawners from other stocks that inhabit the Russian Far East. It is suggested that the shorter the maturation period is, the higher the chance of sockeye is to increase its stock abundance under artificial reproduction at Iturup Island.
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