Abstract <p>The study investigated potential drivers of interannual changes in pink salmon (<i>Oncorhynchus gorbuscha</i>) abundance in the waters of Iturup Island in 1984–2024 using mathematical models previously validated in studies of pink salmon populations inhabiting regions with continental climate, specifically mainland populations in the Amur River and rivers along the mainland coast of the Strait of Tartary. In contrast to these populations, the abundance of spawners in the rivers of Iturup Island varied little over the years, and the typically maritime climate on the island (mild, snowy winters) favored the successful completion of the embryonic-larval stage of offspring development in spawning redds. Consequently, the dynamics of the pink salmon abundance at Iturup Island was preconditioned primarily by the factors affecting their marine period of life. These results are similar to those obtained previously using different models in the studies of pink salmon inhabiting the areas with a maritime or near-marine climate (the “island” populations of the Kamchatka Peninsula, Iturup Island, and southern Sakhalin Island). A comparison of results derived from a unified methodological approach confirmed that the formation dynamics of pink salmon (<i>Oncorhynchus gorbuscha</i>) year-class abundance are governed by regional reproductive conditions.</p>