Analysis of satellite-derived sea surface temperature data from 1998 to 2023 reveals distinct spatiotemporal variations in thermal conditions along the coast of the Iturup Island. The interannual variability is most pronounced in summer temperature maxima with fluctuations, reaching approximately 5°C. Decomposition of temperature fields, using empirical orthogonal functions, identifies spatially segregated zones influenced by the Sea of Okhotsk and Pacific waters. The temporal modes reflect a notable climatic shift around 2012–2013, which testifies to a significant reorganization of the thermal regime during the Pacific salmon fishing season. While extreme temperature anomalies in waters adjacent to the Iturup Island are generally rare, they were observed across nearly the entire study area in 2023. The correlation analysis between sea surface temperature and catch data for pink (Oncorhynchus gorbuscha) and chum (Oncorhynchus keta) salmon suggests that thermal conditions during juvenile migration and prespawning periods may affect interannual fishery dynamics in the Iturup Island region.
Tskhay et al. (Wed,) studied this question.