Long-term changes in the species composition and abundance of commercial fish in the ichthyoplankton of the eastern part of Peter the Great gulf (Sea of Japan)

Our study provides an analysis of the ongoing seasonal and interannual changes in ichthyoplankton in the eastern part of Peter the Great Bay (Sea of Japan), based on own data on the species composition and abundance of ichthyoplankton in the summer season in 2011–2012 and from autumn 2022 to spring 2024, and published data for the 1950-s and 1980-s and 2007. In the warm season, three periods with a characteristic composition and proportion of the studied species are clearly distinguished in the studied water area: 1. late spring (April–May), 2. early summer (June, occasionally May and July), 3. late summer – early autumn (July–October). 2023–2024 are characterized by a high, gradually decreasing share of pollock egg in catches in the spring period due to spawning individuals of the productive generation of 2014. Also noted is the appearance in ichthyoplankton, in noticeable quantities, of chub mackerel egg and, for the first time since the end of the last century, sardine, which indicates the imminent, previously predicted, next surge in the number of its population in the Japan Sea to a commercial level in the waters of Primorye. Reproduction of spring-summer spawning flounders, despite their fairly high share in catches, is currently at a low level compared to the 1950s and 1980s.