Intraspecific structure, abundance, and survival rate of marked hatchery pink salmon Oncorhynchus gorbuscha of the Far East based on data of trawl surveys in the Sea of Okhotsk basin and Northwestern Pacific Ocean in 2022–2024

The intraspecific structure (regional origin), spatial distribution, relative abundance, and survival rate of hatchery pink salmon (from salmon hatcheries of the Russian Far East) in the Sea of Okhotsk basin (fall 2022 and 2023) and in the waters near Kuril Islands of the Northwestern Pacific Ocean (summer 2023 and 2024) were estimated. The hatchery origin was identified based on results of otolith marking. Material for the research included otolith samples collected during trawl surveys in the waters mentioned. Potential survival rate of hatchery pink salmon of the Sea of Okhotsk basin during marine/oceanic feeding was estimated based on comprehensive information on the regional composition and relative abundance of pink salmon from different hatcheries in the trawl catches. Results indicate that survival rates during the period from release to migration into the open waters of the Sea of Okhotsk ranged from 30–70%, and it is 20–25% for the period from leaving the Sea of Okhotsk until coming back to the coastal waters of the Northwestern Pacific Ocean. The overall survival rate of hatchery pink salmon for the life cycle from release to return into the coastal waters of the Northwestern Pacific Ocean is 5–15%.