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%.

The article represent analysis of the influence of a complex of climate and oceanological factors during winter and spring feeding of pink salmon in the Bering Sea and adjacent waters of Northern Pacific Ocean on formation of the abundance of pink salmon returns (runs) in North-East Kamchatka. The factors analyzed included sea/ocean surface temperature anomalies (SSTa) in the areas of wintering and early prespawning migrations of examined group of stocks of the species and several regional climate indices: WP (the West-Pacific oscillation), PDO (the Pacific decade oscillation), AO (the Arctic oscillation) and NPGO (North-Pacific gyre oscillation). The SSTa, WP and PDO were estimated as the most significant predictors. As a result of the research there were multivariate prognostic models of the type “stock-recruitment” or “ocean accounts – return” made taking into account the climate and oceanological factors. Operational improvement based on these models get applicable to correct long-term forecasts of the abundance of pink salmon returns in North-East Kamchatka right before salmon fishing campaign.

Genetic structure of sockeye salmon population in the Kurile Lake was examined for 9 microsatellite loci. Average estimates of heterozygosity for different loci ranged from 0.260 to 0.906. Pairwise differentiation (F_st) analysis showed differences between samples of different seasonal forms only. The results of the study based on Bayesian clustering of samples in the software package “Structure” allowed us to identify two clearly separating clusters coinciding with the separation of samples by spawning time. The results revealed that all samples of the early run had passed the bottle-neck stage. The observed decline in stock abundance is most likely relatively recent.

One of possible approaches to modeling sockeye salmon age structure dynamics in the Ozernaya River (Western Kamchatka) is analyzed. The model discussed is a kind of statistical cohort model for mentioned stock unit. Using the abundance of juvenile escapement and the data on the age structure of spawners in the catches and in spawning grounds it allows under given conditions to obtain retrospective abundances for all age groups of sockeye salmon, to evaluate mature stock and to make probabilistic forecast for sockeye salmon run in the Ozernaya River for a short-term feature period (1–2 years).

Data on species composition and spatial distribution of zooplankton in spring months in Kronotsky Gulf in 2018, 2019, 2021 and 2023 are provided. It is found, that Copepods make up the main group in the abundance and biomass of zooplankton community. Neritic and oceanic zooplankton species persist in the gulf not isolated, what is due to their migrations and adaptations to environmental conditions. Zooplankton distribution in the waters of Kronotsky Gulf is regulated by coastal aquatic circulation and Kamchatka Current.

The taxonomic composition of the bottom fauna was identified on the data of dredge survey carried out at 11 stations in 2002 in Kamchatka Gulf at depths of 24–200 m. The distribution of macrozoobenthos biomass and its taxonomic structure are compared with the data of 1950s and 1986. The distribution of biomass and taxonomic structure of macrozoobenthos are given in comparison with the data of 1950s and 1986. It is shown that on the bottom areas surveyed in 2002, coinciding with the bottom areas studied earlier, faunal complexes identified by biomass have a similar appearance and comparable biomass. Thus, the highest biomass of macrozoobenthos was observed in the southwestern part of the gulf, the lowest – in the desalinated area near the mouth of the Kamchatka River. The distribution of bottom communities was highly mosaic.

Based on survey data from 2014 and 2021–2023, the boundaries of increased concentrations of commercial male opilio snow crab in the Shelikhov Gulf of the Sea of Okhotsk were outlined. The northern boundary of the king crab fishery in the 2023 fishing season was figured out based on the SDR (ship’s daily report) data. It was found that the distance between the opilio snow crab aggregations and the northern boundary of the king crab fishery in the West Kamchatka subzone is 48–51 miles, which is half the distance from the traditional opilio snow crab fishing grounds located near the boundary line between the Northern Sea of Okhotsk and West Kamchatka subzones along 153°30´ E. The data obtained will make it possible to significantly reduce non-productive losses of fishing time and more rationally utilize the resource base of the domestic crab fishery.