Analysis of 2021 Pacific salmon fishing season in the Far East of Russia is presented. It is based on data obtained from the Department of Anadromous Fish of Russia and the Far Eastern branches of the FSBSI «VNIRO», as well as the Far Eastern Territorial Administrations of the Federal Agency for Fisheries. Causes of discrepancy between forecasted and actual harvest of Pacific salmon are revealed. Proposals for improving Pacific salmon fishery management of and its scientific support are presented.

The article analyzes the sea trawl surveys on pink salmon and their interrelation with the values of pink salmon returns to the main spawning water bodies of the Bering and Okhotsk Seas. According to the fall trawl surveys in the Bering and Okhotsk Seas, the number of juvenile pink salmon was 1.05 and 2.10 billion, respectively. These estimates supposed return of 200 mln pink salmon in 2021 in the Bering Sea (catch — 160–180 thousand tons, 50 mln — pass to spawning groungs), 200–270 mln in the Sea of Okhotsk (catch in the western Kamchatka — 200– 250 thousand tons, 50 mln — pass), Mainland coast of the Sea of Okhotsk — 20–30 thousand tons, 13 mln — pass, eastern Sakhalin and Kurils — 20–25 thousand tons, 5–10 mln — pass). Results of summer trawl surveys of prenadromous pink salmon showed high level winter survival and confirmed earlier returns estimations. The actual pink salmon catch in the Sea of Okhotsk and Bering Sea basins of the Far East was 424.000 tons, which was close to the overall average forecasted catch of 418.000 tons. The Pacific salmon catch in the TINRO area of responsibility (Primorsky Krai and Chukotka AD) was 5.711 thousand tons (5.496 thousand tons — Chukotka AD, 0.215 thousand tons — Primorsky Krai).

Data on forecasted catch, catch and effective catch utilization are presented for Pacific salmon and char. Also, analysis of fishing activities and their characteristics in 2021 is carried out. Quantitative estimates of spawners abundance, migration timing in rivers and catch dynamics are provided. Factors that drive expected and observed runs are considered. Efficiency of complex measures to support natural Pacific salmon reproduction is estimated. Preliminary forecast of Pacific salmon and char stocks for Khabarovsk Territory in 2021 should be acknowledged as generally satisfactory (reliability — 65.6 %). Several quota underutilization cases were linked to seasonal fishing restrictions and fish migrations peculiarities. Positive dynamics of fish at spawning grounds and incubation volumes at salmon hatcheries is elucidated. This supports prolongation of restrictions implemented in recent years.

Ctenophores, hydroid jellyfish, appendicularians, salpas, and the pteropoda mollusk Clione limacina, conditionally combined into the group of “jellyfish”, are found in the food of all Pacific salmon — chum salmon, pink salmon, sockeye salmon, coho salmon and chinook salmon, but only in chum salmon their share is most significant, which is shown both absolute criteria (CHIN-private index of gastric filling of certain species and groups of jelly beans) and relative (share of jelly in the total INJ-general index of stomach filling). In food, chum salmon were present in 45.0 % of samples, pink salmon — 11.0 %, sockeye salmon — 7.0 %, coho salmon — 3.3 %, chinook salmon — 1.1 %. Chum salmon is well adapted to nutrition with jelly, because. has a stomach many times larger than that of other salmon, and in the diet of gelatinous it takes first place among them. Thus, in the event of a shortage of the main food (crustaceans, fish, squid), the chum salmon, due to the ability to consume and assimilate low-calorie food in large volumes, receives additional benefits in competitive relations with salmon and other pelagic fish.

The results of trawl surveys in the Sea of Okhotsk and in the Pacific waters of Kuril Islands at the R/V «Professor Kaganovskii» in the winter 2021 are analyzed. These studies provide data on spatial distribution, abundance and biomass of fishes, cephalopods and jellyfishes in the epipelagic layer of the Sea of Okhotsk and in the Pacific waters of Kuril Islands The analysis of the contemporary status of epipelagic nekton communities of the Pacific waters and one of the Okhotsk Sea near Kuril Islands is provided. Quantitative distribution and biological state of all Pacific salmon in the winter season is reviewed in full detail.

The results of trawl surveys at western part of Bering Sea and Okhotsk Sea at the R\V «TINRO» and R/V «Professor Kaganovskii» in the fall 2021 are analyzed. These studies provide data on spatial distribution, abundance and biomass of fishes, cephalopods and jellyfishes in the epipelagic layer of the Bering and Okhotsk Seas. The analysis of the contemporary status of epipelagic nekton communities of the Bering and Okhotsk Seas is provided. Quantitative distribution and biological state of juveniles of pink salmon in the autumn season is reviewed in full detail.

As a result, of a trawl survey performed in the Pacific waters of the Kuril Islands within the EEZ of the Russian Federation and outside the external border of the EEZ of the Russian Federation, the abundance and biomass of all representatives of nekton and macroplankton were determined. Peculiarities of the spatial distribution of massive representatives of pelagic nekton and jellyfish were revealed. According to the summer survey of the upper epipelagic layer of the Pacific waters, the abundance and biomass of Pacific salmon during their pre-anadromous migrations to the rivers of the Okhotsk Sea basin were taken into account and the main concentrations of mature pink salmon were outlined. During the survey, data on the biological state of salmon in mixed clusters were obtained and preliminary spatial differentiation of the early and late pink salmon stock belonging to different regions of the Okhotsk Sea was performed.

In this paper, a mathematical model is constructed that reflects the dependence of the distribution of autumn chum salmon along the spawning tributaries stream of the Amur River from fishing on the tracks of an extended anadromous migration.

 This article discusses changes in the biomass of taxa of trawl macrofauna during the day in the upper epipelagial of the northwestern Pacific Ocean. Information from the database «Marine Biology» No. 0220006765 in the state register was used, flights to the NIS «Professor Kaganovsky», NIS «Professor Levanidov» and NIS «TINRO» during the pre-airfield migrations of Pacific salmon in May-July 2004–2020 in the amount of 1,471 trawls in the water area of more than 1 million km² . It has been established that the period of years 2004–2013 is the «pre-sardine epoch», and since 2014 — the next «sardine epoch». The average water surface temperature was higher in the «pre-sardine epoch» than in the «sardine epoch» 7.2 ^oC versus 7.1 ^oC. At night (19-07 hours), the average number of taxons in the catch increases, the Simpson index and average body sizes decrease. Only 5 out of 140 taxa do not change their specific biomass during the day: Aequorea sp., Chrysaora melanaster, Oncorhynchus gorbuscha, O. keta и Phacellophora camtschatica. The following 16 taxa are never found in daytime catches: Benthalbella dentata, Ceratoscopelus warmingii, Diaphus theta, Icichthys lockingtoni, Lipolagus ochotensis, Notoscopelus japonicus, Tarletonbeania crenularis, Trachipterus ishikawae, Lampanyctus jordani, Desmodema lorum, Nemichthys scolopaceus, Stenobrachius leucopsarus, Symbolophorus californiensis, Arctozenus risso, Leuroglossus schmidti, Chiroteuthis calyx.

The number of salmon offspring depends both on the number of parents and on the conditions of reproduction. In case of random deviations of reproduction conditions from the average long-term values, classical «stock–recruitment» models are usually used. Based on simulation modeling, it is shown that with directed climate changes, the use of such models leads to significant errors in the forecast of the recruitment. For such cases, the necessity of using models that take into account the trend component of the variability of reproduction conditions is justified.

In Lake Tunaicha mainly artificial reproduction of chum salmon is carried out. The escapement is at a high level — more than 1 million fish. Significant pre-settlement mortality of chum salmon has been regularly observed in the lake basin over the last three years (2019–2021). The scale of fish mortality was estimated based on the results of surveys of the lake, including those carried out with the help of UAVs. The data of fishing statistics, the filling of natural spawning grounds and the features of spawning chum salmon migration were analyzed. The sea surface temperature (SST) data was used. To assess the hydrochemical conditions in Lake Tunaicha during the period of mass entry of chum salmon spawners in 2019–2021, water samples were taken in the coastal area of Lake Tunaicha and in the estuarine sections of the rivers of its basin. The coastal marine fishery cannot keep up with the withdrawal of the commercial part of chum salmon return (no more than 10 %), and most of the fish migrate from the sea to the lake through the Krasnoarmeisky Strait. Before entering the rivers the chum salmon spends a long time in the lake (average of 11 days), and significant accumulations of chum salmon create a danger of fish mortality due to unfavorable hydrological conditions (low oxygen content, high water temperature), especially in shallow areas with an abundance of aquatic vegetation. It is necessary to organize the withdrawal of chum salmon brood stock surplus in the basin of Lake Tunaicha. Taking into account the nature protection status of the lake, this is only possible to implement in the Krasnoarmeisky Strait at the Okhotsk salmon fish farm fish accounting barrier. It is recommended to remove 50 % of the spawning chum salmon there from the beginning of its mass migration in the strait — from September 11.

Following the results of quantitative assessment in the Malaya Khusi river, total number of seaward migrating pink salmon fry was 0,22 mln. Extremely low number of pink salmon fry is is due to unfavorable environmental conditions during embryonic and larval development. Seaward migration of pink salmon fry started 10 days later relative to the long-term average. Previously, pink salmon alevins, physiologically unprepared for migration to the sea, were washed out of from ground affected by massive flood. The maximum of intensity of migration occurred on June 20–21. Variation in the intensity of migration under stable hydrological conditions was determined by fluctuations in water temperature. Migration of pink salmon took place at the dark time of the day. Average body length and weight of seaward migrating pink salmon fry increased slightly during migration. The proportion of fish with a residual yolk sac varied significantly. By the end of the migration period, individuals which began to feed in fresh water were found among seaward migrating fry.

This paper presents the results of a comprehensive hydrologic-ichthyological route survey of the main part of the Gorodskaya River channel (Paramushir Island, Northern Kurils, Sakhalin Oblast) conducted in June 2021. The purpose of this survey was to determine the presence of native ichthyofauna components and to clarify a number of hydrologic and hydrobiological characteristics of the Gorodskaya River. As a result of the route survey, no ichthyofauna components were found in the waters of the Gorodskaya River; a number of bathymetric and hydrologic characteristics of the surveyed watercourse were updated in the course of the work.