An updated concept for the state, dynamics, and production of plankton communities in the upper epipelagic layer of the western Bering Sea is presented based on the timeseries for 1986–2020. The zooplankton biomass in summer exceeded the biomass in fall season in 1.3–2.1 times for the layer of 0–50 m and in 1.1–1.8 times for the layer of 0–200 m, mostly because of decreasing abundance of copepods and chaetognaths that was not compensated by slight increase of the euphausiids and amphipods biomass. Interannual variations were higher and reached 2–3 times and 4–5 times, respectively. Abnormal blooming of certain ecological groups of zooplankton (either warm-water or cold-water) occurred in the anomalous years. Species structure of zooplankton community varied in dependence on oceanographic conditions, generally toward higher abundance in warmer environments. In spite of considerable impact of thermal regime, this dependence was not close and even was absent in some cases that indicated a complex organization of zooplankton communities subjected to influence of many environmental factors. Mean total biomass of large-sized zooplankton and micronekton (prey for large-sized nekton) in the upper epipelagic layer of the western Bering Sea is estimated as 41 . 106 t in summer and 24 . 106 t in fall season, its total production as 101 . 106 t and 67 . 106 t, respectively. In summer, production of non-predatory zooplankton (phyto- and euryphages) prevailed over the predatory zooplankton production, with exception of 2009 and 2013. On the contrary, production of zoophages prevailed in autumn due to successive seasonal changes in the epipelagic plankton communities. These modern data on biomass and production of the zooplankton communities indicate significant reserves of food resources for fish and squids in the deep-water Commander Basin, western part of the Aleutian Basin, and in the area at Cape Navarin.

Interannual dynamics of feeding conditions for nekton in the upper epipelagic layer of the western Bering Sea is considered for the summer and fall seasons of 2002–2020. In the summers, daily consumption by fish and squids ranged from 0.01 to 0.10 t/km² in the deepwater basins and between 0.01–0.38 t/km² in the shelf area at Cape Navarin. In the falls, the consumption increased to 0.03–0.14 t/km² in the deep-water basins, and to 0.01–0.53 t/km² in the Navarin area. Summary in the summer-fall periods, the fish and squids consumed 2–5 % of zooplankton production (up to 5–7 % in some years) in the deep-sea basins that is rather low degree of the zooplankton resources usage. In the Navarin area, the consumption is considerably higher and is estimated as 5 % in summer and 21 % in fall season, on average. In cases of heightened nekton biomass and reduced zooplankton biomass in some years, the grazing pressure on plankton increased, in particular on euphausiids, hyperiids and pteropods, while the intensity of salmon feeding decreased, with extension the portions of nektonic food and other zooplankton groups, as arrowworms, in their diet. On the other hand, the portion of juvenile fish and squids in the salmon diet increased in cases of high abundance of this prey, too. Weak correlation was detected both between the salmon feeding and abundance of their prey and between the salmon feeding and abundance of salmons. The feeding conditions for pink salmon during their offshore migration did not determine the rate of their returns. Strong year-classes of pink salmon had large returns in conditions of either poor or rich food supply in fall season, so the feeding in fall was not important for the pink salmon survival in the ocean in winter. Feeding of other fish and squids species did not change noticeably in the years with reduced food supply. In general, abundance and species composition of plankton and nekton communities were rather stable in the western Bering Sea in the 2000-2010s, and this current state of the ecosystem provides stable functioning of nekton communities both in the deepwater and Navarin areas.

Data of bottom trawl surveys at southwestern Sakhalin and surveys of the herring spawning grounds at southern Sakhalin and Kuril Islands are summarized, with assessment of the spawning grounds size and the eggs density in clutches. Fishery statistics and media reports are overviewed, as well. The stock of the Sakhalin-Hokkaido population increases since 2015, both off southwestern and southeastern coasts of Sakhalin, in the Aniva Bay, and at southern Kuril Islands. Number of the spawning herring increases everywhere within the Russian waters, as well as the size of spawning grounds and the density of eggs laying. In particular, the biomass of spawning herring was estimated in 2020 as 35.5 . 103 t at southwestern Sakhalin and 62.5 . 103 t at southeastern Sakhalin; it was 21.6 . 103 t in the Aniva Bay in 2021; the total catch of herring in the waters at Sakhalin Island and southern Kuril Islands reached 8.3 . 103 t in 2021. The stock of Sakhalin-Hokkaido herring is restoring after long depression, so this species is capable to return to the list of the major objects for fishery in the Sakhalin- Kuril region of Russia.

Annual data on the 1976–2019 year-classes of pink salmon from Iturup Island are presented, as their number on spawning grounds, abundance of wild and hatchery juveniles migrating downstream, and returns of adult fish after the marine period of life. On average, 1.48 . 106 spawners entered annually the rivers of Iturup Island in these years and 237 . 106 fry juveniles rolled down (the downstream migration index was 165 juveniles per conventional producer), plus 133 . 106 juveniles from salmon hatcheries. After fattening in the sea, the annual returns were 16.56 . 106 ind., on average, so the marine survival index was 4.70 %. This is the highest value of the return for the Sakhalin-Kuril region, relative to the area of spawning grounds and to the number of spawners. The year-classes of odd years dominated until the middle 1990s, then the year-classes of even years became more numerous. Biological parameters of fish (body length and weight, fecundity) fluctuated from year to year both for odd and even year-classes, though these parameters averaged for a long period of observation had no difference between the odd and even year-classes, as well as the indices of reproduction efficiency.

Estimations of a poaching catch in the Amur estuary for kaluga and amur sturgeon are presented. Total illegal catch of these species in 2011 and 2016 is amounted as 8,300 and 15,060 ind. or 409.1 and 745.0 t, respectively. The volume of poaching on kaluga and amur sturgeon exceeded in 1–2 orders (in 26–268 times) the legal catch for research purposes and artificial reproduction. The poaching in the Amur is relatively stable through decades.

Data on captures of pond smelt Hypomesus olidus in the basin of Lake Khanka are presented. The list of cyclostomes and fishes recorded in this basin is updated to 90 species belonged to 21 families.

New data on finding of dragonet Draculo mirabilis in Peter the Great Bay (Japan Sea) are presented. This subtropical-lowboreal fish species is rare for this area. One adult specimen (39 mm TL) was found in the Sukhodol River estuary on sandy bottom at the depth of 0.6–0.7 m in September 2021, under the water temperature 20 оC and salinity 27 ‰. An illustrated description of this specimen is presented.

The sockey salmon entry to the Bolshaya River on Zavyalov Island in the northern Okhotsk Sea was registered for the first time on July 26, 2021. Larger specimens were observed among the pink salmon going to spawn in this river, and one of them was caught by a brown bear at a distance of 300 m from the river mouth. It was the female of sockeye salmon Oncorhynchus nerka (Walbaum, 1792); the data on its size and weight are presented.

Plankton survey was conducted in the Chukchi Sea in August-September 2019 by two research vessels: RV Professor Levanidov in the western part of the sea and RV Ocean Starr in its eastern part. Parasagitta elegans dominated everywhere in zooplankton. Beside these arrowworms, species of the arctic and arctic-boreal complex were abundant in the northwestern Chukchi Sea, as Calanus glacialis and other species typical for the adjacent East-Siberian Sea. C. glacialis was numerous in the northeastern Chukchi Sea, too, together with species of the Arctic waters and the Beaufort Sea. The southern Chukchi Sea was occupied by the waters invaded from the Bering Sea, so species of the Bering Sea complex were abundant there, as Eucalanus bungii and Neocalanus plumchrus/flemingeri, at Alaska coast together with neritic species typical for the Alaska coastal water mass. The zooplankton community structure corresponded to the spring phase of seasonal succession in the northern area, whereas to the summer phase in the southern area. Total density of zooplankton was estimated as 65 t/km2 for the northwestern part of the sea, presented mostly by large-sized fraction (56 t/km2) including arrowworms (35 t/km2) and copepods (13 t/km2), and as 48 t/km2 for the southwestern part of the sea, also mostly large-sized fraction (40 t/km2). So high zooplankton density in the western Chukchi Sea is considered as result of the Bering Sea waters advection (previously such abundance was observed in 2008 — 40 and 36 t/km2, when the advection was also active). In the eastern Chukchi Sea, the total density of zooplankton was 44 t/km2 in the northeastern area (including 29 t/km2 of large-sized fraction) and 43 t/km2 in the southeastern area, that was higher than in 2017 (15 t/km2) but lower than in 2007 (49 t/km2). However, different phases of seasonal succession should be noted: summer season in 2019, spring season in 2017, and late-summer season in 2007.

Macrobenthos of soft bottoms on the shelf of two Arctic seas was investigated in the survey conducted aboard RV TINRO in August-September 2015. The area of 32,800 km² in the depth range of 15–34 m was researched in the East Siberian Sea where 13 taxonomic groups of bottom fauna were found, mainly Bivalvia (75.9 % by biomass). The area of 22,500 km² in the depth range of 45–96 m was surveyed in the Laptev Sea, where 20 groups of macrobenthos were identified, with predominance of Polychaeta (34.1 %), Bivalvia (27.7 %), and Sipuncula (21.2 %), by biomass. Significant changes in structure of benthic communities are revealed on the external shelf of the Laptev Sea (below of 70 m), in comparison with the data of previous years, possibly caused by warming of the environments: the previously dominated group of Ophiuroidea was replaced by Sipuncula. Although the dominant groups were widely occurred, their quantitative distribution was neither uniform nor similar. The dominant species had different trophic habits and occupied disjointed zones with domination of sestonophages or detritophages, in dependence on the habitat conditions. The average abundance and biomass of macrobenthos were assessed as 881 ± 174 ind./m² and 149.2 ± 25.5 g/m² in the East Siberian Sea, and 251 ± 32 ind./m² and 71.0 ± 13.0 g/m² in the Laptev Sea, respectively.

Results of two bottom grab surveys in the Olyutorsky Bay of the Bering Sea conducted in 1985 (37 stations with 60 samples in the depth range of 20–200 m) and 2012 (26 stations with 48 samples at the depths of 51–270 m) are compared. Average biomass of macrozoobenthos was rather stable: 561.1 ± 95.2 g/m2 in 1985 and 581.3 ± 94.5 g/m2 in 2012. Sea urchins, bivalves and polychaetes dominated by biomass in 1985 (84.7 % of the total biomass for these 3 groups), but sipunculids appeared in the list of the dominant taxonomic groups in 2012 when 91.3 % of the total biomass consisted of the top 4 groups. The main communities of macrozoobenthos practically retained their location and quantitative parameters. There is concluded that composition, distribution and abundance of macrozoobenthos in the Olyutorsky Bay were stable over a quarter of century.

For successful development of aquaculture, fish farms have to be provided by effective means and methods to prevent and treat diseases of fish. Many drugs are limited for using in aquaculture, so the influence of each particular drug or chemical substance on the fish development should be investigated carefully. Effectiveness of chemical solutions for suppressing the growth of saprolegnium micromycetes on egg membranes and other tissues of sturgeon embryos during their incubation is evaluated. The experiment was conducted at the research and experimental base BIOS belonged to the Russian Res. Inst. of Fisheries and Oceanography, Volga-Caspian branch (CaspNIRKh) located in Astrakhan and included a series of observations on incubation of sturgeon eggs processed with solutions of some chemicals (Purple-K, sodium chloride, hydrogen peroxide) or drug (Iodinol). Two sturgeon species (russian sturgeon and beluga) were tested with measuring biological parameters of their embryos, as survival rate, contamination by saprolegnia micromycetes, number of abnormally developing embryos, and number of obtained prelarvae. The processing with 0.05 % solution of hydrogen peroxide (10 min. exposure) and with 0.90 % solution of sodium chloride (3 min. exposure) showed the best results: these solutions made the lowest negative effect on the embryos survival but reduced significantly infection of incubated eggs.

Previously published results of the study [Khen et al., 2019b] are continued. Long-term changes of the sea surface temperature (SST) in the Far-Eastern Seas and North-West Pacific (NWP) are described for 1950–2019 and their relationship with large-scale climate processes described by climatic indices (AO, Nino 3.4, PDO, ALPI, NPI, PNA, SHI, and WP) is analyzed. SST has increased in all seasons, with higher rate in winter and autumn and less significant trend in summer. A prominent shift to warmer regime occurred in the Bering Sea in 1977 that coincided with a sharp change in dynamics of PDO, ALPI, NPI, and PNA indices. Such shifts were observed in the Okhotsk Sea in 1981 and in the Japan Sea in 1990, one year after the shifts in the time-series of AO, PDO, and PNA indices. Smaller shifts to warming happened in NWP in 2008 and 2018. Pacific Decadal Oscillation is the main contributor to temperature variability in the Bering Sea in all seasons, though the contribution of ALPI and PNA variation is considerable in winter and spring. Arctic Oscillation is the most important for the Okhotsk Sea. Variations of AO, SHI and WP are significant for the SST variability in the Japan Sea. Any single climatic index does not determine the SST variability in NWP, in all seasons. The set of climatic indices can be divided into two categories: western and eastern ones, according to their contribution to SST variability in certain regions. The western group includes AO, SHI, and WP, which contribute mostly to the variations in the western regions, westward from the longitude of Kamchatka. The most important indices in the eastern group are PDO, PNA and ALPI.

Effectiveness of the salmon juveniles feeding was examined during six cycles of fish breeding for pink salmon Oncorhynhus gorbuscha, chum salmon O. keta, cherry salmon O. masou, and coho salmon O. kisutsh at 12 fish hatcheries belonged to the Sakhalin branch of FBSI Glavrybvod with using of different starter feeds produced by Aller Aqua (Denmark) and Aquatech (Russia). All hatcheries worked in the coldwater regime of rearing. Both feeds were rather effective for all species that was evidenced by low feeding coefficients, usually 0.6–0.8. Anyway, average value of the feeding coefficient was lower for the starter feed Aquatech at all factories. Beyond a high quality of this feed, its availability in two variants of flotation was important, as the slowly sinking and floating forms. The floating food was found to be more suitable for the growing juvenile pink salmon at all farms. On the other hand, both starter feeds were suitable for chum salmon, their priority for this species depended on fish farm and obviously was determined by combination of many factors, such as temperature conditions, configuration of canals and ponds, their hydrodynamics, feed dispensers, etc.

Brown algae can be used as raw materials for pharmacological and functional extracts, in particular carotenoids of brown alga Sargassum pallidum are a source for biologically active substances, as a carotenoid fucoxanthin with a wide spectrum of properties useful both for daily preventive consumption and therapeutic diets. Prospects for using S. pallidum as a raw material for extracting the carotenoid fucoxanthin and its further using as a biologically active component in the food industry are considered. The algae were collected in the coastal zone of Peter the Great Bay (Novik Bay of Russky Island) in October 2020, then frozen. Before freezing, the algae were washed and excess moisture was removed. Small pieces of the alga tissue were cut, put into closed packages, and processed for 24 hours by ethyl alcohol with 80 % concentration in a dark place in refrigerator under temperature +7 oC. The obtained alcohol extract was used as a functional addictive for beverages, as iced black tea and juice concentrates. These beverages were examined for organoleptic properties (by the group of 10 experts) and economic value. The apple and red grape juice concentrates with the fucoxanthin extract have the best organoleptic properties. As the final result, technology of functional drinks with alcohol extract of fucoxanthin from brown alga S. pallidum is developed.

Species composition in catches of the ichthyoplankton survey conducted on June 4, 2021 in the periphery of the Tauiskaya Guba Bay (northern Okhotsk Sea) is considered. Eggs of 3 fish species were collected, the portion of alaska place was 1.3 %. Specific pigmentation of the alaska place embryos was defined that allowed to identify reliably the eggs of this species, in combination with other signs.