The pink salmon abundance dynamics is considered for Sakhalin-Kuril region in 2007–2016. The year-classes of pink salmon originated from Iturup Island and four areas of eastern Sakhalin became weaker if they were affected by typhoons during their embryonic development in rivers (spawning nests) or feeding of the juveniles in the coastal sea soon after their downstream migration from the rivers. That means that extreme environmental events are the most important for formation of the pink salmon abundance. The pink salmon runs to these areas in 2017 were successfully modeled using this dependence.

Stock of demersal fish species at the depths of 20–386 m in the northwestern Bering Sea, as well as pelagic and anadromous fishes in the bottom biotopes, are considered on the data of the bottom trawl survey conducted within the West-Bering and Chukchi fishery districts in the summer of 2017. The total accounted biomass of demersal fish was 1756,870 t, including 1578,430 t in the West-Bering and 178,440 t in the Chukchi district. The mean distribution density was similar in both districts: 11331.8 and 10748.0 kg/km², respectively. Pacific cod formed the bulk of the demersal fish biomass — 1227,300 t.  Among other species, the stocks were considerable for flathead sole — 96,310 t, great sculpin — 79,160 t, alaska plaice — 71,200 t, and arrowtooth flounder — 40,630 t, and the summary biomass of all others was 242,270 t. The total biomass of pelagic and anadromous fish species presented in the bottom biotopes was estimated as 3884,150 t, including 3555,930 t in the West-Bering and 328,220 t in the Chukchi district. They had higher distribution density in the West-Bering district — 25527.9 kg/km² vs 19769.9 kg/km2 in the Chukchi district. Walleye pollock prevailed among these species with the total biomass 3884,150 t (assessed with the catchability coefficient for adults k = 0.4), including 36,080 t of accounted yearlings (k = 0.1). Biomasses of other pelagic fishes in the bottom biotopes were 415,380 t for pacific herring, 18,680 t for arctic cod, 920 t for capelin, and 260 t for all others in sum. Comparing these new assessments with the data of analogous survey in 2015, the stocks of pacific herring, rock sole, alaska plaice, and ray Bathyraja parmifera have decreased and the stocks of arctic cod, saffron cod, pacific cod, walleye pollock (both adults and yearlings), flathead sole, and yellowfin sole have increased. Positive and negative anomalies from the standard curves of size composition for some species could be considered as a basement for forecasting of their stocks tendencies in the nearest future.

Fish counts by SCUBA visual methods are conducted in the coastal biotopes at Furugelm and Popov Islands and in the Sivuchia, Kalevala, and Pemzovaya Bays in the western Peter the Great Bay in July-August of 2012 and 2014. In total, 23 fish species were registered on transects at Furugelm Island and 11 species at Popov Island in 2012, and in 2014 — 17 fish species at Furugelm Island, 16 at Popov Island, 9 in the Sivuchia Bay, 6 in the Kalevala Bay, and 11 in the Pemzovaya Bay. Species composition of fish had moderate or high similarity between transects (35 pairs with Sørensen-Chekanowski index 0.3–0.5 and 25 pairs with higher values). The species diversity and its similarity were conditioned by bottom structure and presence or absence of sea grasses and algae. The highest fish biomass was observed in the Pemzovaya Bay (29.2 g/m², mainly large-sized Sebastes schlegelii) and at Furugelm Island (21.2 g/m², mainly S. taczanowskii and nesting males of Hexagrammos otakii), but the biomass values < 10 g/m² prevailed. Generally, the observed fish diversity, density, and biomass are lower in compare with the mid 1990s because of partial degradation of their habitats (disappearance of eelgrass Zostera marina) and water warming that prevents migrations of some coldwater fishes to the shallows. The most prominent decreasing is noted for Sebastes taczanowskii adults and juveniles, previously high abundant on rocky grounds, and for flounders on sandy grounds. So far as the changes of fish abundance and diversity have natural reasons, there is concluded that the effect of protection regime in the marine reserve is insignificant for fish populations.

Pike perch was introduced into Lake Khanka in 1970–1978. The introduction was founded on concept of low commercial productivity of the lake prevailed in those times. For the past 50 years, the species acclimatized successfully in the lake. However, the process of its naturalization was not easy, with periodic disappearance from the catches succeeded by blooms. In recent years, the species became one of the most important objects of commercial fishery. Studies of its ecology show that Lake Khanka environments are rather good for pike perch breeding, in particular the food supply for all stages of its larvae and juveniles. As the result, pike perch in Lake Khanka is distinguished by earlier puberty in comparison with the same species in the Amur River and the Curonian Lagoon. Its adults consume low-valued fish and shrimps abundant in the lake. After successful acclimatization in Lake Khanka, pike perch penetrated through the Sungacha to the Ussuri River by 1985, and further to the Amur where in decade it extended upstream to the Bira tributary and downstream to Yelabuga village. Currently, pike perch is a common species in catches on the middle and low Amur from Blagoveshchensk to Mago, i.e. > 1 500 km from Lake Khanka.

Species composition in 64 catches obtained by fry seine (length 15 m, height 2.5 m, mesh size 5 mm) in the estuaries of the Olga Bay (Primorye) in the daytime in warm seasons of the 2012 and 2013 are analyzed, including 4 catches in the Olga River estuary, 43 in the Avvakumovkа estuary and 17 in the Tihaya Pristan Bight, as the common external estuary of both rivers. In total, 53 taxa of aquatic organisms belonged to 23 families were defined: 49 fish species and 4 species of decapods. The families with the highest species diversity were Cottidae — 7 species, Gobiidae — 5 species, and Hexagrammidae — 5 species. The most common species were Tribolodon spp. (occurrence 92 %), Crangon spp. (66 %), Gasterosteus nipponicus (64 %), and Megalocottus platycephalus taeniopterus (59 %). The species richness decreased in the order: Tihaya Pristan Bight (42 species) — Avvakumovka estuary (29 species) — Olga estuary (11 species). Seven mass species made about 90 % of the total catch: Tribolodon spp., Eriocheir japonica, Megalocottus platycephalus taeniopterus, Platichthys stellatus, Gasterosteus nipponicus, Oncorhynchus keta, and Hypomesus sp. Among them, M. platycephalus taeniopterus and Tribolodon spp. were the most frequent. Species domination by Simpson index decreased in the order: Olga estuary (0.434) — Tihaya Pristan Bight (0.373) — Avvakumovka estuary (0.243). The biomass distribution density was calculated using the coefficient of catchability 1.0. It was the highest in the Tihaya Pristan Bight — 10.1 g/m² and considerably lower in both internal estuaries: the Avvakumovka — 6.1 g/m² and the Olga — 4.9 g/m². The mean density fluctuated in the range of 2.5–8.9 g/m² with the average value of 6.7 g/m². Tribolodon spp., E. japonica, P. stellatus, M. platycephalus taeniopterus, and G. nipponicus prevailed in the freshwater biotopes of the internal estuaries distinguished by low salinity and strong water flow with the mean distribution density 2.5, 0.9, 0.7, 0.6, and 0.4 g/m², respectively. Tribolodon spp., M. platycephalus taeniopterus, H. octogrammus, M. stelleri, L. pinnifasciata, and O. ocellatus prevailed in the marine biotopes of the external estuary distinguished by relatively warm, salty and calm water, shallow depths and thickets of Zostera marina, their mean distribution density was 10.1, 2.7, 0.7, 0.5, 0.4, and 0.4 g/m², respectively.

Abundance and density distribution of four seal species (ringed, ribbon, spotted, and bearded) on spring ice was estimated based on the data from two instrumental aerial surveys in the western Bering Sea in April-May 2012 and April 2013 and compared with the previously published values. The number of ringed seals on ice was about 61,000, they were rather evenly distributed in the southern, middle and northern parts of the Russian EEZ in the Bering Sea. The estimated number of ribbon seals was about 62,000 in 2012, but only 15,000 in 2013. The number of bearded seals was estimated as 42,000 animals. The abundance and density distribution of spotted seals was shown to be a subject of significant interannual fluctuations with the maximum of about 97,000 individuals. The spotted or ribbon seals were not found in the Anadyr Bay, but importance of the Karaginsky Bay for reproduction of the phocid seals was confirmed. A large population of spotted seals was concentrated there and the ringed and bearded seals were presented there in the highest recorded density. Effectiveness of the instrumental aerial survey method application for assessing abundance and distribution of seals on sea ice was demonstrated. However, in order to estimate the real population abundance, it is essential to apply correction coefficients allowing to account for behavioural and migration processes predefining the proportion of seals available for detection.

Linear and weight growth of amur white bream are considered on the basis of von Bertalanffy and Schmalhausen growth equations using the data collected in the Amur River (from Nizhneleninskoe village to the mouth) in 1958–2011. Age was determined for 1703 specimens (672 females and 699 males, sex not defined for others). The main feature of the amur white bream growth is a sexual dimorphism, primarily in the specific growth rate. Generally, females live longer than males. Another important feature is a compensatory growth, that maintains the size of all individuals around the mean level in the age of their pubertation. Mean age of females maturation is 5+...6+ years, when their body length is 27 cm on average. Males mature earlier, in the age of 4+...5+ years. Commercial size of amur white bream is determined as 27 cm that corresponds with the size in the age of mass maturation and the highest biomass of females. The minimum natural mortality coefficient (φM) is determined as 0.249 for females and 0.320 for males, on average. The maximum body length of amur white bream, both in the model and real observations, is 50 cm, the maximum body weight is 2 kg, and the maximum age is 17 years. So, the reports about findings of amur white bream with the length up to 55 cm and weight up to 4.1 kg are doubtful.

Reproduction of the sea urchins Strongylocentrotus intermedius, Mesocentrotus nudus, and the scallop Mizuhopecten yessoensis is considered in natural communities with various algae: red (Gracilaria verrucusa and Tichocarpus crinitus), brown (Sacharina cichorioides), and green (Vulva fenistrata). In these environments, their reproduction is influenced by exometabolites released by macrophytes, so the gametes with different production capacity could be formed and products of metabolism could impede their growth and development. To avoid these negative effects in polyculture, the cultured community should include species of different trophic levels forming a single food chain in which their exometabolites are utilized. The polyculture could be controlled by changing the number of species or influence on them by change of abiotic factors. In artificial polyculture, optimal conditions for reproduction and growth of cultivated species could be created, that provides the maximum production from a limited area.

Two periods are clearly distinguished within the last two decades (1997–2017) by several quantitative parameters of the plankton community in the northern shelf zone of the Okhotsk Sea: the period of high productivity in the 1997–2005 with the biomass of 1000–1200 mg/m3 and the period of medium productivity in the 2006–2017 with the biomass of 550–580 mg/m3. The sharp drop of the biomass had occurred in just one year because of decreasing of the large-sized zooplankton abundance (euphausiids, mysids, hyperiids, and pteropods) that formed the bulk of the food base for commercial species of nekton. After the drop, the plankton biomass had stabilized again. The similar decreasing was observed earlier, in 1998, as the result of several warm years, but in those times the zooplankton abundance restored its maximal values in 2 years. Correlations of the large-sized zooplankton dynamics with the thermal parameters, as the cold subsurface layer temperature and the maximum and mean values of the ice cover are considered. Generally, the period of high productivity was distinguished by cold environments, and they were warmer in the period of medium productivity.

Persistent organic pollutants as organochlorine pesticides are lipophilic anthropogenic substances. Isomers of HCH and DDT and their metabolites are detected in organs of the seabirds Larus schistisagus, Aethia cristatella, Aethia pusilla, Fulmarus glacialis, and Oceanodroma furcata collected in the Okhotsk Sea. Total content of the pesticides in the certain examined organs varies from 28 ng to 16095 ng per 1 g of lipids: 28–8289 ng/g in feathers, 1567–16095 ng/g in feathers with skin, 1679–2478 ng/g in liver, 2230–3000 ng/g in muscles. Their average content in the whole body changes in the range from 12.5 to 15112.0 ng/g. Species specific features of the lipophilic xenobiotics accumulation are conditioned mainly by feeding habits and lipid content in the  organs.

Bottom substrates and structure and distribution of macrobenthos in the sublittoral zone of the Vladimir Bay (northwestern Japan Sea) were surveyed in July 2012 and 2014. The substrates were identified and their spatial patterns were described. Organic matter content was determined for the soft sediments that occupied the major part of the bay. Taxonomic composition of macrobenthos was identified in the upper sublittoral zone (depth of 2–40 m) and the species richness was evaluated. In total, 63 species of macrobenthos inhabit the sublittoral zone of the Vladimir Bay including 45 species of invertebrates and 18 plant species. The high species diversity is conditioned by influence of terrestrial discharge, in particularly organics. Quantitative characteristics of the bottom communities are compared with other areas of southern Primorye.

First data on concentrations of Fe, Zn, Cu, Cd, Pb, and Ni in brown algae Sargassum miyabei and S. pallidum in the coastal waters at Russky Island in Peter the Great Bay near Vladivostok are presented on the samples collected in July-August, 2016. S. pallidum that covers rocky southeastern coast (faced to the Ussuri Bay) is less polluted by the metals than the algae from other coasts of the Island. However, the elements concentrations in the algae at Russky Island, in general, mostly exceed their background levels for Sargassum algae in the northwestern Japan Sea.

The water dynamics and distribution of the sea grass Zostera marina are investigated as factors of the curative mud forming in the Voevoda Bay. The water currents are measured directly. The closed circulation is formed in the middle part of the bay by prevailing winds: anticyclonic by northwestern wind and cyclonic by southeastern wind. Zostera marina distribution is researched by divers. Its highest biomass is observed on the shallows where projective coating is 100 % and mean biomass is 3 kg/m² (wet weight). Bottom sediments and depth of the acoustic basement are mapped using seismoacoustic method. The maximal thickness of the curative mud layer is found in the internal part of the bay (Melkovodnaya Bight) where it reaches 15 meters.

Data of observations on drifters in 1988–2015 are used to study seasonal variability of the surface water circulation in the Japan Sea. The well-known circulation patterns are observed, as the Tsushima Current, the East-Korean Current, the Primorye Current, and the northern cyclonic gyre. In the fall season (October), the main features of the mean flow are a very strong inflow through the Korean/Tsushima Strait and the intensive Tsushima Current and East-Korean Current. In winter (January), the cyclonic gyre over the norther basin and the Primorye Current along Primorye coast are strengthened. These seasonal changes of the flow field are presumably caused by monsoon winds variation. In spring (April) and summer (July), the water circulation is generally weakened; one of important patterns of the summer circulation in the northern Japan Sea is the westward branch of the Tsushima Current toward Primorye coast.

Geostrophic deep circulation in the Japan Sea is modeled using the primitive equation multilayer model developed by N.B. Shapiro and E.M. Mikhaylova (Marine Hydrophysical Istitute, RAS). The main simulated patterns are the cyclonic gyres along the sea margins and in the deep basins and the anticyclonic circulation above underwater rises, that generally corresponds with the schemes based on deep floats tracking. The deep circulation is more intense in the subarctic sector than in the subtropical sector and the most intense cyclonic gyre is simulated in the Japan Basin, with the current speed up to 7–8 cm/s at its eastern margin. Speed of the simulated currents compares well with that derived from Argo data. Weakening anticyclonic circulation in the southwestern part of the sea under forcing of cyclonic wind stress curl or decrease of volume transport in the Korea Strait causes increasing of the simulated deep currents in the entire sea and the cyclonic gyres in the whole water column in its subarctic sector. Therefore, the wind and thermal forcing indirectly affect the deep circulation through the water mass redistribution by the surface currents. The deep cyclonic gyre in the Japan Basin has strong seasonal variation, strengthening in winter and weakening in summer, in line with the buoys data. The gyre intensification is accompanied with its shrinkage and the current speed decreasing at its periphery, that explains the seasonal variation of the deep currents at the northern slope of the Japan Basin observed by deep mooring. This winter strengthening of the gyre, both in the deep and intermediate layers, increases the currents barotropy, whereas the gyre strengthening in the surface layer in summer, when it weakens below 100–150 m, increases the baroclinicity. Despite of relatively low spatial resolution, the model captures deep dynamic structures related to local bottom topographic features, such as anticyclonic eddies around underwater rises and seamounts and cyclonic eddies above topographic depressions in the subarctic sector. The reverse currents were simulated above Yamato Rise, Korea Plateau, and in the Ulleung Basin in condition of the weakened deep circulation adjusting in one or two months. The reverse currents are tracked by Argo buoys, too, they follow the changes of surface currents.

Cultivation, biological and production parameters of domesticated spawners of amur sturgeon in the age from 8 to 24 years are described for the warm-water cage farm conditions. In three year-classes bred from native spawners in the cages, the females mature firstly in the age 8–10 years, while males in the age 6–7 years. The females have larger body weight, length, girth, and fatness than males in all age groups from 8 to 24 years. The males are able to produce 40–350 mL of high-quality sperm per one drain-off session, while the firstmatured females produce 0.7–2.3 kg of eggs. Majority of the females (75 %) spawn annually or biennially. Average fecundity of the females in age 8–24 years is 200,000 eggs (3.82 kg, 7,500 eggs/kg), their average oosomatic index before spawning is 14.5. The females with the highest fecundity have the age 17–23 years and produce up to 520,000 eggs (7.0–10.5 kg, up to 13,500 eggs/kg), the highest oosomatic index is 24.5 %. In total, the females which reach the age 21–24 years produced on average 22–31 kg of roe in 6–8 spawnings that is equal to 90–98 % of their body weight, and the most productive ones (27 % of total number) produced 29–43 kg of roe, or 103–138 % of their body weight. The females are technologically welladaptable for maintenance. Their survival in the period of exploitation is 65 %.

Contents of heavy metals and arsenic were measured in bottom sediments under plantations of the marine farm in the Severnaya Bay in 2015–2017, using atomic-absorption spectrophotometer Shimadzu 6800 and mercury analyzer Milestone DMA-80. Indices of pollution C_f and C_dHM and the sediment quality guideline quotient (SQG-Q) are calculated. Dangerous As content is found: it exceeded the probable toxic dose (PTD) for one plantation in 2016–2017 and exceeded the probable effect level (PEL) for all plantations in 2017. Content of Cd was also high, though unstable — the Cd pollution could be caused by scallops metabolism because this species concentrates Cd in its tissues. Using the quantitative indices, pollution of the bottom sediments in the Severnaya Bay is evaluated as moderate toxic, able to make negative effect on marine organisms. The same elements contents in tissues of the cultivated scallop were measured, as well, in 2016. The dangerous content of Cd over the maximum permissible concentration allowed by the norms of the Custom Union Commission (2010) was detected for gills of adult (1+) scallop.

Influence of shredding on molecular weight and biological value of dry concentrate is investigated for the sea cucumber Stichopus japonicus from the Severnaya Bay (Peter the Great Bay, Japan Sea). Size of particles of the shredded tissue depends on temperature of freezing: the lower the temperature, the smaller the particles. This dependence affects on intensity of the freeze-drying: decreasing of the raw material temperature from minus 5 to minus 30 оC causes the water content lowering in 1.7 times. The freezing and subsequent shredding have destructuring effect on the protein macromolecules, primarily collagens of the muscles, that contributes to their better absorption by human organism. In the crushed sample, the high-molecular proteins have lower molecular weights, the medium-molecular proteins are almost absent, and the low-molecular proteins are presented by fractions with molecular weight 15 and 50 kDa. The freeze-drying itself contribution to lowering of the proteins molecular weight is evaluated as insignificant. The optimal size of the particles after disintegration is 4–50 μm — this size provides the highest biological value of the dry sea cucumber concentrate.