The western Bering Sea is the feeding area for many nekton species with seasonally variable composition. Seasonal changes in abundance, composition and structure of the nekton community in the upper epipelagic layer (0-50 m) of this area are considered on the data collected in trawl surveys conducted by Pacific Fish. Res. Center (TINRO) in June-October of the 2003-2015, separately for the deep-water Aleutian and Commander Basins and shelf waters at Cape Navarin. The highest total abundance of nekton was observed in the middle August (2700 kg/km², on average) and decreased significantly earlier (100 kg/km² in early June) and later (200 kg/km² in late October). The dominant species were pacific salmons (Oncorhynchus spp., in particular O. keta ), boreopacific gonate squid ( Boreoteuthis borealis ) and shortarm gonate squid ( Gonatus kamtschaticus ). Besides, walleye pollock ( Theragra chalcogramma ), pacific herring ( Clupea pallasii ) and capelin ( Mallotus villosus ) were abundant in the shelf waters. Three seasons are defined by the species structure: i) early summer from early June to middle July with dominance of pre-anadromous pink salmon O. gorbuscha and chum salmon ( O. keta ) and moderate species diversity (polydominance index 3.5-4.0); ii) summer from late July to middle September with absolute dominance of chum salmon (> 70 % of total nekton abundance) and low species diversity (1.5-2.0); and iii) autumn from late September to the end of October with dominance of chum salmon, sockeye salmon and boreopacific gonate squid in relatively equal proportion, mass appearance of pink salmon juveniles and high species diversity (4.5). Spatial patterns of the nekton distribution change between the seasons, too. They are formed in early summer by mass migrations of many species to the western Bering Sea from the east and south, reflect low intensity of the migrations in summer, and are determined by backward migrations toward the southeastern Commander Basin and further to the central Bering Sea and North Pacific in autumn.

Usefulness of operational data on catch of pacific salmons for forecasting of their annual landings is considered. The landing dependence on daily and cumulative catch is analyzed. The former index has better correlation with the annual landing in the beginning of the fishery season but later loses this advantage. The landing relationship with the latter index increases naturally with time and rather reliable forecasts could be based on its value from early July for pink salmon, from middle July for summer chum salmon, and from middle August for fall chum salmon.

Modern views on dynamics of some mass fish species, as walleye pollock Theragra chalcogramma , pacific salmon Oncorhynchus spp., and japanese sardine Sardinops melanosticta are critically analyzed. Recent tendency to formal and simplified approaches in explaining the status of populations and the factors limiting their abundance is noted, both for biologists and fishery oceanographers. It is reasoned by shortage of expeditionary researches combined with passion for formal indices and ignoring the role of population and endogenous factors in forming of new generations.

New information on reproductive biology, embryonic and early post-embryonic development of saffron cod Eleginus gracilis Tilesius is presented on the base of long-term observations in the Tauyskaya Guba Bay, northern Okhotsk Sea. The species begins to spawn in this area at the age of 2 years, with the body length of 14 cm, and reaches mass maturity (when at least 50 % of fish in the age group are matured) at the age of 3 years. All fish are matured at the age of 5 year and elder. Males prevail in the first three age groups, but females dominate in elder groups. The mature fish enter to the spawning grounds in the Tauyskaya Guba Bay in December. The spawning occurs in January-March under the water temperature of -1.5^оC. The saffron cod females spawn 7.2-172.0 thousand eggs, depending on their size, weight, and age (on average 56,600 eggs or 334 eggs per 1 g of body weight). Relative fecundity of the females increases until the age of 7 years, elder females have slightly lower but stable fecundity. The eggs at the beginning of the second stage of development have the diameter of 1.00-1.58 mm, on average 1.410 ± 0.005 mm, and are distinguished by almost transparent shell and colorless yolk, with the ochre colored plasmodisc. The animal pole (were plasmodisc is formed) is in the upper position. A micropyle on the outer shell is clearly visible as a small bulge with diameter slit surrounded by two concentric beads (this structure remains during entire embryogenesis and can be considered as a taxonomic sign of the species rank). Under the incubation temperature of 2.8^оC, the eggs reach the stage of two blastomeres in 11-12 h. At the first stages of partition, numerous small fat-like inclusions are visible in the blastomeres. The second and third cycles of the zygote division with forming of 4 and 8 blastomers pass in the age interval 14-18 h. The interphase between divisions increases from 3 h between the first and second divisions to 5 h between further divisions. The eggs reach the early stage III (large cell blastula) and late stage III (small cell blastula) after 30 and 41 h of their development, respectively. By the end of the stage III, the dome of blastula is maximally developed. At the age of 75 h, the stage of gastrulation and epiboly begins. The blastoderm covers 50-60 % of the yolk surface after 123 h. Bead-shaped embryo is formed after 177 h of development. In the next 309, 417, 459 h of incubation, the embryos undergo successively the stages of tail separation from the yolk sac, mobility beginning, and heart functioning. In experiments, prelarvae of saffron cod hatched after 849 h of incubation. Their size in the Tauyskaya Guba population is the largest known in scientific literature: the total body length varies from 5.30 to 6.25 mm (on average 5.82 ± 0.05 mm); besides, they are distinguished by greater number of pigment cells on the yolk sac and nearby. Intensive pigmentation of prelarvae is known for other fish species in the northern Okhotsk Sea, as well, that presumably is their adaptation for better accumulation of solar heat in conditions of late spring warming in this area.

Retrospective data on catches of fine-mesh fishes in the Amur collected by Khabarovsk branch of the Pacific Fish. Res. Center (TINRO) since 1937 are analyzed. The main factors influencing on stock and catches of the Amur pike Esox reichertii (Dybowski, 1869) are revealed by methods of multiple regression and variance analyses, as the water level and preceding withdrawal by fishery. Dependence of the pike annual catch on these factors in preceding year (annual landing and the water level in June-September) and in current year (the water level in June) describes about 80 % of the catches variation. The tendency to both stock and landings decreasing since in the late 20^th century is caused by the Amur water regime change. Ways of the stock recovery in conditions of low water level are discussed.

State of the demersal fish community in the northwestern Japan Sea in the period 1978-1990 is considered on the data of bottom trawl surveys. Mean total biomass of the demersal fish in the USSR economic zone in those times is estimated as 1.106^. 10⁶ t. The bulk of fish community was formed by the families Gadidae, Pleuronectidae, Clupeidae, Hexagrammidae, and Cottidae with summary portion 95.1 % by biomass and 84.8 % by number. The most abundant fish species were walleye pollock Theragra chalcogramma (44.8 % of the biomass), scale-eye plaice Acanthopsetta nadeshnyi (12.2 %), pacific herring Clupea pallasii (8.6 %), blackfin flounder Glyptocephalus stelleri (7.7 %), pacific cod Gadus macrocephalus (4.7 %), and arabesque greenling Pleurogrammus azonus (4.6 %), portions of other species didn’t exceed 3 %. The summary portion of flounders (23 species) was 28.0 %, by biomass. Scale-eye plaice dominated among them (on average 135.4^. 10³ t), other mass flounders were the blackfin flounder (84.8^. 10³ t), yellowstriped flounder Pseudopleuronectes herzensteini (29.0^. 10³ t), and yellowfin sole Limanda aspera (13.2^. 10³ t) though the latter species had dominated there in the 1930s.

Seasonal and interannual variability of zooplankton in the area at Cape Navarin are considered on the base of long-term surveys. This area is the main fishing grounds for Russian pollock fishery in the Bering Sea. Species composition of zooplankton changes cardinally during the feeding period: large-size copepods prevail in summer, but euphausiids, mainly the krill Thysanoessa inermis - in autumn. Year-to-year changes of the zooplankton abundance are species-specific and driven by different environmental factors. The water circulation is crucially important for such allochtonous species as krill by transporting them from the spawning areas. Advection either from the south, i.e. from the continental slope (till 2006), or from the east and west, i.e. from the shelf (in 2007-2014), was observed in the last two decades that corresponded to replacing of relatively warm oceanographic regime by relatively cold regime and could be traced by dynamics of the ice cover and the cold water pool area on the eastern Bering Sea shelf. The advection from the slope provides the krill transport to the area at Cape Navarin, but conditions of the cold regime limit the transport. From the other hand, the cold oceanographic regime is favorable for reproduction of many zooplankton species, including krill, because of higher primary productivity. As the result, the krill and some other mass zooplankton species have a bell-shape dependence of their abundance on water temperature: they have the maximal biomass in relatively warm years within the cold periods and in relatively cold years within the warm periods. In the years with severe winters, the pollock starts its back migration early, in August-September because of seasonal depletion of copepods and lack of krill, while the years with warm winters are also unfavorable for long feeding of pollock in the Navarin area because of low abundance of many zooplankton species. «Moderate» conditions are optimal for long feeding of pollock in this area, when the Russian fishery continues here longer, till November-December, with the annual landings > 500,000 t (as in 1996-1999, 2001, 2007-2008).

Quantitative distribution of certain ecological-trophic groups of microorganisms in the Novik Bay (Peter the Great Bay, Japan Sea) is considered for summer-fall season and compared with their state in the Posyet Bay. The marine environments quality is evaluated. There is concluded that the Novik Bay is subjected to strong anthropogenic impact whereas the Posyet Bay is a clean area with insignificant anthropogenic load.

Data of observations on drifting buoys in the western Okhotsk Sea are presented. Quasi-stochastic mode of the buoys drift under forcing of atmospheric cyclone is noted. The drift is analyzed jointly with analysis of the wind field and the sea surface satellite altimetry. The buoy drift trajectories are modeled under separate influence of the wind-driven and geostrophic flows. There is concluded that both wind-driven and geostrophic currents at the sea surface should be accounted for forecasting of drift for buoys or any floating objects.

New data are presented on qualitative and quantitative composition of forage benthos obtained in hydrobiological surveys in the lower Don River in 2016. The area from Semikarakosk to the mouth (193 km), including the Don estuary, was surveyed. The benthos was sampled by Petersen dredge of 0.025 m²; in total 60 samples were processed, with some replicate ones. Mollusca was the main group of the forage benthos both in May, June, and September, mostly due to high abundance of zebra mussels. The biomass of forage mollusks varied in the range of 1.3-104.3 g/m², with the maximum in September after settling of D. polymorpha and D. bugensis juveniles. The biomass of “soft” forage benthos (mainly oligochaetes and chironomids) ranged from 6.3 to 12.6 g/m². By quantitative abundance of benthic fauna, the feeding capacity of the lower Don is assessed as high.

Concentrations of As, Cd, Pb, Hg, Se, Fe, Cu, and Zn in tissues of the commercial crabs and shrimps Chionoecetes opilio, Paralithodes camtschaticus, Pandalus borealis, Pandalus hypsinotus , and Sclerocrangon salebrosa from Primorye waters are determined. The samples were collected by research vessels of Pacific Fish. Res. Center (TINRO) in 2012-2016. Content of metals and arsenic in the soft tissues (from claws and phalanxes of crabs and abdomen of shrimps) was determined by atomic absorption analysis (fiery and flameless methods), using Shimadzu AA-6800 spectrophotometer and mercury analyzer DMA-80 Milestone. As, Cd and Pb concentrations were measured by electrothermal method, with graphite cuvette as an atomizer; Fe, Cu and Zn concentrations were measured in the acetylene/air flame, with single-slot burner as an atomizer and background correction by a deuterium lamp. The standard solutions of the metals were used for calibration. Generally, the microelement composition in soft tissues of all shrimp and crab species is similar. For all species, concentrations of the elements in the soft tissues decrease in the order: Zn > Fe > As > Cu > Se > Cd ~ Pb ~ Hg. All samples are distinguished by heightened concentration of Cu. The following ranges of the toxic metals concentration are observed (mg per kg of wet weight): Pandalus borealis As - 1.6-8.5; Cd - 0.03-0.15; Pb - 0.01-0.02; Pandalus hipsinotus As - 2.78-14.6; Cd - 0.01-0.13; Pb - 0.00-0.01; Sclerocrangon salebrosa As - 5.4-17.3; Cd - 0.01-0.04; Pb - 0.01-0.03; Chionoecetes opilio As - 9.4-14.0; Cd - 0.01-0.05; Pb - 0.01-0.05; Paralithodes camtschaticus As - 3.0-8.8; Cd - 0.0008-0.10; Pb - 0.001-0.009. Cases of exceeding the maximum permissible level of As are detected for all species: in 68.0 % of samples for Paralithodes camtschaticus , in 35.0 % of samples for Sclerocrangon salebrosa , in 33.3 % of samples for Panadalus hipsinotus , in 17.5 % of samples for Panadalis borealis , and in 17.0 % of samples for Chionoecetes opilio .

Following recent tendencies in fisheries policy to ensure both sustainability of ecosystems and conservation of economically sustainable fisheries, protection of vulnerable resources with low direct economic value comes to the focus of fisheries management on ecosystem principles. One of the problems of modern fishing is a negative impact of bottom trawling because of destruction of benthic organisms vulnerable to mechanical impacts. This by-effect of fishing could affect negatively on functioning of bottom biocenoses, reproduction of exploited species, and decrease generally productivity of vulnerable marine ecosystems (VME). Potential VME indicators are determined for the area of the Anadyr Bay in the Bering Sea on the base of results of 4 benthic surveys using bottom sampler (1985, 2005) and bottom trawl (2008, 2012), as the most common species in some macrozoobenthic groups of epifauna. They are Gersemia rubiformis for soft corals, Myxilla incrustans , Halichondria panicea , Semisuberites cribrosa for sponges, Halocynthia aurantium , Boltenia ovifera for sea squirts, Cystisella saccata , Flustra foliacea for bryozoans, Chirona evermanni for barnacles, and Gorgonocephalus eucnemis for brittle stars. Their distribution is mapped. According to their life history and feeding habits, these species-indicators are divided onto two groups: immobile sestonophages (alcyonarians, sponges, ascidians, bryozoans, cirripedians) and mobile filtrators (brittle stars). The first group prevails on hard and mixed grounds mainly along southwestern and northeastern coasts of the Anadyr Bay at the depths of 80-90 m (sponges and bryozoans - to 250 m in the Navarin Canyon) with relatively warm water, active hydrodynamics and high biological productivity. The second group represented by G. eucnemis dominates on soft sediments in the central part of the Anadyr Bay with the depths of 50-270 m occupied by the cold water pool. Quantitative distribution of brittle star, on the one hand, and barnacles with sea squirts, on the other hand, is alternative to each other. On the contrary, barnacles, sponges and sea squirts have similar distribution of the biomass, being complementary species. Distribution patterns of all species-indicators are stable for many decades. However, biomass of some these species has changed in the southern Anadyr Bay between the similar surveys conducted in the 2008 and 2012: the mean biomass of barnacle Ch. evermanni and sea squirt H. aurantium had decreased in 6.5 and 3.7 times, respectively, whereas the mean biomass of sponges, brittle star G. eucnemis and sea squirt B. ovifera did not change. Bottom trawl fishery is not active in the northwestern Bering Sea, moreover, the habitats of immobile sestonophages with hard grounds are avoided by bottom trawlers being dangerous for fishing gears, so the observed decreasing of two species abundance is presumably caused by natural reasons or is a random error of the mosaic-distributed stocks assessment with insufficiently dense sampling grid.

Seasonal changes in abundance and species composition of the yeast flora from organs of juvenile sturgeons were traced during their growing in the warm-water ponds of Luchegorsk Research Station of the Pacific Fish. Res. Centre (TINRO) in 2008-2009. The fungal community of the sturgeons was represented by whey, brewers, and wine yeasts, mostly with probiotic properties. Naganishia albida, Papiliotrema laurentii, Saccharomyces cerevisiae, Trichomonascus ciferrii , and fungi of the genus Candida were found in the intestines and gills of kaluga and siberian sturgeon juveniles, but they came from the water and are usual for microflora of cages for fish cultivation. Cryptococcus neoformans and Ogataea angusta were found in the water only. Rhodotorula mucilaginosa , Cystobasidium minuta and fungi of the genus Hanseniaspora were associated with the sturgeon organs. Generally the yeast heterotrophic microbiota in the cages showed inhibitory effect against mould and enterobacteria. Colonization of the sturgeon mucous membranes by yeasts had seasonal dynamics that definitely affected on local immunity of the juveniles. Complete elimination of the yeasts from the sturgeon mucous membranes should be considered as a predictor of worsening of their physiological state and anti-epizootic measures are necessary in this case.

Modeling technique for horizontal near-bottom longlines is presented. An example of this technique application for re-equipment of currently used bottom longlines to the near-bottom longlines is considered. Recommendations are given on choice of the buoys buoyancy, the anchor weight, and the weights for rigging of the near-bottom longline.

Polyphenol compounds in extracts from the seaweeds Saccharinа japonica , Fucus evanescens , and Ahnfeltia tobuchinensis are investigated and antioxidant activity of the extracts is evaluated. The extracts were prepared using different solvents (distilled water, ethanol, acetone) or mixtures of the solvents under various conditions. By the species, the polyphenols were extracted better by water from S. japonica and A. tobuchinensis and by 1 : 1 mixture of water and ethanol from F. evanescens . Heating increased the degree of polyphenols extraction but could decrease antioxidant activity of the extracts. After 24 hours extraction by 70 % acetone solution under 50^оC, the antioxidant activity of the extract from S. japonica was in 3 times lower as compared with the extract obtained at room temperature, though the polyphenols concentration was almost the same (0.09 and 0.11 mg/mL, respectively). The polyphenols concentration was the highest and antioxidant activity was the strongest for the extract from F. evanescens by 50 % ethanol solution under room temperature. The properties of the extracts from seaweeds are compared with the extracts from terrestrial plants. The polyphenols content in the extract from blackcurrant berry is comparable with the extract from S. japonica and its antioxidant activity is close to that for the extract from F. evanescens .

Peptides extracted from tissues of 11 shellfish species ( Corbicula japonica, Mercenaria stimpsoni, Anadara broughtoni, Patinopecten yessoesis, Crenomytilus grayanus, Spisula sachalinensis, Maktra chinensis, Serripes groenlandicus, Glycymeris yessoensis, Callista brevisiphonata, Dosinia japonica ) are tested for their antioxidant properties in different in vitro conditions. Frozen muscles and viscera of the shellfish were minced and subjected to water extraction of proteins and to hydrolysis with Protamex 1.5 MG. The peptides antioxidant activity was evaluated by assessing of 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity on free radicals generated in oxidative systems. In the experiment, the high perfomance liquid chromatography (HPLC) system (Agilent Technologies 1260) included the frame TSKgel G 3000PWXL, the flow rate was 0.1 mL/min (0.1 N NaCI-20 mM Tris-HCI, pH 8.0), the detection was made under 280 nm. Molecular weight of the proteins was determined by comparison of their retention time with pure protein standards. The enzyme activity was high in conditions of pH in the range of 5.5-8.0, with the maximum under pH 7.0. Among 11 shellfish species, the highest antioxidant activity in water extract was observed for C. japonica , M. stimpsoni , C. brevisiphonata , G. yessoensis , and C. grayanus : 86.3, 68.7, 72.3, 90.2, and 67.5 mg of ascorbic acid/g, respectively. The DPPH radical scavenging activity increased with increasing of the hydrolysis degree. The 1-step hydrolysis with Protamex enhanced the DPPH scavenging activity for all samples, with the highest value for the protein hydrolysate of M. stimpsoni tissues (215 mg of ascorbic acid/g). Size of generated peptides is important for the antioxidant activity therefore molecular weight distribution of the peptides during the proteolysis was investigated using HPLC. Portion of the low molecular weight peptides (≤ 1 kDa) in the protein hydrolysate was increased in 4-14 % as compared with the starting protein. The antioxidant activity correlated positively with the number of low molecular weight peptides in protein hydrolysates.