Long-term information on mean annual biomass of the main taxa of bottom and demersal fishes on the shelf and upper continental slope (down to 2025 m) in the Far Eastern Seas and adjacent Pacific waters is summarized. Mean annual biomass of fish in the benthic layer (without pelagic species) is estimated as 9.8^. 10⁶ t (60.2 % in the Okhotsk Sea, 20.4 % in the Bering Sea, 11.2 % in the Pacific waters at Kuril Islands, 4.1 % in the Japan Sea, and 4.1 % in the Pacific waters at Kamchatka). Schemes of these species distribution in the pelagic layers are presented, too. Even truly bottom fishes rise to the pelagic layers sometimes (mostly in the nighttime). Eggs, larvae and juveniles of many demersal and benthic species dwell mainly in the pelagic layers, transported by currents everywhere including the open waters beyond the continental shelf and slope; elder fish, from the stage of fingerlings, are able for migrations, even against stream. Biomass of the species majority is proportional to square of shelf and slope, with exception of the species associated with complicated bottom topography (rocks, canyons, guyots, etc.), in particular at steep slopes.

Data on mean annual biomass (t) of the bottom macrofauna groups and main species in the Far-Eastern Seas and adjacent waters of the Pacific Ocean, by bathymetric ranges, and on density of their distribution (t/km²) are summarized. The average density of distribution for bottom and demersal fish varies from 5.8 to 26.9 t/km² in the range 0-200 m, from 8.6 to 26.9 t/km² in the range 200-500 m, from 3.6 to 14.7 t/km² in the range 500-1000 m, and from 3.4 to 15.7 t/km² in the range 1000-2000 m. The average density for bottom invertebrates varies within 4.0-12.6, 4.7-19.6, 1.7-10.2, and 0.6-3.0 t/km², respectively. The density usually increases in the transitional zone between the continental shelf and a slope (200-500 m). Aggregations of total macrofauna are the densest in this bathymetric range and reach 32.3 t/km² in the Bering Sea, 15.2 t/km² in the Japan Sea, and 41.4 t/km² in the Pacific waters at Kuril Islands. However, the concentrations in this zone in the Okhotsk Sea (maximum 13.3 t/km²) and the Pacific waters at Kamchatka (31.5 t/km²) are lower than that ones on the continental shelf.

Dynamics of commercial stock is considered for arabesque greenling at southern Kuril Islands on the data on size-age structure of its catches and fishery statistics for 1974-2015. The stock was the highest in the late 1970s when the spawning biomass was estimated as 35^.10³ t and the commercial biomass was about 40^.10³ t. After this maximal values, the arabesque greenling resources reduced fast to approximately 1.3^.10³ t for the spawning stock and 2.0^.10³ t for the commercial stock in the middle 1980s, and then grew gradually owing to irregular appearance of strong year-classes until the early 2000s (the commercial biomass in the 2001-2005 was 24^.10³ t, on average). The stock decreases again in the last decade, until nowadays. The dynamics is similar to the dynamics of the arabesque greenling stock at northern Hokkaido, so common processes of these stocks regulation are assumed, as the fishery in the zone of the stocks overlapping on the shelf between Sakhalin and Hokkaido. This area is a feeding ground for the greenling juveniles of both populations, spawning separately at Hokkaido and at southern Kuril Islands, and an important fishing ground for Japanese fleet. Annual landings of arabesque greenling by Japan changed in the last decades from 132^.10³ t in 1990s to 53^.10³ t in 2010s, with 75 % of yearlings (0+) on average, that exceeds considerably the Russian landings of this species at southern Kuril Islands as by-catch (on average 1 % of the total Russian catch in this area, 3-5 % of the Japanese catch of arabesque greenling).

Data on oceanographic conditions, composition of plankton communities, benthic and demersal fish and invertebrates in the southern East Siberian Sea are presented by results of the complex survey conducted in August 2015, The bottom trawl survey assessed 10 species of fish and 3 species of jellyfish with total biomass 1900 t. Arctic cod Boreogadus saida dominated absolutely in the benthic ichthyocenose (60.6 % of the total biomass). Besides, 3 species of shrimps, 1 crab species, 4 species of gastropods, and 6 other taxonomic groups of macrobenthos including starfish and isopods were found in trawl catches, with the average biomass of macrobenthos 41.7 kg/km². In the bottom samples of macrobenthos, 12 taxonomic groups were presented, with predominance of bivalves, polychaetes, isopods, and amphipods (summary 95 % of the total biomass).

Variability of three SNP loci allocated in the mitochondrial DNA ( One_CO1, One_Cytb_17, One_Cytb_26 ) is analyzed for sockeye salmon from its different habitats from Chukotka to Kuril Islands. Two basic haplotypes (GCC and GTT) are revealed in 20 samples of sockeye ( n = 33-100) from 15 lake-river systems. Their ratio is mostly equal, but GTT haplotype prevails in the populations from Kuril Islands (except Shumshu Island) and is absent in the sample from Commander Islands. This geographical pattern is presumably caused by historical-demographic events related to the species range formation in the middle-late Pleistocene: fragmentation of the areal and subsequent secondary contact between early diverged populations. Two scenarios are discussed, both with multiple expansions of the species to Asia during periods of oceanic transgression after Pleistocene glaciation. According to one of the scenarios, the GTT haplotype has more ancient origin somewhere on the mainland, whereas the GCC appeared much later in the central Kamchatka refugia. The second scenario presumes the origin of both haplotypes on Beringia Bridge where they diverged in the times of middle-Pleistocene (Wurm) glaciation.

One possible approach to the stock assessment for marine commercial fish species is considered by the example of the Okhotsk Sea pollock. The method is based on cohort modeling. Unknown parameters of the model are selected by solution of the filtration and identification problem.

Results of observations on northern fur seals in the Tatar Strait are presented. The mammals were observed from the Nevelskoy Strait in the north to Cape Krilyon in the south.

Biannual sequence of high-numerous and low-numerous year-classes of pink salmon ( Oncorhynchus gorbuscha ) is disturbed rarely in the areas close to its spawning grounds where mostly local groupings are landed, as it is shown on the data of fishery statistics in many areas of Russian Far East for 1907-1986. The disturbances are related usually with by-catch of transitory fish, in particular for the Sakhalin-Kuril region. Dynamics of the pink salmon annual landings in the Amur correlates with its dynamics at northwestern Sakhalin, that allows to suppose the species migration from the Okhotsk Sea to its spawning grounds via northwestern Sakhalin. Besides, a part of the Amur pink is caught at the mainland coast of the Gulf of Sakhalin, but the landings in the Amur correlate well with this transitory area in even years only, when the run is stronger. The highest catches of pink salmon on the mainland coast of the Gulf of Sakhalin in 2015 could be ensured neither the Amur nor the Sakhalin groupings; a hypothesis on the Shantar groupings contribution is discussed. In general, high catches of pink salmon in Khabarovsk Region in 2015-2016 are possibly reasoned by its good survival and lowered fishery in the Sakhalin-Kuril region.

Chemical and ecological state of the Novik Bay waters is described on the data of surveys conducted in summer, autumn, winter, and spring of 2014-2015. Lowered content of dissolved oxygen is noted for summer, with occasional decreasing to 5-6 mg/L that is below the standard summer value for fishery ponds. However, the oxygen content restores quickly in autumn, up to 12 mg/L, that is conditioned by hydrodynamic activity, water temperature decreasing, and phytoplankton blooming. The latter process is confirmed by high values of BOD₅ (4.44-5.58 mgO₂/L) in autumn. Winter conditions under the sea ice are satisfactory for marine organisms: dissolved oxygen content is > 4 mg/L in the whole water column that is close to the standard winter value for fishery ponds.

Fauna of helminthes and feeding of pacific salmon (pink, chum, and coho) juveniles at the continental coast of the northern Okhotsk Sea are considered both for freshwater and early marine stages of their life. Possible conditions of the parasitic worms invasion are discussed. In total, 17 species of parasitic worms are found in salmon juveniles including cestodes (2 species), trematodes (8), nematodes (4), and acanthocephalans (3). The trematodes Brachyphallus crenatus and Pronoprymna petrowi have the highest values of infestation. The helminthes are mainly the representatives of freshwater ecological group (10 species are found in fresh waters and 8 species in estuaries), only 6 species represent the marine ecological group. One marine species ( Hysterothylacium gadi aduncum ) is found in estuarine coho juvenile and one freshwater species ( Diplostomum sp., met.) is found in marine coho juvenile.

Adaptive abilities of the microscopic red alga Porphyridium purpureum (strain PP-AB11, isolated from the northwestern Japan Sea) are investigated experimentally by its repeated cultivation under various water salinity. Under the salinity of 8 ‰, the growth of P. purpureum was inhibited (0.1 division/day) during the first four days though there were no morphological differences of the cells as compared with those in the control (mean cell size was 6.3±1.2 µm in both cases); the cell density increased to 85 % of the control value after 21 days exposure. Under the salinity of 4 ‰, the lag-phase was also 4 days but size of the cells increased (on average up to 7.8 ± 1.5 µm), the cell morphology changed including the cytoplasm retraction, and contraction and granulation of the chloroplasts; the cell density increased less (to 53 % of the control value) after 21 days exposure. Under the salinity of 2 ‰, changes of the cell morphology and density were the most prominent: density of viable cells decreased to 6 % of the control value after 4-days exposure, size of the cells increased on average up to 8.7 ± 1.6 µm due to hydration, granulation was noticed in the chloroplasts, and the cytoplasm became dense. Under the salinity of 0 ‰, all the cells died after 4 days. Being cultivated repeatedly, the alga was better adapted to low salinity: after 21-days exposure the cell density was 97 % of the control value under salinity of 8 ‰ and 84 % of the control value under salinity of 4 ‰, with the growth rate 0.5 divisions/day and without visible morphological differences of the cells as compared with those in the control. It was adapted even to salinity of 2 ‰: the cells morphology was restored though the growth rate after 21-days exposition was still lower than in the control because of serious deterioration of the cells. The growth rate and cell morphology did not significantly differ from the control after reinoculation of the culture, previously adapted to salinity of 2 ‰, into the medium with salinity of 32 ‰.

Complex assessment of the marine environments changes in the coastal zone of the Japan Sea at Primorye and Sakhalin coasts is presented for the last 4 decades. Both natural and anthropogenic aspects of these changes are considered with the tasks: 1) to compare interannual variability of oceanographic parameters, as water temperature, salinity, and sea level, and reveal distinctions and common tendencies; 2) to define indicators of chemical pollution and find general features of interannual dynamics for polluting substances and water quality. The data of regular oceanographic observations at 11 coastal stations and the data of pollution monitoring in certain areas conducted by hydrometeorological service of Russia (Roshydromet) in 1980-2015 are analyzed. Cyclic fluctuations with the period of 2-5 years prevail in year-to-year variability of oceanographic parameters being observed on the background of long-term trends, more significant in the 21^st century. The sea surface temperature has a strong positive trend (up to 1.4^o per 35 years) at many stations, with exclusion of 5 ones located in northwestern Sakhalin and central Primorye; the average trend for the whole area is 0.7^о per 35 years. Majority of the stations have the significant positive trend in summer and fall, but Sovetskaya Gavan - in all seasons. For all stations, the lowest mean annual temperature was observed in 1980 and 1987, the highest one - in 1990. Salinity has a significant negative trend at all stations (up to -2.66 ‰ per 35 years), except Alexandrovsk-Sakhalinsky, with average value -1.3 ‰ per 35 years. The negative trend of salinity is more significant in spring and summer, though other tendencies could be seen locally in certain seasons. The sea level has a positive trend, significant at all stations in any season, with the maximal value in spring (on average 7 cm per 35 years that is 35-50 % of the range of seasonal fluctuations). Dynamics of pollution is described by frequency of high concentration (over the maximum permissible level) of organochlorine pesticides (HOPs), petroleum hydrocarbons (TPHs), phenols, detergents, and heavy metals. The high concentrations of TPHs and phenols are observed rather frequently, usually in the Tartar Strait and Peter the Great Bay (Golden Horn Bay, Diomid Bight, and Bosfor Vostochny Strait). In the latter area, the dangerous levels of dissolved oxygen content are observed, as well. Other pollutants don’t exceed frequently the maximum permissible level.

Data on species composition of ciliates in the small rivers at Khabarovsk and in southern Sakhalin Island are presented. Modified method of sampling was applied with using of samplers and “glass fouling” on the shallows of the rivers. More than 230 samples were collected in the small rivers at Khabarovsk and about 200 samples in the southern Sakhalin. Species composition of the ciliates was determined immediately after the sampling and repeatedly on nutrient media. In total, 86 species of ciliates are identified, mostly belonged to the classes Oligohymenophorea and Spirotrichea. Six eurybionts were found: Coleps hirtus, Paramecium caudatum, Dexiostoma campylum, Colpidium colpoda, Uronema nigricans, and Vorticella convallaria сomplex . The classes Armophorea and Phyllopharyngea were more diverse by species in the area at Khabarovsk but the class Spirotrichea - in southern Sakhalin. In general, faunas of ciliates in two surveyed regions are similar. The highest inter-regional similarity of the species composition is registered between the rivers at Khabarovsk and the Susuya River in Sakhalin (25-33 %, by Jackaroo) that is probably associated with a heightened level of pollution in the Susuya. Most of the species adapt to habitat rapidly, so they are found in different environments: among benthos, plankton, periphyton. Some patterns of the ciliocommunities are discussed.

Biology of Mytilus trossulus is investigated in the Vesyolaya Cove, the Tauiskaya Bay on June 16 - September 20, 2011 within experimental studies of its cultivation ability in severe conditions of the northern Okhotsk Sea. In case of so called Spanish cultivation technology or its White Sea modification, the mussels grow to the commercial size (35 mm) in 3-4 seasons. To decrease this time to 1-2 seasons, the breeding technology is applied with the mussels collecting from the littoral substrate and their further breeding in hanged collectors. The mussels growth rate is evaluated both on the littoral substrate and in the collectors. The growth rate becomes lower after the mussels transfer from the littoral substrate to the hanged collectors but increases intensively after their transfer from the collectors to the littoral substrate, being higher that for the originally littoral mollusks. The growth rate dependence on size and age of the mussels is considered.

Geometric parameters of the bottom trawl DT 27.1/24.4 were tested aboard RV TINRO in the Bering Sea using the acoustic equipment «Scanmar» (Norway). Possible errors in the estimates of marine organisms abundance by bottom trawl survey are calculated for different species by comparing the actual data on the trawl geometry with the fixed constant value of its horizontal opening. The obtained data can be used for evaluation of the hauled area in bottom trawl surveys.

New techniques of fish tranport from fishing gears aboard is proposed for a case of mixed aggregations of chub mackerel and japanese sardine. These species resume their mass migration to the Russian waters since 2014. Submersible impeller pumps with hydraulic power drive are used usually for catch transport aboard in the world practice of purse seining of mackerel. However, this technique is unsuitable for mixed aggregations of mackerel and sardine because the impeller pump could damage the sardine. Applicability of the vacuum and waterjet pumps for this case is considered. The vacuum fish pump TransVac was designed in 1982, initially for transfer of damage-sensitive fish from fishing vessel to shore fish processing plant, and the waterjet fish pump SilkStream was designed in 1988 for transfer of alive fish and later was adapted for fish transport aboard from trawl and seine nets. Both types of fish pumps are recommended for the medium- and large-capacity fishing vessels working with the mixed aggregations of sardine and mackerel. Using of these pumps together with freezing equipment allows to avoid losses in quality of catch.

Algorithm for calculation of illumination produced by shipboard lights at the sea surface and underwater is developed and implemented with Microsoft© Office Excel software. The surface illumination is calculated for the fishing vessel STR-420 with the light equipment for saury fishery. Irregularity of the lighting around the vessel is shown that depends on the lamps arrangement. Optimal scheme of the lamps arrangement is proposed for a new saury trap with the catch volume > 7000 m³. The optimal arrangement provides more regular lighting and therefore larger illuminated area for attraction of fish with positive phototaxis, as saury. Relationship between natural density of saury distribution and its catch per trap is determined for this trap.

Methods of arachidonic acid (AA) isolation from animal and vegetal natural sources are considered. Traditional raw material as the lipids of beef liver and alternative source as the red alga Gracilaria vermiculophylla are tested. The AA was isolated by a sequence of known techniques for concentration of polyunsaturated fatty acids: sedimentation of saturated fatty acids in the form of their lithium salts, iodo-lactonization, and high performance liquid chromatography. All these techniques were applied for isolation of AA from the beef liver lipids, where the AA content did not exceed 7.7 % of total lipids, and the yield of AA with purity of 98.76 % was 50.8 %. The AA content in the algae lipids was significantly higher (> 35 %), while the amount of n-3 polyunsaturated fatty acids was insignificant, so two techniques only were applied (sedimentation of lithium salts and liquid chromatography), and the yield of AA with purity of 97.60 % was 68.3 %. Thus, high-purity arachidonic acid could be isolated from the algae G. vermiculophylla using simple and reproducible procedure. Taking into account the high yield of AA, this method is economically feasible and is proposed for biochemical and medical researches.

A new cooling medium for storage of fish and seafood is proposed - frozen water solution of polysaccharides of natural origin, as the natural biopolymer chitosan. Rational concentration of its solution for producing the chitosan ice is determined experimentally. Organoleptic, physical, and microbiological parameters of the ice prepared from solution of polyelectrolyte complexes of chitosan and its co-polymers are examined. Better results for cooling of marine raw materials are shown for the solution of polyelectrolyte complexes based on chitosan with sodium alginate and carboxymethyl cellulose. The chitosan-alginate ice is distinguished by higher density and homogeneous consistency within the temperature range from -5 to +5^оC. Antiseptic microbiological activity of the chitosan-alginate ice is in 2.3 times higher as compared with the water ice and in 1.8 times higher than for the chitosan ice. High technological properties of the ice of polyelectrolyte complexes of chitosan with sodium alginate provide good prospects for its using in technology of cooling in fishery industry.