Features of seasonal distribution are considered for the most abundant fish species in the northwestern Japan Sea and their stocks are assessed on the data of the bottom trawl survey over the shelf and continental slope from Peter the Great Bay to the Soya (La Perouse) Strait conducted by Pacific Fisheries Research Center (TINRO) on April 1 - July 8, 2015. The total biomass of bottom and demersal fish species in the surveyed area is estimated as 584.5 · 10³ t, including 137.8 · 10³ t of flatfishes (23.5 %) and 135.3 · 10³ t of sculpins (23.1 %). Deep-water sealyeye plaice had the maximal biomass among flatfishes with the stock of 63.8 · 10³ t, it concentrated mainly at southern Primorye (28.3 · 10³ t). Its stock was comparable with the total flatfish biomass at western Sakhalin (61.2 · 10³ t). The family Cottidae was also very important in bottom communities of the northwestern Japan Sea, but this group had higher species diversity: 22 species. Blackedged sculpin, graypurple sculpin, plain sculpin, and great sculpin were the most abundant sculpins and dominated in this group in different proportion in all areas. The total stock of these four species was 110.6 · 10³ t (81.7 % of the total biomass of Cottidae), including 25.8 · 10³ t in Peter the Great Bay, 45.7 · 10³ t at southern Primorye, and 20.4 · 10³ t at western Sakhalin. The sculpins dwelled mostly shallower than 400 m, only 3 % of their biomass was assessed deeper. The observed values of the stocks were close to their mean values, with exception of Peter the Great Bay, where the assessed stocks were considerably lower of the mean values. The underestimation was supposedly caused by early timing of the survey start that wasn’t optimal taking into account seasonal migrations of some mass species. For example, the main concentrations of flatfishes were located in early April deeper than the survey limit.

Abundance and biomass of walleye pollock Theragra chalcogramma in the Bering Sea exceeded the mean values in 2015 owing to the high-abundant year-classes of 2008 and 2012 and several medium-abundant year-classes (of 2006, 2009-2011, 2013, and 2014). In contrast to rather stable distribution on its spawning grounds, distribution of feeding pollock in the northern Bering Sea is very variable and depends on both biomass of the population and long-term and short-term variations of environments, as water temperature and zooplankton abundance. In some years including recent times (2005-2007 and 2010-2014), the pollock migrated earlier and faster into the northwestern Bering Sea and returned back to the eastern shelf also early: in late summer - early autumn. This scenario is supposedly conditioned by low zooplankton abundance over the Bering Sea that forces pollock to active feeding migrations, particularly a deficit of preferable food (large-sized zooplankton) on the north-western feeding grounds could be a reason for its leaving this area in late summer. Strength of pollock year-classes is highly variable, too, and depends mostly on young-of-the-year fish survival in winter. As usual, favorable conditions for reproduction and progeny survival, when strong year-classes appear, are observed in the years or short periods of transition from one state of marine environments to another, whereas long periods of either «warm» or «cold» regime are not favorable for forming of high-abundant year-classes of the Bering Sea pollock.

Some common ideas about environmental factors that determine the patterns of migration (including timing) and stock dynamics of walleye pollock are critically analyzed with particular attention to the Bering Sea. There is shown that the conception of the migration timing dependence on food supply in the northern Bering Sea does not represent the real facts, as well as the conception of year-class strength dependence on winter mortality of fingerlings determined by food supply, especially in conditions of its deficiency. Periodicity of the pollock stocks dynamics associated with global changes of climatic and oceanographic factors is also called in question. Role of provincial factors in dynamics of the pollock populations is discussed and emphasized.

Reproductive biology of embryogeny and early ontogenesis is considered for pacific capelin Mallotus villosus catervarius (Pennant) from the Tauiskaya Bay in the northern Okhotsk Sea on the data of long-term sampling. The stages of periblastic sinus and Kupffer’s vesicle are described for the first time for the genus Mallotus. Results of the study allow to assume development of the embryonic vascular system of respiration for the capelin embryo. Tendency to the pacific capelin fecundity increasing is observed in the last five decades conditioned by its abundance lowering and consequent increase of the older fish percentage.

Influence of several factors (water temperature, food supply, predatory, size of juveniles) on pacific salmons survival during wintering is considered on the data collected from the upper pelagic layer in surveys conducted by Pacific Fisheries Research Center (TINRO) in the North-West Pacific. There is highly unlikely that the temperature influences on fish mortality directly. There is no obvious proof of negative influence of the low temperature on food base of salmons, as well. The lowering of forage zooplankton biomass in the Subarctic Front zone in February-March is insufficient for the salmons starvation taking into account that the total abundance of planktivorous nekton is also lowered in this area and generally in the Subarctic waters in winter-spring, so the food supply cannot be considered as a crucial factor of the salmons survival. Seasonal changes with lowering of feeding intensity, lipid accumulation, and somatic growth in winter known for pacific salmons aren’t forced by poor food base but are a feature of their species-specific life strategy with cyclic changes of metabolism. Predators are not abundant in the Subarctic zone in winter, so the predatory also cannot cause the high mortality of salmons. Relationship between the size of juveniles and their mortality in winter is considered in detail for the Okhotsk Sea stocks of pink salmon and there is concluded that the size of juveniles cannot be a predictor of their year-classes return for spawning. Thus, any single factor doesn’t determine winter mortality of pacific salmons but their survival is likely determined by a complex interaction of abiotic and biotic factors.

Numbers of scale circuli are calculated and intercirculi spacings are measured along 3 radii (the longest one and two lateral ones deviated by 15^o from the longest) for pink salmon Oncorhynchus gorbuscha from the Kurilsky Bay (Iturup Island, southern Kuril Islands) and the Ostrovka and Kura Rivers (southern Sakhalin Island). The difference of the circuli numbers along different radii was twice lower in comparison with the difference of their number between fish, but the differences of circulus spacing were similar between the radii and between fish in each area. Variability of these parameters was significantly higher between the areas, the differences were statistically significant for both in this case. The feature of low variability of the circuli number and intrecirculi spacing allows to pick a proper radius for measuring the circuli to avoid over- or underestimation of their number in cases of local deformation of scale (merging or splitting of some circuli).

The information on fishery object limited by CPUE data and fragmentary data on age and size is sufficient for production models. However, this type of models is improper for long-living species, as crabs, because of problem with assumption on equilibrium stock. Describing dynamics of a single year-class, these models average the parameters for all generations that impedes to use them for assessment of crabs stocks. Finite-difference models with delay are more promising in this case. Deriso-Snute finite-difference model with delay was used for simulating of the spiny king crab biomass dynamics at southern Kuril Islands and forecasting of TAC for this species. Parameters of the model were estimated using the algorithm of sampling by scheme of Markov chain. The model is relatively simple and undemanding to data - time-series of commercial catch per effort is sufficient for its simplest version. Results of modeling are comparable with the results of cohort models.

Gonads of females and males of the sea cucumber Apostichopus japonicus were collected along Primorye coast of the Japan Sea (bays Kiyevka, Sokolovskaya, Melkovodnaya, Sredniaya, and the area between Cape Genbachev and Cape DeLivron) in different seasons from May to October, 2011. The gonads were fixed in 70 % alcohol and Buena fixing agent, using Isoprep and Histomix, and subjected to histophyisiological analysis. Sex of the animals and condition of their gonads were defined visually and on histological preparations. Their whole bodies, skin and muscular bags, and sexual glands were weighted, gonad-somatic indices were calculated, dynamics of cellular composition was traced for the sex glands, timing of spawning and duration of the rest stage were determined. For the cucumbers from the Kiyevka and Melkovodnaya Bays, diameter of sex tubules varied from 0.2 mm to 1.9 mm, diameter of freely lying oocytes - from 71.4 mm to 167.0 mm, and diameter of wall oocytes - from 47.6 mm to 119.0 mm; they were ready for spawning in late July - early August, and spawned in the first 10-days of August. Plication of the tubule walls internal surface was observed later in the process of mature cells resorption in sex tubules; new generation of the cells appeared, which most likely would undergo to further destruction (small tubules with plication of their walls were observed for a specimen from the Kiyevka Bay in late September, 2011). New gametogenesis was registered both for females (small oocytes) and males (spermatocytes of I and II orders) from the Sredniaya Bay and between Cape Genbachev and Cape DeLivron in early October, simultaneously with continuing process of the tubule walls plication. The rest stage (without forming of new sex tubules) continued 1.0-1.5 months: from early August to middle September, with some variations between the areas.

Parameters of external respiration are considered for white whales Delphinapterus leucas living in captivity on the observations in 2009-2012. Low respiration rate (on average 2.2 ± 0.3 breath per minute) and short apnea phase (no more than 1.7 minutes) were observed in the first days after the catch, but both parameters returned to normal values (3.0 ± 0.2 breath per minute, apnea up to 5.1 minutes) in the next 10-34 days. The respiration rate in the morning is higher in comparison with the evening. The respiration rate dependence on the whales motor activity, their age, and water temperature is discussed, as well.

Intrapopulation heterogeneity of cell volume is estimated for the diatom Attheya ussuriensis acclimated to 17.5 ‰ salinity after its transfer to the media with salinity 8.8 ‰ (hypoosmotic conditions), 35.0 ‰ (hyperosmotic conditions) and 17.5 ‰ (control) at different stages of growth, under conditions of different nutrients supply and interaction with the diatom Conticribra weissflogii . The samples of A. ussuriensis were collected in the Ussuri Bay (Japan Sea) from an area with pure culture of this species. The cell volume of A. ussurensis increased under conditions of optimal nutrient supply and decreased under shortage of nutrients, irrespective on salinity. However, the salinity influenced on variability of the cell volume; the intrapopulation heterogeneity was formed mainly by size variation of large cells. The cell volume probability distribution became more asymmetric at change of growth stages, for any salinity as well. Clustering of cell volume distribution did not depend on salinity and nutrient supply. Both asymmetry and clustering of cell volume distribution for A. ussuriensis were rather different between mono- and mixed cultures in hypo- and hyperosmotic conditions but were almost equal in the control.

Males and females of lyre crab Hyas lyratus were found in the northwestern Bering Sea in 2010 (late July - early August), for the first time in the Russian waters. The crabs were caught during the trawl survey by bottom trawl at the depth of 111-169 m, on mixed grounds. Crabs of this species were caught again in the same area in August 2012. Thus, new western limit of the species distribution area is established as the western vicinity of Cape Navarin (61^о52′ N 177^о51′ E). Size of males was 35-43 mm, size of females varied within the range 19-49 mm. All males were at the 3^rd molting stage in 2010 and at the 3^rd terminal stage in 2012. All females, except one juvenile, had eggs of orange color. Traumatism (autotomy) of crabs was insignificant. Biological parameters of the crabs from the northwestern Bering Sea are compared with those from the Salish Sea (North-East Pacific).

Morphological description is given for 31 specimens of spotted ratfish Hydrolagus barbouri caught at northeastern Japan and southern Kuril Islands in the 1980, including both male and female juveniles and adults. Counts for teeth enamel rods, prepelvic tenaculum hooks, and intestinal valves are presented. The species biology is discussed.

Two specimens of velvet dogfish Zameus squamulosus (TL 68.0 and 68.4 cm) caught in the epipelagic layer of the North-West Pacific are described, including morphometric parameters, number of vertebras, number of teeth rows, number of mitral valves, and number of intestinal valve coils.

Light conditions and nutrients supply, as factors of primary production, are considered for the Razdolnaya River estuary in period of freezing (January-March). Water samples were collected at the water surface and at the bottom for measuring of salinity and concentrations of chlorophyll (Chl), phosphate, nitrite, nitrate, ammonium, and silicate. Profiles of water temperature, conductivity, Chl fluorescence, and turbidity were measured in situ by CTD-probe RBR XR-620; besides, vertical attenuation of PAR was measured at each station. The internal estuary (salinity < 10 ‰) was characterized by high values of the light diffuse attenuation coefficient ( k_d ≈ 2 m^-1 that corresponded to the euphotic depth z_eu < 2.5 m) because of high turbidity (> 5 FTU) and high concentration of humine substances (up to 2 mgC/l) in the river waters. The ice cover lowered light intensity in the river water, too. In the zone close to the river bar with salinity 1-25 ‰, Chl concentration was 0.4-1.7 mg/m³ irrespective of salinity. DIN (dissolved inorganic nitrogen) and DISi (dissolved inorganic silicon) had conservative behaviour in this zone, the DISi : DIN ratio was ≈ 0.7-1.1.These features indicate an absence of significant production or destruction of organic matter in the internal estuary. However, intensive removal of dissolved inorganic phosphorus (DIP) (up to 80 %) was observed in this zone, that’s why the extraordinary high DIN : DIP ratio was observed under salinity 5-20 ‰ (up to 200 : 1, though the usual DIN : DIP ratio in the river water is close to Redfild ratio: DIN : DIP = (21-27) : 1). In the external estuary (salinity15-32 ‰), the water became more transparent ( k_d = 0.5-0.3 m^-1; z_eu ≈ 9-15 m) and both chlorophyll concentration and dissolved oxygen content became higher (Chl up to 20 mg/m³, DO up to 500 mM/kg) as the result of high primary production, whereas nutrients concentrations became lower: DIP were completely removed and DIN and DISi retained 10-25 % of their initial values in the river water. The primary production value was evaluated by two ways: on the data of light intensity and on the data of nutrients removal. The light conditions in the internal estuary in February-March corresponded to the value 20-80 mgC/m²d which declines in 6-13 times and 50-100 times (close to zero) under the ice and under the ice with snow, respectively. In the external estuary, the light conditions in March corresponded to the value 300-600 mgC/m²d in the areas without ice and to the value lower in 6-13 times under the ice. The nutrients removal corresponded to the primary production value ≈ 200-400 mgC/m²d in the external estuary, irrespective of ice cover, that is close to the previous estimation by light conditions. So, the primary production in the Razdolnaya River estuary changes in winter in the range from 0 to 500 mgC/m²d, increasing seaward, the ice and snow are the factors of its limitation by light.

State of zooplankton, as the food base of walleye pollock, in the western Bering Sea in the early 21^st century is considered. Warm period of the 2001-2006 changed to cold period of the 2007-2013 and, after the transitional year of 2014, a new warm period began in 2015 that could be seen on a number of parameters including the ice cover that was the lowest for the last 15 years. In the previous warm period, the walleye pollock food base wasn’t reduced in this area, in contrast to the eastern Bering Sea where the biomass of its favorite prey was lowered. The same is observed in the beginning of the new warm period. Data on zooplankton abundance are presented, including both dominant and minor groups, that allows to assess a real feeding conditions for six size classes of walleye pollock. Food supply of pollock is evaluated quantitatively as a number of its monthly rations in the zooplankton stock, taking into account age and regional properties of its diet. This index was high in the western Bering Sea for both warm and cold periods, any deficit of food for pollock was never observed there.

Daily ration of the Okhotsk Sea herring is estimated as 3.9 % of the body weight in spring, 7.7 % in summer, 4.9 % in autumn, and 1.2 % in winter. Its mean annual consumption is assessed as 35.9 million t of prey, mainly zooplankton (97.3 % of the ration) including 15.86 · 10⁶ t of euphausiids (43.0 %), 15.16 · 10⁶ t of copepods (41.1 %), and 2.7 · 10⁶ t of amphipods (6.2 %). In total, 6.9 % of the Euphausia stock, 3.7 % of the Copepoda stock, 9.7 % of the Amphipoda stock, and 0.1 % of the Chaetognatha stock are grazed by herring annually. The herring consumption is on average 18.9 % of the total volume of food consumed by nekton in the epipelagic layer of the Okhotsk Sea.

Mean daily ration of walleye pollock (various size) in the Okhotsk Sea is estimated as 2.3 % of fish body weight in spring, 5.4 % in summer, 3.4 % in autumn, and 2.2 % in winter. Its total annual consumption is amounted as 98.88 · 10⁶ t on average for the 2000s. Zooplankton dominated in the diet, with its mean annual grazing 80.42 · 10⁶ t, including 41.84 · 10⁶ t of euphausiids (44.1 % of total consumption) and 19.83 · 10⁶ t of copepods (20.9 %), while only 11.29 · 10⁶ t of nekton (11.9 %) was grazed annually by pollock. Pollock grazed annually 16.7 % of the Euphausia stock, 5.0 % of the Copepoda stock, 40.7 % of the Amphipoda stock, and 1.1 % of the Sagitta stock, on average. About a half (50.7 %) of the nekton total consumption in the Okhotsk Sea is provided by pollock.

Euphausia in the Okhotsk Sea is one of the most abundant groups of zooplankton, its portion in the total zooplankton biomass in the epipelagic layer is 25.4-37.4 %, depending on season, the total stock is 83.2 · 10⁶ t in spring, 66.3 · 10⁶ t in summer, 57.4 · 10⁶ t in autumn, and 73.3 · 10⁶ t in winter (mean assessments for 1986-2012). The highest biomass is observed in spring - 369 mg/m³, on average, and the minimum one in autumn - 256 mg/m³, on average. Two species, Thysanoessa raschii and Thysanoessa longipes , are the most abundant. Year-to-year fluctuations of Euphausia abundance are prominent: up to 5 times, but it never causes any catastrophic change in their populations. Sharp declines usually are followed by sharp rises in their number. Mean daily ration of euphausiid in the Okhotsk Sea is 7.5-8.5 % of the body weight. Annually they consume 2012.7 · 10⁶ t of prey, including 1636.5 · 10⁶ t of phytoplankton and 341.8 · 10⁶ t of micro-heterotrophs. About 11.4 % of the annual production of phytoplankton and 26.0 % of the annual production of micro-heterotrophs are grazed by euphausiids.

Variability of temperature and salinity in the 0-1000-m layer of the North-West Pacific is analyzed on the data of shipboard oceanographic observations obtained in 1950-2014. Significant decadal changes of these parameters are revealed at the depth of 300-600 m that exceeds the depth of seasonal fluctuations, with the highest rate in the Subarctic frontal zone. The heat content was the highest in the 1960-1974, then decreased in the 1975-1999, increased again in the 2000-2014, and the next phase of thermal «discharge» may begin supposedly in 5-6 years. Mechanisms of such climate changes are discussed. Similar changes are observed in different regions of the World Ocean that means that it is a global-scale phenomenon. These climate changes of water temperature in the subsurface layer of the ocean and air temperature over the continent have opposite directions that denotes the auto-oscillation in the open non-linear system «ocean-atmosphere-continent» as their main mechanism. The previous period of the water thermal discharge was conditioned by active winter center of low atmospheric pressure - Aleutian Low. It was accompanied by strengthening of the East-Kamchatka Current and Oyashio Current and high abundance of japanese sardine. The modern period of warming from the beginning of the 21^st century is distinguished by negative values of PDO index, observed since 1998. However, PDO is positive again since January 2014, though stability of this change is not clear yet. On the other hand, winter SST in the spawning grounds of japanese sardine, both in the Japan Sea and North-West Pacific, gradually decreased after the maximum in the 1998-2000 and reached negative anomalies in the areas at Japan in 2011-2015 that was favorable for its reproduction. The sardine biomass was gradually increased, too, in particularly in the 2010-2012, and its migration to the Russian EEZ became more active, up to 0.7 million tons in the South-Kuril area in 2015.

The time-series for the ice cover dynamics in the Okhotsk Sea in the period from 1882 to 2015 are reconstructed on the base of shipboard, airborne, and satellite observations and measurements of the air temperature at the coastal meteorological stations. Abnormality of the ice conditions is estimated relative to the “climate norm” determined as the mean seasonal variation for the 1961-1990. Long-term variability of the ice cover is analyzed. Its regime shift with change of trend is revealed in the late 1970s - early 1980s that corresponds to the regime shift of the air temperature variability in the northern hemisphere.

Data on cultivation of scallop Mizuhopecten yessoensis in the Ussuri Bay are generalized. The marine farms are located in the shallow waters at depths of 2-18 m, their plantations occupy different areas with different hydrodynamics. Complex structure of the plantations (collectors, cages and bottom facilities) is formed in the semi-closed Sukhodol Bay, but bottom plantations only for growing of scallop and sea cucumber are mounted in two other bays. The local broodstocks of scallop were formed by juveniles transported from the Posyet Bay, after that at least 20 million individuals of scallop spat were collected in three bays in 2000-2014, and their growing gave the total commercial output about 216 t (111 t in the Sukhodol Bay, 70 t in the Ilmovaya Bay, and 35 t in the Malye Kushi Bay). This is rather weak result that shows that the area has limited abilities for development of this type of aquaculture. The main reason was low density of spat on substrata: it never exceeded 200 ind./collector and did not increase during the farms development, so the farmers were forced to increase the number of collectors to obtain required number of spat; moreover, some years were unfavorable for collecting of juvenile scallops. There is concluded that environmental conditions in the eastern Ussuri Bay are not optimal for the scallop cultivation by extensive method.

Method for analytical determining of trawl doors parameters is presented that allows to define by computer modeling the position of warp and bridles fastening that provides stable functioning of the doors and the whole trawl system.

Modeling by means of SolidWorks Flow Simulation software for determination of hydrodynamic parameters of trawl doors is described by the example of the trawl doors Project 2490 designed by P.P. Augulis.

Mathematical model of trawl doors is presented and methods of their modeling with account of the water currents are described. The model could be used for optimal tooling of trawl systems for real environments.

Japanese sardine resumes mass migrations to the Russian waters since 2014 that allows to restart domestic fishery of this species. Traditionally, Russian fishermen use purse seine for the sardine landing. Capacities of both purse seine and trawl fishing of japanese sardine are analyzed. There is concluded that the trawl fishing is more appropriate for the catch processing to fish flour.

Fresh milts of salmon, cod, and herring possess high technological properties which are lowered in the processes of freezing and storage. The lowering is insignificant in the first month of storage but becomes more essential after two months of storage, in particular for the milt of cod. One of these properties is a high emulsifying ability. Stability of the emulsion systems with use of milt depends on the fish species, freshness of the raw materials, and preliminary thermal processing: the emulsions with milt of salmon have higher stability relative to the milts of other species and the unprocessed milt provides the highest stability of the emulsion systems. The milts could be used in emulsified products both as the emulsifiers and as functional ingredients that include proteins, nucleic acids, phospholipids, and polyunsaturated fatty acids.