Defnition of the term adaptive zone (AZ) is amended. The Petersen-type communities (PC) are not communities in every sense of the word. They are just the areas within which the same species prevail in their abundance. An accounting gear used for identifcation of PC must be suited for catching of the most abundant species. All dominant species must be represented in the lists, regardless of whether they are seasonal or permanent components of population. Only one factor (either number of individuals or biomass) has to be used for species abundance comparison. For recognition and naming of several PC, the same number of the dominant and subdominant species should be used. Under the abovementioned conditions, if this number is equal to 1 — this method selects nothing more than AZ, which are the elementary PC. The fundamental ecological niche (EN) of a species includes its realized AZ — the real space actually coincides with its geographical range (GR). The GR is situated inside the EN, and the realized AZ is a part of GR. The GR (and sometimes EN) of different species can be partially or fully overlapped, but their AZ cannot be overlapped. Each AZ is compliant with a certain species, but not each species is compliant with AZ. AZ are available to the most dominant species and the size of AZ may serve as one of simple measures of the species capability for survival or success in their struggle for existence, and corresponds to portion of total ecological capacity of the environment used by the species. The interiors of the species GR may contain from zero to several AZ, both of this and other species. The interiors of the species AZ also contain parts of GR of other species having similar requirements to the environment (prey, predators, parasites, competitors, symbionts, and other biotic habitat factors). Potential AZ may be located both inside and outside the real GR of a species, but only within its fundamental GR. The potential AZ can be realized by changing the environmental conditions or passing through existing barriers of distribution. Transformation of potential AZ into a realized one can cause an ecological catastrophe if it breaks the existing balance and leads to signifcant redistribution of the shares of total ecological capacity available for species. But even signifcant changes in the ratios of GR and AZ of species will not cause catastrophic consequences in conditions of abundant vital resources, if ecological capacity of the environment is not flled and packing density of EN is low. Changes in the environment, as well as ontogenetic, migratory, succession and evolutionary processes cause changes in ratio of abundance between different species, including mass ones, that leads to variability of their AZ. Number, sizes, shapes, location of the AZ change progressively, both on the actual and geological time scales, and cyclically in accordance with circadian, seasonal and perennial rhythms. Therefore AZ, as well as GR, EN and communities, should be studied in dynamics and in connection with changes in the environment. Defnitions of the main terms are presented in a Supplement.

Despite the long history of studies, some aspects of the greenland halibut biology in the North Pacifc are still poorly known. In particular, scientifc publications on its groupings in the Bering Sea and at the continental slope of the North Pacifc and their dynamics are rather few, with exception of the western Bering Sea area from Cape Olyutorsky to the Anadyr Bay where its dynamics is well traced by surveys of Pacifc Fish. Res. Center (TINRO). All data on long-term dynamics of the greenland halibut abundance and distribution in the Bering Sea and Pacifc waters at Kamchatka and Kuril Islands are overviewed and comparatively analyzed, including materials of bottom trawl surveys conducted in 1950–2015 and published research reports, in total the data of 66 surveys (4,350 bottom trawls) in the Karaginsky and Olyutorsky Bays, 43 surveys (4,900 trawls) on the Pacifc shelf and continental slope of Kamchatka and northern Kuril Islands, and 24 surveys (2,048 trawls) at southern Kuril Islands. Biomass of greenland halibut is assessed for the western Bering Sea and the Pacifc waters at Kamchatka and the Kuriles using the data of TINRO and for the eastern Bering Sea using the published data of NOAA and NPFMC. Gradual decreasing of commercial value of the halibut groups is shown with increase of the distance from its main spawning grounds in the southeastern Bering Sea. Self-reproduction of the halibut groups supposedly decreases in the same direction. This assumption is confrmed by the data on its larvae and juveniles density in the epipelagic layer of the western Bering Sea and North-West Pacifc that decreases from the maximum values in the Anadyr Bay to the Olyutorsko-Navarinsky district and further southward to the minimum value at southern Kuril Islands. The average portions of certain groups of greenland halibut in its total biomass in the North Pacifc (without the Okhotsk Sea) are estimated as follows: almost 85 % (146.0 . 103 t) is contributed by the southeastern Bering Sea, about 14 % (23.2 . 103 t) — by Olyutorsko-Navarinsky district and the Anadyr Bay, and 1% (about 1.5 . 103 t) — by the waters at northeastern and eastern Kamchatka and at Kuril Islands. Stock dynamics is similar for all groups: the stocks increased until the early 1970s with the peak in 1976–1980, when the species biomass was estimated as 280 . 103 t in the southwestern Bering Sea, 40 . 103 t in the Anadyr Bay and Olyutorsko-Navarinsky district, and 5 . 103 t in the bays of eastern Kamchatka and at northern Kuril Islands, then declined to the minimum in 1990–2000s, and recently the peripheral groups show a gradual growth. The dynamics similarity is possibly reasoned by passive transfer of the halibut eggs and larvae from the Bering Sea toward eastern Kamchatka and Kuril Islands by the system of oceanic currents.

Spatial distribution and reproductive ability of the pacifc oyster Crassostrea gigas aggregations in the northern Amur Bay (Peter the Great Bay, Japan Sea) are investigated using the data of direct and remote accounts. Totally 772 oyster banks and reefs are detected with the summary area of 284.6 hectares that is signifcantly larger than earlier assessments. The 35 giant beds (> 1 ha) occupy 53.2 % of the summary area, but 79.8 % of mollusks gather in medium and large aggregations which occupy 45.5 % of the summary area. Majority of the aggregations (> 95 %) are located on shallows with the depth less than 5 m. The oyster matur-ing is completed when it reaches the size of 50 mm. The ratio of males to females is 1.0 : 1.5, on average, that indicates indirectly favorable habitat conditions for C. gigas. Males prevail among the small-sized individuals, but females prevail among the large-sized ones that corresponds to reproductive strategy of pacifc oyster and type of its reproduction. The males to females ratio changes from year to year. Portion of young mollusks is rather high (13.9–56.2 %), portion of the main reproductive groups changes from 40.6 to 88.9 % that indicates active processes of natural reproduction and the oyster reefs forming. Mollusks with high reproductive rate prevail among the main reproductive group with the size 70–130 mm (58.2 %). The largest number of such individuals is observed in the largest aggregations of oysters at Rechnoy Island (85.0 %) and at Skrebtsov Island (60.7 %). Spatial variations of the shells shape and ratio of size-physiological groups in the aggregations reflect patterns of the habitat conditions. Generally, the state of native oyster aggregations in the northern Amur Bay is stable with a tendency to their population increasing.

Results of biological and physiological surveys of juvenile coho salmon from hatcheries of Magadan Region (artifcial origin) and from the main rivers of the northern Okhotsk Sea coast (natural origin) are presented. Biological and morpho-physiological indices of coho fry are compared between different salmon hatcheries and different rivers. Hematological indices for the fsh of natural origin are considered in dynamics. Positive effect of the higher water temperature and longer growing in artifcial conditions on length, body weight, fatness, feeding intensity and morpho-physiological indices of internal organs (liver, intestines) is detected for the coho fry; effect of the water temperature on length and weight of coho salmon in natural conditions is also positive. There is concluded that the coho salmon growing from the larvae under relatively high and stable temperature (4–5 oC) can provide the weight of fry over 0.6 g no later than middle July. If coho salmon is cultivated in conditions of low temperature (0.8–1.0 оС), the short-term growing before release (2.0–2.5 months) under a higher temperature (> 5o) is recommended to improve its fry quality, possibly in the nursery ponds equipped in natural reservoirs — in this case, the juveniles with the weight over 1.0 g could be produced in late August. Hematological indices are measured for different age groups of coho salmon from several rivers. Their dependence on the water temperature was not determined because of high variety of physiological state. However, a signifcant deviation to decrease from the normal values was detected for the red cell count and hemoglobin content in blood of the coho juveniles caught from the Taui River in 2018, obviously reasoned by their younger age and lower size and weight. The juveniles caught from the Yana River in 2016 had no signifcant deviations from the normal values, except of the hematocrit value that indicated stable conditions of their habitat and normal age structure. The hematological indices (hemoglobin content and red cell count) of coho juveniles caught from the Taui River in 2013 and 2014 corresponded to the end of downstream migration. Increasing of hematological indices with age of juveniles is found for coho salmon of natural origin living in favorable environments (favorable water temperature, good food supply).

Main bioenergetic parameters are evaluated for 14 species of pelagic fsh and squids from the Okhotsk Sea, with special attention to walleye pollock and pacifc herring. Caloric value of the muscle tissues varies from 867 cal.g–1 (squid) to 2062 cal.g–1 (chinook salmon) in wet weight and from 5151 to 6484 cal/g in dry weight. The studied nekton species are mostly distinguished by high caloric value of the muscle tissue, with exception for pollock and squids with the value < 1000 cal/g WW. Lipid fraction in the pollock tissues varies from 0.7 to 1.1 %, proteins are 15.5–17.9 %, and carbohydrates — 0.6–0.7 % in wet weight, the average caloric value is 979–1131 cal.g–1 WW or 5154–5264 cal.g–1 DW. Dynamics of the main biochemical parameters and the total caloric value shows weak ontogenetic changes for the pollock muscles, without signifcant difference between different stages of gonad maturity both for males and females. During maturation, amount of accumulated energy remains constant in soma, but changes in liver and gonads of pollock, and their energy content is noticeably higher for females than for males: on average in 3 times in gonads and in 1.5 times in liver. The total amount of energy accumulated by pollock during its life cycle from juvenile (< 17 cm) to extra large individuals (> 60 cm) is estimated as 1964 kcal for females and 1465 kcal for males. Caloric value for the muscle tissue of mature herring is lower in spring (on average 1498 cal.g–1 WW) than in autumn (1676 cal.g–1 WW), and for the whole body (mince) is in 1.2 times higher for juveniles, in 1.7–1.8 times higher for adults in spring, and in 2.1–2.2 times higher for adults in autumn after fattening, with average exceeding in 20–40 %. Lipid fraction in the herring tissues is on average 6.2 % in spring and 6.6 % in autumn. In spring, the maximum values of biochemical parameters are registered for the herring with gonad maturity at stage III. Later, during transition to the stage IV, and especially to the stage V, the fat decreasing and proteins watering is observed in its muscles. On opposite, the post-spawning herring at stage VI–II has the minimum parameters and caloric value in spring but enhances them to autumn, after intensive fattening, when caloric value of its mince becomes twice higher than for muscle tissue because of lipids accumulation in the subcutaneous tissue. The main energy parameters of the mature herring tissues in autumn are close to those in spring (by maturity stages), with only slight increase of fatness and caloric value, which are the maximum in autumn for mince, mostly because of fat accumulation in viscera and subcutaneous tissue. Caloric value of the herring gonads varies from 1330 to 1714 cal.g–1 WW, 4809–5894 cal.g–1 DW for females and from 1155 to 1604 cal.g–1 WW, 4809–5894 cal.g–1 DW for males, with the maximum at the maturity stage IV (the same as fat content), both for males and females. The gonads caloric value is higher in spring, immediately before spawning. For herring, the major amount of energy is concentrated in soma, and its portion increases during the life cycle from 55.0 to 72.1 %, on average. Males and females of herring have common patterns of this value dynamics in the process of ontogenesis, though females have higher percentage for gonads. In annual cycle, the maximum portion of energy concentrates in the herring gonads in spring (16.7–22.1 % for females and 13.1 % for males) and decreases to autumn. The total amount of energy accumulated by herring during its life cycle is estimated as 542 kcal for females and 476 kcal for males. Females accumulate more because the oogenesis requires more energy than spermatogenesis.

Exchange of Bivalvia and Gastropoda larvae between the Aniva Bay and Busse Lagoon is described on results of the plankton survey conducted in the connecting Suslov Channel in 2014. Taxonomic composition of meroplankton is described. Tide-induced water exchange through the channel is estimated, as well. The total water flux is evaluated for each tidal cycle using the data on the water level in the lagoon and on the area of its water mirror. The main factor of the larvae exchange is the tidal water flow that reaches the rate of 4 knots both for ebb and tide currents. The meroplankton from the lagoon is transported by the ebb current rather far to the sea, and its reverse drift with the tide current back to the lagoon looks doubtful, so export of the meroplankton from the lagoon is detected, with certain seasonal dynamics. The export is the most intensive in early summer (July) because of earlier spawning in the lagoon, which water is warmed quicker on shallows. The exchange decreases in August, when the water temperature is the highest both in the lagoon and in the Aniva Bay and many species spawn actively in both areas. Both reverse transport and export of the larvae are low in September because of the water cooling and cessation of the spawning.

Habitat conditions, as qualitative and quantitative composition of aquatic vegetation and oceanographic factors, are compared for six populations of sea urchin Strongylocentrotus intermedius with different growth rate and mean size of individuals. The highest growth rate is observed in the areas between Cape Sosunov and Plitniak Bay, between Oprichnik Bay and Cape Grozny, and between Cape Lisuchenko and Kreiser Rock Island; all these areas are distinguished by high density and species diversity of macrophytes. On the contrary, the growth rate is the lowest at Cape Yuzhny where the vegetation is less abundant. All populations of slow-growing sea urchins inhabit the areas exposed to wave action that usually forms flat rocky platforms: at Cape Yuzhny, at Cape Nadezhda, and between the Yezhovaya Bay and Cape Khitrovo. However, density of sea urchin populations in these areas is higher (on average from 9.8 to 20.8 ind./m2) than in the areas with relatively high growth rate (from 0.16 to 7.20 ind./m2). Any signifcant correlation between the water temperature and mean size of sea urchins, by ages, is not detected.

Two groups of juvenile sockeye salmon are feeding in Lake Azabachye. They belong to the 2nd order stock of the lake (stock A) and to other 2nd order stocks of middle and down stream tributaries of the Kamchatka River which underyearlings migrate into the lake for feeding and wintering (group E). The main part of the stock A leaves the lake to the sea at the age 2+ (mainly 2.3) and the youngsters of the group E migrate to the sea at the age 1+ (mainly 1.3). The body length and weight parameters of the stock A smolts at the age 2+ and the group E smolts at the age 1+ could be similar or dissimilar in particular years. The maximal difference between the smots of these stocks is observed in the years with higher body length and weight for the stock A. Mean for 1979–2016 length and weight of smolts at abovementioned ages are evaluated as 98.42/87.46 mm and 10.40/7.38 g for the A/E stocks. For the stock A, statistically signifcant positive correlation is noted between size-weight parameters of smolts in the years of emigration and their abundance in the years of mass return. However, the regression has a shift between the periods of emigration/return of 1979–2000/1982–2003 and 2003–2013/2006–2016. The correlation is higher for the frst period (r = 0.820; P < 0.001 for body weight and r = 0.797; P < 0.001 for body length, n = 16) than for the second one with higher abundance (r = 0.669; P < 0.05 for body weight and r = 0.711; P < 0.05 for body length, n = 11). On opposite, the returns of the group E depend weakly on size-weight parameters of its smolts for the period of emigration/return of 1979–1997/1982–2000 (no data for return in 1999) and the dependence is insignifcant for the period of 2000–2013/2003–2016.

Pacifc herring stock was evaluated for two fshery districts in the Okhotsk Sea (North-Okhotsk and West-Kamchatka subzones) on the data collected during winter-spring fshery in 2017. The method of evaluation is described, quality of the materials collected aboard commercial fshing vessels is discussed, and the assessments are presented. Taking into account the areas of the districts and density of fsh distribution, the stock of herring is counted as 1854.92. 103 t (7390.36 . 106 ind.), mostly within the North-Okhotsk subzone (64.6 % by biomass). More than 90 % of this stock was formed by herring of commercial size that means that its juveniles were not counted properly by commercial catches. So, the stock assessment on the data of commercial catches could be used as additional method of the commercial stock monitoring, beyond the data of scientifc surveys.

Later embryonic development of Sebastes trivittatus passes in 20 days under water temperature 10 оС (in June-July). During this period, the embryos of S. trivittatus increase in diameter from 0.1 mm to 1.3 mm and change their shape from spherical to elliptical. Within gonads of pre-hatching females, the embryos have different stages: from prelarvae on late stages of development in the internal layers to pre-hatching larvae in the external layer. The pre-hatching larva has TL 4.1 mm, 5–6 melanophores on the top of head, 20 melanophores in ventral row, some melanophores on peritoneum, and oil globule in the frontal part of intestine; its notochord is not flexed, yolk sac is absent, body myotomes are poor visible, number of tail myotomes is 24.

Species composition and quantitative distribution of seaweeds on the shelf and continental slope of Primorye in the northwestern Japan Sea (depth 20–750 m) are considered on the data of trawl surveys conducted in 2015–2016. In total, 26 seaweed species were found: 16 Rhodophyta, 7 Phaeophyta, 1 Chlorophyta, and 2 species of sea grass. Most of the species were found on the depth < 60 m where the biomass of seaweeds varied from 44 to 569 kg/km2. On the depth about 100 m, the biomass decreased signifcantly to the value < 36.4 kg/km2, and only single seaweeds were found on the depth > 700 m. There is supposed that the lowest limit of the phytal zone in the northwestern Japan Sea is located at the depth 50–100 m.

Qualitative and quantitative composition of parasites from herring (Dolgino population), caspian shad, and big-eyed shad is analyzed on the data of long-term samplings, using traditional methods and determinants for identifcation. The community of parasites has temporal fluctuations associated with changes of habitat conditions, including feeding base for hosts, and depended on biological features of both parasites and their hosts. The basis of the herring parasitofauna is composed by specifc and euryxene species. Monogeneans and intestinal trematodes has a stable high degree of infection. Helminths dangerous for human and epizootically signifcant parasites are recorded sporadically. Hyphae of microscopic fungi are found on the smears-prints of parenchymal organs of herrings with domination of gen. Penicillium. All detected parasites do not cause signifcant clinical deseases in organisms of the investigated species.

All available oceanographic data for the deep-water part of the Okhotsk Sea, in total 111,944 stations collected in 1931–2014, are analyzed after removing the duplicate and lowquality ones. The mixed layer depth is determined on the water temperature profle for each station and monthly mean values of temperature and salinity in the mixed layer are calculated for the 0.5о-size grid. In May-October, the mixed layer depth varies within the range 5–25 m, with the highest values in the areas with active water dynamics. On the contrary, the mixed layer is much deeper in December-April when its thickness exceeds 40–60 meters and even reaches 100–120 m in the central Kuril Straits. Two types of temperature distribution change annually within the mixed layer in the Okhotsk Sea: the winter pattern with higher (positive) temperature at Kuril Islands occurs in December-April and the summer pattern is formed in June-September and is distinguished by spots of lower temperature in the dynamically active  areas with strong tidal and non-tidal currents (Kuril Straits, Kashevarov Bank, entrance to the Shelikhov Bay, Shantar Islands vicinity, northeastern shelf of Sakhalin Island). Transition patterns of the temperature distribution are observed in May, October, and November. Largescale patterns of salinity distribution within the mixed layer are permanent throughout a year and indicate prevailing currents and other processes in the upper layer of the Okhotsk Sea. The maximum salinity is observed in the southern Okhotsk Sea, whereas the lower salinity values are usual for the coastal waters (except the coasts of Kuril Islands) affected to the river runoff.

Satellite data on chlorophyll concentration from ESA (CCI-OC) and Goddard Space Flight Center, NASA and shipboard observations of CTD, P, N, Si, inorganic carbon, DCI, and Chl a at 38 stations in the northeastern Japan Sea (46th cruise of RV Academik M.A. Lavrentyev on July 9–19, 2009) are analyzed. The highest chlorophyll concentrations were found in the subsurface layer (depth 20–40 m) or even deeper in the Polar Front zone, so they were not reflected in the satellite data. The minimal depths of the subsurface maximum were observed northward from the Polar Front where the estimations of chlorophyll concentration in the upper optical layer (Zd = 1/kd) were similar for the shipboard and satellite measurements (on average 0.384 ± 0.160 mg/m3 and 0.406 ± 0.120 mg/m3, respectively). Primary production was calculated using the assimilation number 4.46 mgC/mgChl per hour. Depth of euphotic layer was estimated using the vertical profles of nutrients and Chl a. Within this layer, the primary production in the northeastern Japan Sea was evaluated for the shipboard stations as 895–2275 mgС.m–2.day–1, on average 1450 ± 430 mgС.m–2.day–1, and for the satellite data on average 770 ± 190 mgС.m–2.day–1. The estimations based on the shipboard and satellite data were weakly correlated. The shipboard estimations exceed considerably the results obtained by Koblents-Mishke et al. (1956, 1970) and Yamada et al. (2005). Poor accuracy of satellite estimations of primary production is concluded because the deeper part of the euphotic layer with the maximum concentration of chlorophyll is in shadow for satellite sensors.

Cell number dynamics and growth rate of microalgae Dunaliella salina (Chlorophyta) and Phaeodactylum tricornutum (Bacillariophyta) are considered in dependence on selenium concentration in the medium. The concentrations 0.01, 0.10, and 0,50 mg/l were tested. Onetime addition of selenium did not influence on the cell number and morphology of D. salina. Under repeatable addition of selenium (every 2 days), reliable differences in the cells number were detected for the concentration 0.10 mg/l only, but the concentrations 0.01 and 0.50 mg/l did not make any effect on the cells different from the control. Under frequent repeatable addition of selenium (every day), the concentration 0.50 mg/l caused a visible decreasing of the cell number in compare with the control sample — after 6 days the cells started to decay, settled to the flask bottom and aggregated, the suspension color turned to yellowish. Reaction of diatom Phaeodactylum tricornurum was more complicated. Its cell number increased signifcantly against the control under both one-time addition of selenium in the concentration of 0.10 and 0.50 mg/l or the repeatable addition in every 2 days in the concentration 0.01 and 0.10 mg/l. But more frequent (every day) addition of selenium in the concentration 0.50 mg/l caused inhibition of the cells growth and decreasing of their number against the control sample — after 4 days the cells adhesion to the flask bottom was detected, apparently because of their metabolism alteration.

Marine farms in Peter the Great Bay are oriented predominantly to cultivation of bivalve mollusks that causes excessive accumulation of biodeposits in the areas of plantations. To reduce this negative impact on the ecosystem, development of bicultural farms with cultivation of flterfeeders and detritivores is recommended. In the area of mussel (Mytilus trossulus) plantations in the Sukhodol Bay, the sedimentation rate reaches 34.1 g.m–2.day–1, with mean portion of organic carbon in the biodeposits as 20.2 %. Annual biodeposition from 1 hectare of mussel plantations is about 124 t that corresponds to annual consumption of detritus by 1 million of 1-year-old sea cucumber Apostichopus japonicus. By the end of the 4-year cycle of cultivation, the sea cucumbers of commercial size consume this amount of biodeposits within a month (60 g of organic carbon per year each). Production of a sea cucumber plantation with 5 million juveniles of sea cucumber settling every year can exceed 700 t in 10 years of operation, if it is mounted within the bicultural marine farm with bivalve cages as additional source of suspended organic matter.

Reproduction of japanese scallop Mizuhopecten yessoensis in the Busse Lagoon (Sakhalin Island) is investigated. Abiotic environments influence on duration of early stages in its life cycle is determined. Interannual variability of the scallop larvae abundance and timing of its settling on substrata is traced. The Busse Lagoon is recommended for using as a natural source of seeding material (spat) of japanese scallop.

The Possiet Bay in the western Japan Sea is crucially important for marine aquaculture of Primorye because of the environments favorable for cultivation of many aquatic species. The local marine farms cultivate sea cucumber and several bivalve species, including the most valuable yesso scallop, which output production is counted in hundreds of tons. The number of farms in the Possiet Bay increases recently, as well as their production of seeding materials and marketable output of seafood. Cultivation of 3 bivalve species (yesso scallop, pacifc blue mussel, and pacifc oyster) and 1 holothurian species (japanese spiky sea cucumber) is considered. The seeding material is collected by the farms located in the Possiet Bay, which prefer to collect more valuable spat of the scallop and sea cucumber, while the mussel and oyster are collected in smaller amounts. In total, more than 640 million of the scallop juveniles and about 1.2 million of the sea cucumber juveniles were collected by local farms in the period from 2000 to 2015, including both the spat collected on their own collectors or bought from other vendors. Dynamics of the output is presented for these species. The greatest harvest of the marketable scallop (over 1800 t) was produced in 2006–2010, with the highest annual output over 510 t. The summary production of all marine farms in the Possiet Bay within the 15-year period (2001–2015) is estimated as 4,300 t, that exceeds the registered catch of scallop in this area in the whole history of its fshery (that was banned in the middle of 1980s). Even before the fshery opening in the early XX century, the yeaso scallop biomass in this area did not exceed 1,000 t. Dynamics of anthropogenic pressure to the Possiet Bay waters is analyzed, as well. There is concluded that yesso scallop has natural ability to considerable growth of its biomass because of high fecundity, though this potential is limited by lack of substrate for the spat settling that is successfully compensated with artifcial substrata provided by marine farms. However, the growth of scallop biomass and production causes higher phytoplankton consumption, increasing of water pollution by dissolved and particulate organic matter, and accumulation of metabolic by-products in marine organisms. Rapid development of aquaculture causes some social and ecological risks, as well, as territorial disputes, legislative problems (with harvesting permits, etc.), starfsh expansion, grazing of farmed mollusks by marine birds, destruction of aquaculture facilities in new areas located in the insuffciently closed bights by typhoons, and epizootics (most dangerous for the sea cucumbers).

The rigging parameters calculation for midwater trawls are discussed with description of numerical model for calculating the parameters of trawl boards, hydrodynamic kites, and dispersed and concentrated weights which provide the designed values of horizontal and vertical opening of the trawl mouth. A distinctive feature of the proposed technique is a systematic approach: the trawl, trawl boards, and wires are considered as a joint complex.

Biological activity of tissues and enzyme hydrolyzates is investigated for three species of bivalve mollusks: Corbicula japonica, Mercenaria mercenaria, and Anadara broughtonii. Antiradical activity of all samples has increased signifcantly during their enzymatic hydrolysis: in eight times for C. japonica, in three times for M. mercenaria, and in 2.5 times for A. broughtonii. The highest anti-trombolitic activity (0.0823 units) is found for the hydrolyzate of C. japonica in concentration of 10 mg/mL. Angiotensin I-converting enzyme inhibitory activity is found only for the hydrolyzate of M. mercenaria in concentration of 10–100 mg/mL. The maximum inhibitory activity for alpha-amylase and alpha-glycosidase (7.5 and 7.2 %, respectively) is observed for the hydrolyzate of M. mercenaria in concentration 1 mg/mL. Hepatoprotective activity, measured by survival rate of HepG2 hepatocytes, is detected for the hydrolyzate of tissues for all species in weak concentrations: 0.1 mg/mL for C. japonica and M. mercenaria and 0.2 mg/mL for A. broughtonii.