Quantitative information on the bottom macrofauna of the continental shelf and slope down to the depth 2025 m is generalized for the Far East of Russia and the adjacent waters of North Korea and Japan (in total 32,700 bottom trawls obtained in 224 expeditions over the area about 2 million km² in 1977-2010). The total mean biomass of macrofauna is estimated as 38.64 million tons including 21.8 · 10⁶ t of fish and cyclostomes and 16.9 · 10⁶ t of invertebrates: 22.5 · 10⁶ t in the Okhotsk Sea, 8.2 · 10⁶ t in the Bering Sea, 3.7 · 10⁶ t in the Pacific waters of Kamchatka, 2.8 · 10⁶ t in the Pacific waters of Kuril Islands, and 1.4 · 10⁶ t in the Japan Sea. The Okhotsk and Bering Seas have the higher biomass mainly because of their vast areas, but the density of macrofauna is ranked in other order: the Pacific waters of Kamchatka (64.5 t/km², without jellyfishes - 18.7 t/km²) - Pacific waters of Kuril Islands (27.1 t/km²) - Bering Sea (24.5 t/km²) - Okhotsk Sea (16.5 t/km²) - Japan Sea (11.7 t/km²). The total biomass of fish and cephalopods at the sea bottom is the following: 13.8 · 10⁶ t in the Okhotsk Sea, 4.6 · 10⁶ t in the Bering Sea, 2.7 · 10⁶ t in the Pacific waters of Kuril Islands, 1.4 · 10⁶ t in the Pacific waters of Kamchatka, and 0.9 · 10⁶ t in the Japan Sea, and their density is: 26.5 t/km² in the Pacific waters of Kuril Islands, 23.6 t/km² in the Pacific waters of Kamchatka, 13.9 /km² in the Bering Sea, 10.1 t/km² in the Okhotsk Sea, and 7.4 t/km² in the Japan Sea. The areas with narrow shelves and sharp slopes, steep and patchy relief, are usually denser populated. However, the Japan Sea has the lowest biomass and density of benthic macrofauna, possibly because of lower productivity.

Early embryogenesis and post-embryonic development of pacific cod Gadus macrocephalus Tilesius from the Tauyskaya Bay is investigated in experiment. Its fertilized eggs at stage II had the diameter 1.000-1.250 mm, on average 1.103 ± 0.003 mm. Numerous teardrop-shaped inclusions were observed in plasma of the blastodisk and in the blastomeres, presumably important for prevention of the eggs freezing under low temperature during incubation in vivo . Duration of the embryogenesis in vitro under the temperature 2.2 and 5.2^оC was 490 and 768 hours, respectively. The prelarvae hatched at the length 4.28-5.10 mm, on average 4.34 ± 0.03 mm, and turned to mixed and exogenous feeding in 6 and 10 days, at the mean length 4.97 and 5.18 mm, respectively.

A possible model approach to stock assessment of marine commercial invertebrates is discussed based on modeling of year-to-year dynamics for three functional groups (recruits, prerecruits, and commercial males). The model parameters are determined by joint solution of the tasks of optimal filtration and identification. As an example, this approach is used for assessment of the stock of king crab on the shelf of West Kamchatka. For this case, the data on actual catch are used obtained from reports of customs in Japan, Korea, USA, and China about the volume of crab products imported from Russia. The modeling confirms the conclusion from direct observations about rapid growth of the red king crab stock at West Kamchatka in recent years. Following to these results, the value of total allowable catch (TAC) can be substantially increased for this species. The officially recommended TAC of red king crab at West Kamchatka for 2016 is below of the 95 % confidence interval of the really possible catch. This value does not account the species stock recovery and hamper rational utilization of the valued natural resource.

Juveniles of pink and chum salmon are investigated in the Iska River flowing into the Okhotsk Sea. The pink juveniles begin their seaward migration in May, with the ice melting, the migration lasts about 40 days, approximately from May 20 to July 5. The seaward migration of chum juveniles begins in the same time but ends in 5-10 days later. The portion of pink salmon fry with the remains of yolk sac is 82-94 %; even in the end of their migration it is rather high, up to 76 %. This species juveniles begin to feed in the river, in particular in «dry» years, the portion of feeding fry increases with disappearance of the yolk sac up to 78 % (by the stomach fullness). Both pink and chum juveniles migrate at night only. Hydrological conditions influence on the timing of migration: it is close to normal dates in conditions of high water level and strong water flow but delayed in conditions of low water discharge (that’s why the portion of juveniles feeding in the river is higher in those years). Year-to-year dynamics of the juveniles and spawners abundance is traced for the 1951-2012. The pink salmon escapement to the Iska changed from 11.0 · 10³ (in 2004) to 1344.4 · 10³ (in 1958) ind., on average 280.0 · 10³ ind. for even years and from 22.7 · 10³ (in 1959) to 2005.8 · 10³ (in 2007) ind., on average 372.9 · 10³ ind. for odd years. The number of pink salmon downstream migrants changed from 0.8 · 10⁶ (in 1954) to 40.9 · 10⁶ (in 1964), on average 10.9 · 10⁶ ind. for even years and from 1.0 · 10⁶ (in 2005) to 41.8 · 10⁶ (in 1957), on average 8.9 · 10⁶ ind. for odd years.

Morphometric parameters of the heart, the absolute and relative caliber of the aortic arch and the major arterial trunks are determined for northern fur seal Callorhinus ursinus , Steller sea lion Eumetopias jubatus , spotted seal Phoca largha , harbor seal Phoca vitulina stejnegeri , and ribbon seal Histriophoca fasciata . The value of cardiac index, the thickness of ventricular wall, and the relative diameter of arterial trunks correlate well with energy expenditures of the entire body of mammals or their certain organs during the life cycle. The hypothesis is confirmed on seals’ adaptation to asphyxia by pronounced dilatation of the aorta ascending that ensures constant blood pressure and supports perfusion of brain and cardiac tissue.

Fecundity of northern shrimp Pandalus borealis is investigated for the first time on the data collected from the depth 200-400 m near the coast of West Kamchatka in 2013-2014. The absolute and relative individual fecundity are determined, their relationship with size and age of the shrimp is analyzed. The individual fertility of females changes in limits of 1395-4648 eggs, with average number in the laying 2799 ± 190 eggs. The maximum fecundity is noted for females at the age of 7+. Losses of eggs for the northern shrimp at the west coast of Kamchatka don’t exceed 12 %.

Dynamics of stock abundance and survival is similar for the pink salmon populations from East Kamchatka and West Kamchatka, obviously because of the same large-scale environmental factors influence, as the Pacific Decadal Oscillation (PDO) and the Western Pacific pattern (WP) that correlate significantly with the pink salmon populations indices for various stages of the life cycle. The survival measured as the recruits number per parental stock (R/S) has a non-linear dependence on this environmental indices described by parabolic equations. These dependencies are used in reproductive models, which simulate observed fluctuations of R/S with high accuracy. Note that these environmental factors influence on the pink salmon survival is opposite for its odd and even generations. For example, high PDO value in November is unfavorable for survival of the pink salmons in East Kamchatka in the first year of their life (incubation) but favorable for survival of the same population in the second year (marine feeding) - that’s why strong and weak year-classes of pink salmon are alternated. Both PDO and WP indices have quasi-biennial periodicity that is a bit longer than the 2-year alternation of the pink salmon generations, hence favorable environments change their correspondence with odd or even generations from time to time, on average in approximately every 8 years. Similar regularities are supposed for other salmon species, as West Kamchatka coho salmon.

Spatial distribution and seasonal and interannual variability are determined for parameters of the upper mixed layer and seasonal thermocline in the western deep basin of the Bering Sea in summer and fall of 2002-2013 and compared with chlorophyll- a concentration at the sea surface. The mixed layer is formed by solar heating of the sea surface and wind mixing. Its thickness doesn’t exceed 10-15 m in summer but increases up to 25-40 m in fall. The thermocline becomes deeper from summer to fall, too, in particular its lower bound that sinks from 37 to 48 m, on average; however, its thickness decreases from 20-25 to 16-22 m and temperature and density gradients increase from 0.23-0.25 to 0.37-0.45 °C/m and from 0.032 to 0.062 units/m, respectively, that means that the thermocline becomes steadier. Tendency to cooling was observed for both layers in the last decade, the process was more visible in autumn, with a shift at the upper bound of thermocline (from the mean temperature of 9.8 °C in 2002-2006 to the mean temperature of 8.4 °C in 2007-2013) and gradual decreasing at its lower bound (from 3.3 °C in 2003 to 2.1 °C in 2013), and not so obvious in summer. Year-to-year fluctuations of salinity in summer/autumn were within the limits 32.77-33.03/32.60-32.96 psu for the upper bound of the thermocline and 32.98-33.14/33.06-33.13 psu for its lower bound and had slight negative tendency. In both seasons, the mixed layer depth has significant negative correlation with the temperature at the upper bound of the thermocline (R² = 0.6) and the temperature at the lower bound of the thermocline correlates significantly with salinity at its both bounds (R² > 0.4). Spring bloom of chlorophyll- a has no relationship neither with temperature in the mixed layer in April and May, nor with the rate of warming between these months. Strong fall bloom of chlorophyll- a develops if the fall cooling begins in conditions of high temperature at the sea surface (> 6 °C) that negatively depends on the mixed layer thickness, so slow cooling and delay of the fall mixing are favorable for chlorophyll- a blooming in autumn.

Production-destruction balance is determined and primary production is evaluated for different parts of the estuaries of two rivers with different hydrological regime in Peter the Great Bay basin (Razdolnaya/Suifen and Sukhodol) in different seasons on the data of chemical surveys conducted in 2010-2013. The values of production and destruction are calculated from the difference between observed nutrients (phosphorus) concentration in the estuaries and their potential concentration conditioned by the river water dilution. The nutrients concentration in the water passing through estuaries increased in their upper parts over the potential values due to the nutrients influx from destruction, then decreased below the potential values because of the consumption for photosynthesis. Production processes prevailed over the estuaries in spring, the sign of production-destruction balance changed in summer from destruction in the upper estuaries to production in the lower estuaries, and destruction processes prevailed in autumn-winter. Productivity of the Razdolnaya/Suifen estuary is based mainly on utilization of terrigenous nutrients dissolved in its highly mineralized water, but in the Sukhodol estuary the nutrients of terrigenous origin are consumed quickly and its productivity is maintained by recycling of nutrients. Passing the estuaries, 1 m³ of both rivers water produces on average 0.8-1.0 gС/m³km that corresponds to values of primary production up to 5.6 gC/m³day in summer, with the maximum in the upper parts of the external estuaries under salinity 5-10 ‰, at the haline front dividing almost fresh water of the internal estuary from brackish water of the external estuary. Taking destruction of organic matter into account, net production is mostly below zero in the river parts of estuaries, particularly in autumn, it reaches the maximum in the upper part of external estuaries (up to 0.7-1.0 gC/m³km or 3-5 gC/m³day) and remains on lower but positive level further offshore. So, estuaries are simultaneously «marginal filters» limiting penetration of terrigenous nutrients into the sea and «factories of nutrients»: the latter process dominates in their internal parts and enhances considerably biological productivity of these water bodies.

The intertidal zone of the Gizhiginskaya Guba and Yamskaya Guba inlets located in the Shelikhov Bay is surveyed and 179 species are found in its macrobenthos (66 plants and 113 animals). They form 25 communities, including 7 ones on soft bottom sediments, 12 - on hard substrates, and 6 transitional (mixed) communities. The community of Lyonsia cucumerina is endemic of the Shelikhov Bay, it occupies the mixed substrate, namely flat rocks covered with silty sand that occur in the Gizhiginskaya Guba and at Ust’-Palana.

Impact of economic activity on environment quality is assessed for the coastal waters of the Possyet Bay (Peter the Great Bay, Japan Sea). Total volume of the sewage water discharged from coastal sources to the bay and total amount of principal pollutants wasting this water body are calculated. Specific index of sewage for the Possyet Bay is estimated as 0.081 g/m³ that is rather high value. Distribution of petroleum hydrocarbons in the coastal waters is considered: their concentration ranges from 0.025 to 0.065 mg/L. Following to biotesting results, the worst water quality is in the Reid Pallada Bay where the highest inhibitory effect on the byssus thread formation of mussel Crenomytilus grayanus is observed.

Radiation environment is assessed for the Pacific waters off Kuril Islands and effects of radiation pollution on pacific saury migrating through this area for feeding are evaluated on the samples collected by research vessels of Pacific Fisheries Research Center (TINRO) in 2011-2013 and processed in the specially equipped laboratory of this institute. Short-term increasing of the radiation background was registered in March 2011 only, and radiation pollution of the fish tissues was not detected. Obviously, the accident at the nuclear power plant Fukushima-1 had no significant effect on pacific saury. No threat to safety of the food made of pacific saury is concluded. However, a dangerous effect of the accident is possible for other commercial species of fish, in particular long-living ones that have repeated migrations through the waters adjacent to the power plant, as sardine and mackerel. These species aren’t landed by Russian fishermen now but their fishery can be resumed under growth of their populations in future.

Combined effect of two stress factors (decreasing of salinity and presence of potassium dichromate in the medium) on adaptive capacity of benthic alga Attheya ussurensis is investigated. The salinity decreasing to 20 ‰ combined with 0.01 mg/L of K₂Cr₂O₇ in the medium didn’t cause any change of the cells growth in number, as compared with uncontaminated environment (32 ‰, control), or changes in their morphology. The same salinity decreasing with K₂Cr₂O₇ concentration 0.10 mg/L caused a lowering of the cells growth to 86 % of the control value by the end of experiment that was accompanied by minor morphological abnormalities, as cells elongation in pervalvar axis direction and granulation of chloroplasts. In the second seeding, there was no change of the cells growth again under the low concentration of K₂Cr₂O₇ and their adaptation to the concentration 0.10 mg/L was observed: in the end of experiment the cells number had no significant difference from the control one. The salinity decreasing to 16 ‰ with the toxicant concentration 0.01 mg/L caused a lowering of the cells growth in the 4^th day that persisted until the end of experiment and some insignificant changes of their morphology. The same salinity decreasing with the toxicant concentration 0.10 mg/L caused a significant drop of the cells number with strong negative morphological changes; moreover, the alga wasn’t able to adapt to this combined stress after re-seeding.

Ecotoxicological assay of seawater quality along the shelf of West Kamchatka, including the areas of oil and gas deposits, was conducted in the summer of 2014. Temperature and salinity conditions were usual for summer season, as well as the field of density currents. For introduction of modern and representative bioassay methods in practice of environmental monitoring in the regions of oil and gas production and transportation, embryogenesis of sand dollar Scaphechinus mirabilis was used for biotesting. The stations with high number of the embryos and larvae abnormalities had mosaic distribution - this effect may be connected with shipping of fishing and merchant vessels.

Secondary production of macrobenthic communities is evaluated for 14 different-type estuaries in Primorye on the base of 52 surveys conducted in 2007-2013 (922 stations, 2426 samples). Species composition and abundance of macrobenthos in the estuaries depend mostly on water salinity. Three types of estuaries were distinguished: i) polyhaline with prevaled salinity 18-30 ‰ (external and internal estuaries of the rivers Ryazanovka, Barabashevka, Sukhodol, Tumanovka and external estuaries of the rivers Olga and Avvakumovka); ii) mesohaline with salinity 5-18 ‰ (external and internal estuaries of the rivers Tesnaya and Gladkaya, internal estuaries of the rivers Avvakumovka, Kievka, and Partizanskaya, Lake Presnoye and external estuary of the Razdolnaya River); and iii) oligohaline with salinity 0.5-5.0 ‰ (internal estuaries of the rivers Razdolnaya, Artemovka and Lake Solenoye). Mean annual biomass of macrozoobenthos is the lowest (2.8 ± 0.4 gС/m²) in the polyhaline estuaries and the highest in the meso- and oligihaline ones (6.6 ± 3.0 and 7.0 ± 2.5 gС/m², respectively). Annual production of macrobenthic communities in the estuaries varies from 0.5 to 11.2 gС/m², with mean values 7.5 ± 1.0 gС/m² in the polyhaline estuaries, 4.1 ± 1.3 gС/m² in the mesohaline estuaries, and 2.7 ± 1.4 gС/m² in the oligohaline estuaries, it is the highest in the polyhaline estuaries and the lowest in the oligohaline ones. The production is formed mainly by gastropods, bivalves, polychaetes and amphipods in the polyhaline estuaries; the same groups and also isopods and amphibiotic insects larvae form the production in the mesohaline estuaries, and bivalves and polychaetes are the main producers in the oligohaline estuaries. Daily production of macrobenthic community has strong seasonal variation with the maximum in July-September and the minimum (sometimes below zero) in May-June and October, i.e. at the beginning and the end of vegetation season. The portion of carnivore macrobenthos production varies from 0.7 to 26.5 % of the total annual production of macrobenthic community, it is the highest in the mesohaline estuaries. It increases from spring to autumn; in the autumn predators have the best feeding because of high abundance of young benthic animals at the bottom of estuaries. Mean annual P/B -ratio is 3.4, 1.1 and 0.4 for the polyhaline, mesohaline and oligohaline estuaries, respectively, that is conditioned by species composition of dominant taxonomic groups. Species composition of bivalve mollusks is the main factor of macrobenthic production variability: brackish clam Corbicula japonica with high biomass (up to 5 kg/m²) and low P/B -ratio (0.4-0.7, mean value ≈ 0.5) dominates in the mesohaline and oligohaline estuaries, while euryhaline marine bivalves as Macoma spp., Potamocorbula amurensis, Laternula marilina , and others dominate in the polyhaline estuaries though their biomass is relatively low (no more than 0.36 kg/m²), their P/B -ratio is 0.8-4.5. Year-to-year variability of macrozoobenthos production is supposedly significant, at least its considerable fluctuations are registered in the Sukhodol estuary (from 4.8 to 11.2 gС/m² in the 2009-2012). Estuarine macrobenthic communities in Primorye usually have intermediate values of production between those in freshwater and seawater biotopes.

Caspian seal was subjected in the 2000s to complex combined infection caused by viruses and pathogenic bacteria that led to mass mortality of this species, the only marine mammal in the Caspian Sea. So, bacteriological monitoring and detection of pathogenic microorganisms in internals and tissues of the seal were conducted in the 2007-2014 and a broad spectrum of high-adaptive pathogenic microbial associations was found. The examined mammals had not diseases of bacterial origin in that time, and the most part of this microflora was qualified as the resident one, but these bacteria were able to trigger infectious process in case of deterioration of environmental conditions (anthropogenic pollution, malnutrition, lack of ice fields, etc.). Composition and abundance of the conditionally pathogenic microflora depended on physiological state of seals: the animals with invasive diseases had more abundant and diverse sanitary-indicative microorganisms. Presence of highly adaptive opportunistic microorganisms in the organism of seal is a sign of unfavourable sanitary-microbiological state of this species and considerable persistence of sanitary-indicative microflora in the ecosystem of the Volga-Caspian basin, with significant parasitizing and multiple antibiotic resistance, that is a background for high epidemiological risk.

Results of long-term research of tumorous disease in internals of two sprat species dwelling in the Caspian Sea ( Clupeonella delicatula and C. engrauliformes ) are presented. Pathological changes are similar for both species: they are mainly tumorogenesis and abnormalities in hemodynamics and morphology of parenchymatous and reproductive organs. The visceral neoplasms are diagnosed as malignant insulocarcinomas with conditionally pathogenic micromycetes in their granulomas (identified on smears of liver and spleen). Pathogenic Hyphomycetes fungi are detected in injured organs, mostly of the genus Aspergillus. The disease is registered for all age groups of fish but is more apparent for middle and elder ages. The morbidity has strong seasonal and year-to-year variability with the maximum in 2014. Pollution of marine environments contributes to development of the epizootic process.

Wintering is one of the most complicated biotechnical processes in pisciculture, and its success depends on a wide spectrum of biotic and abiotic factors, first of all on the fish physiological status before this period. Sturgeon fishes are believed to stop feeding under the water temperature below 4 °C that causes essential reorganization of their metabolism because of transition to endogenous feeding. Physiological status of fingerlings of kaluga and reciprocal hybrid sterlet x kaluga is compared in the beginning, middle and end of wintering, with comparative characteristic of their peripheral blood reaction and understanding of starvation influence on their digestive and hemopoietic systems. The fingerlings of both species were kept in cages of warm-water farm and fed with fodder. The fingerlings of kaluga started the wintering with improper physiological status, with evident pathological processes expressed as eosinophilia, macrocytic hyperchromic anaemia, increase of immature erythrocytes, and pathomorphological changes of erythrocytes (poikilocytosis, anisocytosis, karyorhexis, hemolysis). These symptoms could be caused by either herpesvirus infection or cumulative polytoxicosis, but results of hematological and histological analysis in the middle and end of the wintering confirmed the viral nature. Thus, mass disease and mortality of fish is possible in conditions of the temperature increase in spring. Therefore, prophylactic measures are recommended for overwintered kaluga fingerlings to enhance their immune and physiological status, such as addition of vitamins C and E, probiotics and prebiotics to fodder. On the contrary, the fingerlings of reciprocal hybrid sterlet x kaluga had a high physiological status before and during wintering, in spite of a rather high portion of eosinophiles in their leukogram.

Giant freshwater prawn Macrobrahium rosenbergii is one of the most prospective species of Decapoda for artificial reproduction. It is cultivated mostly in the areas with subtropical and moderate climate, but rare is grown to the maximal size. Investigations for improvement the biotechnological process of this species cultivation were conducted in Crimea in 2010-2013, in particular for the stage of early ontogenesis. In total, 245 individuals were used in the experiments. The embryonic development was divided into 5 stages. The eggs were taken from pleopods of vital females and observed by microscope with measurements by ocular micrometer and weighting. Initial realized fecundity (IRF) and finite realized fecundity (FRF) were determined by the weight method. IRF for the females with length 7.7-14.3 cm and weight 5.2-38.4 g was 3071-54692 eggs in one clutch; FRF for the females with length 7.5-14.2 cm and weight 5.3-38.1 g was 678-39925 eggs in one clutch. Both IRF and FRF increased with the length and weight of females increasing. During embryonic development, the eggs grew in 1.5 times in size and 2.1 times in weight. The volume of the eggs ovulated and just laid to pleopods was 0.08 mm³ under the temperature 24^оC and 0.06 mm³ under the temperature 28^оC.

Technologies for processing of bivalve mollusks are developed on the base of study of their physical, chemical, and technological properties and evaluation of the food and biological value. Bivalves in the coastal waters of the Japan Sea are very different by their size and chemical composition, but all of them are a source of full value protein, essential amino acids, and some substances with therapeutic effect. Biochemical and technological properties of the bivalves differ significantly from traditional fish raw materials. Boiled and salted products of them are distinguished by high rigidity because of the high protein content of connective tissue and its specific microstructure. However, consistency of bivalve products can be regulated by means of thermal and biochemical processing of the raw material. Comprehensive waste-free technology of the bivalves processing is presented for manufacturing of food and fodder products with high consumer properties. The bivalve mollusks from the coastal waters of Primorye are considered as safe for food on the basis of phytotoxins content in their soft tissues, radionuclides activity, and concentrations of toxic elements in their foot, mantle and liver.

Data on stock and distribution of commercial and prospective for harvesting brown algae at the coast of Russian Far East are presented and compared. Their total biomass in the traditional harvesting grounds prevails 3.5 million tons. Saccharina japonica, Saccharina gurjanovae, Cystoseira crassipes have the highest biomass. However, taking into account both the stock and chemical composition of the tissues, Saccharina bongardiana, Arthrothamnus bifidus, and Eualaria fistulosa are the most profitable for harvesting and processing. The algae from the coastal waters of south-western Sakhalin have generally higher content of valuable proteins and minerals, but the content of mannitol and alginic acid is higher in the algae from the coastal waters of Kamchatka and Primorye. Contamination of the algae by toxic elements is considered, as well: in general, the safety indicators allow to regard all basic harvesting grounds of brown algae in the Far Eastern waters as suitable for commercial exploitation, though insignificant excess of the permissible level of lead (0.5 mg/kg) is detected for the brown algae from the coastal waters of Primorye and several sites in the Aniva Bay (southern Sakhalin).

Molecular-weight composition of peptides in extracts and hydrolyzates from soft tissues of the clams Corbicula japonica and Mercenaria mercenaria and liver of chum salmon is investigated. Antiradical activity is defined for low-molecular peptides, as well as for high-molecular proteins and free amino acids in the extracts. The maximum activity is detected for the extracts of salmon liver; all protein fractions in the water extract of the liver have antiradical activity. Low-molecular peptides and free amino acids have antiradical activity in all samples. The peptides with molecular weight 4.3 kDa have the highest activity in the water extract from C. japonica (43 units) and the peptides with molecular weight 4.7 kDa - in the water extract from M. mercenaria (5.6 units). After hydrolysis, the portion of low-molecular peptides increases for C. japonica , M. mercenaria , and salmon liver in 22.1, 14.5, and 11.1 %, respectively. Hence antiradical activity for hydrolyzates from C. japonica and M. mercen aria is in 1.9 times higher and for hydrolyzates from salmon liver - in 1.3 times higher than for water extracts from their tissues. Only the peptides with molecular weight 2.8-4.7 kDa have antiradical activity in the hydrolyzates; its value is 1-24 activity units for M. mercenaria ; 13-76 units for C. japonica and about 40 units for the chum salmon liver. Correlation is found between the content of peptides with molecular weight 3-4 kDa in hydrolyzates and their antiradical activity.