The material of spring registration surveys of the blue king crab Paralithodes platypus conducted in the Shelikhov Bay of the Okhotsk Sea from 2007 to 2019 is presented. It is proposed to use the relative abundance index (I%N) for a quick assessment of the characterizing state of the stock of the exploited population. The index I%N is defined as the ratio of the number of a separate functional group of the crab to the maximum number for this group of crab in the study period, expressed as a percentage. A similar algorithm was used to determine the index of the relative density of the distribution of crabs (I%P) and the index of the relative average daily catch of fishing vessels for the first half of the year (I%M). When comparing the relative indices I%N, I%P, I%M, the most convincing was the relative population index I%N. To assess the stock status of the studied functional group of crabs in the values of the index I%N, it was proposed to distinguish 4 quartiles (interval 25 units): 1st quartile (Q₁) I%N <75 stock condition is good; 2nd quartile (Q₂) I%N = 51–75 stock condition is satisfactory or relatively stable; 3rd quartile (Q₃) I%N 26–50 stock status uncertain; 4th quartile (Q₄) I%N ≤25 stock status is unsatisfactory or depressive. The boundary values between quartiles Q₁–Q₂, Q₂–Q₃, and Q₃–Q₄ are I%N values of 75, 50, and 25, respectively. The dynamics of the I%N index in the studied time period reflects the real process taking place in the fishing unit of the stock based only on empirical data.

The results in the water area from island Big Shantar to the Babushkina bay points to the existence of morphometric differences in the blue crab from the northern part of the Sea of Okhotsk. The proportions of the crab’s body change statistically significantly: in the direction from the west (severe hydrological regime) to the east (relatively warm area) crabs become more elongated in width, the right claw in all measured parameters and the height of the left claw decrease relative to the width of the carapace, and there was also a decrease in the length of the merus of the first walking leg. With the inclusion of materials from the Shelikhov Bay, in the correlation analysis, in addition to the previously found dependences (associated with the fishing length of the carapace and the height of the right claw), the clinal variability of the length of the second pereopod was also noted: its shortening occurs as in the first pereopod in the direction from west to east. When performing discriminant analysis (the sample from Shelikhov Bay was not included), the most significant morphometric differences were noted between the most remote areas: western and eastern (D²_M =2,95–3,72), which, apparently, is a consequence of contrasting environmental conditions.

In the historical aspect, the estimates of the state of the North-East Atlantic mackerel stock made at ICES in 1980–2020 are considered. The dynamics of input data for setting up models and biological reference points used in assessments in different years is analyzed. Some aspects of the international mackerel fishery are briefly presented and trends in the management of the exploitation of its stock are studied. On the basis of long-term data, the consequences of the ICES recommendations for the historical development of the international Atlantic mackerel fishery are estimated. It is shown that the significant change in trends in the dynamics of spawning stock and commercial mortality of mackerel observed in the second decade of the XXI century reflects changes in the settings of the models used and indicates the instability of estimates of mackerel stock. It is noted that only compliance with the established rules of stock operation and target biological guidelines will prevent the decline of the spawning stock of mackerel to a level below the safe biological boundaries and minimize the risk of its collapse. The necessity of strict regulation of fishing within the framework of ICES and NEAFC with the application of the principles of the “precautionary” approach and scientific research data is shown.

The concept of muscle tissue growth as a chain of successive interdependent events makes it possible to develop a system of regulatory factors influencing the nutrition and growth of fish, their health and productive qualities. In bony fish, the primary and secondary generation of muscle fibers occurs at the embryonic and postembryonic stages of development, respectively. Unlike mammals and birds, the postnatal development of fish is accompanied by hypertrophy and hyperplasia of muscle tissues throughout their life, which determines the specificity of the growth of their muscle tissue and affects the quality of fish fillets. With an increase in the fiber area over 3500 µm2 with a simultaneous increase in the density of myofibrils up to 4.901 per 1 µm2 in underyearlings and in two-year-old carp fishes (carp, grass carp and silver carp), longitudinal splitting of fibers was observed. It has been shown that the formation of muscle tissue is accompanied by sustained oscillatory processes: tension and recovery within a single hypercycle of growth processes at different levels: at the level of myofibrils and muscle fibers, thus hyperplasia and hypertrophy of muscle fibers are not separated in time and space, but naturally replace each other, providing a common myogenic task — the growth of fish and its muscle tissue. The question of their relationship requires additional research in the future.

We studied the diet of Steller sea lion (Eumetopias jubatus) on the eastern coast of Kamchatka based on the remains of undigested food parts found in feces at terrestrial sites near Cape Kozlova (rookery) and Cape Kekurny (haulout) in the summer. A total of 276 fecal samples were analyzed from 2004 to 2008. Forty eight food items of 17 fish families and one family of cephalopod mollusks were identified. Steller sea lion diet was diverse yet dominated by only several species. The pollock Gadus chalcogrammus, Atka mackerel Pleurogrammus monopterygius, Pacific sand lance Ammodytes hexapterus and Hemilepidotus sp. were dominant by frequency of occurrence in decreasing order at both sites. Differences were found in the Steller sea lion diet in the studied sites. Prey diversity at Kekurny Cape within scat samples ranged from one to twelve objects within the median of four prey item per a sample. The median of prey diversity at Kozlov Cape within scat samples was two food objects within a range of one to nine prey types per sample. Of the 37 scats (24,5 %) collected at Kozlov Cape that contained a single prey item, 75,7% contained Atka mackerel. Among scats collected at Kekurny Cape that contained a single prey species (n=10, 8,0 %), 50,0 % contained Atka mackerel and 40,0 % pollock. In contrast to the high diet diversity at Kekurny Cape haulout, breeding Steller sea lions at Kozlova Cape rookery fed on a narrow set of prey items. Interannual changes in the diet structure at each site were not statistically significant.

The results are presented on the daily and annual food consumption by killer whales with year-round keeping in net enclosures in Srednyaya Bay. The diet consisted of two species of fish: pink salmon and herring. For females, the daily fish consumption varied from 9 to 50.9 kg with an average of 32.6 kg, for males from 6 to 45.1 kg with an average of 34.1 kg. The annual minimum amount of fish for keeping one young individual in captivity ranges from 11.5 to 12.1 tons of pink salmon, which corresponds to energy requirements of 15.9 Gcal/year for females and 16.7 Gcal/year for males. An increase in the required amount of food for an animal with a decrease in water temperature was established. Based on the results of the factual material on nutrition, the annual consumption of a group of ten killer whales of different ages found in natural conditions was calculated. This value in terms of pink salmon is estimated at 200 tons of feed per year. The theoretical calculation of the annual consumption of various species of aquatic organisms by killer whales is presented. Based on the results of research and analysis of modern literature sources in comparison with historical data on the feeding of killer whales, it was proposed not to divide this species in the Sea of Okhotsk into “mammal-eating” and “fish-eating” ecotypes. In our opinion, the manifestation of different types of behavior (resident type, transit type) in killer whales should be considered, depending on climatic conditions and the availability of food objects. In hunting grounds, the resident type predominates in killer whales, which changes to a transit type of behavior when changing the feeding area or seasonal migration.

The article presents an analysis of long-term fluctuations in the area of spawning areas of three sections of the Cheboksary reservoir, depending on the water content of the year and water levels in the spring period, and their effect on the number of replenishment of the main commercial fish species. Basing on the interpretation of Landsat satellite images, the boundaries and areas of floodplain and coastal spawning areas at different levels were determined. A formula was obtained for the dependence of the area of spawning areas on water levels; the difference between the minimum and maximum values of spawning areas was 1.65 times. It was shown that a high degree of watering of spawning grounds favorably affects the reproductive success of most commercial fish species — a noticeable positive correlation was established between the number of underyearlings and the area of spawning grounds (Spearman’s correlation coefficient is 0.65 at p = 0.01). A formula was obtained for the dependence of the number of underyearlings on the area of spawning grounds, on the basis of which a forecast of recruitment in years with different degrees of water availability was given. According to preliminary calculations, the efficiency of natural reproduction can increase 20.5 times in high-water years compared to low-water years. By geo-referencing the boundaries of spawning grounds in geographic information systems, differences in the interpretation of the descriptions of spawning grounds in the Fishing Rules have also been eliminated.

The microbiological characteristic of Lake Ladoga water masses as a habitat for bioresources, based on the results of observations in June and September 2020, is presented. At the beginning of summer, a heterogeneous spatial distribution of bacterioplankton was observed, because of the water temperature discrepancy in different regions. The maximum values of the total bacterial counts (TBC) were discovered in the southeastern coastal area and the area of the Sortavala skerries, whereas the minimum values were found in the deep-water region. In autumn, the distribution of bacterioplankton was rather uniform due to the equalization of water temperatures in the surface layer. The average values of the TBC during the observation period indicate that the trophic state of the various areas of the lake ranged from oligotrophic in Petrokrepost Bay to mesotrophic-eutrophic in the southeastern region and Sortavala skerries. According to the numbers of saprophytic microorganisms (SM), the water masses of the lake, except for the skerries, were identified as “clean” and “very clean”, which corresponds to xeno — and oligosaprobic waters. The amount of total coliform bacteria (TCB) and thermotolerant coliform bacteria (ThCB) was significantly lower than the standards established for different categories of water use. The exception was the site at the mouth of the Volkhov River in June, where the number of TCB and ThCB exceeded the norms by an order of magnitude, indicating the presence of fecal contamination. The presence of salmonella in the water masses was not detected. The values of microbiological parameters indicate high water quality in most regions of Lake Ladoga. However, some areas of environmental risk due to anthropogenic impact have been identified: the Volkhov Bay, including the mouth of the Volkhov River, areas in the skerries near the cities of Sortavala, Lakhdenpokhya, and Pitkyaranta, and the water area beside a city of Priozersk.

The article presents the problem of receiving and processing fat-containing raw materials from the covering fat of ringed seal (Phoca hispida) inhabiting the territory of Arctic Yakutia. The extreme weather and climatic conditions of Arctic Yakutia determine the high content of saturated and unsaturated fatty acids (PUFAs) in the covering fat of marine mammals. For the human body, these fatty acids are essential because PUFAs are local or tissue hormones that modulate the metabolism and activity of both the cell itself and its environment. A special feature of marine mammal and fish fat is the presence of PUFA acids with double bonds, which are not found in plant and animal lipids. Ringed seal is the most numerous and widespread type of marine animals on the territory of the Arctic Yakutia. The specific features of the chemical composition and bioactive properties of the seal blubber make it necessary to develop specific methods and technologies for fishing, harvesting and complex processing of this animal type in this territory. The duration of the season of negative temperatures (8 months a year) is a significant difficulty for commercial fishing of marine mammals in the territory of Yakutia. They were harvested only in the last century, but never on an industrial level. The seals were harvested for hides, fat and meat. Nowadays in Yakutia, the local population produces ringed seals by the piece, for personal purposes, and there is no commercial processing.

The analysis of the pricing mechanism in the domestic market of fish products of the Russian Federation is carried out. To do this, we used official data published by the Federal State Statistics Service on average prices for frozen fish, which accounts for two-thirds of the entire domestic market for products from aquatic biological resources. The growth in prices for fish products in the period under review (2016–2020) was within the inflation (19.7%) and at the level of the growth in prices for the food group as a whole. An assessment is made of the stability of the all-Russian domestic fish market and the optimization of prices for its products. An expert assessment of the shares of participation of manufacturers of fish products, representatives of the wholesale and retail market segments in the formation of prices was carried out. The levels of profitability from the sale of each of them have been determined. Suggestions were made on the possible further development of the fishery complex of the Russian Federation, including sources of financing and implementation mechanisms.

The world development of aquaculture is disclosed on the example of 10 countries and Russia. Using the extrapolation method, the dynamics of the development of commercial fish farming in the Russian Federation has been revealed. The investment attractiveness of the development of aquaculture in the European North of Russia is analyzed (by the example of the enterprise LLC «Russian Sea — Aquaculture»). The volume of Atlantic salmon cultivation in the world and in Russia is given. The production of marketable fish in the constituent entities of the Russian Federation for 2020 is analyzed. The water fund of inland water bodies and coastal waters of the seas of Russia, including the territory of the North-West Federal District, is presented — the potential for the accelerated development of aquaculture. The policy of import substitution and government assistance are disclosed as an important stimulating factor in the development of aquaculture. European North of Russia. Among the results obtained, the following can be distinguished: the factors that reduce the economic efficiency of growing and selling salmon products have been substantiated; the causes of salmon diseases in the European North of Russia are revealed, and an analysis of the impact of the development of commercial farming of Atlantic salmon on import substitution is presented, and the level of impact of cage farming on the ecology and on the gene pool of natural salmon populations is revealed. Particular attention is paid to the economic efficiency of feed.

Based on the results of own work and published research analysis it is shown that small UAVs can be used efficiently for cost-effective evaluation of fishes, mammals, benthic vegetation, IUU catches and landscape mapping. These devices enable point, sample and total surveys of marine areas. UAVs are well suited for integrated re search programs utilizing diverse methods. Small UAVs application enables significant savings of research time and expenditures. To achieve peak efficiency of drones it is necessary to account for their technical capabilities, constraints and vulnerabilities. Optimization of UAVs deployment to survey area is an important factor in in creasing their efficiency. Software for automatic flight mission execution allows to expand surveyed area and decrease accident rate. Software for automated photo grammetric processing of acquired aerial photography allows to minimize efforts for orthophotos production. Created orthophotos serve as a basis for aquatic species distribution mapping, abundance estimates and GIS visualization. Due to low cost and high functional characteristics modern consumer UAVs already can play a key role in marine coastal biological studies. Their importance as an instrument for such research programs will increase shortly along inevitable growth of their technical characteristics and decrease in price.

The materials of scientific research work in the Pacific waters of the Kuril Islands in the period of September — October 2020 are presented. The joint flow of the coastal and seaward branches of the Oyashio formed a zone of below zero temperature anomalies. Soy stream waters were characterized by positive temperature anomalies. According to acoustic data, the occurrence of Far Eastern sardine and Japanese mackerel was recorded in a wide range of ocean surface temperature from 8.4 °C to 19.9 °C, however, trawling in the ocean surface temperature range for S. melanostictus — 14.3–15.5 °C, and for S. japonicus — 14.2–15.1 °C turned out to be more effective. The number and biomass of Japanese mackerel amounted to 756.6 million specimens and 61.5 thousand tons, Far Eastern sardine — 3924.2 million specimens and 144.3 thousand tons, respectively. The number and biomass of the entire trawl nekton in the study area amounted up to 30749.6 million specimens and 264.5 thousand tons.

The materials of scientific research of studies of the Atka mackerel Pleurogrammus monopterygius, Pacific beak perch Sebastes alutus and by-catch species carried out in fishing areas of the Far Eastern region (West Bering Sea zone, Karaginskaya and Petropavlovsko-Komandorskaya subzones of Eastern Kamchatka) in April 2021. Data on the productivity of catches and the formation of pre-spawning clusters were analyzed, differences of Atka mackerels biological characteristics in three fishing areas were noted. Ichthyopathological studies of Atka mackerel, Pacific beak perch, Walleye pollock and Alaskan thorny-head were carried out and indicated a low proportion of fish with pathologies of organs and tissues. Danger parasites for humans (Anisakis sp.) and parasites that spoil products (cestodes (Nybelinia sp.) and protozoa (Microsporidia spp.) were noted. A high degree of invasion by the larvae of nematodes Anisakis sp. of the studied fish was established in the liver and body cavity. However, the proportion of muscle damage by these parasites was low. During the study of the gastrointestinal tract of the Pacific beak perch polymer particles were found.

In March 2021, the four-masted barque «Sedov» celebrated its centenary. On the eve of the anniversary, in August- October 2020, the training sailing vessel (TSV) barque «Sedov» for the first time in the history of Arctic research made the crossing along the Northern Sea Route in one navigation without ice wiring, covering 7.1 thousand miles on the passage from Vladivostok to Murmansk. VNIRO’s scientific staff made observations on the shelf of the north-western part of the Pacific Ocean and the Arctic Seas along the ship’s route. Methods of collecting samples for the assessment of sea pollution with microplastics, oceanographic conditions, the number and distribution of marine mammals, adapted to the working conditions of a sailing ship in the Arctic seas, were developed during practical training with cadets. Scientific observations made during the passage of the barque «Sedov» along the Northern Sea Route showed the possibility of using training sailing vessels of Rosrybolovstvo to collect relevant data on the biota, environmental conditions and ecology of the Seas and Oceans.