The aim: Investigation of the survival rate of the red king crab during trawl fishing under the conditions of a research survey.
   The methods: The paper based on works which were completed in 2020–2021 through the trawl survey in the Barents Sea. King crabs were overexposed on the open deck of the research vessel and after that they were keeped in traps and dropped out in the sea water of 15 m depth and keeped there more than 1.5 hours. Crabs heath conditions were checked after the experiments. We also used data on the state of the environment in the area of work and data on the number of injured individuals in the catches.
   The newness: This is a first comlex research of king crabs survivability on the Barents Sea during the trawl catch. The same works were provided on the Barents Sea through traps.
   The results: On an open deck at an air temperature of 3 to 12 °C and overexposure of less than 3 hours, the mortality of crabs was extremely low, amounting to a maximum of 2.5 % of the number of individuals in the experiment. Over the next 3–5 hours, up to 40 % of crabs could die, and if overexposed for more than 5 hours, up to 59 %. The average proportion of dead crabs during overexposure of 3–5 hours was 5.4 ± 0.3 %, more than 5 hours — 23.4 ± 1.2 % and increased with increasing air temperature: under conditions above 10 °C 100 % survival were never seen. The average delayed mortality in the simulation of release of crabs into the sea was 11 percent.
   The practical significance: The results could be used for improving of fishery rules on the North fishery basign and red king crabs stock assessement. The article is not intended to calculate possible damage based on the results of control activities.

   The aim of the research is a retrospective analysis of the stock of the blue king crab Paralithodes platypus inhabiting the western part of the Bering Sea, to show the prospects of using the relative abundance index (I%N) as an assessment characterizing the state of the stock of this species.
   Material and methods. It is based on the data of direct accounting of P. platypus during trawl and trap surveys in 2005–2021. For each year, an index of relative abundance was established, expressed as a percentage of the maximum number of crabs noted in the retrospective period. The I%N index was determined for different functional groups of the crab separately and for combined size and age groups.
   New data. The use of the relative abundance index I%N in quartiles makes it possible to apply a four-zonal evaluation characteristic of the stock status of P. platypus: the stock condition is good, satisfactory, uncertain and depressive. This indicative method displays the dynamics of the state of the stock in the studied period and visualizes its variability in the historical period. In the West Bering Sea population of P. platypus, there has recently been a decrease in the number, which is less than 40 % of the maximum number observed during the study period. In all functional groups of P. platypus, the estimate of abundance (stock) is currently characterized as uncertain.
   Practical significance. The retrospective dynamics of the relative abundance index I%N is an additional operational indicator in making a management decision when developing P. platypus as a commercial reserve unit in the western part of the Bering Sea.

   The aim was to work out an algorithm for the analytical estimation of the commercial crabs aggregations area.
   Materials were ship daily reports (SDR) from the fisheries of shelf and deep-sea crabs in 2013–2021.
   As results, an original algorithm which allows calculating the surveyed area (of the crab commercial aggregations) as the sum of account squares is suggested. For each stock, the account square is characterized both by a certain side size and the minimum number of SDR, which allow us to consider it to be explored. Based on the data on the annual increase of the surveyed area, methodology for estimating the annual increase of the real area has been suggested. It takes into account both the annual variations of the fishing effort and outliers which may occur due to small number of samples. For different stocks, the minimum number of SDR, which allow to consider an account square to be explored, varied from 5 to 11 with a modal value of 7, the side size of the square varied presumably from 0.09 to 0.18 ° N, the relative annual increase of the real area varied from 0,82 to 1,23 with a modal value of 1.
   Conclusion: New indicator for the commercial stock dynamics estimation is suggested.

   The aim: synthesis of original and literary data on the species composition of fish-like vertebrates and fresh-water fishes of the Continental coast of the Sea of Okhotsk.
   Applied methods: routine methods of salmonids investigations were applied to prepare this article.
   Scientific novelty: the most complete annotated list fish-like vertebrates and freshwater fishes of the Continental coast of the Sea of Okhotsk is presented in the article. Distribution of ichthyofauna is described.
   Result: actual taxonomic list of fish-like vertebrates and fishes which reproduce in the water bodies of the Continental coast of the Sea of Okhotsk is presented. It includes 63 species from 30 genera, 18 families, 9 orders, 2 classes and 2 superclasses.
   Practical relevance: information presented in the article would be necessary for the purposes of organizing and conducting research work, organizing and regulating of fisheries and substantiating conservation measures for ichthyofauna of the Continental coast of the Sea of Okhotsk biological diversity, particularly under conditions of climatic shift.

   The aim of the work is to present the first data on the size and age characteristics of juveniles and adults of sockeye salmon in the lake Sopochnoye in comparison with the data characterizing the juveniles and adults of sockeye salmon in the lake Krasivoye.
   The material of the study was the collection of juveniles and adults of sockeye salmon from lakes Sopochnoye and Krasivoye, obtained in the course of various studies in the period from 1995 to 2020.
   Methods used: comparative data analysis, descriptive statistics methods.
   Results. It was established that most of the juvenile sockeye salmon from both lakes migrated to the sea at the age of 1+, and most of the adults belonged to two age groups — 1.2+ and 1.3+. The share of fish of these groups was 80.0 % in the lake Krasivoye and 89.7 % — in the lake Sopochnoe. Three more age groups — 1.4+, 2.2+ and 2.3+ were represented symbolically. At the same time, in the population of lake Krasivoye 85.0 % of all individuals, both males and females, spent only two years at sea. The proportion of such fish in the lake Sopochnoe was also significant — 35.9 %, but most of the producers spent a year longer at sea. The mass of females and males in the first of the lakes averaged 2.01 and 2.18 kg, and in the second 1.76 and 2.11, respectively.
   Practical significance. Since almost all sockeye salmon from the lake Krasivoye and Sopochnoye migrates to the coast at the age of 1+, and with rare exceptions (both females and males) spends only 2–3 years in the sea, it can be characterized as relatively early maturing. This fact significantly increases the attractiveness of Iturup Island sockeye salmon as a potential object for artificial reproduction.

   Purpose of the work: to assess the condition and structure of the pollock stock in the period 2011–2020 based on the materials of scientific surveys carried out in the main areas of its reproduction in the northern part of
the Sea of Okhotsk.
   Methods used: data on the biology and fishing of pollock were obtained during scientific trawling surveys in the northern part of the Sea of Okhotsk in the spring period 2011–2020. The areal method was used to calculate the abundance and biomass. Recalculation of the size composition of pollock in the age is carried out using the size-age key.
   Novelty: the elements of novelty are the analysis of the structure and dynamics of the pollock stock according to trawl surveys, as well as its fishing in the northern part of the Sea of Okhotsk over a ten-year period. The yield level of pollock generations at the age of one year and the age of near replenishment of the spawning stock, which appeared during the 2010s, was determined.
   Result: despite the heterogeneity of the size and age structure of pollock in the considered fishing subzones of the Sea of Okhotsk, the presence of high-yielding generations is usually manifested for the entire northern part of the Sea of Okhotsk. The most significant fluctuations in pollock stocks were observed in the first half of the decade under review. During the 2010s, the trends in pollock catch in the North Okhotsk subzone and Kamchatka subzones coincided. The efficiency of pollock use in the northern part of the Sea of Okhotsk is characterized by maximum values.
   Practical significance: the results obtained on the dynamics and structure of the pollock stock in the North Okhotsk and two Kamchatka fishing subzones of the Sea of Okhotsk over a ten-year period will be used for prognostic purposes.

   The aim of this research was to assess the scale and determine the possible reasons of the death of Caspian seals (Pusa caspica), that were washed up by a storm on the coast of the Republic of Dagestan in early December 2020. The corpses of seals were found on the Dagestan coast from the mouth of the Terek River to the southern outskirts of Derbent, in total about 205 km long.
   The main methods of collecting material were: accounting of dead seals in open (not overgrown with vegetation) coastal areas, measurements and pathoanatomic autopsies of corpses, sampling of internal organs and tissues of animals for histological, virological, helminthological and toxicological studies. Simultaneously with the onshore work, observations of seals and registration of hydro- meteorological parameters in the coastal waters of the Republic of Dagestan were carried out by two research vessels of the Caspian branch of the Federal Research Institute for Fishery and Oceanography («KaspNIRH»): «Caspian Explorer» and «Hydrobiologist».

   As a result, 12 coastal sites with a total length of 49.2 km were surveyed, where 313 corpses of dead seals were registered; the average density was 12.27 ± 2.16 specimens/km. The total number of dead seals in December 2020 was estimated at 2,515 ± 443 individuals. Adult females predominated among the dead animals, most of which were pregnant. The corpses showed no signs of infectious diseases or exhaustion. Judging by their condition, the death of animals occurred during the first two decades of November, at some distance from the shore.
   Conclusion: Basing on the data collected, infectious diseases, helminthiasis, intoxication, accident by catch in the fishing gears, and the impact of an underwater shock wave were excluded from the possible reasons of the death of seals. Acute asphyxia as a result of local release of natural gas, which could form above the sea surface a polluted lens of air unsuitable for breathing, was recognized as the most likely cause of the seals death.

   The aim of this article: assess the impact of abiotic conditions on aquatic biological resources (sprat, herring, cod) of the Baltic Sea. The need for this study is due to the pronounced climate variability in the modern period. There is an increased role of the impact of environmental conditions on commercial fish species and, often, unfavorable for their spawning, survival of offspring, feeding, etc.
   Methods used: carried out an integrated ecosystem analysis using the method of principal components in the R software environment. To detect statistically significant levels of changes in the time series of principal components, the STARS program, represented by an Excel add-in, was used. For the analysis of abiotic conditions, long-term series of air temperature, data from regular oceanological observations at a monitoring station were used. Since the stocks of commercial fish species in the Baltic Sea are transboundary, the values of their spawning biomass and biological parameters of populations were analyzed according to the data of
the ICES Working Groups.
   Novelty: this is the first time that such an analysis for a 30-year period adapted to the Russian water area in SD ICES 26 has been carried out.
   Result: an integrated analysis of the abiotic and biotic components of the sea over the past three decades showed «mesoscale» shifts in 2002 and 2013. The direct and indirect impact of climate on the fish stocks of the Baltic Sea was an important unfavorable factor determining the current state, size and weight parameters, reproductive capacity and stocks dynamics. The most pronounced negative impact of environmental factors was noted for the stock of cod.
   Practical significance: the results of the analysis carried out are necessary when predicting the catch of aquatic biological resources in the Baltic Sea for the short and long term, for making management decisions on the regulation of fishing in terms of understanding the risks in the current conditions of climate change.

   The aim of the work is to investigate the effect of compound feeds with different levels of protein on the growth of juveniles of the Australian red claw crayfish Cherax quadricarinatus.
   Used methods: To solve this problem, two experiments were carried out in the aquariums of aquaculture invertebrate department at VNIRO: the first was on juveniles weighing 0.017 ± 0.004 g and 0.87 ± 0.08 mm long; the second one was on juveniles weighing 0.31 ± 0.14 g and 23.7 ± 3.9 mm long. The duration of the experiments was 30 and 40 days, respectively. Feeding of juveniles was carried out with three variants of compound feed recipes with an estimated protein content of 25 %, 35 % and 45 %. The main part of the formulations consisted of components of plant origin. Tetra Wafer Mix food for fish and crustaceans (Germany) with a protein content of 45 % was used as a control. The duration of the experiments was 30 and 40 days, respectively. Feeding of juveniles was carried out with three variants of compound feed recipes with an estimated protein content of 25 %, 35 % and 45 %. The main part of the formulations consisted of components of plant origin. Tetra Wafer Mix food for fish and crustaceans (Germany) with a protein content of 45 % was used as a control.
   Newness: Development of a feed formulation for rearing juveniles of the Australian red claw crayfish in recirculating aquaculture systems (RAS).
   Results: These experiments showed that the growth rate of juvenile Australian red claw crayfish is directly dependent on the proportion of protein in the feed. It was established that the relative content of protein in the muscles of crayfish depends on its content in compound feed. An analysis of our own and published data indicates that feeds with protein content below 35 % cannot be recommended for growing of juveniles’ Australian red claw crayfish. Feeds with a protein content of 45 % are optimal for the growth of juveniles. It was established that the effectiveness of compound feeds depends not only on the protein content and energy value, but also on their taste attractiveness.
   Practical significance: The obtained results will be used in the development of mixed feed for juveniles Australian red claw crayfish.

   The aim of the work was to study the effect of compound feeds with full or partial replacement of fish oil with vegetable oils on the composition of tissues and growth perfomance of rainbow trout.
   Method of chemical analyses was used for the estimation of nutritional value of the feed. To determine the fatty acid composition of the total lipids of feed and muscle tissue of trout, methyl esters of fatty acids were analyzed on a Crystal 5000.2 chromatograph. To assess the effect of compound feeds on fish, a number of fish-breeding and biological indicators were determined.

   The novelty of the study is associated with modeling the optimal ratio of fish oil, rapeseed and soybean oils in fish diets.
   As a result of the research, it was found that the highest growth rates and survival at lower feed costs were found in fish grown on diet without replacing fish oil and diet with a mixture of fish oil, rapeseed and soybean oils in a ratio of 4:6:5. Replacing fish oil with vegetable oils in feed recipes did not adversely affect the chemical composition of fish muscle tissue. Due to the elongation and desaturation processes occurring in the tissues of rainbow trout, the inclusion of rapeseed and soybean oils in the compound feed did not lead to a decrease in the amount of eicosapentaenoic and docosahexaenoic fatty acids.
   The practical significance of the work lies in obtaining new diets for compound feeds for valuable fish species, providing opportunities for effective cultivation of rainbow trout with specified quality characteristics.

   The aim: to determine the areas in the Barents Sea where the most significant changes in water temperature in the bottom layer occured over the last 15 years.
   Methods used: analysis of time series of water temperature in the bottom layer to identify trends in their structure, at grid nodes with steps of 10’ in latitude and 30’ in longitude; calculation of correlations with hydrometeorological parameters.
   Novelty: аreas with significant trends in water temperature in the bottom layer of the Barents Sea were identified on the basis of observations for 2004–2019, and trend coefficients were calculated.
   Result: for the investigated period, there were no significant changes in water temperature in the bottom layer in the central and southern parts of the Barents Sea. The area of positive trends was found off the western coast of the Novaya Zemlya Archipelago, with an increase in temperature by 0.1–0.2 °C per year. In the northern part of the sea, the area of decreasing trends in water temperature (by 0.1–0.2 °C per year) was identified.
   Practical significance: trend coefficients make it possible to estimate rates of changes in water temperature in the bottom layer, analyze features of year-to-year variability of water temperature, and consider the possible impact on ecosystem components.

   The purpose of this study is update the norms for the output of walleye pollock processing products for the Far Eastern fishery basin based on a statistical assessment of the results of experimental control works aimed at improving the fishing regulation system in terms of verifying actual catches.
   Methods used: experimental and control work was carried out according to the «Methods for determining the consumption rates of raw materials in the production of products from hydrobionts». 145 experimental and control works were carried out, the mass of raw fish directed to their implementation was 21499.4 kg. Calculations of the results of experimental and control work using the «Complex of programs for processing the results of experimental control works in the production of frozen products from raw fish (except for sturgeon and salmon)».
   Novelty: it has been established that the use of modernized fish cutting equipment or new generation machines can increase the yield of headless walleye pollock by 3,8 %, and output skinless and boneless walleye pollock fillets in season «B» increased by 2,9 %. For the first time, the output of skinless, boneless fillets from walleye pollock in season «A» was established, which amounted to 26,9 %.

   Result: this article is a continuation of the great work carried out by the Federal State Budgetary Scientific Institution «VNIRO» to update the rates of output from walleye pollock. In the first message, the rates of output from the Sea of Okhotsk pollock were considered, in the second message the data on the output of production from the West Bering Sea, East Kamchatka, North and South Kuril zones.
   Practical significance: the developed rates for the yield of walleye pollock processed products in 2020 included in new collection of «Basin rates for waste, losses, finished product yield and raw material consumption in the production of frozen and fodder products from fish of the Far East region».

   The purpose of the work is to determine the level of provision of the domestic market with fish products in order to meet the requirements for increasing the average per capita consumption of fish products by the population of the Russian Federation.
   Materials and methods: official data published by the Federal State Statistics Service on the average per capita consumption of food products by the population, including fish products, were used in the work. The methods of logical and system analysis made it possible to identify promising sources of providing the domestic market of Russia with fish products.
   The results of the study are to determine the sources of the resource base to increase the volume of production from aquatic biological resources in the domestic market. Proposals were made on the possible further development of the fishery complex of the Russian Federation, including measures of state support and regulation of the domestic market.
   The practical significance lies in the possibility of using the results of the study in developing approaches to solving the task set by Rospotrebnadzor to increase the norms of per capita consumption of fish products by the population of the Russian Federation.

   The purpose of the work is to investigate changes in accounting and control related to digital technologies and the advantages of accounting and analytical information in the management of fisheries activities based on the principles of sustainable development.
   The methods used — dialectical, monographic, the method of scientific abstractions, comparison and empirical generalization allowed us to highlight the features of accounting and control of the fisheries complex in the digital environment.
   An element of novelty — digital technologies in accounting and control develop methodology and practical approaches to their organization in the direction of operational management of fisheries activities at all levels, allow management to make management decisions on compliance with the principles of sustainable development.
   Research results — the digital environment is changing approaches to the organization of accounting and control in the direction of transparency, accuracy, efficiency of information, without changing the content of accounting methodology. Integration of accounting and analytical information with other sources in the digital environment provides a management and decision-making system for the sustainable functioning of the production structures of the fisheries complex.
   Practical significance — compliance with the principles and high-quality performance of accounting and control functions in the digital environment expands the information space for making management decisions in the system of extraction, processing of aquatic biological resources, promotion of fish products to markets, while reducing the time and complexity of obtaining information, increasing efficiency and effectiveness.

   The purpose of these studies is to obtaining up-to-date information on the dynamics of spawning migration and the quality indicators of Pacific salmon on the Paramushir and Shumshu Islands (Northern Kuril Islands).
   Methods used: the work was carried out in accordance with the methods generally accepted in fisheries research.
   Scientific originality: for the first time in the last decade, data were collected on the dynamics of anadromous migration and on the biological parameters of the Pacific salmon of the Northern Kuriles.
   Result: up-to-date information on the timing of spawning migration and quality indicators of pacific salmon of the Northern Kuril Islands in 2021 is presented. Information about the temporal structure of the spawning stream has been obtained.
   Practical significance: the results will be used in the preparation of materials substantiating the forecasted volumes of pacific salmon catches in subsequent years, as well as in regulating the fishing of pacific salmon in the Northern Kuril Islands.