The aim: analysis of ichthyoplankton and characteristics of eggs and larvae of migrating subtropical species.
Methods: Ichthyoplankton samples, processed using generally accepted methods in the Russian Federation.
Innovations: data on chub mackerel spawning in the southeastern part of the of Tatar Strait has been obtained for the first time after more than 70 years absence. Pacific sardine spawning has been recorded in study area for the first time.
Results: from May to the first half of July, ichthyoplankton was composed by typical species for study area, mainly by Pleuronectidae. In the third decade of July, resident species were replaced by species of subtropical complex – chub mackerel and Pacific sardine. Their spawning became possible as a result of increase in population abundance and formation of optimal temperature conditions at the northern boundary of areal. Mackerel eggs and larvae were predominant. Based on catches by different nets, the average density of mackerel eggs was 16.9-20.6 ind./m², density of mackerel larvae was 1.3-1.9 ind./m². The sizes of mackerel eggs and larvae in 2025 were smaller than in the 1940s, which may be due to the maternal effect. The proportion of non-viable eggs was 27%. Sardine was presented only by eggs with average density of 2.5-3.1 ind./m². The proportion of embryonic pathologies was 8%.
Practical significance: eggs and larvae of subtropical fishes are indicators of the Tatar Strait warming and current ecosystem changes in summer ichthyofauna of this area. Information about extension of reproductive area can be taken into account in forecast assessments, recommendations for fishery as well as in the planning of specialized scientific projects in early ontogeny of migrants.

The aim: to characterize sea current influence on the direction of the Azov anchovy overwintering migration into the Black Sea.
Material and methods: the assessment was based on long-term Azov anchovy catch statistics from ship and coastal fisheries and data of currents in the Kerch pre-strait area in 2015-2024 based on the Copernicus monitoring project dataset. The hypothesis of a relationship between spatio-temporal changes in sea currents and the direction of the Azov anchovy migration was tested using nonparametric statistics (Mann-WhitneyWilcoxon test) and spatial analysis.
Results: the relationship between the eastern and northern currents, that related with the direction of the Azov anchovy migration in the Kerch Strait area, was shown. Spatial patterns in the eastern and northern components of the currents that determine the migration direction have been identified. The key factors in determining the migration direction are: 43rd, 45th and 46th weeks of the year for the eastern component of the currents, 46th week for the northern component of the currents.
Novelty: using statistical spatio-temporal analysis of long-term data the relationship between currents and Azov anchovy overwintering migration was showed.
Practical significance: long-term spatial patterns of sea currents and their influence on the direction of the Azov anchovy migration into the Black Sea can make it possible to increase the efficiency of organizating Russian fisheries.

The aim of the research is to develop the methodology for assessment the Baikal seal based on direct counting of animals on ice using unmanned aerial systems (UAS).
Materials were the data of aerial survey obtained in 2019 and 2021 and the manuscript published in the open press “Methodological recommendations for conducting a census of the Baikal seal (Pusa sibirica) offspring using unmanned aerial vehicles in the Baikal fishery basin.
Novelty – the method for assessment the Baikal seals based on direct counting of animals on ice using several UAS simultaneously is proposed. Processing of an array of high-resolution digital photographs was automated through the use of software packages that use computer vision based on neural network technologies of artificial intelligence (AI) to recognize various types of images, including marine mammals.
Result: The methodology for assessment the Baikal seals based on direct counting of animals on ice using UAS has been developed and tested, including calculations of the species’ numbers using the separate extrapolation method. The methodology was tested using materials from aerial surveys in 2019 and 2021 – as a result, estimates of the number of Baikal seals on ice were obtained: 106,486 specimens and 107,723 specimens, respectively.
Practical significance: the proposed method of direct census of animals on ice has been developed with the aim of increasing the accuracy and reliability of final estimates of the population size and developing recommendations for its conservation and rational use.

The aim: The approbation of underwater imaging for G. lacustris counting in the under ice layer of fishery water body at the Beloe Lake as an example.
Methods: The method of underwater imaging was used to account G. lacustris inhabiting the bottom side of the ice cover and caught there into the frames of the counting zone which was determined on diameter of the hole from the manual fishing ice-drill. The biomass of G. lacustris in the biotope was calculated by multiplication of average number of individuals per unit area, determined from video recordings, by the average mass of one individual. Individuals for biomass determination were taken from the counting holes by the first release of individuals onto the ice during drilling of the hole.
Novelty: The method of G. lacustris counting based on underwater imaging is novel.
Results: Data on population density and biomass of G. lacustris in the Beloe Lake in April 2025 were obtained. It was established that the density of G. lacustris in the under-ice layer varied from 0 to 1960 ind. m^‑2 (on average – 314±110.7 ind. m^‑2). With an average weight of one individual of 0.047 g, the biomass of G. lacustris per unit area is 14.8 g m^‑2, and in the under ice layer of the shallow zone of the lake is 5.9 tons. Taken into account the lower limit of standard error of density the biomass is 3.8 tons.
Practical significance: The proposed method can be implemented in the practice of determining the stocks of G. lacustris in commercial (fishery) water bodies, as well as for the purpose of monitoring the population of this species in water bodies with different characteristics.

The aim of the work: to consider the history of intensive fishing and its impact on the state of red bed-forming algae stocks in order to develop an optimal regime for modern fishing of Ahnfeltia in Izmena Bay.
Methods used: the analysis was based on literature sources and information obtained in 1989-2021 according to the recommended methods of fishery research.
Novelty: analyzed data on the impact of fishing on the resources of red bed-forming algae, revealed the relationship between extraction from the «live» bed and degradation of fields, developed recommendations for the exploitation of the Ahnfeltia bed in Izmena Bay, Kunashir Island.
Result: The experience of exploitation of red bed-forming algae cenopopulations in the USSR has clearly demonstrated that exploitation of a «living» bed inevitably leads to subsequent degradation of reserves and destruction of its (bed) structure. In spite of the fact that each field shows different resistance to impact, it is more reasonable to base fishing on regularly formed pre-discharge accumulations. The volume of pre-release accumulations for all bed-forming algae is significant. In order to preserve the commercial importance of the Ahnfeltia field in Izmena Bay, it is proposed to prohibit fishing for Ahnfeltia in the center of the main bed. At the same time, the pre-discharge accumulations formed in the coastal zone at depths up to 2 m can be removed completely.
Practical significance: developed recommendations for the rational use of resources of the commercial algae Ahnfeltia fastigiata var. tobuchiensis in the Sakhalin Region.

The purpose of the work: to describe the variability of cod fishes stocks and catches in the Far Eastern seas and the Pacific waters of Kamchatka and the Kuril Islands and to assess the prospects for their fishery.
Methods used: to achieve this goal, data on the biomass and catches of walleye pollock, Pacific cod and saffron cod for the period from 1935 to 2025 were analyzed. Calculations were made for fish in general, for individual habitats and local stocks.
Novelty: the novelty elements include generalized materials on the reserves and catch of cod fishes resources in the Far East for the entire period of their study and fishery. In total, information on 30 groups of walleye pollock, Pacific cod and saffron cod living in the study area was considered, the dynamics of their biomass and catches were shown. Trends and cyclicality of stocks and catches of fish of individual stocks were revealed. The periodicity of the formation of cod fishes stocks made it possible to present forecast estimates of the expectation of high estimates of their abundance for the period 2026-2038. Geographical localization in the sequence of formation of biomass maxima of individual fish populations was also revealed, the clarification of the reasons for which will serve as the basis for further research.
Practical significance: the information obtained can become the basis for a long-term action plan for the effective use of cod fishes stocks, which are fundamental for Russian fishery.

The aim of the work is to determine the origin and potential routes of spread of infectious hematopoietic necrosis virus (IHNV) of trout in fish farms of the Russia based on an assessment of the genetic diversity and molecular epidemiological relationships of isolates.
Methods used: Standard virological methods for isolating fish viruses on cell lines were used. Identification was performed using RT-PCR, and sequencing was performed by Sanger. Comparative analysis and a search for closely related IHNV nucleotide sequences were performed using the GenBank database. A phylogenetic tree was constructed using neighbor-joining methods.
The study revealed that most Russian IHNV isolates from rainbow trout clustered within the European E group, with a few falling into the U group. Analysis of the obtained data revealed that the virus was imported to Russia at least twice: first from the United States, likely in the 1990s, and then from Europe in 2014-2017, most likely from Italy. It is hypothesized that the subsequent spread of the pathogen in Russian fish farms occurred through transfer via water, birds, and animals, as well as through the movement of infected planting material within Russia. The adaptation pathway of the virus, originally enzootic for US sockeye salmon and belonging to the U genogroup, to rainbow trout and its subsequent transformation into the E genogroup in Europe is demonstrated.
Practical significance: The results are important for improving IHNV surveillance, diagnosis, and control systems in Russian fish farms, as well as for developing measures to contain the further spread of the virus.

The aim is to assess the impact of using RBS Russian sturgeon on the level of genetic polymorphism in the released juveniles and on the dynamics of the allele composition of the population in the Sea of Azov.
Methods: Polymorphism analysis was carried out at five microsatellite (STR) loci (Afug41, An20, AoxD161, AoxD165, Afug51) on two samples of Russian sturgeon: I. individuals captured in the Sea of Azov in 1999-2003 (250 samples, offspring of «wild» broodstock) and II. individuals captured in 2020-2024 (250 samples, offspring of broodstock from established RBS).
Novelty: For the first time, comparative genetic analysis results are presented for archival (1999-2003) and contemporary (2020-2024) Russian sturgeon samples, along with an assessment of the temporal stability of the population’s genetic structure.
Results: Comparison of microsatellite data between the two samples (offspring of natural and artificially reproduced broodstock) showed that the mean number of alleles per locus did not change significantly over the 25‑year period. However, in the sample of offspring from artificial reproduction, the mean number of alleles per individual decreased slightly (by 2.41%), and the proportion of homozygotes was higher compared to the wild-origin offspring (0.07 vs. 0.05, respectively). These results indicate that allele diversity in the Azov population of Russian sturgeon remains at a stable level, although a slight increase in the inbreeding coefficient was observed.
Practical significance: The findings demonstrate the high efficiency of artificial reproduction in maintaining the natural genetic diversity of Russian sturgeon and can be applied in genetic monitoring at sturgeon hatcheries to ensure the long-term maintenance of offspring genetic heterogeneity.

The aim of the work is to study mercury pollution of components of aquatic ecosystems of the Lower Don, since mercury is a widespread pollutant in water bodies with high toxicity for living organisms and the ability to bioaccumulate.
Materials and methods. The results of studies of mercury content in water, bottom sediments and aquatic organisms in the lower reaches of the Don River, collected at 10-25 stations during the period 1995-2024 in the spring, summer and autumn seasons, are presented. Mercury was determined using the cold vapor atomic absorption method.
Results: in 1995-2005, the mercury concentration in the water of the Lower Don was high on average, then for 15 years its content was at a low level, and from 2020 to 2024, cases of high mercury concentrations began to be recorded again, with maximums in the area of the Romanovskaya station (up to 62 MPC) and the city of Semikarakorsk (up to 140 MPC). In 2022, in the spring-summer period of the year in the area of st. Romanovskaya, mercury accumulation was detected not only in the water, but also in bottom sediments. In the modern period, a higher mercury content has been noted in the muscles of predatory fish species without exceeding the permissible level.
The novelty: for the first time, data on mercury content in water and bottom sediments of the Lower Don over 30 years of observations and aquatic bioresources in the modern period (2020-2024) were summarized and analyzed.
Practical significance: the obtained results were used to establish safety criteria for the waters of the Lower Don and commercial fish in accordance with the standard of maximum permissible mercury concentration for fishery waters adopted in Russia and the requirements of the Technical Regulations of the Customs Union.

The aim of the work is analysis of the influence of the hydrological regime of the floodplain-river system of the Middle Ob and the ambient temperature in the spring on the dynamics of catches of commercial fish species with different reproductive ecologies.
Methods used: the research methodology is based on data on catches of aquatic biological resources and on the construction and analysis of graphs of interannual variability of hydro-logical and temperature parameters for 1947-2020.
Novelty: for the first time in the Middle Ob region, an analysis of the combined impact of the hydro-logical regime and environmental temperature in the spring period on the state of commercial fish stocks has been conducted.
Results: for effective natural reproduction of native phytophilic fish species (ide and roach) of the Middle Ob, conditions of timely flooding of the floodplain and optimal temperature conditions in May, as well as higher and prolonged flooding of the floodplain in June are necessary. The spawning efficiency of bream is less dependent on hydro-logical indicators and more on temperature indicators in May.
Practical significance: the obtained results make it possible to increase the accuracy of long-term forecasting of stock status and develop a strategy to reduce the risk of overexploitation when adjusting the recommended catch of aquatic biological resources of the Middle Ob.

The purpose of the work: to calculate and determine the level of Arctic security of the regions of the Arctic Zone of the Russian Federation (Arkhangelsk and Murmansk regions, the Republic of Karelia) using the sectoral aggregate criterion of economic security. Based on the results obtained, develop and propose industry-specific tools for ensuring Arctic security.
Materials and methods: the method of econometric analysis and forecasting was applied using a statistical assessment of socio-economic indicators of the Arkhangelsk and Murmansk regions, the Republic of Karelia according to economic security criteria.
Results: in the analyzed period, the Murmansk region showed a high level of Arctic security according to industry criteria, while the Arkhangelsk region and the Republic of Karelia received negative values of the indicator, which means instability to industry risks and threats. This is due to a decrease in the production indicators of sectoral economic entities and the lack of innovation.
Novelty: a forecast assessment of the likelihood of an unfavorable scenario for the implementation of threats to the Arctic security of the Russian Federation was obtained. Recommendations have been developed to prevent and minimize the consequences of risks for the three Arctic regions.
Practical significance: the dynamics of changes in strategic indicators of Arctic security is the basis for making management decisions by regional authorities and the business community; can be used for predictive justification of production, financial and innovative transformations of the industry.

The purpose: to assess the impact of various digitalization factors on the financial and production performance of fisheries and aquaculture organizations, to establish links between the key digitalization parameters and performance indicators.
Methods used: the information base of the study consisted of statistical materials and reports of enterprises on the use of digital technologies. The main methods of the study were the calculations of financial and production performance indicators of fisheries and aquaculture for all fishery basins, taking into account the dynamics of the organizational structure and the average annual number of employees. The nature and degree of dependence of digitalization factors and performance was identified by constructing a correlation matrix based on the two-sided Pearson correlation. The nature of the impact of individual digital technologies on performance factors was established based on the calculation of the impact index.
Novelty: a dynamic analysis of the financial and production performance of fisheries and aquaculture was carried out according to the basin principle. The interdependence of the essential parameters of digitalization and performance of fishery organizations was established.
Result: a dynamic, comparative and correlation assessment of the impact of digitalization on the production and financial performance of fisheries and aquaculture organizations in fishery basins was carried out. The impact of digital technologies on various parameters of the efficiency of fisheries and aquaculture organizations was determined.
Practical significance: the results can be used to form and adjust the digital transformation strategy at the micro and meso levels of the fisheries economy. The methodology is applicable to assessing and developing projects to increase the level of digital maturity of fisheries and aquaculture enterprises.

The purpose of the work is improving methodological approaches to the diagnosis of the regional fisheries complex (hereinafter referred to as RHC), which allows taking into account a variety of criteria, including aspects of sustainable development, food security conditions, etc.
Methods used: general scientific research methods, statistical, expert methods, systematic and situational approaches, indicative method. An element of novelty: the necessity of using a multidimensional model in the diagnosis of regional RHC is substantiated, the visualization of which in the form of a hexagon allows us to build a diagnostic algorithm and form a list of indicators in accordance with the criteria selected for analysis. The study of regional RHC using a multidimensional model expands the diagnostic directions through the prism of the criteria laid down, allows us to identify cases of “superposition” of individual planes on top of each other, which makes it possible to detail the list of indicators used to the extent that it presupposes the determination of cause-and-effect relationships in the identified deviations from the normative values.
Research results: within the framework of the proposed multidimensional diagnostic model, criteria are presented, according to which a list of recommended indicators is formed as an analysis tool, the sequence of individual diagnostic stages is determined, their interrelation and features are described. It shows the details of two of the six diagnostic stages in accordance with the multidimensional model, which pay attention to industry-wide characteristics, the features that determine the composition of the indicators included in the group specific to the regional RHC.
Practical significance: the results contribute to the improvement of the algorithm for diagnosing regional RHC, refine the tools for assessing the state of its individual components, which can be used by authorities for the sustainable development.

The aim: assessment of stocks and prospects of fishing for aquatic biological resources in the Sea of Okhotsk.
Methods: data collection was carried out in accordance with generally accepted methods in ichthyological practice.
Innovations: up-to-date data on the composition, ratio, abundance, and biomass of nekton in the Sea of Okhotsk in the spring of 2025 have been obtained.
Results: an assessment of the reserves of aquatic organisms in the Sea of Okhotsk was carried out, which totaled 34,0 billion specimens and 10,2 million tons. Data on the distribution and biological status of nekton in three areas of the Sea of Okhotsk were obtained: Western Kamchatka, Shelikhov Bay (West Kamchatka and Kamchatka-Kuril subzones) and the northern part of the Sea of Okhotsk (North Okhotomor subzone). An analysis of the spatial distribution of pollock in various areas of the Sea of Okhotsk showed the highest density of its accumulations in Western Kamchatka and in the hall. Shelikhov. At the same time, dense accumulations of herring are noted above the slopes of the deep-sea trough in the hall. Shelikhov and above the shelf part of the North Okhotsk region. Capelin accumulations were mostly localized in the hall. Shelikhov and northwestern Kamchatka. The general distribution of sakhalin flounder was confined to the offshore waters off Western Kamchatka and in the North Okhotsk region.
The practical significance: the results of the study will serve as the basis for developing materials for forecasting the total number of species of aquatic biological resources in the Sea of Okhotsk.

The purpose. Assessment of the current state of the High Arctic Ichthyocene of the sublittoral zone of the Dezhnev Bay on Alexandra Land Island of the Franz Josef Land Archipelago in the ice–free period of 2025.
The methods used. The collection of ichthyological material was carried out by passive net fishing gear on a grid of stations. The catch structure was evaluated using mathematical statistics methods.
Result. For the first time during the period of ichthyological research, information is provided on the catches structure in the sublittoral zone of the islands of the Franz Josef Land archipelago is provided.
Practical significance. An assessment of the population status of fish species in the northeastern part of the Barents Sea will make it possible to understand and the degree of adaptation to to living on the sublittoral in the high-latitude Arctic.