In 2007, the European Commission initiated the Eel Recovery Plan (Council Regulation No. 1100/2007) to try to bring the European eel stocks back to more sustainable adult levels and the return of the glass eel. Each EU Member State is required to develop a national eel management plan. These plans aim to achieve a return of silver eels to the spawning population equal to or greater than 40 % of the potential biomass that could be obtained in the absence of anthropogenic disturbances related to fishing, water quality or barriers to migration. The advantage of this approach is that it offers a standard basis and allows for the integration of stock status data between EU and non-EU countries. The purpose of this Plan was to determine for the Vistula Lagoon within the territory of the Kaliningrad region of the Russian Federation: 1. Management objectives based on an assessment of the potential stock of the silver eel in the absence of anthropogenic mortality and high (before 1980) recruitment levels. 2. The current level of the stock of silver eel in relation to the planned indicator (ie assessment of compliance with the planned indicator). 3. Control actions necessary to achieve or maintain this compliance. 4. A set of data needed to support the steps 1-3 above and to demonstrate whether compliance will be achieved in the future, i.e. that the actions defined in the management plan will lead to the recovery of the eel population.

   The article presents the results of experimental studies to assess the impact of heavy metals on the functioning of phyto- and zooplankton (Scenedesmus quadricaud, Daphnia magna). Determination of inactive and threshold concentration of strontium, toxicity parameters and the degree of acute toxicity has been carried out. As a result of the studies the data on the effect of strontium on hydrobionts of different trophic links were obtained. For zooplankton in terms of survival rate the maximum allowable concentration of strontium was 4 mg/l, in terms of fecundity - 2 mg/l in terms of fecundity. According to the indicator of single-celled algae Sc. quadricauda viability (cell number) in the chronic experiment the maximum allowable concentration of strontium is 2 mg/l.

   The paper considers a nonlinear phenomenon borrowed from the works of one of the world founders of the theory of catastrophes, Academician V.I. Arnold, which relates to the economic aspects of the fleet, where the features of transformations during the restructuring of the economic formation in Russia are thoroughly described. The correspondence of the one-product model of the restructuring of the economic formation in Russia is shown, which is not only a special case of the scientific, technical and socio –political world progress occurring in the form of waves of Kuznets and Kondratiev, but also the general cultural evolution of Mankind, as well as Russia's modern policy of restructuring its economy for import substitution and logistics chains, catastrophe multiple folds extending beyond 7 elemental catastrophes.

   The current political and legal challenges of fisheries management at the present stage, taking into account the Sustainable Development Goals adopted by the UN in 2015 are considered in the article. Steps to improve the international legal management of fisheries, taken as part of the implementation of the goals set in Goal 14 " Conserve and sustainably use the oceans, seas and marine resources for sustainable development", were noted. Also considered are other political and legal problems of fisheries, which were identified within the framework of international organizations, closely related to the concept of sustainable development.

   The history of the study and fishing of the golden king crab, which lives in the northern part of the Sea of Okhotsk, is considered. Based on the materials collected in 2000-2020, the course of fishing and catching of this object is analyzed. It is shown that the prospects for the industrial development of this valuable object in the coming years do not cause concerns, although some reduction in the reserve is possible.

   Based on long-term materials, the ecology, the current state of the reserve and some features of the biology of the Black Sea-Caspian Sea sprat in the Cheboksary reservoir are considered. A brief biological characteristic of its age and size-weight indicators is given. The prospects of industrial development are shown.

   To understand the mechanisms of formation of water quality in an aquatic ecosystem, the processes of formation of funds of dissolved organic matter (DOM) and detritus are essential. When the algae die off, the bulk of their contents enter the aquatic environment within one week. Detritus settles at a rate of about one meter per day. In deep water bodies, the destruction of detritus occurs to a significant extent in the water column; in shallow water bodies, it occurs mainly at the bottom. DOM is consumed by bacteria and algae. This article presents the results of an experimental study of the quantitative aspects of DOM transformation and metabolism using natural water samples immediately after they were taken from a mesotrophic freshwater ecosystem. The total heterotrophic activity of various fractions of plankton in natural water was determined. The specific heterotrophic activity (per a unit of biomass) was also determined. It was found that the specific heterotrophic activity of bacteria (per a unit of biomass) in all cases is higher than the activity of phytoplankton. The new results provide a detailed understanding of chemical-biotic interactions in aquatic ecosystems, which is important for the analysis of water self-purification processes.

   The hybrid of sturgeon "lenbel" (F₁ ♀ Acipenser baerii × ♂ Huso huso) was studied by conventional methods for a complex of plastic and meristic signs. It was found that only the horizontal diameter of the eye (O), the greatest height of the head (HC), the distance from the end of the rostrum to the base of the middle antennae (rc) and to the cartilaginous arch of the mouth (rr), the width of the snout at the cartilaginous arch of the mouth (SRr), the width of the mouth (SO) and the width of the break of the lower lip (il) for hybrid and beluga, and the width of the lower lip break (il) and the width of the snout at the base of the middle antennae (SRc) for hybrid and Siberian sturgeon have a transgression index of less than 67 %, and can be used to identify the hybrid form. The beluga fingerlings were largely consolidated, and therefore united into a single cluster. Siberian sturgeon and hybrid also form two clearly differentiated clusters, but the intra-group divergence of the hybrid is slightly higher than that of the original forms. In hybrid fingerlings, relative plastic and meristic signs are not related to body size and remain constant during the growing period, that is, they may be specific to it. It is shown that some head measurements can be used for confident identification of the hybrid.

   Bioflavonoids, also known as flavonoids, are substances with low molecular weight that are found in vascular plants. They are found in all parts of plants, but especially in photosynthetic cells and have a wide spectrum of action as antioxidants, enzymatic inhibitors, precursors of toxic substances, protection against ultraviolet radiation, and also participate in energy conversion. The article discusses the experience of using a new generation antioxidant – dihydroquercetin and an immunostimulator – arabinogalactan in feeding sturgeon fish.

   The objects of research in the work were: two-year-olds of Russian sturgeon, as well as dihydroquercetin, arabinogalactan and feed formulations for sturgeon fish species.

   In the process of work, the formulation of a full-fledged compound feed for sturgeon fish species was adjusted using the bioflavonoid dihydroquercin, an arabinogalactant immunostimulator, and the productive effect of feed on fish was evaluated according to fish-biological and physiological indicators. The obtained results complement the existing ideas about the fields of application of antioxidants, and also prove the prospects of using herbal remedies as antioxidant feed additives. The results obtained in the course of research can serve as a basis for improving technologies for the production of compound feeds when growing fish on an intensive basis.

   The technology being developed for the production of a feed mixture based on the biomass of a cultivated worm is aimed at improving factory feeds by adding an additional volume of protein, thereby increasing the nutritional value of the feed, eliminating the need to buy a specific feed of greater nutritional value, providing the opportunity to supplement feeds less saturated with protein components. Also, the technology being developed is aimed at partial or complete replacement of currently known protein feed components (such as soy meal, meat and bone meal and fish meal). In the course of the study, a trial production of a protein feed component was carried out, according to the methodologies described in the work, in order to test the proposed technology in practice.

   In this paper, the genotoxicity of (1-(4-chlorophenyl)-3-(2,6-difluoro-benzoyl) urea) is investigated by a micronuclear test on Danio rerio, as a standard test object, at concentrations of 0.5, 1 and 2 mg/l. As a result of the work, a significant increase in the frequency of occurrence of micronuclei (0.73 %) was found, while other nuclear anomalies in the maximum concentrations of erythrocytes were also significant. It was found that the frequency of micronuclei in concentrations of 0.5 and 1 mg/l on the fifth day of the experiment was the maximum, while at the maximum concentration (2 mg/l) the level of micronuclei was lower, which is probably due to toxic effects. An increase in the level of micronuclei may be associated with the genotoxic effect of DFB decay products. The genotoxicity results obtained using the micronucleus test method were contradictory. For this reason, it is necessary to conduct additional studies using the comet method or experiments on cell cultures.

   The article presents an algorithm for using spectrophotometric measurement to determine the number of cells of cultures of microalgae of the genus Tetraselmis filtered and unfiltered samples. The dependence "density – number of cells" is approximated by a linear equation with a high correlation coefficient, more than 75 %, which confirms the high reliability of the method. The ability to measure the density of unfiltered culture samples on a spectrophotometer allows you to quickly estimate the number of cells both in the field and on an industrial scale.

   The paper examines the effectiveness of artificial reproduction of the whitefish of the Baltic Sea, which in autumn comes to spawn in the Curonian Lagoon. Reproduction of whitefish began in 2009 at the experimental fish farm of FSI “Zapbaltrybvod”. The planned volume of reproduction is 150 thousand juveniles of 1-10 g. Due to the technology improvement, the actual volume in recent years has reached 350 thousand pieces. The rate of commercial return of whitefish is unknown. As an indicator of the effectiveness of artificial reproduction, biological parameters of the whitefish spawning stock have been used, which are annually assessed based on the monitoring results. It has been established that over 10 years of operation of the fish-breeding plant, there has been a change in the size and age structure of the population towards rejuvenation, which indicates recruitment increase, possibly as a result of artificial reproduction. At the same time, an increase has been noted in the indices of the number of the spawning stock of whitefish by 10 times and the volume of commercial catch by 4 times. All these can serve as artificial reproduction effectiveness indicators. It is recommended to modify the monitoring system for whitefish during harvesting of its spawners in order to obtain a more complete picture of the state of its population and assess artificial reproduction effectiveness.

   On the example of new foreign vessels put into operation in 2019-2021 and those under construction, the design features of a new generation of vessels for fishing research are considered. Due to the specifics or the research, the projects are carefully grouped by work conducted in the Atlantic and Pacific regions. The identified information on ten projects of specialized vessels with a maximum length of 44 to 85 m was analyzed, the main characteristics of which are summarized in the table. The features of the deck-laboratory complex and the scientific equipment of a number of ships of particular interest are considered. The results of the analysis draw attention to current trends in the design and equipment of fishing R/Vs.

   The article is devoted to the problems of developing an automated active trawl complex.The main structural features of the developed automated active trawl complex are described, including its hydrodynamic features, internal and external layout, polar installations and control system.

   The purpose of the scientific work is to study the indicators of the quality and safety of fish culinary products for children's nutrition.

   The object of the study were fish dishes.

   Microbiological and physico-chemical methods determined the nutritional value, toxicity and set the shelf life of products.

   The article provides up-to-date information on the impact of the nutritional
factor on the development of the child's body. The lack of a balanced diet can lead to various forms of allergies, anemia, rickets, and an increase in the frequency of infectious diseases. In this regard, fish raw materials can most fully solve the issue of meeting the needs of a child in nutrients that are important for him. One of the important indicators is the content of the dense and liquid parts in the model minced meat, because fish contains 80-81 % water in its composition, then an increase in free liquid in the minced meat recipe would lead to its dilution and the loss of the possibility of manufacturing molded products. In the course of the work, it was found that the duration of storage at a temperature of 4+-2 °C is possible for 72 hours (3 days) without changing the safety indicators. The microbiological safety of the developed products was established: The number of mesophilic aerobic and facultative anaerobic microorganisms (QMAFAnM) at all points of control of samples does not exceed the normalized level. An important aspect in the nutrition of school-age children is the organoleptic characteristics of dishes. As a result of the examination, it was determined that the products under study are characterized by attractive organoleptic characteristics: the taste and smell are not pronounced fishy, characteristic of the products, there is no taste of extraneous cod, the texture is juicy, tender, acceptable for school-age children.