Based on materials from 2006, 2015, on the river Voznesenka (south-eastern coast of Sakhalin Island) presents the results of typification of channel zones and identification of fish communities of a typical salmon river in this area of the island. Differences in the structure of fish communities in different seasons and differences in the efficiency of reproduction of spawning grounds for Pacific salmon in different channel zones of the studied river are shown.

Nowadays after a long period of depression, pacific sardine iwashi and Japanese jack mackerel are on the rise. At a high stock level, these species expand their range greatly, migrating to the high-productive Pacific waters of the Kuril Islands. The survey that was carried out in October 2019 described the distribution of pacific sardine iwashi as well as Japanese jack mackerel concentrations in the Pacific waters of the South Kuril Islands and their nutrition in autumn.

The article presents materials of long-term studies of bream from the Volga river and the Kuibyshev reservoir, and notes the changes that have occurred in its population. Before the creation of the Kuibyshev reservoir, in the Volga river sexual maturity in females of bream occurred at the age of 6–9 years, in males a year earlier. In the Kuibyshev reservoir, males began to mature at the age of 4–5 years, females — at the age of 5–6 years, and mass maturation began to be observed at the age of 9–11 years. The changes that took place both in the ecosystem of the reservoir and in the conditions of fish habitat contributed to a radical restructuring of the structure of the bream herd, which adapted to reproduction under significant fluctuations in the level regime of the reservoir. Its former, rather homogeneous local populations differentiated and began to multiply at different times. In shallow waters, it began to multiply at an earlier date, because the water here warms up faster, and in deeper places a little later, usually with repeated floods during a period of high water levels. At present, the rejuvenation of the commercial bream stock in the reservoir has been noted. In 1987, the catches included fish aged from 6+ to 20+ — 21+ years, today the age range of the reservoir bream is made up of fish 2+ — 17+ years old. This is due to the fact that over the past 20 years, in the Kuibyshev reservoir and in many water bodies of Russia, there has been an orientation of the fishery towards valuable species of fish, and to a greater extent large individuals with the greatest commercial benefit are caught.

The analysis of the possible impact of global climate change on the results of Russian fishing in the Black and Azov Seas in the 21st century, concurrent with a decrease in commercial catches, has been carried out. At present, the contribution of the Azov and Black Sea Fishery Basin to the annual total catch of Russian fishers ranges within 1,4–2,2%, which is about an order of magnitude lower than in the first half of the last century. One of the likely causes of this phenomenon may be climate change. The transformation of climatic conditions in the Azov and Black Sea Region manifests itself in an increase in the temperature of sea water in the summer and an increase in the salinity of the Azov Sea. The impact of this factor on the marine ichthyofauna of the southern regions of Russia is demonstrated by the example of the species composition of commercial and research catches. It is shown that in the current century, the proportion of thermophilic fish, which spawning season occurs in summer — European anchovy, red mullet, horse mackerel — has increased in the Black Sea. In the Azov Sea, the share of marine fish species — mullets, red mullet, horse mackerel, and the Pontic shad — has increased in the catches. It has been concluded that a thorough investigation of this issue is necessary for long-term forecasting of the state of the raw material base of the fishing industry in the Azov and Black Sea Basin of Russia.

Here are the results of studies to determine the optimal parameters of the mass of juveniles, stocking density, temperature regime and the composition of artificial feed for the adaptation of pond zander to industrial conditions. It was found that pond juveniles with an average weight of 101 mg were characterized by the best adaptive properties, which quickly (within 3–4 days) switched to the consumption of artificial feed and reached 1 g in 25 days. The average daily growth rate was 9,4%, the survival rate was 93%. On the contrary, juveniles, which grew in ponds to an average weight of 452 mg, required a two-week adaptation to new growing conditions and feed, during this period they did not feed and showed signs of cannibalism, which led to a loss of body weight up to 30% and mortality up to 58%. When growing pike perch adapted to the pond, the best results were obtained under conditions of low stocking density (2,7 ind./l) at a water temperature of 22–23 °C. Juveniles under such conditions reached a weight of 2,72 g in three weeks of rearing with a survival rate of 69%. Testing various experimental diets showed that the inclusion of microbial biomass in the feed formulation (25% of the total feed composition) increases the growth rate of juveniles by an average of 17%, and the survival rate by 13%, compared with juveniles that received a control feed containing as a source protein a combination of components in the form of soy feed concentrate (12% of the total feed) and dry egg protein (11% of the total feed). Complete replacement of fish oil (control food) with flaxseed oil in the feed increased the growth rate by 16% and the survival rate of juveniles by 16% in relation to the control variant. The results of biochemical studies of pike perch cultivated under industrial conditions indicate a decrease in the level of fat and protein in juveniles with an increase in water temperature. Replacing fish oil with flaxseed oil in the experimental diet leads to a decrease in total lipids in the body of pike perch (by 9%), and the introduction of high-protein products of microbiological synthesis into the feed instead of vegetable and egg proteins increases the protein level in juveniles (up to 9%). The hematological parameters of pike perch grown in different temperature conditions and on different diets (including the commercial feed Biomar) showed a significant decrease in the level of immature erythrocytes with an increase in water temperature and a decrease in the proportion of neutrophils when replacing fish oil in the diet with vegetable oil in experimental juveniles pike perch. Comparison of the biochemical parameters of pike perch grown in different conditions (ponds and fish-breeding basins) showed a decrease in pond juveniles, relative to the hatchery, in total fat (2,5 against 6,3 % on average), protein (15,8 against 16,9 %) and vitamin C (25,1 versus 54,3 μg / kg), and high humidity (78,4 versus 73,2%) in the fish body. Hematological parameters of pond juveniles were characterized by a relatively low proportion of mature lymphocytes (84,5 versus 88,1–90,8%), the number of leukocytes (5,5 versus 6,8–8,4 out of 500 erythrocytes) and immature erythrocytes (3,7 versus 5,4–7,6 out of 200 pcs.), and increased proportions of neutrophils (2,2 versus 0,2–0,8%) and monocytes (6,3 versus 2,5–5,7%) in comparison with pike perch grown by the combined method: first in ponds and then in industrial conditions. In general, biochemical and hematological studies of pike perch underyearlings did not reveal any obvious pathologies and significant deviations from the physiological norm, which indicates the normal state and development of fish cultured in factory conditions.

The analysis of the bivalve mollusks’ growth: blue mussels, long-necked clams and macomas, growing in polyculture with different stocking density (biomass) (30–70 kg/m²) in cages located from 1 to 5,5 m below the sea surface, was carried out. The maximum increases in length and mass of mollusks were recorded in cages with biomass of 30 and 50 kg / m² at a depth of 1–3,5m. Mollusks grew more slowly in cages with a density of 70 kg/m² at a depth of 5–5,5 m. Maximum increases in shell length (4,9–7 mm) were noted in blue mussels, and weight gains (5,6–7,7 g) were observed in long-necked clams. The highest percentage of elimination was observed in blue mussels, 7,1–12,8%, and the lowest in macomas, 1,5–2,6%. The efficiency of cultivation of various types of bivalve mollusks in polyculture in the northern part of the Sea of Okhotsk is shown.

Monitoring of prices for fish products and determining the dynamics of their changes is an important part of development of the economic regulation measures. The prices for fish products are influenced by many factors and have significant differences, depending on the type of aquatic biological resources and the type of product. At the moment, the current system for monitoring prices for fish products used by Federal State Statistics Service in accordance with the list of RCPEA does not imply detailed accounting of the cost of products by types of aquatic biological resources. In order to reflect the actual situation on the fish products market, there is a need to update the RCPEA used in the calculations in accordance with the types of aquatic biological resources and types of products for enlarged items.

The world food markets are still experiencing significant (rapid) price increases. Moreover, this phenomenon occurs with a stagnating global economy, rapid social stratification of the population and the ongoing Covid19 pandemic. The Composite World Food Price Index (CPI), calculated by FAO (Food and Agriculture Organization of the United Nations), has increased according to available data over the last year, from April 2020 to April 2021, by more than 30%. The leaders in the growth of world prices were such types of food as corn (an increase of 67%), soybeans (an increase of 70%), vegetable oil (an increase of 2 times), sugar (an increase of 60%). It is important to note that the rapid growth in world food prices is not decreasing at the present time (June-July 2021). It is known that in the previous three years (2017–2019), the world food market was extremely calm, the annual CPI fluctuations did not exceed 3%. In the course of the study, a comparative analysis of food prices, taking into account purchasing power parity (PPP), was carried out. The factors that significantly affect the level of prices in both external and internal markets of consumer food products have been established. The effective mechanisms for regulating prices in the external and internal food markets of the leading countries of the world have been identified, and their comparative analysis has been carried out. Proposals have been formulated to stabilize consumer prices in the domestic market of Russia.

The article reveals scientific, methodological and practical approaches to ensuring the sustainable development of the fisheries complex in the emerging digital economy. Worldview, ecosystem, project-target, competitive — industry, consumer — value approaches direct economic entities to transform the internal environment, business management systems to ensure sustainable development. The uncertainty of the external environment with the threats of a pandemic, the emergence of a new technological order and digitalization requires the introduction of innovations that increase the added value in production chains and the competitiveness of RCS. Increased spending on innovations in technology, communications, technical re-equipment and training of personnel in the digital environment contributes to competition in fishing and fish farming and reduces the loss of VBR. Sustainable development of the RKH based on worldview and other approaches contributes to the formation of value orientations in business transformation with a reduction in the loss of resources and time to meet consumer demand for high-quality fish products.