CONTENT
Review Articles
Scenario forecast of the development of the fishery resources and fish catches in the Azov Sea in the context of declining freshwater runoff and increasing salinity
Mirzoyan A.V., Belousov V.N., Shlyakhov V.A., Dudkin S.I., Luzhnyak V.A., Nadolinskiy V.P.
Abstract
Background. The reduction in freshwater runoff and the increase in the Azov Sea salinity are accompanied by a drastic transformation of aquatic biocenoses, as well as restructuring of various ecological groups of the ichthyofauna. Abrupt changes in the composition and abundance of fishing targets render traditional approaches to fishing ineffective and dictate the need to develop new kinds of fishery. Relevance. Identification of possible scenarios of the fishery resource development for the next 5–10 years is necessary to ensure the fisheries sustainability in the Azov Sea Basin. The aim of this work is to analyze the dynamics of the composition of commercial fish catches in the Azov Sea in the modern period of the sea salinization and to develop possible status scenarios for the stocks and catches of fishing targets for the next 3–10 years to substantiate fisheries management and regulation. Methods. In the course of developing such scenarios, the data on the actual dynamics and trends in the fishery resource changes during the comparable periods have been used, as well as the data on the ecological valence of the representatives of various ecological groups of fish at different stages of their ontogenesis in terms of their salinity tolerance. Results. 3 main unequally probable scenarios of changes in the abundance and biomass of various ecological groups of fish—primary industrial-scale fishing targets in the Azov Sea—have been developed; the recommendations for adapting the existing fishing practices to the changes in the fishery resources have been given. Conclusion. A further decrease in the commercial importance is predicted for the freshwater fish species, freshwater-spawning anadromous and semi-anadromous fish species, as well as for gobies and Black and Caspian Sea sprat (tyulka). The role of Black Sea migrants—European anchovy, grey mullets, red mullet, Mediterranean horse mackerel, garfish—will be reduced. Marine fish species—acclimatized so-iuy mullet and Black Sea turbot (kalkan)—will become the main fishing targets.
Keywords: Azov Sea, salinity, fish species, forecast of changes, fishery resources, industrial fishing, fisheries management
Environmental Concerns and the State of Aquatic Environment
Dynamics of the concentrations of dissolved heavy metals in the Moscow River water based on the data of the monitoring surveys conducted in 2021–2023
Kladiti S.Yu., Dukhova L.A., Oganesova E.V., Barabashin T.O.
Abstract
Background. The Moskva River is a prime example of a natural urban watercourse subjected to strong and varied anthropogenic pressure. For many years, this river has been characterized by increased content of heavy metals. The exceedance of the maximum allowable concentrations of harmful substances in the waters of water bodies used for fishery can result in disruption of the normal functioning of aquatic ecosystems. Relevance. The summarized data collected over the course of monitoring surveys of the Moskva River for three years will be indicative of the relative contribution of natural and anthropogenic sources into its pollution. The aim of this work is to identify the dynamics of spatial and temporal distribution of heavy metals in the Moskva River water and its relation to hydrological seasons, as well as to assess the anthropogenic pressure exerted by the city of Moscow on the river. Methods. Water samples were collected in 2021–2023 during four hydrological seasons. Identification of heavy metals in the collected samples has been carried out using the atomic absorption method. Results. The analysis of the content of dissolved heavy metals (iron, cadmium, cobalt, manganese, copper, nickel, lead, and chrome) in the Moskva River water in various seasons of 2021–2023 has been conducted, and the same was done for zinc in 2023. The dynamics of the spatial and temporal distribution of these heavy metals has been identified, as well as its dependence on the hydrological phases. The influence of the urban infrastructure on the composition of the Moskva River water has been elucidated. Within the investigated area, the exceedance of the values prescribed by the water quality standards for the water bodies used for fishery (MACfish) has been recorded. Conclusion. The waters of the Moskva River have been characterized as polluted, mainly with iron, manganese, copper, and zinc. For lead, chrome, cobalt, nickel, and cadmium, no exceedance of the MACfish has been recorded. It has been found that the majority of the investigated elements were exceeding the values prescribed by the established standards in the spring season, but their concentrations decreased in summer.
Keywords: heavy metals, Moskva River, anthropogenic pressure, MACs for the water bodies used for fishery
Classification of the trophic capacity of water bodies based on chlorophyll content using remote sensing through the example of the Chogray Reservoir during the period 2021–2023
Mirzoyan A.V., Piatinskii M.M., Sirota Yu.V.
Abstract
Background. The Chogray Reservoir is a large artificial water body in the south of Russia, which is used for commercial fisheries. Relevance. The investigation of the spatio-temporal variability of the main biological parameters of this reservoir and identification of its trophic status is of immediate importance due to the currently observed increase in the total dissolved solids and eutrophication rate in the context of frequent seasonal fluctuations of its water level. The aim of this study is to develop an approach to the trophic classification of a water body based on chlorophyll content with the use of remote sensing data. Methods. 55 Sentinel-2 satellite images for the period 2021–2023 have been used as the primary data for this research allowing to calculate NDWI and NDCI for the future approximation of the chlorophyll-α and relative phytoplankton biomass values. Results. The seasonal dynamics of phytoplankton vegetation in the reservoir has been identified (the period of vegetation starts in February and ends in October, with the peaks of abundance in July and September), as well as the long-term dynamics of phytoplankton biomass. The spatial patterns of the phytoplankton vegetation dynamics in the reservoir have been determined. Conclusion. The Chogray Reservoir has the status of a mesotrophic water body with eutrophic features in some water areas in the late summer – early autumn season. An increase in the duration of phytoplankton large-scale vegetation until the end of October has been recorded.
Keywords: Chogray Reservoir, phytoplankton, chlorophyll, classification, remote sensing, trophic capacity
Biology and Ecology of Aquatic Organisms
Spatial trend and ratio of the gelatinous to forage zooplankton biomass in the World Ocean
Meger Ya.V., Piontkovski S.A.
Abstract
Background. Zooplankton is an important structural component in the trophic web of aquatic ecosystems, ensuring the transfer of matter and energy from producers (phytoplankton) to consumers (small pelagic fish). Relevance. The increase in the gelatinous-to-forage zooplankton biomass ratio and the partial redirection of carbon flux to detrital chain induced by gelatinous organisms can have an adverse effect on the reproduction of fish stocks in the World Ocean and on the income from global fisheries, most of which originates in the Northern Hemisphere. The aim of this study was to test the hypothesis suggesting the existence of a negative trend in the large-scale spatial variability of the gelatinous zooplankton biomass in the direction from the continental shelf to oceanic waters. Methods. The analysis of 223 5-degree squares, which measurements were extracted from international databases and literature sources, has been performed. Additionally, the ratio of the gelatinous to forage zooplankton biomass has been calculated for 393 5-degree squares. Results. It has been shown that the decrease in the gelatinous biomass observable in the direction from the continental shelf to open ocean waters is statistically significant despite the 7-fold variability in large-scale spatial distribution. The median of the long-term biomass of gelatinous zooplankton in the Northern Hemisphere waters is ten times higher than in the Southern Hemisphere. The median of the gelatinous-to-forage zooplankton biomass ratio is also higher in the Northern Hemisphere. Conclusion. A correlation analysis of the gelatinous zooplankton biomass and the flux of suspended organic carbon at the bottom of the euphotic layer of the World Ocean showed the statistical significance of their relationship. The prevalence of the gelatinous zooplankton biomass over the forage zooplankton biomass indirectly indicates the partial passage of the organic carbon flux not through the grazing food chain but through the detrital one.
Keywords: zooplankton biomass, pelagic ecosystems, World Ocean
Ichthyofauna of Marine and Inland Water Bodies
A body volume model for the common perch Perca fluviatilis L., 1758
Shumak V.V.
Abstract
Background. Expansion of the digitalization possibilities in the modern scientific research aligns with the trends in societal development. The study of the body shape features of a fish contributes to collecting the primary material for further processing. The species-specific morphometric characteristics provide the means to derive a model from the original. Relevance. The improvement of methodological approaches to the creation of digital models in ichthyology and fish farming is crucial for expanding the possibilities of studying fish biology. The aim of this work is to substantiate the methodological approaches to the introduction of a digital model for a fish species using the common perch Perca fluviatilis L., 1758 as an example. Methods. The collection of primary material has been carried out according to conventional methods of ichthyological research. The volume of a fish body has also been studied through the example of a body shape model based on the collected morphometric data in the form of the sum of two halves of two ellipsoids. The possibility of using morphometric characteristics for creation of a “morphological passport” of a fish species has been investigated. Results. The ratio of the measured body volume of a common perch to the calculated volume according to the model featuring the sum of the halves of two ellipsoids has been identified. Based on the obtained values, it has been found to be close to 0.97, which is compliant with the investigated model by 97 % and determines the development of the common perch in the Dnieper–Bug Canal within the Pinsky District, Republic of Belarus. The rationale for using a non-specific data presentation for a fish species with the common perch as an investigation target is given based on the length from the end of its snout to the end of its scale covering. Following the results of
this study, it has also been found out that the percentage values regarding l1/l in the common perch fingerling changed as compared to those of seven-yearling from 25 % to 17 %. However, the investigated
O/l ratio increased from 43 % in fingerlings of this species to 50 % in older age groups. Conclusion. The sum of the ratios of the common perch body length taken from the top of the snout to the vertical line drawn from the base of the ventral fins to the dorsal fin, as well as its body width, height, and girth, to the length of its body from the top of the snout to the end of the scale covering has been identified. It started with 1.218 in fingerlings and increased to 1.926 in seven-yearlings. This unique combination of the four values of the investigated relationships can be used in creating a digital “morphological passport” of the common perch.
Keywords: common perch Perca fluviatilis, body width, body height, body length, body shape, model
Fisheries and Processing of Aquatic Bioresources
Improvement of trawl fishing of the Black and Caspian Sea sprat (tyulka) in the Azov Sea in the current context of restoration of the sturgeon fish species populations
Stafikopulo A.M., Andronov V.A., Vtyurina N.V., Gorbatyuk Ya.I.
Abstract
Background. At present, the Black and Caspian Sea sprat (tyulka) is the least exploited species of the aquatic biological resources in the Azov and Black Sea Fishery Basin, although it has always been a valuable fishing target and a possible reserve pool for the increase of fish catches in the Basin. In the recent years, with the increasing number of midwater trawls allowed for using in the Black and Caspian Sea sprat (tyulka) fishery, all vessels transitioned to its trawl fishing; however, its total catch is decreasing, and the fishing results of these vessels are on the decline. Relevance. Taking into consideration the stock restoration occurring to the sturgeon fish species in the Azov Sea Basin in the recent years, it is necessary to take measures for maintaining this trend, as the Black and Caspian Sea sprat trawl fishing can result in increased mortality or injury of sturgeon fish and considerably damage their population. With a substantial decrease in the Black and Caspian Sea sprat fishing stock, the matter of stock restoration of the sturgeon fish species in the Azov Sea can induce the prohibition of the trawl operations in this water body, including the complete ban of the insufficiently profitable trawl fishing of the Black and Caspian Sea sprat in its current form. The aim of this article is to examine the design of the midwater trawls used in the Black and Caspian Sea sprat fishing in the Azov Sea, to investigate the global best practices in the trawl selectivity improvement, and to substantiate the main design characteristics for the specialized tyulka midwater trawls and means of their selectivity improvement. Methods. The standard methods of sample collection and data processing that could characterize fishing methods, gears and techniques for harvesting aquatic bioresources have been used. Results. The designs for the specialized trawls for the Black and Caspian Sea sprat fishing (exploitation) and methods for their selectivity improvement have been developed. Conclusion. These specialized trawls with the sorting units and a new principle of using otter boards (trawl doors) can increase fishing selectivity and mitigate possible damage inflicted by trawling to the populations of sturgeon fish species in the Azov Sea.
Keywords: Azov Sea, industrial fishing, fishing gear, Black and Caspian Sea sprat (tyulka), sturgeons, selectivity, midwater trawl, unwanted by-catch, sorting unit, types of vessels, wintering aggregations
International Cooperation
Cooperation between the Russian Federation and the Republic of Abkhazia in the field of fisheries: results and prospects
Dudkin S.I., Dbar R.S., Shcherbakova N.I., Bragina T.M., Belousov V.N.
Abstract
Background. The Republic of Abkhazia has a high natural and climatic potential for the development of fisheries and aquaculture, which creates a reliable basis for its cooperation with the Russian Federation in the field of fisheries. Relevance. The analysis of the efforts of these two countries in the field of fisheries is relevant for the further advancement of their cooperation and can facilitate the sustainable development of fisheries and aquaculture, as well as rational and economically efficient use of aquatic resources in the Southeastern Black Sea. The aim of this work is to give an overview of the dynamics of the fisheries activities conducted by the Republic of Abkhazia over the past decade and to present the results of its international cooperation with the Russian Federation undertaken within the scope of the Intergovernmental Russian-Abkhazian Fisheries Commission in 2011–2024. Methods. The analysis of the developmental indices of the fisheries of the Republic of Abkhazia and the provisions of the sessions of the Russian-Abkhazian Fisheries Commission in the context of implementation of its decisions has been conducted. Results. The achievements in the main avenues of scientific, technological, educational, and economic cooperation between the Russian Federation and the Republic of Abkhazia in the field of fisheries are shown. Eight sessions of the Commission have been conducted, under the auspices of which the scientific and technological cooperation between fisheries organizations of Russia and Abkhazia in the area of multidisciplinary ecological and fisheries research has been envisioned and implemented, annual catches of anchovy during its wintering in the waters of the Republic of Abkhazia have been coordinated, operating conditions of the Russian fishing vessels in the Abkhazian sea waters have been established, and the Fishing Regulations for the waters of the Republic of Abkhazia have been developed in compliance with the provisions and articles of the Russian Fishing Regulations for the Azov and Black Sea Fishery Basin. Conclusion. Cooperation between the Russian Federation and the Republic of Abkhazia in the field of fisheries has a significant potential for deepening and development.
Keywords: Republic of Abkhazia, Black Sea, international cooperation, aquaculture, fishery, anchovy, catch
Informational Messages
On the anniversary Tenth International Symposium on Sturgeon (ISS10) (Yichang, China, October 20–25, 2025): current issues
Chebanov M.S., Bragina T.M.
Abstract
Background. The decline in the population and the threat of extinction that is currently applicable to most sturgeon species, as well as changes in their habitat and spawning environment have been the focus of attention for scientists and governments of different states for many years. Relevance. The preservation and restoration of fishing stocks of valuable sturgeon species and conservation of other vulnerable species are urgent tasks within the scope of rational use of natural resources and conservation of biological diversity and require international efforts. The aim of this work is to consider the main subject matters and focal areas of the upcoming Tenth International Symposium on Sturgeon, which will be held on October 2025 in Yichang (China). Methods. The main topics of the preliminary reports of the participants and speakers of the symposium have been analyzed, as well as the problems set out to be discussed over its duration. Results. This article is intended to familiarize the scientific community of Russia and other countries with the international-level matters associated with the upcoming symposium. Conclusion. The relevance of the international discussion of the current status of studies concerning sturgeon fish species, of increasing their natural reproduction efficiency, their breeding and rearing in the context of declining population abundance have been emphasized, as well as importance of identification of the prospects and challenges in restoration of some species' populations with consideration to the dedicated long-term release of sturgeon juveniles into the natural water bodies and exploration of the approaches to their ex situ conservation.
Keywords: International Symposium, Yichang, China, sturgeons, breeding, ex situ conservation