• Possible effect of the partial transfer of the Volga River runoff to the Don River Basin

      Zhukova, S.V.; Shishkin, V.M.; Karmanov, V.G.; Podmareva, T.I.; Burlachko, D.S.; Lutynskaya, L.A.; Taradina, E.A. (2021)
      This paper considers the consequences of the low-water cycle for the water content of the Don River, leading to an imbalance in the ecosystems of the Lower Don River and the Azov Sea and to the deterioration of the environmental conditions for aquatic biological resources. An assessment of the possible effect of the partial transfer of the Volga River runoff to the basin of the Don River amounting to 1.8 or 5.0 km3 and the impact of such transfer on the formation of the Azov Sea salinity and the desalinated areas in the Taganrog Bay has been conducted.
    • Proceedings of AzNIIRKH. Vol. 3

      Belousov, V.N. (Azov-Black Sea Branch of the FSBSI “VNIRO” (“AZNIIRKH”)Rostov-on-Don, Russia, 2021)
      Complex studies of biological resources and aquaculture utilization, biological foundation of valuable fish species reproduction, aquaculture, ecological problems and nature protection measure in the fishery water bodies of the Azov and Black Seas Basin.
    • Content of cadmium and arsenic in the veined rapa whelk viscera and estimation of the prospects for their processing

      Esina, L.M.; Chernyavskaya, S.L.; Belyakova, I.A.; Korablina, I.V. (2021)
      This work presents the data on the content of cadmium and arsenic in the viscera (visceral mass) of the veined rapa whelk Rapana venosa caught in the Azov Sea (Kerch Strait) and the Black Sea (Feodosia Gulf). In the viscera of the individuals from the Azov Sea, cadmium content was 8.6 mg/kg, and for the individuals from the Black Sea, this value was 3.5, with the allowable level 2.0 mg/kg as stipulated by TR CU 021/2011. Cadmium content in various internal organs of the investigated veined rapa whelk individuals varied. The highest content of cadmium (48 mg/kg) was recorded in the kidney of the individuals caught in the Azov Sea; cadmium content in the digestive gland also exceeded the allowable level. Arsenic content in the viscera of the individuals from the Azov Sea exceeded the allowable level by 7.8 %; this value was significantly lower for the Black Sea (0.1 mg/kg, while the established norm is 5.0 mg/kg). In several organs of the individuals from the Azov Sea (namely, the kidney, ovaries/testes, and digestive gland), arsenic content was within the normal values established by the regulations. The product derived from veined rapa whelk through enzymolysis and subsequent concentration by evaporation, was characterized by increased content of cadmium and arsenic. In terms of cadmium and arsenic content, ovaries and testes of the investigated individuals proved to be safe for consumption; their yield amounts to 10.9 % out of the entire visceral mass, and it is possible to use them as a source of valuable nutrients.
    • Analysis of the approaches to estimation of the age composition of a crayfish population

      Marchenko, A.O. (2021)
      This paper presents a review of academic sources concerning the issue of age estimation in crayfish. It describes several popular methods for estimation of the age composition of a crayfish population: age and length composition of a population, the relationship between age and lipofuscin content in nervous tissues, and counting of “growth bands”. It has been established that the most promising method for crayfish age estimation is the one based on the identification of “growth bands”. Analysis of the other methods has also shown their viability; however, for consistent age determination in crayfish, they need further elaboration.
    • Assessment of the hydrochemical status of the Azov Sea based on the data collected during field surveys in 2019–2020

      Trushkov, A.V.; Grin, A.V.; Baskakova, T.E.; Lezgovka, N.A.; Kartamysheva, T.B.; Shevtsova, E.A. (2021)
      This work presents the results of the investigation of the influence the biogenic substances exercise on the primary production of organic matter by phytoplankton in the Azov Sea in 2019–2020. The analysis of the oxygen regime and the development of kill events has been conducted. During the investigated period, the changes in the oxygen regime of the Azov Sea were observed over the course of time. The content of ammonium nitrogen and phosphorus, as well as nitrate and total ones, in the Azov Sea influences the level of organic matter primary production by phytoplankton to a considerable degree. At present, as the result of low river flow volume, the concentration of biogenic substances is decreasing, which, in turn, leads to the decrease in the primary production of organic matter. The equations describing the relationship between the primary production and the content of biogenic substances are considered.
    • Effect of oil pollution on the pelagic fish species in the Azov Sea

      Pavlenko, L.F.; Klimenko, T.L.; Anokhina, N.S.; Korablina, I.V. (2021)
      The monitoring results for the oil pollution of the Azov Sea water in the summer and autumn seasons of 2018–2020 are presented. The identified concentrations of petroleum products are given based on the total content of the main petroleum components: hydrocarbons, resins, and asphaltenes. The concentrations of petroleum products in the water ranged from <0.02 to 0.85 mg/dm3 in the summer season, and from <0.02 to 0.11 mg/dm3 in the autumn season. In some years, the weighted average values of the content of petroleum products in water exceeded the maximum allowable level: by 2.4 times in the summer season, and by 1.2 times in autumn. Based on the averaged data for the investigated period, the most severe water pollution was recorded in the central area of the Taganrog Bay and the sea itself. The highest influx of petroleum products occurs to the eastern parts of the Taganrog Bay and the sea in the autumn season, and to the southern part of the sea in summer. Along with the petroleum products identified in water, the highest content of petroleum hydrocarbons in the organs and tissues of the investigated fish was recorded in the roach, captured in the Taganrog Bay in the summer and autumn seasons of 2018. In other examined pelagic fish species of the Azov Sea (anchovy, Black Sea sprat, zander), content of petroleum products ranged at the level of determination limit.
    • Pesticides of modern classes in the water and bottom sediments of the Veselovsky Reservoir

      Valiullin, V.A.; Zinchuk, O.A.; Karpushina, Yu.E. (2021)
      The Veselovsky Reservoir is surrounded by agricultural land, where the use of pesticides is an integral part of the production cycle. By transferring with the air masses or seeping through the soil, pesticides can enter the water of the water bodies of fisheries importance, be deposited in bottom sediments, and negatively affect the vital activity of hydrobionts. The aim of the study was to detect the content of 20 active ingredients of the pesticides of modern classes most widely used in agriculture in the region, the half-life of which can exceed six months. It was found that the concentrations of pesticide active ingredients in the living environment of hydrobionts in the Veselovsky Reservoir are by more than an order of magnitude lower than the established maximum allowable concentrations (MAC), which indicates the relative safety of the environment for hydrobionts.
    • Seasonal dynamics of the total lipid content in the body of the European anchovy Engraulis encrasicolus (Linnaeus, 1758) in 2017–2020

      Voikina, A.V.; Bugaev, L.A.; Kirichenko, O.V.; Tsibulskaya, M.A.; Ruzhinskaya, L.P.; Belousov, V.N.; Sergeeva, S.G.; Lisovskaya, V.V.; Mosesyan, G.V. (2021)
      Analysis of the lipid content in the body of the European anchovy (Engraulis encrasicolus) at all stages of its life cycle for the years 2017–2020 has been conducted. This article presents a comparison of the obtained data with the reference range of lipid content that had been calculated based on the results of long-term studies. It has been found that the differences in the content of constructive and energybearing substances in the body of an anchovy individual is age-specific: the lipid content in fingerlings is lower than in the individuals at the later stages of the life-cycle. Following the investigation of interseasonal dynamics of the lipid content in the body, it has been identified that the lowest lipid content was characteristic for the anchovy in April–May, and the highest lipid content was observed in October. Analysis of the inter-annual dynamics of the lipid content in the body at the end of the feeding period has shown that, in recent years, there is a trend for the gradual decline of their amount due to increasing load of environmental factors on fish population.
    • Status of the zooplankton community in the Black Sea coastal waters (based on the data collected during an autumn monitoring survey in 2020)

      Martynyuk, M.L. (2021)
      This work considers specific features of development and spatial distribution of the animal plankton in the coastal waters of the Black Sea encompassing the areas along the Crimean Peninsula and in the northeastern part of the sea. Zooplankton community was predominantly comprised of the live feed organisms, which distribution across this areas was extremely irregular. The lowest and the highest values of the biomass and abundance of live feed plankton were recorded in the northeastern part of the sea. In the area around the Crimean Peninsula, their distribution was more uniform. The highest level of development was recorded for the representatives of the summer and autumn range of species, with Oithona davisae and Penilia avirostris as the dominant species, which prevalence is characteristic for these seasons. Sea sparkle Noctiluca scintillans was poorly developed throughout the entire investigated area. In higher numbers, this species was presented in the coastal waters of the Crimean Peninsula. The coastal waters of the Northeastern Black Sea were characterized by the highest species diversity.
    • Determination of the catchability coefficient of a survey dragnet for the juveniles of common carp and herbivorous fish species (silver carp, grass carp) with the purpose of improving the appraising method for the juveniles of the species targeted by artificial reproduction in the Azov and Black Sea Fishery Basin

      Stafikopulo, A.M.; Gorbatyuk, Ya.I. (2021)
      This article considers the main results of experimental research work aimed at determination of the catchability coefficients of a fingerling survey dragnet for the juveniles of common carp and herbivorous fish species (silver carp, grass carp), conducted in the rearing ponds of the Aquaculture Research Center “Vzmorye” (“Seacoast”) in 2019–2020 with the purpose of improving the appraising method for fish assessment. The factors influencing and determining the catchability coefficient of the survey fishing gear are discussed. The methods for conducting the appraisal surveys of fish juveniles are presented. According the methodology developed by the authors for conducting experimental research work and for determination of the calculated catchability coefficient for a survey dragnet, the source data were collected and processed; based on those data, the catchability coefficients for a survey dragnet, size 15×2 m, targeting the common carp juveniles weighted 10 g and 40–85 g, have been evaluated. The possibility of using a fingerling survey dragnet for the juveniles of herbivorous fish species (silver carp of the average weight 10 g, and grass carp of the average weight 15–25 g) has been considered, and its catchability coefficients have been identified. The possibility of using a longer dragnet, of the size 302 m, in the appraising surveys of herbivorous fish species (silver carp) has been evaluated experimentally. The results showing the unfitness of the 15×2 m dragnet for the appraisal surveys of the juveniles of herbivorous fish species (silver carp, grass carp) in the rearing ponds of the Azov Sea and Don River Region upon a headwater level 0.6–1.2 m have been obtained.
    • Status of the zooplankton in the central Syvash Bay in the summer season of 2019

      Terentyev, A.S.; Zaremba, N.B. (2021)
      The Syvash Bay is located in the Western Azov Sea and is separated from it by the Arabat Spit. After the channel was shut off in 2014, the water salinity in the bay gradually increased, which leads to the changes in the Syvash biota. During the desalinization period, the bay served as an important spawning and feeding ground for the juveniles of the Azov Sea fish species that mainly feed on zooplankton. The increase in salinity has inevitably influenced its state. It is shown that the highest indices of zooplankton development have been recorded in the northern part, the most desalinated one, and the lowest values have been observed in the southern part, characterized by the highest salinity. That said, in the northern part of the bay, zooplankton abundance was 1.2–1.4 and biomass was 2.7–2.9 times lower in July than in June. At the same time, in the southern part of the bay, characterized by the highest salinity, the average abundance of zooplankton in July was 2.1–4.4 times lower as compared to June, and for zooplankton biomass, this value was 1.5–4.1 times lower. Furthermore, rotifers and isopods were virtually absent in this area, and no nematodes and flatworms were recorded. The study has shown that, as the result of the further salinization, the Syvash Bay has the possibility to become a hypersaline water body again. In this case, the species richness of zooplankton will deteriorate considerably, and ultrasaline species will be prevalent in its species composition. This work was aimed at the investigation of the status of the zooplanktonic community in the summer season (June–July) of 2019.
    • Food safety of the barrel jellyfish Rhizostoma pulmo as a raw material for processing

      Chernyavskaya, S.L.; Belyakova, I.A.; Esina, L.M.; Korablina, I.V.; Kistina, S.N. (2021)
      Integration of new fishing or harvesting targets in the food production is always associated with the examination of the raw material and the products derived from it in terms of the safety for human consumption. A targeted harvesting of jellyfish in the Azov and Black Seas, according to the Fishing Regulations, is to be conducted within 15 June – 30 September timeframe that is characterized by the average daily air temperature around 25 °С. The results of investigation of microbiological characteristics indicate the possibility for preserving the quality of barrel jellyfish Rhizostoma pulmo during its cold storage. Microbiological safety of the raw jellyfish bells is determined for mesophilic aerobic and facultative anaerobic microorganisms, bacteria of the coliform group, and pathogenic microorganisms, including salmonella (Listeria monocytogenes). Recommended shelf life of chilled jellyfish (bells) is established at the duration of 4 days at the temperature in a refregirating chamber 4±2 °С, which should involve one of the possible cooling methods: with ice, by water immersion, or by aimbient air; recommended shelf life of frozen jellyfish at the storage temperature no higher than minus 18 °С is established at the duration of 5 months. It is shown that content of toxic elements (lead, cadmium, mercury, arcenic) in jellyfish does not exceed the specified allowable level.
    • Special features of the vertical distribution of the phytoplankton in the Kerch coastal waters (Black Sea) in the summer season of 2019

      Sereda, M.M.; Safronova, L.M.; Bondarev, S.V.; Khrenkin, D.V.; Ivanchenko, E.V.; Afanasyev, D.F. (2021)
      Following the increasing anthropogenic load on the Black Sea ecosystem, monitoring surveys of phytoplankton as the foundation of the trophic pyramid become more and more essential. The data on composition and functional characteristics of the phytoplankton in the Kerch coastal waters (Black Sea), collected in the course of the expeditionary trip of the Research Vessel “Professor Vodyanitskiy” in July, 2019, are presented. The samples were collected and processed using standard methods of hydrobiological research. Estimation of the biomass was conducted using the enumerative volumetric method based on the personally collected measurement data. Mathematical processing was performed with the original software “Phytoplankton”, developed in the Laboratory of the Systems Analysis of Aquatic Biological Resources and Databases. The changes in phytoplankton composition within the hydrological layers are shown; the quantitative parameters of the development of phytoplankton communities are analyzed. Thespecies composition and the combination of the most abundant species were compliant with those of the summer season. The highest species diversity and quantitative values of the plankton were recorded in the surface and thermocline levels. Coccolithophore Emiliania huxleyi comprised the majority of its abundance, and the dinoflagellates were the most sizable in terms of biomass. The cold mixed layer was inhabited by low-species algocoenoses with low abundance and biomass.
    • Analysis of the status of zander Sander lucioperca (Linnaeus, 1758) population in the Chogray Reservoir (2015–2020)

      Karnaukhov, G.I. (2021)
      Dynamics of the zander linear growth rate in the Chogray Reservoir has been analyzed. Actual estimates for the average length by age have been approximated by the von Bertalanffy growth equation. Joint size and age-length keys have been calculated for the years 2015–2020, and the distinctions and differences in the changes in the average body length of the individuals in relation to their age are presented. From year to year, zander asymptotic length L∞ changes from 73.5.0±6.12 (2017) to 78.5±6.0 (2019). Correlation coefficients between L∞ and Lt values changed from 0.385 до 0.823 in all cases and were significant at the high level of significance (p>0.01). It was concluded that the particularities of zander linear growth should be taken into account during assessment of fishing stocks and in rational fishery management.
    • Results of rearing roach (Rutilus rutilus L.) juveniles in the spawning and rearing farms in the Krasnodar Territory in 2020

      Poroshina, E.A.; Sergeeva, S.G.; Gorbenko, E.V.; Khorosheltseva, V.N.; Bugaev, L.A. (2021)
      This work presents the data characterizing qualitative and quantitative parameters of the roach juveniles, reared in 2020 in the spawning and rearing farms (hatcheries) of the Krasnodar Territory; the hatcheries belong both to the liman (East-Akhtarsk and Chernoerkovsk Hatcheries) and floodplain (Beysug and Yeysk Hatcheries) types. In the East-Akharst Hatchery, all migrating juveniles reached their standard weight and were characterized by good physiological status. In the Chernoerkovsk Hatchery, the weight of around 70 % of the released juveniles was lower than the normative values (300 g); their physiological status was acceptable. Density of the roach juveniles distribution in this hatchery exceeded 40,000 ind./ha, which led to high food competition. In the water bodies of the Beysug Hatchery, the average body weight and physiological status of the released roach juveniles were compliant with the normative values. In the Yeysk Hatchery, due to poor hydrological regime during the reproductive season, the efficiency of roach reproduction was extremely low.
    • Results of artificial reproduction of vimba bream (Vimba vimba) juveniles in the Azov Sea and Don River Region

      Zipelt, L.I.; Gorbenko, E.V.; Pavlyuk, A.A. (2021)
      Recruitment to the vimba bream (Vimba vimba natio carinata (Pall.)) population with juveniles in the Azov Sea Basin occurs through both natural and artificial reproduction. This work presents the results of long-term studies aimed at the assessment of artificial reproduction and rearing the juveniles of vimba bream in the Azov Sea and Don River Region. The quality of the juveniles released into a natural water body has been assessed based on their morphometric characteristics and the chemical composition of their muscle tissue. The criteria for quality assessment based on the fat, protein, and ash content have been established. The correlation between morphobiological characteristics and fecundity has been identified; the equations for calculation of some parameters, such as weight of the gonads and estimated operational fecundity, have been derived. The recruitment to the stocks of aquatic biological resources with vimba bream juveniles for the last 7 years (2015–2021) is presented.
    • Status of the Azov Sea populations of roach and zander at the present time

      Zherdev, N.A.; Lukyanov, S.V. (2021)
      Roach and zander are valuable semi-anadromous fish species, targeted by fishing operations in the Azov Sea, which necessitates evaluation of their current status. This article analyzes the data collected during the trawl surveys in the Azov Sea, the assessment of the juveniles of exploitable fish species in the Lower Don, the investigation of the reproduction in the water bodies of the Azov limans and spawning and rearing farms (hatcheries), and the monitoring of fishing catches in 2018–2020. In these three years, the feeding area of roach and zander decreased from 2,618 to 1,400 and from 1,230 to 822 km2, respectively. Roach catch decreased from 730.243 to 282.110 t. For the time, the exploitation of zander was suspended after the temporary fishing ban introduced in 2017. Age composition of the roach fishing stock consisted of four age groups; among them, three-yearlings (30.5 % by abundance, 23.6 % by weight) and four-yearlings (54.2 % by abundance, 51.4 % by weight) prevailed. Average age decreased from 3.1 to 2.8 years. Age composition of the zander fishing stock in the Don River was characterized by three age groups. In terms of abundance, three-yearlings prevailed (69.5 %), four-yearlings comprised 25.7 % of the total abundance, and five-yearlings comprised 1.5 % of it. In the Kuban River population of zander consisted of seven age groups. The most abundant were yearlings (54.4 %). Two-yearlings comprised 8.9 % of the total abundance, the share of three-yearlings was 25.0 %, and the eldest age groups of 4–7 years comprised 10.7 %. Quantities of the juveniles released in 2018–2020 from the water bodies used for natural and artificial reproduction came to be insufficient for proper recruitment to roach and zander stocks. Water bodies belonging with the hatcheries are the main sources for roach recruitment, and the Azov limans of the Krasnodar Territory serve the same purpose for zander.
    • Assessment of the bream population in the Veselovsky Reservoir at the present time

      Chubova, E.E.; Saenko, E.M.; Golovko, G.V. (2021)
      This paper presents the analysis of the field data collected in 2012–2020 and the academic sources concerning the population status of common bream (Abramis brama) in the Veselovsky Reservoir (Rostov Region) under current biotic and abiotic conditions. In the recent period (2012–2020), 6-yearlings prevail in the age composition of the bream population; older age groups are recorded in small number. The age composition varies depending on the productivity of a generation. Absolute fecundity of the females, on average, is 96.8 thousand eggs. Fishing stocks of this species are relatively stable despite inter-annual fluctuations of its abundance and biomass, which indicates that, at present, the bream population in the Veselovsky Reservoir is in a satisfactory condition; its fishing stocks in the coming years are predicted to be at the level of 162–165 t.
    • Fishery and biological characteristics of the big-scale sand smelt, flathead grey mullet, and picarel exploitation in the marine coastal waters and the stocks of these species in the Azov and Black Sea Fishery Basin in 2018–2020

      Shlyakhova, O.V.; Efanov, A.D.; Isachkov, A.E.; Kirnosov, E.A.; Morozova, I.A. (2021)
      A brief description of the biology, fishery and stock units of big-scale sand smelt, flathead grey mullet, and picarel is given for the Russian fisheries in the coastal areas of the Black and Azov Seas. The data on the annual catches in 2000–2020, age, length and weight compositions of the catch in 2018–2020, and the present status of the stocks of these species in 2020 are presented. The estimates for the abundance, biomass and fishing mortality of the three investigated stock units based on the Jones’ length cohort analysis are presented. It is shown that the present stock of big-scale sand smelt, as compared with that for the two previous years, has decreased, the stock of flathead grey mullet has increased, and the stock of picarel has remained stable. If ranked by their status over the last 3 years and the degree of their thermophility, the stock of flathead grey mullet, the most thermophilic species, was increasing, the stock of picarel, which holds the middle position, remained at the same level, and the stock of big-scale sand smelt, the least thermophilic species, was decreasing.
    • Status of the Azov Sea populations of common bream and vimba bream at the present time

      Cherednikov, S.Yu.; Vlasenko, E.S. (2021)
      After introduction of the fishing ban on sturgeons and zander, common bream and vimba bream became the most valuable fishing target for the fisheries organizations. For this reason, characterization of the current status of the populations of these two native species becomes rather crucial. In this article, the data collected by research catches with a bottom trawl in the Azov Sea, recurrent trips for assessment of the juveniles with fry dragnet in the Lower Don mainstream, and the monitoring of fishing catches for years 2018–2020 are presented. In these 3 years (high-water 2018 and low-water 2019–2020), the status of the Azov Sea populations of these two valuable fish species changed considerably. The average weight and average age of common bream decreased; however, these values in vimba bream grew higher. The generation of common bream born in the high-water 2018 played a dominant role in its fishing stock in 2020: the share of common bream 3-yearling was 40.8 % out of entire population abundance. As for vimba bream, in 2020, the generation born in 2016 prevailed; its share was 56.3 % in terms of abundance. Fishing exploitation of these species also underwent notable changes: in these years, the annual catch of common bream and vimba bream increased by 4 and 2 times, respectively. Recruitment with juveniles in both species depended on hydrological conditions in the spring season. With the exception of high-water 2018, the conditions for natural spawning of anadromous and semi-anadromous fish species in 2019–2020 were unfavorable; the reduction of feeding area resulting from salinization of the Azov Sea was observed for both species. Thus, by 2020, vimba bream abundance stayed at a low but stable level, which indicates a certain degree of equilibrium between recruitment and mortality. The status of common bream population should be considered as depressed.