Volume 5. Number 4



Environmental Concerns and the State of Aquatic Environment

A. T. Kochergin, V. A. Okunevich

Abstract. Upwelling areas are characterized by high biological productivity, which influences both the performance of sprat fishing and the development of coastal aquaculture. Based on the satellite images of the sea surface, the time ranges for weak and strong upwelling activity in the area   of Feodosia Gulf and Dvuyakornaya (Two-Anchors) Bay have been identified for June–September of 2001–2021. It has been found out that the upwelling phenomena were the most   frequent in June and   July in   the   presence of relatively warmed-up surface and cold subsurface water layers. Mildly   pronounced   upwellings   most often developed in August, when the water warmed to considerable depth, and relatively warm waters, not drastically differing in temperature from the surface ones, entered the surface layer. Strong upwellings occurred mostly in September, when the temperature difference between the center and the surrounding waters reached 9.5 °С. Weak upwellings, where the temperature of surface waters within did not drop lower than 15.5 °С, were recorded in almost all years; strong ones, with the temperature decrease down to 12 °С, were observed in 2003–2007 and 2011–2021 in various months except for August. To a large extent, the strength of upwellings depended upon the gusts of wind during their activity period, and not on the wind velocity itself, which, during the investigated period, was predominantly lower than the average long-term one, in line with its negative trend in the recent two decades. The prevailing wind direction, both during an upwelling phenomenon and three days prior, is western. Three characteristic year ranges of the inter- annual variability of the atmospheric and related upwelling processes have been identified. It is shown that upwelling phenomena depend on the intensity of zonal atmospheric transfer with a significant correlation coefficient.
Keywords: upwellings, water temperature, wind gusts, atmospheric transfers

Biology and Ecology of Aquatic Organisms

Qualitative characteristics of bottom Artemia cysts in hyperhaline lakes of the Altai Territory.
G. V. Lukerina, Ya. S. Pyatkova, D. A. Surkov, O. A. Maznikova
Abstract. Bottom Artemia cysts from 22 hyperhaline lakes of the Altai Territory have been investigated. Four groups of Artemia bottom eggs were identified: externally whole cysts; cysts with a defective chorion (rounded, whole with breaks and irregularities on the shell surface); eggs without a chorion (orange, rounded   or irregular   in shape, soft); cysts and eggs with   abnormal   coloration (black   or gray   chorion). On average, the proportion of externally   whole cysts in   lakes was 54.8 %   (Cv=31.4 %); for the cysts with a defective chorion it was 28.9 % (Cv=47.7 %), and for the eggs without a chorion it was 13.7 % (Cv=77.2 %). Cysts with black and gray chorion coloration have been recorded in the muddy soils of the Yodnoe (Iodine) Lake (42.3 % of the total concentration of cysts in the lake), Kuchuk Lake, Malinovoe (Raspberry) Lake, Bolshoe (Big) Yarovoe Lake, Kulunda Lake, and Maloe (Small) Yarovoe Lake (1.8 %; Cv=111.8 %). The correlation between the proportion of externally whole cysts and the content of sand in the soil (r=0.229) has been proved; cysts and eggs of   black and   gray   color have   been recorded in silty soils or in the soils with a high content of silt (r=0.212). No cysts were found in salt deposits, and the concentration of externally whole Artemia cysts decreases in the soils with an admixture of salt (r=-0.213). The average hatching rate of nauplii from bottom cysts in lakes was 7.8 % (0–22 %).
Keywords: Artemia (at the stage of cysts), hyperhaline lake, bottom artemia cysts, hatching of Artemia

Status of natural feed resources and habitat of crayfish in the basin of the Sal River.
E. M. Saenko, S. V. Zhukova, Yu. V. Kosenko, I. V. Korablina, A. V. Trushkov, A. O. Marchenko, V. A. Valiullin, O. A. Zinchuk, Yu. E. Karpushina, E. A. Taradina, D. S. Burlachko, L. A. Lutynskaya, T. I. Podmareva

Abstract. Crayfish is a well-established fishing target in the basin of the Sal River within the Rostov Region. The climate change causing unstable hydrological conditions, as well as the extensive anthropogenic activity have a significant impact on aquatic biological resources. This work was aimed at the investigation of the status of the water bodies and exploitable biological resources (crayfish) in the water bodies of the Sal River Basin, with the   anthropogenic pressure   and   climate changes   taken   into account. A retrospective analysis of the following parameters has been carried out: hydrological regime of the Sal River Basin since 1937, of the habitat conditions and status of the crayfish population (2012–2021), and the status of its feeding resources (2000–2013) in the context of anthropogenic activities and climate change. It has been found out that the hydrological regime of the water-deficient basin of the Sal River since the mid-1970s has been characterized by a decreased runoff during the spring flood and an increased runoff during the winter and summer–autumn low water period due to air temperature increase in the cold season. Due to the decrease in the water content of the Sal River Basin, the stream water supply lessened and the content of sulfates, chlorides and total dissolved solids in water increased, which resulted in the change of the water type from the hydrocarbonate to the sulfate one. These changes in the concentrations and ratios of salt-forming ions have been also caused by decreased precipitation and an increased feed of ground- and underground waters to the rivers of this basinThe priority toxicants and active ingredients of the pesticides of modern classes found in the water and bottom sediments of the Sal River did not affect the growth and reproduction of the crayfishCommercial productivity of crayfish stock has shown a trend   toward decrease,   which resulted from the changes in some observed climate parameters (an increase in air temperature, a decrease in water content in the Sal River Basin), as well as from the increase in total dissolved solids in the water. However, the hydrochemical regime remains to be relatively favorable for life sustenance of the bottom species of aquatic animals, and the anthropogenic pollution of the ecosystem with priority toxicants is low, which makes it possible for the population to maintain stable length composition and similar quantitative values for different length classes of crayfish, as well as its reproduction capacity.
Keywords: Sal River Basin, crayfish, structure, crayfish productivity, organochlorine pesticides, polychlorinated biphenyls, heavy metals, total dissolved solids, water content, precipitation.

Ichthyofauna of Marine and Inland Water Bodies

Black scorpionfish Scorpaena porcus Linnaeus, 1758 as a bioindicator for water pollution of the Caucasian and Crimean shelves of the Black Sea with heavy metals and organochlorine compounds.
A. A. Polin, I. V. Korablina, T. O. Barabashin

Abstract. The results of the investigation of several sets of the black scorpionfish Scorpaena porcus samples collected in two areas within the Crimean shelf and four areas within the Caucasian shelf of the Black Sea are presented. The sampling sites selected for this study are geographically located at a considerable distance from each other; the biotopes differed in terms of the influencing biotic and abiotic factors (including the hydrological regime and the degree of anthropogenic pressure). In each investigated area, three females belonging to the older age groups and selected from the set of random samples collected in spring and summer of 2020, have been examined. The morphometric and meristic characteristics of the black scorpionfish have been investigated, and the geographic differences in the average values of the relevant parameters have been identified. The ranges and average content of organochlorine compounds (persistent pesticides,   polychlorinated   biphenyls),   heavy   metals,   and   arsenic   in   the   organs   and   tissues of the black scorpionfish are presented, and the differences in their bioaccumulation are elaborated. The relationship between the level of accumulation of toxicants in the black scorpionfish and the location of various sampling sites at the Caucasian and Crimean shelves of the Black Sea has been revealed. The relationship between the level of accumulation of toxicants and the average body length of fish has also been identified. Conversely, no correlation between the levels of accumulation of toxicants and fish condition factor has been found, which may result from the high adaptive capacity of the investigated fish species.
Keywords: black scorpionfish, Black Sea, Caucasian shelf, Crimean shelf, heavy metals, organochlorine pesticides, polychlorinated biphenyls

Aquaculture and Methods of Artificial Reproduction

Specific features of rearing of the Russian sturgeon juveniles in the
Don Sturgeon Hatchery in 2021.

E. V. Gorbenko, A. A. Pavlyuk, O. A. Vorobyeva, S. G. Sergeeva,
 M. G. Panchenko 

Abstract. This work considers the results of the Russian   sturgeon   (Acipenser   gueldenstaedtii   Brandt, 1833) controlled reproduction in the Don Sturgeon Hatchery in 2021. The data on hydrochemical and hydrobiological characteristics of the environment at various stages of the production cycle are presented. Reproductive and biological characteristics of the breeders from the cultivated broodstock have been investigated. In this spawning campaign, 106 females were used; for 50 % of them, it was the second or third spawning. The body weight and condition factor of the sturgeon females were within the prescribed norm; their majority was represented by the repeat-spawning individuals. The eggs produced by these individuals were of high quality. Their fertilization, hatching, and larvae survival rates exceeded the standard values. However, the growth rate of the juveniles at the final stage of their rearing in the ponds under the mixed method of cultivation was relatively low, which could be attributed to the poor food resources provided by the ponds. The duration of rearing   the juveniles in the   ponds was extended   to 60 days   as compared to standard 40–50 days. Sturgeon juveniles released in a natural water body were morphologically well- developed, and their physiological status was satisfactory. Analysis of the data collected in the course of operational monitoring of the Don Sturgeon Hatchery made it possible to identify “bottlenecks” in the biotechnological practice of sturgeon reproduction. The violations in the practice of handling the sturgeon spawners in the Don Sturgeon Hatchery that occurred in 2021 resulted from the lack of facilities and production capacity for pre-spawning retaining of reproducing individuals. The decrease in the efficiency of sturgeon juveniles growth was predicated upon low productivity of the ponds. In 2021, 3.45 million ind. of the Russian sturgeon juveniles were obtained in the Don Sturgeon Hatchery. The exploitation rate of sturgeon spawners was high and equaled to 32.55 thousand hatchlings per one female.
Keywords: Russian sturgeon Acipenser gueldenstaedtii Brandt, 1833, broodstock, maturation rate, oocytes, fecundity, fertilization rate, survival rate, larvae, juveniles, food resource

Calculation of optimal density limits for a semi-continuous culture of microalgae Tetraselmis viridis Rouch. to maintain its maximum growth rate.
R. P. Trenkenshu, Ya. D. Zhondareva, T. M. Novikova

Abstract. On the example of the laboratory culture Tetraselmis viridis (Rouchijajnen), a method for achieving the maximum productivity in a process of growing microalgae based on a regular dilution of the culture down to a specific density (“quasi-densitotat”) is shown. The experimental basis for calculating optimal   conditions is a   cumulative curve   under specific growing conditions. Analysis   of this   curve made it possible to identify a linear growth section from the 4th to the 6th cultivation day, as well as to establish the maximum productivity (0.42 g/L·day) and find the range of densities (1.32–2.37 g/L), within which microalgae grow at maximum speed. After switching to a quasi-densitostat cultivation regime, the optimal range is narrowed from the top down by the amount of growth gain for the time between culture dilutions. For T. viridis, growth time within the optimal density range exceeds a day, which allows to keep control over the density and do the extraction only once a day, maintaining its productivity at the maximum level. With daily extraction and dilution of the culture, the optimal density range is 1.32–1.95 g/L. Transition to a quasi- densitostat mode of T. viridis cultivation   with   daily   dilution down to   1.4 g/L experimentally   confirmed the calculated data. On the cumulative growth curve, the end point of the maximum productivity phase is characterized by a sharp decrease in the growth rate, which indicates a change in the factor limiting growth at a culture density above 2.37 g/L. Further linear growth indicates that this factor is the insufficient carbon supply to the cell. Experimental verification confirmed this assumption. In the additional experiment, the flow of carbon with the air was reduced by turning off the air sprayer. It resulted in a decrease in the range of optimal densities from 0.95 to 0.69 g/L, with the maximum productivity of 0.26 g/L·day. Transition to a quasi-densitostat mode of cultivation with daily dilution to the density of 0.8 g/L experimentally confirmed the calculated data.
Keywords: microalgae, Tetraselmis viridis, semi-continuous cultivation, maximum productivity, optimal density range.

Fisheries and Processing of Aquatic Bioresources

Revision of the standards on fish preserves in special brine.
L. M. Esina, L. A. Gorbenko

Abstract. Present revision of the standards on fish preserves in   special   brine   has been conducted as   a part of operation of the Technical Committee for Standardization TC 300 “Fish products for human and animal consumption, and industrial   purposes, as well   as their package”. This article presents the   analysis of the requirements currently set by acting standards on the preserves in special brine produced using the Pontic shad, Japanese pilchard, Pacific saury, horse mackerel, Atlantic mackerel, and other fish species; the conclusion on the feasibility of inclusion of the analyzed requirements to the newest standard on preserves currently in development is stated. Taking into consideration the classification commonly used in the fisheries, the preserves with fat content in fish exceeding 8 % are proposed to be considered   as a fatty fish product; this information could be indicated in the label of preserves. It is shown to be impractical to standardize fish length in the final preserved product due to its discrepancy with the minimum landing size, which also takes into account that the catch of certain fish species is regulated by international agreements. As per requirements of TR EAEU 040/2016, presence of aging traits in preserves has not been adopted as a required property of this product, requirements for its buffer capacity have not been included in the developed draft standard, and the buffer value is not considered to be an intrinsic indicator for fish aging in preserves. The standards for the content of salt (sodium chloride) and preserving agents, as well as for the weight percentage of fish in the preserves in special brine have been elaborated and specified. Application of the developed standard will facilitate the adherence to the TR EAEU 040/2016 requirements.
Keywords: revision, standards, preserves, special brine, aging, buffer capacity, technical   regulation, Technical Committee for Standardization, physicochemical properties.

Fishing parameters of the vessels of various types in the Azov and Black Sea Basin in 2017–2021.
A. M. Stafikopulo, N. V. Vtyurina, Ya. I. Gorbatyuk

Abstract. This article considers the key aspects of the industrial fisheries in the Azov and Black Sea Basin over the last five years. The factors, determining its parameters and performance, have been analyzed; they include technical specifications and operational characteristics of the vessels of various types engaged in fishing activity, time expenditures for fishing operations, catches per unit effort, fishing areas, the state of fish stocks, the   number of vessels in operation, and other characteristics. Daily vessel activity reports on the main fishing targets—European anchovy, European sprat, Black Sea sprat, gobies—for 2017–2021 have been processed; comparative data on the performance of the vessels of various types, as well as the trends in industrial fishing parameters, are presented for the investigated period. A comparative analysis of the vessels engaged in industrial fishing in the Azov and Black Sea Basin and belonging to four types—medium fishing freezer trawler, small-size fishing trawler, receiving and   transporting   refrigerator,   refrigerating fishing seiner-trawler—has been conducted. The most high-performance types of vessels for the target species have been identified. It is also noted that, in recent years, fishing seiners and refrigerating fishing seiner-trawlers started to be involved into the fishing of other   commercial species: veined rapa whelk, Black Sea   turbot, and horse mackerel (fishing with light   attractor). The data presented will make it possible to assess the present status of the industrial fisheries.
Keywords: Azov and Black Sea Basin, industrial fisheries, types of vessels, European anchovy, European sprat, Black Sea sprat, gobies, fishing performance, fishing effort, fishing pressure


Informational Messages

First report of epimeletic behaviour in a Black Sea harbour porpoise (Phocoena phocoena relicta Abel, 1905) towards a dead calf.
A. V. Korosteleva, A. N. Postnikova, I. V. Suvorova, K. G. Kuklin

The term “epimeletic” (“caregiving”) is used to represent a range of cetacean behavioural patterns directed at dead or distressed conspecifics, including accompanying, lifting to the surface, and protecting from apparent threats. This behaviour has been described in the literature for various cetacean species; however, such reports have not yet involved members of the Phocoenidae family. The Black Sea harbour porpoise (Phocoena phocoena relicta Abel, 1905) is an endangered subspecies that is endemic to the Black Sea. Despite the proximity of its habitats to the coast, many aspects of its biology, including behaviour, remain poorly studied. In this paper, we present the first report of epimeletic behaviour in a wild Black Sea harbour porpoise towards a dead calf. The observation took place during the marine mammal stranding network operation off the Crimean coast in July 2018. A recently deceased harbour porpoise calf was found floating on the water surface close to the shore, where it was escorted by a live adult porpoise. We performed a physical examination and an autopsy of the calf, which revealed pulmonary edema, esophagitis, and enteritis. Milk was present in the stomach, indicating recent feeding. We assume that the adult individual could be a lactating female. This observation is probably the only indication to date of the possibility of wild harbour porpoises showing epimeletic behaviour towards dead calves, which emphasizes the importance of conducting wider in-depth studies on their behavioural characteristics and social interaction.
Keywords: harbour porpoise, Black Sea, cetaceans, epimeletic behaviour, marine mammals, Phocoena phocoena