RSS 1.0EUROPE
Browse by
Sub-communities within this community
-
Germany [2450]
-
Latvia [109]
-
Poland [33]
-
Russian Federation [725]
-
Ukraine [140]
Collections in this community
Recent Submissions
-
On the fifth anniversary of the scientific peer-reviewed journal “Aquatic Bioresources & Environment”Водные биоресурсы и среда обитанияThe scientific peer-reviewed journal “Aquatic Bioresources & Environtment” has been published since 2018 and functions as a discussion platform for researchers and practitioners of the vast fishery region (mainly the Southern Russia). In July 2023, the journal celebrated its fifth anniversary. The aim of this article is to review the notable milestones of the formation of the journal as a scientific publication from its first issue up to the present moment. Currently, the journal is included in the List of peer-reviewed scientific publications, in which the main scientific results of dissertations for the degree of Candidate of Science and for the degree of Doctor of Science should be published (List of the Higher Attestation Commission), and is abstracted in the International Information System for Aquatic Sciences and Fisheries Abstracts (ASFA) and the Scientific Electronic Library e-library.ru (eLIBRARY), as well as indexed in the Russian Science Citation Index (RSCI). Articles in the journal are assigned with Digital Object Identifiers (DOI), which are registered by the international agency Crossref; they are posted on the journal's website and added to RSCI and other databases.
-
Stock assessment of the marine fish species in the Black Sea (Russian waters) in 2021Водные биоресурсы и среда обитанияBased on the available biological and fisheries data, stock status review for 18 units of the fish species inhabiting the Black Sea and the both Azov and Black Seas is presented. A modified version of the traditional approach to the harvest control rules for the aquatic bioresources of the Azov and Black Sea Fishery Basin is described for the case when they are assessed by the mathematical methods to estimate the current stock biomass and fishing mortality. For 11 stock units, analytical modeling including cohort, production and trend models has been applied. Based on the estimates of biomass and fishing mortality concerning biological reference points, in 2021, the status of six stock units of the marine fish species inhabiting the basin and exploited by the Russian fisheries was identified as increasing or stable (“Black Sea” stock units of the European sprat and European anchovy, “Crimean” stock unit of turbot, “Crimean and Caucasian” stock unit of red mullet, and “Black and Azov Seas” stock units of garfish and rays). Five fishery stock units (“Crimean and Caucasian” of mullets, picarel and Mediterranean horse mackerel, “Black and Azov Seas” of sand smelts, and “Caucasian” of turbot) have shown a decreasing trend in terms of abundance, and for the rest of the investigated fish stock units (“Mediterranean migrant” bluefish, Atlantic bonito and Atlantic mackerel, “Black Sea” whiting, so-iuy mullet and the other marine fish species, “Black and Azov Seas” spiny dogfish), the status has not been determined due to the absence of systematic biological and fishery data.
-
Fluctuating asymmetry of the head seismosensory canals in roach Rutilus rutilus (L.) from the middle rivers of Udmurtia with different levels of chemical pollutionAquatic Bioresources & EnvironmentIn the middle rivers of the Udmurt Republic, fish were caught near the sampling stations for the state environmental monitoring. The fluctuating asymmetry (FA) of the pore number of the seismosensory canals in the dermal head bones of the roach, Rutilus rutilus (L.), which prevailed in the catches, was estimated using osteological analysis. Its indicators in the roach individuals caught in the different river sections have been collated with the values of specific combinatorial water pollution index (SCWPI) of the examined sections and with the average concentrations of some pollutants in water in late spring and early summer for the several years preceding the years of catching. A statistically significant trend for the increase in the FA variance (Sas2), calculated on the basis of the total number of pores in the head seismosensory system of the roach, with the increase in the SCWPI and the content of some anions (chlorides, nitrites, nitrates) in the river water of its habitats has been identified. The highest Sas2 was observed in the roach individuals caught in the Izh River dowstream from Izhevsk in the environment, severely polluted by municipal wastewater, while the lowest one was recorded in the Kilmez River, the least polluted by wastewaters. No significant relationships between the FA indicators in this fish species and the content of heavy metals or other pollutants in the middle rivers of Udmurtia have been revealed. These results are considered to be attributable to a decrease in stability of morphogenesis in the fish organisms that developed under non-optimal (stressful) hydrochemical conditions.
-
Characterization of the beluga breeding practices at the Don Sturgeon HatcheryВодные биоресурсы и среда обитанияThe study conducted in 2022 has identified a lack of consistency in the results of the beluga artificial reproduction at the Don Sturgeon Hatchery (DSH). To obtain eggs, mostly the females born in 2001–2004 were used, out of which 31 females at age 18 reached their first maturity and one female at age 21 was a repeat spawner. The majority of first-spawning females produced eggs of low quality. During incubation, there was a substantial loss of fertilized eggs, and various anomalies of embryonic development were observed, which necessitated termination of the incubation of such eggs. The yield of one-day larvae from the eggs obtained from the first-spawning females and set for incubation was low, around 12 %. One of the reasons for the increased mortality rates and development anomalies in the larvae was low quality of the oocytes in the first-spawning individuals. A second-spawning female has shown satisfactory results; the fertilization rate was in line with the standard values, and no more than 17 % of the eggs manifested embryonic anomalies during their incubation. The yield of one-day larvae was 53.3 %. In total, 799 thousand one-day beluga larvae were obtained. The analysis of the cultivation practices at the Don Sturgeon Hatchery made it possible to identify the bottleneck points and critical junctures at some stages of the biotechnological process, as well as to give recommendations on improvement of the hatchery operation. An important prerequisite for obtaining good results is the physiological adequacy of beluga females, which is based, for the most part, on the living environment and feeding quality of the breeders and their replacement in the broodstock.
-
Hydrobiological communities of the middle reaches of the Lena RiverВодные биоресурсы и среда обитанияThe investigated site is located within the area of the Yakutsk Urban District and subjected to a high anthropogenic load. The construction of a bridge over the Lena River at its middle reaches is crucial for transport accessibility but will have a negative impact on aquatic bioresources and their habitat. Previously, this section of the river has not been studied, so the results will be indicative of the current state of aquatic biological resources and their habitat. This factor determined the aim of this study: the status assessment of the hydrobionts inhabiting a localized area in the middle reaches of the Lena River. The hydrochemical analysis of water samples has been carried out in the laboratory of the Republican Center for Information, Analysis and Environmental Monitoring (State Budgetary Institution “RIATSEM”); collection and laboratory processing of zooplankton and zoobenthos samples have been conducted according to generally accepted methods. The hydrochemical composition and dissolved gases of the aquatic environment in the localized section of the Middle Lena River in the vicinity of the bridge crossing are favorable for the development of organic life. Zooplankton is represented by 54 species, more than a half of which is comprised by rotifers (52 %). The average biomass of zooplankton in the spring and summer seasons was 1.135 g/m3; in the autumn and winter seasons it was 0.057 g/m3, and the average annual value was 0.238 g/m3. Crustaceans have the highest share in the biomass, and rotifers are the most abundant. Zoobenthic organisms are represented by 9 groups; oligochaetes and chironomid larvae prevail throughout the year. The average biomass of the zoobenthos in the area along the shore was 37.41 g/m2; in the auxiliary streams it was 174.84 g/m2, and in the main course it was 3.52 g/m2. Following the results of this study, the qualitative and quantitative characteristics of the invertebrates have been found to be indicative of a favorable state of their habitat.
-
Long-term variability of oceanic zooplankton biomassВодные биоресурсы и среда обитанияNumerous scientific publications are dedicated to the analysis of long-term variability of zooplankton biomass in oceanic and neritic zones of the World Ocean. The number of these publications keeps growing with the availability of new data. Relevance of this research can be attributed to the crucial role of zooplankton biomass in the spatio-temporal and trophic structure of aquatic ecosystems. Interannual fluctuations of zooplankton biomass affect the catch volumes of small pelagic fish. This research is aimed at identification of statistically valid long-term trends of the World Ocean zooplankton biomass, which involves the analysis of the data from databases and published articles describing such variability. Regional and international databases (namely COPEPOD, HOT, JGOFS, ODATE and others), which are available in the form of CDs, archived materials, and online, have been used. For the time series of the biomass across 21 areas of the World Ocean (Pacific, Indian, Atlantic Oceans and internal seas), the regression analysis has been conducted, which made it possible to estimate the parameters of linear monotonic trends. Based on bivariate spatial autocorrelation functions, the areas within which the trends are statistically homogeneous have been identified. A comparative study of long-term variability of zooplankton biomass, phytoplankton biomass, primary production, and the total live biomass of the pelagic World Ocean is presented. It is shown that the spatial distribution of positive, negative and neutral trends of zooplankton biomass on the World Ocean scale is heterogeneous. The negative monotonic trends of zooplankton biomass are found to be prevailing (in 1980–2010s); the regression parameters describing them are presented.
-
Energy metabolism of Mytilus galloprovincialis under low seawater pHВодные биоресурсы и среда обитанияThe problem of acidification of the World Ocean and predicting the consequences for its inhabitants is becoming more and more relevant every year. The effect of short-term pH fluctuations in coastal ecosystems on the physiology of calcifying organisms—bivalves—remains poorly understood. The energy metabolism of the Black Sea mussel Mytilus galloprovincialis was investigated for the marine environment in a wide pH range, from 8.2 to 6.65. Lowering the pH to 7.0–7.5 led to a 20–25 % reduction in oxygen consumption by molluscs. At lower pH (6.54–6.7), aerobic respiration sharply decreased by 85– 90 %, down to the minimum values (2.12–2.62 μgO2/g dry/h), and the organisms transitioned to anaerobic metabolism. The metabolic response of the mussels subjected to short-term pH changes (8.2→6.65→7.2) has been investigated. The oxygen consumption of molluscs exposed at the same pH of 7.2 depended on the direction of the change in pH. Thus, in the case of pH 6.65→7.2, the respiration intensity was 30 % higher compared to the values obtained under the acidification pH 8.2→7.2. The Black Sea mussel M. galloprovincialis is shown to have the capacity for survival in the marine environment characterized by the rapid fluctuations in pH that occur during the upwelling events in the coastal areas of the Black Sea.
-
Infection of cyprinid fish with larvae of human-pathogenic helminths and bacteria in the Lower Volga River Delta at the present timeВодные биоресурсы и среда обитанияRecreational and artisanal fishing is very widespread in the Astrakhan Region; its primary targets are cyprinids, which are susceptible to epedemiological threats. Food products derived from the biological resources harvested during such fishing are not subjected to the processing in specialized facilities, and therefore, safety of the final product for its consumer cannot be ensured. In this region, the diseases, the agents of which are transmitted through fish and the products of its processing, are annually recorded among the population. Sanitary and parasitological control is one of the components in the set of measures for the prevention of these diseases. This work was aimed at evaluation of the infection level in some species of commercially valuable cyprinids in the Lower Volga River Delta with bacteria and larvae of pathogenic helminths capable of causing the development of diseases in humans. An incomplete helminthological survey of Caspian roach, common bream, white bream, crucian carp and rudd, as well as microbiological examination of their muscle tissue have been carried out in accordance with the requirements of the regulatory documents currently in force with application of methods described in State Standards. Larvae belonging to four species of human-pathogenic parasites have been recorded in the parasitic fauna of the Caspian roach, rudd, and white bream. Common bream was infected by larvae belonging to two species of such helminths. The identified larvae of pathogenic trematodes and nematodes were viable. The level of bacterial contamination of fish muscle tissues did not exceed the standard-prescribed limit, and the sanitary indicator microorganisms were absent. The results of the parasitological study indicated the need for mandatory disinfection of cyprinid fish from larvae of pathogenic helminths.
-
Qualitative and quantitative composition of hydrocarbons in bottom sediments in the Northeastern Kara SeaВодные биоресурсы и среда обитанияThe surface layer (0–5 cm) of the bottom sediments, which samples were collected during the expedition of the RV “Academician Boris Petrov” in the Northeastern Kara Sea in the summer of 2022, has been investigated. Data on the content and composition of hydrocarbons (HCs) in the bottom sediments of the investigated aquatic area have been obtained. Since oil and petroleum products are among the most common sources of pollution of the seas and oceans, it is necessary to conduct regular surveys of marine ecosystems. This work is aimed at a qualitative and quantitative assessment of HCs in the bottom sediments of the Northeastern Kara Sea and identification of their possible sources. Examination of the qualitative and quantitative composition of HCs was carried out by gas chromatography using the gas chromatograph "Crystal-5000.2" with a flame ionization detector. The quantitative determination of the total HC content was conducted by the method of absolute calibration of the FID using a mixture of HCs prepared by the gravimetric method. Chromatec Analytic 3.0 software was used to process the results. It has been found that the total amount of HCs in the bottom sediments of the Northeastern Kara Sea ranged from 25.8 to 152.4 mg/kg, being 68.21±7.76 mg/kg on average. Based on analysis of the chromatograms, the predominance of high-molecular fractions has been identified; the maximum distribution of n-alkanes was represented by homologous compounds n-C25–C29, which are the markers of allochthonous organic matter. After comparison with the calculated diagnostic indices (CPI1, CPI2, ACL, LWH/HWH, TAR, C31/C29, Paq, TMD, ΣC25–35/ΣC15–21, Pr/Ph), it was found that the increased concentrations of HCs mainly result from the natural processes and prevalence of allochthonous organic matter in bottom sediments.
-
Macrophytes of the genus Potamogeton as the bioindicators for the accumulation of heavy metalsВодные биоресурсы и среда обитанияThis work presents the investigation of the content of some heavy metals in the pondweeds of the Lower Volga River Delta within the area of Astrakhan State Biosphere Reserve. Higher aquatic plants extract chemical elements both from bottom sediments and water column. Moreover, the macrophytes, namely the representatives of Potamogeton genus, are capable of extraction and accumulation of the metals dissolved in the water, contained in the suspended colloidal particles, and present on the surface of leaves. This work is aimed at the identification of species-specific features of the typical hydatophytes (aquatic plants of Potamogeton genus) pertaining to the accumulation of heavy metals. The content of chemical elements in the investigated specimens has been identified using atomic absorption spectrometry; the results have been processed with statistical methods. It has been found that all investigated plant species accumulate iron and manganese in the highest quantities and cobalt and cadmium in the lowest. The investigated pondweed species have shown species-specific properties in the accumulation of chemical elements. Potamogeton crispus and Potamogeton lucens are found to be iron concentrating species. Potamogeton lucens also accumulates nickel, iron and manganese, and Potamogeton pectinatus accumulates chrome, cobalt and lead.
-
Scientific, Technical and Economic Committee for Fisheries (STECF), Evaluation of economic indicators and closure areas in the western Mediterranean. (STECF-23-01).Commission Decision of 25 February 2016 setting up a Scientific, Technical and Economic Committee for Fisheries, C(2016) 1084, OJ C 74, 26.2.2016, p. 4–10. The Commission may consult the group on any matter relating to marine and fisheries biology, fishing gear technology, fisheries economics, fisheries governance, ecosystem effects of fisheries, aquaculture or similar disciplines. This report is the 10th of a suite of STECF EWG reports dedicated to the evaluation of the implementation of the Western Mediterranean Sea Multi-Annual management Plan (hereafter, MAP), following EWG reports 18-09, 18-13, 19-01, 19-14, 20-13, 21-01, 21- 13, 22-01 and 22-11. The group was requested to continue the development of socio-economic indicators to be used in the evaluation of management measures for the West Med MAP in both West Med management units (EMU1 and EMU 1) (TOR1). Two roadmaps were discussed, a short term approach and a long term approach which would consider the expansion of all the mixed-fisheries bio-economic models to both management units. As a first step, the group focused on the proposal of harmonizing the economic indicators across the models implemented (TOR2). The group was than requested to further develop the approach implemented during EWG 22-01 to identify persistence hotspots of the six target species of the West Med MAP using scientific survey data (MEDITS) in combination to commercial spatial data (VMS joined with logbooks), to test existing and additional closure areas (TOR 3). The group was also requested to revise Article 8 of the 2023 fishing opportunities for the West Med MAP (COUNCIL REGULATION (EU) 2023/195), which lists the compensation mechanisms that MSs can implement within the West Med MAP to obtain additional fishing days in 2023 (TOR 4). For TOR 1 a roadmap was discussed and proposed on how to organise the work on socio-economic assessments for the West Med MAP in 2023. The EWG suggests that here should be a three-step process: a scoping exercise (done with EWG 23- 01), a meeting with stakeholders in the middle of the year to discuss their perception of the socio-economic consequences of measures of the West Med MAP and the running of scenarios during EWG 23-11 with results from socio-economic assessments. The EWG notes that the modellers have only the five-day meeting in September to run scenarios. Therefore, it would be crucial for the success of the assessments that the 6 scenarios provided by DG Mare for the EWG 22-11 and with some adjustments for EWG 23-01 will not change for EWG 23-11. It is crucial because those scenarios are already implemented in the models and the implementation of new scenarios would take a lot of time. The EWG proposes to run a few additional scenarios with only one measures to separate impacts of certain measures from the six scenarios where a mixture of measures is included. This would hopefully allow to give an indication what additional efforts may be necessary to reach MSY (in 2025 but also beyond in case the objective is not reached by 2025) and when gains from the implementation of the West Med Plan could be expected. The EWG observes that modelers need to put in additional effort and resources to improve the models for an improved assessment of the West Med MAP. The models were not originally developed for the assessment of the West Med MAP and only cover parts of the area of the Western Mediterranean. Such an improvement of the models could also include work to provide longer-term socio-economic assessments of measures where modelers need to take additional assumptions into account. The EWG notes that it would be beneficial if modelers receive a basic list of assumptions for key economic variables before the EWG 23-11 meeting in September. In 2022, for example, the increased fuel costs were an important factor regarding the economic performance of the fleets. In 2023 fuel costs have decreased but there are other cost categories with a substantial increase. The EWG concludes that DG Mare should not change the 6 provided scenarios substantially before the EWG 23-11 meeting in September. This would allow the modelers to run the models during the meeting and provide the socio-economic results. The EWG concludes that STECF and DG Mare should further discuss how resources could be provided to modelers to improve the applied models. The EWG concludes that the chairs of EWG 23-01 and 23-11 will provide a list of assumptions for the implementation of the models regarding key variables for the socio-economic assessments (short- and long-term). For TOR 2 the EWG discussed what variables and indicators the applied models include and provide. From that discussion a list of indicators was developed for which modelers will be able to provide results in the EWG 23-11 report. The EWG concludes that a list of indicators is provided for which EWG 23-11 will present results in autumn 2023. For TOR 3 the EWG notes that new closure areas for 2023 were implemented only by Spain (EMU 1) (Orden APA/80/2023). All closures areas implemented under the West Med MAP are described to allow testing if their implementation would reduce the catches of juveniles and adults of the six target species of the MAP by 15-25%. The EWG notes that the methodology followed to prioritise, developing and updating closure areas based on their conservation value on the basis of existing closures, proposed closures from EWG 22-01 and new proposals developed by EWG 23-01 based on updated MEDISEH layers is similar to the one used during EWG 22- 01. Updated MEDISEH layers were used for priority species (ARA, MUT and HKE) in combination with old MEDISEH layers for other species and distribution maps of commercial effort from EWG 22-01. Calculation of the percentage of the trawlable GSA area closed to fishing is higher in EMU 1 than EMU 2, therefore the estimation of additional closure areas on top of the existing ones foccused on this management unit. Additional closure areas to test were based on persistence hotsposts from survey data and from areas of high effort in order to impact directly on the reduction of fishing mortality. The EWG notes that the exisiting and additional closures could be tested only in EMU 2 and GSA 7 as for GSA 1, 5 and 6 the extension of the spatially-explicit model ISIS-Fish is not complete yet and it is still limited to a single species (HKE). The EWG notes that closure areas in GSA 7 were tested with two different methods. A static method comparing effort distribution data before and after the closures implementation in 2020, and a dynamic method applying ISIS-Fish. The first method showed how the establishment of the spatio-temporal closure imposed a strong seasonal constraint to the fishing effort in the Gulf of Lions, and that the fishermen community responded quite well to the new rule, although vessels increased their fishing effort along the closure border, with a typical « fishing the line » pattern, especially in the fall. The second model showed that introducing an additional closure did not improve the rebuilding of the hake stock, while changing the closures from seasonal to permanent suggested the strongest effect. The EWG notes that in EMU 2 that temporal closures for the whole fleet reduce global effort while additional spatial closures increase effort towards coastal areas (depths <200m) specifically for fleet segments <18m. Fishing mortality instead is reduced for all species by the introducion of additional closures, specifically those targeting high effort areas, although Fmsy is reached only for ARS and DPS and for already underexploited stocks (MUT 10 and NEP). The EWG concludes that provided that the area in GSA 7 have been chosen according to juvenile hake catch, we can expect that, given the strong observed response of the fishermen community, the closure in GSA7 has the potential to positvely impact the hake recruitment in the long run. Still, two years of implementation remains a short time-scale to observe strong changes in a long- lived stock. More time, observations and analysis will be necessary in the future to further quantify the efficiency of these closures. The EWG concludes that no positive effects on the stocks biomasses are observed in EMU 2 indipendently of the scenarios applied. For TOR 4, the EWG notes that both definitions of “juveniles” and “spawners” are not clearly stated in the Regulation (95/2023) making a bit challenging the evaluation of the criterions. A similar consideration could be done for the term “catch reduction” which is never specified whether it should be considered in number or weight. The EWG could not fully understand if the compliance with the criterions in term of results achieved would be evaluated at some point in the process. The EWG reports that for point a) the literature suggests that the requested threshold of at least 25% of reduction in hake juveniles seems not achievable. For point b) only for Blue and red shrimps the introduction of a 50mm square mesh size seems to lead to the decrease of specimens below 25mm CL at least of 25%. However, for vessels targeting Blue and red shrimps in EMU2, this is a mixed fisheries targeting also Giant red shrimp and it is not applicable to have two different size thresholds for the two species. The EWG suggested that the criterion should be revised providing just one size threshold, ideally selecting the one proposed for blue and red shrimps. According to the IMPLEMED results the same conclusion of point a) can be shared with point c) when a grid of 20mm space bar is used. For point d) EWG cannot find any clear evidence or results which corroborate the fact that specific closures could lead to a reduction in juveniles and spawners at the level requested by the criterion. Point e) refers to an increase of the MCRS for hake (26cm TL) which if not linked with some additional technical measures should just lead to an increase of discards of hake and, likely, black market. For point f), the EWG agreed the temporal closures implemented by Spain and France under the West Med MAP are following the criterion. The EWG concludes that considering the available knowledge and the analysis done during the meeting only the requests based on point b) and point f) could be considered fully in compliance with what the criterion stated, for point d) there weren’t enough information to be fully evaluated if it is feasible or not while the others criterion seems to be not corroborated by the available literature.
-
Scientific, Technical and Economic Committee for Fisheries (STECF) - Evaluation of Joint Recommendations on the landing obligation and on Technical Measures Regulation (STECF-23-04 & 23-06)Commission Decision of 25 February 2016 setting up a Scientific, Technical and Economic Committee for Fisheries, C(2016) 1084, OJ C 74, 26.2.2016, p. 4–10. The Commission may consult the group on any matter relating to marine and fisheries biology, fishing gear technology, fisheries economics, fisheries governance, ecosystem effects of fisheries, aquaculture or similar disciplines. This report contains a review of Joint Recommendations submitted by Member States Regional Groups for the implementation of the Landing Obligation in 2024 and beyond.
-
Trophic basis of the European anchovy stock development in the Azov SeaВодные биоресурсы и среда обитанияFormation of the European anchovy Engraulis encrasicolus (Linnaeus, 1758) stocks in the Azov Sea depends on the development of zooplankton, which is the main food source for this fish species. Under the conditions of the natural flow regime of the rivers (1937–1951) and the 10.6 ‰ salinity of the sea, native zooplankton species ensured a high food supply for the anchovy, which resulted in relatively large anchovy stocks. During the Azov Sea salinization up to 12.8 ‰ that occurred in the late 60–70s of the last century, the zooplankton species composition changed. Predatory scyphoid jellyfish species—Aurelia aurita and Rhizostoma pulmo—underwent drastic increase in abundance, which led to the reduction in the summer biomass of the zooplankton almost by half. During that period, large stocks of the European anchovy developed less often. In the late 1980s, as a result of the introduction of a predatory ctenophore Mnemiopsis leidyi in the Azov Sea, the summer biomass of the zooplankton decreased further by 2–3 orders of magnitude. During the feeding season of the European anchovy, the areas with high zooplankton productivity disappeared, which resulted in the recurring low stocks of this fish species. At the end of the 1990s, a ctenophore Beroe ovata, feeding on the mnemiopsis, appeared in the Azov Sea. Its invasion led the delayed entry of the mnemiopsis into the sea, which, in turn, ensured the development of a sufficient food supply for the anchovy during its pre-spawning period. However, the main feeding season of the anchovy, just as before the arrival of B. ovata, took place under a shortage of the food supply. In the last few years, another increase in salinity to 15.0 ‰ is observed in the Azov Sea. The Black Sea jellyfishes A. aurita and R. pulmo are actively developing once again and, along with M. leidyi, provide even stronger food competition for the anchovy. During these years, only low-productive generations and low stocks of this fish species have been observed.
-
Retrospective analysis of the fish fauna of the Tom River before the construction of the Krapivinsky ReservoirВодные биоресурсы и среда обитанияThe resumption of design and survey work for the construction of the Krapivinsky Hydroelectric Power Plant on the Tom River has necessitated the assessment of the current state of its fish resources and called for making the prediction of their transformation in the event of the hydroelectric complex being put into operation. In the early 20th century, the Tom River was classified as a salmonid habitat. At that time, such valuable commercial species as the Siberian taimen Hucho taimen, blunt-snouted lenok Brachymystax tumensis, tugun Coregonus tugun, humpback whitefish Coregonus pidschian, Nickolsky’s grayling Thymallus nikolskyi, nelma Stenodus leucichthys nelma, muksun Coregonus muksun, and peled Coregonus peled were permanent residents. Sturgeons, such as the Siberian sturgeon Acipenser baerii and sterlet Acipenser ruthenus, were also abundant. Currently, out of these species, grayling, occasionally taimen and lenok are caught in the Tom River; the common roach Rutilus rutilus, European perch Perca fluviatilis, Siberian dace Leuciscus baicalensis and Eurasian ruffe Gymnocephalus cernuus comprise 95 % of all fish caught. If construction of the Krapivinsky Reservoir on the Tom River is completed and it is put into operation, a deep-water, slow-flowing “lake-type” water body will be created. The river bed will be blocked, so semi-anadromous fish species, many of which are listed in the Red Data Book — such as Siberian sturgeon, sterlet and nelma,—will disappear. A decrease in the abundance of grayling, taimen and lenok, already low in number, should also be expected. These fish species winter in the pits, some of them migrate to the Ob River, so, after passing the spillway, they will not be able to return upstream to the spawning grounds. The abundance of lake and lake-river species is expected to increase, among them the common roach, dace Leuciscus leuciscus, European perch, Prussian carp Carassius gibelio (introduced locally, subsequently self-dispersed), as well as common bleak Alburnus alburnus and sunbleak Leucaspius delineates (accidental invaders). In the future, it is possible to make an attempt to introduce peled to the upper basin of the Krapivinsky Reservoir. There is a prospective threat of the Chinese sleeper Perccottus glenii spreading in the upcoming reservoir, which can severely undermine its fish stocks.
-
Comparative characterization of fish feeds based on the biochemical characteristics of Oncorhynchus mykiss (Walbaum, 1792) blood serumВодные биоресурсы и среда обитанияThe main reasons for the decrease in feeding efficiency are dietary inadequacy and poor quality of the feed, which leads to its suboptimal consumption and accumulation of residue, which, in turn, results in deterioration of the hydrochemical regime. This study presents the comparative analysis of two fish feeds in terms of their safe use for Oncorhynchus mykiss (Walbaum, 1792) feeding and their impact on water quality. The investigation was conducted on the rainbow trout individuals in the recirculating aquaculture system at the Aquaculture Center of the K.G. Razumovsky Moscow State University of Technologies and Management in 2021–2020 and involved the comparison of the feeds CRYSTAL (protein content 42.65 %) produced by Alltech Coppens and Basic PL 45/20 A50 (protein content 45.81 %) produced by BNBC (Belarusian National Biotechnology Corporation). Six test groups were included in the experiment: three groups were fed with Alltech Coppens CRYSTAL and the other three groups were fed with BNBC Basic PL compound feed. The biochemical characteristics of the rainbow trout blood serum have been identified using the blood taken from a caudal vein, and the hydrochemical characteristics of the water have been identified using standard procedures. A distinct relationship between the protein content in Oncorhynchus mykiss blood serum and protein content in the feeds has been found. The hydrochemical characteristics of the water in the recirculating aquaculture system over the course of the experiment remained within the normal range, with exception of iron that had been present before the experiment and did not have an adverse effect on the fish’s health.
-
Development of the technology for salted products derived from barrel jellyfish Rhizostoma pulmo (Macri, 1778)Водные биоресурсы и среда обитанияIncrease in the barrel jellyfish abundance, recently observed in the Azov and Black Sea Fishery Basin, has an adverse effect on the fishery and tourism in the region. Jellyfish consumption is a longstanding tradition for the countries of East and Southeast Asia, where the processing technology for jellyfish is based on the salting involving potassium alum. Jellyfish treatment with potassium alum leads to the accumulation of aluminum in the final product, which poses a threat for the human health. Thus, the research of the jellyfish processing methods excluding the use of aluminum is of utmost importance. This study was aimed at the development of the salting methods for barrel jellyfish Rhizostoma pulmo that would involve using plant-based tanning substances. This article presents processing scheme and technological parameters for the salted products derived from jellyfish. Using tanning substances extracted from oak bark and green tea leaves in the quantity of no less than 0.75 % of the jellyfish brought for salting (in terms of weight) made it possible to obtain the salted product with condensed structure. For a lightly salted product, salting should be conducted in 8–10 % saline solution at the temperature 4±2 °С. Based on the identified technological parameters and the assessment of quality and safety characteristics of the obtained samples of salted jellyfish, specifications and processing instruction for the salted products derived from jellyfish for its further use as a food ingredient in multicomponent recipes have been developed.
-
On the effect of logarithmic transformation of data on estimation of the length at first maturity in fishesВодные биоресурсы и среда обитанияTo characterize fish sexual maturity, such parameter as the length at which 50 % of individuals are sexually mature is widely applied. The conventional practice is to use the fish length values directly, without their preliminary logarithmic transformation. However, based on theoretical considerations, such logarithmic transformation should be expected to improve the quality of approximation of the relationship between the percentage of mature individuals and their length. This study is aimed at the testing of the hypothesis that logarithmic transformation improves the quality of approximation of the data on fish maturity, as well as at the assessment of practicability and expedience of the logarithmic transformation when estimating the length at which 50 % of the individuals are sexually mature. This research is conducted based on the published data. Approximation was carried out using two methods: by the probability integral of a normal distribution and by the logistic function. Following the data analysis involving an original two-level approach, it has been found out that the preliminary logarithmic transformation of the length values statistically significantly improves the quality of approximation. However, this pattern manifests only in the case of analyzing a certain volume of data sets. The difference between the results obtained using transformed and non-transformed length values is not big and, oftentimes, unsubstantial. Nevertheless, in some cases, such a difference is noticeable, which provides a reason to recommend the logarithmic transformation of the fish length values when conducting the analysis. It is also demonstrated that, during the estimation of the length at which 50 % of the individuals are sexually mature, both tested functions are equally suitable for approximation.
-
Use of Artemia salina nauplii as the carrier for probiotic bacteria of Bacillus genus in aquacultureAquatic Bioresources & EnvironmentThis paper presents the results of the investigation of the effect of probiotic preparations based on Bacillus strains on Artemia salina nauplii. The use of live food is a necessary step in cultivation of many fish species, and Artemia nauplii are widely used for this purpose. It is crucial to use probiotics in aquaculture, as they can act as natural antagonists of aquatic pathogens, as well as stimulate fish growth and development. This work aims to study the immobilization of probiotic Bacillus strains on Artemia nauplii in order to develop highly effective feeds with probiotic properties for juvenile fish. Experiments on the introduction of various doses of preparations based on three probiotic strains of Bacillus into the water during the rearing of Artemia salina cysts were carried out. The number of bacteria in the water, as well as on the surface and inside the nauplii, was estimated by plating on nutrient media. It has been established that, despite the fact that brine shrimps do not feed at the orthonauplius stage, when probiotic strains are introduced into the water, bacteria are immobilized on the covers of the crustaceans; the concentration of the introduced Bacillus strains in the wipe samples taken from the nauplii surface is 1 order higher than it is for the planktonic form in the water. The introduction of bacilli at a dose of 0.0017 g/L activated the release of nauplii from cysts by 9–41 % of the control, while increasing the dose to 0.17 g/L led to a decrease in the proportion of hatched crustaceans. Thus, if the correct dosage were identified, it would make it possible to accomplish two important tasks at once: to obtain the live feed with probiotic properties for fish larvae and to increase the yield of nauplii.
-
Oceanographic conditions for autumn migration and fishing of the Black Sea anchovy off the coast of Crimea in 2021Aquatic Bioresources & EnvironmentIn 2019–2022, the Black Sea anchovy (Engraulis encrasicolus ponticus Alexandrov, 1927) was wintering off the western and southern coasts of Crimea, where it was subjected to heavy exploitation by the Russian fishers. The conditions resulting in the active autumn migration of the Black Sea anchovy into Crimean waters are of great scientific and practical concern. This study examines the course of the Black Sea anchovy fishing and the oceanographic conditions for its entry, migration and wintering near the southern coast of the peninsula in November and December 2021. The daily data from the FSBI “Centre of Fishery Monitoring and Communications” have been used, as well as the satellite imagery data sets of the sea surface heights and temperatures from the Copernicus Marine Service information system website. Altimetry data were used in the grid nodes with a resolution of 0.125 degrees, and temperature data were used in the grid nodes with a resolution of 0.05 degrees. Relocation of the Black Sea anchovy to Crimea in mid-November was caused by strengthening of the southeastern currents in the waters to the west of the peninsula, associated with the northern position of the Sevastopol Anticyclonic Vortex, as well as with relatively high sea surface temperatures beyond the shelf zone. In contrast to 2019 and 2020, in November and December 2021, an intense thermodynamic frontal zone of the main Black Sea current was located 15–30 miles offshore to the south of Crimea, which became a natural barrier to further migration of the Black Sea anchovy southwards and determined its distribution on the southern shelf of the Crimean Peninsula. The Black Sea anchovy fishing season in 2021/2022 off the coast of Crimea (as opposed to the previous two fishing seasons) was characterized by its relatively early start and the shift of the fishing operations eastwards to Cape Chauda.
-
New species of freshwater bryozoans Plumatella sibirica (Phylactolaemata), Western Siberia (Russia)Vestnik of MSTUWestern Siberia is the least studied region with respect to the distribution, ecology, and systematic composition of freshwater bryozoans. The collection of material on freshwater bryozoans of the West Siberian Plain was carried out as part of study of the zooperiphyton of the water bodies of the Tyumen region (including the Khanty-Mansiysk and Yamalo-Nenets Autonomous Districts) in 1987–2016. As a result of the collected material analysis, description of a new species of phylactolemic bryozoans (Bryozoa) Plumatella sibirica has been presented. The new species has autozooids in the form of tubules with a rounded cross section. Phlotoblasts are oval, with slightly narrowed poles. Size and surface morphology of flotoblasts and sessoblasts distinguish the species from related species Plumatella repens (Linn?) and P. buschnelli (Wood). The maximum biomass of zooperiphyton in forest-tundra lakes has been noted in communities dominated by large colonies of Plumatella sibirica, where this bryozoan is the absolute dominant. In the course of further studies, a new species of bryozoans Plumatella sibirica may also be found in other regions of Siberia.
