Now showing items 1-20 of 4407

    • Occurrence of sterile North-East Arctic cod individual

      Filina, E. A.; Makeenko, G. A. (2018-06-30)
      Based on histological analysis, cod individuals of older age groups that completely lost their reproductive capacity due to age-related gonads' degeneration have been considered. Such individuals have been found among both females and males. It has been revealed that in the gonads of sterile fish the replacement of gametes with connective tissue is taking place. According to the obtained data, the portion of sterile fish in samples among females of more than 100 cm has reached 2.2 %. The analysed sterile individuals are characterized by the drastically low gonadosomatic index while gepatosomatic index is mostly above the average. The reasons of age related sterility of the Barents Sea cod have not been discovered yet. The main role of age related fish reproductive condition is considered to be linked to hormonal regulation distortion of sexual cycle. Studying the distortion in the cod reproduction resulting in spawning skips or fish sterility is believed to be significant not only in theory, but in practice as well. Mature females' biomass is usually applied as reproductive potential indicator. However, the reproductive disorder leading to spawning skips affects reproductive abilities of the species that should be taken into account while estimating total allowable catches. In order to monitor abundance of sterile individuals of the Barents Sea cod, it has been proposed to add its maturity scale with VII stage for fish without reproductive capacity.
    • Aminoacids composition of muscular tissue of Coregonus lavaretus L. (the Kola Peninsula)

      Mishanina, L. A. (2018-06-30)
      The studies of the protein aminoacid composition and free aminoacids of muscle tissue of different ages of Coregonus lavaretus L. from Lakes Umbozero and Lovozero (the Kola Peninsula) have been presented. The research of aminoacid spectra in separate tissues allows to some extent to evaluate the features of protein metabolism and the physiological state of the organism. Aminoacid composition of proteins has been investigated by high-performance liquid chromatography. Fractional composition of the proteins' solubility has been determined by spectrophotometry. Significant differences in the ratio of bound and free aminoacids of muscle tissue of Coregonus lavaretus L. have been substantiated. It is established that the proteins of the muscle tissue of whitefish from Lake Lovozero have a higher total content of essential aminoacids unlike whitefish from Lake Umbozero. The content of essential aminoacid leucine in the proteins of muscle tissue of whitefish from Lovozero increases significantly, which is associated with an increase in the content of salt-soluble myofibrillar fraction. The content of essential aminoacids valine and isoleucine is significantly lower in Coregonus lavaretus L. of Lake Umbozero compared to Coregonus lavaretus L. of Lake Lovozero. Perhaps the lack of these essential aminoacids will lead to the violation of metabolism in the studied fish from Lake Umbozero. The ratio of alkaline aminoacids to acidic ones in the muscle tissue of whitefish from Lake Umbozero is less than that of whitefish from Lake Lovozero. During whitefish puberty the overall pool of essential free aminoacids decreases, the pool is in inverse proportion to content of protein aminoacids.
    • Morphological development of the digestive system of Atlantic salmon Salmo salar L. in the Umba farm during the endogenous feeding

      Livadina, L. V.; Anokhina, V. S. (2018-06-30)
      The morphological and histological characteristics of the digestive system ontogenesis in hatchery of the Atlantic salmon larvae during the endogenous feeding period have been given. An analysis of a number of articles updating information on modern studies of the digestive system in the early ontogeny of various groups of fish has been carried out. The samples were collected at the Umba hatchery in 2015–2016. The authors have performed morphological and histological analyses of embryos and larvae, histological examination of the digestive system of larvae during the transition to exogenous nutrition, the establishment of biological age at the time of certain events in the ontogenesis of the digestive system. Actual values of the biological age of Umba hatchery larvae, at which they shift to the mixed (580 tau-somite) and exogenous (630 tau-somite) feeding have been determined. The obtained results have been compared with the literature data when development of Atlantic salmon larvae takes place in conditions with controlled temperature. Variation in biological age values, when formation of the digestive system structures takes place, has pointed at the functional and morphological differences in ontogenesis of the Atlantic salmon from natural and artificial water circumstances. Development of the Atlantic salmon larvae after hatching in cold-water conditions (3–4 ?С, the Umba hatchery), sequence of the digestive system structures composition, and establishment of the functional readiness to food assimilation has been shown. In this period the growth rate of larvae has been evaluated. The organs responsible for exogenous feeding have been divided into 3 groups, and analysis of their ontogenesis has been performed. It has been recommended to start exogenous feeding with 15–20 % of yolk in presence, at the biological age of 540 tau-somite, 45–48 days after hatching in our case.
    • Weight growth of different generation of the trout Parasalmo mykiss on Lake Imandra

      Kalinina, N. R.; Anokhina, V. S.; Kravets, P. P.; Tyukina, O. S. (2018-06-30)
      The averaged indicators of the weight growth of four generations of trout at different temperatures in the time interval of the life cycle from the transfer of larvae to cultivation until the fish reaches a portioned commercial weight of 400 g when the first withdrawal of products for sale takes place have been analyzed. It has been shown that fish of different generations passes into the weight category "goods" sequentially, but after reaching different ages, while there is no direct correlation between the terms "generation formation" – "first withdrawal for sale". According to our data the most intensive weight growth of fish has been noted in the temperature range equal to 8–13 °C. An increase in the water temperature in the cages to 15–18 °C has led to a slowdown, and then to the suspension of the accumulation of fish biomass. In cages operating in the area of Kola NPP heated water trout of April generation gains the commercial weight of 400 g in 7–8 months after landing of larvae for cultivation, November trout – after 15 months. Trout of October and January generation reaches commercial weight at 11 and 9 months, respectively. The stretching of timing of biomass accumulation is most pronounced in the autumn generation of trout. It has been found that the greatest increase in weight per unit body (145.1 mg per day) is provided by the trout of the January biological group, the smallest – by the November trout (75.8 mg per day). The energy reserve of heat allowing for differently derived individuals to reach a commodity weight of 400 g, is in the range from 3 320 to 5 300 degree-day.
    • Macroalgae's flora of the Kola Bay (the Barents Sea)

      Malavenda, S. V. (2018-06-30)
      The Kola Bay is the most developed part of the Barents Sea. Benthic phytocenoses of its southern part are well studied, and the Northern ones have almost no modern descriptions. Flora of the Kola Bay has not been revised since the beginning of the XX century. The list of species for the Kola Bay of the Barents Sea has been compiled based on the results of expeditions in 2009–2013. The distribution of species in the areas of the bay has been analyzed. Altogether flora according to our data includes 94 species of algae macrophytes. Species diversity decreases towards the top of the Kola Bay: in the northern knee 87 species have been identified, in the middle one – 75, and in the south – only 24. The largest number of species along one incision has been observed on the island of Toros, at the mouth of the bay, – 51. Kornmannia leptoderma and Saccorhiza dermatodea have been detected as species having conservation status.
    • The inclusion of grothite in the zircon from granitoids of the crystalline basement of the Southern Yamal Peninsula

      Erokhin, Yu. V.; Ivanov, K. S.; Khiller, V. V. (2019)
      Grothite – rare F-Al-rich type of titanite – has been found in accessory zircon from the granitoids of the preJurassic basement of the Verkhnerechensky oil-gas area (in the southern part of the Yamal Peninsula) as a result of the study. Titanite forms rare inclusions (so-called minerals-prisoners) in the central parts of zircon crystals; in our sample of 35 individuals only two grains of titanite have been discovered. The measurement of the chemical composition of the mineral has been carried out on an electron-probe microanalyzer CAMECA SX 100, equipped with five wave spectrometers (IGG UrB RAS, Ekaterinburg). According to the microprobe analysis, the mineral has an unusual chemical composition, it shows the presence of significant concentrations of alumina (Al2O3 to 8.5 wt.%), rare earths elements (REE to 4.3 wt.%), and fluorine (F to 2 wt.%). This grothite is dramatically different in chemical composition from the accessory titanite of the matrix granitoid (monzoleicogranite), which is characterized by values close to the reference sphene. Overall, grothite is an intermediate connection between the two extreme members CaTiSiO4O (titanite) – CaAlSiO4F (synthesized Al-F-titanite), and the Verkhnerechensky mineral content of a hypothetical Al-F-titanite achieves a high level of 24–26 %. Unfortunately, grothite is crystallized in a wide range of temperatures and pressures which does not allow its use in thermodynamic reconstructions. The existence of grothite (or Al-F-titanite) is apparently determined not so much on the PT-conditions of rocks' formation, but most likely on the chemistry of the environment. So it is obvious that the Verkhnerechensky titanite was formed in the melt with an increased concentration of fluorine. It is the first record of grothite in the form of inclusions in accessory zircon.
    • Phytoplankton variables dynamics in the Halda River (Bangabandhu Fisheries Heritage), Chittagong, Bangladesh

      Islam, Md.S. (2021)
      The Halda is a river ecosystem of major importance, well-suited for the natural spawning of major carps due to the unique physicochemical and biological properties of its water. The productivity of the Halda ecosystem mainly depends on the plankton density. The present study has been aimed at the determination of qualitative and quantitative density of the phytoplankton in the Halda River during a two-year period extending from January, 2017 to December, 2018. Phytoplankton density is a good indicator of the water quality of a river ecosystem. A total of 74 species of phytoplankton divided into 47 genera belonging to 6 phyla has been recorded. Bacillariophyta was the most dominant phylum of phytoplankton followed by Cyanobacteria, Chlorophyta, Miozoa, Charophyta, and Euglenozoa. The maximum phytoplankton density was recorded during the pre-monsoon period, and its minimum fell upon the post-monsoon period. The phytoplankton showed a positive significant relationship with transparency, total dissolved solids, conductivity, calcium, total hardness, and BOD5 and an inverse significant relationship with water temperature. The water of the Halda River is organically polluted and eutrophic in its nature.
    • Водные биоресурсы и среда обитания. Том 4, вып. 2

      Bragina, T.M. (Azov-Black Sea Branch of the FSBSI “VNIRO” (“AZNIIRKH”)Rostov-on-Don, Russia, 2021)
      Chlorophyll-α in the Azov Sea has been studied according to the data of remote sensing of the Earth collected in 2006–2019. Biology and spatial distribution of roach Rutilus rutilus heckelii and common bream Abramis brama juveniles in the Don River have been characterized for the period of 2020. Abiotic environmental factors in classification of the water from energy facilities have been investigated for aquaculture purposes. Reproduction results of the semi-anadromous fish species at the floodplain spawning and rearing farms (hatcheries) of the Azov Sea and Kuban River region have been summarized for 2020. Preservation techniques for zostera (eelgrass) washed ashore as storm debris are described. Long-term dynamics of the bream stocks in the Azov Sea (Russian waters) has been tracked based on the results of CMSY modeling under the conditions of limited data availability (2002–2020). Possibilities of the short-term forecast of the catch of the European sprat from the Black Sea stock off the western coast of Crimea are suggested.
    • Book Abstract "Physiological and genetic aspects of so-iuy mullet Planiliza haematocheila (Temminck & Schlegel, 1845) biology in the Azov and Black Sea Basin"

      Azov-Black Sea Branch of VNIRO (2021)
      This work characterizes the physiological status of so-iuy mullet Planiliza haematocheila (Temminck & Schlegel, 1945) upon formation of its broodstock at the beginning of its acclimatization (1979–1983) in the Azov and Black Sea Basin. Following the results of a long-term investigation, age-length, seasonal, and annual dynamics of physiological parameters have been identifi ed, as well as specifi c features of so-iuy mullet metabolism and reproduction.
    • Possibilities of short-term forecasting of the catch of the European sprat from the Black Sea stock off the western coast of Crimea

      Panov, B.N.; Spiridonova, E.O. (2021)
      This research work presents the results of the analysis of the data collected during the multimethod monitoring of the European sprat fishing (the Black Sea stock) off the western coast of Crimea in July–September, 2019. The monitoring was aimed at identification of a relationship between the behavior of biological resources and their environmental conditions with the purpose of developing the methods of short-term forecasting of fishing efficiency. Graphical and correlation analysis of the daily data on vessel catches and sea surface temperature, as well as satellite altimetry data and characteristics of atmospheric transfers in the fishing area made it possible to suggest an environmental mechanism for the formation of commercial sprat aggregations in the investigated area. During its summer feeding in the coastal waters, sprat forms denser aggregations under the influence of synoptic anticyclonic vortices that develop near the shelf. Intensification of those aggregations is associated with an increase in the western atmospheric transfers in this region. Southern currents, uncharacteristic for the investigated area, and a decrease in the temperature of surface waters in the coastal zone indicate escalation of the stable impact of anticyclonic vortices on the coastal waters. The presence of statistically significant anticipatory relationships between average daily fishing pressure and abiotic factors holds a promise for the possibility of short-term forecasting of the sprat fishing efficiency off the western coast of Crimea in the summer season with the forecast interval equaling 1–7 days.
    • Long-term dynamics of the bream stocks in the Azov Sea (Russian waters) based on the results of CMSY modeling under the conditions of limited data availability (2002–2020)

      Cherednikov, S.Yu.; Piatinskii, M.M.; Kozobrod, I.D. (2021)
      Analytical assessment of the Azov Sea stock of the common bream Abramis brama (Linnaeus, 1758) for the time range 2002–2020 has been performed using CMSY trend model in R that is suitable for application in the context of limited data availability. Current state of the stock is at the level of the reference point based on stock biomass, and shows evidence of substantial overexploitation (B2020/BMSY=0.989; F2020/FMSY=1.82). Accounting for the volumes of IUU-fishing using indirect estimates increases comprehensiveness of the results and ensures adequate stock assessment and evaluation of fishing mortality. Pooled estimates of bream stock biomass for the investigated period indicate a collapse of population abundance that fell upon 2005–2013 and, presumably, stemmed from climatic and hydrochemical changes in the Azov Sea environment, not being associated with overexploitation of the population in those years. At present, the bream population still remains in depressed state, with prerequisites for stock recovery. Following the results of modeling and after a consideration of forecast scenarios, the size of recommended legal catch for 2022–2023 could be set within the range between 40 and 110 t, depending on the efficiency of control, accounting, prevention and suppression of IUU-fishing. So long as the population is exploited within these limits, stock biomass will remain at a safe level and has the possibility of reaching 950 t. The results of this investigation highlight the necessity of control and prevention of bream IUU-fishing in the Azov Sea and Don River Basins; this is a crucial factor influencing bream population in the recent years.
    • Preservation techniques for zostera (eelgrass) washed ashore as storm debris

      Bogomolova, V.V.; Belyakova, I.A.; Esina, L.M.; Chernyavskaya, S.L.; Krivonos, O.N. (2021)
      The results of organoleptic evaluation of seagrass Zostera marina (eelgrass) storm debris are presented. The chemical composition of Zostera during its mass aggregation along the wrack line of the Black Sea coast in the spring and summer seasons of 2020 has been investigated. The safety of Zostera storm debris for consumption has been evaluated based on such indicators as content of radionuclides and toxic elements, and microbiological characteristics. Preservation of the storm debris samples has been conducted using the following techniques: drying under natural conditions (average daily air temperature 19–25 °С, wind velocity 5–8 m/s, atmospheric humidity 56.5–80.0 %, height of a storm debris layer 5–10 cm), artificial drying (forced ventilation at 40±2 °С, layer height 5–10 cm), and salting (using dry method with addition of table salt in the amount equal to 20 % of the weight of macrophytes). Organoleptic properties of dried and salted eelgrass under various storage times are described. It has been established that the eelgrass, inhabiting the Azov and Black Sea Fishery Basin and washed ashore, contains from 16.9 to 25.7 % pectic substances, which indicates high value of this macrophyte. A method of preservation does not severely affect the content of pectic substances. Recommendations on eelgrass preservation by means of drying (both under natural and controlled conditions) and salting have been given to ensure the highest possible retention of its quality.
    • Reproduction results of the semi-anadromous fish species at the floodplain spawning and rearing farms (hatcheries) of the Azov Sea and Kuban River region in 2020

      Khorosheltseva, V.N.; Gorbenko, E.V.; Poluyan, A.Ya.; Medvedeva, A.A.; Voloshina, M.V. (2021)
      Long-term observations over floodplain spawning grounds reveal the decrease in reproductive efficiency of zander (pike-perch) (Sander lucioperca, Linnaeus, 1758) and roach (Rutilus rutilus heckelii, Nordmann, 1840), resulting from deterioration of hydrological and hydrochemical regimes. Due to its low water content, the year of 2020 has been recorded as most unfavorable for the reproduction of semi-anadromous fish species. This article considers the results of 2020 spawning migration at the spawning and rearing farms of a floodplain type (Beysug Hatchery and Yeysk Experimenal Hatchery). In the spring season of 2020, these two farms reached planned stocking amount of breeders. The best age, length and weigh characteristics were exhibited by the roach breeders entering the water bodies of Yeysk Experimenal Hatchery for spawning. At Beysug Hatchery, the quality of breeders belonging to the semi-anadromous fish species was at its average long-term level. Despite substantial entry of breeders to the water bodies of Yeysk Experimental Hatchery, abundance of the roach juveniles migrating down to the Azov Sea was almost 9 times lower than average long-term values, and for zander juveniles this value was 3 times lower. In Beysug Hatchery, due to low water content, abundance of zander juveniles during their downward migration was 22 times lower (in a long-term context).
    • Abiotic environmental factors in classification of the water from energy facilities for aquaculture purposes

      Kalayda, M.L.; Gordeeva, M.E. (2021)
      This article proposes a water classification that is based on the means and practices of water supply to energy facilities with regard to the temperature parameter and accounting for the prospective possibility of using such water for the purposes of aquaculture. This water classification relies on physicochemical characteristics of water: temperature, pH, dissolved oxygen concentration, redox potential, and total antioxidant activity. The collection of the data on the actual status of abiotic environmental factors was conducted at natural water bodies, including the ones used for cooling purposes by the energy facilities of the Republic of Tatarstan, from 2010 to the present time. Based on the temperature parameter, three water classes have been distinguished: 1) with the physicochemical characteristics typical for a water body of that geographical location; 2) water of the water bodies used for cooling purposes by energy facilities with the presence of zones of increased temperatures; 3) water of cooling ponds. This investigation has revealed that the waters are characterized by a complex structure involving different sets of physicochemical characteristics. It is shown that three distinguished water classes are characterized by certain sets of values of the Water Structure Index (5–7, 2.7–3.2, and 9–16, respectively) and redox potential (in the range of 2.47 unitsEh, 2 unitsEh, and 3.43–4.5 unitsEh, respectively). For these classes the following types of uses in aquaculture are most applicable: 1) cultivation of fish species native for this fish farming area; 2) cage farms, including the ones with multiple cycles of production; 3) cultivation of phytovorous fish species in the overgrown and blooming environment.
    • Biological characterization and spatial distribution of roach Rutilus rutilus heckelii and common bream Abramis brama juveniles in the Don River in 2020

      Piatinskii, M.M.; Kozobrod, I.D.; Cherednikov, S.Yu.; Zherdev, N.A. (2021)
      The data collected during the scientific monitoring of the spawning run of roach Rutilus rutilus heckelii and common bream Abramis brama in the Don River have been analyzed. Investigation of the biological characteristics, spatial distribution and specific features of the downward migration of fish juveniles was carried out in the Lower Don area stretching from Romanovskaya Settlement to the Don River Delta in May–October, 2020. The obtained results show significant gain in average length and weight of roach and bream juveniles in the spring – summer season of 2020 and its absence in the summer – autumn season, which was caused by the downward migration of the partially grown juveniles in the Taganrog Bay. Hauls of fry drag nets showed that the juveniles in the investigated water bodies kept to the shallow coastal waters. Quantitative assessment of the spatial distribution of juveniles indicates spatial heterogeneity of their aggregations and moderately productive spawning run in the context of low water content in 2020. Based on the outcomes of the scientific monitoring, the abundance of roach juveniles was assessed to be 49.3 million ind., and for bream juveniles it equaled 30.4 million ind. In the future, the research results factoring in statistical processing will make it possible to analyze the long-term dynamics of the biological characteristics of roach and bream juveniles.
    • Assessment of water quality in small rivers of the Seversky Donets and the Tuzlov River Basins using biotic indices

      Bakaeva, E.N.; Taradayko, M.N. (2021)
      The restructuring of the coal mining industry, which began in the 1990s, has impacted the environmental situation in Eastern Donbass within Rostov Region rather adversely. Aquatic ecosystems of rivers with low water content and, consequently, low dilution capacity are characterized by high susceptibility to anthropogenic impact. Samples of macrozoobenthos were taken in the areas with different anthropogenic load in 18 sections of small rivers of the Seversky Donets and Tuzlov River Basins: the upper reaches, the places downstream of mine drainage water outlets, and mouths. Based on a comparison of the values of the Woodiwiss, Parele, Goodnight–Whitley, and Mayer biotic indices, sections with different levels of water pollution have been identified in these three areas. Water was characterized as “clean” in 47 % of the sections according to the Goodnight–Whitley index, and in 27 % according to the Parele index. The greatest overlap in the estimation of water pollution level according to these indices was in the “polluted” category. Altogether 62 % of the river mouth waters, 50 % of the sections located downstream of mine drainage water outlets, and 17 % of the upper reaches are attributed to this level of pollution. According to all water indices, most of the sections are classified as “polluted”, although there is a difference. Thus, 94 % of the sections were “polluted” according to the Mayer index, 89 % of them according to the Woodiwiss index, 47 % according to the Parele index, and only 33 % of the sections were identified as “polluted” according to the Goodnight–Whitley index. The discrepancy in estimation of water pollution by biotic indices has been found in five cases out of eighteen investigated stations. The final score has been assigned according to the index with the most negative result. For Eastern Donbass area, taking into consideration the class of small rivers, their zoological and geographical characteristics, the consequences of restructuring the coal mining industry, and agricultural nature of this region, biotic indices should be considered as indicators of organic water pollution along with the abundance, biomass, and number of the macrozoobenthos taxa.
    • Chlorophyll-a in the Azov Sea according to the data of remote sensing of the Earth in 2006–2019

      Kochergin, А.T.; Kriskevich, L.V. (2021)
      Based on satellite images of the sea surface, chlorophyll-α content in different areas of the Azov Sea in 2006–2019 has been estimated for several timeframes: its minimum, spring and summer–autumn peaks. The areas and timelines of the main pronounced and secondary peaks of chlorophyll concentration, its decline and the lowest point of its development are presented. During the investigated period, chlorophyll-α concentrations in the context of the spring population explosion were predominantly lower than 20 mg/m3, except for the central part of the sea and its eastern areas, where, in certain years, the content of this pigment reached 50 mg/m3. Particularly low concentrations of chlorophyll-α in spring were observed after 2013; they did not exceed the value of 16.5 mg/m3 in any area. A pronounced spring explosion mainly fell upon April and May, with its secondary weaker case in January – March, especially in the eastern and southeastern parts of the sea through the recent decade. The summer–autumn peak of chlorophyll-α content was characterized by increased concentrations: up to 40–50 mg/m3 in the northern, central and eastern parts of the sea until 2014, and up to 20 mg/m3 throughout the entire area since then. The summer–spring peak of chlorophyll-α concentration stretches predominately from June to September, and there exists the second peak in some areas. Second peak is less pronounced and falls upon October – December. In the course of the observation period, the minimum of chlorophyll-α content was decreasing from 10.0 to 4.0 mg/m3 throughout the entire sea area. The minimum was recorded mostly during the following months: October – February for the western parts of the sea, and November – March for the central and eastern parts. It is possible that the negative trend in chlorophyll-α content could be induced by salinization and changes in the biotic structure of the sea.
    • Ertrags- und Einnahmeverluste bei Dorsch, Hering und Sprotte durch Unterfischung von Dorsch in der östlichen Ostsee.

      Bethke, Eckhard (Eckhard BethkeWendel, Germany, 2019)
      Kurzfassung: Aus dem aktuellen WGBFAS-Bericht des ICES geht hervor, dass Nahrungsmangel in der östlichen Ostsee Kümmerwachstum und damit einen Verlust an Produktivität bei Dorsch verursacht. Dieser Zustand, zunächst unbemerkt, verschlimmert sich seit etwa 30 Jahren. Hungernde Bestände müssen unbedingt vermieden werden, denn, nur der über den Grundbedarf hinausgehende Anteil der assimilierten Nahrung, wird für das Wachstum eingesetzt. Eine Reduktion der Bestandsgröße ist erforderlich! Der Internationale Rat für Meeresforschung (ICES) hat jedoch die Schließung der Fischerei auf Dorsch empfohlen. Betrachten wir die Fischerei durch die Brille der Aquakultur, stellen wir fest, dass diese Empfehlung kritisch hinterfragt werden muss. Nutzt man den „gemästeten“ Dorschbestand nicht ausreichend, werden mögliche Erträge ebenfalls nicht realisiert. Zusätzlich zu diesem Verlust verliert man das zur Mast eingesetzte Futter. Denn, als Alternative zur Dorschmast wären Erträge aus der Fischerei auf Hering und Sprotten möglich. Im Gegensatz dazu verursacht die Überfischung des Dorschbestandes zwar Ertragseinbußen, eröffnet aber gleichzeitig erweiterte Fangmöglichkeiten auf die Futterfischbestände. Die Überarbeitung der verwendeten Bestandsmodelle und die Hinwendung vom Einartenansatz über den Ökosystemansatz, hin zu Ansätzen, die Ökonomie und Ökologie vereinen, sind notwendig. Vergleicht man die Futterkosten mit den späteren Erlösen wird klar, dass bei der Mast von Dorsch über einer Körpermasse von etwa 1 kg mehr Geld in der alternativen Futterfisch-Fischerei verloren wird, als bei der Fischerei auf Dorsch gewonnen wird. Ein reflexartig geforderter Bestandsschutz verursachte in den vergangenen Jahrzehnten geringe Wachstumsraten bei Dorsch durch Unterfischung in der östlichen Ostsee und damit einen Rückgang der Produktivität auch bei anderen Arten. Man kann keine ertragreiche Fischerei auf Dorsch, Hering und Sprotten erwarten, wenn man einen hungernden Dorschbestand duldet. Um nun aber größere Dorsche fangen zu können, muss die Zahl der Rekruten ausreichend gering sein. Wir wissen es aus unserem Kleingarten. Wenn wir die Radieschenreihen nicht ausdünnen, können wir nur kleine Radieschen ernten. Das Gleiche gilt für den Kabeljau in der Ostsee. Wenn wir die Zahl der Rekruten nicht frühzeitig reduzieren, werden wir immer kleinen Kabeljau zu unattraktiven Preisen fangen.You can find the English version of the manuscript here: https://ssrn.com/abstract=3419758Abstract: The latest ICES WGBFAS report shows that food shortages in the eastern Baltic Sea are causing poor growth and thus a loss of cod productivity. This situation, initially unnoticed, has been worsening for about 30 years. It is essential to avoid starving stocks, because only the part of assimilated food that exceeds basic needs is used for growth. A reduction of the stock size is necessary! However, the International Council for the Exploration of the Sea (ICES) has recommended the closure of the cod fishery. If we look at fishing through the eyes of aquaculture, we see that this recommendation must be questioned critically. If the "fattened" cod stock is not used sufficiently, potential yields will not be realised either. In addition to this loss, the feed used for fattening is also lost. Because, as an alternative to cod fattening, yields from fishing for herring and sprat would be possible. In contrast, overfishing of the cod stock may result in a loss of yield, but at the same time it opens up greater fishing opportunities for forage fish stocks. A revision of the stock models used and a shift from the one-species approach via the ecosystem approach to approaches that combine economy and ecology are necessary. If one compares the feed costs with the later revenues, it becomes clear that when fattening cod beyond a body mass of about 1 kg more money is lost in the alternative forage-fish fishery than is gained when fishing for cod. A reflex-like demand for stock protection has caused low growth rates for cod in recent decades due to underfishing in the eastern Baltic Sea and thus a decline in productivity for other species as well. You cannot expect high-yield fishing for cod, herring and sprat if you tolerate a starving cod population. In order to catch larger cod, however, the number of recruits must be sufficiently low. We know this from our allotment garden. If we don't thin out the rows of radishes, we can only harvest small radishes. The same applies to cod in the Baltic Sea. If we do not reduce the number of recruits beforehand, we will always catch small cod at unattractive prices.
    • Hydrographic-hydrochemical assessment of the Baltic Sea 2017

      Naumann, Michael; Umlauf, Lars; Mohrholz, Volker; Kuss, Joachim; Siegel, Herbert; Waniek, Joanna J.; Schulz-Bull, Detlef E. (Leibniz-Institut für Ostseeforschung WarnemündeRostock, Germany, 2018)
      ENGLISH ABSTRACT: The article summarizes the hydrographic-hydrochemical conditions in the western and central Baltic Sea in 2017. Based on meteorological conditions, the horizontal and vertical distribution of temperature, salinity, oxygen/hydrogen sulphide and nutrients are described on a seasonal scale. For the southern Baltic Sea area, the “cold sum” of the air temperature of 31.7 Kd in Warnemünde amounted to a mild winter in 2014/15 and ranks as 15th warmest winter since the beginning of the record in 1948. The summer “heat sum” of 159.5 Kd ranks on 28th position of the warmest summers over the past 70 years and is slightly above the long-term average of 153.4 Kd. Based on satellite derived Sea Surface Temperature (SST) 2017 was the eleventh-warmest year since 1990 and with 0.24 K slightly above the long-term SST average. March, April and October - December contributed to the average by their positive anomalies. July and August were characterized by negative anomalies. The anomalies reached maximum values of +2 K and -3 K. The situation in the deep basins of the Baltic Sea was mainly coined by beginning stagnation at bottom-near water depths of the eastern Gotland Basin and ongoing ventilation of the upper part 5 of the deep-water above 150 m as a consequence of weak inflows. For the first time within this phase of intensified inflow activity, starting in 2014, the ventilation of the Farö Deep at the Northern Central Basin was registered at the beginning of the year. In the course of 2017 two weak inflows showing total volumes of 210 km^³ (February) and 188 km^³ (October) were registered. In conclusion, the impact of the observed phase of intensified water exchange processes with subsequent consequences for the biogeochemical cycles is weakening.GERMAN ABSTRACT: Die Arbeit beschreibt die hydrographisch-hydrochemischen Bedingungen in der westlichen und zentralen Ostsee für das Jahr 2017. Basierend auf den meteorologischen Verhältnissen werden die horizontalen und vertikalen Verteilungsmuster von Temperatur, Salzgehalt, Sauerstoff/ Schwefelwasserstoff und Nährstoffen mit saisonaler Auflösung dargestellt. Für den südlichen Ostseeraum ergab sich eine Kältesumme der Lufttemperatur an der Station Warnemünde von 31,7 Kd. Im Vergleich belegt der Winter 2016/17 den 15. Platz der wärmsten Winter seit Beginn der Aufzeichnungen im Jahr 1948 und wird als mild klassifiziert. Mit einer Wärmesumme von 159,5 Kd rangiert der Sommer im Mittelfeld der 70jährigen Datenreihe und reiht sich auf Platz 28 der wärmsten Sommer ein. Das Langzeitmittel liegt bei 153,4 Kd. Auf der Grundlage von satellitengestützten Meeresoberflächentemperaturen (SST) war 2017 das elft- wärmste Jahr seit 1990 und mit 0,24 K etwas über dem langfristigen SST-Mittel. März, April und Oktober - Dezember trugen durch ihre positiven Anomalien zum Durchschnitt bei. Juli und August waren durch negative Anomalien gekennzeichnet. Die Anomalien erreichten Höchstwerte von +2 K und -3 K. Die Situation in den Tiefenbecken der Ostsee war im Wesentlichen geprägt durch bodennah einsetzende Stagnation im östlichen Gotland Becken und Belüftung der mittleren Wassersäule oberhalb 150 m im Zuge kleinerer Einströme. Zu Jahresbeginn wurde das im nördlichen Zentralbecken gelegene Farö Tief erstmals innerhalb der aktuellen Einstromphase belüftet. Im Jahresverlauf 2017 wurden zwei weitere schwache Einströme mit Volumina zwischen 210 km³ und 188 km³ im Februar sowie Oktober registriert. Zusammenfassend kann gesagt werden, dass die Auswirkungen der seit 2014 beobachten Phase von verstärkten Wasseraustauschprozessen mit entsprechenden Konsequenzen für die biogeochemischen Kreisläufe abklingen.
    • World Ocean Review: Living with the oceans

      Bollmann, Moritz; et, al (Maribus GmbHHamburg, Germany, 2010)