scholarly journals INTERSPECIFIC NUTRITIONAL RELATIONSHIP BETWEEN CLUPEONELLA ENGRAULIFORMIS AND CLUPEONELLA CASPIA IN THE CASPIAN SEA

2019 ◽  
pp. 13-19
Author(s):  
Anna Viktorovna Mikhajlova
Keyword(s):  
Fish Species ◽  
Caspian Sea ◽  
Food Preferences ◽  
Pelagic Fish ◽  
Middle Part ◽  
Aqueous Environment ◽  
The Caspian Sea ◽  
Commercial Fish ◽  
The North ◽  
Close Relationship

Vital activity of the Caspian ichthyofauna is mainly determined by aqueous environment with its multiple factors influencing the hydrobionts’ life cycle. It is well known that in the process of evaluating the stocks of commercial fish species it is necessary to take into account supplying them with food. Trophologic studies of mature species of Clupeonella Caspia and Clupeonella Engrauliformis in the Caspian Sea make a basis for a large number of works; however, the research of food preferences of these fish species is scarce. Clupeonella Caspia inhabits the north, middle and south parts of the Caspian Sea above the 60 m isobath. Clupeonella Engrauliformis is widespread in the middle and southern parts of the Caspian Sea above the depths more than 200 m. In the course of evaluating kilka fattening in the Caspian Sea that was continued in 2011 there were estimated nutrition relations of kilka species over the many years, traced the degree of nutritional similarity and registered interspecific relationship between these pelagic fish. The results obtained have been summarized and the whole range of trophic studies has been shown. The monitoring nature of the studies allows to infer the intensive feeding of Clupeonella Caspia and Clupeonella Engrauliformis in the summer of 2011-2014 and in 2016 in the middle part of the Caspian Sea (the study of pelagic fish fatting was not conducted in 2015). The multi-year comparative analysis of Clupeonella Caspia and Clupeonella Engrauliformis nutrition demonstrated the differences of using the dominant foodstuff among planktonic invertebrates. It has been stated that the index of similarity of the food spectrum does not always have a greater degree of coincidence in close relationship of fish in a systematic respect.

THE NUMBER AND QUALITATIVE CHARACTERISTICS OF FRY FISH IN SHALLOW COASTAL WATERS OF THE VOLGA IN THE SUMMER-AUTUMN PERIOD OF 2012

2017 ◽  
pp. 65-73
Author(s):  
Edward Vladimirovich Nikitin
Keyword(s):  
Fish Species ◽  
Coastal Waters ◽  
Caspian Sea ◽  
The Caspian Sea ◽  
Volga River ◽  
Commercial Fish ◽  
Autumn Period ◽  
Fish Juveniles ◽  
Qualitative Characteristics ◽  
Shallow Coastal Waters

Shallow coastal waters of the Volga river is a flooded feeding area for fish juveniles of nonmigratory fish species. There takes place annual downstream migration of fluvial anadromous fish species from spawning grounds of the Volga river to the Northern Caspian Sea. The most important factors determining the number and qualitative characteristics of fry fishes are the level of the Caspian Sea (currently having a tendency to the lowering), hydrological and thermal regimes of the Volga river. Researches were carried out in definite periods of time. In the summer-autumn period of 2012 fry fishes were presented by 19 species (13 of them were commercial species), which belonged to 9 families. The article gives data on all the commercial fish species. In the first decade of July the maximum number of fry fish was registered in the western part of the Volga outfall offshore - in box 247 (19.86 mln specimens/km2), in the eastern part - in box 142 (20.4 mln specimens/km2). The most populous were roach, red-eye, silver bream and bream; size-weight characteristics were better in the areas remoted from the Volga delta. In the third decade of July the quantitative indicators of fry fish on these areas decreased, size-weight characteristics greatly increased. In the second decade of October in the western part of the seaside there were registered increased pre-wintering concentrations of fish juveniles, their qualitative indicators increased, which is evidence to favorable feeding conditions in 2012.

scholarly journals TO THE FAUNA OF BIVALVE MOLLUSCS OF THE DAGESTAN COAST OF THE CASPIAN SEA

2018 ◽  
Vol 13 (2) ◽  
pp. 9-21 ◽  
Author(s):  
Marina V. Khlopkova ◽  
Magomedzagid K. Guseynov ◽  
Kais M. Guseynov ◽  
Aysha Sh. Gasanova
Keyword(s):  
Fish Species ◽  
Caspian Sea ◽  
Food Resource ◽  
Fish Fauna ◽  
Bivalve Mollusks ◽  
The Caspian Sea ◽  
Commercial Fish ◽  
Main Food ◽  
The Third ◽  
The Individual

Aim. The aim is to study bivalve mollusks of the Dagestan zone of the Caspian Sea as the main feed for all the fish fauna in modern conditions. Material and methods. For the study, are used the materials received in the period of spring-autumn 2015-2017. The collection of material and data processing was carried out according to traditional methods. For the study of nutrition, 30 specimens of each fish species were opened. Such feeding characteristics as the composition of food and the ratio of feed components are given. In the study of shells of bivalve mollusks, the following morphological parameters were measured: length (L), height (H), convexity (Con.), in accordance with the most common measurement technique. Were calculated the allometric coefficients for each year of the life of the individual: the coefficient of elongation (the ratio of height to length), the convexity coefficient (the ratio of convexity to the height). Results. At all periods of the level regime, mollusks are the main food resource of the Caspian Sea. At present they form the basis of the food bolus of the investigated commercial fish species. In June 2017, 25 km north of the city of Makhachkala, after a storm, we found 109 shells of Corbicula fluminalis (O.F. Müller, 1774) (a new invasive atypical species for the investigated aquatorium), the third part of which still had the remains of the ligament. The species was the third most abundant and represented by specimens of all age stages. Conclusions. At present, there are fluctuations in the biomass of the autocolonizers Cerastoderma lamarcki (Reeve), Mytilaster lineatus (Gmelin) and Abra ovata (Philippi), as well as a significant reduction in the range of autochthonous Caspian species, mainly Didacna Eichw. Bivalve mollusks are the main food resource of the Caspian Sea. In conditions of increasing anthropogenic load, further detailed studies of the Caspian's malacofauna are needed.

scholarly journals Temporal variability of catches, distribution and dynamics of length of Russian sturgeon in waters of the Caspian Sea in 2015 –2020

2021 ◽  
Vol 0 (4) ◽  
pp. 80-90
Author(s):  
Irina Victorovna Konopleva
Keyword(s):  
Caspian Sea ◽  
Adult Population ◽  
Water Layer ◽  
Middle Part ◽  
Russian Sturgeon ◽  
The Caspian Sea ◽  
Bottom Water Layer ◽  
The North ◽  
Shallow Zone ◽  
Heating Up

The paper presents long-term data on catches, distribution and length dynamics of Russian sturgeon in the waters of the Caspian Sea for the summer-autumn periods in 2015-2020. When considering the catches in the different parts of the sea there is found their annual variability, which is especially noticeable in the shallow zone in the North Caspian (0.31-2.0 specimens/trawl) and in the Middle Caspian (0-1.31 specimens/trawl). In the course of determining the reasons for the interannual dynamics of catches there were revealed several decadal rises. The dependence of decadal catches on the temperature of the bottom water layer was analyzed. The highest rise in catches was observed in the first decade of September when the temperature of water lowered up to 20.0-15.0 °C. The increase was observed due to migrating individuals to the shallow zone of the Northern Caspian Sea from shallow waters. Despite the variability of catches, the localization of Russian sturgeon schooling in the northern and middle part of the sea during the summer-autumn periods of 2015-2020 has certain similar features and trends. Sturgeon species fed mainly on shallow banks and deep dumps, where the largest catches of sturgeon were recorded from 5.0 to 12.0 specimens/trawl. The absence of sturgeon at depths of up to 3.0 m isobath in the last five years is due to the water heating up to 27.6-28.8 °C. The decrease in the length of the Russian sturgeon observed in recent years is due to an increase in the proportion of youngsters (19.2-70.0%) against the background of a decrease in the adult population. It should be noted that from 2017 to 2019 there were not found the adult species in the catches by fishing nets, which indicates their continued re-moval from the population.

scholarly journals Some commercial fish species nutrition in the Kazakhstan part of the Caspian Sea

2019 ◽  
Vol 81 (4) ◽  
pp. 78-93
Author(s):  
S. M. Shalgimbayeva ◽  
◽  
N. N. Popov ◽  
N. Ibragimova ◽  
Zh. S. Omarova ◽  
...  
Keyword(s):  
Fish Species ◽  
Caspian Sea ◽  
The Caspian Sea ◽  
Commercial Fish

scholarly journals DISTRIBUTION OF CASPIAN SPRATS IN THE NORTH-WESTERN PART OF THE CASPIAN SEA (BASED ON RESULTS OF HYDROACOUSTIC RESEARCH IN NOVEMBER 2018)

2019 ◽  
pp. 41-50
Author(s):  
Tatiana Vasilievna Pomogaeva
Keyword(s):  
Caspian Sea ◽  
Water Surface ◽  
Bottom Layer ◽  
Water Area ◽  
Middle Part ◽  
Average Density ◽  
Layer By Layer ◽  
The Caspian Sea ◽  
The North ◽  
Study Results

Since Caspian sprat today is a reserve fishery object, hydroacoustic studies are the main purpose of solving the problem of estimating concentrations, areas and terms of the organization of the Russian marine fishery. A promising fishing area is the region of the middle part of the Caspian Sea, off the Dagestan coast, which has been studied since 2011. As it was found during previous studies, the densest sprat schools form in the autumn period in the bottom layer. The present research focuses on Caspian sprat distribution in the western part of the Middle Caspian in November 2018. Hydroacoustic tacks covered a water area of 630 NM. The echo recordings of hydroacoustic surveys covering the water area at the depths 20-60 m were analyzed. The recordings were studied considering the response of sprat to the day and night light. Processing of hydroacoustic data was carried out in several stages: analytical viewing of echograms purposed to identify specific features of sprat; recording minimum and maximum values of echo intensity depending on the depth; data post-processing in SIMRAD BI-60 program. The distribution of Caspian sprats is represented totally from the water surface to the ground, and layer by layer, in layers of 10 meters from the water surface. It has been stated that in the surface layer there are practically no sprat schools. The maximum value of the average density (8.7 t / mile2) was registered in the bottom layer (40-50 m). The study results can be used in organization of Russian sprats fishing in the Caspian Sea.

INFLUENCE OF INVADER CTENOPHORAN MNEMIOPSIS LEIDYI (A. AGASSIS, 1865) ON THE GENERAL PARTS OF THE CASPIAN SEA ECCOSYSTEM

2018 ◽  
pp. 35-48
Author(s):  
Andrey Mikhailovich Kamakin ◽  
Yuriy Aleksandrovich Paritskiy ◽  
Raisa Pavlovna Khodorevskaya
Keyword(s):  
Fish Species ◽  
Caspian Sea ◽  
Marine Mammals ◽  
Nutrient Budget ◽  
Mnemiopsis Leidyi ◽  
Ecological Problem ◽  
Annual Data ◽  
The Caspian Sea ◽  
Commercial Fish ◽  
Strategy Of Development

The article presents annual data (1999-2016) of ecological surveillance on the influence of newish for the Caspian Sea invader Mnemiopsis leidyi (A. Agassis, 1865) on marine and anadromous fish species. There has been given the analysis of unfavourable effect of invader Mnemiopsis leidyi (A. Agassis, 1865) on the abundance of marine, anadromous, semi-anadromous fishes and Caspian seal. There have been considered mechanisms, sequence and degree of impact of ctenophoran on ichthyophauna and marine mammals via a nutritive base. It has been stated that mnemiopsis distribution corresponds to seasonal distribution of zooplankton and meroplankton, whereas ctenoforan being an organism with aggressive "r-strategy" of development influences ichthyophauna both directly (eating pelagic roe and larvae of sea fish) and indirectly (via nutritive base). Drastic reduction of catches of the Caspian sprat, in particular anchovy sprat and big-eyed sprat, is stipulated by nutritional competence between these fish species and ctenoforan Mnemiopsis leidyi. In turn, decrease in number of the Caspian sprat resulted in change of the nutrient budget of the sturgeon (Russian sturgeon, stellate sturgeon, beluga) and in decrease of their number and commercial stocks. There have been offered the solutions to the ecological problem and measures to restore sturgeon stocks. Results of the research can be used in forecasting commercial fish species stocks in the Caspian Sea and in determining the damage from annual invasions of Mnemiopsis ( Memiopsis leidyi (A. Agassis, 1865)) in the northern part of the Caspian Sea.

INFLUENCE OF THE ENVIRONMENTAL FACTORS ON SHEATFISH FISHING IN THE VOLGA-CASPIAN AND THE NORTH-CASPIAN FISHERY SUBAREAS

2018 ◽  
pp. 49-58
Author(s):  
Gennadij Grigor'evich Kolosyuk ◽  
Sergey Yurievich Nikiforov
Keyword(s):  
Environmental Factors ◽  
Sea Level ◽  
Fish Species ◽  
Abiotic Factors ◽  
The Caspian Sea ◽  
Delta Front ◽  
Volga River ◽  
Commercial Fish ◽  
Silurus Glanis ◽  
The North

Delta and delta front of the Volga river are the main fishing areas in the Astrakhan region, which provide high fish capacity. At the same time, productiveness of fishing in these areas is extremely unstable because they are effected by numerous environmental factors. The essential factor is changing the level of the Caspian Sea, which is directly related to hydraulicity of the Volga watershed. Sea-level change results in changing the area of shallow water zone and coast line, which strongly impacts on a previous biotope. Besides changing the sea level and the volume of fresh-water flowing, water bio-resources are influenced by the volume of spring flood, terms of the flood beginning and thermal regime in the region. Interference of all these factors impacts on stock forming and on fishing of all fish species caught in this region. But this interference of different fish groups (semi-anadromous, river, non-migratory) is ambiguous, which is related with their biology. The purpose of the research is to define the influence of these factors on fishing one of the most important commercial fish species - sheatfish ( Silurus glanis ). The analysis of the available materials has shown that sheatfish catches in a great degree depend on some abiotic factors. Thus, raising the sea level leads to the decrease of sheatfish catches, and increasing of water mass during the flooding period in the Volga river results in lowering the total catch. Later beginning of the flood period improves the effectiveness of fishing, as well as early warning-up of water.

ICE CONDITIONS IN THE NORTH-WESTERN PART OF THE CASPIAN SEA IN THE MODERN PERIOD

2020 ◽  
Vol 19 (6) ◽  
pp. 4-17
Author(s):  
Nepomenko Leonid ◽  
◽  
Popova Natalia ◽  
Zubanov Stepan ◽  
Ostrovskaya Elena ◽  
...  
Keyword(s):  
Caspian Sea ◽  
The Caspian Sea ◽  
The North ◽  
Modern Period ◽  
Ice Conditions ◽  
North Western
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