scholarly journals Long-term dynamic of reproductive performance of European anchovy Engraulis encrasicolus Linnaeus, 1758 and its connection with temperature

2017 ◽  
Vol 2 (2) ◽  
pp. 3-19
Author(s):  
G. V. Zuev ◽  
T. N. Klimova
Keyword(s):  
Water Temperature ◽  
Black Sea ◽  
Relative Abundance ◽  
The Black Sea ◽  
Western Coast ◽  
European Anchovy ◽  
Engraulis Encrasicolus ◽  
European Anchovy Engraulis Encrasicolus ◽  
Calendar Dates

European anchovy (Engraulis encrasicolus Linnaeus, 1758) is one of the most numerous species of fish in the Azov-Black Sea basin. It is the main commercial fishery object, its share being about 80 %. Assessment of the functional state of the anchovy population and its dynamics in conditions of the climatic warming was one of the topical tasks in contemporary research. The paper is devoted to the study of a long-term dynamic of anchovy population: reproductive parameters and its relation with water temperature for the purpose of potential prediction. The results of our own investigations made in 2000–2015 in the area bordering the south-western coast of Crimean peninsula (Sevastopol–Balaklava region) have been considered in the paper. The eggs were collected with Bogorov – Rass net (BR-80/113) from the layer of 0–10 m. Adult specimen were caught with pound seines. 702 ichthyoplankton samples and 941 mature anchovy females (gonad maturation stage V, VI–IV and VI–V) were analyzed. Calendar dates and duration of spawning season, intensity and efficiency of spawning, intraspecific composition of mature anchovy females were researched. Calendar dates of anchovy spawning beginning near the south-western coast of Crimea in 2000–2014 varied from the 2ⁿᵈ decade of May (early spawning) to the 3ʳᵈ decade of June (late spawning); finishing dates – from the 3ʳᵈ decade of August to the 3ʳᵈ decade of September. Total reproductive period duration was 8–14 weeks, average – 11 weeks. In long-term plan the time shift for earlier calendar dates was determined at the start of the spawning. Maximum peak of spawning intensity in 2012–2013 varied from 33.6 to 78.7 % (average 51.2 %). Peak of population spawning was in July – August, its repeatability in July – 25 and in August 66.7 %. The peak spawning shift to the earlier time was determined in perennial plan: in 2000–2005 years peak spawning periodicity amounts in August to 100 %; in 2007–2013 – only 50 %. Absolute number of eggs (spawning efficiency) change from 1.6 to 29.9 specimen·m-2 in 2000–2014 years (average 10.3 specimen·m-2). Low, average and high yielding years with number of eggs less than 10, 10–20 and more than 20.0 specimen·m-2 were determined. The average spawning efficiency was: 5.1, 14.5 and 25.0 specimen·m-2 respectively. Spawning efficiency in high-yielding years exceeded 1.7 and 4.9 times the efficiency of low and average-yielding years. In long-term plan the positive efficiency spawning trend was determined. In 2000–2001 the intraspecific structure reconstruction of anchovy took place, followed by redistribution of numerical relation in composition of spawning part of the Azov and the Black Sea subspecies in favor of the last one. In 2000–2004 relative abundance of Black Sea anchovy amounted 33.3 %, in 2005–2011 years – 76.7 %. Simultaneously a considerable catch growth was registered. Сorrelation coefficient of the Black Sea anchovy’s relative abundance and catch was 0.92. Calendar time of spawning beginning, its intensity and efficiency are closely connected with the water temperature. Lower temperature limit for mass spawning was 17.5 °С. The region of “maximum favorable spawning temperature” lays in the range of 23 °C and warmer. Nearly 2/3 of population reproductive potential is realized within this temperature range.

scholarly journals Stable C and N Isotope Composition of European Anchovy, Engraulis encrasicolus, from the Marmara Sea and the Black Sea

2021 ◽  
Vol 9 (6) ◽  
pp. 1087-1091
Author(s):  
Tanju Mutlu
Keyword(s):  
Black Sea ◽  
Isotope Composition ◽  
Nitrogen Isotope ◽  
Isotope Ratios ◽  
The Black Sea ◽  
Marmara Sea ◽  
Δ13c And Δ15n ◽  
European Anchovy ◽  
Engraulis Encrasicolus ◽  
European Anchovy Engraulis Encrasicolus

The aim of this study is to determine the stable isotope ratios of anchovy caught in the Black Sea and Marmara Sea. Stable carbon and nitrogen isotope ratios (δ13C, δ15N) of European anchovy (Engraulis encrasicolus) were estimated at four sampling sites (İğneada, İstanbul, Trabzon and Hopa) in the Black Sea and Marmara Sea (Turkey). δ13C and δ15N values of European anchovy ranged from -22.31 to -19.19 ‰ and from 3.81 to 12.79 ‰, while C/N ratios ranged from 2.01 to 6.21 in muscle tissue of European anchovy, respectively. İğneada station had more depleted δ13C values and more enriched δ15N values than other stations. This difference might be due to the terrestrial input and agricultural activities in this region.

scholarly journals Current population structure of European anchovy Engraulis encrasicolus L. (Engraulidae: Pisces) in the Sea of Azov – Black Sea basin and history of its formation

2019 ◽  
Vol 4 (1) ◽  
pp. 45-62
Author(s):  
G. V. Zuyev
Keyword(s):  
Population Structure ◽  
Black Sea ◽  
The Black Sea ◽  
Sea Of Azov ◽  
European Anchovy ◽  
Engraulis Encrasicolus ◽  
The Sea Of Azov ◽  
Rates Of Evolution ◽  
History Of ◽  
European Anchovy Engraulis Encrasicolus

European anchovy Engraulis encrasicolus L. is one of the most abundant fish species in the Sea of Azov – Black Sea basin. Historically it is the main commercial fish in all Black Sea countries. In modern conditions, the share of anchovy catches totals 80–85 %. In recent years (since 2001) the average annual catch was 250 tones. E. encrasicolus is a polytypic species. In the Black Sea and in the Sea of Azov there are two intraspecific forms – Black Sea anchovy (E. encrasicolus ponticus Alex.) and Sea of Azov anchovy (E. encrasicolus maeoticus Pusanov), and their taxonomic status is still unclear. An actual task is the assessment of the current population structure of E. encrasicolus and its possible changes under the influence of climatic and anthropogenic factors in order to develop the necessary measures to prevent negative impacts and to preserve the resource potential of the species. This work focuses on the study of European anchovy modern population structure in the Black Sea and the Sea of Azov, the geological and paleoclimatic conditions of its formation and assessment of possible changes taking into account real natural and anthropogenic risk factors. The work is based on the research results of intraspecific morphobiological, biochemical, genetic and ecological variability of E. encrasicolus, as well as spatial and reproductive relationships between Sea of Azov anchovy and Black Sea anchovy. Investigations concerned with the study of intraspecific heterogeneity problem of E. encrasicolus in the Black Sea and in the Sea of Azov were reviewed. Data obtained by domestic and foreign authors for a 100-year period (1913–2014) were analyzed; the list of publications includes more than 40 titles. Our own research results were also used in the work. The information about reproductive area boundaries of Sea of Azov anchovy and Black Sea anchovy was systematized and summarized. Their reproductive areas were found to be distributed over the entire water area of the Black Sea and the Sea of Azov and overlapped over the whole space. The absence of spatially separate reproductive areas and the presence of simultaneous spawning exclude belonging of Black Sea anchovy and Sea of Azov anchovy to different subspecies (geographical races). Population level of the differences between Black Sea anchovy and Sea of Azov anchovy was confirmed by the results of genetic and biochemical studies: the coefficients of genetic similarity and genetic distance between them were 0.9983–0.9985 and 0.0015–0.0017, respectively. Geological history of population structure formation of Engraulis encrasicolus was presented. Modern Sea of Azov anchovy and Black Sea anchovy in the past were spatially separated and came into contact again only after appearance of a number of differences between them in the course of evolution. Their isolation occurred in the newly formed Sarmatian Sea isolated from the Tethyan Ocean in the Miocene (23.0–5.3 million years ago). As a result, two geographically isolated and independent anchovy groups (western and eastern) appeared. Further development of these groups occurred at different rates. Faster rates of evolution of the western group led to the formation of more progressive Black Sea anchovy and Mediterranean anchovy, lower rates of evolution of the eastern group led to the formation of more primitive Sea of Azov anchovy. Only in the modern era, after the last glacial period had ended and the connection of the Black Sea with the Mediterranean Sea had been reconstituted (7–5 thousand years ago) Sea of Azov anchovy and Black Sea anchovy contacted, the process was followed by their subsequent hybridization, i. e. by the appearance of the zone of secondary intergradation. There is a real threat of Sea of Azov anchovy genofund destruction and its “genetic absorption” by Black Sea anchovy in conditions of introgressive hybridization in recent decades associated with salinity increase of the Sea of Azov caused by human economic activity. Nevertheless, the genetic uniqueness of Sea of Azov anchovy persists to the present, first of all, due to ecological isolation mechanisms – seasonal isolation (timing) and biotope isolation (site selection) during the reproductive period. А certain pattern of redistribution in the spawning population composition of Sea of Azov anchovy and Black Sea anchovy females was identified: the share of Sea of Azov anchovy females decreased while the share of Black Sea anchovy females increased. Thus, Sea of Azov anchovy and Black Sea anchovy populations are the “temperature” races adapted to different reproductive temperature conditions: Sea of Azov anchovy – to lower temperature conditions, Black Sea anchovy – to higher ones. In addition to seasonal isolation, the biotopic isolation of Black Sea anchovy and Sea of Azov anchovy was found. Black Sea anchovy prefers to spawn in open areas of the Black Sea with water salinity above 16 ‰: its share is here 55–60 %, whereas in the coastal waters its share does not exceed 5–40 %. Sea of Azov anchovy, on the contrary, in spawning period prevails in the coastal freshened waters with salinity below 15 ‰, with its share here reaching 60–90 %.

Stock Assessment of Anchovy (Engraulis encrasicolus L) in Northern Black Sea and Sea of Azov

2015 ◽  
pp. 209-243 ◽  
Author(s):  
Alexander Chashchin ◽  
Vladyslav Alekseevich Shlyakhov ◽  
Vladimir E. Dubovik ◽  
Sergey Negoda
Keyword(s):  
Black Sea ◽  
Stock Assessment ◽  
Direct Methods ◽  
Distribution Patterns ◽  
The Black Sea ◽  
European Anchovy ◽  
Engraulis Encrasicolus ◽  
Leading Role ◽  
Wintering Areas ◽  
Survey Results

European anchovy is most abundant in the Azov and Black Sea Basin ichthyocenosis and plays leading role in the marine fisheries. There are two subspecies of the European anchovy in the Black Sea: the Black Sea anchovy Engraulis encrasicolus ponticus Aleksandrov and the Azov anchovy Engraulis encrasicolus maeoticus Pusanov. Wintering areas of both subspecies (stocks) are located in the Black Sea. Basing on the more than 30-years research of anchovy, this chapter summarizes data on catches, catch per unit effort, population parameters, spatial distribution patterns, abundance, and scientific survey results separately for two stocks. Direct methods of stock assessment, based on trawl, lampara and hydroacoustic surveys data, have been applied. Authors recommend to the Black Sea countries authorities to build their anchovy fishery-regulating decisions mainly on the hydroacoustic surveys' results. A major impact of invasive Atlantic ctenophores Mnemiopsis leidyi and Beroe ovata on anchovy populations is revealed.

scholarly journals Tendencies of long-term changes of temperature fields, salinity and water level of the North-Western part of the Black Sea

2019 ◽  
pp. 84-94
Author(s):  
N. Berlinsky ◽  
R. Gavriluk ◽  
O. Danilenko
Keyword(s):  
Water Temperature ◽  
Sea Level ◽  
Black Sea ◽  
Temperature Increase ◽  
The Black Sea ◽  
Sea Level Fluctuations ◽  
The North ◽  
Long Term Changes ◽  
North Western

The paper analyzes the variability of hydrological characteristics of the North-Western part of the Black for different temporal scales: long-term, seasonal and synoptic. The traditional methods of geographic investigations, such as comparative-geographic, retrospective and cartographic methods, were used. When analyzing sea level data packages and thermohaline characteristics mathematical methods, including statistical, correlation and regression analysis, were used. As a result of the conducted research quantitative estimates of tendencies of long-term changes of the thermohaline characteristics and level in the North-Western part of the Black Sea were received. Over the period of 1982-2005 an increase of water temperature in the North-Western part of the Black Sea was observed: in winter water temperature in the surface layer increased by 2оC, in the bottom layer – by more than 2оC. Over the period of 1990-2005 an increase of an average annual water temperature in Odesa area constituted 1,2°C. The most considerable and statistically significant temperature increase took place during the summer hydrological season: an average summer temperature increased during this period by 2,7оC. During transitional seasons (autumn and spring) there was also a tendency of temperature increase, however, statistically significant trend was observed only during the autumn period. There is a statistically significant negative trend observed for long-term changes of salinity. For the period of 1990-2005 an average annual salinity decreased by 1.36 ‰. A tendency of salinity decrease was observed for all seasons of the year, however, statistically significant trends are observed only in winter and summer. A close relationship between long-term changes in water salinity and runoff of the Dnieper River was also established. A sea level rise is observed at all stations of the North-Western part of the Black Sea. Over the period of 1947-2012 an average annual sea level in Odesa increased by 14 cm. An analysis of climatic changes of wind-induced sea level fluctuations showed that the frequency of surges of varying intensity remained almost unchanged, however, the frequency of sweeps changed significantly. Over the period of 1980-2012, as opposed to the period of 1947-1979, the frequency of minor sweeps (no more than 30 cm) increased, and the frequency of significant (more than 30 cm) and very significant (more than 50 cm) sweeps, on the contrary, decreased by about 5%-6%. Changes of wind-induced sea level fluctuations' character harmonize with wind direction and wind speed over the North-Western part of the Black Sea.

Oithona davisae: naturalization in the Black sea, inter-annual and seasonal dynamics, effect on the structure of the planktonic copepod community

2019 ◽  
Vol 59 (6) ◽  
pp. 1008-1015
Author(s):  
A. D. Gubanova ◽  
O. A. Garbazey ◽  
D. A. Altukhov ◽  
V. S. Mukhanov ◽  
E. V. Popova
Keyword(s):  
Black Sea ◽  
Coastal Waters ◽  
Native Species ◽  
Significant Decline ◽  
Acartia Tonsa ◽  
The Black Sea ◽  
Copepod Community ◽  
Oithona Davisae ◽  
Sevastopol Bay

Long-term (20032014) routine observations of zooplankton in Sevastopol Bay (the Black Sea) have allowed the naturalization of the invasive copepod Oithona davisae to be studied in the Black Sea coastal waters. Inter-annual and seasonal variability of the species and their impact on the native copepod community have been analyzed. The invasion of O. davisae and their undoubted dominance in terms of abundance were shown to alter the community structure but, at the same time, the abundances of the native species did not decrease, excepting the Black Sea earlier invader Acartia tonsa. A significant decline in A. tonsa numbers over the stages of O. davisae establishment and naturalization provided evidence of competition between the species. O. davisae have been demonstrated to gain competitive advantage over A. tonsa, that ensured their fast dispersal in the Black Sea, acclimatization in the new habitat and the successful competition over native species.

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