scholarly journals Modern state of the population of the European anchovy Engraulis encrasicolus (L.) (Pisces: Engraulidae) wintering off the coast of the Eastern Crimea and the North Caucasus

2019 ◽  
Vol 4 (3) ◽  
pp. 56-68
Author(s):  
G. V. Zuyev
Keyword(s):  
Black Sea ◽  
Age Structure ◽  
Average Length ◽  
Relative Number ◽  
Sea Of Azov ◽  
North Caucasus ◽  
European Anchovy ◽  
The North ◽  
Average Share

European anchovy (Engraulis encrasicolus L.) is one of the most abundant fish species in the Sea of Azov – Black Sea basin. Anchovy is the main commercial species in the region. In recent decades the share of anchovy catch has reached 80–85 %. The species is represented by two forms – Black Sea anchovy and Sea of Azov anchovy. One of the most important aims of modern research is to assess the state of anchovy population and to forecast its possible changes under the influence of various natural and anthropogenic factors. The results of studying the long-term (2010/11–2017/18) dynamics of the length-age structure and the intraspecific composition of anchovy wintering off the coast of the Eastern Crimea and the North Caucasus are presented. Totally 138 fish samples from trawl catches of fishing vessels were studied. Standard length of 44 202 specimens was measured with accuracy of 0.1 cm. The age of 1162 specimens was determined. Length-age key was compiled. The intraspecific identification of European anchovy was determined using otolith index (method of Skazkina). As indicators of the length-age structure, the average length and average age, distribution (number ratio of representatives of different length groups and age classes) were studied. Positive trends of the average length and the average age of anchovy were found, reflecting an increase of the proportion of large (> 9.5 cm) individuals in the population – three yearlings (2+) and four yearlings (3+). In the long-term plan the average length of the anchovy increased from 8.06 to 9.09 cm. At the same time the relative number of small (< 7.5 cm) individuals decreased almost 4 times (from 22.5 to 5.7 %), and the share of large individuals increased almost 6 times (from 5.7 to 33 %). The average age increased from 1.64 to 1.98 year. On the one hand, it was due to a nearly 3-fold reduction (from 7.1 to 2.6 %) in the relative number of young-of-the-year individuals (0+) and 1.5-fold reduction (from 72.6 to 47.7 %) of yearlings (1+). On the other hand, it was due to 2.4- and 4.3-fold increase in the relative number of three yearlings (2+) and four yearlings (3+), respectively. The appearance of abundant year class in 2013, 2014 and 2015 was the immediate reason of these changes. The intraspecific determination of the anchovy was found, Sea of Azov and Black Sea forms were identified. In the long-term plan their quantitative redistribution was shown. So, in 2010/11–2013/14 Sea of Azov form dominated in mixed wintering aggregations. Its average share was 58.5 %, with the share varying from 55 to 63 %. Average share of Black Sea form did not exceed 41.5 %, with the share varying from 37 to 45 %. However, in 2014/15 the number ratio of Sea of Azov and Black Sea forms changed to the opposite – with Black Sea anchovy dominating. Its share increased to 53 %, and in subsequent years ranged from 52 to 63 %, with average value of 56 %. The results obtained are in full accordance with the hypothesis of intraspecific structure reorganization of anchovy because of the change in climatic conditions (general regional warming). Earlier we suggested this hypothesis based on the results of research of long-term (1999–2010) structure dynamics of anchovy wintering off the western coast of Crimea. According to this hypothesis, in 1999–2004 Sea of Azov anchovy dominated in wintering aggregations with average share 66.7 % of the total number, with the share varying from 56 to 87 % in different years. The average share of Black Sea anchovy in that period did not exceed 33.3 %, with the share varying from 13 to 44 % in different years. In 2005 the ratio of two forms changed to the opposite. Black Sea anchovy dominated. In 2005–2010 its share was 76.7 % on average, varying in different years from 57 to 88 %. Apparently, the reorganization of the anchovy intraspecific structure should be considered as ecological adaptation of this species, ensuring more perfect adaptability to changing environmental conditions, in particular, to the water temperature. Sea of Azov anchovy and Black Sea anchovy are “temperature races”. Sea of Azov anchovy is resistant to lower reproductive temperature, Black Sea anchovy – to higher one. From the standpoint of the occurred changes in the length-age structure, the current state of anchovy population can be considered as quite good. However, taking into account the sharp decline of relative number of young-of-the-year individuals (0+) in 2016 and 2017, significant rejuvenescence of the population, and consequently anchovy length decrease should be expected in the nearest future.

Influence of Currents and Atmospheric Circulation on the Efficiency of European Anchovy Fishing during its Wintering off the Black Sea Coast of the Krasnodar Territory

2021 ◽  
Author(s):  
B. N. Panov ◽  
E. O. Spiridonova ◽  
◽  
Keyword(s):  
Black Sea ◽  
Atmospheric Transport ◽  
Mesoscale Eddy ◽  
The Black Sea ◽  
Short Term ◽  
European Anchovy ◽  
The North ◽  
Daily Data ◽  
Black Sea Coast ◽  
Sea Coast

Russian fishermen harvest European anchovy primarily off the Black Sea coast of the Krasnodar Territory during its wintering and wintering migrations. At wintering grounds, temperature conditions become a secondary factor in determining the behaviour of commercial concentration of European anchovy, with wind and currents being the primary factors. Therefore, the aim of this work is to determine the potential use of daily data on water circulation and local atmospheric transport in short-term (1–7 days) forecasting of European anchovy fishing in the Black Sea. The research used the European anchovy fishery monitoring materials for January – March 2019, as well as daily maps of the Black and Azov Seas level anomalies (from satellite altimetry data) and surface atmospheric pressure and temperature in Europe (analysis) for the mentioned period. The dynamics of the catch rate and its relation to altimetry and atmospheric transport indicators in the north-eastern part of the Black Sea were investigated using graphical and correlation methods. This analysis showed that the main factor contributing to increased catches is intensification of northwest currents in the coastal 60-km zone. The effect of atmospheric transport on fishing efficiency depends on the mesoscale eddy structure of the nearshore current field. In the presence of an intense northwest current in the fishing area, southwest atmospheric transports have a positive effect on fishing, while in the presence of an anticyclonic meander of currents, northeast atmospheric transports become effective. The presence of maximum significant relationships when the determinants of fishing performance are shifted by 1–7 days allows making short-term predictions of fishing efficiency.

scholarly journals Long term trends in the sea surface temperature of the Black Sea

Ocean Science ◽  
2010 ◽  
Vol 6 (2) ◽  
pp. 491-501 ◽  
Author(s):  
G. I. Shapiro ◽  
D. L. Aleynik ◽  
L. D. Mee
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Black Sea ◽  
Sea Surface ◽  
The Black Sea ◽  
The North ◽  
Sst Variability ◽  
Long Term Trends ◽  
Cooling Trend

Abstract. There is growing understanding that recent deterioration of the Black Sea ecosystem was partly due to changes in the marine physical environment. This study uses high resolution 0.25° climatology to analyze sea surface temperature variability over the 20th century in two contrasting regions of the sea. Results show that the deep Black Sea was cooling during the first three quarters of the century and was warming in the last 15–20 years; on aggregate there was a statistically significant cooling trend. The SST variability over the Western shelf was more volatile and it does not show statistically significant trends. The cooling of the deep Black Sea is at variance with the general trend in the North Atlantic and may be related to the decrease of westerly winds over the Black Sea, and a greater influence of the Siberian anticyclone. The timing of the changeover from cooling to warming coincides with the regime shift in the Black Sea ecosystem.

The northern Black Sea and North Caucasus

2018 ◽  
Author(s):  
Valenina Mordvinceva ◽  
Sabine Reinhold
Keyword(s):  
Black Sea ◽  
Iron Age ◽  
Seventh Century ◽  
The Black Sea ◽  
North Caucasus ◽  
The North ◽  
Long Time ◽  
History Of ◽  
Northern Shore ◽  
Greek Colonization

This chapter surveys the Iron Age in the region extending from the western Black Sea to the North Caucasus. As in many parts of Europe, this was the first period in which written sources named peoples, places, and historical events. The Black Sea saw Greek colonization from the seventh century BC and its northern shore later became the homeland of the important Bosporan kingdom. For a long time, researchers sought to identify tribes named by authors such as Herodotus by archaeological means, but this ethno-deterministic perspective has come under critique. Publication of important new data from across the region now permits us to draw a more coherent picture of successive cultures and of interactions between different parts of this vast area, shedding new light both on local histories and on the role ‘The East’ played in the history of Iron Age Europe.

scholarly journals Modern state of the reproductive potential of Black Sea sprat Sprattus sprattus phalericus (Risso, 1826) (Pisces: Clupeidae) in Crimean region and conditions for its formation

2019 ◽  
Vol 4 (4) ◽  
pp. 3-14
Author(s):  
G. V. Zuyev
Keyword(s):  
Black Sea ◽  
Average Length ◽  
Reproductive Potential ◽  
Danube River ◽  
The Black Sea ◽  
Total Catch ◽  
Sprattus Sprattus ◽  
The Absolute ◽  
Individual Fecundity

Black Sea sprat Sprattus sprattus phalericus (Risso, 1826) is one of the abundant species of fish in the Sea of Azov – Black Sea basin. Due to its large number sprat plays an extremely important role in the ecosystem of the sea, being an intermediate link between zooplankton and representatives of the highest trophic level – large predatory fish, dolphins, and birds. At the same time sprat is one of the important commercial fish in all the Black Sea countries, steadily being on the second place of catch volume in recent decades (after anchovy). The total catch reaches 100 thousand tons. Turkey and Ukraine are the main producing countries. Monitoring and forecast of biological state of sprat population with rising fishing intensity and climate changes are urgent tasks. The research subject of this article is the long-term (2000–2016) dynamics of biological (qualitative) parameters determining the population fecundity of Black Sea sprat in Crimean region, the current state of reproductive potential, and the conditions for its formation. The article is based on the results of own research. Parameters determining the population fecundity – the length-age structure of the spawning part population, the absolute individual fecundity, and the sex structure population (ratio between females and males) – were studied. In the long-term plan (in 2011–2016 compared with 2000–2004) the average length of spawning females decreased by 1.22 times (from 7.36 to 6.03 cm). It was accompanied by a decrease in the absolute individual fecundity by 2.39 times (from 13 625 to 5690 eggs). The numerical ratio between females and males decreased by 1.23 times (from 1.95 to 1.59). Simultaneously the sprat stock in the northern part of the Black Sea was reduced by more than 2.5 times (from > 500 thousand tons to < 200 thousand tons). As a result, the population fecundity of sprat in Crimean region decreased by more than 7 times (2.39 × 1.23 × 2.5). The conditions of sprat fishing in the northern part of the Black Sea (from the mouth of the Danube River to the Kerch Strait) were studied. They showed 2-fold decrease (from 251.9 thousand tons in 2000–2004 to 129.1 thousand tons in 2011–2016) in the total catch and more than 2.3-fold decrease (from 50.4 to 21.4 thousand tons) in average annual catch in this region. On the contrary, in the Crimean shelf the total catch at that time increased by 1.2 times (from 76.9 to 92.2 thousand tons), and its average annual value remained constant (15.4 thousand tons). While reducing the stock by 2.5 times, this means that the fishing pressure on the Crimean population increased 2.5 times. This fact suggests considering the factor of fishing as the main cause of its degradation. Validity of this version is confirmed by the fact of conjugacy (inverse connection) of interannual fluctuations between the catch and the length-age parameters of sprat in Crimean region in 2003–2013 previously found: catches over 15–16 thousand tons were accompanied by a next year decrease in the fish average length. Regulation of fishing is a necessary condition for preventing further degradation, for restoring and maintaining sustainable state of sprat population in Crimean region and its reproductive potential. The negative impact of natural (climatic and trophic) factors on the state of the population should be recognized as a secondary one. Local overfishing indicates indirectly the structuring of the commercial stock of Black Sea sprat, its division into a number of geographical aggregations (stock units), i. e. the presence of intraspecific differentiation.

scholarly journals Geographical variability of length-age structure of the Black Sea sprat Sprattus sprattus phalericus (Risso) (Pisces: Clupeidae) and intraspecific differentiation

2016 ◽  
Vol 1 (1) ◽  
pp. 24-35
Author(s):  
G. V. Zuyev ◽  
V. A. Bondarev ◽  
Yu. V. Samotoi
Keyword(s):  
Interannual Variability ◽  
Black Sea ◽  
Age Structure ◽  
The Black Sea ◽  
Population Parameter ◽  
Intraspecific Differentiation ◽  
Geographical Regions ◽  
The Crimea ◽  
Scientific Technical

Investigations of the Black Sea sprat intraspecific differentiation are the basis for the scientific substantiation of rational exploitation of its resource potential. This work is devoted to the study of spatial variability of length and age structure of sprat as specific population parameter reflecting its intraspecific differentiation. Our own data and materials of Scientific, Technical and Economic Committee for Fisheries (STECF) of the European Commission have been used. The first time long-term dynamics (2007–2012) and interannual variability of length and age structure of sprat in different geographical regions of the Black Sea (coastal waters of Bulgaria – Romania, Turkey and the Crimea) have been investigated. Differences of the long-term dynamics and interannual variability of length and age structure in these regions have been found. Sprat population from Bulgaria – Romania region is in better conditions (mean length 8.59 ± 0.01 cm; mean age 1.79  year), sprat population from Crimea region is in worse conditions (mean length 7.64 ± 0.01 cm; mean age 1.38 year). It has been shown that the main factor determining the interregional biological heterogeneity of sprat is the different fishery regulations. This fact disagrees with concept of united commercial sprat stock in the Black Sea.

Study of water exchange in Kerch strait using NEMO model of Black Sea

2021 ◽  
Author(s):  
Roman Sedakov ◽  
Barnier Bernard ◽  
Jean-Marc Molines ◽  
Anastasiya Mershavka
Keyword(s):  
Water Flow ◽  
Black Sea ◽  
Water Exchange ◽  
Discharge Rate ◽  
The Black Sea ◽  
External Forcing ◽  
Sea Of Azov ◽  
The Sea Of Azov ◽  
The North ◽  
Kerch Strait

&lt;p&gt;The Sea of Azov is a small, shallow, and freshened sea that receives a large freshwater discharge. Under certain external forcing conditions brackish water from the Sea of Azov flow into the north-eastern part of the Black Sea through the narrow Kerch Strait and form a surface-advected buoyant plume. Water flow in the Kerch Strait also regularly occurs in the opposite direction, which results in the spreading of an advected plume of saline and dense water from the Black Sea into the Sea of Azov. Using a regional Black Sea Azov Sea model based on NEMO we study physical mechanisms that govern water exchange through the Kerch Strait and analyze the dependence of its direction and intensity on external forcing conditions. We show that water exchange in the Kerch Strait is governed by a wind-induced barotropic pressure gradient. Water flow through the shallow and narrow Kerch Strait is a one-way process for the majority of the time. Outflow from the Sea of Azov to the Black Sea is induced by moderate and strong northerly winds, while flow into the Sea of Azov from the Black Sea is induced by southerly winds. The direction and intensity of water exchange have wind-governed synoptic and seasonal variability, and they do not depend on the variability of river discharge rate to the Sea of Azov on an intraannual timescale.&lt;/p&gt;

Introduction

2016 ◽  
pp. 1-8
Author(s):  
Paul Huddie
Keyword(s):  
Black Sea ◽  
Russian Empire ◽  
The Black Sea ◽  
Western Balkans ◽  
Crimean War ◽  
Black Sea Region ◽  
The North ◽  
The Russian Empire ◽  
North Western

The year 2014 marked the 160th anniversary of the beginning of the Crimean War, 1854–6. It was during that anniversary year that the names of Crimea, Sevastopol, Simferopol and the Black Sea re-entered the lexicon of Ireland, and so did the terms ‘Russian aggression’, ‘territorial violation’ and ‘weak neighbour’. Coincidentally, those same places and terms, and the sheer extent to which they perpetuated within Irish and even world media as well as popular parlance, had not been seen nor heard since 1854. It was in that year that the British and French Empires committed themselves to war in the wider Black Sea region and beyond against the Russian Empire. The latter had demonstrated clear aggression, initially diplomatic and later military, against its perceived-to-be-weak neighbour and long-term adversary in the region, the Ottoman Empire, or Turkey. As part of that aggression Russia invaded the latter’s vassal principalities in the north-western Balkans, namely Wallachia and Moldavia (part of modern-day Romania), collectively known as the Danubian Principalities. Russia had previously taken Crimea from the Ottomans in 1783....

scholarly journals Water exchange between the Sea of Azov and the Black Sea through the Kerch Strait

Ocean Science ◽  
2020 ◽  
Vol 16 (1) ◽  
pp. 15-30 ◽  
Author(s):  
Ivan Zavialov ◽  
Alexander Osadchiev ◽  
Roman Sedakov ◽  
Bernard Barnier ◽  
Jean-Marc Molines ◽  
...  
Keyword(s):  
Water Flow ◽  
Black Sea ◽  
Water Exchange ◽  
The Black Sea ◽  
External Forcing ◽  
Sea Of Azov ◽  
Buoyant Plume ◽  
The Sea Of Azov ◽  
The North ◽  
Kerch Strait

Abstract. The Sea of Azov is a small, shallow, and freshened sea that receives a large freshwater discharge. Under certain external forcing conditions low-salinity waters from the Sea of Azov flow into the north-eastern part of the Black Sea through the narrow Kerch Strait and form a surface-advected buoyant plume. Water flow in the Kerch Strait also regularly occurs in the opposite direction, which results in the spreading of a bottom-advected plume of saline and dense waters from the Black Sea into the Sea of Azov. In this study we focus on the physical mechanisms that govern water exchange through the Kerch Strait and analyse the dependence of its direction and intensity on external forcing conditions. Analysis of satellite imagery, wind data, and numerical modelling shows that water exchange in the Kerch Strait is governed by a wind-induced barotropic pressure gradient. Water flow through the shallow and narrow Kerch Strait is a one-way process for the majority of the time. Outflow from the Sea of Azov to the Black Sea is induced by moderate and strong north-easterly winds, while flow into the Sea of Azov from the Black Sea occurs during wind relaxation periods. The direction and intensity of water exchange have wind-governed synoptic and seasonal variability, and they do not depend on the rate of river discharge to the Sea of Azov on an intra-annual timescale. The analysed data reveal dependencies between wind forcing conditions and spatial characteristics of the buoyant plume formed by the outflow from the Sea of Azov.

Short Communication: Estimating abundance, survival and age structure of the Alberes cattle using recapture techniques

2011 ◽  
Vol 91 (3) ◽  
pp. 343-347
Author(s):  
Marta Fina ◽  
Joaquim Casellas ◽  
Jesús Piedrafita
Keyword(s):  
Overall Survival ◽  
Genetic Variability ◽  
Age Structure ◽  
Death Rate ◽  
Short Communication ◽  
Average Length ◽  
Local Breed ◽  
Capture Recapture ◽  
Average Longevity

Fina, M., Casellas, J. and Piedrafita, J. 2011. Short Communication: Estimating abundance, survival and age structure of the Alberes cattle using recapture techniques. Can. J. Anim. Sci. 91: 343–347. The Alberes breed is an endangered bovine breed with an unknown population size. In this study, we estimated a total of 447.9 (435.5 to 456.6) individuals using capture-recapture methods. Overall survival and recapture estimates were 0.85±0.01 and 0.94±0.01, respectively, leading to an average longevity of 5.64 yr and with the highest death rate concentrated in the first 3 yr of life (38.94%). For breeding cows, the average length of the productive life was 8.35 yr. The current population of this local breed is too small to prevent future losses of genetic variability, and a conservation program is essential to ensure the long-term viability of the breed.

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