Understanding the Impact of Environmental Variability on Anchovy Overwintering Migration in the Black Sea and its Implications for the Fishing Industry

Güraslan, Ceren
Fach Salihoğlu, Bettina Andrea
Oğuz, Temel
Black Sea anchovy (Engraulis encrasicolus) undertake extensive overwintering migrations every fall from nursery grounds to warmer overwintering areas located on the south-eastern coast of the Black Sea. During migration and particularly upon arrival at the Anatolian coast, they support an important fishery and valuable source of income for the regional community. Black Sea anchovy have undergone significant stock fluctuations partly related to climatic conditions, for example, migrating anchovy schools arrived late or failed to arrive at the Anatolian coast when fall temperatures increased. It is therefore of importance to understand the conditions required for successful overwintering migration and explore different migration routes. This study invokes a Lagrangian modeling approach applied to satellite derived circulation and temperature data as a first attempt to model anchovy migration dynamics in the Black Sea. This modeling approach takes the influence of the physical environment into account, while the quality of overwintering grounds, adaptive, schooling, and homing behavior is neglected. The model is used to investigate the possible influence of interannual and seasonal variability of temperature and surface currents, as well as the influence of migration behavior on the success of anchovy overwintering migration for both the Black Sea and Azov Sea anchovy. The results of the present work show the possibility that overwintering anchovy fished along the Turkish Eastern Anatolian coast may not exclusively originate from the northwestern shelf, but mainly from the eastern Black Sea basin. Migration pathways are identified for both Black Sea and Azov Sea anchovy, which are of importance for the national fisheries efforts of riparian countries. The modeling results are in agreement with general patterns of anchovy migration given in the literature indicating that the physical environment may be a major factor in shaping general migration patterns. Simulation results are used to hypothesize about alternatives to previously determined migration routes and provide potential reasons that explain the inability of the Bulgarian anchovy fishery to recover. Results show that the intensity and timing of autumnal cooling, coupled with current strength, can be of significant importance in determining annual and seasonal variability of migration success. Considering the need for fisheries management to account for the variability in fishable overwintering anchovy stocks a modeling approach as developed in the current study may provide such a tool.


Güraslan, Ceren; Fach Salihoğlu, Bettina; Department of Oceanography (2016-10-21)
Black Sea anchovy (Engraulis encrasicolus ponticus) undertake extensive (~1000km long) overwintering migration in autumn from northern spawning grounds to the overwintering areas located at the south-eastern coasts of the Black Sea. When arriving at the Anatolian coast, they support important fisheries in Turkey. Black Sea anchovy is known to experience stock variability quite frequently including stock collapses, which are believed to be closely linked with environmental conditions. Therefore, it is of imp...
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Gücü, Ali Cemal; Ok, Meltem; Sakinan, Serdar (2016-01-01)
Towards the end of the 1980s, when the spawning grounds in the northwestern shelf (NWS) of the Black Sea were lingering with the effects of eutrophication and of an exotic invasive ctenophore, a series of basin-wide international ichthyoplankton surveys pointed out an increase in the anchovies spawning in the southern half of the Black Sea. Later, with the help of international conservation efforts, several key littoral ecosystem components within the anchovy's historical spawning grounds showed signs of re...
Modeling the impact of climate variability on Black Sea anchovy recruitment and production
Güraslan, Ceren; Fach Salihoğlu, Bettina Andrea; Oğuz, Temel (2014-09-01)
The connection of climate variability with anchovy spawning and recruitment in the Black Sea in particular, and other ecosystems in general, was studied using a two-way coupled lower trophic level and anchovy bioenergetics model. Climate variability was represented by a 50-yr time series of daily temperature and vertical mixing rates with stochastic variations. Temperature was found to be the dominant factor influencing early life stages and hence population dynamics of Black Sea anchovy as marked by a high...
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Fach Salihoğlu, Bettina Andrea (2014-01-01)
Dispersal mechanisms of Black Sea anchovy larvae (Engraulis encrasicolus ponticus) across the Black Sea were studied with an individual based anchovy larvae model embedded in a Lagrangian model using surface currents calculated from daily dynamic height topography maps of altimeter data during a period of three years (2001-2003). Particles representing anchovy eggs were released at different sites during June to August and their movement was tracked over time. Drifters were advected for 36 days, representin...
Elucidating the patterns in mid-winter waterbird surveys by using climate, lake water level fluctuations and macrophyte records
Özgencil, İbrahim Kaan; Beklioğlu, Meryem; Özkan, Korhan; Department of Biology (2017)
Impacts of winter climate in Eastern Europe, North Atlantic Oscillation (NAO), water level changes and submerged macrophytes on wintering waterbird community size and structure in three Turkish shallow lakes from three different geographical regions were investigated by using the Mid-Winter Waterbird Survey results from 1967-2016. The study demonstrated that average winter air temperatures in Eastern Europe and combined wintering waterbird community density of the study lakes were negatively correlated. Nor...
Citation Formats
C. Güraslan, B. A. Fach Salihoğlu, and T. Oğuz, “Understanding the Impact of Environmental Variability on Anchovy Overwintering Migration in the Black Sea and its Implications for the Fishing Industry,” FRONTIERS IN MARINE SCIENCE, pp. 0–0, 2017, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/32460.