Recent dramatıc changes in the Black Sea ecosystem the reason for the sharp decline in Turkish anchovy fisheries

As a result of eutrophication caused by increased nutrient input via major rivers during the last few decades, the Black Sea ecosystem has been subject to extreme changes in recent years. These changes first became evident in the 1980's, with abnormal phytoplankton blooms and a large increase in medusae (Aurelia aurita) biomass. Then, the introduction of a new species (a lobate ctenophore, Mnemiopsis sp.) into the Black Sea radically affected the whole ecosystem. This species competes with anchovy for the edible zooplankton as well as possibly consuming anchovy eggs and larvae in the Black Sea. The mass occurence of Mnemiopsis appears to be one of the most important reasons for the sharp decrease of anchovy and other pelagic fish stocks in the Black Sea. Although the future of the Black Sea ecosystem seems rather bleak, it is suggested that in addition to reducing anthropogenic impact, systematic studies are essential if the Black Sea fisheries are to recovery.
Journal Of Marine Systems


TUĞRUL, SÜLEYMAN; BASTURK, O; SAYDAM, C; Yılmaz, Ayşen (1992-09-10)
DURING the past two decades, catastrophic changes have occurred in the Black Sea ecosystem: the influx of pollution from the major rivers has caused intense eutrophication at the northwest coastal margin1, and fish stocks have collapsed throughout the sea2. The hydrochemical details of these events are still poorly understood3-7, and a way needs to be found to distinguish long-term variations from short-term natural fluctuations3,4 if future management of the Black Sea ecosystem is to be successful. We show...
Recent changes in the spawning grounds of Black Sea anchovy, Engraulis encrasicolus
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...
Seasonal and long-term trends in the spatial heterogeneity of lake phytoplankton communities over two decades of restoration and climate change
Fu, Hui; Yuan, Guixiang; Özkan, Korhan; Johansson, Liselotte Sander; Søndergaard, Martin; Lauridsen, Torben L.; Jeppesen, Erik (Elsevier BV, 2020-12-15)
World-wide, reducing the external nutrient loading to lakes has been the primary priority of lake management in the restoration of eutrophic lakes over the past decades, and as expected this has resulted in an increase in the local environmental heterogeneity, and thus biotic heterogeneity, within lakes. However, little is known about how the regional spatial heterogeneity of lake biotic communities changes with restoration across a landscape. Using a long-term monitoring dataset from 20 Danish lakes, we el...
Current state of overfishing and its regional differences in the Black Sea
OGUZ, Temel; Akoğlu, Ekin; Salihoğlu, Barış (2012-03-01)
Long-term (1950-2006) changes of fish landings in combination with some ecosystem indicators are used to evaluate the status and sustainability of the Black Sea fishery. Following the depletion of large pelagic predator and demersal fish stocks during the 1950-1960s, the main fishery was targetted on small and medium pelagics that declined abruptly to similar to 200 kton (kton 10(3) t) at 1989-1991 after a highly productive (similar to 750 kton) but overfished state in the 1980s. Thereafter, total landings ...
Modeling trophic interrelationships in the Black Sea
Gücü, Ali Cemal (1997-06-19)
The Black Sea being one of the largest enclosed seas, has been subjected to severe ecological changes within the last few decades. The river induced nutrient enrichment and eutrophication caused significant changes in the species composition. Some of species have disappeared while some others were newly introduced and became dominant in the Black Sea ecosystem. Among those which dominated the pelagic ecosystem, gelatinous organisms suddenly attained a high level of biomass in 1989, which can hardly be suppo...
Citation Formats
A. E. Kıdeyş, “Recent dramatıc changes in the Black Sea ecosystem the reason for the sharp decline in Turkish anchovy fisheries,” Journal Of Marine Systems, pp. 171–181, 1994, Accessed: 00, 2020. [Online]. Available: