Controls of Multiple Stressors on the Black Sea Fishery

Oguz, Temel
Black Sea is one of the most severely degraded and exploited large marine ecosystems in the world. For the last 50 years after the depletion of large predatory fish stocks, anchovy (with the partial contribution of sprat) has been acting as the main top predator species and experienced a major stock collapse at the end of 1990s. After the collapse, eastern part of the southern Black Sea became the only region sustaining relatively high anchovy catch (400,000 tons) whereas the total catch within the rest of the sea was reduced to nearly its one-third. The lack of recovery of different fish stocks under a slow ecosystem rehabilitation may be attributed, on the one hand, to inappropriate management measures and the lack of harmonized fishery policy among the riparian countries. On the other hand, impacts of multiple stressors (eutrophication, alien species invasions, natural climatic variations) on the food web may contribute to resilience of the system toward its recovery. The overfishing/recovery problem therefore cannot be isolated from rehabilitation efforts devoted to the long-term chronic degradation of the food web structure, and alternative fishery-related management measures must be adopted as a part of a comprehensive ecosystem-based management strategy. The present study provides a data driven ecosystem assessment, underlines the key environmental issues and threats, and points to the critical importance of holistic approach to resolve the fishery-ecosystem interactions. It also stresses the transboundary nature of the problem.


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Recent events in the Black Sea have had a severe impact on all compartments of the ecosystem, including ichthyoplankton. The distribution of eggs and larvae of the anchovy, the major commercial fish species, was investigated in relation to ambient conditions in the southern Black Sea during July 1992, August 1993, and June-July 1996. Average highest egg and larva numbers were observed in June-July 1996, Ichthyoplankton distribution was closely connected with the hydrography. Besides surface temperature and ...
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The invasive ctenophore Mnemiopsis leidyi (Agassiz), which was transported from the Black Sea into the Caspian Sea at the end of the 1990s, has negatively affected the ecosystem of the Caspian Sea. Zooplankton abundance, biomass and species composition were evaluated on the Iranian coast of the Caspian Sea during 2001-2006. A total of 18 merozooplankton (13 species composed of larvae of benthic animals) and holozooplankton (four Copepoda and one Cladocera) species were identified. The total number of zoopla...
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It is widely known that in 1989 a tremendous biomass of Mnemiopsis leidyi was reported in the Black Sea, At the same time, drastic declines in the pelagic fish stocks were reported. Several authors, overlooking the rapid development of the fisheries industry in the Black Sea, pointed out that the new invader was the major factor responsible for the fisheries collapse in the Black Sea. This study examines the development of the Black Sea fisheries industry, along with the ecological changes that were taking ...
Citation Formats
T. Oguz, “Controls of Multiple Stressors on the Black Sea Fishery,” FRONTIERS IN MARINE SCIENCE, pp. 0–0, 2017, Accessed: 00, 2020. [Online]. Available: