Gazihan, Ayşe
Rising societal and economic needs of the increasing human population together with the growing size of fishing fleets, developing technology in the fishing and globalization of fish food market exerted a significant pressure on the marine ecosystems within the last decades. These pressures resulted in irreversible changes on the marine ecosystem structures and, in turn, limited the socio-economic benefits obtained from marine ecosystems. Ecosystem Based Fisheries Management aims to achieve a sustainable balance between the sociatial needs of the society and ecological health of the natural resources. This study provides a base for Ecosystem Based Fisheries Management (EBFM) for Turkish Seas employing an interdisciplinary holistic approach in three steps; I) Evaluating the historical development of the Turkish fisheries sector with its diverse sub-sectoral (marine and inland capture and aquaculture), sub-regional (along seven discrete geographical areas) and species based production trends as well as defining its diverse societal objectives, II) Exploring the direction and magnitude of the historical changes in the Turkey’s marine capture fisheries (in the Black Sea, the Marmara Sea, the Aegean Sea and the Mediterranean Sea) and the corresponding response of its supporting ecosystems in relation to concurrent management measures, III) elucidating and comparing the structure, function and fisheries impact of the regional EEZs and predicting the impact of different management options. The holistic approach included socioeconomic and ecological indicators as well as modelling studies with Ecopath with Ecosim (EwE). Results quantified the level of human induced pressures driven by increasing societal and economic demands due to the human population increase, national economic crises and corresponded governmental subsidies. Since 1980s, per capita fish consumption decreased 1.5 kg/year with 14% increase in Turkey’s fisheries production capacity and 52% rise of the human population. Indicator trends and interrelations observed between the indicators in this study could be summarised as follows; i) regional fisheries fleets have developed an over-fishing capacity, too many fishers were exploiting the constrained amount of stocks with excessive number of vessels that have excessive engine power with very low efficiency, ii) this fishing over-capacity eradicated the long sized, vulnerable fish species from the ecosystem and the ecosystem became significantly dominated by small pelagic fish, iii) even though the numbers of fishers, vessels and fishing effort of the fleet have been decreasing within the last decade, ecological indicators continued to give warning signals for a possible more severe deterioration in the regional ecosystems. Scenario simulations (except the ecology weighted scenario in the Black Sea) indicated that if the histrorical management policies were based on the ecosystem characteristics, the current targeted fish species biomass, landing weight and value would be in a better condition. Similar to the past scenario simulations, future predictions showed that EBFM can contribute to the ecological health of the ecosystems as well as to their economic efficiency. For this reason, the achievement and sustainability of ecological and socio-economic targets can be possible with a successful implementation of ‘Ecosystem Based Fisheries Management’ to the regional seas. The produced information and assessed gaps within the thesis study can be taken as a step forward on this way.


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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 ...
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A new generation (circulation, biogeochemical and a higher trophic level) model for the Black Sea was developed to provide an integrated analysis of ecosystem attributes that contributes to policy oriented criteria's of the European Union's ambitious Marine Strategy Framework Directive towards achieving Good Environmental Status by 2020. The biogeochemical model, including the carbonate module, comprises thirty state variables. The higher trophic level model includes thirteen fish species. The model system ...
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