UBC Theses and Dissertations
Assessment of the Red Sea ecosystem with emphasis on fisheries Tesfamichael, Dawit
A comprehensive assessment of the Red Sea large marine ecosystem (LME), with emphasis on fisheries, was carried out using several approaches. The assessment started with a multidisciplinary rapid appraisal of the sustainability of the fisheries using standardized attributes in ecological, economic, social, technical and ethical fields. Then a time-series assessment of the fishery was carried out using data from interviews and the reconstruction of catch from 1950 - 2006. A case study to estimate the unreported catch by quantifying qualitative information on incentives to misreport was carried out for Eritrean fisheries. Finally, a comprehensive and detailed assessment was done in an ecosystem-based framework using the modelling tool Ecopath with Ecosim (EwE), which quantifies the trophic interactions of the organisms and fisheries. It was used to predict the impact of different scenarios of fisheries on the ecosystem and explore the conflict between artisanal and industrial fisheries. Uncertainty analysis was carried out for the different assessment methods employed. The results of the assessments have varying levels of detail: relative ranking of the sustainability of fisheries in the rapid appraisal assessment, relative quantitative changes over time in the interview analysis, actual historic quantitative assessment of the catches in the catch reconstruction, and finally a quantitative assessment with potential to predict future scenarios using ecosystem modelling. The results give a holistic understanding of the Red Sea ecosystem and its fisheries. The data and resources needed increased as the details of the outputs increased. The assessments complemented each other and there are similarities in the results. They all showed declines in all fisheries, except for beach seining. Sharks, the top predator of the system, showed the worst decline in all the assessments; and the interview and catch reconstruction methods gave strikingly similar results for sharks. The ecosystem modelling did not show direct impact between artisanal and industrial fishery sectors due to the lack of trophic interactions. In addition, the thesis demonstrates that fishery researchers and practitioners can utilize different assessment tools, given the resources at their disposal, to assist the management of resources to conserve ecosystems and livelihoods.
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