The trophic and fishery impact of invasive Nemipterus randalli (Russell, 1986) in the northeastern Mediterranean Sea

2022-8-31
Akgün, Yağmur
The Eastern Mediterranean Sea is one of the most invaded marine ecosystems under the impact of Lessepsian species which migrated from the Red Sea to the Mediterranean Sea after the construction of the Suez Canal. The impacts of Lessepsian species on the indigenous fish and fisheries can be both positive and negative. This study aimed to delineate the commonly seen Lessepsian species Randall’s threadfin bream (Nemipterus randalli)’s impact on the food web and fishery dynamics besides current ecosystem health in Mersin, Levantine Sea using one of the most widely adopted marine food-web model, Ecopath with Ecosim. Synthetic ecological indicators were used to assess the ecosystem status of the study area. The model included thirteen functional groups that were related to N. randalli either by prey-predator interaction or competition. The model was parameterized using data collected by monthly bottom trawl samplings in 2019 and literature data. N. randalli's stomach contents were analyzed. Scenarios were applied to compare N. randalli's impacts on other species and fishery. The findings highlighted that N. randalli's increasing population in the Eastern Mediterranean Sea negatively affected the commercially exploited native fish species: red mullet, surmullet, common pandora, and axillary seabream. Ecosystem of the study area showed common characteristics with other Eastern Mediterranean regions; however, it differed in ecosystem structure and functioning due to geographical differences. Considering the plans to expand further and deepen the Suez Canal in the near future, the increase in Lessepsian species necessitates the implementation of tailored conservation methods for the Eastern Mediterranean Sea. Targeted fisheries exploitation and incentives of marketing of N. randalli are alternative management strategies that can be recommended in the Eastern Mediterranean Sea to reduce the negative effects of the species.

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Citation Formats
Y. Akgün, “The trophic and fishery impact of invasive Nemipterus randalli (Russell, 1986) in the northeastern Mediterranean Sea,” M.S. - Master of Science, Middle East Technical University, 2022.