Shifts in the pelagic fishery dynamics in response to regional sea warming and fishing in the Northeastern Mediterranean

Date

2023-12-01

Author

Demirel, Nazlı
Akoğlu, Ekin
Yıldız, Taner

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This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

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Understanding the dynamics of pelagic fish fluctuations is crucial to ecosystem well-being and sustainable fishery. Here, inter- and intra-annual landing dynamics of small and medium pelagic fish were delineated between 2000 and 2022 in the landlocked Sea of Marmara. Time series of environmental variables and fisheries landings were analyzed for their trends and inter-correlations. Results showed that variations in the landings of small and medium pelagic fish in the Sea of Marmara had strong seasonality and were very likely affected by fishing effort, and sea surface temperature regimes. During the study period, landings of anchovy, bonito and bluefish, and net primary production showed no significant trends. On the other hand, Mediterranean horse mackerel had a significant decreasing trend, while sardine landings and the sea surface temperature (0.05 ± 0.01 °C/y−1) had a significant increasing trend. Analysis of the duration of the fishing period in a given fishing season showed that reaching 90% of the landings (L90) for anchovy, sardine, and Mediterranean horse mackerel shifted almost one month earlier, and for bonito, L90 showed no change for larger ones, but extended almost one month for small individuals. The multiple linear regression models indicated that the landing dynamics of small and medium pelagic fish were also influenced by the prey-predator relations in the food web. Exploiting anchovy stocks would likely have consequences on the dynamics of bonito and bluefish stocks, and exploiting bonito and bluefish stocks would have a cascading trophic impact on small pelagic fish catches. This study highlights the necessity of adaptive management measures for fisheries under regional sea warming conditions, and a one-and-a-half-month delay in the opening time of the fishing season, thus shortening its duration is strictly recommended.

Subject Keywords

Climate change, Fishing season, Landing dynamics, Sea of Marmara, Sea surface temperature, Small pelagic

URI

https://hdl.handle.net/11511/106195

Collections

Graduate School of Marine Sciences, Article