Preliminary Assessment of the relationship between CPUEs and large-scale climate Indices on the South coast of Turkey

Merve KURT, Ali Cemal GÜCÜ


The Mediterranean, particularly the east side, is considered one of the most susceptible regions to climate change. The marine fauna, including fish, has already been reported to respond to changing conditions. It is fundamental to understand which changes in the fish stocks are related to varying temperatures to design sustainable fishing practices. On the Turkish coast of the Mediterranean Sea, fluctuations in the fish stocks are attributed primarily to overfishing, pollution, and the Lessepsian invasion. As the region is listed among the fastest-warming areas, enlightening the impact of rising temperature on fish populations is essential. Within this context, we hypothesized that the large-scale climate indices might explain the changes in the abundance of exploited fish populations on the south coast of Turkey. We aimed to measure the responsiveness of catch per unit effort (CPUE) to North Atlantic Oscillation Winter Index (NAO DJFM) and East Atlantic-West Russia (EA/WR) seasonal indices. For that purpose, official landing and fishing fleet statistics were reported by the Turkish Statistical Institute (TUİK) compiled for 1987 and 2020. Landings of fish species are categorized regarding the fishing practice targeting them. The total number of fishing vessels is used to calculate the annual CPUEs of trawlers and purse seiners. To investigate the relationship between climate indices and variations in CPUEs, cross-correlation analysis incorporating the differencing and pre-whitening methods has been performed. In general, CPUE of trawlers was significantly affected by NAO DJFM and EA/WR indices, while CPUE of purse seiners was significantly correlated only with EA/WR Winter Index. Considering the role of the EA/WR pattern on precipitation and NAO teleconnection on temperatures, the large-scale climate indices seem to impact the reproductive success and growth of the fish populations. Our results indicated that the large-scale climate indices have great potential to explain particular patterns of CPUEs. However, other, drivers such as fisheries and eutrophication that are probably acting in combination with climate must be included in the future studies.


Catch per unit effort, Fisheries, Marine climate change, Northeastern Mediterranean Sea, Climate indices

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