| Summary: | Pelagic migrating sharks are by-caught incidentally in longline fisheries. Some of these species have been catalogued as threatened or vulnerable by several Regional Fisheries Organizations and International Conservational NGOs. Alboran Sea is an important area for pelagic migrating sharks because it is the natural and unique communication way between the Atlantic Ocean and Mediterranean Sea. This area is considered by several authors as a hot-spot of Climate Oscillation, such as the North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO). In addition, Alboran Sea is an important fishing ground where the longline fisheries targeting swordfish operates. Recent studies concluded that historical landing of pelagic sharks from harbours of Alboran Sea and Balearic Sea were mediated for atmospheric oscillations. The main aim of the present study was to assess the effect of atmospheric oscillation on the Catch per Unit Effort (CPUE) of vulnerable sharks thresher shark, Alopias vulpinus (Bonnaterre, 1788) and shortfin mako, Isurus oxyrinchus (Rafinesque, 1810) by-caught in the traditional longline fisheries. The atmospheric oscillations tested in this study were the North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO). We found a significant positive correlation between the NAO and AO indexes of the previous year to the CPUE tested.
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