| Summary: | Tunas and related species are considered Highly Migratory Pelagic animals (HMP) with a high fisheries interest and an important commercial value. Many authors have highlighted the effect of climatic oscillation such as NAO (North Atlantic Oscillation) and AO (Arctic Oscillation) on HMP. In this paper we analyzed the differential effect of these oscillations on three HMP: albacore (Thunnus alalunga), yellowfin tuna (Thunnus albacares) and swordfish (Xiphias gladius). Fisheries data for the Spanish fleet from North Atlantic area were obtained from International Commission for the Conservation of Atlantic Tunas (ICCAT). Data since 1950 for albacore, 1962 for yellowfin tuna and 1950 for swordfish, from different gears: troll (TROL), purse seine (PS), longline (LL) and bait boat (BB) were analyzed. We used the nonparametric test U Mann Whitney to test the relationships between species, gear and oscillation phases (positive or negative) of NAO and AO. Our results indicated that the landings of albacore caught with TROL increased with the positive phase of AO and AOw. The landing of swordfish caught with LL in the North Atlantic and Mediterranean Sea significantly increased with the positive phase of AO, AOw, and NAOw. Finally, the landing of yellowfin tuna caught with PS in the East Atlantic increased significantly with the positive phase of NAOw, and LL landing increased with the negative phase of NAOw. The inclusion of the climate effects on the standardization of abundance indexes used in the assessment of HMP could improve its results and catch projections.
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