Large pelagic fish exploitation by longliners in the Atlantic Ocean and Mediterranean Sea: A contribution to spatial planning and sustainable fisheries

Understanding longline fisheries dynamics is crucial for sustainable resource management. This study aims to provide a panorama of the fishing effort of the principal nations that have exploited tuna and associated species in the Atlantic Ocean for the past decade, integrating vessel data from Global Fishing Watch (GFW) and catch data from the International Commission for the Conservation of Atlantic Tunas (ICAAT), with specific information on the production of these different fleets and resources. Twelve nations represented 94.6 % of all Apparent fishing hours (AFH) of the total effort in the Atlantic Ocean and 99.9 % of all catches in the last years. Our study revealed that regions proximate to the continental shelf break and oceanic islands exhibit notably higher fishing effort than other areas within the Atlantic Ocean. We also highlight a declining trend in fishing efforts in the last ten years, likely due to regulation and overfishing. The blue shark (Prionace glauca) was the most caught species in biomass, representing 38.1 %; bigeye tuna (Thunnus obesus) represented 20.5 %; swordfish (Xiphias gladius) 15.1 %; albacore tuna (Thunnus alalunga) 11.3 %, and yellowfin tuna (Thunnus albacares) 6.1 %. The alarming trends in pelagic shark catch emphasise the need for immediate conservation actions. Management strategies should target critical nations, addressing their significant contributions to shark catch. The lack of information on several species and periods highlights the need for comprehensive research and management initiatives.