The tropical tuna purse seine fishery exploiting skipjack (Katsuwonus pelamis), bigeye (Thunnus obesus), and yellowfin tuna (Thunnus albacares) is one of the most important fisheries worldwide and catches tuna as either free-swimming schools or when associated to floating objects. Considering the increasing global demand for tuna, it is vital to assess the impact of the fishery on marine ecosystems. Using observer data for the Spanish fleet in the Atlantic and Indian Ocean between 2003 and 2021, the Primary Production Required to sustain fisheries, the Mean Trophic Level, and Mean Size of the Catch were calculated. Satellite-derived estimates of Net Primary Productivity and Primary Production Required showed an increased spatial coupling over time suggesting an expansion of the fishery into more productive waters. A temporal decrease of Primary Production Required in areas of sustained fishing effort due to decline in the Mean Trophic Level and Mean Size of the Catch was partially supported. Floating objects appropriated more Primary Production Required while the Mean Trophic Level and Mean Size of the Catch was higher for free-swimming schools. This provides useful information regarding the ecological effects and evolution of the fishery and emphasizes the need for an ecosystem-based approach to fisheries management.
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