A Crusade Throughout the World’s Oceans: Genetic Evidence of the Southern Bluefin Tuna Thunnus maccoyii and the Pacific Bluefin Tuna Thunnus orientalis in Brazilian Waters

The large pelagic species play an important role in transferring energy in vast distant marine ecoregions. Results obtained report on extraordinary findings of important commercial species in southeast-south Brazilian waters, including the Southern bluefin tuna <i>Thunnus maccoyii</i> and the Pacific bluefin tuna <i>Thunnus orientalis,</i> an endemic species from the Pacific Ocean. These specimens were identified within the genomic description of 10 individuals randomly selected from the catch to evaluate the catch composition of pelagic longline fisheries off Brazilian waters. Most of the records were from <i>T. maccoyii</i> (6), followed by the Bigeye tuna <i>T. obesus</i> (2), Yellowfin tuna <i>T. albacares</i> (1), and <i>T. orientalis</i> (1). Yellowfin and Bigeye tuna are expected to be captured in the vicinity of the longline fishing areas. However, the unlikely presence of the cold-water <i>T. maccoyii</i> and the warm-water <i>T. orientalis</i> suggests a long migration from common species ranges that could be influenced by climate change. These results imply a readjustment of spatial management structures for these species.