Abstract

Atlantic bluefin tuna (Thunnus thynnus) are highly migratory and are broadly distributed throughout the temperate waters of the Atlantic Ocean. Historically, the species was viewed as two distinct populations, with the eastern population hypothesized to spawn in the Mediterranean Sea and the western population known to spawn in the Gulf of Mexico (GoM). However, recent scientific advances indicate mixing in foraging areas between the two populations (Block et al. 2005, Rooker et al. 2008). The GOM is a critical spawning ground for bluefin tuna; therefore, targeted fishing for these fish is restricted in the GOM, although they continue to be caught as bycatch on pelagic longlines targeting yellowfin tuna (Thunnus albacares) and swordfish (Xiphias gladius). Moreover, the ecological effects from the 2010 Deepwater Horizon oil spill are difficult to assess and remain unclear, but it is likely that the health of pelagic fishes, including bluefin tuna, was significantly affected. For instance, Hazen et al. (2016) demonstrated significant spatial overlap between bluefin tuna spawning habitat (eggs, larvae, and adults) and oiled surface waters. Together, these factors have increased the vulnerability of bluefin tuna to overexploitation. To mitigate this concern, NOAA Fisheries’ Restoration Center recently initiated the “Bluefin Tuna Restoration Project.”