Bigeye tuna (Thunnus obesus) is distributed throughout the Atlantic Ocean between 50ºN and 45ºS, but not in the Mediterranean Sea. This species swims deeper than other tropical tuna species and exhibits extensive vertical movements. The stock has been exploited in the Atlantic Region by three major gears (longline, bait boat and purse seine fisheries) and many countries throughout its range (ICCAT 2021).

Various pieces of evidence, such as a lack of identified genetic heterogeneity, the time-area distribution of fish and movements of tagged fish, as confirmed by the recent data obtained from the Atlantic Ocean Tropical Tuna Tagging Programme (AOTTP), suggest an Atlantic-wide single stock for this species (ICCAT 2021).