Bigeye Tuna

Bigeye tuna can grow up to 2.5 m (98 in; 8.2 ft) in length. Maximum weight of individuals probably exceeds 180 kg (400 lb), with the all-tackle angling record standing at 178 kg (392 lb 7 oz). They are large, deep-bodied, streamlined fish with large heads and eyes. The pectoral fins are very long, reaching back beyond the start of the second dorsal fin in juveniles and the space between the first and second dorsal fin in adults. They have 13 or 14 dorsal spines.

Bigeye tuna primarily feed on epipelagic and mesopelagic fish, crustaceans and cephalopods.

Conventional tagging data and counts of growth increments in otoliths (ear bones) of bigeye tuna have recorded a maximum age of 16 years. Recorded lengths at which sexual maturity is attained varies geographically with a length at which 50% of fishes sampled are mature of 135 cm (53 in) in the eastern Pacific Ocean and 102–105 cm (40–41 in) in the western Pacific Ocean. This translates to an age of maturity of 2–4 years. Differences in methods of studies may contribute to this variability. Spawning takes place across most months of the year in tropical regions of the Pacific Ocean, becoming seasonal at higher latitudes when sea surface temperatures are above 24 °C (75 °F). In the northwestern tropical Atlantic spawning occurs in June and July, and in January and February in the Gulf of Guinea, which is the only known Atlantic nursery area.