Details
Thunnus obesus
A large oceanic tuna of tropical and temperate seas, with big eyes, deep-diving habits, and high value for sashimi.
Map: Ecoregions 2017 © RESOLVE (CC BY 4.0) · Natural Earth (PD)
Widespread in warm open waters of the Pacific, Indian, and Atlantic oceans, using deep cool layers by day and shallower water at night.
The body is thick and streamlined, dark blue above and silvery below. The eyes are large, and the pectoral fins are relatively long.
Schools migrate long distances and shift depth strongly between day and night, sometimes gathering near floating objects and seamounts.
It eats fish, squid, and crustaceans, including deep scattering-layer prey such as lanternfish and squid.
Adults broadcast many eggs in warm offshore waters. Growth is rapid, but fishing pressure can strongly affect stocks.
Bigeye tuna is traded as high-quality sashimi fish and requires international management by regional fisheries bodies.
