It is a large species of bony fish with a round body which possesses gill rakers, a swim bladder, and two dorsal fins. The second dorsal fin and the anal fin are notably long. Its underside or belly is yellow and silver that changes colour to a metallic dark blue at the back. Its dorsal and anal fins are bright yellow, hence its name. They grow fast, have high fecundity and are an important commercial resource.
The yellowfin tuna is epipelagic and an oceanic species, present worldwide across tropical and subtropical regions. It is found above and below the thermocline (a region of changing water temperature) and can be found at depths of about 400m. It is, however, very responsive to oxygen concentrations and mainly found at 250m deep.
It is panmictic, and therefore, able to breed with individuals from any population randomly without any genetic, behavioural or environmental hurdle.
Its diet consists of fish, squid and crustaceans. Conspecific assembly can be observed, or individuals are also found in multispecies assemblages. Spawning occurs year-round but there are peaks during summer months.
The Thunnus albacares is listed as ‘Near Threatened’ according to the IUCN Red list. Overfishing, especially in the Indian Ocean is one of the biggest threats to this species, unless the maximum sustainable yield threshold is respected, in which case populations could recover.