Tuna

Tuna (pl.: tunas or tuna) are saltwater fish belonging to the tribe Thunnini, a subgrouping of the Scombridae (mackerel) family. The Thunnini comprise 15 species across five genera, the sizes of which vary from the bullet tuna (max length: 50 cm or 1.6 ft, weight: 1.8 kg or 4 lb) to the Atlantic bluefin tuna (max length: 4.6 m or 15 ft, weight: 684 kg or 1,508 lb), which averages 2 m (6.6 ft) and is believed to live up to 50 years. Tuna, opah, and mackerel sharks are the only species of fish that can maintain a body temperature higher than that of the surrounding water. An active and agile predator, the tuna has a sleek, streamlined body, and is among the fastest-swimming pelagic fish — the yellowfin tuna, for example, is capable of speeds of up to 75 km/h (47 mph). Found in warmer seas, the tuna is commercially fished extensively as a food fish, and is popular as a bluewater game fish. As a result of overfishing, some tuna species, such as the southern bluefin tuna, are threatened with extinction.