Bluefin tuna is the common name for several large, migratory tuna species prized for their rich, buttery flesh, most importantly Atlantic bluefin (Thunnus thynnus) and Pacific bluefin (Thunnus orientalis) — distinct species despite the shared name and similar appearance. Atlantic bluefin is native to the Atlantic Ocean and Mediterranean Sea; Pacific bluefin to the temperate Pacific.
Bluefin tuna's meat is bright red, firm, and dense, with a high fat content that includes prized fatty cuts like toro from the belly. It's central to Japanese sushi and sashimi, and is also grilled, seared, broiled, or served raw as carpaccio outside Japan.
Demand for bluefin, especially for sushi-grade toro, has driven serious overfishing; international quotas and management plans now restrict catches, and Atlantic and Southern bluefin populations in particular have faced conservation concern, keeping prices high and availability limited in some markets.