A warm-blooded ocean giant capable of transoceanic migrations, the most prized fish at Tokyo's tuna auctions.
Where it lives
Atlantic bluefin range from the tropical Atlantic to the cool waters of Newfoundland and Norway, and they enter the Mediterranean to spawn. Pacific and southern bluefin (separate species) make similar transoceanic migrations. Bluefin can dive over 1000 m yet thermoregulate to remain active in cold water.
How to recognise it
A massive, deep-bodied tuna with a dark metallic blue back, silvery flanks, and short pectoral fins that do not reach past the rear of the first dorsal. Yellow and black finlets line the back and belly before the lunate tail. The body is built around enormous red muscle blocks fed by countercurrent heat exchangers.
Diet & behavior
Bluefin tuna are apex pelagic hunters that chase schools of herring, mackerel, squid, and small tuna at high speed. They form mixed-age schools that cross entire oceans on annual spawning migrations.
Fisheries & Conservation
Recently reclassified as Least Concern after decades of conservation effort, but Atlantic stocks remain a fraction of their historical biomass. Single fish at Tsukiji and Toyosu have sold for over $3 million.