Atlantic bluefin tuna

The Atlantic bluefin tuna is the largest kind of tuna. It lives in the Atlantic Ocean and the Mediterranean Sea, and it is a powerful, streamlined swimmer. Animals as big as 680 kilograms have been recorded, although most are much smaller.

Bluefins travel in schools and make huge migrations. A tracking study found that they can cross the whole Atlantic in 40 to 60 days. Their speed, size and strength have made them a favourite of anglers, writers and scientists, and also a very valuable catch for fishing fleets. Its flesh is highly prized, so the species has been at the centre of a very valuable fishing industry for a long time.

Where does it live and what does it eat?

Bluefins are found in the temperate and subtropical Atlantic and in the Mediterranean, and they can dive to about 1,000 metres. They are fast hunters of fish and other prey. The species disappeared from the Black Sea because of overfishing, although it has recently been seen moving into waters near Norway and Ireland.

Records show some individuals reaching 680 kilograms, and the species is a fast, strong swimmer; our card gives a top speed of about 70 km/h. Bluefin cross the Atlantic by following temperature and food, and the card notes they keep their bodies warmer than the cold water around them.

Is it in danger?

Because bluefin is so prized for sushi and sashimi, it has been heavily fished. In 2009 the international commission that watches Atlantic tuna reported that stocks had fallen by 72 percent in the eastern Atlantic and 82 percent in the western Atlantic over about 40 years.

Fishing limits were discussed internationally after that report, and today the IUCN lists the species as Least Concern, but scientists keep watching the numbers. The international fight over how much bluefin can be caught shows how hard it is to protect a fish that swims across many countries' waters.

On the globe

The model shows a big, torpedo-shaped bluefin tuna swimming through open water.