Atlantic bluefin tuna
Atlantic bluefin tuna / Northern bluefin tuna
Atlantic Ocean, Gulf of Mexico, Mediterranean Sea
Overfished (IUCN data deficient)
Adults are typically 3m in length, but can reach 4m, making the Atlantic tuna one of the largest bony fishes and the largest of all tuna species. Adults average 130-680kg, although the upper weight range is rarer now.
Bluefin tuna are built like torpedoes. Not only do they have a hydrodynamic shape, their pectoral (side) fins can be retracted and, unlike other fish, their eyes are set flush to their body. This means their bodies create little drag as they swim through water.
Habitat and Distribution
There are 2 populations of Atlantic bluefin tuna: a smaller western population which spawns in the Gulf of Mexico, and a larger eastern population which spawns in the Mediterranean Sea.
These 2 populations are not completely separate, however. Adults and juveniles from both populations feed together, particularly off the east coast of North America and in the central Atlantic.
Atlantic bluefin tuna spawn just once a year and do not reach reproductive maturity until they are 8-12 years old. This makes bluefin tuna more vulnerable to overfishing than some of the smaller tuna species that can spawn several times in a year. Female Atlantic bluefin can produce up to 10 million eggs per year, but just a small fraction survives to adulthood.