Atlantic bluefin tuna

How it lives

Atlantic bluefin are fast, warm-bodied hunters that school by size. The eastern stock spawns in the western Mediterranean and the western stock in the Gulf of Mexico. Spawning is mostly June to August, and eggs hatch after about 2 days. The oldest age reported by FishBase is 32 years. Large fish tagged in Skagerrak all belonged genetically to the Mediterranean population.

Where it goes

Very long. In a 2022 study, fish tagged in Skagerrak covered 16,000 to 25,900 km while tracked, one over 22,000 km, and two returned to the tagging region after 359 and 365 days. They stayed 2 to 38 days in Skagerrak before leaving, mostly mid-September to late October. A later study of 25 fish tagged off Norway found that every fish with a full-year track returned to Norwegian waters. Fifteen of them entered the Mediterranean between 4 and 30 May, and one dived to about 1,190 m. In Danish and Swedish waters tuna are typically present from August to October.

We only draw a journey on the map when scientists have tracked it or clearly documented it. For this animal we have not found one yet.

Populations

IUCN moved the species from Endangered to Least Concern in 2021. The larger eastern population, which spawns in the Mediterranean, has grown by at least 22% over four decades. The smaller western population, which spawns in the Gulf of Mexico, has fallen by more than half. IUCN credits tighter fishing quotas and action against illegal fishing. In Denmark and Sweden catches fell to almost zero in the early 1960s, and the tuna were absent for more than half a century before returning in about 2015 to 2016.