Also known as Thunnus thynnus, belongs to the largest group of tuna and has been observed on occasions in Swedish waters. This species is strictly protected.

The tuna thrives in the open sea, often at depths down to 500 meters, in both the North Atlantic and the North Pacific. During the summer period, it can rarely be seen along the Swedish west coast and has also been reported further south, right down to Öresund and the southern Baltic Sea.

Historically, the tuna was a common sight along the Swedish west coast during the 1930s and 1950s. But since the 1970s, it has become a rarer guest in our waters. In recent years, however, tuna have started to return to Swedish coastal areas, probably as a result of successful management and recovery efforts, especially in the Mediterranean.

It appears that reduced fishing pressure in the Mediterranean, together with migration patterns of its prey fish, particularly herring and mackerel, have contributed to the return of tuna along our coasts. It is worth noting that the species is still red-listed by the IUCN due to the uncertainty surrounding the size and distribution of its population.