Some varieties of tuna , such as the bluefin and bigeye tuna , Thunnus obesus , are threatened by overfishing , which dramatically affects tuna populations in the LOCATION@1 and northwestern Pacific Oceans .

Some varieties of tuna , such as the bluefin and bigeye tuna are threatened by overfishing , dramatically affecting tuna populations in the LOCATION@1 and northwestern Pacific Oceans .
