But it doesn't have to be confusing. That's part of why the latest cross-sectional report from the International Union for the Conservation of Nature (IUCN) on threat levels for billfish and scombrid species was greeted with relief when it arrived at HuffPost Food HQ. (Tuna is a sub-class of scombrids, which also include bonito, mackerel and Spanish mackerel.) Its data on tuna threat levels are both more comprehensive and more fine-grained than data at the better-known Monterey Bay Aquarium.
The IUCN report indicates that five of the eight species in the Thunnus species, which comprise the eight major varieties of tuna, are threatened with extinction. The two species facing the greatest threats are the Atlantic bluefin (Thunnus tynnus) and the southern bluefin (Thunnus maccoyii), which the IUCN rated endangered and critically endangered respectively. The report classified albacore (Thunnus alalunga) and yellowfin (Thunnus albacares) tuna as near threatened and bigeye (Thunnus obesus) tuna as vulnerable. (Vulnerable is the classification between "near threatened" and "endangered" on the IUCN red list.) Longtail (Thunnus tonggol) tuna are said to be data deficient, while blackfin (Thunnus atalanticus) and Pacific bluefin (Thunnus orientalis) tuna fall under the category "Least Concern."
None of this is great news; at least five, and possibly six, of the eight species of tuna are at risk of extinction, largely because of overfishing. But the resilience of stocks of blackfin and Pacific bluefin tuna is at least heartening. And the report also noted that many species closely related to the major tuna genus, such as skipjack and bonito, are still relatively plentiful. This won't do anything to help the southern bluefin recover; with populations just 5% of what they would be without fishing, it may be too late for them. But it does mean that, if conservation begins soon, we may not lose the last wild food forever.