Tuna Trouble: Several Species of Tuna Threatened from Overexploitation

(Tuna for sale at Tsukiji fish market. By tacoekkel via Flickr)

What marine species are endangered? Well, tuna are in trouble, according to a recent assessment. The group responsible for labeling how marine animals are faring looked at eight tuna species and deemed that five of them are threatened or close to it.

The group, a part of the International Union for the Conservation of Nature, the largest global conservation network, judged the status of 61 fish species in total. The fish included tunas, bonitos, mackerels, swordfish and marlins, many of which face overexploitation. Their final classifications were published in Science and are a big step in conservation awareness. Many of the species didn't have labels before.

To find out how each species was doing, the group examined data on population, distribution, habitat, trends, and major threats. Major threats to the survival of fish populations include overfishing, bad fishing practices, invasive species, pollution, and disease. Using these criteria to assess the current state of the fish, the group then labeled each species according to how much trouble they are in. Here are the results for the five tuna that made that caution list:

-Southern Bluefin (critically endangered)
-Atlantic Bluefin (endangered)
-Bigeye (vulnerable)
-Yellowfin (Near Threatened)
-Albacore (Near Threatened).

Tuna are especially in danger because they’re in high demand. Since they sell at high market prices, there’s little external pressure to protect the population from overfishing. Tuna also have longer life spans than other fish, so they mature and reproduce at a later age. If a tuna population is dramatically reduced, then it can take a long time for it to bounce back. "All three bluefin tuna species are susceptible to collapse under continued excessive fishing pressure,” said Kent Carpenter, a manager at the IUCN and an author of the paper, in a statement.

Despite the new labels, the scientists do think there is some hope. To prevent collapse in some species, the scientists stress that the fisheries should be shut down entirely until the populations have time to rebound. However, they understand that that’s not the most economically viable option, since it would put the livelihoods of those in the fishing world in danger as well as trigger illegal fishing.

But even without such extreme measures, fish populations can be saved from their population plummets with smart management plans. Regulating how many fish can be caught and employing law enforcement to make sure those caps are followed can protect wildlife and promote sustainability. The strategy worked for swordfish, in addition to some local populations of tuna, say the scientists.

The Global Marine Species Assessment hopes to label 20,000 marine species by their risk of extinction. They’ve also looked at marine mammals, mangroves, corals, crustaceans, and many others.

The Red List of Endangered Species can be found here.

You can do your part to protect threatened fish by being an informed consumer: use fish buying guides.

Also read:
Guilt-Free Fish: How to eat your seafood and have it, too.
For the Love of Fish. Farmed or wild?