Bluefin tuna are being hunted to extinction. They have already been reduced to a small fraction of the global numbers of a hundred ago. They may disappear from the Atlantic Ocean by 2012. The average weight of those caught has already been dropping. Other kinds of tuna and related fish are also being slaughtered, but the bluefish will be the first to go under.
Bluefin tuna are the genus Thunnus in the family Scombridae, with several species, among them Thunnus atlanticus (blackfin tuna), Thunnus orientalis (Pacific bluefin), and Thunnus thynnus (Northern bluefin).
The bluefin have a big problem: they taste very good. Tuna have been eaten for centuries. Indeed, the word “tuna” comes from ancient Greek. Canned tuna greatly increased the consumption, but what is finally terminating the bluefin is sushi. Four fifths of the bluefin tuna consumption is for sushi and sashimi. Sushi is seaweed-coated vinegar rice wrapped around a morsel of food such as raw fish, and sashimi is the raw fish by itself.
Bluefin tunas taste good because unlike most fish, they are homeothermic (warm blooded); they metabolize their temperature, like mammals and birds. With a higher body temperature than the surrounding cold water, tuna have a large ocean range. The warmth also enables tuna to swim fast (“tuna” in Greek means “to rush”), which enables them to catch more prey. So bluefin tuna grow up to a size of up to four meters.
Their warm bodies produce a red fatty underbelly called “toro” in Japanese. While the Spanish cry “toro!” when a bull charges, Japanese consumers call “toro!” for the delicious uncooked fatty parts of bluefin sushi and sashimi.
Traditional sushi was made of fermented fish and rice. The word “sushi” meant “it is sour.” Today’s sushi is not fermented, and can be made quickly. It is Japanese fast food. While there is a tiny health risk from eating raw fish, the bigger danger is the mercury in large fish such as tuna, which are at the top of the food chain, just below man. But the mercury has not stopped people from gobbling tuna world-wide. The problem of parasites in raw fish is solved by freezing the fish and then thawing it so that it seems raw again.
In Europe and elsewhere there are now so-called tuna “ranches.” They don’t really raise the tuna as in real ranches; they hunt wild tuna and then keep them in circular nets. These menageries feed the tuna sardines and other fish to get them big and fat. When the wild tuna are caught, they include young ones that don’t grow up to make other tuna, so this “ranching” is quickly depleting the stock of tuna, especially the bluefin. Baby’s a tuna, and it’s feeling blue!
It is possible to completely farm-raise tuna; this has been successfully tested in Kinki University in Japan. Evidently they managed to remove the kinks from raising tuna, and an Australian university has now also bred tuna in captivity.
Because of the high demand, a bluefish tuna can sell for $100,000 in Japan. The depletion of Bluefin tuna is a prime example of what is called the “tragedy of the commons.” The oceans are a common natural resource, with nothing to stop fishers from catching unlimited amounts of seafood. There are international rules and organizations that have jurisdiction in the oceans, such as the International Commission for the Conservation of Atlantic Tunas and the Commission for the Conservation of Southern Bluefin Tuna.
Unfortunately for the Atlantic tuna, the limits set by ICCAT are too high for sustainability, and the restrictions are not being enforced. About half the bluefin catch is not reported. The members of ICCAT have not authorized the organization to catch and punish the poachers.
Wild tuna are economic land, a natural resource. They are a common heritage that should be preserved, hunting only taking the annual increase, like consuming only the interest from savings. When fishers take the tuna with no compensation to humanity for depletion, they are in effect stealing land that belongs to humanity, including future generations.
Bluefin tuna should be classified as endangered, with sustainable limits to the catch, and the payment of fees that would finance the enforcement. Ecologically sound tuna farming should be promoted to replace wild tuna, and biologists could experiment with producing tuna flesh synthetically, avoiding having to raise the fish.
The depletion of bluefin tuna is a prime example of massive government failure, the refusal of governments to establish and enforce humanity’s property rights in renewable natural resources. Tuna fishers are in effect getting short-term subsidies, as they are granted an exemption from paying the social cost of their activity.
What can we do? We can contribute to organizations such as the WWF (World Wildlife Fund or World Wide Fund For Nature) or the Tuna Research and Conservation Center in California. We can contact government representatives to create pressure to preserve the ocean wildlife. We can also ask food stores and restaurants to either not sell bluefin tuna or to inform customers that the bluefin are endangered.
[Editor’s note: this essay first appeared on Dr. Foldvary’s blog, the Foldvarium, on Jan 17 2010]