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People love this toxic fish...and we're eating too much of it

The star of a Japanese dish called fugu is a puffer fish that produces toxins so deadly that it can kill if prepared improperly. Yet the delicacy is so popular that overfishing may be pushing one species of puffer to the brink of extinction, according to a report by an environmental group.

The Chinese puffer, Takifugu chinensis, is one of the top four puffer species used in the dish in Japan, according to the International Union for the Conservation of Nature.

Like most types of puffer, it ingests toxin-producing bacteria that it uses as a defense against predators in the wild. The fish stores these toxins in organs such as the liver—one fish can contain enough toxin to kill up to 30 people.

The IUCN is not connected to a government and doesn't have any regulatory power, but maintains the list as a resource to inform people about species it believes are under siege.

A poisonous delicacy

Japanese chefs typically train to prepare the fish safely, and often need to be licensed. But even with these precautions, accidents happen. In 2011, a two-Michelin-starred Tokyo restaurant served up some fugu that almost killed a diner.

Nevertheless, the fish is prized in Japan and elsewhere for its subtle flavor, and often the dish does not come cheap. A meal at Tokyo's Tsukuji Yamamoto (two Michelin stars) averages about 35,000 yen—roughly $300.

Its popularity is a problem for the fish, though. The UK-based conservation group believes overfishing could eradicate the fish entirely. Last Tuesday the group listed the Chinese puffer as "critically endangered" on its "Red List" of threatened and extinct species.

Data collected by the IUCN show that its numbers have declined 99.9 percent over the last 40 years. In 1969, the total Chinese puffer catch measured around 3600 metric tons, according to statistics from Sekai National Fisheries Institute in Nagasaki and the National Fisheries University in Shimonoseki City. In 1975, the catch shrank to 1600 tons.

By 2008, it hit a single ton.

Part of the problem is that current fishing methods are too effective, said Caroline Pollock, program director for the IUCN's Red List.

"Without too much effort fisherman can take a massive catch, so the populations don't have much of a chance to replenish themselves," Pollock said.

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Another prized species of puffer—Takifugu rubripes, or "tiger puffer"—is "near threatened," but is still in far better shape, according to the IUCN. That species had previously suffered such declines that the Japanese government instituted controls for rebuilding populations in 2005. Stocks had still not fully improved five years later, and some begun farming the puffers to help meet consumer demand.

To combat further declines, the IUCN recommends regulators take a similar course with the Chinese puffer as Japanese officials did with its nearly identical relative, the tiger puffer. They also urge an assessment of the puffer's coastal habitat.

"If exploitation continues at the level it is at, there is a good chance it will be extinct quite quickly," Pollock said. "The species has already undergone massive declines, so there is a good chance there might not be enough left for the species to carry on."

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When the group updated the Red List this year, they noticed that four of the animals they included were all commonly eaten as food, and that human consumption appeared a big factor behind the dropping numbers.

Other edible species on the Red List include the Pacific bluefin tuna, the American eel—which has become a popular substitute for its increasingly scarce Japanese relative—and the Chinese cobra, which is one of the top animals exported to Hong Kong. The province enjoys the snake as a delicacy.

Managing wild fish populations can help species rebound. Fish such as Chilean sea bass and swordfish saw steep declines in their numbers when they became popular delicacies in the 1990s. However, regulators set catch limits and size limits, leading to partial recoveries.

That, in turn, helped keep the fish on the plate.

—By Robert Ferris