Fishmongers check bluefin tuna before the new year's first auction at the Tsukiji fish market in Tokyo in January. (Toshifumi Kitamura/AFP/Getty Images)

The world's Pacific bluefin tuna won something of a reprieve Friday, when tuna-fishing countries reached an agreement to gradually rebuild severely depleted stocks while still allowing nations such as Japan to catch and consume the delicacy.

Japan — by far the world’s biggest consumer of bluefin, eating about 80 percent of the global haul in the $42 billion tuna industry — had been resisting new rules, while conservationists have warned about the commercial extinction of bluefin in the Pacific Ocean.

Proponents of limits hailed the deal as a compromise that everyone could live with.

"It's definitely a good first step towards the recovery of the species," said James Gibbon, global tuna conservation officer at the Pew Charitable Trusts. "But it is only the first step. There are a lot of commitments that the countries agreed to, and we need to make sure they stick to them."

At the week-long meeting in Busan, South Korea, the two bodies charged with shared management of Pacific bluefin — the northern committee of the Western and Central Pacific Fisheries Commission and the Inter-American Tropical Tuna Commission — hammered out a plan to try to put the fish back on a path to sustainability. Countries represented at the meeting included the United States, Canada, China, South Korea and Japan.

The Pacific bluefin population has been depleted by more than 97 percent from its historic high, because of overfishing.

At the meeting, the two organizations agreed to a target to rebuild tuna stocks to 20 percent of historic levels by 2034, the minimum level that scientists consider necessary to protect the species.

If the chances of meeting the 2034 rebuilding target fall below 60 percent, the parties agreed to immediately reduce their catch levels. Over the next seven years, countries' catch quotas could be increased only if there is a 75 percent chance of meeting the new goal.

The groups also agreed to develop a “catch documentation scheme” by 2020 to try to stop illegally caught Pacific bluefin from entering the international market.

Both Japan and Mexico have exceeded their annual bluefin fishing for the 2017 fishing year, which ended in June, and Japan’s Fisheries Agency estimated that more than 100 tons had been caught illegally or without being reported. Japan’s domestic limits on fishing are entirely voluntary.

"What makes Japan different from many other countries is that Japan has so many small-scale fishermen, and the government hasn't been able to find a way to control them," said Aiko Yamauchi, director of the oceans group at WWF Japan.

Pacific bluefin is particularly prized in Japan for its fatty underbelly, called “otoro,” which sells for as much as $23 per piece at Michelin-starred sushi restaurants in Tokyo.

Chefs at Tokyo's top sushi restaurants are concerned about the prospect of their supplies vanishing.

"Tuna stocks are diminishing, and it's a major problem," said Katsumi Honda, master chef at Irifune, one of Tokyo's most famous raw tuna joints. "Stronger regulations on fishing is the way to go. Prices would most certainly go up, and that would be a big worry for us, but preserving tuna stocks is a good thing for a long term."

But Japanese fishermen have resisted higher limits and tighter regulation.

Going into the meeting, Japan’s Fisheries Agency had contended that replenishment goals could be met through a new rule introduced last year that sought to halve the annual catch of juvenile bluefin, or tuna weighing less than 66 pounds, to increase the egg-laying adult bluefin tuna population.

But Japan had not been sticking to this rule, and its delegates came under sustained pressure from other countries and the Japanese media to agree to the new targets.

That made the new rules imperative, said Yamauchi of WWF. “There’s no other resource that is as terribly depleted as the Pacific bluefin tuna, so there’s no time to wait,” she said.

Japanese authorities have been trying to placate the fishing industry by telling them to agree to the new rules, as there were ways to ease them later, said Toshio Katsukawa, an associate professor at Tokyo University of Marine Science and Technology.

The Japanese fishing industry also has pinned some hopes on President Trump, noting that he does not place a high priority on protecting the environment, he said.

"But if Japan truly wants to protect fishermen, they really should work hard to rebuild the tuna stocks, even if the fishermen had to go through hard times in the process," Katsukawa said. "After all, it's the fishermen who'd be hardest hit if the tuna were wiped out."

Yuki Oda contributed to this report.

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