In a stunning setback to the dolphin hunt in Taiji, the Japanese Association of Zoos and Aquariums on Wednesday banned its members from acquiring animals captured during the annual slaughter.

Of the country’s 54 aquariums that house dolphins, 17 are non-JAZA members and are not bound by the decision. Aquariums from at least 20 foreign countries also acquire dolphins from Taiji. Meanwhile, it’s not clear if the JAZA ban extends to dolphins caught in places other than Taiji.

Still, the move is a big blow to the live-animal trade in Taiji. About 40 percent of all dolphins caught there are sent to aquariums in Japan, according to Sarah Lucas, chief executive of Australia for Dolphins. Nearly half of the dolphins in Japanese aquariums, meanwhile, may have been taken from Taiji.

"JAZA will prohibit its members to acquire wild dolphins caught by drive fishing in Taiji and to take part in their export and sale,” the group’s chairman, Kazutoshi Arai, said at a news conference on Wednesday.

Scientists and activists applauded the move.

“This is a huge victory for the dolphins,” Ric O’Barry, director of Ric O’Barry’s Dolphin Project and star of the Oscar-winning documentary on Taiji, The Cove, said in an email. “And it's another nail in the coffin for the annual dolphin slaughter. We must be vigilant however. We will monitor the captures very carefully this year as usual.”

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Last month, the World Association of Zoos and Aquariums suspended the Japanese group’s membership for failure "to adhere to policies that prohibit participating in cruel and non-selective methods of taking animals from the wild."

The global organization was set to expel JAZA on Thursday if the Japanese didn’t take action.

“WAZA considers JAZA’s decision to be a welcome breakthrough and looks forward to receiving further details from JAZA in order to fully appreciate the implications of today’s decision,” the group said in a statement.

Diana Reiss, a marine mammal scientist and a psychology professor at Hunter College in New York, said she and other scientists and industry insiders had been working with JAZA and WAZA to bring about such a ban since 2004.

“It’s amazing and important news,” Reiss said. “What’s really terrific and critical about this decision is that it came from within Japan’s zoological community…which says that this needs to stop.”

JAZA’s decision, which was approved by a 142–43 vote of its members, came after years of negotiations with and pressure from WAZA.

The Taiji drives, where entire pods are forced into a small cove and then slaughtered, released, or captured and sold to aquariums for up to $150,000 apiece, has been the focus of enormous international opposition for years.

But Arai made it clear that JAZA was not rejecting drive hunts altogether.

"We do not think it is cruel to take wild dolphins...but as we have reached this kind of conclusion in relation to WAZA, we need to steer [our policy] toward breeding," Arai said.

Ramping up Japan’s captive breeding efforts will be difficult. Many aquariums are too small to house breeding pools, and only about 13 percent of aquarium dolphins in Japan were bred in captivity, compared with about 70 percent in the United States, according to Arai.

Arai estimated it could take “five years or more" to establish adequate breeding skills in Japan. Failing that, “some aquariums could eventually face difficulty operating as they may not be able to find an alternative source of dolphins,” the Japanese newspaper Mainichi reported.

Possible loopholes in the new ban have some critics concerned.

“They say they will no longer capture dolphins in Taiji, but it’s not clear whether they’re going to capture dolphins in other places or not,” Reiss said. “This needs to be clarified with JAZA.” Moreover, non-JAZA aquariums presumably will continue buying dolphins from Taiji.

“JAZA’s decision…is a big step, and one that will hopefully contribute to an end to these hunts,” Courtney Vail, program and campaigns manager for Whale and Dolphin Conservation, said in an email. “We must still be concerned, however, with all wild captures. As long as zoo and aquaria keep the door open for acquisition from the wild, dolphins will suffer.”