Japanese whaling fleets have returned from Antarctica with 333 butchered bodies of minke whales in what officials are calling “ecological research.” Labeling the whale kill as science is a way to dodge a global hunting moratorium protecting the giant mammals, rights groups say.

Groups are exempt from the 1986 international ban on commercial whaling if they say they are doing so for research. Specifically, Japanese officials called the killings “research for the purpose of studying the ecological system in the Antarctic Sea,” Agence France-Presse reported Friday. Opponents of the program say it’s a cover for commercial whaling. The Japanese fleets sell the whales they’ve killed for food.

“It is an obscene cruelty in the name of science that must end,” said Kitty Block, executive vice president of Humane Society International. “There is no robust scientific case for slaughtering whales.”

But officials also insist that eating whale meat is part of Japan’s culture — though the meal is losing popularity — and they hope to resume full-on commercial whaling in the future.

Japan has faced international protests over the hunts, and Sea Shepherd activists have confronted the fleets at sea in an effort to protect the whales. In January, Australia said it was “deeply disappointed” that Japan continued its hunt after what seemed to be a positive meeting on the issue between Prime Ministers Malcolm Turnbull and Shinzo Abe, Reuters reported.

Authorities argue that fleet workers are tracking scientific information about the animals such as size and weight, and the data collected now will be used to prove that the world’s whale population can survive hunts.

The International Court of Justice ruled in 2014 that the kills by the Japanese vessels were not research. But the hunts continued last year, after the number of whales taken was cut back. The 333 killed this year is the five-ship fleet’s entire quota following an 83-day hunt.

Norway and Iceland still hunt whales, though the meat in both countries is increasingly unpopular there as well, reports Smithsonian.com.