Activists who have clashed violently with Japanese whalers in Antarctic waters in recent months were headed back to port Tuesday because they were running out of fuel.
The Sea Shepherd Conservation Society ship Steve Irwin was leaving the hunting region for this season, which is due to end in less than two weeks, the group said on its Web site.
Last week, activists hurled rancid butter at a Japanese whaler, which responded with so-called flash-bang grenades, which create a loud noise but scatter no shrapnel.
Sea Shepherd captain Paul Watson said he had been shot but not wounded during the encounter. Japan denied he was shot.
In January, two Sea Shepherd activists boarded a Japanese harpoon ship and spent several days in detention before they were picked up by Australian Customs officers.
The activist group vows to do anything short of causing injury to stop Japan's annual whale kill, which critics say skirts an international moratorium on whaling by justifying the hunt on scientific grounds.
Sea Shepherd claimed the whalers had not killed any animals since at least Feb. 23 and that its campaign had succeeded in curtailing the Japanese program, which had targeted about 1,000 whales.
"We've done everything we can do down here for this season, and it has been an enormous success," Watson said, claiming to have saved more than 500 whales. Japan has not made public the numbers of whales killed.
Waston also rejected a rebuke from the International Whaling Commission, which at a meeting in London last week accused the group for "jeopardizing safety at sea" and urged it to drop dangerous tactics.
"While they were in London talking about whales, we were down here actually protecting the whales," Watson said. "So they can condemn us until the cows come home, but I think we served our clients, the whales, as best we could, and every whale's life saved has been a victory for us.