From the Associated Press by Tanalee Smith

ADELAIDE, Australia – Anti-whaling activists on Friday cut short what they called their “most successful” Antarctic campaign against Japanese whalers, citing an engine problem on one of their ships.

There are two weeks left in the three-month whaling season, during which Japan sends its six-vessel whaling fleet into Antarctic waters as part of a research program, an allowed exception to the International Whaling Commission’s 1986 ban on commercial whaling.

Paul Watson, founder of the U.S.-based Sea Shepherd group that confronts the whalers each year, said in a statement Thursday that he had ordered the Bob Barker vessel to stop pursuing the Japanese and set a course for Tasmania. He said the vessel had a fuel valve problem that could cause an engine breakdown.

Watson said his group had had its best season ever, adding that the Japanese had not been able to kill a whale for three weeks thanks to Sea Shepherd’s efforts. The protest vessels had closely tailed the Japanese fleet of harpoon and factory vessels, which generally travel together, since late January.

“We’ve hurt the Japanese whaling fleet more this year than any year before,” Watson said. “This has been our most successful campaign in the six-year history of our interventions in the Southern Ocean Whale Sanctuary. We have done the best job possible with the resources available to us, and I am confident that we have prevented the slaughter of hundreds of whales.”

He said the Sea Shepherd’s effort this season “spells financial disaster for Japan’s whaling fleet.”

There was no immediate reaction from Japan.

Japan hunts hundreds of mostly whales in the Antarctic annually, with a maximum quota of 935 minke and 50 finback whales. Whale meat not used for study is sold for consumption in Japan, which critics say is the real reason for the hunts.

During each whaling season, in the southern hemisphere summer, Sea Shepherd activists try to block the whalers from firing harpoons and dangling ropes in the water to try to snarl their ships’ propellers. They also hurl packets of stinking rancid butter at their rivals. The whalers have responded by firing water cannons and sonar devices meant to disorient the activists. Collisions have occurred occasionally.

Earlier this month, activist Peter Bethune of New Zealand jumped aboard one of the Japanese ships with the stated goal of making a citizen’s arrest of the ship’s captain, while handing over a $3 million bill for the destruction of his protest ship last month. He is being held on the ship as it returns to Japan, where he may face charges of intrusion.

Watson said the Sea Shepherd will be arranging a legal defense for Bethune.