SYDNEY—The anti-whaling ship Steve Irwin has stopped its pursuit of the Japanese whaling fleet in the Southern Ocean to return to port for refuelling.
The Shepherd Conservation Society vessel's captain, Paul Watson, said the Irwin's efforts so far had been successful in stopping the Japanese whale hunt.
"We have engaged them, we have stopped their whaling activities for two weeks and we have successfully chased them out of the Australian Antarctic Territorial waters," he said in a statement.
"We now have to return to land to refuel.
"We don't have the luxury of refuelling at sea like the Japanese fleet has," Capt Watson said.
"We don't have the resources to operate two ships down here and we don't have the support of Greenpeace to relieve us.
"We are doing the best we can with the resources available to us and we are having a significant impact on their kills."
The Steve Irwin had chased the Japanese fleet for two weeks and for more than 3,000km from the extreme Western end of their hunting territory near Commonwealth Bay in the Australian Antarctic Territory, to the Eastern side of the Ross Sea, Capt Watson said.
The vessel would now return to the nearest available port to refuel before heading back out in pursuit of the fleet again as quickly as possible, he said.
The Institute of Cetacean Research (ICR) in Tokyo last week accused Sea Shepherd activists on the Steve Irwin of launching an attack on the whale-spotting vessel Kaiko Maru, just after it had completed a day of research activities.
The ICR said protesters from the Steve Irwin threw about 15 bottles of acid and bottles containing a bluish-green liquid at their vessel on December 27.
It also accused the activists of engaging in several hours of dangerous close harassment and of ramming the Kaiko Maru.
Capt Watson said the Steve Irwin got close enough to throw around 10 bottles of rotten butter and 15 of a mixture of methyl cellulose and indelible dye at the Japanese ship during an encounter in which the two vessels struck each other without causing serious damage.
Sea Shepherd said it was behaving legally and accused the whaling ship of entering Australia's economic exclusion zone.
The Japanese whaling fleet plans to kill about 1,000 whales this summer, using a loophole in a 1986 global whaling moratorium that allows "lethal research" on the ocean giants.
The Australian Government has appealed for calm on the high seas.