An anti-whaling protest ship was taking on water after colliding with a security vessel of the Japanese whaling fleet in the Antarctic, the Sea Shepherd Conservation Society's leader said Wednesday, DPA reported.
Paul Watson said five of the six crew members aboard the high-speed trimaran were rescued and taken aboard an accompanying protest ship, the Bob Barker.
The captain stayed with the 1.5-million-US-dollar Ady Gil, in the hope of saving it from sinking.
"It's taking on water and it's in no position to navigate without a bow," Watson said from the main Sea Shepherd boat, the Steve Irwin. "We were taken by surprise that they (the whalers) would be so aggressive. They weren't doing anything when they were struck by the Shonan Maru 2."
Japan's Institute of Cetacean Research, which supports the whaling programme, blamed the protestors for the collision.
"The Ady Gil came to collision-distance directly in front of the (ship's) bow," the institute said in a statement. "The (ship) started its water cannons and proceeded to prevent the Ady Gil coming closer."
The Ady Gil, capable of a speed of 50 knots (93 kilometres per hour), circled the globe in a record 60 days the vessel was still known as Earthrace. It was renamed Ady Gil after the US multimillionaire who helped buy it for Sea Shepherd.
The boat's hull had been strengthened to handle ice in the Antarctic Ocean and been painted black to deflect radar signals, making it hard for the Japanese fleet to detect.
"The whales are worth more to us than the ships, so we will continue," Watson said. "These are poachers, they are criminals, which is why we've never been prosecuted and why they haven't sued us. We're doing the job that governments ought to be doing."
It was the most serious clash of this year's whaling season between the six-ship Japanese fleet and the three protest boats belonging to Sea Shepherd.
Japan uses a loophole in the 1986 whaling moratorium to continue whaling under the guise of scientific research. According to conservation organization Greenpeace, it has killed more than 9,000 minke whales over the last 22 years.
Watson said Sea Shepherd chased the Japanese fleet for more than 3,200 kilometres last year, forcing the Japanese to limit their season's catch to 680 whales.
Sea Shepherd said it has undertaken 25 years of anti-whaling protests without a single fatality or serious injury.