Video: Japanese ship accused of killing protected minke whales A group of anti-whaling activists is chasing Japan's whaling fleet in the icy waters off Antarctica, as the country's annual Antarctic whale hunt gets under way. The Sea Shepherd organisation, which each year tries to harass the whaling fleet into stopping its hunt, said it had caught up with all five of Japan's whaling vessels on Monday. The group released images of several dead whales lying on the deck of one ship. Each whaling season, Sea Shepherd and Japan engage in clashes that occasionally turn aggressive, with stink bombs, water cannons and ship collisions common features. Sea Shepherd calls the whalers butchers, and the whalers says activists from Sea Shepherd are terrorists. In years past, a Sea Shepherd boat sank after its bow was shorn off in a collision with a whaling ship and a Sea Shepherd activist spent five months in a Japanese jail after boarding one of the whaling vessels. Japan, which this year is planning to kill about 1,000 whales, is allowed to hunt the animals for scientific purposes under an exception to a 1986 ban on whaling. But opponents argue the scientific program is a cover for commercial whaling because whale meat not used for study is sold as food in Japan. Bob Brown, chairman of Sea Shepherd Australia and former leader of Australia's minor Greens party, said his group will run a peaceful but relentless campaign this year. He dubbed this season's hunt grotesque and cruel. "There's blood all over the place, meat being carted around on this factory ship deck, offal, innards being dumped in the ocean," Brown said. It's just a gruesome, bloody, medieval scene which has got no place in this modern world. Australia went to the United Nations' highest court last year in a bid to outlaw Japan's annual whale hunt, arguing it violates the 1986 moratorium on commercial whaling. Japan says the hunt is legal and produces valuable scientific data. The International Court of Justice is expected to issue its decision sometime this year.