Story highlights An anti-whaling group says it split up Japan's fleet and chased it out of the Antarctic zone

"Within a day and a half, we have the entire whaling fleet in disarray," an activist says

Japan says the whaling ships are still in the Southern Ocean and the hunt continues

Environmental groups clash each year with Japan's whaling vessels

Environmental activists have declared an early success at the start of their annual high seas showdown with Japanese whalers in Antarctic waters.

The anti-whaling group Sea Shepherd Australia said its ships had split up the Japanese fleet in the Southern Ocean and chased it out of the main Antarctic zone.

"The whale poaching fleet is scattered and currently not hunting whales," Sea Shepherd said in a statement Monday.

But Japanese authorities say the hunt is still on.

Japan's fleet carries out an annual whale hunt despite a worldwide moratorium, taking advantage of a loophole in the law that permits the killing of the mammals for scientific research. Whale meat is commonly available for consumption in Japan.

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Each year, environmental groups like Sea Shepherd pursue the Japanese hunters in an attempt to disrupt the whaling. The resulting confrontations have led to collisions of ships and the detention of activists.

Sea Shepherd said Monday that the Japanese fleet's harpoon ships are "separated by hundreds of miles." The factory ship, the Nisshin Maru, is "on the run," the environmental group claimed.

It said its three ships had ushered the Japanese fleet out of the Antarctic Treaty Zone, the internationally designated area below 60 degrees south latitude.

"Within a day and a half, we have the entire whaling fleet in disarray," said Siddarth Chakravarty, the captain of one of the Sea Shepherd ships.

Japan's Fisheries Agency, which oversees the annual hunt, said Tuesday that the whaling operation has not been halted.

It said the fleet remains in the Southern Ocean, which is generally considered to cover a similar area to the Antarctic Treaty Zone.

The agency declined to comment specifically on Sea Shepherd's claims or on the fleet's exact whereabouts.

On Monday, Sea Shepherd published photos and videos that it said showed three harpooned Minke whales lying on the deck of the Nisshin Maru and another being butchered.

The Australian government has challenged the Japanese whaling program in the International Court of Justice.

But the current hunt will continue, and Sea Shepherd activists say they'll continue to fight it.

"We have won this battle," said Adam Meyerson, another of the group's ship captains. "But the war for the Southern Ocean Whale Sanctuary will wage on over the coming months."