The founder and president of hardline conservationists Sea Shepherd, Paul Watson, is stepping down from the leadership after a ruling from a United States court over a Japanese restraining order.
Former Australian Greens leader Bob Brown is to take over running Sea Shepherd's imminent Antarctic anti-whaling campaign.
Watson, 62, who is wanted by Japan under an Interpol "red notice", remains at sea aboard the group's flagship, Steve Irwin.
The Steve Irwin docked at Timaru on Saturday to take on fuel, but Watson switched to another vessel before his ship arrived in port.
He said that 35 years after he founded the group he was resigning from all paid positions, as well as the captaincy of the Steve Irwin, and would remain onboard as an observer of the campaign.
Watson pledged to operate within boundaries set by a US appeal court restraining Sea Shepherd from attacking the whalers, or coming within 450 metres of their ships in the Antarctic.
"As a US citizen, I will respect and comply with the ruling of the US 9th District Court and will not violate the temporary injunction granted to the Institute for Cetacean Research (ICR)," he said.
Direction of the group's campaign to halt the Japanese whaling fleet will shift to Brown and Sea Shepherd's Australian manager, Jeff Hansen.
Brown, who resigned from the Greens leadership last year, said he would be taking advice from Watson, but rejected any suggestion that the switch was a token move.
"He's behind the scenes, but he's not in charge of the operation," Brown said.
"I'll be every day working, as will Jeff, working with the Sea Shepherd fleet under the authority of Sea Shepherd Australia, to make sure this mission is successful."
For the first time Sea Shepherd will use four ships in its campaign, including a recently acquired former Japanese research ship, renamed the Sam Simon.
In response to the leadership changes, the Japanese consul-general in Melbourne, Hidenobu Sobashima, reiterated concerns that Sea Shepherd was jeopardising the safety of crews and ships engaged in research whaling.
Former Howard government environment minister, Ian Campbell, said it was time for the Gillard Government to offer an assurance that Watson could land in Australia safely.
Sobashima was asked whether Japanese authorities had sought Watson's arrest if he came ashore in Australia.
"I am not [in] a position to explain specific communications between Japan and Australia," he said.
The whaling fleet is about two weeks steaming away from the Antarctic.
In a notice to the International Whaling Commission, the Japanese Government confirmed it had issued the ICR with a permit to kill up to 935 minke whales, 50 fin whales and 50 humpbacks.
The humpback kill, which would target whales that migrate along the Australian coasts in winter, would again be suspended, the ICR said.
- Sydney Morning Herald