Activist group Sea Shepherd is abandoning its annual face-off with Japanese whaling ships in Antarctic waters, saying it has little chance of success against Japan's economic and military might.
The end of the 12-year campaign means Japan will continue its so-called "scientific" whaling programme without the group trying to physically prevent the annual slaughter, which takes place despite loud international protest.
Japan reportedly intends to take about 4000 whales over the next 12 years in the name of "research", and ultimately plans to resume commercial whaling.
In a statement, Sea Shepherd founder Captain Paul Watson said Japan had doubled its hunting grounds in the Southern Ocean and reduced its annual whale-kill quota to 333, giving its fleet "more time and more area to kill".
He said Japan was also using "military" tactics in the form of real-time satellite surveillance to track Sea Shepherd ship movements, "and if they know where our ships are at any given moment, they can easily avoid us … we cannot compete with their military grade technology".
"The decision we have had to face is: do we spend our limited resources on another campaign to the Southern Ocean that will have little chance of a successful intervention or do we regroup with different strategies and tactics?
"If something is not working the only recourse is to look for a better plan," he wrote.
Watson said Japanese whalers were backed by resources and subsidies from their government, while Sea Shepherd was "limited in resources and we have hostile governments against us in Australia, New Zealand and the United States."
Watson pointed to Australia's refusal to allow the group charitable tax-deduction status, hampering its ability to raise funds.
He said the group was "not abandoning the Southern Ocean whale sanctuary ... we need to cultivate the resources, the tactics and the ability to significantly shut down the illegal whaling operations of the Japanese whaling fleet".
Watson said Sea Shepherd was "in the Southern Ocean doing what the Australian government has the responsibility to do but has refused to do". He called on the Turnbull government to uphold international and Australian law in relation to whaling.