The anti-whaling organisation Sea Shepherd will not contest the Southern Ocean against Japanese whalers this season, Captain Paul Watson has announced, accusing “hostile governments” in the US, Australia and New Zealand of acting “in league with Japan” against the protest vessel.

Sea Shepherd has been obstructing Japanese whaling vessels in the Southern Ocean each year since 2005, but Watson said the cost of sending vessels south, Japan’s increased use of military technology to track them, and new anti-terrorism laws passed specifically to thwart Sea Shepherd’s activities made physically tracking the ships impossible.

Australia took Japan to the international court of justice over its Southern Ocean whaling program in 2014, winning a judgment that condemned Japan’s whaling programs as being in breach of the International Whaling Commission’s ban on commercial whaling. The court rejected Japan’s argument that its whaling was for “scientific” purposes.

Watson said his volunteer organisation could not compete with Japanese military satellite technology, which tracked Sea Shepherd in the ocean. Japan has also passed anti-terrorism laws that make protest ships’ presence near whalers a terrorist offence.

“We’re just a group of volunteers trying to do the impossible, trying to do the job Australia and New Zealand and the United States and all these others countries should be doing but they’re too busy appeasing Japan.”

In a statement on Monday, Watson said the Japanese whaling companies “not only have all the resources and subsidies their government can provide, they also have the powerful political backing of a major economic superpower. Sea Shepherd however is limited in resources and we have hostile governments against us in Australia, New Zealand and the United States.”

Speaking on radio in Australia, Watson accused the Australian government of acting in league with Japan, indirectly supporting whaling by obstructing Sea Shepherd’s activities.

“Australia is definitely in league with Japan,” he said. “When our ships come in we’re harassed, we’re investigated, we’re searched, when our crew come in from other countries they have problems getting visas. We’ve been applying for charity status for 10 years – they won’t give it to us. This has been extremely hostile.

“Really what it’s all about is appeasing Japan. Trade deals take priority over conservation law.”

He said countries opposed to Japan’s whaling should have ships in the southern waters to monitor and deter whaling. “[They should] uphold their own laws, under US laws it’s illegal. Australia and New Zealand should be down there protecting their waters from poachers.”

Japan’s whaling in the Southern Ocean is illegal under international law. The US, Australia and New Zealand have all publicly, diplomatically and legally challenged Japan’s whaling program.

Aside from the ICJ challenge, Australia also pursued Japan in the Australian federal court in 2015, which fined the Japanese whaling company Kyodo $1m – a penalty that has not yet been paid.

Last month the New Zealand foreign affairs minister, Gerry Brownlee, said he was “extremely disappointed” Japan had passed new legislation to subsidise its whaling fleet and said he was concerned about Japan’s continued efforts to overturn the longstanding global moratorium on commercial whaling.

The US, Australia, New Zealand and the Netherlands were signatories to a joint statement in 2016, which accused the Japanese governments of flouting the ICJ order, and said: “Our governments remain resolutely opposed to commercial whaling.”

But that statement also warned anti-whaling activists against “dangerous, reckless or unlawful behaviour”.

The Sea Shepherd’s pursuit of whaling vessels has also attracted criticism. The Japanese government has described Sea Shepherd as “eco-terrorists” and sought to have Watson placed on an Interpol watch-list.

Security experts have criticised Sea Shepherd’s tactics at sea, saying they endanger lives.

And Sea Shepherd was fined for contempt of a US court for breaching an injunction not to physically attack or harass Japanese whalers.

In a statement issued on Tuesday, Watson said Sea Shepherd’s 12 years of action against Japan’s whalers had been successful, having seen 6,500 whales saved, not a single humpback killed, and only 10 endangered fin whales killed.

Japan’s whaling quota has been reduced from more than 1,000 whales a season to 333 a year.

Watson said Sea Shepherd would “never abandon the whales” but would formulate a new plan for contesting Japan’s whaling.