Anti-whaling group Sea Shepherd says Japan's use of military-grade technology to track its ships has ended its attempts to stop the Southern Ocean whale hunt.
For the past 12 years, the activist group's ships have confronted the Japanese whaling fleet in a bid to limit its ability to conduct what the country calls scientific whaling.
Sea Shepherd founder Paul Watson said he would now have to find an alternative.
"They're using military technology," he said.
"They have real-time satellite coverage. Where we are, we cannot close in on them.
"We don't have their money, we don't have their technology, but we are going to have to find an alternative way to deal with them, and we will."
Mr Watson criticised the Australian Government, saying Canberra could have done more to help prevent the whale hunts.
"Now Australia is supposed to go down there, send a ship to monitor what Japan is doing, at least," he said.
"Australia could actually help us by using satellites to help give us the locations, but they don't."
Japan trade 'takes priority' over conservation
He said trade deals were taking precedence over conservation laws.
"They have made a lot of promises that they haven't kept, but really what it's all about is appeasing Japan, not upsetting Japan. Trade deals take priority over conservation law," he said.
Former Greens leader Bob Brown said Prime Minister Malcolm Turnbull had "whale blood on his hands" for not doing enough to stop Japan's Southern Ocean whale hunt.
But the Federal Environment Minister Josh Frydenberg said: "No country has done more than Australia to try to end Japan's so-called 'scientific' whaling, particularly in the Southern Ocean.
"The Government has made representations at the highest level in Japan and we are working hard through the International Whaling Commission (IWC) to end any commercial or so-called 'scientific' whaling and promote whale conservation.
"Australia recently invested an additional $1.5 million to the IWC's highly successful Southern Ocean Research Partnership, to support non-lethal whale research in the Southern Ocean."
