Despite protests and an international ban on commercial whaling, Japan continues whaling - Japan maintains its official stance that it hunts whale for "scientific purposes," despite meat from its hunts ending up on the market.

In 2014, the International Court of Justice in The Hague also banned whaling in Antarctica for scientific reasons, ruling that Japan's whaling served no scientific purpose, but was instead used to disguise commercial practices.

However, Japan failed to comply with the ruling, and has continued its whaling practices - at first in the North Pacific and then, one year later, also in Antarctica.

Japanese whale hunters had been met with fierce resistance by United States-based marine wildlife protection organization Sea Shepherd, which has been fighting against whaling and sealing since 1977.

Sea Shepherd says it has managed to successfully interfere with whaling ships in recent years, and thus helped save thousands of whales from being killed. Since 2015, writes Paul Watson, the founder of the organization, "another 1,400 whales were spared the lethal harpoons."

Sea Shepherd's Paul Watson (second from right) protests Japan's whaling practices with others

However, despite such efforts, Japanese whalers still managed to meet their quotas for 2016 and 2017, even though Sea Shepherd had deployed two ships.

Military surveillance to stop whale lovers

"What we discovered is that Japan is now employing military surveillance to watch Sea Shepherd ship movements in real time by satellite - and if they know where our ships are at any given moment, they can easily avoid us," Watson wrote.

"The Sea Shepherd ships did get close, and our helicopter even managed to get evidence of their illegal whaling operations - but we could not physically close the gap.

"We cannot compete with their military-grade technology," Watson concluded.

Sea Shepherd also says its work is threatened by Japan's new anti-terror laws, "some of which are specifically designed to condemn Sea Shepherd tactics," he wrote.

"For the first time ever, they have stated they may send their military to defend their illegal whaling activities."

To help focus its limited resources, the environmental protection organization has now decided to stop sending vessels to the Southern Ocean.

Japan maintains it catches whales for "scientific research" - a notion the International Court of Justice shot down in 2014

Watson says they "need to cultivate the resources, the tactics and the ability to significantly shut down the illegal whaling operations of the Japanese whaling fleet."

He did not specify what these tactics could be.

Watson also stressed how past efforts had paid off, since "there are now voices in the Japanese government opposing the continuation of whaling."

Will other groups fill the void?

A member of the Japanese fishing authority said it had acknowledged the statement by Sea Shepherd.

"It's not clear what the real intention of their statement is, and we don't know whether the organization will stop its anti-whaling actions this year," said the official, who wanted to remain anonymous, to news agency Reuters.

"We can't deny the possibility that other anti-whaling groups may take action - so we continue to closely monitor the situation and we're not making any predictions," the official added.