However, the Japanese government announced it would resume its "scientific" whaling programme, drawing criticism from environmental groups and the Australian and United Kingdom governments.
Sea Shepherd has released aerial images reporting to show a dead protected Antarctic minke whale aboard a Japanese ship in Australian waters.
Japan is a signatory to the International Whaling Commission's moratorium on whaling in force since 1986.
"'Deeply disappointed' is really not good enough", Mr Hansen told The New Daily. "Now they're in power and there's still blood in the water and a blind eye in Canberra".
Sea Shepherd has been patrolling the Southern Ocean for five weeks.
In July 2015, the Sea Shepherd was fined US$2.55 million for harassing the Japanese whaling fleet.
"This Japanese whaling fleet is heavily funded and backed by the government of Japan - this is Shinzo Abe's whaling fleet", he said.
It comes after Japanese Prime Minister Shinzo Abe visited Australia.
Images taken by helicopter appear to show a dead minke whale carcass with a harpoon wound on board the Japanese whaling ship Nisshin Maru.
A slaughtered whale was photographed on board a Japanese ship by the activist group Sea Shepherd, in defiance of a recent global court ruling against Tokyo's sea hunts.
"The Australian people want action, and in the absence of that they're left with Sea Shepherd but it shouldn't be left up to us", he said.
After the Japanese crew saw the Sea Shepherd helicopter, they covered the harpoons and attempted to hide the whale carcass with a tarpaulin, according to Sea Shepherd. "No more whales will be killed today", said Meyerson.
"Australia is opposed to all forms of commercial and so-called "scientific" whaling".
'No country has done more to try to end whaling than Australia'. Japan is ignoring a worldwide moratorium on whale hunting using the excuse of scientific research.
"They know they are in contempt of the ruling of the International Court of Justice and the Australian Federal Court".
Sea Shepherd has clashed with Japan's whaling fleet in the past in an attempt to disrupt the hunt, with Tokyo accusing the activist group of sabotage in their controversial high seas protest.
This is despite the 2014 International Court of Justice ruling that Japan's Southern Ocean whaling program was illegal and must stop.
Mr Frydenberg's Opposition counterpart, Tony Burke, also issued a statement, criticising the "slaughter under the guise of "scientific research". Japan insists that since then it has only been whaling for "scientific research", but the activists doubt that slaughtering more than 8,000 minke whales in the past three decades for that objective was necessary.