It is expected its departure will be opposed globally, particularly among anti-whaling nations.
Japan's rationale could be also questioned as it is a member of the UN Convention on the Law of the Sea that calls for the use and conservation of marine resources via global organisations.
"We would like to wholeheartedly celebrate an end to Japan's whaling in the Southern Ocean, but if Japan leaves the International Whaling Commission and continues killing whales in the north Pacific it will be operating completely outside the bounds of international law", said Nicola Beynon, head of campaigns at Humane Society International in Australia.
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Japan has long towed the line with the IWC, which was established in 1948. This was finally the original task of the whaling Commission, argued Moronuki: the conservation of Whales and the sustainable use of the Walressourcen.
However, Slooten said the withdrawal of staunchly pro-whaling nations could conversely allow the IWC to become a more progressive organization, focused on the conservation of other cetaceans such as dolphins and porpoises.
Japan previously threatened to leave the IWC in 2007, but changed its mind after talking with representatives from the United States and other member nations, according to Kyodo News. Critics accuse Japan, however, has always been to use science as a cover for commercial whaling by the back door.
Supporters of whaling say that it is a Japanese tradition and that foreign critics who consume farmed and hunted animals are hypocrites. Of the 333 minke whales caught during the four-month expedition, 181 were female - including 53 juveniles.
Japan has hunted whales in the Southern Ocean since 1987 for what it calls "scientific research" purposes, but this has been criticized internationally as a cover for commercial purposes. After a year's pause, Japan began what it said was a scaled-back whaling program. If it does leave, Japan would join Iceland and Norway in openly defying the moratorium.