"These ongoing and cruel persecutions of marine mammals are increasingly out of step with modern scientific thinking," said Mark Simmonds from Humane Society International.
The Humane Society International has condemned the "cruelty of Japan's whale hunt."
Activists say overfishing will have devastating consequences for the species.
Anonymous has been targeting Japanese and Icelandic websites over whaling.
Conservationists, and neighboring countries Australia and New Zealand, aren't happy with the decision.
Fin whales are considered endangered and illegal for most countries to transport.
Japanese whaling boats will return to the Antarctic next year despite international opposition, a government official announced Monday.