Whale
The IWC has designated two whale sanctuaries: the Southern Ocean Whale Sanctuary, and the Indian Ocean Whale Sanctuary. The Southern Ocean whale sanctuary spans and envelopes Antarctica. The Indian Ocean whale sanctuary takes up all of the Indian Ocean south of 55°S. The IWC is a voluntary organization, with no treaty. Any nation may leave as they wish; the IWC cannot enforce any law it makes.
North Pacific right whale
There have been a record of rather aggressive interspecies interactions between a right whale and a pod of grey whales off California, making it the only record of possible interspecies aggression among baleen whales, but there have been an observation of social behaviors between the two species on Sakhalin. Furthermore, there is no decent population of grey whales existing outside of North Pacific as of 2014, therefore extents of interspecies competitions, if ever happened, or peaceful habitat sharing between these coastal species, before whaling, are unknown. A theory of humpback whales to invade and become a dominant species over Hawaiian islands, former wintering ground for right whales, in the past few centuries, corresponding with the timing of right whale hunts across the Pacific Ocean, had been claimed as well.