According to this article
The IWC has grown from 14 member states, when it was set up in 1946, to 55, and it is the only global body formally to address all threats to the existence of cetaceans.Six species are critically endangered and at least one, the Yangtze River Basin dolphin, is in immediate danger of becoming extinct.They have this PDF document from 2003 which explains the plight of the dolphin.
6.1 Baiji
The baiji (Lipotes vexillifer) is the most endangered cetacean. Its range is restricted to the Yangtze River and its population size is probably only a few tens of animals.
