http://www.iht.com/articles/ap/2007/08/29/asia/AS-GEN-China-Dolphin-Extinction.phpLast year, the freshwater Baiji (means 'white flag') or Yangzi River Dolphin was declared extinct after a search turned up zero remaining animals. Now, there
may be a sighting.
Even if it were an actual white river dolphin, I see almost zero chance of it being able to find, let alone breed with others and produce enough offspring though. Cloning maybe?