Scientists doing a survey of endangered finless porpoises on China\'s Yangtze River said they also hope to find white-flag dolphins, declared extinct in 2007. A 2006 survey by Chinese and foreign scientists failed to find any white-flag dolphins on China\'s longest river. In 2007 white-flag dolphins were declared \"functionally extinct,\" meaning the population is too small for the species to effectively reproduce, China\'s state-run Xinhua news agency reported. \"There is still the possibility of finding one or two white-flag dolphins on the Yangtze,\" Wang Kexiong, deputy head of the survey team, said. \"We are looking forward to a miracle.\" The white-flag dolphin, among the 12 most endangered species in the world, is under Chinese state protection. In 2004, the body of a white-flag dolphin was found on the bank of the Yangtze, the last known proof of the species\' existence, Xinhua said.