If the white-flag dolphin disappears, it will be the first whale species to become extinct due to human activity, said Wang Ding, vice director of the hydrobiology institute of the Chinese Academy of Sciences. Scientific data indicates that more than 90 percent of deaths of white-flag dolphins were caused by human activity. However, Wang insisted that it is still too early to say whether the white-flag dolphin is extinct, even though scientists found none during their 3,400-km expedition along the main section of the Yangtze River.