Wang Ding said before the ongoing expedition, they have conducted several smaller surveys in the Yangtze River region, which suggested threats facing the porpoises have remained since 2006.
"We've just surveyed the section between Yichang and Wuhan, and caught rare sights of porpoises. We are not optimistic about the results of the mainstream survey either," Wang said.
Lei Gang, director of WWF China's Freshwater Program, said immediate action is needed if people wish to save the finless propoises from the same ill fate as the white-flag dolphins.
"This means better laws and enforcement -- we need to see harmful fishing practices stopped, sand dredging better controlled, and new reserves developed," Lei said.
Wang expected the survey could help put the porpoises onto China's top list of wildlife protection, which will bring more government investment to related conservation programs.
"We've discussed this for years as it involves complicated procedures, but as far as I know, the change may come soon," Wang said.
Beijing experiences windy weather, temperature drop