The shy mammals quickly submerged.

"They only come up for a couple of seconds to breathe. We go out patrolling every day and we see them every day," Wang says.

The 21-kilometer-long lake offers sanctuary, but porpoises within the river face intense pressure.

The WWF's Zhang warns that the species' days in the river may be numbered.

"They have nowhere to hide in the river," he says.

"As long as danger exists, such as a further deterioration of natural habitat, it's very likely their numbers could drastically decrease again."

Clock is ticking

With the clock ticking, a research facility in the nearby industrial city of Wuhan hosts six finless porpoises for research, breeding and to engage the public.

Two of them gracefully circled past an observation window that looks into their huge tank, playfully tilting their bodies to catch a glimpse of the human visitors.

"They are saying 'hi' to us," says Liu Hanhui, a volunteer.

"I think they understand human feelings."

According to the WWF, adult Yangtze finless porpoises have the intelligence equivalent to that of a child aged between 3 and 5.

Just before feeding, they are coaxed to open their mouths on cue, show off their smiles and shake hands by extending a flipper.

Yet, they are difficult to breed in captivity.

A calf born in June at the dolphinarium-founded in 1980-is just the second produced there to survive more than 100 days, whereas wild calves often die before adulthood due to human impact on their environment.

Liu, an aquaculture student at a nearby university, along with 40 other volunteers, helps feed them on weekends and holidays, and takes part in various activities to promote awareness.

Conservation programs and events in the region have proliferated in recent years, backed by scores of businesses and NGOs aiming to instruct the public and encourage greater government protection efforts.

"Our development has caused a species to rapidly disappear. I feel like I'm atoning for mankind's crimes," Liu says.