China's finless porpoises face a fight for survival in and around the Yangtze River but researchers see signs of hope, Kelly Wang reports in Wuhan. 

In an oxbow lake along the middle reaches of the Yangtze River, a breathy sigh pierces the surface stillness as one of China's most endangered animals comes up for a gulp of hazy air.

A slick black back with no dorsal fin arches briefly above the water line before plunging back down.

Such glimpses of the shy Yangtze finless porpoise, the only aquatic mammal left in China's longest river and known in Chinese as the "smiling angel" for its perma-grin, are increasingly rare.

Pollution, overfishing and shipping traffic have rendered them critically endangered, worse off even than China's best-known symbol of animal conservation, the panda.

China's government estimates there were 1,012 wild Yangtze finless porpoises in 2017, compared to more than 1,800 giant pandas that are no longer endangered.

But researchers see signs of hope.

Porpoise numbers fell by nearly half from 2006 to 2012 to an estimated 1,040.

But the rate of decline has slowed markedly since then, suggesting that conservation may be making a dent.

A central component of the rescue effort is the introduction of porpoises to several conservation areas off the busy river, where researchers say numbers have actually been increasing.

Encouraging signs

Around 30 to 40 porpoises were brought to the Tianezhou Oxbow Nature Reserve in central China's Hubei province-a curving lake linked to the Yangtze by a stream-at the beginning of the 1990s. There are now around 80.

"We found out that the animals can not only survive, but also reproduce naturally and successfully at Tianezhou," says Wang Ding, 60, a porpoise expert with the Chinese Academy of Sciences.

"That's very encouraging."

Researchers also credit official clampdowns on polluting activities and overfishing, artificial reproduction projects, and growing environmental awareness among China's emerging middle class.

"The voice and supervision of the public have played an important role," says Zhang Xinqiao, the species' project manager at the World Wide Fund for Nature.

Chinese officials are keen to avoid a repeat of the baiji, or Yangtze dolphin-the river's only other aquatic mammal, which since 2007 has been considered "functionally extinct"-which was a huge conservation setback for China.

Losing the "smiling angel" would be a further tragedy, conservationists say.

One of the world's few freshwater porpoise subspecies, it is considered a natural barometer of the overall health of China's most important river.

'River pig'

The finless porpoise is mentioned in ancient Chinese poems and has been considered a harbinger of rain.

Some locals call it the "river pig" for its plump body and rounded head.

Adults can reach two meters long.

Since China reopened to the world four decades ago, living standards have soared, but so have air and water pollution.

But in January 2016, President Xi Jinping called for a river protection push. Steps have included curbs on development, stricter fishing rules and other protection projects.

Later that year, a formal porpoise action plan was launched, including increased relocations away from the river, more reserve sites and research on artificial breeding.

The Tianezhou reserve, established in 1992, claims to be the world's first and only example of cetaceans-which include dolphins and porpoises-surviving and reproducing after relocation.

Local fishermen near the lake were encouraged to change professions and Wang Hesong, 46, became a patrolman at the reserve.

"Look over there, a mother and a baby," Wang says, as his pilot cut their patrol boat's engine at the sight of two arched backs breaking the lake's silvery surface.

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.