"We are just hoping the baiji are still here," Brent Stewart, a research biologist from Hubbs-Seaworld Research Institute in San Diego, said aboard the Kekao One, one of the expedition's ships.

Expectations among the experts from China, Japan, Switzerland and the US that the baiji has overcome China's relentless environmental degradation are tempered by gritty reality.

Massive pollution from factories along the banks of the world's third longest river dump brown, foul smelling effluent into the water.

Fisherman, their silhouettes dotting the river's turbid waters, cast lethal kilometer- (half-mile-) long nets that result in severe over fishing of the baiji's food source.

The rolling hook fishing nets also inadvertently trap the baiji, while illegal dynamite fishing blows them to bits. Electrofishing stuns them just long enough so they can drown.

Meanwhile, giant barges weighed down with coal, oil, gas, minerals -- among the many key resources China consumes to power its booming economy -- crowd the baiji out of its river home.

August Pfluger, co-expedition chief and head of Swiss-based baiji.org, an environmental group dedicated to saving whales and dolphins, put the baiji's chance of survival at around five percent.

China's unprecedented industrialization over the past 30 years has so damaged the Yangtze's ecology that today fewer than 50 baiji are believed to survive, according to researchers on the expedition.

Wang Ding, head of China's Institute of Hydrobiology and one of the world's foremost experts on Yangtze marine life, said the fate of the baiji highlighted China's willingness to sacrifice the environment for economic progress.

"China used to be poor and so it always focused on economic development, while society just didn't care about nature," said Wang.

"Now society has started to realize what has happened. Maybe it is too late but we have to do something otherwise it will be gone for sure."

The objective of the six-week expedition is to find, count and observe the baiji, then capture them and put them in a safer home such as an aquatic reserve.

Aboard the two ships, scientists armed with high-tech optical and acoustic equipment, as well as a group of trained observers, will have scoured 1,750 kilometers (1,085 miles) of the Yangtze when their voyage from Wuhan to Shanghai is complete.

But even the high-tech efforts to monitor the dolphins are being hampered by the frantic economic activity.

The incessant roar of ships' engines drowns out the eerie, melancholic high-pitched whine of the baiji.

"Ships' engine noise sounds like the baiji, so you get noise contamination that can result in missing 50 percent of the sounds, said Tomonari Akamatsu, an underwater bio-acoustics expert from Japan's National Research Institute of Fisheries Engineering.

In a nine-day trip in March researchers failed to find a single baiji, which relies on its highly developed sonar system instead of its eyes. But with its navigational system impaired by the shipping activity the baiji has become the marine equivalent of road kill -- an animal run over and butchered beneath boat propellers.

One of the other great threats to the dolphin, as well as to its Yangtze cousin, the finless porpoise -- which is set to join the baiji at the end of this year on the list of critically endangered species -- is China's Three Gorges dam, the world's largest.

According to Zhang Xianfeng, director of research at the Institute of Hydrobiology, the dam's massive sluice gates have changed the Yangtze's natural water flows thus impacting biodiversity, probably forever.

The confluence of these factors cut the number of baiji, identifiable by its long, teeth-filled jaw, from about 400 in 1984 to fewer than 100 a decade later.

The last time scientists saw the animal in the wild was more than two years ago. The last confirmed count in 1997, done by naked eye, recorded just 13.

Leigh Barrett, one of baiji.org's project managers, described searching for the animal she has never seen alive as a little like "believing in the tooth fairy".

If the goddess of the river, as the baiji is called in ancient Chinese mythology, has vanished, it will mean the loss of a mammalian evolutionary line believed to have begun 25 million years ago -- or about 20 million years before man.

Related Links
Hubbs-Seaworld Research Institute
Darwin Today At TerraDaily.com