By Richard Black Environment correspondent, BBC News website

The baiji is thought to be the world's most endangered mammal

Zoologists have developed a plan to save the Yangtze River dolphin, probably the world's most endangered mammal, from extinction.

They hope to take some dolphins from the Yangtze and rear them in a nearby lake, protected from fishermen.

The species is threatened by overfishing which removes its food, industrialisation, boat collisions, and through being caught in fishing nets.

The most recent surveys found only 17 living individuals.

Also known as the baiji and Chinese lake dolphin, Lipotes vexillifer is listed as Critically Endangered on the internationally recognised Red List of Threatened Species, which describes it as "probably the most endangered cetacean in the world".

Safe haven

Late last year an international group of conservation zoologists held a workshop in San Diego aiming to develop a coherent rescue plan.

That plan has now been published by a group led by Samuel Turvey from the Institute of Zoology, part of the Zoological Society of London (ZSL).

"It's been suggested for a long time that the only way to save them from dying out is to set up a closely monitored breeding population under semi-natural breeding conditions," he told the BBC News website.

"The plan is to set up a reserve in an oxbow lake 21km long which was part of the Yangtze until the 1970s."

There is massive human population pressure, industralisation, overfishing, boat collisions, bycatch, and various dams Samuel Turvey

Tian-e-Zhou lake already houses another freshwater cetacean, the Yangtze finless porpoise, so conditions are likely to suit the baiji.

There are fish in the lake to provide food for the dolphins; and although there may be some human fishing, it is likely to be on a much smaller scale than in the Yangtze itself.

There, the pressure of China's burgeoning population have brought stocks of some of the baiji's prey species to one thousandth of their pre-industrial levels, Dr Turvey said.

"There is massive human population pressure, industralisation, overfishing. Boat collisions have had a huge impact, then there's bycatch, and various dams of which the Three Gorges is just the best known.

"That was another nail in the coffin, but the species has been declining for decades; during the Great Leap Forward there was even a factory established to make bags out of dolphin skin."

ZSL and its collaborating organisations anticipate the endorsement of their plan, and are starting to look for funds.

Costs could amount to between £200,000 and £300,000 ($365,000 and $545,000) for the first year's operations.

Boats are needed to catch the dolphins, helicopters to transfer them to Tian-e-Zhou. Holding pens need to be constructed, veterinary staff provided, and an inventory made of fish stocks.

The rescue plan speaks of conducting five dolphin capture operations in the Yangtze within the next three years "...in order to establish a viable ex-situ breeding population of baiji at Tian-e-Zhou before the Yangtze population undergoes a further decline or becomes extinct".

The long-term plan would be to re-introduce them to the Yangtze, but only when the prospects of them thriving there have risen.