Note: forwarded message attached.
---------------------------------
Ready for the edge of your seat? Check out tonight's top picks on Yahoo! TV. --- Begin Message ---
http://news.bbc.co.uk/2/hi/science/nature/6935343.stm
Last Updated: Tuesday, 7 August 2007, 23:53 GMT 00:53 UK
E-mail this to a friend Printable version
Rare river dolphin 'now extinct'
Yangtze river dolphin (Image: Stephen Leatherwood)
An extensive survey of its habitat failed to find any sign of the baiji
A freshwater dolphin found only in China is now "likely to be extinct", a team
of scientists has concluded.
The researchers failed to spot any Yangtze river dolphins, also known as
baijis, during an extensive six-week survey of the mammals' habitat.
The team, writing in the Royal Society Biology Letters journals, blamed
unregulated fishing as the main reason behind the dolphins' demise.
It would be the first extinction of a large vertebrate for over 50 years.
The World Conservation Union's Red List of Threaten Species currently
classifies the creature as "critically endangered".
We have yet to take full responsibility in our role as guardians of the planet
Dr Sam Turvey,
Zoological Society of London
Sam Turvey of the Zoological Society of London (ZSL), one of the paper's
co-authors, described the findings as a "shocking tragedy".
"The Yangtze river dolphin was a remarkable mammal that separated from all
other species over 20 million years ago," Dr Turvey explained.
"This extinction represents the disappearance of a complete branch of the
evolutionary tree of life and emphasises that we have yet to take full
responsibility in our role as guardians of the planet."
'Incidental impact'
The species (Lipotes vexillifer) was the only remaining member of the
Lipotidae, an ancient mammal family that is understood to have separated from
other marine mammals, including whales, dolphins and porpoises, about 40-20
million years ago.
The white, freshwater dolphin had a long, narrow beak and low dorsal fin; lived
in groups of three or four and fed on fish.
The team carried out six-week visual and acoustic survey, using two research
vessels, in November and December 2006.
"While it is conceivable that a couple of surviving individuals were missed by
the survey teams," the team wrote, "our inability to detect any baiji despite
this intensive search effort indicates that the prospect of finding and
translocating them to a [reserve] has all but vanished."
The scientists added that there were a number of human activities that caused
baiji numbers to decline, including construction of dams and boat collisions.
"However, the primary factor was probably unsustainable by-catch in local
fisheries, which used rolling hooks, nets and electrofishing," they suggested.
"Unlike most historical-era extinctions of large bodied animals, the baiji was
the victim not of active persecution but incidental mortality resulting from
massive-scale human environmental impacts - primarily uncontrolled and
unselective fishing," the researchers concluded.
--- End Message ---
