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Anonymous
'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.
Story from BBC NEWS: http://news.bbc.co.uk/go/pr/fr/-/2/hi/science/nature/6935343.stm
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