#4. Yangtze River Dolphin Extinction
The Chinese called it baiji and "goddess of the Yangtze," and it
was the only surviving member of a family of species that split off from
saltwater whales and dolphins between 20 million and 40 million years ago.
But now, according to a survey released in August, this rare freshwater
mammal is almost certainly extinct — the first aquatic vertebrate species
to disappear from the Earth in 50 years, and the first large mammal to fall
victim to human impact. The multiple pressures: noisy boat collisions and
dam construction that may have imperiled the sonar-driven animals, and overfishing — not for the dolphins themselves, but for river fish — with such indiscriminate techniques as netting, dynamite and
powerful electric shocks. The disappearance of a top-level predator like the
baiji — an indicator species that signals the health of its
ecosystem — portends trouble for the Yangtze River and for the 400
hundred million people who depend on it.