The baiji is gone. During six weeks of searching the Yangtze River, scientists and conservationists failed to spot any of the unique creatures. This means, they say, that the "goddess of the Yangtze" is extinct because, even if a scattered few are still around, there are not enough to reproduce and perpetuate the species.

"Our inability to detect any baiji in the main channel of the river despite this intensive search effort has the sad consequence that the prospect of finding and translocating any surviving dolphins to an ex situ reserve—their only conservation hope—has all but vanished," says zoologist Samuel Turvey of the Zoological Society of London. The scientists employed both four continuous spotters as well as a trailing microphone to try to pick up the baiji's waterborne whistles, which have been heard on Earth for at least 20 million years.

There was never a huge number of these freshwater dolphins, characterized by a long, tapering snout and a crestlike, remnant dorsal fin; the several thousand reported in ancient accounts had dwindled to just a few hundred by last decade. A 1999 survey turned up just 13 of the animals and the last time one was sighted and photographed was five years ago, according to a paper documenting the decline in Biology Letters.

The long, slow death of the baiji was caused by overfishing, construction of the Three Gorges Dam and other changes in the vicinity of the Yangtze River (where more than 10 percent of humanity makes its home), rather than hunting or other direct human impacts. Locals living on the banks of the Yangtze still use indiscriminate electrical charges in the water and so-called rolling hooks—long lines set with hundreds of hooks that snag fish (and baiji) foraging on the bottom—decades after they were banned by law. "Once the baiji was caught by one piece of hook, it would struggle to escape and then it would be entangled by more rolling hooks," says Wang Ding, deputy director of the Institute of Hydrobiology (IHB) in Wuhan. "Finally, the animal would drown."

Turvey adds: "We witnessed massive amounts of fishing daily along the river, both legal fishing (gill nets) but also large amounts of illegal rolling-hook long-lining and electrofishing, which have long been banned. … In fact, before we even set off on the survey, fishermen were fishing with long lines right next to our survey boats at the dock in Wuhan."

Despite predictions decades ago of the baiji's decline, few efforts were made to preserve the animal outside its main habitat in a few reserves. One male baiji—nicknamed Qi Qi—became the sole resident of a pool at the Baiji Dolphinarium at the IHB. "The reasons for this inactivity appear to stem from a reluctance to make firm conservation decisions based on limited data, a fear of being seen to fail in a potentially high-risk conservation exercise, and a preference for more 'hands-off' recovering strategies," Turvey says. "Had recommended conservation actions actually been carried out, the baiji would almost certainly be with us today."

The loss of the baiji marks the first extinction of a large animal since the disappearance of the Caribbean monk seal in the 1950s, though the U.N. estimates that three smaller animal or plant species go extinct every hour. And scientists warn that if changes are not made soon, the Yangtze finless porpoise may soon follow its cetacean cousin, having dropped by half from the roughly 2,500 extant in the 1990s.

"Without quick and substantial intervention, the [porpoise] may also soon be extinguished," Ding notes. He says that better studies of this unique animal and more reserves in the Yangtze are required, though scientists at his institute have started a captive breeding program. Two babies—one in 2005 and one this year—have been born, improving the survival odds of this rare freshwater porpoise.

As for the baiji, hope is the last vestige of the animal to die. "The latest unconfirmed sighting of the baiji was April 27, 2006, which is a good reason to suppose that there are likely a few animals living somewhere in the river but hard to find," Ding says. Turvey is among a band of scientists and conservationists that plans to interview fishermen throughout the baiji's historic range, to track down any survivors. But "the continued deterioration of the Yangtze ecosystem," he says, "means that the species has no hope of even short-term survival as a viable population in the river if it has not already disappeared."