After scouring China’s Yangtze River for six weeks, a team of international experts has declared the baiji, a rare white river dolphin, “functionally extinct.” August Pfluger, head of the Swiss-based baiji.org Foundation and a co-organizer of the expedition, told the New York Times: “We might have missed one or two animals but it won’t survive in the wild. We are all incredibly sad.” The baiji is the first large aquatic mammal to become extinct since the 1950s, when the over-hunted and over-fished Caribbean monk seal disappeared.

 

A team of 30 international scientists and crew used underwater microphones and high-tech optical equipment to search more than 1,600 kilometers of the Yangtze, the baiji’s only known habitat. The nearly blind cetacean, which relied on its sonar abilities for navigation and finding food, survived some 20 million years as a species, but ultimately disappeared surprisingly fast, experts say. As recently as the early 1980s, some 400 individuals were known to exist, and there were 13 confirmed sitings in 1997.

 

The dolphin’s extinction points to larger issues, experts say. “It’s not only the loss of a beautiful animal but an indication that the way its habitat is being managed, The factors that drove the baiji to its demise—including pollution, heavy ship traffic, and over-fishing—still threaten the world’s five remaining species of freshwater dolphin, three of which live in Asia and all of which are critically endangered.