The first species to be erased from this planet’s great and ancient Order of Cetaceans in modern times is not one of the charismatic sea mammals that have long been the focus of conservation campaigns, like the sperm whale or bottlenose dolphin.

It appears to be the baiji, a white, nearly blind denizen of the Yangtze River in China.

On Wednesday, an expedition in search of any baiji, run by Chinese biologists and baiji.org, a Swiss foundation, ended empty-handed after six weeks of patrolling its onetime waters in the middle and lower stretches of the river, the baiji’s only known habitat.

The Yangtze, Asia’s longest waterway and thought to be akin to the Amazon long ago in its biological richness, now has a dominant species: the 400 million (and counting) people busily plying its waters and industrializing its banks.