If I asked you to name the most endangered cetacean species, I doubt the vaquita would come to mind. You might mention the baiji, the dolphin living in China’s Yangtze river, but alas, no living members of this species have been seen for years, despite intense search efforts, and the species is presumed extinct. Unfortunately, the vaquita seems to be next in line. Biologist Brooke Bessesen here tells its sad story, revealing the complex world of species conservation.