The Ganges river dolphin is one of only two remaining freshwater dolphin species on earth. But pollution, fishing, and dams threaten to wipe it out entirely.
So acoustical engineer Harumi Sugimatsu and her team have deployed an experimental sonar monitoring system just under the surface of the murky water. The hope is to track the dolphins by the high-frequency clicks they use to navigate and hunt. By eavesdropping on their underwater lives, Sugimatsu believes she can gather data about their behavior and geographical range—data that conservationists can use in their struggle to keep the species from going extinct.