The rare Gangetic and Mahseer dolphins inhabit the Karnali River in Bardia National Park. This is an extremely endangered species, currently it is estimated that there are about 11 specimens in Karnali River.
They can only live in fresh water and are essentially blind. They hunt by emitting ultrasonic offspring. One of the biggest threats to this species was essentially the intensive practice of agriculture on the banks of the Karnali River, where populations diverted a lot of water from the river over several years, which caused the levels to drop, threatening the species with extinction.