Explanation:

Indus Dolphin is subspecies of freshwater river dolphin (which also includes Ganges River dolphin) found in Indus river (and its Beas and Sutlej tributaries) flowing through India and Pakistan. It is national mammal of Pakistan. It is a key indicator species of river’s health. Its presence is considered as river is healthy. Indus dolphin like Ganges River dolphin is functionally blind and relies on echolocation to navigate, communicate and hunt prey in muddy river water.

Only 1,816 Indus dolphins are reported to exist presently in lower parts of Indus River. They are patchily distributed in five small, sub-populations that are separated by irrigation barrages across course of Indus river and its tributaries. Their numbers have declined dramatically after construction of irrigation system. It listed by the IUCN as endangered on its Red List of Threatened Species. Indus Dolphin was also found in Sutlej decades back, but river pollution has caused its extinction in river.