After thousands of years swimming the mighty river the gentle, blind mammal is under threat from a combination of uncontrolled fishing & damage to its habitat caused by man-made dams. The dolphin, which can grow up to 2.5 metres, is one of the world's rarest mammals, with a population of just 1,400 living scattered along a 1,200-kilometre stretch of the Indus, which rises in the Himalayas & flows out into the Arabian Sea near Karachi. They are classed as endangered on the International Union for Conservation of Nature (IUCN) red list of threatened species, which says the population has fallen by more than 50 percent since 1944.