Did You Know?
Besides the Amazon in South America, Asian rivers like the Ganges, Brahmaputra, Mekong, and Irrawaddy are also home to freshwater dolphins.
It's sad that the Yangtze River dolphin or Baiji (Lipotes vexillifer) came into the spotlight only after it became functionally extinct. If extinction is the price these mammals have to pay to make their presence felt, then other river dolphins, including the two subspecies of the South Asian river dolphin (Platanista gangetica): the Indus River dolphin (P. g. minor) and the Ganges River dolphin (P. g. gangetica) are also on their way.
The two subspecies are morphologically similar, such that, it is difficult to distinguish them from each other. The differences between them revolve around their geographic range, and the fact that the Indus River dolphin is slightly smaller of the two. Their classification as two separate species was revised in 1998, to make them two subspecies of the South Asian river dolphin.
Indus River Dolphin Facts
1. The present-day geographic range of the Indus River dolphin is restricted to the lower and middle areas of the main stem of the Indus in Pakistan. Historically though, this dolphin has been recorded in abundance along the length of the Indus, right from the foothills of the Himalayas in India to the Indus River delta in Pakistan.
2. The Indus River dolphin boasts of being the first side-swimming cetacean to be discovered. Its unique ability to swim on its sides helps it move around in relatively shallow water―as shallow as 1 meter at times.
3. Echolocation plays a crucial role for this species with respect to navigation and hunting, which shouldn't come as a surprise, considering that it is functionally blind. Its tiny eyes lack a crystalline eye lens, and therefore, it can only detect light levels.
4. It is also known as the Indus side-swimming dolphin, because of its ability to swim on its sides, and the Indus blind dolphin, as it is functionally blind. Besides these names, it is also called Bhulan in the local language.
5. This dolphin measures 7 - 9 ft in length, and weighs around 150 - 200 lb, which makes it slightly smaller than its sister species, the Ganges river dolphin. The females are larger than the males, in what is one of the best examples of sexual dimorphism.
6. The long, pointed nose is a characteristic adaptation of river dolphins the world over; the Indus River dolphin is no exception. It uses its nose to probe sediments at the bottom of the river while hunting bottom-dwelling species in the muddy water of the Indus.
7. Its diet comprises invertebrates like prawns and clams, as well as fish such as catfish and gobies.
8. It has a lifespan of 28 - 30 years. The species attains sexual maturity between 6 - 10 years of age.
9. The Indus River dolphin is considered the second most endangered cetacean in the world.
10. The species is enlisted as an endangered species by the International Union for Conservation of Nature (IUCN) in the Red List of Threatened Species, with roughly around 1,200 - 1,300 individuals remaining in the wild.
11. Habitat fragmentation resulting from the construction of barrages along the Indus is by far the biggest threat for the Indus River dolphin, as it isolates the populations of this species and makes breeding difficult.
12. Other threats to the species include increasing pollution with industrial and agricultural waste being dumped into the river, and the use of fishing nets in which they get entangled and cannot surface to breathe. Additionally, they are also hunted by the locals for their oil and meat.
The conservation of the Indus River dolphin is also important because it's the flagship species―the ambassador of its natural habitat. The authorities have no doubt made some efforts to save this species. In 1974, for instance, the 125-mile Guddu-Sukkur segment of the Indus was declared the Indus Dolphin Reserve. Environmentalists though, believe that more needs to be done, or else this species will be only seen in the IUCN Red List a few years from now.