Dolphins are one of the oldest creatures in the world along with some species of turtles, crocodiles and sharks. The Ganges River Dolphin was officially discovered in 1801. Ganges river dolphins once lived in the Ganges-Brahmaputra-Meghna and Karnaphuli-Sangu river systems of Nepal, India, and Bangladesh. But the species is extinct from most of its early distribution ranges.
The Ganges river dolphin can only live in freshwater and is essentially blind. They hunt by emitting ultrasonic sounds, which bounces off of fish and other prey, enabling them to “see” an image in their mind. They are frequently found alone or in small groups, and generally a mother and calf travel together. Calves are chocolate brown at birth and then have grey-brown smooth, hairless skin as adults. Females are larger than males and give birth once every two to three years to only one calf.
The habitat of the Ganges river dolphin is within one of the most densely populated areas of the world. Ganges river dolphins and people both favour areas of the river where fish are plentiful and the water current is slower. This has led to fewer fish for people and more dolphins dying as a result of accidentally being caught in fishing nets, also known as bycatch. The Ganges river dolphin is still hunted for meat and oil, which are both used medicinally. The oil is also used to attract catfish in net fishery.
Industrial, agricultural, and human pollution is another serious cause of habitat degradation. Each year, 9,000 tons of pesticides and 6 million tons of fertilizers are used in the vicinity of the river. High levels of pollution can directly kill prey species and dolphins, and completely destroy their habitat. As the top predator, river dolphins have been known to have high levels of persistent toxic chemicals in their bodies, which is likely to adversely affect their health.
The Ganges river dolphin is important because it is a reliable indicator of the health of the entire river ecosystem. The government of India declared it the National Aquatic Animal in 2009.
Source: https://www.worldwildlife.org/photos/karnaphuli-river-bangladesh
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