For the first time, a population of Gangetic River Dolphins has been found in the Mahananda river, in Bihar’s Kishanganj district. The presence of dolphins is the sign of a healthy river ecosystem.
• Mahananda river is a tributary of the Ganga.
• It originates from the Himalayas in Darjeeling, West Bengal.
• The river flows through Bihar, West Bengal, and then continues south-eastward to join the Ganga at Godagari in Bangladesh.
▪ The Ganges river dolphin is found in parts of the Ganges, Meghna, and Brahmaputra river systems in India, Nepal and Bangladesh.
▪ They are locally known as Susu, which refers to the noise the dolphin is said to make when it breathes.
▪ The Gangetic river dolphin is India's national aquatic animal.
Behaviour and Habitat:
o They are generally blind and can detect only the direction of light.
o They emit an ultrasonic sound which reaches the prey. The dolphin then registers this image in its mind and subsequently catches hold of its prey.
o In fact, these dolphins live by echolocation. They navigate, feed, escape danger, find mates, breed, and nurse babies by echolocation.
o Dolphins prefer water that is at least five to eight feet deep.
o Gangetic dolphins live in a zone where there is little or no current, helping them save energy. If they sense danger, they can dive into deep waters.
Threats to dolphins:
▪ Water Level: Declining water in the river, putting more pressure on the dolphins to manage their life cycle.
▪ Climate change: The increasing pollution due to large scale discharge of industrial and municipal waste, siltation, and mechanised boats pose one of the biggest threats to these freshwater dolphins.
▪ Poaching: They frequently fall prey to poachers. Their carcasses are found frequently on river banks.
* IUCN Status: Endangered
* It is listed on CITES Appendix I
* It is classified under Schedule 1, Wildlife (Protection) Act, 1972 providing absolute protection as offences under these are prescribed the highest penalties.
■ The Gangetic river dolphin is one of the four freshwater dolphin species in the world. The other three are found in the Yangtze River in China, the Indus river in Pakistan and the Amazon river in South America. Vikramshila Gangetic Dolphin Sanctuary
■ It is located in Bhagalpur district of Bihar, India.
■ The sanctuary is a 50 km stretch of the Ganges River from Sultanganj to Kahalgaon.
■ It was designated as a protected area for the endangered Gangetic dolphins in 1991.