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Biodiversity & Environment

Gangetic Dolphins Found in Mahananda River

  • 06 Jul 2019
  • 5 min read

For the first time, a population of Gangetic River Dolphins has been found in the Mahananda river, in Bihar’s Kishanganj district.

  • Dolphins were spotted during a survey conducted by a team of scientists from Vikramshila Biodiversity Research and Education Centre (VBREC) of Tilka Manjhi Bhagalpur University.

Mahananda River

  • 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 southeastward to join the Ganga at Godagari in Bangladesh.
  • According to scientists, the number of dolphins in the Mahananda and its tributaries can be much more than this, as the survey was not conducted in a suitable season.
    • Post monsoon is a suitable season when there is adequate water level.
  • The presence of dolphins is the sign of a healthy river ecosystem.

Gangetic Dolphins

  • 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:
    • The Gangetic Dolphins are generally blind and can detect only the direction of light.
    • 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.
  • In fact, these dolphins live by echolocation. They navigate, feed, escape danger, find mates, breed, and nurse babies by echolocation.
    • Dolphins prefer water that is at least five to eight feet deep.
    • 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.
    • The dolphins swim from the no-current zone to the edges (Turbulent waters) to hunt for fish and return.
  • Threats:
    • 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 regularly on river banks.
    • Protection Status:
      • 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.

NOTE: CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) is an international agreement which aims to ensure that international trade in specimens of wild animals and plants does not threaten their survival.

  • 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.
    • The Amazon river dolphin is also known as the boto or ‘pink river dolphin. It is characterized by its long snout and pale pink color.
    • The Indus river dolphins locally as the Bhulan. They are found in the lower parts of the Indus River in Pakistan. Another small, isolated population can be found in the Beas River in India.

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.
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