Gangetic River Dolphin

In News

• The Dolphins have started coming back to Ganga river with improvement in the quality of its water through the Namami Gange programme.

About Gangetic River dolphin

• Discovery: 
  • The Ganges river dolphin was officially discovered in 1801.
  • They were declared as the National Aquatic Animal of India in 2009.
• Freshwater species:
  • The Gangetic river dolphin is one of the four freshwater dolphin species in the world. 
    • The other three are the baiji, now likely extinct from the Yangtze River in China, the bhulan of the Indus in Pakistan and the boto of the Amazon River in Latin America.
• Habitat:
  • 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 distribution range of the Ganges river dolphins in India covers seven states namely, Assam, Uttar Pradesh, Madhya Pradesh, Rajasthan, Bihar, Jharkhand and West Bengal.
• Characteristics:
  • The Ganges river dolphins can only live in freshwater and are essentially blind.
  • They are frequently found alone or in small groups, and generally a mother and calf travel together.
  • Females are larger than males and give birth once every two to three years to only one calf.
  • The Dolphin cannot breathe in the water. It surfaces every 30-120 seconds to breathe in fresh air as it is a mammal.
  • Navigation and hunting through a highly developed ‘sonar system’, using echolocation (ultrasonic sounds).
• Different names:
  • They are also known as Susu, Hihu, Blind dolphin, Ganga river dolphin, side swimming dolphin and South Asian river dolphin. 
    • They hunt by emitting ultrasonic sounds, which bounces off of fish and other prey, enabling them to see an image in their mind.
• IUCN Status
  • Ganges river dolphins are listed as Endangered in the IUCN Red List.

Environmental significance

• They are an indicator of a healthy ecosystem. 
• They are the apex predators in the freshwater food chain and their presence indicates that the water is clean and there is a good number of prey species such as fish, turtles, crustaceans etc. 

Threats

• Dam creation, barrages, irrigation projects and fishing are activities that are dividing and isolating populations of the Ganga river dolphin, significantly reducing its range.
• Poachers kill them for their flesh, fat and oil. They are also sometimes injured by machines in the water or accidentally caught in fishing nets. 

Source: TH