Gangetic dolphin – Fresh water Dolphins

River dolphins are a group of freshwater cetaceans that inhabit various river systems across Asia and South America. The Six Surviving River Dolphin Species include: Amazon, Ganges, Indus, Irrawaddy, Tucuxi, and the Yangtze finless porpoise.The Chinese river dolphin was deemed 'probably extinct' in 2007.

As per the IUCN Red list, Yangtze finless porpoise are classified as Critically Endangered.Amazon, Ganges, Indus, Irrawaddy and Tucuxi are labeled as Endangered.

Note: The Yangtze finless porpoise is the world’s only freshwater porpoise but it is included with the other freshwater cetaceans under the umbrella name ‘river dolphins’.

The Amazon river dolphin also known as the pink river dolphin or boto is the largest river dolphin.

About Gangetic River dolphin

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.

Global Declaration for River Dolphins

Recently, 11 Asian and South American countries signed a landmark deal in Bogota, Colombia to save the world’s six surviving species of river dolphins from extinction.This landmark deal signifies a ray of hope in combating the severe decline of river dolphin populations, which have dwindled by a staggering 73% since the 1980s.

Global Declaration for River Dolphins?

The Global Declaration for River Dolphins aims to halt the decline of all river dolphin species and bolster the most vulnerable populations through concerted efforts.It outlines measures such as eradicating gillnets, reducing pollution, expanding research initiatives, and creating protected areas to safeguard the remaining river dolphin species.

Countries that adopted the declaration include: Bangladesh, Bolivia, Brazil, Cambodia, Colombia, Ecuador, India, Nepal, Pakistan, Peru, and Venezuela.

There was also a representative from the regional government in Indonesia that has responsibility for the Mahakam river.

Foundational Pillars:

• • The eight foundational pillars of the Global Declaration for River Dolphins comprise initiatives like establishing a network of protected areas, improving river dolphin site management, expanding research and monitoring efforts, engaging local communities and Indigenous Peoples, eradicating unsustainable fishing practices, enhancing water quality and quantity, promoting World River Dolphin Day (24^th October) to raise awareness, and augment resource allocation and partnerships.

Challenges Faced by River Dolphins:

River dolphins are threatened by diverse factors, including unsustainable fishing practices, hydropower dam construction, pollutionfrom various industries, agriculture, and mining, as well as habitat loss.Also, the recent tragic deaths of over 150 river dolphins in the drought-stricken Lake Tefe in the Amazon illustrate how climate change poses an increasingly severe threat to their survival.

Successful Conservation Efforts:

Conservation efforts in populated river basins like the Indus and Yangtze have seen success.

• • • For instance, the Indus river dolphin population in Pakistan doubled due to joint stakeholder action.
    • Additionally, the Yangtze finless porpoises witnessed a 23% increase in numbers owing to protective measures.

Moreover, the World Wildlife Fund's electronic pinger project saved 80 dolphins in Indonesia's Mahakam river from gill net entanglement.