Aquatic Mammals of India

India hosts a variety of aquatic mammals in its extensive river systems, lakes, and surrounding seas. The iconic mammal species include Ganges River Dolphin, Sea Cow / Dugongs, some species of threatened whales and dolphins etc.

Dolphins

Ganges River Dolphin

Government of India has notified the Ganges River Dolphin (Platanista gangetica gangetica) as India’s National Aquatic Animal. It is also known as Susu because of the sound it produces when breathing.  The Total population of Ganges River Dolphin is estimated to be around 2000 and they inhabit the Ganges-Brahmaputra-Meghna and Karnaphuli-Sangu river systems of Nepal, India and Bangladesh.

These dolphins are found in Assam, Uttar Pradesh, Madhya Pradesh, Rajasthan, Bihar, Jharkhand and West Bengal (7 states ) and ideal habitats are in the Ganga, Chambal, Ghaghra, Gandak, Sone, Kosi, the Brahmaputra and Kulsi rivers.

Ganges River Dolphin is placed under “Endangered Category” in the IUCN Red List. It lives in one of the world’s most densely populated areas, and is threatened by removal of river water and siltation arising from deforestation, pollution and entanglement in fisheries nets.  They have been poached over for their oil. The habitat degradation due to declining flow, heavy siltation and construction of barrages causing physical barrier for this migratory species is also one of the reasons behind decline of their numbers.

Other River Dolphins

There are only four true freshwater river dolphins viz. Ganges River Dolphin, Indus River Dolphin, Amazon River Dolphin and Yagtze River Dolphins (now extinct).

• Both Ganges River Dolphin and Indus River Dolphin are now taxonomically considered one species since 1998.
• Irrawady river dolphins can survive in both fresh and marine waters.
• The Amazon River Dolphins are is found in plenty number in Amazon river.
• The Yangtze river dolphins have gone extinct.

Indus River dolphin

The Indus River dolphin (Platanista minor minor) is classified as Endangered with approximately 2,000 remaining. They inhabit the Indus River system mainly in Pakistan and adjacent border river basins in India (Beas & Sutlej).

Irrawaddy dolphin

The Irrawady river dolphins, which can survive both in fresh water and marine water are found in Myanmar, Indonesia and the Mekong river delta in south-east Asia. Some of the Irrawady River Dolphins are also found in Bangladesh and India’s Chilka Lake in Odisha. They have been classified as Vulnerable. Just around 150 dolphins inhabit the lagoon system. Threats from fishing and shrinkage of suitable brackish habitat have stabilized from past decades due to protection measures.

Humpback dolphin

The Indo-Pacific humpback dolphin found along the Indian coastline has an estimated 11,000-13,000 individuals remaining. Due to habitat degradation and bycatch they are classified as Near Threatened.

Common dolphin

Around 100,000 short- and long-beaked common dolphins are found in offshore and coastal waters. They remain relatively abundant around the Indian peninsula though face some bycatch issues.

Dugong / Sea Cow

Dugong or Sea Cow is a seagrass eating mammal which is found in waters of as many as 37 countries. It is now on verge of extinction, because it has been hunted for meat and oil. In India also, its meat is considered to be aphrodisiac.

Maximum Population of Dugong is found in Red Sea, followed by the Persian Gulf.

Largest Dugong was as long as 13.5 ft and was found in Gulf of Katch in India. In India, they are found in Gulf of Kutch, the only population remaining in western India and Gulf of Mannar. The Gulf of Mannar Biosphere (GoMB) has the largest population of dugongs in India. They are also found near the Andaman and Nicobar Islands.

With fewer than 200 dugongs (commonly known as sea cow) in its waters, India is strongly encouraging its neighbours in South Asia to sign the Dugong United Nations Environment Programme/Convention of Migratory Species (UNEP/CMS) MoU as early as possible.

Currently classified as vulnerable under the IUCN Red List of Threatened Species, the dugongs are vulnerable to human-related influences due to their life history and dependence on sea grasses that are restricted to coastal habitats under increased pressure from human activities.

Reasons for the decline in population are sea grass habitat loss and degradation, gill netting, chemical pollutants, indigenous use, and hunting.