The researchers studied ancient DNA that they got out of skulls and skeletons which were 20 to 30 to even 150 years old of South Asian river dolphins and the detailed analysis has revealed that the Indus and Ganges River dolphins are not one, but two separate species.
Prelims, GS-III: Environment and Ecology (Species in news, Conservation of Ecology and Environment)
Dimensions of the Article:
- Divergent species
- About the Ganges river dolphin and Indus river Dolphin
- Threats to the dolphins
- Steps Taken to conserve and protect dolphins
- Currently, Indus and Ganges river dolphins are classified as two subspecies under a single species – Platanista gangetica – and this needs a revision.
- The study estimates that Indus and Ganges river dolphins may have diverged around 550,000 years ago.
About the Ganges river dolphin and Indus river Dolphin
Ganges River Dolphins
- The Ganges river dolphin (Platanista gangetica gangetica) was officially discovered in the 1800s and these 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 Ganges river dolphin was recognised as the National Aquatic Animal in 2009, by the Government of India.
- The Ganges river dolphin can only survive in freshwater and is essentially blind.
- They are frequently found alone or in small groups, and generally a mother and calf travel together.
Indus river Dolphins
- Indus river dolphins (Platanista minor) are believed to have originated in the ancient Tethys Sea. When the sea dried up approximately 50 million years ago.
- They can now only be found in the lower parts of the Indus River in Pakistan and in River Beas, a tributary of the Indus River in Punjab, India.
- In Pakistan, their numbers declined dramatically after the construction of an irrigation system, and most dolphins are confined to a 750 mile stretch of the river and divided into isolated populations by six barrages.
- They have adapted to life in the muddy river and are functionally blind.
- They rely on echolocation to navigate, communicate and hunt prey including prawns, catfish, and carp.
- The Indus and Ganges River dolphins are both classified as ‘Endangered’ species by the International Union for Conservation of Nature (IUCN).
- The Ganges dolphin is a Schedule I animal under the Indian Wildlife (Protection) Act 1972, and has been included in Annexure – I (most endangered) of Convention on International Trade in Endangered Species (CITES).
- The Ganges dolphin is also listed under Appendix II of the Convention on Migratory Species (CMS) (migratory species that need conservation and management or would significantly benefit from international co-operation).
Threats to the dolphins
- Physical barriers such as dams and barrages created across the river reduced the gene flow to a great extent making the species vulnerable.
- River flow is also declining very fast as river water is being diverted through the barrages and this has affected the dolphin habitats.
- Previously fishermen used to hunt dolphins and use their oil as bait, but though that practice of directed killing has stopped and they are not being hunted intentionally they end up as accidental catches.
- Both point and non-point sources of pollution are also affecting the dolphin habitat.
Threats to Gangetic river dolphin
- Pollution: It faces a number of threats such as dumping of single-use plastics in water bodies, industrial pollution, and fishing.
- Restrictive Flow of Water: The increase in the number of barrages and dams is also affecting their growth as such structures impede the flow of water.
- Poaching: Dolphins are also poached for their flesh, fat, and oil, which is used as a prey to catch fish, as an ointment and as a supposed aphrodisiac.
- Shipping & Dredging: It is also called a blind dolphin because it doesn’t have an eye lens and uses echolocation to navigate and hunt.
Recently, the Chinese river dolphin went extinct and we need to learn from this and have more ground action and close work with local communities to help them survive, besides the legal protection given to the dolphin by the Indian Government.
Steps Taken to conserve and protect dolphins
- Project Dolphin: The Prime Minister announced the government’s plan to launch a Project Dolphin in his Independence Day Speech 2020. It will be on the lines of Project Tiger, which has helped increase the tiger population.
- Dolphin Sanctuary: Vikramshila Ganges Dolphin Sanctuary has been established in Bihar.
- Conservation Plan: The Conservation Action Plan for the Ganges River Dolphin 2010-2020, which “identified threats to Gangetic Dolphins and impact of river traffic, irrigation canals and depletion of prey-base on Dolphins populations”.
- National Ganga River Dolphin Day: The National Mission for Clean Ganga celebrates 5th October as National Ganga River Dolphin Day.
-Source: The Hindu