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The population of dolphins in Chilika, India’s largest brackish water lake, and along the Odisha coast has doubled in 2021 compared to 2020.

The population estimation exercise for dolphins and other cetacean species covered almost the entire coast of Odisha.


Prelims, GS-III: Environment and Ecology (Species in news, Conservation of Ecology and Environment, Protected Areas in News)

Dimensions of the Article:

  1. About Chilika Lake
  2. Threats to Chilika Lake ecosystem
  3. About Irrawaddy dolphins
  4. Steps taken to protect Dolphins
  5. Highlights of the population estimation exercise of Dolphins

About Chilika Lake

  • Chilika Lake is a brackish water lagoon, spread over the Puri, Khurda and Ganjam districts of Odisha state on the east coast of India.
  • It is situated at the mouth of the Daya River, flowing into the Bay of Bengal.
  • It is the largest coastal lagoon in India and the second largest brackish water lagoon in the world after The New Caledonian barrier reef.
  • In 1981, Chilika Lake was designated the first Indian wetland of international importance under the Ramsar Convention.
  • It has been listed as a TENTATIVE UNESCO World Heritage site.
  • It is the largest wintering ground for migratory birds on the Indian sub-continent, hosting over 160 species of birds in the peak migratory season.
  • Birds from as far as the Caspian Sea, Lake Baikal, Aral Sea and other remote parts of Russia, Kirghiz steppes of Kazakhstan, Central and southeast Asia, Ladakh and Himalayas come here.
  • Geological evidence indicates that Chilika Lake was part of the Bay of Bengal during the later stages of the Pleistocene period (1.8 million to 10,000 years BP).
INDIA ORISSA Chilika Lake Bengal

Threats to Chilika Lake ecosystem

Over the years, the Chilika lake ecosystem of the lake encountered several problems and threats such as:

  1. Siltation due to littoral drift and sediments from the inland river systems
  2. Shrinkage of water surface area
  3. Choking of the inlet channel as well as shifting of the mouth connecting to the sea
  4. Decrease in salinity and fishery resources
  5. Proliferation of freshwater invasive species and
  6. An overall loss of biodiversity with decline in productivity adversely affecting the livelihood of the community that depended on it
  7. Fights between fishermen and non-fishermen communities about fishing rights in the lake and consequent court cases

About Irrawaddy dolphins

  • Irrawaddy dolphins (Orcaella brevirostris) are found in coastal areas in South and Southeast Asia, and in three rivers: the Irrawaddy (Myanmar), the Mahakam (Indonesian Borneo) and the Mekong (China).
  • The IUCN Red List classifies the Irrawaddy dolphins as ‘Endangered’.
  • The total population of these aquatic mammals in the world is estimated to be less than 7,500 and more than 6,000 Irrawaddy dolphins have been reported from Bangladesh.
  • Dolphin distribution in Chilika is considered to be the highest single lagoon population.

Steps taken to protect Dolphins

  • Setting up of the Conservation Action Plan for the Gangetic Dolphin (2010-2020), which has identified threats to Gangetic dolphins and impact of river traffic, irrigation canals and depletion of prey-base on dolphin populations.
  • Gangetic dolphins have been included in Schedule -I of the Wildlife Protection Act, 1972, which means they have the highest degree of protection against hunting.
  • They are also one among the 21 species identified under the centrally sponsored scheme, “Development of Wildlife Habitat”.

Highlights of the population estimation exercise of Dolphins

  • Three species were recorded during the census, with more than 500 Irrawaddy, bottle-nose and humpback dolphins sighted in 2021, compared with less than 250in 2020.
  • Wildlife activists are elated over the sizeable growth in the population of endangered Irrawaddy dolphins, which are mostly found in Chilika lake.
  • Apart from Chilika, Irrawaddy dolphins were sighted in the Rajnagar mangrove division.
  • The highest growth has been noticed in the case of humpback dolphins.

Reasons for the increase in numbers:

  • The rise in the Irrawaddy dolphin population in Chilika can be attributed to the eviction of illegal fish enclosures.
  • After thousands of hectares of Chilika water were made encroachment-free, Irrawaddy dolphins found unobstructed area for movement.
  • Moreover, due to the COVID-19 lockdown last year, there were comparatively fewer tourist boats on Chilika lake, which made it conducive for dolphins to move from one part of the lake to another.

-Source: Down to Earth Magazine, The Hindu

December 2023