Relevance:

• GS 3 || Environment || Biodiversity || Marine Organisms

Why in the news?

The population of dolphins in Chilika, India’s largest brackish water lake, and along the Odisha coast has doubled this year compared with last year.

Present context:

The wildlife wing of the State Forest and Environment Department released the final data on the dolphin census conducted in January and February this year, indicating a spectacular growth in numbers.

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).
• They are ‘Endangered’ as per the IUCN Red List.
• The total population of these aquatic mammals in the world is estimated to be less than 7,500.
• More than 6,000 Irrawaddy dolphins have been reported from Bangladesh.
• Dolphin distribution in Chilika is considered to be the highest single lagoon population.
• Divided into 41 units, wildlife activists, academicians, Forest Department officials, NGO members, boat operators and researchers from the Bombay Natural History Society, Mumbai, participated in the estimation exercise.
• The population estimation exercise for dolphins and other cetacean species covered almost the entire coast of Odisha.
• Three species were recorded during the census, with 544 Irrawaddy, bottle-nose and humpback dolphins sighted this year, compared with 233 last year.
• The highest growth has been noticed in the case of humpback dolphins. Only two humpbacks were sighted in the Rajnagar mangrove in 2020. In 2021, however, this population grew astronomically to 281
• About Indian Ocean Humpback dolphins:
  • The Indian Ocean Humpback Dolphin occurs within the Indian Ocean from South Africa to India
  • The International Union for Conservation of Nature (IUCN) categorizes the Indian Ocean Humpback Dolphin as Endangered
  • In India, Dolphins are endangered cetacean species, protected under Schedule I of the Wildlife Protection Act, 1972
  • Indian Humpback Dolphin is listed in Appendix I of The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES)

About Chilika Lake:

• Chilika Lake is a brackish water lagoon that spans the districts of Puri, Khurda, and Ganjam in Odisha, India’s east coast.
• It’s at the mouth of the Daya River, which empties into the Bay of Bengal.
• After the New Caledonian barrier reef, it is India’s biggest coastal lagoon and the world’s second largest brackish water lagoon.
• Chilika Lake was named the first Indian wetland of international significance under the Ramsar Convention in 1981,
• It is now a Tentative UNESCO World Heritage site.
• In the peak migratory season, it hosts over 160 species of birds, making it the largest wintering ground for migratory birds on the Indian subcontinent.
• Birds flock here from as far away as the Caspian Sea, Lake Baikal, the Aral Sea, and other remote parts of Russia, Kazakhstan’s Kirghiz steppes, Central and Southeast Asia, Ladakh, and the Himalayas.
• According to geological data, Chilika Lake was once a part of the Bay of Bengal during the Pleistocene epoch (1.8 million to 10,000 years BP).

Threats to Chilika Lake ecosystem

• The Chilika lake ecosystem has faced a number of problems and threats over the years, including:
  • Littoral drift and sediments from inland river systems cause siltation.
  • Water surface area shrinkage,
  • Clogging of the inlet channel, and shifting of the mouth connecting to the shore.
  • Salinity levels are dropping, and fisheries resources are dwindling.
  • Proliferation of freshwater invasive species and
  • An overall loss of biodiversity, combined with a drop in productivity, has harmed the livelihood of the population that relied on it.
  • Fights for fishing rights in the lake between fishermen and non-fisherman groups, and the resulting court cases.

Issues with the existence of Dolphins

• Climate change: The effects of climate change on the ocean is reaching an alarming state, especially for dolphins. Ocean temperatures are on the rise. Data from the US National Oceanic and Atmospheric Administration (NOAA) shows that the average global sea surface temperature – the temperature of the upper few meters of the ocean – has increased by approximately 0.13°C per decade over the past 100 years. The change affects feeding grounds and migratory pathways.
• Commercial harvest: Dolphins carry a dangerously high level of mercury and other contaminants in their flesh, but are still harvested for food at an alarmingly high rate. Japan is recognized for its large dolphin harvest, which occurs despite illness and disorders documented in humans directly linked to the consumption of dolphin.
• Entanglement: It’s easy for dolphins to become entangled in fishing wire or net, as many types of the material are transparent and difficult for the dolphin to recognize and avoid. Because dolphins breathe through lungs rather than gills, it’s crucial that they can reach the water’s surface to gain oxygen. Entanglement ca easily drown a dolphin, pushing many species to the brink of endangerment or extinction.
• Habitat loss: Man-made fixtures like dams, waterfront residential and commercial development, and boat traffic destroy the habit of river dolphins each

Steps taken to protect Dolphins

• Establishment of the Gangetic Dolphin Conservation Action Plan (2010-2020), which identifies threats to Gangetic dolphins as well as the effect of river traffic, irrigation canals, and prey loss on dolphin populations.
• Gangetic dolphins are protected under Schedule I of the Wildlife Conservation Act of 1972, which means they are protected from hunting to the greatest extent possible.
• They’re also one of 21 species listed under the federally funded “Creation of Wildlife Habitat” program.
• Highlights of the population estimation exercise of Dolphins
• More than 500 Irrawaddy, bottle-nose, and humpback dolphins were seen in 2021, compared to fewer than 250 in 2020, according to the census.
• Wildlife activists are ecstatic about the significant increase in the population of endangered Irrawaddy dolphins, which are mostly found in Chilika Lake.
• Irrawaddy dolphins have been seen in the Rajnagar mangrove division, in addition to Chilika.
• In the case of humpback dolphins, the fastest rate of development has been observed.

Reasons for the increase in numbers:

• The eviction of illegal fish enclosures in Chilika has resulted in an increase in the number of Irrawaddy dolphins.
• Irrawaddy dolphins discovered an unobstructed space for travel after thousands of hectares of Chilika water were rendered encroachment-free.
• Additionally, due to the COVID-19 lockdown last year, there were fewer tourist boats on Chilika Lake, allowing dolphins to travel from one section of the lake to another.

Mains oriented question:

River ecosystem plays an important role in maintaining the entire ecosystem sudden change in Climate has made all ecosystem unbalanced from river to forest, what are the steps taken to conserve the ecosystem in recent time how fruitful it has been yet, Elaborate. (250 words)