Context:

The first-ever detailed dolphin population survey in India has estimated a total of 6,327 riverine dolphins across the country's major river basins. Conducted between 2021 and 2023, the survey identified 6,324 Gangetic dolphins in the Ganga and Brahmaputra river basins, along with three Indus river dolphins in the Beas river basin in Punjab.

• The study was carried out by the Wildlife Institute of India in collaboration with state forest departments of Punjab, Uttar Pradesh, Bihar, Assam, Jharkhand, and Rajasthan, along with Aaranyak, the World Wildlife Fund, Turtle Survival Alliance, and the Wildlife Trust of India.

Key Findings
The study revealed that the highest number of dolphins were reported in Uttar Pradesh, followed by Bihar, West Bengal, and Assam. Specifically, there was an average of 3,275 dolphins in the main stem of the Ganga, 2,414 in the Ganga tributaries, 584 in the Brahmaputra mainstream, 412 in the Brahmaputra tributaries, and 101 in the river Beas.

Methodology of Counting
Counting dolphins is a challenging task due to their underwater habitat. The research team used hydrophones—underwater microphones—to detect dolphin sounds, relying on the dolphins' echolocation to locate them. Additionally, two sets of observers on the boat ensured that each dolphin was only counted once. This method of triangulating the presence of the dolphins, along with constant boat speed, made the counting process more accurate.

About Ganga River Dolphin: 

The Ganga River Dolphin (Platanista gangetica), also known as the Susu or Tiger of the Ganga, is a unique and endangered species endemic to the Indian sub-continent. 

·        It has a distinctive long thin snout and large flippers that aid in its unique swimming behavior.

·        Further it has a slit-like nostril on top of its head, which acts as a blowhole.

·        It uses ultrasonic waves for hunting and navigation. Its unique swimming pattern helps in locating food, and it emits a distinctive "Susu" sound while surfacing to breathe.

·        Female Ganga River Dolphins are larger than males. They give birth to one calf every two to three years.

Conservation Status

IUCN: Endangered

Wildlife (Protection) Act: Schedule-I

CITES: Appendix I

It faces significant threats from unintentional killing, overexploitation of prey, poaching for dolphin oil, habitat destruction, pollution, and population fragmentation due to dams.

For conservation, the Vikramshila Gangetic Dolphin Wildlife Sanctuary in Bihar remains India’s only dedicated dolphin sanctuary. Additionally, Project Dolphin, modeled after Project Tiger, aims to implement special conservation measures for the species.

The Ganga River Dolphin was declared India’s national aquatic animal on October 5, 2009, a date now observed as National Ganga River Dolphin Day.

Conclusion:

This first-ever estimates provides valuable insight into the population of Gangetic dolphins and highlights the need for on-going conservation efforts. The survey's success marks a significant step forward in understanding and preserving these endangered riverine species.