First Estimate of Gangetic Dolphins in India

First Estimate of Gangetic Dolphins in India

Sub: Env

Sec: Species in news

Context:

• The first-ever estimate of Gangetic dolphins, India’s only riverine dolphins, recorded 6,327 individuals in the Ganga and its tributaries.
• The study was conducted between 2021 and 2025, covering a cumulative distance of 8,507 km.
• The maximum number of dolphins were reported in Uttar Pradesh, followed by Bihar, West Bengal, and Assam.

Dolphin Population Estimates

• Total population: 6,327 dolphins.
• Ganges river dolphins: 6,324.
• Indus river dolphins: 3.
• Distribution across river systems:
• Ganga main stem: 3,275 dolphins.
• Ganga tributaries: 2,414 dolphins.
• Brahmaputra mainstream: 584 dolphins.
• Brahmaputra tributaries: 412 dolphins.
• River Beas: 101 dolphins.

Challenges in Dolphin Counting

• Dolphins are underwater species, surfacing only occasionally to breathe.
• Unlike tigers (stripes) or elephants (ears), individual dolphins cannot be uniquely identified visually.
• The survey used acoustic hydrophones (underwater microphones) to detect sounds emitted by dolphins.
• Echo-location is the primary mode of communication and movement for these blind animals.

Double counting prevention:

• Used triangulation method with two different observer groups on the boat.

Survey Methodology

• Conducted via boats moving at a constant speed.
• Researchers trained in new techniques for accurate estimation.
• The next survey is planned after four years.

Threats to Gangetic Dolphins

• Fishing nets: Dolphins often get entangled and die.
• Pollution: Studies are underway to analyze its impact on dolphin habitat.

Government Involvement

• Report made public on March 3, 2025 (World Wildlife Day).
• Announced by Prime Minister Narendra Modi during the National Board for Wildlife meeting in Gujarat.
• Local population participation and school visits to dolphin habitats were encouraged for conservation awareness.

Conclusion

• The survey provides a baseline estimate but cannot determine trends over time due to different past methodologies.
• Conservation efforts must focus on reducing fishing net entanglement and mitigating pollution effects on dolphin habitats.