First-Ever Estimate of Gangetic Dolphins Reveals 6,327 Across Four States!

First-Ever Estimate of Gangetic Dolphins Reveals 6,327 Across Four States, Highlights Rare Brahmaputra Population!

DILIP DAIMARY

In a landmark effort to conserve India’s national aquatic animal, the first-ever comprehensive survey of Gangetic river dolphins has estimated their population at 6,327 across four states—Uttar Pradesh, Bihar, West Bengal, and Assam.

The survey, which began in 2021 and spanned a cumulative distance of 8,507 km, marks a significant step in understanding and protecting this elusive species.

Notably, the mighty Brahmaputra River of Assam, a lifeline for the region, is home to a rare and distinct population of dolphins that differ subtly from their Gangetic counterparts.

The findings were officially released on Monday (03-03-2025) by Prime Minister Narendra Modi during his visit to Gujarat, where he chaired a meeting of the National Board for Wildlife. Emphasizing the importance of local communities in conservation efforts, PM Modi also called for encouraging school children to visit dolphin habitats to foster awareness and appreciation for the species.

Counting Gangetic dolphins is no easy task. Unlike tigers or elephants, which can be visually identified through unique markings, dolphins are underwater creatures that surface only briefly to breathe. This makes traditional counting methods ineffective. To overcome these challenges, researchers employed innovative techniques, including acoustic hydrophones—underwater microphones that detect sounds emitted by the dolphins.

“Using hydrophones and two sets of observers on boats, we triangulate the presence of a dolphin and ensure the same individual isn’t counted twice,” explained Qamar Qureshi, a former scientist at the Wildlife Institute of India (WII) who was closely involved in the survey.

The Gangetic dolphin, nearly blind and reliant on echolocation for navigation and communication, is uniquely adapted to its riverine habitat. However, its elusive nature and sporadic surfacing behavior—lasting only 5 to 30 seconds—pose significant challenges for researchers.

The survey revealed that Uttar Pradesh hosts the largest population of Gangetic dolphins, followed by Bihar, West Bengal, and Assam. While the Ganga River system remains the primary habitat for these dolphins, the Brahmaputra River in Assam supports a rare and ecologically distinct population.

Dolphins in the Brahmaputra are considered a unique variety, adapted to the river’s dynamic flow and rich biodiversity. Unlike the Gangetic dolphins, which are primarily found in slower-moving waters, the Brahmaputra dolphins thrive in the river’s faster currents and deeper channels. This adaptability makes them a fascinating subject for researchers studying the species’ resilience and ecological role.

One of the most pressing threats to Gangetic dolphins is accidental entanglement in fishing nets. “The major challenge is bycatch, but we are also studying the impact of pollution on their habitat,” Qureshi noted. In the Brahmaputra, additional threats include sand mining, dam construction, and habitat fragmentation, which disrupt the river’s natural flow and affect dolphin populations.

To address these challenges, the Ministry of Environment, Forest, and Climate Change, in collaboration with the WII and the Assam Forest Department, has launched Project Dolphin. A key milestone under this initiative was the first-ever tagging of a Gangetic river dolphin in India, conducted in the Brahmaputra River.

In a groundbreaking effort, a healthy male dolphin from the Kulsi River, a tributary of the Brahmaputra, was tagged and released under veterinary supervision. The lightweight tag, designed to minimize interference with the dolphin’s movement, emits signals compatible with Argos satellite systems, even during the animal’s brief surfacing periods.

“This is a historic milestone for the species and for India,” said Environment Minister . “The tagging will deepen our understanding of the dolphin’s seasonal and migratory patterns, range, and habitat utilization, particularly in the Brahmaputra’s unique ecosystem.”

Virendra R. Tiwari, Director of WII, emphasized the importance of evidence-based conservation strategies. “Tagging river dolphins will provide critical data needed to protect this species, especially in fragmented or disturbed river systems like the Brahmaputra,” he said.

The Gangetic dolphin is not just an iconic species but also an ecological indicator. As an apex predator, it plays a crucial role in maintaining the health of river ecosystems. Its conservation benefits not only aquatic biodiversity but also the thousands of people who depend on these rivers for their livelihoods.

“Understanding the ecological needs of river dolphins is vital for conserving critical habitats within these vast river systems,” said Vishnupriya Kolipakam, WII’s project investigator. “This effort will help sustain both biodiversity and human communities, particularly in the Brahmaputra basin, which is a biodiversity hotspot.”

The next dolphin survey is expected to take place in four years, providing updated insights into population trends and conservation needs. Meanwhile, plans are underway to extend the tagging initiative to other states inhabited by Gangetic dolphins, with a special focus on the Brahmaputra River. This will help build a comprehensive understanding of their population dynamics and habitat requirements.

As India takes bold steps to protect its national aquatic animal, the Gangetic dolphin—and its rare Brahmaputra counterpart—stands as a symbol of the intricate connection between rivers, wildlife, and human communities. Their survival is not just a conservation priority but a testament to the health of India’s lifelines—its rivers.

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