India’s First River Dolphin Population Survey: Key Findings and Conservation Insights

India’s river systems are home to two distinct species of river dolphins: the Ganges River Dolphin (Platanista gangetica) and the Indus River Dolphin (Platanista minor). These elusive creatures, often referred to as the “Tigers of the Ganga,”. And serve as vital indicators of the health of freshwater ecosystems. In a pioneering effort to understand and conserve these endangered mammals, India conducted its first comprehensive river dolphin population survey between 2021 and 2023. The findings, released on March 3, 2025. And offer critical insights into the current status of these species and underscore the importance of targeted conservation strategies. Read more about India’s first river dolphin population survey.

Survey Overview

The survey, orchestrated by the Wildlife Institute of India under the Union Environment Ministry, spanned eight states and encompassed 28 rivers. And including major channels and tributaries of the Ganga and Brahmaputra rivers, as well as the Beas River in Punjab. Over 8,500 kilometers were meticulously examined over a span of 3,150 man-days. And making it one of the most extensive freshwater assessments globally.

Key Findings

• Population Estimates: The survey estimated a total of 6,327 river dolphins across the surveyed regions. Uttar Pradesh emerged as the state with the highest number of dolphins, recording 2,397 individuals. Bihar followed with 2,220 dolphins, West Bengal with 815, and Assam with 635. Notably, the Beas River in Punjab reported only three Indus River Dolphins, highlighting a critical conservation concern for this species.
• Distribution Patterns: The Ganga’s main stem harbored approximately 3,275 dolphins, while its tributaries supported around 2,414 individuals. The Brahmaputra’s main channel was home to about 584 dolphins, with an additional 51 in its tributaries. These figures underscore the significance of both primary rivers and their tributaries in sustaining dolphin populations.

Survey Methodology

Detecting river dolphins poses unique challenges due to their brief surfacing times and the turbid waters they inhabit. To address these challenges, the survey employed a combination of visual and acoustic monitoring techniques:

• Visual Surveys: Depending on river depth and width, different visual survey methods were employed. For deep and wide channels, the double observer method was used, where two teams positioned on different decks covered different angles around the vessel on its left and right flanks. For narrower channels, tandem and single boat methods were utilized.
• Acoustic Monitoring: Underwater microphones, or hydrophones, captured the echolocation clicks produced by dolphins. This method allowed researchers to detect individuals that might have been missed during visual observations, providing a more comprehensive population estimate.

Identification of Hotspots and Coldspots

The survey identified specific river stretches with varying dolphin densities:

• Hotspots: Certain stretches exhibited high dolphin densities, termed ‘hotspots.’ For instance, in Bihar, the Chausa-Manihar stretch spanning 590 kilometers had an encounter rate of 2.20 dolphins per kilometer. Similarly, the stretch between Manihari in Bihar and Rajmahal in Jharkhand had an encounter rate of 2.75 dolphins per kilometer.
• Coldspots: The survey identified the 366-kilometer stretch from Narora to Kanpur in Uttar Pradesh as a ‘coldspot’ due to its sparse or absent dolphin populations, with an encounter rate of just 0.1 dolphins per kilometer.

Conservation Implications

The survey’s findings have profound implications for river dolphin conservation in India:

• Targeted Conservation Efforts: Identifying hotspots allows for focused conservation initiatives in areas with high dolphin densities, ensuring the protection of critical habitats.
• Addressing Threats in Coldspots: Recognizing coldspots highlights regions where dolphin populations are declining or absent, prompting investigations into underlying causes such as pollution, habitat degradation, or anthropogenic disturbances.
• Policy Formulation: Accurate population data enables policymakers to allocate resources effectively, develop evidence-based conservation strategies, and engage local communities in preservation efforts.

Challenges Ahead

Despite the comprehensive data gathered, several challenges persist:

• Anthropogenic Pressures: River dolphins face threats from pollution, riverbed mining, low water depth, habitat damage, prey decline, and climate change.
• Limited Visibility: Dolphins’ brief surfacing times and turbid water conditions make monitoring and population estimation inherently challenging, necessitating continuous methodological advancements.

Future Directions

Building on the survey’s insights, several steps are essential for the future:

• Community Engagement: Involving local communities in conservation efforts fosters stewardship and ensures the sustainability of initiatives. Educational programs can raise awareness about the ecological significance of river dolphins.
• Policy Integration: Incorporating survey findings into national and state-level conservation policies ensures that strategies are data-driven and address the specific needs of dolphin populations.
• Research and Monitoring: Continuous research is vital to monitor population trends, understand behavioral ecology, and assess the effectiveness of conservation interventions.

Conclusion

India’s inaugural river dolphin population survey marks a significant milestone in the nation’s conservation journey. The comprehensive data obtained provides a foundation for informed decision-making and strategic interventions. As stewards of these majestic creatures, it is imperative to translate these findings into actionable conservation measures. And ensuring that river dolphins continue to thrive in India’s waterways for generations to come.

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