IN NEWS: Bengal Records Third-Highest River Dolphin Population in India

ANALYSIS

Introduction

The report “Population of River Dolphins in India (2024)”, released by Narendra Modi under Project Dolphin, estimates India’s river dolphin population at 6,327 individuals.Within this national estimate, West Bengal recorded 815 Gangetic dolphins, making it the third-highest dolphin population state after Uttar Pradesh and Bihar. Additionally, 108 Irrawaddy dolphins were estimated in the Sundarbans, though not included in the river dolphin count.

Key Findings of the Survey

• Total dolphin population (India): 6,327
• Bengal’s contribution:
  • 815 Gangetic dolphins
  • 108 Irrawaddy dolphins (separate estuarine species)
• Survey coverage in Bengal:
  • 2,366 km across 12 rivers
• Key stretches:
  • Farakka–Diamond Harbour (Hooghly): 429 dolphins (highest)
  • Rupnarayan stretch: 167 dolphins
• Encounter rates:
  • Highest: 3.6/km (Bakshi Canal, Howrah)
  • Average: 0.3/km
• Population range estimate:
  • 763 – 870 dolphins

Geographical Distribution

• Bengal ranks third nationallyafter:
  • Uttar Pradesh
  • Bihar
• Rivers surveyed include:
  • Bhagirathi-Hooghly River
  • Rupnarayan River
  • Dwarakeshwar, Haldi, Churni
• Coverage included:
  • Farakka Barrage to Ganga Sagar stretch
  • Indo-Bangladesh border river systems

Distinct Feature:

Bengal hosts two dolphin species:

• Ganges river dolphin (freshwater)
• Irrawaddy dolphin (freshwater + marine adaptability)

Survey Methodology

The survey (2021–2024) used a combination of scientific techniques:

• Coverage:
  • 58 rivers (28 via boats, 30 via road surveys)
• Techniques:
  • Visual observation
  • Hydrophone-based acoustic detection
• Addressed availability error:
  • Dolphins surface only ~1.26 seconds
  • Dive for ~107 seconds
• Hydrophones recorded echolocation clicksto:
  • Detect underwater presence
  • Calibrate visual counts

Significance of the Study

• Provides first detailed regional assessment for Bengal
• Identifies:
  • High-density stretches for conservation focus
• Highlights dolphins as:
  • Bio-indicators of river health
• Helps in:
  • Balancing infrastructure development (Hooghly waterway) with ecology
• Strengthens evidence-based conservation planning

Limitations of the Estimate

• Short surfacing time leads to:
  • Counting challenges
• Dependence on:
  • Acoustic calibration techniques
• Irrawaddy dolphins:
  • Not included in national river dolphin count
• Limited knowledge of:
  • Movement patterns and habitat preferences

Conservation Context

• Major threats:
  • Fishing net entanglement (bycatch)
  • Intentional killing for oil extraction
  • River pollution and anthropogenic pressure
• Increasing concerns:
  • Infrastructure projects (jetties, waterways)
  • Noise pollution affecting echolocation
• Stakeholders involved:
  • Forest Department
  • World Wide Fund for Nature (WWF-India)
  • Central Pollution Control Board
  • International agencies like the World Bank

Way Forward

• Ensure eco-sensitive infrastructure development
• Strengthen:
  • Fishing regulation and awareness
• Expand:
  • Acoustic monitoring and scientific research
• Focus on:
  • Critical habitats (Hooghly, Rupnarayan stretches)
• Address:
  • Noise pollution and habitat disturbance
• Promote:
  • Integrated river basin management

Conclusion

West Bengal’s dolphin population highlights both ecological richness and conservation challenges. While the presence of two dolphin species reflects a healthy and diverse aquatic ecosystem, increasing anthropogenic pressures necessitate a balanced approach between development and conservation.

STATIC PART

Project Dolphin

• Launched: 15 August 2020
• Launched by: Narendra Modi
• Objective:
  • Conservation of river and marine dolphins
  • Promote scientific and community-based conservation
• Focus:
  • Habitat protection
  • Research and monitoring
  • Stakeholder coordination

Central Pollution Control Board (CPCB)

• Established: 1974 (under Water Act, 1974)
• Headquarters: New Delhi
• Functions:
  • Monitoring water and air quality
  • Advising government on pollution control
  • Supporting environmental conservation efforts

WWF-India

• Established: 1969
• Headquarters: New Delhi
• Role:
  • Biodiversity conservation
  • Wildlife protection programmes
  • Policy advocacy and awareness

**Updated - 05 March 2025 | 10:46 AM IST | News Source: Telegraph India**