Why in News? 

The first count of Gangetic dolphins found 6,327 dolphins living in the Ganga River and its tributaries according to report released on World Wildlife Day by PM Narendra Modi. 

Survey Method 

• Conducted between 2021-2024, covering 8,507 km. 
• Used acoustic hydrophones to detect dolphins since they rely on echolocation. 
• Boats traveled at a constant speed with two observer teams to avoid double-counting. 

Distribution 

• The count recorded 3,275 dolphins in the main Ganga River, 2,414 in its tributaries, and smaller populations in the Brahmaputra and Beas rivers. 
• Highest dolphin population in Uttar Pradesh, followed by Bihar, West Bengal, and Assam. 

Dolphin Characteristics 

• Habitat: Ganges river dolphins live in freshwater environments. 
• Vision: They are blind and use echolocation to move and find food. 
• Breathing: These dolphins come to the surface every 30 to 120 seconds to breathe. 
• Social Behavior: They usually live alone or in small groups. 
• Reproduction: Mothers give birth to one calf every 2 to 3 years. 

Threats 

• Entanglement in fishing nets is the biggest threat. 
• Ongoing research on the impact of pollution on dolphin habitats. 

Future Surveys: The next estimate is planned in four years.