The population of the endangered Gangetic river dolphin has declined at Vikramshila Gangetic Dolphin Sanctuary (VGDS) in Bhagalpur District of Bihar, India’s only sanctuary for its national aquatic animal.
A survey conducted in December 2017 by Vikramshila Biodiversity Research and Education Centre (VBREC) – in partnership with researchers from Ashoka Trust for Research on Ecology and Environment (ATREE), Bengaluru, and Wild Life Institute of India (WII), Dehradun – found that the number of dolphins in the sanctuary had declined to 154 from 207 in 2015.
Gangetic dolphins would suffer from the noise pollution created by large ship propellers, and by dredging. Dredging activity in the area has increased manifold in recent years because the Central government has declared the stretch of the Ganga from Varanasi to Haldia in West Bengal National Waterway Number 1. A channel for heavy ships is being dredged, and a shipping container port in Varanasi is almost ready.
The plan is part of India’s aim for cooperation with Nepal in the transboundary Ganga basin, with a shipping container port meant for goods to be transported to and from Nepal being built in Bihar.
During the monsoon dolphins go to the tributaries and side channels, and return when the water recedes. But in the last two years – when the current dredging activity really started – the dolphins had not returned.
Dolphins are also sometimes killed without intention by being trapped in fish nets or hit by propellers. Poachers kill dolphins for their flesh, fat and oil, which is used as a prey to catch fish, as an ointment and as a supposed aphrodisiac. Dolphins prefer water that is at least 1.5-2.4 metres in depth. They are usually found in water where there is enough fish for them to feed on.