Patna: The population of the endangered Gangetic river dolphin is stable along nearly 1,000 km stretch of the river Ganga and its two major tributaries – Gandak and Ghaghra – inBihar. It was revealed by three teams of experts and scientists who undertook the exercise of enumeration of the Gangetic dolphins.
Gopal Sharma, senior scientist at the Zoological Survey of India (ZSI), who led one of the teams, said here that the population of Gangetic river dolphins is stable; it is a positive news for all of us. “We will submit the final findings of the three teams that conducted comprehensive census by March 31 this year, but what we found out is that there are 1,150 Gangetic dolphins,” Sharma said.
Sharma told Newsclick that the outcome of this comprehensive survey is positive for conservation of Gangetic river dolphins. "We are hopeful that the first such move to count the dolphins in rivers of Bihar will help conserve them."
Apart from the one team from ZSI, another team was led by Sameer Kumar Sinha of the Wildlife Trust of India, and the third team was led by Sunil Choudhary, coordinator of Vikramshila Biodiversity Research and Education Centre (VBREC), Tilka Manjhi Bhagalpur University.
According to Sharma, it was the first time that a survey was being conducted simultaneously in the Ganga and its two major tributaries. This is also the first time that a coordinated exercise was planned for the dolphin population assessment.
Sharma, who travelled for 22 days – from Chausa in Buxar district to Mokama in Patna – over a stretch of about 300 km in the river Ganga, to count the number of dolphins, found 300 Gangetic dolphins.
About 700 Gangetic dolphins were found in the river from Mokama to Manihari, a stretch of about 300 kilometres; 100 Gangetic dolphins were found in Gandak, and 50 in Ghaghra rivers along a 400-km stretch.
Vikramshila Gangetic Dolphin Sanctuary in Bhagalpur district – India's only such sanctuary, spread over 50 km along the Ganges – was also part of the survey.
All three teams reportedly conducted surveys in their respective zones on the same days to minimise the possibility of duplication in the dolphin count.
Bihar is home to around half of the estimated 3,000 Gangetic dolphins in the country. The last survey of the dolphins was conducted in a limited stretch in 2012 in Bihar, and nearly 1,500 dolphins were counted then.
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The findings of the survey will help the government take measures for conservation of the dolphins.
Biologist and environmentalist R K Sinha, also known as the 'Dolphin Man', said that dolphins’ presence is a sign of a healthy river ecosystem. “Dolphins prefer water that is at least five feet to eight feet deep. They are usually found in turbulent waters, where there are enough fish for them to feed on,” he said.
Gangetic dolphins live in a zone where there is little or no current, which helps them save energy. If they sense danger, they can dive into deep waters. The dolphins swim from the no-current zone to the edges to hunt for fish and return, he said.
Demand for water from the river has been increasing with rise in temperature. "We need more water, but water level is declining in the river, putting more pressure on the dolphins to manage their life cycle," R.K. Sinha said.
Experts agree that Gangetic dolphins' habitat faces serious threats from climate change. They pointed that increasing pollution due to large-scale discharge of industrial and municipal waste, siltation, and mechanised boats pose the biggest threat to these freshwater dolphins.
The Gangetic river dolphin is India's national aquatic animal, but frequently falls prey to poachers. Their carcasses are found regularly on river banks.
Gangetic river dolphins fall under Schedule I of the Indian Wildlife (Protection) Act, and have been declared an endangered species by the International Union for Conservation of Nature (IUCN).
The Gangetic river dolphin is one of the four freshwater dolphin species in the world. The other three are found in the Yangtze river, China, the Indus river in Pakistan and the Amazon river in South America.
The Gangetic river species – found in India, Bangladesh and Nepal – is blind and finds its way and prey in the river waters through echoes. These dolphins live by echolocation, and sound is everything to them. They navigate, feed, escape danger, find mates, breed, and nurse babies by echolocation.
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