"In the Ganges as a whole, the river dolphin population declined from 6000 in 1982 to around 2000 in 2005. It is further reduced to less than 1800. Its annual mortality is estimated to be 130-160 animals," Chief Executive Officer of WWF-India, Ravi Singh, told reporters here.
Ganges River Dolphin was declared India's National Aquatic Animal in 2009.
Ahead of the launch of a three-day awareness programme "My Ganga, My Dolphin" campaign in and around Uttar Pradesh from October 5 to 7, Singh said the threatened ecosystem is posing a danger to the existence of fresh water dolphin.
The Ganges River Dolphin, or susu, inhabits Ganges-Brahmaputra-Meghna and Karnaphuli-Sangu river systems of Nepal, India, and Bangladesh. This vast area has been altered by the construction of more than 50 dams and other irrigation-related projects, with dire consequences for the river dolphins, the WWF-India said.
"Industrial actions and intensive agriculture along the course of the river have introduced new threats for the Ganges River Dolphin and its habitats. Use of pesticides and fertilisers have impacted the freshwater biodiversity. Ganges River Dolphin is one of the four freshwater dolphins of the world," it said.
The 'My Ganga, My Dolphin' campaign is being launched to survey the number of Gangetic River Dolphins present across a 2800 km stretch of the River Ganga and its tributaries including Yamuna, Son, Ken, Betwa, Ghagra and Geruwa.
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The total number of dolphins found in the stretch will be announced by Uttar Pradesh Chief Minister Akhilesh Yadav on October 7.
The mammal is listed in the Schedule I of the Indian Wildlife (Protection) Act, 1972 and categorised as "endangered" by the World Conservation Union and enjoys high level of legal protection, nationally and internationally.