Patna, March 13 : The endangered Gangetic river dolphin population has been stable in Bihar over the last six years, despite accidental and intentional killing of the mammal in the rivers, an official said here.

The latest survey and dolphin count by the state Dolphin Conservation Committee has revealed that the population of the Gangetic dolphin has stabilised, an official said Tuesday.

"This is good news for all of us, and conservationists and environmentalists are happy that the population of the Gangetic river dolphin has remained unchanged in a 650-km stretch in the state," R.K. Sinha, an expert on Gangetic river dolphins and chairman of the Dolphin Conservation Committee of the state said.

Sinha said that a survey by the committee in a 500-km stretch in river Ganga found 1.5 dolphins per kilometre on concentration parameters, the same as in the survery undertaken in 2006.

In a 150-km stretch in river Gandak, the survey found .55 dolphins per kilometre.

"The stable count of dolphins is encouraging. Breeding has helped the species maintain steady population concentration in the river, irrespective of bio-degradation of habitat and other threats to their survival," the committee said.

Sinha said the survey registered between 775 to 800 sightings of dolphins in river Ganges between Chausa and Sahebganj in Bihar, while 88 sightings of dolphins were recorded in river Gandak.

The survey was undertaken for the preparation of the report of action plan for conservation of dolphins in the state.

"We will submit the draft report of action plan to the state government this month," Sinha said.

Gangetic dolphins, India's national aquatic animal, are killed at an alarming rate by poachers for their flesh as well as oil, which is used as an ointment and considered an aphrodisiac. Their carcasses are regularly found on the river banks.

The Gangetic river dolphin is one of the four freshwater dolphin species in the world. The other three are found in the Yangtze river in China, the Indus river in Pakistan and the Amazon river in South America.

The mammal is covered under the Schedule I of the Indian Wildlife (Protection) Act and has been declared an endangered species by the International Union for Conservation of Nature (IUCN).

Last year, the Bihar government decided to set up a task force for the conservation of the endangered animal.

Earlier this year, a Gangetic dolphin research centre, the first such centre in the country, was set up in the Bihar capital.

The Gangetic river species - found in India, Bangladesh and Nepal - is blind and finds its way and prey in the river waters through echoes.