The annual census of dolphins began in Odisha's Bhitarkanika national park and Gahirmatha marine sanctuary, officials said on Thursday.

Over 100 wildlife experts were conducting the headcount in a three-day exercise, which began on Wednesday, they said. Each team is equipped with binoculars, GPS sets, rangefinders and data recording sheets for a foolproof headcount of the dolphins, officials of the Chilika Development Authority said.

The exercise was being conducted using the 'Transact Survey Method', followed worldwide, they said. The Odisha coast has emerged as an ideal habitat for dolphins with an impressive rise of 33 per cent in their population, officials said, quoting the last census. A total of 726 dolphins were sighted during the census conducted in the last December-January season in the five coastal divisions in Chilika lagoon, they said. Six species of dolphins -- Irrawaddy, Bottlenose, Humpback, Striped, Finless and Spinner -- were recorded during the last census, they added.?