Bhubaneswar, Jan. 7: Enumerators, who will count the Irrawady dolphins in the Chilika lake tomorrow, were imparted training in the methodology today.

Sources in the state forest department said more than 80 persons would be engaged in the annual census of the Irrawady dolphins. In 2012, the lake housed 145 Irrawady dolphins.

Presence of the dolphins in the Chilika was first recorded in 1915, but their numbers and movement had remained undocumented. But in 2002, the first systemic survey was conducted to find out the number of the mammals in the largest brackish water lagoon in the country.

The enumerators use the Global Positioning System (GPS) and exact distance range finders to keep a track record of the mammals’ movement.The track routes are pre-determined through computer programming and the track points are preloaded into the GPS sets provided to each team.

In another development, the census of birds in the lake, which concluded yesterday, revealed presence of more than 8.77 lakh birds of 112 various species. The count of birds is around 5,000 less than last year’s bird census. While presence of two new birds — Goliath Heron and Mallard — brought cheers for the forest officials, the number of birds present at Nalaban witnessed an increase of 10 per cent. A forest official said the herons were spotted in the lake for the first time and Mallards were seen after a long gap.

The count included more than one lakh northern pintails and Eurasian wigeons this year. The number of Eurasian wigeons is the highest in the past five years. Similarly, eight near-threatened species of birds, including spotbill Pelican, painted Stork, Asian Dowitcher and black-tailed Godwit, were spotted in the Chilika this year. However, no duck congregation was sighted between Chandraput-Nalaban and Barkul-Balugaon.

The census also revealed a heavy decline of presence of tufted ducks in the lake area.

Principal chief conservator of forest J.D. Sharma expressed concerns over movement of illegal boats in the lake causing ecological disturbance. “More than 700 boats, including the illegal ones, are operating in the lake and posing threat to the ecology. We have informed the district administration and an action plan will shortly be made to curb the boats’ movement in the area,” said Sharma.