The population of endangered Irrawaddy dolphins at Orissa’s Chilika lake is on the rise, officials said here on Thursday.

According to a recent census, the number of Irrawaddy dolphins in Chilika Lake has increased to 158 from last year’s 146, which indicated a nine per cent rise, they said.

While 86 were counted in the outer channel, 72 others were counted in the central and the southern sector of the lake.

To monitor the status and population dynamics of Irrawaddy dolphin in Chilika, an annual population estimation is carried out in the first week of this month by the Chilika Development Authority (CDA).