A population assessment survey of the endangered Ganges river dolphin was made between February and Apil 2005 in the Brahmaputra River starting from Assam-Arunachal border to the India-Bangladesh border. One hundred and ninety seven dolphins were recorded in the entire 856 km river stretch with an encounter rate of 0.23 dolphins per km.
Ganges River dolphins (Platanista gangetica gangetica) occur in the Ganges-Brahmaputra River system primarily in India and Bangladesh. They are listed as Endangered by the IUCN due to a probable population decline of at least 50% over the last 50 years and projected future population declines. No quantitative estimates of abundance are available for the Ganges River
