The Irrawaddy dolphin population in the Mekong River numbers roughly 85, with the survival of new calves very low, suggesting they are at high risk of extinction, environmental group WWF said on Wednesday.
The Irrawaddy dolphins live in a 120 mile section of the Mekong between Kratie, Cambodia and the Khone Falls, which are on the border with Laos.
Fishing gear, especially gill nets, and illegal fishing methods involving explosions, poison and electricity all appear to be taking a toll, with surveys conducted from 2007 to 2010 showing the dolphin population slowly declining, the WWF added.
"Evidence is strong that very few young animals survive to adulthood, as older dolphins die off and are not replaced," said Li Lifeng, director of WWR's Freshwater Programme, in a statement.
"This tiny population is at risk by its small size alone. With the added pressure of gill net entanglement and high calf mortality, we are really worried for the future of dolphins."
Research also shows that the population of dolphins in a small transboundary pool on the Cambodia-Laos border may be as few as 7 or 8, the WWF added, despite the fact that Irrawaddy dolphins are protected by law in both nations.
The group called on Cambodia to establish a clear legal framework to protect dolphins, including steps such as banning gill nets if needed.
"Our best chance of saving this iconic species from extinction in the Mekong River is through joint conservation action," Li said.
Dolphins once ranged from the Mekong delta in Vietnam up through the Tonle Sap in Cambodia, and then up tributaries into Laos, but shot by soldiers and harvested for oil in the past.
Irrawaddy dolphins are found in coastal areas in South and Southeast Asia, and in three rivers: the Mekong, the Ayeyarwady in Myanmar, and the Mahakam in Indonesian Borneo.