Irrawaddy dolphins could disappear from the Mekong river if action is not taken soon. That's the message from the World Wildlife Foundation (WWF), having conducted 11 studies of dolphin populations in the area between 2007 and 2010. The organisation believes that there could be fewer than 85 dolphins left in the river and that number is continuing to fall.

The distinctive dorsal fin of the Irrawaddy dolphin was once seen in great numbers up and down the Mekong river, but hunting and illegal fishing methods has decimated the numbers to near-extinction level.

It was also found that calves are experiencing high levels of mortality suggesting that pollution may also be playing its part in the demise of the Irrawaddy dolphin.

Using the unique shape of each dolphin's dorsal to identify individual dolphins, the WWF research team was able to accurately estimate dolphin numbers during a number of visits to the area. At the last count, the team noted a population of between 78 and 91.

Significantly, however, high levels of birth mortality implied that the population is still in decline.

Dr Li of the WWF Freshwater Programme said: "Evidence is strong that very few young animals survive to adulthood, as older animals die off and are not replaced."

It all points to a very real chance that the dolphins will become extinct in the Mekong river unless immediate action is taken.

"Our best chance of saving this iconic species from extinction in the Mekong river is through joint conservation action," said Dr Li.

"WWF is committed to working with the Fisheries Administration, the Dolphin Commission, and communities all along the river to reverse the decline and ensure the survival of this beautiful species in the Mekong."

The WWF has recommended that the Cambodian government introduce dolphin conservation zones, as well as ban, or, at the very least, limit, the use of gillnets to prevent further losses to the Irrawaddy dolphin population.