The Mekong River dolphin is on the brink of extinction due to pollution according to WWF.

The species has been listed as critically endangered on the IUCN Red List of Threatened Species since 2004 with an estimated population of 66-86 individuals inhabiting a 190km stretch of the Mekong River between Cambodia and Lao. There have been 88 recorded deaths since 2003 of which 60% were calves under two weeks old.

Dr Verne Dove of WWF Cambodia said “Necropsy analysis identified a bacterial disease as the cause of the calf deaths. This disease would not be fatal unless the dolphin’s immune systems were suppressed, as they were in these cases, by environmental contaminants”.

Post-mortem analysis of the dead dolphin calves found high levels of DDT, PCBs, dioxins, mercury and other toxic, persistent environmental contaminants.

Dr Dove said “These pollutants are widely distributed in the environment and so the source of this pollution may involve several countries through which the Mekong River flows. WWF Cambodia is currently investigating the source of the environmental contaminants,”

Mercury, suspected to be from gold mining activities, directly affects the immune system making the animals more susceptible to infectious disease.

The Mekong River dolphin is a sub-species of the Irrawaddy River dolphin which is not a true river dolphin in that it lives in estuaries and brackish waters. Other sub-species are found across the Indian sub-continent and South-east Asia with a total population of less than 7,000 animals.

Seng Teak of WWF Cambodia said “A trans-boundary preventative health programme is urgently needed to manage the disease affected animals in order to reduce the number of deaths each year. The Mekong River dolphins are isolated from other members of their species and they need our help. Science has shown that if the habitat of cetaceans is protected then populations can show remarkable resilience,” said Teak.

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