BY BUTH REAKSMEY KONGKEA
The World Wide Fund for Nature, also known as the World Wildlife Fund (WWF) announced that Pollution in the Mekong River has pushed the local population of Irrawaddy dolphins to the brink of extinction.
The Mekong River Irrawaddy dolphin (Orcaella brevirostris) population inhabits a 190km stretch of the Mekong River between Cambodia and Lao PDR. Since 2003, the population has suffered 88 deaths over 60 percent of which were calves under two weeks old. The population is now estimated to stand somewhere between 64 and 76 members.
“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,” said Dr. Verné Dove, report author and veterinarian with WWF Cambodia.
Dr. Dove said that researchers found toxic levels of pesticides such as DDT and environmental contaminants such as PCBs during analysis of the dead dolphin calves. These pollutants may also pose a health risk to human populations living along the Mekong that consume the same fish and water as the dolphins.
“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,” he said.
He pointed out that high levels of mercury were also found in some of the dead dolphins. Mercury, suspected to be from gold mining activities, directly affects the immune system making the animals more susceptible to infectious disease.
“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,” said Seng Teak, Country Director of WWF Cambodia.
He also said that limited genetic diversity due to inbreeding was another factor in the dolphin deaths.
“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.
Phay Somany of the Office of Fisheries Administration in the Ministry of Agriculture, Forestry and Fisheries, said that according to investigation and report, a dozen of the old dolphins died every year.
Somany said that the old dolphins were killed by anglers’ nets and diseases caused by chemical contaminants. Inbreeding depression also left them susceptible to the Aeromonas Hydrophila bacteria.
“Now the situation for the Mekong dolphins in Cambodia is getting worse. I am afraid that if we do not take immediate measures to protect them, they will disappear from our waters forever. I think that would be a great shame for our nation,” he told The Southeast Asia Weekly during a telephone interview on June 19.
To protect the dolphins, Somany said that his ministry has been executing law enforcement measures to combat illegal fishing activities. There are also regular patrols along the entire stretch of river know to be inhabited by the aquatic mammals.
He added that his ministry also prohibited fishing nets where the dolphins live and encourage locals to release the animals should they be caught up in old nets.
The Mekong River Irrawaddy dolphin has been listed as critically endangered on the IUCN Red List of Threatened Species. It has been included on this list since 2004, according WWF Cambodia. ////