Pollution in the Mekong River has pushed the local population of Irrawaddy dolphins to the brink of extinction, a new report by WWF has revealed.
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 of which over 60 percent were calves under two weeks old. The latest population is estimated 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.
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,” said Dr Dove.
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.
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 Mr Teak.
The Mekong River Irrawaddy dolphin has been listed as critically endangered on the IUCN Red List of Threatened Species since 2004.
Mekong river dolphin 'nearly extinct'
Patrick Falby Yahoo News 18 Jun 09;
PHNOM PENH (AFP) – Pollution in southeast Asia's Mekong River has pushed freshwater dolphins in Cambodia and Laos to the brink of extinction, a conservation report said Thursday, sparking a furious government denial.
The WWF said only 64 to 76 Irrawaddy dolphins remain in the Mekong after toxic levels of pesticides, mercury and other pollutants were found in more than 50 calves who have died since 2003.
"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," said WWF veterinary surgeon Verne Dove in a press statement.
The organisation said it was investigating how environmental contaminants got into the Mekong, which flows through Cambodia, Laos, Myanmar, Thailand, Vietnam and the southern Chinese province of Yunnan.
However, the Cambodian government official tasked with caring for the country's Irrawaddy dolphins said there remained "about 150 to 160" of them in the Mekong, and alleged the WWF's report used flawed research methodology.
"It's big trouble -- they (the WWF) should resign. They should leave Cambodia," Touch Seang Tana, chairman of Cambodia's Commission to Conserve Mekong River Dolphins and Develop Eco-tourism, told AFP.
"They published this without consulting me, and I'm the authority here," he said, adding he did not believe the river contained the pollutants listed in the WWF's report.
The WWF said it suspected that high levels of mercury found in some dead dolphins came from gold mining activities.
It added that Irrawaddy dolphins in Cambodia and Laos urgently needed a health programme to counter the effects of pollution on their immune systems.
Inbreeding among the small population could have also contributed to weakened immune systems in the dead young dolphins, all of whom were under two weeks old.
"The Mekong River dolphins are isolated from other members of their species and they need our help," said WWF Cambodia country director Seng Teak, adding the mammals "can show remarkable resilience" if their habitat is protected.
The Mekong River Irrawaddy dolphin, which inhabits a 190-kilometre (118-mile) stretch in Cambodia and Laos, has been listed as critically endangered since 2004, the WWF said.
Thousands of Irrawaddy dolphins once swam in the Mekong. Although regarded as sacred in Cambodia and Laos, their numbers were cut by the use of illegal fishing nets and Cambodia's drawn-out civil conflict, in which dolphin blubber was used to lubricate machine parts and fuel lamps.
The Cambodian government, however, has been promoting dolphin-watching to attract eco-tourism and cracked down on the use of illegal nets which entangled them.
It hopes such measures and establishing protected areas will raise their numbers over the next few years.
The Mekong is one of only five freshwater habitats in the world for the Irrawaddy dolphin, and Cambodia is thought to support its largest remaining population.
With their pale grey skin and blunt beaks, Irrawaddy dolphins resemble porpoises more than their sea-going cousins, and congregate in a handful of the Mekong's natural deep-water pools.
The river is the world's largest inland fishery, producing some 2.5 million tonnes of fish per year valued at more than 2 billion dollars.
The Mekong also provides 80 percent of the animal protein for 60 million people who live along its lower basin.
Mekong dolphins 'almost extinct'
BBC News 18 Jun 09;
Pollution in the Mekong river has pushed freshwater dolphins in Cambodia and Laos to the brink of extinction, the conservation group WWF has said.
Only 64 to 76 Irrawaddy dolphins remain in the Mekong, it says, and calls for a cross-border plan to help the dolphins.
Toxic levels of pesticides, mercury and other pollutants have been found in more than 50 calves that have died since 2003.
The Mekong flows from China through Laos, Cambodia, Thailand and Vietnam.
"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," said WWF veterinary surgeon Verne Dove in a press statement.
Critically endangered
The group said it was investigating how contamination had entered the Mekong river.
Since 2003, the dolphin population has suffered 88 deaths, of which more than 60% were calves under two weeks old, it said.
"Necropsy analysis identified a bacterial disease as the cause of the calf deaths," Dr Dove said in the WWF report.
"This disease would not be fatal unless the dolphin's immune systems were suppressed, as they were in these cases, by environmental contaminants," he said.
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 - who consume the same fish and water as the dolphins - the group suggested.
High levels of mercury were also found in some of the dead dolphins, which 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.
The Mekong River Irrawaddy dolphin, which inhabits a 190 km (118 mile) stretch in Cambodia and Laos, has been listed as critically endangered since 2004, the WWF said.
The Irrawaddy dolphin is also seen in parts of South Asia.
There too it has dwindled in numbers, although last year thousands of Irrawaddy dolphins were found in Bangladeshi waters when they were previously thought to be extinct in the area.