The population of Irrawaddy dolphins in the Mekong River numbers just 85 individuals and may be on the brink of extinction, according to research by WWF. The researchers also found that calf survival was very low and that the overall population is in decline. A small population living on the border of Cambodia and Lao People's Democratic Republic may be in an even more perilous situation, with just 7 or 8 individuals. This is the only area in Lao PDR where dolphins remain.
The population of Irrawaddy dolphins in the Mekong River numbers just 85 individuals and may be on the brink of extinction, according to research by WWF. The researchers also found that calf survival was very low and that the overall population is in decline. A small population living on the border of Cambodia and Lao People's Democratic Republic may be in an even more perilous situation, with just 7 or 8 individuals. This is the only area in Lao PDR where dolphins remain.
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WWF's research was based on photographic identification of individual dolphins, using unique marks on their dorsal fins to help produce a population estimate.
Although the current population estimate is slightly higher than earlier estimates, the researchers note that more data and more advanced analysis mean that previously unidentified dolphins have now been included, and that the dolphin population has not increased over recent years.
"Evidence is strong that very few young animals survive to adulthood, as older dolphins die off and are not replaced," said Dr Li Lifeng, Director of WWF's Freshwater Programme.
The Irrawaddy dolphin is patchily distributed in shallow, coastal waters in the Indo-Pacific, from the Philippines to north-east India. Freshwater populations also occur in three river systems: the Mahakam of Indonesia, the Ayeyarwady (Irrawaddy) of Myanmar, and the Mekong of Cambodia, Lao PDR and Vietnam.
Although the species as a whole is classified as Vulnerable by the IUCN, the three freshwater populations are classified as Critically Endangered. Irrawaddy dolphins face a number of threats, including entanglement in fishing gear, pollution, the degradation of river systems, dam construction and live capture for aquarium display.
Article continues: http://blog.arkive.org/2011/08/mekong-dolphins-on-brink-of-extinction/
