for National Geographic News
Editor's Note: After this story was published, Touch Seang Tana, chair of Cambodia's Commission for Mekong Dolphin Conservation, said that the population estimates he cited were for 1999 to 2006 and not 2006 to 2007. The story appears here in its original form.
Asia's critically endangered Irrawaddy river dolphin may be in greater danger of extinction than ever, scientists say—and not less, as the government of Cambodia recently announced.
According to Touch Seang Tana, chair of Cambodia's Commission for Mekong Dolphin Conservation, there are now about 160 dolphins in the upper Mekong River, up from only 90 when the Cambodian government banned the practice of net fishing last year (see map of Cambodia).
But researchers who study the rare dolphin have expressed deep skepticism that such a dramatic turnaround could have occurred.
They said it would be biologically impossible for the dolphins to rebound so quickly, because their gestation period is 11 months and the animals generally only have one offspring every two years.
There are no dolphins from other areas that could have moved into the upper Mekong River once nets were removed, the researchers added.
"It's impossible that the dolphin population would have increased substantially in only one year," said Isabel Beasley, a Ph.D. candidate at Australia's James Cook University who researched dolphins in the Mekong River from 2001 to 2005.
"The mortality [in recent years] is too high and 95 percent of dolphins in the river already occurred in the areas where the nets were banned."
Dams and Boat Traffic
Two to three meters (seven to ten feet) long, the Irrawaddy river dolphin is similar in appearance to the better known beluga whale. Also known as the Mekong River dolphin, the Irrawaddy is found near coasts and in estuaries in parts of southeast Asia and Australia.
The Irrawaddy's three river populations are some of the most critically endangered dolphins known to exist.
As of April 2005 Irrawaddy dolphins numbered between 127 and 161 in the entire Mekong River, according to Beasley.
SOURCES AND RELATED WEB SITES