The sound came first, a sharp blowing sound from somewhere in the muddy waters of the Mekong River. Then Phong Choeun got a brief, breath-catching glimpse of what he had been looking for - the blue-gray fin of an irrawaddy dolphin.
Villagers had warned him that sightings of these freshwater mammals are increasingly rare, he says. And as his long-tail boat bobbed quietly on the river, Phong Choeun decided he would do whatever he could to save the few that were left.
Protecting the dolphin is crucial for reasons beyond saving the species, says Ian Baird, a Laos-based researcher, who wrote a recent study on dolphins in Cambodia. The dolphins' presence is indicative of a rich river ecosystem, says Baird. "You save the Mekong River dolphin and you save the Mekong as a whole."
But Phong Choeun, a Cambodian development aid worker, knows he is running out of time. The dolphins are not being killed intentionally, but dwindling fish stocks mean fishermen are using more destructive practices to bring in their catch. Heavy boat traffic on the river is also a problem.
Thousands of the snub-nosed dolphins once played in the Mekong, but experts believe there are now fewer than 100. The march toward economic development that has put the rest of the world's freshwater dolphins on the edge of extinction has finally caught up with the irrawaddies.
"With great effort at this point they can be saved, but they have to start now and be vigilant," says Baird.
No dolphin survey of Cambodia's river systems had ever been conducted before Baird spent three weeks in 1997 counting dolphins and mapping their habitats. He says what he and team member Phong Choeun discovered was alarming. Only 40 dolphins were spotted and, with reports from other areas, Baird believes only 80 are left in Cambodia.
The irrawaddy's habitat extends from the Bay of Bengal to northern Australia, and examples can be found both in rivers and coastal areas. But Baird believes that, after centuries of separation, the irrawaddy in the Mekong has become genetically different from its cousins elsewhere.
Besides the irrawaddy, there are only four species of freshwater dolphins in the world: the baiji in China's Yangtze River, boto in the Amazon, and bhulan and susu dolphins in Asia's Ganges and Indus River systems. The threats are similar worldwide. Pollution, dams, boat traffic, and destructive fishing practices are destroying the dolphin's river habitats.
Some, such as the boto in South America, are still abundant. But the Whale and Dolphin Conservation Society, based in Bath, England, calls the situation "critical" for China's baiji dolphins, believed to number only 100.
It takes six to eight years for a river dolphin to reach sexual maturity, and a pregnancy, which lasts 10 to 11 months, produces only one offspring. For several of the species, including the irrawaddy, there may not be enough dolphins left to breed a healthy group, says Baird.
Conservation efforts have met with mixed success.
China opened a semi-natural reserve on an oxbow lake on the Yangtze several years ago and tried to relocate its remaining baiji dolphins to the reserve.
International support waned for this approach after several of the baiji died, says Alison Smith, director of the Whale and Dolphin Conservation Society. Environmental groups are now encouraging the Chinese to protect the river itself.
Efforts to set up a sanctuary for river dolphins on a stretch of India's Ganges River in 1991 also stalled until recently. Smith's organization is trying to revive the project with funds for a community management plan, educational campaign, and a warden to enforce the regulations.
Other projects have proven more successful.
In the heart of the Colombian Amazon, the number of pink botos unintentionally caught by fishermen has dropped significantly since a research and public awareness campaign began in 1991, says Smith.
Laos's conservation efforts are also bearing fruit. Baird has helped set up locally managed "fish conservation zones" along the Lao-Cambodian border stretch of the Mekong. After several years it is beginning to pay off, he says, with fishermen reporting increased fish stocks as well as the continued presence of irrawaddies. And ecotourism is flourishing as foreign visitors make their way down to the border area to see the dolphins.
For dolphin conservation projects to work, Smith says, the involvement of the local community is critical. "People have to understand the benefits to themselves of implementing conservation strategies for fish and dolphins," she says. "Unless local people are involved and committed to the initiative, it won't work."
Cambodia's Phong Choeun is trying to replicate the Lao fish conservation program, and there have been several seminars in the country to discuss conservation and raise alarm. But local environmentalists say a more concerted action plan needs to be implemented immediately if there is to be any hope of preserving the country's remaining dolphins.