Cambodia's population of critically endangered Irrawaddy river dolphins has increased by one – and the new arrival is a small but hopeful sign for the future of the species.  

Image: WWF Cambodia/used with permission

These rare, freshwater-dwelling dolphins are found in coastal areas in south and southeast Asia, in just three rivers: the Ayeyarwady (Myanmar), the Mahakam (Indonesian Borneo) and here, in the Mekong river of Cambodia, where just 80 individuals remain. 

Over the last decade, human encroachment, gill-net fishing, poaching and poisoning have pushed the Irrawaddy dolphin to the brink of extinction, but a recent survey suggests the animals could be on the road to recovery. "Their annual rate of decline has slowed from approximately 7 percent per year in 2007 to the current rate of 1.6 percent in 2015," says WWF Cambodia. "This is thanks to years of work by the Fisheries Administration and WWF in protecting their habitat." 

A close relative of the Australian snubfin dolphin, the Irrawaddy (Orcaella brevirostris) is one of seven species of river dolphins. The blue-grey animals are notoriously shy of boats, making surveys like this one particularly difficult. Depsite their smiley appearance (all thanks to a round melon, reduced beak and a mouth line that angles up), life for these creatures is not easy.

Unlike some of their "sweet water" kin, Irrawaddy dolphins can live in both fresh and salt water, but it's the freshwater residents who are considered critically endangered. The river basins they call home also support over 15 percent of our planet's human population, and include some of the most densely populated areas on earth.

The animals give birth only every two to three years, so each new addition is extremely precious cargo. The latest arrival was last seen in Kampi pool, a slow-moving section of the river that plays home to some 20 dolphins. 

It's not time to celebrate quite yet," urges WWF Cambodia director Sam Ath Chhith. "But we have reason to hope that the Mekong's majestic dolphins are on the way back. Now is not the time for complacency. We need to re-double our efforts to protect them."

river dolphin-4-2016-7-15
Image: WWF Cambodia/used with permission
river dolphin-3-2016-7-15
Image: WWF Cambodia/used with permission

One of the gravest threats to the dolphins is the construction of hydropower dams along the Mekong. One such dam, the controversial Don Sahong in Laos, sits less than two kilometres upstream from a similar deep-river pool, which contains the country's four remaining Irrawaddy dolphins.

Blasts during dam construction affect the rare cetaceans' hearing and sensory systems, but a more serious threat is the dam's potential to strangle the animals' food supply once the structure is completed. 

"The dam would block the only year-round migratory channel for fish and dolphins on that section of the Mekong," says the team. "In addition, pesticides, heavy metals, plastic particles and other contaminants from industry, agriculture and towns can also endanger the dolphins' lives."

Don Sahong is just one of 11 open proposals for hydropower dams on the Mekong River. 

Threats posed by dams make for an uncertain future for the new arrival, but it's not just the dolphins that are at risk. A rerouting of local fish populations could also hamper the world's largest inland fishery, the main source of protein for the region's 60 million people.

WWF Camobia is urging local governments to halt construction plans until further studies on the environmental and social implications of the dams can be completed, but for now, we'll have to keep fingers crossed for the river's newest resident. Just 0.8% of juvenile Irrawaddy dolphins survive to adulthood.

"This is a ray of hope for the recovery of Mekong Irrawaddy Dolphins," says the team. "Because prior to 2013, [that number] was estimated at zero."

WWF Cambodia believes that working with local communities and government is the only way to protect the remaining dolphins. Nearly 70 guards – mostly local villagers – have been stationed along the Mekong to keep an eye out for illegal activity as the dolphin survey continues.  

Image: WWF Cambodia/used with permission


Top header image: WWF Cambodia