Tonle Sap

Tonle Sap Great Lake, Cambodia
Cambodia’s Tonle Sap Great Lake is the largest freshwater floodplain lake in the world, increasing and decreasing in size annually from 3000 sq. km at the peak of the dry season in May to 12,000 sq. km in the wet season in October, and varying in depth from 1m to 14m over the same period. This annual flood cycle creates an incredibly productive environment for both wildlife and people. The seasonally inundated forest and scrub around the lake has been recognized since 1994 as the last breeding stronghold in Southeast Asia for a number of globally threatened large waterbirds, particularly pelicans, storks and ibis. Since early 2000, WCS has worked with the Cambodian Government to establish conservation activities in Prek Toal, one of three Core Areas of the Tonle Sap Biosphere Reserve.  The project works to protect the waterbird colonies from egg and chick collection, and to gather baseline research and monitoring data on bird populations and breeding ecology.

The Human Aspect
3.5 million people live on the floodplain around the Tonle Sap and there are 170 floating villages on the lake itself. Fishing is the dominant activity of all the villagers and over 70% of the protein consumed throughout Cambodia is estimated to come from fish from the Tonle Sap.  The Tonle Sap Biosphere Reserve was designated to conserve the wildlife, cultural practices and ecological functions of the lake. 

Threats
The main threat to the large waterbirds of the Tonle Sap is the collection of eggs and chicks from the nest. Turtles and crocodiles are also threatened by hunting. The predominant livelihood activity throughout the lake is fishing, supplemented by other activities in the wet season, including firewood collection and catching watersnakes. The level of threat caused by these last two activities is not yet known.

WCS Activities
WCS works with the local people in several floating villages around the Prek Toal Core Area to protect the nests of large waterbirds during the breeding season.  WCS has formed a local village conservation team, half of whom were former bird collectors, to protect the waterbird colonies in the Prek Toal Core Area. The members of the village team have been trained as conservation rangers and ongoing monthly sessions are held to continue to increase their capacity. A bird population-monitoring program has also been initiated and the rangers are being trained to accurately count the bird colonies on a regular basis and report their findings.  In 2004 population monitoring recorded that breeding numbers of Darter had increased five-fold over the three years since the start of the program. This is solely as a result of the protection activities and demonstrates the remarkable success of the local protection and patrolling activities. This has led not only to a decrease in egg and chick collection, but also to a decrease in the illegal harvesting of other wildlife, including crocodile and turtle hunting. The close proximity of Prek Toal to the temples of Angkor Wat has meant an increasing number of tourists are now visiting the Biosphere Reserve to see the spectacular waterbird colonies. WCS is now working with the Government to develop guidelines to promote sensible ecotourism, taking account of both the conservation of the birds and the livelihoods of the local floating villages.

Important Next Steps
• Consolidate and strengthen the protection activities in Prek Toal, expanding activities to outlying bird colonies
• Continue and expand waterbird population monitoring in Prek Toal
• Continue working with the Government to develop ecotourism guidelines for the Prek Toal Core Area
• Conduct further research to assess the status of threatened mammals, particularly otters and flying-foxes, on the lake
• Conduct research to monitor and better understand the trade in watersnakes and turtles around the lake