This paper examines Tonle Sap Lake, the most important inland wetland in Southeast Asia, located in western Cambodia. It surveys the lake's remarkable natural resources — including its world-class freshwater fisheries, diverse wildlife, and seasonal hydrological behavior — and describes how more than three million people depend on it for food, income, and daily life. The paper also profiles the lake's unique floating villages and the social challenges their residents face. Finally, it addresses serious environmental threats: overfishing, destruction of flooded forests, upstream dam construction, illegal fishing practices, and water pollution. The Tonle Sap Biosphere Reserve's conservation mandate and funding structure are also discussed.
Tonle Sap Lake is an enormous resource located in roughly the west-central part of Cambodia. It is, in fact, the "most important inland wetland in Southeast Asia," according to the Cambodia National Mekong Committee report Policy and Strategy for the Tonle Sap Biosphere Reserve (2007). This paper reviews the resources of the lake, including the raw materials that are available, how people live, what resources communities require, how residents cook and what they eat, and the environmental issues that relate to the natural resources and to the people who live near and depend on the lake for their subsistence.
Tonle Sap Lake was created by two tectonic plates coming together and forming a depression. The "geological stress" produced by the "collision of the Indian subcontinent with Asia" (Wikipedia) formed both the lake itself and the surrounding floodplain. Between 40% and 70% of the protein that Cambodians eat annually comes from Tonle Sap Lake.
The lake changes shape and size dramatically depending on the season. During the dry season, Tonle Sap Lake covers about 2,500 square kilometers; during the rainy season it expands enormously, becoming a freshwater lake of some 12,000 square kilometers, according to journalist Mike Ibbertson. In the dry season the lake becomes shallow and drains through the Tonle Sap River into the Mekong River at the capital, Phnom Penh. Between June and November, however, the rains arrive and when the "high water level" is reached in the Mekong River, there is a reverse flow "up the Tonle Sap River into the Tonle Sap Lake." When the lake fills to capacity it becomes "the largest freshwater lake in Southeast Asia" (Ibbertson, 2009). At peak flood, the depth of the lake increases from one meter to ten meters (Dr. Neou Bonheur, Tonle Sap Biosphere Reserve).
Surrounding the lake are mangrove forest plains that are home to over 100 varieties of water birds, including a number of endangered species (Ibbertson). The lake itself contains over 200 species of fish, and the associated wetlands support crocodiles, otters, and turtles. Twenty percent of the Mekong River's floodwaters are absorbed by the Tonle Sap, while 62% of the Tonle Sap's water originates from the Mekong River (TSBR). The remaining 38% originates from the Tonle Sap watershed. Approximately 1.2 million people live in the area bordered by highways #5 and #6. Because the lake's fisheries account for up to 70% of the protein consumed by Cambodians — and because the CIA World Factbook indicates that 35% of Cambodia's population lives below the poverty line — the lake's productivity is of vital national importance.
The CIA World Factbook lists Cambodia's national natural resources as oil and gas, timber, gemstones, iron ore, manganese, phosphates, and hydropower potential. The resources specific to Tonle Sap Lake, however, are equally significant to the country's economy and culture. Most notably, the lake supplies "life to one of Asia's largest rice bowls" (mekonginfo.org), and its fresh water is itself a critical natural resource.
More than 200 species of fish are found in Tonle Sap Lake, and 70 of those species are "of commercial value" (mekonginfo.org). The Tonle Sap Biosphere Reserve fact sheet states that the lake yields "about 230,000 tons of fish" each year — more than 50% of the total fish catch used for food in Cambodia. Tonle Sap is considered one of the "most productive freshwater fisheries in the world," yielding "more than ten times more fish than the North Atlantic Sea" (tsbr-ed.org). Additional natural resources from the lake include eels, crabs, and shrimp.
Wildlife resources are equally diverse. The lake and its inundated surrounding forest are home to 23 snake species, 13 turtle species, one species of crocodile, macaque, capped langur, leopard cat, and otter. The combination of extraordinary fish productivity and rich wildlife makes the Tonle Sap ecosystem one of the most biologically significant inland water bodies in the world.
When the monsoon arrives and the lake fills, the reverse flow of water produces a "nutrient rush" that creates "one of the most productive inland fisheries in the world." The lake supports "more than three million people" and provides "more than three quarters of Cambodia's annual inland fish catch" (Fitzherbert). Nevertheless, the Tonle Sap basin "remains one of the poorest regions in Cambodia" (Fitzherbert).
Historically, large fishing industry concessions dominated Tonle Sap's shoreline; however, many of these areas have recently been returned to local communities. This transition has triggered a domino effect of "overfishing, declining fish stocks, rising fish prices, and a growing demand for cheaper alternatives" (Fitzherbert). As a result, many fishermen — particularly those living in poverty — have shifted from fishing for fish to fishing for snakes.
About four million snakes representing eight species are harvested from Tonle Sap Lake annually, though Virginia Fitzherbert, writing in the journal Geographical, suggests the actual number is "likely to be much higher." This level of take is thought to be "the greatest exploitation of any single snake community in the world" (Fitzherbert). Serious concerns about long-term sustainability have been raised in many quarters.
Fitzherbert witnessed many "crates of snakes being weighed" at the port of Chong Khneas near Siem Reap — more than a ton per day on average — and was shocked by the volume. The snakes are brought ashore by "middlemen who buy directly from fisher families who live out on the lake in settlements" that float. The snakes are then separated and sold: some for skins, some for human food, and some to feed the "thousands of crocodile farms that surround the lake." Crocodile farms purchase more snakes than any other single buyer category.
"Mass snake fishing, crocodile farms, and sustainability concerns"
"UNESCO designation, funding bodies, and conservation goals"
"Life in floating settlements and community displacement struggles"
"Overfishing, deforestation, dams, pollution, and legal failures"
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