UNESCO: United Nations Educational Scientific and Cultural Organization

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Special Issue

The Mekong: an Exception to the Rule
The Tonle Sap in Cambodia is an enormous fishing reserve
© John Vink/Magnum, Paris
Unlike most great rivers, which have lost their natural fecundity, the Mekong has succeeded in preserving its resources
Once the world’s rivers teemed with fish. Then during the 20th century, most of them were barricaded by dams that tamed their wild waters. Almost everywhere this has caused a drastic decline in wild fisheries. One of the few places this has not happened is the Mekong River, the great artery of Southeast Asia, where half a century of warfare kept the dam-builders away.

Maintaining natural fecundity

Here, without barriers, the fish have prospered, especially in a vast forested basin off the main river that still floods in the monsoon season, called the Tonle Sap, or Great Lake. The lake is a UNESCO Biosphere Reserve. Its complex hydrology, in which the flow of the river that connects it to the main river reverses its direction twice a year, maintains it as the nursery of the world’s largest inland fishery, and the source of livelihood for more than a million local people, according to a joint study by UNESCO scientists and Columbia University in New York.

The lake has a long history of sustaining large populations. On its shores sits the World Heritage site of Angkor Wat, one of the great jungle civilisations 1,000 years ago, which fed itself on fish from the lake and rice from the paddies that it watered.

Today the Mekong is threatened by increasing demands on the river’s resources, from hydroelectric power companies, cities who want water supplies, and navigators who want to dredge its rapids. UNESCO scientists are working with the Cambodian government and the intergovernmental UNESCO-backed Mekong River Commission on proposals to integrate uses of the river to maintain its extraordinary fecundity.

This forms part of a wider UNESCO initiative that encourages research on how best to maintain and revive the natural fecundity of river systems, often by concentrating on the wetland fish nurseries within their catchments. Other examples include the Sudd wetland on the Nile, the Iquitos floodplain in Peru and the wetlands of the Yellow River. But the Mekong, as the least domesticated, is a good place to start. “The Mekong is not just another river,” says Chris Barlow of the Mekong River Commission. “It is the least modified of all the major rivers of the world. The fisheries are a source of natural wealth for the poor. If they were destroyed, people’s only alternative would be a job in a factory making textiles for the West.”

See also:
  • Tonle Sap
        Biosphere Reserve information
  • Author(s): 
    Fred Pearce
    Europe and North America Latin America and the Caribbean Africa Arab States Asia Pacific