Threat of Over-fishing in the Mekong
In Cambodia’s 'great lake', the Tonle Sap, where most large-scale inland fishing takes place, fishers report the rampant use of illegal fishing methods and declining fish catches.
Several Mekong fish species are now endangered and both the number and size of fish caught has steadily declined. In fact, recent data demonstrates a pattern of increasing catch and increasing fishing effort followed by a declining catch with a sustained effort, typical of an over-exploited population.
For instance, a century ago, the Mekong Giant Catfish was found along the entire length of the river from Vietnam to southern China. Since then, however, populations have dropped precipitously. Scientists estimate that the total number of Mekong Giant Catfish has decreased about 90% in just the past two decades.
WWF recently helped broker a voluntary ban on this species with Thai fishers. In Laos as early as 1890, a large fishery developed for the Mekong Giant Catfish but by 1940, declines were observed in northeast Thailand.
In the Mekong, uncertain fishing rights, over-fishing and illegal fishing have taken a heavy toll on fish stocks. People illegally use small-meshed mosquito nets to capture fish (which catch juveniles as well as adult fish), electro-shock fish with car batteries, and increasingly over-harvest fish with poison. Inherited from colonial times, the Cambodian government has managed its fisheries according to a concession system that enables unfair access, corruption and occasionally violent disputes.
The productivity of the Mekong River underscores the importance of this region in providing millions with food, but creates the misleading impression that its resources are limitless. It is clear, however, that unsustainable fishing practices and levels of harvest, along with changes in water flows induced by new dams, threaten the permanence of this wealth.