A recent study by the Environmental Justice Foundation says that, in the Cau Mau province of Vietnam, the world's fifth-largest producer of farmed shrimp, the Mekong Delta's mangrove cover is 30% of what it was in 1975. Shrimp aquaculture is easily the main cause. Elsewhere, though, aquaculture has probably contributed to the loss of less than 10% of the world's mangroves: the rest is due to causes such as rice production, grazing, urban development and tourism.