It is not just in the Pearl River Delta that construction measures are causing broad-scale destruction of rivers and wetlands. Also under threat is the Mekong in South East Asia, a significant river system and a lifeline for millions of people. At 4350 kilometres in length, the Mekong is one of the world’s longest rivers. It flows through China, Myanmar, Laos, Thailand, Cambodia and Vietnam, and splits into a large delta before discharging into the South China Sea. The Mekong is extremely rich in biodiversity; it is home to around 1500 different species. What a high number this is can be seen from a comparison with the Mississippi, where only 250 species occur. Around 120 species in the Mekong are fished. Since the river carries large quantities of minerals and nutrients as it flows down from the Tibetan highlands, it is very productive and supplies large quantities of fish. Particularly in the lower-lying Mekong Basin in Laos, Thailand and Cambodia and in the Mekong Delta in Vietnam, there is a well-developed fishery supplying around 2.6 million tonnes of fish per year. Its market value is estimated at 2 to 3 billion US dollars.
Fish is not just a trading product, however, but first and foremost an important source of protein for the approximately 60 million people living in the Mekong Basin and Delta. Depending on the region, fish contributes between 49 and 82 per cent of the population’s intake of animal protein. But several dam projects are about to place the Mekong’s abundant fish stocks under threat. Laos, Thailand, Cambodia and Vietnam are all planning new dams for hydroelectric power generation. Laos has set itself particularly ambitious goals and intends to commission several dams in the next few years and establish itself as the “battery of South East Asia” – a major electricity exporter. Dam construction will disrupt many fish species’ migration routes between the sea and their spawning grounds up river. Some commercially important species will be affected. Thus, decisions made far inland have consequences that extend to the coastal areas.
The dam projects are colossal. The first to be commissioned, in Laos in 2019, will be the Xayaburi Dam: a structure 50 metres in height and 800 metres wide, it will impound the river into a lake of around 50 square kilometres – roughly the area of the Italian island of Ischia. Although there are plans to build fish ladders into the dam to facilitate fish migration, environmentalists warn that very few fish species can make use of these artificial passages upstream. Overall it is feared that the abundance of fish in the Mekong could decline substantially. If that happens, many people stand to lose a vitally important source of income or protein.

fig. 2.37 > Protest outside the administrative court in Bangkok against the construction of the Xayaburi Dam in Laos.