· From the Mountains to the Sea
· Special Features
· Did You Know?
· Wild Side
· Cause for Concern
· Looking Ahead

Global 200 Snapshot

The Mekong River contains many endemic species. One-quarter of the approximately 240 species of fish in the river are found only in the Mekong and about 100 species of freshwater snails also live only here. The huge migrations of fish that move up the Mekong also make the ecoregion unusual.  

From the Mountains to the Sea

The Mekong starts among the glaciers of Tibet and ends by flowing into the South China Sea. It is the longest river in Southeast Asia and the tenth longest in the world. The mighty Mekong is an important source of water for people in six countries and forms the border between three. The Mekong is also the source of life for many unusual species of fish and other animals.

Special Features

The Mekong often flows with great force. It passes through mountain gorges and cascades down waterfalls up to 70 feet (21 m) high. The Mekong can be narrow enough for small boats to cross or be several miles wide. At its most southern point in Vietnam, the river creates a wide delta.

	During the flood season in Cambodia (June-October), the Mekong River swells from a depth of 5 feet (1.5 m) to nearly 45 feet (14 m). Water then fills the Great Lake (a natural reservoir), which becomes ten times larger than it is during the dry season.

Wild Side

Some of the Mekong’s 240 species of fish migrate long distances against currents to reach other parts of the river to spawn. The Laotian shad (freshwater herring) can be found up to 1,200 miles (2,000 km) upstream from the ocean, but unfortunately it is endangered, with the last known migration occurring in 1984. Other endemic large fish include the migratory catfish and the giant Mekong catfish, the giant barb, and the thicklip barb. Both the giant barb and the giant Mekong catfish grow to be up to 10 feet (3 m) long! The Mekong is also home to 100 endemic snail species. The Mekong also supports habitat for other animals, such as wetlands where the fishing cat lives. Some birds spend the winter along the river, including the Siberian crane, the sarus crane, and the swan goose. The Mekong basin provides habitat for the endangered Irrawaddy dolphin.

Cause for Concern

Even though the Mekong is huge and powerful, it is also vulnerable to population growth and human activity. The many cities and towns along its route cause pollution. Trees and other vegetation along the river have been cleared for agriculture, which causes soil erosion. Dams, which have been built to restrict flooding and to create electricity, block the movements of the ecoregion’s numerous migratory fish, and destroy riverine habitat. Over-fishing is also a serious threat.

Looking Ahead

There is competition over the Mekong's resources. Demand for electricity is increasing in Southeast Asia, so many people want more dams on the Mekong. But others want the water for agriculture. In 1995, four countries in the area signed an agreement to manage the river's resources in a sustainable way.