Mekong River

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.

Local Species
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 2,000km upstream from the ocean, but unfortunately it is endangered, with the last known migration occurring in 1984.

Among the numerous endemic fish species, one of the most imperiled and extraordinary is the Mekong giant catfish (Pangasianodon gigas), which can grow to over 300kg and may have historically migrated up to 2,000km. Other endemic fish that are under threat are Mae Khong herring (Tenualosa thibaudeaui), Thicklip barb (Probarbus labeamajor), and a cave fish (Barbus speleops).

This ecoregion is a major wintering area for the endangered Siberian crane (Grus leucogeranus) and Swan goose (Anser cygnoides), and is home to Sarus crane (Grus antigone). Also found here are 100 endemic snail species. The Mekong basin also provides habitat for the endangered Irrawaddy dolphin (Orcaella brevirostris).

Threats
The Mekong River system suffers from a wide range of serious threats such as:

• Deforestation that has changed runoff patterns and increased sedimentation.
• Modification of the hydrologic regime by flood control schemes, water diversions, and a vast array of hydropower projects.
• Impoundments that block the movements of the ecoregion's numerous migratory fish species.
• Over fishing, particularly with the increased use of poisons.
• Urban, industrial, and agricultural pollution that are largely untreated.

• NationalGeographic.com