Giant Fish of Mekong River Endangered

Giant Fish May Go Extinct
Tara Mathur 0725528

The Mekong River which passes through Cambodia, China, Lao PDR, Myanmar, Thailand and Vietnam is home to at least 1100 species of fish (Thompson 2010). Due to the deep water pools, which provide natural protection and richness of food to fish species during the dry season, four out of the top ten giant freshwater fish species also call this 4800 km river home (Thompson 2010). Scientifically speaking, a species must be capable of growing to at least two metres in length or 100 kg in weight to qualify as a giant fish (Thompson 2010). The giant fish species that can be found in the Mekong River can grow up to 5 metres in length and weigh almost half a ton (Thompson 2010). Some of these giant freshwater fish, including the giant freshwater stingray, the Mekong giant catfish, the giant pangasius (dog-eating catfish) and the giant barb, are in danger due to hydropower dams that are to be built in the Lower Mekong River and large tributaries.
There are future plans for eleven hydropower dams to be built on the mainstream of the Lower Mekong River (Thompson 2010). These dams pose a threat to giant freshwater fish species. Many of the species are migratory and the dams creates a physical block which prevents them from migrating. If the fish can not migrate then they are unable to spawn wildly and therefore will not reproduce. This could lead to an extinction of a particular species as eventually they will all die off.
The first dam to be built is the Sayabouly hydropower dam which will be located in the Sayabouly Province of northern Lao PDR. If the Sayabouly dam is built, it is feared that the giant catfish will go extinct as it will not be able to survive as a species if it cannot pass through the dam. One of the most critical parts of the Mekong River is between Chang Rai, Thailand and Bokeo, Laos. It is a crucial section as it is believed by fisherman and scientists that it is one of the only areas that the giant catfish spawn wildly (Thompson 2010). The giant catfish are long distance migrators and any dam that is built on the mainstream of the lower Mekong River will prevent them from spawning (Thompson 2010). This will effectively not let them reproduce thus killing of the species as we know it.
The World Wildlife Fund does not believe that the impact of the of these dams have been fully assessed as they state in their 2010 study, River of Giants: Giant Fish of the Mekong, that “While the impacts of dams have been well studied in other areas of the world, data gaps in the Greater Mekong region prevent a proper assessment of the impacts of the 11 hydropower dams planned.” They suggest building sustainable hydropower projects on the tributaries towards the Mekong River as it is beneficial for their construction. Also if one tributary gets blocked up by a dam, there will be another tributary that will be left free-flowing, which will connect the upper and lower reaches of the basin. But there is only one mainstream and if you block it up the ecosystem connectivity could be potentially lost.
“Currently the Lower Mekong remains free-flowing, which presents a rare opportunity for the conservation of these species. But the clock is ticking.” says Christian Thompson, author of the 2010 WWF study, River of Giants: Giant Fish of the Mekong.


References:

Hogan, Zeb. "Bear-Size Catfish, Half-Ton Stingrays Among World's ''Monster'' Fishes." National Geographic News. National Geographic, n.d. Web. 14 Oct 2010. .

Thompson, C. (2010). River of giants: giant fish of the mekong. Retrieved from http://assets.panda.org/downloads/new_river_of_giants_report_14_may_2010_web_version.pdf