Dams pose threat to giant catfish [Bangkok Post 28/07/2010]

Dams pose threat to giant catfish

http://www.bangkokpost.com/news/local/188177/dams-pose-threat-to-giant-catfish

Giant catfish in the Mekong River will be driven to extinction if plans for hydroelectric dams go ahead, a report by the World Wildlife Fund says.

The report, "River of Giants: Giant Fish of the Mekong", profiles four giant fish living in the Mekong that rank among the world's 10 largest freshwater fish.

At half the length of a bus and weighing up to 600kg, the Mekong River's giant freshwater stingray is the largest freshwater fish in the world. The critically endangered and culturally fabled Mekong giant catfish ranks third at up to three metres in length and weighing 350kg.

"A fish the size of a Mekong giant catfish simply will not be able to swim across a large barrier like a dam to reach its spawning grounds upstream," said Roger Mollot, freshwater biologist for WWF Laos. "This would lead to the collapse of the wild population of this iconic species."

Scientists say the Mekong giant catfish migrate from the Tonle Sap Lake in Cambodia up the Mekong River to spawn in northern Thailand and Laos. It is believed dams built on the lower Mekong will block the migration route.

Those objecting to the projects say the hydropower dam planned for the Mekong in Sayaboury province, northern Laos, is a threat to the survival of the wild population of Mekong giant catfish.

The Sayaboury dam is the first dam on the lower Mekong mainstream to enter a critical stage of assessment before member countries of the Mekong River Commission advise on whether to approve its construction.

"More giant fish live in the Mekong than any other river on Earth," said Dang Thuy Trang, Mekong River eco-region coordinator for the WWF Greater Mekong Programme.

"Currently, the lower Mekong remains free-flowing, which presents a rare opportunity for the conservation of these species. But the clock is ticking."

Other Mekong giant fish featured in the report are the dog-eating catfish, named because it has been caught using dog meat as bait, and the giant barb, the national fish of Cambodia. At 300kg, these tie for fifth place on the global top 10 for freshwater fish.

The impact of lower Mekong River mainstream dams is not restricted to these Mekong giants. They would also exacerbate the impact of climate change on the Mekong River Delta, one of the world's most productive regions for fisheries and agriculture.

Building the Sayaboury dam would reduce sediment flowing downstream to the Mekong River Delta, increasing the vulnerability of this area to the impact of climate change such as sea level rise.

The WWF supports a delay in the approval of the mainstream dams, including the Sayaboury dam, to ensure a comprehensive understanding of all the positive and negative impacts of their construction and operation.

Download the report here: http://assets.panda.org/downloads/new_river_of_giants_report_14_may_2010_web_version.pdf