[enviro-vlc] WWF report says Mekong dams threaten rare giant fish

[vern weitzel]

From: Kevin Yuk-shing Li <kevinysli at gmail.com>
Date: 28 July 2010 6:26:26 PM PDT
To: China-Mekong <lancang-mekong at googlegroups.com>
Subject: [China-Mekong] WWF report says Mekong dams threaten rare giant fish
Reply-To: kevinysli at gmail.com

WWF report says Mekong dams threaten rare giant fish
http://wwf.panda.org/wwf_news/?194313/Mekong-dams-threaten-rare-giant-fish

Wild populations of the iconic Mekong giant catfish will be driven to
extinction if hydropower dams planned for the Mekong River go ahead,
says a new report by WWF.

The report, River of Giants: Giant Fish of the Mekong, profiles four
giant fish living in the Mekong that rank within the top 10 largest
freshwater fish on the planet (see list of top 10 at bottom of page).

At half the length of a bus and weighing up to 600kgs, the Mekong
River’s giant freshwater stingray (Dasyatis laosensis) is the world’s
largest freshwater fish. The critically endangered and culturally
fabled Mekong giant catfish (Pangasianodon gigas) ranks third at up to
3 metres in length and 350kgs.

Dam will present unsurmountable barrier for giant fish

“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.”

Current scientific information suggests the Mekong giant catfish
migrate from the  Tonle Sap Lake in Cambodia up the Mekong River to
spawn in northern Thailand and Laos. Any dam built on the lower Mekong
River mainstream will block this migration route.

The hydropower dam planned on the  Mekong River at Sayabouly Province,
northern Laos, is a threat to the survival of the wild population of
Mekong giant catfish. The Sayabouly Dam is the first lower Mekong
River mainstream dam to enter a critical stage of assessment before
member countries of the Mekong River Commission advise on whether to
approve its construction.

Mekong River home to more giant freshwater fish than any other

“More giant fish live in the Mekong than any other river on Earth,”
said Ms Dang Thuy Trang, Mekong River Ecoregion 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.”

The other Mekong giant fish featured in the report are the "dog-
eating" catfish (Pangasius sanitwongsei), named because it has been
caught using dog meat as bait, and the giant barb (Catlocarpio
siamensis), the national fish of Cambodia and largest carp in the
world. At 300kgs each, these fish tie for fifth place on the global
top ten.

Dams will amplify the impact of climate change on fisheries and
agriculture

However, the impacts of lower Mekong River mainstream dams are not
restricted to these Mekong giants, they would also exacerbate the
impacts of climate change on the Mekong River Delta, one of the
world’s most productive regions for fisheries and agriculture.

Building the Sayabouly Dam would reduce sediment flowing downstream to
the Mekong River Delta, increasing the vulnerability of this area to
the impacts of climate change like sea level rise.

There are alternatives

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

To meet immediate energy demands, WWF promotes sustainable hydropower
projects on tributaries of the Mekong River, prioritising those that
already have hydropower dams developed on them.

The Global Top 10 Giant Freshwater Fish

  1. Giant freshwater stingray (Himantura chaophraya) 600kg (500cm,
240cm disc width) Mekong River Basin
  2. Chinese paddlefish (Psephurus gladius) 500kg (700cm) Yangtze
River Basin
  3. Mekong giant catfish (Pangasianodon gigas) 350kg (300cm) Mekong
River Basin
  4. Wels catfish (Silurus glanis) 306kg (500cm) Widespread in Europe
and Asia
  5. Giant pangasius (dog-eating catfish) (Pangasius sanitwongsei)
300kg (300cm) Mekong River Basin
  6. Giant barb (Catlocarpio siamensis) 300kg (300cm) Mekong River
Basin
  7. Arapaima (pirarucu; paiche) (Arapaima gigas) 200kg (450cm)
Amazon River Basin
  8. Piraíba (laulau; lechero) (Brachyplatystoma filamentosum) 200kg
(360cm) Amazon River Basin
  9. Nile perch (Lates niloticus) 200kg (200cm) Nile River Basin
 10. Alligator gar (Atractosteus spatula) 137kg (305cm) Mississippi
River Basin

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