Photos: Dams Threaten Mekong River Megafishes

Mekong Giant Catfish

Photograph by Suthep Kritsanavarin, WWF/NGS via AP

Two Thai fishermen hold a giant Mekong catfish caught in northern Thailand in 2005. The mammoth fish weighed 646 pounds (293 kilograms).

Biologists have warned that the Xayaburi Dam proposed for the main stem of the Mekong River in Laos will block the migratory routes of dozens of fish species and could place 41 fish species at risk of extinction, including the critically endangered Mekong giant catfish.

(See video of the Mekong giant catfish, and learn more about the species on National Geographic Channel’s Hooked: Monster Fish of the Mekong episode.)

Published March 30, 2011

Damming the Mekong

Photograph by Eugene Hoshiko, AP

The Dachaoshan dam in Yunnan province, China is one of many dams on the approximately 3,000-mile (4,800-kilometer) Mekong River.

The river is traditionally separated into two parts on maps: The upper Mekong flows through China, where it is known as the Lancang River, while the lower Mekong runs alongside Myanmar and through Laos, Thailand, Cambodia, and Vietnam before emptying into the South China Sea.

The newly proposed Xayaburi Dam in northern Laos is the first of 11 proposed dams planned for construction on the lower Mekong River. Nine dams are planned for Laos, and two others are slated for Cambodia.

The Xayaburi Dam will take eight years to complete and cost an estimated $3.5 billion. It will generate 1,260 megawatts of electricity, most of which will be sold to Thailand.

Published March 30, 2011

Mekong Giant Catfish Release

Photograph by Chor Sokunthea, DCS/DY/Reuters

Cambodia Fisheries personnel release a Mekong giant catfish in 2005. The 5-foot (1.5-meter) megafish weighed nearly 100 pounds (50 kilograms).

In terms of biodiversity, the Mekong River is second only to the Amazon among the world's great rivers. As a home to more than 1,000 fish species, the Mekong supports the world's largest freshwater fishery, and it provides food and income—through fishing, farming, ecotourism, and other jobs—for many of the 65 million people who live in the Lower Mekong basin.

The Mekong is unique among the world’s large rivers because "the fish diversity is extremely high, the diversity of migratory species is extremely high, and human dependence upon these species for fisheries is extremely high," said Peter McIntyre, a freshwater conservation expert at the University of Wisconsin-Madison.

"You put all of that together, and putting a large dam in the Mekong is likely to cause major problems."

(Related news: “New Mekong Species Photos: Fangless Snake, Bald Bird.”)

Published March 30, 2011

Giant Carp

Photograph by Andy Eames, AP

Cambodian fishermen pose with a giant carp caught on the Tonle Sap River in 2003.

The builders of the Xayaburi Dam have promised to create "fish passages" that would allow fish to continue their migrations.

But International River's Ame Trandem said no fishery technology currently exists that can guarantee safe passage for the Mekong's numerous fish species.

"Right now, all the evidence points to the fact that fish passages will not work on the Mekong River because you're dealing with such a high volume of fish and such a large number of fish species," Trandem said.

(Read more from National Geographic Emerging Explorer and Fish Biologist Zeb Hogan: “Why We Shouldn’t Dam the World’s Most Productive River.”)

Published March 30, 2011

Mekong Giant Catfish

Photograph by Sukree Sukplang, Reuters

A Thai fishery department official catches a 66-pound (33 kilogram) Mekong giant catfish in 2006. The fish’s eggs were harvested as part of a captive breeding program and effort to restore giant catfish populations in the Mekong River system.

(See video of the giant catfish.)

Published March 30, 2011