World's Largest Catfish Species Threatened by Dam

April 8, 2008
Stefan Lovgren at Khone Falls, Cambodia
for National Geographic News

This is the sixth story in a continuing series on the Megafishes Project. Join National Geographic News on the trail with project leader Zeb Hogan as he tracks down the world's largest freshwater fishes.

In the swift currents of the Mekong River in northern Cambodia, fishers expertly navigate their longboats past rock outcroppings and fallen logs.

But soon these wild waters may be tamed. Plans for the construction of a large hydroelectric dam just across the border, at Khone Falls in Laos, would permanently alter one of the most pristine areas in Southeast Asia.

The dam is one of several being planned on the mostly untouched Mekong River, which meanders through six countries—China, Myanmar (Burma), Thailand, Laos, Cambodia, and Vietnam (see map).

The future of the Mekong was a key issue when the prime ministers of those countries met for a regional summit earlier this week in the Laotian capital of Vientiane.

The Don Sahong dam at Khone Falls, one of five dams that Laos is planning along the Mekong, will block the deepest channel on the section of the river that migratory fish pass through when the water level is at its lowest, conservationists say.

One of those migratory fish is the critically endangered Mekong giant catfish, which holds the record as the largest freshwater fish ever caught. The record catch, made in northern Thailand in 2005, tipped the scales at 646 pounds (293 kilograms).

"An impassable dam at the falls could cause the extinction of the Mekong giant catfish species," said Zeb Hogan, a fisheries biologist at the University of Nevada in Reno.

Hogan, who visited the Khone Falls area last week, heads the Megafishes Project, a three-year effort to document the 20-plus species of freshwater fish that measure at least 6.5 feet (2 meters) in length or 220 pounds (100 kilograms) in weight.

(The Megafishes Project is partly funded by the National Geographic Society, which operates National Geographic News.)

Spawning Ground

Fishers at Khone Falls had long known that the giant catfish traveled through their area.

But in 2007 Thai photographer Suthep Kritsanavarin for the first time photographed a giant catfish caught at Khone Falls.

Giant catfish were once plentiful throughout the Mekong River basin, but in the last century the population has declined 95 to 99 percent, according to Hogan.

The massive fish is not targeted by fishers, but it is sometimes caught as bycatch. In Cambodia, where the largest population of giant catfish is found, eight of the giant fish were caught last year.

Although fishing is the biggest immediate threat to the giant catfish in the Mekong, dams and habitat fragmentation could disrupt the animal's ability to reproduce, Hogan said.

"There is only one known spawning ground for Mekong giant catfish, and that spawning ground is in northern Thailand," he said.

"Until we know better, we have to assume that fish from Cambodia may migrate to Thailand to spawn."

The construction of the Don Sahong dam, which is slated for completion in 2010, would make that migration impossible, Hogan said.

Untouched

Advocates of the dams point to the enormous hydropower potential that the Mekong offers to an energy-hungry region. With oil prices at record levels, the projects have taken on added urgency, they say.

So far the Mekong runs almost uninterrupted; only China has dammed the river at two locations in Yunnan Province.

One of the dams that China is now building will be second in size only to the Yangtze River's Three Gorges Dam.

"China, as an upstream country, will never do anything that will harm the interests of downstream countries," He Yafei, China's assistant foreign minister, told reporters before last week's regional summit.

But officials in Vietnam, where the Mekong empties into the South China Sea, say water extraction for farm irrigation upstream has already caused ocean salt water to move inland, destroying rice fields.

Conservationists likewise warn that the new dams could harm fish stocks that millions of people throughout the Mekong depend on.

"Fisheries resources are essential to the population of the Mekong Basin," said Eric Baran of the nonprofit World Fish Center in Phnom Penh, Cambodia.

"In Cambodia, for instance, the fish catch contributes 65 to 75 percent of the animal protein of households."

More than a thousand fish species live in the Mekong River system, a biodiversity second only to the Amazon in South America, Baran said.

In a report last year, the World Fish Center warned that the economic benefits of the U.S. $300-million Don Sahong dam may be outweighed by losses from local fisheries, whose production has been estimated at over U.S. $2 billion a year.

Deep Channel

At Khone Falls the Mekong River drops up to 100 feet (30 meters) from the Khorat plateau to the Mekong plain, forming a complex network of narrow channels, called hoo in Lao.

Scientists have found that the area supports at least 201 fish species, including several endemic or endangered species.

The area is also home to one of the few remaining concentrations of freshwater dolphins in the Mekong.

The dam will block Hoo Sahong, the deepest channel and the only one that migratory fish can pass through at the peak of the dry season, in April and May, when the Mekong is at its lowest.

Nongovernmental organizations in Cambodia called on their government this month to ask Laos for a construction moratorium on the Don Sahong dam to allow for more environmental assessments.

Hogan admits that dams provide a number of benefits, including flood control, water for irrigation, and electricity.

"But it is also important to consider the costs," he said, "especially in an area where a large part of the population is dependent on fish for food."

"From a migratory fish's perspective, there is nothing worse than a dam."

Planned Lao Dam Raises Concerns on the Mekong

By Andrew Nette
Newsmekong*

PHNOM PENH, Mar 28 (IPS) - The Lao government’s decision earlier this year to press ahead with plans to build the Don Sahong dam on the mainstream of the Mekong River in southern Laos is causing major concern in Cambodia and internationally.

The most advanced of eight hydropower projects mooted for the lower Mekong mainstream, the Don Sahong dam is also ramping up pressure on the Mekong River Commission (MRC), the inter-governmental body charged with managing development on the river.

The Cambodian government appears to be taking the issue seriously. The Foreign Ministry said on Thursday that Cambodian Prime Minister Hun Sen would pay a one-day visit to Laos to meet with regional officials on issues affecting the Mekong River.

Cambodian NGOs this week called upon their government to ask Laos for an immediate construction moratorium on Dong Sahong to allow for an independent trans-boundary assessment of environmental and social impacts.

In March 2006, the Lao government signed an agreement granting the Malaysian engineering firm Mega First Corp Berhad the exclusive mandate to carry out a feasibility study of the Don Sahong project.

On Feb. 13 this year, the company signed a project development agreement with Vientiane to push ahead with the scheme on a build-own-operate basis.

In a statement to the Malaysian stock exchange, the company said the dam, located in Champassak province two kilometres from the Lao border with Cambodia, would be a run-of-river facility with the capacity to generate between 240 and 360 megawatts of electricity to be sold mainly to Laos and neighbouring countries.

Their statement also said "the feasibility and social/ environmental studies of the proposed Don Sahong Project (show it) to be technically and financially viable." Critics are concerned that these studies have not been publicly released.

The dam will be built on the Mekong mainstream at a location known as Khone Falls, where the River forms a complex network of narrow channels, or ‘hoo’ in Lao, at the point at which it flows into Cambodia.

The dam will block Hoo Sahong, the deepest channel on that section of the river, and the movement of migratory fish that now easily pass through at the peak of the dry season, April to May, when the water level of the Mekong is at its lowest.

This will effectively block the dry season migration of fish between the feeding habitats of the Tonle Sap Lake and upstream breeding zones in Laos and Thailand, critics say. It is also likely to alter water flow patterns in the immediate downstream area, further disrupting migration patterns for fish species sensitive to changes in water levels.

According to a June 2007 briefing paper by the Phnom Penh-based WorldFish Centre, the Khone Falls supports at least 201 fish species, as well as one of the few remaining concentrations of freshwater dolphins in the Mekong.

"In the absence of detailed design information it is not possible to provide a full assessment of the impact of the proposed Don Sahong dam on the Mekong basin fisheries," the brief stated, although "this review of available information shows that the risks are very high."

While no economic valuation of the amount of fish that pass through the channel in the April to May period has been made, fisheries experts believe it is significant.

According to the WordFish Centre brief, 87 percent of the fish species in the Mekong whose behaviour is known, including some of the most commercially important species, are migratory.

Experts believe that the loss of even small percentage of Cambodia’s fisheries catch represents tens of thousands of tonnes and millions of dollars worth of fish.

In an open letter on Don Sahong dam in May 2007, over 30 fisheries scientists stated that Don Sahong "will have grave environmental impacts, particularly on fish and fisheries but also on tourism and other significant aspects of the economy and livelihoods, causing damage that will far exceed net returns from the project".

The Lao government has previously considered the channel of critical importance to migratory fish and specifically banned fishing there at various times between 1960 and 1990.

Informed sources say the project had been the subject of significant discussion in Lao government until the signing of the project development agreement in February put a halt to this.

Don Sahong was the subject of intense debate at a meeting of the Vientiane-based MRC in Siem Reap, Cambodia in November 2007. According to one media report, Cambodian delegates made their frustration clear with what they claimed was a lack of transparency on the part of Laos in relation to the dam.

In response to the February announcement, Lim Kean Hor, Minister for Water Resources and Meteorology and chair of the Cambodian National Mekong Committee (CNMC), said the MRC is studying the impact of the dam and would release a report at the end of 2008.

"The MRC have not ignored the potential problems with the fisheries on the Cambodian side," he said. "After the study is finished we will talk about the benefits and negatives because it is a multi-purpose project." CNMC officials were unavailable to be interviewed at this time about Don Sahong.

Nao Thuok, director general of Fisheries Administration at the Ministry of Agriculture, Forestry and Fisheries in Phnom Penh, confirmed that there have been discussions between the Cambodian and Lao governments about the potential impacts of the dam.

"We have suggested to Lao counterparts that they should study (Don Sahong) carefully before damming and they promised to do so. We just heard recently that they decided to build the dam soon, so it is not clear what the situation is."

It is understood that the MRC has prepared an analysis of the draft environment impact assessment for Don Sahong and economic valuation of the potential impact on fisheries from the project. These documents have not been publicly released.

The issue will also be discussed at the upcoming Joint Committee meeting of the MRC in Vietnam in early April.

In a letter sent this week to CNMC, Cambodian NGOs have requested that their government ask for a moratorium on the dam construction. "During the moratorium period, a comprehensive and participatory scientific transboundary environmental and social impact assessment must be carried out by an independent party," the letter said.

"As part of this scientific assessment, there should be public consultations and discussion between the countries of the lower Mekong region that examine and assess the future costs and benefits of this project to each country, and the poor and vulnerable communities living in affected areas," it added.

While China has completed two dams on the upper Mekong mainstream and construction on a further much larger project is underway, the lower reaches of the river have remained free from dam development until now.

Of the eight dam projects planned for the lower Mekong mainstream, five are in Laos including Don Sahong, two in Thailand and one in Cambodia.

A Chinese company has been undertaking a feasibility study of the Sambor dam in the central Cambodia, although there are mixed reports as to whether the government intends to move ahead on the project.

The English-language ‘Vientiane’ Times reported this week that Laos and Thailand have signed an agreement to allow a private firm to commence feasibility studies into the 1,800-megawatt Ban Kum Kun hydropower dam located on the Mekong mainstream on their border. "The need for a credible and effective river basin management organisation in the Mekong Region has never been more apparent, yet for the MRC a crisis of legitimacy and relevancy is looming," said a statement signed by 51 citizens’ groups and individuals from the six Mekong countries, sent on Mar. 27 to newly appointed MRC Chief Executive Officer Jeremy Bird.

The prospect of extensive hydropower development on the Mekong puts the MRC in a catch-22 situation, said Carl Middleton, a research analyst with Rivers International.

"If the MRC provides advice to government agencies that is perceived as critical of proposed hydropower projects, this advice could be unwelcome, ignored, and then no longer sought, undermining the MRC's relevance in the eyes of the government agencies it considers itself primarily answerable to."

"Yet, by not providing this objective analysis and releasing it into the public domain, as it should do, the MRC faces a crisis of legitimacy in the eyes of the wider public that it is also intended to serve," Middleton added.

(*This story was written for the Imaging Our Mekong Programme coordinated by IPS Asia-Pacific)