A newly published research paper offers a Pacific Northwest lessons learned perspective on how migratory fish might be protected in southeast Asia’s Mekong River basin in the face of planned hydropower expansion that is needed to boost the economy.
The paper, “Potential Effects of Dams on Migratory Fish in the Mekong River: Lessons from Salmon in the Fraser and Columbia Rivers,” was published in the January issue of Environmental Management. The paper can be found at
Lead author of the paper is John Ferguson, head of the Fish Ecology Division at NOAA Fisheries’ Northwest Fisheries Science Center in Seattle. Co-authors include Michael Healey of the University of British Columbia, Vancouver, Patrick Dugan WorldFish Centre, Penang, Malaysia, and Chris Barlow, Australian Centre for International Agricultural Research, Canberra, Australia.
“Minimizing impacts will require decades to design specialized fish passage facilities, dam operations, and artificial production, and is complicated by the Mekong’s high diversity and productivity,” the paper says.
“Prompt action is needed by governments and fisheries managers to plan Mekong water resource development wisely to prevent impacts to the world’s most productive inland fisheries, and food security and employment opportunities for millions of people in the region.”
“Because the knowledge needed to design, install, and operate fish mitigation facilities at dams in the Mekong region does not exist, additional monitoring and research on the biological requirements of key migratory species is needed.”
The paper looks at the effects on salmon, as witnessed over the past several decades, related to hydro development in the Northwest and relates them to issues likely to emerge in the Mekong basin. The Fraser River has few dams and all are located in tributaries, whereas the Columbia River has more than 130 large mainstem and tributary dams.
“Not surprisingly, we found substantial effects of development on salmon in the Columbia River,” the paper says.
The paper had its genesis in a gathering of 17 experts convened in September 2008 by the Mekong Delta Commission to discuss potential impacts on fish populations, and possible mitigation, related to hydropower expansion in the southeast Asian river basin. The MRC was established in 1995 by an agreement between the governments of Cambodia, Lao Peoples Democratic Republic, Thailand and Viet Nam.
The expert panel convened by the MRC represented extensive expertise in fish biology and ecology, and in efforts to design and operate hydro dams so as to reduce their impacts on fisheries. The panelists have worked on these issues in a wide range of countries and river systems in Asia, Africa, Australia, Latin America, North America and Europe,
Members from the United States included Ferguson, John Nestler and Robert Davidson of the U.S. Army Corps of Engineers and Glenn Cada of Oak Ridge National Laboratory. Dugan was also a member of the panel.
The 1995 Agreement on the Cooperation for the Sustainable Development of the Mekong River Basin came about as the four countries saw a common interest in jointly managing their shared water resources and developing the economic potential of the river.
The Mekong River is the world’s 10th longest river, extending 4,909 kilometers, or 3,050 miles, from the Tibetan Plateau in China down through Lao PRD, Cambodia and Thailand to its mouth in southern Vietnam.
“The Mekong River lies in a region in desperate need of electricity for economic development and nearly 200 dams are completed, under construction, or planned in tributaries,” the paper says.
On the other hand, “Its physical diversity, tropical location, and high productivity fostered the evolution of a diverse fish community comprised of about 850 freshwater species (Valbo-Jorgensen and others 2009), and as many as 1,100 indigenous species if coastal and marine species that use the Mekong River ecosystem are considered (Hortle 2009a),” the paper says. “Species richness in the Mekong is second only to that in the Amazon River (Froese and Pauly 2010) and supports the world’s largest inland fishery with approximately 2.6 million tonnes annual harvest.”
That fish list includes a total of 135 species that evolved with potadromous life history strategies, including the Mekong giant catfish, which grows to more than 3 meters in length and 300 kilograms in weight. Potadromous fish require movement through fresh water systems to complete their lifecycle.
The combined fishery from natural harvest and aquaculture has an estimated value of from $3.6 billion to $6.5 billion at the point of first sale, according to research cited in the paper.
“These values do not consider the food security and employment benefits the fisheries provide for millions of people with limited livelihood alternatives, nor do they recognize that Mekong fish are the main source of animal protein, vitamins, and calcium for 60 million people” in the lower Mekong River basin.
The “stark contrast” between the Fraser and Columbia in terms of hydro development gave the researchers the “opportunity to explore key issues facing Mekong River planners and resource managers, including the overall impact of dams and the relative impact of mainstem versus tributary dams on fish abundance,” the paper says. The Columbia has 13 mainstem dams that fish must pass to complete their life cycle.
“When we compared patterns in abundance between the Fraser and Columbia rivers, we found no substantial differences, and thus no obvious effects of water resource development on salmon in the Columbia River,” the paper said.
“In contrast, we found substantial differences in the extent to which salmon production in the two rivers relies on artificial production to support fisheries and mitigate for dam passage and other sources of mortality. In the Fraser River, the Canadian federal government’s Salmonid Enhancement Program is comprised of only 12 hatcheries.”
“…salmon abundance and fisheries in the Columbia basin are dependent upon 178 hatchery programs, many of which were implemented explicitly to mitigate impacts from private and federal dams installed in the basin,” the paper says.
The paper says it could take decades, if it is even technically feasible, to develop successful artificial production techniques for the numerous Mekong species as a means of maintaining overall abundance.
Among the lessons learned are:
-- Overall impacts from hydropower development are large;
-- Multiple, adaptive approaches are needed to manage migratory fish resources impacted by mainstem dams;
-- The ability of salmon to negotiate upstream fish passage facilities is comparatively greater than that of tropical species.
-- Greater impacts on migratory fish would result from mainstem versus tributary development.
“The decision to not dam the mainstem Fraser River likely allowed natural production to largely sustain the viability and productivity of most salmon populations. Thus, our broad-scale review led us to conclude that in general, impacts are greater from mainstem dams compared to tributary dams,” the paper says.
“However, there are many qualifiers and caveats to such a broad conclusion.
“A strategic environmental assessment taking into account all economic, environmental, and social considerations to indicate the point along the mainstem where dams should be built is being conducted by the Mekong River Commission (http://www.mrcmekong.org). Such an assessment should also consider the need for some tributaries to remain undammed to retain connectivity among key river components, allow successful spawning and recruitment of keystone migratory species, and conserve fish diversity.”