The river of plenty: uncovering the secrets of the amazing Mekong
Home to giant catfish and stingrays, feeding over 60 million people, and with the largest abundance of freshwater fish in the world, the Mekong River, and its numerous tributaries, brings food, culture, and life to much of Southeast Asia.
Despite this, little is known about the biodiversity and ecosystems of the Mekong, which is second only to the Amazon in terms of freshwater biodiversity. Meanwhile, the river is facing an existential crisis in the form of 77 proposed dams, while population growth, pollution, and development further imperil this understudied, but vast, ecosystem.
“More than 850 species have been described, and researchers estimate there could be over 1,200 species. As a comparison, the whole state of California has about 67 freshwater fishes,” Harmony Patricio, a conservation biologist and the conservation director at FISHBIO, told mongabay.com in a recent interview. “The Mekong is also the most productive freshwater system on the planet in terms of fish biomass. The estimated annual harvest is over 2.6 million metric tonnes per year, which represents about 18% of the total global inland fishery harvests. That’s almost 1/5 of all freshwater fish harvest across the world, found just in this one river basin.”
A new program by FISHBIO, headed by Patricio, is working to compile and disperse data on the freshwater fish across the region, including gathering information on harvesting. The Mekong Fish Network, as it’s called, hopes to draft baseline data, so that information can be compared over regions and time.
“The main goal of the Mekong Fish Network is to help people working with fish in the different countries of the Mekong Basin to collaborate across national borders and share information so we can better understand what’s happening with Mekong fishes throughout the basin,” she says. “These fish migrate between six different countries: China, Myanmar, Lao PDR, Thailand, Cambodia and Vietnam. These countries all speak different languages and have different cultures and government structures, but the fish don’t abide by national borders.”
The data is so important, according to Patricio, because the Mekong River Basin plays a vital role of the many communities that live along it.
“The river means everything to the people living in the basin, especially in rural areas. It’s their source of life. More than 60 million people depend on the fish for food, which typically accounts for more than half of their animal protein. There’s not really a substitute for that. People also use the river for transportation, for their household water supply, and for growing rice and farming.”
However, the river is imperiled by a wide-range of global and local environmental impacts including climate change, pollution, agriculture, logging, the aquarium trade, urban development, and a rapidly rising human population. One of the most immediate threats, however, is the proposed construction of 77 dams on the river, including the controversial Xayaburi Dam, which Patricio says could interrupt the migration of the giant catfish. Considered the world’s biggest freshwater fish, the giant catfish is listed as Critically Endangered and has largely vanished in recent decades. Despite it’s incredible size, scientists still know little about the animal.
“Overall, the cumulative effect [of dam construction] will probably be a reduction in the number of migratory species and a shift in the species composition to favor species that do well in reservoirs,” says Patricio. “Right now, we know more than a third (38%) of the total Mekong fish harvest consists of migratory species. If the biomass of the reservoir species doesn’t scale up to replace the migratory species, we could see a decline in total harvest or productivity.”
She adds, however, that there are ways to mitigate the damage of the dams, such as building massive bypass channels around the dam. In addition, officials could look at other power-generation technologies that wouldn’t involve damming the river.
“Some cool research is looking into building small turbines that are bolted to the riverbed, like free-standing barrels. Screens protect the fish from the turbines, and there is lots of space for fish to pass around,” she says. “People are also designing mesh grids with tiny turbines, maybe the size of a cube of ice. You put that on the substrate, and the little turbines combine to produce a fair amount of electricity, although they can’t generate the amount of electricity that the large dams can.”
Given the immense human and development pressures on the Mekong River Basin, it’s worth wondering how much of the river’s environments can be salvaged, and, if degradation occurs, how many people—dependent on the river for their livelihoods and even their cultural identities—will be harmed? Such questions, which are being asked across the developing world, point to a similar theme: development at what cost? Most countries have been snagged by the idea of development hook, line, and sinker, but their focus remains on big, industrial projects, rather than smarter, smaller, and more locally-driven development.
“It’s quite frustrating that there is a lot of money being poured into development in the Mekong, but it’s hard to get that same level of commitment for environmental research, monitoring, or conservation. In river basins like the Columbia, billions of dollars are spent every year to study, monitor and manage a few species, mostly salmon. Why is the Columbia more deserving of that research and attention than the Mekong?” Patricio asks, adding that it’s time the international community comes to see the Mekong as one of our most important ecosystems.
“The world needs to realize that the Mekong is like the Amazon rainforest. It’s a global resource of incredible diversity and productivity, and the rest of the world needs to support local governments like Laos so they aren’t so pressured to just develop without maintaining the balance of natural resources or aquatic diversity.”