Photo: Hannah Wright via Unsplash.
The Mekong River, where it passes through Cambodia.
You would think that because I was around in the 1960s, mention of the Mekong River would bring to mind only Vietnam War scenes from television. I do think of those but also of Colin Cotterrill’s Dr. Siri Paiboun mystery series, where the river is a character all its own, and where Laotian characters may cross secretly to Cambodia, Thailand, or Vietnam.
So naturally, research on the river’s improving quality caught my eye.
Stefan Lovgren has a report at YaleEnvironment360. “Among the many ailments plaguing Southeast Asia’s Mekong River, ‘hungry water’ stands out with particular clarity. In recent dry seasons, the Mekong has in places turned a pristine blue as upstream dams rob it of the nutritious particles that normally color the river a healthy mud brown. It’s a phenomenon that can be highly destructive, with the sediment-starved water eating away at unbuffered river banks — hence the ‘hungry’ epithet — and causing harmful erosion.
“It also encapsulates the troubled state of the Mekong, a river that may look healthy on the surface but has grown increasingly sick from a wide range of problems, including dam building, overfishing, deforestation, plastic pollution, and the insidious impacts of a changing climate. During El Niño-induced droughts in recent years, things got so bad that some people suggested the Mekong River was approaching an ecological tipping point beyond which it could not recover.
But events in the past year suggest such doomsday predictions may be premature, especially in Cambodia, which sits at the heart of the Mekong basin.
“Thanks to the last monsoon season, which delivered above-average rainfall to the region, and authorities cracking down on illegal fishing, fish stocks have increased. Fishers along the Mekong have discovered giant fish thought to have disappeared, and the Cambodian government, which has a mixed environmental record, has stepped up conservation efforts.
“Among them is a new government-backed proposal that seeks to turn a particularly bio-rich stretch of the river in northern Cambodia into a UNESCO World Heritage Site. Such a designation, reserved for sites of great scientific or cultural significance, means this part of the river should, at least on paper, enjoy protection from various forms of development, including dam building. …
“ ‘The Mekong is not dead,’ says Sudeep Chandra, director of the Global Water Center at the University of Nevada, Reno, who leads the USAID-funded Wonders of the Mekong research project. ‘We’ve seen huge environmental pressures causing the Mekong to dry up and fisheries to almost collapse. And yet we also see the incredible resilience of this river in the face of those threats.’
“Originating in the Tibetan highlands and winding its way through six countries before disgorging into the South China Sea, the 2,700-mile-long Mekong River is home to the world’s largest inland fishery, with about 1,000 species of fish. Many of the 70 million people living in the basin rely on the river for their livelihoods, whether that is farming, fishing, or other occupations.
” ‘A case could be made that the Mekong is the world’s most important river,’ says Chandra.
“The river’s extraordinary productivity is linked to a giant flood pulse that, in the wet season, can raise water levels 40 feet. With the increase comes sediment that’s essential to agriculture as well as vast numbers of young fish, which are swept into Cambodia’s vital Tonle Sap Lake and other floodplains where they feed and grow.
“But the river’s natural flow regime has been increasingly disrupted by dams, especially those that China began building in the early 1990s in the Upper Mekong and which the country has operated with little regard for downstream impacts.
“A subsequent frenzy of dam building in Laos and elsewhere, mostly on tributaries to the Mekong, has greatly exacerbated the problem, with dams blocking fish from completing their natural migrations. Already under extreme pressure from overfishing, some fish populations have plummeted, especially large species like the critically endangered Mekong giant catfish, which can grow to 10 feet in length and more than 600 pounds, but is now on the brink of extinction.
“With climate change intensifying, monsoon rains have become more unpredictable. During droughts in 2019 and 2020, the flow of water from the Mekong into Tonle Sap, the largest lake in Southeast Asia, dried up. …
“Mass deaths of fish due to shallow and oxygen-poor water were reported in the lake, and many of the hundreds of thousands of fishers operating on the lake were forced to abandon their work. On the Tonle Sap River, which connects the Mekong and the lake, two thirds of the 60-something commercial ‘dai’ operators working stationary nets, which in years past could each catch several tons of fish in just an hour, had to shut down. …
“However, the river system caught a break with the most recent monsoon season, which runs roughly from June to November, delivering greater than average rainfall to the lower basin and the Tonle Sap Lake region. Although China continued to hold back water to counter its persisting drought, water levels in Tonle Sap rose more than one meter above recent-year averages. With the lake expanding into seasonally flooded forests, which provide excellent feeding grounds for fish, fish populations appear to have been boosted. …
“On a recent visit to the lake, Ngor noticed an increase in medium- and large-size carps, including Jullien’s golden carp, also known as the isok barb, a critically endangered species. There were spottings of other rare fish too, like the Laotian shad and clown featherback, along with increases of more common fish, like the climbing perch and snakehead. Several wallagos, a catfish that can grow up to 8 feet long, could be seen jumping from the open water.
More at YaleEnvironment360, here. No firewall.
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