Unsustainable development threatens the health and diverse fish populations of the Mekong river, with one-fifth of fish species in Southeast Asia’s main artery facing extinction, a report by conservation groups said.
The Mekong, stretching nearly 5,000 km (3,000 miles) from the Tibetan Plateau to the South China Sea, is a farming and fishing lifeline for tens of millions of people in China, Laos, Myanmar, Thailand, Cambodia and Vietnam.
Threats to its fish include habitat loss, conversion of wetlands for agriculture and aquaculture, unsustainable sand mining, introduction of invasive species, worsening climate change and hydropower dams fragmenting the flow of the river and its tributaries, according to the report compiled by the World Wildlife Fund and 25 global marine and wildlife conservation groups.
“The biggest threat right now, and a threat that’s still potentially gaining momentum, is hydropower development,” said fish biologist Zeb Hogan, who heads the Wonders of the Mekong, one of the groups behind the report.
Dams alter the flow of the world’s third-most biodiverse river, change water quality and block fish migration, he said.
Proliferating Chinese-built hydroelectric dams upriver have blocked much of the sediment that provides essential nutrients to tens of thousands of farms in the Mekong River Delta, Reuters reported in 2022.
To be fair, it sounds like more of a problem with sediment building up behind dams instead of being carried downstream in this case, which is a harder problem to solve. Not only because southeast asia tends to be a lot poorer and can’t use as fancy fish passage systems as the US, but because a lot of sediment makes its ways into river systems from minor and major floods, and something tells me let’s flood your town every few years to feed some fish isn’t going to be very popular with the locals who just got a dam system on the promise it was an end to the climate change boosted floods wiping out their farming towns.
Outside of the video you mentioned, which everyone reading this should watch when it makes it over to Youtube if they haven’t already, Asianometry has a good video on the resivor sedimenting problem from an engineering prospective, though admittedly his presentation tends to be a bit drier in presentation than Pratical Engineering.
Ah, I’d looked to see if it had the First icon before mentioning it but it looks like he never uses the tags. For others, we’re talking about How Fish Survive Hydro Turbines on Nebula (you can watch without an account).
Anyway, thanks for the other video, I’ll watch it soon. It makes sense that sediment is a trickier problem than fish since, unlike fish, sediment isn’t actively trying to get anywhere. When I first posted, I was imagining something like a conveyor belt, or perhaps pipes (either without turbines or ones pushing downstream) low down on the dam.