Extinction of Species: Mekong: Barricaded River | nd-aktuell.de

The Mekong is a river of dreams, legends and adventures. From its source in China, the powerful river crosses Myanmar, Laos, Cambodia and Thailand before flowing more than 4,350 kilometers in Vietnam into the South China Sea. Along the way, the river has many names such as Mae Nam Khong (Mother of All Water) or Nine Dragon River.

In the lower reaches of the river alone, which begins at the meeting point of Myanmar, Laos and Thailand known as the “Golden Triangle”, the lives of more than 65 million people, the flora and fauna as well as the prosperity of agriculture depend on the water, nutrients and sediments of the river gigantic ecosystem.

“With 1,148 known fish species, the Mekong is the third most biodiverse river after the Amazon and the Congo,” says the new report “The Forgotten Fish of the Mekong” from the World Wildlife Fund (WWF). Giants threatened with extinction can be found here, such as the giant catfish, which can be up to three meters long, and the giant freshwater ray, which is considered the largest freshwater fish in the world.

Fish are the most important source of protein for people living on the banks of the Mekong. The Mekong basin accounts for 15 percent of the world’s annual inland fish catch. In 2015, that was 2.3 billion tons of fish, worth more than $11 billion.

However, fish only swim in abundance in the Mekong if they can reproduce. Like hardly anywhere else in the world, most species in the Mekong are migratory fish. But hydroelectric dams block both the fish’s path to their spawning grounds and that of young fish from the Mekong and its tributaries downstream. The artificial barriers also block the natural flow of water and sediment. This is particularly fatal for Lake Tonle Sap, which normally floods half of Cambodia when the water level rises every year and washes fertile sediments over the land into the lake as a breeding ground for agriculture and young fish.

There are already nine dams blocking the way of fish on the upper reaches of the Mekong in China. In Laos there are already two dams, the Xayaburi and Do Sahong, and seven more are being planned. Only Cambodia’s new Prime Minister Hun Manet has reiterated the assurance of his predecessor and father Hun Sen not to build any dams in the Cambodian part of the Mekong.

With the now published report, the WWF, the International Union for Conservation of Nature (IUCN) and 23 other water, fish and nature conservation organizations are sounding the alarm: At least 75 fish species are listed as threatened with extinction on the IUCN Red List, 18 of them classified as particularly at risk. “Officially, this means that around 19 percent of the known Mekong fish species are threatened,” says the report published in March. An “unprecedented combination of threats” such as habitat loss, conversion of wetlands for agriculture and aquaculture, unsustainable sand mining, invasive species and climate change are other factors driving the decline in fish stocks. The economic value of the Mekong fishery is estimated to have fallen by a third between 2015 and 2020. Thai Mekong fisherman Prayoon Sean-ae told Asian media: »Before the Xayaburi Dam was commissioned in 2019, a fisherman could catch ten kilos of fish per day. But now we’re lucky if we catch four to five kilos a week.”

For decades, scientists, as well as environmental organizations and fishermen, have been warning in countless studies of the dams’ catastrophe for the ecology of the river system and the food security of the residents. The builders of the dams, for their part, unanimously assure that by building fish ladders, the fish will continue to be able to migrate, which is crucial for their life and reproduction cycle.

However, scientists give these artificial passages damning evidence. These were designed for salmonid fish in northern latitudes, which can navigate better through such systems. In addition, dams turned the river behind the dams into stagnant water. “For fish that have evolved to survive in a fluid environment, this is a significant change to which many simply cannot adapt,” criticize the authors of the WWF report.

Eric Baran, a Mekong fish specialist, gave a talk entitled “The False Hopes of Fish Passage at Mekong High Dams” at a water management forum in July 2023. After 25 years of research on tropical rivers in Asia, Baran concluded: “There is still not a single case of successful fish passage and sustainable (fish) populations through the use of fish ladders.”

Baran is one of the scientists regularly engaged as consultants by the Mekong River Commission (MRC). The MRC includes Cambodia, Laos, Thailand and Vietnam, but not China. The Chinese are also extremely reluctant to share data from their part of the Mekong, which makes the scientific work of the MRC and other independent institutions massively difficult.

The MRC has been conducting a lot of scientific studies for years, publishing warnings of an ecological catastrophe caused by the dams and cheap recommendations on how to avoid one. But the commission does not have the mandate to force member states to implement the recommendations and is considered a toothless tiger among conservationists and scientists.

Despite everything, the Mekong and the Greater Mekong Region remain a veritable treasure trove of species. Among the 224 new discoveries published by WFF in 2022 were 35 reptiles, 17 amphibians, one mammal, 155 plants and 16 fish species. This means that the number of animal and plant species discovered in the region since 1997 has grown to an astonishing 3,007.