Before being officially declared extinct by scientists late last month, the Chinese paddlefish, a native to the Yangtze River system, had been listed along with the Mekong giant catfish as "critically endangered" by the International Union for Conservation of Nature.
The extinction of the paddlefish, one of the world's largest freshwater species, will perhaps serve as a wake-up call to the builders of dams in the Mekong and regional policymakers about the seriousness of the adverse impacts existing and planned hydropower projects can have.
Last seen by researchers in 2003, the Chinese swordfish species, can grow up to 7 metres long and weigh close to 450 kilograms. They have long, silver-grey bodies, very large mouths, and a long, wide snout that resembles a paddle.
It was commonly found in the Yangtze River until the late 1970s, when over-fishing and other development pressures began reducing its population. In the 1980s, the construction of a dam on the Yangtze as part of the Gezhouba hydroelectric project worsened things at it created an impassable barrier for the fish to migrate to its spawning grounds upstream.
Since then, the building of the enormous Three Gorges Dam on the Yangtze River, along with over-fishing, river transport and pollution have further affected the species.
Much like the Chinese paddlefish, some 160 species in the Lower Mekong Basin rely on long-distance migration for spawning and are facing the threats of over-fishing and development. For instance, the giant catfish, which can be up to 3 metres long and weigh 300 kilograms, has not been found in the wild since 2015. That is one step towards extinction, and the development of hydropower in the Mekong is accelerating this process.
In addition to the eight dams on the upper Mekong in China, Xayaburi and Don Sahong dams in Laos -- two of the 11 projects planned for the lower part of the river -- began operating last year.
Since 2016, the Lao government has moved ahead with its plan to build two more projects Pak Beng and Pak Lay, and just last month, it announced a fifth project -- the Luang Prabang Dam.
Among the potentially adverse environmental impacts associated with these projects, as indicated by science-based studies, is the substantial drop in fish populations, as these dams will block their passage. Even though developers have included fish passages in the dams, these are untested measures. No one knows whether these passages work as intended. A study by the Mekong River Commission published last year indicated that the fish ladder designed for the Xayaburi Dam is ineffective.
Yet, Chansaveng Buongnong, chief of Laos' Department of Energy Policy and Planning, recently assured the media that the latest Luang Prabang project will not affect the river's ecosystem as feared because the specially constructed passages will facilitate fish migration.
However, untested, questionable "mitigation measures" like fish ladders are not reliable. The only reliable option is to slow down on building hydropower projects.
With the state-run Electricity Generating Authority of Thailand (Egat) as a major buyer from these projects, the government should reconsider this scheme and push for Egat to promote the generation and use of renewable energy.
They should also not play down the seriousness of the impact these dams are having on the Mekong giant catfish and other fish species that people rely upon as affordable sources of protein.