Fish passage solutions |
Right: Kleinschmidt Associates is to conduct an extensive study on the movement and upstream passage of the Shortnose Sturgeon at the Holyoke Dam in Massachusetts, US
potamodromous fish species that rely on it for their life cycles. “The Holyoke dam is the first mainstem dam on New
England’s largest river, supporting a host of migratory fish runs,” he said. “HG&E has been at the heart of the effort to improve habitat connectivity through safe and timely fish passage and protection at their hydroelectric facility.” Kleinschmidt has assisted with the project since 2017 and is now helping to bring this intricate multi-year effort to fruition. The study is expected to conclude in 2024.
Concern over Mekong Fish New research claims to have revealed “an alarming
Below: New research claims to have revealed “an alarming decline” in the number of fish species in the Mekong River system in Southeast Asia
decline” in the number of fish species in the Mekong River system in Southeast Asia where two tributaries have shown declines in fish species, while an increase in diversity was noted in a third, largely free-flowing tributary.
Sarah Null, water resources expert in the Utah State
University’s Department of Watershed Sciences, and an author on the study, says that this is one of the first pieces of research to show reduced fish diversity
following dam construction, contrasted with increased diversity in less fragmented rivers in the Mekong River system.
Flowing through six Asian countries, the Mekong supports the highest levels of fish harvest from any inland fishery in the world, sustaining the livelihoods of tens of millions of people. The authors claim that the region’s rapid pace of hydropower development, which includes 129 commissioned dams in the Lower Mekong Basin, will disrupt and block fish migrations and alter fish communities and aquatic ecosystems, leading to decreased biodiversity, abundance, and biomass, according to the authors. The team focused on the Sesan, Srepok and Sekong Rivers that make up just 10 percent of the Mekong watershed geographically, but provide as much as 25 percent of the main river’s flow, supporting 40 percent of the more than 1000 species of fish found in the Mekong River system. The diversity of select fish species decreased
alarmingly in the more heavily dammed Sesan and Srepok Basins, the study found, from 60 and 29 species in 2007 to 42 and 25 species in 2014. During the same period, it increased from 33 to 56 species in the Sekong, the basin with the fewest dams. The results show the importance of keeping rivers like the Sekong free-flowing, said Ratha Sor, researcher at Utah State University and Chea Sim University of Kamchaymear in Cambodia, and lead author of the study. “The Sekong Basin plays an important role as a
free-flowing river corridor for fish migration and can potentially compensate for environmental changes and habitat loss in the Sesan and Srepok Basins,” said Sor. To preserve biodiversity and stem the potential decline in fish species, the researchers urge policymakers to focus on developing other renewable sources of energy and optimising hydropower at existing dams as alternatives to the construction of new dams in the Mekong region.
References
https://www.usu.edu/today/story/dams-at-fault-for-fish- disappearing-from-mekong-river-research-shows
32 | November 2023 |
www.waterpowermagazine.com
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