https://www.nature.com/articles/s41598-026-65437-0
"Habitat fragmentation is a global driver of decline in biodiversity, yet
evaluations of ecological response following re-connection remain rare. In
2024, four hydroelectric dams on the Klamath River were removed, reconnecting
over 640 km of anadromous habitat and marking the largest dam removal project
completed to date. We used a stationary high-resolution multi-beam imaging
SONAR to quantify adult Chinook salmon (
Oncorhynchus tshawytscha) passage
into newly reopened reaches during the first two migratory seasons following
dam removal. An estimated 7,742 (95% CI: 7,702–7,778) Chinook salmon migrated
upstream in 2024 and 13,310 (95% CI: 12,876–13,733) in 2025, representing
18–19% of fish returning to the Klamath River Basin. Within this period,
Chinook salmon recolonized 88% of their documented historical distribution,
expanding into 345 km of reconnected habitats and reaching elevations of up to
1,250 m. Recolonization required fish to swim through dam removal sites,
complex hydraulic corridors and engineered fishways, demonstrating the
propensity for rapid recolonization at basin scale despite these challenges.
These findings provide the first quantitative assessment of salmon response to
the world’s largest dam removal and demonstrate how reconnection can catalyze
large-scale recolonization in historically fragmented river networks."
Via Esther Schindler.
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*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
