Chinook Salmon Restoration in California
While many streams and rivers throughout the central valley of California historically supported vibrant fall and spring runs of Chinook salmon, densities of this economically important species reached a record low in 2007 (go to CNN story). Researchers have proposed a number of possible causes for dwindling numbers of Chinook, including barriers to migration (dams), altered hydrology, and sedimentation to name a few. Collectively, these are thought to reduce the amount of spawning habitat available to adult salmon. To overcome this problem, a common restoration and enhancement practice is to dump truck-loads of medium sized rocks into streams – rocks that are thought to be the optimal size for spawning.
The Merced River serves as a case in point. In 2000, CALFED restored a 1.4-km reach of the Merced River in central CA by reforming the river into a sinuous channel lined with truck-loads of 50-mm rocks. We are taking advantage of the size, and newness of this restoration site to investigate how the restructuring and rescaling of the channel and its floodplain influences physical processes (geomorphology and flow), and how the altered physical conditions directly impact the fish (through their habitat use), and indirectly impact fish (via alterations to algae, macroinvertebrates, and other portions of the food web that support fish).
Collaborators
- Tom Dunne, Bren School of the Environment, UC Santa Barbara
- Hunter Lenihan, Bren School of the Environment, UC Santa Barbara
- Frank Davis, Bren School of the Environment, UC Santa Barbara
- Bruce Kendall, Bren School of the Environment, UC Santa Barbara
- Roger Nisbet, Dept Ecology Evolution & Marine Biology, UC Santa Barbara
Acknowledgements
CALFED.