Comparative Dispersal Patterns for Recolonizing Cedar River Chinook Salmon above Landsburg Dam, Washington, and the Source Population below the Dam

Abstract Anadromous salmonid populations are particularly vulnerable to migration blockages, such as dams and culverts, because access to historic spawning and rearing habitats is prevented. The process of salmonid recolonization has not been well documented for river systems where anthropogenic migration barriers have been removed or where fish passage facilities have been constructed. In September 2003, Seattle Public Utilities completed construction of a fish passage facility that circumvented Landsburg Dam on the Cedar River, Washington. Chinook Salmon Oncorhynchus tshawytscha spawned in newly available main-stem habitats immediately after fish passage facility construction and in all subsequent years. Further dispersal into tributary habitats occurred 5 years after construction. Redds tended to be concentrated in the downstream third of the available habitat above the dam, although some fish did utilize suitable spawning sites throughout the main stem, even in the uppermost reaches of the newly avail...