Native Trout Program - Lewis River and White Salmon River Bull Trout: Patches, Occupancy and Distribution
The objective of this project is to describe bull trout patches in the Lewis River and White Salmon River subbasins, Washington, (following Dunham and Rieman 1999, as modified in RMEG 2008). The purpose is to ascertain the utility of this approach for providing guidance in determining potential bull trout distribution in subbasins with limited existing knowledge of the status of this species or information gathered from on-the-ground sampling efforts. Implementation of this project utilizes maximum annual stream temperature, stream size and catchment area as filters for determining potential bull trout habitat in the Lewis River subbasin. Many other factors identified by Dunham and Rieman (1999) may also influence bull trout distribution (e.g., connectivity, stream gradient, geology, hydrologic regimes, presence of nonnative species, road density, solar radiation). However, maximum annual stream temperature (and the corresponding elevation) effectively dictates the range of this species (Rieman and McIntyre 1995) and patch size (catchment area) may be the most important factor determining bull trout occurrence (Dunham and Rieman 1999). Utilizing these three filters provides the opportunity to evaluate a tool using information that most managers can readily acquire.
Dunham, J.B., and B.E. Rieman. 1999. Metapopulation structure of bull trout: influences of physical, biotic, and geometrical landscape characteristics. Ecological Applications 9:642-655.
Rieman, B.E., and J.D. McIntyre. 1995. Occurrence of bull trout in naturally fragmented habitat patches of varied size. Transactions of the American Fisheries Society 124:285-296.
Hudson, J.M., J.R. Cook, B.P. Silver, and T.A. Whitesel. 2010. Lewis River Bull Trout Recovery Monitoring and Evaluation: Patches, Occupancy and Distribution. 2006-2007 Progress Report. U.S. Fish and Wildlife Service, Columbia River Fisheries Program Office, Vancouver, Washington. (pdf 1.39mb)
Silver, B., J. Cook, J.M. Hudson, and T.A. Whitesel. 2009. White Salmon River Bull Trout: Patches, Occupancy and Distribution. 2008 Progress Report. (pdf 1.8mb)