Using Viable Salmonid Population (VSP) Modeling to Help Prioritize Actions for Willamette River Chinook Salmon and Steelhead Populations

Viable salmonid population (VSP) models provide a framework for investigating how specific management actions have population-level impacts. The four VSP metrics are Abundance, Productivity, Diversity, and Spatial Structure.  We developed stage-specific, life-cycle models for four populations of spring Chinook salmon and two populations of winter steelhead in the upper Willamette River basin in Oregon.  The models were designed to produce VSP metrics as output, and we used the models to assess a suite of potential management actions primarily designed to reestablish natural populations above high-head dams. We will present results of the modeling effort and discuss how VSP metrics can be used to rank alternative actions.  Finally, we conducted a sensitivity analysis that identified several highly influential parameters in the models. One set of these influential parameters represents juvenile capacity above and below the dams, and we will discuss how we are designing studies to reduce uncertainty in these parameters.