Comparing Models of Estimated Range Shifts in Pacific Salmon

Changes in ocean and stream temperatures will affect the pattern of suitable habitat throughout Pacific Salmon’s range. Here we compare initial results from two methods of estimating the potential shift in the fundamental niche for Chinook Salmon. Using Pacific Rim-wide stream temperature scenarios, we first consider a simple mechanistic probability model of Chinook range, based on physiological temperature limits.  We then apply a correlative envelope model to estimate Chinook salmon range in the future. We use a principal coordinates analysis to identify key predictors of current salmon habitat, and use those historical values to calibrate a random forest model projection under a novel climate scenario. We compare results and discuss implications of model uncertainty for salmon conservation in the face of climate change.