Vulnerability of Colorado River Cutthroat Trout Habitat to Climate Change in the Green River Basin

For the Green River Basin Landscape Conservation Design (GRB LCD) assessment, we mapped the vulnerability of occupied Colorado River cutthroat trout (Oncorhynchus clarkii pleuriticus) habitat to climate change for each 12-digit hydrologic unit. Cutthroat trout occupied habitat was mapped from the range-wide status report (Hirsch et. al 2013). Using a vulnerability framework, we defined Sensitivity (S) as the total length of occupied cutthroat trout habitat within HUC12 polygons. The exposure parameter incorporates two climate change metrics, the change in flow timing and change in stream temperature. Exposure is quantified as the square root transformed product of the two climate change metrics. Potential Impact (PI) is the square root transformed product of climate change exposure and cutthroat trout habitat sensitivity. Adaptive Capacity (AC) for cutthroat trout habitat was defined as the inverse of mean ambient air temperature for the warmest quarter. Finally, we combined PI and AC into an overall vulnerability rank for HUC12 polygons.