Potential habitat loss and population fragmentation for cold water fish in the North Platte River drainage of the Rocky Mountains: Response to climate warming

We used three approaches to examine potential habitat loss in relation to climate warming for cold water species of fish in the North Platte River drainage in Wyoming. The projected loss of habitat varied among approaches, but all methods indicated a noticeable loss of habitat for even minor increases in temperature. An approach based on the use of summer air temperatures to define the thermal limits of cold water species estimated a loss of 9–76% of the present geographic range for temperature increases of 1–5°C. A second approach, also based on air temperature limits, projected a loss of 7–64% of the stream distance currently having thermally suitable habitat for cold water fish for temperature increases of 1–5°C. A third approach, based on the use of summer water temperatures to define the thermal limits of cold water species, projected a loss of 16–69% of the stream distance currently having thermally suitable habitat for temperature increases of 1–5°C. In addition to habitat loss, population fragmentation would occur as remaining enclaves of cold water fish are forced to retreat to increasingly isolated headwater stream reaches.