Within their native range in the United States (U.S.), brook trout (Salvelinus fontinalis) are valued for the recreational opportunities they provide to anglers and for their utility as indicators of the environmental health of the habitats in which they are found. For brook trout, stream temperatures within their viable thermal range (0°-25°C) are vital to ensuring growth, reproduction, and survival. Changes in air temperatures related to climate change will influence stream temperatures, likely resulting in alterations in the distribution and quantity of thermal habitat available for brook trout, leading to changes in this fish's range and productivity. I examined the effects of changing air temperature on brook trout thermal habitat availability for 51 streams across 30 subbasins spanning the latitudinal and longitudinal gradient of the brook trout's native range in the U.S. To determine the impact of air temperature changes driven by climate change for these streams, I converted air temperatures projections for the subbasin level from three coupled climate models into stream temperatures using two linear regression models and then rated the quality of stream habitat for brook trout growth and survival based on the results. According to both linear regression models, all 30 subbasins were predicted to increase in temperature by between 0.94°C and 4.16°C from 2006 to 2056, resulting in reduced thermal habitat quality for brook trout in 20 subbasins according to the first model and 15 according to the second model. To mitigate the effects of climate change related increases in water temperatures due to increased air temperature over the course of the next half-century, fisheries managers must focus their efforts on keeping streams as cool as possible by protecting and planting riparian zone shading and by guarding against additional sources of stream warming such as influxes of runoff during storm events and by maintaining other natural stream cooling mechanisms, like groundwater inputs.
Read
