Modeling Brook Trout Habitat in a Changing Climate

Abstract

The eastern brook trout is the only trout (charr) species native to the eastern U.S., which contains approximately 25% of the entire native range of the brook trout and 70% of the U.S. range. Stream temperature is a fundamental limiting factor in the distribution and production of brook trout and their range is bounded to the south by a mean July air temperature of 21ºC. Average air temperature in the U.S. has risen by 0.6ºC over the last century and may increase by another 6ºC over the next 100 years. Climate warming may threaten the long-term survival of the brook trout populations in the southern Appalachian Mountains. Using projected future climate scenarios and land use/land cover classes, we developed ordinal and binary logistic regression models to characterize current habitat suitability of brook trout, determine future suitable habitat and prioritize subwatersheds for brook trout conservation. Explanatory variables held in common in every model were the baseline variables (either forest or agriculture), the respective baseline variable with temperature as an interaction term and wetlands. This analysis further supports temperature as a major driver in the distribution of brook trout. Projected future suitable habitat was shown to be moving further north over time. This analysis resulted in map outputs illustrating areas of greatest brook trout population subwatershed status changes and indicates potential areas of concern for brook trout survival due to projected future climate scenarios. These results can aid in prioritizing subwatersheds for brook trout conservation and restoration.