Predicting Persistence of Rio Grande Cutthroat Trout Populations in an Uncertain Future

Native western U.S. salmonids are expected to be adversely affected by climate change and its synergistic influence on other stressors.  Rio Grande cutthroat trout (RGCT; Oncorhynchus clarki virginalis) have lost a significant amount of habitat (89%) owing to the introduction of nonnative salmonids and habitat loss. Currently RGCT are restricted to 117 small patches of stream habitat in New Mexico and Colorado.  Predicted future changes in climate (i.e., temperature and precipitation) could further threaten these remaining populations which remain at risk of extirpation from interactions with nonnative salmonids and stochastic disturbances (i.e., wildfire, debris flow, and drought).  From 2010-2014, we documented the thermal regime and baseflow conditions in these habitat patches to assess the current climate vulnerability of RGCT and used these data to develop predictive models of stream temperature and summer baseflow.  We coupled these abiotic predictions with a Bayesian network (BN) that integrates the risks of nonnative salmonids, whirling disease, habitat conditions, and stochastic disturbances to predict the probability of persistence for RGCT populations in the 2040s and 2080s.  The BN model will be beneficial to management agencies by allowing them to prioritize restoration activities by identifying major threats to the persistence of individual RGCT populations.