Conservation planning at the intersection of landscape and climate change: brook trout in the Chesapeake Bay watershed

We developed a multi-scale conservation planning framework for brook trout (Salvelinus fontinails) within the Chesapeake Bay watershed that incorporates both land use and climate stressors. Our specific objectives were to (1) construct a continuous spatial model of brook trout distribution and habitat quality at the stream reach scale; (2) characterize brook trout vulnerability to climate change under a range of future climate scenarios; and (3) identify multi-scale restoration and protection priorities for brook trout across the Chesapeake Bay watershed. Boosted regression tree analysis predicted brook trout occurrence at the stream reach scale with a high degree of accuracy (CV AUC = 0.92) as a function of both natural (e.g., water temperature and precipitation) and anthropogenic (e.g., agriculture and urban development) landscape and climatic attributes. Current land use activities result in a predicted loss of occurrence in over 11,000 stream segments (40% of suitable habitat) and account for over 15,000 km (45% of current value) of lost functional brook trout fishery value (i.e., length-weighted occurrence probability) in the Chesapeake Bay watershed. Climate change (increased ambient temperatures and altered precipitation) is projected to result in a loss of occurrence in at least 3000 additional segments (19% of current value) and at least 3000 km of functional fishery value (9% of current value) by 2062. Model outcomes were used to identify low- and high-quality stream segments within relatively intact and degraded sub-watersheds as restoration and protection priorities, respectively, and conservation priorities were targeted in watersheds with high projected resilience to climate change. Our results suggest that traditional restoration activities, such as habitat enhancement, riparian management, and barrier removal, may be able to recover a substantial amount of brook trout habitat lost to historic landscape change. However, restoration efforts must be designed within the context of expected impacts from climate change or those efforts may not produce long-term benefits to brook trout in this region.