Native vs. Non-Native Species Considerations and Tradeoffs During Fish Barrier Restoration Planning

Maintaining or restoring habitat connectivity is one of the cornerstones of conservation management for native stream fishes. Yet connectivity also represents a risk because intact or restored corridors facilitate invasions by nonnative fishes. Recognizing and balancing the benefits and risks of connectivity for freshwater fish populations is increasingly important for fisheries managers, as is prioritizing among conservation alternatives. To these ends, we developed a framework that addresses four questions to guide conservation practitioners. First, what are the conservation values of native fish populations? Second, are populations vulnerable to nonnative species invasions? Third, does isolation constitute a threat to population persistence? And fourth, how might one prioritize conservation actions? We provide examples of using this framework in the Rocky Mountain West, and describe a more formal decision support model for gauging the tradeoffs in connectivity management for native cutthroat trout populations at risk from invasions by nonnative brook trout.