Spreading the Risk: Native Trout Management in a Warmer and More Uncertain Future

Management strategies that maximize biological diversity and promote varied approaches to population protection are more likely to succeed during a future where global warming drives rapid environmental change and increases uncertainty.  We describe how the concept of a diverse management portfolio can be applied to native trout conservation by providing for Representation (protecting/restoring diversity), Resilience (having sufficiently large populations and intact habitats to survive environmental change), and Redundancy (saving enough different populations so that some can be lost without jeopardizing the species).  Saving diversity for native trout requires the conservation of genetically pure populations, the protection and restoration of life history diversity, and the protection of populations across the historic range.  Protecting larger, stronghold populations is important because such populations will have a better chance of surviving future disturbances, including those associated with climate change.  The long-term persistence of populations is likely to require maintenance of larger population sizes and habitat patches than currently exist for many populations.  Redundancy among these elements is important given that many populations are small, occupy reduced habitat in fragmented stream systems, and therefore are vulnerable to extirpation.  Application of the concept is further described in case studies of Yellowstone cutthroat trout and Rio Grande cutthroat trout, two subspecies that illustrate many of the management challenges common to western native trout.