Spreading the Risk: Native Trout Management in a Warmer and Less-Certain Future

Abstract

Management strategies that increase biological diversity and promote varied approaches to population protection are more likely to succeed during a future in which global warming drives rapid environmental change and increases uncertainty of future conditions. We describe how the concept of a diverse management portfolio can be applied to native trout conservation by increasing representation (protecting and restoring diversity), resilience (having sufficiently large populations and intact habitats to facilitate recovery from rapid environmental change), and redundancy (saving a sufficient number of 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 historical 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 management for larger population sizes and larger habitat patches than currently exist for many native trout populations. Redundancy among these elements is important given that many populations are small and occupy reduced habitat in fragmented stream systems and therefore are increasingly vulnerable to extirpation. Application of the concept is further described in case studies of Yellowstone cutthroat trout Oncorhynchus clarkii bouvieri and Rio Grande cutthroat trout O. clarkii virginalis, two subspecies that illustrate many of the challenges that are common to management of western native trout. Received May 16, 2011; accepted January 12, 2012

Declining patterns of Pacific Northwest steelhead trout (Oncorhynchus mykiss) adult abundance and smolt survival in the ocean

“…Less-correlated abundance and survival trends can indicate more robust and sustainable metapopulations that are able to withstand short-and long-term stressors such as predation, variable environments, and climate change (Ando and Mallory 2012;Haak and Williams 2012;Heino et al 1997). For example, variability in the abundance of the many, heavily harvested Bristol Bay, Alaska sockeye salmon (Oncorhynchus nerka) populations, as opposed to similar abundance patterns, results in higher overall abundance of all populations and fewer fishery closures (Schindler et al 2010).…”

Annual Variation of Spawning Cutthroat Trout in a Small Western USA Stream: A Case Study with Implications for the Conservation of Potamodromous Trout Life History Diversity

“…Understanding such diversity may become increasingly important in identifying and prioritizing restoration and conservation strategies to enhance species persistence (Haak and Williams 2012;Segurado et al 2013). Accurately characterizing life history Downloaded by [Queensland University of Technology] at 01:12 21 October 2014 patterns (e.g., spawning distribution and timing) can additionally help identify management strategies (e.g., angling regulations, cattle grazing) to minimize the detrimental effects on target populations (Gregory and Gamett 2009;Peterson et al 2010).…”

Conservation of Native Pacific Trout Diversity in Western North America

“…Pacific trout are especially vulnerable to the effects of climate change in freshwater habitats because they require cold, interconnected, and high-quality habitats, which have already been fragmented and degraded by other anthropogenic activities in many areas. Many populations inhabit waters that are near or at thermal limits (Sloat and Osterback 2013;Matthews and Nussle 2014), and such populations are likely more susceptible to climatic change (Haak and Williams 2012). Pacific trout have persisted under dynamic conditions for millennia, likely due to their broad diversity and ability to disperse, both of which may be critical if they are to persist in a warming world combined with other emerging threats (Waples et al 2008).…”

“…Managers often make conservation decisions with incomplete information (USFWS and NMFS 1998;RGCT Conservation Team 2013) and thus it is important to remember that the first principle of "intelligent tinkering" is keeping every "cog and wheel" (Leopold 1949:190), and for Pacific trout that means maintaining diversity of populations and habitats that are broadly distributed across western North America. Conservation actions that spread risk across the riverscape and among potential strategies (e.g., isolation of headwater areas versus connection; Fausch et al 2009) reduce the negative consequences of scientific uncertainty (Haak and Williams 2012). Riparian restoration, water leases, and formal conservation easements may be used to improve and protect critical habitats, especially in catchments that might be more resistant to climate change.…”