Planning Pacific Salmon and Steelhead Reintroductions Aimed at Long‐Term Viability and Recovery

Abstract

Local extirpations of Pacific salmon Oncorhynchus spp. and steelhead O. mykiss, often due to dams and other stream barriers, are common throughout the western United States. Reestablishing salmonid populations in areas they historically occupied has substantial potential to assist conservation efforts, but best practices for reintroduction are not well established. In this paper, we present a framework for planning reintroductions designed to promote the recovery of salmonids listed under the Endangered Species Act. Before implementing a plan, managers should first describe the benefits, risks, and constraints of a proposed reintroduction. We define benefits as specific biological improvements towards recovery objectives. Risks are the potential negative outcomes of reintroductions that could worsen conservation status rather than improve it. Constraints are biological factors that will determine whether the reintroduction successfully establishes a self‐sustaining population. We provide guidance for selecting a recolonization strategy (natural colonization, transplanting, or hatchery releases), a source population, and a method for providing passage that will maximize the probability of conservation benefit while minimizing risks. Monitoring is necessary to determine whether the reintroduction successfully achieved the benefits and to evaluate the impacts on nontarget species or populations. Many of the benefits, especially diversity and the evolution of locally adapted population segments, are likely to accrue over decadal time scales. Thus, we view reintroduction as a long‐term approach to enhancing viability. Finally, our review of published salmonid reintroduction case studies suggests that large uncertainties remain in the success of reintroduction in establishing self‐sustaining populations, particularly for programs employing active methods. Received September 10, 2012; accepted August 30, 2013 Published online January 30, 2014

Dispersal and productivity of Chinook (Oncorhynchus tshawytscha) and coho (Oncorhynchus kisutch) salmon colonizing newly accessible habitat

“…), contributing to lost biodiversity, local extinctions, and threatened or endangered conservation status within regions occupied by extant populations (National Research Council 1996;Sheer and Steel 2006;Gustafson et al 2007;McClure et al 2008). Dam removal or circumvention projects intended to benefit Pacific salmon and steelhead (anadromous rainbow trout, Oncorhynchus mykiss) have increased markedly over the last decade, and research quantifying colonization patterns and processes is needed to provide a scientific foundation for management decisions confronting such projects (Anderson et al 2014).…”

Predation by Northern Pikeminnow and Tiger Muskellunge on Juvenile Salmonids in a High‐Head Reservoir: Implications for Anadromous Fish Reintroductions

“…These methods involve trapping returning adults below the dams and releasing them into the watershed above, then trapping downstreammigrating smolts at or upstream from the dams and releasing them below these barriers. This strategy, which reintroduces salmon into high-elevation habitat above dams, can help conserve anadromous salmonids by enhancing life history diversity, abundance, productivity, and spatial structure, and may provide a refuge from the effects of climate change and development (McElhany et al 2000;Bilby and Mollot 2008;Schindler et al 2008;Anderson et al 2014).…”

“…Risks include homogenization of population structures, depletions of source populations, and the spread of disease (Viggers et al 1993;Williamson and May 2005;Eldridge and Naish 2007). If these risks are not prohibitive, then potential constraints include the lack of adequate passage around remaining barriers, suitable spawning habitat, and conditions that support the survival of juveniles and adults in the face of changing climate and land use (Beechie et al 2006;Ferguson et al 2007;Schaller and Petrosky 2007;Bilby and Mollot 2008;Sanderson et al 2009a;Anderson et al 2014).…”

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“…We suggest coordination through the formation of specific technical working groups similar to WSWG for preremoval planning, management during removal, and postremoval monitoring. In retrospect, the development of management options by WSWG for each fish species followed a similar decision framework as that outlined by Anderson et al (2014b). The management options ultimately coalesced on postremoval monitoring and reassessment of fish populations and management options in five-year intervals.…”