U.S. conservation translocations: Over a century of intended consequences

Abstract

Conservation translocations (reintroductions, reinforcements, ecological replacements, and assisted colonization) have played a vital and necessary role in conserving endangered species and ecosystems. Yet concerns over potential unintended ecological consequences frequently hinder the progress of translocation activities. We reviewed the history of U.S. translocations to ask: how often were intended benefits the result versus harmful unintended consequences? We found that translocations played a key role in recovery for 30% (14 of 47) of U.S. delisted taxa. Translocations have been performed, are planned, or are part of continuing recovery actions for 70% (1,112 of 1,580) of listed threatened and endangered taxa. Of the 1,014 total taxa we found with recorded conservation translocations spanning 125 years, we found only one restricted instance that caused a loss of biodiversity. All other reports of negative consequences were caused by translocations performed for economic and cultural interests in the absence of conservation-based governance. Examples included fish stocking for sport and biological control programs for agricultural pests. We included biological control programs in this analysis because they can be and often are used as conservation tools, to directly benefit ecosystems.

Conservation science and the ethos of restraint

“…What might justify sliding toward proaction? Novak, Phelan, and Weber (2021) argue that some of the fears of unintended consequences rest on iconic historical examples of failed introductions that are poor analogues for today's conservation interventions, and they collect data demonstrating that harmful unintended consequences are exceptionally rare for a large class of conservation strategies. We agree with Novak, Phelan, and Weber that better, more systematic and accessible data comparing harmful to beneficial consequences of conservation interventions could help conservationist scientists and practitioners update their priors on risks, benefits, and costs.…”

“…Avoiding the precaution/proaction dichotomy in conservation science requires assembling disparate knowledge around specific conservation cases to inform improved assessments (Novak, Phelan, & Weber, 2021). Given that knowledge will always be imperfect, interventions should include management plans that seek to identify both intended and unintended consequences on timescales that can allow redirection.…”

“…First, we must devise procedures for filling knowledge gaps. These gaps include (a) a systematic assessment of consequences of interventions (see Novak, Phelan, & Weber, 2021), (b) evaluative data on forecasting and tools for assessing benefits, risks, and costs (see Mozelewski & Scheller, 2021), (c) development of small-scale interventions, mesocosm studies, and means of control, and (d) better understanding of the indirect and social effects of technologies and conservation actions. These forms of knowledge should influence risk assessments and their use.…”

“…The thesis of this special issue of Conservation Science and Practice is that biotechnology and conservation genetics are under-utilized tools capable of slowing species loss and the erosion of biodiversity. Articles in this issue identify and evaluate successful translocations (Smith & Peterson, 2021), the potential for genetic modification to rescue species like the American chestnut (Newhouse & Powell, 2021), and the need to systematically collect and standardize evaluative data on these forms of conservation interventions (Novak, Phelan, & Weber, 2021). All these approaches resist what we call an ethos of restraint: an attitude of excessive precaution that threatens to miss opportunities for advancing conservation goals by restricting the implementation of novel conservation techniques.…”

Intended consequences statement

“…For some highly documented strategies based on conservation principles, such as biological control, conservation translocations, and restoration of natural fire regimes, evidence to date suggests that careful planning produces the intended consequences while avoiding adverse unintended consequences. For example, better identification and mitigation of risks has resulted in no severe, negative, unintended consequences for conservation translocations and biological control releases over the last 30 years in the United States (Novak et al, 2021).…”