Functional eradication as a framework for invasive species control

Abstract

Invasive species continue to drive major losses in biodiversity and ecosystem function across the globe. Dealing with the effects of invasion is particularly problematic in marine and freshwater habitats, because the pace at which invaders establish often greatly outstrips the resources available for their eradication. While most managers in North America now focus on ongoing containment and suppression interventions, they often lack quantitative guidance from which to set targets and evaluate success. We propose practical guidelines for identifying management targets for invasions for which eradication is unfeasible, based on achieving “functional” eradication – defined as suppressing invader populations below levels that cause unacceptable ecological effects – within high‐priority locations. We summarize key ecological information needed to inform this strategy, including density–impact functions and recolonization rates. We illustrate the framework's application for setting local suppression targets using three globally invasive species as examples: red lionfish (Pterois spp), European green crab (Carcinus maenas), and rusty crayfish (Faxonius rusticus). Identifying targets for suppression allows managers to estimate the degree of removal required to mitigate ecological impacts and the management resources needed to achieve sufficient control of an invader.

Identifying Priorities, Targets, and Actions for the Long-term Social and Ecological Management of Invasive Non-Native Species

“…The logical next step once priorities and targets are ready will be to define instruments, policies, and activities to implement the high-level actions contained in the management plan (Braysher 2017;Green and Grosholz 2021;García-Díaz et al 2021). That is beyond the remit of our manuscript, and we refer readers to Conroy and Peterson (2013), Groves and Game (2016), Braysher (2017), and García-Díaz et al (2021 for further guidance.…”

“…Resolving these trade-offs will require further analyses to evaluate which solutions achieve the most effective management outcomes. Guidance and criteria for assessing and ranking more detailed activities than those defined by the third criterion can be found elsewhere (Groves and Game 2016;Green and Grosholz 2021;Mill et al 2020;Dunham et al 2020;García-Díaz et al 2021).…”

Money Kills Native Ecosystems: European Crayfish as an Example

“…In Finland, and many other European countries, spreading of alien species is illegal, while so far the legal system fails to find culprits or ignores the cases as meaningless in their impacts (our observation). If an alien species cannot be eradicated, a functional eradication could be limiting or even eliminating ecological damage, as has been observed in the case of P. rusticus in North America (Green and Grosholz, 2021). Recent advances in bioengineering would also allow genetic biocontrol, which is based on modifications of the organism's genome in a heritable way that would for example disrupt the reproduction of the alien species (e.g., Teem et al, 2020).…”

Stage-specific overcompensation, the hydra effect, and the failure to eradicate an invasive predator

“…Programs aimed at eradicating invasive species are currently being undertaken worldwide, often at substantial cost (42), including eradication of the European green crab. Invasive species with limited connectivity, highly fecund adults, and strong adult control of juvenile abundance have the potential for overcompensation and thus pose a substantial challenge for eradication programs (43,44). It is critical to improve our predictive abilities in this area and to more fully understand how and why expensive and timeconsuming invasive management programs can fail or, even worse, potentially exacerbate the current impacts of invasive species.…”