De-extinction in conservation: Assessing risks of releasing resurrected species

Biodiversity is decreasing at an alarming rate, and it is therefore important to set ambitious targets and to explore innovative tools, such as de-extinction, to protect and recover species. However, it is also essential that risks associated with innovative tools, such as release of proxies for extinct species into the wild, be carefully evaluated. Risks associated with such releases parallel those for introducing non-native species or re-introducing locally extinct species and include the possibility that the proxy becomes invasive and affects native species, communities, or ecosystems through predation, competition, browsing, hybridisation, facilitation of spread of diseases, and various ecosystem-level impacts such as changed hydrology or fire regimes. It is essential that such risks of releasing a proxy be subjected to rigorous application of advances in risk assessment science. However, the substantial limits of risk assessment methods for such species must be recognized, and the safety of existing native species and substantial maintenance of existing ecosystem functions should be privileged over potential benefits of releasing a proxy for an extinct species when the reliability of these assessments is limited, as is especially likely when the proxied species is long extinct. Quantifying potential costs and benefits of indirect effects of releasing a proxy - such as lessened public concern for biodiversity loss or increased interest in conservation based on a resurrected charismatic species - do not appear tractable with current risk assessment methods.