Protecting high-value areas from introduced marine species

We developed two risk models to investigate the movement of introduced marine species into High-value areas (HVAs), using Undaria pinnatifida invasions in New Zealand as a model system. This process focussed on the secondary transfer of Undaria into the HVAs, as it is already introduced to New Zealand. The first model was a qualitative, theoretical risk assessment based on expert opinion, and was used by management to re-assess the potential impacts of Undaria on values associated with a set of six, expert identified, HVAs. The risk reassessment process identified that Undaria posed an extreme risk to a majority of values in all evaluated HVAs. Based on this outcome, a realised risk assessment model was developed and is described that uses quantitative vessel and propagule strength data to examine secondary transfers of Undaria into HVAs. The realised risk assessment is the next stage in the process of delineating the risk Undaria poses to New Zealand HVAs. The intent of this process was to provide salient, credible and legitimate information to decision-makers in a transparent manner because direct impact data is limited and uncertain. Both models presented are readily applicable to Undaria invasions in different regions and countries, with the original re-assessment model having been used by biosecurity managers.