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 <i>Undaria pinnatifida</i> invasions in New Zealand as a model system. This process focussed on the secondary transfer of <i>Undaria</i> 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 <i>Undaria</i> on values associated with a set of six, expert identified, HVAs. The risk reassessment process identified that <i>Undaria</i> 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 <i>Undaria</i> into HVAs. The realised risk assessment is the next stage in the process of delineating the risk <i>Undaria </i>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 <i>Undaria</i> invasions in different regions and countries, with the original re-assessment model having been used by biosecurity managers.