Risk analysis is a dynamic process: has the risk ranking of the non-native freshwater fishes in England and Wales changed over the past 15 years?

Non-native species risk analysis is a dynamic process that requires periodic review and revision. In this study, we investigated changes in the risk ranks of the 69 non-native freshwater fish species in England and Wales previously screened with the Fish Invasiveness Screening Kit using its successor, the Aquatic Species Invasiveness Screening Kit (AS-ISK). Our objectives were to assess shifts in species risk ranks, evaluate the implications of transitioning to the AS-ISK, and integrate climate change predictions into the screenings. Re-screening revealed several changes, with eleven species re-categorized from non-invasive to invasive and one from invasive to non-invasive, and with 18 species changing their risk ranks. Climate change projections influenced outcomes, with 40 out of 41 high-risk species maintaining such status when accounting for this component. The re-screening process implemented in this study emphasizes the importance of updating protocols to incorporate new data and climate change projections for more accurate risk screening. Analysis showed varied responses to climate change among species, with implications for management strategies. Salmonids exhibited nuanced responses, suggesting the need for tailored management approaches. Confidence levels were generally medium, highlighting the importance of continual refinement. Our study underscores the necessity of regularly updating non-native species risk screenings and follow-up assessments to account for newly available literature information. By integrating new data and climate change scenarios, the effectiveness of management strategies can be enhanced with the aim of safeguarding aquatic ecosystems and their biodiversity. Further research should focus on refining the entire risk analysis process and understanding species responses to changing environmental conditions to inform proactive management approaches.