Can we predict risky human behaviour involving invasive species? A case study of the release of fishes to the wild

Managing risky human behaviour involving invasive species, such as unauthorized stocking or the release of pets to the wild, is difficult because the rationale for risk taking is often unknown. To identify factors that increase the likelihood of risky behaviour, we conducted social surveys and analyzed perceptions about invasive species, natural resource management, social norms, and outreach initiatives for live bait anglers in Ontario, Canada and Michigan, USA. We used classification trees to predict risky behaviour (release of fishes; Ontario, P-release = 0.197, Michigan, P-release = 0.275) based on patterns of variation in social perceptions. Irrespective of release, respondents generally agreed with (and exhibited strong willingness to pay for) prevention management, despite only moderate consensus that natural resource use had been impacted by invasive species. The most parsimonious model to predict release was based on the convenience of releasing fishes and the (mis) perception that released fishes provide an ecological benefit to natural resources, which held for 70.5 % of risk takers (classification rate = 80.6 %, true negative rate = 84.6 %, AUC = 0.81). Therefore, perceptions other than those directly involving invasive species strongly increase the likelihood that an individual will release fishes to the wild. For a subset (29.5 %) of risk takers, release behaviour was unpredictable and lacked obvious rationale; therefore, additional invasive species management efforts remain justified to offset individual actions that may never be understood with certainty and for which targeted social outreach strategies are likely ineffective.