Nature-based experiences support lasting conservation behavior: longitudinal evidence from shark ecotourism in Hawaiʻi

Shark ecotourism is increasingly promoted as a nature-based solution for ocean sustainability, yet empirical evidence of its long-term impacts on conservation behavior remains limited. We employed a quasi-experimental, longitudinal design to evaluate whether participation in a shark ecotourism program in Hawaiʻi influenced individual conservation behavior over time. Survey data were collected from tour participants and a general public comparison group at the time of the tour and again two years later. Using a Bayesian model for quasi-experimental repeated cross-section with inverse-probability weighting and attrition adjustment to account for baseline differences, we find that participation in the program was associated with a 40% increase [26%, 55%] in the likelihood of engaging in shark conservation behavior two years post-tour. While overall conservation engagement increased among all respondents during the study period, this sustained effect of program participation provides suggestive evidence that this form of experiential nature-based tourism can produce durable pro-environmental behavior. By identifying common forms of engagement (e.g., social media, donations) and key barriers to deeper involvement, our findings offer actionable insights for inclusive and scalable marine conservation strategies.