Developing an ecosystem health approach for reducing risk of fish pathogen introduction in a coupled social-ecological system

Abstract

Today’s interconnected society provides ample opportunity for the inadvertent spread of dangerous diseases. Human activities are also capable of spreading wildlife diseases that can have devastating impacts on populations and threaten biodiversity. In inland fisheries, the use and release of live baitfish by recreational anglers has been identified as a particularly important pathway for the spread of pathogens. Despite regulations prohibiting it, baitfish release is widespread and common among anglers, providing substantial opportunity for pathogen spread via this pathway. To address key knowledge gaps and understand the social and ecological dimensions of risk of pathogen spread, I developed an ecosystem health approach to identify, quantify, and mitigate the risk of fish pathogen introduction via the release of live baitfish in Minnesota, USA. I first created a hazard prioritization method to identify the pathogens most likely to harm important Minnesota fishes via release of live baitfish. To quantify the risk of one of these pathogens being released into Minnesota waters, I implemented a survey of adult anglers and used this data to parameterize a stochastic risk assessment model. I modelled pathogen introduction risk across a variety of scenarios representing baseline, outbreak, and source-control scenarios. I found that the average number of angling trips resulting in pathogen release was high across all modeled scenarios, ranging from fewer than 10,000 in a small, localized outbreak, to 1.2 million in a statewide outbreak in multiple live baitfish species. Additionally, I found reducing the rate of illegal release could offer meaningful risk reduction in some scenarios with high pathogen prevalence and/or broad pathogen distribution, but this effect was less pronounced in scenarios where the outbreak was geospatially or otherwise limited. Finally, I used the Theory of Planned Behavior to identify the social and psychological determinants of baitfish release behavior and found that knowledge of the existing regulatory framework and subjective norms around live baitfish disposal play an important role in deterring illegal release. In these four chapters, I demonstrate the implementation of an integrated social-ecological approach to a complex ecosystem health issue and provide a roadmap for managing the risk of fish pathogen introduction via live baitfish release in Minnesota.