Assessing the Risk of Fish Pathogen Introduction via the Illegal Release of Live Baitfish in Minnesota

1,2 Meg C. McEachran, 3 Janice Mladonicky, 3 Catalina Picasso, 4 Fernando Sampedro,

1,3 Dominic A. Travis, 1,2 Nicholas B. D. Phelps

1 Department of Fisheries, Wildlife, and Conservation Biology, University of Minnesota; 2 Minnesota Aquatic Invasive Species Research Center; 3 Center for Animal Health and Food Safety, College of Veterinary Medicine; 4 Environmental Health Sciences Division, School of Public Health, University of Minnesota; 5 One Health Division, Department of Veterinary Population Medicine, College of Veterinary Medicine

ABSTRACT

The release of live fish used as bait by recreational anglers has been identified as a high-risk pathway for the spread of aquatic invasive species and harmful fish pathogens which may be introduced alongside otherwise innocuous native species. Live baitfish release is consequently outlawed in several states, but compliance is less than perfect and release rates range from 20-40% of the millions of anglers that buy a license every year, resulting in significant opportunities for pathogen introduction. Using a risk analysis approach, we created a hazard identification and prioritization framework for determining the pathogens with greatest potential to cause harm to wild fish via release of live baitfish. We then developed a stochastic risk analysis framework parameterized by angler survey data and applied it to assess the risk of introduction of the three pathogens ranked most highly by the prioritization framework by quantifying the number of “risky trips”, or trips that result in the release of an infected baitfish. Our hazard prioritization framework identified viral hemorrhagic septicemia virus, the microsporidian parasite Ovipleistophora ovariae, and the Asian fish tapeworm Schizocotyle acheilognathi as potential pathogens of the baitfish pathway with the highest risk of harm to wild fish populations. We assessed the number of risky trips under four scenarios: current/baseline conditions, outbreak conditions (increased pathogen prevalence), source-focused control measures (decreased pathogen prevalence), and angler-focused control measures (decreased rates of release). Preliminary results show that under baseline conditions, many opportunities for pathogen spread exist, but that implementing risk-based management could show significant risk reduction.