Risk-Based Management of Viral Hemorrhagic Septicemia Virus in Minnesota

Viral hemorrhagic septicemia virus (VHSV; strain VHSV-IVb) is an emergent and serious disease of fish in the Great Lakes region of North America. In addition to the numerous large-scale mortality events in wild fish, the emergence of VHSV has resulted in a major regulatory response to protect both farm-raised and wild fish populations. However, characterizing and mitigating risk factors for the continued transmission of VHSV is a difficult task. A semiquantitative risk assessment model was used to focus VHSV management efforts in Minnesota. The risk of VHSV introduction into major watersheds in Minnesota was directly correlated to their proximity to Lake Superior, the only VHSV-positive body of water in the state. Although the current regulations are uniform across Minnesota, the risk varied for specific locations within the watersheds. For example, the introduction of game fish for stock enhancement (a common fisheries management practice) is a significant factor in determining the risk of VHSV introduction into public waters, as is the movement of baitfish. In this analysis, aquaculture facilities with strict biosecurity programs and frequent health inspections received the lowest risk scores and were largely considered as protective or at low risk for VHSV introduction. These results suggest that the current management strategy, based on political boundaries, should be reevaluated. We recommend the creation of a risk-based management strategy based upon the identification of higher-risk watersheds and specific bodies of water, thus allowing managers to efficiently target surveillance and response activities in Minnesota.Received July 22, 2013; accepted November 27, 2013.