Midwest Fish & Wildlife Conference 2016

AUTHORS: Gary Whelan*, Michigan Department of Natural Resources

ABSTRACT: Given the shared resource occupied by wild and hatchery fish, frequently in the same public trust waterbody, it is not surprising that there is a long history of fish pathogen transfers that have occurred between these fish. These transfers started with the mass untested transfers across the continent and stocking of these fish by public (mainly) and private hatcheries from the 1800s to the early 1970s then continued with poor fish health oversight of private aquaculture by public resource agencies and resulting unregulated fish transfers in that industry through the 1990s. This paper will focus on likely landscape transmission history of Myxobolus cerebralis (whirling disease) and Renibacterium salmoninarum (bacterial kidney disease) in Michigan and other parts of the U.S. to illustrate how such pathogens move between hatchery and wild fish and wild and hatchery fish, and touch on likely transmission routes of other pathogens from domesticated sources to wild fish. The body of work to date and the transmission history clearly shows these interactions to occur. Conversely, I will illustrate how “disease free” hatchery fish can be used to break transmission vectors using the Great Lakes Fish Health Committee Bacterial Kidney Disease Strategy starting in the 1990s as a prime example of how disease interactions can be manipulated using these two groups of fish for the betterment of the public trust resource. To ensure that future interactions between hatchery and wild fish are minimal and positive, it is critical that full disease testing and certification occurs for all hatchery fish along with aggressive, coordinated and preemptive fish health planning and surveillance to determine where “problematic” pathogens occur and allow use of “clean” hatchery fish use to break destructive fish pathogen transmission routes in wild fish populations.