Cooperative Fish and Wildlife Research Units Program: Colorado
Education, Research and Technical Assistance for Managing Our Natural Resources

Colorado Project

Assesing the role of Whirling Disease in Causing Trout Declines in the North Tongue River

July 2023 - June 2025


Participating Agencies

  • Wyoming Game and Fish Department

Identifying whether whirling disease is contributing to trout population declines is essential to formulating management strategies that will maintain viable trout populations on the North Tongue. Using the approaches outlined in the proposal, we will be able to better understand natural disease levels in wild fish and exposure risk to fish over the controlled caging study duration. The expected results will include MC infection prevalence and infection intensity information across species and life stages of the five trout species present. We will also have a clearer understanding of spatial variation in disease risk across the six stations. In general, this information will determine whether MC is contributing significantly to trout population declines or whether more studies are needed to evaluate other possible causal factors of population declines. These results will collectively be useful in management decision making, including possible adjustments to the number and strains of trout that are stocked to better sustain fish populations for angling in the presence of MC. For instance, it may be desirable to shift the fishery towards more resistant strains, but detailed information on MC status is needed beforehand.