The primary focus of this project is to determine the distribution, prevalence, and genetic composition of non-native Salmincola spp. (commonly referred to as gill lice) and the potential impacts that Salmincola spp. are having on the Commonwealth’s wild trout populations. Of particular concern are the impacts of Salmincola spp. on Pennsylvania’s wild Brook Trout and Rainbow Trout including Steelhead in Lake Erie and its tributaries. This project will provide important information on fish health of wild trout and provide insight into whether gill lice may be a host and/or vector for other pathogens resulting in a decrease in wild trout abundance, reduced wild trout genetic diversity, and reduced distribution of wild trout across the state. These data will be beneficial to guiding management decisions to stop the spread of Salmincola spp. including how the Pennsylvania Fish and Boat Commission (PFBC) regulates the stocking and movement of hatchery and wild fish. The importance of gathering additional data to validate concerns that were derived from initial studies, both in Pennsylvania and from other state agencies is imperative to developing polices, regulations, and best management practices that continue to protect, conserve, and enhance Pennsylvania’s wild trout populations.