Gill lice distribution, prevalence, and infestation intensity in the Upper Snake River Watershed

Pathogens are an emerging threat in aquatic ecosystems and are predicted to negatively affect fish populations with climate change. Climate change has the potential to affect the abundance, distribution, and infestation intensity of pathogens such as gill lice, ectoparasitic copepods that parasitize fish. The synergistic and antagonistic effects of these parasites and changing environmental conditions caused by climate on fish population dynamics are poorly known. We hypothesize that climate, fish population and community structure, and gill lice biology are interacting to drive the distribution, prevalence, and intensity of gill lice infestations. Using data from the Wyoming Game and Fish Department and USGS we looked at multiple years of thermal and flow regimes in the Snake River. We explored interannual variability in gill lice outbreak timing and extent in relation to environmental conditions. The preliminary results suggest gill lice prevalence and infestation intensity is low; however, differences across years suggest water levels, flow rates, and water temperature may influence gill lice prevalence and infestation intensity. Our research provides critical baseline data on pathogen-fish interactions in the Upper Snake River watershed.