Graduation Date

Summer 2020

Document Type



Master of Science degree with a major in Natural Resources, option Fisheries

Committee Chair Name

Dr. Mark Henderson

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Dr. Andrew Kinziger

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

Dr. Darren Ward

Third Committee Member Affiliation

HSU Faculty or Staff

Subject Categories



Environmental DNA (eDNA) has the potential to dramatically increase the information available to managers regarding species distribution and abundance. Collection of reliable survey information on fish abundance is essential to monitor population trends and restoration efforts for endangered and threatened species. In Northern California, coho salmon are a federally listed species and a focus of ongoing monitoring programs and restoration projects. I examined the feasibility of using eDNA to supplement, or replace, traditional outmigrating juvenile coho salmon monitoring approaches currently used at two existing coho salmon life-cycle monitoring stations. Over the spring of 2018 and spring of 2019, I collected water samples, water quality, and flow information during the coho salmon smolt migration season at cross-sections of two creeks in Northern Humboldt County, California concurrently with daily downstream migrant trapping. In addition, I compared differences in the amount of eDNA filtered from water samples collected and filtered through multiple filter sizes and material. Extracted DNA was amplified using qPCR and a species-specific assay. Results of model selection using weekly and daily abundance estimates and Flow Corrected eDNA indicate high variability of eDNA concentration both within sites and between sites for each creek. The best-fit models did not include Flow Corrected eDNA; a measure of eDNA concentration adjusted for stream flow. However, when using Flow Corrected eDNA values to generate an additional measure of abundance, Area Under the Curve (AUC), the predictive ability of the models increased significantly on both Prairie and Freshwater Creek. A linear regression resulted in a significant positive relationship that explained 71% of the variation between AUC and the downstream migrant coho salmon estimates on Prairie Creek and 88% of the variation in Freshwater Creek in 2018. Additionally, there was a significant relationship between AUC and the downstream migrant coho salmon estimates in 2019 for only one of the filter sizes tested. These results imply that this approach shows promise for elucidating relationships between eDNA and juvenile coho abundances, but more research is necessary to determine what sampling methods, and analytical approaches, to use in these small lotic systems.

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