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

The Sacramento River is unique in that it supports four different ecotypes of Chinook salmon, Oncorhynchus tshawytscha, including spring, fall, late fall, and winter runs. Unfortunately, due to a combination of anthropogenic actions the spring and winter runs are listed as threatened and endangered, respectively. Monitoring for juveniles in these imperiled populations on the Sacramento River uses a network of monitoring sites with varying reliability. In the upper river, a rotary screw trap located at the Red Bluff Diversion Dam can produce population-level abundance estimates for juvenile Chinook salmon. However, in the lower river monitoring sites are unable to produce population-level abundances due to the unreliability of run identification, low juvenile catch rates, and the inability to estimate gear efficiencies. Environmental DNA (eDNA) techniques could be used to more effectively sample in the lower river, where salmon densities are lower. This data would ultimately facilitate a better understanding of the timing, survival, abundance, and movement of juvenile Chinook Salmon throughout the river.

This research will focus on utilizing eDNA to develop a quantitative method for estimating juvenile Chinook salmon abundance in the Sacramento River. We will be looking at the correlation between eDNA concentrations and juvenile out-migrating trap abundances at the Red Bluff Diversion Dam site. Ideally, out of the four run types of Chinook salmon in the Sacramento River the focus will be on the spring and winter run types. In addition to the correlation between eDNA concentrations and abundance, we will examine if these eDNA abundances estimates are a function of environmental covariates (i.e. temperature, flow, turbidity, etc).