California experienced a series of severe droughts from the years 2012-2015, and is predicted to be one of the most water scarce regions in the world as climate change progresses. This extreme variability in water quality and quantity presents unique challenges for the federally listed Central Valley Chinook Salmon (Oncorhynchus tshawytscha), which uses the limited floodplain in the Central Valley as rearing habitat. These floodplains, such as the Yolo Bypass, a highly managed floodplain on the Sacramento River, can be disproportionately affected by drought and stream flow changes, in turn affecting the fitness of Chinook salmon that depend on the floodplain during rearing and outmigration.
We are interested in understanding how different water years (drought versus flood) influence the run composition and abundance of juvenile Chinook salmon in the floodplain (Yolo Bypass) versus the mainstem of the Sacramento River.
In collaboration with the CA Dept. of Water Resources and US Fish and Wildlife Service, we are sampling juvenile Chinook from the Yolo Bypass and areas along the Sacramento River to evaluate habitat use over time. We are genotyping these samples with an innovative SNP panel (Meek et al. 2016) to identify individuals to the run level (Fall, Late Fall, Winter, and Spring).
Our main questions with this study are:
- Do the different runs of Chinook salmon use the floodplain versus mainstem habitat differentially?
- How does this habitat use change with environmental condition (drought versus flood years)?
This study will help us answer important questions about the impact of water conditions on the different runs of Chinook. It will also provide important information on the loss of genetic diversity due to environmental or anthropogenic changes in the Sacramento River. Chinook are of enormous economic, cultural, and ecological value in California, making a better understanding of how these changes are affecting this species of particular importance. This research will be able to inform critical water management policies to best protect this ESA-listed species.