The Sacramento River and its tributaries serve as critical habitat for the green sturgeon, listed as federally threatened due to its declining population and the impacts of anthropogenic activities such as dam operations and water extraction. We currently lack an understanding of the relationship between flow regimes and sturgeon migration, which is essential for developing effective management strategies to support the species' conservation and for required analysis under state and federal law. By modeling this relationship, this project will contribute to more informed water management, leading to fewer litigation risks for agencies and better outcomes for sturgeon.
This project will model the effects of flow regimes on adult Southern Distinct Population Segment (sDPS) green sturgeon migration within the Sacramento River basin to enhance sturgeon conservation and water management. Specifically, the research will model how flows and temperature affect adult green sturgeon spawning migration. The model will be used to forecast sturgeon movements under various flow scenarios, and the model, the results, and an explanation of their significance will be widely distributed via a website (with a publicly accessible modeling app), a policy brief, a public workshop, and other outreach.
We propose to use a unique toolbox combining genetic and isotopic markers to 1) Assess the genetic diversity of Central Valley spring-run Chinook salmon (Oncorhynchus tshawytscha; CVSC), 2) Identify the juvenile life history diversity and the importance of natal versus non-natal and in-channel versus off-channel habitats, 3) Evaluate the connection between genetic diversity and the expression of life history diversity in each CVSC population, and 4) Investigate the response and resilience of CVSC populations, with various levels of genetic and phenotypic diversity, to changes in habitats and environmental conditions such as droughts and floodplain reconnection.
We will combine otolith, eye lens, and genetic tools to study the phenotypic diversity and genetic origins of returning adult spawners from spring-run Chinook Salmon spawning grounds across the entire ESU in 2024 and 2025. All individuals will first be assigned to their run type using genome wide sequencing and newly developed SHERLOCK methods. Otolith and eye lens isotope methods will then be used to characterize the juvenile migratory strategy diversity, rearing habitat use, natal origin and adult age structure of each CVSC population. These data will be synthesized to evaluate the resilience of CVSC populations with various biocomplexity levels to a changing climate and landscape.
Spring-run Chinook salmon (Oncorhynchus tshawytscha) are a high-priority species under the Endangered Species Act due to their risk of extinction. However, understanding the factors affecting their populations is difficult when monitoring focuses only on returning adult spawners. This limited view overlooks critical life stages. To address this gap, the project aimed to estimate the number of juvenile salmon leaving the Delta at Chipps Island. Monitoring salmon throughout their entire life cycle is essential for identifying the key factors influencing their survival and reproduction.
There is a need from both scientists and managers for accurate data to make informed decisions about salmon protection and conservation. The Department of Water Resources (DWR) mandates that juvenile production estimates for spring-run salmon be included in their incidental take permit, which is necessary for the continued operation of the State Water Project. A method to estimate juvenile abundance of spring-run salmon leaving the Delta (at Chipps Island) did not yet exist.
To develop these annual estimates, researchers built on previous studies and incorporated new genetic data into updated models. This approach maximized the use of available information and the latest genetic research to improve the protection and understanding of these threatened fish.
