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.
Pesticide mixtures originating from both legacy and current-use chemicals are widely detected in Delta waters, sediments, and invertebrate prey, posing potential risks to juvenile Chinook Salmon during critical rearing periods. While pesticides have been measured in juvenile salmon and their prey, substantial uncertainty remains regarding how mixtures of contaminants affect fish behavior and physiology, and how these effects vary across space and time within the Delta. This science activity will apply a recently developed response spectrum modeling framework to evaluate spatial and temporal patterns of sublethal pesticide effects on juvenile Chinook Salmon rearing in the Delta. The model integrates pesticide concentrations measured in salmon tissues to predict behavioral and physiological impairment associated with complex pesticide mixtures. Juvenile fall-run Chinook Salmon collected through existing Delta monitoring programs, including archived specimens from prior years, will be analyzed alongside hatchery-origin juveniles deployed in cages at multiple Delta locations. This combined approach will allow assessment of how pesticide bioaccumulation and model-predicted effects vary across habitats, seasons, and hydrologic conditions. Results will provide a predictive assessment of where and when pesticide mixtures are most likely to impair juvenile salmon performance, with implications for growth, survival, and population-level outcomes. The activity will support management decisions related to pesticide regulation, TMDL development, and evaluation of habitat restoration actions, including reconnected floodplain rearing habitats. In addition, spatial patterns of pesticide bioaccumulation may help identify contaminant sources and inform targeted remediation strategies.
Since 2015, the DIISC Team has organized a biennial Delta Invasive Species Symposium. The symposium is a forum for Delta managers, researchers, and decision-makers to meet, share and synthesize information, and communicate best practices and lessons learned. https://deltaconservancy.ca.gov/diisc-team-activities/
This guide is intended to give land managers an introduction to managing invasive aquatic vegetation (IAV) in tidal wetland habitats, whether the site is established, has been recently restored, or tidal reconnection will soon occur. It addresses submerged aquatic vegetation (SAV), floating aquatic vegetation (FAV), and emergent aquatic vegetation (EAV). It compiles knowledge from land managers in the Delta and members of the Delta Interagency Invasive Species Coordination Team (DIISCT), whose purpose is to foster communication and collaboration among California state agencies, federal agencies, research and conservation groups, and other interested parties that detect, prevent, and manage invasive species and restore invaded habitats in the Delta. The authors hope this guide functions like asking an experienced colleague for recommendations as you start to consider your site’s IAV management. https://deltaconservancy.ca.gov/iav-quick-start-guide/
Preventing the establishment of new invasive species through early detection and rapid response (EDRR) is the most effective and efficient way to limit the negative impacts of invasive species on the Delta. In 2021, the DIISC Team lead a review of the different EDRR resources in the Delta and drafted an EDRR coordination table.
This project examined cold water storage and regulation in Shasta Lake through the Shasta Dam Temperature Control Device (TCD). The TCD is a 300-foot structure with multiple gate openings, allowing water from different depths - and thus different temperatures - to be selectively released to manage water temperature in the river downstream. River water temperature is managed to support the imperiled Chinook salmon, a species of fish that is native to California. This capability is becoming increasingly important because low water years generally mean warmer river water temperatures that compromise habitat suitability for different species. In particular, cold pool management is essential for downstream spawning and rearing habitat for winter-run Chinook salmon that rely on cooler water temperatures to survive and reproduce. When the water is too warm, oxygen availability is limited for Chinook salmon and their eggs, which contributes to their mortality. Although the TCD allows reservoir managers to control water release and downstream water temperature, flow contributions into the TCD under day-to-day operations for different gate openings, operations, and thermal conditions within the reservoir are largely unquantified. Further complicating temperature management, TCD leakage (whether within the structure itself or through malfunctioning gates) needs to be better quantified in location and magnitude. This information will improve operational strategies for cold water performance especially during summer and fall months to manage cold water supply for downstream Chinook salmon habitat.
