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  • Title

    Monitoring and Evaluation of the North Delta Food Subsidies and Colusa Basin Drain Study

    Lead California Department of Water Resource [DWR]
    Description The North Delta Food Subsidies – Colusa Basin Drain Study monitors and evaluates the effects of the North Delta Flow Action on the Delta food web.
    Science topics Delta Smelt, Fish, Flows, Water management
    Updated November 17, 2022
  • Title

    Directed Outflow Project

    Lead U.S. Bureau of Reclamation [USBR]
    Description The U.S. Bureau of Reclamation (USBR) and California Department of Water Resources (DWR), along with collaborators, are continuing efforts to evaluate the hypothesized benefits of outflow and outflow alteration for Delta Smelt. The collective aim of these efforts is to better inform management actions that will bolster and stabilize the Delta Smelt population. The planned five-year Directed Outflow Project (DOP) seeks to assist in evaluating the overarching hypothesis that habitat quality and quantity is improved in the summer/fall when X2 is below 81 km and the LSZ occurs in Suisun Bay and Marsh, and this improvement in habitat conditions will translate into a greater catch density, health, and growth for Delta Smelt using this area
    Science topics Delta Smelt, Fish, Flows, Water management
    Updated November 17, 2022
  • Title

    A Multi-Stock Population Dynamics Framework for the Recovery of Sacramento River Chinook Salmon

    Lead University of Washington [UW]
    Description The purpose of this project is to construct a multi-stock salmon population model and management strategy evaluation (MSE) tool that addresses the cross-linkages between water use and fishery ecosystem response. Recent federal court judgment concluded that insufficient evidence was provided for prescribing specific flow restrictions in two recent conservation measures. The inability to provide adequate evidence was a byproduct of not having the correct quantitative tools at hand. We propose to build these tools by furthering technological developments of previous analyses of Central Valley Chinook population dynamics. Specifically, our work will integrate multiple salmon populations together into a single model that can reconstruct historical population dynamics such that environmental conditions and water resource use can be used as predictors of biological responses of multiple populations. Our goal is to integrate populations into a single model so that the effect of water management and fishery management policies can be examined in light of all fish populations simultaneously. This pertains to the biological interactions between the populations as well as the way in which fisheries impact individual populations depending on growth and maturation rate of each population. All analysis will be framed in the context of historical and proposed water use patterns.
    Science topics Flows
    Updated April 29, 2022
  • Title

    North Delta Flow Action: Role of Improved Yolo Bypass Flows on Delta Food Web Dynamics

    Lead California Department of Water Resource [DWR]
    Description Description In a collaborative effort between CA Department of Water Resources, US Bureau of Reclamation, CA Department of Fish and Wildlife, United States Geological Survey, San Francisco State University, and UC Davis, this study will investigate the role of augmented summer and fall flows in the Yolo Bypass and North Delta areas on lower trophic food web dynamics and the benefits to listed fish species. Using both continuous and discrete sampling approaches, this study will relate hydrologic patterns to chlorophyll-a, nutrients and primary productivity, plankton densities and composition (phytoplankton and zooplankton), contaminant concentrations, as well as water quality parameters such as electrical conductivity, turbidity, temperature, and dissolved oxygen. In addition, caged hatchery Delta Smelt will be monitored to determine the effects of the managed flow action and increased food web productivity on fish survival, growth, and behavior. Need Due to the food-limited nature of the San Francisco Estuary, it is critical to understand mechanisms that result in successful food web productivity including phytoplankton blooms. Food limitation is one of the primary hypothesized causes of the Pelagic Organism Decline. In 2011 and 2012 there was evidence that a moderate Yolo Bypass flow pulse during fall agricultural drainage periods was followed by phytoplankton blooms in the lower Sacramento River. Managed flow actions in the following years showed an increase in food web productivity could be repeated;however, results varied across years and flow actions indicating more research is warranted to understand correlations between flow and abiotic conditions, and the biological response of the food web. The increases of summer/fall flows in North Delta, has been considered a management strategy as part of complying with USFWS Delta Smelt Biological Opinion Action 4. The augmentation of flows through the Yolo Bypass/North Delta is also included as one of several Delta Smelt Resiliency Strategies by Natural Resources Agency. Objectives • Determine if managed flow actions through the Yolo Bypass stimulate increased primary productivity locally and downstream, and if it is repeatable. • Characterize how nutrients, chlorophyll and plankton (composition and density) in the Toe Drain, Cache Slough Complex, and lower Sacramento River change in response to flow pulses. • Determine if nutrient subsidies of the source water and downstream are limited by abiotic and biotic factors. • Characterize spatial differences and transport of pesticide contaminants in the Yolo Bypass in response to the flow actions. • Determine survival, growth and behavior of caged hatchery Delta Smelt before and after the flow action in the Yolo Bypass.
    Science topics Flows, Water management
    Updated April 29, 2022
  • Title

    Directed Outflow Project [DOP] - Paired Habitat Sampling

    Lead U.S. Bureau of Reclamation [USBR]
    Description Special study supporting water quality, food web, and biological measures regarding seasonal outflow and Delta Smelt.
    Science topics Flows, Water management
    Updated April 29, 2022
  • Title

    Examining the relationship between Longfin Smelt and flow in the San Francisco Bay Delta

    Lead University of California - Berkeley [UC Berkeley]
    Description The overarching goal of this study is to investigate the time-varying effects of flow variation and food availability on longfin smelt population dynamics, via advanced modeling of a diverse set of environmental and ecological monitoring time series. Specifically, this project will:(1) Assess how key environmental drivers (flow, salinity, temperature) have changed over the past 5 decades (1967 to present) across the San Francisco Estuary (SFE); (2) Examine how longfin smelt population dynamics have changed over that time period, and whether/when breakpoints in abundance and trends exist (e.g., periods of 'decline' vs' stability'); (3) Quantify the effects of environmental on driving observed fluctuations in longfin smelt dynamics; (4) Determine whether/how environment-smelt relationships have changed in magnitude or sign over time; and if they changed, whether such changes have been spatially consistent across the SFE. These goals will inform ongoing conservation efforts of longfin smelt by determining the combinations of flow, habitat, and prey availability conditions that lead to stable population dynamics for the species.
    Science topics Fish, Flows, Longfin Smelt, Zooplankton
    Updated May 8, 2024
  • Title

    Impacts of predation and habitat on Central Valley Chinook smolt survival

    Lead University of Vermont, USGS Vermont Cooperative Fish and Wildlife Research Unit
    Description The Sacramento River in California’s Central Valley has been highly modified over the past 150 years due to mining, urbanization, and impoundment/diversion of river flow to provide water for municipal, industrial, and agricultural needs. Land use changes combined with high levels of harvest have been accompanied by drastic declines in native salmon populations, including the once abundant Chinook salmon (Oncorhynchus tshawytscha). Further, the region has been subject to the introduction and widespread establishment of non-native fish species, some of which are predators of juvenile salmon. Of the four historic ecotypes of Chinook salmon (fall, late-fall, winter, and spring runs), winter- and spring-runs have been most impacted and are currently listed as endangered and threatened respectively under the US Endangered Species act. Past research has illustrated how smoltification of juvenile salmon and outmigration from freshwater to the ocean is a time of increased mortality, and reduced survival at this life stage can impact the number of reproducing adults returning to the system in subsequent years. While these studies have provided valuable information on how habitat and environmental conditions experienced by migrating Chinook salmon smolts can affect survival, they have primarily focused on individual ecotypes during the portion of the year where downstream migrations occur. However, variation in smolt size and migration timing among ecotypes can expose migrating fish to differing environmental conditions and levels of exposure to predation, which can present distinct risks for outmigration survival. To identify the areas and environmental conditions which have the greatest relative impact on juvenile survival for each ecotype, this project will use over ten years of data (2012-2022) from acoustically tagged smolts representing all four Chinook salmon ecotypes in the Sacramento River/Central Valley. Combining these data will increase sample size relative to previous studies, the range of environmental conditions (e.g., temperature, flow, and predator abundance) modeled, the range of fish sizes, and thus, the statistical power of our analyses. We hypothesize that each ecotype will have different factors that will be the primary drivers of mortality experienced during outmigration. To test our hypotheses, we will implement Cormack-Jolly-Seber (CJS) mark-recapture models to estimate both the probability of survival through reaches of the Sacramento River delineated by acoustic receivers, and the detection probability in each reach. Survival will be modeled as a function of individual, release group, reach-specific, and time-varying covariates. Further, to examine the relative impact of predation on smolt survival, we will include an additional covariate representing predator-prey encounter rates using the Mean Free-path Length model. Finally, model selection will be applied to a series of CJS models to assess the relative impact of each covariate on smolt survival for each of the four Chinook ecotypes.
    Science topics Chinook Salmon, Environmental drivers, Fish, Flows, Habitat, Predation, Salmon migration, Water temperature
    Updated February 2, 2024
  • Title

    White Sturgeon Telemetry Synthesis

    Lead Cramer Fish Sciences
    Description Acoustic telemetry studies are expensive and logistically demanding. A new study to tag and monitor 315 White Sturgeon would require a massive field effort by a large team, but by pooling and leveraging existing datasets, this sample size and analysis will be achieved at a fraction of the cost and effort. In recognition of the efficiencies gained by this approach, the Delta Stewardship Council’s Science Program lists the synthesis and analysis of existing telemetry datasets in Science Action Area (SAA) 2. This project directly addresses SAA 2 by capitalizing on existing White Sturgeon telemetry data through the synthesis of three existing large telemetry dataset to understand system-wide White Sturgeon movements. This contract will synthesize existing long-term acoustic telemetry datasets in order to address high priority research questions for the management of White Sturgeon in the San Francisco Estuary system. These questions include: 1. What is the periodicity of spawning migrations by tagged White Sturgeon, and how do these estimates compare to those from previous, single-basin studies? 2. What is the scope and variability of inter-basin movements exhibited by tagged adult White Sturgeon across years? 3. Is there individual fidelity to specific migration routes or sites within each river basin? 4. Do White Sturgeon migrating through the Yolo Bypass experience delays in reaching spawning grounds relative to fish using the mainstem Sacramento River or San Joaquin River routes? 5. Is the onset of upstream migration movement by individuals associated with a characteristic flow rate or event? This contract will serve as a model for future telemetry synthesis studies by adhering to best practices in scientific computing for reproducible, transparent research, and by making all parts of the data and analysis accessible to the broader Delta research community.
    Science topics Environmental drivers, Fish, Flows, White Sturgeon
    Updated May 21, 2024
  • Title

    Continuous Flow and Water Quality Monitoring Network in the Sacramento-San Joaquin Delta

    Lead U.S. Geological Survey [USGS]
    Description This project envisions the continuation, expansion, and further integration of high frequency monitoring for flow, water quality (including chlorophyll and nutrients), sediment, as well as biological responses at key locations in the Delta and Suisun Bay. The physical properties monitored by the fixed-station network are the primary drivers of the habitat conditions and biological responses that management actions hope to achieve. Nutrient dynamics are explicitly measured at select stations to improve our understanding of how physical dynamics, water quality and landscape features shape the base of Delta food webs. These data will provide information about drivers linked to food quantity and quality as well as potential toxins production by harmful algae. Suspended-sediment monitoring provides an understanding of the inputs and internal exchanges between regions, locations of sources and sinks, and provides insight into the underlying cause of turbidity variability in the study area. Suspended-sediment measurements gage the availability of suspended sediment for existing marshes and for proposed large-scale marsh restoration efforts in the Delta. There are a total of 5 sub-tasks in this project: • Task 1: Hydrodynamics Team – Fixed Station Network Operation and Maintenance • Task 2: BioGeoChemistry Team -- Fixed Station Network Operation and Maintenance • Task 3: Delta Sediment Team – Fixed Station Network Operation and Maintenance • Task 4: Bay Sediment Team – Fixed Station Network Operation and Maintenance • Task 5: Project Management
    Science topics Chlorophyll A / B, Conductivity, Dissolved oxygen, Flows, Nutrients, pH, Phytoplankton, Sediments, Stage, Surface water / flow, Tides, Turbidity, Velocity, Water operations / exports, Water temperature
    Updated January 19, 2024