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  • Title

    Predation Dynamics Across Reach-Specific Gradients in Juvenile Salmon Survival

    Lead U.S. Geological Survey [USGS]
    Description Description The overarching goal of this project is to determine if predation by piscivorous fishes is an important explanatory driver of survival of juvenile Chinook Salmon emigrating through the north Delta. To achieve this goal, we seek to determine if variation in reach-specific characteristics of predation dynamics covary with survival of acoustictagged juvenile Chinook Salmon collected during the study period. This will be accomplished by comparing reach-specific characteristics of the piscivore community and its observed and modeled consumption of juvenile Chinook Salmon across a range of environmental conditions. Need This is not a mandated study but it addresses an important research need. Objectives • How does the piscivore community (species composition, size structure, and abundance) vary across specific migratory pathways (river reaches) in the North Delta? • To what extent do environmental conditions (e.g., water temperature, turbidity, and discharge) control the consumption of juvenile Chinook Salmon? • Do characteristics of the predator community explain variation in survival of acoustic tagged salmon collected during the study period?
    Science topics Predation
    Updated April 29, 2022
  • Title

    Extracting Better Information from Long-Term Monitoring Data: Estimating Occupancy and Abundance of Near-Shore Fishes in the Sacramento-San Joaquin River Delta

    Lead U.S. Fish and Wildlife Service [USFWS]
    Description

    Description The purpose of this study is to expand IEP monitoring and inference to other dominant near-shore, littoral habitats not sampled by beach seines through the use of boat electrofishing. To accomplish this we will sample key littoral fish species across various near-shore habitats in order to determine how best to estimate abundance, occupancy, capture probabilities, and related environmental drivers. Need Expanding DJFMP sampling to other habitats throughout the Delta will allow our program to detect and monitor fishes and ecological trends through time, alleviating a recognized data gap. Current sampling relies on data collected through non-random fixed point sampling of unobstructed habitats, which limits the utility of our data to inform management decision. Objectives • Design boat electrofishing survey methods to expand DJFMP’s monitoring into habitats and locations not sampled by beach seining. • Design and develop field and data analysis methods for estimating capture probability and abundance using boat electrofishing techniques. • Predict spatio-temporal distribution of habitats occupied by key littoral species.

    Science topics Habitat
    Updated April 24, 2025
  • 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 4 teams associated with this work: • Hydrodynamics Team – Fixed Station Network Operation and Maintenance (Flow, Velocity, Gage Height, Core WQ) • BioGeoChemistry Team -- Fixed Station Network Operation and Maintenance (Expanded WQ, Nutrients, Phytoplankton) • Delta Sediment Team – Fixed Station Network Operation and Maintenance (Suspended Sediment, Delta) • Bay Team – Fixed Station Network Operation and Maintenance (Suspended Sediment and WQ in SF Bay)
    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 May 22, 2025