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  • 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

    Fish Diet and Condition

    Lead California Department of Fish and Wildlife [CDFW]
    Description Description The Diet and Condition study has provided information on the food habits of pelagic fishes in the estuary since 2005. We focus on the temporal and spatial differences in diet composition and feeding success of Delta Smelt, Striped Bass, Threadfin Shad, Longfin Smelt, Mississippi Silversides, and American Shad. Need Data from this project has been used to inform the Fall Low Salinity Habitat Program (FLaSH), Directed Outflow Project (DOP), and Management, Analysis and Synthesis Team reports, as well as life history models used for the conservation of fish and their habitats. Understanding what prey are utilized for food in the context of available prey, with the associated body-condition of fish, helps clarify the existence and timing of food limitation for young pelagic fish in the estuary. This work began as part of the Pelagic Organism Decline investigations and continued as a contributor to FLaSH investigations during which we in collaborated with the Fish Health Monitoring Project. Recently staff completed Longfin Smelt diet investigations as part element #296 (Longfin Smelt Investigations – in response to a litigation agreement) that will also contribute to the Longfin Smelt Conceptual Model and Synthesis effort (element #320). Finally, we will process Delta Smelt diets from investigations prompted by the Delta Smelt Resilience Strategy, and as part of the DOP. Objectives 1. What are the diets of pelagic fishes (especially Delta Smelt and Longfin Smelt) in the estuary and do they vary regionally or temporally? 2. Is there evidence of reduced feeding success spatially or temporally in the estuary? 3. Is feeding success associated with changes in relative weight or condition of fish? 4. Is there seasonal and regional overlap of diets between species (with a focus on age-0 Delta Smelt, Longfin Smelt, Striped Bass, Prickly Sculpin, Pacific Herring, and Threadfin Shad)?
    Science topics None specified
    Updated April 29, 2022
  • Title

    Aquatic Habitat Sampling Platform: Standardized Fish Community Sampling Across Habitat Types

    Lead U.S. Bureau of Reclamation [USBR]
    Description Description The Aquatic Habitat Sampling Platform (AHSP) is an integrated aquatic species and habitat sampling system that can effectively monitor aquatic organisms and reveal habitat associations while having minimal or no “take” of sensitive species. Further development and deployment of the AHSP will expand data collection to shallow and off-channel habitat, while offering the capability to transition to deeper and open water habitats, providing reliable sampling efficiency estimates (e.g., probability fish detection) and “catch” per unit effort (i.e., number of individual species per volume of water sampled) and improving our knowledge about populations, habitat associations and major stressors of key organisms within the San Francisco Estuary (Estuary). Need Within the Estuary, numerous monitoring techniques are used. However, monitoring weaknesses for determining fish status and trends include: 1) restricted locations available for some techniques;2) limited ability to simultaneously assess zooplankton and fish larvae;and 3) difficulty in estimating fish population size due to lack of gear efficiency information (Honey et al. 2004). Furthermore, past attempts at integrated abundance indices from more than one sampling method have had limited success. Although there continues to be considerable collaborative monitoring and research devoted to understanding Central Valley fish species, coordination among activities has been difficult. Other issues include permitting take of listed species and time-consuming monitoring with extended periods of down time due to sample post-processing of fish and invertebrate species. Identification of key microhabitats for each lifestage and attributes and linking associated physical parameters such as habitat features (e.g., depth, structure, channel type) and water quality is needed. Objectives • Test AHSP operation within the Estuary while providing information highly relevant to pressing Delta management issues (IEP 2016); • Provide detailed information on distribution and approximate abundance of adult Delta Smelt within identified habitat types (Biological Opinion on the Long-Term Operational Criteria and Plan for coordination of the Central Valley Project and State Water Project;https://www.fws.gov/sfbaydelta/documents/SWPCVP_OPs_BO_12-15_final_OCR.pdf);and • Assess habitat associations and diurnal behavior of Delta Smelt and other fishes (Durand 2015).
    Science topics Delta Smelt
    Updated April 29, 2022
  • Title

    Central Valley Salmonid Coordinated Genetic Monitoring [Year 4]

    Lead U.S. Bureau of Reclamation [USBR]
    Description Description This work will include tasks to rapidly identify winter-run Chinook juvenile salmon at the CVP/SWP salvage facilities, process juvenile salmonid tissues from various CVPIA and IEP fish monitoring stations, and support coordination of genetic monitoring across the CVP and SJRRP programs. PIs: Josh Israel (USBR);Scott Blankenship (Cramer Fish Science);Ken Bannister (USFWS);John Carlos Garza (NOAA-Fisheries);Brett Harvey (DWR);Noble Hendrix (QEDA);Rachel Johnson (NOAA-Fisheries);Mariah Meek (UC Davis);Kevin Reece (DWR) Need This study is needed due to the limited accuracy of Lenght at Date stock identification. Inaccurate identification of Chinook salmon is problematic because it compromises the management value of data collected from standard monitoring programs. This project will improve the science and management value of the Central Valley salmon monitoring network, supported through IEP and Central Valley Project Improvement Act (CVPIA) monitoring stations, by accurately determining stock identification of multiple Chinook salmon stocks across their distribution. Classification tables will be developed to characterize monthly and seasonal accuracy between length-at-date and genetic race assignment at IEP and BiOp monitoring locations. This multi-year dataset will be used to evaluate the likelihood of accurate assignment and potential biophysical explanatory variables influencing genetic accuracy. Objectives Improve accuracy of CVPIA and IEP monitoring programs by providing genetic stock identification information for tissues collected from Red Bluff, Knights Landing, DJFMP, salvage facilities and San Joaquin River fish monitoring stations. Samples will be collected from all four runs of Chinook salmon based on length-at-date (i.e., samples will be collected from Chinook of various sizes throughout the sampling period).
    Science topics Chinook Salmon
    Updated April 29, 2022
  • Title

    Enhanced Acoustic Tagging, Analysis, and Real-Time Monitoring

    Lead National Oceanic and Atmospheric Administration [NOAA]
    Description Description This project tracks the movement and survival of wild and hatchery juvenile Chinook salmon with a large acoustic receiver network (JSATS), including real-time receivers, and the development of real-time metrics and retrospective modeling of juvenile salmon migration data. Need There is a well-documented need for improved detection and associated modeling of salmon migration and survival in the Central Valley. Understanding salmon survival and movement dynamics in the Delta and its tributaries is critical to the operation of state and federal water projects, recovery of ESA-listed species, and sport and commercial fisheries management. Objectives • Maintain 20 real-time JSATS receivers: will provide information on migrating salmon smolt location and timing of Delta entry and exist, which is key for informing time-sensitive decisions • Deployment of autonomous JSATS receiver array: this will provide fine-scale reach-specific survival and movement rates • Development of new metrics for the real-time data: this will inform key management relevant questions, such how many fish are entrained at critical junctions • Development of real-time website to convey movement and survival rates of acoustic tagged juvenile salmonids at various real-time locations in the Sacramento River and Delta.
    Science topics Salmon migration
    Updated April 29, 2022
  • Title

    Suisun Marsh Salinity Control Gate Study

    Lead California Department of Water Resource [DWR]
    Description Description Suisun Bay and Marsh are a key part of the habitat for Delta Smelt, but during drier periods such as summer, Delta Smelt may be at least partially excluded from Suisun Marsh due to high salinities. The purpose of this proposal is to provide scientific support a management action for Smelt, operation of the Suisun Marsh Salinity Control Gates (SMSCG). This facility is currently to tidally pump water into the Marsh to improve fall and winter habitat conditions for waterfowl, but could also provide a tool to manage aquatic habitat for Delta Smelt in other periods. Specifically, by using the SMSCG to direct more fresh water in Suisun Marsh, our prediction is that reduced salinities will improve habitat conditions for Delta Smelt in the region. Need The status of Delta Smelt is dire. As part of the Resources Agency's Delta Smelt Resiliency Strategy, in August 2018 we conducted pilot operations of the SMSCG to support Delta Smelt , with promising results. Based on this early success, we expect that the SMSCG will be used as a seasonal tool to support Delta Smelt in summer-fall in coming years as part of the coming FWS Biological Opinion and DFW ITP. Neither has been completed, but SMSCG operations for fish are expected to be required in each. Hence, the proposed study is intended to provide a scientific evaluation and guidance for an expected SMSCG action in 2020. Objectives The primary objective of this project is to evaluate the effectiveness of the SMSCG action. Questions to be addressed include: • Did the action improve habitat conditions for Delta Smelt in the Suisun Region? • Does the Suisun Region typically have better habitat and food web conditions than the upstream River Region? • Do Delta Smelt respond favorably to the SMSCG flow action? • Does operation of the SMSCG affect other fishes and clams?
    Science topics Salinity
    Updated April 29, 2022
  • Title

    Physiological and Behavioral Effects of Domestication on Delta Smelt

    Lead California Department of Water Resource [DWR]
    Description Description Due to the continued population decline of Delta Smelt and the threat of extinction, conservation efforts may include future supplementation practices using the refuge population of Delta Smelt at the Fish Conservation and Culture Laboratory (FCCL) in Byron, CA to assist in maintaining the wild population. Prior to any supplementation planning, it is first critical to determine if Delta Smelt with varying levels of domestication indices (i.e. level of hatchery ancestry) respond differently, both physiologically and behaviorally, to various habitat conditions. This project aims to provide a better understanding of the effects of domestication on captive Delta Smelt (Hypomesus transpacificus) by assessing the refuge population at the FCCL. Three studies will be conducted exploring if domestication index (i.e. the level of hatchery ancestry) affects the physiological and behavioral performance of Delta Smelt in response to physical handling and climate change stressors. Need Physiological and behavioral changes of hatchery fish due to domestication could lead to unintended detrimental effects in the wild;therefore, research characterizing the alterations of hatchery Delta Smelt across levels of domestication indices are warranted to understand the effects of captivity and how they might shape future supplementation and conservation strategies. For example, identification of differences among groups of Delta Smelt with varied domestication index may create the need for domestication management and the implementation of altered hatchery practices. This project will provide relevant and timely information for conservation managers and adaptive restoration strategies and dovetail with the recommendations from the 2017 Delta Smelt Supplementation Workshop. As such, this study is included in the supplementation studies work plan which came out of that workshop. Specifically, this project fits within two topics in the IEP Science Strategy: Effects of Climate Change and Extreme Events and Restoring Native Species and Communities. Objectives 1. To characterize domestication effects on hatchery Delta Smelt by synthesizing existing/historical datasets on growth and reproduction of fish at the FCCL since the start of the hatchery program. 2. To identify the impacts of domestication index on the physiological stress response of Delta Smelt following handling stress. 3. To determine the effects of domestication index on individual and group swimming behavior, responses to predation, and responses within the context of climate change factors including warming and increased salinity.
    Science topics Delta Smelt
    Updated June 13, 2024
  • Title

    Developing an eDNA metabarcoding protocol to improve fish and mussel monitoring in the San Francisco Estuary

    Lead National Oceanic and Atmospheric Administration [NOAA]
    Description Description We propose to develop an eDNA metabarcoding protocol to complement existing IEP monitoring surveys and assess the effects of management activities such as habitat restoration or flow alteration. We will develop a reference sequence database for native and invasive fish, mussels, and other macroinvertebrates present in the San Francisco Estuary (SFE). We will optimize a molecular and computational pipeline for metabarcoding and ground truth the method against three SFE monitoring efforts, each using different sampling gear. We will investigate the relationship between eDNA sequence read count and fish biomass or abundance (EDSM survey). Finally, we will determine the ability of metabarcoding to detect fish and macroinvertebrate assemblages across large and small spatial scales and over time. Need Our overarching goal is to develop a non-invasive, low cost monitoring tool that can be used in conjunction with existing IEP monitoring programs or used alone to assess biological community composition at locations of interest in the SFE. This proposal is related to the 2020 – 2024 IEP Science Strategy by creating a new monitoring tool that can assist in two main areas: 1) Restoring Bay-Delta native fishes and community interactions and 2) assessing effects of flow alteration on Bay-delta aquatic resources. Broadly, this study will inform management decisions by supporting and augmenting existing monitoring surveys in the SFE. It will also lead to a richer and more complete understanding of SFE ecology. This study is not explicitly required by law or agreement, and to our knowledge is neither a recommended action nor a result from an IEP review or synthesis effort. Objectives Objective 1: Develop robust molecular methods and a computational pipeline for detection of SFE fish and macroinvertebrates by eDNA metabarcoding of water samples. Objective 2: Compare eDNA metabarcoding head-to-head with existing and historical monitoring data from three ongoing ecological surveys using diverse conventional sampling gear and evaluate accuracy of fish abundance and biomass estimates from eDNA metabarcoding data. Objective 3: Evaluate factors that influence eDNA detection of species of interest (e.g. rare or invasive species) and suites of species (e.g. benthic fishes and invertebrates) on two spatial scales, within and between habitats, along with temporal variation.
    Science topics Fish
    Updated April 29, 2022
  • 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

    Directed Field Collections

    Lead California Department of Fish and Wildlife [CDFW]
    Description Description The Direct Field Collections element (-089) provides funding support for expanded field collections, allowing CDFW to provide other, IEP-approved researchers access to research-capable boats and experienced operators, and thus the ability to safely sample the upper San Francisco Estuary. This element most recently facilitated investigations associated with the Fall Low Salinity Habitat (FLaSH) project and the Directed Outflow Project (DOP). Need This element allows CDFW and thus IEP to provide boat and operator time to assist collaborating researchers leading approved IEP projects with “on-the-water” sampling. There is no mandate for this element. Objectives To provide CDFW operational flexibility to assist collaborating researchers leading approved IEP projects with access to CDFW boat operators and boats to complete "onthe-water" sampling.
    Science topics None specified
    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 June 13, 2024
  • Title

    Estimating Abundance of Juvenile Winter-run Chinook Salmon Entering and Exiting the Delta [SAIL]

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

    Description This is a continuation of a five year project funded by CDWR and CDFW and the Central Valley Project Improvement Act in 2017. The objective of the project is to improve estimates of population abundances for fall, winter and spring run juvenile Chinook Salmon at Sacramento and Chipps Island by improving efficiency estimates using data from releases of coded wire tags (CWT), acoustic tags (AT), and by genetically sampling the trawl catch in 2018. The project will (1) develop statistical models for estimating trawl efficiencies using 2016-2018 data for paired AT-CWT releases of winter run and fall-run Chinook Salmon;(2) use 2018 genetic sampling of trawl catch in combination with efficiency estimates to estimate population abundances of fall, spring and winter run at Sacramento and Chipps Island in 2018;(3) implement trawl efficiency studies for multiple salmon runs in 2018 informed by the 2016 and 2017 results and in coordination with hatcheries for inclusion of AT fish with existing CWT releases;and (4) combine trawl efficiencies with genetic samples of trawl catch to provide estimates of fall, spring and winter-run salmon abundance (with estimated precision) entering and exiting the Delta in 2018. Need There is growing appreciation that a salmon monitoring network that could quantitative estimates of abundance is desirable to improve our knowledge and resolution of life stage success and movement across the landscape (Salmon SAIL conceptual models 2016). Objectives (1) Estimate the population-level status and trends for winter run;and status of spring and fall run;(2) evaluate production estimates for juvenile winter-run Chinook Salmon entering the Delta used in water project take development;(3) provide estimates of winter and fall run-specific freshwater cohort strength to support ocean harvest management decisions;(4) establish a time series of winter, spring and fall run-specific production estimates at key locations for incorporation into life cycle models.
    Science topics Chinook Salmon
    Updated April 24, 2025
  • Title

    Reconstructing Juvenile Salmon Growth, Condition, and Delta Habitat Use in 2014-15 Drought and Beyond [SAIL]

    Lead University of California - Davis [UC Davis]
    Description Description Life history diversity buffers salmon populations over space (e.g. the use of natal and non-natal rearing habitats and time (e.g. variable migration timing resulting in greater probability of meeting optimal ocean conditions). Historically the Sacramento-San Joaquin Delta provided critical salmon rearing habitat, but urban expansion, water diversions and species introductions have resulted in inhospitable conditions unlikely to meet rearing needs. This study fills critical data gaps regarding Delta rearing by juvenile Chinook salmon – primarily to determine the annual migrant portfolio (proportion of different populations and life stages) and the relative success of Delta vs. natal rearing (inferred by rearing duration, growth rate, diet and condition). We quantify the extent to which Delta rearing contributes to salmon population resiliency under different environmental conditions, including drought (2014-15) and flood conditions (2017, 2019), and provide baseline data to provide insights into population-level responses to future habitat restoration and climate change. The study uses annual collections of fall & late fall run salmon samples from sites upstream (Mossdale/Sherwood Harbor), within, and downstream (Chipps Island) of the Delta sampled by the IEP Delta Juvenile Fish Monitoring Program (DJFMP). Need Annual monitoring surveys routinely sample salmon entering and leaving the Delta, but the extent to which these juveniles rear there is virtually unknown, and has been highlighted as a critical data gap for parameterizing the NMFS Chinook salmon life cycle model (S. Lindley NOAA pers. comm.). There are limited tools available to monitor habitat use by native fishes, with most efforts providing a snapshot of fish presence/absence or abundance. Tagging studies provide key information about migratory pathways and survival through stretches of the Delta, but are typically limited to larger individuals and often use hatchery smolts with different rearing needs and seareadiness to the smaller individuals most likely to use Delta habitats. Otoliths represent a unique tool to reconstruct fish age, natal origin, growth history, movement patterns, and habitat use, even in fry <40mm fork length. Objectives We will use juvenile salmon collected by the IEP Delta Juvenile Fish Monitoring Program to assess: 1. Contributions of different rivers & hatcheries to sites upstream, within & downstream of the Delta. 2. Delta habitat use (frequency, duration) and success (growth rates, condition and diet). 3. Mechanisms governing juvenile salmon outmigration timing from the natal tributary.
    Science topics None specified
    Updated April 29, 2022
  • Title

    Enhanced Delta Smelt Monitoring [EDSM]

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

    Description The Enhanced Delta Smelt Monitoring (EDSM) program is a year-round monitoring program comprised of multiple crews trawling concurrently at multiple sites in predefined strata within the San Francisco Estuary. Post-larval Delta Smelt are targeted approximately April through June using 20mm trawling gear, and Kodiak trawling gear is employed the remainder of the year. Gear efficiency experiments and shallow water sampling elements are incorporated when possible. Need The declining Delta Smelt population has highlighted the need to keep improving the array of information that supports our understanding of the factors affecting Delta Smelt population dynamics and management decisions to minimize adverse effects of water operations on the population. EDSM has biological significance and potential conservation benefit by providing data to resource managers on nearly all life stages of endangered Delta Smelt and near-real-time data on the juvenile and adult life stages. EDSM data is provided to the Smelt Working Group and other managers in near realtime to help inform management decisions during the entrainment season. Objectives • To estimate the total abundance of Delta Smelt, along with standard errors or confidence intervals, on a weekly to bi-weekly basis for various life stages (postlarvae, juveniles, sub-adults, adults) throughout the year; • To estimate the spatial distribution of Delta Smelt at a management relevant temporal and spatial resolution;and • To provide data that support management decisions and address scientific questions to further understanding of sampling efficiency, drivers of Delta Smelt population patterns, and other conservation and management-relevant topics.
    Science topics Delta Smelt
    Updated April 24, 2025
  • Title

    Effect of Outflow Alteration upon Delta Smelt Habitat, Condition and Survival

    Lead U.S. Bureau of Reclamation [USBR]
    Description Description The Directed Outflow Project (DOP) is a continuing collaborative effort among a dozen state, federal and non-governmental groups. The DOP will employ a focused spatial and temporal approach to evaluate mechanistic hypotheses directly related to the rationales provided for the summer Delta outflow action and Yolo Bypass Toe Drain action to benefit Delta Smelt, with direct relevance to the fall outflow action. Paired data collections (same location and time) of abiotic and biotic habitat constituents to test specific hypotheses will assist in avoiding prior shortcomings of using data collected for different studies/hypotheses and/or across variable spatial/temporal scales (as discussed in MAST [2015] and elsewhere). Sampling will occur during the Delta Smelt juvenile rearing-stage, a period known to be associated with the location of the low salinity zone (LSZ). Results should strengthen our understanding of the mechanisms and drivers impacting Delta Smelt vital rates and associated habitat features with a focus on outflow conditions. Results should assist in evaluating the benefit and feasibility of future flow augmentation actions for managers and decision makers. Results from this and other related studies will inform evaluations on which particular outflow-related action or group of actions provides the most benefit for Delta Smelt. Need Requests and plans for water management actions related to augmentation of Delta outflow have proceeded and are expected to proceed in the future. However, there is uncertainty and disagreement regarding the mechanistic relationship of Delta outflow during the rearing period to Delta Smelt vital rates and habitat, and the hypothesized benefit of outflow alteration for Delta Smelt. Delta outflow has experienced reductions in recent years, coinciding with the collapse of the Delta Smelt. Reduced outflow has been linked to reductions in habitat suitability in Suisun Bay and Marsh and movement of the LSZ to the Confluence of the Sacramento-San Joaquin River where little connection to shallow open water habitats exists. Objectives The DOP’s main objective will be to evaluate the hypothesized benefit of outflow alteration for Delta Smelt and its habitat in coordination with all stakeholder groups. The following process and product related sub-objectives will facilitate progression toward this evaluation objective. • Test mechanistic hypotheses addressing the rationale behind outflow-based actions to benefit Delta Smelt. • Concurrently sample fish and measure abiotic/biotic habitat conditions at each randomly selected location along the salinity and habitat gradient of the north to western Delta along the Sacramento River during the summer and fall.
    Science topics Delta Smelt
    Updated April 29, 2022
  • Title

    Integrating Measurement of Fish Body Condition within the Delta Juvenile Fish Monitoring Program [DJFMP]

    Lead U.S. Fish and Wildlife Service [USFWS]
    Description Description The aim of this pilot effort is to begin assessing methods and developing protocols for incorporating measurement of fish body condition (Fulton’s Condition Index, K) into standard Delta Juvenile Fish Monitoring Program (DJFMP) sampling. Need The goal of this study is to examine the utility of fish body condition as a measure for DJFMP to evaluate underlying factors driving fish health and survival in the Sacramento and San Joaquin River-Delta system. This will provide a more complete assessment of how condition metrics vary for common fish species that are sensitive to differences in environmental conditions, filling a fundamental data gap in our existing monitoring program. Objectives • Establish a pilot sampling design and methods for collection of data from fish sampled through DJFMP. • Assess the utility and expand the use of body condition to include up to 7 species of commonly sampled fishes. • Develop protocols for incorporating new methods into DJFMP sampling.
    Science topics Fish
    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