This study analyzes 12 notch scenarios in the Fremont Weir in terms of entrainment of juvenile salmon. The goal is to quantify the relative entrainment rates (between 0 and 1) across the suite of scenarios and to identify possible strategies for enhancing entrainment outcomes. This study does not predict future entrainment as models generally do not predict future outcomes so much as highlight trends
Much research in the Delta has focused on foodweb dynamics, stimulated by evidence that low productivity of plankton is linked to declines in several fish species including the endangered delta smelt. Pseudodiaptomus forbesi is the most abundant copepod (small crustaceans) in the Delta in summer. It is an important food source for many fishes and makes up about half of the food of delta smelt. This study focuses on the feeding, reproduction, and growth of copepods as essential foodweb support for fishes. This work investigates four diverse habitats including two open-water channels and two shallow habitats. The researchers will measure copepods' feeding rates on microscopic plants and animals, and relate feeding to their rates of growth and reproduction. Computer models will be used to estimate their movement and death rates. These results will show the sources of nutrition used for growth and reproduction of these key organisms. Results will inform how food webs respond to large scale changes in the Delta ecosystem, for example, restoration and the Sacramento wastewater treatment plant upgrade.
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)?
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).
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.
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 "on the water" sampling.
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 trawl efficiency estimates using data from releases of coded wire tags (CWT), acoustic tags (AT), and by genetically sampling the trawl catch in 2025 and 2026. The project will (1) develop statistical models for estimating trawl efficiencies using 2016-2025 data for paired AT-CWT releases of winter run and fall-run Chinook Salmon; (2) use 2016-2025 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 for 2016-2025; (3) implement trawl efficiency studies for multiple salmon runs in 2025-2026 informed by the prior 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 2016-2025.
Description: The Enhanced Delta Smelt Monitoring (EDSM) program is a comprehensive, year-round monitoring initiative that employs multiple research crews conducting concurrent trawling operations across designated strata within the San Francisco Estuary. The program specifically targets post-larval Delta Smelt from April through June using 20mm trawling gear, while Kodiak trawling gear is utilized for the remainder of the year. Need: The ongoing decline of the Delta Smelt population has underscored the critical need for continuous improvement in the data supporting our understanding of the ecological and anthropogenic factors influencing Delta Smelt population dynamics. The EDSM program plays a vital role in providing essential biological data that informs management strategies aimed at mitigating the adverse effects of water operations on this endangered species. By capturing data across nearly all life stages of Delta Smelt, including near-real-time information on juvenile and adult stages, the EDSM program offers significant conservation benefits. This data is promptly disseminated to the Smelt Working Group and other resource managers to facilitate informed decision-making during the critical entrainment season. Objectives: -Estimate the total abundance of Delta Smelt, including standard errors or confidence intervals, on a weekly to bi-weekly basis across various life stages (post-larvae, juveniles, sub-adults, adults) throughout the year. -Assess the spatial distribution of Delta Smelt at a management-relevant temporal and spatial resolution. -Provide data that supports management decisions and addresses scientific inquiries related to sampling efficiency, drivers of Delta Smelt population patterns, and other conservation and management-related topics.
Chinook Salmon (Oncorhynchus tshawytscha) populations in California are in decline due to the combined effects of habitat degradation, water diversions, and shifting climate regimes. This project uses archival tissues (otoliths, vertebrae) from modern and ancient spring-run Chinook Salmon to understand how shifts in migration timing and habitat use allowed salmon to cope with highly variable environmental conditions. We will learn how salmon responded to the recent drought and flood periods (2012-2020 CE), the California Gold Rush Period (~1835-1870 CE), the Little Ice Age (~1560-1780 CE), and the Megadrought Period (~1200-1410 CE). This effort will provide the insights needed for developing climate-adapted conservation actions to support salmon into the future.
