The Environmental Monitoring Program (EMP) began in 1975 to conduct baseline and compliance monitoring of water quality, phytoplankton, zooplankton, and benthic invertebrates in the San Francisco Bay-Delta estuary. This monitoring program was designed to track the impact of water diversions to the State Water Project (SWP) and Central Valley Project (CVP) on the Bay-Delta. In the decades since, EMP scientists have monitored these constituents at fixed and floating stations throughout the estuary and ensured compliance with state and federal mandates such as Water Right Decision 1641 (D-1641). In the years and decades since its inception, EMP has become one of the cornerstones for scientists' and managers' understanding of the pace and pattern of change in this critical ecosystem. By sampling water quality and biological communities concurrently, EMP has created a dataset that is uniquely useful in better understanding causal connections between physical, biological, and biogeochemical processes.
The Diet and Condition study has provided information on the food habits of young pelagic fishes in the San Francisco Estuary (SFE) since 2005. This study was created to address questions of food limitation in young fish by understanding the types and amount of prey eaten among seasons and regions of the SFE. Food limitation can be an important factor to the annual recruitment success of fish that use the estuary as a nursery, such as ESA listed Delta Smelt (Hypomesus transpacificus) and Longfin Smelt (Spirinchus thaleichthys). We focus on the temporal and spatial differences in diet composition and foraging of native smelts and also non-natives such as age-0 Striped Bass (Morone saxatilis), Threadfin Shad (Dorosoma petenense), Mississippi Silversides (Menidia beryllina), Wakasagi (Hypomesus nipponensis), and age-0 American Shad (Alosa sapidissima). Data from this project has been used to inform the Fall Low Salinity Habitat Program (FLaSH), Directed Outflow Project (DOP), 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. The focus of the study currently is to analyze existing diet data and report findings generated from study species, to inform Longfin Smelt foraging conditions, ongoing outflow management of Summer-Fall Habitat Action efforts, and Delta Smelt Supplementation evaluations of wild vs culture origin foraging success. 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)?
The CDFW Fish Restoration Program will collect fish and invertebrate data near existing and planned tidal wetlands. These data will provide information on how fish and invertebrate communities change pre-/post-restoration. While collecting these data, the variability of invertebrate catches will be assessed for each gear type to determine the optimal number of samples per sampling site.
Under the 2008, 2019, 2024 State Water Project/Central Valley Project Joint Operations Biological Opinion from United States Fish and Wildlife Service, 2009, 2019, 2024 National Marine Fisheries Service, and 2009, 2020, and 2024 State Water Project Incidental Take Permit, Department of Water Resources (DWR) is required to restore >8,000 acres of tidal wetlands in the Sacramento-San Joaquin Delta (Delta) and Suisun Marsh to improve habitat and food web resources for threatened fishes. The Fish Restoration Program is responsible for biological monitoring in these restored tidal habitats to assess their success for providing habitat and food web benefits for at-risk native fishes.
Assess the food web resources (nutrients, phytoplankton, zooplankton, and macroinvertebrates) associated with pre- and post-restoration tidal wetlands, as well as with existing reference wetlands
Assess the fish community of restoring wetlands including use by rearing salmonids and characterization of the predator and competitor communities
The Zooplankton Study has sampled macro-, meso-, and micro-zooplankton in the upper San Francisco Estuary since 1972. Samples are collected monthly at 19 stations, located from upper San Pablo Bay to the eastern Delta, using three gear types – a pump sampler for microzooplankton, such as copepod nauplii and rotifers, a CB net for mesozooplankton, such as adult copepods and cladocerans, and a mysid net for macrozooplankton. The Zooplankton Study provides data on zooplankton abundance and distribution to assess the food resources available to fish in the upper San Francisco Estuary, as zooplankton are an important trophic link between primary producers and upper trophic levels. This information is used by aquatic ecologists to investigate physical and biological drivers of the lower food web and relationships between food resources and fishes that feed on zooplankton in the upper estuary, including listed species such as Delta and Longfin Smelt.
The Zooplankton Study is conducted in compliance with the SWRCB’s Water Rights Decisions 1485 (Term 10a) and 1641 (Term 11a). This study may also inform the CDFW 2024 Incidental Take Permit, the operations of the State Water Project (Table 2), the 2024 NMFS and USFWS Biological Opinions for operations of the Central Valley Project, and the Summer-Fall Habitat Action Team.
