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Captive Delta Smelt
The 2022 IEP Workshop was a great success.
Links to the workshop session recordings can be found on the
IEP Annual Workshop
. Recordings will be made available for viewing until June 30, 2022. We congratulate the Best Early Career Poster Award Winner, Claudia Macfarlane (USFWS) for her poster "Liberty Island: A New Hope for Natives" and the People's Choice Best Presentation Award Winner, Denise Colombano (University of California, Berkeley) for her plenary on "Strength in Numbers: advancing estuarine ecology through data synthesis and collaboration".
The USGS California Water Science Center recently published their
California Waters Winter 2022 - Volume II - Issue I newsletter
. The purpose of the newsletter is to keep readers updated with current research projects, the latest publications, and other work the center is doing. Check out the articles on nutrient loads entering the Sacramento- San Joaquin Delta and research on the hydrodynamics in the Upper Sacramento Deep Water Ship Channel.
Experimental Release of Delta smelt into the Wild for the First Time (PDF)
- During the week of December 17, 2021, the U.S. Fish and Wildlife Service, the California Department of FIsh and Wildlife, the California Department of Water Resources, the U.S. Bureau of Reclamation along with our partners at U.S. Geological Survey and UC Davis, experimentally released captively produced Delta smelt into the Sacramento-San Joaquin River Delta.
Photos and videos
from the release can be viewed and downloaded from the U.S. Fish and Wildlife Service's California-Great Basin Region
The 2021 summer/fall edition (Volume 40, Issue 3) of the IEP Newsletter is now available on our
page. No submissions were received for the 2022 winter edition, so no issue will be published. We are also announcing the call for articles for the 2022 spring edition of the newsletter. Articles can be sent to
. Submissions are due by June 15. Don't forget to
to our Newsletter list so you can receive the next edition in your mailbox.
Biologists from California State Parks, the Interagency Ecological Program, and other agencies have identified a new weed in the Delta. The species is Ribbon Weed (
Ribbon Weed Fact Sheet (PDF)
provides more information on how to recognize it and report it. So far, it has been documented at Rio Vista Delta Marina Yacht Harbor, Long Island, Hogback Island Boat Launch, Liberty Island, Mokelumne River near Lighthouse Marina, and Sherman Lake. Please report any sightings to Trish Gilbert (
) at the California Department of Parks and Recreation, Division of Boating and Waterways.
Smelt Larva Survey
– Many native fish use cooler temperatures in winter and early spring to time their spawning activities. Heat stress may be at a minimum this time of year, and seasonally higher stream flows can help disperse pelagic larvae. The
Smelt Larva Survey
, initiated in January 2009, provides near real-time distribution data for longfin smelt larvae in the Delta, Suisun Bay and Suisun Marsh. These data are used by agency managers to assess vulnerability of longfin smelt larvae to entrainment in south Delta export pumps.
Half a century of data collection returns rewards from analytical “look-backs”
In a nod to IEP’s recent 2020 Gold Anniversary we call your attention to two recent publications of note. In the first, from
Limnology and Oceanography
, Bashevkin, Mahardja, and Brown, examine long-term records of temperature data in the upper San Francisco Estuary and find that temperature changes through five decades have multiple drivers and cannot be ascribed to any single source of change. A second review of monitoring data by Bashevkin and 7 others available from
presents zooplankton abundance sampled in the San Francisco Estuary since 1972. This estuarine zooplankton dataset is the longest such data record anywhere in the world and will help scientists understand variability in food web dynamics throughout the Estuary. The dataset is available for download from the
Environmental Data Initiative
A new Delta Smelt-oriented IEP Technical Report includes white paper chapters summarizing various issues related to environmental variability in the upper San Francisco Estuary
The purpose of this Technical Report is to provide background information on various topics that are consistently considered important for understanding Delta Smelt ecology, including abiotic habitat, biotic habitat, and measures of response of individual Delta Smelt and the population to environmental conditions. Prepared by the Flow Alteration (FLOAT) Management Analysis and Synthesis Team (MAST), this
Technical Report 98 (PDF)
is prelude to annual summaries and syntheses (in development) of factors affecting the Delta Smelt population, provides background for understanding the annual syntheses, and will be useful to anyone needing a basic background in Delta Smelt ecology.
Complicated life history strategies demand additional monitoring and analysis to understand Steelhead (Oncorhynchus mykiss) populations and recovery
Eschenroeder and colleagues published their research article in the most recent volume of the
San Francisco Estuary and Watershed Science
journal. Recommendations for additional and modified data collection are described.
Why we need to monitor pathogens in our conservation and supplementation programs
Gille and others published their rationale and recommendations for including improved molecular pathogen assays as part of regular procedures used for fish supplementation and reintroduction programs. This research is also found in the most recent volume of the
San Francisco Estuary and Watershed Science
Drought impacts reproductive performance of Delta Smelt (Hypomesus transpacificus)
The dry and critically dry years of 2013 and 2014 negatively impacted the reproductive status of female Delta Smelt caught in IEP surveys as reported in
by Kurobe and colleagues. The study discusses whether drought-related changes in water quality lay behind the lowered performance in these drier years in the Estuary.
Yelton, Slaughter, and Kimmerer describe how “Diel behaviors of Zooplankton interact with tidal patterns to drive spatial subsidies in the Northern San Francisco Estuary” in a recent article published in
Estuaries and Coasts
Using strontium isotopes to reconstruct White Sturgeon (Acipenser transmontanus) life histories – From
frontiers in Marine Science
Kirsten Sellheim and five co-authors improve our documented understanding of White Sturgeon habitat use through space and time in the San Francisco Estuary.
Featured Dataset Publication
Bashevkin, S.M., J.W. Gaeta, T.X. Nguyen, L. Mitchell, and S. Khanna. 2022.
Fish abundance in the San Francisco Estuary (1959-2021), an integration of 9 monitoring surveys. ver 1. Environmental Data Initiative.
The San Francisco Estuary (SFE) is simultaneously a central hub of water delivery in California and home to commercially important and endangered fishes, such as Chinook Salmon, Green Sturgeon, and Delta and Longfin Smelt. Extensive ecological monitoring has been conducted for over 50 years, mainly under the auspices of the
Interagency Ecological Program
for the San Francisco Estuary. We integrated fish catch and length data from 9 long-term monitoring surveys in the SFE. The integrated database contains survey-level data such as environmental variables and sampling effort in addition to the fish-level species, lengths, and counts. Zero catches have been filled in for any species not caught in a sample. The geographic scope includes San Francisco Bay through the upper estuary, and the timeseries spans 1959 to 2021. Sampling methods, gear, fish length metric, and other factors differ among the component surveys. Sampling designs (locations and temporal frequency) have also changed over time. Thus, it is highly recommended to inspect the documentation of the component surveys for more information on their methods.
Burdi, C.E., S.M. Breining-Aday, and S.B. Slater. 2022.
Interagency Ecological Program: Zooplankton and water quality data in the San Francisco Estuary collected by the Summer Townet and Fall Midwater Trawl monitoring programs. ver 1. Environmental Data Initiative.
The Interagency Ecological Program’s (IEP)
Summer Townet Survey (STN)
Fall Midwater Trawl (FMWT)
are two long-term monitoring projects conducted by the California Department of Fish and Wildlife (CDFW) to monitor fish abundance and distribution trends in the San Francisco Estuary (SFE) since 1959 and 1967, respectively. Starting in 2005, zooplankton monitoring was added and paired with fish tows to investigate food availability for young fishes. Food limitation has been a long-term issue and a focus of the Pelagic Organism Decline (POD) studies that began in 2005. By 2011, STN routinely conducted zooplankton monitoring at 40 stations, and FMWT at 32 stations in the upper SFE from Carquinez Strait to the Sacramento Deep Water Ship Channel and into the South Delta. STN samples every other week from June to August and FMWT samples once monthly from September to December. Both projects collect mesozooplankton samples using a modified Clarke-Bumpus (CB) net to target copepods and cladocerans, and FMWT also samples macrozooplankton (i.e. mysids and amphipods) using a mysid net. Flowmeters are used to measure the volume sampled to determine zooplankton catch per unit effort. Environmental variables such as water temperature, turbidity, secchi, and electrical conductivity are collected with each zooplankton sample. Concurrent fish and zooplankton tows conducted by STN and FMWT have allowed for comparisons of fish diet to the available zooplankton prey at the time of collection.
Check out the
for upcoming Project Work Team, Stakeholder Group meetings and other IEP related events!
June 2 Aquatic Vegetation Project Work Team from 1:00 p.m. to 4:00 p.m.
June 3 Winter-run Chinook Salmon PWT Meeting from 1:00 p.m. to 3:00 p.m.
June 8 Contaminants PWT Meeting from 1:00 p.m. to 4:00 p.m.
June 9 FLOAT PWT Meeting from 9:00 a.m. to 11:00 a.m.
June 22 Zooplankton PWT Meeting from 1:30 p.m. to 3:30 p.m.
Other Events or News
Delta Science Program - National Center for Ecological Analysis and Synthesis (DSP-NCEAS) 2021 Synthesis Working Group
This working group provides high-quality training in synthetic data science and statistical techniques and offers an opportunity for enhanced collaboration between agency and academic scientists. The group leverages training and a collaborative setting to analyze drivers of the Delta's estuarine food supply. Products from this working group will offer strong scientific support to inform decision-making for restoration, the protection of endangered species, and the management of flow actions. More information about the effort, including resources developed during the 2021 Synthesis Workshop can be found on the
Recording of the Delta Smelt Individual Based Model Workshop is now available. This is the first of two planned workshops on the updated Delta Smelt Individual Based Model (DSIBM) developed jointly by USFWS' San Francisco Bay Delta Fish and Wildlife Office, University of Maryland Center for Environmental Science (UMCES), and San Francisco State University Estuary & Ocean Science Center. The newly updated DSIBM expanded its capacity to evaluate effects of environmental variables, proposed long-term water operation plans (e.g., flow and entrainment), and other management actions (e.g., hatchery delta smelt supplementation, food enhancement, habitat restoration) on delta smelt population dynamics.
Until further notice IEP meetings/gatherings are being held remotely/virtually.
Frontiers for Young Minds
provides a collection of freely available scientific articles by distinguished scientists that are shaped for younger audiences by the input of their own peers.
Where the river meets the ocean - Stories from San Francisco Estuary
is a collection of stories from IEP scientists that tell; how people, plants, and animals use the San Francisco Estuary.
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The View from Here
- A blog by the IEP Lead Scientist, Steve Culberson
Views from the Water
- A blog by our IEP survey field crew members
Science Stories: Adventures in Bay-Delta Data
- A blog by Rosemary Hartman (DWR), one of IEP's Synthesis Team members.
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