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Captive Delta Smelt
Save the Dates March 21-24, 2023
for the upcoming 2023 IEP Annual Workshop. The workshop will be held in the California Natural Resources Headquarters building at 715 "P" Street in downtown Sacramento. The workshop will be a
hybrid (in-person and virtual) event! Information on the workshop will be posted on our
IEP Annual Workshop
web page and distributed via our IEP Annual Workshop email list. Make sure to
to receive updates.
A Call for IEP Newsletter articles for the Winter, Volume 42, Issue 1, 2023 is now open!
The deadline for submission is February 15, 2023.
Submissions should be sent to
at the California Department of Water Resources.
Spring, Volume 41, Issue 2, 2022 (pdf)
IEP Newsletter is now available. Previous issues can be found on our
IEP Newsletter page
and in the
The Summer/Fall, Volume 41, Issue 3, 2022 will be coming out soon!
NASA's Earth Science Applied Sciences is pleased to announce the release of the A.40 Earth Science Applications: Ecological Conservation (formertly Ecological Forecasting) solicitation. This program element solicits proposals that would enable decision-making to combat the spread of invasive species, advance the use of ecosystem service assessment for decision-making, and inform management, establishment, or protection of protected areas. Proposals must activities and products that will achieve operational deployment and sustained use in decision-making by the end user(s) (i.e., ARL 9) before the end of the award. To feasibly achieve this objective, all submissions must show a demonstrated maturity in development beyond initial discovery, feasibility, and development (i.e., start at ARL 5 or greater) and an established relationship with an end user. Like past solicitations, proposals must combine three components: Earth observations, in-situ biological observations, and ecological models to develop decision-support tools.
Notices of intent are requested by March 14, 2023, and proposals are due April 14, 2023. A virtual meeting for potential proposers will occur January 13, 2023, from 2-4 pm eastern time.
Connect information will be posted under other documents on the
NSPIRES page for this program element
no later than December 13, 2022. Questions on the solicitation can be directed to
Dylan Stompe, Project Lead of the California Department of Fish and Wildlife (CDFW) Sturgeon Study, was recently highlighted in an episode of
Angler West TV (Video)
. He joined Gate Crashers Zach and Virginia to discuss sturgeon in the San Francisco Estuary and the CDFW sturgeon tagging program. The episode includes a special segment with Dylan and two teams from CDFW conducting a trammel net survey. Listen to Dylan as he explains how collected data from captured fish and the tagging program are used to better understand the life history and current population status of sturgeon in the estuary. The tagging program uses reward tags that fishermen can redeem for money. Questions regarding the reward tags can be directed to
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.
Foodwebs associated with wetland restoration are the subject of the interestingly-titled article by Hartman and colleagues in the San Francisco Estuary and Watershed Science journal. “
I’m Not that Shallow – Different Zooplankton Abundance But Similar Community Composition Between Habitats in the San Francisco Estuary
” suggests “
that monitoring of wetland restoration sites must rely on multiple years of data collected on the site—rather than relying on adjacent open-water sampling—and should include monitoring of epiphytic and epibenthic invertebrates as well as zooplankton
In a new article published in
Nature: Scientific Reports
Dr. Hung and colleagues at UC Davis used controlled laboratory experiments to document Delta Smelt temperature and salinity preferences.
The authors found “that Delta Smelt showed no temperature preference below 15 °C, a modest aversion to the warmer tank from 15 to 28 °C, and a strong aversion to the warmer tank with elevated mortality at temperatures above 28 °C. Delta Smelt also preferred lower salinities, and this preference became more pronounced as salinity increased toward 23 ppt. These results indicate that Delta Smelt can tolerate high temperatures and salinities for a short time, and that their preferences for lower temperature and salinity strengthens as these variables increase."
A variety of IEP and Agency datasets were combined to yield an improved picture of the life-cycle of Wakasagi, a non-native congener to the endangered Delta Smelt in the San Francisco Estuary.
Davis and 9 others published in
San Francisco Estuary and Watershed Science
an article that discusses how they “found Wakasagi in greatest abundance in the upper watershed below source reservoirs, and in the northern regions of the estuary with the most co-occurrence with Delta Smelt; however, their range extends to western regions of the estuary, and we found evidence of an established population that annually spawns and rears in the estuary."
Larval recruitment of Longfin Smelt
is the subject of an article by C.A. Brennan and others in the most recent edition of
San Francisco Estuary and Watershed Science
. In this publication surveys of coastal northern California estuaries detected Longfin Smelt larvae northward of Cape Mendocino. The relationship of San Francisco Estuary Longfin Smelt populations to others found outside the Estuary are unknown and need further examination and study.
University of Maryland colleague P.M. Glibert and local researchers from San Francisco State University and the California State University Maritime Academy published an article focusing on the
low productivity of the San Francisco Bay Delta and how nutrient input changes from wastewater treatment plants (upgrades) in the system over time may have affected the status of regional food webs
. Pre- and post-upgrade phytoplankton concentrations were used to describe how long-term observations will be needed to track the effects of nutrient changes to the estuary over time and at various intervals. This publication appears in Nitrogen, titled: “
Ecosystem Recovery in Progress? Initial Nutrient and Phytoplankton Response to Nitrogen Reduction from Sewage Treatment Upgrade in the San Francisco Bay Delta
San Francisco Estuary and Watershed Science
journal is featured again in this article from Young et al. from the USGS wherein they
used Striped Bass diet analysis to gain an appreciation for how these fish forage across different habitat types
. The authors conclude that “Striped Bass diets differ across habitats, with marsh foraging important to Striped Bass regardless of collection location.” These results may be important when considering design and placement of restored marsh habitats.
climate change review (PDF)
has been published as an IEP Technical Report
and is now available for distribution. This recent effort by the Climate Change Management Analysis and Synthesis Team (MAST) represents critical analysis of issues important for continued management of water and aquatic habitats in the upper San Francisco Estuary and surrounding watersheds.
In the words of the authors: “Management strategies for ecological values in the face of climate change require reliable and focused information. In this technical report, our focus is on the Upper San Francisco Estuary which contains the Sacramento-San Joaquin Delta and Suisun Bay. This area is home to three interconnected ecosystems: open water, floodplain, and tidal marsh. Starting with a conceptual model, we focus our analyses on the likely impacts of climate change on these aquatic habitats. We illustrate how changes in habitats are likely to affect diverse species. We describe ecological trends attributable to climate change and likely future impacts.”
The Report citation follows: Climate Change MAST (Management, Analysis and Synthesis Team). 2022. Synthesis of data and studies related to the effects of climate change on the ecosystem and biota of the Upper San Francisco Estuary. IEP Technical Report 99.
In a long-awaited manuscript, Hendrix and others examined fall habitat quality for Delta Smelt using IEP data from 1980 to 2015.
As part of an effort from the Delta Smelt Scoping Team (DSST) within the Collaborative Adaptive Management Team (CAMT), this paper in
Estuaries and Coasts
looked at occupancy models to determine what physical factors accounted for presence/absence of the endangered smelt.
Of what consequence is longfin smelt entrainment and of what use managing diverted flows to their population index?
In this article from
Estuaries and Coasts
, Kimmerer and Gross “showed the cumulative proportional losses of longfin smelt to diversions to be small in comparison to the 100-fold dynamic range of the population index. This finding indicates that attempts to reverse the decline of this species through manipulation of diversion flows are unlikely to bear fruit.”
Featured Dataset Publications
The IEP Smelt Larval Survey Team has published a new dataset and is linked on the Environmental Data Initiative data repository site. See Interagency Ecological Program (IEP), L. Damon, V.M. Mora, and J.A. Jimenez. 2022.
Interagency Ecological Program San Francisco Estuary Smelt Larva Survey 2009 – 2022 ver 5. Environmental Data Initiative
The Interagency Ecological Program San Francisco Estuary Smelt Larva Survey was initiated by the California Department of Fish and Wildlife (CDFW) in 2009 to monitor the distribution and abundance of newly-hatched Longfin Smelt (Spirinchus thaleichthys) in the San Francisco Estuary. Surveys are conducted bi-weekly and sampling begins in December, and continues through March. The surveys sample at fixed locations, stations, from Carquinez Strait through Suisun Bay and into the Sacramento-San Joaquin River Delta. Napa River stations were added in 2014. Each survey consists of 44 stations. At each station, one 10 minute stepped-oblique (bottom to top) tow is made following a prescribed tow schedule. The net is a conical 505 µm mesh lashed to a D shaped frame mounted on skis. Larval fish samples are preserved in the field in 10% Formalin and brought back to the CDFW Stockton Lab for identification to species and enumeration under a microscope. Several types of data are collected at each station in addition to the larval fish sample, including the volume of water sampled by the net, surface water temperature, surface and bottom specific conductance (EC normalized at 25˚C), Secchi disk depth, tow duration, tidal condition, and surface water turbidity.
The goal of
is to provide easy access to the integrated San Francisco estuary Delta fish dataset. This dataset is published, citable, and documented on EDI. The dataset contains around 45 million rows, which are not easily query-able with normal R techniques.
utilizes the R implementation of Apache Arrow and the parquet data format, along with dbplyr to make the process of working with this large dataset much easier on a standard computer. For non-R users, you can find the
on the Delta Stewardship Council shiny app page.
IEP Seasonal Monitoring Report
has now been updated with 2021 data.
Check out the
for upcoming Project Work Team, Stakeholder Group meetings and other IEP related events!
December 1 Aquatic Vegetation PWT meeting 1:00 p.m. to 3:00 p.m.
December 14 Contaminants PWT meeting 1:00 p.m. to 4:00 p.m.
December 14 Zooplankton PWT meeting 1:30 p.m. to 3:30 p.m.
Other Events or News
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.
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
Recording of the
Delta Smelt Individual Based Model Workshop (video)
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.
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.
IEP Blogs -
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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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