Arroyo Canal And Sack Dam Project Update
Bureau of Reclamation
The Arroyo Canal Fish Screen and Sack Dam Fish Passage Project is specifically identified in the settlement under paragraph 11(a)(1)(6) and 11(a)(1)(7) respectively. The Arroyo Canal Fish Screen will prevent entrainment of fish into the Arroyo Canal and the Sack Dam Fish Passage project will create fish passage around Sack Dam. This presentation will highlight the design and function of the Fish Ramp, River Bypass, and Fish ladder to move fish and flows around Sack Dam as well as the screen alignment that provides full delivery to the Arroyo Canal while preventing fish entrainment. Our updated design features have increased the channel capacity around Sack Dam, created greater frequency by which anadromous fish species and other species like sturgeon can pass around Sack Dam, improved the capacity for deliveries to Arroyo Canal, improved the effectiveness of safely screening fish from the Arroyo Canal and incorporating subsidence.
Eastside Bypass Control Structure Fish Passage Improvement Project
California Department of Water Resources (DWR)
DWR is assisting the San Joaquin River Restoration Program (SJRRP) in identifying structures that have the potential to impede fish passage within the San Joaquin River and flood bypasses from Friant Dam to the confluence of the Merced River. One of the structures identified as a fish passage impediment at lower flows is the Eastside Bypass Control Structure (EBCS) – a gated structure that is part of the Lower San Joaquin River Flood Control Project and provides flood control for the region. DWR will install a full-width rock ramp at the EBCS to improve fish passage for not only salmonids but other resident native fish including sturgeon and lamprey. The overall goal of the project is to improve fish passage while still maintaining the local levee district’s ability to manage flood flows. The rock ramp is a fish passage project that will allow the SJRRP to meet a major milestone of providing volitional fish passage in the next few years. Adult salmon are actively returning to the Restoration Area during wetter water years and the ability for the SJRRP to keep the river connected. The EBCS is one of the downstream most barriers in the system and making modifications to this structure is imperative to the overall success of the program.
Defining Success for San Joaquin River Fish Populations
O. Towns Burgess, Ph.D.
Bureau of Reclamation
The Settlement’s Restoration Goal is, “to restore and maintain fish population in ‘good condition’ in the main stem of the San Joaquin River below Friant Dam to the confluence of the Merced River, including naturally-reproducing and self-sustaining populations of salmon and other fish.” Though the Settlement identifies specific actions related to fish reintroduction, channel and structural improvements, and flow releases, it does not define the biological objectives needed to achieve the Restoration Goal. This presentation will review how the San Joaquin River Restoration Program defines a naturally-reproducing and self-sustaining population, and how fishery objectives are used to assess progress toward meeting the Restoration Goal and the effectiveness of restoration activities. The current state of the reintroduced spring-run Chinook salmon population will be discussed, and future challenges will be identified that must be overcome to restore fish populations in good condition in the San Joaquin River Restoration Area.
Complexity of Land Subsidence in the Central Valley, California
Claudia Faunt, Jon Traum, and Scott Boyce
U.S. Geological Survey, California Water Science Center
In California’s Central Valley, agricultural demand for irrigation is heavily reliant on surface water and groundwater. In the last few decades, land-use changes and limited surface-water availability—including drought, reduced conveyance, and environmental flows—have led to increased pumping, causing groundwater-level and groundwater-storage declines, land subsidence, decreased stream flows, changes to ecosystems, and degradation of water quality. Land subsidence is causing damage to infrastructure, which has led to a decrease in the delivery of surface water and permanent loss of aquifer storage. In some locations, the magnitude of subsidence varies greatly throughout short distances (horizontally and vertically). Subsidence can easily be tied to the wrong stressor and causes cannot be accurately determined if the underlying stresses (such as pumping- including screened interval, location, magnitude, and timing) and geology/ aquifer properties are unknown or cannot be estimated robustly. Analysis of compaction and subsidence data from multiple measurement methods (InSAR, extensometer, continuous GPS, and leveling data) and simulations show that subsidence occurs in areas with complex interactions including fast- and slow-draining clay interbeds and driven by varying locations and rates of groundwater extraction. With the increasing variability in climate conditions and the implementation of California’s Sustainable Groundwater Management Act (SGMA), collecting, compiling, analyzing, and simulating these data and processes accurately can help inform local and regional management decisions aimed at improving groundwater sustainability in the Central Valley.
Part III Projects – what have we done, and what’s next?
Friant Water Authority
Enacted in 2009, Part III of the San Joaquin River Settlement Act authorized funding for studies and construction of canal capacity restoration, groundwater banking and recharge projects within the Friant Division. This presentation will review projects completed to date, their successes and lessons learned, and the status of ongoing and future projects.
Groundwater Seepage: Managing Groundwater Levels in the Restoration Area
Bureau of Reclamation
The San Joaquin River Restoration Settlement Act, Public Law 111‐11, calls for the Secretary of the Interior to address any material adverse impacts from groundwater seepage that may result from Restoration Flows. This includes developing a seepage monitoring program. The Seepage Management Plan (Plan) was developed over several years and is a dynamic and adaptive document, incorporating new data and stakeholder input. The Plan aims to manage groundwater levels through an extensive monitoring network and evaluation of any recommended flow changes. The SJRRP maintains a groundwater monitoring well network of 200+ wells to avoid exceedance of agricultural and historical groundwater thresholds. This monitoring effort allows for the release of Restoration Flows within seepage limitations while seepage projects are completed. These projects can be realty transactions or physical projects. The SJRRP continues to monitor and evaluate the need for any seepage projects to achieve the Settlement objective of 4,500 cfs capacity throughout the Restoration Area.
San Joaquin River Spawning Surveys
US Fish and Wildlife Service
The San Joaquin River Restoration Program has been working to establish a spring-run Chinook salmon (SRCS) population to the San Joaquin River. The SRCS population was extirpated from the San Joaquin River upstream of the Merced River confluence when anthropogenic events degraded and blocked access to their historical spawning habitat. The San Joaquin River Restoration Program has released adult SRCS annually since 2016, to assess spawning success, and promote species reintroduction. Two important aspects to assessing spawning success are documenting redd creation and the quality of spawning habitat used by SRCS within the San Joaquin River Restoration Area. The U.S. Fish and Wildlife Service and California Department of Fish and Wildlife have documented 377 redds over the past 6 years. These spawning events were the result of various reintroduction strategies including releases of ancillary adult broodstock, returning adults that were trapped, hauled, and released into Reach 1 of the San Joaquin River Restoration Area, and volitionally returning SRCS. Here, we will discuss results and trends from these surveys and discuss the spatial and temporal variation of SRCS spawning, superimposition, and water temperatures from 2016 through 2022.
Adult Spring-run from the SJRRP Outside the Restoration Area
National Marine Fisheries Service
Have you ever wondered what happens to San Joaquin River Restoration Program (Program) fish after they have been released? We have! In 2018 NMFS gave a presentation about where Program juveniles have been found outside of the Restoration Area. Since then, the Program has evolved, and our fish have grown up. This year we plan to present the data NMFS has compiled about Program adults returning to the Program Area, observed in the ocean fishery, and throughout the Central Valley. Adult fish that return to the Central Valley contribute towards resiliency of the greater CV spring-run Chinook salmon population, which is essential to achieving the recovery goals outlined in NMFS’s 2014 Central Valley Salmonid Recovery Plan.
Juvenile Spring-Run Chinook Salmon Production, Survival, and Emigration in the San Joaquin River Restoration Area
Bureau of Reclamation
Survival at the juvenile life stage has been posited as a limiting factor towards the success of restoring spring-run Chinook salmon (Oncorhynchus tshawytscha) in the San Joaquin River Restoration Area (RA). As a means to monitor and evaluate juvenile salmon, rotary screw traps (RSTs) have been used for the past five sampling seasons (starting Fall 2017 through late Spring 2022) to monitor emigration from spawning grounds in Reach 1 of the RA. Objectives of RST monitoring are to evaluate production, survival, and emigration timing in the RA, as well as environmental factors that may affect these metrics. Additionally, tissue samples collected from juveniles are submitted for genetic analyses; the results of which help identify family-specific production and the total number of adults contributing to production. Efforts thus far have been constrained to Reaches 1–2 of the RA. Limited catch rates at the most downstream RSTs in Reach 2 have precluded sampling any further downstream. Data from the five years of sampling efforts have provided annual estimates of reach-specific production and survival, length-at-date capture metrics, permitted a better understand of downstream survival in upstream Reaches of the RA, and give an indication of potential areas where future Restoration efforts may need to be focused to help achieve the Restoration Goal of re-establishing spring-run Chinook Salmon in the RA. In addition, data from these analyses have revealed the first instance of volitionally returning adult salmon to the RA, evidenced by captured progeny in 2017–18.
Vegetation Pilot Study
Bureau of Reclamation
Vegetative restoration will be an integral part of the SJRRP in Reach 2B and the Compact Bypass, functioning to stabilize soils and provide essential habitat components for aquatic and terrestrial species. Assessments of revegetation factors and species response is necessary to support revegetation design and planning, improve establishment rates, and increase cost efficiency. The goals of this study are to evaluate site-specific factors concerning revegetation success in Reach 2B, including baseline site conditions (soils, climate, herbivory and weed pressure, etc.), native plant establishment rates, and effects of irrigation regime and seeding/planting methods. Native plants evaluated in the study include 12 herbaceous (seeded) and 6 woody (transplanted) species. Control plots are also included to assess passive restoration. The study site was cleared and the woody species transplants were installed in Feb 2023. Seeding will be conducted in the fall of 2023.
Salmon Conservation and Research Facility Development
California Department of Fish and Wildlife
The Salmon Conservation and Research Facility (SCARF) concept began in 2008 in order to meet reintroduction needs for the San Joaquin River Restoration Program. As early design and environmental review were underway, a smaller-scale interim SCARF (Interim Facility) was initiated in early 2010. By 2012 spring-run Chinook salmon were being raised at the Interim Facility to produce juveniles to seed the reintroduced population on the San Joaquin River. Since then, the Interim Facility has undergone incremental expansion to reach its present-day maximum production capacity of approximately 200,000 juveniles for release per year. In 2017, construction of the SCARF began and its completion is expected by late fall of 2023. While the interim facility is capable of producing approximately 200,000 juveniles for the program annually, the SCARF will be capable of producing approximately 1 million juveniles annually. An update of SCARF construction and a discussion of the facility’s various components, functions, and capabilities are provided.
Captive Broodstock Management and Production for the San Joaquin River Restoration Program
California Department of Fish and Wildlife
The San Joaquin River Restoration Program (SJRRP) captive broodstock effort began in the fall of 2012 when 560 eggs were collected from adult spring-run Chinook salmon returning to the Feather River Hatchery (Oroville, California). These eggs were then transferred to and raised at the Interim Salmon Conservation and Research Facility (Interim Facility) in Friant, California where they were spawned starting in 2015. For more than a decade, the Interim Facility has successfully worked with five generations of spring-run Chinook salmon, resulting in the production and release of over 1.35 million juveniles and 28,000 yearlings to the San Joaquin River (SJR). Additionally, the SJRRP has trapped and transported over 150 returning adult salmon, observed over 500 adults volitionally return to the SJR and local tributaries, and released nearly 1,000 mature adult broodstock to the SJR for research purposes and to allow them to spawn naturally in the river.
The presentation will describe the process for managing and spawning the captive broodstock population. This process is highly regulated to ensure that sufficient genetic diversity is maintained, which is critical for sustaining this progenitor population. The presentation will also detail plans for scaling up production in the new hatchery and discuss other potential donor stocks.
Growth of juvenile Chinook Salmon; transition from yolk to prey sources of energy, carbon, and nitrogen
Yugjeet Grewal(1), and Steve Blumenshine(2)
Affiliations: (1)College of Science and Mathematics, CSU Fresno; (2)Department of Biology, CSU Fresno
San Joaquin River Restoration Program was started in 2006 to create water flows that can restore a naturally reproducing and self-sustaining population of Chinook salmon. The Blumenshine lab collaborates with the SJRRP and plays an important part in salmon restoration by studying the interactions between juvenile Chinook and their environment, including trophic (feeding) interactions. Carbon (δ13C) and nitrogen (δ15N) stable isotope analyses (SIA) are widely used in aquatic ecology to understand the trophic interactions of fish because the stable isotope signatures of fish closely resemble that of their prey. We processed juvenile Chinook salmon samples from the San Joaquin River over three years from 2019-2022 as well as samples from a control group; hatchery-raised Kokanee trout that were fed on a consistent hatchery diet for SIA. We dissected, dried, encapsulated, and shipped dorsal muscle tissue samples to the UC Davis Stable Isotope Facility for dual δ13C and δ15N SIA. Analysis of the river Chinook stable isotope data showed abnormally high δ15N values for smaller and recently hatched fish that decreased quickly as the size of the fish increased and then remained fairly flat, thus showing an apparent relationship between fish size and δ15N values. We hypothesize that the high δ15N values in recently hatched Chinook can be attributed to the distinct stable isotope signature of yolk derived from the maternal sources. However, the stable isotope data from hatchery-fed Kokanee showed no relationship between δ15N and size probably because the maternal tissue was also derived from the same diet. We will use the results from this study to inform our selection of viable individuals for studying trophic interactions in the future.
San Joaquin River Restoration Program Adult Spring-Run Chinook Salmon Trap and Haul 2019-2022
Zachary Sutphin and Shaun Root
Bureau of Reclamation
A goal of the San Joaquin River Restoration Program is to restore and maintain fish populations in “good condition” in the mainstem San Joaquin River (SJR) downstream of Friant Dam to the confluence with the Merced River (i.e., Restoration Area [RA]) including naturally reproducing and self-sustaining populations of salmon and other fish (Restoration Goal). To facilitate reestablishment of spring-run Chinook salmon within the RA, the U.S. Fish and Wildlife Service was permitted by the National Marine Fisheries Service under the authority of section 10(a)(l)(A) of the Endangered Species Act to conduct direct releases of juvenile spring-run Chinook Salmon (Oncorhynchus tshawytscha) from Feather River stock into the SJR with the intent of having returning adults fulfilling their life cycle. Since the reintroduction of spring-run Chinook Salmon has started prior to completion of construction projects designed to improve fish passage at barriers, adult salmon trap and haul efforts are necessary to (1) ameliorate the effects of existing passage barriers on reestablishment, (2) fulfill the monitoring and management requirements associated with the Program’s section 10(a)(l)(A) permit, and (3) provide data to help direct a variety of critical adaptive fishery management decisions. Adult spring-run Chinook Salmon trap and haul has been completed annually since 2019 and constitutes capturing fish with fyke traps and nets in the lower reaches of the RA and subsequently truck-transporting individuals for release in the reaches upstream of passage barriers. Since inception, 184 adult spring-run Chinook Salmon have been captured (2019 = 23, 2020 = 57, 2021 = 93, 2022 = 11) and 152 fish released into Reach 1 of the RA (2019 = 20, 2020 = 48, 2021 = 74, 2022 = 10). This provided access to suitable spawning habitat, and also contributed to additional monitoring efforts to assess over summer holding, pre-spawn mortality, egg-to-fry survival, and juvenile production, emigration, and survival.
San Joaquin River Restoration Program Steelhead Monitoring Plan
Shaun Root, Zachary Sutphin and Jarod Hutcherson
Bureau of Reclamation
The Central Valley (CV) steelhead Distinct Population Segment (DPS) includes naturally spawning populations of steelhead (Oncorhynchus mykiss) and their progeny, in the Sacramento and San Joaquin Rivers and their tributaries and is protected as threatened under the U.S. Endangered Species Act. Central Valley steelhead are currently extirpated from all waters upstream of the Merced-San Joaquin River (SJR) confluence. However, Restoration and irrigation return flows could attract adult steelhead into the Restoration Area where current passage barriers would exclude fish from suitable spawning habitat. In coordination with the National Marine Fisheries Service (NMFS), the U.S. Bureau of Reclamation (Reclamation) began implementing an annual Steelhead Monitoring Plan (SMP) in 2012 to facilitate the detection of steelhead in the SJR, upstream of the Merced River confluence, and transport to suitable habitat downstream. These efforts will inform future decisions on take coverage requests during the ESA Section 7 process for Program-related activities. Since inception, SMP occurred 2012–14 and 2017–23, annually. Sampling was generally completed two weeks a month, from December–April, when environmental conditions were suitable. Sampling gear included raft electrofishing, fyke traps and nets, and trammel nets. To date, no steelhead have been captured. During this time a total of 7,992 fish, comprising 34 species, have been captured during SMP activities in downstream reaches of the Restoration Area (RA), to include connecting sloughs (Mud and Salt Slough, and Eastside Bypass). Once captured, species and length were recorded, and the fish released back into the SJR. If a CV steelhead was captured, the fish would have been relocated to suitable locations downstream of the RA, and Reclamation would have initiated consultation with NMFS.
It Isn’t Easy Being Green in the San Joaquin: Green Sturgeon Considerations in the San Joaquin River System
Annalisa Tuel(1), Jake Rennert(2), Hilary Glenn(2), Meiling Colombano(2)
Affiliations: (1)Contractor with Environmental Assessment Services in support of NOAA Fisheries; (2)National Marine Fisheries Service
This poster will discuss: 1) the life cycle of green sturgeon and the threats they face; 2) known presence and occurrence in the San Joaquin River basin, and; 3) scientific information on sturgeon passage considerations. The southern Distinct Population Segment (sDPS) of North American green sturgeon (Acipenser medirostris) was listed as threatened under the Endangered Species Act in 2006 because of precipitous declines in abundance and ongoing freshwater habitat degradation, including inaccessibility of spawning, rearing, and feeding habitat. Green sturgeon are ancient, long-lived fish-dinosaurs whose life cycle depends on having accessibility to large areas of freshwater habitat to spawn, rear, and feed. Their unique lifecycle makes the species vulnerable to threats such as impassable barriers, altered flows, entrapment, and environmental stressors. Their presence in the San Joaquin River basin has been documented in the recent past and will likely continue to occur in the future. Federal and state agencies in the California Central Valley should prioritize opportunities to ameliorate habitat degradation by supporting fish passage projects that improve green sturgeon accessibility to spawning and rearing habitats. NMFS’s 2018 green sturgeon recovery plan, the 2021 5-Year Status Review, and sturgeon passage considerations should be used to help guide biologists, engineers, and natural resource managers in designing habitat improvement projects in the San Joaquin River basin.
Are Macrophytes Positively Contributing to Fish in the SJR? : Modeling Juvenile Chinook Salmon Prey Sources and Monitoring Macrophyte Habitat Use
The Blumenshine Aquatic Ecology Lab at CSU-Fresno has been working on a two phase conceptual model in order to accurately model juvenile Chinook salmon (Oncorhynchus tshawytscha) growth and survival over space and time in Reach 1A. The first phase consists of combining empirical approaches of habitat attributes relevant to juvenile Chinook production with simulations in phase two including drone images and spatial models, bioenergetics models, habitat simulations, and stable isotope mixing models.. As part of this funded research my MS Thesis project aims to explore juvenile Chinook salmon (JCS) use of macrophyte beds within Reach 1A of the San Joaquin River through patterns of stable isotope ratios & macrophyte habitat observations. Macrophytes have habitat attributes such as having lower water velocity, reducing maximum water temperatures, increasing habitat structure, supporting larger invertebrate taxa, and supporting more macroinvertebrates than the surrounding open water. Which may make macrophytes an ideal microhabitat for supporting the bioenergetic needs of fish species including juvenile Chinook salmon. I will present preliminary data from stable isotope analyses as well as raw footage from macrophyte video observations.
Sediment Bedload Transport Downstream of a Concrete Gravity Dam
How sediment moves downstream of the San Joaquin River under Friant Dam is still being determined. There are five sites downstream of Friant Dam where sediment samples are collected. At each of these five sites data is collected by river cross sections. The river cross sections also include a pebble and vegetative count. Also, sediment accumulation data is collected by both a Helly Smith Bedload Sampler and Nalgene bottles. The information collected will describe how bedload sediment is moving downstream of Friant Dam, and the current river structures present. The project will highlight the bedload conditions present in Chinook salmon spawning habitat.
Fine Sediment Sources and Mobilization of Sand Downstream of Friant Dam within San Joaquin River Spring-Run Chinook Spawning Reach, California
Trent Sherman(1), Erin Bray(1), Smokey Pittman(2), and Scott McBain(2)
Affiliations: (1)Department of Earth and Climate Sciences, San Francisco State University; (2)McBain Associates-Applied River Sciences
The upper 7 miles of the mainstem San Joaquin River (SJR) is expected to be the primary spawning and egg incubation reach for spring-run Chinook salmon. However, the habitat quality is negatively impacted due to significant in-channel sand storage that clogs the gravel bed and reduces hyporheic exchange, thereby reducing salmon egg-to-emergence success. Given that the coarse sediment supply from upstream was disconnected by Friant Dam in the mid-1940s, several questions exist regarding the source of large volumes of in-channel fine sediment storage and the extent to which fine sediment is evacuated from the reach. We implemented a cataraft-based bedload sampling field campaign during winter of Water Year 2023 on the mainstem SJR and Cottonwood Creek (CTK) during flood flows. Preliminary results show that (1) sand is transporting at flows of 6,700 cubic feet per second (cfs) on the SJR, (2) a preliminary sedigraph for CTK suggests that 65 tons of sand were transported over a 2-day period at flows ranging from 160 to 470 cfs, (3) hysteresis was observed in CTK sand transport, potentially due to changes in a backwater effect from the SJR, and (4) the highest sand transport rates along the SJR channel transect did not occur where flow velocity was highest. These results raise questions about how effective is the SJR at flushing the sand supplied by CTK, where this in-channel stored sand is coming from, how management actions can reduce sand storage in the spawning reach to increase salmon fry-to-emergence success, and how high flows can be more effective in flushing fine sediment from the mainstem SJR. Future sediment sampling across a greater range of flows is needed to better constrain sand supply from CTK to the SJR, and sediment sampling downstream of Little Dry Creek (LDC) is needed to estimate fine sediment supply from LDC.
Spring-run Chinook Salmon Egg Survival and Fry Emergence in the San Joaquin River Restoration Area
Nicholas Fischer(1), Austin Demarest(1), and Andy Shriver(2)
Affiliations: (1)U.S. Fish and Wildlife Service; (2)California Department of Fish and Wildlife
The US Fish and Wildlife Service and California Department of Fish and Wildlife have conducted spawning surveys since spring-run Chinook Salmon releases to the Restoration Area began in 2016, with the purpose of assessing spawning and incubation success in Reach 1. These surveys can help the San Joaquin River Restoration Program identify the quantity and quality of spawning habitat, inform the Restoration Administrator for Restoration Flow management, and guide potential habitat restoration (e.g., gravel augmentation projects). Starting in 2018, salmon fry have been captured in emergence traps on select redds to enumerate emerged fry, estimate egg-to-fry survival, and document incubation timing. A total of 34 redds have been capped with emergence traps with a total fry count of 13,346 . This poster will present results from 2018 through 2021 but will be focused on the trapping efforts that have occurred since we last presented at the 2020 Science Meeting. In 2021, emergence traps were placed on seven redds, with a total emergence of 2,874 fry. It can be difficult to document the spawner identity (i.e., ocean returners versus broodstock released spawners) of a redd when selecting a redd for trapping. Therefore, based on the seven monitored redds, egg-to-fry survival per redd ranged from 0 to 58.8 percent (using the average Salmon Conservation and Research Facility broodstock fecundity), and from 0 to 28.5 percent (using the average Feather River Fish Hatchery fecundity). Results from forthcoming genetic analyses will identify the parentage of emerged fry that were sampled and allow for inferences to be made on the performance of various release strategies. In 2021, fry emerged slightly earlier and at lower developmental stage on average than in prior years, but still fell within expected incubation timing. No redds were trapped in 2022.
Multi-benefit restoration at a former 900- acre gravel quarry: River Rock Mitigation Bank
Geoff Smick1, Michael Linton(2), Virginia Mahacek(1), Nathan Bello(1), and Andrew Smith(1)
Affiliations: (1)WRA, Inc.; (2)Vulcan Materials
River Rock is a former 900-acre gravel mine on the south bank of the San Joaquin River, 8 miles downstream from Friant Dam and 1 mile upstream of Hwy. 41 (Reach 1a). The operator, Vulcan Materials, is planning a multibenefit project that includes stream and riparian habitat restoration and recreation benefits. The project concept includes regrading over 700 acres to expand the floodplain and create new side channels resulting in over 500 acres of new floodplain and riparian habitat. The current design has over 200 acres of floodplain that would be inundated with flows of 1,400 cfs. While the majority of the historic mining pits would be regraded, the two largest pits will remain and be used primarily for recreation.
The San Joaquin River Conservancy owns approximately 1/3rd of the property and is a project proponent making this a great example of a public private partnership. The San Joaquin River Parkway and Conservation Trust also owns several inholdings and is a project proponent that would manage the recreation aspects of the project. While the scale of the project is impressive, it requires considerable earthwork (>4.5M cy). By creating a mitigation bank, the project sponsor can fund and implement the project with reduced financial risk. An added benefit of the project as a mitigation bank includes the establishment of a management plan and endowment to ensure the project functions well into the future.
The current grading concept was developed to minimize fish stranding and to support habitat elements of the experimental population of spring-run chinook. The project proponents are eager to receive feedback from SJRRP member agencies and experts on various aspects of the project including habitat elements, salmonid issues, and the potential for other multibenefit uses such as flood abatement and groundwater recharge.
Striped Bass in the San Joaquin River Restoration Area: Population and Bioenergetics Modeling
Jeremy Hammen, Meghan White, Zak Sutphin
Bureau of Reclamation
The San Joaquin River Restoration Program (SJRRP) aims to establish sustainable Chinook salmon (Oncorhynchus tshawytscha) populations within the mainstem San Joaquin River below Friant Dam to the confluence of the Merced River (referred to as the Restoration Area). Predation of juvenile salmon is identified as a “critical stressor” to the population within the San Joaquin River and the SJRRP’s success. Non-native Striped Bass (Morone saxatilis) are the dominant piscivore within the Restoration Area and have well-established populations throughout the San Joaquin/Sacramento Delta and adjacent rivers systems. Passive Integrated Transponder (PIT) tagged Striped Bass recaptured during Winter/Spring seasons of 2019/2020 and 2020/2021 SJRRP Steelhead Monitoring and Adult Trap and Haul projects were used to generate population and bioenergetics models. Striped Bass population estimations were generated with RMark using the POPAN model for open populations that is based on the Jolly-Seber method using the MLogit link function. Results from the Striped Bass population model, parameters from published literature, and morphometric data from captured Striped Bass within the lower reaches of the Restoration Area and juvenile Chinook Salmon from the upper reaches of the Restoration area were used to develop a bioenergetics model (Fish Bioenergetics 4.0) using proportion of maximum consumption (Cmax) to estimate predation impacts on emigrating juvenile salmon. Results suggests that the population of Striped Bass population within the Restoration Area peaks during juvenile salmon emigration and could result in a loss of 9,500 to 95,000 Chinook Salmon between January and May. During most months, Striped Bass appear to be operating at maximum metabolic efficiency, but reductions in water temperature could decrease salmon consumption. Results from these preliminary models help describe the potential impact of Striped Bass to native fish, like juvenile salmon, and highlight the value of increased data collection to improve the accuracy and relevance of these models.