Science activities

Tradeoffs among objectives in natural resource management can be exacerbated in altered ecosystems and when there is uncertainty in predicted management outcomes. Multicriteria decision analysis (MCDA) and value of information (VOI) are underutilized decision tools that can assist fisheries managers in handling tradeoffs and evaluating the importance of uncertainty. We demonstrate the use of these tools using a case study in the Sacramento River, California, U.S.A., where two imperiled species with different temperature requirements, winter-run Chinook Salmon (Oncorhynchus tshawytscha) and Green Sturgeon (Acipenser medirostris), spawn and rear in the artificially cold Shasta Dam tailwater. A temperature-control device installed on Shasta Dam maintains cool water for Chinook Salmon; however, uncertainties exist related to the effects of temperatures on the spawning and rearing of both species. We consider four alternative hypotheses in models of early life-stage dynamics to evaluate the effects of alternative temperature-management strategies on Chinook Salmon and Green Sturgeon management objectives. We used VOI to quantify the increase in management performance that can be expected by resolving hypothesis-based uncertainties as a function of the weight assigned to species-specific objectives. We found the decision was hindered by uncertainty; the best performing alternative depends on which hypothesis is true, with warmer or cooler alternative management strategies recommended when weights favor Green Sturgeon or Chinook Salmon objectives, respectively. The value of reducing uncertainty was highest when Green Sturgeon was slightly favored, highlighting the interaction between scientific uncertainty and decision makers’ values. Our demonstration features MCDA and VOI as transparent, deliberative tools that can assist fisheries managers in confronting value conflicts, prioritizing resolution of uncertainty, and optimally managing aquatic ecosystems.

This project aims to test the feasibility of using novel acoustic transmitters to track Delta smelt in the San Francisco Bay-Delta. Successful utilization of acoustic telemetry to track Delta smelt can provide researchers and resource managers with information about the species’ habitat preferences, the effects of water-management practices on Delta smelt movement and distribution, and the success of ongoing supplemental release efforts. The assessment of feasibility will include a comprehensive analysis of both the lethal and sublethal effects of surgical tag implantation on Delta smelt, as well as the development of a species-specific tagging protocol.

The San Francisco Estuary (SFE) supports the southernmost reproductive population of longfin smelt (LFS) along the Pacific Coast. Long term monitoring studies have observed a precipitous decline of LFS in the SFE over the past several decades, and the San Francisco Bay-Delta Distinct Population Segment was listed as endangered under the Endangered Species Act in July of 2024. There are important gaps in our understanding of LFS ecology and movement within the highly urbanized SFE, posing challenges to the development of effective recovery strategies. More complete information about the movement and migration of LFS in the wild can lead to improved life-cycle modeling and provide insight into the species’ relationship with temperature, salinity and other habitat features of the SFE. An effective tool to learn about fish migration and movement is through a tracking method known as acoustic telemetry. Until recently this practice has been impossible on small fish such as LFS due to their body size relative to existing acoustic transmitters, or ‘tags’. With recent advances in telemetry technology, we now have an opportunity to implant newly miniaturized acoustic transmitters into adult LFS. However, before the results of telemetry studies utilizing these newly developed transmitters can be used to make inferences about wild populations, it is imperative to determine whether the tagged individuals are surviving and behaving in the same way as their un-tagged counterparts. The study aims to establish post-tagging survival and transmitter retention rates of wild and captive-reared LFS surgically implanted with newly miniaturizes acoustic transmitters, as well as the sublethal effects of transmitter implantation on LFS swimming performance. The results of this study will directly inform the implementation of acoustic telemetry on LFS, aiding in the conservation and recovery of an imperiled native species.

SacPAS serves to provide information integration services to the Central Valley Project Improvement Act and practitioners working on matters related to ESA-listed fishes. The web-based services relate fish passage to environmental conditions and provide resources for evaluating the effects of river management and environmental conditions on salmon passage and survival.

The work performed as part of this agreement includes developing, maintaining, and making accessible query tools and decision support tools to access: historical, real-time and forecasted data; data summaries and visualizations; and hindcasts, forecasts, and scenario-derived predictions from statistical and mechanistic models. More specifically, the objectives are to: 

1)    Maintain and extend a secondary data repository of historical, real-time, and forecasted fish, environmental, and operational data from the Sacramento River and other river systems in the Central Valley, integrated from primary, public databases. 

2)    Maintain and improve the data query and visualization tools and services provided through the SacPAS website (https://www.cbr.washington.edu/sacramento/) for historical, real-time, and forecasted environmental and fish data.

3)    Conduct research and provide access to modeling tools for fish survival and migration, through the SacPAS website, in support of Reclamation-funded and ESA-mandated activities, especially in efforts to predict, track, and evaluate the efficacy of proposed or actual actions.