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.

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.
 

Chinook Salmon (Oncorhynchus tshawytscha) populations in California are in decline due to the combined effects of habitat degradation, water diversions, and shifting climate regimes. This project uses archival tissues (otoliths, vertebrae) from modern and ancient spring-run Chinook Salmon to understand how shifts in migration timing and habitat use allowed salmon to cope with highly variable environmental conditions. We will learn how salmon responded to the recent drought and flood periods (2012-2020 CE), the California Gold Rush Period (~1835-1870 CE), the Little Ice Age (~1560-1780 CE), and the Megadrought Period (~1200-1410 CE). This effort will provide the insights needed for developing climate-adapted conservation actions to support salmon into the future.