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Regional Back Ground
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Project 199102900 began in 1991 to provide some of the first biological data on the contemporary population of fall Chinook salmon Oncorhynchus tshawytscha in the Snake River basin that was eventually listed in 1992 under the Endangered Species Act as the Snake River fall Chinook salmon evolutionary significant unit (ESU). Up until 2018, the project was implemented cooperatively by staff of the U.S. Fish and Wildlife Service and the U.S. Geological Survey. In 2018, the USGS assumed primary sponsorship of the project. As in past years, the project continue to complement and be coordinated with existing Snake River fall Chinook salmon ESU projects including staff of Idaho Power Company, the Nez Perce Tribe Department of Fisheries Resources Management, National Oceanographic and Atmospheric Administration, University of Idaho, and Washington Department of Fish and Wildlife.

The 2008 Biological Opinion and RPA have received much attention from the resources management community in the Pacific Northwest.  Most recently it was reviewed by the Obama Administration.  This review led to an Adaptive Management Implementation Plan (AMIP).  A full review of the AMIP is beyond the scope of this back ground statement, but it builds on the 2008 Biological Opinion and parallels and supports the other regional actions outlined above.  The AMIP advocates collecting more data and improving analytic tools to better inform future adaptive management decision making.  It calls for enhanced research on salmon predators and invasive species including a determination of whether removals of smallmouth bass in areas of intense predation could reduce the mortality of juvenile salmonids.  It supports enhanced RM&E actions to fill data gaps including: adult status and trend monitoring, juvenile status and trend monitoring, and the development of expanded life-cycle and passage models.  Project staff will be actively involved in the AMIP process.

We will also summarize historical data and collect new data to make progress towards answering two questions posed in the Monitoring, Evaluation, Research and Reporting plan: (1) is the ESU abundant, diverse, productive, and spatially distributed; and (2) is the ESU responding to implemented actions as anticipated?  We recast these two questions as regional objectives: (1) increase the abundance, productivity, and spawning distribution of natural origin adults, and (2) increase the abundance and diversity of natural-origin subyearlings during early freshwater rearing and migration.  The success criteria for regional objective 1 will be: (1) an increased understanding of the anthropogenic, biological, and environmental factors that influenced historical and contemporary trends in adult abundance, (2) an increased understanding of how varying influential anthropogenic, biological, and environmental factors might facilitate meeting the minimum viability threshold, and (3) documentation of the status of escapement of natural-origin adults to the spawning areas relative to the explicit population level spatial structure criteria, and (4) support for expanded life-cycle and passage modeling.  The success criteria for objective 2 will be: (1) estimates of passage abundance for natural-origin fall Chinook salmon subyearlings at Lower Granite Dam during the spring, summer, and fall, (2) an increased understanding of the anthropogenic, biological, and environmental factors that influence trends in passage abundance, (3) an increased understanding of how varying influential anthropogenic, biological, and environmental factors might increase passage abundance of natural-origin fall Chinook salmon subyearlings, (4) an increased understanding of the effect of predation in riverine habitat on passage abundance of natural-origin fall Chinook salmon subyearlings, and (5) support for expanded life-cycle and passage models.

We will accomplish the regional objectives by accomplishing several scientific objectives each of which will produce final deliverables including models to support the AMIP process.


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Regional Objective 1 Final Deliverables
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Final deliverable 1A will be a set of models that provide a historical retrospective of adult abundance and spawning distribution that will rely on adult counts made without distinction of adult origin, but with redd counts made throughout the Snake River basin from 1947 to 2018. These models will accomplish the following scientific objectives: (1) describe the numerical trends in the adult counts, (2) describe the numerical and spatial trends in redd counts; (3) evaluate changes in the ability to use redd counts as accurate and precise predictors of adult counts, and (4) increase the understanding of how the numerical trends in the adult counts were influenced by anthropogenic, biological, and environmental change. In 2021, we will add to our existing adult data set to address these objectives. The models and continued analysis of adult productivity through empirical data collection and life-cycle modeling will help complete regional objective 1 success criterion 1.

Final deliverable 1B will be a second set of models that help to explain and predict increases in the abundance, productivity, and spawning distribution of natural origin adults by focusing on estimated counts of natural-origin adults at Lower Granite Dam from run construction and on redd counts made upstream of Lower Granite Reservoir after 1982 (or as early as possible depending on data availability).  It will accomplish the following scientific objectives: (1) increase the understanding of how the numerical trends in the estimated counts of natural-origin adults during 1983–2020 were influenced by anthropogenic, biological, and environmental change, (2) predict how varying influential anthropogenic, biological, and environmental factors might affect the status of natural-origin adults relative to the minimum viability threshold, and (3) predict the status of escapement of natural-origin adults to the spawning areas relative to the explicit population level spatial structure criteria.  

One of the recovery measures recently implemented for the Snake River fall Chinook salmon population was the creation of a natural production area in the upper reach of Hells Canyon above Pittsburg Landing. The intent of this action is to create a stronghold for natural-origin adults in this area. In 2018, hatchery supplementation releases were moved from Hells Canyon Dam to the Salmon River. With less hatchery influence, the area is expected to see an increase in natural-origin fish. To monitor the effectiveness of this action, project staff along with Idaho Power Company staff have been collecting tissue samples from spawners in this reach and using parentage analysis to determine the proportions of hatchery and natural-origin spawners. This is an important metric for NOAA Fisheries to gauge the effectiveness of this action.

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Regional Objective 2 Final Deliverables
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Final deliverable 2A will be set of models that help to explain and predict variation in passage abundance of natural-origin subyearlings at Lower Granite dam during 1992–2018. The scientific objectives will be to: (1) describe numerical trends in passage abundance of natural-origin fall Chinook salmon subyearlings estimated by reconstructing the run; (2) compare annual passage timing distributions calculated using different methods, (3) increase the understanding of how the numerical trends in passage abundance were associated with anthropogenic, biological, and environmental change, (4) use the results from scientific objectives 1 and 2 to predict how varying influential anthropogenic, biological, and environmental factors might increase abundance of natural-origin fall Chinook salmon subyearlings. By adding new PIT-tag data from our project and collected by our collaborators as it becomes available, we will strive to complete a journal manuscript describing the results before the end of 2021. The models and the manuscript will confirm completion of objective 2 success criteria 1, 2, and 3.

To accomplish this objective, project staff will continue annual PIT tagging efforts in the Snake River. In addition, we will begin PIT tagging fall Chinook in the Salmon River starting in 2021 to evaluate the effectiveness of the relocated Hells Canyon supplementation releases to the Salmon River. Any progeny collected will likely be from the return of 2-year old fish in 2020. This will be an important monitoring activity because it is closely related to the effectiveness of the natural production area in Hells Canyon.

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Monitoring Total Dissolved Gas Effects
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The regional variable spill program implemented in 2020 increases the total dissolved gas (TDG) cap from 120 to 125%. Under the 2020 Biological Opinion for the Federal Columbia River Power System, BPA is required to monitor the effects of increased TDG on native resident fishes. This will be a new task for project 199102900 that will begin in FY21. The tailrace areas of three projects (Bonneville, McNary, and one in the Snake River) will be sampled for resident fish during the spring spill season (April through June). Fish will be examined for gas bubble trauma (GBT) using regional protocols and weekly reports will be provided. 2021 will be treated as a pilot year to determine the best locations and sampling designs for moving forward in the future.