Event Title

Concurrent Sessions B: Case Studies of Passage at Dams - Restoration of Chinook Salmon in the South Fork Mckenzie River–Status of a Complex, Long-Term Dam Mitigation Effort

Location

Oregon State University

Start Date

27-6-2013 4:10 PM

End Date

27-6-2013 4:30 PM

Description

Construction of Cougar Dam in 1963 eliminated Chinook salmon Oncorhynchus tshawytscha from more than 85% of former habitat in the South Fork McKenzie River and reduced the productivity of river reaches downstream of the dam. Fisheries management changes and modifications to Cougar Dam during the past two decades included out-planting of adult hatchery-origin Chinook salmon (beginning in 1993), extreme reservoir drawdown during construction of a water temperature control facility (2002–2004), temperature control operations (2005), and operation of an upstream fish passage facility (2010). Downstream passage modifications for juvenile salmon are being planned. Here, we summarize data on adult salmon demographics, hatchery versus wild origin, pre-spawning mortality, and spawning distribution in relation to these modifications. We include data from spawning surveys, operation of the upstream passage facility, and out-planting of hatchery-origin adult salmon. Restoration of a run in the reach upstream of the dam is in its early stages, with at least 56 female and 135 male naturally produced salmon transported upstream in each of the past three years. Low replacement rates to date suggest that out-planting of adult hatchery-origin salmon will likely continue at least until downstream passage survival is improved to provide additional forage for resident fishes and to increase future returns of natural-origin adult salmon. The dynamic nature of this system and interaction of multiple factors affecting survival complicate detection of population responses to modifications, and continued monitoring will be essential for evaluating overall effectiveness of this effort.

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Jun 27th, 4:10 PM Jun 27th, 4:30 PM

Concurrent Sessions B: Case Studies of Passage at Dams - Restoration of Chinook Salmon in the South Fork Mckenzie River–Status of a Complex, Long-Term Dam Mitigation Effort

Oregon State University

Construction of Cougar Dam in 1963 eliminated Chinook salmon Oncorhynchus tshawytscha from more than 85% of former habitat in the South Fork McKenzie River and reduced the productivity of river reaches downstream of the dam. Fisheries management changes and modifications to Cougar Dam during the past two decades included out-planting of adult hatchery-origin Chinook salmon (beginning in 1993), extreme reservoir drawdown during construction of a water temperature control facility (2002–2004), temperature control operations (2005), and operation of an upstream fish passage facility (2010). Downstream passage modifications for juvenile salmon are being planned. Here, we summarize data on adult salmon demographics, hatchery versus wild origin, pre-spawning mortality, and spawning distribution in relation to these modifications. We include data from spawning surveys, operation of the upstream passage facility, and out-planting of hatchery-origin adult salmon. Restoration of a run in the reach upstream of the dam is in its early stages, with at least 56 female and 135 male naturally produced salmon transported upstream in each of the past three years. Low replacement rates to date suggest that out-planting of adult hatchery-origin salmon will likely continue at least until downstream passage survival is improved to provide additional forage for resident fishes and to increase future returns of natural-origin adult salmon. The dynamic nature of this system and interaction of multiple factors affecting survival complicate detection of population responses to modifications, and continued monitoring will be essential for evaluating overall effectiveness of this effort.