Effects of Environmental Conditions during Stream, Estuary, and Ocean Residency on Chinook Salmon Return Rates in the Skagit River, Washington

Greene, Correigh M.; Jensen, David W.; Pess, George R.; Steel, E. Ashley; Beamer, Eric M.

doi:10.1577/t05-037.1

Cited by 64 publications

(79 citation statements)

References 62 publications

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“…Nevertheless, our results consistently showed that in the Lemhi River, flow variables had stronger explanatory power than climate predictors, corroborating some studies that have detected higher covariation in life-cycle production at subbasin rather than basinwide scales (Schaller et al, 1999;Botsford & Paulsen, 2000;Deriso et al, 2001). Studies that have included flow as well as climate signals in the context of the life cycle have also shown strong effects of flow (e.g., Greene et al 2005). Models of single spawning populations with long time series that can disentangle effects of flow from other environmental variables are clearly needed to evaluate the influence of hydromodification against the backdrop of climate variation at multiple life stages.…”

Section: Discussionsupporting

confidence: 89%

Contrasting life-cycle impacts of stream flow on two Chinook salmon populations

et al. 2010

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Stream flow affects many aspects of freshwater fish biology, but the extent to which variation in stream flow influences productivity of anadromous salmonid populations across their entire life cycle is not well known. We compared relationships of stream flow and productivity for Chinook salmon (Oncorhynchus tshawytscha) from two systems in the Salmon River basin in Idaho: the Lemhi River, a watershed subjected to intensive water use for irrigation, and Marsh Creek, a drainage with a natural hydrograph. We estimated rates of productivity based on monitoring at four life stages: the number of eggs initiating each cohort, juveniles migrating from the natal tributary past an outmigrant trap, smolts surviving to the Snake River, and adults returning to spawn. Using model selection techniques, we examined whether river flow experienced during these life stages explained variation above and beyond predictors of climate associated with each stage. In the Lemhi River, tributary stream flow during early residence exhibited strong correlations with egg-trap, egg-smolt, and egg-adult return rates, and was consistently a better predictor of productivity than stream flow occurring during late summer. Model selection indicated that early rearing flow was the single best predictor of both egg-trap and trap-smolt transition rates in the Lemhi River, and path analysis revealed a strong set of pathways linking rearing flow to adult return rate primarily through egg-trap productivity. These patterns were much less strongly exhibited or nonexistent in Marsh Creek. However, for both populations, migration flow in the Columbia River was the best predictor of smolt-adult return rates. Potentially confounding climatic variables exhibited relatively weak effects upon both early life histories and tributary flow, but were included in the best models of migration flows and smolt-adult return rate. These results suggest that effects of stream flow on juvenile salmonids in flow-altered systems can have substantial impacts on returning adults.

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Section: Discussionsupporting

confidence: 89%

Contrasting life-cycle impacts of stream flow on two Chinook salmon populations

et al. 2010

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“…Seiler et al (2003) found that the annual incubation flood magnitude was a significant predictor of freshwater survival rates for Skagit River chinook salmon, wherein larger floods resulted in smaller survival rates. Greene et al (2005) found that the annual flood magnitude was a strong predictor of total lifecycle return rates for Skagit River chinook salmon. These findings could result from several different mechanisms linking peak incubation flows to early freshwater life-stage survival rates for salmon.…”

Section: Model Validation and Applicationmentioning

confidence: 96%

Climate change impacts on streamflow extremes and summertime stream temperature and their possible consequences for freshwater salmon habitat in Washington State

2010

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This study evaluates the sensitivity of Washington State's freshwater habitat of Pacific Salmon (Oncorhynchus spp.) to climate change. Our analysis focuses on summertime stream temperatures, seasonal low flows, and changes in peak and base flows because these physical factors are likely to be key pressure points for many of Washington's salmon populations. Weekly summertime water temperatures and extreme daily high and low streamflows are evaluated under multimodel composites for A1B and B1 greenhouse gas emissions scenarios. Simulations predict rising water temperatures will thermally stress salmon throughout Washington's watersheds, becoming increasingly severe later in the twenty-first century. Streamflow simulations predict that basins strongly influenced by transient runoff (a mix of direct runoff from cool-season rainfall and springtime snowmelt) are most sensitive to climate change. By the 2080s, hydrologic simulations predict a complete loss of Washington's snowmelt dominant basins, and only about ten transient basins remaining in the north Cascades. Historically transient runoff watersheds will shift towards rainfall dominant behavior, undergoing more severe summer low flow periods and more frequent days with intense winter flooding. While cool-season stream temperature changes and impacts on salmon are not assessed in this study, it is possible that climate-induced warming in winter and spring will benefit parts of the freshwater life-cycle of some salmon populations enough to increase their reproductive success N. Mantua · I. Tohver · A. Hamlet 188 Climatic Change (2010) 102:187-223 (or overall fitness). However, the combined effects of warming summertime stream temperatures and altered streamflows will likely reduce the reproductive success for many Washington salmon populations, with impacts varying for different life historytypes and watershed-types. Diminishing streamflows and higher stream temperatures in summer will be stressful for stream-type salmon populations that have freshwater rearing periods in summer. Increased winter flooding in transient runoff watersheds will likely reduce the egg-to-fry survival rates for ocean-type and stream-type salmon.

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“…This low-level salinity environment (<15 ppt) are very suitable for fish migratory pathways in estuaries [3,26,27] and can increase fish return rate into Skagit River. For example, Greene et al [28] suggested that freshwater and nearshore environmental conditions are the main controlling factors of the survival rate of Skagit River Chinook salmon. …”

Section: Discussionmentioning

confidence: 99%

Sediment Transport into the Swinomish Navigation Channel, Puget Sound—Habitat Restoration versus Navigation Maintenance Needs

Khangaonkar

Nugraha

Hinton

et al. 2017

JMSE

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Abstract:The 11 mile (1.6 km) Swinomish Federal Navigation Channel provides a safe and short passage to fishing and recreational craft in and out of Northern Puget Sound by connecting Skagit and Padilla Bays, US State abbrev., USA. A network of dikes and jetties were constructed through the Swinomish corridor between 1893 and 1936 to improve navigation functionality. Over the years, these river training dikes and jetties designed to minimize sedimentation in the channel have deteriorated, resulting in reduced protection of the channel. The need to repair or modify dikes/jetties for channel maintenance, however, may conflict with salmon habitat restoration goals aimed at improving access, connectivity and brackish water habitat. Several restoration projects have been proposed in the Skagit delta involving breaching, lowering, or removal of dikes. To assess relative merits of the available alternatives, a hydrodynamic model of the Skagit River estuary was developed using the Finite Volume Community Ocean Model (FVCOM). In this paper, we present the refinement and calibration of the model using oceanographic data collected from the years 2006 and 2009 with a focus on the sediment and brackish water transport from the river and Skagit Bay tide flats to the Swinomish Channel. The model was applied to assess the feasibility of achieving the desired dual outcome of (a) reducing sedimentation and shoaling in the Swinomish Channel and (b) providing a direct migration pathway and improved conveyance of freshwater into the Swinomish Channel. The potential reduction in shoaling through site-specific structure repairs is evaluated. Similarly, the potential to significantly improve of brackish water habitat through dike breach restoration actions using the McGlinn Causeway project example, along with its impacts on sediment deposition in the Swinomish Navigation Channel, is examined.

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Effects of Environmental Conditions during Stream, Estuary, and Ocean Residency on Chinook Salmon Return Rates in the Skagit River, Washington

Cited by 64 publications

References 62 publications

Contrasting life-cycle impacts of stream flow on two Chinook salmon populations

Contrasting life-cycle impacts of stream flow on two Chinook salmon populations

Climate change impacts on streamflow extremes and summertime stream temperature and their possible consequences for freshwater salmon habitat in Washington State

Sediment Transport into the Swinomish Navigation Channel, Puget Sound—Habitat Restoration versus Navigation Maintenance Needs

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