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• 1. [Article] Modeling Large Wood Impacts on Stream Hydrodynamics and Juvenile Salmon Habitat

  Large wood (LW) pieces are recognized as an important habitat component for salmon freshwater habitat. As such, they are often used in stream habitat restoration practices despite a lack of knowledge about ...

  Citation × Citation Citation Abstract Copy Title: Modeling Large Wood Impacts on Stream Hydrodynamics and Juvenile Salmon Habitat Author: Bair, Russell Large wood (LW) pieces are recognized as an important habitat component for salmon freshwater habitat. As such, they are often used in stream habitat restoration practices despite a lack of knowledge about their impacts on spatial and temporal hydraulic characteristics relevant to fish habitat. In this thesis we present results on the impacts of LW on reach scale stream hydraulics. We use hydraulic models to identifying patterns and magnitudes of change in aspects of the flow field that are relevant to juvenile Coho Salmon after an addition of LW. The Nays2DH model was used because of its capacity to model unsteady flows around LW structures in-stream. Flow conditions after LW addition were modeled in three alluvial plane bed gravel reaches of Mill Creek in the Oregon Coast Range, a long term salmon life cycle study site. Study streams are small, with a bankfull (Q[subscript bf]) discharge between 2.2 and 8.7 m³/s and bankfull widths varying from 5.5 to 10.6 m. Survivable habitat was characterized for the flow field in terms of a) velocity (v) less than critical swim speed of juvenile Coho Salmon (v[subscript crit] = 0.5 m/s); b) and bed refuge estimated based on the likelihood of the movement of the reach median bed particle size (D₅₀). Spatial and temporal increases in wetted area were also determined. After the addition of LW, the area of acceptable habitat increased 17-26% in terms of velocity, 31-39% in terms of substrate stability, and 24-35% in terms of wetted area at Q[subscript bf]. Similar magnitudes of increase were observed over an entire storm hydrograph in each site. Patterns of change in the flow field showed deep pools of slower water forming upstream of LW jams which agreed with initial field observations of geomorphic change. Newly inundated flood plains and bars represented large portions of the additional habitat after the addition of LW. These areas had low velocity and shear stress values indicating that their contributions to additional habitat will be resilient to fluctuation even if acceptable habitat metrics were to be adjusted. Title: Modeling Large Wood Impacts on Stream Hydrodynamics and Juvenile Salmon Habitat Author: Bair, Russell Large wood (LW) pieces are recognized as an important habitat component for salmon freshwater habitat. As such, they are often used in stream habitat restoration practices despite a lack of knowledge about their impacts on spatial and temporal hydraulic characteristics relevant to fish habitat. In this thesis we present results on the impacts of LW on reach scale stream hydraulics. We use hydraulic models to identifying patterns and magnitudes of change in aspects of the flow field that are relevant to juvenile Coho Salmon after an addition of LW. The Nays2DH model was used because of its capacity to model unsteady flows around LW structures in-stream. Flow conditions after LW addition were modeled in three alluvial plane bed gravel reaches of Mill Creek in the Oregon Coast Range, a long term salmon life cycle study site. Study streams are small, with a bankfull (Q[subscript bf]) discharge between 2.2 and 8.7 m³/s and bankfull widths varying from 5.5 to 10.6 m. Survivable habitat was characterized for the flow field in terms of a) velocity (v) less than critical swim speed of juvenile Coho Salmon (v[subscript crit] = 0.5 m/s); b) and bed refuge estimated based on the likelihood of the movement of the reach median bed particle size (D₅₀). Spatial and temporal increases in wetted area were also determined. After the addition of LW, the area of acceptable habitat increased 17-26% in terms of velocity, 31-39% in terms of substrate stability, and 24-35% in terms of wetted area at Q[subscript bf]. Similar magnitudes of increase were observed over an entire storm hydrograph in each site. Patterns of change in the flow field showed deep pools of slower water forming upstream of LW jams which agreed with initial field observations of geomorphic change. Newly inundated flood plains and bars represented large portions of the additional habitat after the addition of LW. These areas had low velocity and shear stress values indicating that their contributions to additional habitat will be resilient to fluctuation even if acceptable habitat metrics were to be adjusted. Close

• 2. [Article] Restoring the Columbia River Estuary : Chinook Salmon Recovery and Invasive Species Management

  As highlighted in this study, shallow-water habitats and the prey they provide are important for juvenile salmon in the Columbia River estuary, but the spread of invasive species and large-scale changes ...

  Citation × Citation Citation Abstract Copy Title: Restoring the Columbia River Estuary : Chinook Salmon Recovery and Invasive Species Management Author: Klopfenstein, Rachael As highlighted in this study, shallow-water habitats and the prey they provide are important for juvenile salmon in the Columbia River estuary, but the spread of invasive species and large-scale changes to the estuary influence how these habitats are utilized. Reed canarygrass (Phalaris arundinacea) (“PHAR” hereafter) is a highly invasive aquatic plant species that affects a number of emergent wetland habitats in the upper Columbia River estuary, and is of concern to those trying to restore important shallow-water habitats for juvenile salmon. The presence of PHAR undoubtedly reduces plant diversity, but this study seeked to elucidate how PHAR affects juvenile Chinook Salmon rearing success relative to natural emergent vegetation. The study further evaluated the importance of wetland-deriver prey to juveniles found in shallow-water habitats along a habitat gradient (i.e., back-water channel, confluence, and main stem). We conducted research at a floodplain wetland restoration site in the tidal-fluvial portion of the estuary, where a water control structure is used to manage water levels and the spread of PHAR. The goal of the research was to compare two microhabitats within the floodplain: areas dominated by PHAR and areas dominated by natural emergent vegetation. Using hatchery-raised juvenile Chinook salmon, we designed a series of feeding experiments in artificial enclosures to determine whether invasive PHAR and natural emergent vegetation provide similar foraging and growth opportunities for juvenile salmon. We further identified differences in physical and biological parameters of each habitat (e.g., temperature, dissolved oxygen, and invertebrate community) and examined feeding characteristics (e.g., diet composition and modeled growth rates) for juveniles through a stomach content analysis. Additionally, we conducted beach seining and diet analysis for fish collected along a habitat gradient and compared the diet composition and modeled growth rates between the sample areas. In the floodplain wetland, invertebrate prey compositions from the 2015-2016 (March- June) fallout and emergence traps were similar, but prey abundances and diversity varied seasonally. Across both years, for emergence traps, the average total density (per m²) of invertebrates in the natural vegetation and in PHAR was 154±18 m² and 225±34 m², respectively, and for the fallout traps was 664±95 m² and 662±64 m², respectively. Salmon diets were mostly similar, and a large proportion of diets in both habitats were made up of Copepoda/Cladocera (60-98% composition by biomass). Growth during the net pen experiment differed significantly between the two vegetation types (Kruskal-Wallis: p<0.001), with fish growing more in the natural emergent vegetation. In 2015, juveniles grew an average 6.4 mm FL in the natural emergent vegetation, compared to 4.7 mm FL in PHAR, and consumed fewer Copepoda/Cladocera and more Diptera over the 10 days. In 2016, juveniles grew an average 9.2 mm FL in the natural emergent vegetation compared to 7.6 mm FL in PHAR. In 2016, fish from both habitats consumed a higher abundance of Copepoda/Cladocera and grew more, despite poor water quality conditions at the site. Of the subyearlings (n=170) and yearlings (n=14) collected in habitats adjacent to the floodplain wetland, 48% were of known hatchery origin. Modeled potential growth rates for subyearlings were similar on average between February and May in the back channel, confluence, and main stem, ranging from 0.067–0.07 g/g/d, but the rates varied seasonally. Growth potential was higher in the back channel habitat earlier in the sampling season (February-March), as the modeled daily growth rates were 0.08 g/g/d compared to 0.06 g/g/d in the main stem. All fish collected prior to May were relatively small and unclipped, highlighting the seasonal benefits of shallow-water habitats to support a variety of life-history traits. When comparing modeled growth rates of the juveniles reared at the floodplain wetland compared to the in adjacent habitats, estimates from the floodplain wetland were higher across all months. Restoration of shallow-water habitats is important for the overall health of the estuary, but the effects of large-scale ecosystem changes (e.g., flow regulation and spread invasive species) on salmon recovery and estuary-management decisions are uncertain. For example, water control structures to limit the spread of PHAR also reduce fish access to floodplain habitats, and fewer high-flow events further limit fish access and may facilitate the spread of invasive species. PHAR has been shown to reduce overall plant diversity and, as observed in this study, may provide habitat that is less suitable to juvenile Chinook Salmon. The high density of important prey for salmon found at the site, regardless of the presence of PHAR, and high potential growth measured at the site, emphasize the importance of restoring shallow-water habitats that are accessible to juvenile Chinook Salmon in the upper estuary. Title: Restoring the Columbia River Estuary : Chinook Salmon Recovery and Invasive Species Management Author: Klopfenstein, Rachael As highlighted in this study, shallow-water habitats and the prey they provide are important for juvenile salmon in the Columbia River estuary, but the spread of invasive species and large-scale changes to the estuary influence how these habitats are utilized. Reed canarygrass (Phalaris arundinacea) (“PHAR” hereafter) is a highly invasive aquatic plant species that affects a number of emergent wetland habitats in the upper Columbia River estuary, and is of concern to those trying to restore important shallow-water habitats for juvenile salmon. The presence of PHAR undoubtedly reduces plant diversity, but this study seeked to elucidate how PHAR affects juvenile Chinook Salmon rearing success relative to natural emergent vegetation. The study further evaluated the importance of wetland-deriver prey to juveniles found in shallow-water habitats along a habitat gradient (i.e., back-water channel, confluence, and main stem). We conducted research at a floodplain wetland restoration site in the tidal-fluvial portion of the estuary, where a water control structure is used to manage water levels and the spread of PHAR. The goal of the research was to compare two microhabitats within the floodplain: areas dominated by PHAR and areas dominated by natural emergent vegetation. Using hatchery-raised juvenile Chinook salmon, we designed a series of feeding experiments in artificial enclosures to determine whether invasive PHAR and natural emergent vegetation provide similar foraging and growth opportunities for juvenile salmon. We further identified differences in physical and biological parameters of each habitat (e.g., temperature, dissolved oxygen, and invertebrate community) and examined feeding characteristics (e.g., diet composition and modeled growth rates) for juveniles through a stomach content analysis. Additionally, we conducted beach seining and diet analysis for fish collected along a habitat gradient and compared the diet composition and modeled growth rates between the sample areas. In the floodplain wetland, invertebrate prey compositions from the 2015-2016 (March- June) fallout and emergence traps were similar, but prey abundances and diversity varied seasonally. Across both years, for emergence traps, the average total density (per m²) of invertebrates in the natural vegetation and in PHAR was 154±18 m² and 225±34 m², respectively, and for the fallout traps was 664±95 m² and 662±64 m², respectively. Salmon diets were mostly similar, and a large proportion of diets in both habitats were made up of Copepoda/Cladocera (60-98% composition by biomass). Growth during the net pen experiment differed significantly between the two vegetation types (Kruskal-Wallis: p<0.001), with fish growing more in the natural emergent vegetation. In 2015, juveniles grew an average 6.4 mm FL in the natural emergent vegetation, compared to 4.7 mm FL in PHAR, and consumed fewer Copepoda/Cladocera and more Diptera over the 10 days. In 2016, juveniles grew an average 9.2 mm FL in the natural emergent vegetation compared to 7.6 mm FL in PHAR. In 2016, fish from both habitats consumed a higher abundance of Copepoda/Cladocera and grew more, despite poor water quality conditions at the site. Of the subyearlings (n=170) and yearlings (n=14) collected in habitats adjacent to the floodplain wetland, 48% were of known hatchery origin. Modeled potential growth rates for subyearlings were similar on average between February and May in the back channel, confluence, and main stem, ranging from 0.067–0.07 g/g/d, but the rates varied seasonally. Growth potential was higher in the back channel habitat earlier in the sampling season (February-March), as the modeled daily growth rates were 0.08 g/g/d compared to 0.06 g/g/d in the main stem. All fish collected prior to May were relatively small and unclipped, highlighting the seasonal benefits of shallow-water habitats to support a variety of life-history traits. When comparing modeled growth rates of the juveniles reared at the floodplain wetland compared to the in adjacent habitats, estimates from the floodplain wetland were higher across all months. Restoration of shallow-water habitats is important for the overall health of the estuary, but the effects of large-scale ecosystem changes (e.g., flow regulation and spread invasive species) on salmon recovery and estuary-management decisions are uncertain. For example, water control structures to limit the spread of PHAR also reduce fish access to floodplain habitats, and fewer high-flow events further limit fish access and may facilitate the spread of invasive species. PHAR has been shown to reduce overall plant diversity and, as observed in this study, may provide habitat that is less suitable to juvenile Chinook Salmon. The high density of important prey for salmon found at the site, regardless of the presence of PHAR, and high potential growth measured at the site, emphasize the importance of restoring shallow-water habitats that are accessible to juvenile Chinook Salmon in the upper estuary. Close

• 3. [Article] Coastal cutthroat trout : life in the watershed

  Citation × Citation Citation Abstract Copy Title: Coastal cutthroat trout : life in the watershed Author: Fitzpatrick, Martin S., Oregon State University. Sea Grant College Program Title: Coastal cutthroat trout : life in the watershed Author: Fitzpatrick, Martin S., Oregon State University. Sea Grant College Program Close

• 4. [Article] Coastal steelhead trout : life in the watershed

  Citation × Citation Citation Abstract Copy Title: Coastal steelhead trout : life in the watershed Author: Fitzpatrick, Martin S., Oregon State University. Sea Grant College Program Title: Coastal steelhead trout : life in the watershed Author: Fitzpatrick, Martin S., Oregon State University. Sea Grant College Program Close

• 5. [Article] Reconnecting aquatic habitats : validating historical habitat use by anadromous fishes using telemetry and stable isotope analysis above barriers

  I conducted a study to identify potential spawning habitat for anadromous salmonids above a 60-year-old hydropower dam in the headwaters of the North Umpqua River in Oregon. Like many other historical ...

  Citation × Citation Citation Abstract Copy Title: Reconnecting aquatic habitats : validating historical habitat use by anadromous fishes using telemetry and stable isotope analysis above barriers Author: Lewis, Sierra Koch I conducted a study to identify potential spawning habitat for anadromous salmonids above a 60-year-old hydropower dam in the headwaters of the North Umpqua River in Oregon. Like many other historical salmonid-bearing rivers, little documentation exists for anadromous fish presence above potential natural obstacles upstream of Soda Springs Dam. My prediction was that if migratory salmonids are allowed to move upstream of the dam using a new fish ladder they would utilize available upstream spawning habitat. I captured, radio-tagged, and transplanted wild adult summer steelhead, O. mykiss, above Soda Springs Dam and tracked daily movements for 1 year to observe habitat preferences. I also investigated evidence of historical anadromy throughout the North Umpqua River basin using stable isotope analysis of salmon-derived nitrogen (¹⁵N) in foliar samples from Douglas fir trees, P. menziesii, (>100 years old). I tested the hypothesis that I could identify undocumented, historical salmon spawning reaches above natural and anthropogenic obstacles based solely upon δ¹⁵N foliar deposition patterns. While tracking radio-tagged steelhead, I documented holding locations, the timing of spawning activities, and the outmigration of kelts. Tagged fish did not show any extensive movement in the river or tributaries above the dam. Most of the tagged adults showed incremental daily movements near the release site or downstream into the hydropower reservoir but did not travel further than 1 kilometer upstream in the main river channel. I recorded movements and localized activities that suggested some of the fish spawned and subsequently moved downstream towards the Pacific Ocean. My observations indicated that spawning behavior of tagged fish above Soda Springs Dam was delayed several weeks relative to fish spawning below the dam. There was no evidence from telemetry that any fish moved upstream in Fish Creek, the newly accessible habitat of interest in this project. My data suggest that steelhead will use restored habitat above dams, but that re-colonization activities are variable and may be affected by altered flow regimes within the restored habitat upstream of the dam and intra-specific density dependence. My stable isotope data indicated that the foliar δ¹⁵N deposition patterns were confounded with elevation. I documented potential "salmon-derived" false positives on the Umpqua National Forest above impassable waterfalls. Overall I found that foliar δ¹⁵N deposition patterns were highly variable and unexpectedly indicated a statistically significant negative correlation of foliar δ¹⁵N values with historical salmon presence. My linear mixed-effects modeling suggests that the presence of salmon is the most important indicator of foliar δ¹⁵N values, rather than the proximity of a sampled tree to stream flow above or below migratory barriers. I was not able to use the mixed effects model to identify previously undocumented salmon spawning habitat. My results from the foliar technique suggest that the method may not be universally applicable as has been previously suggested in the literature. Title: Reconnecting aquatic habitats : validating historical habitat use by anadromous fishes using telemetry and stable isotope analysis above barriers Author: Lewis, Sierra Koch I conducted a study to identify potential spawning habitat for anadromous salmonids above a 60-year-old hydropower dam in the headwaters of the North Umpqua River in Oregon. Like many other historical salmonid-bearing rivers, little documentation exists for anadromous fish presence above potential natural obstacles upstream of Soda Springs Dam. My prediction was that if migratory salmonids are allowed to move upstream of the dam using a new fish ladder they would utilize available upstream spawning habitat. I captured, radio-tagged, and transplanted wild adult summer steelhead, O. mykiss, above Soda Springs Dam and tracked daily movements for 1 year to observe habitat preferences. I also investigated evidence of historical anadromy throughout the North Umpqua River basin using stable isotope analysis of salmon-derived nitrogen (¹⁵N) in foliar samples from Douglas fir trees, P. menziesii, (>100 years old). I tested the hypothesis that I could identify undocumented, historical salmon spawning reaches above natural and anthropogenic obstacles based solely upon δ¹⁵N foliar deposition patterns. While tracking radio-tagged steelhead, I documented holding locations, the timing of spawning activities, and the outmigration of kelts. Tagged fish did not show any extensive movement in the river or tributaries above the dam. Most of the tagged adults showed incremental daily movements near the release site or downstream into the hydropower reservoir but did not travel further than 1 kilometer upstream in the main river channel. I recorded movements and localized activities that suggested some of the fish spawned and subsequently moved downstream towards the Pacific Ocean. My observations indicated that spawning behavior of tagged fish above Soda Springs Dam was delayed several weeks relative to fish spawning below the dam. There was no evidence from telemetry that any fish moved upstream in Fish Creek, the newly accessible habitat of interest in this project. My data suggest that steelhead will use restored habitat above dams, but that re-colonization activities are variable and may be affected by altered flow regimes within the restored habitat upstream of the dam and intra-specific density dependence. My stable isotope data indicated that the foliar δ¹⁵N deposition patterns were confounded with elevation. I documented potential "salmon-derived" false positives on the Umpqua National Forest above impassable waterfalls. Overall I found that foliar δ¹⁵N deposition patterns were highly variable and unexpectedly indicated a statistically significant negative correlation of foliar δ¹⁵N values with historical salmon presence. My linear mixed-effects modeling suggests that the presence of salmon is the most important indicator of foliar δ¹⁵N values, rather than the proximity of a sampled tree to stream flow above or below migratory barriers. I was not able to use the mixed effects model to identify previously undocumented salmon spawning habitat. My results from the foliar technique suggest that the method may not be universally applicable as has been previously suggested in the literature. Close

• 6. [Article] Recovery of Wild Salmonids in Western Oregon Lowlands

  This report was prepared by the Independent Multidisciplinary Science Team to the Oregon Plan for Salmon and watersheds.

  Citation × Citation Citation Abstract Copy Title: Recovery of Wild Salmonids in Western Oregon Lowlands Author: Independent Multidisciplinary Science Team (Or.) This report was prepared by the Independent Multidisciplinary Science Team to the Oregon Plan for Salmon and watersheds. Title: Recovery of Wild Salmonids in Western Oregon Lowlands Author: Independent Multidisciplinary Science Team (Or.) This report was prepared by the Independent Multidisciplinary Science Team to the Oregon Plan for Salmon and watersheds. Close

• 7. [Article] Urban and rural-residential land uses : their role in watershed health and the rehabilitation of Oregon's wild salmonids

  This report was prepared by the Independent Multidisciplinary Science Team of the Oregon Plan for Salmon and Watersheds.

  Citation × Citation Citation Abstract Copy Title: Urban and rural-residential land uses : their role in watershed health and the rehabilitation of Oregon's wild salmonids Author: Independent Multidisciplinary Science Team This report was prepared by the Independent Multidisciplinary Science Team of the Oregon Plan for Salmon and Watersheds. Title: Urban and rural-residential land uses : their role in watershed health and the rehabilitation of Oregon's wild salmonids Author: Independent Multidisciplinary Science Team This report was prepared by the Independent Multidisciplinary Science Team of the Oregon Plan for Salmon and Watersheds. Close

• 8. [Article] Oregon's Water Temperature Standard and its Application: Causes, Consequences, and Controversies Associated with Stream Temperature

  This report was prepared by the Independent Multidisciplinary Science Team of the Oregon Plan for Salmon and Watersheds.

  Citation × Citation Citation Abstract Copy Title: Oregon's Water Temperature Standard and its Application: Causes, Consequences, and Controversies Associated with Stream Temperature Author: Independent Multidisciplinary Science Team (Or.) This report was prepared by the Independent Multidisciplinary Science Team of the Oregon Plan for Salmon and Watersheds. Title: Oregon's Water Temperature Standard and its Application: Causes, Consequences, and Controversies Associated with Stream Temperature Author: Independent Multidisciplinary Science Team (Or.) This report was prepared by the Independent Multidisciplinary Science Team of the Oregon Plan for Salmon and Watersheds. Close

• 9. [Article] Juvenile coho salmon movement, growth and survival in a coastal basin of southern Oregon

  Juvenile salmonids display highly variable spatial and temporal movement patterns that are influenced by density dependent (e.g., competition, predation) and density independent (e.g., genetics, stream ...

  Citation × Citation Citation Abstract Copy Title: Juvenile coho salmon movement, growth and survival in a coastal basin of southern Oregon Author: Weybright, Adam D. Juvenile salmonids display highly variable spatial and temporal movement patterns that are influenced by density dependent (e.g., competition, predation) and density independent (e.g., genetics, stream discharge, physical habitat conditions) factors. The effects of these factors differ with fish life history stage, but will ultimately affect how salmonids utilize freshwater nursery habitats and influence their size at smolting. Although juvenile coho salmon (Oncorhynchus kisutch) (Walbaum 1792) movement patterns and their relationships with body mass have been previously examined, the temporal scale considered in most studies has been within individual seasonal periods. In this study, we monitored the movement of PIT tagged juvenile coho salmon throughout the period of freshwater residence in an entire southern Oregon coastal basin to identify the prevalent sedentary and mobile strategies these fish may adopt and to examine possible relationships between those strategies and fish body mass, growth and survival. Specific objectives include: 1) to describe juvenile coho salmon movement strategies and patterns during the freshwater residence period; 2) to determine the relative proportions of juvenile coho salmon that exhibit each movement strategy; 3) to establish whether juvenile coho salmon body mass and growth rates are related with a set of habitat variables recorded during this study; 4) to determine whether coho salmon body mass or growth rates are related to movement strategy; and 5) to evaluate whether winter survival of juvenile coho salmon is associated with movement strategy. Results revealed seasonally and spatially variable movement. More than half of coho salmon tracked throughout the period of freshwater residence exhibited movement behavior that differed between summer and winter seasons. Within seasonal periods, coho salmon in tidally affected reaches exhibited greater prevalence of mobile behavior relative to those in riverine reaches. Regression analysis indicated coho biomass density, habitat unit structural complexity and size at tagging were important in predicting summer growth of coho salmon. Juvenile coho salmon that were mobile during summer were either larger or no different in body mass in early summer relative to fish that exhibited sedentary behavior. Similarly, no consistent differences were observed between sedentary and mobile coho salmon in regards to summer growth. Coho salmon that were sedentary in summer and winter experienced higher apparent winter survival than mobile fish in each season, though the reach in which an individual resided at the start of winter appeared to also affect survival. Coho salmon residing in the tide gate reservoir reach and mainstem headwater reaches experienced greatest apparent winter survival. These results indicate that juvenile coho salmon movement within a stream basin is spatially and temporally variable and that mobility does not necessarily indicate inferior competitive ability. In a broader context, variable movement patterns reflect the capacity for plastic behavior in salmonids and this research demonstrates the importance of maintaining seasonally diverse freshwater and estuarine nursery habitats for juvenile fish. Title: Juvenile coho salmon movement, growth and survival in a coastal basin of southern Oregon Author: Weybright, Adam D. Juvenile salmonids display highly variable spatial and temporal movement patterns that are influenced by density dependent (e.g., competition, predation) and density independent (e.g., genetics, stream discharge, physical habitat conditions) factors. The effects of these factors differ with fish life history stage, but will ultimately affect how salmonids utilize freshwater nursery habitats and influence their size at smolting. Although juvenile coho salmon (Oncorhynchus kisutch) (Walbaum 1792) movement patterns and their relationships with body mass have been previously examined, the temporal scale considered in most studies has been within individual seasonal periods. In this study, we monitored the movement of PIT tagged juvenile coho salmon throughout the period of freshwater residence in an entire southern Oregon coastal basin to identify the prevalent sedentary and mobile strategies these fish may adopt and to examine possible relationships between those strategies and fish body mass, growth and survival. Specific objectives include: 1) to describe juvenile coho salmon movement strategies and patterns during the freshwater residence period; 2) to determine the relative proportions of juvenile coho salmon that exhibit each movement strategy; 3) to establish whether juvenile coho salmon body mass and growth rates are related with a set of habitat variables recorded during this study; 4) to determine whether coho salmon body mass or growth rates are related to movement strategy; and 5) to evaluate whether winter survival of juvenile coho salmon is associated with movement strategy. Results revealed seasonally and spatially variable movement. More than half of coho salmon tracked throughout the period of freshwater residence exhibited movement behavior that differed between summer and winter seasons. Within seasonal periods, coho salmon in tidally affected reaches exhibited greater prevalence of mobile behavior relative to those in riverine reaches. Regression analysis indicated coho biomass density, habitat unit structural complexity and size at tagging were important in predicting summer growth of coho salmon. Juvenile coho salmon that were mobile during summer were either larger or no different in body mass in early summer relative to fish that exhibited sedentary behavior. Similarly, no consistent differences were observed between sedentary and mobile coho salmon in regards to summer growth. Coho salmon that were sedentary in summer and winter experienced higher apparent winter survival than mobile fish in each season, though the reach in which an individual resided at the start of winter appeared to also affect survival. Coho salmon residing in the tide gate reservoir reach and mainstem headwater reaches experienced greatest apparent winter survival. These results indicate that juvenile coho salmon movement within a stream basin is spatially and temporally variable and that mobility does not necessarily indicate inferior competitive ability. In a broader context, variable movement patterns reflect the capacity for plastic behavior in salmonids and this research demonstrates the importance of maintaining seasonally diverse freshwater and estuarine nursery habitats for juvenile fish. Close

• 10. [Article] Review of the hatchery measures in the Oregon plan for salmon and watersheds. Part I: consistency of the Oregon Plan with recommendations from recent scientific review panels

  This report was written by the Independent Multidisciplinary Science Team of the Oregon Plan for Salmon and Watersheds

  Citation × Citation Citation Abstract Copy Title: Review of the hatchery measures in the Oregon plan for salmon and watersheds. Part I: consistency of the Oregon Plan with recommendations from recent scientific review panels Author: Independent Multidisciplinary Science Team (Or.) This report was written by the Independent Multidisciplinary Science Team of the Oregon Plan for Salmon and Watersheds Title: Review of the hatchery measures in the Oregon plan for salmon and watersheds. Part I: consistency of the Oregon Plan with recommendations from recent scientific review panels Author: Independent Multidisciplinary Science Team (Or.) This report was written by the Independent Multidisciplinary Science Team of the Oregon Plan for Salmon and Watersheds Close