Search

Search Results

• 6041. [Image] Influences of human activity on stream temperatures and existence of cold-water fish in streams with elevated temperature: report of a workshop: Independent Multidisciplinary Science Team, Corvallis, OR, October 5-6, 2000

  	Executive Summary The Independent Multidisciplinary Science Team (IMST) convened a panel of experts on stream temperature and fish ecology on October 5-6, 2000 for a scientific workshop on human influences ...
  	Citation × Citation Citation Abstract Copy Title: Influences of human activity on stream temperatures and existence of cold-water fish in streams with elevated temperature: report of a workshop: Independent Multidisciplinary Science Team, Corvallis, OR, October 5-6, 2000 Author: Independent Multidisciplinary Science Team (Oregon) Year: 2000, 2008, 2005 Executive Summary The Independent Multidisciplinary Science Team (IMST) convened a panel of experts on stream temperature and fish ecology on October 5-6, 2000 for a scientific workshop on human influences on stream temperature and responses by salmonids. The workshop was designed to review and discuss scientifically credible data and publications about 1) factors related to human activity that influence stream temperature and 2) behavioral, physical, and ecological mechanisms of cold water fish species for existing in streams with elevated temperatures. The goal of the workshop was to review empirical evidence and to identify points of agreement, disagreement, and knowledge gaps within the scientific community concerning the factors that influence stream temperature and fish responses to elevated temperatures. This information will assist the IMST in preparing a broader temperature report on Oregon's stream temperature water quality standards and their implementation. This report is prepared by the IMST. It was reviewed by workshop participants and revised by the IMST accordingly. The report includes abstracts of plenary presentations on factors that influence stream temperatures and fish responses, and the results of group discussions. The workshop participants focused on three main questions and were asked to list statements of agreement and disagreement, and to identify gaps in the scientific knowledge related to each question: ? How and where does riparian vegetation influence stream temperature? ? Do other changes in streams cause increases in stream temperature? ? How can apparently healthy fish populations exist in streams with temperatures higher than laboratory and field studies would indicate as healthy? The workshop participants provided answers to the questions in the form of bullets. The answers below represent the IMST's summation of the workshop findings and were reviewed by the participants. Several gaps in the scientific basis for specific questions or relationships were identified. The participants found no areas of disagreement for which technical information was available. They noted that any disagreements were not related to scientific interpretation, but were based on concerns or opinions about application, regulation, and management. How and where does riparian vegetation influence stream temperature? The influence of riparian vegetation on stream temperature is cumulative and complex, varying by site, over time, and across regions. Riparian vegetation can directly affect stream temperature by intercepting solar radiation and reducing stream heating. The influence of riparian shade in controlling temperature declines as streams widen in downstream reaches, but the role of riparian vegetation in providing water quality and fish habitat benefits continues to be important. Besides providing shade, riparian vegetation can also indirectly affect stream temperature by influencing microclimate, affecting channel morphology, affecting stream flow, influencing wind speed, affecting humidity, affecting soil temperature, using water, influencing air temperature, enhancing infiltration, and influencing thermal radiation. It is critical to know the site potential to understand what vegetation a site can support. There is not a good scientific understanding of how much vegetation shading is required to affect stream temperature. 1 This lack of understanding may be due to the spatial and temporal variability in landscape components, and the resulting variability in both the direct and indirect influences of vegetation on stream temperature. Therefore, it is difficult to generalize about the effects of vegetation on stream temperature. Do other changes in streams cause increases in stream temperature? The answer to this question is yes, other physical changes in the stream system can modify stream temperatures. Stream temperature is a product of complex interactions between geomorphology, soil, hydrology, vegetation, and climate within a watershed. Changes in these factors will result in changes in stream temperature. Human activities influence stream temperature by affecting one or more of four major components: riparian vegetation, channel morphology, hydrology, and surface/subsurface interactions. Stream systems vary substantially across the landscape, and site-specific information is critical to understanding stream temperature responses to human activities. How can apparently healthy fish populations exist in streams with temperatures higher than laboratory and field studies would indicate as healthy? Workshop participants identified several mechanisms that might explain the ability of fish populations to exist at higher than expected temperatures. The first mechanism was that the fish may have physiological adaptations to survive exposures to high temperatures. A second possibility was that stream habitats may contain cooler microhabitats that fish can occupy as refuge from higher temperatures. A third consideration is that ecological interactions may be different under differing thermal conditions resulting, for example, in changes in disease virulence or cumulative effects of stressors. Finally, since substantial differences exist between laboratory and field studies, it is difficult to apply results of laboratory studies to fish responses in the field. It is important to note that these proposed mechanisms are speculative and, as the list of gaps indicates, substantial experimental work is required to establish their influences on fish in different stream systems. Workshop Summaiy Workshop participants recognized gaps in the available science. Additional knowledge about human influences on stream temperatures and, consequently, influences on cold-water fish populations, will improve our ability to prevent further degradation of stream habitat and will enhance efforts geared towards the recovery of depressed fish populations. Even with these gaps, there was enough agreement on factors that influence stream temperature to indicate information is available to start developing and implementing management practices that are designed to reduce stream warming. It was suggested that managers should consider riparian vegetation, channel morphology, and hydrology, and should account for site differences. Title: Influences of human activity on stream temperatures and existence of cold-water fish in streams with elevated temperature: report of a workshop: Independent Multidisciplinary Science Team, Corvallis, OR, October 5-6, 2000 Author: Independent Multidisciplinary Science Team (Oregon) Year: 2000, 2008, 2005 Executive Summary The Independent Multidisciplinary Science Team (IMST) convened a panel of experts on stream temperature and fish ecology on October 5-6, 2000 for a scientific workshop on human influences on stream temperature and responses by salmonids. The workshop was designed to review and discuss scientifically credible data and publications about 1) factors related to human activity that influence stream temperature and 2) behavioral, physical, and ecological mechanisms of cold water fish species for existing in streams with elevated temperatures. The goal of the workshop was to review empirical evidence and to identify points of agreement, disagreement, and knowledge gaps within the scientific community concerning the factors that influence stream temperature and fish responses to elevated temperatures. This information will assist the IMST in preparing a broader temperature report on Oregon's stream temperature water quality standards and their implementation. This report is prepared by the IMST. It was reviewed by workshop participants and revised by the IMST accordingly. The report includes abstracts of plenary presentations on factors that influence stream temperatures and fish responses, and the results of group discussions. The workshop participants focused on three main questions and were asked to list statements of agreement and disagreement, and to identify gaps in the scientific knowledge related to each question: ? How and where does riparian vegetation influence stream temperature? ? Do other changes in streams cause increases in stream temperature? ? How can apparently healthy fish populations exist in streams with temperatures higher than laboratory and field studies would indicate as healthy? The workshop participants provided answers to the questions in the form of bullets. The answers below represent the IMST's summation of the workshop findings and were reviewed by the participants. Several gaps in the scientific basis for specific questions or relationships were identified. The participants found no areas of disagreement for which technical information was available. They noted that any disagreements were not related to scientific interpretation, but were based on concerns or opinions about application, regulation, and management. How and where does riparian vegetation influence stream temperature? The influence of riparian vegetation on stream temperature is cumulative and complex, varying by site, over time, and across regions. Riparian vegetation can directly affect stream temperature by intercepting solar radiation and reducing stream heating. The influence of riparian shade in controlling temperature declines as streams widen in downstream reaches, but the role of riparian vegetation in providing water quality and fish habitat benefits continues to be important. Besides providing shade, riparian vegetation can also indirectly affect stream temperature by influencing microclimate, affecting channel morphology, affecting stream flow, influencing wind speed, affecting humidity, affecting soil temperature, using water, influencing air temperature, enhancing infiltration, and influencing thermal radiation. It is critical to know the site potential to understand what vegetation a site can support. There is not a good scientific understanding of how much vegetation shading is required to affect stream temperature. 1 This lack of understanding may be due to the spatial and temporal variability in landscape components, and the resulting variability in both the direct and indirect influences of vegetation on stream temperature. Therefore, it is difficult to generalize about the effects of vegetation on stream temperature. Do other changes in streams cause increases in stream temperature? The answer to this question is yes, other physical changes in the stream system can modify stream temperatures. Stream temperature is a product of complex interactions between geomorphology, soil, hydrology, vegetation, and climate within a watershed. Changes in these factors will result in changes in stream temperature. Human activities influence stream temperature by affecting one or more of four major components: riparian vegetation, channel morphology, hydrology, and surface/subsurface interactions. Stream systems vary substantially across the landscape, and site-specific information is critical to understanding stream temperature responses to human activities. How can apparently healthy fish populations exist in streams with temperatures higher than laboratory and field studies would indicate as healthy? Workshop participants identified several mechanisms that might explain the ability of fish populations to exist at higher than expected temperatures. The first mechanism was that the fish may have physiological adaptations to survive exposures to high temperatures. A second possibility was that stream habitats may contain cooler microhabitats that fish can occupy as refuge from higher temperatures. A third consideration is that ecological interactions may be different under differing thermal conditions resulting, for example, in changes in disease virulence or cumulative effects of stressors. Finally, since substantial differences exist between laboratory and field studies, it is difficult to apply results of laboratory studies to fish responses in the field. It is important to note that these proposed mechanisms are speculative and, as the list of gaps indicates, substantial experimental work is required to establish their influences on fish in different stream systems. Workshop Summaiy Workshop participants recognized gaps in the available science. Additional knowledge about human influences on stream temperatures and, consequently, influences on cold-water fish populations, will improve our ability to prevent further degradation of stream habitat and will enhance efforts geared towards the recovery of depressed fish populations. Even with these gaps, there was enough agreement on factors that influence stream temperature to indicate information is available to start developing and implementing management practices that are designed to reduce stream warming. It was suggested that managers should consider riparian vegetation, channel morphology, and hydrology, and should account for site differences. Close

• 6042. [Image] Biological opinion Klamath Project operations

  	"May 31, 2002."; Includes bibliographical references.
  	Citation × Citation Citation Abstract Copy Title: Biological opinion Klamath Project operations Author: United States.; National Marine Fisheries Service. Year: 2002, 2008, 2005 "May 31, 2002."; Includes bibliographical references. Title: Biological opinion Klamath Project operations Author: United States.; National Marine Fisheries Service. Year: 2002, 2008, 2005 "May 31, 2002."; Includes bibliographical references. Close

• 6043. [Image] The Water Report - Watershed assessments: the Upper Klamath Basin process

  	Only portions of issues of The Water Report are available in the Klamath Waters Digital Library. See the full report at http://www.thewaterreport.com/
  	Citation × Citation Citation Abstract Copy Title: The Water Report - Watershed assessments: the Upper Klamath Basin process Author: Envirotech Publications Year: 2004, 2008, 2006 Only portions of issues of The Water Report are available in the Klamath Waters Digital Library. See the full report at http://www.thewaterreport.com/ Title: The Water Report - Watershed assessments: the Upper Klamath Basin process Author: Envirotech Publications Year: 2004, 2008, 2006 Only portions of issues of The Water Report are available in the Klamath Waters Digital Library. See the full report at http://www.thewaterreport.com/ Close

• 6044. [Image] Historic resource study: Crater Lake National Park, Oregon

  	ill.; "June 1984."; Bibliography: p. 307-317
  	Citation × Citation Citation Abstract Copy Title: Historic resource study: Crater Lake National Park, Oregon Author: Greene, Linda W. Year: 1984, 2009, 2010 ill.; "June 1984."; Bibliography: p. 307-317 Title: Historic resource study: Crater Lake National Park, Oregon Author: Greene, Linda W. Year: 1984, 2009, 2010 ill.; "June 1984."; Bibliography: p. 307-317 Close

• 6045. [Image] Soil survey of Crater Lake National Park, Oregon

  	ill. (some col.), maps (some col.); 13 folded maps tipped in; Also available via Internet as of April 20, 2005; Includes data tables; Includes bibliographical references (p. 151-153) and glossary (p. 1...
  	Citation × Citation Citation Abstract Copy Title: Soil survey of Crater Lake National Park, Oregon Author: United States Department of Agriculture, Natural Resources Conservation Service, in cooperation with United States Department of the Interior, National Park Service Year: 2008 ill. (some col.), maps (some col.); 13 folded maps tipped in; Also available via Internet as of April 20, 2005; Includes data tables; Includes bibliographical references (p. 151-153) and glossary (p. 155-163) Title: Soil survey of Crater Lake National Park, Oregon Author: United States Department of Agriculture, Natural Resources Conservation Service, in cooperation with United States Department of the Interior, National Park Service Year: 2008 ill. (some col.), maps (some col.); 13 folded maps tipped in; Also available via Internet as of April 20, 2005; Includes data tables; Includes bibliographical references (p. 151-153) and glossary (p. 155-163) Close

• 6046. [Image] Annual project history: Klamath Project, Oregon-California, 1958

  	INTRODUCTION AND GENERAL Genex*al Description of the Project Location. The Klamath Project is in the Upper Klamath River Basin, east of the Cascade Range. It is located in Klamath Comity, Oregon, ...
  	Citation × Citation Citation Abstract Copy Title: Annual project history: Klamath Project, Oregon-California, 1958 Author: United States. Bureau of Reclamation Year: 1958, 2008, 2006 INTRODUCTION AND GENERAL Genex*al Description of the Project Location. The Klamath Project is in the Upper Klamath River Basin, east of the Cascade Range. It is located in Klamath Comity, Oregon, and in Modoc and Siskiyou Counties of California. Project headquarters is located at the principal city of Klamath Falls, Oregon, which has a population of about 3&>^00, including suburbs. Smaller towns on the project in Oregon are Merrill, Malin, and Bonanza. The town of Tulelake, California, was established in 1931 near the center of the Tule Lake Division. Climate ? The mean temperature for the warmest month is 630 F. The coldest month has raez.n temperature of 29? F. Summer nights are cool. The annual rainfall is about 13 inches, of which about 3^ inches fall during the growing season of 90 to 130 days. Topography, soils, and crops. The project area is about U,100 feet elevation above sea level. The surface topography is generally smooth and flat for the large areas of lake bottom, and gently sloping on the higher lands? Peat and muck soils are common in the recent lake bottoms. Soils vary from sandy loam to clay on other parts of the project. The principal crops grown are alfalfa, malting and feed barley, potatoes, clover seed, and irrigated pasture and other forage. Stock raising is an important enterprise. Industry and transportation. Farming and lumbering each provide the major portion of the economy of the Basin. Three major railroad lines, one major highway and many secondary highways, and two airlines serve the project area. Plan and purpose. In 1958 the project provided irrigation service to 21^,500 acres. The water supply is provided by two main water courses, Klamath River and Lost River and their tributaries. Besides storing, diverting, and distributing water for irrigation, project facilities have reclaimed by drainage large areas formerly inundated by Lower Klamath and Tule Lakes. Flood waters of Lost River, which terminates In Tule Lake, are diverted to the Klamath River through the Lost River Diversion Channel. This channel is also used to carry irrigation water in the opposite direction in the summertime. Another principal function of the project is water-level control for the Tule Lake and Lower Klamath Lake National Wildlife Refuges. DTERODUCTIOH AND GBNKRAL (Continued) General Description of the Project (Cont.) Upper Klamath Lake on the Klamath River is the principal storage reservoir, having an active capacity of 52^,800 acre-feet. It is controlled by Link River Dam constructed, maintained, and operated by The California Oregon Power Company under an agreement with the project whereby irrigation requirements and rights are protected. The Main, Lower Klamath, and Tule Lake Divisions are served from this source. Gerber Reservoir on Miller Creel; and Clear Lake Reservoir on Lost River provide flood control for the Tule Lake Division and an irrigation supply for the Langell Valley Division. Their active storage capacities are 9*b3OO acre-feet and 513*300 acre-feet, respectively. Federally-financed project works also include the diversion, distribution, and drainage systems for the Main and Tule Lake Divisions; the diversion darn and main canals for the Langell Valley Division; and drainage outlets for the Lower Klamath and Tule Lake Divisions? Title: Annual project history: Klamath Project, Oregon-California, 1958 Author: United States. Bureau of Reclamation Year: 1958, 2008, 2006 INTRODUCTION AND GENERAL Genex*al Description of the Project Location. The Klamath Project is in the Upper Klamath River Basin, east of the Cascade Range. It is located in Klamath Comity, Oregon, and in Modoc and Siskiyou Counties of California. Project headquarters is located at the principal city of Klamath Falls, Oregon, which has a population of about 3&>^00, including suburbs. Smaller towns on the project in Oregon are Merrill, Malin, and Bonanza. The town of Tulelake, California, was established in 1931 near the center of the Tule Lake Division. Climate ? The mean temperature for the warmest month is 630 F. The coldest month has raez.n temperature of 29? F. Summer nights are cool. The annual rainfall is about 13 inches, of which about 3^ inches fall during the growing season of 90 to 130 days. Topography, soils, and crops. The project area is about U,100 feet elevation above sea level. The surface topography is generally smooth and flat for the large areas of lake bottom, and gently sloping on the higher lands? Peat and muck soils are common in the recent lake bottoms. Soils vary from sandy loam to clay on other parts of the project. The principal crops grown are alfalfa, malting and feed barley, potatoes, clover seed, and irrigated pasture and other forage. Stock raising is an important enterprise. Industry and transportation. Farming and lumbering each provide the major portion of the economy of the Basin. Three major railroad lines, one major highway and many secondary highways, and two airlines serve the project area. Plan and purpose. In 1958 the project provided irrigation service to 21^,500 acres. The water supply is provided by two main water courses, Klamath River and Lost River and their tributaries. Besides storing, diverting, and distributing water for irrigation, project facilities have reclaimed by drainage large areas formerly inundated by Lower Klamath and Tule Lakes. Flood waters of Lost River, which terminates In Tule Lake, are diverted to the Klamath River through the Lost River Diversion Channel. This channel is also used to carry irrigation water in the opposite direction in the summertime. Another principal function of the project is water-level control for the Tule Lake and Lower Klamath Lake National Wildlife Refuges. DTERODUCTIOH AND GBNKRAL (Continued) General Description of the Project (Cont.) Upper Klamath Lake on the Klamath River is the principal storage reservoir, having an active capacity of 52^,800 acre-feet. It is controlled by Link River Dam constructed, maintained, and operated by The California Oregon Power Company under an agreement with the project whereby irrigation requirements and rights are protected. The Main, Lower Klamath, and Tule Lake Divisions are served from this source. Gerber Reservoir on Miller Creel; and Clear Lake Reservoir on Lost River provide flood control for the Tule Lake Division and an irrigation supply for the Langell Valley Division. Their active storage capacities are 9*b3OO acre-feet and 513*300 acre-feet, respectively. Federally-financed project works also include the diversion, distribution, and drainage systems for the Main and Tule Lake Divisions; the diversion darn and main canals for the Langell Valley Division; and drainage outlets for the Lower Klamath and Tule Lake Divisions? Close

• 6047. [Image] Region II Klamath Project annual history, 1945

  	Ill., maps (some color), photographs; Includes fiscal year financials, photographs, crop and livestock yields, water storage and distribution, hydrography report, etc.; Title covers: calendar years for ...
  	Citation × Citation Citation Abstract Copy Title: Region II Klamath Project annual history, 1945 Author: United States. Bureau of Reclamation Year: 1945, 2008 Ill., maps (some color), photographs; Includes fiscal year financials, photographs, crop and livestock yields, water storage and distribution, hydrography report, etc.; Title covers: calendar years for 1944 – 1945; Description is based on: Region II Klamath Project annual history 1944. Contains three parts and three table of contents.; Dates of the beginning year(s) of publication are derived from May 1, 1903 to December 31, 1912, History of the Klamath Project and from the volume information on later volumes (v. 35) Klamath District and Klamath Project Annual history for 1945, dated December 1, 1946 Title: Region II Klamath Project annual history, 1945 Author: United States. Bureau of Reclamation Year: 1945, 2008 Ill., maps (some color), photographs; Includes fiscal year financials, photographs, crop and livestock yields, water storage and distribution, hydrography report, etc.; Title covers: calendar years for 1944 – 1945; Description is based on: Region II Klamath Project annual history 1944. Contains three parts and three table of contents.; Dates of the beginning year(s) of publication are derived from May 1, 1903 to December 31, 1912, History of the Klamath Project and from the volume information on later volumes (v. 35) Klamath District and Klamath Project Annual history for 1945, dated December 1, 1946 Close

• 6048. [Image] Bull Trout, Salvelinus Confluentus... Draft Recovery Plan, Chapter 1, Introduction...

  	EXECUTIVE SUMMARY FOR THE BULL TROUT RECOVERY PLAN Current Species Status The bull trout (Salvelinus confluentus) in the coterminous United States was listed as threatened on November 1, 1999 (64 ...
  	Citation × Citation Citation Abstract Copy Title: Bull Trout, Salvelinus Confluentus... Draft Recovery Plan, Chapter 1, Introduction... Author: U.S. Fish and Wildlife Service Year: 2003, 2008, 2005 EXECUTIVE SUMMARY FOR THE BULL TROUT RECOVERY PLAN Current Species Status The bull trout (Salvelinus confluentus) in the coterminous United States was listed as threatened on November 1, 1999 (64 FR 58910). Earlier rulemakings had listed distinct population segments of bull trout as threatened in the Columbia River, Klamath River, and Jarbidge River basins (63 FR 31647, 63 FR 42757, 64 FR 17110). Bull trout distribution, abundance, and habitat quality have declined rangewide. Several local extirpations have been documented, beginning in the 1950fs. Bull trout continue to occur the Klamath River, Columbia River, Jarbidge River, St. Mary-Belly River, and Coastal-Puget Sound, in the states of Idaho, Montana, Nevada, Oregon, and Washington. Habitat Requirements and Limiting Factors Bull trout have more specific habitat requirements than most other salmonids. Habitat components that influence bull trout distribution and abundance include water temperature, cover, channel form and stability, substrate for spawning and rearing, and migratory corridors. Bull trout are found in colder streams and require colder water than most other salmonids for incubation, juvenile rearing, and spawning. Spawning and rearing areas are often associated with cold-water springs, groundwater infiltration, and/or the coldest streams in a watershed. Throughout their lives, bull trout require complex forms of cover, including large woody debris, undercut banks, boulders, and pools. Alterations in channel form and reductions in channel stability result in habitat degradation and reduced survival of bull trout eggs and juveniles. Channel alterations may reduce the abundance and quality of side channels, stream margins, and pools, which are areas bull trout frequently inhabit. For spawning and early rearing bull trout require loose, clean gravel relatively free of fine sediments. Because bull trout have a relatively long incubation and development period within spawning gravel (greater than 200 days), transport of bedload in unstable channels may kill young bull trout. Bull trout use migratory corridors to move from spawning and rearing habitats to foraging and overwintering habitats and back. Different habitats provide bull trout with diverse resources, and migratory corridors allow local populations to connect, which may increase the potential for gene flow and support or refounding of populations. Declines in bull trout distribution and abundance are the results of combined effects of the following: habitat degradation and fragmentation, the blockage of migratory corridors, poor water quality, angler harvest and poaching, entrainment (process by which aquatic organisms are pulled through a diversion structure or other device) into diversion channels and dams, and introduced iv normative species. Specific land and water management activities that continue to depress bull trout populations and degrade habitat include dams and other diversion structures, forest management practices, livestock grazing, agriculture, road construction and maintenance, mining, and urban and rural development. Some threats to bull trout are the continuing effects of past land management activities. Organization and Development of the Recovery Plan Because bull trout in the coterminous United States are widely distributed within a large area, the recovery plan is organized into multiple chapters. This introductory chapter (Chapter 1) describes our overall recovery strategy for the species, defines recovery, and identifies recovery actions applicable for all listed bull trout in the coterminous United States. Each successive chapter focuses on bull trout in specific geographic areas (recovery units), and describes conditions, defines recovery criteria, and identifies specific recovery actions for the recovery unit. Recovery Objectives The goal of this recovery plan is to describe the actions needed to achieve the recovery of bull trout, that is, to ensure the long-term persistence of self-sustaining, complex interacting groups (or multiple local populations that may have overlapping spawning and rearing areas) of bull trout distributed across the species' native range. Recovery of bull trout will require reducing threats to the long-term persistence of populations, maintaining multiple interconnected populations of bull trout across the diverse habitats of their native range, and preserving the diversity of bull trout life-history strategies (e.g., resident or migratory forms, emigration age, spawning frequency, local habitat adaptations). To recover bull trout, the following four objectives have been identified: ? Maintain current distribution of bull trout within core areas as described in recovery unit chapters and restore distribution where recommended in recovery unit chapters. ? Maintain stable or increasing trend in abundance of bull trout. ? Restore and maintain suitable habitat conditions for all bull trout life history stages and strategies. ? Conserve genetic diversity and provide opportunity for genetic exchange. ? These objectives apply to bull trout in all recovery units. Additional objectives may be necessary to achieve recovery in some recovery units and will be identified in the respective recovery unit chapters. Recovery Criteria Criteria are established to assess whether recovery objectives are being achieved. Criteria specific to each recovery unit are defined in each recovery unit chapter. Individual chapters may contain criteria for assessing the status of bull trout and alleviation of threats that are unique to one or several recovery units. However, every recovery unit chapter will contain criteria that address the following characteristics: ? The distribution of bull trout in identified and potential local populations in all core areas within the recovery unit. ? The estimated abundance of adult bull trout within core areas in the recovery unit, expressed as either a point estimate or a range of individuals. ? The presence of stable or increasing trends for adult bull trout abundance in the recovery unit. ? The restoration of passage at specific barriers identified as inhibiting recovery. We expect recovery of bull trout to be a dynamic process occurring over time. The recovery objectives are based on our current knowledge and may be refined as more information becomes available. Some local populations of bull trout, and possibly core area populations, may be extirpated even though recovery actions are being implemented. If reestablishment of recently extirpated populations is not feasible or practical, recovery criteria for a given recovery unit will be revised on a case-by-case basis. Meeting the four recovery criteria is not intended to be precluded where localized extirpations of bull trout are offset by sufficiently strong improvements in other areas of a recovery unit in meeting the four recovery objectives. The determination of whether a distinct population segment of bull trout is recovered will rely on an analysis of the overall status of the species, threats to the species, and the adequacy of existing regulatory and conservation mechanisms. For example, it may be possible for the Columbia River Distinct Population Segment, which has 22 recovery units, to be recovered prior to all recovery unit criteria being met in all recovery units. Success in accomplishing the recovery VI criteria will be reviewed and considered for the impacts both within a recovery unit and throughout a distinct population segment. Actions Needed Specific tasks falling within the following seven categories will be necessary to initiate recovery within all recovery units: ? Protect, restore, and maintain suitable habitat conditions for bull trout. ? Prevent and reduce negative effects of normative fishes and other normative taxa on bull trout. ? Establish fisheries management goals and objectives compatible with bull trout recovery and implement practices to achieve goals. ? Characterize, conserve, and monitor genetic diversity and gene flow among local populations of bull trout. ? Conduct research and monitoring to implement and evaluate bull trout recovery activities, consistent with an adaptive management approach using feedback from implemented, site-specific recovery tasks. ? Use all available conservation programs and regulations to protect and conserve bull trout and bull trout habitats. ? Assess the implementation of bull trout recovery by recovery units and revise recovery unit plans based on evaluations. Recovery Priority Number The recovery priority number for bull trout in the coterminous United States is 9C, on a scale of 1 to 18, indicating that (1) taxonomically, these populations are distinct population segments of a species, (2) the five populations are subject to a moderate degree of threat(s), (3) the recovery potential is high, and (4) the degree of potential conflict during recovery is high. vrr Estimated Cost of Recovery The total cost estimate of recovery for bull trout in the coterminous United States is presented in the individual recovery unit chapters. The costs presented in each chapter are attributed to bull trout conservation but other species will also benefit. Date of Recovery Expected time to achieve recovery varies among recovery units because of differences in bull trout status, factors affecting bull trout, implementation and effectiveness of recovery tasks, and responses to recovery tasks. Achieving bull trout recovery in all recovery units will be a complex process that will likely take 25 years or more. vin Title: Bull Trout, Salvelinus Confluentus... Draft Recovery Plan, Chapter 1, Introduction... Author: U.S. Fish and Wildlife Service Year: 2003, 2008, 2005 EXECUTIVE SUMMARY FOR THE BULL TROUT RECOVERY PLAN Current Species Status The bull trout (Salvelinus confluentus) in the coterminous United States was listed as threatened on November 1, 1999 (64 FR 58910). Earlier rulemakings had listed distinct population segments of bull trout as threatened in the Columbia River, Klamath River, and Jarbidge River basins (63 FR 31647, 63 FR 42757, 64 FR 17110). Bull trout distribution, abundance, and habitat quality have declined rangewide. Several local extirpations have been documented, beginning in the 1950fs. Bull trout continue to occur the Klamath River, Columbia River, Jarbidge River, St. Mary-Belly River, and Coastal-Puget Sound, in the states of Idaho, Montana, Nevada, Oregon, and Washington. Habitat Requirements and Limiting Factors Bull trout have more specific habitat requirements than most other salmonids. Habitat components that influence bull trout distribution and abundance include water temperature, cover, channel form and stability, substrate for spawning and rearing, and migratory corridors. Bull trout are found in colder streams and require colder water than most other salmonids for incubation, juvenile rearing, and spawning. Spawning and rearing areas are often associated with cold-water springs, groundwater infiltration, and/or the coldest streams in a watershed. Throughout their lives, bull trout require complex forms of cover, including large woody debris, undercut banks, boulders, and pools. Alterations in channel form and reductions in channel stability result in habitat degradation and reduced survival of bull trout eggs and juveniles. Channel alterations may reduce the abundance and quality of side channels, stream margins, and pools, which are areas bull trout frequently inhabit. For spawning and early rearing bull trout require loose, clean gravel relatively free of fine sediments. Because bull trout have a relatively long incubation and development period within spawning gravel (greater than 200 days), transport of bedload in unstable channels may kill young bull trout. Bull trout use migratory corridors to move from spawning and rearing habitats to foraging and overwintering habitats and back. Different habitats provide bull trout with diverse resources, and migratory corridors allow local populations to connect, which may increase the potential for gene flow and support or refounding of populations. Declines in bull trout distribution and abundance are the results of combined effects of the following: habitat degradation and fragmentation, the blockage of migratory corridors, poor water quality, angler harvest and poaching, entrainment (process by which aquatic organisms are pulled through a diversion structure or other device) into diversion channels and dams, and introduced iv normative species. Specific land and water management activities that continue to depress bull trout populations and degrade habitat include dams and other diversion structures, forest management practices, livestock grazing, agriculture, road construction and maintenance, mining, and urban and rural development. Some threats to bull trout are the continuing effects of past land management activities. Organization and Development of the Recovery Plan Because bull trout in the coterminous United States are widely distributed within a large area, the recovery plan is organized into multiple chapters. This introductory chapter (Chapter 1) describes our overall recovery strategy for the species, defines recovery, and identifies recovery actions applicable for all listed bull trout in the coterminous United States. Each successive chapter focuses on bull trout in specific geographic areas (recovery units), and describes conditions, defines recovery criteria, and identifies specific recovery actions for the recovery unit. Recovery Objectives The goal of this recovery plan is to describe the actions needed to achieve the recovery of bull trout, that is, to ensure the long-term persistence of self-sustaining, complex interacting groups (or multiple local populations that may have overlapping spawning and rearing areas) of bull trout distributed across the species' native range. Recovery of bull trout will require reducing threats to the long-term persistence of populations, maintaining multiple interconnected populations of bull trout across the diverse habitats of their native range, and preserving the diversity of bull trout life-history strategies (e.g., resident or migratory forms, emigration age, spawning frequency, local habitat adaptations). To recover bull trout, the following four objectives have been identified: ? Maintain current distribution of bull trout within core areas as described in recovery unit chapters and restore distribution where recommended in recovery unit chapters. ? Maintain stable or increasing trend in abundance of bull trout. ? Restore and maintain suitable habitat conditions for all bull trout life history stages and strategies. ? Conserve genetic diversity and provide opportunity for genetic exchange. ? These objectives apply to bull trout in all recovery units. Additional objectives may be necessary to achieve recovery in some recovery units and will be identified in the respective recovery unit chapters. Recovery Criteria Criteria are established to assess whether recovery objectives are being achieved. Criteria specific to each recovery unit are defined in each recovery unit chapter. Individual chapters may contain criteria for assessing the status of bull trout and alleviation of threats that are unique to one or several recovery units. However, every recovery unit chapter will contain criteria that address the following characteristics: ? The distribution of bull trout in identified and potential local populations in all core areas within the recovery unit. ? The estimated abundance of adult bull trout within core areas in the recovery unit, expressed as either a point estimate or a range of individuals. ? The presence of stable or increasing trends for adult bull trout abundance in the recovery unit. ? The restoration of passage at specific barriers identified as inhibiting recovery. We expect recovery of bull trout to be a dynamic process occurring over time. The recovery objectives are based on our current knowledge and may be refined as more information becomes available. Some local populations of bull trout, and possibly core area populations, may be extirpated even though recovery actions are being implemented. If reestablishment of recently extirpated populations is not feasible or practical, recovery criteria for a given recovery unit will be revised on a case-by-case basis. Meeting the four recovery criteria is not intended to be precluded where localized extirpations of bull trout are offset by sufficiently strong improvements in other areas of a recovery unit in meeting the four recovery objectives. The determination of whether a distinct population segment of bull trout is recovered will rely on an analysis of the overall status of the species, threats to the species, and the adequacy of existing regulatory and conservation mechanisms. For example, it may be possible for the Columbia River Distinct Population Segment, which has 22 recovery units, to be recovered prior to all recovery unit criteria being met in all recovery units. Success in accomplishing the recovery VI criteria will be reviewed and considered for the impacts both within a recovery unit and throughout a distinct population segment. Actions Needed Specific tasks falling within the following seven categories will be necessary to initiate recovery within all recovery units: ? Protect, restore, and maintain suitable habitat conditions for bull trout. ? Prevent and reduce negative effects of normative fishes and other normative taxa on bull trout. ? Establish fisheries management goals and objectives compatible with bull trout recovery and implement practices to achieve goals. ? Characterize, conserve, and monitor genetic diversity and gene flow among local populations of bull trout. ? Conduct research and monitoring to implement and evaluate bull trout recovery activities, consistent with an adaptive management approach using feedback from implemented, site-specific recovery tasks. ? Use all available conservation programs and regulations to protect and conserve bull trout and bull trout habitats. ? Assess the implementation of bull trout recovery by recovery units and revise recovery unit plans based on evaluations. Recovery Priority Number The recovery priority number for bull trout in the coterminous United States is 9C, on a scale of 1 to 18, indicating that (1) taxonomically, these populations are distinct population segments of a species, (2) the five populations are subject to a moderate degree of threat(s), (3) the recovery potential is high, and (4) the degree of potential conflict during recovery is high. vrr Estimated Cost of Recovery The total cost estimate of recovery for bull trout in the coterminous United States is presented in the individual recovery unit chapters. The costs presented in each chapter are attributed to bull trout conservation but other species will also benefit. Date of Recovery Expected time to achieve recovery varies among recovery units because of differences in bull trout status, factors affecting bull trout, implementation and effectiveness of recovery tasks, and responses to recovery tasks. Achieving bull trout recovery in all recovery units will be a complex process that will likely take 25 years or more. vin Close

• 6049. [Image] The Water Report - Hydro relicensing OR/CA: fish passage

  	Only portions of issues of The Water Report are available in the Klamath Waters Digital Library. See the full report at http://www.thewaterreport.com/
  	Citation × Citation Citation Abstract Copy Title: The Water Report - Hydro relicensing OR/CA: fish passage Author: Envirotech Publications Year: 2006, 2008 Only portions of issues of The Water Report are available in the Klamath Waters Digital Library. See the full report at http://www.thewaterreport.com/ Title: The Water Report - Hydro relicensing OR/CA: fish passage Author: Envirotech Publications Year: 2006, 2008 Only portions of issues of The Water Report are available in the Klamath Waters Digital Library. See the full report at http://www.thewaterreport.com/ Close

• 6050. [Article] Distribution and movements of Chinook salmon, Oncorhynchus tshawytscha, returning to the Yukon River basin

  Chinook salmon, Oncorhynchus tshawytscha, returning to the Yukon River basin and other large river systems in western Alaska have declined dramatically since the late 1990s. This continuing trend has ...

  Citation × Citation Citation Abstract Copy Title: Distribution and movements of Chinook salmon, Oncorhynchus tshawytscha, returning to the Yukon River basin Author: Eiler, John H. Chinook salmon, Oncorhynchus tshawytscha, returning to the Yukon River basin and other large river systems in western Alaska have declined dramatically since the late 1990s. This continuing trend has raised concerns over the future status of the returns, and severely impacted commercial and subsistence fisheries within the drainage. Management is further complicated by the mixed-stock composition of the run, the presence of other temporally similar salmon species, and the need to equitably allocate harvests between the numerous fisheries and user groups scattered throughout the basin. Detailed information is needed on Chinook salmon run characteristics to better understand and manage the returns, and facilitate conservation efforts. However, this goal is exacerbated by the massive size and remote nature of the basin, the large number of highly mobile fish, and the compressed timing of the run. To address these challenges, radio telemetry was used to determine the stock composition and spawning distribution of the returns, and the migratory characteristics of the fish. The migratory patterns exhibited by returning salmon provide a number of insights into the status of the run. Since the Yukon River is essentially free-flowing (i.e., not regulated), this study also presented an opportunity to document the distribution and upriver movements of large returns of wild Chinook salmon under natural conditions. During 2002-2004, returning adult Chinook salmon were captured in the lower Yukon River (approximately 300 km upriver from the river mouth), tagged with radio transmitters, and tracked upriver using remote tracking stations located on important migratory routes and major spawning tributaries. Aerial tracking surveys were used to locate fish in spawning areas and between stations. The fish responded well to the capture and handling procedures, with most (2,790, 98%) resuming upriver movements. Although the fish initially displayed a negative tagging response, with slower migration rates observed immediately after release, the duration of this response was relatively short (several days) and less severe as the fish moved upriver. Independent measures indicated that the swimming speeds and timing of the fish upriver from the tagging area were comparable to untagged fish, suggesting that the tagging methods used were relatively benign. Fish returned to spawning areas throughout the basin, ranging from several hundred to over 3,000 km from the tagging area. Distribution patterns were similar across years, suggesting that the principal components of the run were identified. Most spawning fish were clustered in a number of key tributaries, with smaller numbers of fish located in other spatially isolated areas. The fish typically returned to clear water tributaries that were relatively entrenched, had moderate gradients, and were associated with upland areas. Fish were largely absent in lowland reaches characterized by meandering, low gradient, highly alluvial channels often associated with main river floodplains. There was suggestive evidence of mainstem spawning in reaches of the Upper Yukon. The status of fish remaining in other mainstem areas was less certain, and may represent local spawning activity or fish that died while in-transit to upriver areas. Although Chinook salmon spawned throughout the basin, the run was dominated by two regional components (Tanana and Upper Yukon), which annually comprised over 70% of the return. Substantially fewer fish returned to other areas ranging from 2-9% of the return, although the collective contribution of these stocks was appreciable. Most regional returns consisted of several principal stocks and a number of small, spatially isolated populations. Regional and stock composition estimates were similar across years even though differences in run abundance were reported, suggesting that these abundance differences were not related to regional or stock-specific differences. Run timing was relatively compressed compared to rivers in the southern portion of the range, with most stocks passing through the lower river over a 6-week period, ranging from 16 to 38 d. Run timing was generally earlier for stocks traveling farther upriver, although exceptions were noted. Lower basin stocks were primarily later run fish. Pronounced differences were observed in the migration rates (km/d) exhibited by regional stocks. Substantially slower swimming speeds were observed for fish returning to terminal tributaries in the lower basin ranging from 28-40 km/d compared to 52-62 km/d for upper basin stocks. The migratory patterns (migration rates in sequential reaches) of the fish also showed distinct regional differences. Average migration rates through the lower river were remarkably similar for the different stocks, ranging from 57-62 km/d, with most stocks exhibiting a general decline as the fish moved farther upriver. Tanana River stocks displayed a pronounced reduction in swimming speed after leaving the Yukon River main stem, with migration rates declining to 24 km/d on average as the fish approached their terminal tributaries. Conversely, upper basin stocks exhibited a relatively gradual (but variable) overall decline in migration rate even though these fish were traveling substantially greater distances upriver. Average migration rates for upper basin stocks ranged from 43-61 km/d as the fish approached their terminal tributaries. There was substantial variation in the migratory patterns exhibited by individual fish, although these patterns tended to be similar to the patterns exhibited by the regional stocks, particularly as the fish moved farther upriver from the tagging area. The dominant source of variation among fish reflected the average migration rate, with individual fish traveling slower in the lower basin exhibiting consistently slower migration rates as they moved upriver compared to their faster moving counterparts. This migratory pattern was consistent across stocks, and on average explained 74% of the within-stock variation in migration rate represented by the multivariate data. The second source of variation in migration rate reflected a shift in the relative swimming speeds of the individual fish as they progressed upriver. Although movement rates declined for nearly all of the fish during the migration, differences were observed in the pattern of the decline. Fish with faster migration rates in the lower river exhibited a pronounced decline in swimming speed as they moved upriver, whereas fish moving slower in the lower river displayed a more gradual decline in migration rate. On average, this migratory pattern explained 22% of the within-stock variation in migration rate represented by the multivariate data. Most fish (98%) exhibited continuous upriver movements and strong fidelity to the rivers they entered. However a small number of fish (n = 66) deviated from this pattern. Some of these individuals initially passed their final destination and continued upriver for varying distances before reversing direction, swimming back downstream, and entering their terminal tributary. Although most of these excursions were relatively short (< 30 km), there were several instances where fish traveled hundreds of kilometers out of their way. Thirty-four fish tracked to terminal tributaries subsequently left these rivers, and traveled to other terminal tributaries within the basin (n = 31) or were harvested in upriver fisheries (n = 3). Although most of these incidents involved nearby tributaries, major diversions were also observed, with several fish traveling over 300 km to natal rivers after leaving the initial tributary. Chinook salmon returns to the Yukon River typically consisted of a series of distinct and sizable increases in the number fish entering the river over the course of the run, commonly referred to as pulses. A large number of fish (n = 251) were radio tagged over a 4-day period during a pulse in 2003 to provide information on the progression of the pulse as it moved upriver. The time taken by the pulse to move past subsequent upriver locations increased as the fish moved farther upriver from the tagging area, with the fish passing sites located 580 and 800 km upriver over a span of 14 and 21 d, respectively. Although not surprising considering the extensive variation in migration rates observed among individual fish, this finding does suggest that these pulses do not represent cohesive aggregates of fish moving upriver. Unlike the well established methods used to estimate other life history characteristics, the development of quantitative methods for analyzing and modeling fish movements has lagged noticeably behind, due in part to the complexity associated with movement data and (prior to the advent of telemetry) the difficulty of collecting this type of information on free-ranging individuals. Two fundamentally different analytical approaches, hierarchical linear regression models and multivariate ordination, were used during this study to evaluate factors thought to influence the upriver movements of the fish. In spite of the inherent differences, both methods provided strikingly similar results, indicating that the study findings were not dependent on the approach used, and suggesting that the results were plausible based on the information available and the weight of evidence. Both analytical methods had advantages, and provided complementary information. With hierarchical linear models, it was possible to simultaneously evaluate a wide range of explanatory variables (in our case, both biological and environmental), which provided standardized comparisons and simplified the interpretation of the results. Since both fixed and random effects were incorporated in the models, it was possible to account for sources of variation when insufficient information was available to identify the underlining factors – an important consideration since few field studies provide comprehensive data. With multivariate ordination, separate analyzes were needed to examine the relationships between the migration rates and the biotic and physical variables. In addition to being cumbersome, this limitation made it more difficult to compare the relative influence of the different factors and interactions between factors. However, ordination was very useful as an exploratory tool. Although compartmentalized by stock, across fish comparisons were simple and relatively straightforward. Because the explanatory variables were evaluated separately in relation to the ordination score assigned to the fish, it was possible to examine and compare highly correlated variables. Ordination was also able to identify overall patterns within the data and assess the relative importance. While this can be accomplished within the framework of linear regression using mixture models to determine whether multiple distributions exist within the data, the process is much simpler with ordination. The migratory patterns of the fish were influenced by a wide range of factors, with evidentiary support for complex, multi-faceted relationships. Physical features of the basin demonstrated stronger explanatory power, accounting for over 70% of the observed variation in migration rate compared to 18% for the biological characteristics of the fish. Parameter estimates associated with the steepness of the migratory route and remaining distance the fish had to travel to reach their natal rivers were most strongly correlated with migration rate, with consistent relationships observed across stocks. Migration rates were also noticeably slower in extensively braided reaches of the basin. The weaker relationships between migration rate and biotic factors may reflect stabilizing selection on long-distance migrants. Smaller fish exhibited minimally faster swimming speeds on average than larger individuals. This relationship was stronger in highly braided reaches. Run timing was positively related to migration rate for most stocks. Surprisingly, upper basin stocks traveling farther upriver displayed progressively negative relationships, suggesting that late-run fish were moving slower. Ancillary information suggests that this decline may relate to deteriorating fish condition later in the season. Title: Distribution and movements of Chinook salmon, Oncorhynchus tshawytscha, returning to the Yukon River basin Author: Eiler, John H. Chinook salmon, Oncorhynchus tshawytscha, returning to the Yukon River basin and other large river systems in western Alaska have declined dramatically since the late 1990s. This continuing trend has raised concerns over the future status of the returns, and severely impacted commercial and subsistence fisheries within the drainage. Management is further complicated by the mixed-stock composition of the run, the presence of other temporally similar salmon species, and the need to equitably allocate harvests between the numerous fisheries and user groups scattered throughout the basin. Detailed information is needed on Chinook salmon run characteristics to better understand and manage the returns, and facilitate conservation efforts. However, this goal is exacerbated by the massive size and remote nature of the basin, the large number of highly mobile fish, and the compressed timing of the run. To address these challenges, radio telemetry was used to determine the stock composition and spawning distribution of the returns, and the migratory characteristics of the fish. The migratory patterns exhibited by returning salmon provide a number of insights into the status of the run. Since the Yukon River is essentially free-flowing (i.e., not regulated), this study also presented an opportunity to document the distribution and upriver movements of large returns of wild Chinook salmon under natural conditions. During 2002-2004, returning adult Chinook salmon were captured in the lower Yukon River (approximately 300 km upriver from the river mouth), tagged with radio transmitters, and tracked upriver using remote tracking stations located on important migratory routes and major spawning tributaries. Aerial tracking surveys were used to locate fish in spawning areas and between stations. The fish responded well to the capture and handling procedures, with most (2,790, 98%) resuming upriver movements. Although the fish initially displayed a negative tagging response, with slower migration rates observed immediately after release, the duration of this response was relatively short (several days) and less severe as the fish moved upriver. Independent measures indicated that the swimming speeds and timing of the fish upriver from the tagging area were comparable to untagged fish, suggesting that the tagging methods used were relatively benign. Fish returned to spawning areas throughout the basin, ranging from several hundred to over 3,000 km from the tagging area. Distribution patterns were similar across years, suggesting that the principal components of the run were identified. Most spawning fish were clustered in a number of key tributaries, with smaller numbers of fish located in other spatially isolated areas. The fish typically returned to clear water tributaries that were relatively entrenched, had moderate gradients, and were associated with upland areas. Fish were largely absent in lowland reaches characterized by meandering, low gradient, highly alluvial channels often associated with main river floodplains. There was suggestive evidence of mainstem spawning in reaches of the Upper Yukon. The status of fish remaining in other mainstem areas was less certain, and may represent local spawning activity or fish that died while in-transit to upriver areas. Although Chinook salmon spawned throughout the basin, the run was dominated by two regional components (Tanana and Upper Yukon), which annually comprised over 70% of the return. Substantially fewer fish returned to other areas ranging from 2-9% of the return, although the collective contribution of these stocks was appreciable. Most regional returns consisted of several principal stocks and a number of small, spatially isolated populations. Regional and stock composition estimates were similar across years even though differences in run abundance were reported, suggesting that these abundance differences were not related to regional or stock-specific differences. Run timing was relatively compressed compared to rivers in the southern portion of the range, with most stocks passing through the lower river over a 6-week period, ranging from 16 to 38 d. Run timing was generally earlier for stocks traveling farther upriver, although exceptions were noted. Lower basin stocks were primarily later run fish. Pronounced differences were observed in the migration rates (km/d) exhibited by regional stocks. Substantially slower swimming speeds were observed for fish returning to terminal tributaries in the lower basin ranging from 28-40 km/d compared to 52-62 km/d for upper basin stocks. The migratory patterns (migration rates in sequential reaches) of the fish also showed distinct regional differences. Average migration rates through the lower river were remarkably similar for the different stocks, ranging from 57-62 km/d, with most stocks exhibiting a general decline as the fish moved farther upriver. Tanana River stocks displayed a pronounced reduction in swimming speed after leaving the Yukon River main stem, with migration rates declining to 24 km/d on average as the fish approached their terminal tributaries. Conversely, upper basin stocks exhibited a relatively gradual (but variable) overall decline in migration rate even though these fish were traveling substantially greater distances upriver. Average migration rates for upper basin stocks ranged from 43-61 km/d as the fish approached their terminal tributaries. There was substantial variation in the migratory patterns exhibited by individual fish, although these patterns tended to be similar to the patterns exhibited by the regional stocks, particularly as the fish moved farther upriver from the tagging area. The dominant source of variation among fish reflected the average migration rate, with individual fish traveling slower in the lower basin exhibiting consistently slower migration rates as they moved upriver compared to their faster moving counterparts. This migratory pattern was consistent across stocks, and on average explained 74% of the within-stock variation in migration rate represented by the multivariate data. The second source of variation in migration rate reflected a shift in the relative swimming speeds of the individual fish as they progressed upriver. Although movement rates declined for nearly all of the fish during the migration, differences were observed in the pattern of the decline. Fish with faster migration rates in the lower river exhibited a pronounced decline in swimming speed as they moved upriver, whereas fish moving slower in the lower river displayed a more gradual decline in migration rate. On average, this migratory pattern explained 22% of the within-stock variation in migration rate represented by the multivariate data. Most fish (98%) exhibited continuous upriver movements and strong fidelity to the rivers they entered. However a small number of fish (n = 66) deviated from this pattern. Some of these individuals initially passed their final destination and continued upriver for varying distances before reversing direction, swimming back downstream, and entering their terminal tributary. Although most of these excursions were relatively short (< 30 km), there were several instances where fish traveled hundreds of kilometers out of their way. Thirty-four fish tracked to terminal tributaries subsequently left these rivers, and traveled to other terminal tributaries within the basin (n = 31) or were harvested in upriver fisheries (n = 3). Although most of these incidents involved nearby tributaries, major diversions were also observed, with several fish traveling over 300 km to natal rivers after leaving the initial tributary. Chinook salmon returns to the Yukon River typically consisted of a series of distinct and sizable increases in the number fish entering the river over the course of the run, commonly referred to as pulses. A large number of fish (n = 251) were radio tagged over a 4-day period during a pulse in 2003 to provide information on the progression of the pulse as it moved upriver. The time taken by the pulse to move past subsequent upriver locations increased as the fish moved farther upriver from the tagging area, with the fish passing sites located 580 and 800 km upriver over a span of 14 and 21 d, respectively. Although not surprising considering the extensive variation in migration rates observed among individual fish, this finding does suggest that these pulses do not represent cohesive aggregates of fish moving upriver. Unlike the well established methods used to estimate other life history characteristics, the development of quantitative methods for analyzing and modeling fish movements has lagged noticeably behind, due in part to the complexity associated with movement data and (prior to the advent of telemetry) the difficulty of collecting this type of information on free-ranging individuals. Two fundamentally different analytical approaches, hierarchical linear regression models and multivariate ordination, were used during this study to evaluate factors thought to influence the upriver movements of the fish. In spite of the inherent differences, both methods provided strikingly similar results, indicating that the study findings were not dependent on the approach used, and suggesting that the results were plausible based on the information available and the weight of evidence. Both analytical methods had advantages, and provided complementary information. With hierarchical linear models, it was possible to simultaneously evaluate a wide range of explanatory variables (in our case, both biological and environmental), which provided standardized comparisons and simplified the interpretation of the results. Since both fixed and random effects were incorporated in the models, it was possible to account for sources of variation when insufficient information was available to identify the underlining factors – an important consideration since few field studies provide comprehensive data. With multivariate ordination, separate analyzes were needed to examine the relationships between the migration rates and the biotic and physical variables. In addition to being cumbersome, this limitation made it more difficult to compare the relative influence of the different factors and interactions between factors. However, ordination was very useful as an exploratory tool. Although compartmentalized by stock, across fish comparisons were simple and relatively straightforward. Because the explanatory variables were evaluated separately in relation to the ordination score assigned to the fish, it was possible to examine and compare highly correlated variables. Ordination was also able to identify overall patterns within the data and assess the relative importance. While this can be accomplished within the framework of linear regression using mixture models to determine whether multiple distributions exist within the data, the process is much simpler with ordination. The migratory patterns of the fish were influenced by a wide range of factors, with evidentiary support for complex, multi-faceted relationships. Physical features of the basin demonstrated stronger explanatory power, accounting for over 70% of the observed variation in migration rate compared to 18% for the biological characteristics of the fish. Parameter estimates associated with the steepness of the migratory route and remaining distance the fish had to travel to reach their natal rivers were most strongly correlated with migration rate, with consistent relationships observed across stocks. Migration rates were also noticeably slower in extensively braided reaches of the basin. The weaker relationships between migration rate and biotic factors may reflect stabilizing selection on long-distance migrants. Smaller fish exhibited minimally faster swimming speeds on average than larger individuals. This relationship was stronger in highly braided reaches. Run timing was positively related to migration rate for most stocks. Surprisingly, upper basin stocks traveling farther upriver displayed progressively negative relationships, suggesting that late-run fish were moving slower. Ancillary information suggests that this decline may relate to deteriorating fish condition later in the season. Close