U.S. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

National Marine Fisheries Service

NOAA Technical Memorandum NMFS-NWFSC-66

Updated Status

of Federally Listed ESUs

of West Coast

Salmon and Steelhead

June 2005
NOAA Technical Memorandum

NMFS Series

The Northwest Fisheries Science Center of the National

Marine Fisheries Service, NOAA, uses the NOAA

Technical Memorandum NMFS series to issue informal scientific and technical publications when complete formal review and editorial processing are not

appropriate or feasible due to time constraints. Documents published in this series may be referenced in the

scientific and technical literature.

The NMFS-NWFSC Technical Memorandum series of

the Northwest Fisheries Science Center continues the

NMFS-F/NWC series established in 1970 by the

Northwest & Alaska Fisheries Science Center, which

has since been split into the Northwest Fisheries

Science Center and the Alaska Fisheries Science

Center. The NMFS-AFSC Technical Memorandum

series is now being used by the Alaska Fisheries

Science Center.

Reference throughout this document to trade names

does not imply endorsement by the National Marine

Fisheries Service, NOAA.

This document should be cited as follows:

Good, T.P., R.S. Waples, and P. Adams (editors).

2005. Updated status of federally listed ESUs of West

Coast salmon and steelhead. U.S. Dept. Commer.,

NOAA Tech. Memo. NMFS-NWFSC-66, 598 p.
NOAA Technical Memorandum NMFS-NWFSC-66

Updated Status

of Federally Listed ESUs

of West Coast

Salmon and Steelhead

Edited by

Thomas P. Good, Robin S. Waples, and Pete Adams*

From contributions by the editors and

Eric P. Bjorkstedt*, David Boughton*, Thomas Cooney,

Richard G. Gustafson, Peter W. Lawson, Steven T. Lindley*,

Paul McElhany, James M. Myers, Orlay Johnson,

Mary H. Ruckelshaus, Norma Jean Sands, Brian C. Spence*,

Sarah Sydor, Thomas C. Wainwright, and Laurie A. Weitkamp

Northwest Fisheries Science Center

2725 Montlake Boulevard East

Seattle, Washington 98112

Southwest Fisheries Science Center

Santa Cruz Laboratory

110 Shaffer Road

Santa Cruz, California 95060

June 2005

U.S. DEPARTMENT OF COMMERCE

Carlos M. Gutierrez, Secretary

National Oceanic and Atmospheric Administration

Vice Admiral Conrad C. Lautenbacher, Jr. USN (Ret), Administrator

National Marine Fisheries Service

William T. Hogarth, Assistant Administrator for Fisheries

*
Most NOAA Technical Memorandums NMFS-NWFSC

are available online at the Northwest Fisheries Science

Center web site (http://www.nwfsc.noaa.gov)

Copies are also available from:

National Technical Information Service

5285 Port Royal Road

Springfield, VA 22161

phone orders (1-800-553-6847)

e-mail orders (orders@ntis.fedworld.gov)

ii
Table of Contents 

List of Figures............................................................................................................................................xiii

List of Tables ............................................................................................................................................xxv

Executive Summary .................................................................................................................................xxxi

Acknowledgments..................................................................................................................................xxxiii

Abbreviations and Acronyms .................................................................................................................xxxv

1. Introduction (By Robin S. Waples and Thomas C. Wainwright) .............................................................3

ESU Determinations..................................................................................................................................4

Geographic Boundaries .........................................................................................................................5

Artificial Propagation ............................................................................................................................5

Resident Fish .........................................................................................................................................7

Risk Assessments....................................................................................................................................11

ESA Definitions...................................................................................................................................11

Factors for Decline ..............................................................................................................................11

Artificial Propagation ..........................................................................................................................12

Resident Fish .......................................................................................................................................13

Factors Considered in Status Assessments..........................................................................................14

Scoring VSP Criteria ...........................................................................................................................15

Recent Events......................................................................................................................................15

Historical Distribution and Abundance ...............................................................................................15

Marine Productivity.............................................................................................................................17

Overall Risk Assessment .....................................................................................................................19

2. Methods (By Thomas P. Good and Sarah Sydor)...................................................................................20

Recent Abundance...................................................................................................................................20

Trends in Abundance ..............................................................................................................................21

Population Growth Rate ..........................................................................................................................21

Calculating Recruits................................................................................................................................24

Population Viability Analysis .................................................................................................................24

3. Background and History of Chinook Salmon Listings (By James M. Myers) .......................................27

4. Snake River Fall-Run Chinook Salmon ESU (By Thomas Cooney)......................................................29

Summary of Previous BRT Conclusions.................................................................................................30

New Data and Updated Analyses............................................................................................................30

Abundance ...........................................................................................................................................30

Productivity .........................................................................................................................................33

Harvest Impacts...................................................................................................................................34

Mainstem Hydropower Impacts ..........................................................................................................35

Habitat .................................................................................................................................................35

iii 
New Hatchery Information......................................................................................................................35

5. Snake River Spring/Summer-Run Chinook Salmon ESU (By Thomas Cooney)...................................37

Summary of Previous BRT Conclusions.................................................................................................38

New Data and Updated Analyses............................................................................................................39

Abundance ...........................................................................................................................................39

Productivity .........................................................................................................................................41

Hydropower Impacts ...........................................................................................................................41

Harvest.................................................................................................................................................44

Habitat .................................................................................................................................................44

New Hatchery Information......................................................................................................................44

6. Upper Columbia River Spring-Run Chinook Salmon ESU (By Thomas Cooney) ................................53

Summary of Previous BRT Conclusions.................................................................................................54

New Data and Updated Analyses............................................................................................................54

New Hatchery Information......................................................................................................................59

Comparison with Previous Data..............................................................................................................61

7. Puget Sound Chinook Salmon ESU (By Mary H. Ruckelshaus and Norma Jean Sands) ......................65

Summary of Previous BRT Conclusions.................................................................................................65

Status and Trends.................................................................................................................................65

Threats.................................................................................................................................................66

ESU Status at a Glance ........................................................................................................................67

ESU Structure ......................................................................................................................................67

Abundance of Natural Spawners .........................................................................................................67

Trends in Natural Spawners.................................................................................................................82

Updated Threats Information...............................................................................................................95

Comparison with Previous Data..............................................................................................................97

8. Lower Columbia River Chinook Salmon ESU (By Paul McElhany).....................................................99

Summary of Previous BRT Conclusions.................................................................................................99

New Data and Updated Analyses............................................................................................................99

Historical Population Structure............................................................................................................99

Abundance and Trends......................................................................................................................100

EDT-Based Estimates of Historical Abundance................................................................................122

Loss of Habitat from Barriers............................................................................................................123

New Hatchery and ESU Information ....................................................................................................123

Recent Hatchery Releases..................................................................................................................123

Comparison with Previous Data ........................................................................................................125

9. Upper Willamette River Chinook Salmon ESU (By Paul McElhany)..................................................126

Summary of Previous BRT Conclusions...............................................................................................126

New Data and Updated Analyses..........................................................................................................126

Historical Population Structure..........................................................................................................127

Abundance and Trends......................................................................................................................128

Loss of Habitat from Barriers............................................................................................................132

Hatchery Releases..............................................................................................................................132

10. California Coastal Chinook Salmon ESU (By Eric P. Bjorkstedt).....................................................135

Summary of Previous BRT Conclusions...............................................................................................135

ESU Structure ....................................................................................................................................135

iv
Summary of Risk Factors and Status.................................................................................................135

New Data and Updated Analyses..........................................................................................................137

Abundance and Trends......................................................................................................................137

Summary............................................................................................................................................142

New Hatchery Information....................................................................................................................142

Freshwater Creek...............................................................................................................................143

Mad River..........................................................................................................................................143

Eel River............................................................................................................................................143

Mattole River.....................................................................................................................................143

Russian River.....................................................................................................................................144

Summary............................................................................................................................................144

Comparison with Previous Data............................................................................................................144

11. Sacramento River Winter-Run Chinook Salmon ESU (By Steven T. Lindley) .................................145

Summary of Previous BRT Conclusions...............................................................................................145

Summary of Major Risk Factors and Status Indicators.....................................................................145

Previous BRT Conclusions................................................................................................................146

Viability Assessments........................................................................................................................146

Draft Recovery Plan ..........................................................................................................................146

New Abundance Data ........................................................................................................................146

Harvest Impacts.................................................................................................................................150

New Hatchery Information....................................................................................................................151

New Comments.....................................................................................................................................151

12. Central Valley Spring-Run Chinook Salmon ESU (By Steven T. Lindley).......................................153

Summary of Previous BRT Conclusions...............................................................................................153

Summary of Major Risk Factors and Status Indicators.....................................................................153

Previous BRT Conclusions................................................................................................................155

New Data and Updated Analyses..........................................................................................................155

Status Assessments............................................................................................................................155

Population Structure ..........................................................................................................................156

Historical Habitat Loss......................................................................................................................158

Life History........................................................................................................................................158

Harvest Information...........................................................................................................................158

Abundance Data.................................................................................................................................159

New Hatchery Information....................................................................................................................160

New Comments.....................................................................................................................................160

Comparison with Previous Data............................................................................................................162

13. Chinook Salmon BRT Conclusions (By Robin S. Waples)................................................................163

Snake River Fall-Run Chinook Salmon ESU........................................................................................163

Snake River Spring/Summer-Run Chinook Salmon ESU.....................................................................164

Upper Columbia River Spring-Run Chinook Salmon ESU ..................................................................165

Puget Sound Chinook Salmon ESU......................................................................................................165

Lower Columbia River Chinook Salmon ESU .....................................................................................166

Upper Willamette River Chinook Salmon ESU....................................................................................166

California Coastal Chinook Salmon ESU .............................................................................................167

Sacramento River Winter-Run Chinook Salmon ESU..........................................................................167

Central Valley Spring-Run Chinook Salmon ESU ...............................................................................167

v
14. Background and History of Steelhead Listings (By Thomas P. Good and Robin S. Waples)............ 171

Background ...........................................................................................................................................171

Resident Fish.........................................................................................................................................173

15. Snake River Basin Steelhead ESU (By Thomas Cooney) ..................................................................176

Historical Returns..................................................................................................................................176

Summary of Previous BRT Conclusions...............................................................................................177

New Data and Updated Analyses..........................................................................................................177

Abundance and Trends......................................................................................................................177

Resident O. mykiss Considerations....................................................................................................182

New Hatchery Information....................................................................................................................187

Artificial Production History .............................................................................................................187

Hatchery Summaries..........................................................................................................................190

16. Upper Columbia River Steelhead ESU (By Thomas Cooney) ...........................................................192

Summary of Previous BRT Conclusions...............................................................................................193

New Data and Updated Analyses..........................................................................................................193

Population Definitions and Criteria ...................................................................................................193

Current Abundance............................................................................................................................193

Current Productivity ..........................................................................................................................196

Resident O. mykiss Considerations....................................................................................................196

New Hatchery Information....................................................................................................................200

17. Middle Columbia River Steelhead ESU (By Thomas Cooney)..........................................................201

Summary of Previous BRT Conclusions...............................................................................................201

New Data and Updated Analyses..........................................................................................................202

Abundance .........................................................................................................................................202

Productivity .......................................................................................................................................203

Resident O. mykiss Considerations....................................................................................................203

New Hatchery Information....................................................................................................................207

18. Lower Columbia River Steelhead ESU (By Paul McElhany) ............................................................215

Summary of Previous BRT Conclusions...............................................................................................215

New Data and Updated Analyses..........................................................................................................215

Historical Population Structure..........................................................................................................215

Abundance and Trends......................................................................................................................217

Resident O. mykiss Considerations....................................................................................................223

19. Upper Willamette River Steelhead ESU (By Paul McElhany)...........................................................237

Summary of Previous BRT Conclusions...............................................................................................237

New Data and Updated Analyses..........................................................................................................237

Historical Population Structure..........................................................................................................237

Abundance and Trends......................................................................................................................237

Loss of Habitat from Barriers............................................................................................................245

Resident O. mykiss Considerations....................................................................................................245

ESU Summary.......................................................................................................................................246

20. Northern California Steelhead ESU (By David Boughton and Eric P. Bjorkstedt)............................247

Summary of Previous BRT Conclusions...............................................................................................247

Summary of Major Risks and Status Indicators ................................................................................247

vi
Listing Status.....................................................................................................................................248

New Data and Updated Analyses..........................................................................................................250

Updated Eel River Data .....................................................................................................................251

New Time Series................................................................................................................................251

Juvenile Data .....................................................................................................................................252

Possible Changes in Harvest Impacts................................................................................................254

Resident O. mykiss Considerations....................................................................................................256

New Hatchery Information....................................................................................................................256

Mad River Hatchery (Mad River Steelhead, CDFG).........................................................................256

Yager Creek Hatchery (Yager Creek Steelhead [Pacific Lumber Company])..................................257

North Fork Gualala River Hatchery (Gualala River Steelhead Project, CDFG) ...............................258

21. Central California Coast Steelhead ESU (By David Boughton and Eric P. Bjorkstedt).....................259

Summary of Previous BRT Conclusions...............................................................................................259

Summary of Major Risks and Status Indicators ................................................................................259

Previous BRT Conclusions................................................................................................................261

New Data and Updated Analyses..........................................................................................................261

Juvenile Data .....................................................................................................................................261

Possible Changes in Harvest Impacts................................................................................................262

Resident O. mykiss Considerations....................................................................................................264

New Hatchery Information....................................................................................................................265

Don Clausen Fish Hatchery (Warm Springs Steelhead, CDFG).......................................................265

Monterey Bay Salmon and Trout Project (Kingfisher Flat [Big Creek] Hatchery; Scott Creek 

Steelhead) ..........................................................................................................................................266

22. South-Central California Coast Steelhead ESU (By David Boughton)..............................................268

Summary of Previous BRT Conclusions...............................................................................................268

Summary of Major Risks and Status Indicators ................................................................................268

Previous BRT Conclusions................................................................................................................269

New Data and Updated Analyses..........................................................................................................269

Current versus Historical Distribution...............................................................................................269

Review of Historical Run Sizes.........................................................................................................270

Abundance in the Carmel River.........................................................................................................271

Possible Changes in Harvest Impacts................................................................................................273

Resident O. mykiss Considerations....................................................................................................274

Minor Barriers ...................................................................................................................................274

New Hatchery Information....................................................................................................................275

Whale Rock Hatchery (Whale Rock Steelhead, CDFG) ...................................................................275

23. Southern California Steelhead ESU (By David Boughton)................................................................277

Summary of Previous BRT Conclusions...............................................................................................277

Summary of Major Risks and Status Indicators ................................................................................277

Previous BRT Conclusions................................................................................................................278

New Data and Updated Analyses..........................................................................................................278

Current Distribution versus Historical Distribution...........................................................................278

Recent Colonization Events...............................................................................................................279

Review of Historical Run Sizes.........................................................................................................280

Recent Run Sizes of Large River Systems ........................................................................................283

Harvest Impacts.................................................................................................................................285

Resident O. mykiss Considerations....................................................................................................286

vii
24. California Central Valley Steelhead ESU (By Steven T. Lindley).....................................................288

Summary of Previous BRT Conclusions...............................................................................................288

Major Risk Factors and Status Indicators..........................................................................................288

Previous BRT Conclusions................................................................................................................288

Historical Distribution and Abundance .............................................................................................290

Current Abundance............................................................................................................................290

Current Distribution...........................................................................................................................292

Resident O. mykiss Considerations....................................................................................................292

Harvest Impacts.................................................................................................................................297

New Hatchery Information....................................................................................................................297

Comparison with Previous Data............................................................................................................297

25. Steelhead BRT Conclusions (By Robin S. Waples) ...........................................................................300

Snake River Basin Steelhead ESU........................................................................................................300

Upper Columbia River Steelhead ESU .................................................................................................301

Middle Columbia River Steelhead ESU................................................................................................302

Lower Columbia River Steelhead ESU.................................................................................................303

Upper Willamette River Steelhead ESU ...............................................................................................303

Northern California Steelhead ESU ......................................................................................................304

Central California Coast Steelhead ESU...............................................................................................304

South-Central California Coast Steelhead ESU ....................................................................................305

Southern California Steelhead ESU ......................................................................................................306

California Central Valley Steelhead ESU .............................................................................................306

26. Background and History of Coho Salmon Listings (By Laurie A. Weitkamp)..................................311

27. Oregon Coast Coho Salmon ESU (By Peter W. Lawson) ..................................................................313

Summary of Previous BRT Conclusions...............................................................................................313

Major Risk Factors and Status Indicators..........................................................................................313

Evaluation of ESU under Conditions in 1997 ...................................................................................313

Population Abundance.......................................................................................................................314

Population Trends and Production.....................................................................................................315

Hatchery Production and Genetic Risks............................................................................................315

Habitat Conditions.............................................................................................................................316

Influence of OCSRI...........................................................................................................................316

Harvest Measures...............................................................................................................................316

Hatchery Measures ............................................................................................................................316

Previous BRT Conclusions................................................................................................................317

New Comments.....................................................................................................................................319

Alsea Valley Alliance v. Evans ..........................................................................................................319

Petition for Listing.............................................................................................................................319

Independent Multidisciplinary Science Team ...................................................................................320

Douglas County Board of Commissioners ........................................................................................320

New Data and Updated Analyses..........................................................................................................321

Population Abundance.......................................................................................................................321

Growth Rates and Productivity..........................................................................................................327

Population Spatial Structure ..............................................................................................................328

Population Diversity ..........................................................................................................................328

Harvest Impacts.................................................................................................................................329

Habitat Condition...............................................................................................................................331

New Hatchery Information....................................................................................................................332

viii
28. Southern Oregon/Northern California Coast Coho Salmon ESU (By Brian C. Spence, Thomas C. 

Wainwright, and Eric P. Bjorkstedt).........................................................................................................339

Summary of Previous BRT Conclusions...............................................................................................339

Status Indicators and Major Risk Factors..........................................................................................339

Previous BRT Conclusions................................................................................................................343

New Data and Updated Analyses..........................................................................................................343

California Populations.......................................................................................................................343

CDFG Presence-Absence Analysis ...................................................................................................344

NMFS Presence-Absence Analysis...................................................................................................345

Adult Time Series..............................................................................................................................350

Juvenile Time Series..........................................................................................................................351

Oregon Populations ...........................................................................................................................351

New Hatchery Information....................................................................................................................356

Iron Gate Hatchery ............................................................................................................................357

Trinity River Hatchery.......................................................................................................................359

Mad River Hatchery ..........................................................................................................................360

Rowdy Creek Hatchery......................................................................................................................360

Cole Rivers Hatchery.........................................................................................................................360

Summary............................................................................................................................................361

Comparison with Previous Data............................................................................................................362

29. Central California Coast Coho Salmon ESU (By Brian C. Spence and Eric P. Bjorkstedt)...............364

Summary of Previous BRT Conclusions...............................................................................................364

Status Indicators and Major Risk Factors..........................................................................................364

Previous BRT Conclusions................................................................................................................367

New Data and Updated Analyses..........................................................................................................367

CDFG Presence-Absence Analysis ...................................................................................................368

NMFS Presence-Absence Analysis...................................................................................................368

Adult Time Series..............................................................................................................................372

Smolt Time Series..............................................................................................................................372

Juvenile Time Series..........................................................................................................................374

New Comments.....................................................................................................................................375

New Hatchery Information....................................................................................................................375

Noyo Egg Collecting Station .............................................................................................................375

Don Clausen (Warm Springs) Hatchery ............................................................................................376

Kingfisher Flat (Big Creek) Hatchery ...............................................................................................377

Summary ...............................................................................................................................................378

Artificial Propagation ........................................................................................................................378

Harvest Impacts.................................................................................................................................378

Comparison with Previous Data............................................................................................................379

30. Lower Columbia River Coho Salmon ESU (By Paul McElhany) ......................................................381

Summary of Previous BRT Conclusions...............................................................................................381

New Data and Updated Analyses..........................................................................................................381

Historical Population Structure..........................................................................................................381

Abundance and Trends......................................................................................................................383

Other Oregon Populations .................................................................................................................386

Washington Populations....................................................................................................................388

New Hatchery Information....................................................................................................................389

Hatchery Production ..........................................................................................................................389

ix
Loss of Habitat from Barriers............................................................................................................389

ESU Summary ...................................................................................................................................389

31. Coho Salmon BRT Conclusions (By Robin S. Waples).....................................................................400

Oregon Coast Coho Salmon ESU .........................................................................................................400

Southern Oregon/Northern California Coast Coho Salmon ESU .........................................................401

Central California Coast Coho Salmon ESU ........................................................................................402

Lower Columbia River Coho Salmon ESU ..........................................................................................403

32. Background and History of Sockeye Salmon Listings (By Richard G. Gustafson) ...........................407

33. Snake River Sockeye Salmon ESU (By Robin S. Waples) ................................................................410

Summary of Previous BRT Conclusions...............................................................................................410

New Data and Updated Analyses..........................................................................................................411

34. Ozette Lake Sockeye Salmon ESU (By Mary H. Ruckelshaus).........................................................415

Summary of Previous BRT Conclusions...............................................................................................415

Status and Trends...............................................................................................................................415

Threats...............................................................................................................................................415

Previous BRT Conclusions................................................................................................................415

New Data and Updated Analyses..........................................................................................................416

ESU Status at a Glance ......................................................................................................................416

ESU Structure ....................................................................................................................................416

Updated Status Information...............................................................................................................416

Updated Threats Information.............................................................................................................419

35. Sockeye Salmon BRT Conclusions (By Robin S. Waples)................................................................421

Snake River Sockeye Salmon ESU.......................................................................................................421

Ozette Lake Sockeye Salmon ESU .......................................................................................................421

36. Background and History of Chum Salmon Listings (By Orlay Johnson)...........................................425

37. Hood Canal Summer-Run Chum Salmon ESU (By Mary H. Ruckelshaus and Norma Jean Sands) .427

Summary of Previous BRT Conclusions...............................................................................................427

Status and Trends...............................................................................................................................427

Previously Reported Threats..............................................................................................................427

Previous BRT Conclusions................................................................................................................428

New Data and Updated Analyses..........................................................................................................428

ESU Status at a Glance ......................................................................................................................428

ESU Structure ....................................................................................................................................428

Abundance of Natural Spawners .......................................................................................................429

Trends in Natural Spawners...............................................................................................................438

Updated Information on Potential Threats.........................................................................................439

38. Columbia River Chum Salmon ESU (By Paul McElhany) ................................................................443

Summary of Previous BRT Conclusions...............................................................................................443

New Data and Updated Analyses..........................................................................................................443

Results of New Analyses...................................................................................................................443

Abundance, Distribution, and Trends................................................................................................444

Reasons for 2002 Increase in Abundance..........................................................................................453

EDT-Based Estimates of Historical Abundance................................................................................453

Loss of Habitat from Barriers............................................................................................................454

x
New ESU Information...........................................................................................................................454

39. Chum Salmon BRT Conclusions (By Robin S. Waples)....................................................................456

Hood Canal Summer-Run Chum Salmon ESU.....................................................................................456

Columbia River Chum Salmon ESU.....................................................................................................457

References.................................................................................................................................................461

Appendix A: Chinook Salmon..................................................................................................................513

Appendix B: Steelhead .............................................................................................................................555

Appendix C: Coho Salmon .......................................................................................................................579

Appendix D: Sockeye Salmon ..................................................................................................................585

Appendix E: Chum Salmon ......................................................................................................................587

 

xi
 

xii 
List of Figures 

Figure 1. Summary of the hatchery categorization system..........................................................................7

Figure 2. Monthly values for the Pacific Decadal Oscillation (PDO) index, which is based on sea 

surface temperatures in the North Pacific...................................................................................................17

Figure 3. Estimated spawning escapement of fall-run Chinook salmon at Lower Granite Dam, 

1975–2001. .................................................................................................................................................33

Figure 4. Returns per spawner plotted against broodyear escapements for Snake River fall-run 

Chinook salmon, 1975–1997 ......................................................................................................................34

Figure 5. Aggregate (ocean and in-river fisheries) exploitation rate index for Snake River fall-run 

Chinook salmon, 1975–2001.. ....................................................................................................................35

Figure 6. Snake River spring-run Chinook salmon escapement over Lower Granite Dam, 1979–2001...39

Figure 7. Snake River summer-run Chinook salmon escapement, 1979–2002 .........................................40

Figure 8. Tucannon River spring-run Chinook salmon spawning escapement, 1979–2001......................40

Figure 9. Wenaha River spring-run Chinook spawning escapement, 1964–1996.....................................41

Figure 10. Minam River Chinook salmon spawning escapements, 1964–2001 ........................................46

Figure 11. Lostine River spring-run Chinook salmon total counts, 1964–2001........................................46

Figure 12. Upper Grande Ronde River spring-run Chinook salmon redd counts, 1960–2001..................47

Figure 13. Imnaha River spring-run Chinook salmon spawning escapement, 1953–2001........................47

Figure 14. Poverty Flat summer-run Chinook salmon spawning escapement, 1957–2001.......................48

Figure 15. Johnson Creek summer-run Chinook salmon spawning escapement, 1957–2001...................48

Figure 16. Sulphur Creek spring-run Chinook salmon spawning escapement, 1957–2001 ......................49

Figure 17. Bear Valley/Elk Creek spring-run Chinook spawning escapement, 1966–2001......................49

Figure 18. Marsh Creek spring-run Chinook salmon spawning escapement, 1957–2001.........................50

Figure 19. Total redd count in the Lemhi River (includes hatchery and natural returns), 1957–2001 ......50

Figure 20. Upper Valley Creek spring-run Chinook salmon redd counts, 1957–2001..............................51

Figure 21. East Fork Salmon River summer-run Chinook salmon redds per mile, 1957–2001 ................51

Figure 22. Short-term median growth rate (1990–2001) for total spawners for Snake River 

spring/summer-run production areas ..........................................................................................................52

Figure 23. Spring/summer-run Chinook salmon returns per spawner for the Minam River, 

1964–1997 ..................................................................................................................................................52

Figure 24. Wenatchee River spring-run Chinook salmon spawning escapement, 1960–2001..................56

Figure 25. Entiat River spring-run Chinook salmon spawning escapement, 1960–2001 ..........................57

Figure 26. Methow River spring-run Chinook salmon spawning escapement, 1960–2001... ..................57

xiii
Figure 27. Wenatchee River spring-run Chinook salmon returns per spawner by broodyear, 

1960–2001 (returns to spawning grounds)..................................................................................................58

Figure 28. Methow River spring-run Chinook salmon returns per spawner by broodyear, 1960–1995....58

Figure 29. Entiat River spring-run Chinook salmon returns per spawner by broodyear, 1960–1997. ......59

Figure 30. Long-term (1960–2001) annual growth rates (λ) for Upper Columbia River spring-run 

Chinook salmon ESU populations..............................................................................................................63

Figure 31. Short-term (1990–2001) annual growth rates (λ) for Upper Columbia River spring-run 

Chinook salmon ESU populations..............................................................................................................64

Figure 32. Total and natural-origin spawner abundance estimates versus year for the North Fork 

Nooksack River population of Chinook salmon, 1984–2001 .....................................................................71

Figure 33. Total and natural-origin spawner abundance estimates versus year for the South Fork 

Nooksack River population of Chinook salmon, 1984–2001 .....................................................................71

Figure 34. Total and natural-origin spawner abundance estimates versus year for the lower 

Skagit River population of Chinook salmon, 1951–2002...........................................................................72

Figure 35. Total and natural-origin spawner abundance estimates versus year for the upper 

Skagit River population of Chinook salmon, 1951–2002...........................................................................72

Figure 36. Total and natural-origin spawner abundance estimates versus year for the upper 

Cascade River population of Chinook salmon, 1984–2002........................................................................73

Figure 37. Total spawner abundance estimates versus year for the lower Sauk River population of 

Chinook salmon, 1952–2002. .....................................................................................................................73

Figure 38. Total spawner abundance estimates versus year for the upper Sauk River population of 

Chinook salmon, 1960–2002. .....................................................................................................................74

Figure 39. Total spawner abundance estimates versus year for the Suiattle River population of 

Chinook salmon, 1952–2002 ......................................................................................................................74

Figure 40. Total and natural-origin spawner abundance estimates versus year for the North Fork 

Stillaguamish River population of Chinook salmon, 1974–2002 ...............................................................75

Figure 41. Total spawner abundance estimates versus year for the South Fork Stillaguamish River 

population of Chinook salmon, 1974–2003................................................................................................75

Figure 42. Total and natural-origin spawner abundance estimates versus year for the Skykomish 

River population of Chinook salmon, 1965–2002 ......................................................................................76

Figure 43. Total and natural-origin spawner abundance estimates versus year for the Snoqualmie 

River population of Chinook salmon, 1965–2003 ......................................................................................76

Figure 44. Total spawner abundance estimates versus year for the north Lake Washington tributaries 

population of Chinook salmon, 1983–2002................................................................................................77

Figure 45. Total spawner abundance estimates versus year for the Cedar River population of Chinook 

salmon, 1965–2002.....................................................................................................................................77

Figure 46. Total and natural-origin spawner abundance estimates versus year for the Green/Duwamish 

rivers population of Chinook salmon, 1967–2002......................................................................................78

Figure 47. Total spawner abundance estimates versus year for the Puyallup River population of 

Chinook salmon, 1969–2002 ......................................................................................................................78

xiv
Figure 48. Total spawner abundance estimates versus year for the White River population of Chinook 

salmon, 1970–2002.....................................................................................................................................79

Figure 49. Total spawner abundance estimates versus year for the Nisqually River population of 

Chinook salmon, 1968–2002 ......................................................................................................................79

Figure 50. Total spawner abundance estimates versus year for the Skokomish River population of 

Chinook salmon, 1987–2003. .....................................................................................................................80

Figure 51. Total spawner abundance estimates versus year for the Dosewallips/Hamma 

Hamma/Duckabush rivers population of Chinook salmon, 1967–2002 .....................................................80

Figure 52. Total spawner abundance estimates versus year for the Dungeness River population of 

Chinook salmon, 1986–2002. .....................................................................................................................81

Figure 53. Total spawner abundance estimates versus year for the Elwha River population of 

Chinook salmon, 1986–2001 ......................................................................................................................81

Figure 54. Preharvest recruits and spawners versus broodyear for the North Fork Nooksack River 

Chinook salmon population, 1984–2001 ....................................................................................................84

Figure 55. Preharvest recruits and spawners versus broodyear for the South Fork Nooksack River 

Chinook salmon population, 1984–2001 ....................................................................................................84

Figure 56. Preharvest recruits and spawners versus broodyear for the lower Skagit River Chinook 

salmon population, 1951–2002...................................................................................................................85

Figure 57. Preharvest recruits and spawners versus broodyear for the upper Skagit River Chinook 

salmon population, 1951–2002...................................................................................................................85

Figure 58. Preharvest recruits and spawners versus broodyear for the upper Cascade River Chinook 

salmon population, 1984–2002...................................................................................................................86

Figure 59. Preharvest recruits and spawners versus broodyear for the lower Sauk Chinook salmon 

population, 1951–2002 ...............................................................................................................................86

Figure 60. Preharvest recruits and spawners versus broodyear for the upper Sauk River Chinook 

salmon population, 1951–2002...................................................................................................................87

Figure 61. Preharvest recruits and spawners versus broodyear for the Suiattle River Chinook 

salmon population, 1951–2002...................................................................................................................87

Figure 62. Preharvest recruits and spawners versus broodyear for the North Fork Stillaguamish River 

Chinook salmon population, 1974–2002 ....................................................................................................88

Figure 63. Preharvest recruits and spawners versus broodyear for the South Fork Stillaguamish River 

Chinook salmon population, 1974–2002 ....................................................................................................88

Figure 64. Preharvest recruits and spawners versus broodyear for the Skykomish River Chinook 

salmon population, 1965–2002...................................................................................................................89

Figure 65. Preharvest recruits and spawners versus broodyear for the Snoqualmie River Chinook 

salmon population, 1965–2002...................................................................................................................89

Figure 66. Preharvest recruits and spawners versus broodyear for the north Lake Washington 

tributaries Chinook salmon population, 1983–2002 ...................................................................................90

Figure 67. Preharvest recruits and spawners versus broodyear for the Cedar River Chinook salmon 

population, 1965–2002 ...............................................................................................................................90

xv
Figure 68. Preharvest recruits and spawners versus broodyear for the Green River Chinook salmon 

population, 1967–2002 ...............................................................................................................................91

Figure 69. Preharvest recruits and spawners versus broodyear for the Puyallup River Chinook salmon 

population, 1968–2002 ...............................................................................................................................91

Figure 70. Preharvest recruits and spawners versus broodyear for the White River Chinook salmon 

population, 1970–2002 ...............................................................................................................................92

Figure 71. Preharvest recruits and spawners versus broodyear for the Nisqually River Chinook salmon 

population, 1968–2002 ...............................................................................................................................92

Figure 72. Preharvest recruits and spawners versus broodyear for the Skokomish River Chinook 

salmon population, 1987–2002...................................................................................................................93

Figure 73. Preharvest recruits and spawners versus broodyear for the Dosewallips River Chinook 

salmon population, 1967–2002...................................................................................................................93

Figure 74. Preharvest recruits and spawners versus broodyear for the Dungeness River Chinook 

salmon population, 1986–2002................................................................................................................... 94

Figure 75. Preharvest recruits and spawners versus broodyear for the Elwha River Chinook salmon 

population, 1986–2001 ...............................................................................................................................95

Figure 76. Historical independent Lower Columbia River ESU early and late-fall-run Chinook 

salmon populations ...................................................................................................................................100

Figure 77. Historical independent Lower Columbia River ESU spring-run Chinook salmon 

populations................................................................................................................................................101

Figure 78. Big White Salmon River fall-run Chinook salmon total spawner abundance, 1967–2001....104

Figure 79. Clackamas River fall-run Chinook salmon total spawner abundance, 1967–2001. ...............105

Figure 80. Coweeman River fall-run Chinook salmon total spawner abundance, 1964–2001................105

Figure 81. Lower Cowlitz River fall-run Chinook salmon spawner abundance, 1964–2000..................106

Figure 82. Estimate of fall-run Chinook preharvest recruits and spawners in the Cowlitz River, 

1980–2001. ...............................................................................................................................................106

Figure 83. East Fork Lewis River fall-run Chinook salmon total spawner abundance, 1980–2001........107

Figure 84. Estimate of fall-run Chinook salmon spawner abundance preharvest recruits and 

spawners in the East Fork Lewis River, 1980–2001.................................................................................107

Figure 85. Elochoman River fall-run Chinook salmon spawner abundance, 1964–2001........................108

Figure 86. Estimate of fall-run Chinook salmon preharvest recruits and spawners in the Elochoman 

River, 1980–2001......................................................................................................................................108

Figure 87. Grays River fall-run Chinook salmon spawner abundance, 1964–2001. ...............................109

Figure 88. Estimate of Grays River fall-run Chinook salmon preharvest recruits and spawners, 

1980–2001. ...............................................................................................................................................109

Figure 89. Kalama River fall-run Chinook salmon spawner abundance, 1964–2001. ............................110

Figure 90. Estimate of Kalama River fall-run Chinook salmon preharvest recruits and spawners, 

1980–2001. ...............................................................................................................................................110

Figure 91. Lewis River late-fall-run (bright) Chinook salmon spawner abundance, 1964–2001............111

xvi
Figure 92. Estimate of Lewis River late-fall-run (bright) Chinook salmon preharvest recruits and 

spawners, 1980–2001................................................................................................................................111

Figure 93. Mill, Germany, and Abernathy creeks fall-run Chinook salmon spawner abundance, 

1980–2001. ...............................................................................................................................................112

Figure 94. Estimate of Mill, Germany, and Abernathy creeks fall-run Chinook salmon preharvest 

recruits and spawners, 1980–2001............................................................................................................112

Figure 95. Sandy River fall-run Chinook salmon spawner abundance, 1988–2001................................113

Figure 96. Sandy River late-fall-run (bright) Chinook salmon spawner abundance, 1984–2001............113

Figure 97. Washougal River fall-run Chinook salmon spawner abundance, 1964–2001........................114

Figure 98. Estimate of Washougal River fall-run Chinook salmon preharvest recruits and spawners 

1980–2001 ................................................................................................................................................114

Figure 99. Wind River fall-run Chinook salmon total spawner abundance, 1964–2001.........................115

Figure 100. Cowlitz River spring-run Chinook salmon total spawner abundance below Mayfield Dam, 

1980–2001 ................................................................................................................................................115

Figure 101. Kalama River spring-run Chinook salmon total spawners, 1980–2001 ...............................116

Figure 102. Lewis River spring-run Chinook salmon total spawner abundance below Merwin Dam, 

1980–2001 ................................................................................................................................................116

Figure 103. Youngs Bay Chinook salmon per mile, 1972–2001.............................................................117

Figure 104. Big Creek Chinook salmon per mile, 1970–2001 ................................................................117

Figure 105. Clatskanie River Chinook salmon per mile, 1970–2001 ......................................................118

Figure 106. Historical populations of spring-run Chinook salmon in the Upper Willamette 

River ESU.................................................................................................................................................127

Figure 107. Number of spring-run Chinook salmon passing Willamette Falls, 1953–2001....................128

Figure 108. Number of spring-run Chinook salmon passing North Fork Dam on the Clackamas 

River, 1958–2002......................................................................................................................................129

Figure 109. North Santiam River Chinook salmon redds per mile, 1996–2002......................................130

Figure 110. Number of McKenzie River spring-run Chinook salmon at Leaburg Dam, 1970–2001......131

Figure 111. Number of fall-run Chinook salmon at Willamette Falls, 1952–2001 .................................133

Figure 112. Number of Chinook salmon at the weir on Freshwater Creek, 1994–2001..........................138

Figure 113. Abundance time series for Chinook salmon in portions of the Mad River basin.................140

Figure 114. Abundance time series for Chinook in portions of the Eel River basin.. .............................141

Figure 115. Estimated Sacramento River winter-run Chinook spawner abundance, 1970–2002............147

Figure 116. Abundance and growth rate of Central Valley salmonid populations..................................148

Figure 117. Number of juvenile Sacramento River winter-run Chinook salmon released by 

Coleman and Livingston Stone National Fish Hatcheries, 1963–2000 ....................................................151

Figure 118. Number of adult Sacramento River winter-run Chinook salmon collected for 

broodstock by Coleman and Livingston Stone National Fish Hatcheries, 1989–2000.............................152

xvii
Figure 119. Map of Central Valley, California, showing the locations of spring-run Chinook salmon 

populations with consistent runs, plus Big Chico Creek, which in recent years has had a small run.......154

Figure 120. Neighbor joining tree (Cavalli-Sforza and Edwards’ [1967] chord distances) for Central 

Valley Chinook salmon populations, based on 24 polymorphic allozyme loci........................................156

Figure 121. Neighbor joining tree (Cavalli-Sforza and Edwards’ [1967] chord distances) for Central 

Valley Chinook salmon populations, based on 12 microsatellite loci ......................................................157

Figure 122. Time series of population abundance for Central Valley spring-run Chinook salmon ........159

Figure 123. Abundance and growth rate of Central Valley salmonid populations..................................161

Figure 124. Number of spring-run Chinook salmon released by Feather River Hatchery, 

1967–1999. ...............................................................................................................................................162

Figure 125. Number of spring-run Chinook salmon returning to Feather River Hatchery, 

1963–1999. ...............................................................................................................................................162

Figure 126. Lower Granite Dam counts of Snake River A-run steelhead, 1985–2001 ...........................179

Figure 127. Lower Granite Dam counts of Snake River B-run steelhead, 1985–2001............................179

Figure 128. Spawner abundance counts (redds per mile) for Imnaha River steelhead, 1974–2000........180

Figure 129. Spawner escapement for Joseph Creek steelhead: Grande Ronde, 1974–2002....................180

Figure 130. Spawner escapement for the upper mainstem Grande Ronde River, 1967–2000.................181

Figure 131. Estimated spawner escapement for Tucannon River steelhead, 1987–2001 ........................182

Figure 132. Long-term median population growth-rate estimates and 95% confidence limits for 

the Snake River Basin steelhead ESU.......................................................................................................184

Figure 133. Short-term median population growth-rate estimates and 95% confidence limits for 

the Snake River Basin steelhead ESU.......................................................................................................185

Figure 134. Estimated annual spawner escapements of Wenatchee and Entiat river steelhead, 

1976–2001. ...............................................................................................................................................194

Figure 135. Estimated annual spawner escapements for Methow River steelhead, 1976–2001..............195

Figure 136. Returns per spawner versus broodyear spawning escapement of Wenatchee/Entiat river 

steelhead, 1976–2001................................................................................................................................198

Figure 137. Returns per spawner versus broodyear spawning escapement for Methow River 

steelhead, 1976–2001................................................................................................................................198

Figure 138. Yakima River steelhead spawning escapement estimates, 1980–2001 ................................210

Figure 139. Deschutes River steelhead escapement estimates over Sherars Falls, 1978–2002...............210

Figure 140. Touchet River steelhead escapement estimates, 1987–2001................................................211

Figure 141. Umatilla River steelhead counts at Three Mile Dam, 1966–2002........................................211

Figure 142. Upper John Day River steelhead estimates, based on annual redd counts, 1974–2002 .......212

Figure 143. South Fork John Day River steelhead redds per mile from index areas, 1974–2002...........212

Figure 144. Lower mainstem John Day River steelhead redds per mile from index areas, 

1965–2001 ................................................................................................................................................213

Figure 145. Middle Fork John Day River steelhead redds per mile from index areas, 1974–2001.........213

xviii
Figure 146. Upper North Fork John Day River steelhead redds per mile from index areas, 

1977–2002 ............................................................................................................................................... 214

Figure 147. Lower North Fork John Day River steelhead redds per mile from index areas, 

1976–2002 ................................................................................................................................................214

Figure 148. Historical populations of winter-run steelhead in the Lower Columbia River 

steelhead ESUU ...........................................................................................................................................217

Figure 149. Historical populations of summer-run steelhead in the Lower Columbia River 

steelhead ESUU ...........................................................................................................................................218

Figure 150. Winter-run steelhead abundance at North Fork Dam on the Clackamas River, 

1958–2001 ................................................................................................................................................224

Figure 151. Preharvest recruits and spawners for winter-run steelhead estimated from counts at 

North Fork Dam on the Clackamas River, 1958.......................................................................................225

Figure 152. Winter-run steelhead abundance at Marmot Dam on the Sandy River, 1978–2001 ............225

Figure 153. Preharvest recruits and spawners for winter-run steelhead estimated from counts at 

Marmot Dam on the Sandy River, 1978–2001 .........................................................................................226

Figure 154. Estimate of winter-run steelhead spawner abundance in the South Fork Toutle River, 

1987–2002. ...............................................................................................................................................226

Figure 155. Estimate of winter-run steelhead preharvest recruits and spawners in the South Fork 

Toutle River, 1994–2002 ..........................................................................................................................227

Figure 156. Estimate of winter-run steelhead abundance in the North Fork Toutle River, 

1989–2002 ................................................................................................................................................227

Figure 157. Estimate of winter-run steelhead preharvest recruits and spawners in the North Fork 

Toutle River, 1989–2002. .........................................................................................................................228

Figure 158. Estimate of winter-run steelhead abundance in the Kalama River, 1977–2002...................228

Figure 159. Estimate of winter-run steelhead preharvest recruits and spawners in the Kalama River, 

1977–2002. ...............................................................................................................................................229

Figure 160. Estimate of winter-run steelhead abundance in the Coweeman River, 1987–2002 .............229

Figure 161. Estimate of winter-run steelhead preharvest recruits and spawners in the 

Coweeman River, 1987–2002...................................................................................................................230

Figure 162. Index counts of natural-origin winter-run steelhead in the East Fork Lewis River..............230

Figure 163. Estimate of winter-run steelhead abundance in the Hood River, 1992–2000.......................231

Figure 164. Estimate of winter-run steelhead abundance in the Washougal River, 1991–2002 .............231

Figure 165. Estimate of summer-run steelhead abundance in the Hood River, 1992–2000....................232

Figure 166. Estimate of the total summer-run steelhead abundance in the Washougal River, 

1986–2003................................................................................................................................................232

Figure 167. Estimate of summer-run steelhead preharvest recruits and spawners in the 

Washougal River, 1986–2003...................................................................................................................233

Figure 168. Estimate of summer-run steelhead abundance in the Kalama River, 1977–2003. ...............233

Figure 169. Estimate of summer-run steelhead preharvest recruits and spawners in the 

Kalama River, 1977–2003. .......................................................................................................................234

xix
Figure 170. Estimate of summer-run steelhead abundance in the Wind River, 1989–2003....................234

Figure 171. Estimate of summer-run steelhead preharvest recruits and spawners in the Washougal River, 

1989–2003 ................................................................................................................................................235

Figure 172. Lower Columbia River ESU steelhead long-term trend versus 5-year geometric mean 

abundance of natural-origin spawners ......................................................................................................235

Figure 173. Lower Columbia River ESU steelhead long-term growth rate versus 5-year geometric 

mean abundance of natural-origin spawners.............................................................................................236

Figure 174. Lower Columbia River ESU steelhead long-term growth rate versus 5-year geometric 

mean abundance of natural-origin spawners.............................................................................................236

Figure 175. Map of historical Upper Willamette River steelhead ESU populations...............................238

Figure 176. Counts of winter-run steelhead at Willamette Falls, 1971–2002..........................................239

Figure 177. Redd surveys of winter-run steelhead in the Molalla River, 1980–2000 .............................240

Figure 178. Redd surveys of winter-run steelhead in the North Santiam River, 1980–2001 ..................241

Figure 179. Counts of winter-run steelhead at the Minto Trap on the North Santiam River, 

1960–2000 ................................................................................................................................................242

Figure 180. Counts of winter-run steelhead at Foster Dam on the South Santiam River (RKm 77), 

1967–2002 ................................................................................................................................................242

Figure 181. Redd surveys of winter-run steelhead in the South Santiam River below Foster Dam, 

1980–2001 ................................................................................................................................................243

Figure 182. Redd surveys of winter-run steelhead in the Calapooia River, 1980–2001..........................243

Figure 183. Estimates of the fraction of hatchery-origin spawners in populations of Upper 

Willamette River ESU winter-run steelhead, 1980–2000.........................................................................244

Figure 184. Estimates of the harvest rate on populations of Upper Willamette River ESU 

winter-run steelhead, 1973–2000..............................................................................................................244

Figure 185. Time-series data for the Northern California steelhead ESU ...............................................249

Figure 186. Trends versus abundance for the time-series data from Figure 185. ....................................251

Figure 187. Distribution of trends in juvenile density for 10 independent populations within 

the Northern California steelhead ESU.....................................................................................................255

Figure 188. Distribution of trends in juvenile densities for five independent populations within 

the Central California Coast steelhead ESUU .............................................................................................263

Figure 189. Adult steelhead counts at San Clemente Dam, Carmel River ..............................................271

Figure 190. Abundance and growth rate of Central Valley salmonid populations..................................289

Figure 191. Returns of steelhead passing the Red Bluff Diversion Dam fish ladders, 1966–1994.........289

Figure 192. Central Valley tributaries known or suspected to be used by steelhead adults ....................293

Figure 193. Releases of steelhead from Central Valley hatcheries..........................................................298

Figure 194. Returns of steelhead to Central Valley hatcheries................................................................299

Figure 195. Map of Oregon and Washington coasts showing the 11 major river systems and three 

coastal lakes that comprise the Oregon Coast coho salmon ESU.............................................................318

xx
Figure 196. Time series of spawners and preharvest recruits, by broodyear, for rivers in the 

Oregon Coast coho salmon ESU, 1970–2002...........................................................................................326

Figure 197. Time series of spawners and preharvest recruits, by broodyear, for lakes in the 

Oregon Coast coho salmon ESU, 1960–2002...........................................................................................326

Figure 198. Short-term (13-year, 1990–2002) trends in spawners and recruits versus the recent 3-year 

geometric mean abundance plotted for 11 major river populations in the Oregon Coast coho 

salmon ESU ..............................................................................................................................................327

Figure 199. Short-term (13-year, 1990–2002) trends in spawner abundance for 11 major river basins 

in the Oregon Coast coho salmon ESU.....................................................................................................327

Figure 200. Short-term (13-years, 1990–2002) trends in recruit abundance for 11 major river basins 

in the Oregon Coast coho salmon ESU.....................................................................................................329

Figure 201. Long-term trends (33 years, 1970–2002) for spawners and recruits in coastal lakes (lakes), 

river basins (rivers), and total in the Oregon Coast coho salmon ESU.....................................................329

Figure 202. Conceptual model of effects of declining habitat quality and cyclic changes in ocean 

productivity on the abundance of Oregon’s coastal natural coho salmon.................................................333

Figure 203. Rearing origin of naturally spawning adult coho salmon in major Oregon coastal river 

basins over the 6-year period 1992–1998 .................................................................................................336

Figure 204. Proportion of streams surveyed for which coho salmon presence was detected, by 

broodyear, for all historical coho streams and coho streams identified in Brown and Moyle’s (1991) 

historical list within the Southern Oregon/Northern California Coast coho salmon ESU....................... 349.

Figure 205. Trends in Rogue river coho salmon populations..................................................................353

Figure 206. Percent survival of coded-wire-tag-marked coho salmon from Cole Rivers Hatchery. .......354

Figure 207. Proportion of streams surveyed for which coho salmon presence was detected, by 

broodyear, for all historical coho streams and coho streams identified in Brown and Moyle’s (1991) 

historical list within the Central California Coast coho salmon ESU.......................................................370

Figure 208. Counts of adult coho salmon at Noyo Egg Collecting Station, 1962–2001 .........................372

Figure 209. Coho salmon smolt counts (1987–2002) at (a) Little River and (b) Caspar Creek, 

Mendocino County....................................................................................................................................373

Figure 210. Tentative historical populations of the lower Columbia River coho salmon ESU...............382

Figure 211. Clackamas North Fork Dam counts of adult (3-year-old) coho salmon, 1957–2002...........385

Figure 212. Clackamas North Fork Dam counts of adult (3-year-old) coho salmon by cohort, 

1957–2002 ................................................................................................................................................391

Figure 213. Clackamas River early and late-run coho salmon, 1973–1998.. ..........................................392

Figure 214. Total outmigrating juvenile coho salmon passing Clackamas North Fork Dam, 

1959–2003 ................................................................................................................................................392

Figure 215. Estimate of preharvest coho salmon recruits and spawners in the Clackamas River, 

1957–1998 ................................................................................................................................................393

Figure 216. Estimate of preharvest coho salmon recruits per spawner in the Clackamas River, 

1957–1998. ...............................................................................................................................................393

Figure 217. Clackamas River natural-origin coho salmon harvest rate, 1957–1999 ...............................394

xxi
Figure 218. Count of adult (≥3 year old) coho salmon at the Marmot Dam on the Sandy River, 

1977–2002. ...............................................................................................................................................394

Figure 219. Count of adult (≥3 year old) coho salmon at Marmot Dam on the Sandy River by 

cohort ........................................................................................................................................................395

Figure 220. Estimate of preharvest coho salmon recruits and spawners in the Sandy River, 

1977–2002 ................................................................................................................................................396

Figure 221. Estimate of preharvest coho salmon recruits per spawners in the Sandy River, 

1977–2002 ................................................................................................................................................396

Figure 222. Sandy River natural-origin coho salmon harvest rate, 1977–2002.......................................397

Figure 223. Youngs Bay coho salmon spawners per mile, 1949–2001 ...................................................397

Figure 224. Big Creek coho salmon spawners per mile, 1949–2001.......................................................398

Figure 225. Clatskanie River coho salmon spawners per mile, 1949–2001 ............................................398

Figure 226. Scappoose River spawners per mile, 1949–2001 .................................................................399

Figure 227. Estimated numbers of adult sockeye salmon entering Lake Ozette, 1978–2001. ................417

Figure 228. Salmon/Snow rivers summer-run chum salmon annual spawner abundance versus year 

by population, 1974–2002. .......................................................................................................................431

Figure 229. Dosewallips River summer-run chum salmon annual spawner abundance versus year by 

population, 1972–2002. ............................................................................................................................431

Figure 230. Combined Quilcene River summer-run chum salmon annual spawner abundance versus 

year by population, 1974–2002.................................................................................................................432

Figure 231. Jimmycomelately Creek summer-run chum salmon annual spawner abundance versus 

year by population, 1974–2002.................................................................................................................432

Figure 232. Hamma Hamma River summer-run chum salmon annual spawner abundance versus year 

by population, 1968–2002 ........................................................................................................................433

Figure 233. Lilliwaup River summer-run chum salmon annual spawner abundance versus year by 

population, 1971–2002 .............................................................................................................................433

Figure 234. Union River summer-run chum salmon annual spawner abundance versus year by 

population, 1974–2002 .............................................................................................................................434

Figure 235. Salmon/Snow rivers summer-run chum salmon recruit and spawner abundance versus 

year by population, 1974–2002.................................................................................................................434

Figure 236. Dosewallips River summer-run chum salmon recruit and spawner abundance versus year 

by population, 1972–2002 ........................................................................................................................435

Figure 237. Combined Quilcene River summer-run chum salmon recruit and spawner abundance 

versus year by population, 1974–2002 .....................................................................................................435

Figure 238. Jimmycomelately Creek summer-run chum salmon recruit and spawner abundance 

versus year by population, 1974–2002 .....................................................................................................436

Figure 239. Hamma Hamma River summer-run chum salmon recruit and spawner abundance versus 

year by population, 1968–2002.................................................................................................................436

Figure 240. Lilliwaup River summer-run chum salmon recruit and spawner abundance versus year 

by population, 1971–2002 ........................................................................................................................437

xxii
Figure 241. Union River summer-run chum salmon recruit and spawner abundance versus year by 

population, 1974–2002 .............................................................................................................................437

Figure 242. Historical chum salmon populations in the Columbia River chum salmon ESU.................444

Figure 243. Columbia River chum salmon returns, 1904–1994 ..............................................................446

Figure 244. Extant Columbia River chum salmon populations...............................................................446

Figure 245. Grays River chum salmon abundance estimates, 1945–2000...............................................449

Figure 246. Grays River chum salmon recruits and spawners, 1966–1998.............................................449

Figure 247. Hamilton and Hardy creeks (lower Columbia Gorge population) chum salmon spawner 

abundance, 1944–2000 .............................................................................................................................450

Figure 248. Hamilton and Hardy creeks (lower Columbia Gorge population) chum salmon recruits 

and spawners, 1950–2000.........................................................................................................................450

Figure 249. Abundance of chum salmon observed in 2000 Pacific States Marine Fisheries 

Commission surveys.................................................................................................................................451

Figure 250. Adult chum salmon passing Bonneville Dam, 1992–2002...................................................452

xxiii
xxiv
 

List of Tables 

Table 1. Template for the risk matrix used in BRT deliberations..............................................................16

Table 2. Escapement and stock composition of fall-run Chinook salmon at Lower Granite Dam, 

1975–2001.. ................................................................................................................................................31

Table 3. Fall-run Chinook salmon hatchery releases into the Snake River basin, 1985–2001..................32

Table 4. Summary of abundance and trend information for Snake River spring/summer-run Chinook 

salmon ESU relative to previous BRT status review analyses. ..................................................................42

Table 5. Total hatchery releases of spring/summer-run Chinook salmon into the Snake River basin, 

by stock and release site..............................................................................................................................45

Table 6. Summary of abundance and trend information for the Upper Columbia River spring-run 

Chinook salmon ESU relative to previous BRT status review. ..................................................................55

Table 7. Upper Columbia River spring-run Chinook salmon ESU hatchery returns, 1994–2001.............56

Table 8. Historical populations of Chinook salmon in the Puget Sound ESU, run-timing types for each 

population, and each population’s biogeographic region ...........................................................................68

Table 9. Abundance of natural spawners, estimates of the fraction of hatchery fish in natural 

escapements, and estimates of historical capacity of Puget Sound streams................................................69

Table 10. Estimates of long- and short-term trends, and the short-term median population growth 

rate (λ), and their 95% confidence intervals (CI) for spawners in Puget Sound Chinook salmon 

populations..................................................................................................................................................82

Table 11. Estimated broodyear adult-equivalent exploitation rates on populations of Puget Sound 

Chinook salmon. .........................................................................................................................................95

Table 12. Total estimated recent annual average returns of hatchery-produced Chinook salmon 

(adults returning to hatchery racks and to spawning grounds) and total releases of juvenile Chinook 

salmon in streams containing independent populations of Chinook salmon in Puget Sound.....................96

Table 13. Historical population structure and abundance statistics for Lower Columbia ESU 

Chinook salmon populations, by life history and ecological zone............................................................102

Table 14. Long-term trend and growth rate for a subset of Lower Columbia River ESU Chinook 

salmon populations for which adequate data are available.......................................................................120

Table 15. Short-term trend and growth rate for a subset of Lower Columbia River ESU Chinook 

salmon populations for which adequate data are available.......................................................................121

Table 16. Probability that the long-term abundance trend or growth rate is less than 1 for a subset of 

Lower Columbia River ESU Chinook salmon populations......................................................................122

Table 17. Estimate of historical abundance based on the WDFW’s EDT analysis of equilibrium 

abundance under historical habitat conditions..........................................................................................123

Table 18. Loss of habitat due to barriers in the Lower Columbia River Chinook salmon ESU..............124

Table 19. Historical populations of Upper Willamette River spring-run Chinook salmon ESU.............132

xxv 
Table 20. Upper Willamette River spring-run Chinook salmon ESU hatchery releases.........................133

Table 21. Historical estimates of abundance of Chinook salmon in the California Coastal Chinook 

salmon ESU. .............................................................................................................................................136

Table 22. Plausible hypotheses for independent populations considered by the North-Central 

California Coast TRT................................................................................................................................137

Table 23. Geometric means, estimated λ, and long- and short-term trends for abundance time series 

in the California Coastal Chinook salmon ESU........................................................................................138

Table 24. Summary statistics for trend analyses......................................................................................147

Table 25. Parameter estimates for the constant-growth and step-change models applied to 

Sacramento River winter-run Chinook salmon.........................................................................................149

Table 26. Summary statistics for trend analyses for Central Valley spring-run Chinook salmon 

ESU populations. ......................................................................................................................................160

Table 27. Tally of the FEMAT vote distribution regarding the status of nine Chinook salmon ESUs 

reviewed by the Chinook salmon BRT.....................................................................................................163

Table 28. Summary of risk scores for four VSP categories for the nine Chinook salmon ESUs 

reviewed....................................................................................................................................................164

Table 29. Summary of abundance and trend estimates for the Snake River Basin steelhead ESU .........178

Table 30. Snake River Basin steelhead ESU population growth-rate analysis........................................183

Table 31. Distribution of Snake River Basin steelhead ESU trout populations by category...................186

Table 32. Hatchery releases of steelhead in the Snake River Basin steelhead ESU, organized by 

major steelhead production areas and broodstock of the release ..............................................................188

Table 33. Summary of current abundance and trend information relative to previous BRT status review 

for Upper Columbia River steelhead ........................................................................................................195

Table 34. Upper Columbia River steelhead population growth-rate analysis..........................................197

Table 35. Distribution of O. mykiss by category relative to the Upper Columbia River 

steelhead ESUU ...........................................................................................................................................199

Table 36. Hatchery releases of steelhead in the Upper Columbia River ESU, organized by major 

steelhead production areas and broodstock...............................................................................................200

Table 37. Summary of recent 5-year average (geometric mean) population abundance and trend 

estimates in comparison to estimates included in the previous BRT status review..................................204

Table 38. Middle Columbia River steelhead ESU population growth-rate analysis ...............................205

Table 39. Distribution of steelhead populations by category relative to the Middle Columbia River 

steelhead ESUU ...........................................................................................................................................208

Table 40. Steelhead hatchery releases in the middle Columbia River region by major steelhead 

production areas and broodstock...............................................................................................................209

Table 41. Historical population structure and abundance statistics for Lower Columbia River 

steelhead ESU populations, by ecological zone and major life history type ............................................216

Table 42. Long-term trend and growth rate for a subset of Lower Columbia River steelhead ESU 

populations for which adequate data are available ...................................................................................220

xxvi
Table 43. Short-term trend and growth rate for a subset of Lower Columbia River steelhead ESU 

populations for which adequate data are available ...................................................................................221

Table 44. Probability that the long-term abundance trend or growth rate of a subset of Lower 

Columbia River steelhead ESU populations is less than 1. ......................................................................221

Table 45. Probability that the long-term abundance trend or growth rate of a subset of Lower 

Columbia River steelhead ESU populations is less than 1. ......................................................................222

Table 46. Estimates of historical abundance for a subset of Lower Columbia River steelhead ESU 

populations, based on the EDT model. .....................................................................................................222

Table 47. Loss of habitat from barriers in the Lower Columbia River steelhead ESU ...........................223

Table 48. Releases of winter-run steelhead for the final years that winter-run steelhead were 

stocked in the Willamette River................................................................................................................239

Table 49. Trends in redds-per-mile surveys of Upper Willamette River ESU winter-run steelhead 

populations................................................................................................................................................240

Table 50. Historical populations of Upper Willamette River ESU steelhead and loss of habitat from 

barriers. .....................................................................................................................................................245

Table 51. Summary of historical abundance (average counts) for steelhead in the Northern 

California steelhead ESU (see also Figure 185) .......................................................................................248

Table 52. Historical estimates of number of spawning steelhead for rivers in the Northern 

California steelhead ESU..........................................................................................................................250

Table 53. Summary of time-series data for the Northern California steelhead ESUU ...............................253

Table 54. Interpretation of data on juvenile trends for Northern California steelhead ESU....................254

Table 55. Summary of estimated run sizes for the Central California Coast steelhead ESU ..................260

Table 56. Estimates of historical steelhead run sizes from the previous status review............................270

Table 57. Summary of time-series data for the South-Central California Coast steelhead ESU.............272

Table 58. Estimates from Busby et al. (1996) for run sizes in the major river systems of the 

Southern California steelhead ESU...........................................................................................................280

Table 59. Presence of steelhead in the lower Santa Ynez River system..................................................284

Table 60. Summary statistics for California Central Valley steelhead ESU trend analyses....................288

Table 61. Estimated natural production of steelhead juveniles from the Central Valley.........................291

Table 62. Summary of distribution information for steelhead in the California Central Valley 

steelhead ESUU ...........................................................................................................................................294

Table 63. Tally of FEMAT vote distribution regarding the status of 10 steelhead ESUs reviewed........300

Table 64. Summary of risk scores for four VSP categories for the 10 steelhead ESUs reviewed..........301

Table 65. Numbers of natural-origin spawners in the Oregon Coast coho salmon ESU, 1990–2002, 

subtotaled by ODFW monitoring area, rivers, lakes, and coastwide ........................................................322

Table 66. Three-year statistics and 13-year trends for 11 major river basins in the Oregon Coast coho 

salmon ESU. .............................................................................................................................................325

Table 67. Three-year statistics and 33-year trends for Oregon Coast coho salmon ESU rivers, lakes, 

and combined rivers and lakes..................................................................................................................325

xxvii
Table 68. Oregon Productivity Index (OPI) area hatchery marine survival, Oregon coastal hatchery 

adult returns per smolt, and OPI area exploitation rate on unmarked coho salmon, 1990–2002..............331

Table 69. Millions of smolts released, adult returns, and number of operating hatcheries on the 

Oregon coast, 1990–2002 .........................................................................................................................335

Table 70. Percent of natural spawning coho salmon of hatchery origin in Oregon coastal river basins, 

based on fin clips from carcasses (1998, 1999) or both carcasses and live fish (2000–2002)..................337

Table 71. Proportion of natural spawning fish of hatchery origin, 1990–2002 .......................................338

Table 72. Historical estimates of coho salmon spawner abundance for various rivers and regions 

within the Southern Oregon/Northern California Coast (SONCC) coho salmon ESU. ..............................340

Table 73. Historical presence of coho salmon in the Southern Oregon/Northern California Coast 

(SONCC) coho salmon ESU, as determined by Brown and Moyle (1991) and the California 

Department of Fish and Game’s presence-by-broodyear investigation (as of February 2002). ...............346

Table 74. Percent of surveyed streams within the Southern Oregon/Northern California 

Coast (SONCC) ESU for which coho salmon were detected for four time intervals: broodyears 

1987–1989, 1990–1992, 1993–1995, 1996–1998, and 1999–2001 ..........................................................348

Table 75. Abundance and trend estimates for Rogue River basin coho salmon natural spawners, 

estimated from Huntley Park seine data, 1980–2001................................................................................354

Table 76. Average annual releases of coho salmon juveniles (fry and smolts) from selected hatcheries 

in the Southern Oregon/Northern California Coast (SONCC) coho salmon ESU during release years 

1987–1991, 1992–1996, and 1997–2002..................................................................................................358

Table 77. Historical estimates of coho salmon spawner abundance for various rivers and regions 

within the Central California Coast coho salmon ESU.............................................................................365

Table 78. Historical presence of coho salmon in the Central California Coast ESU, as determined by 

Brown et al. (1994) and the California Department of Fish and Game’s analysis of recent presence 

(1995–2001)..............................................................................................................................................366

Table 79. Percent of surveyed streams within the Central California Coast coho salmon ESU for 

which coho salmon were detected for four time intervals: broodyears 1987–1989, 1990–1992, 

1993–1995, 1996–1998, and 1999–2001..................................................................................................371

Table 80. Population trend analysis for Caspar Creek and Little River smolt outmigrant data...............374

Table 81. Trend slopes and confidence intervals for nine putative coho populations in the Central 

California Coast coho salmon ESU. .........................................................................................................375

Table 82. Average annual releases of coho salmon juveniles (fry and smolts) from hatcheries in the 

Central California Coast coho salmon ESU during release years 1987–1991, 1992–1996, 

and 1997–2003..........................................................................................................................................378

Table 83. Recent abundance of natural-origin spawners and recent fraction of hatchery-origin 

spawners for Lower Columbia River ESU coho salmon populations.......................................................384

Table 84. Recent abundance estimates for subset of Lower Columbia River ESU coho populations.....385

Table 85. Long-term trend and growth rate for subset of Lower Columbia River ESU coho salmon 

populations................................................................................................................................................386

Table 86. Short-term trend and growth rate for subset of Lower Columbia River ESU coho 

populations................................................................................................................................................387

xxviii
Table 87. Probability that the long-term abundance trend or growth rate of Lower Columbia River 

ESU coho salmon is less than 1. ...............................................................................................................387

Table 88. Probability that the short-term abundance trend or growth rate of Lower Columbia River 

ESU coho salmon is less than 1 ................................................................................................................387

Table 89. Estimates of natural coho salmon juvenile outmigrants from Washington Lower 

Columbia River streams............................................................................................................................388

Table 90. Total coho salmon hatchery releases into the Columbia River basin ......................................389

Table 91. Loss of habitat from barriers in the Lower Columbia River coho salmon ESU......................390

Table 92. Tally of FEMAT vote distribution regarding the status of four coho salmon ESUs 

reviewed by the coho salmon BRT...........................................................................................................401

Table 93. Summary of risk scores or four VSP categories for the four coho salmon ESUs reviewed. ...401

Table 94. Adult anadromous sockeye salmon returns to the Redfish Lake Creek weir, 1954–1968, 

and the Redfish Lake Creek trap and Sawtooth Fish Hatchery weir, 1991–2002 ....................................412

Table 95. Releases of progeny from the Redfish Lake sockeye salmon captive broodstock program 

into Redfish, Alturas, and Pettit lakes, 1993–2002...................................................................................413

Table 96. Estimated run size of natural-origin recruits to Lake Ozette and Umbrella Creek, and 

the fraction of hatchery-origin fish returning to Umbrella Creek for Lake Ozette sockeye salmon, 

1978–2001 ................................................................................................................................................418

Table 97. Percentages of 5-year-old fish sampled from otoliths in carcasses in sockeye salmon 

subpopulations in Lake Ozette, 2000–2001..............................................................................................419

Table 98. Tally of FEMAT vote distribution regarding the status of two sockeye salmon ESUs 

reviewed....................................................................................................................................................421

Table 99. Summary of risk scores for four viable salmonid population categories for the Snake River and 

Ozette Lake sockeye salmon ESUs...........................................................................................................421

Table 100. Historical populations of summer-run chum salmon in the Hood Canal chum 

salmon ESU ..............................................................................................................................................429

Table 101. Abundance and estimated fraction of hatchery fish in natural escapements of 

Hood Canal summer-run chum salmon spawning populations.................................................................430

Table 102. Estimates of long- and short-term trends, short-term median population growth rate (λ), 

and their 95% confidence intervals (CI) for natural spawners in extant Hood Canal summer-run 

chum salmon populations. ........................................................................................................................438

Table 103. Average annual exploitation rates on populations of Hood Canal summer-run chum 

salmon during three time periods, 1974–2002..........................................................................................439

Table 104. Average estimated annual returns of hatchery summer-run chum salmon to the 

spawning grounds of extant populations of summer-run chum salmon in Hood Canal. ..........................440

Table 105. Numbers of hatchery-origin juvenile summer-run chum salmon released into 

Hood Canal streams, 1993–2001.. ............................................................................................................441

Table 106. Impact ratings of regionwide historical factors for decline of summer-run chum salmon 

in Hood Canal and Strait of Juan de Fuca streams....................................................................................442

Table 107. Historical population structure of Columbia River chum salmon. ........................................445

xxix
Table 108. Recent abundance estimates for Lower Columbia Gorge and two Grays River chum 

salmon populations. ..................................................................................................................................445

Table 109. Trend and growth rate for a Lower Columbia Gorge and two Grays River chum salmon 

populations................................................................................................................................................447

Table 110. Probability that the abundance trend or growth rate of Columbia River chum salmon is 

less than 1..................................................................................................................................................448

Table 111. Loss of habitat from barriers for the Columbia River chum salmon ESU.............................454

Table 112. FEMAT votes regarding status of the Hood Canal summer-run and Columbia River 

chum salmon ESUs...................................................................................................................................456

Table 113. Summary of risk scores for four viable salmonid population categories for the 

Hood Canal summer-run and Columbia River chum salmon ESUs. ........................................................456

Table A-1. SSHAG categorizations of hatchery stocks of the nine Chinook salmon ESUs reviewed ....513

Table A-2. Chinook salmon time-series data sources..............................................................................516

Table A-3. Lower Columbia River hatchery releases..............................................................................549

Table B-1. Distribution of O. mykiss trout by category in the Columbia Basin steelhead ESUs .............555

Table B-2. Distribution, abundance, and stocking of O. mykiss above major recent barriers (case 3 

situations) within five steelhead ESUs in California, listed by ESU and watershed ................................558

Table B-3. SSHAG categorizations of hatchery populations of nine steelhead ESUs reviewed.............565

Table B-4. Steelhead time-series references. ...........................................................................................566

Table C-1. Preliminary SSHAG categorizations of hatchery populations of the four coho salmon 

ESUs reviewed..........................................................................................................................................579

Table C-2. Coho salmon time series data sources....................................................................................580

Table D-1. Preliminary SSHAG categorizations of hatchery populations of the Ozette Lake 

sockeye ESU.............................................................................................................................................585

Table E-1. Preliminary SSHAG categorizations of hatchery populations of chum salmon of the 

Hood Canal summer-run and Columbia River chum salmon ESUs.........................................................587

Table E-2. Chum salmon time-series data sources .................................................................................. 588

xxx
Executive Summary 

During the 1990s, the National Marine Fisheries Service (NMFS or NOAA Fisheries 

Service) conducted a series of reviews of the status of West Coast populations of Pacific salmon 

and steelhead (Oncorhynchus spp.) with respect to the U.S. Endangered Species Act (ESA). 

This technical memorandum summarizes scientific conclusions of the NMFS Biological Review 

Teams (BRTs) regarding the updated status of 26 ESA-listed ESUs (evolutionarily significant 

units) of salmon and steelhead (and one candidate species ESU) from Washington, Oregon, 

Idaho, and California. These ESUs were listed following a series of status reviews conducted 

during the 1990s. The status review updates were undertaken to allow consideration of new data 

that accumulated over the various time periods since the last updates and to address issues raised 

in recent court cases [Alsea Valley Alliance v. Evans, 161 F. Supp. 2d 1154, D. Oreg. 2001, and

EDC v. Evans, SACV-00-1212-AHS (EEA); MID v. Evans, CIV-F-02-6553 OWW DLB (E.D. 

Cal)] regarding the ESA status of hatchery fish and resident (nonanadromous) populations. 

This technical memorandum represents the first major step in the agency’s efforts to 

review and update the listing determinations for all listed ESUs of salmon and steelhead. By 

statute, ESA listing determinations must consider not only the best scientific information 

available but also those efforts being made to protect the species. After receiving the BRT report 

and considering the conservation benefits of protective efforts, NMFS will determine what 

changes, if any, to propose to the listing status of the affected ESUs. 

As in the past, the BRTs used a risk-matrix method to quantify risks in different 

categories within each ESU. In the current report, the method was modified to reflect the four 

major criteria identified in the NMFS viable salmonid populations (VSPs) document (McElhany 

et al. 2000): abundance, growth rate/productivity, spatial structure, and diversity. These criteria 

are used as a framework for approaching formal ESA recovery planning for salmon and 

steelhead. Tabulating mean risk scores for each element allowed the BRTs to identify the most 

important concerns for each ESU and to compare relative risk across ESUs and species. The 

BRTs considered these data and other information in making their overall risk assessments. 

Based on provisions in a draft of the revised NMFS policy on consideration of artificial 

propagation in salmon listing determinations, each BRT’s risk analysis focused on the viability 

of populations sustained by natural production. 

Based on the criterion of self-sustainability, for the following ESUs the majority BRT 

conclusion was “in danger of extinction:” Upper Columbia River spring-run Chinook 

(Oncorhynchus tshawytscha), Sacramento River winter-run Chinook, Upper Columbia River 

steelhead (O. mykiss), Southern California steelhead, California Central Valley steelhead, Central 

California Coast coho (O. kisutch), Lower Columbia River coho, Snake River sockeye (O. 

nerka). For the following ESUs, the majority BRT conclusion was “likely to become 

endangered in the foreseeable future:” Snake River fall-run Chinook, Snake River 

spring/summer-run Chinook, Puget Sound Chinook, Lower Columbia River Chinook, Upper 

Willamette River Chinook, California Coastal Chinook, Central Valley spring-run Chinook, 

xxxi
Snake River steelhead, Lower Columbia River steelhead, Upper Willamette River steelhead, 

Northern California steelhead, Central California Coast steelhead, South-Central California 

Coast steelhead, Oregon Coast coho, Southern Oregon/Northern California Coasts coho, Ozette 

Lake sockeye, Hood Canal summer-run chum, and Lower Columbia River chum. In one case 

(Middle Columbia River steelhead), the BRT was nearly evenly split on the question of whether 

the ESU was likely to become endangered in the foreseeable future (a slight majority concluded 

that the ESU was likely to become endangered) (Table ES-1). 

Table ES-1. BRT conclusions regarding updated status of salmon and steelhead ESUs. X = the majority 

vote. (X) = a substantial minority (>40% of the vote). 

Species ESU 

Danger of

extinction 

Likely to 

become 

endangered 

Not likely to 

become 

endangered 

Snake River fall run – X – 

Snake River spring/summer run – X – 

Upper Columbia River spring run X (X) – 

Puget Sound – X – 

Lower Columbia – X – 

Upper Willamette – X – 

California Coastal – X – 

Sacramento River winter run X – – 

Chinook 

Central Valley spring run – X – 

Snake River Basin – X – 

Upper Columbia River X (X) – 

Middle Columbia River – X (X) 

Lower Columbia River – X – 

Upper Willamette River – X – 

Northern California – X – 

Central California Coast – X – 

South-Central California Coast – X – 

Southern California X – – 

Steelhead 

California Central Valley X – – 

Oregon Coast – X (X) 

Southern Oregon/Northern California 

Coasts – X – 

Central California X – – 

Coho 

Lower Columbia X – – 

Sockeye Snake River X – – 

Ozette Lake – X – 

Chum Hood Canal summer run – X – 

Columbia River – X – 

xxxii
 

Acknowledgments 

We are grateful to the large number of regional biologists who provided raw data and 

information used in this report. This report was improved as a result of comments provided by 

state, tribal, and federal comanagers on an earlier draft. The effort to update the status of all 

listed ESUs of West Coast salmon and steelhead would not have been possible without the help 

of many, including Andrew Albaugh, Charlene Bergeron, Ronda Carbary, Henry Carson, Kurt 

Davis, Christopher Donohoe, Tamara Harms, Christine Holt, Andrea Jarvela, Laura Johnston, 

Jenny Moslemi, Jessica Piasecke, Cory Ruedebusch, Brycen Swart, J. J. Westfall, and Thomas 

Williams. 

xxxiii 
xxxiv
 

Abbreviations and Acronyms 

BRT Biological Review Team 

CBD Center for Biological Diversity 

DPS distinct population segment 

ESA U.S. Endangered Species Act 

ESU evolutionarily significant unit 

FCRPS Federal Columbia River Power System 

FEMAT Forest Ecosystem Management Assessment Team 

NMFS National Marine Fisheries Service (also referred to as NOAA Fisheries) 

NOAA National Oceanic and Atmospheric Administration 

PDO Pacific Decadal Oscillation 

PVA population viability analysis 

SASSI Salmon and Steelhead Stock Inventory 

SSHAG Salmon and Steelhead Hatchery Assessment Group 

TRT Technical Recovery Team 

USFWS U.S. Fish and Wildlife Service 

VSP viable salmonid population 

xxxv 
xxxvi
INTRODUCTION AND METHODS

1 
2 
1. Introduction 

During the 1990s, the National Marine Fisheries Service (NMFS or NOAA Fisheries 

Service) conducted a series of reviews of the status of West Coast populations of Pacific salmon 

and steelhead (Oncorhynchus spp.) with respect to the U.S. Endangered Species Act (ESA). 

Initially, these reviews were in response to petitions for populations of a particular species within 

a particular geographic area, but in 1994 the agency began a series of proactive, comprehensive 

ESA status reviews of all populations of anadromous Pacific salmonids from Washington, Idaho, 

Oregon, and California (NMFS 1994a). 

The first step in these reviews is to determine the units that can be considered “species” 

under the ESA and hence listed as threatened or endangered, if warranted, based on their status. 

The ESA allows listing not only of full species but also named subspecies and distinct population 

segments (DPSs) of vertebrates (including fish). The ESA petitions and status reviews for 

Pacific salmonids have focused primarily on the DPS level. To guide DPS evaluations of Pacific 

salmonids, NMFS has used the policy developed in 1991 (NMFS 1991a, Waples 1991, 1995), 

which is described in the next section. As a result of these status reviews, NMFS has identified 

over 50 evolutionarily significant units (ESUs) of salmon and steelhead from California and the 

Pacific Northwest, of which 26 are listed as threatened or endangered species under the ESA.1

In 2000 NMFS initiated formal ESA recovery planning for listed salmon and steelhead 

ESUs. Recovery efforts are organized into a series of geographic areas or domains. Within each 

domain, a Technical Recovery Team (TRT) has been (or is in the process of being) formed to 

develop a sound scientific basis for recovery planning. Regional planners will use the 

information the TRTs provide to craft comprehensive recovery plans for all listed ESUs within 

each domain. For more information about the ESA recovery planning process for salmon and 

steelhead and the TRTs, see the NMFS Northwest Salmon Recovery Planning Web site 

(http://www.nwfsc.noaa.gov/trt/). 

Recently, several factors led NMFS to conclude that the ESA status of listed salmon and 

steelhead ESUs should be reviewed at this time. First, a September 2001 court ruling called into 

question the NMFS decision to not list several hatchery populations considered to be part of the 

Oregon Coast coho salmon ESU (Alsea Valley Alliance v. Evans, 161 F. Supp. 2d 1154, D. Oreg. 

2001, hereafter called the Alsea decision). The ruling held that the ESA does not allow listing of 

any unit smaller than a DPS (or ESU), and that NMFS had violated that provision of the act by 

listing only part of an ESU. Although this legal case applied directly only to the Oregon Coast 

coho salmon ESU, the same factual situation (hatchery populations considered part of listed 

ESUs, but not listed) also applied to most other listed ESUs of salmon and steelhead. Second, 

 

1

 A complete list of these evaluations can be found online (http://www.nwr.noaa.gov/1salmon/salmesa/fractlist.htm), 

and the technical documents representing results of the status reviews can be accessed online at Web sites of the 

Northwest Fisheries Science Center (http://www.nwfsc.noaa.gov/publications/index.cfm), the Southwest Regional 

Office (http://swr.nmfs.noaa.gov/salmon.htm), the Santa Cruz Laboratory (http://www.pfeg.noaa.gov/), and the 

Northwest Regional Office (http://www.nwr.noaa.gov/). 

3 
INTRODUCTION AND METHODS

two additional lawsuits currently pending that involve California ESUs of steelhead [EDC v. 

Evans, SACV-00-1212-AHS (EEA); MID v. Evans, CIV-F-02-6553 OWW DLB (E.D. Cal).] 

raised a similar issue—NMFS concluded that resident fish were part of the ESU, but only the 

anadromous steelhead were listed. Again, this same factual situation is found in most, if not all, 

listed steelhead ESUs. Finally, at least several years of new data are available for most ESUs, 

and up to a decade has passed since the first populations were listed in the Sacramento and Snake 

rivers. Furthermore, in some areas, adult returns in the last few years have been considerably 

higher than have been seen for several decades. 

As a result of these factors, NMFS committed to a systematic updating of the ESA status 

of all listed ESUs of Pacific salmon and steelhead—Chinook salmon (Oncorhynchus 

tshawytscha), steelhead (O. mykiss), coho salmon (O. kisutch), sockeye salmon (O. nerka), and 

chum salmon (O. keta) (NMFS 2002a). This report summarizes updated biological information 

for the 26 listed salmon and steelhead ESUs and one candidate ESU (lower Columbia coho 

salmon), and presents the team’s conclusions regarding these ESUs’ current risk status. The 

Biological Review Teams (BRTs) consisted of a core groups of scientists from the NMFS 

Northwest and Southwest Fisheries Science Centers, supplemented by experts on particular 

species from NMFS and other federal agencies. BRT membership is indicated in the sections for 

each species. The BRTs met in January, March, and April 2003 to review information related to 

the updated status reviews. 

ESU Determinations 

As amended in 1978, the ESA allows listing of distinct population segments of 

vertebrates as well as named species and subspecies. However, the ESA provided no specific 

guidance for determining what constitutes a distinct population segment, and the resulting 

ambiguity led to the use of a variety of criteria in listing decisions over the past decade. To 

clarify the issue for Pacific salmonids, NMFS published a policy describing how the agency will 

apply the definition of “species” in the ESA to anadromous salmonid species, including sea-run 

cutthroat trout and steelhead (NMFS 1991a). A more detailed description of this topic appeared 

in the NMFS “Definition of Species” paper (Waples 1991). The NMFS policy stipulates that a 

salmon population or group of populations is considered “distinct” for purposes of the ESA if it 

represents an ESU of the biological species. An ESU is defined as a population that 1) is 

substantially reproductively isolated from conspecific populations, and 2) represents an 

important component in the evolutionary legacy of the species. Information that can be useful in 

determining the degree of reproductive isolation includes incidence of straying, rates of 

recolonization, degree of genetic differentiation, and the existence of barriers to migration. 

Insight into evolutionary significance can be provided by data on genetic and life history 

characteristics, habitat differences, and the effects of stock transfers or supplementation efforts. 

The BRTs have used a comprehensive approach that used all available scientific information to 

define ESUs. A discussion of how the NMFS policy was applied in a number of ESA status 

reviews can be found in Waples (1995). 

4
1. INTRODUCTION

Geographic Boundaries 

The status review updates focused primarily on risk assessments, and (apart from the 

discussion of resident fish in steelhead ESUs) the BRTs did not consider issues associated with 

the geographic boundaries of ESUs. If significant new information arises to indicate that 

specific ESU boundaries should be reconsidered, it will be done at a later time. 

Artificial Propagation 

Most salmon and steelhead ESUs have hatchery populations associated with them, and it 

is important for administrative, management, and conservation reasons to determine the 

biological relationship between these hatchery fish and natural populations within the ESU. The 

NMFS ESA policy for artificial propagation of Pacific salmon and steelhead (NMFS 1993a) has 

guided ESA status reviews conducted since 1993. That policy recognizes that “genetic resources 

important to the species’ evolutionary legacy may reside in hatchery fish as well as in natural 

fish, in which case, the hatchery fish can be considered part of the biological ESU in question.” 

As part of the coastwide status reviews (Weitkamp et al. 1995, Busby et al. 1996, Gustafson 

et al. 1997, Johnson et al. 1997, Myers et al. 1998), the BRTs applied this principle in evaluating 

the ESU status of hatchery populations associated with all listed salmon and steelhead ESUs, 

with the result that many hatchery populations are currently considered to be part of the ESUs. 

However, only a small fraction of these hatchery populations have been listed—generally, those 

associated with natural populations or ESUs considered at high risk of extinction. NMFS felt 

that listing other hatchery populations in the ESUs would provide little or no additional 

conservation benefit beyond that conferred by the listing of natural fish, but would greatly 

increase the regulatory burden on stakeholders, researchers, and the general public. 

As discussed, a recent court decision determined that this approach is inconsistent with 

the ESA—that is, an ESU must be listed or not listed in its entirety. At the same time that the 

agency announced the status review updates, NMFS committed to revising the ESA artificial 

propagation policy for Pacific salmonids and to using the revised policy to guide the hatchery 

ESU determinations and consideration of artificial propagation in the risk analyses (NMFS 

2002a). Although a revised artificial propagation policy has not yet been finalized, a draft has 

been available on the agency’s Web site (http://www.nwr.noaa.gov/HatcheryListingPolicy/ 

DraftPolicy.pdf) since August 2002. That draft indicates hatchery populations that have 

“diverged substantially from the evolutionary lineage represented by the ESU” will not be 

considered part of the ESU. The draft policy is currently under revision, and one issue that 

remains to be resolved is how “substantial” the divergence must be before a hatchery population 

should no longer be considered part of a salmon or steelhead ESU, even if it was originally 

derived from populations within the ESU. Due to the lack of resolution of this issue, the BRTs 

have not attempted to revisit the ESU determinations for hatchery populations in this report. 

However, a separate working group, the Salmon and Steelhead Hatchery Assessment Group 

(SSHAG), updated the stock histories and biological information for every hatchery population 

associated with each listed ESU (SSHAG 2003) and assigned each hatchery population to one of 

four categories, as described below. How these categories relate to ESU membership remains to 

be determined. A table showing the SSHAG categories appears in the appendix for each section 

of this report for each species. The BRTs reviewed the information in these appendices, along 

5
INTRODUCTION AND METHODS

with other hatchery information, to obtain a better understanding of the nature and role of 

hatcheries associated with each listed ESU. 

In the SSHAG document, each hatchery stock was assigned to a category based on 

variation across three axes (Figure 1): 1) the degree of genetic divergence between the hatchery 

stock and the natural populations that occupy the watershed into which the hatchery stock is 

released, 2) the origin of the hatchery stock, and 3) the status of the natural populations in the 

watershed. There are four categories of divergence: minimal, moderate, substantial, and 

extreme. Minimal divergence means that, based on the best information available, there is no 

appreciable genetic divergence between the hatchery stock and the natural populations in the 

watershed (e.g., because the hatchery and wild populations are well mixed in each generation). 

Moderate divergence means the level of divergence between the hatchery stocks and the local 

natural populations is no more than what would be expected between closely related populations 

within the ESU. Substantial divergence is roughly the level of divergence expected between 

more distantly related populations within the ESU. Extreme divergence is divergence greater 

than what would be expected among natural populations in the ESU, such as that caused by 

deliberate artificial selection or inbreeding. The second axis describes the origin of the hatchery 

stock, and it can either be local, nonlocal but predominantly from within the ESU, or 

predominantly from outside of the ESU. The third axis describes the status of the natural 

populations in the watershed of the same species as the hatchery stock, which can either be 

native or nonnative. 

Category 1 stocks are characterized by no more than minimal divergence between the 

hatchery stock and the local natural populations and regular, substantial incorporation of naturalorigin fish into the hatchery broodstock. Within category 1, category 1a stocks are characterized 

by the existence of a native natural population of the same species in the watershed, and category 

1b stocks are characterized by the lack of such a population (i.e., the local, naturally spawning 

population was introduced from elsewhere). Note that a category 1a designation can describe a 

range of biological scenarios, and does not necessarily imply that the hatchery stock and the 

associated natural population are close to a “pristine” state. For example, a hatchery program 

that started many years ago with local broodstock and regularly incorporated local natural-origin 

fish in substantial proportions thereafter would likely be a category 1a, even if both the hatchery 

stock and the local natural population have diverged from what the natural population was like 

historically. 

Category 2 stocks are no more than moderately diverged from the local, natural 

populations in the watershed. Category 2a stocks were founded from a local, native population 

in the watershed in which they are released. Category 2b stocks were founded nonlocally, but 

from within the ESU, and are released in a watershed that does not contain a native natural 

population. Category 2c stocks were founded nonlocally, but from within the ESU, and are 

released in a watershed that contains a native natural population. 

Category 3 stocks are substantially diverged from the natural populations in the 

watershed in which they are released. The a, b, and c designations are the same as described for 

category 2 above. 

6
1. INTRODUCTION

Source of hatchery stock and status of local population 

Local; native 

natural 

population 

Nonlocal but 

within ESU; no 

native local 

natural 

population 

Nonlocal but 

within ESU; 

native local 

natural 

population 

exists 

Nonlocal and 

predominantly 

from outside of 

ESU 

Substantial naturalorigin fish in 

broodstock and minimal 

divergence 

1a 1b NA 

Moderate to few 

natural-origin fish in 

broodstock and no more 

than moderate 

divergencea

2a 2b 2c 

Substantial divergenceb 3a 3b 3c 

4 

Relationship to natural population 

Extreme divergencec 4 4 4 4 

a

 Moderate divergence = no more than observed between similar populations within ESU. 

b

 Substantial divergence = comparable to divergence observed within entire ESU. c

 Extreme divergence = greater than divergence observed within ESU or substantial artificial selection or 

manipulation. 

Figure 1. Summary of the hatchery categorization system. Source: SSHAG (2003). 

Category 4 stocks are characterized either by being founded predominantly from sources 

that are not considered part of the ESU in question, or by extreme divergence from the natural 

populations in the watershed in which they are released, regardless of founding source. 

Resident Fish 

In addition to the anadromous life history, sockeye salmon and steelhead have 

nonanadromous or resident forms, generally referred to as kokanee (O. nerka) and rainbow trout 

(O. mykiss), respectively. (At least one resident population of Chinook salmon also occurs, in 

Lake Cushman, Washington.) As is the case with hatchery fish, it is important to determine the 

relationships of these resident fish to anadromous populations in listed ESUs. The complexity of 

jurisdictional responsibilities complicates this issue—NMFS has ESA responsibility for 

anadromous Pacific salmonids, but the U.S. Fish and Wildlife Service (USFWS) has ESA 

jurisdiction for resident fish. At the time this report was prepared, the two agencies had not 

developed a general policy on how to determine the ESU/DPS status of resident fish or how to 

make the listing determinations for the overall ESU/DPSs. 

7
INTRODUCTION AND METHODS

Resident (kokanee) populations in the two ESA-listed sockeye salmon ESUs (Redfish 

Lake and Ozette Lake) have been genetically characterized and determined not to be part of the 

sockeye salmon ESUs. However, the ESU status of many resident populations of O. mykiss 

remains in doubt. Therefore, for the purposes of this status review update, the BRTs adopted a 

working framework for determining the ESU/DPS status of O. mykiss that is geographically 

associated with listed steelhead ESUs. These evaluations were guided by the same biological 

principles used to define ESUs of natural fish and determine ESU membership of hatchery fish: 

the extent of reproductive isolation from and evidence of biological divergence from other 

populations within the ESU. These principles are comparable to the “discreteness” and 

“significance” criteria of the joint DPS policy of the two listing agencies (USFWS and NMFS 

1996). Ideally, each resident population would be evaluated individually on a case-by-case 

basis, using all available biological information. In practice, little or no information is available 

for most resident salmonid populations. 

To facilitate conclusions about the ESU/DPS status of resident fish, NMFS and USFWS 

identified three different cases, reflecting the range of geographic relationships between resident 

and anadromous forms within different watersheds: 

Case 1: No obvious physical barriers to interbreeding exist between resident and anadromous 

forms. 

Case 2: Long-standing natural barriers (e.g., a waterfall) separate resident forms upstream 

from anadromous forms downstream. 

Case 3: Relatively recent (e.g., within the last 100 years) human actions or man-made 

barriers (e.g., construction of a dam without provision for upstream fish passage) separate 

resident and anadromous forms. 

The BRTs reviewed available information about individual resident populations of 

O. mykiss to determine into which case each population fits. The BRTs also adopted, for the 

purpose of the updated status reviews and extinction risk assessments, the following working 

assumptions about ESU membership of resident O. mykiss falling in each of these categories: 

Case 1: Resident fish were assumed provisionally to be part of the ESU. Rationale: 

Empirical studies show that resident and anadromous O. mykiss are typically very similar 

genetically when they co-occur in sympatry, with no physical barriers to migration or 

interbreeding (Chilcote 1976, Currens et al. 1987, Leider et al. 1995, Pearsons et al. 1998). 

(Note: This assumption is not necessarily applicable to O. nerka, because sockeye and 

kokanee can show substantial divergence, even in sympatry.) 

Case 2: Resident fish were assumed provisionally not to be part of the ESU. Rationale: 

Many populations in this category have been isolated from contact with anadromous 

populations for thousands of years. Empirical studies (Chilcote 1976, Currens et al. 1990) 

show that, in these cases, the resident fish typically show substantial genetic and life history 

divergence from the nearest downstream anadromous populations. 

Case 3: No default assumption was made about ESU status of resident fish. 

The default assumptions about ESU membership for case 1 and case 2 populations can be 

overridden by specific information for individual populations. For example, as noted above, 

8
1. INTRODUCTION

anadromous and resident O. nerka can diverge substantially in sympatry, and it is possible the 

same may be true for some O. mykiss populations. 

The BRTs discussed case 3 populations at some length. Case 3 populations were most 

likely case 1 populations (and hence presumably part of the ESU) prior to construction of the 

artificial barrier. Some BRT members felt that, in the absence of information to the contrary, it 

is reasonable to assume that case 3 populations of O. mykiss are still in the ESU, given that the 

time since erection of the artificial barriers has been relatively short for substantial evolutionary 

divergence to have occurred. However, the majority of the BRT members preferred to make no 

particular assumption regarding case 3 populations for two main reasons. First, case 3 

populations that historically were part of the ESU may no longer represent the ESU biologically 

because of 1) bottlenecks or local adaptation and rapid evolutionary divergence in a novel 

environment; or 2) displacement or introgression from nonnative, hatchery-origin rainbow trout. 

Notably, releases of hatchery rainbow trout have been widespread in the Pacific Northwest and 

California, including areas impounded by dams that block access to anadromous fish (Ludwig 

1995, Van Vooren 1995). Empirical studies (Wishard et al. 1984, Williams et al. 1997, Utter 

2001) have shown that the results of such releases can be quite variable, ranging from 

replacement of the native gene pool to hybridization to no detectable genetic effect. Therefore, 

the current relationship between case 3 populations and anadromous populations in the ESU is 

difficult to evaluate without empirical data and historical stocking records for the population in 

question. Second, identifying a default assumption for case 3 populations in the face of 

considerable biological uncertainty requires consideration of other factors that are not entirely 

scientific: What is the appropriate burden of proof? What are the biological, economic, and 

political consequences of making a wrong assumption? Therefore, because of these issues, in 

this report, the BRTs did not suggest a default assumption regarding the ESU status of case 3 

populations. Instead, this report summarizes empirical information that does exist for specific 

case 3 populations and discusses its relevance to ESU determinations. As new biological 

information relevant to the ESU status of individual case 3 populations is developed as part of 

the overall recovery planning process for West Coast salmon and steelhead (described in the 

species subsections titled Background and Introduction) that information will be passed on to 

NMFS regional office staff for consideration. 

Genetic data can provide a powerful means for determining the evolutionary origin of a 

sampled population, and such data can therefore be useful in evaluating the extent to which 

native resident O. mykiss populations have been affected by releases of nonnative hatchery 

rainbow trout. The steelhead ESU reports in this technical memorandum summarize this 

information as it applies to specific case 3 populations. As discussed, rapid genetic changes 

associated with human impacts can also occur within populations in the absence of stock 

transfers, and these changes are unlikely to be detected with standard molecular genetic 

techniques. Evaluating the importance of such effects is very difficult. Phenotypic and life 

history traits can serve as proxies for genetically based, adaptive differences among populations; 

however, environmental conditions can affect such traits, which confounds their interpretation. 

These confounding effects can generally be teased apart only with very detailed experiments. It 

is therefore likely that the evolutionary relationships of many case 3 populations will remain 

uncertain for the foreseeable future. 

9
INTRODUCTION AND METHODS

In response to a request for additional information about listed ESUs of steelhead (NMFS 

2002b), NMFS received two comments relevant to the ESU status of resident O. mykiss. The 

Center for Biological Diversity (CBD 2003) argued that NMFS erred in referring to O. mykiss

trapped above dams as “resident” fish and excluding them from the steelhead listings. 

According to the CBD, the distinction between anadromous and resident populations should be 

based not on circumstances of geography (i.e., whether the fish are currently above or below a 

recent man-made barrier), but rather on biological attributes of the populations—specifically, the 

“genetic trait expressed in smoltification.” They argued that resident populations that are 

genetically (i.e., historically) anadromous but currently trapped above human barriers with no 

opportunity to express anadromy should be considered part of the listed steelhead ESUs. The 

conclusions of the BRTs regarding the ESU status of case 3 resident populations (above human 

barriers) are described in the previous discussion. 

Trout Unlimited (2003) argued that, based on substantial ecological and life history 

differences, anadromous and resident O. mykiss should be in separate ESUs, even in cases where 

there are no appreciable molecular genetic differences between the two forms. They cited 

studies showing 1) little evidence that transplanted rainbow trout can give rise to anadromous 

populations, and 2) one study in the Deschutes River, in which all anadromous fish examined 

were found to have an anadromous female parent and all resident fish examined were found to 

have a resident female parent, as evidence for a genetic basis for the differences between the two 

forms. This argument is similar to the arguments the BRTs considered in previous status 

reviews, that summer- and winter-run steelhead, or spring- and fall-run Chinook in coastal 

basins, should be in different ESUs (Busby et al. 1996, Myers et al. 1998). As in those status 

reviews, the BRTs do not dispute that the two forms of O. mykiss can exhibit some degree of 

reproductive isolation, even in areas where they co-occur. However, the strong genetic similarity 

of the two forms in sympatry in every case where they have been examined indicates that, in 

general, the two forms are genetically linked on evolutionary time frames. Furthermore, the 

Deschutes River study (Zimmerman and Reeves 2000) also examined a population in British 

Columbia, where the authors found that anadromous fish can give rise to resident offspring, and 

vice versa—a result that has been found in other areas as well. In general, genetic data show that 

resident and anadromous O. mykiss below barriers in the same basin are genetically more similar 

to each other than either is to the same form in another basin. Therefore, lumping steelhead and 

resident populations into separate ESUs would create artificial units in which each population 

had its nearest relative in a different ESU. This problem could be resolved only by considering 

every population (anadromous or resident) its own ESU—a result that would lead to hundreds of 

ESUs of O. mykiss and would be inconsistent with the approach NMFS has taken in all other 

status reviews for Pacific salmonid. Therefore, the BRTs continued to consider the evolutionary 

relationships between resident and anadromous populations in a way that was consistent with the 

approach used in evaluating alternative life history forms in previous status reviews. 

Although resident O. mykiss may occasionally produce anadromous offspring, and vice 

versa, there is (as noted by Trout Unlimited 2003) little empirical evidence to indicate that a 

population of resident O. mykiss can give rise to a self-sustaining anadromous population. This 

issue is relevant to extinction risk analysis for ESUs containing both forms and is discussed in 

the steelhead report. 

10
1. INTRODUCTION

Risk Assessments 

ESA Definitions 

After the composition of an ESA species is determined, the next question to address is “Is 

the species threatened or endangered?” Section 3 of the ESA defines endangered species as “any 

species which is in danger of extinction throughout all or a significant portion of its range.” The 

term threatened species is defined as “any species which is likely to become an endangered 

species within the foreseeable future throughout all or a significant portion of its range.” Neither 

NMFS nor the USFWS have developed formal policy guidance about how to interpret the ESA 

definitions of threatened or endangered species. 

The BRTs consider a variety of information in evaluating the level of risk an ESU faces. 

According to Section 4 of the ESA, the determination of whether a species is threatened or 

endangered should be made “solely on the basis of the best scientific and commercial data 

available” regarding the species’ current status, after taking into account efforts made to protect 

the species. In their biological status reviews, the BRTs do not evaluate possible future effects of 

protective efforts, except to the extent the effects are already reflected in metrics of population or 

ESU viability. The NMFS regional offices take into account protective efforts in a separate 

process prior to making listing determinations. Therefore, the BRTs do not make 

recommendations as to whether identified ESUs should be listed as threatened or endangered 

species because that determination requires evaluation of factors the teams do not consider. 

Rather, the BRTs draw scientific conclusions about the current risk of extinction faced by ESUs, 

under the assumption that present conditions will continue into the future (recognizing, of 

course, that natural demographic and environmental variability are inherent features of “present 

conditions”). 

Factors for Decline 

According to Section 4 of the ESA, the Secretary of Commerce or the Interior shall 

determine whether a species is threatened or endangered as a result of any or a combination of 

the following factors: destruction or modification of habitat, overutilization, disease or predation, 

inadequacy of existing regulatory mechanisms, or other natural or man-made factors. 

Collectively, these factors are often referred to as “factors for decline.” In the Federal Register

notices announcing the ESA listing decisions for West Coast salmon and steelhead (see 

Background and History subsection of each species for more detail), NMFS included sections 

identifying what have come to be known as the 4H factors for decline—habitat degradation and 

loss, hydropower development, overharvest, and hatchery propagation—as well as other factors. 

However, in the status reviews, the BRTs did not attempt a rigorous analysis of this subject, and 

the same is true for this report. There are several reasons for this approach. 

• First, the BRTs chose to focus primarily on the question of whether an ESU is at risk, 

rather than how it came to be at risk. Although the latter question is important, a 

population or ESU that has been reduced to low abundance will continue to be at risk for 

demographic and genetic reasons until it reaches a larger size, regardless of the reasons 

for its initial decline. Furthermore, in some cases, a factor that was important in causing 

the original declines may no longer be an impediment to recovery. 

11
INTRODUCTION AND METHODS

• Second, unlike many other ESA-listed species that face a single primary threat, salmon 

face a bewildering array of potential threats throughout every stage of their complex life 

cycle. It is relatively easy to simply enumerate current and past threats to salmon 

populations, but it is much more difficult to evaluate the relative importance of a wide 

range of interacting factors. 

• Third, evaluating the degree to which historical factors for decline will continue to pose a 

threat in the future generally requires consideration of issues that are more in the realm of 

social science than biological science—such as whether proposed changes will be funded, 

and, if funded, will be implemented effectively. 

In its listing determination for the updated status reviews, NMFS considers factors for 

decline and the extent to which protective efforts have alleviated those factors. The BRTs expect 

that, for ESUs that remain listed, formal ESA recovery planning will address these issues in 

detail. The agency has outlined a two-step process for recovery planning: the first step is 

identifying biologically based delisting criteria, and the second step is developing a suite of 

actions (the Recovery Plan) that has a high probability of achieving the recovery goals. (For 

more information about ESA recovery planning for West Coast salmon and steelhead, visit 

http://www.nwfsc.noaa.gov/trt/about.htm.) Delisting occurs only after the ESU satisfies both the 

biological delisting criteria and associated administrative delisting criteria, which typically 

involve assurances that the threats to the continued existence of the ESU have been resolved. 

Although this technical memorandum does not consider factors for decline in a 

comprehensive way, the BRTs considered major risk factors identified in previous status 

reviews. The sections focusing on specific ESUs summarize the previous BRT conclusions and 

identify any major changes in risk factors that have occurred since the time of listing. 

Artificial Propagation 

The 1993 NMFS ESA policy for artificial propagation of Pacific salmon and steelhead 

recognizes that artificial propagation can be one of the conservation tools used to help achieve 

recovery of ESA-listed species, but it does not consider hatcheries to be a substitute for 

conservation of the species in its natural habitat. Therefore, ESA risk analyses for salmon and 

steelhead ESUs were conducted for “natural-origin” fish (which are defined as the progeny of 

naturally spawning fish), based on whether or not the natural populations can be considered selfsustaining without regular infusion of hatchery fish. This is the same provision articulated in the 

joint USFWS-NMFS policy on artificial propagation of all species under the ESA (USFWS and 

NMFS 2002) and is consistent with the approach the USFWS has used to evaluate captive 

propagation programs for other species, such as the California condor (USFWS 1996) and the 

bonytail chub (USFWS 2002). 

The draft revised salmon hatchery policy outlines a three-step approach for considering 

artificial propagation in listing determinations: 

1. Identify which hatchery populations are part of the ESU (see previous section). 

2. Review the status of the ESU. 

3. Evaluate existing protective efforts and make a listing determination. 

12
1. INTRODUCTION

This document is concerned with step 2—reviewing the status for listed salmon and steelhead 

ESUs via risk analyses. 

The draft revised hatchery policy interprets the purpose of the ESA as to conserve 

threatened and endangered species in their natural habitats. In its risk evaluations, the BRTs 

therefore used the approach they have in the past—focusing on whether populations and ESUs 

are self-sustaining in their natural habitat. In this report, therefore, when we refer to BRT 

evaluations or conclusions regarding the status of ESUs, we are referring to analyses conducted 

using the criterion of self-sustainability of natural populations. 

Artificial propagation can be used as a conservation tool. Potential benefits of artificial 

propagation for natural populations include reducing the short-term risk of extinction, helping to 

maintain a population until the factors limiting recovery can be addressed, reseeding vacant 

habitat, and helping to speed recovery. Whether these potential benefits will be realized in any 

particular case is difficult to predict. To the extent that such benefits have already occurred, they 

are reflected in the population abundance and trend data the BRTs considered. The draft revised 

hatchery policy also indicates that the potential future conservation benefits of artificial 

propagation should be considered before making a listing determination. NMFS regional office 

and headquarters staff will consider the potential conservation benefits of artificial propagation, 

together with other protective efforts, in determining whether to propose any changes to the 

current ESA listing for West Coast salmon and steelhead. 

Artificial propagation is important to consider in ESA evaluations of anadromous Pacific 

salmonids for several other reasons. First, although natural fish are the subject of risk 

assessments, possible positive or negative effects of artificial propagation on natural populations 

must also be evaluated. For example, artificial propagation can alter life history characteristics 

such as smolt age and migration, and spawn timing. Second, in addition to the potential to 

increase abundance of fish, artificial propagation poses a number of risks to natural populations 

that may affect their risk of extinction or endangerment. In contrast to most other types of risk 

for salmon populations, those arising from artificial propagation are often not reflected in 

traditional indices of population abundance. For example, to the extent that habitat degradation, 

overharvest, or hydropower development have contributed to a population’s decline, these 

factors will already be reflected in population abundance data and accounted for in the risk 

analysis. The same is not necessarily true of artificial propagation. Hatchery production may 

mask declines in natural populations that will be missed if only raw population abundance data 

are considered. Therefore, a true assessment of the viability of natural populations cannot be 

attained without information about the genetic and demographic contribution of naturally 

spawning hatchery fish. Furthermore, even if such data are available, they will not in themselves 

provide direct information about possible deleterious effects of fish culture. Such an evaluation 

requires consideration of the genetic and demographic risks of artificial propagation for natural 

populations. 

Resident Fish 

As indicated, the BRTs concluded in previous status reviews that at least some resident 

O. mykiss populations belonged to steelhead ESUs, and these resident fish were considered in the 

overall risk analyses for those ESUs. However, in most cases, little or no information was 

13
INTRODUCTION AND METHODS

available about the numbers and distribution of resident fish, or about the extent and nature of 

their interactions with anadromous populations. Given this situation, the previous risk analyses 

for steelhead ESUs focused primarily on the status of anadromous populations. 

In these updated status reviews, increased efforts have been made to gather biological 

information for resident O. mykiss populations to assist in the risk analyses. For example, 

although the two listed sockeye salmon ESUs considered in this report (Redfish Lake and Ozette 

Lake) have associated kokanee populations, in neither case are they considered to be part of the 

sockeye salmon ESU, so kokanee were not formally considered in the risk analyses. Information 

on resident fish is summarized in the steelhead sections (14–25), where ESU-specific 

information is discussed in more detail. The steelhead background information section also 

contains a more general discussion of how the BRTs considered resident fish in the risk analyses 

for steelhead ESUs. 

Factors Considered in Status Assessments 

Salmonid ESUs are typically metapopulations; that is, they are usually composed of 

multiple populations with some degree of interconnection, at least over evolutionary time 

periods. These multiple populations make the assessment of extinction risk difficult. The 

approach to this problem that NMFS adopted for recovery planning is outlined in the VSP report 

(McElhany et al. 2000). In this approach, risk assessment is addressed at two levels: first at the 

population level, then at the overall ESU level. We have modified previous BRT approaches to 

ESU risk assessments to incorporate VSP considerations. 

Individual populations are assessed according to the four VSP criteria: abundance, 

growth rate/productivity, spatial structure, and diversity. We then summarize the condition of 

individual populations on the ESU level and consider larger-scale issues in evaluating the status 

of the ESU as a whole. These larger-scale issues include total number of viable populations, 

geographic distribution of these populations (to ensure inclusion of major life history types and 

to buffer the effects of regional catastrophes), and connectivity among these populations (to 

ensure appropriate levels of gene flow and recolonization potential in case of local extirpations). 

McElhany et al. (2000) details these considerations. 

In previous status reviews, the BRTs have used a simple “risk matrix” for quantifying 

ESU-scale risks according to major risk factors. The revised matrix (Table 1) integrates the four 

major VSP criteria (abundance, productivity, spatial structure, and diversity) directly into the risk 

assessment process. After reviewing all relevant biological information for a particular ESU, 

each BRT member assigns a risk score (see below) to each of the four VSP criteria. Use of the 

risk matrix makes it easier to compare risk factors within and across ESUs. The BRT tallies and 

reviews the scores before making its overall risk assessment (see Forest Ecosystem Management 

Assessment Team [FEMAT] method, below). Although this process helps to integrate and 

quantify a large amount of diverse information, there is no simple way to translate the riskmatrix scores directly into an assessment of overall risk. For example, simply averaging the 

values of the various risk factors would not be appropriate: an ESU at high risk for low 

abundance would be at high risk even if there were no other risk factors. 

14
1. INTRODUCTION

Scoring VSP Criteria 

Risks for each VSP factor are ranked on a scale of 1 (very low risk) to 5 (very high risk): 

1. Very Low Risk. Unlikely that this factor contributes significantly to risk of extinction, 

either by itself or in combination with other factors. 

2. Low Risk. Unlikely that this factor contributes significantly to risk of extinction by itself, 

but some concern that it may, in combination with other factors. 

3. Moderate Risk. This factor contributes significantly to long-term risk of extinction, but 

does not in itself constitute a danger of extinction in the near future. 

4. High Risk. This factor contributes significantly to long-term risk of extinction and is 

likely to contribute to short-term risk of extinction in the foreseeable future. 

5. Very High Risk. This factor by itself indicates danger of extinction in the near future. 

Recent Events 

The recent events category considers events that have predictable consequences for ESU 

status in the future but have occurred too recently to be reflected in the population data. 

Examples include a flood that decimated most eggs or juveniles in a recent broodyear, or large 

jack returns that generally anticipate strong adult returns in subsequent years. This category is 

scored as follows: 

++ Expect a strong improvement in status of the ESU 

+ Expect some improvement in status 

0 Neutral effect on status 

– Expect some decline in status 

– – Expect strong decline in status 

Historical Distribution and Abundance 

The ESA has no provision that requires a species to occupy its entire historical habitat or 

reach historical levels of abundance before it can be considered no longer threatened or 

endangered. Using the VSP criteria described above, it is only necessary that an ESU contain 

enough viable populations and satisfy concerns for spatial structure and diversity. However, 

developing strictly quantitative viability criteria is extremely challenging, even at the population 

level (see Section 2, Methods). Therefore, other approaches that provide insight into viability 

are also important to consider. If our definitions of ESUs (groups of populations on independent 

evolutionary trajectories) and populations (demographically independent units over at least a 

100-year time frame) are correct, then by definition they were sustainable at historical levels. 

Therefore, we can be confident that a population or ESU that approximates its historical 

distribution and abundance will be viable into the future. This a priori presumption of viability 

diminishes the further the current status departs from the historical template. For a population or 

ESU that is greatly reduced from its historical distribution or abundance, there is little a priori 

reason to assume the current status is viable. The viability of such a population or ESU is in 

considerable doubt unless independent data can be developed to assess viability.

15
INTRODUCTION AND METHODS

Table 1. Template for the risk matrix used in BRT deliberations. The matrix is divided into five 

sections that correspond to the four viable salmonid population parameters from McElhany et al. 

(2000) plus a recent events category. 

[Evolutionarily significant unit (ESU) name]

Risk category Score*

Abundance

Comments: 

Growth Rate/Productivity

Comments: 

Spatial Structure and Connectivity

Comments: 

Diversity

Comments: 

Recent Events

*

 Rate overall risk of ESU on 5-point scale (1 = very low risk; 2 = low risk; 3 = moderate risk; 4 = increasing risk; 

5 = high risk), except recent events double plus (++ = strong benefit) to double minus (– – = strong detriment). 

16
1. INTRODUCTION

Marine Productivity 

In the last decade, evidence has accumulated to demonstrate 1) recurring, decadal-scale 

patterns of ocean-atmosphere climate variability in the North Pacific Ocean (Mantua et al. 1997, 

Zhang et al. 1997), and 2) correlations between these oceanic productivity “regimes” and salmon 

population abundance in the Pacific Northwest and Alaska (Hare et al. 1999, Mueter et al. 2002). 

There seems to be little doubt that survival rates in the marine environment can be strong 

determinants of population abundance for Pacific salmon and steelhead. It is also generally 

accepted that for at least two decades, beginning about 1977, marine productivity conditions 

were unfavorable for the majority of salmon and steelhead populations in the Pacific Northwest 

(in contrast, many populations in Alaska attained record abundances during this period). Finally, 

evidence shows an important shift in ocean-atmosphere conditions occurred around 1998. One 

indicator of the ocean-atmosphere variation for the North Pacific is the Pacific Decadal 

Oscillation (PDO) index; Figure 2 shows that since 1999 (time period C on the graph), PDO 

values have been mostly negative, whereas the values were positive in most of the previous two 

decades (time period B) and generally negative again for a long period before that (period A). 

Negative PDO values are associated with relatively cool ocean temperatures (and generally high 

salmon productivity) off the Pacific Northwest, and positive values are associated with warmer, 

less productive conditions. As discussed in this report, increases in many salmon populations in 

recent years may be largely a result of more favorable ocean conditions. 

Although these climate-related facts are relatively well established, much less certainty 

can be attached to predictions about what this means for the viability of listed salmon and PDO Index

-4

-2

0

2

4

1900 1920 1940 1960 1980 2000

A

B

C

Figure 2. Monthly values for the Pacific Decadal Oscillation (PDO) index, which is based on sea surface 

temperatures in the North Pacific. Values shown are deviations from the long-term (1900–1993) 

mean. See text for discussion of time periods A, B, and C. Source: Online at 

http://tao.atmos.washington.edu/pdo/. 

17
INTRODUCTION AND METHODS

steelhead. For several reasons, considerable caution is needed to project into the future. First, 

empirical evidence for “cycles” in PDO, marine productivity, and salmon abundance extends 

back only about a century, or about three periods of two to four decades in duration. These 

periods form a very short data record for inferring future behavior of a complex system. Thus as 

with the stock market, the past record is no guarantee of future performance. Second, the past 

decade has seen particularly wide fluctuations not only in climatic indices (e.g., the 1997–1998 

El Niño was in many ways the most extreme ever recorded, and the 2000 drought was one of the 

most severe on record) but also in abundance of salmon populations. In general, as the 

magnitude of climate fluctuations increases, the population extinction rate also increases. Third, 

if anthropogenically caused climate change occurs in the future, it could affect ocean 

productivity. The range of future climate change scenarios consistent with existing data is so 

great that future consequences cannot be predicted with any certainty; however, many models 

suggest that northern latitudes are likely to experience significant temperature increases (IPCC 

2001). Finally, changes in the pattern of ocean-atmosphere interactions do not affect all species 

(or even all populations of a given species) in the same way (Peterman et al. 1998). 

Based on these considerations, the BRTs identified a number of possible future scenarios 

for impacts of ocean productivity on listed salmon and steelhead populations: 

1. The PDO index could remain primarily negative for another decade or two (a typical 

duration for regimes observed in the past), leading to marine productivity conditions that 

are generally more favorable to Pacific Northwest salmon and steelhead than those that 

occurred from the mid-1970s to the late 1990s. 

2. The last several years might be an anomaly, and the PDO index might revert back to the 

positive regime it has largely been in since the mid-1970s. It is worth noting in this 

regard that the PDO index has been positive in every month from August 2002 through 

March 2003 (Figure 2). 

3. Marine and freshwater systems may continue to see wide fluctuations in environmental 

conditions. 

4. Anthropogenically caused climate change might be a significant factor in the future, with 

difficult-to-predict consequences. 

Given all these uncertainties, the BRTs were reluctant to make any specific assumptions 

about the future behavior of the ocean-atmospheric systems or their effects on the distribution 

and abundance of salmon and steelhead. The BRTs were concerned that even under the most 

optimistic scenario (1), increases in abundance might be only temporary and could mask a failure 

to address underlying factors for decline. The real conservation concern for West Coast salmon 

and steelhead is not how they perform during periods of high marine survival, but how prolonged 

periods of poor marine survival affect the VSP parameters of abundance, growth rate, spatial 

structure, and diversity. It is reasonable to assume that salmon populations have persisted over 

time, under pristine conditions, through many such cycles in the past. Less certain is how the 

populations will fare in periods of poor ocean survival when their freshwater, estuary, and 

nearshore marine habitats are degraded. 

18
1. INTRODUCTION

Overall Risk Assessment 

The BRT analysis of overall risk to the ESU uses categories that correspond to definitions 

in the ESA: in danger of extinction, likely to become endangered in the foreseeable future, or 

neither. (As discussed, these evaluations do not consider protective efforts, and therefore are not 

recommendations regarding listing status.) The overall risk assessment reflects each BRT 

member’s professional judgment. The results of the risk matrix analysis as well as expectations 

about likely interactions among factors guide this assessment. For example, a single factor with 

a “high risk” score might be sufficient to result in an overall score of “in danger of extinction,” 

but a combination of several factors with more moderate risk scores could also lead to the same 

conclusion. 

To allow for uncertainty in judging the actual risk facing an ESU, the BRTs have adopted 

a “likelihood point” method, often referred to as the FEMAT method because it is a variation of 

a method scientific teams used in evaluating options under President Clinton’s Forest Plan 

(FEMAT 1993). In this approach, each BRT member distributes 10 likelihood points among the 

three ESU risk categories, reflecting the member’s opinion of how likely that category correctly 

reflects the true ESU status. Thus, if a reviewer were certain that the ESU was in the “not at 

risk” category, he or she could assign all 10 points to that category. A reviewer with less 

certainty about ESU status could split the points among two or even three categories. This 

method has been used in all status review updates for anadromous Pacific salmonids since 1999.

19
2. Methods 

The BRTs requested data on abundance, the fraction of hatchery-origin spawners, 

harvest, age structure, and hatchery releases from state, federal, and tribal sources (NMFS 

2002a) and compiled the data with previous data to conduct updated risk analyses for each ESU. 

The BRTs obtained data on adult returns from a variety of sources, including time series of 

freshwater spawner surveys, redd counts, and counts of adults migrating past dams or weirs. 

Time series were assembled and analyzed at the scale of VSP populations where TRTs have 

identified these populations, or putative populations where TRTs are in the process of identifying 

them. 

State, federal, and tribal comanagers reviewed preliminary data and analyses for accuracy 

and completeness. Where possible, the BRTs obtained population or ESU-level estimates of the 

fraction of hatchery-origin spawners or calculated estimates from information using scale 

analyses, fin clips, and so on. Harvest estimates were obtained for some stocks directly; for 

others, harvest rates on nearby indicator stocks were used to estimate the number of fish in the 

target population that would have returned to spawn in the absence of harvest. See appendices 

for each species section for detailed information and references for data sources. 

Recent Abundance 

Recent abundance of natural spawners is reported as the geometric mean (and range) of 

the most recent data to be consistent with previous coastwide status reviews of these species 

(Weitkamp et al. 1995, Busby et al. 1996, Gustafson et al. 1997, Johnson et al. 1997, Myers et al. 

1998). Geometric means were calculated to represent the recent abundance of natural spawners 

for each population or quasi-population within an ESU. Geometric means were calculated for 

the most recent 5 years (Chinook, steelhead), 4 years (chum, sockeye), or 3 years (coho); these 

time frames were selected to correspond with modal age at maturity for each species. Zero 

values in the data set were replaced with a value of 1, and missing data values within a multipleyear range were excluded from geometric mean calculations. The geometric mean is the nth root 

of the product of the n data: 

n G NNNNX n ... = 321 (1) 

where Nt is the abundance of natural spawners in year t. Arithmetic means (and ranges) were 

also calculated for the most recent abundance data: 

n

N

X i

A = ∑ (2) 

where Nt is the abundance of natural spawners in year t. 

20 
2. METHODS 

Trends in Abundance 

Short- and long-term trends were calculated from time series of the total number of adult 

spawners. Short-term trends were calculated using data from 1990 to the most recent year, with 

a minimum of 10 data points in the 13-year span. Long-term trends were calculated using all 

data in a time series. 

Trend was calculated as the slope of the regression of the number of natural spawners 

(log-transformed) over the time series; to mediate for zero values, 1 was added to natural 

spawners before transforming the data. Trend was reported in the original units as exponentiated 

slope, such that a value great than 1 indicates a population trending upward, and a value greater 

than 1 indicates a population trending downward. The regression was calculated as: 

N β +=+ β X + ε 10 ln( )1 (3) 

where N is the natural spawner abundance, β0 is the intercept, β1 is the slope of the equation, and 

ε is the random error term. 

Confidence intervals (95%) for the slope, in their original units of abundance, were 

calculated as 

)exp(ln( ) )exp(ln( ) 1 1 ),2(05.01 bdf 1 ),2(05.01 bdf − stb ≤ β ≤ + stb (4) 

where b1 is the estimate of the true slope, β1, t0.05(2), df is the two-sided t-value for a confidence 

level of 0.95, df is equal to n – 2, n is the number of data points in the time series, and sb1 is the 

standard error of the estimate of the slope, b1. The probability that the trend value was declining 

[P(trend < 1)] was also calculated. 

Population Growth Rate 

In addition to analyses of trends in natural spawners, we calculated the median short-term 

population growth rate (λ) of natural-origin spawners as a measure for comparative risk analysis. 

Lambda more accurately reflects the biology of salmon and steelhead, as it incorporates 

overlapping generations and calculates running sums of cohorts. It is an essential parameter in 

viability assessment, as most population extinctions are the result of steady declines (λ < 1). It 

has been developed for data sets with high sampling error and age-structure cycles (Holmes 

2001). These methods have been extensively tested using simulations for both threatened and 

endangered populations as well as for stocks widely believed to be at low risk (Holmes 2004), 

and cross-validated with time-series data (Holmes and Fagan 2002). 

The λ of natural-origin spawners was calculated in two ways for each population over the 

short-term time frame (1990–most recent year). The first (λ) assumed that hatchery-origin 

spawners had zero reproductive success, while the second (λh) assumed that hatchery-origin 

spawners had reproductive success equivalent to that of natural-origin spawners. These extreme 

assumptions bracket the range likely to occur in nature. Empirical studies indicate that hatcheryorigin spawning fish generally have lower (and perhaps much lower) reproductive success than 

natural-origin spawners (reviewed by Reisenbichler and Rubin 1999). However, this difference 

can vary considerably across species and populations, and it is very rare that data are available 

21 
INTRODUCTION AN D METHODS

for a particular population of interest. Therefore, to be conservative, we bracketed the scenarios 

that are likely to be occurring in nature. 

A multistep process based on methods developed by Holmes (2001), Holmes and Fagan 

(2002) and described in McClure et al. (2003) was used to calculate estimates for λ, its 95% 

confidence intervals, and its probability of decline [P(λ < 1)]. The first step was calculating 

4-year running sums for natural-origin spawners as 

∑=

= +−

4

1

1

i

t NR it (5) 

where Nt is the number of natural-origin spawners in year t. A 4-year running sum window was 

used for all species, as analysis by McClure et al. (2003) indicates that this is an appropriate 

window for a diverse range of species life histories. 

Next, an estimate of μ, the rate at which the median of R increases through time (Holmes 

2001), was calculated as 

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ = +

t

t

R

R mean 1 μˆ ln (6) 

the mean of the natural log-transformed running sums of natural-origin spawners. The point 

estimate for λ was then calculated as the median annual population growth rate, 

μ λ ˆ ˆ = e (7) 

Confidence intervals (95%) were calculated for λ to provide a measure of the uncertainty 

associated with the growth rate point estimate. First, an estimate of variability for each 

population was determined by calculating an estimate for 

2

 using the slope method (Holmes 

2001). The slope method formula is 

σ pop

ˆ ln varof slope . vs. 2 t σ τ τ

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ = +

t

pop R

R (8) 

where τ is a temporal lag in the time series of running sums. 

Individual population variance estimates were highly uncertain, so a more robust variance 

estimate, , was obtained by averaging the estimates from all the populations in an ESU. 

This average variance estimate was then applied as the variance for every population in an ESU. 

The degrees of freedom associated with the average variance estimate are obtained by summing 

the degrees of freedom for each of the individual population variance estimates. The degrees of 

freedom for the individual population estimates were determined using the method of Holmes 

and Fagan (2002), which identifies the adjusted degrees of freedom associated with slope method 

variance estimates. The calculation for the adjusted degrees of freedom is 

2 σ avg2 σ pop

df = 0.212n – 1.215 (9) 

where n is the length of the time series. Using the average variance estimate and the summed 

degrees of freedom, the 95% confidence intervals for λ were calculated as 

22 
2. METHODS 

( )⎟

⎠

⎞ ⎜

⎝

⎛ exp ˆ ± ˆ − 4/ 2

),2(05. t n μ σ slpdf (10) 

In addition, the probability that the population growth rate was declining [P(λ < 1)] was 

calculated using the fact that ln(λ) follows a t-distribution. This probability is calculated by 

finding the probability that the natural log of the calculated lambda divided by its standard error 

is less than zero. 

The preceding treatment ignores contributions of hatchery-origin spawners to the next 

generation, in effect assuming that they had zero reproductive success. This assumption 

produces the most optimistic view of viability of the natural population. The other extreme 

assumption (that hatchery-origin spawners have reproductive success equivalent to that of 

natural-origin spawners), produces the most pessimistic view of viability of the natural 

population, given any particular time series of data. To calculate the median growth rate under 

this assumption (λh), a modified approach to the method Holmes (2001) developed was used to 

calculate estimates for λ h, 95% confidence intervals for λh, and to determine P(λh < 1). The first 

step was calculating 4-year running sums (RN) for natural-origin spawners as 

∑=

= +−

4

1

1 )(

i

RN t N it (11) 

Next, the 4-year running sum of hatchery-origin spawners was calculated as 

∑=

= +−

4

1

1 )(

i

RH t H it (12) 

where Ht is the number of hatchery spawners in year t. 

The ratio of total spawners to natural-origin spawners was calculated as 

. )(

)()(

t

t t

t RN

+ RHRN

ψ = (13) 

The average age at reproduction, T, was calculated in three steps: 

1. Determine the total number of spawners for each age (A) by calculating 

∑∑=

= +

age max

1 

.)(

j

t

tall

A j j HNa (14) 

2. Calculate the total number of spawners (G): 

∑=

=

age

j

AG j

max

1

 (15) 

3. Determine the average age at reproduction (TT) by calculating 

∑=

× =

age

j

j

G

Aj T

max

1

 (16) 

23 
INTRODUCTION AN D METHODS

Next, an estimate of μ, the rate at which the median increases through time (Holmes 

2001), was calculated as 

( ) .ln 1

)(

)( ˆ ln 1

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ −⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ = +

t

t

t

TRN

RN

μ mean ψ (17) 

The point estimate for λh was then calculated as the median annual population growth rate 

(Equation 7). 

Confidence intervals (95%) for λh and its probability of decline [P(λh < 1)] were 

calculated as for λ, with modification to the slope method for calculating the variance 

ln . vs.

1

)(

)( ˆ ln varof slope

1

0

2 t σ τψ

τ

τ

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

⎟

⎟

⎠

⎞ ⎜

⎜

⎝

⎛ −⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ = ∏

−

=

+

+

i

it

t TRN

RN (18)

Calculating Recruits 

Recruits, or spawners in the next generation, from a given broodyear were calculated as 

it

MaxAge

i

t it iANC +

=

= ∑ + )(

1

 (19) 

where Ct is the number of recruits from broodyear t, Nt is the number of natural-origin spawners 

in year t, and A(i)t is the fraction of age i spawners in year t. The estimate of preharvest recruits 

is similarly 

( ) it

MaxAge

i

t it C preHarvest iAP +

=

= ∑ + )(

1

 (20) 

where C(preHarvest)t is the number of preharvest recruits in year t, Pt is the number of naturalorigin spawners that would have returned in year t if there had not been a harvest, and A(i)t is the 

fraction of age i spawners in year t had there not been a harvest. (Because Pt is in terms of the 

number of fish that would have appeared on the spawning grounds had there not been a harvest, 

it can be quite difficult to estimate; thus simplifying assumptions are often made.) 

Population Viability Analysis 

Scientists have used a variety of quantitative approaches to population viability analysis 

(PVA) with Pacific salmonids. Because no consensus has emerged on how best to model 

population viability in salmon, we did not employ a standardized PVA model in this report. 

However, we considered results of population viability analyses that had been conducted for 

specific populations. 

24 
CHINOOK SALMON

25 
26 
3. Background and History 

of Chinook Salmon Listings 

Chinook salmon (Oncorhynchus tshawytscha), also commonly referred to as king, spring, 

quinnat, Sacramento, California, or tyee salmon, is the largest of the Pacific salmon (Myers et al. 

1998). The species historically ranged from the Ventura River in California to Point Hope, 

Alaska, in North America; and in northeastern Asia from Hokkaido, Japan, to the Anadyr River 

in Russia (Healey 1991). Additionally, Chinook salmon have been reported in the Mackenzie 

River area of northern Canada (McPhail and Lindsey 1970). Chinook salmon exhibit diverse 

and complex life history strategies. Healey (1986) described 16 age categories for Chinook 

salmon, 7 total ages with 3 possible freshwater ages. This level of complexity is roughly 

comparable to sockeye salmon, although sockeye salmon have a more extended freshwater 

residence period and use different freshwater habitats (Miller and Brannon 1982, Burgner 1991). 

Gilbert (1912) initially described two generalized freshwater life history types: “stream-type” 

Chinook salmon reside in freshwater for a year or more following emergence, whereas “oceantype” Chinook salmon migrate to the ocean predominantly within their first year. Healey (1983, 

1991) promoted the use of broader definitions for ocean type and stream type to describe two 

distinct races of Chinook salmon. This racial approach incorporates life history traits, 

geographic distribution, and genetic differentiation, and provides a valuable frame of reference 

for comparisons of Chinook salmon populations. For this reason, the BRTs have adopted the 

broader “racial” definitions of ocean and stream type for this review. 

Of the two life history types, ocean-type Chinook salmon exhibit the most varied and 

plastic life history trajectories. Ocean-type Chinook salmon juveniles emigrate to the ocean as 

fry, subyearling juveniles (during their first spring or fall), or as yearling juveniles (during their 

second spring), depending on environmental conditions. Ocean-type Chinook salmon also 

undertake distinct, coastally oriented, ocean migrations. The timing of the return to freshwater 

and spawning is closely related to the ecological characteristics of a population’s spawning 

habitat. Five different run times are expressed by different ocean-type Chinook salmon 

populations: spring, summer, fall, late-fall, and winter. In general, early run times (spring and 

summer) are exhibited by populations that use high spring flows to access headwater or interior 

regions. Ocean-type populations within a basin that express different run times appear to have 

evolved from a common source population. Stream-type populations appear to be nearly 

obligate yearling outmigrants (some 2-year-old smolts have been identified); they undertake 

extensive offshore ocean migrations and generally return to freshwater as spring- or summer-run 

fish. Stream-type populations are found in northern British Columbia, Alaska, and the headwater 

regions of the Fraser River and Columbia River interior tributaries. 

Prior to development of the ESU policy (Waples 1991), NMFS recognized Sacramento 

River winter-run Chinook salmon as a DPS under the ESA (NMFS 1987). Subsequently, in 

reviewing the biological and ecological information concerning West Coast Chinook salmon, 

BRTs have identified additional ESUs for Chinook salmon from Washington, Oregon, and 

California: 

27 
CHINOOK SALMON

Snake River fall-run Chinook salmon ESU (Waples et al. 1991a) 

Snake River spring- and summer-run Chinook salmon ESU (Matthews and Waples 1991) 

Upper Columbia River summer- and fall-run Chinook salmon ESU (originally the MidColumbia River summer- and fall-run Chinook salmon ESU, Waknitz et al. 1995) 

Puget Sound Chinook salmon ESU 

Washington Coast Chinook salmon ESU 

Lower Columbia River Chinook salmon ESU 

Upper Willamette River Chinook salmon ESU 

Middle Columbia River spring-run Chinook salmon ESU 

Upper Columbia River spring-run Chinook salmon ESU 

Oregon Coast Chinook salmon ESU 

Upper Klamath and Trinity rivers Chinook salmon ESU 

Central Valley fall- and late-fall-run Chinook salmon ESU 

Central Valley spring-run Chinook salmon ESU (Myers et al. 1998) 

Southern Oregon/Northern California Coasts Chinook salmon ESU 

California Coastal Chinook salmon ESU 

Deschutes River Chinook salmon ESU (NMFS 1999a) 

Of the 17 Chinook salmon ESUs NMFS identified, 8 are not listed under the ESA; 7 are listed as 

threatened (Snake River spring- and summer-run Chinook salmon, and Snake River fall-run 

Chinook salmon [NMFS 1992], Puget Sound Chinook salmon, Lower Columbia River Chinook 

salmon, and Upper Willamette River Chinook salmon [NMFS 1999a], Central Valley fall-run, 

and California Coastal Chinook salmon [NMFS 1999a]), and 2 are listed as endangered 

(Sacramento River winter-run Chinook salmon [NMFS 1994a] and Upper Columbia River 

spring-run Chinook salmon [NMFS 1999a]). 

NMFS convened a BRT to update the status of listed Chinook salmon ESUs in 

Washington, Oregon, California, and Idaho. The Chinook salmon BRT2 met in March and April 

2003 in Seattle, Washington, to review updated information on each ESU under consideration.

 

2 The BRT for the updated Chinook salmon status review included the following: from the NMFS Northwest 

Fisheries Science Center, Thomas Cooney, Dr. Robert Iwamoto, Dr. Robert Kope, Gene Matthews, Dr. Paul 

McElhany, Dr. James Myers, Dr. Mary Ruckelshaus, Dr. Thomas Wainwright, Dr. Robin Waples, and Dr. John 

Williams; from the NMFS Southwest Fisheries Science Center, Dr. Peter Adams, Dr. Eric Bjorkstedt, and Dr. 

Steve Lindley; from the NMFS Alaska Fisheries Science Center (Auke Bay Laboratory), Alex Wertheimer; and 

from the USGS Biological Resource Division, Dr. Reginald Reisenbichler. 

28 
4. Snake River Fall-Run 

Chinook Salmon ESU 

Snake River fall-run Chinook salmon enter the Columbia River in July and August. The 

Snake River component of the Chinook salmon fall run migrates past the lower Snake River 

mainstem dams from August through November. Spawning occurs from October through early 

December. Juveniles emerge from the gravels in March and April of the following year. Snake 

River fall-run Chinook salmon exhibit an ocean-type life history pattern, with juveniles 

migrating downstream from their natal spawning and rearing areas from June through early fall. 

Fall-run Chinook salmon returns to the Snake River generally declined through the first 

half of the 20th century (Irving and Bjornn 1981). In spite of the declines, the Snake River basin 

remained the largest single natural production area for fall-run Chinook salmon in the Columbia 

River drainage into the early 1960s (Fulton 1968). The construction of a series of Snake River 

mainstem dams significantly reduced spawning and rearing habitat for Snake River fall-run 

Chinook salmon. Historically, the primary fall-run Chinook salmon spawning areas were located 

on the upper mainstem Snake River. Currently, natural spawning is limited to the area from the 

upper end of Lower Granite Reservoir to Hells Canyon Dam, the lower reaches of the Imnaha, 

Grande Ronde, Clearwater, and Tucannon rivers, and small mainstem sections in the tailraces of 

the lower Snake River hydroelectric dams. 

Adult salmon counts at Snake River dams are an index of the annual return of Snake 

River fall-run Chinook salmon to spawning grounds. Lower Granite Dam is the uppermost of 

the mainstem Snake River dams that allow for passage of anadromous salmonids. Adult traps at 

Lower Granite Dam have allowed for sampling of the adult run as well as for removal of a 

portion of nonlocal hatchery fish prior to passage above the dam. The dam count at Lower 

Granite covers a majority of fall-run Chinook salmon returning to the Snake River basin. 

However, Snake River fall-run Chinook salmon do return to locations downstream of Lower 

Granite Dam and are therefore not included in the ladder count. Lyons Ferry Hatchery is located 

on the mainstem Snake River below both Little Goose and Lower Monumental dams. Although 

a fairly large proportion of adult returns from the Lyons Ferry Hatchery program do stray to 

Lower Granite Dam, a substantial proportion of the run returns directly to the facility. In 

addition, mainstem surveying efforts have identified relatively small numbers of fall-run 

Chinook salmon spawning in the tailraces of lower Snake River mainstem hydroelectric dams 

(Dauble et al. 1999). 

Lyons Ferry Hatchery was established as one of the hatchery programs under the Lower 

Snake Compensation Plan, administered through USFWS. Snake River fall-run Chinook salmon 

production is a major program for Lyons Ferry Hatchery, which is operated by the Washington 

Department of Fish and Wildlife (WDFW) and is located along the Snake River main stem 

between Little Goose Dam and Lower Monumental Dam. WDFW began developing a Snake 

29 
CHINOOK SALMON

River fall-run Chinook salmon broodstock in the early 1970s through a trapping program at Ice 

Harbor and Lower Granite dams. The Lyons Ferry facility became operational in the mid-1980s 

and took over incubation and rearing for the Snake River fall-run Chinook mitigation and 

compensation program. 

Summary of Previous BRT Conclusions 

Previous Chinook salmon status reviews (Waples et al. 1991b, Myers et al. 1998) 

identified several concerns regarding Snake River fall-run Chinook salmon: steady and severe 

decline in abundance since the early 1970s, loss of primary spawning and rearing areas upstream 

of the Hells Canyon Dam complex, increase in nonlocal hatchery contribution to adult 

escapement over Lower Granite Dam, and relatively high aggregate harvest impacts by ocean 

and in-river fisheries. 

Listing status: Threatened. 

New Data and Updated Analyses 

The Lyons Ferry Hatchery Snake River fall-run Chinook salmon broodstock has been 

used to supply a major natural spawning supplementation effort in recent years (Bugert and 

Hopley 1989, Bugert et al. 1995). Facilities adjacent to major natural spawning areas have been 

used to acclimate release groups of yearling smolts. Additional releases of subyearlings have 

been made in the vicinity of the acclimation sites. The level of subyearling releases depends on 

the availability of sufficient broodstock to maintain the on-station program and the off-station 

yearling releases (Table 2). Returns in 2000 and 2001 reflect increases in the level of off-station 

plants and relatively high marine survival rates. 

Abundance 

The 1999 NMFS status review update noted increases in the Lower Granite Dam counts 

in the mid-1990s (Figure 3), and the upward trend in returns has continued. The 2001 count over 

Lower Granite Dam exceeded 8,700 adult fall-run Chinook salmon. The 1997 through 2001 

escapements were the highest on record since the count of 1,000 in 1975. Returns of naturally 

produced Chinook salmon and increased hatchery returns from the Lyons Ferry Hatchery (onstation releases and supplementation program) account for the increase in escapements over 

Lower Granite Dam (Table 3).

Returns classified as natural origin exceeded 2,600 in 2001. The 1997–2001 geometric 

mean natural-origin count over Lower Granite Dam was 871 fish, approximately 35% of the 

delisting abundance criteria proposed for this run (2,500 natural-origin spawners averaged over 

an 8-year period). The largest increase in fall-run Chinook salmon returns to the Snake River 

spawning area was from the Lyons Ferry Hatchery–Snake River stock component. Returns 

increased from under 200 per year prior to 1998 to over 1,200 and 5,300 adults in 2000 and 

2001, respectively. The increase includes returns from the on-station release program as well as 

returns from large supplementation releases above Lower Granite Dam. Smolt releases from the 

30 
4. SNAKE RIVER FALL-RUN CHINOOK SALMON ESU 

Table 2. Escapement and stock composition of fall-run Chinook salmon at Lower Granite Dam, 

1975–2001. Source: Stock composition is based on marked recoveries from Lower Granite Dam 

adult trapping (Yuen 2002).

Stock composition of Lower Granite Dam 

escapement*

Run 

year 

Lower 

Granite 

Dam count 

Marked fish 

to Lyons 

Ferry 

Hatchery 

Lower 

Granite Dam 

escapement 

Natural 

origin 

Hatchery 

origin 

(Snake 

River) 

Hatchery 

origin 

(non–Snake 

River) 

1975 1,000 – 1,000 1,000 – – 

1976 470 – 470 470 – – 

1977 600 – 600 600 – – 

1978 640 – 640 640 – – 

1979 500 – 500 500 – – 

1980 450 – 450 450 – – 

1981 340 – 340 340 – – 

1982 720 – 720 720 – – 

1983 540 – 540 428 112 – 

1984 640 – 640 324 310 6 

1985 691 – 691 438 241 12 

1986 784 – 784 449 325 10 

1987 951 – 951 253 644 54 

1988 627 – 627 368 201 58 

1989 706 – 706 295 206 205 

1990 385 50 335 78 174 83 

1991 630 40 590 318 202 70 

1992 855 187 668 549 100 19 

1993 1,170 218 952 742 43 167 

1994 791 185 606 406 20 180 

1995 1,067 430 637 350 1 286 

1996 1,308 389 919 639 74 206 

1997 1,451 444 1007 797 20 190 

1998 1,909 947 962 306 479 177 

1999 3,381 1,519 1,862 905 879 78 

2000 3,830 1,372 2,458 857 1,278 323 

2001 10,782 2,064 8,718 2,652 5,330 736 

*

 Returning adults produced from naturally spawning parents (regardless of the origin of the parents) are classified 

as natural origin. 

31 
Table 3. Fall-run Chinook salmon hatchery releasesa into the Snake River basin, 1985–2001. Source: The 1994–2001 data 

(2003); 1985–1993 release data are from the Fish Passage Center Hatchery database (NWPPC 2003). 

Acclimation sites 

Lyons Ferry (direct) Pittsburg Landing Capt. John 

Big Canyon 

(Clearwater River) 

Release year Yearlingb

Subyearling Yearlingb Sub- yearlingc Yearlingb Sub- yearlingc Yearlingb Sub- yearlingc 

1985 650,300 539,392 – – – – – – 1986 481,950 1,789,566 – – – – – – 1987 386,600 1,012,500 – – – – – – 1988 407,500 4,563,500 – – – – – – 1989 413,017 1,710,865 – – – – – – 1990 436,354 3,043,756 – – – – – – 1991 224,439 – – – – – – – 1992 689,601 – – – – – – – 1993 206,775 – – – – – – – 1994 603,661 – – – – – – – 1995 349,124 – – – – – – – 1996 407,503 – 114,299 – – – – – 1997 456,872 – 147,316 – – – 199,399 252,705 1998 419,002 – 141,814 – 133,205 – 61,172 – 1999 432,166 204,194 142,885 – 157,010 – 229,608 347,105 2000 456,401 196,643 134,709 400,156 131,186 892,847 131,306 890,474 2001 338,757 199,976 103,741 374,070 101,976 501,129 113,215 856,968 

a All releases are from Lyons Ferry Hatchery–origin broodstock. Hells Canyon Dam releases increased to 500,000 in 2002. b On-station releases and acclimation site yearling releases are marked or tagged. c Acclimation site subyearling releases are generally unmarked. 

32 
4. SNAKE RIVER FALL-RUN CHINOOK SALMON ESU 

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total Natural origin

Figure 3. Estimated spawning escapement of fall-run Chinook salmon at Lower Granite Dam, 

1975–2001. 

acclimation sites above Lower Granite Dam were marked. In recent years, large numbers of 

unmarked subyearling Lyons Ferry Hatchery fall-run Chinook have been released from the 

acclimation sites. These fish will contribute to adult returns over Lower Granite Dam, 

complicating the estimation of natural production rates (WDFW 2003). Escapement over Lower 

Granite Dam represents the majority of Snake River fall-run Chinook salmon returns. In 

addition, Snake River fall-run Chinook salmon returns to the Tucannon River system (≤100 

spawners per year based on redd counts) and to Lyons Ferry Hatchery (recent average returns to 

the facility have been approximately 1,100 fish per year). Small numbers of fall-run Chinook 

salmon redds have also been reported in tailrace areas below the mainstem Snake River dams 

(Dauble et al. 1999). 

Productivity 

Both the long- and short-term trends in total returns are positive (1.05, 1.22). The shortterm (1990–2001) estimates of the median population growth rate (λ) are 0.98, assuming a 

hatchery-spawning effectiveness of 1.0 (equivalent to that of wild spawners), and 1.137 with an 

assumed hatchery-spawning effectiveness of 0. The estimated long-term growth rate for the 

Snake River fall-run Chinook salmon population is strongly influenced by the hatcheryeffectiveness assumption. If hatchery spawners have been equally effective as natural-origin 

spawners in contributing to broodyear returns, the long-term λ estimate is 0.899, and the 

associated probability that λ is less than 1.0 is estimated as 99%. If hatchery returns over Lower 

Granite Dam are not contributing at all to natural production (hatchery effectiveness of 0.0), the 

long-term estimate of λ is 1.024. The associated probability that λ is less than 1.0 is 0.26. 

Broodyear returns-per-spawner estimates were low for 3 or more consecutive years in the 

mid-1980s and the early 1990s (Figure 4). The large increase in natural abundance in 2000 

33
CHINOOK SALMON

0.1

1.0

10.0

100.0

1970 1975 1980 1985 1990 1995 2000

Broodyear

Returns per spawner

Total Natural origin

Figure 4. Returns per spawner plotted against broodyear escapements for Snake River fall-run Chinook 

salmon, 1975–1997 (escapement estimates are from Lower Granite Dam counts, assuming a 10% 

prespawning mortality). Broodyear returns are estimated by applying sample age-at-return 

estimates to annual dam counts. 

and 2001 is reflected in the 1996 and 1997 return-per-spawner estimates (1997 returns per 

spawner is based on 4-year-old component only). 

Harvest Impacts 

Due to their patters of ocean distribution and the timing of their spawning run up the 

Columbia River, Snake River fall-run Chinook salmon are subject to harvest in a wide range of 

fisheries. Coded-wire tag studies using Lyons Ferry Hatchery fish of Snake River origin indicate 

that Snake River fall-run Chinook salmon have a broad distribution. Coastal fisheries in 

California, Oregon, Washington, British Columbia, and southeast Alaska have reported 

recoveries of tagged fish from the Snake River. The timing of the return and upriver spawning 

migration of Snake River fall-run Chinook salmon overlaps the Hanford Reach upriver bright 

Chinook salmon returns, as well as several large hatchery runs returning to lower river release 

areas or to the major hatcheries adjacent to the lower mainstem Columbia River. 

Harvest impacts on Snake River fall-run Chinook salmon declined after listing and have 

remained relatively constant at approximately 35–40% in recent years (Figure 5). The decline 

and subsequent listing of Snake River fall-run Chinook salmon prompted major restrictions on 

U.S. fisheries impacting this stock. In-river gillnet and sport fisheries are “shaped” in time and 

space to maximize the catch of harvestable hatchery and natural (Hanford Reach) stocks while 

minimizing impacts on the intermingled Snake River fall-run Chinook salmon. Reductions in 

ocean fishery impacts on Snake River fall-run Chinook salmon resulted from management 

measures designed to protect weakened or declining stocks specific to each set of fisheries. 

34
4. SNAKE RIVER FALL-RUN CHINOOK SALMON ESU 

0

0.2

0.4

0.6

0.8

1

1970 1975 1980 1985 1990 1995 2000 2005

Run year

Exploitation rate index

Figure 5. Aggregate (ocean and in-river fisheries) exploitation rate index for Snake River fall-run 

Chinook salmon, 1975–2001. Source: Data from Marmorek et al. (1998); 1998–2001 data from 

Columbia River Technical Advisory Committee database.3

Mainstem Hydropower Impacts 

Migration conditions for subyearling Chinook salmon from the Snake River have 

generally improved since the early 1990s (FCRPS 2000). The lack of baseline data prior to the 

mid-1990s precludes quantifying the changes. 

Habitat 

There have been no major changes in available habitat for Snake River fall-run Chinook 

salmon since the previous status review. 

New Hatchery Information 

Sampling marked returns determines the composition of the fall Chinook salmon run at 

Lower Granite Dam. Since the early 1980s, the run has consisted of three major components: 

unmarked returns of natural origin, marked returns from the Lyons Ferry Hatchery program, and 

strays from hatchery programs outside of the mainstem Snake River (Table 3). Although all 

three components of the fall run have increased in recent years, returns of Snake River–origin 

Chinook salmon have increased disproportionately to outside hatchery strays. Prior to the 

1998–1999 status reviews, the 5-year average contribution of outside stocks to the escapement 

over Lower Granite Dam exceeded 26.2%. The most recent 5-year average (1997–2001) was 

12.4%, with the contribution in 2001 being just over 8%. The drop in relative contribution by 

outside stocks reflects the disproportionate increase in returns of the Lyons Ferry Hatchery 

 

3

H. Yuen, U.S. Fish and Wildlife Service, Vancouver, WA. Pers. commun., December 2002. 

35
CHINOOK SALMON

component, the systematic removal of marked hatchery fish at the Lower Granite Dam trap, and 

modifications to the Umatilla program to increase homing of fall-run Chinook salmon release 

groups intended to return to the Umatilla River. 

The primary contributor of non-ESU strays to Lower Granite Dam continues to be 

releases from the Umatilla fall-run Chinook salmon program (Priest Rapids stock). In addition, 

low numbers of returns from releases into the Klickitat River have been consistently detected at 

the Lower Granite Dam adult trap. In 2000–2002, two or three adult Chinook salmon with 

Klickitat Hatchery coded-wire tags were detected in each sampling year (Milks et al. 2003). 

Recoveries of Umatilla-origin adult tags at the Lower Granite Dam trap ranged from 43 to 166 

for the same 3-year period (Milks et al. 2003). 

One of the concerns leading to the listing of Snake River fall-run Chinook salmon under 

the ESA was the possibility of significant introgression due to increased straying by outside 

stocks into the natural spawning areas above Lower Granite Dam. Removal of all outside-origin 

stock at Lower Granite Dam is not feasible—the trapping operation does not handle 100% of the 

run at the dam, and outside stocks are generally not 100% marked. A genetic analysis of 

outmigrant smolts produced from spawning above Lower Granite Dam was conducted to 

evaluate the potential for introgression of outside stocks. Marshall et al. (2000) concluded that 

distinctive patterns of allelic diversity persisted in the stock, indicating that the natural Snake 

River Chinook salmon fall run remains a distinct resource. 

Categorizations of Snake River fall-run Chinook salmon hatchery stocks (SSHAG 2003) 

can be found in Appendix A, Table A-1.

36
5. Snake River Spring/Summer-Run 

Chinook Salmon ESU 

NMFS classified spring- and summer-run Chinook salmon returning to the major 

tributaries of the Snake River as an ESU (Matthews and Waples 1991). This ESU includes 

production areas characterized by spring- and summer-timed returns, and combinations from the 

two adult timing patterns. Runs classified as spring-run Chinook salmon are counted at 

Bonneville Dam beginning in early March and ending the first week of June; runs classified as 

summer-run Chinook salmon return to the Columbia River from June through August. 

Returning fish hold in deep mainstem and tributary pools until late summer, when they emigrate 

up into tributary areas and spawn. In general, spring-run type Chinook salmon tend to spawn in 

higher-elevation reaches of major Snake River tributaries in mid- through late August, and 

summer-run Snake River Chinook salmon spawn approximately one month later than spring-run 

fish. Summer-run Chinook salmon tend to spawn lower in the Snake River drainages, although 

their spawning areas often overlap with spring-run spawners. 

Many of the Snake River tributaries spring/summer-run Chinook salmon use exhibit two 

major features: extensive meanders through high-elevation meadowlands and relatively steep 

lower sections joining the drainages to the mainstem Salmon River (Matthews and Waples 

1991). The combination of relatively high summer temperatures and the upland meadow habitat 

creates the potential for juvenile salmonid high productivity. Historically, the Salmon River 

system may have supported more than 40% of the total return of spring/summer-run Chinook 

salmon to the Columbia River system (e.g., Fulton 1968). 

The Snake River spring/summer-run Chinook salmon ESU includes current runs to the 

Tucannon River, the Grande Ronde River system, the Imnaha River, and the Salmon River 

(Matthews and Waples 1991). The Salmon River system contains a range of habitats used by 

spring- and summer-run Chinook salmon. The South Fork and Middle Fork Salmon River 

currently support the bulk of natural production in the drainage. Two large tributaries entering 

above the confluence of the Middle Fork Salmon River, the Lemhi and Pahsimeroi rivers, drain 

broad alluvial valleys and are believed to have historically supported substantial, relatively 

productive anadromous fish runs. Returns into the upper Salmon River tributaries were 

reestablished following the opening of passage around Sunbeam Dam on the mainstem Salmon 

River downstream of Stanley, Idaho. Sunbeam Dam in the upper Salmon River was a serious 

impediment to migration of anadromous fish and may have been a complete block in at least 

some years before its partial removal in 1934 (Waples et al. 1991b). 

Current runs returning to the Clearwater River drainages were not included in the Snake 

River spring/summer-run Chinook salmon ESU. Lewiston Dam in the lower main stem of the 

Clearwater River was constructed in 1927 and functioned as an anadromous block until the early 

1940s (Matthews and Waples 1991). Spring and summer Chinook salmon runs were 

reintroduced into the Clearwater system via hatchery outplants beginning in the late 1940s. As a 

37 
CHINOOK SALMON

result, Matthews and Waples (1991) concluded that even if a few native salmon survived the 

hydropower dams, “the massive outplantings of nonindigenous stocks presumably substantially 

altered, if not eliminated, the original gene pool.” 

Spring/summer-run Chinook salmon from the Snake River basin exhibit stream-type life 

history characteristics (Healey 1983). Eggs are deposited in late summer and early fall, incubate 

over the following winter, and hatch in late winter and early spring of the following year. 

Juveniles rear through the summer, overwinter, and migrate to sea in the spring of their second 

year of life. Depending on the tributary and the specific habitat conditions, juveniles may 

migrate extensively from natal reaches into alternative summer-rearing or overwintering areas. 

Snake River spring/summer-run Chinook salmon return from the ocean to spawn primarily as 4- 

and 5-year-old fish, after 2 to 3 years in the ocean. A small fraction of the fish return as 3-yearold “jacks,” heavily predominated by males. 

Summary of Previous BRT Conclusions 

The 1991 ESA status review (Matthews and Waples 1991) of the Snake River spring/ 

summer-run Chinook salmon ESU concluded that the ESU was at risk. Aggregate abundance of 

naturally produced Snake River spring and summer Chinook salmon runs had dropped to a small 

fraction of historical levels. Short-term projections (including jack counts and habitat/flow 

conditions in the broodyears producing the next generation of returns) were for a continued 

downward trend in abundance. Risk modeling indicated that if the historical trend in abundance 

continued, the ESU as a whole was at risk of extinction within 100 years. The review identified 

related concerns at the population level within the ESU. Given the large number of potential 

production areas in the Snake River basin and the low levels of annual abundance, risks to 

individual subpopulations may be greater than the extinction risk for the ESU as a whole. The 

1998 Chinook salmon status review (Myers et al. 1998) summarized and updated these concerns. 

Both short- and long-term abundance trends had continued downward. The report identified 

continuing disruption due to the impact of mainstem hydroelectric development, including 

altered flow regimes and impacts on estuarine habitats. The 1998 review also identified regional 

habitat degradation and risks associated with the use of outside hatchery stocks in particular 

areas—specifically including major sections of the Grande Ronde River basin. 

Direct estimates of annual runs of historical spring/summer-run Chinook salmon to the 

Snake River are not available. Chapman (1986) estimated that the Columbia River produced 2.5 

million to 3.0 million spring/summer-run Chinook salmon per year in the late 1800s. Total 

spring/summer-run Chinook salmon production from the Snake River basin contributed a 

substantial proportion of those returns; the total annual production of Snake River 

spring/summer-run Chinook salmon may have been in excess of 1.5 million adult returns per 

year (Matthews and Waples 1991). Returns to Snake River tributaries had dropped to roughly 

100,000 adults per year by the late 1960s (Fulton 1968). Increasing hatchery production 

contributed to subsequent years’ returns, masking a continued decline in natural production. 

Listing status: Threatened. 

38 
5. SNAKE RIVER SPRING/SUMMER-RUN CHINOOK SALMON ESU 

New Data and Updated Analyses 

Abundance 

Aggregate returns of spring-run Chinook salmon (as measured at Lower Granite Dam) 

showed a large increase over recent year abundances (Figure 6). The 1997–2001 geometric 

mean return of natural-origin Chinook salmon exceeded 3,700. The increase was largely driven 

by the 2001 return—estimated to have exceeded 17,000 naturally produced spring-run Chinook 

salmon—however, a large proportion of the run in 2001 was estimated to be of hatchery origin 

(88%). The summer run over Lower Granite Dam has increased as well (Figure 7). The 

1997–2001 geometric mean total return was slightly more than 6,000. The geometric mean 

return for the broodyears for recent returns (1987–1996) was 3,076. (Note: This figure does not 

address hatchery versus wild breakdowns of the aggregate run.) 

Returns in other production areas are shown in Figures 8–21 and summarized in Table 4. 

The lowest 5-year geometric mean returns for almost all individual Snake River spring/summerrun Chinook salmon production areas were in the 1990s. Sulphur Creek and Poverty Flat 

production areas had low 5-year geometric mean returns in the early 1980s. Many, but not all, 

production areas had large increases in return year 2001. Recent return levels are also compared 

against interim delisting criteria (abundance) for those production areas with designated levels 

(Table 4). The Snake River Salmon Recovery Team (Bevan et al. 1994) suggested the interim 

abundance criteria, and in some cases it was developed for use in analyses supporting the Federal 

Columbia River Power System biological opinions. 

0

20000

40000

60000

80000

100000

120000

140000

160000

1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total Natural origin 

Figure 6. Snake River spring-run Chinook salmon escapement over Lower Granite Dam, 1979–2001. 

39 
CHINOOK SALMON

0

200

400

600

800

1000

1200

1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total Natural origin

Figure 7. Snake River summer-run Chinook salmon escapement, 1979–2002. 

0

200

400

600

800

1000

1200

1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total Natural origin

Figure 8. Tucannon River spring-run Chinook salmon spawning escapement, 1979–2001. Estimates are 

based on trap counts and expanded redd estimates. See Appendix A, Table A-2 for abundance 

source information. 

40 
5. SNAKE RIVER SPRING/SUMMER-RUN CHINOOK SALMON ESU 

0

500

1000

1500

2000

2500

1960 1965 1970 1975 1980 1985 1990 1995 2000

Year

Abundance

Total Natural origin

Figure 9. Wenaha River spring-run Chinook spawning escapement, 1964–1996. Estimates are expanded 

from redd counts. 

Productivity 

Long-term trend and λ estimates were less than 1 for all natural production data sets, 

reflecting the large declines since the 1960s. Short-term trends and λ estimates were generally 

positive, with relatively large confidence intervals (Table 4 and Figure 22). Grande Ronde and 

Imnaha data sets had the highest short-term growth rate estimates. Tucannon River, Poverty Flat 

(2000 and 2001 not included), and Sulphur Creek index areas had the lowest short-term λ

estimates in the series. Patterns in returns per spawner for stocks with complete age information 

(e.g., Minam River) show a series of extremely low return rates in the 1990s, followed by 

increases in the 1995–1997 broodyears (Figure 23). 

Hydropower Impacts 

Snake River spring/summer-run Chinook salmon must migrate past a series of mainstem 

Snake and Columbia river hydroelectric dams to and from the ocean. The Tucannon River 

population must migrate through six dams; all other major Snake River drainages supporting 

spring/summer-run Chinook salmon production are above eight dams. Earlier status reviews 

concluded that mainstem Columbia and Snake river hydroelectric projects have resulted in major 

disruption of migration corridors and have affected flow regimes and estuarine habitat. 

41 
Table 4. Summary of abundance and trend information for Snake River spring/summer-run Chinook salmon ESU relative 

review analyses. 

Recent 5-year geometric meana

Total Natural 

Short-term trend 

(percent/year) 

Populations 

Percent 

natural 

origin 

(previous) Mean (range) Current Previous Current Previous 

Tucannon River 24 303 (128–1,012) 80 190 –4.1 –11.0 Wenaha Riverd 36 225 (67–586) 82 – –9.4 –23.6 

Wallowa River 95 0.57 redds (0.0–29.0) – – +11.5 – Lostine River 95 34 redds (9–131) – – +12.7 – Minam River 95 180 (96–573) 172 69 +3.3 –14.5 

Catherine Creekd 44 50 (13–262) 22 45 –25.1 –22.5 

Upper Grande Ronde 

Riverd

42 46 (3–336) 20 – –9.4 – 

South Fork Salmon River 91 496 redds (277–679) – – +1.1 -13.6 Secesh River 96 144 redds (38–444) – – +9.8 – Johnson Creek 100 131 redds (49–444)e – – –1.5 – 

Big Creek spring run 100 53 (21–296) 53 – +5.4 –34.2 Big Creek summer run ? 5 redds (2–58) – – +1.7 –27.9 Loon Creek 100 27 redds (6–255) – – +12.2 – Marsh Creek 100 53 (0–164) 53 – –4.0 – Bear Valley/Elk Creek 100 266 (72–712) 266 – +6.2 – North Fork Salmon Rivere ? 5.6 redds (2.0–19.0) – – – – 

Lemhi River 100 72 redds (35–216) – – +12.8 –27.4 Pahsimeroi River ? 161 (72–1,097) – – +12.8 – East Fork Salmon spring 

runf

? 0.27 rpmg (0.2–1.41) 

– – 

–5.7 

– 

East Fork Salmon summer 

run 

100 1.22 rpmg (0.35–5.32) – – +0.9 –32.9 

Yankee Fork spring runf ? 0.0 rpmg (0.0–0.0) – – –6.3 – 

Yankee Fork summer run 100 2.9 redds (1.0–18.0) – – +4.1 – Valley Creek spring run 100 7.4 redds (2.0–28.0) – – +14.9 –25.9 Valley Creek summer runh ? 2.14 rpmg (0.71–9.29) – – +5.8 –29.3 

Upper Salmon spring run ? 69 redds (25–357) – – +5.3 – 

42 
Table 4 continued. Summary of abundance and trend information for Snake River spring/summer-run Chinook salmon ES

BRT status review analyses. 

Recent 5-year geometric meana

Total Natural 

Short-term trend 

(percent/year) 

Populations 

Percent 

natural 

origin 

(previous) Mean (range) Current Previous Current Previous 

Upper Salmon summer runf ? 0.24 rpmg (0.07–0.58) – – –3.3 – Alturas Lake Creek ? 2.7 redds (0–18) – – +10.2 – Imnaha River 38 564 redds (194–3,041)i – 216 +12.8 –24.1 

Big Sheep Creek 3 0.25 redds (0.0–1.0) – – +0.8 – Lick Creek 41 1.4 redds (0.0–29.0) – – +11.7 – 

a Five-year geometric means calculated using years 1997–2001 unless otherwise noted. Previous natural geomean for 1987–1996 periob Interim targets from Ford et al. (2001), Lohn (2002). c Comparison of current (recent 5-year geometric mean) to interim target only for those production areas with estimated spawners and c

target. 

d Five-year geometric mean calculated using years 1992–1996. e Five-year geometric mean calculated using years 1996–2000. f Five-year geometric mean calculated using years 1993–1997. g rpm = redds per mile. h Five-year geometric mean calculated using years 1997, 2000, and 2001 only. i Expanded redds. 

43 
CHINOOK SALMON

Harvest 

Harvest impacts on Snake River spring-run Chinook salmon are generally low. Ocean 

harvest rates are also low. Historical harvest estimates reflect the impact of mainstem and 

tributary in-river fisheries. In response to initial declines in returns, in-river harvests of both 

spring- and summer-run Chinook salmon were restricted beginning in the early 1970s (Matthews 

and Waples 1991). 

Fishery impacts were further reduced following ESA listing in 1991, with lower harvest 

rates from 1991 to 1999. In response to the large increase in returns of spring-run Chinook 

salmon, additional impacts were allowed beginning in 2000. The management agreement 

providing for increased impacts as a function of abundance also calls for additional reductions if 

and when runs drop below prescribed thresholds.4

Habitat 

Tributary habitat conditions vary widely among the various drainages of the Snake River 

basin. Habitat is degraded in many areas of the basin, reflecting the impacts of forest, grazing, 

and mining practices. Impacts relative to anadromous fish include lack of pools, higher water 

temperatures, low water flows, poor overwintering conditions, and high sediment loads. 

Substantial portions of the Salmon River drainage, particularly in the middle fork, are protected 

in wilderness areas. 

New Hatchery Information 

Spring/summer-run Chinook salmon are produced from a number of artificial production 

facilities in the Snake River basin (Table 5). Much of the production was initiated under the 

Lower Snake River Compensation Plan. Lyons Ferry Hatchery serves as a rearing station for 

Tucannon River spring-run Chinook salmon broodstock. Rapid River Hatchery and McCall 

Hatchery provide rearing support for a regionally derived summer-run Chinook salmon 

broodstock released into lower Salmon River areas. Two major hatchery programs have 

operated in the upper Salmon Basin—the Pahsimeroi and Sawtooth facilities. Since the mid1990s, small-scale natural stock supplementation studies and captive breeding efforts have been 

initiated in the Snake River basin. 

Historically, releases from broodstock originating outside the basin constituted a 

relatively small fraction of the total release into the basin. The 1998 Chinook salmon status 

review (Myers et al. 1998) identified concerns regarding the use of the Rapid River Hatchery 

stock reared at Lookingglass Hatchery in the Grande Ronde River basin. The Rapid River 

Hatchery stock was originally developed from broodstock collected from the spring-run Chinook 

salmon returns to historical production areas above the Hells Canyon Dam complex. 

 

4 Order approving interim management agreement for upriver spring Chinook, summer Chinook, and sockeye. 

Approved 5 April 2001. United States v. Oregon Technical Advisory Committee, Civil 68-513. 

44 
5. SNAKE RIVER SPRING/SUMMER-RUN CHINOOK SALMON ESU 

Use of the Rapid River Hatchery stock in Grande Ronde drainage hatchery programs has 

been actively phased out since the late 1990s. In addition, a substantial proportion of marked 

returns of Rapid River Hatchery stock released in the Grande Ronde River have been intercepted 

and removed at the Lower Granite Dam ladder and at some tributary-level weirs. Carcass survey 

data indicate significant declines in hatchery contributions to natural spawning in areas 

previously subject to Rapid River Hatchery stock strays. 

Concerns for the high incidence of bacterial kidney disease (BKD) in Snake River basin 

hatchery facilities were also identified (Myers et al. 1998). Categorization of Snake River 

spring/summer-run Chinook salmon hatchery stocks (SSHAG 2003) can be found in Appendix 

A, Table A-1. 

Table 5. Total hatchery releases of spring/summer-run Chinook salmon into the Snake River basin, by 

stock and release site. Source: Information from Fish Passage Center (NWPPC 2003) smolt 

release database.

Average releases per year 

Basin Stock 1985–1989 1990–1994 1995–2001 

Rapid River 405,192 445,411 146,728 

Leavenworth 32,857 – – 

Lookingglass – – 20,622 

Mixed – – 29,369 

Mainstem Snake River 

Mainstem Total 438,049 445,411 196,719 

Carson 784,785 100,934 – 

Imnaha River 24,700 – – 

Lookingglass 396,934 – – 

Rapid River 452,786 642,605 239,756 

Mainstem Grande Ronde River 

Grande Ronde River – – 581 

Carson 60,893 – – 

Rapid River – 14,000 – 

Catherine Creek 7,552 – 24,973 

Catherine Creek 

Lookingglass 153,420 – – 

Carson 70,529 – – 

Lookingglass 55,120 – – 

Lostine River – – 25,847 

Rapid River – 28,863 – 

Wallowa River 

Grande Ronde Total 2,006,718 786,401 291,158 

Little Salmon River Rapid River 2,374,325 2,631,741 1,552,835 

South Fork Salmon River South Fork Salmon River 929,351 1,020,393 888,469 

Pahsimeroi River Pahsimeroi River 418,160 479,382 74,934 

Salmon River 55,809 – 40,444 

East Fork Salmon River Salmon River 182,598 147,614 6,222 

Upper Salmon River Pahsimeroi River 145,100 – – 

Rapid River 10,020 20,000 – 

Salmon River 1,220,188 1,091,576 96,877 

Salmon River Total 5,335,551 5,390,706 2,656,782 

Imnaha River Imnaha River 98,425 339,928 269,886 

ESU Total All stocks 7,942,476 7,071,402 3,511,286 

45 
CHINOOK SALMON

0

100

200

300

400

500

600

700

800

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total Natural origin

Figure 10. Minam River Chinook salmon spawning escapements, 1964–2001. Estimates are based on 

expanded redd counts and carcass sampling. See Appendix A, Table A-2 for abundance source 

information. 

0

20

40

60

80

100

120

140

160

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total Natural origin

Figure 11. Lostine River spring-run Chinook salmon total counts, 1964–2001. Estimates are based on 

redd count expansions and carcass sampling. See Appendix A, Table A-2 for abundance source 

information. 

46 
5. SNAKE RIVER SPRING/SUMMER-RUN CHINOOK SALMON ESU 

0

50

100

150

200

250

300

350

1955 1965 1975 1985 1995 2005

Year

Redd count

Total Natural origin

Figure 12. Upper Grande Ronde River spring-run Chinook salmon redd counts, 1960–2001. Hatchery 

contributions are based on carcass sampling. See Appendix A, Table A-2 for abundance source 

information. 

0

500

1000

1500

2000

2500

3000

3500

4000

1950 1960 1970 1980 1990 2000

Year

Abundance

Total Natural origin

Figure 13. Imnaha River spring-run Chinook salmon spawning escapement, 1953–2001. Estimates are 

based on expanded redd counts and carcass sampling. See Appendix A, Table A-2 for abundance 

source information. 

47 
CHINOOK SALMON

0

500

1000

1500

2000

2500

3000

3500

4000

1955 1965 1975 1985 1995 2005

Year

Abundance

Total Natural origin

Figure 14. Poverty Flat summer-run Chinook salmon spawning escapement, 1957–2001. Estimates are 

based on redd count expansions. See Appendix A, Table A-2 for abundance source information. 

0

200

400

600

800

1000

1200

1955 1965 1975 1985 1995 2005

Year

Abundance

Total Natural origin

Figure 15. Johnson Creek summer-run Chinook salmon spawning escapement, 1957–2001. Estimates 

are based on expanded redd counts. See Appendix A, Table A-2 for abundance source 

information. 

48 
5. SNAKE RIVER SPRING/SUMMER-RUN CHINOOK SALMON ESU 

0

100

200

300

400

500

600

700

800

900

1955 1965 1975 1985 1995 2005

Year

Abundance

Total Natural origin

Figure 16. Sulphur Creek spring-run Chinook salmon spawning escapement, 1957–2001. Estimates are 

based on expanded redd counts and carcass surveys. See Appendix A, Table A-2 for abundance 

source information. 

0

500

1000

1500

2000

2500

1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total Natural origin

Figure 17. Bear Valley/Elk Creek spring-run Chinook spawning escapement, 1966–2001. Estimates are 

based on expanded redd counts and carcass surveys. See Appendix A, Table A-2 for abundance 

source information. 

49 
CHINOOK SALMON

0

200

400

600

800

1000

1200

1400

1955 1965 1975 1985 1995 2005

Year

Abundance

Total Natural origin

Figure 18. Marsh Creek spring-run Chinook salmon spawning escapement, 1957–2001. Estimates are 

based on expanded redd counts and carcass sampling. See Appendix A, Table A-2 for abundance 

source information. 

0

200

400

600

800

1000

1200

1400

1600

1800

2000

1955 1965 1975 1985 1995 2005

Year

Redds

Total

Figure 19. Total redd count in the Lemhi River (includes hatchery and natural returns), 1957–2001. 

50 
5. SNAKE RIVER SPRING/SUMMER-RUN CHINOOK SALMON ESU 

0

50

100

150

200

250

300

350

1955 1965 1975 1985 1995 2005

Year

Redd count

Total

Figure 20. Upper Valley Creek spring-run Chinook salmon redd counts, 1957–2001. 

0

5

10

15

20

25

30

35

40

45

1955 1965 1975 1985 1995 2005

Year

Redds per mile

Total

Figure 21. East Fork Salmon River summer-run Chinook salmon redds per mile, 1957–2001. 

51 
CHINOOK SALMON

0.5

0.7

0.9

1.1

1.3

1.5

1.7

1.9

2.1

Tucannon (H0) Tucannon (H1)

Minam (H0) Minam (H1)

Lostine

Wenaha (H0) Wenaha (H1)

Catherine (H0) Catherine (H1)

Upper (H0)

Imnaha (H0) Imnaha (H1)

Lick Creek (H0) Lick Creek (H1)

Poverty Flats

Secesh (H0) Secesh (H1)

South ForkSouth Fork

Johnson

Big Camas Loon Sulphur Bear Valley Marsh

Lemhi

East Fork

Valley Creek Yankee Fork

Annual Rate of Change

Figure 22. Short-term median growth rate (1990–2001) for total spawners for Snake River 

spring/summer-run production areas. Error bars represent 95% confidence limits of the trend. 

H0 = hatchery-origin spawners are assumed to have zero reproductive success. H1 = hatcheryorigin spawners are assumed to have the same reproductive success as natural-origin fish. 

0.01

0.1

1

10

100

1960 1965 1970 1975 1980 1985 1990 1995 2000

Broodyear

Returns per spawner

Figure 23. Spring/summer-run Chinook salmon returns per spawner for the Minam River, 1964–1997, 

calculated as estimated natural returns to the spawning grounds divided by broodyear total 

spawners. 

52 
6. Upper Columbia River Spring-Run 

Chinook Salmon ESU 

There are no estimates of historical abundance specific to the Upper Columbia River 

spring-run Chinook salmon ESU prior to the 1930s. The drainages supporting this ESU are all 

above Rock Island Dam on the upper Columbia River. Rock Island Dam is the oldest major 

hydroelectric project on the Columbia River; it began operations in 1933. Counts of returning 

Chinook salmon have been made since the 1930s. Annual estimates of the aggregate return of 

spring-run Chinook salmon to the upper Columbia River are derived from the dam counts, based 

on the nadir between spring and summer return peaks. Spring-run Chinook salmon currently spawn 

in three major drainages above Rock Island Dam—the Wenatchee, Methow, and Entiat rivers. 

Annual counts of spawning redds are used to estimate returns to specific production areas within 

each of these tributary drainages. Historically, spring-run Chinook salmon may have also used 

portions of the Okanogan River. 

Grand Coulee Dam, completed in 1938, formed an impassable block to the upstream 

migration of anadromous fish. Chief Joseph Dam was constructed on the mainstem Columbia 

River downstream from Grand Coulee Dam and is also an anadromous block. There are no 

specific estimates of historical production of spring-run Chinook salmon from mainstem 

tributaries above Grand Coulee Dam. Habitat typical of that spring-run Chinook salmon use in 

accessible portions of the Columbia River basin is found in the middle and upper reaches of 

mainstem tributaries above Grand Coulee Dam. It is possible that the historical range of this 

ESU included these areas; alternatively, fish from the upper reaches of the Columbia River may 

have been in a separate ESU. 

Artificial production efforts in the area the Upper Columbia River spring-run Chinook 

salmon ESU occupy extend back to the 1890s. Hatchery efforts were initiated in the Wenatchee 

and Methow river systems to augment catches in response to declining natural production (e.g., 

Craig and Soumela 1941). Although there are no direct estimates of adult production from early 

efforts, contributions were likely small. 

In the late 1930s, the Grand Coulee Fish Maintenance Program (GCFMP) was initiated to 

address the fact that the completion of the Grand Coulee Dam cut off anadromous access above 

the dam site. Returning salmonids, including spring-run Chinook salmon, were trapped at Rock 

Island Dam and either transplanted as adults or released as juveniles into selected production 

areas within the accessible drainages below Grand Coulee Dam. Nason Creek in the Wenatchee 

system was a primary adult transplantation area in this effort. The program was conducted 

annually from 1938 until the mid-1940s. 

53 
CHINOOK SALMON

Summary of Previous BRT Conclusions 

In late 1998, the previous BRT reviewed the Upper Columbia River spring-run Chinook 

salmon ESU (NMFS 1998a). That team expressed concern regarding the relatively low 

abundance and the strong downward trend in annual returns for the ESU, noting that although the 

aggregate return (mainstem dam count minus returns to hatchery facilities) was just under 5,000 

fish from 1990 to 1994, returns to natural spawning areas declined dramatically. As a result 

“escapements in 1994–1996 were the lowest in at least 60 years.” The team was concerned that 

at these population sizes, negative effects of demographic and genetic stochastic processes are 

likely to occur. 

The BRT recognized that the implementation of emergency natural broodstocking and 

captive broodstocking efforts for the ESU “indicate[s] the severity of the population declines to 

critically small sizes.” The BRT also noted that “habitat degradation, blockages and 

hydrosystem passage mortality all have contributed to the significant declines in this ESU.” 

Listing status: Endangered. 

New Data and Updated Analyses 

WDFW, the Yakama Tribe, and USFWS conduct annual redd count surveys in nine 

selected production areas within the geographical area encompassed by this ESU (Carie 2000, 

Hubble and Crampton 2000, Mosey and Murphy 2002). Prior to 1987, redd count estimates 

were single-survey peak counts. From 1987 on, annual redd counts have been generated from a 

series of on-the-ground counts and represent the total number of redds constructed in any 

particular year. The agencies use annual dam counts from the mainstem mid-Columbia River 

dams as the basis for expanding redd counts to estimates of total spring-run Chinook salmon 

returns. In the Wenatchee River basin, video counts at Tumwater Dam are available for recent 

years. Returns to hatchery facilities are subtracted from the dam counts prior to the expansion. 

Updated returns are summarized in Tables 6 and 7 and in Figures 24–29. 

An initial set of population definitions for the Upper Columbia River spring-run Chinook 

salmon ESU, along with basic criteria for evaluating the status of each population, were 

developed using the VSP guidelines described in McElhany et al. (2000). The definitions and 

criteria are described in Ford et al. (2001) and were used in the development and review of MidColumbia River Public Utility District plans and the Federal Columbia River Power System 

Biological Opinion (FCRPS 2000). The interim definitions and criteria are being reviewed as 

the Interior Columbia TRT recommendations. Briefly, the joint technical team recommended 

that the Wenatchee, Entiat, and Methow rivers be considered separate populations within the 

Upper Columbia River steelhead ESU. The historical status of spring-run Chinook salmon 

production in the Okanogan River is uncertain. The committee deferred a decision on the 

Okanogan to the Interior Columbia TRT. Abundance, productivity, and spatial structure criteria 

for each population in the ESU were developed and are described in Ford et al. (2001). 

54 
Table 6. Summary of abundance and trend information for the Upper Columbia River spring-run Chinook salmon ESU rel

status review. 

Recent 5-year geometric meana

Total Natural 

Short-term trend 

(percent/yr/) 

Populations 

Percent 

Natural 

origin 

(previousb) Mean (range) Current Previousb Current Previousb

In

t

Methow River totald 41 680 (79–9,904) 282 144 +2.0 –15.3 2Methow River main stemd 41 161 redds (17–2,864) – – +6.5 – 

Twisp Riverd 46 58 redds (10–369) – 87 –9.8 –27.4 Chewuch River 59 58 redds (6–1,105) – 62 –2.9 –28.1 Lost/Early Winters creeksd 46 12 (3–164) 6 62b –14.1 –23.2e 

Entiat River 58 111 (53–444) 65 89 –1.2 –19.4 Wenatchee River total 58 470 (119–4,446) 274 27 –1.5 –37.4 Chiwawa River 53 109 redds (34–1,046) – 134 –0.7 –29.3 Nason Creek 61 54 redds (8–374) – 85 –1.5 –26.0 Upper Wenatchee River 34 8 redds (0–215) – – –8.9 – White River 92 9 redds (1–104) – 25 –6.6 –35.9 Little Wenatchee River 79 11 redds (3–74) – 57 –25.8 –25.8 

a Five-year geometric means calculated using years 1997 to 2001 unless otherwise noted. b Previous years 1987–1996. c Interim targets from Ford et al. (2001). d Five-year geometric mean calculated without year 1998; no data available. e Lost River only. 

55 
CHINOOK SALMON

Table 7. Upper Columbia River spring-run Chinook salmon ESU hatchery returns, 1994–2001. 

Watershed Years Hatchery Stock Release site Total 

1994 Methow Chewuch Chewuch River 40,882

1995–2000 Methow Chewuch Chewuch River 737,621

1994 Methow Twisp Twisp River 35,881

1992–2001 Methow Twisp Twisp River 322,863

1995–2001 Methow Methow Methow River 1,164,289

1992, 1993 Methow Leavenworth NFH* Methow River – 

1991–1994 Winthrop NFH Carson NFH Methow River 3,013,272

1991–1996 Winthrop NFH Methow Methow River 1,639,498

Methow River 

1998–2001 Winthrop NFH Methow Methow River 1,564,392

1994 Entiat NFH Entiat NFH Entiat River 873 adults

1992–1996 Entiat NFH Entiat NFH Entiat River 2,485,310

1997–2001 Entiat NFH Entiat NFH Entiat River 1,828,029

1991, 1992 Entiat NFH Carson NFH Entiat River 1,539,803

Entiat River 

1995, 1996 Entiat NFH Leavenworth NFH Entiat River 276,699

Wenatchee 1991–1994 Chiwawa Pond Chiwawa Chiwawa River 243,421

River 1995–2000 Chiwawa Pond Chiwawa Chiwawa River 608,066

1992 Eastbank Leavenworth NFH Icicle Creek 530,700

1991–1993 Leavenworth NFH Carson NFH Icicle Creek 7,292,301

1994–1996 Leavenworth NFH Leavenworth NFH Icicle Creek 4,942,554

1997–2001 Leavenworth NFH Leavenworth NFH Icicle Creek 7,568,173 *

 NFH = National Fish Hatchery. 

0

1000

2000

3000

4000

5000

6000

7000

8000

1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Escapement

Total Natural origin

Figure 24. Wenatchee River spring-run Chinook salmon spawning escapement, 1960–2001. Sources: 

Estimates expanded from redd counts (Beamesderfer et al. 1998, Cooney 2001); 2001 data from 

Mosey and Murphy (2002). 

56
6. UPPER COLUMBIA RIVER SPRING-RUN CHINOOK SALMON ESU 

0

200

400

600

800

1000

1200

1400

1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total Natural origin

Figure 25. Entiat River spring-run Chinook salmon spawning escapement, 1960–2001. Sources: 

Estimates from expanded redd counts (Beamesderfer et al. 1998, Cooney 2001); recent year data 

from Carie (2002). 

0

2000

4000

6000

8000

10000

12000

1955 1965 1975 1985 1995 2005

Year

Abundance

Total Natural origin

Figure 26. Methow River spring-run Chinook salmon spawning escapement, 1960–2001. Sources: 

Estimates expanded from redd counts (Beamesderfer et al. 1998, Cooney 2001); recent year data 

from Yakama Indian Nation Fisheries.5

 

 

5

J. Hubbell, Confederated Tribes and Bands of the Yakama Nation, Fisheries Resource Management, Toppenish, 

WA. Pers. commun., November 2002.

57
CHINOOK SALMON

0.01

0.10

1.00

10.00

1955 1965 1975 1985 1995 2005

Broodyear

Returns (spawner) per spawner

Figure 27. Wenatchee River spring-run Chinook salmon returns per spawner by broodyear, 1960–2001 

(returns to spawning grounds). Calculated as estimated natural returns to the spawning grounds 

divided by broodyear total spawners (solid line) and returns adjusted to recent average harvest 

rate (1985–2001; dashed line). 

0.01

0.1

1

10

1955 1965 1975 1985 1995 2005

Broodyear

Returns (spawner) per spawner

Spawning escapement Harvest adjustment

Figure 28. Methow River spring-run Chinook salmon returns per spawner by broodyear, 1960–1995 

(returns to spawning grounds). 

58
6. UPPER COLUMBIA RIVER SPRING-RUN CHINOOK SALMON ESU 

0.1

1

10

1955 1965 1975 1985 1995 2005

Broodyear

Returns per spawner

Spawning escapement Harvest adjustment

Figure 29. Entiat River spring-run Chinook salmon returns per spawner by broodyear, 1960–1997 

(returns to spawning grounds). 

New Hatchery Information 

Three national fish hatcheries operated by the USFWS are located within the geographic 

area associated with this ESU. These hatchery programs were established as mitigation 

programs for the construction of Grand Coulee Dam. Leavenworth National Fish Hatchery 

(NFH), located on Icicle Creek, a tributary to the Wenatchee River system (RKm 42), has 

released Chinook salmon since 1940. Entiat NFH is located on the Entiat River, approximately 

10 km upstream of the confluence with the Columbia River main stem. Spring-run Chinook 

salmon have been released from this facility since 1974. Winthrop NFH is on the Methow River 

main stem, approximately 72 km upstream of the confluence with the Columbia River. Springrun Chinook salmon were released from 1941 to 1961, and from 1974 to the present. Initial 

spring-run Chinook salmon releases from these facilities were for the GCFMP project. 

Leavenworth NFH hatchery returns served as the principal stock source for all three facilities 

until the early 1990s. Production was augmented with eggs transferred into the programs from 

facilities outside the ESU, primarily Carson NFH. Broodstocking for each hatchery program has 

been switched to emphasize locally returning broodstocks. Management objectives for the 

Winthrop NFH have been modified to this conservation strategy. The Entiat and Leavenworth 

hatchery programs retain the original harvest augmentation objectives but are managed to restrict 

interactions with natural populations. Carcass surveys and broodstocking efforts in the upstream 

natural spawning areas of the Wenatchee and Entiat rivers support the assumption that the stray 

rate from the downstream hatchery facilities is low—on the order of 1–5%. Significantly higher 

contribution rates have been observed in mainstem Methow River natural spawning areas, 

possibly due to the close proximity of the hatchery and to the recent shift to locally adapted 

stocks. 

59
CHINOOK SALMON

Additional spring-run Chinook salmon hatchery production efforts were initiated in the 

1980s as mitigation for smolt losses at mainstem mid-Columbia River projects operated by 

PUDs. These programs are aimed at directly supplementing targeted natural production areas in 

the Wenatchee and Methow river systems. In the Wenatchee River drainage, this program 

targeted the Chiwawa River, a major spring-run Chinook production tributary entering at river 

kilometer (RKm) 78.2. Broodstock are collected at a weir located approximately 2 km upstream 

of the mouth of the Chiwawa River. In some years, broodstocking has been augmented by using 

marked adults collected at Tumwater Dam. Release groups are returned to an acclimation pond 

adjacent to the lower Chiwawa River for final acclimation and release. 

In the Methow River, the supplementation program began in 1992 with broodstock 

collected from the natural runs to the Chewuch and Twisp rivers. The Methow Fish Hatchery, 

operated by WDFW, has actively managed broodstock collection and mating to maintain 

separate groups for use in the Chewuch, Twisp, and Methow rivers. In 1996, and again in 1998, 

extremely low adult returns led to a decision to collect all adults at Wells Dam. Scale reading, 

elemental scale analysis, and extraction or reading of coded-wire tags have been used at the 

Methow NFH to help maintain broodstock separation. 

Beginning in 1998, a composite stock was initiated, and the management objectives for 

Winthrop NFH were established. Since that time, Methow and Winthrop hatcheries have worked 

together on broodstock collection and spawning activities. Juveniles are reared at the Winthrop 

facility and released into the mainstem Methow River in coordination with releases from 

acclimation sites on the Twisp and Chewuch rivers. The Methow Fish Hatchery program was 

initiated with Winthrop NFH hatchery stock and is being converted to local broodstock. These 

supplementation programs have had two major impacts on natural production areas. Returns to 

natural spawning areas have included increasing numbers of supplementation fish in recent 

years, especially in the Methow River mainstem spawning areas adjacent to the Winthrop NFH. 

The WDFW Salmon and Steelhead Stock Inventory (SASSI) report identified nine stocks 

of spring-run Chinook salmon within the Upper Columbia River spring-run Chinook salmon 

ESU. Ford et al. (2001) describes the results of applying the population definition and criteria 

provided in McElhany et al. (2000) to current Upper Columbia River spring-run Chinook salmon 

production. The conclusions of the effort were that “there are (or historically were) three or four 

independent viable populations of spring-run Chinook salmon in the upper Columbia River 

basin, inhabiting the Wenatchee, Entiat, Methow and (possibly) the Okanogan River basins. 

There appears to be considerable population substructure within the Wenatchee and Methow 

River basins, which should be considered when evaluating recovery goals and management 

actions.”6

 

Hatchery impacts vary among production areas. Large on-station production programs in 

the Wenatchee and Entiat river drainages are located in the lower reaches, some distance 

downstream of natural spawning areas. In the Methow Basin, Winthrop NFH is upstream, 

adjacent to part of the mainstem spawning reach for spring-run Chinook salmon and steelhead. 

Straying of returning hatchery-origin adults into the natural production areas is thought to be low 

 

6

 Spring Chinook salmon spawning in Icicle Creek, Peshastin Creek, Ingalls Creek, and Leavenworth National Fish 

Hatchery are considered an independent, hatchery-derived population that is not part of the ESU (NMFS 1999a). 

60
6. UPPER COLUMBIA RIVER SPRING-RUN CHINOOK SALMON ESU 

for the Wenatchee and Entiat rivers. The supplementation programs in the upper Wenatchee and 

the Methow river basins are designed to specifically boost natural production. In years when the 

return of natural-origin adults is extremely low, the proportion of hatchery-origin adults on the 

spawning grounds can be high, even if the dispersal rate of the returning hatchery fish is low. It 

is likely that returning hatchery fish contribute to spawning in natural production areas in the 

Methow River at a higher rate. Carcass sampling data are available for a limited number of year 

and area combinations for the upper Columbia River drainages (e.g., Mosey and Murphy 2002). 

Spring-run Chinook salmon returns to the Wenatchee and the Methow river systems have 

included relatively large numbers of supplementation program fish in recent years. The total 

return to natural spawning areas in the Wenatchee River system for 2001 is estimated to be 

approximately 4,000—with 1,200 returning from natural spawning and 2,800 from the hatcherybased supplementation program. The return to spawning areas for the Methow in 2001 was 

estimated at well over 9,000. Carcass surveys indicate that returning supplementation adults 

accounted for approximately 80% of the 2001 run to the Methow spawning areas. 

Supplementation programs have contributed substantially to getting fish on the spawning 

grounds in recent years. Little information is available to assess the long-term impact of high 

levels of supplementation on productivity. Categorization for upper Columbia River spring-run 

Chinook salmon hatchery stocks (SSHAG 2003) can be found in Appendix A, Table A-1. 

Comparison with Previous Data 

All three existing Upper Columbia River spring-run Chinook salmon populations have 

exhibited similar trends and patterns in abundance over the past 40 years. The 1998 Chinook 

salmon status review (Myers et al. 1998) reported that long-term trends in abundance for upper 

Columbia River spring-run Chinook salmon populations were generally negative, ranging from 

–5% to +1%. Analyses of the data series, updated to include 1996–2001 returns, indicate that 

those trends have continued. The long-term trend in spawning escapement is downward for all 

three systems. Since 1958, Wenatchee River spawning escapements have declined at an average 

rate of 5.6% per year, the Entiat River population at an average of 4.8% per year, and the 

Methow River population at an average of 6.3% per year. These rates of decline were calculated 

from the redd count data series.7

Mainstem spring-run Chinook salmon fisheries harvested Chinook salmon at rates 

between 30% and 40% per year through the early 1970s. Restricting mainstem commercial 

fisheries and sport harvest in the mid-1970s substantially reduced the harvest. The calculated 

downward trend in abundance for the upper Columbia River stocks would be higher if the early 

redd counts had been revised to reflect the potential “transfer” from harvest to escapement for 

the early years in the series. 

In the 1960s and 1970s, spawning escapement estimates were relatively high, with 

substantial year-to-year variability. Escapements declined in the early 1980s, then peaked at 

 

7

 Prior to 1987, annual redd counts were obtained from single surveys and reported as peak counts. Since 1987, redd 

counts have been derived from multiple surveys and are reported as annual total counts. An adjustment factor of 

1.7 was used to expand the pre-1987 redd counts for comparison with the more recent total counts (Beamesderfer 

et al. 1998). 

61
CHINOOK SALMON

relatively high levels in the mid-1980s. Returns declined sharply in the late 1980s and early 

1990s. Returns from 1990 to 1994 were at the lowest levels observed in the 40-plus years of the 

data sets. The Upper Columbia Biological Requirements Workgroup (Ford et al. 2001) 

recommended interim delisting levels of 3,750, 500, and 2,200 spawners for the populations 

returning to the Wenatchee, Entiat, and Methow river drainages, respectively. The most recent 

5-year geometric mean spawning escapements (1997–2001) were at 8–15% of these levels. 

Target levels have not been exceeded since 1985 for the Methow River run, and since the early 

1970s for the Wenatchee and Entiat river populations. 

Short-term trends for the aggregate population areas reported in the 1998 BRT status 

review (Myers et al. 1998) ranged from –15.3% (Methow River) to –37.4% (Wenatchee River). 

Escapements from 1996 to 1999 reflected that downward trend. Escapements increased 

substantially in 2000 and 2001 in all three systems. Returns to the Methow and Wenatchee 

rivers reflected the higher return rate on natural production as well as a large increase in 

contributions from supplementation programs. Short-term trends (1990–2001) in natural returns 

remain negative for all three Upper Columbia River spring-run Chinook salmon ESU 

populations. Natural returns to the spawning grounds for the Entiat, Methow, and Wenatchee 

river populations continued downward at average rates of 3%, 10%, and 16% respectively. 

Short- and long-term trends in returns to the individual subpopulations within the 

Wenatchee and Methow systems were consistent with the aggregate population-level trends. 

Long- and short-term trends for upper Columbia River spring-run Chinook salmon populations 

are shown in Figures 30 and 31. 

McClure et al. (2003) reported standardized quantitative risk assessment results for 152 

listed salmon stocks in the Columbia River basin, including representative data sets (1980–2000 

return years) for upper Columbia River spring-run Chinook salmon. Average annual growth rate 

(λ) for the upper Columbia River spring-run Chinook salmon population was estimated at 0.85, 

the lowest average reported for any of the Columbia River ESUs analyzed in the study. 

Assuming that population growth rates were to continue at the 1980–2000 levels, upper 

Columbia River spring-run Chinook salmon populations are projected to have a very high 

probability of a 90% decline within 50 years (0.87 for the Methow River population, 1.0 for the 

Wenatchee and Entiat runs). 

The major harvest impacts on upper Columbia River spring-run Chinook salmon have 

been in mainstem fisheries below McNary Dam and in sport fisheries in each tributary. There 

are no specific estimates of historical harvest impacts on upper Columbia River spring-run 

Chinook salmon runs. Assuming that upper Columbia River spring-run Chinook salmon runs 

were equally available to mainstem commercial fisheries, as were the runs to other areas of the 

Snake and Columbia rivers, harvest rates in the lower Columbia River commercial fisheries were 

likely to be on the order of 20–40% of the in-river run. Lower Columbia River harvest rates on 

up-river spring-run Chinook salmon stocks were sharply curtailed beginning in 1980 and were 

again reduced after the listing of Snake River spring/summer-run Chinook salmon in the early 

1990s. Sport fishery impacts were also curtailed. Harvest impacts are currently being managed 

under a harvest management schedule—harvest rates are curtailed even further if the average 

return drops below a predefined level, or increased at high run sizes. 

62
6. UPPER COLUMBIA RIVER SPRING-RUN CHINOOK SALMON ESU 

Upper Columbia River spring-run Chinook salmon are subject to passage mortalities 

associated with mainstem hydroelectric projects. Production from all upper Columbia River 

tributary drainages passes through the four lower Columbia River federal dam projects and a 

varying number of mid-Columbia River Public Utility District dam projects. The Wenatchee 

River enters the Columbia River above seven mainstem dams, the Entiat above eight dams, and 

the Methow and Okanogan rivers above nine dams. In the early 1990s, the draft Mid-Columbia 

Habitat Conservation Plan established salmonid survival objectives for Wells, Rocky Reach, and 

Rock Island dams. Interim operating guidelines apply to Wanapum and Priest Rapids dams. 

Operational improvements were made to increase outmigrant survival through the mainstem 

mid-Columbia River Public Utility District hydroelectric dams (Cooney 2001, FCRPS 2000). 

Each upper Columbia River spring-run Chinook salmon area has a particular set of 

habitat problems. In general, tributary habitat problems affecting this ESU include increasing 

urbanization on the lower reaches, irrigation and flow diversions in upriver sections of the major 

drainage, and impacts of grazing on middle reaches. 

Previous assessments of stocks within this ESU identified several populations as being at 

risk or of concern. WDF et al. (1993) considered nine such stocks within this ESU, eight of 

0.7

0.8

0.9

1.0

1.1

1.2

1.3

Wenatchee

(H0)

Wenatchee

(H1)

Entiat (H0)Entiat (H1)

Methow (H0)Methow (H1)

λ

Figure 30. Long-term (1960–2001) annual growth rates (λ) for Upper Columbia River spring-run 

Chinook salmon ESU populations. Error bars represent 95% confidence limits. H0 = hatchery 

fish are assumed to have zero reproductive success; H1 = hatchery-origin spawners are assumed 

to have the same reproductive success as natural-origin fish. 

63
CHINOOK SALMON

0.7

0.8

0.9

1.0

1.1

1.2

1.3

Wenatchee

(H0)

Wenatchee

(H1)

Entiat (H0)Entiat (H1)

Methow (H0)Methow (H1)

λ

Figure 31. Short-term (1990–2001) annual growth rates (λ) for Upper Columbia River spring-run 

Chinook salmon ESU populations. Error bars represent 95% confidence limits of the trend. H0 = 

hatchery fish are assumed to have zero reproductive success; H1 = hatchery-origin spawners are 

assumed to have the same reproductive success as natural-origin fish. 

which were considered of native origin and predominantly natural production. The status of all 

nine stocks was considered to be depressed. Nehlsen et al. (1991) listed six additional stocks 

from the upper Columbia River as extinct, all of them associated with drainages entering the 

Columbia River main stem above Chief Joseph and Grand Coulee dams. Those dams blocked 

access by adult anadromous fish to the upper Columbia River basin. 

64
7. Puget Sound Chinook Salmon ESU 

The status of Puget Sound Chinook salmon was formally assessed during a coastwide 

status review (Myers et al. 1998). In November 1998, a BRT was convened to update the status 

of this ESU by summarizing information received since that review and comments on the 1997 

status review (NMFS 1998a). The subsection below, Summary of Previous BRT Conclusions, 

summarizes findings and conclusions made at the time of the 1998 status review update; New 

Data and Updated Analyses reports on new information received through March 2003 and the 

2003 BRT’s conclusions, based on the new information. 

Summary of Previous BRT Conclusions 

Status and Trends 

The BRT concluded in 1998 that the Puget Sound Chinook salmon ESU was likely to 

become endangered in the foreseeable future. The estimated total run size of Chinook salmon to 

Puget Sound in the early 1990s was 240,000 Chinook, down from an estimated 690,000 

historical run size. The 5-year geometric mean of spawning escapement of natural Chinook 

salmon runs in north Puget Sound during the period from 1992 to 1996 was approximately 

13,000. Both long- and short-term trends for these runs were negative, with few exceptions. In 

south Puget Sound, spawning escapement of the natural runs averaged 11,000 spawners at the 

time of the last status review update. In this area, both long- and short-term trends were 

predominantly positive. In Hood Canal, spawning populations in six streams were considered a 

single stock by the comanagers because of extensive transfers of hatchery fish (WDF et al. 

1993). Fisheries in the area were managed primarily for hatchery production and secondarily for 

natural escapement; high harvest rates directed at hatchery stocks resulted in failure to meet 

natural escapement goals in most years (USFWS 1997). 

The 5-year geometric mean natural spawning escapement at the time of the last update 

was 1,100, with negative short- and long-term trends (except in the Dosewallips River). The 

ESU also includes the Dungeness and Elwha rivers, which have natural Chinook salmon runs as 

well as hatchery runs. The Dungeness River had a run of spring- and summer-run Chinook 

salmon, with a 5-year geometric mean natural escapement of 105 fish at the time of the last 

status review update. The Elwha River had a 5-year geometric mean escapement of 1,800 fish 

during the mid-1990s, which includes a large, but unknown fraction of naturally spawning 

hatchery fish. Both the Elwha and Dungeness river populations exhibited downward trends in 

abundance in the 1990s. 

65 
CHINOOK SALMON

Threats 

Habitat throughout the ESU has been blocked or degraded. In general, forest practices 

impacted upper tributaries, and agriculture or urbanization impacted lower tributaries and 

mainstem rivers. WDF et al. (1993) cited diking for flood control, draining and filling of 

freshwater and estuarine wetlands, and sedimentation due to forest practices and urban 

development as problems throughout the ESU. Blockages by dams, water diversions, and shifts 

in flow regime due to hydroelectric development and flood control projects are major habitat 

problems in several basins. Bishop and Morgan (1996) identified a variety of critical habitat 

issues for streams in the range of this ESU, including changes in flow regime (all basins), 

sedimentation (all basins), high temperatures (Dungeness, Elwha, Green/Duwamish, Skagit, 

Snohomish, and Stillaguamish rivers), streambed instability (most basins), estuarine loss (most 

basins), loss of large woody debris (Elwha, Snohomish, and White rivers), loss of pool habitat 

(Nooksack, Snohomish, and Stillaguamish rivers), and blockage or passage problems associated 

with dams or other structures (Cedar, Elwha, Green/Duwamish, Snohomish, and White rivers). 

The Puget Sound Salmon Stock Review Group of the Pacific Fishery Management 

Council (PFMC 1997a) provided an extensive review of habitat conditions for several stocks in 

this ESU. It concluded that reductions in habitat capacity and quality have contributed to 

escapement problems for Puget Sound Chinook salmon, citing evidence of direct losses of 

tributary and mainstem habitat due to dams, and of slough and side-channel habitat due to 

diking, dredging, and hydromodification. It also cited reductions in habitat quality due to land 

management activities. 

WDF et al. (1993) classified 11 out of 29 stocks in this ESU as being sustained, in part, 

through artificial propagation. Nearly 2 billion fish have been released into Puget Sound 

tributaries since the 1950s (Myers et al. 1998). The vast majority of these fish were derived from 

local returning fall-run adults. Returns to hatcheries have accounted for 57% of total spawning 

escapement, although the hatchery contribution to spawner escapement is probably much higher 

than that, due to hatchery-derived strays on the spawning grounds. Almost all releases into this 

ESU have come from stocks within this ESU, with the majority of within-ESU transfers coming 

from the Green River Hatchery or hatchery broodstocks derived from Green River stock 

(Marshall et al. 1995). The electrophoretic similarity between Green River fall-run Chinook 

salmon and several other fall-run stocks in Puget Sound (Marshall et al. 1995) suggests that there 

may have been a significant effect from some hatchery transplants. Overall, the pervasive use of 

Green River stock throughout much of the extensive hatchery network that exists in this ESU 

may reduce the genetic diversity and fitness of naturally spawning populations. 

Harvest impacts on Puget Sound Chinook salmon stocks were quite high. Ocean 

exploitation rates on natural stocks averaged 56–59%; total exploitation rates averaged 68–83% 

(1982–1989 broodyears) (PSC 1994). Total exploitation rates on some stocks have exceeded 

90% (PSC 1994). 

Previous assessments of stocks within this ESU identified several stocks as being at risk 

or of concern (reviewed in Myers et al. 1998). 

Listing status: Threatened. 

66
7. PUGET SOUND CHINOOK SALMON ESU 

New Data and Updated Analyses 

ESU Status at a Glance 

Historical peak run size ≈690,000 

Historical populations 31 

Extant populations 22 

5-year geometric mean natural spawners 

per population 

222–9,489 (median = 766) 

Long-term trend per population 0.92–1.2 (median = 1.0) 

Recent λ (Η1) per population 0.67–1.2 (median = 1.0) 

ESU Structure 

The Puget Sound Chinook salmon ESU is composed of 31 historically quasi-independent 

populations, 22 of which are believed to be extant currently (Puget Sound TRT 2001, 2002). 

The populations presumed to be extinct are mostly early returning fish; most of these are in midto southern Puget Sound or Hood Canal and the Strait of Juan de Fuca (Table 8). The ESU 

populations with the greatest estimated fractions of hatchery fish tend to be in mid- to southern 

Puget Sound, Hood Canal, and the Strait of Juan de Fuca (Table 9). 

New information obtained for the 22 Chinook salmon populations in the Puget Sound 

ESU is summarized in Appendix A, Table A-2. Data sources and detailed information on data 

years are provided for each population separately in the appendix. 

Abundance of Natural Spawners 

The most recent 5-year (1998–2002) geometric mean of natural spawners in populations 

of Puget Sound Chinook salmon ranges from 222 (in the Dungeness River) to almost 9,500 fish 

(in the upper Skagit River population). Most populations contain natural spawners numbering in 

the high hundreds (median recent natural escapement = 766); and of the 10 populations with 

greater than 1,000 natural spawners, only 2 are thought to have a low fraction of hatchery fish 

(Table 9, Figures 32–53). Estimates of the fraction of natural spawners that are of hatchery 

origin are sparse—data are available for only 12 of the 22 populations in the ESU, and such 

information is available for only the most recent 5–10 years (Table 9). Estimates of the hatchery 

fraction of natural spawners come from counts of otolith-marked local hatchery fish sampled 

from carcasses (Nooksack River basin, Snohomish River basin), adipose fin-clip counts from 

redd count surveys (Skagit River basin), and coded-wire tag sampling (North Fork Stillaguamish 

and Green rivers). In general, populations in the Skagit River basin are the only ones with 

presumed low estimates of naturally spawning hatchery fish. The Stillaguamish and Snohomish 

populations have moderate estimates of naturally spawning hatchery fish. Estimates of historical 

equilibrium abundance from predicted pre-European settlement habitat conditions range from 

1,700 to 51,000 potential Chinook salmon spawners per population (Mobrand 2000). The 

historical estimates of equilibrium abundance are several orders of magnitude higher than 

realized spawner abundances currently observed throughout the ESU. 

67
CHINOOK SALMON

Table 8. Historical populations of Chinook salmon in the Puget Sound ESU, run-timing types for each 

population, and each population’s biogeographic region. 

Populationa Status 

Runtimingb

Bio-geographic 

regionb Reference 

North Fork Nooksack Extant Early Strait of Georgia – 

South Fork Nooksack Extant Early Strait of Georgia – 

Nooksack late Extinct Late Strait of Georgia Puget Sound TRT 

(2001) 

Lower Skagit Extant Late Whidbey Basin – 

Upper Skagit Extant Late Whidbey Basin – 

Lower Sauk Extant Late Whidbey Basin – 

Upper Sauk Extant Early Whidbey Basin – 

Suiattle Extant Early Whidbey Basin – 

Upper Cascade Extant Early Whidbey Basin – 

North Fork Stillaguamish Extant Late Whidbey Basin – 

South Fork Stillaguamish Extant Late Whidbey Basin – 

Stillaguamish early Extinct Early Whidbey Basin Nehlsen et al. (1991), 

WDF et al. (1993) 

Skykomish Extant Late Whidbey Basin – 

Snoqualmie Extant Late Whidbey Basin – 

Snohomish early Extinct Early Whidbey Basin Nehlsen et al. (1991), 

WDF et al. (1993) 

Cedar Extant Late Main/South Basins – 

North Lake Washington Extant Late Main/South Basins – 

Green/Duwamish Extant Late Main/South Basins – 

Green/Duwamish early Extinct Early Main/South Basins Nehlsen et al. (1991), 

WDF et al. (1993) 

Puyallup Extant Late Main/South Basins – 

White Extant Early Main/South Basins – 

Puyallup early Extinct Early Main/South Basins Nehlsen et al. (1991) 

Nisqually Extant Late Main/South Basins – 

Nisqually early Extinct Early Main/South Basins Nehlsen et al. (1991), 

ONRC and Kawa (1995) 

Skokomish Extant Late Hood Canal – 

Skokomish early Extinct Early Hood Canal Nehlsen et al. (1991), 

WDF et al. (1993) 

Dosewallips Extant Late Hood Canal – 

Dosewallips early Extinct Early Hood Canal Nehlsen et al. (1991), 

ONRC and Kawa (1995) 

Dungeness Extant Late Strait of Juan de Fuca – 

Elwha Extant Late Strait of Juan de Fuca – 

Elwha early Extinct Early Strait of Juan de Fuca Nehlsen et al. (1991) a

 Puget Sound Technical Recovery Team (2001). 

b

 Puget Sound Technical Recovery Team (2001, 2002). 

68
Table 9. Abundance of natural spawners, estimates of the fraction of hatchery fish in natural escapements, and estimates o

Puget Sound streams. Sources: For data sources, see Appendix A, Table-2.

Population 

Geometric 

mean 

natural 

spawners 

(1998–2002) 

Arithmetic mean 

natural spawners 

(1998–2002) 

(minimum, 

maximum) 

Geometric 

mean 

natural– 

origin 

spawners 

(1998–2002) 

Average 

% hatchery fish 

in escapementa

1997–2001 

(min.–max. 

since 1992) 

Chinook salmon 

hatcheries in basin Hatchery 

data? (y

North Fork Nooksackc

1,538 2,275 (366–4,671) 125 91 (88–95) Kendall (NFH; RM 45) Yes (1995

South Fork Nooksackc

338 372 (157–620) 197 40 (24–55) Kendall (NFH; RM45) Yes (1999

Lower Skagit 2,527 2,833 (1,043–4,866) 2,519 0.2 (0–0.7) Marblemount (mouth of 

Cascade)d

Yes (1998

Upper Skagit 9,489 10,468 (3,586–13,815) 9,281 2 (2–3) Marblemount (mouth of 

Cascade)d

Yes (1995

Upper Cascade 274 329 (83–625) 274 0.3 Marblemount (mouth of 

Cascade)d

No (assum

Lower Sauk 601 669 (295–1,103) 601 0 Marblemount (mouth of 

Cascade)d

Yes (2

Upper Sauk 324 349 (180–543) 324 0 Marblemount (mouth of 

Cascade)d

No (ass

Suiattle 365 399 (208–688) 365 0 Marblemount (mouth of 

Cascade)d

No (ass

North Fork Stillaguamish 

1,154 1,172 (845–1,403) 671 40 (13–52) Tribal (NF) Yes (1988

South Fork Stillaguamish 

270 272 (243–335) NA NA Tribal (NF) Non

Skykomish 4,262 4,286 (3,455–4,665) 2,392 40 (11–66) Wallace River Yes (1979Snoqualmie 2,067 2,229 (1,344–3,589) 1,700 16 (5–72) Wallace River Yes (1979North Lake Washington 

331 351 (227–537) NA NA Lake Washington, 

Issaquah, University of Washington 

Non

Cedar 327 394 (120–810) NA NA Lake Washington, 

Issaquah, University of Washington 

Non

Green 8,884 9,286 (6,170–13,950) 1,099 83 (35–100) Soos, Icy, Keta creeks Yes (1989Whitee 844 1,039 (316–2,002) NA NA White River (RM 23); 

Voights Creek (Carbon River), Diru (RM 5) 

Non

69
Table 9 continued. Abundance of natural spawners, estimates of the fraction of hatchery fish in natural escapements, and e

capacity of Puget Sound streams. Sources: For data sources, see Appendix A, Table-2. 

Population 

Geometric 

mean 

natural 

spawners 

(1998–2002) 

Arithmetic mean 

natural spawners 

(1998–2002) 

(minimum, 

maximum) 

Geometric 

mean 

natural– 

origin 

spawners 

(1998–2002) 

Average 

% hatchery fish 

in escapementa

1997–2001 

(min.–max. 

since 1992) 

Chinook salmon 

hatcheries in basin 

Hatchery 

data? (y

Puyallup 1,653 1,679 (1,193–1,988) NA NA Voights Creek (Carbon 

River), Diru (RM 5) 

Non

Nisqually 1,195 1,221 (834–1,542) NA NA Kalama, Clear Creek NonSkokomish 1,392 1,437 (926–1,913) NA NA George Adams (Purdy 

Creek, lower Skok) 

Non

Dosewallipsf 48 50 (29–65) NA NA None Non

Duckabushf 43 57 (20–151) NA NA None NonHamma Hammaf 196 278 (32–557) NA NA None NonMid Hood Canal 311 381 (95–762) NA NA None NonDungenesse 222 304 (75–663) NA NA Dungeness (and Hurd 

Creek) 

Non

Elwhag, h 688 691 (633–813) NA NA Tribal (RM 1) and state 

(RM 3.2) 

Non

NFH = National Fish Hatchery. a Estimates of the fraction of hatchery fish in natural spawning escapements are from the Puget Sound TRT database; Green River est

Alexandersdottir (2001).

b Estimates of historical equilibrium abundance based on an EDT analysis conducted by the comanagers in Puget Sound (Puget Sound c North Fork Nooksack natural escapement counts include estimated numbers of spawners from the Middle Fork Nooksack River sinc

Chinook salmon returning to the North Fork hatchery that were released back into the North Fork to spawn; South Fork Nooksack nestimates contain naturally spawning hatchery fish from the early run and late-run hatchery programs in the Nooksack River basin. 

d Previous summer-run Chinook salmon hatchery program discontinued—last returns in 1996; current summer-run program (initiated 

broodstock from spawners in upper Skagit River. 

e Captive broodstock program for early run Chinook salmon ended in 2000; estimates of natural spawning escapement include an unk

spawning hatchery-origin fish from late- and early run hatchery programs in the White and Puyallup River basins. 

f The Puget Sound TRT considers Chinook salmon spawning in the Dosewallips, Duckabush, and Hamma Hamma rivers to be subpop

historically independent population; annual counts in those three streams are variable due to inconsistent visibility during spawning 

g Year 2002 natural escapement data are not available. h Estimates of natural escapement do not include volitional returns to the hatchery or those fish gaffed or seined from spawning groun

collection. 

70
7. PUGET SOUND CHINOOK SALMON ESU 

0

100

200

300

400

500

600

700

1980 1985 1990 1995 2000 2005

Year

Abundance

Total Natural origin

Figure 32. Total and natural-origin spawner abundance estimates versus year for the North Fork 

Nooksack River population of Chinook salmon, 1984–2001. 

0

500

1000

1500

2000

2500

3000

3500

4000

4500

1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002

Year

Abundance

Total Natural origin

Figure 33. Total and natural-origin spawner abundance estimates versus year for the South Fork 

Nooksack River population of Chinook salmon, 1984–2001.

71
CHINOOK SALMON

0

2000

4000

6000

8000

10000

12000

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total Natural origin

Figure 34. Total and natural-origin spawner abundance estimates versus year for the lower Skagit River 

population of Chinook salmon, 1951–2002.

0

2000

4000

6000

8000

10000

12000

14000

16000

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total Natural origin

Figure 35. Total and natural-origin spawner abundance estimates versus year for the upper Skagit River 

population of Chinook salmon, 1951–2002. 

72
7. PUGET SOUND CHINOOK SALMON ESU 

0

100

200

300

400

500

600

700

1980 1985 1990 1995 2000 2005

Year

Abundance

Total Natural origin

Figure 36. Total and natural-origin spawner abundance estimates versus year for the upper Cascade River 

population of Chinook salmon, 1984–2002. 

0

500

1000

1500

2000

2500

3000

3500

4000

4500

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Figure 37. Total spawner abundance estimates versus year for the lower Sauk River population of 

Chinook salmon, 1952–2002.

73
CHINOOK SALMON

0

500

1000

1500

2000

2500

3000

3500

4000

1950 1960 1970 1980 1990 2000 2010

Year

Abundance

Figure 38. Total spawner abundance estimates versus year for the upper Sauk River population of 

Chinook salmon, 1960–2002. 

0

200

400

600

800

1000

1200

1400

1600

1800

2000

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Figure 39. Total spawner abundance estimates versus year for the Suiattle River population of Chinook 

salmon, 1952–2002.

74
7. PUGET SOUND CHINOOK SALMON ESU 

0

200

400

600

800

1000

1200

1400

1600

1800

2000

1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total Natural origin

Figure 40. Total and natural-origin spawner abundance estimates versus year for the North Fork 

Stillaguamish River population of Chinook salmon, 1974–2002. 

0

50

100

150

200

250

300

350

400

1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Figure 41. Total spawner abundance estimates versus year for the South Fork Stillaguamish River 

population of Chinook salmon, 1974–2003. 

75
CHINOOK SALMON

0

1000

2000

3000

4000

5000

6000

7000

8000

1960 1970 1980 1990 2000 2010

Year

Abundance

Total Natural origin

Figure 42. Total and natural-origin spawner abundance estimates versus year for the Skykomish River 

population of Chinook salmon, 1965–2002. 

0

500

1000

1500

2000

2500

3000

3500

4000

1960 1970 1980 1990 2000 2010

Year

Abundance

Total Natural origin

Figure 43. Total and natural-origin spawner abundance estimates versus year for the Snoqualmie River 

population of Chinook salmon, 1965–2003.

76
7. PUGET SOUND CHINOOK SALMON ESU 

0

100

200

300

400

500

600

1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002

Year

Abundance

Figure 44. Total spawner abundance estimates versus year for the north Lake Washington tributaries 

population of Chinook salmon, 1983–2002. 

0

200

400

600

800

1000

1200

1400

1600

1800

2000

1960 1970 1980 1990 2000 2010

Year

Abundance

Figure 45. Total spawner abundance estimates versus year for the Cedar River population of Chinook 

salmon, 1965–2002. 

77
CHINOOK SALMON

0

2000

4000

6000

8000

10000

12000

14000

16000

1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total Natural origin

Figure 46. Total and natural-origin spawner abundance estimates versus year for the Green/Duwamish 

rivers population of Chinook salmon, 1967–2002. 

0

1000

2000

3000

4000

5000

6000

1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Figure 47. Total spawner abundance estimates versus year for the Puyallup River population of Chinook 

salmon, 1969–2002. 

78
7. PUGET SOUND CHINOOK SALMON ESU 

0

500

1000

1500

2000

2500

1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Figure 48. Total spawner abundance estimates versus year for the White River population of Chinook 

salmon, 1970–2002.

0

500

1000

1500

2000

2500

1960 1970 1980 1990 2000 2010

Year

Abundance

Figure 49. Total spawner abundance estimates versus year for the Nisqually River population of Chinook 

salmon, 1968–2002.

79
CHINOOK SALMON

0

500

1000

1500

2000

2500

3000

1985 1990 1995 2000 2005

Year

Abundance

Figure 50. Total spawner abundance estimates versus year for the Skokomish River population of 

Chinook salmon, 1987–2003. 

0

200

400

600

800

1000

1200

1400

1600

1960 1970 1980 1990 2000 2010

Year

Abundance

Figure 51. Total spawner abundance estimates versus year for the Dosewallips/Hamma 

Hamma/Duckabush rivers population of Chinook salmon, 1967–2002.

80
7. PUGET SOUND CHINOOK SALMON ESU 

0

100

200

300

400

500

600

700

1985 1990 1995 2000 2005

Year

Abundance

Figure 52. Total spawner abundance estimates versus year for the Dungeness River population of 

Chinook salmon, 1986–2002. 

0

1000

2000

3000

4000

5000

6000

1985 1990 1995 2000 2005

Year

Abundance

Figure 53. Total spawner abundance estimates versus year for the Elwha River population of Chinook 

salmon, 1986–2001.

81
CHINOOK SALMON

Trends in Natural Spawners 

Long-term trends in abundance for naturally spawning populations of Chinook salmon in 

Puget Sound indicate that approximately half the populations are declining, and half are 

increasing in abundance over the length of available time series (Table 10 and Figures 32–53). 

The median over all populations of long-term trend in abundance is 1.0 (range 0.92–1.2), 

indicating that most populations are just replacing themselves. Over the long term, the most 

extreme declines in natural spawning abundance have occurred in the combined Dosewallips and 

Elwha populations. Those populations with the greatest long-term population growth rates are 

the North Fork Nooksack and White rivers. All populations reported above are likely to have a 

moderate to high fraction of naturally spawning hatchery fish, so it is not possible to say what the 

trends in naturally spawning, natural-origin Chinook salmon might be in those populations. 

Table 10. Estimates of long- and short-term trends, and the short-term median population growth rate (λ), 

and their 95% confidence intervals (CI) for spawners in Puget Sound Chinook salmon 

populations. 

Population Data years 

Long-term trend 

(CI)a

Short-term 

trend (CI) 

(1990–2002)b

ST λ (+ lnSE)

(1990–2002)b

North Fork Nooksack 1984–2001 1.16 (1.04–1.30) 1.42 (1.18–1.70) 0.75 (0.07) 

South Fork Nooksack 1984–2001 1.00 (0.96–1.05) 1.07 (0.98–1.15) 0.94 (0.05) 

Lower Skagit 1952–2002 0.99 (0.97–1.00) 1.06 (0.94–1.18) 1.05 (0.09) 

Upper Skagit 1952–2002 1.00 (0.99–1.01) 1.06 (0.98–1.14) 1.05 (0.06) 

Upper Cascade 1984–2002 1.04 (1.00–1.08) 1.05 (0.98–1.14) 1.06 (0.05) 

Lower Sauk 1952–2002 0.99 (0.98–1.00) 1.03 (0.91–1.17) 1.01 (0.12) 

Upper Sauk 1952–2002 0.97 (0.96–0.99) 0.97 (0.89–1.06) 0.96 (0.06) 

Suiattle 1952–2002 0.99 (0.98–0.99) 1.00 (0.92–1.08) 0.99 (0.06) 

North Fork Stillaguamish 1974–2002 1.01 (0.99–1.03) 1.06 (1.01–1.11) 0.92 (0.04) 

South Fork Stillaguamishc 1974–2002 1.02 (1.00–1.04) 1.00 (0.97–1.02) 0.99 (0.02) 

Skykomish 1965–2002 0.99 (0.98–1.00) 1.07 (1.03–1.11) 0.87 (0.03) 

Snoqualmie 1965–2002 1.03 (1.01–1.04) 1.10 (1.01–1.21) 1.00 (0.04) 

North Lake Washingtonc 1983–2002 0.97 (0.91–1.03) 1.04 (0.91–1.19) 1.07 (0.07) 

Cedarc 1965–2002 0.97 (0.95–0.98) 0.97 (0.89–1.07) 0.99 (0.07) 

Greenc 1968–2002 1.02 (1.01–1.04) 1.05 (0.98–1.13) 0.67 (0.06) 

Whitec 1970–2002 1.05 (1.00–1.10) 1.14 (1.06–1.22) 1.16 (0.06) 

Puyallupc 1968–2002 1.02 (1.00–1.04) 0.96 (0.91–1.02) 0.95 (0.06) 

Nisquallyc 1968–2002 1.02 (0.99–1.05) 1.06 (0.93–1.20) 1.04 (0.07) 

Skokomishc 1987–2002 0.99 (0.93–1.05) 1.04 (0.97–1.12) 1.04 (0.04) 

Combined Dosewallipsc 1968–2002 0.96 (0.93–0.98) 1.11 (0.99–1.20) 1.17 (0.10) 

Dungenessc 1986–2002 1.02 (0.94–1.10) 1.07 (0.94–1.20) 1.09 (0.11) 

Elwhac 1986–2001 0.92 (0.84–1.00) 0.97 (0.86–1.10) 0.95 (0.11) a

 Long- and short-term trends are calculated on all spawners. 

b

 Short-term λ is calculated assuming the reproductive success of naturally spawning hatchery fish is equivalent to 

that of natural-origin fish (for those populations where information on the fraction of hatchery fish in natural 

spawning abundance is available). 

c Estimate of the fraction of hatchery fish in time series is not available for use in λ calculation, so trend represents 

that in hatchery-origin + natural-origin spawners. 

82
7. PUGET SOUND CHINOOK SALMON ESU 

Fewer populations exhibit declining trends in abundance over the short term than over the 

long term—4 of 22 populations in the ESU declined from 1990 to 2002 (median = 1.06, range = 

0.96–1.4) (Table 10). In contrast, estimates of short-term population growth rates suggest a very 

different picture when the reproductive success of hatchery fish is assumed to be 1. As discussed 

in Section 2, Methods, short-term population growth rates (λ) were calculated under two 

assumptions about the reproductive success of naturally spawning hatchery fish: the reproductive 

success was 0 (H0), or the reproductive success was equivalent to that of natural-origin fish 

(H1). Short-term λ estimates, assuming the reproductive success of hatchery fish was 0, are very 

similar to estimates of short-term trend, so they are not reported here. The median short-term λ

over all populations (when the reproductive success of hatchery fish is assumed to be 1) is 

λ − Η1 = 1.0 (range = 0.67 – 1.2) (21) 

The median estimate of short-term population growth would be even lower if the 

estimates of the fraction of naturally spawning hatchery fish were available for all populations in 

the ESU. As mentioned earlier, the 10 populations in the ESU for which no hatchery fraction 

information is available are all suspected to have a moderate to high fraction of hatchery-origin 

adults in natural escapements. In those cases where hatchery information is available and the 

fraction of hatchery-origin natural spawners is significant (e.g., North Fork Nooksack and Green 

rivers), the effect of the reproductive success of hatchery fish assumption on estimates of λ is 

dramatic. The most extreme short-term declines in natural spawner abundance have occurred in 

the upper Sauk, Cedar, Puyallup, and Elwha populations. Of these populations, only the upper 

Sauk is likely to have a low fraction of hatchery fish in escapements. When λ is calculated 

assuming the reproductive success of hatchery fish is equivalent to that of natural-origin fish, the 

biggest estimated short-term population declines are in the Green, Skykomish, North Fork 

Stillaguamish, and North Fork Nooksack populations (Table 10). Again, if hatchery fraction 

data were available for the additional 10 populations in the ESU for which such data are missing, 

more examples of significant short-term declines in population growth rate surely would emerge. 

The populations with the most positive short-term trends and population growth rates are the 

combined Dosewallips and White river populations. Both of these populations are thought to 

have a moderate fraction of naturally spawning hatchery fish, but because such estimates are not 

available, estimating the trends in natural-origin spawners is not possible. 

Another indicator of the productivity of Chinook salmon populations is presented in the 

time-series figures showing the total number of spawners (natural and hatchery origin) and the 

number of preharvest recruits produced by those spawners against time (Figures 54–75). 

Dividing the number of preharvest recruits by the number of spawners for the same time period 

would yield an estimate of the preharvest recruits per spawner. Generating this type of figure 

requires harvest and age structure information and therefore could be produced for only a limited 

number of years in some populations. Representing information this way can indicate whether 

there have been changes in preharvest recruitment and the degree to which harvest management 

has the potential to recover populations. If the preharvest recruitment line is consistently below 

the spawner line, it indicates that the population would not be replacing itself, even in the 

absence of all harvest. In most populations, the preharvest recruits exceeded spawners in all but 

a few years for which data are available (Figures 54–75). 

83
CHINOOK SALMON

0

500

1000

1500

2000

2500

3000

3500

4000

4500

1980 1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 54. Preharvest recruits and spawners versus broodyear for the North Fork Nooksack River 

Chinook salmon population, 1984–2001. 

0

200

400

600

800

1000

1200

1980 1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 55. Preharvest recruits and spawners versus broodyear for the South Fork Nooksack River 

Chinook salmon population, 1984–2001. 

84
7. PUGET SOUND CHINOOK SALMON ESU 

0

10000

20000

30000

40000

50000

60000

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 56. Preharvest recruits and spawners versus broodyear for the lower Skagit River Chinook salmon 

population, 1951–2002. 

0

20000

40000

60000

80000

100000

120000

140000

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 57. Preharvest recruits and spawners versus broodyear for the upper Skagit River Chinook salmon 

population, 1951–2002.

85
CHINOOK SALMON

0

200

400

600

800

1000

1200

1980 1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 58. Preharvest recruits and spawners versus broodyear for the upper Cascade River Chinook 

salmon population, 1984–2002. 

0

5000

10000

15000

20000

25000

30000

35000

1950 1960 1970 1980 1990 2000 2010

Year

Abundance

Preharvest recruits Spawners

Figure 59. Preharvest recruits and spawners versus broodyear for the lower Sauk Chinook salmon 

population, 1951–2002. 

86
7. PUGET SOUND CHINOOK SALMON ESU 

0

1000

2000

3000

4000

5000

6000

7000

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 60. Preharvest recruits and spawners versus broodyear for the upper Sauk River Chinook salmon 

population, 1951–2002. 

0

1000

2000

3000

4000

5000

6000

7000

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 61. Preharvest recruits and spawners versus broodyear for the Suiattle River Chinook salmon 

population, 1951–2002. 

87
CHINOOK SALMON

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 62. Preharvest recruits and spawners versus broodyear for the North Fork Stillaguamish River 

Chinook salmon population, 1974–2002. 

0

200

400

600

800

1000

1200

1400

1600

1800

2000

1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 63. Preharvest recruits and spawners versus broodyear for the South Fork Stillaguamish River 

Chinook salmon population, 1974–2002. 

88
7. PUGET SOUND CHINOOK SALMON ESU 

0

10000

20000

30000

40000

50000

60000

1960 1970 1980 1990 2000 2010

Year

Abundance

Preharvest recruits Spawners

Figure 64. Preharvest recruits and spawners versus broodyear for the Skykomish River Chinook salmon 

population, 1965–2002. 

0

5000

10000

15000

20000

25000

1960 1970 1980 1990 2000 2010

Year

Abundance

Preharvest recruits Spawners

Figure 65. Preharvest recruits and spawners versus broodyear for the Snoqualmie River Chinook salmon 

population, 1965–2002. 

89
CHINOOK SALMON

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 66. Preharvest recruits and spawners versus broodyear for the north Lake Washington tributaries 

Chinook salmon population, 1983–2002. 

0

500

1000

1500

2000

2500

3000

3500

1960 1970 1980 1990 2000 2010

Year

Abundance

Preharvest recruits Spawners

Figure 67. Preharvest recruits and spawners versus broodyear for the Cedar River Chinook salmon 

population, 1965–2002. 

90
7. PUGET SOUND CHINOOK SALMON ESU 

0

200

400

600

800

1000

1200

1400

1980 1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 68. Preharvest recruits and spawners versus broodyear for the Green River Chinook salmon 

population, 1967–2002. 

0

1000

2000

3000

4000

5000

6000

7000

8000

1960 1970 1980 1990 2000 2010

Year

Abundance

Preharvest recruits Spawners

Figure 69. Preharvest recruits and spawners versus broodyear for the Puyallup River Chinook salmon 

population, 1968–2002. 

91
CHINOOK SALMON

0

500

1000

1500

2000

2500

3000

3500

1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 70. Preharvest recruits and spawners versus broodyear for the White River Chinook salmon 

population, 1970–2002. 

0

5000

10000

15000

20000

25000

30000

1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 71. Preharvest recruits and spawners versus broodyear for the Nisqually River Chinook salmon 

population, 1968–2002. 

92
7. PUGET SOUND CHINOOK SALMON ESU 

0

5000

10000

15000

20000

25000

30000

1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 72. Preharvest recruits and spawners versus broodyear for the Skokomish River Chinook salmon 

population, 1987–2002. 

0

100

200

300

400

500

600

700

800

900

1960 1970 1980 1990 2000 2010

Year

Abundance

Preharvest Recruits Spawners

Figure 73. Preharvest recruits and spawners versus broodyear for the Dosewallips River Chinook salmon 

population, 1967–2002. 

93
CHINOOK SALMON

0

100

200

300

400

500

600

700

1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 74. Preharvest recruits and spawners versus broodyear for the Dungeness River Chinook salmon 

population, 1986–2002. 

0

1000

2000

3000

4000

5000

6000

1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 75. Preharvest recruits and spawners versus broodyear for the Elwha River Chinook salmon 

population, 1986–2001. 

94
7. PUGET SOUND CHINOOK SALMON ESU 

Updated Threats Information 

The Puget Sound TRT has estimated adult equivalent exploitation rates for each 

population of Chinook salmon in the ESU (Table 11). Exploitation rates are the proportion of 

the returning population that are caught in fisheries or are killed as a result of fishing activities 

(e.g., nonretention mortality). These harvest estimates include mortality from sport and 

commercial fisheries in the ocean, Puget Sound, and in rivers. Exploitation rate estimates are a 

function of coded-wire tag recoveries, escapement estimates, and estimates of incidental 

mortalities provided by the Chinook Technical Committee of the Pacific Salmon Commission 

(PSC 2001a, 2001b). These harvest rates are equivalent to exploitation rates provided by the 

CTC, but they are different from exploitation rates estimated by the Fishery Regulation 

Assessment Model (FRAM). 

Exploitation rates on Puget Sound Chinook salmon populations averaged 75% (median = 

85%; range 31–92%) in the earliest 5 years of data availability and have dropped to an average 

of 44% (median = 45; range 26–63%) in the most recent 5-year period. 

Table 11. Estimated broodyear adult-equivalent exploitation rates on populations of Puget Sound 

Chinook salmon. 

Population 

Data years 

(broodyear) 

Earliest 

5-year mean 

exploitation rate 

(%) 

Most recent 

5-year mean 

exploitation rate 

(%) 

North Fork Nooksack 1982–1998 43 26 

South Fork Nooksack 1982–1998 44 26 

Lower Skagit* 1969–1998 86 61 

Upper Skagit* 1969–1998 88 63 

Upper Cascade* 1982–1998 80 56 

Lower Sauk* 1969–1998 88 63 

Upper Sauk* 1979–1998 72 56 

Suiattle* 1979–1998 73 58 

North Fork Stillaguamish 1972–1998 89 40 

South Fork Stillaguamish 1972–1998 89 40 

Skykomish 1969–1998 86 49 

Snoqualmie 1969–1998 85 45 

North Lake Washington 1981–1998 40 27 

Cedar 1969–1998 52 31 

Green 1969–1998 82 57 

White 1972–1998 90 26 

Puyallup 1971–1998 53 30 

Nisqually 1977–1998 92 62 

Skokomish 1985–1998 90 31 

Dosewallips 1985–1998 92 38 

Dungeness 1984–1998 31 32 

Elwha 1984–1998 64 44 * The population-specific harvest rates for the Skagit River basin are in dispute; Puget Sound TRT, NOAA Fisheries 

Northwest Regional Office, and the Puget Sound comanagers are working to resolve different estimates resulting 

from the Pacific Salmon Commission (Chinook Technical Committee) and FRAM. 

95
CHINOOK SALMON

The Puget Sound TRT has amassed estimates of the total number of hatchery-origin 

Chinook salmon returning to streams (Table 12). For each population, these estimates include 

the total return—returns to natural spawning grounds and to hatchery racks within a population’s 

Table 12. Total estimated recent annual average returns of hatchery-produced Chinook salmon (adults 

returning to hatchery racks and to spawning grounds) and total releases of juvenile Chinook 

salmon in streams containing independent populations of Chinook salmon in Puget Sound. 

Sources: Puget Sound TRT (2002) and Waknitz (2002). 

Population 

Average annual return 

to stream 1987–2001

(minimum–maximum)a

Previous (1990–1994) average 

annual releases of Chinook 

salmon hatchery juveniles by 

life stage (in thousands) 

Most recent (1995–2001) 

average annual releases 

of Chinook salmon 

hatchery juveniles by 

life stage 

(in thousands) 

North Fork Nooksack 1,720 (0–9,179) 

South Fork Nooksack 1,254 (0–5,515) 

5,500 (4,763 fall; 737 

spring/summer) 

3,081 fall 

Lower Skagit 

Upper Skagit 

Upper Cascade 

Lower Sauk 

Upper Sauk 

Suiattle 

1,171 (70–4,110) 2,251 (1,292 fall; 491 spring, 468 

summer) 

754 (32 fall; 423 spring; 

299 summer) 

North Fork Stillaguamish 318 (2–777) 

South Fork Stillaguamishb NA 

NA 178 summer 

Skykomish 3,666 (824–8,530) 

Snoqualmie 2,921 (19–6,514) 

1,926 (1,316 fall; 

610 summer) 

2,574 (1,401 fall; 

1,173 summer)

North Lake Washingtonb NA 

Cedar NA 

2,349 fall 2,077 fall

Green 13,565 (3,211–23,014) 4,413 fall 3,681 fall 

Whiteb NA 

Puyallupb 2,048 (762–3,484) 

1,686 (1,672 fall, 

14 spring) 

1,695 (1,669 fall; 

26 spring) 

Nisquallyb 2,559 (0–13,481) NA 

70 fall in south 

Sound general 

NA 

Miscellaneous South Puget 

Sound streams 

NA 6,947 fall 6,411 fall 

Eastern Kitsap streams NA 2,851 (2,519 fall; 332 spring) 3,771 (3,447 fall; 

324 spring) 

Skokomishb 3,621 (294–8,816) 

Combined Dosewallipsb NA 

4,928 (4,637 fall; 291 spring) 6,856 (6,793 fall; 

63 spring) 

Dungenessb NA NA 1,283 spring 

Elwha 634 (97–2,089) 1,831 fall 2,482 fall a Hatchery rack-return data are not available for all streams. 

b Estimates of hatchery-origin Chinook salmon returning to spawn are not available. 

96
7. PUGET SOUND CHINOOK SALMON ESU 

geographic boundaries. These estimates do not account for possible strays of hatchery fish from 

outside the population’s boundaries. It is apparent from Table 12 that even populations of 

Chinook salmon in northern Puget Sound (not a hatchery production management area for 

comanagers) receive significant numbers of adult hatchery fish returning each year. The 

numbers of hatchery-origin juvenile Chinook salmon released into Puget Sound streams each 

year also are reported in Table 12. Average annual numbers of juvenile releases have declined 

since the time of the last status review (1990–1994 versus 1995–2001) in the Nooksack, Skagit, 

and Green river basins, and releases have remained roughly the same in the North Lake 

Washington/Cedar, White/Puyallup rivers, and south Puget Sound streams. In contrast, juvenile 

Chinook salmon releases have increased in the Snohomish and Elwha river basins, in eastern 

Kitsap Peninsula streams, and in Hood Canal. With the exception of the Skagit and 

Stillaguamish river basins, all major watersheds in Puget Sound receive annual releases of over a 

million (close to 7 million in Hood Canal) juvenile Chinook salmon. Hatchery stocks of 

Chinook salmon in Puget Sound have been categorized (SSHAG 2003) and are in Appendix A, 

Table A-1. 

Comparison with Previous Data 

Overall, the natural spawning escapement estimates for Puget Sound Chinook salmon 

populations are improved relative to those at the time of the previous status review of Puget 

Sound Chinook salmon conducted with data through 1997. The differences between population 

escapement estimates based on status assessments using data from 1997 and the present 

assessment using data through 2002 could be due to 1) revised pre-1997 data, 2) differences in 

which fish are counted as part of a population, 3) new information on the fraction of natural 

spawners that are hatchery fish, or 4) true differences reflected in new data on natural spawners 

obtained over the most recent 5 years. The median across populations of the most recent 5-year 

geometric mean of natural escapement for the same 22 populations through 1997 was N = 438 

(compared to N = 771 through 2002), and the range was 1–5,400. As was the case at the time of 

the previous status review, it is not possible to determine the status of the natural-origin, natural 

spawners in half the populations of Chinook salmon in Puget Sound. The most dramatic change 

in recent natural escapement estimates from the previous status assessment was in the Green 

River—the recent natural-origin escapement estimate is lower than the previous one by almost 

5,000 spawners. This apparent drop in natural escapement is probably due primarily to new 

information about the fraction of hatchery fish that are spawning naturally. 

Throughout the ESU, the estimates of trends in natural spawning escapements for Puget 

Sound Chinook salmon populations are similar to the previous status review of Puget Sound 

Chinook salmon conducted with data through 1997. Some populations exhibit improvements in 

trends relative to the last status assessment, and others show more significant declines. As stated 

above for escapement estimates, the differences in trend estimates between the previous status 

assessments using data from 1997 and the present assessment using data through 2002 could be 

due to 1) revised pre-1997 data, 2) differences in which fish are counted as part of a population, 

3) new information on the fraction of natural spawners that are hatchery fish, or 4) true 

differences reflected in new data on natural spawners obtained over the most recent 5 years. The 

median across populations of the long-term trend in natural spawners was a 1.1% decline per 

year through 1997, compared to a median estimate indicating a flat trend through 2002. Twelve 

97
CHINOOK SALMON

98

populations had declining long-term trends through 1997, and 10 populations have declining 

long-term trends through 2002. Short-term trends are generally more positive in recent years—

the median trend across 22 populations through 1997 was a 4% decline per year, and the median 

trend through 2002 was a 1.1% increase per year. Fourteen populations showed declining shortterm trends at the time of the previous status reviews, and only four populations exhibit declining 

short-term trends in recent years. Nevertheless, as stated above for interpreting abundance 

estimates, we lack information on the fraction of naturally spawning, hatchery-origin fish for 10 

of the 22 populations of Chinook salmon in Puget Sound, so our understanding of the trend in 

natural-origin spawners among populations across the ESU is incomplete. An illustration of how 

misleading trend estimates on total natural spawners can be for estimating trends in naturalorigin spawners can be found comparing the λ calculations assuming naturally spawning 

hatchery fish do (i.e., λ − Η1) or do not (i.e., λ − Η0) contribute naturally spawning offspring. 

For those 12 populations with information on the hatchery fraction of natural spawners in the 

ESU, 7 populations switched from an estimated positive short-term population growth rate to a 

negative rate when hatchery fish were assumed to contribute naturally spawning offspring. 

The spatial distribution of Chinook salmon populations with a strong component of 

natural-origin spawners in the Puget Sound ESU has not changed since the last status 

assessment. Populations containing significant numbers of natural-origin spawners whose status 

can be reliably estimated occur in the Skagit River basin, the South Fork Stillaguamish, and the 

Snohomish River basin. The remaining populations in mid- and south Puget Sound, Hood 

Canal, and the Strait of Juan de Fuca have significant (but nonquantifiable) fractions of hatcheryorigin spawners, so their contribution to spatial structure in the ESU is not possible to estimate. 

The change in diversity in the ESU from historical conditions also has not changed since 

the last status review. An estimated 31 independent populations of Chinook salmon occurred 

historically in the ESU, and 22 remain extant. All but one of the nine putatively extinct Chinook 

salmon stocks is an early run population (or component of a population). The loss of early run 

Chinook salmon stocks in Puget Sound represents an important loss of part of the evolutionary 

legacy of the historical ESU.
8. Lower Columbia River Chinook Salmon ESU 

Summary of Previous BRT Conclusions 

NMFS reviewed the status of the Lower Columbia River Chinook salmon ESU initially 

in 1998 (Myers et al. 1998) and updated it that same year (NMFS 1998a). In the 1998 update, 

the BRT noted several concerns for this ESU. The 1998 BRT was concerned that very few 

naturally self-sustaining populations of native Chinook salmon remained in the Lower Columbia 

River ESU. The 1998 BRT identified naturally reproducing (but not necessarily self-sustaining) 

populations: the Lewis and Sandy rivers bright fall runs and the tule fall runs in the Clackamas, 

East Fork Lewis, and Coweeman rivers. These populations were identified as the only bright 

spots in the ESU. The previous BRT did not consider the few remaining populations of springrun Chinook salmon in the ESU to be naturally self-sustaining because of either small size, 

extensive hatchery influence, or both. The previous BRT felt that the dramatic declines and 

losses of spring-run Chinook salmon populations in the Lower Columbia River ESU represented 

a serious reduction in life history diversity in the region. The team felt that the presence of 

hatchery Chinook salmon in this ESU posed an important threat to the persistence of the ESU 

and obscured trends in abundance of native fish. The team noted that habitat degradation and 

loss due to extensive hydropower development projects, urbanization, logging, and agriculture 

threatened the Chinook salmon spawning and rearing habitat in the lower Columbia River. A 

majority of the 1998 BRT concluded that the Lower Columbia River ESU was likely to become 

endangered in the foreseeable future. A minority felt that Chinook salmon in this ESU were not 

presently in danger of extinction, nor were they likely to become so in the foreseeable future. 

Listing status: Threatened. 

New Data and Updated Analyses 

New data acquired for this report includes spawner abundance estimates through 2001, 

new estimates of the fraction of hatchery spawners, and harvest estimates. In addition, WDFW 

provided estimates of historical abundance. Information on recent hatchery releases was also 

obtained. New analyses include the designation of relatively demographically independent 

populations, recalculation of previous BRT metrics with additional years of data, estimates of 

median annual growth rate (λ) under different assumptions about the reproductive success of 

hatchery fish, and estimates of current and historically available kilometers of streams. 

Historical Population Structure 

As part of its effort to develop viability criteria for Lower Columbia River ESU Chinook 

salmon, the Willamette/Lower Columbia Technical Recovery Team (WLC-TRT) has identified 

historically demographically independent populations (Myers et al. 2002). Population 

boundaries are based on an application of VSPs defined in McElhany et al. (2000). Myers et al. 

99 
CHINOOK SALMON

hypothesized that the ESU historically consisted of 20 fall-run populations (tules), 2 late-fall-run 

populations (brights), and 9 spring-run populations for a total of 31 populations (Figures 76 and 

77). The populations identified in Myers et al. 2002 are used as the units for the new analyses in 

this report. 

The WLC-TRT partitioned Lower Columbia River ESU Chinook salmon populations 

into a number of strata based on major life history characteristics and ecological zones 

(McElhany et al. 2003). The WLC-TRT concluded that a viable ESU would need multiple 

viable populations in each strata. The strata and associated populations are identified in 

Table 13. 

Abundance and Trends 

Data sources for abundance time series and related data are in Appendix A, Table A-2. 

The recent abundance of both total and natural-origin spawners, and recent fraction of hatcheryorigin spawners, for Lower Columbia River ESU Chinook salmon populations are summarized 

Figure 76. Historical independent Lower Columbia River ESU early and late-fall-run Chinook salmon 

populations. Source: Myers et al. (2002). 

100
8. LOWER COLUMBIA RIVER CHINOOK SALMON ESU 

Figure 77. Historical, independent, Lower Columbia River ESU spring-run Chinook salmon populations. 

Source: Myers et al. (2002). 

in Table 13. Natural-origin fish had parents that spawned in the wild, as opposed to hatcheryorigin fish, whose parents were spawned in a hatchery. The abundances of natural-origin 

spawners range from near extirpation for most of the spring-run populations to over 7,841 for the 

Lewis River bright population. The majority of the fall-run tule populations have a substantial 

fraction of hatchery-origin spawners in the spawning areas and may be sustained largely by 

hatchery production. Exceptions are the Coweeman population and the East Fork Lewis portion 

of the Lewis River/Salmon Creek population, which have few hatchery fish spawning on the 

natural spawning areas. These two populations have recent geometric mean natural-origin 

abundance estimates of 274 and 256 spawners respectively. Although quantitative information is 

not yet available, preliminary examination of scales indicates that almost all current spring-run 

spawners in the Washington part of this ESU are of hatchery origin.8

 The majority of the springrun populations have been extirpated, largely as the result of dams blocking access to their highelevation habitat. The two bright Chinook populations (i.e., Lewis and Sandy) have relatively 

high abundances, particularly the Lewis. 

 

8

 D. Rawding, Washington Department of Fish and Wildlife, Vancouver, WA. Pers. commun., 18 March 2003. 

101
Table 13. Historical population structure and abundance statistics for Lower Columbia ESU Chinook salmon populations, 

ecological zone. 

Total spawners Natural-origin spawn

Life historyaecological zoneb Population 

Years for 

recent meansc

Recent 

geometric 

mean 

Recent 

arithmetic 

mean 

Recent 

geometric 

mean 

Recen

arithm

mean 

Fall run 

Youngs Bay No data Grays River 1997–2001 99 152 59 89 Big Creek No data Elochoman River 1997–2001 676 1,074 186 289 Clatskanie River No data Mill, Abernathy, Germany creeks 

1997–2001 734 1,197 362 626 

Coastal 

Scappoose Creek No data Coweeman River 1997–2001 274 469 274 469 Lower Cowlitz River 1996–2000 1,562 1,626 463 634 Upper Cowlitz River 2001 5,682 Toutle River No data Kalama River 1997–2001 2,931 3,138 655 1,214 Salmon Creek/Lewis River 1997–2001 

(East Fork 

data only 

256 294 256 294 

Clackamas River 1998–2001 40 56 No dWashougal River 1997–2001 3,254 3,364 1,130 1,277 

Cascade 

Sandy River 1997–2001 183 216 No dLower gorge tributaries No data Upper gorge tributaries 1997–2001 

(Wind River 

data only) 

136 216 109 198 

Hood River 1994–1998 18 21 No d

Columbia Gorge 

Big White Salmon River 1997–2001 334 602 218 462 

102
Table 13 continued. Historical population structure and abundance statistics for Lower Columbia ESU Chinook salmon p

history and ecological zone. 

Total spawners Natural-origin spawn

Life historyaecological zoneb Population 

Years for 

recent meansc

Recent 

geometric 

mean 

Recent 

arithmetic 

mean 

Recent 

geometric 

mean 

Recen

arithm

mean 

Late fall (bright) 

Cascade Sandy River 1997–2001 504 773 778 750 

North Fork Lewis River 1997–2001 7,841 8,834 6,818 7,828 

Spring run 

Upper Cowlitz River Cispus River Tilton River 

2001 1,787 No d

Toutle River No data Kalama River 1997–2001 98 185 No dLewis River 1997–2001 347 363 No d

Cascade 

Sandy River No data 

Columbia Gorge Big White Salmon River No data (no fish?) 

Hood River 1994–1998 51 61 No d

a Life history types are based on traits related to run timing. b Ecological zones are based on ecological community and hydrodynamic patterns. c Time series used for the summary statistics are referenced in Appendix A, Table A-2. d Natural-origin spawners had parents that spawned in the wild, as opposed to hatchery-origin fish, whose parents were spawned in a ha

103
CHINOOK SALMON

Access to the habitat of the historical upper Cowlitz, Cispus, and Tilton populations is 

blocked by the Mayfield, Mossy Rock, and Cowlitz Falls dams. A relatively large number of 

both spring- and fall-run Chinook salmon are currently released as part of a reintroduction 

program to establish Chinook above Cowlitz Falls Dam (Serl and Morrill 2002). The adults for 

the reintroduction program are collected at the Cowlitz Salmon Hatchery, and the vast majority 

of the Chinook trucked above Cowlitz Falls are believed to be of hatchery origin, though 

marking of hatchery fish is not complete and a quantitative assessment has not been undertaken. 

Downstream survival of juvenile Chinook through the dams and reservoirs is considered 

negligible, so juveniles are collected at Cowlitz Falls and trucked downstream. The current 

collection efficiency of juveniles at Cowlitz Falls is considered too low for the reintroduction to 

be self-sustaining.9

Where data are available, the abundance time-series information for each population is 

presented in Figures 78–105. Three types of time-series figures are presented. The first type 

plots abundance against time (Figures 78–81, 83, 85, 87, 89, 91, 93, 95–97, and 99–102). Where 

possible, two lines are presented on the abundance figure: one line is the estimated total number 

0

500

1,000

1,500

2,000

2,500

3,000

1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Total spawners

Figure 78. Big White Salmon River fall-run Chinook salmon total spawner abundance (hatchery and 

natural origin), 1967–2001. 

 

9

D. Rawding, Washington Department of Fish and Wildlife, Vancouver, WA. Pers. commun., 28 March 2003. 

104
8. LOWER COLUMBIA RIVER CHINOOK SALMON ESU 

0

200

400

600

800

1,000

1,200

1,400

1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Total spawners

Figure 79. Clackamas River fall-run Chinook salmon total spawner abundance (hatchery and natural 

origin), 1967–2001. 

0

500

1,000

1,500

2,000

2,500

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Total spawners

Figure 80. Coweeman River fall-run Chinook salmon total spawner abundance (almost all spawners are 

of natural origin), 1964–2001. 

105
CHINOOK SALMON

0

5,000

10,000

15,000

20,000

25,000

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total spawners Natural-origin spawners

Figure 81. Lower Cowlitz River fall-run Chinook salmon spawner abundance, 1964–2000. 

0

1,000

2,000

3,000

4,000

5,000

1978 1981 1984 1987 1990 1993 1996 1999 2002

Broodyear

Abundance

Preharvest recruits Spawners

Figure 82. Estimate of fall-run Chinook preharvest recruits and spawners in the Cowlitz River, 

1980–2001. 

106
8. LOWER COLUMBIA RIVER CHINOOK SALMON ESU 

0

100

200

300

400

500

600

700

1978 1983 1988 1993 1998 2003

Year

Total spawners

Figure 83. East Fork Lewis River fall-run Chinook salmon total spawner abundance (almost all spawners 

are of natural origin), 1980–2001. 

0

200

400

600

800

1,000

1,200

1978 1981 1984 1987 1990 1993 1996 1999 200

Broodyear

Abundance

Preharvest recruits Spawners

Figure 84. Estimate of fall-run Chinook salmon spawner abundance preharvest recruits and spawners in 

the East Fork Lewis River, 1980–2001. 

107
CHINOOK SALMON

0

500

1,000

1,500

2,000

2,500

1962 1967 1972 1977 1982 1987 1992 1997 2002

Year

Abundance

Total spawners Natural-origin spawners

Figure 85. Elochoman River fall-run Chinook salmon spawner abundance, 1964–2001. 

0

500

1,000

1,500

2,000

2,500

1978 1981 1984 1987 1990 1993 1996 1999 2002

Broodyear

Abundance

Preharvest recruits Spawners

Figure 86. Estimate of fall-run Chinook salmon preharvest recruits and spawners in the Elochoman 

River, 1980–2001. 

108
8. LOWER COLUMBIA RIVER CHINOOK SALMON ESU 

0

500

1,000

1,500

2,000

2,500

3,000

1962 1967 1972 1977 1982 1987 1992 1997 2002

Year

Abundance

Total spawners Natural-origin spawners

Figure 87. Grays River fall-run Chinook salmon spawner abundance, 1964–2001. 

0

500

1,000

1,500

2,000

2,500

1978 1981 1984 1987 1990 1993 1996 1999 2002

Broodyear

Abundance

Preharvest recruits Spawners

Figure 88. Estimate of Grays River fall-run Chinook salmon preharvest recruits and spawners, 

1980–2001. 

109
CHINOOK SALMON

0

5,000

10,000

15,000

20,000

25,000

1962 1967 1972 1977 1982 1987 1992 1997 2002

Year

Abundance

Total spawners Natural-origin spawners

Figure 89. Kalama River fall-run Chinook salmon spawner abundance, 1964–2001. 

0

5,000

10,000

15,000

20,000

25,000

1978 1981 1984 1987 1990 1993 1996 1999 2002

Broodyear

Abundance

Preharvest recruits Spawners

Figure 90. Estimate of Kalama River fall-run Chinook salmon preharvest recruits and spawners, 

1980–2001. 

110
8. LOWER COLUMBIA RIVER CHINOOK SALMON ESU 

0

5,000

10,000

15,000

20,000

25,000

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total spawners Natural-origin spawners

Figure 91. Lewis River late-fall-run (bright) Chinook salmon spawner abundance, 1964–2001. 

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

1978 1981 1984 1987 1990 1993 1996 1999 2002

Broodyear

Abundance

Preharvest recruits Spawners

Figure 92. Estimate of Lewis River late-fall-run (bright) Chinook salmon preharvest recruits and 

spawners, 1980–2001. 

111
CHINOOK SALMON

0

1,000

2,000

3,000

4,000

5,000

6,000

1978 1983 1988 1993 1998 2003

Year

Abundance

Total spawners Natural-origin spawners

Figure 93. Mill, Germany, and Abernathy creeks fall-run Chinook salmon spawner abundance, 

1980–2001. 

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

1978 1983 1988 1993 1998

Broodyear

Abundance

Preharvest recruits Spawners

Figure 94. Estimate of Mill, Germany, and Abernathy creeks fall-run Chinook salmon preharvest recruits 

and spawners, 1980–2001. 

112
8. LOWER COLUMBIA RIVER CHINOOK SALMON ESU 

0

500

1,000

1,500

2,000

1986 1988 1990 1992 1994 1996 1998 2000 2002

Year

Total spawners

Figure 95. Sandy River fall-run Chinook salmon spawner abundance, 1988–2001. 

0

500

1,000

1,500

2,000

2,500

1982 1985 1988 1991 1994 1997 2000

Year

Total spawners

Figure 96. Sandy River late-fall-run (bright) Chinook salmon spawner abundance, 1984–2001. 

113
CHINOOK SALMON

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

5,000

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total spawners Natural-origin spawners

Figure 97. Washougal River fall-run Chinook salmon spawner abundance, 1964–2001. 

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

1978 1981 1984 1987 1990 1993 1996 1999 2002

Broodyear

Abundance

Preharvest recruits Spawners

Figure 98. Estimate of Washougal River fall-run Chinook salmon preharvest recruits and spawners 

1980–2001. 

114
8. LOWER COLUMBIA RIVER CHINOOK SALMON ESU 

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

1962 1967 1972 1977 1982 1987 1992 1997 2002

Year

Total abundance

Figure 99. Wind River fall-run Chinook salmon total spawner abundance (hatchery and natural origin), 

1964–2001. 

0

5,000

10,000

15,000

20,000

25,000

30,000

1978 1983 1988 1993 1998

Year

Abundance

Total Natural origin

Figure 100. Cowlitz River spring-run Chinook salmon total spawner abundance below Mayfield Dam 

(the majority of spawners are of hatchery origin), 1980–2001. 

115
CHINOOK SALMON

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

1978 1983 1988 1993 1998

Year

Abundance

Total run size Natural-origin spawners

Figure 101. Kalama River spring-run Chinook salmon total spawners (the majority of spawners are of 

hatchery origin), 1980–2001. 

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

1978 1981 1984 1987 1990 1993 1996 1999 2002

Year

Total spawners

Figure 102. Lewis River spring-run Chinook salmon total spawner abundance below Merwin Dam (the 

majority of spawners are of hatchery origin), 1980–2001. 

116
8. LOWER COLUMBIA RIVER CHINOOK SALMON ESU 

0

20

40

60

80

100

120

1970 1975 1980 1985 1990 1995 2000 2005

Year

Fish per mile 

Figure 103. Youngs Bay Chinook salmon per mile, 1972–2001. Fish per mile 

0

200

400

600

800

1000

1960 1970 1980 1990 2000 2010

Year

Figure 104. Big Creek Chinook salmon per mile, 1970–2001. 

117
CHINOOK SALMON

Fish per mile 

0

200

400

600

800

1000

1960 1970 1980 1990 2000 2010

Year

Figure 105. Clatskanie River Chinook salmon per mile, 1970–2001. 

of spawners, the other is the estimated number of fish of natural origin. In many cases, data were 

not available to distinguish between natural- and hatchery-origin spawners, so only total spawner 

information is presented. This type of figure can give a sense of the abundance levels, overall 

trend, variability patterns, and fraction of hatchery-origin spawners. A high fraction of hatcheryorigin spawners indicates that the population may potentially be sustained by hatchery 

production, not the natural environment. It is important to note that estimates of fraction of 

hatchery-origin fish are highly uncertain because the hatchery marking rate for Lower Columbia 

River ESU fall-run Chinook salmon is generally only a few percent, and expansion to population 

hatchery fraction is based on only a handful of recovered marked fish (WLC-TNT 2002).10

The second type of time series figure displays fish-per-mile data. For three fall-run 

Chinook populations in Oregon watersheds, total abundance estimates are not available, but a 

fish-per-mile time series exists (Figures 103–105). There are no estimates of the fraction of 

hatchery-origin spawners in these fish-per-mile time series, but the percentage may be high given 

the large number of hatchery fish released and the high fraction of hatchery-origin spawners 

estimated in Washington watersheds, directly across the Columbia River. The lack of 

information on hatchery fraction reduces the value of these time series for evaluating extinction 

risk. 

The third type of time-series figure presents the total number of spawners (natural and 

hatchery origin) and the estimated number of preharvest recruits produced by those spawners 

against time (Figures 82, 84, 86, 88, 90, 92, and 94). Dividing the number of preharvest recruits 

by the number of spawners for the same time period would yield an estimate of the preharvest 

recruits per spawner for the broodyear. Spawners are taken as the sum of hatchery- and naturalorigin spawners. This type of figure requires harvest and age structure information and therefore 

could be produced for only a limited number of populations. This type of figure can indicate 

whether preharvest recruitment has changed and the degree to which harvest management has 

 

10P. McElhany, NMFS, Northwest Fisheries Science Center, Seattle, WA. 

118
8. LOWER COLUMBIA RIVER CHINOOK SALMON ESU 

the potential to recover populations. If the preharvest recruitment line is consistently below the 

spawner line, the population would not be replacing itself, even in the absence of all harvest. 

Summary statistics on population trends and growth rate are presented in Tables 14–16. 

The methods for estimating trends and growth rate (λ) are described in Section 2, Methods. 

Trends are calculated on total spawners, both hatchery and natural origin. The λ estimate is 

calculated using two different assumptions about the reproductive success of hatchery-origin 

spawners. In one analysis, hatchery-origin spawners are assumed to have zero reproductive 

success; in the other analysis, hatchery-origin spawners are assumed to have a reproductive 

success equal to that of natural-origin spawners. Because λ is only calculated for time series for 

which the fraction of hatchery-origin spawners is known, most of the long-term trend estimates 

use data dating from 1980, even though the abundance time series of total spawners may extend 

earlier than 1980. The majority of populations have a long-term trend of less than 1, indicating 

the population is in decline. In addition, for most populations there is a high probability that the 

true trend/growth rate is less than 1 (Table 16). However, in general there is a great deal of 

uncertainty about the growth rate, as the large confidence intervals indicate. The uncertainty 

about growth rate is generally higher for Chinook salmon than for other lower Columbia River 

anadromous salmonids because of the high variability observed in the time series. Assuming 

that hatchery-origin fish have a reproductive success equal to natural-origin fish, analysis 

indicates a negative long-term growth rate for all of the populations except the Coweeman River 

fall run. The Coweeman fall run had very few hatchery-origin spawners (Table 14). Potential 

reasons for these declines were cataloged in previous status reviews: they include habitat 

degradation, overharvest, deleterious hatchery practices, and climate-driven changes in marine 

survival. 

The Lewis River bright population is considered the healthiest in the ESU. The 

population is significantly larger than any other population in the ESU; in fact, it is larger than 

any salmon population in the Columbia River basin except for Hanford Reach Chinook. The 

Lewis bright Chinook harvest has been managed to an escapement target of 5,700, which has 

been met every year for which data are available except 1999 (Figure 91). The preharvest 

recruits exceeded spawners in all years for which data are available except two (Figure 92). 

There has been a hatchery program for Lewis River brights, but hatchery-origin spawners have 

generally comprised less than 10% of the spawning population over the time series. These 

indicators all suggest a relatively healthy population. However, the long-term population trend 

estimate is negative (Table 14), and it is not clear the extent to which this reflects management 

decisions to harvest closer to the escapement goal, as compared to declining productivity over 

the time series. The population is also geographically confined to a reach that is only a few 

kilometers long and located immediately below Merwin Dam, where it is affected by the flow 

management of the hydrosystem. This limited spatial distribution is a potential risk factor. 

119
CHINOOK SALMON

Table 14. Long-term trend and growth rate for a subset of Lower Columbia River ESU Chinook salmon 

populations for which adequate data are available (95% confidence intervals are in parentheses). 

Long-term median growth rate 

(λ) 

Run 

 population 

Years for 

long-term 

trenda

Long-term 

trend of total 

spawnersb

Years for 

long-term λc Hatchery = 0d Hatchery = wilde

Fall run 

Grays River 1964–2001 0.965 

(0.928–1.003) 

1980–2001 0.944 

(0.739–1.204) 

0.844 

(0.660–1.081) 

Elochoman River 1964–2001 1.019 

(0.990–1.048) 

1980–2001 1.037 

(0.813–1.323) 

0.800 

(0.625–1.024) 

Mill, Abernathy, 

Germany creeks 

1980–2001 0.965 

(0.909–1.024) 

1980–2001 0.981 

(0.769–1.252) 

0.829 

(0.648–1.006) 

Coweeman River 1964–2001 1.046 

(1.018–1.075) 

1980–2001 1.092 

(0.855–1.393) 

1.091 

(0.852–1.396) 

Lower Cowlitz River 1964–2000 0.951 

(0.933–0.968) 

1980–2000 0.998 

(0.776–1.282) 

0.682 

(0.529–0.879) 

Kalama River 1964–2001 0.994 

(0.973–1.016) 

1980–2001 0.973 

(0.763–1.242) 

0.818 

(0.639–1.048) 

Salmon Creek/Lewis 

River 

1980–2001 0.981 

(0.949–1.014) 

1980–2001 0.984 

(0.771–1.256) 

0.979 

(0.765–1.254) 

Clackamas River 1967–2001 0.937 

(0.910–0.965) 

No hatchery fraction data 

Washougal River 1964–2001 1.088 

(1.002–1.115) 

1980–2001 1.025 

(0.803–1.308) 

0.815 

(0.637–1.045) 

Upper gorge 

tributaries 

1964–2001 

(Wind 

only) 

0.935 

(0.892–0.979) 

1980–2001 0.959 

(0.751–1.224) 

0.955 

(0.746–1.223) 

Big White Salmon 

River 

1967–2001 0.941 

(0.912–0.971) 

1980–2001 0.963 

(0.755–1.229) 

0.945 

(0.738–1.210) 

Late-fall run (brights) 

Sandy River 1984–2001 0.946 

(0.880–1.014) 

1984–2001 0.943 

(0.715–1.243) 

0.935 

(0.706–1.237) 

North Fork Lewis 

River 

1964–2001 0.992 

(0.980–1.008) 

1980–2001 0.968 

(0.756–1.204) 

0.948 

(0.741–1.214) 

Spring run 

 Upper Cowlitz River 1980–2001 0.994 

(0.942–1.064) 

No hatchery fraction data (presumed high) 

 Kalama River 1980–2001 0.945 

(0.840–1.064 

No hatchery fraction data (presumed high) 

 Lewis River 1980–2001 0.935 

(0.879–0.995) 

No hatchery fraction data (presumed high) 

a The long-term analysis used the entire data set. 

b The trend estimate is for total spawners and includes both natural- and hatchery-origin fish. c The λ calculation is an estimate of what the natural growth rate would have been after accounting for hatcheryorigin spawners. The λ estimate is calculated under two hypotheses about the reproductive success of hatcheryorigin spawners. 

d Hatchery fish are assumed to have zero reproductive success. 

e Hatchery fish are assumed to have the same relative reproductive success as natural-origin fish. 

120
8. LOWER COLUMBIA RIVER CHINOOK SALMON ESU 

Table 15. Short-term trend and growth rate for a subset of Lower Columbia River ESU Chinook salmon 

populations for which adequate data are available (95% confidence intervals are in parentheses). 

Short-term median growth rate 

(λ)

c

Run 

 population 

Years for 

short-term 

trenda

Short-term 

trend of total 

spawnersb

Years for 

short-term λ Hatchery = 0d

Hatchery = 

wilde

Fall run 

Grays River 1990–2001 1990–2001 1.004 

(0.787–1.282) 

0.898 

(0.701–1.150)

 Elochoman River 1990–2001 

1.086 

(0.840–1.405) 

1.154 

(0.988–1.347) 

1990–2001 1.119 

(0.877–1.428) 

0.869 

(0.679–1.113)

Mill, Abernathy, 

Germany creeks 

1990–2001 0.974 

(0.833–1.139) 

1990–2001 0.993 

(0.778–1.268) 

0.823 

(0.643–1.054)

Coweeman River 1990–2001 0.985 

(0.816–1.139) 

1990–2001 0.977 

(0.765–1.247) 

0.977 

(0.763–1.251)

Lower Cowlitz 

River 

1990–2000 1.031 

(0.969–1.097) 

1990–2000 1.231 

(0.873–1.443) 

0.782 

(0.607–1.009)

Kalama River 1990–2001 0.996 

(0.898–1.104) 

1990–2001 0.944 

(0.740–1.205) 

0.799 

(0.624–1.022)

Salmon Creek/ 

Lewis River 

1990–2001 1.017 

(0.929–1.114) 

1990–2001 1.027 

(0.805–1.311) 

1.027 

(0.802–1.315)

Clackamas River 1990–2001 0.799 

(0.677–0.945) 

1990–2001 No hatchery fraction data 

Washougal River 1990–2001 1.009 

(0.961–1.058) 

1990–2001 0.985 

(0.722–1.257) 

0.769 

(0.600–0.989)

Upper gorge 

tributaries 

1990–2001 1.291 

(0.943–1.769) 

1990–2001 1.246 

(0.976–1.590) 

1.235 

(0.964–1.581)

Big White Salmon 

River 

1990–2001 1.106 

(0.899–1.361) 

1990–2001 1.057 

(0.828–1.348) 

1.013 

(0.791–1.297)

Late-fall run (brights) 

Sandy River 1990–2001 0.915 

(0.796–1.052) 

1990–2001 0.919 

(0.697–1.212) 

0.912 

(0.689–1.207)

North Fork Lewis 

River 

1990–2001 0.969 

(0.889–1.056) 

1990–2001 0.966 

(0.754–1.236) 

0.945 

(0.738–1.210)

Spring run 

 Upper Cowlitz 

River 

1990–2001 1.011 

(0.891–1.148) 

1990–2001 No hatchery fraction data 

 Kalama River 1990–2001 1.080 

(0.880–1.326) 

1990–2001 No hatchery fraction data 

 Lewis River 1990–2001 0.857 

(0.783–0.937) 

1990–2001 No hatchery fraction data 

a

 Short-term data sets include data from 1990 to the most recent available year. 

b

 The trend estimate is for total spawners and includes both natural- and hatchery-origin fish. c

 The λ calculation is an estimate of what the natural growth rate would have been after accounting for hatcheryorigin spawners. The λ estimate is calculated under two hypotheses about the reproductive success of hatcheryorigin spawners. 

d

 Hatchery fish are assumed to have zero reproductive success. 

e

 Hatchery fish are assumed to have the same relative reproductive success as natural-origin fish. 

121
CHINOOK SALMON

Table 16. Probability that the long-term abundance trend or growth rate is less than 1 for a subset of 

Lower Columbia River ESU Chinook salmon populations. 

Long-term analysis Short-term analysis 

Probability λ < 1 Probability λ < 1 

Run 

 population 

Probability 

trend 

< 1 

Hatchery 

= 0 

Probability 

trend < 1 

Probability 

Trend 

< 1 

Hatchery 

= 0a

Hatchery 

= wildb

Fall run 

Grays River 0.965 0.715 0.947 0.245 0.491 0.710 

Elochoman River 0.099 0.373 0.967 0.033 0.270 0.765 

Mill, Abernathy, 

Germany creeks 

0.887 0.581 0.973 0.643 0.514 0.833 

Coweeman River 0.001 0.194 0.196 0.570 0.556 0.556 

Lower Cowlitz River 1.000 0.510 0.510 0.148 0.216 0.952 

Kalama River 0.710 0.612 0.612 0.536 0.704 0.962 

Salmon Creek/Lewis 

River 

0.876 0.663 0.663 0.340 0.331 0.331 

Clackamas River 1.000 No hatchery fraction data 0.993 No hatchery fraction data 

Washougal River 0.000 0.323 0.323 0.350 0.556 0.989 

Upper gorge tributaries 0.997 0.612 0.612 0.050 0.137 0.148 

Big White Salmon 

River 

1.000 0.623 0.623 0.151 0.405 0.476 

Late-fall run (brights) 

Sandy River 0.994 0.833 0.833 0.906 0.828 0.849 

North Fork Lewis 

River 

0.817 0.800 0.800 0.785 0.733 0.841 

Spring run 

 Upper Cowlitz River 0.591 No hatchery fraction data 0.423 No hatchery fraction data 

 Kalama River 0.834 No hatchery fraction data 0.210 No hatchery fraction data 

 Lewis River 0.993 No hatchery fraction data 0.998 No hatchery fraction data a Hatchery-origin fish are assumed to have zero reproductive success. 

b Hatchery-origin fish are assumed to have reproductive success equivalent to that of natural-origin fish. 

EDT-Based Estimates of Historical Abundance 

The WDFW has conducted analyses of the Lower Columbia River ESU Chinook salmon 

populations using the EDT (ecosystem and diagnosis treatment) model (Busack and Rawding 

2003). The EDT model attempts to predict fish population performance based on input 

information about reach-specific habitat attributes (http://www.olympus.net/community/ 

dungenesswc/EDT-primer.pdf). WDFW populated this model with estimates of historical 

habitat conditions that produced the estimates of average historical abundance shown in Table 

17. There is a great deal of unquantified uncertainty in the EDT historical abundance estimates, 

which should be considered when interpreting these data. In addition, the habitat scenarios 

122
8. LOWER COLUMBIA RIVER CHINOOK SALMON ESU 

Table 17. Estimate of historical abundance based on the WDFW’s EDT analysis of equilibrium 

abundance under historical habitat conditions. Source: Busack and Rawding (2003). 

Population 

EDT estimate of 

historical abundance 

Grays River fall run 2,477 

Coweeman River fall run 4,971 

Lower Cowlitz River fall run 53,956 

Toutle River fall run 25,392 

Kalama River fall run 2,455 

Lewis River fall run (East Fork only) 4,220 

Lewis River brights 43,371 

Washougal River fall run 7,518 

Upper gorge tributaries fall run (Wind River only) 2,363 

Toutle River spring run 2,901 

Kalama River spring run 4,178 

evaluated as “historical” may not reflect historical distributions, because some areas that were 

historically accessible, but are currently blocked by large dams, are omitted from the analyses; 

and some areas that were historically inaccessible, but are recently passable because of human 

intervention, are included.

The EDT outputs are provided here to give a sense of the historical abundance of 

populations relative to each other and an estimate of the historical abundance relative to the 

current abundance. 

Loss of Habitat from Barriers 

Steel and Sheer (2003) conducted an analysis to assess the number of stream kilometers 

historically and currently available to salmon populations in the lower Columbia River (Table 

18). Stream kilometers usable by salmon are determined based on simple gradient cutoffs and 

the presence of impassable barriers. This approach will overestimate the number of usable 

stream kilometers, because it does not consider habitat quality (other than gradient). However, 

the analysis does indicate that for some populations (particularly spring run) currently accessible 

stream habitat kilometers are greatly reduced from historical conditions. 

New Hatchery and ESU Information 

Recent Hatchery Releases 

Updated information on Chinook hatchery releases in the ESU is provided in Appendix 

A, Table A-3. These data indicate a high level of Chinook salmon hatchery production in the 

lower Columbia River. Categorizations of Lower Columbia River ESU hatchery stocks 

(SSHAG 2003) can be found in Appendix A, Table A-1. 

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CHINOOK SALMON

Table 18. Loss of habitat due to barriers in the Lower Columbia River Chinook salmon ESU. 

Population 

Potential 

current habitat 

(km)a

Potential 

historical 

habitat (km)b

Current to 

historical 

habitat ratio 

(%)c

Youngs Bay fall run 178 195 91 

Grays River fall run 133 133 100 

Big Creek fall run 92 129 71 

Elochoman River fall run 85 116 74 

Clatskanie River fall run 159 159 100 

Mill, Abernathy, and Germany 

creeks fall run 117 123 96 

Scappoose Creek fall run 122 157 78 

Coweeman River 61 71 86 

Lower Cowlitz River fall run 418 919 45 

Upper Cowlitz River fall run 

Toutle River fall run 217 313 69 

Kalama River fall run 78 83 94 

Salmon Creek/Lewis River fall run 438 598 73 

Clackamas River fall run 568 613 93 

Washougal River fall run 84 164 51 

Sandy River fall run 227 286 79 

Lower gorge tributaries fall run 34 35 99 

Upper gorge tributaries fall run 23 27 84 

Hood River fall run 35 35 100 

Big White Salmon River fall run 0 71 0 

Sandy River late fall run (bright) 217 225 96 

North Fork Lewis River late fall run 

(bright) 87 166 52 

Upper Cowlitz spring run 4 276 1 

Cispus River spring run 0 76 0 

Tilton River spring run 0 93 0 

Toutle River spring run 217 313 69 

Kalama River spring run 78 83 94 

Lewis River spring run 87 365 24 

Sandy River spring run 167 218 77 

Big White Salmon spring run 0 232 0 

Hood River spring run 150 150 99 

Total 4,075 6,421 63 a The potential current habitat is the kilometers of stream with a gradient between 0.5% and 4%, below all 

currently impassable barriers. 

b The potential historical habitat is stream kilometers with a gradient between 0.5% and 4%, below historically 

impassable barriers. 

c The current to historical habitat ratio is the percent of the historical habitat that is currently available. 

124
8. LOWER COLUMBIA RIVER CHINOOK SALMON ESU 

Comparison with Previous Data 

The ESU exhibits three major life history types: fall run (tules), late-fall run (brights), and 

spring run. The ESU spans three ecological zones: coastal (rain-driven hydrograph), western 

Cascade (snow- or glacial-driven hydrograph), and Columbia Gorge (transitioning to drier 

interior Columbia River basin ecological zones). The fall-run Chinook salmon populations are 

currently dominated by large-scale hatchery production, relatively high harvest, and extensive 

habitat degradation (discussed in previous status reviews). The Lewis River late-fall-run 

Chinook salmon population is the healthiest in the ESU and has a reasonable probability of being 

self-sustaining. The spring-run populations are largely extirpated as the result of dams, which 

block access to their high-elevation habitat. Abundances have largely declined since the last 

status review update (1998), and trend indicators for most populations are negative, especially if 

hatchery fish are assumed to have a reproductive success equivalent to that of natural-origin fish. 

However, 2001 abundance estimates increased over the previous few years for most Lower 

Columbia River ESU Chinook salmon populations, and preliminary indications are that 2002 

abundance also increased.11 Many salmon populations in the Pacific Northwest have shown 

increases in abundance over the last few years, and the relationship of these increases to potential 

changes in marine survival are discussed in the introduction to this report. 

 

11See Footnote 9. 

125
9. Upper Willamette River Chinook Salmon ESU 

Summary of Previous BRT Conclusions 

NMFS reviewed the status of the Upper Willamette River Chinook salmon ESU initially 

in 1998 (Myers et al. 1998) and updated it that same year (NMFS 1998a). In the 1998 update, 

the BRT noted several concerns for this ESU. The previous BRT was concerned about the few 

remaining populations of spring-run Chinook salmon in the Upper Willamette River ESU, and 

the high proportion of hatchery fish in the remaining runs. The BRT noted with concern that the 

Oregon Department of Fish and Wildlife (ODFW) was able to identify only one remaining 

naturally reproducing population in this ESU, the spring-run Chinook salmon in the McKenzie 

River. The previous BRT was concerned about severe declines in short-term abundance that 

occurred throughout the ESU, and that the McKenzie River population had declined 

precipitously, indicating that it may not be self-sustaining. The 1998 BRT also noted that the 

potential for interactions between native spring-run and introduced fall-run Chinook salmon had 

increased relative to historical times due to fall-run Chinook salmon hatchery programs and the 

laddering of Willamette Falls. The previous BRT partially attributed the declines in spring-run 

Chinook salmon in the Upper Willamette River ESU to the extensive habitat blockages caused 

by dam construction. The previous BRT was encouraged by efforts to reduce harvest pressure 

on naturally produced spring-run Chinook salmon in upper Willamette River tributaries, and the 

increased focus on selective marking of hatchery fish should help managers targeting specific 

populations of wild or hatchery Chinook salmon. A majority of the previous (1998) BRT 

concluded that the Upper Willamette River Chinook salmon ESU was likely to become 

endangered in the foreseeable future. A minority of BRT members felt that Chinook salmon in 

this ESU were not presently in danger of extinction, nor were they likely to become so in the 

foreseeable future. 

Listing status: Threatened. 

New Data and Updated Analyses 

New data for this update include spawner abundance through 2002 in the Clackamas 

River, 2001 in the McKenzie River, and 2001 at Willamette Falls. In addition, new data include 

updated redd surveys in the upper Willamette River basin, new estimates of the fraction of 

hatchery-origin spawners in the McKenzie and North Santiam rivers from an otolith-marking 

study, the first estimate of hatchery fraction in the Clackamas River (2002 data), and information 

on recent hatchery releases. New analyses for this update include the designation of relatively 

demographically independent populations, recalculation of previous BRT metrics in the 

McKenzie River with additional years of data, estimates of current and historically available 

stream kilometers, and updates on current hatchery releases. 

126
9. UPPER WILLAMETTE RIVER CHINOOK SALMON ESU 

Historical Population Structure 

As part of its effort to develop viability criteria for upper Willamette River Chinook 

salmon, the WLC-TRT identified historical demographically independent populations (Myers et 

al. 2002). Population boundaries are based on an application of the VSP definition (McElhany et 

al. 2000). Myers et al. (2002) hypothesized that the ESU historically consisted of seven springrun populations (Figure 106). The populations identified in Myers et al. (2002) are used as the 

units for the new analyses in this report. 

Figure 106. Historical populations of spring-run Chinook salmon in the Upper Willamette River ESU. 

Source: Myers et al. (2002). 

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CHINOOK SALMON

Abundance and Trends 

References for abundance time series and related data are presented in Appendix A, 

Table A-3. Recent abundance of natural-origin spawners, recent fraction of hatchery-origin 

spawners, and recent harvest rates for Upper Willamette River ESU Chinook salmon populations 

are summarized in Table 19. The total number of spring-run Chinook spawners passing 

Willamette Falls from 1953 to 2001 is shown in Figure 107. All spring-run Chinook in the ESU, 

except those entering the Clackamas River, must pass Willamette Falls. There is no assessment 

of the ratio of hatchery- to natural-origin Chinook passing the falls, but the majority of fish are 

undoubtedly of hatchery origin. (Natural-origin fish are defined has having had parents that 

spawned in the wild, as opposed to hatchery-origin fish, whose parents spawned in a hatchery.) 

The status of individual populations follows. 

Clackamas 

The count of spring-run Chinook salmon passing the North Fork Dam on the Clackamas 

from 1958 to 2002 is shown in Figure 108 (Cramer 2002a). The total number of Chinook 

passing above the dam exceeded 1,000 in most years since 1980, and the last several years show 

large increases. However, the majority of these fish are likely of hatchery origin. The only year 

for which hatchery-origin estimates are available is 2002, and the estimate is 64% of hatchery 

origin. Although the majority of spring-run Chinook spawning habitat is above North Fork Dam, 

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

1950 1960 1970 1980 1990 2000

Year

Abundance

Figure 107. Number of spring-run Chinook salmon passing Willamette Falls, 1953–2001. The count is 

of mixed natural and hatchery origin, with the majority of fish likely of hatchery origin. 

128
9. UPPER WILLAMETTE RIVER CHINOOK SALMON ESU 

0

1000

2000

3000

4000

5000

6000

7000

1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total count Natural-origin spawners

Figure 108. Number of spring-run Chinook salmon passing North Fork Dam on the Clackamas River 

(Cramer 2002a), 1958–2002. The total count is all fish passing above the dam. There is only one 

estimate (in 2002) of the number of fish passing above the dam that are of natural origin. 

spawning is observed below the dam. The majority of spawning below the dam is also 

considered to be by hatchery-origin spawners. The population has shown substantial increases in 

total abundance (mixed hatchery and natural origin) in the last couple years. 

Molalla 

A 2002 survey of 16.3 miles (26.2 km) of stream in the Molalla found 52 redds. 

However, 93% of the carcasses recovered in the Molalla in 2002 were fin-clipped and of 

hatchery origin (Schroeder et al. 2002). Fin-clip recovery fractions for spring-run Chinook in the 

Willamette tend to underestimate the proportion of hatchery-origin spawners (Schroeder et al. 

2002), so the true fraction is likely in excess of 93% (i.e., near 100%). The Molalla naturalorigin spring-run Chinook population is believed to be extirpated, or nearly so. 

North Santiam 

Survey estimates of redds per mile in the North Santiam River are shown in Figure 109 

(from Schroeder et al. 2002). The number of stream miles surveyed varies between 26.8 and 

43.5. The total redds counted in a year varies between 116 and 310. Schroeder et al. (2002) 

estimate an escapement of 94 natural-origin spawners above Bennett Dam in 2000 and 151 in 

2001. These natural-origin spawners were greatly outnumbered by hatchery-origin spawners 

(2,192 and 6,635 in 2000 and 2001, respectively). This resulted in an estimate of 94% hatcheryorigin spawners in 2000 and 98% in 2001. This population is not considered self-sustaining. 

129
CHINOOK SALMON

0

2

4

6

8

10

12

1995 1996 1997 1998 1999 2000 2001 2002 2003

Year

Redds/Mile

Figure 109. North Santiam River Chinook salmon redds per mile, 1996–2002. The number of stream 

miles surveyed varies between 26.8 and 43.5 miles. The total redds counted in a year varies 

between 116 and 310. Over 95% of the spawners are estimated to be of hatchery origin. Source: 

Data from Schroeder et al. (2002). 

South Santiam 

A 2002 survey of 50.8 miles (81.7 km) of stream in the South Santiam River below 

Foster Dam found 982 redds. However, 84% of the carcasses recovered in the South Santiam in 

2002 were fin-clipped and of hatchery origin (Schroeder et al. 2002). Fin-clip recovery fractions 

for spring-run Chinook in the Willamette River tend to underestimate the proportion of hatcheryorigin spawners (Schroeder et al 2002), so the true fraction is likely in excess of 84%. This 

population is not considered self-sustaining. 

Calapooia 

A 2002 survey of 11.1 miles (17.8 km) of stream in the Calapooia River above 

Brownsville found 16 redds (Schroeder et al. 2002). The carcasses recovered in the Calapooia in 

2002 were too decomposed to determine the presence or absence of fin clips. However, it was 

assumed that all the fish were surplus hatchery fish outplanted from the South Santiam Hatchery 

(Schroeder et al. 2002). The Calapooia natural-origin spring-run Chinook population is believed 

to be extirpated, or nearly so. 

130
9. UPPER WILLAMETTE RIVER CHINOOK SALMON ESU 

0

1000

2000

3000

4000

5000

6000

7000

8000

1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total count Natural-origin spawners

Figure 110. Number of McKenzie River spring-run Chinook salmon at Leaburg Dam, 1970–2001. 

McKenzie 

The time series of total spring-run Chinook counts and natural-origin fish passing 

Leaburg Dam on the McKenzie River is shown in Figure 110. The average fraction of hatcheryorigin fish passed above the dam from 1998 to 2001 was estimated to be 26%. Redds are 

observed below Leaburg Dam, but the fraction of hatchery-origin fish is higher (Schroeder et al. 

2002). The fraction of fin-clipped spring-run Chinook carcasses recovered below Leaburg Dam 

was 72% in 2000 and 67% in 2001. Again, fin-clip recoveries tend to underestimate the fraction 

of hatchery-origin spawners. The spring-run Chinook population above Leaburg Dam in the 

McKenzie River is considered the best in the ESU, but with over 20% of the fish of hatchery 

origin, it is difficult to determine whether this population would be naturally self-sustaining. The 

population has shown substantial increases in total abundance (mixed hatchery and natural 

origin) in the last couple years. 

Middle Fork Willamette 

A 2002 survey of 17 miles (27.4 km) of the mainstem Middle Fork Willamette River 

found 64 redds. However, 77% of the carcasses recovered in the Middle Fork in 2002 were finclipped and of hatchery origin (Schroeder et al. 2002). In Fall Creek, a tributary of the Middle 

Fork, 171 redds in 13.3 miles were found in 2002. The 2002 carcass survey found that 39% of 

fish were fin-clipped. Fin-clip recovery fractions for spring-run Chinook in the Willamette River 

tend to underestimate the proportion of hatchery-origin spawners. This population is not 

considered to be self-sustaining. 

131
CHINOOK SALMON

No formal trend analyses were conducted on any Upper Willamette River ESU Chinook 

salmon populations. The two populations with long time series of abundance (Clackamas and 

McKenzie) have insufficient information on the fraction of hatchery-origin spawners to permit a 

meaningful analysis. 

Loss of Habitat from Barriers 

Steel and Sheer (2003) conducted an analysis was conducted to assess the number of 

stream kilometers historically and currently available to salmon populations in the upper 

Willamette River basin (Table 19). Stream kilometers usable by salmon are determined based on 

simple gradient cutoffs and on the presence of impassable barriers. This approach will 

overestimate the number of usable stream kilometers, because it does not consider habitat quality 

(other than gradient). However, the analysis does indicate that, for some populations, the 

number of stream habitat kilometers currently accessible is significantly reduced from the 

historical condition. 

Hatchery Releases 

A large number of spring-run Chinook salmon are released into the upper Willamette 

River as mitigation for the loss of habitat above federal hydroprojects (Table 20). This hatchery 

production is considered a potential risk because it masks the productivity of the natural 

population, interbreeding of hatchery and natural fish poses genetic risks, and the incidental take 

from the fishery promoted by hatchery production can increase adult mortality. Harvest 

retention is only allowed for hatchery-marked fish, but take from hooking mortality and 

noncompliance is still a potential issue. 

Table 19. Historical populations of Upper Willamette River spring-run Chinook salmon ESU. 

Population 

Hatchery 

fraction 

(%) 

Potential 

current 

habitata

 (%) 

Potential 

historical 

habitata (km) 

Current to 

historical habitat 

ratio (%) 

Clackamas River 64b 369 475 78 

Molalla River >93c 432 688 63 

North Santiam River 97 173 269 64 

South Santiam River >84c 445 658 68 

Calapooia River 

Estimated 

@100 163 253 65 

McKenzie River 26d 283 382 74 

Middle Fork Willamette River >77c 197 425 46 

Total 2,063 3,150 65 a

 The current and historical habitat estimates are based on Steel and Sheer’s analysis (2003). 

b

 For the Clackamas River population, only one year (2002) of hatchery fraction estimate is available (Cramer 

2002a). 

c

 Hatchery fraction in the Molalla, South Santiam, and Middle Fork Willamette rivers are minimum estimates based 

on the ratio of adipose-marked versus unmarked fish recovered in 2001 (Schroeder et al. 2002). 

d

 For the McKenzie River population, hatchery fraction is the average percent of spawners of hatchery origin over 

the last 4 years. 

132
9. UPPER WILLAMETTE RIVER CHINOOK SALMON ESU 

Table 20. Upper Willamette River spring-run Chinook salmon ESU hatchery releases. Source: Compiled 

by Waknitz (2002). 

Watershed Years Hatchery Stock Release site Total 

1994 Dexter Pond McKenzie Lower Willamette River 73,028 

1995 Dexter Pond Willamette Lower Willamette River 137,573 

1995 Lowerone Star Clackamas Lower Willamette River 59,654 

1995 Marion Forks North Santiam Lower Willamette River 40,320 

1993–1994 McKenzie McKenzie Lower Willamette River 344,089 

1992–1993 Step Clackamas Lower Willamette River 70,193 

1993–1994 Step McKenzie Lower Willamette River 331,446 

1993–1995 McKenzie Clackamas Lower Willamette River 125,585 

1996–1999 Willamette McKenzie Lower Willamette River 225,122 

1995–1996 Willamette North Santiam Lower Willamette River 81,513 

Willamette 

River 

1995–1999 McKenzie McKenzie Lower Willamette River 574,117 

Clackamas 1991–1994 Clackamas Clackamas Clackamas River 4,358,092 

River 1995–2002 Clackamas Clackamas Clackamas River 9,182,916 

1996–2001 McKenzie McKenzie Clackamas River 1,332,542 

1991 Eagle Creek Clackamas Eagle Creek 556,814 

Fall-run Chinook salmon are not native to the upper Willamette River and are not part of 

the Upper Willamette River Chinook salmon ESU. Fall-run Chinook hatchery fish are no longer 

released into the upper Willamette River, though there have been substantial releases in the past 

(Figure 111). 

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

1950 1960 1970 1980 1990 2000 2010

Year

Abundance

Figure 111. Number of fall-run Chinook salmon at Willamette Falls, 1952–2001. Fall-run Chinook 

salmon are not native in the upper Willamette River and are not found in the Upper Willamette 

River Chinook salmon ESU. 

133
CHINOOK SALMON

ESU Summary 

The updated information provided in this memorandum, the information contained in 

previous Upper Willamette River ESU Chinook salmon status reviews, and WLC-TRT’s 

preliminary analysis indicate that most natural-origin spring-run Chinook populations are likely 

extirpated, or nearly so. The only population considered potentially self-sustaining is the 

McKenzie River population. However, its abundance has been relatively low (low thousands), 

with a substantial number of these fish being of hatchery origin. The McKenzie River 

population has shown a substantial increase in the last couple years, hypothesized to be a result 

of increased ocean survival. What ocean survival will be in the future is unknown, and the longterm sustainability of the McKenzie River population is uncertain. 

134
10. California Coastal Chinook Salmon ESU 

Summary of Previous BRT Conclusions 

The status of Chinook salmon throughout California and the Pacific Northwest was 

formally assessed in 1998 (Myers et al. 1998). Substantial scientific disagreement about the 

biological data and its interpretation persisted for some ESUs, which were reconsidered in a 

subsequent status review update (NMFS 1999a). Information from those reviews regarding ESU 

structure, analysis of extinction risk, risk factors, and hatchery influences is summarized in the 

subsections that follow. 

ESU Structure 

The initial status review proposed a single ESU of Chinook salmon inhabiting coastal 

basins south of Cape Blanco, Oregon, and the tributaries to the Klamath River downstream of its 

confluence with the Trinity River in California (Myers et al. 1998). Subsequent review of an 

augmented genetic data set and further consideration of ecological and environmental 

information led to the division of the originally proposed ESU into the Southern Oregon and 

Northern California Coastal Chinook salmon ESU and the California Coastal Chinook salmon 

ESU (NMFS 1999a). The California Coastal Chinook salmon ESU currently includes Chinook 

salmon from Redwood Creek to the Russian River (inclusive). 

Summary of Risk Factors and Status 

The California Coastal Chinook salmon ESU is listed as threatened. Primary causes for 

concern were low abundance, reduced distribution (particularly in the southern portion of the 

ESU’s range), and generally negative trends in abundance; all of these concerns were especially 

strong for spring-run Chinook salmon in this ESU (Myers et al. 1998). Data for this ESU are 

sparse and in general of limited quality, which contributes to substantial uncertainty in estimates 

of abundance and distribution. The BRT considered degradation of the genetic integrity of the 

ESU to be of minor concern and to present less risk for this ESU than for other ESUs. 

Previous reviews of conservation status for Chinook salmon in this area exist. Nehlsen 

et al. (1991) identified three putative populations (Humboldt Bay tributaries, Mattole River, and 

Russian River) as being at high risk of extinction and three other populations (Redwood Creek, 

Mad River, and lower Eel River) as being at moderate risk of extinction. Higgins et al. (1992) 

identified seven “stocks of concern,” of which two populations (tributaries to Humboldt Bay and 

the Mattole River) were considered to be at high risk of extinction. Some reviewers indicate that 

Chinook salmon native to the Russian River have been extirpated. 

135
CHINOOK SALMON

Table 21. Historical estimates of abundance of Chinook salmon in the California Coastal Chinook 

salmon ESU. 

Selected watersheds CDFGa

 (1965) 

Wahle and 

Pearson (1987) 

Redwood Creek 5,000 1,000 

Mad River 5,000 1,000 

Eel River 55,000 17,000 

Mainstem Eel Riverb 13,000 – 

Van Duzen Riverb 2,500 – 

Middle Fork Eel Riverb 13,000 – 

South Fork Eel Riverb 27,000 – 

Bear River – 100 

Small Humboldt County rivers 1,500 – 

Miscellaneous rivers north of Mattole 

River – 600 

Mattole River 5,000 1,000 

Noyo River 50 – 

Russian River 500 50 

Total 72,550 20,750 a CDFG = California Department of Fish and Game. 

b Entries for subbasins of the Eel River basin are not included separately in the total. 

Historical estimates of escapement are presented in Table 21. These estimates are based 

on professional opinion and evaluation of habitat conditions, and thus do not represent rigorous 

estimates based on field sampling. Historical time series of counts of upstream migrating adults 

are available for Benbow Dam (South Fork Eel River 1938–1975), Sweasy Dam (Mad River 

1938–1964), and Cape Horn Dam (Van Arsdale Fish Station, Eel River); the latter represent a 

small, unknown, and presumably variable fraction of the total run to the Eel River. Data from 

cursory, nonsystematic stream surveys of two tributaries to the Eel River (Tomki and Sprowl 

creeks) and one tributary to the Mad River (Canon Creek) were also available; these data provide 

crude indices of abundance. 

Previous status reviews considered the following to pose significant risks to the California 

Coastal Chinook salmon ESU: degradation of freshwater habitats due to a variety of agricultural 

and forestry practices, water diversions, urbanization, mining, and severe recent flood events 

(exacerbated by land use practices). Special concern was noted regarding the more precipitous 

declines in distribution and abundance in spring-run Chinook salmon. Many of these factors are 

particularly acute in the southern portion of the ESU and were compounded by uncertainty 

stemming from the general lack of population monitoring in California (Myers et al. 1998). 

In previous status reviews, the effects of hatcheries and transplants on the ESU’s genetic 

integrity elicited less concern than other risk factors for this ESU, and were less of a concern 

compared to other ESUs. 

Listing status: Threatened. 

136
 10. CALIFORNIA COASTAL CHINOOK SALMON ESU 

New Data and Updated Analyses 

The TRT for the North-Central California Coast (NCCC) recovery domain proposed a set 

of plausible hypotheses, based largely on geography, regarding the population structure of the 

California Coastal Chinook salmon ESU (Table 22), but concluded that information to 

discriminate among these hypotheses is insufficient (Bjorkstedt et al. in prep.). Data are not 

available for all potential populations; only those for which data are available are considered 

below. 

Abundance and Trends 

New or updated time series for Chinook salmon in this ESU include 1) counts of adults 

reaching Van Arsdale Fish Station near the effective headwater terminus of the Eel River; 2) 

cursory, quasi-systematic spawner surveys on Canon Creek (tributary to the Mad River), Tomki 

Creek (tributary to the Eel River), and Sprowl Creek (tributary to the Eel River); and 3) counts of 

Table 22. Plausible hypotheses for independent populations considered by the North-Central California 

Coast TRT. This information is summarized from a working draft report and should be 

considered as preliminary and subject to revision. 

Lumped Split 

Redwood Creek 

Mad River 

Humboldt Bay tributaries 

Eel Rivera

South Fork Eel River 

Van Duzen River 

Middle Fork Eel River 

North Fork Eel River 

Upper Eel River 

Bear River 

Mattole River 

Tenmile to Gualalab

Russian River a Plausible hypotheses regarding the population structure of Chinook salmon in the Eel River basin include scenarios 

ranging from five independent populations (South Fork Eel River, Van Duzen River, upper Eel River, Middle Fork 

Eel River, and North Fork Eel River) to a single, strongly structured independent population. 

b This stretch of the coast comprises numerous smaller basins that drain directly into the Pacific Ocean, some of 

which appear sufficiently large to support independent populations of Chinook salmon. The following hypotheses 

span much of the range of plausible scenarios: 1) independent populations exist in all basins that exceed a 

minimum size; 2) independent populations exist only in basins between the Tenmile River and Big River, 

inclusive, that exceed a minimum size; 3) Chinook salmon inhabiting basins along this stretch of coastline exhibit 

patchy population or metapopulation dynamics in which the occupancy of any given basin depends on migrants 

from other basins, and possibly from larger basins to the north and south; and 4) Chinook salmon inhabiting basins 

between the Tenmile River and Big River, inclusive, exhibit patchy population or metapopulation dynamics in

which the occupancy of any given basin depends on migrants from other basins in this region and possibly to the 

north, while other basins to the south only sporadically harbor Chinook salmon. 

137
CHINOOK SALMON

Table 23. Geometric means, estimated λ, and long- and short-term trends for abundance time series in the 

California Coastal Chinook salmon ESU. 

5-year geometric mean Trend 

Recent Minimum Maximum Long term Short term 

Freshwater Creeka 22 13 22 0.137 (–0.405, 0.678) 0.137 (–0.405, 0.678) 

Mad River 

Canon Creekb 73 19 103 0.0102 (–0.106, 0.127) 0.155 (–0.069, 0.379) 

Eel River 

Sprowl Creekc 43 43 497 –0.096 (–0.157, –0.034) –0.183 (–0.356, –0.010)

Tomki Creekc 61 13 2,233 –0.199 (–0.351, –0.046) 0.294 (0.055, 0.533) a S. Ricker, CDFG, Steelhead Research and Monitoring Program, Arcata, CA. Pers. commun., 30 May 1999. 

b Preston (1999). 

c PFMC (2002a). 

returning spawners at a weir on Freshwater Creek (tributary to Humboldt Bay). None of these 

time series is especially suitable for analyzing trends or estimating population growth rates. 

Freshwater Creek 

Counts of Chinook salmon passing the weir near the mouth of Freshwater Creek, a 

tributary to Humboldt Bay, provide a proper census of a small (N ≈ 20) population of natural and 

hatchery-origin Chinook salmon (Figure 112). Chinook salmon occupying this watershed may 

be part of a larger “population” that uses tributaries of Humboldt Bay (NCCC-TRT in prep.). 

The time series comprises only 8 years of observations, too few to draw strong inferences 

regarding trends. Clearly, the trend is positive, although the role of hatchery production in 

producing this signal may be significant (Table 23 and Figure 112). 

0

20

40

60

80

100

120

140

160

180

1993 1994 1995 1996 1997 1998 1999 2000 2001 2002

Year

Abundance

Total Hatchery origin

Figure 112. Number of Chinook salmon at the weir on Freshwater Creek, 1994–2001. 

138
 10. CALIFORNIA COASTAL CHINOOK SALMON ESU 

Mad River 

Data for naturally spawning fish are available from spawner surveys on Canon Creek, 

and to a lesser extent on the North Fork Mad River. Only the counts from Canon Creek extend 

continuously to the present (Figure 113a). Due to high variability in these counts, short- and 

long-term trends do not differ significantly from zero, although the tendency is toward a positive 

trend. Due to a hypothesized, but unquantified, effect of interannual variation in water 

availability on distribution of spawners in the basin, it is not clear whether these data provide any 

useful information for the population as a whole; however, more sporadic counts from the 

mainstem Mad River suggest that the estimates from Canon Creek capture gross signals and 

support the hypothesis of a recent positive trend in abundance (Figure 113b). 

Eel River 

The Eel River plausibly harbors anywhere from one to five independent populations 

(NCCC-TRT in prep.; Table 22). Three current time series provide information for the 

populations that occupy this basin: 1) counts of adults reaching Van Arsdale Fish Station near 

the effective headwater terminus of the Eel River (Figure 114a); 2) spawner surveys on Sprowl 

Creek (tributary to the Eel River) (Figure 114b); and 3) spawner surveys on Tomki Creek 

(tributary to the Eel River) (Figure 114c). These data are not especially suited to rigorous 

analysis of population status for a number of reasons, and sophisticated analyses were not 

pursued. 

Two characteristics of the data weaken inferences regarding population status drawn 

from the time series of counts of adult Chinook salmon reaching Van Arsdale Fish Station 

(VAFS). First, adult salmon reaching VAFS include both natural- and hatchery-spawned fish, 

yet the long-term contribution of hatchery production to the spawner population is unknown and 

may be quite variable due to sporadic operation of the egg take-and-release programs since the 

mid-1970s. Second, and perhaps more important, it is not clear what VAFS natural spawner 

counts indicate about the population or populations of Chinook salmon in the Eel River. As a 

weir count, measurement error is expected to be small for these counts. However, very little 

spawning habitat exists above VAFS, which sits just below the Cape Horn Dam. This dearth of 

habitat suggests that counts made at VAFS represent the upper edge of the spawners’ distribution 

in the upper Eel River. Spawner access to VAFS and other headwater habitats in the Eel River 

basin is likely to depend strongly on the timing and persistence of suitable river flow, which 

suggests that a substantial component of the process error in these counts is not due to population 

dynamics. For these reasons, no statistical analysis of these data was pursued. 

Additional data for the Eel River population or populations are available from spawner 

surveys from Tomki and Sprowl creeks, which yield estimates of abundance based on 1) quasisystematic index site spawner surveys that incorporate mark-recapture analysis of carcasses and 

2) additional so-called compatible data from other surveys. Analysis for Sprowl Creek indicates 

negative long- and short-term trends; similar analysis indicates a long-term decline and shortterm increase for Tomki Creek (Table 22). Caution in interpreting these results is warranted, 

particularly given the quasi-systematic collection of these data, and the likelihood that these data 

include unquantified variability due to flow-related changes in spawners’ use of mainstem and 

tributary habitats. In particular, inferences regarding population status based on 

139
CHINOOK SALMON

b. Mainstem Mad River

0

100

200

300

400

500

600

1980 1985 1990 1995 2000

Year

Abundance

a. Canon Creek

0

100

200

300

400

500

600

1980 1985 1990 1995 2000

Year

Abundance

Figure 113. Abundance time series for Chinook salmon in portions of the Mad River basin: a. spawner 

counts on Canon Creek, 1981–2001; b. spawner counts on portions of the mainstem Mad River, 

1985–1998. 

140
 10. CALIFORNIA COASTAL CHINOOK SALMON ESU 

a. Van Arsdale Fish Station

0

200

400

600

800

1000

1200

1400

1600

1800

2000

1933 1943 1953 1963 1973 1983 1993

Abundance

Total Hatchery origin

b. Sprowl Creek

0

500

1000

1500

2000

2500

1964 1968 1972 1976 1980 1984 1988 1992 1996 2000

Abundance

c. Tomki Creek

0

500

1000

1500

2000

2500

3000

3500

4000

1964 1968 1972 1976 1980 1984 1988 1992 1996 2000

Year

Abundance

Figure 114. Abundance time series for Chinook in portions of the Eel River basin: a. counts of Chinook 

at Van Arsdale Fish Station at the upstream terminus of anadromous access on the mainstem Eel 

River; b. estimates of spawner abundance based on spawner surveys and additional data from 

Sprowl Creek; c. estimates of spawner abundance based on spawner surveys and additional data 

from Tomki Creek. 

141
CHINOOK SALMON

extrapolations from these data to basinwide estimates of abundance are expected to be weak and 

perhaps not warranted. 

Mattole River 

The Mattole Salmon Group has conducted spawner and redd surveys on the Mattole 

River and tributaries since 1994. The surveys provide useful information on the distribution of 

salmon and spawning activity throughout the basin. Local experts have used these and ancillary 

data to develop rough “index” estimates of spawner escapement to the Mattole River; however, 

the intensity and coverage of these surveys have not been consistent, and the resulting data are 

not suitable for rigorous estimation of abundance (e.g., through area-under-the-curve analysis). 

Russian River 

No long-term, continuous time series are available for sites in the Russian River basin, 

but sporadic estimates based on spawner surveys are available for some tributaries. Video-based 

counts of upstream migrating adult Chinook passing a temporary dam near Mirabel on the 

Russian River are available for 2000–2002. Counts are incomplete, due to technical difficulties 

with the video apparatus, occasional periods of poor water clarity, occasional overwhelming 

numbers of fish, and disparities between counting and migration periods; thus, these data 

represent a minimum count of adult Chinook. Counts have exceeded 1,300 fish in each of the 

last 3 years (5,465 in 2002); and a rigorous mark-recapture estimate of outmigrant abundance in 

2002 exceeded 200,000.12 Because Chinook have not been produced at the Don Clausen 

Hatchery since 1997, these counts represent natural production or straying from other systems. 

No data were available to assess the genetic relationship of these fish to others in this or other 

ESUs. 

Summary 

Historical and current information indicates that abundance in putatively independent 

populations of Chinook is depressed in many of those basins where they have been monitored. 

The relevance of recent strong returns to the Russian River to ESU status is not clear because the 

genetic composition of these fish is unknown. Reduction in geographic distribution, particularly 

for spring-run Chinook and for basins in the southern portion of the ESU, continues to present 

substantial risk. Genetic concerns are reviewed below (see subsection, New Hatchery 

Information, below). As for previous status reviews, uncertainty continues to contribute 

substantially to assessments of risk facing this ESU. 

New Hatchery Information 

Hatchery stocks that are considered for inclusion in this ESU are 1) Mad River Hatchery; 

2) hatchery activities of the Humboldt Fish Action Council on Freshwater Creek; 3) Yager Creek 

Hatchery, operated by Pacific Lumber Company; 4) Redwood Creek Hatchery; 5) Hollow Tree 

Creek Hatchery; 6) Van Arsdale Fish Station; and 7) hatchery activities of the Mattole Salmon 

Group. Chinook are no longer produced at the Don Clausen Hatchery on Warm Springs Creek 

 

12S. Chase, Sonoma County Water Agency, Santa Rosa, CA. Pers. commun., 18 December 2002. 

142
 10. CALIFORNIA COASTAL CHINOOK SALMON ESU 

(Russian River). In general, hatchery programs in this ESU are not oriented toward large-scale 

production; rather, they are small-scale operations oriented at supplementing depressed 

populations. 

Freshwater Creek 

This hatchery is operated by Humboldt Fish Action Council (HFAC) and the California 

Department of Fish and Game (CDFG) to supplement and restore natural production in 

Freshwater Creek. All spawners are from Freshwater Creek; juveniles are marked, and hatchery 

fish are excluded from use as broodstock. Weir counts provide good estimates of the proportion 

of hatchery- and natural-origin fish returning to Freshwater Creek (30–70% hatchery from 1997 

to 2001); the contribution of HFAC production to spawning runs in other streams tributary to 

Humboldt Bay is unknown. 

Mad River 

Recent production from this hatchery has been based on small numbers of spawners 

returning to the hatchery. There are no estimates of naturally spawning Chinook abundance 

available for the Mad River to determine the contribution of hatchery production to Chinook in 

the basin as a whole. Broodstock has generally been drawn from Chinook returning to the Mad 

River; however, releases in the 1970s and 1980s included substantial releases of fish from out of 

the basin (Freshwater Creek) and out of the ESU (Klamath-Trinity and Puget Sound). 

Eel River 

Four hatcheries, none of which are major production hatcheries, contribute to production 

of Chinook salmon in the Eel River basin: hatcheries on Yager Creek (recent effort is 

approximately 12 females spawned per year), Redwood Creek (approximately 12 females), 

Hollow Tree Creek, and the Van Arsdale Fish Station (VAFS) (approximately 60 males and 

females). At the first three hatcheries, broodstock is selected from adults of nonhatchery origin; 

at VAFS, broodstock includes both natural and hatchery-origin fish. In all cases, however, 

insufficient data on naturally spawning Chinook are available to estimate the effect of hatchery 

fish on production or other characteristics of naturally spawning Chinook in the Eel River basin. 

Since 1996, all fish released from VAFS have been marked. Subsequent returns indicate that 

approximately 30% of the adult Chinook trapped at VAFS are of hatchery origin. It is not clear 

what these numbers indicate about hatchery contributions to the population of fish spawning 

below VAFS. 

Mattole River 

The Mattole Salmon Group has operated a small hatchbox program since 1980 (current 

effort approximately 40,000 eggs from approximately 10 females) to supplement and restore 

Chinook salmon and other salmonids in the Mattole River. All fish are marked, but no rigorous 

estimate of hatchery contributions to adult escapement is possible. Hatchery-produced 

outmigrants comprised approximately 17.3% (weighted average) of outmigrants trapped during 

1997, 1998, and 2000 (Mattole Salmon Group 2000). Trapping efforts did not fully span the 

143
CHINOOK SALMON

period of natural outmigration, so this figure may overestimate the contribution of hatchbox 

production to total production in the basin. 

Russian River 

Production of Chinook salmon at the Don Clausen (Warm Springs Hatchery) ceased in 

1997 and had been largely ineffective for a number of years prior to that. Recent returns of 

Chinook salmon to the Russian River stem from natural production, and possibly from fish 

straying from other basins, including perhaps Central Valley stocks. 

Summary 

Artificial propagation of Chinook salmon in this ESU remains at relatively low levels. 

No putatively independent populations of Chinook salmon in this ESU appear to be entirely 

dominated by hatchery production, although proportions of hatchery fish can be quite high where 

natural escapement is small and hatchery production appears to be successful (e.g., Freshwater 

Creek). It is not clear whether current hatcheries pose a risk or offer a benefit to naturally 

spawning populations. Extant hatchery programs are operated under guidelines designed to 

minimize genetic risks associated with artificial propagation and, save for historical inputs to the 

Mad River Hatchery stock, do not appear to be at substantial risk of incorporating out-of-basin or 

out-of-ESU fish. Thus, it is likely that artificial propagation and degradation of genetic integrity 

do not represent a substantial conservation risk to the ESU. Categorizations of hatchery stocks in 

the California Coastal Chinook salmon ESU (SSHAG 2003) can be found in Appendix A, 

Table A-1. 

Comparison with Previous Data 

Few new data, and few new data sets, were available for consideration, and none of the 

recent data contradicts the conclusions of previous status reviews. Chinook salmon in the 

California Coastal Chinook salmon ESU continue to exhibit depressed population sizes relative 

to historical abundances; this is particularly true for spring-run Chinook salmon, which may no 

longer be extant anywhere within the range of the ESU. Evaluation of the significance of recent 

potential increases in abundance of Chinook salmon in the Russian River must weigh the 

substantial uncertainty regarding the genetic relatedness of these fish to others in the northern 

part of the ESU. 

Harvest rates are not explicitly estimated for this ESU; however, it is likely that current 

restrictions on harvest of Klamath River fall-run Chinook salmon maintain low ocean harvest of 

Chinook from the California Coastal Chinook salmon ESU (PFMC 2002a, 2002b). Potential 

changes in age-structure of Chinook salmon populations (e.g., Hankin et al. 1993) and associated 

risk have not been evaluated for this ESU. 

No information exists to suggest new risk factors or substantial effective amelioration of 

risk factors noted in the previous status reviews, except for recent changes in ocean conditions. 

Recent favorable ocean conditions have contributed to apparent increases in abundance and 

distribution for a number of anadromous salmonids, but the expected persistence of this trend is 

unclear.

144
11. Sacramento River Winter-Run 

Chinook Salmon ESU 

Summary of Previous BRT Conclusions 

The status of Chinook salmon coastwide was formally assessed in 1998 (Myers et al. 

1998); however, NMFS had previously recognized Sacramento River winter-run Chinook 

salmon as a distinct population segment under the ESA (NMFS 1987). 

Summary of Major Risk Factors and Status Indicators 

Historically, winter-run Chinook salmon depended on access to spring-fed tributaries to the 

upper Sacramento River that stayed cool during the summer and early fall. Adults enter 

freshwater in early winter and spawn in the spring and summer. Juveniles rear near the 

spawning location until at least the fall, when water temperatures in lower reaches are suitable 

for migration. Winter-run Chinook salmon were abundant and comprised populations in the 

McCloud, Pit, and Little Sacramento rivers, with perhaps smaller populations in Battle Creek and 

the Calaveras River. Based on commercial fishery landings in the 1870s, Fisher (1994) 

estimated that the total run size of winter-run Chinook salmon may have been 200,000 fish. 

The most obvious challenge to winter-run Chinook salmon was the construction of Shasta 

Dam, which blocked access to the entire historical spawning habitat. It was not expected that 

winter-run Chinook salmon would survive this habitat alteration (Moffett 1949). Cold-water 

releases from Shasta Dam, however, created conditions suitable for winter-run Chinook salmon 

for roughly 100 km downstream from the dam. Presumably, there were several independent 

populations of winter-run Chinook salmon in the Pitt, McCloud, and Little Sacramento rivers 

and various tributaries to these rivers, such as Hat Creek and the Fall River. These populations 

merged to form the present single population. If there ever were populations in Battle Creek and 

the Calaveras River, they have been extirpated. 

In addition to having only a single extant population dependent on artificially created 

conditions, winter-run Chinook salmon face numerous other threats. Chief among these threats 

is small population size—escapement fell below 200 fish in the 1990s. Population size declined 

monotonically from highs of near 100,000 fish in the late 1960s, indicating a sustained period of 

poor survival. There are questions of genetic integrity due to winter-run Chinook salmon having 

passed through several bottlenecks in the 20th century. Other threats include inadequately 

screened water diversions, predation at artificial structures and by nonnative species, pollution 

from Iron Mountain Mine (among other sources), adverse flow conditions, high summer water 

temperatures, unsustainable harvest rates, passage problems at various structures (e.g., Red Bluff 

Diversion Dam), and vulnerability to drought. 

145
CHINOOK SALMON

Previous BRT Conclusions 

The Chinook salmon BRT spent little time considering the status of winter-run Chinook 

salmon, because winter-run Chinook salmon were already listed as endangered at the time of 

previous BRT meetings. 

Listing status: Endangered. 

New Data and Updated Analyses 

Viability Assessments 

Two studies have been done on the population viability of Sacramento River winter-run 

Chinook salmon. Botsford and Brittnacher (1998), in a paper that is part of the draft recovery 

plan, developed delisting criteria using a simple age-structured, density-independent model of 

spawning escapement. They concluded, on the basis of the 1967–1995 data, that winter-run 

Chinook salmon were certain to fall below the quasi-extinction threshold of three consecutive 

spawning runs with fewer than 50 females. 

Lindley and Mohr (2003) developed a slightly more complex Bayesian model of winterrun Chinook salmon spawning escapement that allowed for density dependence and a change in 

population growth rate in response to conservation measures initiated in 1989. This model, due 

to its allowance for the growth-rate change, its accounting for parameter uncertainty, and use of 

newer data (through 1998), suggested a lower, but still biologically significant, expected quasiextinction probability of 28%. 

Draft Recovery Plan 

The draft recovery plan for Sacramento River winter-run Chinook salmon (NMFS 1997a) 

provides a comprehensive review of the population’s status, life history, habitat requirements, 

and risk factors. It also provides a recovery goal: an average of 10,000 female spawners per year 

and a λ ≥ 1.0, calculated over 13 years of data (assuming a certain level of precision in spawning 

escapement estimates). 

New Abundance Data 

The Sacramento River winter-run Chinook salmon spawning run has been counted at Red 

Bluff Diversion Dam (RBDD) fish ladders since 1967. Escapement has been estimated with a 

carcass survey since 1996. Through the mid-1980s, the RBDD counts were very reliable. At 

that time, changes to the dam operation were made to alleviate juvenile and adult passage 

problems. Now, only the tail end of the run (about 15% on average) is forced over the ladders, 

greatly reducing the accuracy of the RBDD counts. The carcass mark-recapture surveys were 

initiated to improve escapement estimates. The two measures are in very rough agreement, and 

there are substantial problems with both estimates, making it difficult to choose one as more 

reliable than the other. One problem with the carcass-based measure is estimation of the 

probability of capturing carcasses—it appears that the probability of initial carcass recovery 

depends strongly on the sex and size of the fish, and possibly on whether it has been previously 

146
11. SACRAMENTO RIVER WINTER-RUN CHINOOK SALMON ESU 

0

10000

20000

30000

40000

50000

60000

1970 1975 1980 1985 1990 1995 2000

Year

Abundance

Figure 115. Estimated Sacramento River winter-run Chinook spawner abundance, 1970–2002. 

recovered. In the winter-run Chinook salmon carcass surveys, a high ratio of females to males is 

observed (e.g., Snider et al. 1999), and several studies of salmon carcass recovery have noted 

that females are recovered with a higher probability than males, presumably because of the 

different behavior of males and females (e.g., Shardlow et al. 1986 and references therein). In 

spite of these problems, both abundance measures suggest that the abundance of Sacramento 

River winter-run Chinook salmon is increasing. Based on the RBDD counts, the winter-run 

Chinook salmon population has been growing rapidly since the early 1990s (Figure 115), with a 

short-term trend of 0.26 (Table 24). On the population growth rate–population size space, the 

Sacramento River winter-run Chinook salmon population has a somewhat low population growth 

and moderate size compared to other Central Valley salmonid populations (Figure 116). 

Table 24. Summary statistics for trend analyses 90% confidence intervals are in parentheses). Results for 

other populations are shown for comparison. 

Population 

5-year 

mean 

5-year 

min. 

5-year 

max. λ μ

Long-term 

trend 

Short-term 

trend 

Sacramento River 

winter-run 

Chinook 

2,191 364 65,683 0.97 

(0.87, 1.09) 

–0.10 

(–0.21, 0.01)

–0.14 

(–0.19, –0.09) 

0.26 

(0.04, 0.48) 

Butte Creek springrun Chinook 4,513 67 4,513 1.30 

(1.09, 1.60) 

0.11 

(–0.05, 0.28)

0.11 

(0.03, 0.19) 

0.36 

(0.03, 0.70) 

Deer Creek springrun Chinook 1,076 243 1,076 1.17 

(1.04, 1.35) 

0.12 

(–0.02, 0.25)

0.11 

(0.02, 0.21) 

0.16 

(–0.01, 0.33)

Mill Creek springrun Chinook 491 203 491 1.19 

(1.00, 1.47) 

0.09 

(–0.07, 0.26)

0.06 

(–0.04, 0.16) 

0.13 

(–0.07, 0.34)

Sacramento River 

steelhead 

1,952 1,425 12,320 0.95 

(0.90, 1.02) 

–0.07 

(–0.13, 0.00)

–0.09 

(–0.13, –0.06) 

NA 

147
CHINOOK SALMON

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

2 2.5 3 3.5 4 4.5 5

Log10 (5-year mean population size)

μ

Figure 116. Abundance and growth rate of Central Valley salmonid populations. c = steelhead;  = 

spring-run Chinook; ▲ = winter-run Chinook; • = other Chinook stocks. Error bars represent 

central 0.90 probability intervals for μ estimates. Note: as defined in other sections of the status 

reviews, μ ≈ log(λ). 

Sacramento River winter-run Chinook salmon may be responding to a number of factors, 

including wetter than normal winters, changes in ocean harvest regulations since 1995 that have 

significantly reduced harvests, changes in RBDD operation, improved temperature management 

on the upper Sacramento River (including installation of a cold-water release device on Shasta 

Dam), water quality improvements due to remediation of Iron Mountain Mine discharges, 

changes in operations of the state and federal water projects, and a variety of other habitat 

improvements. Although the status of winter-run Chinook salmon is improving, there is only 

one winter-run Chinook salmon population, and it depends on cold-water releases from Shasta 

Dam, which could be vulnerable to a prolonged drought. The recent 5-year geometric mean is 

only 3% of the maximum, post-1967, 5-year geometric mean. 

The RBDD counts are suitable for modeling as a random-walk-with-drift (RWWD, also 

known as the “Dennis model” [Dennis et al. 1991]). In the RWWD model, population growth is 

described by exponential growth or decline: 

Nt+1 = Nt exp(μ+ ηt) (22) 

where Nt is the population size at time t, μ is the mean population growth rate, and ηt is a normal 

random variable with mean = 0 and variance = σ

2

p. 

The RWWD model, as written in Equation 22, ignores measurement error. Observations 

(yt) can be modeled separately, 

yt = Nt exp(εt) (23) 

where εt is a normal random variable with mean = 0 and variance = σ

2

m. Equations 22 and 23 

together define a state-space model that, after linearizing by taking logarithms, can be estimated 

using the Kalman filter (Lindley 2003). 

148
11. SACRAMENTO RIVER WINTER-RUN CHINOOK SALMON ESU 

A recent analysis of the RBDD data (Lindley and Mohr 2003) indicated that the 

population growth since 1989 was higher than in the preceding period. For this reason, two 

forms of the RWWD model are fitted—one with a fixed growth rate (constant-growth model) 

and another with a growth rate with a step-change model in 1989, when conservation actions 

began (step-change model, μt = μ for t < 1989, μt = μ + δ for t ≥ 1989). In both cases, a 4-year 

running sum was applied to the spawning escapement data to form a total population estimate 

(Holmes 2001). Results of model fitting are shown in Table 25. The constant-growth model 

satisfies all model diagnostics, although visual inspection of the residuals shows a strong 

tendency to underpredict abundance in the most recent 10 years. The residuals of the stepchange model fail the Shapiro-Wilks test for normality; the residuals look truncated on the 

positive side, meaning that good years are not as extreme as bad years. Sacramento River 

winter-run Chinook salmon growth rate might be better modeled as a mixture between a normal 

distribution and another distribution reflecting near-catastrophic population declines caused by 

episodic droughts. 

According to Akaike’s information criterion (AIC), the step-change model is a much 

better approximation to the data than the constant population growth rate model, with an AIC 

difference of 9.61 between the two models (indicating that the data provide almost no support for 

the constant-growth model). The step-change model suggests the winter-run Chinook salmon 

population currently has a λ of 1.21, while for the constant population growth-rate model, λ = 

0.97.13 The extinction risks predicted by the two models are extremely different: winter-run 

Chinook salmon have almost no risk of extinction if the apparent recent increase in λ holds in the 

future, but are certain to go extinct if the population grows at its average rate, with a most likely 

time of extinction of 100 years. Although it would be dangerous to assume that recent 

population growth will hold indefinitely, it does appear that the status of Sacramento River 

winter-run Chinook salmon is improving. 

Table 25. Parameter estimates for the constant-growth and step-change models applied to Sacramento 

River winter-run Chinook salmon (90% confidence intervals are in parentheses). 

Model 

Parameter Constant μ Step change μ

μ –0.085 (–0.181, 0.016) –0.214 (–0.322, –0.113) 

δ NA 0.389 (0.210, 0.574) 

σ

2

p 0.105 (0.094, 0.122) 0.056 (0.046, 0.091) 

σ

2

m 0.0025 (2.45E–6, 0.0126) 0.011 (3.92E–6, 0.022) 

P100(ext)* 0.40 (0.00, 0.99) 0.003 (0.0, 0.0) * Probability of extinction (population size greater than 1 fish) within 100 

years. 

 

13 In this section, λ is defined as exp(μ+ σ2p/2), the mean annual population growth rate. 

149
CHINOOK SALMON

Harvest Impacts 

Substantial changes in ocean fisheries off central and northern California have occurred 

since the last status review (PFMC 2002a, 2002b). The ocean harvest rate of Sacramento River 

winter-run Chinook salmon is thought to be a function of the Central Valley Chinook salmon 

ocean harvest index (CVI), which is defined as the ratio of ocean catch south of Point Arena, 

California, to the sum of this catch and the escapement of Chinook salmon to Central Valley 

streams and hatcheries. Note that other stocks (e.g., Klamath River Chinook salmon) contribute 

to the catch south of Point Arena, and that fish from the Central Valley are caught in Oregon 

fisheries. This harvest index ranged from 0.55 to nearly 0.80 from 1970 to 1995, when harvest 

regimes were adjusted to protect Sacramento River winter-run Chinook salmon. In 2001, the 

CVI fell to 0.27. The reduction in harvest is presumably at least partly responsible for the record 

spawning escapement of fall-run Chinook salmon (≈ 540,000 fish in 2001) and concurrent 

increases in other Chinook salmon runs in the Central Valley. 

Because they mature before the ocean fishing season, Sacramento River winter-run 

Chinook salmon should have lower harvest rates than fall-run Chinook salmon, if they have 

similar age at maturity. At the time of the last status review, the only information on the harvest 

rate of Sacramento River winter-run Chinook salmon came from a study conducted in the 1970s. 

Hallock and Fisher (1985) reported that the average catch/(catch+escapement) for the 1969–1971 

broodyears was 0.40 for the ocean fishery. For the 1968–1975 period, freshwater sport fisheries 

caught an average of 10% of the Sacramento River winter-run Chinook salmon. 

The recent release of significant numbers of adipose fin-clipped, winter-run Chinook 

salmon provides new, but limited, information on the harvest of Sacramento River winter-run 

Chinook salmon in coastal recreational and troll fisheries. The PFMC’s Sacramento River 

Winter and Spring Chinook Salmon Workgroup (SRWSCW) conducted a cohort reconstruction 

of the 1998 broodyear (PFMC 2003a). Winter-run Chinook salmon are mainly vulnerable to 

ocean fisheries as 3-year-olds. SRWSCW calculated, on the basis of 123 coded-wire-tag 

recoveries, that the ocean fishery impact rate on 3-year-olds was 0.23, and the in-river sport 

fishery impact rate was 0.24. These impacts combine to reduce escapement to 100 (1 – 0.23) 

(1 – 0.24) = 59% of what it would have been in the absence of fisheries, assuming no natural 

mortality during the fishing season. The high estimated rate of harvest in the river sport fishery, 

which arises from the recovery of eight coded-wire tags, was a surprise because salmon fishing is 

closed from January 15 to July 31 to protect Sacramento River winter-run Chinook salmon. The 

tags were recovered in late December and early January, at the tail end of the fishery for late-fallrun Chinook salmon. The estimate of river sport fishery impact is much less certain than the 

ocean fishery impact estimate because of the lower number of tag recoveries, less rigorous tag 

sampling, and larger expansion factors. The California Fish and Game Commission is moving 

forward with an emergency action to amend sport fishing regulations to ban retention of salmon 

caught in the river’s sport fisheries on January 1 rather than January 15. Had such regulations 

been in place in 1999–2000, the freshwater harvest rate would have been 20% of that observed. 

150
11. SACRAMENTO RIVER WINTER-RUN CHINOOK SALMON ESU 

New Hatchery Information 

Livingston Stone NFH was constructed at the base of Shasta Dam in 1997, with the sole 

purpose of helping to restore natural production of winter-run Chinook salmon. Livingston 

Stone NFH was designed as a conservation hatchery with features intended to overcome the 

problems of Coleman NFH (better summer water quality, natal water source). All production is 

adipose fin clipped. Each individual considered for use as broodstock is genotyped to ensure that 

it is a Sacramento River winter-run Chinook salmon. No more than 10% of the broodstock is 

composed of hatchery-origin fish, and no more than 15% of the run is taken for broodstock, with 

a maximum of 120 fish. Figure 117 shows the number of Sacramento River winter-run Chinook 

salmon released by Coleman and Livingston Stone NFHs; Figure 118 shows the number of 

Sacramento River winter-run Chinook salmon spawners taken into the hatchery. 

New Comments 

The California State Water Contractors, the San Luis and Delta-Mendota Water 

Authority, and the Westlands Water District recommend that the listing status of Sacramento 

River winter-run Chinook salmon be changed from endangered to threatened. They base this 

proposal on the recent upturn of adult abundance, recently initiated conservation actions 

(restoration of Battle Creek, ocean harvest reductions, screening of water diversions, remediation 

of Iron Mountain Mine, and improved temperature control), and a putative shift in ocean climate 

in 1999. 

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

160,000

180,000

1959 1964 1969 1974 1979 1984 1989 1994 1999

Year

Number released

Figure 117. Number of juvenile Sacramento River winter-run Chinook salmon released by Coleman and 

Livingston Stone National Fish Hatcheries, 1963–2000. 

151
CHINOOK SALMON

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

160,000

180,000

1960 1965 1970 1975 1980 1985 1990 1995 2000

Year

Number returned

Figure 118. Number of adult Sacramento River winter-run Chinook salmon collected for broodstock by 

Coleman and Livingston Stone National Fish Hatcheries, 1989–2000.

152
12. Central Valley Spring-Run 

Chinook Salmon ESU 

Summary of Previous BRT Conclusions 

The status of the Central Valley spring-run Chinook salmon ESU was formally assessed 

during a coastwide status review (Myers et al. 1998). In June 1999, a BRT convened to update 

the status of this ESU by summarizing information and comments received since the 1997 status 

review and presenting BRT conclusions concerning four deferred Central Valley Chinook 

salmon ESUs (NMFS 1999a). 

Summary of Major Risk Factors and Status Indicators 

Threats to Central Valley spring-run Chinook salmon fall into three broad categories: loss 

of most historical spawning habitat, degradation of remaining habitat, and genetic threats from 

the Feather River Hatchery spring-run Chinook salmon program. Like most spring-run Chinook 

salmon, Central Valley spring-run Chinook salmon require cool freshwater while they mature 

over the summer. In the Central Valley, summer water temperatures are suitable for Chinook 

salmon only above 150–500 m elevations, and most such habitat in the Central Valley is now 

upstream of impassable dams (Figure 119). Only three wild populations of spring-run Chinook 

salmon with consistent spawning runs (on Mill, Deer, and Butte creeks, tributaries to the lower 

Sacramento River draining out of the southern Cascade Mountains) are extant. These 

populations reached quite low abundance levels during the late 1980s (5-year mean population 

sizes of 67–243 spawners), compared to a historical peak abundance of perhaps 700,000 

spawners for the ESU (estimate of Fisher [1994], based on early gillnet fishery catches). The 

upper Sacramento River supports a small spring-run population, but population status is poorly 

documented, and the degree of hybridization with fall-run Chinook salmon is unknown. Of the 

numerous populations once inhabiting Sierra Nevada streams, only the Feather River and Yuba 

River populations remain. The Feather River population depends on Feather River Hatchery 

production and may be hybridized with fall-run Chinook salmon. Little is known about the 

status of the spring-run Chinook salmon population on the Yuba River, other than that it appears 

to be small. 

In addition to outright loss of habitat, Central Valley spring-run Chinook salmon must 

contend with widespread habitat degradation and modification of rearing and migration habitats 

in the natal stream, the Sacramento River, and the Sacramento delta. The natal tributaries do not 

have large impassable dams, like many Central Valley streams, but they do have many small 

153
CHINOOK SALMON

Elevation

<VALUE>

-5 - 150

150.0000001 - 500

500.0000001 - 1,000

1,000.000001 - 4,411

Current spring chinook streams

Keystone dams

.

0 50 100 200 Kilometers

Figure 119. Map of Central Valley, California, showing the locations of spring-run Chinook salmon 

populations with consistent runs, plus Big Chico Creek, which in recent years has had a small 

run. These populations are found in the only watersheds with substantial accessible habitat above 

500 m elevation. Keystone dams are the lowest impassable dams on a river or stream. 

154
12. CENTRAL VALLEY SPRING-RUN CHINOOK SALMON ESU 

hydropower dams and water diversions that, in some years, have greatly reduced or eliminated 

in-stream flows during spring-run migration periods. Problems in the migration corridor include 

unscreened or inadequately screened water diversions, predation by nonnative species, and 

excessively high water temperatures. 

The Feather and Yuba rivers contain populations that are thought to be significantly 

influenced by the Feather River Hatchery spring-run Chinook salmon stock. The Feather River 

Hatchery spring-run Chinook salmon program releases its production far downstream of the 

hatchery,14 causing high rates of straying (CDFG 2001a). There is concern that fall-run and 

spring-run Chinook salmon have hybridized in the hatchery. The BRT viewed the Feather River 

Hatchery stocks as a major threat to the genetic integrity of the remaining wild, spring-run 

Chinook salmon populations. 

Previous BRT Conclusions 

In the original Chinook salmon status review, a majority of the BRT concluded that the 

Central Valley spring-run Chinook salmon ESU was in danger of extinction (Myers et al. 1998). 

Listing of this ESU was deferred, and in the status review update, the BRT majority shifted to 

the view that this ESU was not in danger of extinction, but was likely to become endangered in 

the foreseeable future (NMFS 1999a). A major reason for this shift was data indicating that a 

large run of spring-run Chinook salmon on Butte Creek in 1998 was naturally produced, rather 

than strays from Feather River Hatchery. 

Naturally spawning spring-run Chinook salmon in the Feather River were included in the 

listing, but the Feather River Hatchery stock of spring-run Chinook salmon was excluded. 

Listing status: Threatened. 

New Data and Updated Analyses 

Status Assessments 

In 1998, the CDFG reviewed the status of spring-run Chinook salmon in the Sacramento 

River drainage in response to a petition to list these fish under the California Endangered Species 

Act (CESA) (CDFG 1998). CDFG concluded that spring-run Chinook salmon formed an 

interbreeding population segment distinct from other Chinook salmon runs in the Central Valley. 

CDFG estimated that peak run sizes might have exceeded 600,000 fish in the 1880s, after 

substantial habitat degradation had already occurred. They blamed the decline of spring-run 

Chinook salmon on the early commercial gillnet fishery, water development that blocked access 

to headwater areas, and habitat degradation. Current risks to the remaining populations include 

continued habitat degradation related to water development and use, and the operation of Feather 

River Hatchery. CDFG recommended that Sacramento River spring-run Chinook salmon be 

listed as threatened under the CESA. 

 

14 In 2003, California Department of Fish and Game planned to release half its spring-run Chinook salmon 

production into the river, half into San Pablo Bay. 

155
CHINOOK SALMON

Figure 120. Neighbor joining tree (Cavalli-Sforza and Edwards’ [1967] chord distances) for Central 

Valley Chinook salmon populations, based on 24 polymorphic allozyme loci (Teel unpublished 

data). Populations labeled with only a number are various fall-run Chinook salmon populations. 

The “?” after Feather River spring indicates that California Department of Fish and Game 

biologists are not certain that the fish collected for that sample are truly spring-run Chinook 

salmon. 

Population Structure 

There are preliminary results for two studies of spring-run Chinook salmon population 

structure. The data sets provide two important insights. First, Central Valley spring-run 

Chinook salmon do not appear to be monophyletic, yet wild Central Valley spring-run Chinook 

salmon populations from different basins are more closely related to each other than to fall-run 

Chinook salmon from the same basin. Second, neither Feather River natural-origin nor Feather 

River Hatchery–origin spring-run Chinook salmon are closely related to any of the three wild 

populations, although they are closely related to each other and to Central Valley fall-run 

Chinook salmon. 

David Teel of the NWFSC used allozymes to show that Butte and Deer creeks spring-run 

Chinook salmon are not closely related to sympatric fall-run Chinook salmon populations or the 

Feather River Hatchery spring-run Chinook salmon stock (Figure 120). Feather River Hatchery 

spring-run Chinook salmon, putative Feather River natural spring-run Chinook salmon, and 

Yuba River spring-run Chinook salmon fell into a large cluster composed mostly of natural- and 

hatchery-origin fall-run Chinook salmon. 

156
12. CENTRAL VALLEY SPRING-RUN CHINOOK SALMON ESU 

0.01 

L Fall

FR Sp Fall 

BC Sp

D&M Sp

Winter

900 

998 

1000 

994 

Figure 121. Neighbor joining tree (Cavalli-Sforza and Edwards’ [1967] chord distances) for Central 

Valley Chinook salmon populations, based on 12 microsatellite loci. D&M = Deer and Mill 

Creek; BC = Butte Creek; FR = Feather River; Sp = spring-run Chinook salmon; L Fall = latefall-run Chinook salmon; Winter = winter-run Chinook salmon. The tree was constructed using 

Cavalli-Sforza and Edwards’ measure of genetic distance and the unweighted pair-group method 

arithmetic averaging. Source: Hedgecock (2002). 

Dennis Hedgecock, using 12 microsatellite markers, showed two distinct populations of 

Chinook salmon in the Feather River (Hedgecock 2002). One population is formed by early 

running (spring-run) Chinook salmon, the other by late running fish (fall-run). Once run timing 

was accounted for, hatchery and naturally spawning fish appeared to form a homogeneous 

population. The Feather River spring-run population is most closely related to Feather River 

fall-run (Fst = 0.010) and Central Valley fall-run Chinook salmon (Fst = 0.008) and is distinct 

from spring-run Chinook salmon in Deer, Mill (Fst = 0.016), and Butte (Fst = 0.034) creeks. 

Figure 121 shows the neighbor joining tree with Cavalli-Sforza and Edwards’ (1967) chord 

distances and unweighted pair-group method arithmetic averaging. 

At least two hypotheses could explain the Feather River observations: 

1. An ancestral Mill/Deer/Butte-type spring-run Chinook salmon was forced to hybridize 

with the fall-run Chinook salmon, producing an intermediate form. 

2. The ancestral Feather River spring-run Chinook salmon had a common ancestor with the 

Feather River fall-run Chinook salmon, following the pattern seen in Klamath River 

Chinook salmon but different from the pattern seen in Deer, Butte, and Mill creeks. The 

Feather River and Feather River Hatchery populations have merged. 

Hedgecock argues against the first hypothesis. Feather River fish cluster well within 

Central Valley fall-run Chinook salmon rather than between Mill/Deer/Butte spring-run Chinook 

salmon and Central Valley fall-run Chinook salmon, as would be expected under hypothesis 1. 

Furthermore, there is no evidence from linkage disequilibria that Feather River spring- and fallrun populations are hybridizing, that is, these populations are reproductively isolated. It is 

perhaps not surprising that Feather River spring-run Chinook salmon might have a different 

157
CHINOOK SALMON

ancestry than spring-run Chinook salmon in Mill, Deer, and Butte creeks, because the Feather 

River is in a different ecoregion. 

Historical Habitat Loss 

Yoshiyama et al. (2001) detailed the historical distribution of Central Valley spring-run 

Chinook salmon; they estimated that 72% of salmon spawning and rearing habitat has been lost 

in the Central Valley. This figure is for fall- as well as spring-run Chinook salmon, so the 

amount of spring-run Chinook salmon habitat lost is presumably higher because spring-run 

Chinook salmon spawn and rear in higher elevations, areas more likely to be behind impassable 

dams. They deem the CDFG’s 95% loss estimate (Reynolds et al. 1993) as “perhaps somewhat 

high but probably roughly accurate.” 

Regardless of the cause of the genetic patterns, these new data do not support the current 

configuration of the Central Valley spring-run Chinook salmon ESU. Feather River spring-run 

Chinook salmon do not appear to share a common ancestry or evolutionary trajectory with other 

spring-run Chinook salmon populations in the Central Valley. They share the designation of 

spring-run Chinook salmon, and indeed, the Feather River and Feather River Hatchery have a 

Chinook salmon spawning run that starts much earlier than other Sacramento Basin rivers. 

There is no longer a distinct bimodal distribution to run timing, and substantial fractions of fish 

released as Feather River Hatchery spring-run Chinook salmon have returned during the fall-run 

Chinook salmon period (and vice versa) (CDFG 1998). If Feather River and Feather River 

Hatchery spring-run Chinook salmon are retained in the Central Valley spring-run Chinook 

salmon ESU, then the ESU configuration of the Central Valley late-fall-run Chinook salmon 

ESU (among several others) should be reconsidered for the sake of consistency, because latefall-run Chinook salmon are more distinct genetically, and arguably as distinct in terms of life 

history, than Feather River Hatchery spring-run Chinook salmon. 

Life History 

The CDFG recently began intensive studies of Butte Creek spring-run Chinook salmon 

(Ward et al. 2002). One of the more interesting observations is that while the great majority of 

spring-run Chinook salmon leave Butte Creek as young-of-the-year, yearling outmigrants make 

up roughly 25% of the ocean catch of Butte Creek spring-run Chinook salmon. 

Harvest Information 

Substantial changes in ocean fisheries off central and northern California have occurred 

since the last status review (PFMC 2002a, 2002b). Ocean harvest rate of Central Valley springrun Chinook salmon is thought to be a function of the CVI, which is defined as the ratio of ocean 

catch south of Point Arena, California, to the sum of this catch and the escapement of Chinook 

salmon to Central Valley streams and hatcheries. Note that other stocks (e.g., Klamath River 

Chinook salmon) contribute to the catch south of Point Arena. This harvest index ranged from 

0.55 to nearly 0.80 from 1970 to 1995, when harvest regimes were adjusted to protect winter-run 

Chinook salmon. In 2001, the CVI fell to 0.27. The reduction in harvest is presumably at least 

partly responsible for the record spawning escapement of fall-run Chinook salmon (≈ 540,000 

fish in 2001) and recent increases in spring-run populations. 

158
12. CENTRAL VALLEY SPRING-RUN CHINOOK SALMON ESU 

Coded-wire tagging of juvenile spring-run Chinook salmon in Butte Creek provides some 

limited information on the ocean distribution of this population; but there have not yet been 

enough tag recoveries for a full cohort reconstruction. Butte Creek spring-run Chinook salmon 

have a more northerly distribution than winter-run Chinook salmon (PFMC 2003a), with 

recoveries off Oregon and in the Klamath Management Zone and Fort Bragg areas. The majority 

of recoveries have been south of Point Arena. 

Abundance Data 

The time series of abundance for Mill, Deer, Butte, and Big Chico creeks spring-run 

Chinook salmon have been updated through 2001. These time series show that the increases in 

population that started in the early 1990s have continued (Figure 122). During this period, there 

have been significant habitat improvements (including the removal of several small dams and 

increases in summer flows) in these watersheds, as well as reduced ocean fisheries and a 

favorable terrestrial and marine climate. 

Mill Creek

0

500

1000

1500

2000

2500

3000

3500

4000

1960 1970 1980 1990 2000

Escapement

Deer Creek

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

1960 1970 1980 1990 2000

Butte Creek

0

5000

10000

15000

20000

25000

1960 1970 1980 1990 2000

Year

Big Chico Creek

0

100

200

300

400

500

600

1960 1970 1980 1990 2000

Year

Escapement

Figure 122. Time series of population abundance for Central Valley spring-run Chinook salmon. 

159
CHINOOK SALMON

Table 26. Summary statistics for trend analyses for Central Valley spring-run Chinook salmon ESU 

populations. Numbers in parentheses are 90% confidence intervals. 

Population 

5-year 

mean 

5-year 

min 

5-year 

max λ μ 

Long-term 

trend 

Short-term 

trend 

Sacramento River 

winter-run 

Chinook salmon 

2,191 364 65,683 0.97 

(0.87, 1.09)

–0.10 

(–0.21, 0.01)

–0.14 

(–0.19, –0.09) 

0.26 

(0.04, 0.48)

Butte Creek 

spring-run 

Chinook salmon 

4,513 67 4,513 1.30 

(1.09, 1.60)

0.11 

(–0.05, 0.28)

0.11 

(0.03, 0.19) 

0.36 

(0.03, 0.70)

Deer Creek 

spring-run 

Chinook salmon 

1,076 243 1,076 1.17 

(1.04, 1.35)

0.12 

(–0.02, 0.25)

0.11 

(0.02, 0.21) 

0.16 

(–0.01, 0.33)

Mill Creek 

spring-run 

Chinook salmon 

 491 203 491 1.19 

(1.00, 1.47)

0.09 

(–0.07, 0.26)

0.06 

(–0.04, 0.16) 

0.13 

(–0.07, 0.34)

The time series for Butte, Deer, and Mill creeks are barely amenable to simple analysis 

with the random-walk-with-drift model (Holmes 2001, Lindley 2003). The data series are short, 

and inconsistent methods were used until 1992, when a consistent snorkel survey was initiated 

on Butte and Deer creeks. The full records for these three systems are analyzed with the 

knowledge that there may be significant errors in pre-1992 observations. Table 26 summarizes 

the analyses of these time series. 

It appears that the three spring-run Chinook salmon populations in the Central Valley are 

growing. The current 5-year geometric means for all three populations are also the maximum 5-

year means. All three spring-run Chinook salmon populations have long- and short-term λ > 1 

(λ is defined as exp[μ + σ

2

p / 2]—the mean annual population growth rate), with lower bounds of 

90% confidence intervals generally >1. Long- and short-term trends are also positive, although 

some confidence interval lower bounds are negative. Central Valley spring-run Chinook salmon 

have some of the highest population growth rates in the Central Valley, but other than Butte 

Creek and the hatchery-influenced Feather River, population sizes are relatively small compared 

to fall-run Chinook salmon populations (Figure 123). 

New Hatchery Information 

Feather River Hatchery currently aims to release 5 million spring-run Chinook salmon 

smolts per year, although actual releases have been mostly lower than this goal (Figure 124). 

Returns to the hatchery appear to be directly proportional to the releases (Figure 125). 

New Comments 

The State Water Contractors (SWC 2002) submitted several documents, one of them 

relevant to the status review for Central Valley spring-run Chinook salmon. The document, 

“Reconsideration of the Listing Status of Spring-Run Chinook Salmon within the Feather River 

160
12. CENTRAL VALLEY SPRING-RUN CHINOOK SALMON ESU 

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

2 2.5 3 3.5 4 4.5 5

Log10 (5-year mean population size)

μ

Figure 123. Abundance and growth rate of Central Valley salmonid populations. c = steelhead;  = 

spring-run Chinook; ▲ = winter-run Chinook; • = other Chinook stocks. Error bars represent 

central 0.90 probability intervals for μ estimates. Note: as defined in other sections of the status 

reviews, μ ≈ log(λ). 

Portion of the Central Valley ESU,” argues that Feather River spring-run Chinook salmon should 

not be included in the Central Valley spring-run Chinook salmon ESU and do not otherwise 

warrant protection under the ESA. SWC also suggested that NMFS conduct a series of 

evaluations of the following topics: 

• impact of hatchery operations on the population dynamics and the genetic integrity of 

natural stocks, 

• hatcheries as conservation, 

• effects of mixed-stock fisheries, 

• assessment of the relative roles of different mortality factors, 

• experimental assessment of the effects of river operations, 

• efficacy of various habitat improvements, 

• stock identification for salvage and ocean fishery management, and 

• constant fractional marking. 

The California Farm Bureau Federation (CFBF 2002) submitted comments with several 

attachments calling for the removal of most salmonid ESUs from the endangered species list. 

The attachments included 1) an analysis by Miller (2002) showing that significant and expensive 

changes to water operations in the delta provide fairly modest benefits to Chinook salmon 

populations; 2) “Reconsideration of the Listing Status of Spring-Run Chinook Salmon within the 

Feather River Portion of the Central Valley ESU,” discussed in the preceding paragraph; 3) a 

memo (Palmisano 2003) arguing that because changes in marine climate have been shown to 

influence salmon stocks, other putative causes for declines of salmonid populations must be 

161
CHINOOK SALMON

0.0

1.0

2.0

3.0

4.0

5.0

6.0

1960 1970 1980 1990 2000

Number Released

Figure 124. Number of spring-run Chinook salmon released by Feather River Hatchery, 1967–1999. 

0

1000

2000

3000

4000

5000

6000

7000

8000

1960 1970 1980 1990 2000

Number Returned

Figure 125. Number of spring-run Chinook salmon returning to Feather River Hatchery, 1963–1999. 

overrated. In a CFBF review of the Alsea decision, the CFBF argues that hatchery fish must be 

included in risk analyses. 

Comparison with Previous Data 

The upward trends in abundance of the Mill, Deer, and Butte creek populations noted in 

the most recent previous status review (NMFS 1999a) have apparently continued, probably due 

in part to the combined effects of habitat restoration, reduced fishing effort in the ocean, and 

favorable climatic conditions. New population genetics information confirms previous 

suspicions that Feather River Hatchery and Feather River spring-run Chinook salmon are not 

closely related to the Mill, Deer, and Butte creek spring-run Chinook salmon populations.

162
13. Chinook Salmon BRT Conclusions 

Snake River Fall-Run Chinook Salmon ESU 

A majority (60%) of the BRT votes for the Snake River fall-run Chinook salmon ESU 

fell in the “likely to become endangered” category, with minorities falling in the “danger of 

extinction” and “not likely to become endangered” categories (Table 27). This outcome 

represented a somewhat more optimistic assessment of the status of this ESU than was the case 

at the time of the original status review, when the BRT concluded that Snake River fall-run 

Chinook salmon “face a substantial risk of extinction if present conditions continue” (Waples et 

al. 1991b). The BRT found moderately high risks in all VSP elements, with mean risk matrix 

scores ranging from 3.0 for growth rate/productivity to 3.6 for spatial structure (Table 28). 

On the positive side, the number of natural-origin spawners in 2001 was well in excess of 

1,000 for the first time since counts at Lower Granite Dam began in 1975. Management actions 

have reduced (but not eliminated) the fraction of fish passing Lower Granite Dam that are strays 

from out-of-ESU hatchery programs. Returns in the last 2 years also reflect an increasing 

contribution from supplementation programs based on the native Lyons Ferry Hatchery 

broodstock. With the exception of the increase in 2001, the ESU has fluctuated between 

approximately 500 and 1,000 adults, suggesting a somewhat higher degree of stability in growth 

rate and trends than is seen in many other salmon populations. 

Table 27. Tally of the FEMAT vote distribution regarding the status of nine Chinook salmon ESUs 

reviewed by the Chinook salmon BRT. Each of 15 BRT members allocated 10 points among the 

three status categories. 

ESU 

At risk of 

extinction 

Likely to become 

endangered 

Not likely to become 

endangered 

Snake River fall run 38 91 21 

Snake River spring/summer run 30 102 18 

Upper Columbia River spring run 79 67 4 

Puget Sound 12 111 27 

Lower Columbia River 25 107 18 

Upper Willamette River 32 105 13 

California Coastala 36 100 13 

Sacramento River winter runb 78 49 3 

Central Valley spring runb 35 90 5 a

 One BRT member assigned 9 points. 

b

 Votes tallied for 13 BRT members. 

163 
CHINOOK SALMON

Table 28. Summary of risk scores (1 = low to 5 = high) for four VSP categories (see subsection, Factors 

Considered in Status Assessments, for a description of the risk categories) for the nine Chinook 

salmon ESUs reviewed. Data presented are means (range). 

ESU Abundance 

Growth rate/ 

productivity 

Spatial structure 

and connectivity Diversity 

Snake River fall run 3.4 (2–5) 3.0 (2–5) 3.6 (2–5) 3.5 (2–5) 

Snake River spring/summer run 3.6 (2–5) 3.5 (3–5) 2.2 (1–3) 2.3 (1–3) 

Upper Columbia River spring run 4.4 (3–5) 4.5 (3–5) 2.9 (2–4) 3.5 (2–5) 

Puget Sound 3.3 (2–4) 3.6 (3–4) 2.9 (2–4) 3.2 (2–4) 

Lower Columbia River 3.2 (2–4) 3.7 (3–5) 3.5 (3–4) 3.9 (3–5) 

Upper Willamette River 3.7 (2–5) 3.1 (2–5) 3.6 (3–4) 3.2 (2–4) 

California Coastala 3.9 (3–5) 3.3 (3–4) 3.2 (2–4) 3.1 (2–4) 

Sacramento River winter runb 3.7 (3–5) 3.5 (2–5) 4.8 (4–5) 4.2 (3–5) 

Central Valley spring runb 3.5 (3–4) 2.8 (2–4) 3.8 (3–5) 3.8 (3–5) a

 One BRT member assigned 9 points. 

b

 Votes tallied for 13 BRT members. 

In spite of the recent increases, however, the recent geometric mean number of naturally 

produced spawners is still less than 1,000, a very low number for an entire ESU. Because of the 

large fraction of naturally spawning hatchery fish, it is difficult to assess the productivity of the 

natural population. The relatively high risk matrix scores for spatial structure and diversity 

(3.5–3.6) reflect the BRT’s concerns that a large fraction of historical habitat for this ESU is 

inaccessible, diversity associated with those populations has been lost, the single remaining 

population is vulnerable to variable environmental conditions or catastrophes, and continuing 

immigration from outside the ESU at levels that are higher than occurred historically. Some 

BRT members were concerned that the efforts to remove stray, out-of-ESU hatchery fish only 

occur at Lower Granite Dam, well upstream of the geographic boundary of this ESU. Specific 

concerns are that natural spawners in lower river areas will be heavily affected by strays from 

Columbia River hatchery programs, and that this approach effectively removes the natural buffer 

zone between the Snake River ESU and Columbia River ocean-type Chinook salmon. The 

effects of these factors on ESU viability are not known, because the extent of natural spawning 

in areas below Lower Granite Dam is not well understood, except in the lower Tucannon River. 

Snake River Spring/Summer-Run Chinook Salmon ESU 

About two-thirds (68%) of the BRT votes for the Snake River spring/summer-run 

Chinook salmon ESU fell in the “likely to become endangered” category, with minorities falling 

in the “danger of extinction” and “not likely to become endangered” categories (Table 27). As 

indicated by mean risk matrix scores, the BRT had much higher concerns about abundance (3.6) 

and growth rate/productivity (3.5) than for spatial structure (2.2) and diversity (2.3) (Table 28). 

Although there are concerns about loss of an unquantified number of spawning 

aggregations that historically may have provided connectivity between headwater populations, 

natural spawning in this ESU still occurs in a wide range of locations and habitat types. 

164
13. CHINOOK SALMON BRT CONCLUSIONS

Like many other ESUs, this one saw a large increase in escapement in many (but not all) 

populations in 2001. The BRT considered this an encouraging sign, particularly given the record 

low returns seen in many of these populations in the mid-1990s. However, recent abundance in 

this ESU is still short of the levels that the proposed recovery plan for Snake River salmon 

indicated should be met over at least an 8-year period (NMFS 1995a). The BRT considered it a 

positive sign that the nonnative Rapid River broodstock has been phased out of the Grande 

Ronde system, but the relatively high level of both production/mitigation and supplementation 

hatcheries in this ESU leads to ongoing risks to natural populations and makes it difficult to 

assess trends in natural productivity and growth rate. 

Upper Columbia River Spring-Run Chinook Salmon ESU 

The BRT’s assessment of the overall risks faced by the Upper Columbia River spring-run 

Chinook salmon ESU were divided, with a slight majority (53%) of the votes cast in the “danger 

of extinction” category and a substantial minority (45%) in the “likely to be endangered” 

category (Table 27). The mean risk matrix scores reflect strong ongoing concerns regarding 

abundance (4.4) and growth rate/productivity (4.5) in this ESU and somewhat less (but still 

significant) concerns for spatial structure (2.9) and diversity (3.5) (Table 28). 

Many populations in this ESU have rebounded somewhat from the critically low levels 

that immediately preceded the last status review evaluation, which was reflected in the 

substantial minority of BRT votes not cast in the “danger of extinction” category. Although the 

BRT considered this an encouraging sign, the last year or two of higher returns come on the 

heels of a decade or more of steep declines to all-time record low escapements. In addition, this 

ESU continues to have a very large influence from hatchery production, both from 

production/mitigation and supplementation programs. The extreme management measures taken 

in an effort to maintain populations in this ESU during some years in the late 1990s (collecting 

all adults from major basins at downstream dams) are a strong indication of the ongoing risks to 

this ESU, although the associated hatchery programs may ultimately play a role in helping to 

restore self-sustaining natural populations. 

Puget Sound Chinook Salmon ESU 

A majority (74%) of the BRT votes for the Puget Sound Chinook salmon ESU fell in the 

“likely to become endangered” category, with minorities falling in the “danger of extinction” and 

“not likely to become endangered” categories (Table 27). The BRT found moderately high risks 

in all VSP elements, with mean risk matrix scores ranging from 2.9 for spatial structure to 3.6 for 

growth rate/productivity (Table 28). 

Most population indices for this ESU have not changed substantially since the last BRT 

assessment. The Puget Sound TRT has identified approximately 31 historical populations, of 

which nine are believed to be extinct; most of the populations that have been lost were early run. 

Other concerns noted by the BRT are the concentration of the majority of natural production in 

just two basins, high levels of hatchery production in many areas of the ESU, and widespread 

loss of estuary and lower floodplain habitat diversity (and, likely, associated life history types). 

Although in the last 2 to 3 years populations in this ESU have not experienced the sharp 

165
CHINOOK SALMON

increases seen in many other ESUs, more populations increased than decreased over the 4 years 

since the last BRT assessment. After adjusting for changes in harvest rates, however, trends in 

productivity are less favorable. Most populations are relatively small, and recent natural 

production within the ESU is only a fraction of estimated historical run size. On the positive 

side, harvest rates for all populations have been reduced from their peaks in the 1980s, and some 

hatchery reforms have been implemented (e.g., elimination of many net pen programs that were 

leading to widespread straying, and transition of other programs to more local broodstocks). The 

BRT felt that these management changes should help facilitate recovery if other limiting factors 

(especially habitat degradation) are also addressed. The BRT felt that the large recovery effort 

organized around the Puget Sound Shared Strategy was a positive step because it could help to 

link and coordinate efforts in many separate, local watersheds. 

Lower Columbia River Chinook Salmon ESU 

A majority (71%) of the BRT votes for the Lower Columbia River Chinook salmon ESU 

fell in the “likely to become endangered” category, with minorities falling in the “danger of 

extinction” and “not likely to become endangered” categories (Table 27). Moderately high 

concerns for all VSP elements are indicated by mean risk matrix scores ranging from 3.2 for 

abundance to 3.9 for diversity (Table 28). 

The BRT still considered all of the risk factors identified in previous reviews. The WLCTRT estimated that 8 to 10 historical populations in this ESU have been extirpated, most of them 

spring-run populations. Near loss of that important life history type remains an important BRT 

concern. Although some natural production currently occurs in 20 or so populations, only one 

exceeds 1,000 spawners. High hatchery production continues to pose genetic and ecological 

risks to natural populations and to mask their performance. Most populations in this ESU have 

not seen as pronounced increases in recent years as occurred in many other geographic areas. 

Upper Willamette River Chinook Salmon ESU 

A majority (70%) of the BRT votes for the Upper Willamette River Chinook salmon ESU 

fell in the “likely to become endangered” category, with minorities falling in the “danger of 

extinction” and “not likely to become endangered” categories (Table 27). The BRT found 

moderately high risks in all VSP elements (mean risk matrix scores ranged from 3.1 for growth 

rate/productivity to 3.6 for spatial structure) (Table 28). 

Although the number of adult spring-run Chinook salmon crossing Willamette Falls is in 

the same range (about 20,000–70,000) it has been in for the last 50 years, a large fraction of 

these are hatchery produced. The score for spatial structure reflects BRT concern that perhaps a 

third of the historical habitat used by fish in this ESU is currently inaccessible behind dams, and 

the BRT remained concerned that natural production in this ESU is restricted to a very few areas. 

Increases in natural production in the last 3 to 4 years in the largest remaining population (the 

McKenzie) were considered encouraging by the BRT. With the relatively large incidence of 

hatchery fish, it is difficult to determine trends in natural production. 

166
13. CHINOOK SALMON BRT CONCLUSIONS

California Coastal Chinook Salmon ESU 

A majority (67%) of the BRT votes for the California Coastal Chinook salmon ESU fell 

in the “likely to become endangered” category, with votes falling in the “danger of extinction” 

category outnumbering those in “not warranted” category by nearly two to one (Table 27). The 

BRT found moderately high risks in all VSP elements, with mean risk matrix scores ranging 

from 3.1 for diversity to 3.9 for abundance (Table 28). 

The BRT was concerned about continued evidence of low population sizes relative to 

historical abundance and mixed trends in the few time series of abundance indices available for 

analysis, and by the low abundances and potential extirpations of populations in the southern part 

of the ESU. The BRT’s concerns regarding genetic integrity of this ESU were moderate or low 

relative to similar issues for other ESUs because 1) hatchery production in this ESU is on a minor 

scale, and 2) current hatchery programs are largely focused on supplementing and restoring local 

populations. However, the BRT did have concerns with respect to diversity that were based 

largely on the loss of spring-run Chinook salmon in the Eel River basin and elsewhere in the 

ESU, and to a lesser degree on the potential loss of diversity concurrent with low abundance or 

extirpation of populations in the southern portion of the ESU. Overall, the BRT was very 

concerned about the paucity of information and resultant uncertainty associated with estimates of 

abundance, natural productivity, and distribution of Chinook salmon in this ESU. 

Sacramento River Winter-Run Chinook Salmon ESU 

A majority (60%) of the BRT votes for the Sacramento River winter-run Chinook salmon 

ESU fell into the “in danger of extinction” category, with a minority (38%) voting for the “likely 

to become endangered” and only 2% voting for “not warranted.” (Table 27). The main VSP 

concerns were in the spatial structure and diversity categories (4.8 and 4.2, respectively), 

although there was significant concern about the abundance and productivity categories (3.7 and 

3.5, respectively) (Table 28). 

The BRT’s main concerns relate to the lack of diversity within this ESU. The BRT was 

very troubled that this ESU is represented by a single population that has been displaced from its 

historical spawning habitat into an artificial habitat created and maintained by a dam. The BRT 

presumed that several independent populations of winter-run Chinook salmon were merged into 

a single population, with the potential for a significant loss of life history and genetic diversity. 

Furthermore, the population has passed through at least two recent bottlenecks—one when 

Shasta Dam was filled and another in the late 1980s and early 1990s—that probably further 

reduced genetic diversity. The population has been removed from the environment where it 

evolved, dimming its long-term prospects for survival. The BRT was modestly heartened by the 

increase in abundance since the lows of the late 1980s and early 1990s. 

Central Valley Spring-Run Chinook Salmon ESU 

A large majority (69%) of the BRT votes for the Central Valley spring-run Chinook 

salmon ESU fell into the “likely to become endangered” category, with a minority (27%) of 

votes going to “in danger of extinction” and (4%) “not warranted” (Table 27). Concerns about 

167
CHINOOK SALMON

abundance, spatial structure, and diversity (3.5–3.8) were roughly equal, with less concern about 

productivity (2.8) (Table 28). 

A major BRT concern was loss of diversity caused by the extirpation of spring-run 

Chinook salmon populations from most of the Central Valley, including all San Joaquin River 

tributaries. The only populations left in the Sierra Nevada ecoregion are supported by the 

Feather River Hatchery. Another major BRT concern was the small number and location of 

extant spring-run Chinook salmon populations—only three streams, originating in the southern 

Cascade Mountains, support self-sustaining runs of spring-run Chinook salmon, which are close 

together, increasing their vulnerability to catastrophe. Two of the three extant populations are 

fairly small, and all were recently quite small. The BRT was also concerned about the Feather 

River Hatchery spring-run Chinook salmon population, which is not in the ESU but does 

produce fish that potentially could interact with other spring-run Chinook salmon populations, 

especially given the off-site release of the production.

168
STEELHEAD

169 
CHINOOK SALMON

170
14. Background and History 

of Steelhead Listings 

Background 

Steelhead is the name commonly applied to the anadromous form of the biological 

species Oncorhynchus mykiss. The present distribution of steelhead extends from the 

Kamchatka Peninsula in Asia, east to Alaska, and south to southern California (NMFS 1999a), 

although the historical range of O. mykiss extended at least to the Mexico border (Busby et al. 

1996). O. mykiss exhibit perhaps the most complex suite of life history traits of any species of 

Pacific salmonid. They can be anadromous or freshwater resident (and under some 

circumstances, apparently yield offspring of the opposite form). Those that are anadromous can 

spend up to 7 years in freshwater prior to smoltification, then spend up to 3 years in salt water 

prior to first spawning. The half-pounder life history type in southern Oregon and northern 

California spends only 2 to 4 months in salt water after smoltification, then returns to freshwater 

and outmigrates to sea again the following spring without spawning. This species can also 

spawn more than once (iteroparous), whereas all other species of Oncorhynchus except O. clarki

spawn once then die (semelparous). The anadromous form is under the jurisdiction of NMFS, 

while the resident freshwater forms, usually called rainbow or redband trout, are under the 

jurisdiction of USFWS. 

Although no subspecies are currently recognized within any species of Pacific salmon, 

Behnke (1992) proposed that two subspecies of O. mykiss with anadromous life history occur in 

North America: O. mykiss irideus (the coastal subspecies), which includes coastal populations 

from Alaska to California (including the Sacramento River), and O. mykiss gairdneri (the inland 

subspecies), which includes populations from the interior Columbia, Snake, and Fraser rivers. In 

the Columbia River, the boundary between the two subspecies occurs at approximately the 

Cascade Crest. A third subspecies of anadromous O. mykiss (O. mykiss mykiss) occurs in 

Kamchatka, and several other subspecies of O. mykiss are recognized that have only resident 

forms (Behnke 1992). 

Within the range of West Coast steelhead, spawning migrations occur throughout the 

year, with seasonal peaks of activity. In a given river basin there may be one or more peaks in 

migration activity; because these runs are usually named for the season in which the peak occurs, 

some rivers may have runs known as winter-, spring-, summer-, or fall-run steelhead. For 

example, large rivers, such as the Columbia, Rogue, and Klamath rivers, have migrating adult 

steelhead at all times of the year. Local variations in the names identify the seasonal runs 

of steelhead; in northern California, some biologists have retained the terms spring- and fall-run 

steelhead to describe what others would call summer-run steelhead. 

171 
STEELHEAD

Steelhead can be divided into two basic reproductive ecotypes, based on the state of 

sexual maturity at the time of river entry and duration of spawning migration (Burgner et al. 

1992). The stream-maturing type (summer-run steelhead in the Pacific Northwest and northern 

California) enters freshwater in a sexually immature condition between May and October and 

requires several months to mature and spawn. The ocean-maturing type (winter-run steelhead in 

the Pacific Northwest and northern California) enters freshwater between November and April, 

with well-developed gonads, and spawns shortly thereafter. In basins with both summer and 

winter steelhead runs, the summer run appears to occur where habitat is not fully used by the 

winter run or where a seasonal hydrologic barrier, such as a waterfall, separates them. Summerrun steelhead usually spawn farther upstream than winter-run steelhead (Withler 1966, Roelofs 

1983, Behnke 1992). Coastal streams are dominated by winter-run steelhead, whereas inland 

steelhead of the Columbia River basin are almost exclusively summer-run steelhead. Winter-run 

steelhead may have been excluded from inland areas of the Columbia River basin by Celilo Falls 

or by the considerable migration distance from the ocean. The Sacramento–San Joaquin River 

basin may have historically had multiple runs of steelhead, which probably included both oceanand stream-maturing stocks (CDFG 1995, McEwan and Jackson 1996). These steelhead are 

referred to as winter-run steelhead by the California Department of Fish and Game (CDFG); 

however, some biologists call them fall-run steelhead (Cramer et al. 1995). 

Inland steelhead of the Columbia River basin, especially the Snake River subbasin, are 

commonly referred to as either A-run or B-run. These designations are based on a bimodal 

migration of adult steelhead at Bonneville Dam (235 km from the mouth of the Columbia River) 

and differences in age (1- versus 2-ocean) and adult size observed among Snake River steelhead. 

It is unclear, however, whether life history and body-size differences observed upstream are 

correlated back to the groups forming the bimodal migration observed at Bonneville Dam. 

Furthermore, the relationship between patterns observed at the dams and distribution of adults in 

spawning areas throughout the Snake River basin is not well understood. A-run steelhead are 

believed to occur throughout the steelhead-bearing streams of the Snake River basin and the 

inland Columbia River; B-run steelhead are thought to be produced only in the Clearwater, 

Middle Fork Salmon, and South Fork Salmon rivers (IDFG 1994). 

The half-pounder is an immature steelhead that returns to freshwater after only 2 to 4 

months in the ocean, generally overwinters in freshwater, then outmigrates again the following 

spring. Half-pounders are generally less than 400 mm and are reported only from the Rogue, 

Klamath, Mad, and Eel rivers of southern Oregon and northern California (Snyder 1925, Kesner 

and Barnhart 1972, Everest 1973, Barnhart 1986); however, it has been suggested that as mature 

steelhead, these fish may only spawn in the Rogue and Klamath river basins (Cramer et al. 

1995). Various explanations for this unusual life history have been proposed, but there is still no 

consensus as to what, if any, advantage it affords to the steelhead of these rivers. 

In May 1992, the Oregon Natural Resources Council (ONRC) and 10 copetitioners 

petitioned NMFS to list Oregon’s Illinois River winter-run steelhead (ONRC et al. 1992). 

NMFS concluded that Illinois River winter-run steelhead by themselves did not constitute an 

ESA “species” (Busby et al. 1993, NMFS 1993b). In February 1994, NMFS received a petition 

seeking protection under the ESA for 178 populations of steelhead (anadromous O. mykiss) in 

Washington, Idaho, Oregon, and California. At the time, NMFS was conducting a status review 

172
14. BACKGROUND AND HISTORY OF STEELHEAD LISTINGS

of coastal steelhead populations (O. mykiss irideus) in Washington, Oregon, and California. In 

response to the broader petition, NMFS expanded the ongoing status review to include inland 

steelhead (O. mykiss gairdneri) occurring east of the Cascade Mountains in Washington, Idaho, 

and Oregon. 

In 1995, the steelhead BRT met to review the biology and ecology of West Coast 

steelhead. After considering available information on steelhead genetics, phylogeny, and life 

history; freshwater ichthyogeography; and environmental features that may affect steelhead, the 

BRT identified 15 ESUs—12 coastal forms and 3 inland forms. After considering available 

information on population abundance and other risk factors, the BRT concluded that 5 steelhead 

ESUs (Central California Coast, South-Central California Coast, Southern California, California 

Central Valley, and Upper Columbia River) were presently in danger of extinction, 5 steelhead 

ESUs (Lower Columbia River, Oregon Coast, Klamath Mountains Province, Northern 

California, and Snake River Basin) were likely to become endangered in the foreseeable future, 

4 steelhead ESUs (Puget Sound, Olympic Peninsula, Southwest Washington, and Upper 

Willamette River) were not presently in significant danger of becoming extinct or endangered, 

although individual stocks within these ESUs may be at risk, and 1 steelhead ESU (Middle 

Columbia River) was not presently in danger of extinction but the BRT was unable to reach a 

conclusion as to its risk of becoming endangered in the foreseeable future. 

Of the 15 steelhead ESUs identified by NMFS, 5 are not listed under the ESA: Southwest 

Washington, Olympic Peninsula, and Puget Sound (NMFS 1996a), Oregon Coast (NMFS 

1998c), and Klamath Mountain Province (NMFS 2001c); 8 are listed as threatened: Snake River 

Basin, Central California Coast and South-Central California Coast (NMFS 1997b), Lower 

Columbia River, California Central Valley (NMFS 1998c), Upper Willamette River, Middle 

Columbia River (NMFS 1999b), and Northern California (NMFS 2000), and 2 are listed as 

endangered: Upper Columbia River and Southern California (NMFS 1997b). 

The West Coast Steelhead BRT15 met in January, March, and April 2003 to discuss new 

data received and to determine whether the new information warranted any modification of the 

original BRT’s conclusions. This report summarizes new information and the preliminary BRT 

conclusions on the following ESUs: Snake River Basin, Upper Columbia River, Middle 

Columbia River, Lower Columbia River, Upper Willamette River, Northern California, Central 

California Coast, South-Central California Coast, Southern California, and California Central 

Valley. 

Resident Fish 

As mentioned earlier, O. mykiss exhibits varying degrees of anadromy. Nonanadromous 

forms are usually called rainbow trout; however, nonanadromous inland O. mykiss are often 

 

15The BRT for the updated status review for West Coast steelhead included from the NMFS Northwest Fisheries 

Science Center: Thomas Cooney, Dr. Robert Iwamoto, Gene Matthews, Dr. Paul McElhany, Dr. James Myers, Dr. 

Mary Ruckelshaus, Dr. Thomas Wainwright, Dr. Robin Waples, and Dr. John Williams; from NMFS Southwest 

Fisheries Science Center: Dr. Peter Adams, Dr. Eric Bjorkstedt, Dr. David Boughton, Dr. John Carlos Garza, Dr. 

Steve Lindley, and Dr. Brian Spence; from the U.S. Fish and Wildlife Service, Abernathy, WA: Dr. Donald 

Campton; and from the USGS Biological Resources Division, Seattle: Dr. Reginald Reisenbichler. 

173
STEELHEAD

called Columbia River redband trout. A form that occurs in the upper Sacramento River is called 

Sacramento redband trout. Although the anadromous and nonanadromous forms have long been 

taxonomically classified within the same species, in any given area the exact relationship 

between the forms is not well understood. In coastal populations, it is unusual for the two forms 

to co-occur; they are usually separated by a natural or man-made migration barrier. Cooccurrence of the two forms in inland populations appears to be more frequent. Where they cooccur, “it is possible that offspring of resident fish may migrate to the sea, and offspring of 

steelhead may remain in streams as resident fish” (Burgner et al. 1992, p. 6; Shapovalov and Taft 

1954). Mullan et al. (1992) found evidence that in very cold streams, juvenile steelhead had 

difficulty attaining mean threshold size for smoltification and concluded that most fish in the 

Methow River in Washington that did not emigrate downstream early in life were thermally fated 

to a resident life history regardless of whether they were the progeny of anadromous or resident 

parents. Additionally, Shapovalov and Taft (1954) reported evidence of O. mykiss maturing in 

freshwater and spawning prior to their first ocean migration; this life history variation has also been 

found in cutthroat trout (O. clarki) and some male Chinook salmon (O. tshawytscha). 

As part of this status review update, a concerted effort was made to collect biological 

information for resident populations of O. mykiss. Information from listed ESUs in Washington, 

Oregon, and Idaho is contained in a draft report by Kostow (2003) and summarized in Appendix 

B, Table B-1; relevant information for specific ESUs is presented in subsequent sections. 

Information about resident O. mykiss populations in California is in Appendix B, Table B-2. 

The BRT had to consider in more general terms how to conduct an overall risk 

assessment for an ESU that includes both resident and anadromous populations, particularly 

when the resident individuals may outnumber the anadromous ones but their biological 

relationship is unclear or unknown. Some guidance is found in Waples (1991), which outlines 

the scientific basis for the NMFS ESU policy. That paper suggests that an ESU that contains 

both forms could be listed based on a threat to only one of the life history traits “if the trait were 

genetically based and loss of the trait would compromise the ‘distinctiveness’ of the population” 

(p. 16). That is, if anadromy were considered important in defining the distinctiveness of the 

ESU, loss of that trait would be a serious ESA concern. In discussing this issue, the NMFS ESU 

policy (NMFS 1991a) affirmed the importance of considering the genetic basis of life history 

traits such as anadromy and recognized the relevance of a question posed by one commenter: 

“What is the likelihood of the nonanadromous form giving rise to the anadromous form after the 

latter has gone locally extinct?” 

The BRT discussed another important consideration—the role anadromous populations 

play in providing connectivity and linkages among different spawning populations within an 

ESU. An ESU in which all anadromous populations are lost and the remaining resident 

populations are fragmented and isolated would have a very different future evolutionary 

trajectory than one in which all populations remain linked genetically and ecologically by 

anadromous forms. Furthermore, in many (if not all) O. mykiss ESUs, the geographic area used 

by anadromous (but not resident) fish may represent a “significant portion of the range” of the 

ESA species, especially if considering the area the marine migration encompasses. 

174
14. BACKGROUND AND HISTORY OF STEELHEAD LISTINGS

In spite of concerted efforts to collect and synthesize available information on resident 

forms of O. mykiss, existing data are very sparse, particularly regarding interactions between 

resident and anadromous forms (Kostow 2003). The BRT was frustrated by the complex 

questions involving the relationship between resident and anadromous forms, given this paucity 

of key information. To focus the issue, the BRT considered a hypothetical scenario that has 

varying degrees of relevance to individual steelhead ESUs. In this scenario, the once-abundant 

and widespread anadromous life history is extinct, or nearly so, but relatively healthy native 

populations of resident fish remain in many geographic areas. The question the BRT considered 

was: Under what circumstances would you conclude that such an ESU was not in danger of 

extinction or likely to become endangered? The BRT identified the required conditions as follows: 

• The resident forms are capable of maintaining connectivity among populations to the 

extent that the ESU’s historical evolutionary processes are not seriously disrupted. 

• The anadromous life history is not permanently lost from the ESU but can be regenerated 

from the resident forms. 

Regarding the first criterion, although some resident salmonid forms are known to 

migrate considerable distances in freshwater, extensive river migrations have not been 

demonstrated to be an important behavior for resident O. mykiss, except in rather specialized 

circumstances (e.g., forms that migrate from a stream to a large lake or reservoir as a surrogate 

for the ocean). Therefore, the BRT felt that loss of the anadromous form would, in most cases, 

substantially change the character and future evolutionary potential of steelhead ESUs. 

Regarding the second criterion, it is well established that resident forms of O. mykiss can 

occasionally produce anadromous migrants, and vice versa (Mullan et al. 1992, Zimmerman and 

Reeves 2000, Kostow 2003), just as has been shown for other salmonid species such as O. nerka

(Foerster 1947, Fulton and Pearson 1981, Kaeriyama et al. 1992), coastal cutthroat trout (O. 

clarki clarki) (Griswold 1996, Johnson et al. 1999), brown trout (Salmo trutta) (Jonsson 1985), 

and Arctic char (Salvelinus alpinus) (Nordeng 1983). However, available information indicates 

that these occurrences are relatively rare, and there is even less empirical evidence that, once 

lost, a self-sustaining anadromous run can be regenerated from a resident salmonid population. 

Although regeneration must have occurred during the evolutionary history of O. mykiss, the BRT 

found no reason to believe that such an event would occur with any frequency or within a 

specified time period. This would be particularly true if the conditions that promote and support 

the anadromous life history continue to deteriorate. In this case, the expectation would be that 

natural selection would gradually eliminate the migratory or anadromous trait from the 

population, as individuals inheriting a tendency for anadromy migrate out of the population but 

do not survive to return as adults and pass on their genes to subsequent generations. 

Given the above considerations, the BRT focused primarily on information for 

anadromous populations in the risk assessments for steelhead ESUs. This was particularly true 

with respect to case 3 resident fish populations, the vast majority of which are of uncertain ESU 

status. However, as discussed in Section 25, BRT Conclusions, the presence of relatively 

numerous, native resident fish was considered to be a mitigating risk factor for some ESUs. 

175
15. Snake River Basin Steelhead ESU 

The Snake River Basin steelhead ESU is distributed throughout the Snake River drainage 

system, including tributaries in southwest Washington, eastern Oregon, and north/central Idaho 

(NMFS 1996a). Snake River steelhead migrate a substantial distance from the ocean (up to 

1,500 km) and use high-elevation tributaries (typically 1,000–2,000 m above sea level) for 

spawning and juvenile rearing. Snake River steelhead occupy habitat that is considerably 

warmer and drier (on an annual basis) than other steelhead ESUs. Snake River basin steelhead 

are generally classified as summer run, based on their adult run-timing patterns. Summer-run 

steelhead enter the Columbia River from late June to October. After holding over the winter, 

summer-run steelhead spawn the following spring (March to May). Managers classify upriver 

summer steelhead runs into two groups based primarily on ocean age and adult size on return to 

the Columbia River: A-run steelhead are predominantly age-1 ocean fish, while B-run steelhead 

are larger, predominated by age-2 ocean fish.

With the exception of the Tucannon River and some small tributaries to the mainstem 

Snake River, the tributary habitat used by Snake River Basin steelhead ESU is above Lower 

Granite Dam. Major groupings of populations and subpopulations can be found in 1) the Grande 

Ronde River system; 2) the Imnaha River drainage; 3) the Clearwater River drainages; 4) the 

South Fork Salmon River; 5) the smaller mainstem tributaries before the confluence of the 

mainstem Snake River; 6) the Middle Fork Salmon River, 7) the Lemhi and Pahsimeroi rivers, 

and 8) upper Salmon River tributaries. 

Resident O. mykiss are believed to be present in many of the drainages used by Snake 

River steelhead. Very little is known about interactions between co-occurring resident and 

anadromous forms within this ESU. The following review of abundance and trend information 

focuses on information directly related to the anadromous form. 

Historical Returns 

Although direct historical estimates of production from the Snake River basin are not 

available, the basin is believed to have supported more than half the total steelhead production 

from the Columbia River basin (Mallet 1974). There are some historical estimates of returns to 

portions of the drainage. Lewiston Dam, on the lower Clearwater River, began operation in 

1927. Counts of steelhead passing through the adult fish ladder at the dam reached 40,000–

60,000 in the early 1960s (Cichosz et al. 2001). Based on relative drainage areas, the Salmon 

River basin likely supported substantial production as well. In the early 1960s, returns to the 

Grande Ronde and Imnaha rivers may have exceeded 15,000 and 4,000 steelhead per year, 

respectively (ODFW 1991). Extrapolations from tag-recapture data indicate that the natural 

steelhead return to the Tucannon River may have exceeded 3,000 adults in the mid-1950s 

(Thompson et al. 1958). 

176 
15. SNAKE RIVER BASIN STEELHEAD ESU 

Summary of Previous BRT Conclusions 

The primary concern regarding Snake River steelhead identified in the 1998 status review 

was a sharp decline in natural stock returns beginning in the mid-1980s. Of 13 trend indicators 

at that time, 9 were in decline and 4 were increasing. In addition, Idaho Department of Fish and 

Game (IDFG) parr survey data indicated declines for both A-run and B-run steelhead in wild and 

natural stock areas. The high proportion of hatchery fish in the run was also identified as a 

concern, particularly because of the lack of information on the actual contribution of hatchery 

fish to natural spawning. The review recognized that some wild spawning areas have relatively 

little hatchery spawning influence (Selway, lower Clearwater, Middle and South Fork Salmon, 

and lower Salmon rivers). In other areas, such as the upper Salmon River, there is likely little or 

no natural production of locally native steelhead. The review identified threats to genetic 

integrity from past and present hatchery practices as a concern. A concern for the North Fork 

Clearwater stock was also identified: the stock is currently maintained through the Dworshak 

Hatchery program but cut off from access to its native tributary by Dworshak Dam. The 1998 

review also highlighted concerns for widespread habitat degradation and flow impairment 

throughout the Snake River basin and for substantial modification of the seaward migration 

corridor by hydroelectric power development on the Snake and mainstem Columbia rivers. 

The previous BRT status review noted that the aggregate trend in abundance as measured 

by ladder counts at the uppermost Snake River dam (Lower Granite Dam, since 1972) has been 

upward since the mid-1970s, while the aggregate return of naturally produced steelhead was 

downward for the same period (Table 29). The decline in natural production was especially 

pronounced in the later years in the series. 

Listing status: Threatened. 

New Data and Updated Analyses 

Abundance and Trends 

Estimates of annual returns to specific production areas are not available for most of the 

Snake River Basin steelhead ESU. Estimates are available for two tributaries below Lower 

Granite Dam (Tucannon and Asotin creeks). Annual ladder counts at the dam, and associated 

sampling information, allow for an estimate of aggregate returns to the Snake River basin. 

In addition, area-specific estimates are available for the Imnaha River and two major 

sections of the Grande Ronde River system. Updated estimates of return levels are summarized 

in Table 29. Returns to Lower Granite Dam remained at relatively low levels through the 1990s; 

the 2001 run size at Lower Granite Dam was substantially higher relative to the 1990s (see 

Figures 126 and 127). The recent geometric mean abundance was down for the Tucannon River 

relative to the last BRT status review. Returns to the Imnaha and Grande Ronde river survey 

areas were generally higher relative to the early 1990s (see Figures 128–130). 

177
Table 29. Summary of abundance and trend estimates for the Snake River Basin steelhead ESU. Interim delisting target le

the text. 

Recent 5-year geometric mean 

Total Natural 

Short-term trend 

(%/year) 

Populations 

5-year mean % 

natural origin Mean (range) Current Previous Current Previous 

Tucannona 26 [44]e 407 (257–628) 106 140 –3.7 –18.3 Lower Granite Runb 14 106,175 (70,721– 259,145) 14,864 9,500 +6.1 +6.9 

Snake A runb 15 87,842 (50,974– 25,950) 12,667 – +8.5 – Snake B runb 11 17,305 (9,736–33,195) 1,890 – –0.6 – Asotin Creekc Unknown 87 exp. redds (0–543) – 200 +4.0 –19.7 

Upper Grande Ronded 77 1.54 rpmf (0.3–4.7) – – –2.9 – 

Joseph Creek 100g 1,542 (1,077–2,385) 1,542 – +5.0 – 

Imnahad 80 3.7 rpmf (2.0–6.8) – – –3.7 – 

Camp Creek 100g 155 (55–307) 155 80 +2.0 +1.7 

a 5-year geometric mean calculated using years 1999–2001. b 5-year geometric mean calculated using years 1997–2001. c 5-year geometric mean calculated using years 1998–2001. d 5-year geometric mean calculated using years 1996–2000. e Estimate from previous status review. f rpm = redds per mile. g Assumed 100%; no hatchery releases into basin.

178
15. SNAKE RIVER BASIN STEELHEAD ESU 

0

50000

100000

150000

200000

250000

1980 1985 1990 1995 2000 2005

Year

Abundance

Total Natural origin

Figure 126. Lower Granite Dam counts of Snake River A-run steelhead, 1985–2001. Source: Yuen 

(2002). 

0

10000

20000

30000

40000

50000

60000

1980 1985 1990 1995 2000 2005

Year

Abundance

Total Natural origin

Figure 127. Lower Granite Dam counts of Snake River B-run steelhead, 1985–2001. Source: Yuen 

(2002). 

179
STEELHEAD

0

2

4

6

8

10

12

14

16

18

1970 1975 1980 1985 1990 1995 2000 2005

Year

Redds per mile

Total Natural-origin

Figure 128. Spawner abundance counts (redds per mile) for Imnaha River steelhead, 1974–2000. 

0

500

1000

1500

2000

2500

3000

1970 1975 1980 1985 1990 1995 2000 200

Year

Abundance

5

Total Natural origin

Figure 129. Spawner escapement for Joseph Creek steelhead: Grande Ronde, 1974–2002. Source: 

Expanded from redd counts from Oregon Department of Fish and Wildlife (see Appendix A, 

Table A-2). 

180
15. SNAKE RIVER BASIN STEELHEAD ESU 

Overall, long-term trends remained negative for four of the nine available series 

(including aggregate measures and specific production area estimates; Figure 132). Short-term 

trends improved relative to the period analyzed for the previous status review. The median 

short-term trend was +2.0% for the 1990–2001 period. Five out of the nine data sets showed a 

positive trend (Figure 133). 

IDFG has provided updated analyses of parr density survey results through 1999. IDFG 

concluded that generational parr density trends, which are analogous to spawner-to-spawner 

survivorship, indicate that Idaho spring/summer-run Chinook and steelhead, with and without 

hatchery influence, failed to meet replacement for most generations competed since 1985 (Kiefer 

2002). These data do not reflect the influence of increased returns in 2001 and 2002. 

Population growth rate (λ) estimates for Snake River steelhead production areas (Table 

30, Figures 131, 132) demonstrate a similar pattern when compared to the simple trend analysis 

described above. The median long-term λ estimate across the nine series was 0.998, assuming 

that natural returns are produced only from natural-origin spawners, and 0.733 if both hatchery 

and wild potential spawners are assumed to have contributed to production at the same rate. 

Short-term λ estimates are higher: 1.013 assuming a hatchery effectiveness of 0, and 0.753 

assuming hatchery and wild fish contribute to natural production in proportion to their numbers. 

These values are consistent with another recent analysis of population growth rates (McClure 

et al. 2003), which estimated λ at the ESU level as 0.96 if hatchery fish do not reproduce, and 

0.73 if they reproduce at a rate equal to that of wild fish. This analysis spanned the time period 

from 1980 to 2000, making it clear that the most recent returns have had an influence on λ 

0

2

4

6

8

10

12

14

1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Redds per mile

Total Natural-origin

Figure 130. Spawner escapement for the upper mainstem Grande Ronde River, 1967–2000. Source: 

Spawning ground survey data from ODFW (see Appendix A, Table A-2). 

181
STEELHEAD

estimates, particularly in the short term. (Note that population growth rate calculations in the 

Biological Opinion on the Federal Columbia River Power System [NMFS 2000] used 

assumptions of hatchery fish effectiveness bracketed by those in McClure et al. [2003].) 

The standardized abundance trend and population growth rate estimates provided in this 

report do not explicitly differentiate potential density-dependent effects from density-independent 

survival effects. Abundance levels for many production areas considered in the analyses varied 

over a wide range. In several cases, it is likely that abundance, at least in some years, could be 

high enough to affect survival through density-dependent mechanisms. To provide perspective 

on the potential for density-dependent influences, recent geometric mean spawner abundance 

estimates are contrasted with interim delisting levels provided by NOAA Fisheries’ regional 

office (http://www.nwr.noaa.gov/occd/InterimTargets.html). Interim delisting levels for Snake 

River spring/summer-run Chinook production units were derived from recommendations of the 

Bevan Recovery Team (Bevan et al. 1994). Interim delisting levels for upper Columbia River 

spring-run Chinook and steelhead were from Ford et al. (2001). The method described in Ford 

et al. (2001) was used to develop interim delisting levels for mid-Columbia and Snake river 

steelhead production areas. The approach uses estimates of habitat area and, where available, 

estimates of spawning escapements during historical periods of high, sustained returns. 

Resident O. mykiss Considerations 

The available information on resident O. mykiss populations within the ESU is 

summarized in Table 31 and Appendix B, Table B-1, including a broad overview of the 

distribution of case 1, 2, and 3 resident populations within the ESU. See the subsection, 

0

200

400

600

800

1000

1200

1400

1986 1988 1990 1992 1994 1996 1998 2000 2002

Year

Abundance

Total Natural origin

Figure 131. Estimated spawner escapement for Tucannon River steelhead, 1987–2001. Source: 

Washington Department of Fish and Wildlife (see Appendix A, Table A-2). 

182
Table 30. Snake River Basin steelhead ESU population growth-rate analysis. Summary of available trend data sets, results 

population growth rate (

λ), geometric mean, and probability 

λ less than 1.0. 

Percent Wild 

Population 

Series 

length Methoda

1987–

1996 

1997–

2001 

1997–

2001 

geometric 

mean HFb

Longterm λc Probability λ < 1 

Lower Granite Dam—

aggregate 

1990–

2001 

dc 0.18 0.14 14,768 0 

1 

0.994 0.703 

0.551 1.000 

Lower Granite Dam— 

A run 

1985–

2001 

dc 0.18 0.15 12,666 0 

1 

0.998 0.674 

0.512 1.000 

Lower Granite Dam— 

B run 

1985–

2001 

dc 0.18 0.11 1,890 0 

1 

0.927 0.655 

0.915 1.000 

Tucannon River 1987–

2001 

dc 0.39 0.26 95 0 

1 

0.886 0.733 

0.998 0.998 

Grande Ronde River—

upper 

1967–

2000 

rpm 0.83 0.77 NA 0 

1 

0.967 0.951 

0.668 0.736 

Grande Ronde River—

Joseph Creek 

1974–

2002 

tlc 1.00 1.00 1,542 na 1.069 0.130 

Imnaha River 1974–

2000 

rpm 0.80 0.80 na 0 

1 

1.042 1.026 

0.242 0.534 

Imnaha River—

Camp Creek 

1974–

2002 

tlc 1.00 1.00 154 na 1.077 0.099 

Imnaha River—

Little Sheep Creek 

1985–

2002 

tlc 0.30 0.14 42 0 

1 

1.045 0.718 

0.323 0.998 

a Methods: dc = dam counts; rc = redd counts; rpm = redds per mile index; tlc = estimated total live fish on spawning grounds. b Population growth rates calculated for two hatchery effectiveness (HF) assumptions; HF = 0.0 hatchery fish available to spawn do not 

production, HF = 1.0 hatchery returns available to spawn contribute to broodyear natural production at the same rate as natural-origin 

c Long term = the length of the available data series. d Short term = 1990–2001 or most recent year. 

183 
0.5

0.60.70.80.91.01.11.21.31.4

Snake River (LGR) H0

Snake River (LGR) H1

Snake River (A run) H0

Snake River (A run) H1

Snake River (B run) H0

Snake River (B run) H1

Tucannon River H0

Tucannon River H1

Grande Ronde

(Upper main stem)

Grande Ronde

(Joseph Creek)

Imnaha River H0

Imnaha River H1

Camp Creek

Annual rate of change

Figure 132. Long-term median population growth-rate estimates and 95% confidence limits for the Snake River Basin stee

estimates are based on calculations where hatchery-origin spawners have reproductive success equal to 0 (H0) or e

origin spawners (H1) (some hatchery confidence limits estimated by extrapolation). 

184 
0.5

0.60.70.80.91.01.11.21.31.4

Snake River (LGR) H0

Snake River (LGR) H1 SSSS

Figure 133. Short-term median population growth-rate estimates and 95% confidence limits for the Snake River Basin stee

estimates are based on calculations where hatchery-origin spawners have reproductive success equal to 0 (H0) or e

origin spawners (H1). 

nake River (A run) H0

nake River (A run) H1

nake River (B run) H0

nake River (B run) H1

Tucannon River H0

Tucannon River H1

Grande Ronde

(Upper main stem)

Grande Ronde

(Joseph Creek)

Imnaha River H0

Imnaha River H1

Camp Creek

Annual rate of change

185 
Table 31. Distribution of Snake River Basin steelhead ESU trout populations by category. 

Category 1 populationsa

(sympatric) 

Category 2 populations 

(major natural barriersb

) 

Category 3 populations 

(major artificial barriersb

) 

Potentially all areas that are or were 

used by steelhead. 

Tucannon River 

Asotin River 

Grande Ronde River 

Imnaha River 

Salmon found in about 43% of 

streams 

Clearwater River 

Selway River 

Other potential areas 

Palouse River 

Malad River 

Several Hells Canyon 

tributaries 

Upper Malheur basin “recent” 

disconnect from lower Malheur 

Lake basin 

Trout distributions currently 

more restricted than 

historically. 

North Fork Clearwater 

(Dworshak Dam) 

Mainstem Snake (Hells 

 Canyon Dam) 

Powder 

Burnt 

Malheur 

Owyhee 

Weiser 

Payette 

Boise 

Burneau 

Salmon Falls Creek 

Several small tributaries 

a

 The generalized listing of basins and subbasins does not imply that these constitute single trout populations or 

that trout distribution is continuous throughout the areas listed. Detailed trout distribution is usually unknown 

and actual demographically independent trout populations have not been described. All current trout 

distributions are decreased from historical distributions. In particular many mainstem and lower basin 

tributaries are no longer used but probably were historically. Many current trout populations are only in upper 

basins and are highly fragmented. 

b

 Only major barriers are noted; numerous small barriers, both natural and artificial, also exist. Many other 

natural barriers are present but have O. clarki, rather than O. mykiss, above them. O. mykiss distribution in 

areas of sympatry with steelhead may be restricted in some areas if native O. clarki are also in the basin. 

Resident Fish, in Section 14 for an explanation of the three cases and their relevance to ESU 

determinations; it discusses how resident fish are considered in risk analyses. Kostow (2003) 

reviewed information on the abundance and distribution of resident trout for this ESU. IDFG 

presence-absence survey results indicate that O. mykiss were found in 48% of the 84 streams 

sampled throughout the Salmon River basin. Westslope cutthroat trout were found in 43% of 

the locations sampled. When the species co-occurred in a tributary system, the cutthroat trout 

tended to be found in smaller headwater tributaries, while the O. mykiss were in larger 

tributaries lower in the system. Steelhead occupied lower mainstem and associated 

tributaries. IDFG suggested that some resident rainbow in the Salmon and Clearwater 

drainages may be the result of hatchery rainbow introductions. 

The relative abundance of resident O. mykiss in the Imnaha and Grande Ronde river 

basins has not been clearly defined. O. mykiss production has been documented in both 

basins. Kostow (2003) reports that although no formal surveys of resident trout abundance 

have been conducted in the Imnaha River basin, the results of genetics sampling in the basin 

186 
15.SNAKE RIVER BASIN STEELHEAD ESU

support the presence of a resident form. Resident O. mykiss abundance in the Tucannon River 

is believed to be relatively low based on observations during steelhead redd count surveys 

(Kostow 2003). 

Resident O. mykiss populations are present above the Hells Canyon Dam complex, but 

their relationship to existing steelhead populations below the dams has not been determined 

(Kostow 2003). There have been relatively few specific studies of potential relationships 

between sympatric resident and anadromous O. mykiss in the Snake River basin. 

Genetic analysis of case 3 resident O. mykiss above Dworshak Dam shows that the 

sampled population is genetically more similar to Dworshak steelhead than are other Snake 

River O. mykiss populations (Waples 1998, Kostow 2003). This finding suggests that the 

sampled population may be derived primarily from residualized steelhead or native resident 

fish from the North Fork Clearwater River. However, the genetic data cannot rule out some 

introgression from nonnative rainbow trout. 

Kostow (2003) reported that field biologists noted spatial and temporal overlaps in 

spawning between resident and anadromous O. mykiss in the Grande Ronde, Imnaha, 

Tucannon, and upper Snake river basins. ODFW is conducting experimental cross-breeding 

studies using resident and anadromous O. mykiss from the Grande Ronde basin. Preliminary 

results indicate that all potential crosses produce outmigrating smolts. Steelhead × steelhead 

crosses had the highest smolt production rate, and resident trout × resident trout crosses had 

the lowest. Adult female steelhead × resident male trout crosses, the combination most likely 

to occur in nature, had the second highest smolt production rate. Adult returns from the study 

were forthcoming at the time of writing. 

Genetic analyses (e.g., Leary 2001) of case 3 resident populations in tributaries above 

the Hells Canyon Dam concluded that some populations are native redband trout, but others 

are hybridized with hatchery rainbow trout. A number of genetic studies of Snake River O. 

mykiss that are under way should provide more specific information about resident 

populations in the future. 

New Hatchery Information 

Artificial Production History 

Almost all artificial production of steelhead in the Snake River Basin ESU has been 

associated with two major mitigation initiatives—the Lower Snake River Compensation 

Program (LSRCP) and the mitigation program for Dworshak Dam on the North Fork 

Clearwater River. LSRCP is administered by the USFWS and was established as 

compensation for losses incurred as a result of the construction and operation of the four 

lower Snake River hydroelectric dams. Production under this initiative generally began in the 

mid-1980s. The Dworshak mitigation program provides for artificial production as 

compensation for the loss of access to the North Fork Clearwater, a major historical 

production area. Dworshak Hatchery, completed in 1969, is the focus for that production. 

187
STEELHEAD

Hatchery releases of steelhead within the Snake River basin are summarized by time 

period and production area in Table 32. The following subsections summarize historical and 

current artificial production steelhead programs by major geographic area within the ESU. 

Table 32. Hatchery releases of steelhead in the Snake River basin steelhead ESU, organized by major 

steelhead production areas and broodstock of the release. 

Average releases per year*

Basin Stock 1985–1989 1990–1994 1995–2001 

Mainstem Snake River Dworshak B 2,400 1,760 – 

 Lyons Ferry 141,383 72,306 73,616 

 Oxbow A 912,769 651,723 440,999 

 Salmon River A 68,800 – 93,325 

 Wallowa 205,133 138,915 – 

 Wells 112,559 – – 

 Mixed 20,352 – – 

 Imnaha River – 6,722 – 

 Snake River A – – 95,018 

 Pahsimeroi A – 8,695 – 

 Mainstem total 1,463,396 880,121 702,958 

Tucannon River Lyons Ferry 32,300 14,116 151,723 

 Tucannon River 157,469 62,860 8,574 

 Wallowa 16,197 – – 

 Wells 40,229 – – 

 Pahsimeroi A – 23,852 – 

 Mixed – 26,008 – 

 Tucannon total 246,195 126,836 160,297 

Asotin River Lyons Ferry 16,895 6,092 16,328 

 Oxbow A – 27,200 – 

 Pahsimeroi A – 27,569 – 

 Wallowa 5,800 – – 

 Wells 8,930 – – 

 Asotin Total 31,625 60,861 16,328 

Mainstem Clearwater River Dworshak B 1,618,440 1,893,944 1,755,111 

 Clearwater B – – 113,581 

North Fork Clearwater River Dworshak B – – 391,210 

South Fork Clearwater River Clearwater B – – 85,398 

Dworshak B 612,152 869,839 739,543 

 Selway River – 14,313 19,483 

 Clearwater total 2,230,592 2,778,096 3,104,326 

Mainstem Grande Ronde River Wallowa 782,060 616,379 975,089 

Wallowa River Wallowa 529,852 985,339 524,416 

 Grande Ronde total 1,311,912 1,601,718 1,499,505 

Lower and mainstem Salmon River Salmon River A 325,000 432,867 161,537 

Salmon River B 9,900 – 24,940 

Dworshak B – 112,291 109,015 

 Oxbow A – 100,972 63,879 

 Pahsimeroi A – 235,306 68,695 

188
15.SNAKE RIVER BASIN STEELHEAD ESU

Table 32 continued. Hatchery releases of steelhead in the Snake River basin steelhead ESU, organized 

by major steelhead production areas and broodstock of the release. 

Average releases per year*

Basin Stock 1985–1989 1990–1994 1995–2001 

Little Salmon River Hagerman A 61,621 – – 

 Oxbow A 120,261 200,380 341,639 

 Salmon River A 399,135 232,716 271,400 

 Dworshak B – 367,068 222,438 

 Pahsimeroi A – 65,632 39,933 

 Salmon River B – – 48,471 

Panther Creek Pahsimeroi A 49,264 – – 

Salmon River A 141,100 – – 

North Fork Salmon River Salmon River A 92,300 71,600 30,070 

Oxbow A – 26,995 – 

Pahsimeroi A – 38,100 43,500 

Lemhi River Dworshak B 125,000 86,857 – 

Pahsimeroi A – – 132,741 

Salmon River A – – 129,287 

Pahsimeroi River Pahsimeroi A 845,968 693,118 718,435 

Salmon River A – – 114,506 

East Fork Salmon River East Fork Salmon B 475,023 197,670 34,283 

Dworshak B 87,315 773,329 240,523 

Hagerman B 54,042 – – 

Salmon River B – – 71,494 

Upper Salmon River Hagerman A 157,237 – – 

Pahsimeroi A – 447,944 368,748 

Salmon River A 889,353 669,844 590,289 

Dworshak B – – 130,186 

Salmon River B – – 18,387 

Sawtooth A – – 32,348 

Salmon total 3,832,518 4,752,697 4,006,745 

Imnaha River Imnaha River 188,275 325,833 169,758 

Little Sheep Creek – – 131,776 

Imnaha Total 188,275 325,833 301,534 

ESU total All stocks 10,097,233 10,526,167 10,033,360 * Averages calculated by time period to facilitate comparison of release levels since the last status review (Busby 

et al. 1996) with previous levels. 

The broodstock for Tucannon releases was primarily the Lyons Ferry Hatchery stock, 

which was originally derived from Wells Hatchery and Wallowa Hatchery stocks. ODFW 

originally derived the Wallowa Hatchery stock by trapping returning adults in the lower 

Snake River. Pahsimeroi Hatchery stock was used in the program in one year when full 

production was lost at Lyons Ferry Hatchery due to disease outbreaks, primarily infectious 

hematopoietic necrosis virus (IHNV) (Gephart and Nordheim 2001). 

Return rates to the Tucannon River from the hatchery program have been relatively 

low. Beginning in 1998, the release location for hatchery steelhead was moved downriver in 

189
STEELHEAD

response to studies indicating improved survivals from lower river releases and to minimize 

the opportunity for interbreeding between hatchery and natural returns (which included listed 

spring-run Chinook) to the basin. Beginning with the 1999/2000-cycle year, the Tucannon 

River hatchery steelhead program began evaluating the feasibility of using local broodstock 

for the program. A full switchover to an endemic broodstock may occur in the future, 

depending on the success of the pilot program. Problems associated with trapping and rearing 

of the new broodstock, as well as genetic questions, still need to be addressed.16

Hatchery Summaries 

Grande Ronde and Imnaha rivers 

There are LSRCP steelhead hatchery mitigation releases in the Grande Ronde and 

Imnaha river systems. The LSRCP compensation objective for Grande Ronde steelhead 

returns is 9,200. Trapping facilities for adult broodstock are located at Big Canyon Creek 

acclimation site. The original program used outside broodstock (including Skamania 

Hatchery stock) from 1979 to 1982 before switching to the Wallowa broodstock. Smolts are 

acclimated and released at two sites—one within the Wallowa drainage, the other at Big 

Canyon Creek. Oregon manages the Minam River, Joseph Creek, and Wenaha River 

drainages for natural production. Other sections of the Grande Ronde River have been 

outplanted to supplement natural production (Nowak 2001).

LSRCP program releases into the Imnaha River come from a satellite facility on Little 

Sheep Creek after primary rearing at Wallowa Hatchery. Additional releases are targeted in 

Horse Creek and the upper Imnaha River basin (Bryson 2001). 

Clearwater River basin 

Steelhead hatchery releases into the Clearwater River basin are managed under two 

programs—LSRCP and Dworshak Dam mitigation. The Lower Snake Compensation Plan 

program in the Clearwater River drainage uses the Clearwater hatchery as a central rearing 

facility and has an overall production objective of 14,000 adult steelhead returns to the Snake 

River. Program release sites include acclimation ponds on the Powell River (Lochsa River 

drainage), the Red River, and Crooked River sites in the South Fork Clearwater River. The 

Dworshak mitigation program has an adult return objective of 20,000 adult steelhead as 

compensation for losses due to Dworshak Dam, an anadromous block that cuts off the North 

Fork Clearwater River. Genetics studies have indicated that the hatchery stock used in the 

Dworshak program may be representative of the original North Fork run (Cichosz et al. 

2001).

Salmon River basin 

Steelhead hatchery releases into the Salmon River drainage are under the auspices of 

two major steelhead hatchery programs—LSRCP and IDFG programs funded by Idaho Power 

Company. In addition, there are state and tribal experimental supplementation programs in 

 

16 B. Leland, Washington Department of Fish and Wildlife, Olympia, WA. Pers. commun., 31 March 2003. 

190
15.SNAKE RIVER BASIN STEELHEAD ESU

the drainage. The LSRCP program goal for the Salmon River basin is to produce an annual 

return of 25,000 adult steelhead above Lower Granite Dam. Juvenile steelhead produced at 

Magic Valley Hatchery and Hagerman National Fish Hatchery are released into the Salmon 

River drainage. The Idaho Power Company–funded program for steelhead has an objective of 

releasing 400,000 pounds of steelhead smolts (Servheen 2001).

The Middle Fork Salmon River drainages have had minimal or no hatchery releases. 

The upper Salmon River drainages—the Pahsimeroi, Lemhi, Little Salmon, and Lower 

Salmon river areas—have received releases in recent years. 

Categorizations of Snake River basin hatchery stocks (SSHAG 2003) are summarized 

in Appendix B, Table B-3. 

191
16. Upper Columbia River Steelhead ESU 

The life history patterns of upper Columbia River steelhead are complex. Adults 

return to the Columbia River in the late summer and early fall; most migrate relatively quickly 

up the main stem to their natal tributaries. A portion of the returning run overwinters in the 

mainstem reservoirs, passing over the upper mid-Columbia dams in April and May of the 

following year. Spawning occurs in the late spring of the calendar year following entry into 

the river. Juvenile steelhead spend 1 to 7 years rearing in freshwater before migrating to the 

ocean. Smolt outmigrations are predominantly age-2 and age-3 juveniles. Most adult 

steelhead return after 1 or 2 years at sea, starting the cycle again. 

Estimates of the annual returns of upper Columbia River steelhead populations are 

based on dam counts. Cycle counts are used to accommodate the prevalent return pattern in 

upriver summer-run steelhead (runs enter the Columbia River in late summer and fall, some 

fish overwinter in mainstem reservoirs—migrating past the upper dams prior to spawning the 

following spring). Counts over Wells Dam are assumed to be returns originating from natural 

production and hatchery outplants into the Methow and Okanogan river systems. The total 

returns to Wells Dam are calculated by adding annual broodstock removals at Wells to the 

dam counts. The annual estimated return levels above Wells Dam are broken down into 

hatchery and wild components by applying the ratios observed in the Wells sampling program 

for run years since 1982. 

Harvest rates on upper river steelhead have been cut back substantially from historical 

levels. Legislation in the early 1970s eliminated direct commercial harvest of steelhead in 

non-Indian fisheries. Incidental impacts in fisheries directed at other species continued in the 

lower river, but at substantially reduced levels. In the 1970s and early 1980s, recreational 

fishery impacts in the upper Columbia River escalated to very high levels in response to 

increasing returns augmented by substantial increases in hatchery production. In 1985, 

steelhead recreational fisheries in this region (and in other Washington tributaries) were 

changed to mandate release of wild fish. Treaty harvest of summer-run steelhead (including 

returns to the upper Columbia River) occurs mainly in mainstem fisheries directed at upriver 

bright fall-run Chinook salmon. 

Hatchery returns predominate the estimated escapement in the Wenatchee, Methow, 

and Okanogan river drainages. The effectiveness of hatchery spawners relative to their 

natural counterparts is a major uncertainty for both populations. Hatchery effectiveness can 

be influenced by at least three sets of factors: relative distribution of spawning adults, relative 

timing of spawning adults, and relative effectiveness of progeny. No direct information is 

available for the upper Columbia River stocks. Outplanting strategies have varied over the 

period the return/spawner data were collected (1976–1994 broodyears). Although the return 

timing into the Columbia River is similar for both wild and hatchery steelhead returning to the 

upper Columbia, the spawning timing in the hatchery is accelerated. The long-term effects of 

192 
16. UPPER COLUMBIA RIVER STEELHEAD ESU

such acceleration on the spawning timing of returning hatchery-produced adults in nature is 

not known. We have no direct information on relative fitness of upper Columbia River 

steelhead progeny with at least one parent of hatchery origin.

Summary of Previous BRT Conclusions 

The 1998 steelhead status review identified a number of concerns for the Upper 

Columbia River steelhead ESU: “While the total abundance of populations within this ESU 

has been relatively stable or increasing, it appears to be occurring only because of major 

hatchery supplementation programs. Estimates of the proportion of hatchery fish in spawning 

escapement are 65% (Wenatchee River) and 81% (Methow and Okanogan rivers). The major 

concern for this ESU is the clear failure of natural stocks to replace themselves. The BRT 

members are also strongly concerned about the problems of “genetic homogenization due to 

hatchery supplementation...apparent high harvest rates on steelhead smolts in rainbow trout 

fisheries and the degradation of freshwater habitats within the region, especially the effects of 

grazing, irrigation diversions and hydroelectric dams.” The BRT also identified two major 

areas of uncertainty: relationship between anadromous and resident forms, and the genetic 

heritage of naturally spawning fish within this ESU. 

Listing status: Endangered. 

New Data and Updated Analyses 

Population Definitions and Criteria 

We developed an initial set of population definitions for the Upper Columbia River 

steelhead ESU, along with basic criteria for evaluating the status of each population, using the 

VSP guidelines described in McElhany et al. (2000). The definitions and criteria are 

described in Ford et al. (2001) and have been used in the development and review of MidColumbia PUD plans and the FCRPS Biological Opinion. The interim population definitions 

and criteria have been submitted as recommendations to the Interior Columbia Basin 

Technical Recovery Team. Briefly, the joint technical team recommended that the 

Wenatchee, Entiat, and Methow rivers be considered as separate populations within the Upper 

Columbia River steelhead ESU. The Okanogan River may have supported a fourth 

population; the committee deferred a decision on the Okanogan to the Technical Recovery 

Team. Ford et al. (2001) developed and describes abundance, productivity, and spatial 

structure criteria for each population in the ESU. 

Current Abundance 

Returns of both hatchery- and naturally produced steelhead to the upper Columbia 

River have increased in recent years. Priest Rapids Dam is below Upper Columbia River 

steelhead ESU production areas. The average 1997–2001 return counted through the Priest 

Rapids fish ladder was approximately 12,900 steelhead. The average for the previous 5 years 

(1992–1996) was 7,800 fish.

193
STEELHEAD

Total returns to the upper Columbia River continue to be predominantly hatcheryorigin fish. The natural-origin percentage of the run over Priest Rapids increased to over 25% 

in the 1980s, and then dropped to less than 10% by the mid-1990s. The median percent of 

natural origin for 1997–2001 was 17%. Abundance estimates of returning, naturally produced 

upper Columbia River steelhead are based on extrapolations from mainstem dam counts and 

associated sampling information (e.g., hatchery/wild fraction, age composition). The natural 

component of the annual steelhead run over Priest Rapids increased from an average of 1,040 

(1992–1996) to 2,200 (1997–2001). 

The estimate of the combined natural steelhead return to the Wenatchee and Entiat 

rivers increased to a geometric mean of approximately 900 for the 1996–2001 period. The 

percentage of returning upper Columbia River steelhead dropped from 35% to 29% for the 

recent 5-year period. In terms of natural production, recent production levels remain well 

below the interim recovery levels developed for these populations (Table 33, Figure 134). 

The Methow River steelhead population is the primary natural production area above 

Wells Dam. The 1997–2001 geometric mean of natural returns over Wells Dam was 358, 

lower than the geometric mean return prior to the 1998 status review (Table 33, Figure 135). 

The most recent return reported in the data series, 1,380 naturally produced steelhead in 2001, 

was the highest single annual return in the 25-year data series. Hatchery returns continue to 

dominate the run over Wells Dam. The average percent of wild origin dropped to 9% for 

1996–2001, compared to 19% for the period prior to the previous status review. 

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total Natural origin

Figure 134. Estimated annual spawner escapements of Wenatchee and Entiat river steelhead, 

1976–2001. Sources: Cooney (2001); 1999–2001 data from WDFW (see Appendix A, Table A-2). 

194
16. UPPER COLUMBIA RIVER STEELHEAD ESU

Table 33. Summary of current abundance and trend information relative to previous BRT status 

review for Upper Columbia River steelhead. 

Recent 5-year geometric mean 

Total Natural 

Short-term trend 

(%/year) 

Population 

5-year 

mean % 

natural 

origin Mean (range) Current Previous Current Previous 

Interim

targeta

Current 

vs. target

Wenatchee/ 

Entiat 

29 

(35b

) 

3,279 

(1,899–8,036) 894 800 +6.5 +2.6 3,000 30% 

Methow/ 

Okanogan 

9 

(19b) 

3,714 

(1,879–12,801) 358 450 +13.8 –12.0 2,500 14% 

a

 Interim targets are from Ford et al. (2001). 

b

 Estimates are from Busby et al. (1996).

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

1970 1975 1980 1985 1990 1995 2000 2005

Year

Abun

dance

Total Natural origin

Figure 135. Estimated annual spawner escapements for Methow River steelhead, 1976–2001. 

Sources: Cooney (2001); 1999–2001 data from Washington Department of Fish and Wildlife 

(see Appendix A, Table A-2). 

The analyses described above relied on the 1976–2001 abundance data set. The 

starting date for that series is set by the advent of counting at Wells Dam, which allowed for 

separate estimates of run strength to the Methow/Okanogan rivers and the Wenatchee/Entiat 

rivers. Prior to 1976, scientists had no direct ability to separate out counts returning to 

different subbasins above Rock Island Dam. The median run (at that time almost all of 

natural origin) from 1933 to 1954 was approximately 2,300. 

195
STEELHEAD

Current Productivity 

Natural returns have increased in recent years for both stock groupings (Table 34). 

Population growth rates (expressed as λ, calculated using the running sum method) are 

substantially influenced by assumptions regarding the relative effectiveness of hatchery 

spawners. The same key factor must be considered in analyzing return-per-spawner data sets. 

The relative contribution of returning steelhead of hatchery origin to natural spawning is not 

clearly understood. There may be timing and spatial differences in the distribution of 

hatchery- and wild-origin spawners that affect production of juveniles. Eggs and subsequent 

juveniles from natural spawning involving hatchery-origin fish may survive at a different rate 

relative to spawning of natural-origin adults. 

Both short-term (1990–2001) and long-term (1976–2001) estimates of λ are positive 

under the assumption that hatchery fish have not contributed to natural production in recent 

years. Assuming that hatchery fish contributed to natural production at the same level as wild 

fish, λ estimates are substantially lower—under this scenario natural production is 

consistently and substantially below the total number (hatchery plus natural origin) of 

spawners in any given year. This result is consistent with those of McClure et al. (2003) and 

results in the 2000 FCRPS Biological Opinion (NMFS 2000), in which λ was estimated from 

the ESU-level time series for the time period 1980–2000. Although the total spawners have 

an apparent population growth rate of 1.00 (with relatively high variability), this growth rate 

is lowered to 0.69 if hatchery fish contributed to subsequent generations at the same rate as 

wild fish. Clearly, determining the actual contribution of hatchery fish is an important 

element in determining the true status of this ESU. 

Assumptions regarding the relative effectiveness of hatchery-origin spawners also 

influence return-per-spawner patterns for the two steelhead production areas (Figures 136 and 

137). Under the assumption that hatchery and wild spawners are both contributing to the 

subsequent generation of natural returns, return-per-spawner levels have been consistently 

below 1.0 since 1976. Under this scenario, natural production would be expected to decline 

rapidly in the absence of hatchery spawners. Under the assumption that hatchery fish 

returning to the upper Columbia River do not contribute to natural production, return-perspawner levels were above 1 until the late 1980s. Return-per-spawner estimates subsequently 

dropped below replacement (1.0) and remained low until the most recent broodyear with 

measured returns—1996. The actual contribution of hatchery returns to natural spawning 

remains a key uncertainty for upper Columbia River steelhead. This information need is in 

addition to any considerations for long-term genetic impacts of high hatchery contributions to 

natural spawning 

Resident O. mykiss Considerations 

This section summarizes available information on resident O. mykiss populations 

within the ESU. Table 35 and Appendix B, Table B-1 provide an overview of the distribution 

of case 1, 2, and 3 resident populations within the ESU. See the subsection, Resident Fish, in 

Section B.1 Background and History of Listings, for an explanation of the three cases and 

their relevance to ESU determinations. The subsection, Resident Fish, in Section B.1, 

Steelhead, discusses how resident fish are considered in risk analyses. 

196
Table 34. Upper Columbia River steelhead population growth-rate analysis. Summary of available trend data sets, results 

population growth rates (

λ), geometric mean, probability 

λ less than 1.0. 

Percent Wild 

Population Series length Methoda 1987–1996 1997–2001

1997–2001 

geometric 

mean HFb

Long 

termc λ

Probability 

λ < 1 

Wenatchee/Entiat 1976–2001 dc 0.33 0.29 894 0 

1 

1.067 0.733 

0.112 1.000 

Above Wells Dam 1976–2001 dc 0.17 0.085 358 0 

1 

1.086 0.579 

0.088 1.000 

Methow River 1976–2001 dc 0.21 0.11 358 0 

1 

1.086 0.589 

0.088 1.000 

a Methods: dc = dam counts. b Population growth rates calculated for two hatchery effectiveness (HF) assumptions: HF = 0.0 hatchery fish available to spawn do not 

production; HF = 1.0 hatchery returns available to spawn contribute to broodyear natural production at the same rate as natural-origin 

c Long term = the length of the available data series. d Short term = 1990–2001 or most recent year. 

197 
0.1

1

10

1970 1975 1980 1985 1990 1995 2000

Broodyear

Returns per spawner

Total Natural origin

Figure 136. Returns per spawner versus broodyear spawning escapement of Wenatchee/Entiat river 

steelhead, 1976–2001.

0.01

0.1

1

10

1970 1975 1980 1985 1990 1995 2000

Broodyear

Returns per spawner

Total Natural origin

Figure 137. Returns per spawner versus broodyear spawning escapement for Methow River steelhead, 

1976–2001. 

198 
16. UPPER COLUMBIA RIVER STEELHEAD ESU

Resident O. mykiss are relatively abundant in upper Columbia tributaries currently 

accessible to steelhead as well as in upriver tributaries blocked off to anadromous access by 

Chief Joseph and Grand Coulee dams (Kostow 2003). USFWS biologists surveyed the 

abundance of trout and steelhead juveniles in the Wenatchee, Entiat, and Methow river 

drainages in the mid-1980s (Mullan et al. 1992). Adult trout (defined as trout >20 cm) were 

found in surveys in all basins. Juvenile O. mykiss were reported from 94% of the surveys 

conducted in areas believed to be used by steelhead and resident trout (Kostow 2003). The 

results also supported the hypothesis that resident O. mykiss are more abundant in tributary or 

mainstem areas above the general areas used by steelhead for rearing. 

The original status review did not formally evaluate the current ESU status of resident 

populations above Chief Joseph Dam, nor did it formally consider whether O. mykiss in upper 

Columbia River tributaries historically were in the same ESU as populations in the 

Wenatchee, Entiat, Methow, and Okanogan rivers. Kostow (2003) reports that biologists who 

are familiar with the areas above Chief Joseph Dam believe that O. mykiss are present in 

significant numbers. Several of the tributaries above Chief Joseph Dam have been blocked 

off by dams, and introductions of exotic gamefish and trout species have been widespread. 

We are not aware of specific information relevant to the ESU status of case 3 resident 

populations above dams in the Okanogan or Spokane rivers, or above Chief Joseph and Grand 

Coulee dams on the mainstem Columbia River. O. mykiss, believed to be native populations, 

are present in a number of tributaries draining into Lake Roosevelt (Kostow 2003). Mullan 

Table 35. Distributiona of O. mykiss by category relative to the Upper Columbia River steelhead ESU. 

Category 1 populations 

(sympatric)b

Category 2 populations 

(major natural barriers)c

Category 3 populations (major 

artificial barriers)c

Potentially all areas that are or 

were used by steelhead 

Wenatchee 

Lower Entiat 

Methow 

Okanogan 

Upper Entiat 

Upper Kootenay 

Okanogan: 

Enloe Fallsd

Methow: 

Chewuchd

Lost 

Trout distributions currently 

more restricted than historically 

Okanogan Basin: 

Conconully Dam 

Enloe Damd

Chief Joseph Dam 

Lower Spokane to Post Falls 

Sanpoil 

Several small tributaries 

Lower Pend Oreille to Z Canyon

Columbia headwaters in Canada 

a

 The generalized listing of basins and subbasins does not imply that these constitute single populations or that 

distribution is continuous throughout the areas listed. Detailed distribution is usually unknown and actual 

demographically independent populations are not described. All current distributions are decreased from 

historical distributions. In particular, many mainstem and lower basin tributaries are no longer used, but 

probably were historically. Many current populations are only in upper basins and are highly fragmented. 

b O. mykiss distribution in areas of sympatry with steelhead may be restricted in some areas if native O. clarki are 

also in the basin. 

c

 Only major barriers are noted; numerous small barriers, both natural and artificial, also exist. Many other 

natural barriers are present but have O. clarki trout, rather than O. mykiss, above them. 

d Expected presence of O. mykiss trout, but not confirmed by reliable sources. 

199
STEELHEAD

et al. (1992) hypothesized that the native trout populations above Chief Joseph Dam 

effectively preserved native steelhead lineages present before the construction of the 

mainstem impassable dams. Knudsen et al. (2002) concluded that native resident (case 2) 

populations persist in some Kootenai River tributaries, in spite of extensive stocking by 

nonnative rainbow trout. 

New Hatchery Information 

Hatchery production averaged approximately 300,000 smolts/year in the 1960s, 

425,000 in the 1970s, 790,000 in the 1980s, and more than 800,000 in the 1990s (including 

releases exceeding 1.0 million). Current mitigation and supplementation targets are to use 

locally obtained returning adults for programs. The objective for the Wenatchee is to release 

400,000 smolts per year using broodstock collected from run-of-the-river fish in the 

Wenatchee (main collection point is Dryden Dam). Broodstock collected at Wells Dam are 

used for outplanting in the Methow (380,000 target release) and the Okanogan (100,000 target 

release). The Entiat Basin has been designated as a natural production “reference” drainage—

no hatchery outplanting. Presently, no monitoring programs are in place to directly estimate 

natural production of steelhead in the Entiat. Categorizations of upper Columbia River 

steelhead hatchery stocks (SSHAG 2003) can be found in Appendix B, Table B-3. 

Table 36. Hatchery releases of steelhead in the Upper Columbia River ESU, organized by major 

steelhead production areas and broodstock. 

Average*

 releases per year 

Basin Stock 1985–1989 1990–1994 1995–2001 

Ringold 220,421 144,303 – 

Wells 27,757 26,204 202,269 

Skamania – 35,130 70,523 

Wenatchee River – – 500 

Mainstem Columbia River 

Mainstem total 177,270 146,883 273,292 

Wells 43,863 43,247 18,098 

Wenatchee River – – 12,465 

Entiat River 

Entiat total 43,863 43,247 30,564 

Methow River Wells 439,926 428,894 418,227 

Okanogan River Wells 133,198 123,972 119,996 

Leavenworth 62,376 95,631 23,960 

Ringold 113,225 – – 

Wells 121,272 351,735 176,643 

Wenatchee River 81,072 – 106,554 

Wenatchee River 

Wenatchee total 377,945 447,366 307,158 

ESU total All stocks 1,243,110 1,249,116 1,149,239 *

 Averages are calculated by time period to facilitate comparison of release levels since the last status review 

(Busby et al. 1996). 

200
17. Middle Columbia River Steelhead ESU 

The Middle Columbia River steelhead ESU includes steelhead populations in Oregon 

and Washington drainages upstream of the Hood and Wind river systems, up to and including 

the Yakima River. The Snake River is not included in this ESU. Major drainages in this ESU 

are the Deschutes, John Day, Umatilla, Walla Walla, Yakima, and Klickitat river systems. 

Almost all steelhead populations within this ESU are summer-run fish; the exceptions are 

winter-run components returning to the Klickitat River and Fifteenmile Creek watersheds. A 

balance between 1- and 2-year-old smolt outmigrants characterize most of the populations 

within this ESU. Adults return after 1 or 2 years at sea. 

Hatchery facilities are located in a number of drainages within the geographic area of 

this ESU, although there are also subbasins with little or no direct hatchery influence. The 

John Day River system, for example, has not been outplanted with hatchery steelhead. 

Similarly, hatchery production of steelhead in the Yakima River system was relatively limited 

historically and was phased out in the early 1990s. However, the Umatilla and Deschutes 

river systems each have ongoing hatchery production programs based on locally derived 

broodstocks. Moreover, straying from out-of-basin production programs into the Deschutes 

River has been identified as a chronic occurrence. The Walla Walla River (three locations in 

Washington sections) historically received production releases of Lyons Ferry Hatchery stock 

summer-run steelhead from the LSRCP. Mill Creek releases were halted after 1998 due to 

concerns associated with the then pending listing of mid-Columbia River steelhead under the 

ESA. A new endemic broodstock is under development for the Touchet River release site 

(beginning with the 1999/2000 return year). Production levels at the Touchet and Walla 

Walla river release sites have been reduced in recent years (WDFW).17

Blockages have prevented access to sizable steelhead production areas in the 

Deschutes and White Salmon rivers. In the Deschutes River, Pelton Dam blocks access to 

upstream habitat steelhead historically used. Conduit Dam, constructed in 1913, blocked 

access to all but 2 to 3 miles of habitat suitable for steelhead production in the Big White 

Salmon River (Rawding 2001b). Substantial populations of resident trout exist in both areas. 

Summary of Previous BRT Conclusions 

The previous reviews (NMFS 1998c, 1999b) identified several concerns, including 

relatively low spawning levels in streams for which information was available, a 

preponderance of negative trends (10 out of 14), and the widespread presence of hatchery fish 

throughout the ESU. The 1999 status review update (NMFS 1999b) specifically identified 

 

17WDFW comments submitted to NOAA on comanager draft of preliminary conclusions regarding the updated 

status of listed ESUs of West Coast salmon and steelhead, 29 March 2003. 

201 
STEELHEAD

“the serious declines in abundance in the John Day River Basin” as a point of concern, given 

that the John Day system had supported large populations of naturally spawning steelhead in 

the recent past. The previous review also expressed concerns about the low abundance of 

returns to the Yakima River system relative to historical levels “with the majority of 

production coming from a single stream (Satus Creek).” The review also identified the sharp 

decline in returns to the Deschutes River system as a concern. The status review update also 

identified increases of stray steelhead into the Deschutes River as a “major source of 

concern,” as initial results from radio-tagging studies indicated that a substantial proportion of 

steelhead entering the Deschutes River migrated out of the system prior to spawning. Finally, 

the status review update identified a set of habitat problems affecting basins within this ESU. 

High summer and low winter temperatures are characteristic of production or migration 

reaches associated with populations within this ESU, and water withdrawals had seriously 

reduced flow levels in several mid-Columbia River drainages, including sections of the 

Yakima, Walla Walla, Umatilla, and Deschutes rivers. Riparian vegetation and instream 

structure had been degraded in many areas. The team suggested that for stream segments 

inventoried within this ESU, riparian restoration was needed for between 37% and 84% of the 

river bank in various basins (NMFS 1999b). 

Listing status: Threatened. 

New Data and Updated Analyses 

Abundance 

With some exceptions, the recent 5-year average (geometric mean) abundance for 

natural steelhead within this ESU was higher than levels reported in the last status review 

(NMFS 1999b). Information on recent returns, compared to return levels reported in previous 

status reviews, is summarized in Table 37 and depicted in Figures 138–147. Returns to the 

Yakima River, the Deschutes River, and sections of the John Day River system were 

substantially higher compared to 1992–1997. Yakima River returns are still substantially 

below interim target levels and estimated historical return levels, with the majority of 

spawning occurring in one tributary, Satus Creek (Berg 2001). The recent 5-year geometric 

mean return of the natural-origin component of the Deschutes River run exceeded interim 

target levels. Recent 5-year geometric mean annual returns to the John Day Basin are 

generally below the corresponding mean returns reported in the previous status reviews. 

However, each major production area in the John Day system has shown upward trends since 

the 1999 return year. 

Recent year (1999–2001) redds-per-mile estimates of winter-run steelhead escapement 

in Fifteenmile Creek were also up substantially relative to annual levels in the early 1990s. 

Returns to the Touchet River are lower than the previous 5-year average. Trend or count 

information for the Klickitat River winter-run steelhead run are not available, but current 

return levels are believed to be below interim target level. 

202
17. MIDDLE COLUMBIA RIVER STEELHEAD ESU 

Productivity 

Short-term trends in major production areas were positive for 7 of the 12 areas (Table 

37). The median annual rate of change in abundance since 1990 was 2.5%; individual trend 

estimates ranged from –7.9% to 11%. The same basic pattern was reflected in λ estimates for 

the production areas. The median short-term (1990–2001) annual population growth rate 

estimate was 1.045, assuming that hatchery fish on the spawning grounds did not contribute to 

natural production, with 8 of the 12 indicator trends having a positive growth rate. Assuming 

that potential hatchery spawners contributed at the same rate as natural-origin spawners 

resulted in lower estimates of population growth rates. The median short-term λ under the 

assumption of equal hatchery- and natural-origin spawner effectiveness was .967, with 6 of 

the 12 indicator trends exhibiting positive growth rates. 

Long-term trend estimates were also calculated using the entire length of the data 

series available for each production area (Table 37). The median estimate of long-term trend 

over the 12 indicator data sets was –2.1% per year (–6.9 to 2.9), with 11 of the 12 being 

negative. Long-term annual population growth rates (λ) were also negative (Table 37). The 

median long-term λ was .98, assuming that hatchery spawners do not contribute to 

production, and .97 assuming that both hatchery- and natural-origin spawners contribute 

equally. These longer trends are consistent with another recent analysis (McClure et al. 2003) 

of 28 index areas in the Middle Columbia River steelhead ESU from 1980 to 2000. In this 

analysis, the average population growth rate across all streams was 0.96, with only 2 of the 28 

index areas showing a positive trend. (Note that the analyses in McClure et al. [2003] bracket 

those in the 2000 FCRPS Biological Opinion, which used slightly different assumptions about 

hatchery fish spawning effectiveness.) 

All of the production area trends available for this ESU indicate relatively low 

escapement levels in the 1990s. For some of the data sets, earlier annual escapements were 

relatively high compared to the stream miles available for spawning and rearing. In those 

cases, it is reasonable to assume that subsequent production may have been influenced by 

density-dependent effects. In addition, there is evidence of large fluctuations in marine 

survival for Columbia River and Oregon coast steelhead stocks (Chilcote 2001, Cooney 

2001). Spawner return time-series data sets available for mid-Columbia production areas 

cover a relatively short span of years. As a result, population growth rate projections and 

stock/recruit function fits using these data sets should be interpreted with caution. 

Resident O. mykiss Considerations 

This section summarizes available information on resident O. mykiss populations 

within the Middle Columbia River steelhead ESU. Table 39 and Appendix B, Table B-1 

provide a broad overview of the distribution of case 1, 2, and 3 resident populations within the 

ESU. See the subsection, Resident Fish, in Section 14, Background and History of Listings, 

for an explanation of the three cases and their relevance to ESU determinations, and a 

discussion of how resident fish are considered in risk analyses. 

203
Table 37. Summary of recent 5-year average (geometric mean) population abundance and trend estimates in comparison to 

the previous BRT status review (NMFS 1999b). 

Recent 5-year geometric mean 

Total Natural 

Short-term trend 

(%/year) 

Population 

5-year mean % 

natural origin Mean (range) Current Previous Current Previous 

Klickitat River Unknown 155 redds(97–261) – – +14.6 –9.2 Yakima Rivera 97[95]c 1,801(1,058–4,061) 1,747 800 +10.0 +14.0 

Fifteenmile Creeka 100[100?]c 2.87 rpm(1.3–6.0) – – +7.8 –5.4 

Deschutes River 38[50]c 13,455(10,026–21,457) 5,113 3,000 +11.2 +2.6 

John Day upper main stem 96[100]c 2,122(926–4,168) 2,037 – –1.7 –15.2 

John Day lower main stem nrd 1.40 rpm (0.0–5.4) – – –2.5 –15.9 

John Day upper North Fork nrd 2.57 rpm(1.6–5.0) – – +9.6 –11.8 

John Day lower North Fork nrd 3.52 rpm (1.5–8.8) – – +11.0 –1.2 

John Day Middle Fork nrd 3.70 rpm (1.7–6.2) – – –2.7 –13.7 John Day South Fork nrd 2.52 rpm (0.9–8.2) – – –0.8 –7.4 Umatilla River 60[76]c 2,486(1,480–5,157) 1,492 1,096 +8.6 +0.7 

Touchet Riverb 84[93]c 345 (273–527) 289 300 –0.5 –2.7 

a 5-year geometric mean calculated using years 1997–2001. b 5-year geometric mean calculated using only years 1998–2001. c Estimates from previous status reviews are in brackets. d nr = no releases.

204
Table 38. Middle Columbia River steelhead ESU population growth-rate analysis. Summary of available trend data sets, r

annual population growth rates (

λ), geometric mean, and probability that 

λ < 1.0. 

Proportion wild 

Populations 

Series 

length Methodsa 1987–1996

Last 5 

years 

Hatchery 

effectiveness 

assumptionb

Recent 

(5 yr) 

Mean 

Long 

term 

λc

Pr

lo

te

(λ

Yakima River aggregate 1981–2000 dc 0.942 HF = 0.0 901 1.009 0Klickitat River 1990–1992

1996–2001 

dc na na 

Deschutes River 1978–2002 dc 0.4 0.38 HF = 0.0 

HF = 1.0 

5566 1.022

0.840

00

Warm Springs (above weir) 1980–1999 1 1 0.942 0

John Day River 

Upper main stem 1974–2002 Exp. rc 0.986 0.963 HF = 0.0 

HF = 1.0 

2256 0.975

0.966

00

Lower main stem 1965–2001 Exp. rc 1 0.981 0Upper North Fork 1977–2002 Exp. rc 1 1.011 0Lower North Fork 1976–2002 Exp. rc 1 1.013 0Middle Fork 1974–2002 Exp. rc 1 0.966 0South Fork 1974–2002 Exp. rc 1 0.967 0

Umatilla River 1966–2002 dc 0.758 0.674 HF = 0.0 

HF = 1.0 

1658 1.007

0.969

00

Walla Walla 

Touchet River 1987–2001 dc 0.911 0.842 HF = 0.0 

HF = 1.0 

290 0.961

0.939

00

Main fork 1993–2000 dc Data series too short to calculate trends 

Fifteenmile Creek (winter run) 1966–2001 rpm na na 3.48 0.981 0a Methods: dc = dam counts; rc = redd counts; rpm = redds per mile index. b Population growth rates calculated for two hatchery effectiveness (HF) assumptions: HF = 0.0 hatchery fish available to spawn, do no

production, HF = 1.0 hatchery returns available to spawn, contribute to broodyear natural production at the same rate as natural-origin 

c Long term = the length of the available data series. d Short term = 1990–2001, or most recent years. 

205
STEELHEAD

Resident O. mykiss are sympatric with current and historical anadromous steelhead 

distribution throughout the Middle Columbia River steelhead ESU (Kostow 2003). 

Pelton/Round Butte Dam in the Deschutes River system and Condit Dam in the White Salmon 

River are the major anadromous blockages in tributaries in this ESU. Irrigation diversions in 

other tributaries, including the Umatilla and Yakima rivers, result in partial blockages or reduce 

the survival of migrating steelhead. Decades of agricultural impacts have heavily affected lower 

reaches of most major tributaries in this ESU. The Deschutes River is an exception; its lower 

tributaries are relatively intact, with strong flows of cold water. The resident O. mykiss

population in the lower Deschutes River is highly productive, supporting some of the largest and 

most fecund trout in the entire Columbia River basin (Kostow 2003). 

Tributaries and mainstem reaches in the upper portions of the Umatilla, Walla Walla, and 

Klickitat rivers are all relatively intact and support both steelhead and resident O. mykiss

populations, although there are no specific estimates of abundance for the resident form (Kostow 

2003).

Resident O. mykiss production varies widely among the tributaries of the relatively large 

Yakima River system. For 18 years, Roza Dam effectively cut off access for returning 

anadromous migrants to the upper Yakima River drainage. That area is believed to have been 

the most productive historical habitat for steelhead. Resident O. mykiss currently dominate 

production above Roza Dam. Two lower Yakima tributaries, Satus and Toppenish creeks, 

support most of the current steelhead production from the basin. The absence of age-2 and older 

smolts in these tributaries indicates little or no resident production. Steelhead and resident trout 

are present in the Naches River subbasin. 

The John Day River system may have historically supported large populations of resident 

trout; their redds have been observed during steelhead redd surveys in this system (Kostow 

2003). Some proportion of the age-0/age-1 fish counted during juvenile transects may be 

resident trout, although these redds are not systematically counted. 

Water withdrawals and other agricultural activities have heavily impacted the mainstem 

Umatilla River. However, headwater reaches are generally intact and have the capacity to 

support fairly large anadromous and resident O. mykiss juvenile production. Abundance 

estimates of juvenile O. mykiss from the upper Umatilla main stem and its tributaries show a 

high percentage of age-0 and age-1 juveniles, while those age 2 and older make up a relatively 

small proportion of the juveniles sampled. Kostow (2003) concluded that resident adults may 

still outnumber returning steelhead in the basin. 

Studies of relative spawning distributions and timing for steelhead and sympatric resident 

O. mykiss populations have been conducted on the upper Yakima River (Pearsons et al. (1998) 

and Deschutes River (Zimmerman and Reeves 2000). Pearsons et al. (1998) concluded that there 

were substantial overlaps in spawning timing and distribution in the upper Yakima River, with 

steelhead spawning distributions generally nested within those of resident O. mykiss. The 

Deschutes River study indicated less overlap because of differences in microhabitat the two 

forms use. In a previous study, Zimmerman and Reeves (1996) documented trout and steelhead 

pairing late in the steelhead spawning period. Kostow (2003) reported observations of possible 

206
17. MIDDLE COLUMBIA RIVER STEELHEAD ESU

steelhead resident pairings during spawning on the John Day, Klickitat, Walla Walla, and 

Umatilla rivers. 

Zimmerman and Reeves (2000) used otolith microchemistry to compare samples of 

returning adult steelhead to samples taken from resident trout. They concluded that the 

anadromous steelhead sampled had anadromous mothers, and that the resident trout sampled had 

resident mothers. The study was unable to determine the corresponding contributions of 

anadromous and resident males to anadromous and resident progeny. 

In the Klickitat River basin, a sample of presumed resident fish from above Castille Falls 

appears to be of native origin (rather than introduced rainbow trout), based on genetic analyses 

conducted by WDFW (Phelps et al. 2000). However, this is a case 2 population (above a natural 

barrier) and is also differentiated from anadromous populations within the ESU. Currens (1997) 

found genetic evidence for substantial isolation between resident fish in Eightmile Creek (a 

tributary of Fifteenmile Creek) and anadromous fish within the ESU. This is believed to be a 

case 1 population—historical contact with anadromous fish and no apparent barrier to migration 

at present. The genetic profile for the resident fish is consistent with it being a native redband 

population rather than introduced rainbow trout. 

Currens (1997) genetically compared case 3 resident O. mykiss above artificial barriers in 

McKay and Butter creeks (both tributaries of the Umatilla River) with samples from Umatilla 

River steelhead. Currens found considerable variation among all samples, but the samples from 

McKay Creek were particularly distinctive. Currens speculated that the McKay Creek 

population may have been introgressed with nonnative hatchery rainbow trout, which have been 

stocked in the area. 

In the Deschutes River basin, Currens et al. (1990) found genetic differences between O. 

mykiss populations from upper and lower Nena and East Fork Foley creeks that were of the same 

magnitude as differences among different steelhead populations within the basin. The upper and 

lower reaches of these creeks are separated by natural waterfalls, which may or may not serve as 

barriers to anadromous fish (hence, it is uncertain whether these are case 1 or case 3 

populations). White River Falls is an ancient barrier, and case 2 resident fish above the falls are 

genetically quite distinctive (Currens et al. 1990). 

In the John Day River, Currens et al. (1987) found that genetic differences between O. 

mykiss from the North and South Forks were larger than differences between presumed steelhead 

and (case 1) rainbow trout in the South Fork. Genetic analysis of Yakima River O. mykiss 

(Pearsons et al. 1998) found no significant differences between sympatric resident (case 1) and 

anadromous fish, a finding that is consistent with observations of interbreeding between the two 

forms. 

New Hatchery Information 

Relatively high numbers of hatchery-origin steelhead returning from releases outside of 

the Deschutes River system continue to enter the Deschutes system. We do not know the actual 

number of out-of-basin-origin hatchery fish that spawn naturally in the Deschutes. Preliminary 

207
STEELHEAD

results from recent radio tracking studies cited in Cramer et al. (2002) backs up the hypothesis 

that a significant proportion of hatchery strays entering the Deschutes River are “dip-ins,” fish 

that migrate out of the system prior to spawning. The estimated escapements to the spawning 

grounds used in the status review updates already include an adjustment to reflect outmigrating 

stray hatchery fish. The estimates of spawning escapement into the Deschutes River system 

depicted in Figure 139 assume that 50% of the estimated number of outside hatchery fish passing 

over Sherars Falls dropped back down and did not contribute to spawning in the Deschutes River 

system (Chilcote 2002). Cramer et al. (2002) identified two other sets of information regarding 

the potential contribution of hatchery stocks to natural spawning in the Deschutes River. ODFW 

spawner surveys in Buckhollow, Bakeoven, and Trout creeks indicate a relatively high 

Table 39. Distribution of steelhead populations by category relative to the Middle Columbia River 

steelhead ESU. 

Category 1 populations 

(sympatric)a

Category 2 populations 

(major natural barriers)b

Category 3 populations 

(major artificial barriers)b

Historically all areas where 

steelhead are or were present. 

Trout distributions currently more 

restricted. 

Fifteenmile Creek 

Eightmile Creek 

Deschutes River 

KlickitatRiver 

Umatilla River 

Upper Umatilla River 

John Day River 

Upper tributaries 

Walla Walla River 

Upper tributaries 

Yakima River 

Upper Yakima River 

Naches River 

Some other small tributaries 

All natural barriers upstream of 

Klickitat and Deschutes basins. 

Deschutes River 

White River 

Upper Deschutes (Big Falls) 

River 

Upper North Fork Crooked 

River 

John Day River 

Upper South Fork John Day 

River 

Trout distributions currently 

more restricted than historically. 

Little White Salmon River 

(Conduit Dam) 

Deschutes River (Pelton/Round 

Butte Dams) 

Metolius River 

Squaw Creek 

Crooked River 

Umatilla River (irrigation 

dams) 

Willow Creek 

Butter Creek 

McKay Creek 

a O. mykiss distribution in areas of sympatry with steelhead may be restricted in some areas if native O. clarki are 

also in the basin. The generalized listing of basins and subbasins does not imply that these constitute single trout 

populations or that trout distribution is continuous throughout the areas listed. Detailed trout distribution is 

usually unknown and actual demographically independent trout populations have not been described. All current 

trout distributions are decreased from historical distributions. In particular, many mainstem and lower basin 

tributaries are no longer used but probably were historically. Many current trout populations are only in upper 

basins and are highly fragmented. 

b

 Only major barriers are noted; numerous small barriers, both natural and artificial, also exist. Many other natural 

barriers are present but have O. clarki, rather than O. mykiss, above them. 

208
17. MIDDLE COLUMBIA RIVER STEELHEAD ESU

Table 40. Steelhead hatchery releases in the middle Columbia River region by major steelhead 

production areas and broodstock. 

Average*

 releases per year 

Basin Race Stock 1985–1989 1990–1994 1995–2001

Mainstem Columbia River Summer Unknown 4,523 – – 

 Summer Dworshak B – 5,440 412 

Mainstem total 4,523 5,440 412 

White Salmon River Summer Skamania 9,798 18,238 8,641 

 Winter Skamania 12,414 32,615 17,497 

 Winter Elochoman River – – 6,428 

 Winter Kalama River – – 3,669 

 Winter Beaver Creek – – 5,741 

 

White Salmon 

total 

22,212 50, 854 41,976 

Little White Salmon 

River 

Summer Skamania 0 0 15,395 

Klickitat River Summer Skamania 87,821 96,704 113,616 

Deschutes River Summer Deschutes River 209,443 163,505 168,680 

Rock Creek Winter Skamania 1,428 5,176 4,083 

 Winter Elochoman River – – 1,560 

 Rock Creek total 1,428 5,176 5,644 

Umatilla River Summer Umatilla River 66,730 130,958 142,259 

Walla Walla River Summer Lyons Ferry 191,854 208,632 293,256 

 Summer Wells 116,396 – – 

 Summer Ringold – 55,752 – 

 Summer Touchet River – – 5,212 

 Walla Walla total 308,251 264,385 298,469 

Yakima Summer Ringold 21,726 – – 

 Summer Wells 18,201 – – 

 Summer Yakima River 112,641 72,039 – 

Yakima total 152,569 72,039 0 

ESU total All stocks 852,978 789,063 786,451 *

 Averages are calculated by time period to facilitate comparison of release levels since the last BRT review 

(NMFS 1999b) with previous levels. 

proportion of wild fish in those tributaries in recent years in comparison to the estimated fraction 

of wild fish in the total run entering the Deschutes River for those years. In addition, estimated 

natural-origin returns to the main stem or lower tributary roughly track the returns to the Warm 

Springs River in time, in spite of large differences in estimated hatchery contributions in some 

years. Additional information is needed to clarify the potential impact of outside hatchery-origin 

fish to natural production in the system. Categorizations of Middle Columbia River steelhead 

ESU hatchery stocks (SSHAG 2003) can be found in Appendix B, Table B-3. 

209
STEELHEAD

0

500

1000

1500

2000

2500

3000

3500

4000

4500

1975 1980 1985 1990 1995 2000 2005

Year

Spawners

TLC Natural origin

Figure 138. Yakima River steelhead spawning escapement estimates, 1980–2001. Source: From 

Washington Department of Fish and Wildlife database (see Appendix A, Table A-2). Based on 

Prosser Dam count. 

0

5000

10000

15000

20000

25000

1975 1980 1985 1990 1995 2000 2005

Return year

Escapement above Sherars Falls 

Total available to spawn Natural origin

Figure 139. Deschutes River steelhead escapement estimates over Sherars Falls, 1978–2002. Sources: 

Run size estimates based on Oregon Department of Fish and Wildlife mark-recapture analysis. 

Hatchery:wild ratios based on returns to Pelton Ladder and Warm Springs National Fish Hatchery 

(see Chilcote 2001, 2002). 

210
17. MIDDLE COLUMBIA RIVER STEELHEAD ESU

0

200

400

600

800

1000

1200

1986 1988 1990 1992 1994 1996 1998 2000 2002

Year

Abundance

Total Natural origin

Figure 140. Touchet River steelhead escapement estimates, 1987–2001. Source: Estimates based on 

spawning ground surveys upstream of Dayton, Washington, from James and Scheeler (2001). 

0

1000

2000

3000

4000

5000

6000

1970 1975 1980 1985 1990 1995 2000 2005

Return year

Dam counts

Natural origin Total available to spawn

Figure 141. Umatilla River steelhead counts at Three Mile Dam, 1966–2002. Source: Chilcote (2001). 

211
STEELHEAD

0

2000

4000

6000

8000

10000

12000

1970 1975 1980 1985 1990 1995 2000 2005

Spawning year

Redds per mile

Total Natural

Figure 142. Upper John Day River steelhead estimates, based on annual redd counts, 1974–2002. 

Source: Chilcote (2002). 

0

2

4

6

8

10

12

14

16

1970 1975 1980 1985 1990 1995 2000 2005

Spawning year

Redds per mile

Total Natural

Figure 143. South Fork John Day River steelhead redds per mile from index areas, 1974–2002. Source: 

Chilcote (2001). 

212
17. MIDDLE COLUMBIA RIVER STEELHEAD ESU

0

5

10

15

20

25

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Spawning year

Redds per mile

Total Natural

Figure 144. Lower mainstem John Day River steelhead redds per mile from index areas, 1965–2001. 

Source: Chilcote (2001). 

0

2

4

6

8

10

12

14

16

18

20

1970 1975 1980 1985 1990 1995 2000 2005

Spawning year

Redds per mile

Total

Figure 145. Middle Fork John Day River steelhead redds per mile from index areas, 1974–2001. Source: 

Chilcote (2001). 

213
STEELHEAD

0

1

2

3

4

5

6

7

8

1975 1980 1985 1990 1995 2000 2005

Spawning year

Redds per mile

Total

Figure 146. Upper North Fork John Day River steelhead redds per mile from index areas, 1977–2002. 

Source: Chilcote (2001). 

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

1970 1975 1980 1985 1990 1995 2000 2005

Spawning year

Redds per mile

Total

Figure 147. Lower North Fork John Day River steelhead redds per mile from index areas, 1976–2002. 

Source: Chilcote (2001). 

214
18. Lower Columbia River Steelhead ESU 

Summary of Previous BRT Conclusions 

NMFS initially reviewed the status of the Lower Columbia River steelhead ESU in 1996 

(Busby et al. 1996) and most recently in 1998 (NMFS 1998c). In the 1998 review, the BRT 

noted several concerns for this ESU, including low abundance relative to historical levels, 

universal and often drastic declines observed since the mid-1980s, and widespread occurrence of 

hatchery fish in naturally spawning steelhead populations. Analysis also suggested that 

introduced summer-run steelhead may negatively affect native winter-run steelhead in some 

populations. A majority of the 1998 BRT concluded that steelhead in the Lower Columbia River 

steelhead ESU were at risk of becoming endangered in the foreseeable future. 

Listing status: Threatened. 

New Data and Updated Analyses 

New data available for this update included recent spawner data, additional data on the 

fraction of hatchery-origin spawners, recent harvest rates, updated hatchery release information 

and a compilation of data on resident O. mykiss. For many Washington Chinook salmon 

populations, the WDFW has conducted analyses using the EDT model (Busack and Rawding 

2003), which predicts fish population performance based on data about reach-specific habitat 

attributes (http://www.olympus.net/community/dungenesswc/EDT-primer.pdf). New analyses 

for this update include the designation of demographically independent populations, 

recalculation of previous BRT metrics with additional years’ data, estimates of median annual 

growth rate (λ) under different assumptions about the reproductive success of hatchery fish, and 

estimates of current and historically available stream kilometers. 

Historical Population Structure 

As part of its effort to develop viability criteria for lower Columbia River steelhead, the 

WLC-TRT identified historical demographically independent populations (Myers et al. 2002). 

Population boundaries are based on an application of the VSP definition by McElhany et al. 

(2000). Myers et al. hypothesized that the ESU historically consisted of 17 winter-run 

populations and 6 summer-run populations, for a total of 23 populations (Figures 148 and 149). 

The WLC-TRT partitioned Lower Columbia River steelhead ESU populations into a 

number of strata based on major life history characteristics and ecological zones (McElhany

215 
Table 41. Historical population structure and abundance statistics for Lower Columbia River steelhead ESU populations, b

major life history type. 

Life historya Ecological zoneb Population 

Years of 

data for 

recent 

meansc

Recent 

geometric 

mean total 

spawners 

Recent 

arithmetic 

mean total 

spawners 

Cispus River Tilton River Upper Cowlitz River 

2002 2,787 2,787 

Lower Cowlitz River – N o d a t a – Coweeman River 1998–2002 466 490 South Fork Toutle River 1998–2002 504 554 North Fork Toutle River 1998–2002 196 207 Kalama River 1998–2002 726 797 North Fork Lewis – N o d a t a – East Fork Lewis Index data only; no abundance means Salmon Creek – N o d a t a – Washougal River 1998–2002 323 376 Clackamas River 1997–2001 560 717 

Cascade 

Sandy River 1997–2001 977 997 Lower gorge tributaries – N o d a t a – Upper gorge tributaries – N o d a t a – 

Winter run 

Columbia Gorge 

Hood River 1996–2000 756 792 

Summer run Cascade Kalama River 1999–2003 474 633 

North Fork Lewis – N o d a t a – 

East Fork Lewis 1999–2003 434 514 

Washougal River 1999–2003 264 313 

Columbia Gorge Wind River 1999–2003 472 535 

Hood River 1996–2000 931 1,003 

a Life history types are based on traits related to run timing. b Ecological zones are based on ecological community and hydrodynamic patterns. c Time series used for the summary statistics are referenced in Appendix B, Table B-4. 

216 
18. LOWER COLUMBIA RIVER STEELHEAD ESU 

Figure 148. Historical populations of winter-run steelhead in the Lower Columbia River steelhead ESU. 

Source: Myers et al. (2002). 

et al. 2003). WLC-TRT analysis suggests that a viable ESU would need multiple viable 

populations in each stratum. The strata and associated populations are identified in Table 41. 

Abundance and Trends 

Reference citations for abundance time series and related data are presented in Appendix 

B, Table B-4. Recent abundance of total spawners, and recent fraction of hatchery-origin 

spawners for Lower Columbia River steelhead ESU populations are summarized in Table 41. 

The abundance means in Table 41 are for total spawners; they include both natural- and 

hatchery-origin fish. Natural-origin fish had parents that spawned in the wild, as opposed to 

hatchery-origin fish, whose parents were spawned in a hatchery. A number of the populations 

have a substantial fraction of hatchery-origin spawners in the spawning areas and are 

hypothesized to be sustained largely by hatchery production. Exceptions are the Kalama, North 

and South Fork Toutle, and East Fork Lewis winter-run populations, which have few hatchery 

fish spawning in natural spawning areas. These populations have relatively low recent mean 

abundance estimates; the largest is the Kalama River, with a geometric mean of 726 spawners. 

217
STEELHEAD

Figure 149. Historical populations of summer–run steelhead in the Lower Columbia River steelhead 

ESU. Source: Myers et al. (2002). 

The pooled estimate of abundance for the historical Cispus, Tilton, and upper Cowlitz 

river populations has the highest recent total spawner abundance in the Lower Columbia River 

steelhead ESU, as well as the largest fraction of hatchery-origin spawners. The hatchery-origin 

spawners are part of a reintroduction program to establish steelhead above Cowlitz Falls Dam, 

the uppermost of three impassable dams on the mainstem Cowlitz River (Serl and Morrill 2002). 

Adults are collected below the most downstream dam (Mayfield) and trucked above Cowlitz 

Falls Dam. Downstream survival of juvenile steelhead though the dams and reservoirs is 

considered negligible, so juveniles are collected at Cowlitz Falls Dam and trucked downstream. 

The current collection efficiency of juveniles at Cowlitz Falls Dam is considered too low 

for the reintroduction to be self-sustaining.18

 

18See Footnote 9. 

218
18. LOWER COLUMBIA RIVER STEELHEAD ESU 

Where data are available, Figures 150–170 present the abundance time-series information 

for each population. We give two types of time-series figures. The first type plots abundance 

against time (Figures 150, 152, 154, 156, 158, 160, 162–166, 168, 170). Where possible, two 

lines are presented on the abundance figure: One line is the total number of spawners (or total 

count at a dam), and the other line is the number of fish of natural origin. In cases for which data 

were not available to distinguish between natural- and hatchery-origin spawners, only total 

spawner (or dam count) information is presented in order to give a sense of abundance levels, 

overall trend, variability patterns, and fraction of hatchery-origin spawners. 

The second type of figure presents the total number of spawners (natural- and hatcheryorigin) and number of preharvest recruits produced by those spawners by broodyear (Figures 

151, 153, 155, 157, 159, 161, 167, 169, and 171). Dividing the number of preharvest recruits by 

the number of spawners for the same time period would yield an estimate of the preharvest 

recruits per spawner. These figures require harvest and age-structure information; therefore they 

could be produced for only a limited number of populations. These figures can indicate whether 

preharvest recruitment, and the degree to which harvest management has the potential to recover 

populations, has changed. If the preharvest recruitment line is consistently below the spawner 

line, the population would not be replacing itself, even in the absence of all harvest. 

Summary statistics on population trends and growth rate are presented in Tables 42–45 

and Figures 172–174. The methods for estimating trends and growth rate (λ) are described in 

Section 2. The majority of populations have a long-term trend of less than 1, indicating that the 

population is in decline. In addition, for most populations the probability is high that the true 

trend/growth rate is less than 1 (Table 43). When growth rate is estimated, assuming that 

hatchery-origin spawners have a reproductive success equal to that of natural-origin spawners, 

all the populations have a negative growth rate except the North Fork Toutle River winter run, 

which had very few hatchery-origin spawners (Figure 170). The North Fork Toutle population is 

still recovering from the 1980 eruption of Mount St. Helens and is still at low abundance (recent 

mean of 196 spawners). Previous status reviews cataloged the potential reasons for these 

declines; they include habitat degradation, deleterious hatchery practices, and climate-driven 

changes in marine survival. 

Rawding (2003) suggests a major factor driving the decline observed in the available 

time series are marine conditions, and that marine survival is largely responsible for the increases 

observed in the last few years. He poses as an important question: What will happen to lower 

Columbia River steelhead when ocean conditions cycle back to less-productive regimes? 

Because this issue applies to many ESUs, it is discussed in Section 1, Introduction. 

219
STEELHEAD

Table 42. Long-term trend and growth rate for a subset of Lower Columbia River steelhead ESU 

populations for which adequate data are available (95% confidence intervals are in parentheses). 

Median growth rate (λ)

c

Run Population 

Years for 

trend and λα

Trend of total 

spawnersb Hatchery = 0d

Hatchery = 

wilde

Coweeman 1987–2002 0.916 

(0.847–0.990) 

0.908 

(0.792–1.041) 

0.782 

(0.678–0.903) 

South Fork Toutle 1984–2002 0.917 

(0.876–0.961) 

0.938 

(0.830–1.059) 

0.933 

(0.821–1.061) 

North Fork Toutle 1989–2002 1.135 

(1.038–1.242) 

1.062 

(0.915–1.233) 

1.062 

(0.915–1.233) 

Kalama 1977–2002 0.998 

(0.973–1.023) 

1.010 

(0.913–1.117) 

0.916 

(0.824–1.019) 

Clackamas 1958–2001 0.979 

(0.966–0.993) 

0.971 

(0.901–1.047) 

0.949 

(0.877–1.027) 

Winter 

Sandy 1978–2001 0.940 

(0.919–0.960) 

0.945 

(0.850–1.051) 

0.828 

(0.741–0.925) 

Summer Kalama 1977–2003 0.928 

(0.889–0.969) 

0.981 

(0.889–1.083) 

0.712 

(0.642–0.790) 

Washougal 1986–2003 0.991 

(0.942–1.043) 

1.003 

(0.884–1.138) 

0.996 

(0.872–1.138) 

Washougal 1989–2003 0.973 

(0.921–1.028) 

0.983 

(0.853–1.134) 

0.937 

(0.807–1.089) a The long-term analysis used the entire data set. 

b The trend estimate is for total spawners. It includes both natural- and hatchery-origin fish. 

c The λ calculation is an estimate of what the natural growth rate would have been after accounting for hatcheryorigin spawners. The λ estimate is calculated under two hypotheses about the reproductive success of hatcheryorigin spawners. 

d Hatchery fish are assumed to have zero reproductive success. 

e Hatchery fish are assumed to have the same relative reproductive success as natural-origin fish. 

EDT-based estimates of historical abundance 

The WDFW has conducted analyses of the Lower Columbia River Chinook salmon ESU 

populations using the EDT model (Busack and Rawding 2003). WDFW populated this model 

with estimates of historical habitat condition, which produced the estimates of average historical 

abundance shown in Table 46. There is a great deal of unquantified uncertainty in the EDT 

historical abundance estimates, and interpreting these data should include this uncertainty. In 

addition, the habitat scenarios evaluated as “historical” may not reflect historical distributions, 

because some areas that were historically accessible but currently are blocked by large dams are 

omitted from the analyses, and some areas that were historically inaccessible but recently 

became passable because of human intervention are included. The EDT outputs are provided 

here to give a sense of historical abundance of populations relative to each other and an estimate 

of historical abundance relative to current abundance.

220
18. LOWER COLUMBIA RIVER STEELHEAD ESU 

Table 43. Short-term trend and growth rate for a subset of Lower Columbia River steelhead ESU 

populations for which adequate data are available (95% confidence intervals are in parentheses). 

Median growth rate (λ)

c

Run Population 

Years for 

trenda

Trend of total 

spawnersb Hatchery = 0d Hatchery = wilde

Coweeman 1990–2002 0.941 

(0.818–1.083) 

0.920 

(0.803–1.055) 

0.787 

(0.682–0.909) 

South Fork Toutle 1990–2002 0.939 

(0.856–1.130) 

0.933 

(0.826–1.054) 

0.929 

(0.817–1.056) 

North Fork Toutle 1990–2002 1.086 

(0.999–1.018) 

1.038 

(0.894–1.206) 

1.038 

(0.894–1.206) 

Kalama 1990–2002 1.004 

(0.923–1.091) 

0.984 

(0.890–1.088) 

0.922 

(0.829–1.025) 

Clackamas 1990–2001 0.914 

(0.806–1.036) 

0.875 

(0.812–0.943) 

0.830 

(0.767–0.898) 

Winter 

Sandy 1990–2001 0.889 

(0.835–0.946) 

0.866 

(0.797–0.985) 

0.782 

(0.700–0.874) 

Summer Kalama 1990–2003 0.855 

(0.756–0.968) 

0.900 

(0.816–0.994) 

0.664 

(0.598–0.737) 

Washougal 1990–2003 1.024 

(0.951–1.104) 

1.029 

(0.907–1.168) 

0.960 

(0.841–1.097) 

Wind 1990–2003 0.989 

(0.931–1.049) 

0.995 

(0.863–1.148) 

0.903 

(0.777–1.049) a

 Short-term data sets include data from 1990 to the most recent available year. 

b

 The trend estimate is for total spawners. It includes both natural- and hatchery-origin fish. 

c

 The λ calculation is an estimate of what the natural growth rate would have been after accounting for hatcheryorigin spawners. The λ estimate is calculated under two hypotheses about the reproductive success of hatcheryorigin spawners. d

 Hatchery fish are assumed to have zero reproductive success. 

e

 Hatchery fish are assumed to have the same relative reproductive success as natural-origin fish. 

Table 44. Probability that the long-term abundance trend or growth rate of a subset of Lower Columbia 

River steelhead ESU populations is less than 1. 

Probability λ < 1 

Run Population 

Years for trend 

and λ

Probability 

trend < 1 Hatchery = 0a Hatchery = wildb

Coweeman 1987–2002 0.985 0.936 1.000 

South Fork Toutle 1984–2002 0.999 0.884 0.899 

North Fork Toutle 1989–2002 0.005 0.063 0.063 

Kalama 1977–2002 0.574 0.405 0.971 

Clackamas 1958–2001 0.998 0.784 0.918 

Winter 

Sandy 1978–2001 1.000 0.993 1.000 

Summer Kalama 1977–2003 0.999 0.613 1.000 

Washougal 1986–2003 0.644 0.476 0.526 

Wind 1989–2003 0.848 0.639 0.889 a

 Hatchery-origin fish are assumed to have zero reproductive success. 

b

 Hatchery-origin fish are assumed to have reproductive success equivalent to that of natural-origin fish. 

221
STEELHEAD

Table 45. Probability that the long-term abundance trend or growth rate of a subset of Lower Columbia 

River steelhead ESU populations is less than 1. 

Probability λ < 1 

Run Population Years for trend

Probability 

trend < 1 Hatchery = 0a Hatchery = wildb

Coweeman 1990–2002 0.822 0.851 0.995 

South Fork Toutle 1990–2002 0.919 0.797 0.812 

North Fork Toutle 1990–2002 0.026 0.135 0.135 

Kalama 1990–2002 0.463 0.593 0.846 

Clackamas 1990–2001 0.929 0.849 0.929 

Winter 

Sandy 1990–2001 0.999 0.991 1.000 

Summer Kalama 1990–2003 0.991 0.849 1.000 

Washougal 1990–2003 0.249 0.349 0.757 

Wind 1990–2003 0.659 0.538 0.989 a

 Hatchery-origin fish are assumed to have zero reproductive success. 

b Hatchery-origin fish are assumed to have reproductive success equivalent to that of natural-origin fish. 

Table 46. Estimates of historical abundance for a subset of Lower Columbia River steelhead ESU 

populations, based on the EDT model. 

Life history Population 

EDT estimate of historical 

abundance 

Coweeman River 2,243 

Lower Cowlitz River 1,672 

South Fork Toutle River 2,627 

North Fork Toutle River 3,770 

Kalama River 554 

North Fork Lewis River 713 

East Fork Lewis River 3,131 

Salmon Creek – 

Washougal River 2,497 

Lower Columbia Gorge tributaries 793 

Upper Columbia Gorge tributaries 243 

Winter run 

Hood River – 

Summer run Kalama River 3,165 

East Fork Lewis River 422 

Washougal River 1,419 

Wind River 2,288 

Loss of habitat from barriers 

Steel and Sheer (2003) conducted an analysis to assess the number of stream kilometers 

historically and currently available to salmon populations in the lower Columbia River 

(Table 46). Stream kilometers usable by salmon are determined based on simple gradient cutoffs 

and the presence of impassable barriers. Barriers with passage limited to trap-and-haul are 

considered impassable for this analysis. This approach will overestimate the number of usable 

222
18. LOWER COLUMBIA RIVER STEELHEAD ESU 

stream kilometers because it does not consider habitat quality (other than gradient). However, 

the analysis does indicate that for some populations the number of stream habitat kilometers 

currently accessible is greatly reduced from the historical condition. 

Resident O. mykiss Considerations 

The available information on resident O. mykiss populations within the Lower Columbia 

River steelhead ESU is summarized in Table 31 and Appendix B, Table B-1. The tables provide 

a broad overview of the distribution of case 1, 2, and 3 resident populations within the ESU. See 

the subsection, Resident Fish, in Section 1 for an explanation of the three cases and their 

relevance to ESU determinations. The subsection, Resident Fish, in Section 14, Background and 

History of Steelhead Listings, discusses how the BRT considered resident fish in risk analyses. 

Table 47. Loss of habitat from barriers in the Lower Columbia River steelhead ESU. 

Run Population 

Potential 

current 

habitata

Potential 

historical habitat 

(km)b

Current to 

historical habitat 

ratioc

Cispus River 0 87 0% 

Coweeman River 85 102 84% 

Lower Cowlitz River 542 674 80% 

Upper Cowlitz River 6 358 2% 

Tilton River 0 120 0% 

South Fork Toutle River 82 92 8% 

North Fork Toutle River 209 330 63% 

Kalama River 112 122 92% 

North Fork Lewis River 115 525 22% 

East Fork Lewis River 239 315 76% 

Salmon Creek 222 252 88% 

Washougal River 122 232 53% 

Clackamas River 919 1,127 82% 

Sandy River 295 386 76% 

Lower Columbia Gorge tributaries 46 46 99% 

Upper Columbia Gorge tributaries 31 31 100% 

Winter 

Hood River 138 138 99% 

Kalama River 49 54 90% 

North Fork Lewis River 78 83 94% 

East Fork Lewis River 87 364 24% 

Washougal River 181 236 77% 

Wind River 84 164 51% 

Summer 

Hood River 36 41 90% 

Total 3,678 5,879 63% a

 The potential current habitat is the kilometers of stream below all currently impassable barriers between a gradient 

of 0.5% and 4%. 

b

 The potential historical habitat is the kilometers of stream below historically impassable barriers between a 

gradient of 0.5% and 4% (summer) and 0.5% and 6% (winter). 

c

 The current to historical:habitat ratio is the percent of the historical habitat that is currently available. 

223
STEELHEAD

Kostow (2003) reviewed information on the abundance and distribution of resident O. 

mykiss for the Lower Columbia River steelhead ESU and found no quantitative estimates of 

abundance for resident O .mykiss in any Lower Columbia River ESU population. However, 

information and analysis on the distribution and relative abundance of resident O. mykiss is 

available and suggests that resident O. mykiss numerically dominate the Wind River basin and 

the West Fork Hood River basin. However, resident populations are considered less common in 

other portions of the Hood River basin. Residents are considered common in the Collowash 

subbasin of the Clackamas River, though rare or possibly absent in other parts of the basin below 

natural barriers. Resident O. mykiss are considered abundant above the Bull Run dams (1929) in 

the Sandy River basin, Merwin Dam (1931) in the Lewis River basin, and Mayfield Dam (1963) 

in the Cowlitz River basin, but are rare or absent elsewhere in these basins. We are not aware of 

specific information relevant to the ESU status of case 3 resident populations above the dams in 

the Cowlitz, Lewis, or Sandy rivers. Resident O. mykiss are probably common in the upper 

portions of the Kalama and Washougal River basins, but rare in the lower portions. Resident O. 

mykiss are considered absent from all the smaller lower Columbia River tributaries that have 

small patches of spawning anadromous O. mykiss. Cutthroat trout (O. clarki) tend not to cooccur with resident O. mykiss and appear to have historically been the predominant resident trout 

species in many of the lower Columbia River tributaries. 

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

1955 1965 1975 1985 1995 2005

Year

Abundance

Total spawners Natural-origin spawners

Figure 150. Winter-run steelhead abundance at North Fork Dam on the Clackamas River, 1958–2001. 

Source: Data from Cramer (2002a). 

224
18. LOWER COLUMBIA RIVER STEELHEAD ESU 

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total spawners Natural-origin spawners

Figure 151. Preharvest recruits and spawners for winter-run steelhead estimated from counts at North 

Fork Dam on the Clackamas River, 1958–2001. 

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total spawners Natural-origin spawners

Figure 152. Winter-run steelhead abundance at Marmot Dam on the Sandy River, 1978–2001. Source: 

Data from Cramer (2002b). 

225
STEELHEAD

0

500

1000

1500

2000

2500

3000

3500

4000

4500

1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 153. Preharvest recruits and spawners for winter-run steelhead estimated from counts at Marmot 

Dam on the Sandy River, 1978–2001. 

0

500

1,000

1,500

2,000

2,500

1980 1985 1990 1995 2000 2005

Year

Total spawners

Figure 154. Estimate of winter-run steelhead spawner abundance in the South Fork Toutle River, 

1984–2002. Approximately 2% of the total spawners are estimated to be of natural origin. 

226
18. LOWER COLUMBIA RIVER STEELHEAD ESU 

0

500

1,000

1,500

2,000

2,500

1980 1985 1990 1995 2000 2005

Broodyear

Abundance

Preharvest recruits Spawners

Figure 155. Estimate of winter-run steelhead preharvest recruits and spawners in the South Fork Toutle 

River, 1984–2002. 

0

50

100

150

200

250

300

350

1988 1990 1992 1994 1996 1998 2000 2002 2004

Year

Spawners

Figure 156. Estimate of winter-run steelhead abundance in the North Fork Toutle River. There are 

estimated to be no hatchery-origin spawners in the North Fork Toutle population, 1989–2002. 

227
STEELHEAD

0

50

100

150

200

250

300

350

1988 1990 1992 1994 1996 1998 2000 2002 2004

Broodyear

Abundance

Preharvest recruits Spawners

Figure 157. Estimate of winter-run steelhead preharvest recruits and spawners in the North Fork Toutle 

River, 1989–2002. 

0

500

1,000

1,500

2,000

2,500

3,000

1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total spawners Natural-origin spawners

Figure 158. Estimate of winter-run steelhead abundance in the Kalama River, 1977–2002. 

228
18. LOWER COLUMBIA RIVER STEELHEAD ESU 

0

500

1,000

1,500

2,000

2,500

3,000

3,500

1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 159. Estimate of winter-run steelhead preharvest recruits and spawners in the Kalama River, 

1977–2002. 

0

200

400

600

800

1,000

1,200

1,400

1986 1988 1990 1992 1994 1996 1998 2000 2002 2004

Year

Abundance

Total spawners Natural-origin spawners

Figure 160. Estimate of winter-run steelhead abundance in the Coweeman River, 1987–2002. 

229
STEELHEAD

0

200

400

600

800

1,000

1,200

1,400

1986 1988 1990 1992 1994 1996 1998 2000 2002 2004

Broodyear

Abundance

Preharvest recruits Spawners

Figure 161. Estimate of winter-run steelhead preharvest recruits and spawners in the Coweeman River, 

1987–2002. 

0

50

100

150

200

250

300

350

400

450

1980 1985 1990 1995 2000 2005

Year

Abundance of natural-origin spawners

Index area 1 Index area 2

Figure 162. Index counts of natural-origin winter-run steelhead in the East Fork Lewis River. The two 

indexes are for different areas: they cannot be directly compared and cannot be used to create a 

more continuous time trend, 1985–2002. 

230
18. LOWER COLUMBIA RIVER STEELHEAD ESU 

0

200

400

600

800

1,000

1,200

1,400

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

Year

Abundance

Total spawners Natural-origin spawners

Figure 163. Estimate of winter-run steelhead abundance in the Hood River, 1992–2000. 

0

100

200

300

400

500

600

700

800

900

1990 1992 1994 1996 1998 2000 2002 2004

Year

Total spawners

Figure 164. Estimate of winter-run steelhead abundance in the Washougal River. The percent of 

hatchery-origin spawners is considered minimal, 1991–2002. 

231
STEELHEAD

0

500

1,000

1,500

2,000

2,500

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

Year

Abundance

Total spawners Natural-origin spawners

Figure 165. Estimate of summer-run steelhead abundance in the Hood River, 1992–2000. 

0

100

200

300

400

500

600

700

1985 1990 1995 2000 2005

Year

Total spawners

Figure 166. Estimate of the total summer-run steelhead abundance in the Washougal River, 1986–2003. 

The fraction of hatchery-origin fish is minimal (the average is approximately 3%). 

232
18. LOWER COLUMBIA RIVER STEELHEAD ESU 

0

100

200

300

400

500

600

700

1985 1990 1995 2000 2005

Broodyear

Abundance

Preharvest recruits Spawners

Figure 167. Estimate of summer-run steelhead preharvest recruits and spawners in the Washougal River, 

1986–2003.

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

1975 1980 1985 1990 1995 2000 2005

Year

Abun

dance

Total spawners Natural-origin spawners

Figure 168. Estimate of summer-run steelhead abundance in the Kalama River, 1977–2003. 

233
STEELHEAD

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

1975 1980 1985 1990 1995 2000 2005

Broodyear

Abundance

Preharvest recruits Spawners

Figure 169. Estimate of summer-run steelhead preharvest recruits and spawners in the Kalama River, 

1977–2003. 

0

200

400

600

800

1,000

1,200

1,400

1,600

1988 1990 1992 1994 1996 1998 2000 2002 2004

Year

Abundance

Total spawners Natural-origin spawners

Figure 170. Estimate of summer-run steelhead abundance in the Wind River, 1989–2003. 

234
18. LOWER COLUMBIA RIVER STEELHEAD ESU 

0

200

400

600

800

1,000

1,200

1,400

1,600

1988 1990 1992 1994 1996 1998 2000 2002 2004

Broodyear

Abundance

Preharvest recruits Spawners

Figure 171. Estimate of summer-run steelhead preharvest recruits and spawners in the Washougal River, 

1989–2003. 

Coweeman

North Fork Toutle

Kalama

Clackamas

Kalama

Washougal

South Fork Toutle

Sandy

Wind

0.91

0.96

1.01

1.06

1.11

0 100 200 300 400 500 600 700 800

Recent mean natural-origin spawners

Long-term trend

Figure 172. Lower Columbia River ESU steelhead long-term trend versus 5-year geometric mean 

abundance of natural-origin spawners: * = summer-run populations; --- = a flat trend of 1. 

235
STEELHEAD

Coweeman

South Fork Toutle

Kalama

Clackamas

Sandy

Kalama

Washougal

North Fork Toutle

Wind

0.9

0.95

1

1.05

1.1

0 100 200 300 400 500 600 700 800

Recent mean natural-origin spawners

Growth rate (l)

Figure 173. Lower Columbia River ESU steelhead long-term growth rate versus 5-year geometric mean 

abundance of natural-origin spawners. The growth rate is estimated assuming the reproductive 

success of hatchery-origin spawners is 0: * = summer-run populations; --- = a flat trend of 1. 

Coweeman

Kalama

Sandy

Wind South Fork Toutle

North Fork Toutle

Clackamas

Washougal

0.77

0.82

0.87

0.92

0.97

1.02

1.07

0 100 200 300 400 500 600 700 800

Recent mean natural-origin spawners

Growth rate (l)

Figure 174. Lower Columbia River ESU steelhead long-term growth rate versus 5-year geometric mean 

abundance of natural-origin spawners. The growth rate is estimated assuming the reproductive 

success of hatchery-origin spawners is equivalent to that of natural-origin spawners: * = summerrun populations; --- = a flat trend of 1. 

236
19. Upper Willamette River Steelhead ESU 

Summary of Previous BRT Conclusions 

NMFS initially reviewed the status of the Upper Willamette River steelhead ESU in 1996 

(Busby et al. 1996); the most recent review occurred in 1999 (NMFS 1999b). In the 1999 

review, the BRT noted several concerns for this ESU, including relatively low abundance and 

steep declines since 1988. The previous BRT was also concerned about the potential negative 

interaction between nonnative summer-run steelhead and wild winter-run steelhead. The 

previous BRT considered the loss of access to historical spawning grounds because of dams to 

be a major risk factor. The 1999 BRT reached a unanimous decision that the Upper Willamette 

River steelhead ESU was at risk is of becoming endangered in the foreseeable future. 

Listing status: Threatened. 

New Data and Updated Analyses 

New data for the Upper Willamette River steelhead ESU include redd counts and 

dam/weir counts through 2000, 2001, or 2002 and estimates of hatchery fraction and harvest 

rates through 2000. New analyses for this update include the designation of demographically 

independent populations, and estimates of current and historically available stream kilometers. 

Historical Population Structure 

As part of its effort to develop viability criteria for Upper Willamette River ESU 

steelhead, the WLC-TRT identified historical demographically independent populations (Myers 

et al. 2002). Population boundaries are based on application of the VSP definition by McElhany 

et al. (2000). Myers et al. (2002) hypothesized that the ESU historically consisted of at least four 

populations (Mollala, North Santiam, South Santiam, and Calapooia) and possibly a fifth (Coast 

Range) (Figure 175). There is some uncertainty about the historical existence of a population in 

the Coast Range. The populations Myers et al. identified are used as the units for the new 

analyses in this report. 

Abundance and Trends 

Willamette Falls

The number of winter-run steelhead passing over Willamette Falls from 1971 to 2002 is 

shown in Figure 176. All steelhead in the ESU must pass Willamette Falls. Two groups of 

winter-run steelhead currently exist in the upper Willamette River. The late winter-run steelhead 

exhibit the historical phenotype adapted to passing the seasonal barrier at Willamette Falls. The 

falls were laddered, and hatchery early winter-run steelhead fish were released above the falls. 

237 
STEELHEAD

Figure 175. Map of historical Upper Willamette River steelhead ESU populations. 

The early run fish were derived from Columbia River basin steelhead outside the 

Willamette River and are considered nonnative. The release of winter-run hatchery steelhead in 

the Willamette River was recently discontinued (Table 48), but some early winter-run steelhead 

are still returning from the earlier hatchery releases and from any natural production of the early 

run fish that has been established. Table 48 shows the combined early and late returns and only 

the native late run. Nonnative summer-run hatchery steelhead are also released into the upper 

Willamette River, but these numbers are not included on the table. The geometric mean of latereturning steelhead passing Willamette Falls over the years 1998–2002 is 5,819 steelhead; the 

arithmetic mean over the same period is 6,765 steelhead. 

238
19. UPPER WILLAMETTE RIVER STEELHEAD ESU 

0

5,000

10,000

15,000

20,000

25,000

30,000

1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total winter steelhead Late-returning steelhead (native)

Figure 176. Counts of winter-run steelhead at Willamette Falls, 1971–2002. 

Table 48. Releases of winter-run steelhead for the final years that winter-run steelhead were stocked in 

the Willamette River.*

Population Last year winter-run steelhead released 

Mollala River 1999 

North Santiam River 1998 

South Santiam River 1989 

Calapooia River No hatchery 

*

 Stocking of steelhead in the Willamette River was discontinued. However, winter-run hatchery 

fish were still returning over the period of the available time series and summer-run steelhead 

continue to be stocked in the Willamette. This table shows the last year of winter-run releases in 

each of the basins. 

The available time-series data for individual Upper Willamette River steelhead ESU 

populations consist of redd count index surveys, one dam count (Foster Dam), and one hatchery 

trap count (Minto Trap). At one time, ODFW applied an algorithm involving the redd surveys 

and the length of available stream miles to apportion the fish passing Willamette Falls into 

individual populations. This approach appears to have been dropped in 1997, and there are 

currently no estimates of the absolute total numbers of spawners in the individual populations. 

The status of individual populations is discussed below. 

Molalla 

A time series of redds-per-mile data from the Molalla River shows a declining trend from 

1980 to 2000 (Table 49 and Figure 177). Estimates of the fraction of hatchery-origin spawners 

239
STEELHEAD

Table 49. Trends in redds-per-mile surveys of Upper Willamette River ESU winter-run steelhead 

populations (95% confidence intervals are in parentheses). 

Population 

Years of 

data 

Long-term 

trenda

 in 

redds per mile 

Probability 

long-term 

trend < 1 

Short-term 

trendb

 in 

redds per mile 

Probability 

short-term 

trend < 1 

Mollala 1980–2000 0.947 

(0.918–0.977) 

0.999 0.972 

(0.867–1.090) 

0.705 

North Santiam 1980–2001 0.941 

(0.906–0.977) 

0.999 0.962 

(0.845–1.095) 

0.740 

South Santiam 1980–2001 0.936 

(0.904–0.970) 

1.000 0.917 

(0.811–1.037) 

0.926 

Calapooia 1980–2001 0.968 

(0.933–1.003) 

0.964 1.053 

(0.935–1.149) 

0.229 

a

 Long-term trends use the entire data set. 

b

 Short-term trends use data from 1990 through the most recent year. 

for this population are shown in Figure 183; the estimated harvest rate is shown in Figure 184. 

The populations show a declining trend over the available time series. 

North Santiam 

A time series of redds-per-mile data from the North Santiam River shows a declining 

trend from 1980 to 2001 (Figure 178). A time series also exists for the Minto trap on the North 

Santiam (Figure 179). Minto is a hatchery acclimation-and-release site, so it is assumed that the 

majority of fish trapped at this site over the time series are of hatchery origin. Estimates of the 

fraction of hatchery-origin spawners for this population are shown in Figure 183; the estimated 

harvest rate is shown in Figure 184. 

0

5

10

15

20

25

30

1975 1980 1985 1990 1995 2000 2005

Year

Redds per mile

Figure 177. Redd surveys of winter-run steelhead in the Molalla River, 1980–2000. 

240
19. UPPER WILLAMETTE RIVER STEELHEAD ESU 

South Santiam 

Counts of winter-run steelhead at Foster Dam (RKm 77) from 1967 to 2002 are shown in 

Figure 180. A hatchery program was initiated in the 1980s, and hatchery-origin fish were 

identified at the dam facility. Redd surveys are also conducted below Foster Dam (Figure 181). 

Estimates of the fraction of hatchery-origin spawners for this population below Foster Dam are 

shown in Figure 183; the estimated harvest rate is shown in Figure 184. 

Calapooia River 

A time series of redds-per-mile data from the Calapooia River shows a declining trend 

from 1980 to 2001 (Figure 182). Estimates of the fraction of hatchery-origin spawners for this 

population are shown in Figure 183; the estimated harvest rate is shown in Figure 184. 

West side tributaries 

No time series or current counts of spawner abundance for the west side tributaries 

population are available. It is questionable whether a self-sustaining steelhead population ever 

existed in the west side tributaries. There is assumed to be little, if any, natural production of 

steelhead in these tributaries. 

0

10

20

30

40

50

60

1975 1980 1985 1990 1995 2000 2005

Year

Redds per mile

Figure 178. Redd surveys of winter-run steelhead in the North Santiam River, 1980–2001. 

241
STEELHEAD

0

500

1,000

1,500

2,000

1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Figure 179. Counts of winter-run steelhead at the Minto Trap on the North Santiam River, 1960–2000. 

Minto Trap is a hatchery-acclimation pond and release site. 

0

1,000

2,000

3,000

4,000

1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total winter steelhead Natural-origin steelhead

Figure 180. Counts of winter-run steelhead at Foster Dam on the South Santiam River (RKm 77), 

1967–2002. 

242
19. UPPER WILLAMETTE RIVER STEELHEAD ESU 

0

5

10

15

20

25

30

35

1975 1980 1985 1990 1995 2000 2005

Year

Redds per mile

Figure 181. Redd surveys of winter-run steelhead in the South Santiam River below Foster Dam, 

 1980–2001. 

0

2

4

6

8

10

12

14

16

18

1975 1980 1985 1990 1995 2000 2005

Year

Redds per mile

Figure 182. Redd surveys of winter-run steelhead in the Calapooia River, 1980–2001. 

243
STEELHEAD

0

10

20

30

40

50

60

70

1975 1980 1985 1990 1995 2000 2005

Year

Percent spawners of hatchery origin

Molalla North Santiam South Santiam Calapooia

Figure 183. Estimates of the fraction of hatchery-origin spawners in populations of Upper Willamette 

River ESU winter-run steelhead (Chilcote 2001), 1980–2000. Winter-run steelhead are not 

currently released into the upper Willamette River. 

0

5

10

15

20

25

1970 1975 1980 1985 1990 1995 2000 2005

Year

Percent harvest

Molalla North Santiam

Foster Dam Lower South Santiam

Calapooia

Figure 184. Estimates of the harvest rate on populations of Upper Willamette River ESU winter-run 

steelhead, 1973–2000. Source: Chilcote (2001). 

244
19. UPPER WILLAMETTE RIVER STEELHEAD ESU 

Loss of Habitat from Barriers 

Steel and Sheer (2003) conducted an analysis to assess the number of stream kilometers 

historically and currently available to salmon populations in the Upper Willamette River 

steelhead ESU (Table 50). Stream kilometers usable by salmon are determined based on simple 

gradient cutoffs and on the presence of impassable barriers. This approach will overestimate the 

number of usable stream kilometers, because it does not consider habitat quality (other than 

gradient). However, the analysis does indicate that for some populations the number of stream 

habitat kilometers currently accessible is greatly reduced from the historical condition. 

Resident O. mykiss Considerations 

The available information on resident O. mykiss populations within the Upper Willamette 

River steelhead ESU is summarized Appendix B, Table B-1, which provides a broad overview of 

the distribution of case 1, 2, and 3 resident populations within the ESU. See the subsection, 

Resident Fish, in Section 1 for an explanation of the three cases and their relevance to ESU 

determinations. The subsection, Resident Fish, in Section 12, discusses how resident fish are 

considered in risk analyses. 

Kostow (2003) reviewed information on the abundance and distribution of resident 

O. mykiss for the Upper Willamette River steelhead ESU and found no quantitative estimates of 

abundance for resident O. mykiss in any upper Willamette River population. However, expert 

opinion indicates that resident O. mykiss are rare in this ESU. Cutthroat trout (O. clarki) are 

found throughout much of the Willamette River basin and tend not to co-occur with resident 

O. mykiss. Resident O. mykiss in the Middle Fork Willamette and McKenzie rivers might 

normally be considered to be case 1, because there are no obvious barriers to anadromous access 

to these areas. Nevertheless, no evidence shows steelhead historically inhabited these basins, 

Table 50. Historical populations of Upper Willamette River ESU steelhead and loss of habitat from 

barriers. 

Population 

Potential 

current 

habitat (%)a

Potential 

historical 

habitat (km)b

Current to 

historical 

habitat ratioc

Mollala River 524 827 63 

North Santiam River 210 347 61 

South Santiam River 581 856 68 

Calapooia River 203 318 64 

West side tributaries 1,376 2,053 67 

a

 The potential current habitat is the kilometers of stream below all currently impassable barriers 

between a gradient of 0.5% and 4%. b

 The potential historical habitat is the kilometers of stream below historically impassable barriers 

between a gradient of 0.5% and 6%. c

 The current:historical habitat ratio is the percent of the historical habitat that is currently available. 

245
STEELHEAD

and the resident fish in these basins are morphologically distinctive (being known locally as 

“McKenzie redsides,” Kostow 2003). These upper basin resident fish are also genetically quite 

different from Upper Willamette ESU steelhead, and they are not considered part of the Upper 

Willamette River steelhead ESU (NMFS 1999b). 

Resident or residualized rainbow trout are found above the dams on the North and South 

Santiam rivers: historically, these areas were the primary production areas for steelhead in this 

ESU. We are not aware of specific information relevant to the ESU status of these case 3 

resident populations. Resident O. mykiss are found in the numerous small waterfalls that exist in 

the headwater regions of this ESU. 

ESU Summary 

Based on the updated information provided in this report, information contained in 

previous Upper Willamette River steelhead ESU status reviews, and preliminary analyses by the 

WLC-TRT, we could not conclusively identify a single population that is naturally selfsustaining. All populations are relatively small, with the recent mean abundance of the entire 

ESU at less than 6,000. Over the period of the available time series, most of the populations 

were in decline. The recent elimination of winter-run hatchery production will allow estimation 

of the natural productivity of populations in the future, but the presence of hatchery-origin 

spawners confounds available time series. On a positive note, the counts all indicated an 

increase in abundance in 2001, likely at least in part as a result of improved marine conditions. 

The issue of changing marine conditions, which is an issue for many ESUs, is discussed in 

Section 1. 

246
20. Northern California Steelhead ESU

Summary of Previous BRT Conclusions 

The Northern California steelhead ESU inhabits coastal basins from Redwood Creek 

(Humboldt County) southward to the Gualala River (Mendocino County) (Busby et al. 1996). 

Within this ESU, both summer run,19 winter run, and half-pounders20 have been found. 

Summer-run steelhead are found in the Mad, Eel, and Redwood rivers; the Middle Fork Eel 

River population is their southernmost occurrence. Half-pounders are found in the Mad and Eel 

rivers. Busby et al. (1996) argued that when summer- and winter-run steelhead co-occur within 

a basin, they were more similar to each other than either is to the corresponding run type in other 

basins. Thus, Busby et al. (1996) considered summer- and winter-run steelhead to comprise a 

single ESU. 

Listing status: Threatened. 

Summary of Major Risks and Status Indicators 

Risks and limiting factors 

The previous status review (Busby et al. 1996) identified two major barriers to fish 

passage: Mathews Dam on the Mad River and Scott Dam on the Eel River. Numerous other 

blockages on tributaries were also thought to occur. Poor forest practices and poor land use 

practices, combined with catastrophic flooding in 1964, were thought to have caused significant 

declines in habitat quality that persisted up to the date of the status review. These effects include 

sedimentation and loss of spawning gravels. Nonnative Sacramento pikeminnow (Ptychocheilus 

grandis) had been observed in the Eel River basin and could be acting as predators on juvenile 

steelhead, depending on thermal conditions leading to niche overlap of the two species (see also 

Brown and Moyle 1981 and 1997, Harvey et al. 2002, Reese and Harvey 2002). 

Status indicators 

Historical estimates (pre-1960s) of steelhead abundance for the Northern California 

steelhead ESU are few (Table 51). The only time-series data are dam counts of winter-run 

steelhead in the upper Eel River (Cape Horn Dam, 1933–1975), winter-run steelhead in the Mad 

 

19 Some researchers consider summer- and fall-run steelhead to be separate runs within a river, while others do not 

consider these groups to be different. For this review, summer and fall run are considered stream-maturing 

steelhead and will be referred to as summer-run steelhead (see McEwan 2001b for additional details). 

20 A half-pounder is a sexually immature, usually small steelhead that returns to freshwater after spending less than a 

year in the ocean (Kesner and Barnhart 1972, Everest 1973). 

247 
STEELHEAD

Table 51. Summary of historical abundance (average counts) for steelhead in the Northern California 

steelhead ESU (see also Figure 185). 

Average count 

Basin Site 1930s 1940s 1950s 1960s 1970s 1980s Reference 

Eel River Cape Horn Dam 4,390 4,320 3,597 917 721 1,287 Grass (1995b) 

Eel River Benbow Dam 13,736 18,285 12,802 6,676 3,355 – 

Mad River Sweasy Dam 3,167 4,720 2,894 1,985 – – 

River (Sweasy Dam, 1938–1963), and combined counts of summer- and winter-run steelhead in 

the South Fork Eel River (Benbow Dam, 1938–1975; see Figure 185a). More recent data are 

snorkel counts of summer-run steelhead made in the middle fork of the Eel River since 1966 

(with some gaps in the time series).21 Some “point” estimates of mean abundance exist—in 

1963, CDFG estimated steelhead abundance for many rivers in the ESU (Table 52). CDFG 

attempted to estimate a mean count over the interval 1959 to 1963, but in most cases 5 years of 

data were not available, and estimates were based on fewer years (CDFG 1965); the authors state 

that “estimates given here which are based on little or no data should be used only in outlining 

the major and critical factors of the resource” (CDFG 1965). The previous BRT (Busby et al. 

1996) considered the above data sets in making their risk assessment. 

Although the data were relatively few, the data that did exist suggested the following to 

the BRT: 1) population abundances were low relative to historical estimates (1930s dam counts; 

see Table 51, and Figure 185); 2) recent trends were downward (except for a few small summerrun stocks; see Figures 185 and 186); and 3) summer-run steelhead abundance was “very low.” 

The BRT was also concerned about negative influences of hatchery stocks, especially in the Mad 

River (Busby et al. 1996). Finally, the BRT noted that the status review included two major 

sources of uncertainty: lack of data on run sizes throughout the ESU and the genetic heritage of 

winter-run steelhead in the Mad River. 

Listing Status 

Status was formally assessed in 1996 (Busby et al. 1996), updated in 1997 (NMFS 

1997b), and updated again in 2000 (Adams 2000). Although other steelhead ESUs were listed as 

threatened or endangered in August 1997, NMFS allowed steelhead in the Northern California 

steelhead ESU to remain a candidate species pending an evaluation of state and federal 

conservation measures. A “North Coast Steelhead Memorandum of Agreement” (MOA) with 

the State of California listed a number of proposed actions, including a change in harvest 

regulations, a review of California hatchery practices, implementation of habitat restoration 

activities, implementation of a comprehensive monitoring program, and numerous revisions to 

rules on forest practices. These revisions would be expected to improve forest condition on nonfederal lands. In March 1998, NMFS announced its intention to reconsider the previous 

 

21 S. Harris and W. Jones, California Department of Fish and Game, Willits, CA. Pers. commun., 20 September 

2002. 

248
20. NORTHERN CALIFORNIA STEELHEAD ESU 

Year

1940 1960 1980 2000 2020

Adult Returns

0

5000

10000

15000

20000

25000

30000

South Fork Eel (Winter)

Year

1940 1960 1980 2000 2020

Adult Returns

0

500

1000

1500

2000

Middle Fork Eel

(Summer)

Mad 

(Summer)

Mad (Winter)

Year

1940 1960 1980 2000 2020

Adult Returns

0

20

40

60

80

100

Freshwater Crk.

(Winter)

Redwood Crk.

(Summer)

A) Historic Winter Runs

B) Summer Runs (excl. Redwood Creek)

C) Small Runs - Redwood and Freshwater Creeks

Figure 185. Time-series data for the Northern California steelhead ESU: a. historical data from winter 

runs on the Mad River and South Fork Eel River; b. summer run on the Middle Fork Eel and Mad 

Rivers; c. summer-run steelhead in Redwood Creek, and winter-run steelhead in Freshwater 

Creek, Humboldt County. Data from 1982, 1984–1986, and 1989 represent minimum estimates. 

Note the three different scales of the y axes. 

249
STEELHEAD

Table 52. Historical estimates (1963) of number of spawning steelhead for rivers in the Northern 

California steelhead ESU. Source: Data from CDFG (1965). 

Stream Estimate*

Redwood Creek 10,000 

Mad River 6,000 

Eel River (total) 82,000 

Eel River (10,000) 

Van Duzen River (Eel) (10,000) 

South Fork Eel River (34,000) 

North Fork Eel River (5,000) 

Middle Fork Eel River (23,000) 

Mattole River 12,000 

Ten Mile River 9,000 

Noyo River 8,000 

Big River 12,000 

Navarro River 16,000 

Garcia River 4,000 

Gualala River 16,000 

Other Humboldt County streams 3,000 

Other Mendocino County streams 20,000 

Total 198,000 

*

 Estimates are considered by CDFG (1965) to be notably uncertain. 

no-listing decision. On 6 October 1999, the California Board of Forestry failed to take action on 

the forest practices rules, and the NMFS Southwest Region (SWR) regarded this failure as a 

breach of the MOA, despite the fact that other state agencies, such as the CDFG, had complied 

with the MOA. The Northern California steelhead ESU was listed as threatened in June 2000. 

New Data and Updated Analyses 

There are four significant sets of new information regarding status: 

1. Updated time-series data exist for the Middle Fork Eel River (summer-run steelhead, 

snorkel counts; see Figure 185b). 

2. New data collection efforts were initiated in 1994 in the Mad River (summer-run 

steelhead, snorkel counts; Figure 185b) and in Freshwater Creek (winter-run steelhead, 

weir counts; Figure 185c), a small stream emptying into Humboldt Bay. 

3. Numerous reach-scale estimates of juvenile abundance have been made extensively 

throughout the ESU. 

4. Harvest regulations have been substantially changed since the last status review. 

Analyses of this information are described below. 

250
20. NORTHERN CALIFORNIA STEELHEAD ESU 

Abundance

0 1000 2000 3000 4000

Long-Term Trend

-0.4

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

0.4

Freshwater

Creek (winter)

MF Eel 

(summer)

Mad

(summer)

Mad (winter)

(Sweasy Dam

historic counts,

1938 - 1963)

SF Eel (winter)

(Benbow Dam 

historic counts,

1938 - 1975)

Figure 186. Trends versus abundance for the time-series data from Figure 185. Note that neither set of 

dam counts (Sweasy Dam, Benbow Dam) has any recent data. Vertical bars are 95% confidence 

intervals. 

Updated Eel River Data 

The time-series data for the Middle Fork Eel River are snorkel counts of summer-run 

steelhead, made for fish in the holding pools of the entire main stem of the middle fork.22 Most 

adults in the system are thought to oversummer in these holding pools. An estimate of λ over the 

interval 1966 to 2002 was made using the method of Lindley (2003), a random-walk-with-drift 

model fitted using Bayesian assumptions. The estimate of λ is 0.98, with a 95% confidence 

interval of (0.93, 1.04) (Table 53).23 The overall trend in the data is downward in both the long 

and short term (Figure 185b). 

New Time Series 

The Mad River time series consists of snorkel counts for much of the main stem below 

Ruth Dam. Some counts include the entire main stem; other years include only data from land 

owned by Simpson Timber Company. In the years with data from the entire main stem, fish 

from Simpson Timber land make up at least 90% of the total count. The time series from 

Freshwater Creek is composed of weir counts. Estimates of λ were not made for either time 

series because there were too few years of data to make meaningful estimates. 

 

22See Footnote 21. 

23Note that Lindley (2003) defines λ ≈ exp(μ + σ2/2), whereas Holmes (2001) defines λ ≈ exp(μ); see Lindley (2003) 

for meaning of the symbols. 

251
STEELHEAD

Vital statistics for these and other existing time series are given in Table 53; trend versus 

abundance is plotted in Figure 186. 

Juvenile Data 

Data on juvenile abundance were collected at numerous sites using a variety of 

methods.24 Many of the methods involve selection of reaches thought to be “typical” or 

“representative” steelhead habitat; other reaches were selected because they were thought to be 

typical coho habitat, and steelhead counts were made incidental to coho counts. In general, the 

field crew made electro-fishing counts (usually multiple-pass, depletion estimates) of the youngof-the-year and 1+ age classes. Most of the target reaches were sampled several years in a row; 

thus there are a large number of short time series. Although methods were always consistent 

within a time series, they were not necessarily consistent across time series. 

Because there are so few adult data on which to base a risk assessment of this ESU, we 

chose to analyze these juvenile data. However, we note that they have limited usefulness for 

understanding the status of the adult population, due to nonrandom sampling of reaches within 

stream systems, nonrandom sampling of populations within the ESU, and a general lack of 

estimators shown to be robust for estimating fish density within a reach. In addition, even if the 

BRT used more rigorous methods, there is no simple relationship between juvenile and adult 

numbers (Shea and Mangel 2001), the latter being the usual currency for status reviews. Table 

54 describes the possible ways that one might translate juvenile trends into inferences about adult 

trends. 

To estimate a trend from the juvenile data, the data within each time series were logtransformed then normalized, so that each datum represented a deviation from the mean of that 

specific time series. The normalization is intended to prevent spurious trends that could arise 

from the diverse methods used to collect the data. Then, the time series were grouped into units 

thought to plausibly represent independent populations; the grouping was based on watershed 

structure. Finally, within each population a linear regression was done for the mean deviation 

versus year. The estimator for time trend within each grouping is the slope of the regression line. 

The minimum number of observations per time series is 6 years (other assessments in this status 

review place the cutoff at 10 years). The general lack of data on the Northern California 

steelhead ESU prompted us to consider these data sets despite their brevity. This procedure 

resulted in 10 independent populations for which a trend was estimated. Both upward and 

downward trends were observed (Figure 187). We tested the null hypothesis that abundances 

were stable or increasing. It was not rejected (H0: slope >0; p < 0.32 via one-tailed t-test against 

expected value). However, it is important to note that a significance level of 0.32 implies a 

probability of 0.32 that the ESU is stable or increasing, and a probability of 1 – 0.32 = 0.68 that 

the ESU is declining; thus the odds are more than 2:1 that the ESU has been declining during the

past 6 years. This conclusion requires the assumption that the assessed populations 1) are indeed 

 

24See Appendix B, Table B-4, for a list of streams and reference information.

252
Table 53. Summary of time-series data for the Northern California steelhead ESU. 

5-year meana

Population Time series Record Minimum Maximum

λb

Long-term trend 

(95% confidence 

interval) 

Middle Fork Eel River summer 

run 

1966–2002 418 384 1,246 0.98 (0.93, 1.04) –0.006 (–0.029, 0.017) 

Mad River summer run 1994–2002 162 162 384 Insufficient data –0.176 (–0.341, –0.012) 

Freshwater Creek winter run 1994–2001 32 25 32 Insufficient data 0.099 (–0.289, 0.489) Redwood Creek summer run 1981–2002 3 Figure 186c Insufficient data See Figure 185 

South Fork Eel River winter 

rund 1938–1975 – 2,743 20,657 0.98 (0.92, 1.02) –0.060 (–0.077, –0.043) 

Mad River winter rune 1938–1963 – 1,140 5,438 1.00 (0.93, 1.05) –0.053 (–0.102, –0.005) 

a Geometric means. The value 0.5 was used for years in which the count was 0. b Lambda was calculated using the method of Lindley (2003). Note that a population with 

λ greater than 1.0 can nevertheless be declin

stochasticity. 

c Certain years have minimum run sizes, rather than unbiased estimates of run size, rendering the time series unsuitable for some of the d Historical counts made at Benbow Dam (see Appendix A, Table A-2). e Historical counts made at Sweasy Dam (see Appendix A, Table A-2).

253
Table 54. Interpretation of data on juvenile trends for Northern California steelhead ESU. 

Inference made about adult trends 

Increasing Level Decreasing 

Increasing Possible, if no 

density dependence 

in the smolt/oceanic 

phase. The most 

parsimonious 

inference. 

Possible, if density 

dependence occurs in 

the juvenile overwintering phase, or in 

the smolt/oceanic 

phase. 

Possible, if oceanic 

conditions are 

deteriorating 

markedly at the same 

time that reproductive 

success per female is 

improving. 

Observed 

juvenile 

trends 

Level Possible, if oceanic 

conditions are 

improving for adults, 

but juveniles undergo 

density dependence. 

Possible. The most 

parsimonious 

inference. 

Possible, if oceanic 

conditions are 

deteriorating. 

Decreasing Unlikely, but could 

happen over the short 

term due to scramble 

competition at the 

spawning/redd 

phases. 

Possible, if river 

habitat is 

deteriorating and 

there was strong, preexisting density 

dependence in the 

oceanic phase. 

Likely. The most 

parsimonious 

inference. 

independent populations rather than plausibly independent populations, and 2) were randomly 

sampled from all populations in the ESU (in fact they were “haphazardly” sampled). 

Possible Changes in Harvest Impacts 

Since the original status review of Busby et al. (1996), regulations concerning sport 

fishing have been changed in a way that probably reduces extinction risk for the ESU. The 

CDFG (2002a) has prohibited sport harvest in the ocean, and ocean harvest is a rare event,25 so 

effects on extinction risk are negligible. For freshwaters (CDFG 2002b), all streams are closed 

to fishing year round except for special listed streams as follows: Catch-and-release angling is 

allowed year round excluding April and May in the lower main stem of many coastal streams. 

Most of these have a bag limit of one hatchery trout or steelhead during the winter months 

(Albion River, Alder Creek, Big River, Cottoneva Creek, Elk Creek, Elk River, Freshwater 

Creek, Garcia River, Greenwood Creek, Little River in Humboldt County, Gualala River, 

Navarro River, Noyo River, Ten Mile River, and Usal Creek); in a few, the one-fish bag limit 

extends to the entire season (Bear River and Redwood Creek in Humboldt County). The Mattole 

River has a slightly more restricted catch-and-release season, with zero bag limit year round. 

 

25M. Mohr, Southwest Fisheries Science Center, Santa Cruz, CA. Pers. commun., 15 October 2002.

254
20. NORTHERN CALIFORNIA STEELHEAD ESU 

Trend

(slope of regression line)

-0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4

Number of populations

0

1

2

3

4

5

Pr[mean trend > 0] = 0.32

(t-test)

Figure 187. Distribution of trends in juvenile density for 10 independent populations within the Northern 

California steelhead ESU (see text for description of methods). Trend is measured as the slope of 

a regression line through a time series; values less than 0 indicate decline; values greater than 0 

indicate increase. Assuming that the populations were randomly drawn from the ESU as a whole, 

the hypothesis that the ESU is stable or increasing cannot be statistically rejected (p = 0.32), but 

is only half as likely as the hypothesis that the ESU is declining (p = 1 – 0.32 = 0.68). 

The two largest systems are the Mad and Eel rivers. The mainstem Mad River is open 

over a very long stretch, except for April and May. Bag limit is two hatchery trout or steelhead; 

other stretches have zero bag limit or are closed to fishing. Above Ruth Dam, an impassable 

barrier, the bag limit is five trout per day. The Eel River’s main stem and south fork are open to 

catch-and-release over large stretches, year round in some areas and closed April and May in 

others. The Middle Fork Eel River is open for catch-and-release except midsummer and late 

fall/winter. In the upper middle fork and many of its tributaries, summer fisheries have bag 

limits of two or five, with no stipulated restriction on hatchery or wild. In the Van Duzen, a 

major tributary of the mainstem Eel, a summer fishery allows a bag limit of five above Eaton 

Falls (CDFG 2002b). Elsewhere, some summer trout fishing is allowed, generally with a two or 

five bag limit. Cutthroat trout have a bag limit of two from a few coastal lagoons or estuaries. 

At catch-and-release streams, all wild steelhead must be released unharmed. There are 

significant restrictions on gear used for angling. The CDFG monitors angling effort and catchper-unit-effort in selected basins by way of a “report card” system, in which sport anglers selfreport their catch, gear used, and so forth, and in selected other basins by way of creel censuses. 

Although the closure of many areas and institution of catch-and-release elsewhere is 

expected to reduce extinction risk for the ESU, this risk reduction cannot be estimated with 

existing data (due to the fact that natural abundance is not being estimated). After the federal 

listing decisions, NMFS requested that CDFG prepare a Fishery Management and Evaluation 

Plan for the listed steelhead ESUs in California. This has not yet been done for the Northern 

California steelhead ESU. 

255
STEELHEAD

Resident O. mykiss Considerations 

Resident (nonanadromous) populations of O. mykiss were assigned to one of three 

categories for the purpose of provisionally determining ESU membership (see subsection, 

Resident Fish, in Section 1, Introduction, for a description of the three categories and default 

assumptions about ESU membership). The third category consists of resident populations that 

are separated from anadromous conspecifics by recent man-made barriers such as dams without 

fish ladders. No default assumption about ESU membership was possible for case 3 populations, 

so we consider them here case by case according to available information.

As of this writing few data show an occurrence of resident populations and even fewer 

genetic relationships. A provisional survey of the occurrence of case 3 populations in the 

Northern California steelhead ESU (see Appendix, B, Table B-2) revealed the following: In the 

watersheds inhabited by this ESU, 8% of stream kilometers lie behind two major recent 

barriers—Scott Dam on the Eel River and Robert Matthews Dam on the Mad River (Appendix 

B, Table B-2). (Major barriers are defined as blocking access to watersheds with areas of 259 sq. 

km [100 sq. mi.] or greater.) Case 3 populations are documented to occur above both dams and 

there is ongoing stocking of hatchery fish in the Mad River above the dam. No such records of 

stocking were uncovered for the Eel River above Scott Dam. There do not appear to be any 

relevant genetic studies of these case 3 populations. 

New Hatchery Information 

California hatchery stocks being considered for inclusion in the Northern California 

steelhead ESU are those from Mad River Hatchery, Yager Creek Hatchery, and the North Fork 

Gualala River Steelhead Project. The stocks and their associated hatcheries were assigned to one 

of three categories for the purpose of determining ESU membership at some future date (see 

subsection, Artificial Propagation, in Section 1 for a description of the three categories and 

related issues regarding ESU membership). To make the assignments, data about broodstock 

origin, size, management, and genetics were gathered from fisheries biologists and are 

summarized below. 

Mad River Hatchery (Mad River Steelhead, CDFG) 

The Mad River Hatchery is located 20 km upriver near the town of Blue Lake (CDFG 

and NMFS 2001). The trap is located at the hatchery. 

Broodstock origin and history 

The hatchery was opened in 1970 and first released steelhead in 1971. The original 

steelhead releases were from adults taken at Benbow Dam on the South Fork Eel River. 

Between 1972 and 1974, broodstock at Mad River Hatchery were composed almost exclusively 

of steelhead from the South Fork Eel River. After 1974 returns to the hatchery supplied about 

90% of the egg take; other eggs originated from Eel River steelhead. In addition, at least 500 

adult steelhead from the San Lorenzo River were spawned at Mad River Hatchery in 1972. 

Progeny of these fish may have been planted in the basin. All subsequent broodyears are 

reported to have come from trapping at the hatchery. 

256
20. NORTHERN CALIFORNIA STEELHEAD ESU 

Broodstock size/natural population size 

An average of 5,536 adults were trapped from 1991 to 2002 and an average of 178 

females were spawned during the broodyears from 1991 to 2002. There are no abundance 

estimates for the Mad River, but steelhead were observed to be widespread and abundant 

throughout the basin. 

Management 

Starting in 1998, steelhead are 100% marked, and fish are included in the broodstock in 

proportion to the numbers returned. The current production goals are 250,000 yearlings raised to 

4 to 8 lb for release in March to May. 

Population genetics 

Allozyme data group Mad River samples with the Mad River Hatchery and then with the 

Eel River (Busby et al. 1996). 

Category

The hatchery has been determined to belong in case 3. There have been no introductions 

since 1974, and naturally spawned fish are being included in the broodstock. However, there is 

still an out-of-basin nature to the stock (SSHAG 2003; see Appendix B, Table B-3). 

Yager Creek Hatchery 

(Yager Creek Steelhead [Pacific Lumber Company]) 

The Yager Creek trapping and rearing facility is located at the confluence of Yager and 

Cooper Mill creeks (tributaries of the Van Duzen River, which is a tributary of the Eel River). 

Broodstock origin and history

The project was initiated in 1976. Adult broodstock are taken from Yager Creek, and 

juveniles are released in the Van Duzen River basin. As with all cooperative hatcheries, the fish 

are all marked, and hatchery fish are usually excluded from broodstock (unless wild fish are 

rare). There are no records of introductions to the broodstock. 

Management 

About 4,600 juvenile steelhead from Freshwater Creek (a tributary of Humboldt Bay) 

were released in the Yager Creek basin in 1993 (Busby et al. 1996). The current program goal is 

the restoration of Van Duzen River steelhead. 

Population genetics

There are no genetic data for this hatchery. 

257
STEELHEAD

Category

This hatchery was determined to belong to case 1. The broodstock has had no out-ofbasin introductions, and hatchery fish are excluded from the broodstock (SSHAG 2003; see 

Appendix B, Table B-3). 

North Fork Gualala River Hatchery 

(Gualala River Steelhead Project, CDFG) 

This project rears juvenile steelhead rescued from tributaries of the North Fork Gualala 

River. Rearing facilities are located on Doty Creek, a tributary of the Gualala River 12 miles 

from the mouth. Steelhead smolts resulting from this program are released in Doty Creek, the 

main stem of the Gualala River, and other locations in the drainage.

Broodstock origin and history

The project was started in 1981 and has operated sporadically since then. Juvenile 

steelhead are rescued from the North Fork Gualala River and reared at Doty Creek. 

Management 

The current program goal is restoration of Gualala River steelhead. 

Population genetics

There are no genetic data for this hatchery. 

Category

This hatchery was determined to belong to case 1. Usually only naturally spawned 

juveniles are reared at the facility (SSHAG 2003; see Appendix B, Table B-3). 

258
21. Central California Coast Steelhead ESU 

Summary of Previous BRT Conclusions 

The Central California Coast steelhead ESU was determined to inhabit coastal basins 

from the Russian River (Sonoma County) to Soquel Creek (Santa Cruz County) inclusive (Busby 

et al. 1996). Also included in this ESU are populations inhabiting tributaries of San Francisco 

and San Pablo bays (though there is some uncertainty about the latter). The ESU is composed 

only of winter-run fish. 

Listing status: Threatened. 

Summary of Major Risks and Status Indicators 

Risks and limiting factors 

Busby et al. (1996) reported two significant habitat blockages: the Coyote and Warm 

Springs dams in the Russian River watershed. Data indicated that other smaller fish passage 

problems were widespread in the geographic range of the ESU. Other impacts noted in the status 

report were urbanization and poor land-use practices, catastrophic flooding in 1964 causing 

habitat degradation, and dewatering due to irrigation and diversion. The relative strengths of 

these various impacts has not been formally analyzed. Principal hatchery production in the 

region comes from the Warm Springs Hatchery on the Russian River and the Monterey Bay 

Salmon and Trout Project on a tributary of Scott Creek. At the time of the status review, other 

small private programs were producing steelhead in the range of the ESU and, as reported by 

Bryant (1994), were using stocks indigenous to the ESU, but not necessarily to the particular 

basin in which the program was located. There was no information on the actual contribution of 

hatchery fish to naturally spawning populations. 

Status indicators 

Busby et al. (1996) reported one estimate of historical (pre-1960s) abundance: 

Shapovalov and Taft (1954) described an average of about 500 adults in Waddell Creek (Santa 

Cruz County) for the 1930s and early 1940s. A bit more recently, Johnson (1964) estimated a 

run size of 20,000 steelhead in the San Lorenzo River before 1965, and CDFG (1965) estimated 

an average run size of 94,000 steelhead for the entire ESU, for the period 1959–1963 (see Table 

55 for a breakdown of numbers by basin). The analysis by CDFG (1965) was compromised by 

the fact that, for many basins, the data did not exist for the full 5-year period of their analysis. 

The authors of CDFG (1965) state that “estimates given here which are based on little or no data 

should be used only in outlining the major and critical factors of the resource.” 

259
STEELHEAD

Table 55. Summary of estimated run sizes for the Central California Coast steelhead ESU. Source: 

Reproduced from Busby et al. (1996), Tables 19 and 20. 

River basin Run size estimate Year Reference 

Russian River 65,000 1970 CACSS (1988) 

1,750–7,000 1994 McEwan and Jackson (1996), CDFG 

(1994a) 

Lagunitas Creek 500 CDFG (1994a) 

400–500 1990s McEwan and Jackson (1996) 

San Gregorio 1,000 1973 Coots (1973) 

Waddell Creek 481 1933–1942 Shapovolov and Taft (1954) 

250 1982 Shuman (1994)*

150 1994 Shuman (1994)*

Scott Creek 400 1991 Nelson (1994) 

<100 1991 Reavis (1991) 

300 1994 Titus et al. (2002) 

150 1982 Shuman (1994)* San Vicente Creek 

50 1994 Shuman (1994)*

San Lorenzo River 20,000 Pre-1965 Johnson (1964), SWRCB (1982) 

1,614 1977 CDFG (1982) 

>3,000 1978 Ricker and Butler (1979) 

600 1979 CDFG (1982) 

3,000 1982 Shuman (1994)*

 

“few” 1991 Reavis (1991) 

<150 1994 Shuman (1994)*

Soquel Creek 500–800 1982 Shuman (1994)*

<100 1991 Reavis (1991) 

50–100 1994 Shuman (1994)*

 

Aptos Creek 200 1982 Shuman (1994)*

<100 1991 Reavis (1991) 

50–75 1994 Shuman (1994)*

*

 The basis for the estimates provided by Shuman (1994) appears to be questionable. 

Recent data for the Russian and San Lorenzo rivers (Reavis 1991, CDFG 1994a, Shuman 

1994; see Table 55) suggested that these basins had populations smaller than 15% of their size 

30 years earlier. These two basins were thought to have originally contained the two largest 

steelhead populations in the Central California steelhead ESU. 

A status review update in 1997 (NMFS 1997b) concluded that slight increases in 

abundance occurred in the 3 years following the status review. However, the analyses on which 

these conclusions were based had various problems, including inability to distinguish hatchery 

and wild fish, unjustified expansion factors, and variance in sampling efficiency on the San 

Lorenzo River. Presence-absence data compiled by P. Adams26 indicated that most (82%) 

 

26P. Adams, Southwest Fisheries Science Center, Santa Cruz, CA. Pers. commun., 17 October 2002. 

260
21. CENTRAL CALIFORNIA COAST STEELHEAD ESU 

sampled streams (a subset of all historical steelhead streams) had extant populations of juvenile 

O. mykiss. 

Previous BRT Conclusions 

The original BRT concluded that the ESU was in danger of extinction (Busby et al. 

1996). The BRT considered extirpation especially likely in Santa Cruz County and in the 

tributaries to San Pablo and San Francisco bays. The BRT suggested that abundance in the 

Russian River (the largest system inhabited by the ESU) has declined sevenfold since the mid1960s, but abundance appeared to be stable in smaller systems. Two major sources of 

uncertainty were 1) few data on run sizes, which necessitated that the listing be based on indirect 

evidence, such as habitat degradation; and 2) uncertainty regarding genetic heritage of 

populations in tributaries to San Francisco and San Pablo bays, causing uncertainty in the 

delineation of the geographic boundaries of the ESU. A status review update (NMFS 1997b) 

concluded that conditions had improved slightly, and that the ESU was not presently in danger of 

extinction but was likely to become so in the foreseeable future. (Minorities supported both more 

and less extreme views on extinction risk.) Uncertainties in the update mainly revolved around 

sampling efforts that were inadequate for detecting status or trends of populations inhabiting 

various basins.

The BRT formally assessed the status of steelhead in 1996 (Busby et al. 1996). NMFS 

updated the original status review in 1997 (NMFS 1997b) and listed the Central California Coast 

steelhead ESU as threatened in August 1997. 

New Data and Updated Analyses 

There are two significant sets of new information regarding status: 1) numerous reachscale estimates of juvenile abundance have been made for populations of the ESU, and 2) harvest 

regulations have been substantially changed since the last status review. Analyses of this 

information are described below. 

Juvenile Data 

Data on juvenile abundance have been collected at a number of sites using a variety of 

methods (D. W. Alley & Associates 1994, 1995, 1997, 1998, 1999, 2000, 2002a, 2002b; Smith 

1992, 1994a, 1994b, 1994c, 1996a, 1996b, 1996c, 1997, 1998a, 1998b, 1998c, 1999, 2000a, 

2000b, 2001a, 2001b, 2002). Many of the methods involve the selection of reaches thought to be 

“typical” or “representative” steelhead habitat. In general, the field crew made electro-fishing 

counts (usually multiple-pass, depletion estimates) of the young-of-the-year and 1+ age classes. 

Most of the target reaches were sampled several years in a row; thus there are a large number of 

short time series. Although methods were always consistent within a time series, they were not 

necessarily consistent across time series. 

Because there are so few adult data on which to base a risk assessment of this ESU, we 

chose to analyze these juvenile data. However, we note that they have limited usefulness for 

understanding the status of the adult population, due to nonrandom sampling of reaches within 

stream systems, nonrandom sampling of populations within the ESU, and a general lack of 

261
STEELHEAD

estimators shown to be robust for estimating fish density within a reach. In addition, even if 

more rigorous methods had been used, there is no simple relationship between juvenile numbers 

and adult numbers (Shea and Mangel 2001), the latter being the usual currency for status 

reviews. Table 54 describes the various possible ways that one might translate juvenile trends 

into inferences about adult trends. 

To estimate a trend in the juvenile data, the data within each time series were logtransformed and then normalized, so that each datum represented a deviation from the mean of 

that specific time series. The normalization is intended to prevent spurious trends that could 

arise from the diverse set of methods used to collect the data. Then, the time series were grouped 

into units thought to plausibly represent independent populations; the grouping was based on 

watershed structure. Finally, within each population, a linear regression was done for the mean 

deviation versus year. The estimator for time trend within each grouping is the slope of the 

regression line. The minimum number of observations per time series is 6 years (other 

assessments in this status review place the cutoff at 10 years). The general lack of data on the 

Central California Coast steelhead ESU prompted us to consider these data despite the brevity of 

some series. 

This procedure resulted in five independent populations for which a trend was estimated: 

the San Lorenzo River, Scott Creek, Waddell Creek, Gazos Creek, and Redwood Creek in Marin 

County. Only downward trends were observed in the five populations (Figure 188). The mean 

trend across all populations was significantly less than 0 (H0: slope > 0; p < 0.022 via one-tailed 

t-test against expected value). This outcome suggests an overall decline in juvenile abundance, 

but it is important to note that such a conclusion requires the assumptions that the assessed 

populations 1) are indeed independent populations rather than plausibly independent populations, 

and 2) were randomly sampled from all populations in the ESU (they are probably better 

regarded as having been haphazardly sampled). 

Possible Changes in Harvest Impacts 

Since the original status review of Busby et al. (1996), regulations concerning sport 

fishing have been changed in a way that probably reduces extinction risk for the ESU. The 

CDFG has prohibited sport harvest in the ocean (2002a), and ocean harvest is a rare event.27 For 

freshwaters (CDFG 2002b), all coastal streams are closed to fishing year round, except for 

special listed streams that allow catch-and-release angling or summer trout fishing. Catch-andrelease angling with restricted timing (generally, winter season Sundays, Saturdays, 

Wednesdays, and holidays) is allowed in the lower main stems of many coastal streams south of 

San Francisco (Aptos Creek, Butano Creek, Pescadero Creek, San Gregorio Creek, San Lorenzo 

River, Scott Creek, Soquel Creek). Notably, for a while Waddell Creek in Santa Cruz County 

had a five-per-day bag limit during the winter, for the short reach between Highway 1 and the 

ocean. This bag limit was reduced to zero in the supplementary regulations issued in a separate 

document (CDFG 2002b). Catch-and-release is allowed year round, except April and May, in 

the lower parts of Salmon Creek in Sonoma County and Walker Creek in Marin County. 

 

27See Footnote 25. 

262
21. CENTRAL CALIFORNIA COAST STEELHEAD ESU 

Trend

(slope of regression line)

-0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4

Number of populations

0

1

2

3

4

5

Pr[mean trend > 0] = 0.022

(t-test)

Figure 188. Distribution of trends in juvenile densities for five independent populations within the 

Central California Coast steelhead ESU (see text for description of methods). Trend is measured 

as the slope of a regression line through a time series; values less than 0 indicate decline; values 

greater than 0 indicate increase. Assuming that the populations were randomly drawn from the 

ESU as a whole, the hypothesis that the ESU is stable or increasing can be statistically rejected 

(p = 0.022), implying an overall decline. 

Russian Gulch in Sonoma County has similar regulations except that one hatchery fish may be 

taken in the winter. 

The Russian River is the largest system and probably originally supported the largest 

steelhead population in the Central California Coast steelhead ESU. The main stem is currently 

open all year and has a bag limit of two hatchery steelhead or trout. Above the confluence with 

the East Branch it is closed year round. Santa Rosa Creek and Laguna Santa Rosa, Sonoma 

County tributaries to the Russian River, have a summer catch-and-release fishery. 

Tributaries to the San Francisco Bay system have less restricted fisheries. All streams in 

Alameda, Contra Costa, and Santa Clara counties (east and south bay) have summer fisheries 

with a bag limit of five, except for special cases that are closed all year (Mitchell Creek, 

Redwood Creek in Alameda County, San Francisquito Creek and tributaries, and Wildcat 

Creek). In the north Bay, the lower main stem of the Napa River has catch-and-release year 

round except April and May; there is a bag limit of one hatchery steelhead or trout. Upper 

Sonoma Creek and tributaries have a summer fishery with bag limit of five. Summer trout 

fishing is allowed in some lakes and reservoirs or in tributaries to lakes, generally with two or 

five bag limit. 

For catch-and-release streams, all wild steelhead must be released unharmed. There are 

significant restrictions on gear used for angling. The CDFG has prepared a draft Fishery 

263
STEELHEAD

Management and Evaluation Plan (CDFG 2001c), which argues that the upper limit of increased 

mortality due to sport fishing is about 2.5% in all populations. This estimate is based on an 

estimated mortality rate of 5% once a fish is hooked, which is consistent with a published 

metaanalysis of hooking mortality (Schill and Scarpella 1997). Experimental studies on the 

subject—from which the estimates are made—tend to measure mortality only for a period of a 

few days or a week after capture (e.g., Titus and Vanicek 1988). 

The Fishery Management and Evaluation Plan contains no extensive plans for monitoring 

fish abundance. Although the closure of many areas and institution of catch-and-release 

elsewhere is expected to reduce extinction risk for the ESU, this risk reduction cannot be 

estimated quantitatively from the existing data sets, due to the fact that natural abundance is not 

being measured. 

Resident O. mykiss Considerations 

Resident (nonanadromous) populations of O. mykiss were assigned to one of three 

categories for the purpose of provisionally determining ESU membership (see subsection, 

Resident Fish, in Section 1 for a description of the three categories and default assumptions 

about ESU membership). The third category consists of resident populations that are separated 

from anadromous conspecifics by recent man-made barriers such as dams without fish ladders. 

No default assumption about ESU membership was possible for case 3 populations, so the BRT 

considers them case by case according to available information. 

As of this writing few data show an occurrence of resident populations and even fewer 

genetic relationships. A provisional survey of the occurrence of case 3 populations in the Central 

California Coast steelhead ESU (see Appendix B, Table B-2) revealed the following: In the 

watersheds inhabited by this ESU, at least 26% of stream kilometers lie behind recent barriers, 

and a number of resident populations are known to occur above the barriers (Appendix B, Table 

B-2). One significant set of case 3 populations is in Alameda Creek, a tributary to San Francisco 

Bay. Nielsen (2003) examined mitochondrial DNA and microsatellite DNA of fish from four 

subbasins of Alameda Creek and found that three of the subpopulations were most similar to 

each other and were more similar to populations from other creeks within the ESU (Lagunitas 

and San Francisquito creeks) than they were to populations outside the ESU. This finding 

strongly suggests that these case 3 subpopulations should be considered part of the ESU. The 

fourth subpopulation, which occurred in Arroyo Mocho, was quite distinct and was more similar 

to Whitney hatchery stocks than it was to other subpopulations within the basin or even the wider 

ESU. Nielsen (2003) suggests that this population may either be a population of native rainbow 

trout with no association to anadromous forms, or has experienced significant genetic 

introgression from introduced hatchery stocks. 

Gall et al. (1990) examined the genetics of two populations in tributaries to the upper San 

Leandro Reservoir on San Leandro Creek. This creek drains into the San Francisco Bay and is, 

interestingly, the type locality for coastal rainbow trout (Salmo irideus, now known as 

Oncorhynchus mykiss irideus) (Gall et al. 1990, Behnke 1992). Gall et al. (1990) analyzed 

genetic variability at 17 marker loci using electrophoresis and concluded that the populations 

truly belonged to the coastal subspecies of O. mykiss (i.e., ssp. irideus). However, their study 

was not designed to assess whether the populations were more similar to hatchery stocks than to 

264
21. CENTRAL CALIFORNIA COAST STEELHEAD ESU 

nearby wild populations. They reported anecdotal observations that the fish make steelhead-like 

runs to and from the reservoir.

New Hatchery Information 

California hatchery stocks being considered for inclusion in the Central California Coast 

steelhead ESU are those from Don Clausen Fish Hatchery and the Monterey Bay Salmon and 

Trout Project. The stocks and their associated hatcheries were assigned to one of three 

categories for the purpose of determining ESU membership at some future date (see subsection, 

Artificial Propagation, in Section 1, Introduction, for a description of the three categories and 

related issues regarding ESU membership). To make the assignments, data about broodstock 

origin, size, management, and genetics were gathered from fisheries biologists and are 

summarized below. 

Don Clausen Fish Hatchery 

(Warm Springs Steelhead, CDFG) 

The hatchery and collection site is located on Dry Creek, 22 km above the confluence of 

Dry Creek and the Russian River and 75 river km from the ocean. In 1992, the Coyote Valley 

Fish Facility was opened at the base of Coyote Valley Dam on the East Fork Russian River, 157 

km from the ocean. Both facilities trap fish on site. Coyote Valley fish are trapped and spawned 

there, but raised at Don Clausen Fish Hatchery. The Coyote Valley steelhead are imprinted for 

30 days at the facility before release. 

Broodstock origin and history

The hatchery was founded in 198, and the first released steelhead in 1982. The Coyote 

Valley Fish Facility was opened in 1992. Don Clausen Fish Hatchery has had few out-of-basin 

transfers into its broodstock. However, significant numbers of Mad River Hatchery steelhead 

have been released into the basin. In the earlier part of the century, steelhead from Scott Creek 

were released throughout the basin. Since the Coyote Valley Fish Facility has been constructed, 

broodstock has been trapped at the facility. 

Broodstock and natural population size

At Don Clausen Fish Hatchery, an average of 3,301 fish were trapped and 244 females 

were spawned during the broodyears 1992–2002. At the Coyote Valley Fish Facility, an annual 

average of 1,947 steelhead were trapped from 1993 to 2002 and an average of 124 females 

spawned. There are no steelhead abundance estimates for the Russian River, but fish are 

observed to be widely distributed and plentiful (NMFS 2002d). 

Management

As of 1998, steelhead have been 100% ad-clipped. Until broodyear 2000, both hatchery 

and naturally spawned fish were included in the broodstock in the proportion that they returned 

to the hatchery. Since then, only adipose-marked fish are spawned, and all unmarked steelhead 

are relocated into tributaries of Dry Creek. The production goal for Don Clausen Fish Hatchery 

265
STEELHEAD

is 300,000 yearlings released beginning in December, by size, with all fish released by April. 

The Coyote Valley Fish Facility’s goal is 200,000 yearlings that volitionally release between 

January and March. 

Category

The Don Clausen Fish Hatchery has been determined to belong to case 2 (SSHAG 2003; 

Appendix B, Table B-3). Although some out-of-ESU stocks were present in the basin, there 

have been no significant introductions since the hatchery began operations. The stock itself has 

only been cultivated for 20 years. The run is abundant and naturally spawned fish were included 

in the broodstock until 2000. Since that time only adipose-marked steelhead have been spawned. 

Monterey Bay Salmon and Trout Project 

(Kingfisher Flat [Big Creek] Hatchery; Scott Creek Steelhead) 

The Kingfisher Flat Hatchery is located on Big Creek, a tributary of Scott Creek, 6 km 

upstream from the mouth. Broodstock are taken by divers’ netting adults, usually in Big Creek 

below the hatchery, but at times throughout the Scott Creek system (NMFS 2002e). Steelhead 

are also taken at a trap on the San Lorenzo River in Felton, California. San Lorenzo River 

steelhead are kept separately and released back into the San Lorenzo basin. 

Broodstock origin and history 

The Kingfisher Flat Hatchery began in 1975. However, California state hatchery activity 

near this site has a history that dates back to 1904 (Strieg 1991). The state hatchery program 

ended in 1942 due to flood damage. Under the California state hatchery program, Scott Creek 

steelhead were widely planted throughout coastal California, as they were thought to be an 

exceptionally healthy stock. The hatchery was damaged by floods in 1941–1942 and closed. 

There are limited records of introductions from Mount Shasta and Prairie Creek hatcheries into 

this broodstock. 

In 1976, the Monterey Bay Salmon and Trout Project began operations at the Big Creek 

location. Since then, broodstock have been taken either in Scott Creek by divers or at a trap in 

the San Lorenzo River near Felton. Since that time, there have been no introductions into the 

broodstock. As with all cooperative hatcheries, the fish are all marked, and hatchery fish are 

usually excluded from broodstock. Fish are released in either Scott Creek or the San Lorenzo 

River, depending on the source of the broodstock. 

Broodstock and natural population size

An average of 98 fish were trapped and 25 females spawned during the 1990–1996 

broodyears. There are no abundance estimates for Scott Creek and the San Lorenzo River, but 

juveniles have been observed anecdotally to be widespread and abundant (NMFS 2002e). 

266
21. CENTRAL CALIFORNIA COAST STEELHEAD ESU 

Management

Starting in 2000, the practice of planting San Lorenzo fish into the North Fork Pajaro 

River basin was discontinued. Although the distance is only a matter of miles, it is across ESU 

boundaries. The current program goal is the restoration of local steelhead stocks. 

Population genetics

Allozyme data groups the Scott Creek, San Lorenzo, and Carmel River stocks together 

(Busby et al. 1996). Collectively they fall within the “south-of-the-Russian-River” grouping. 

Category 

The hatchery was determined to fall into case 1 (SSHAG 2003; Appendix B, Table B-3). 

The stock has not had out-of-basin introductions in recent years, and hatchery fish are excluded 

from the broodstock. 

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22. South-Central California Coast 

Steelhead ESU 

Summary of Previous BRT Conclusions 

The geographic range of the South-Central California Coast steelhead ESU was 

determined to extend from the Pajaro River basin in Monterey Bay south to, but not including, 

the Santa Maria River basin near the town of Santa Maria. The ESU was separated from 

steelhead populations to the north on the basis of genetic data (mitochondrial DNA and 

allozymes) and from steelhead populations to the south on the basis of a general faunal transition 

in the vicinity of Point Conception. The genetic differentiation of steelhead populations within 

the same ESU, and the genetic differentiation between ESUs, appears to be greater in the south 

than in northern California or the Pacific Northwest; however the conclusion is based on genetic 

data from a small number of populations. 

Summary of Major Risks and Status Indicators 

Risks and limiting factors 

Numerous minor habitat blockages were considered likely throughout the region. Other 

typical problems were thought to be dewatering from irrigation and urban water diversions and 

habitat degradation in the form of logging on steep erosive slopes, agricultural and urban 

development on floodplains and riparian areas, and artificial breaching of estuaries during 

periods when they are normally closed off from the ocean by a sandbar. 

Status indicators 

Historical data on the South-Central California Coast steelhead ESU are sparse. In the 

mid-1960s, the CDFG (1965) estimated that the ESU-wide run size was about 17,750 adults. No 

comparable recent estimate exists; however, recent estimates exist for five river systems (Pajaro, 

Salinas, Carmel, Little Sur, and Big Sur), indicating runs of fewer than 500 adults where 

previous runs had been on the order of 4,750 adults (CDFG 1965). Time-series data only existed 

for one basin (the Carmel River), and indicated a decline of 22% per year over the interval 1963 

to 1993 (see Abundance in the Carmel River, page 271, for an update of this conclusion). 

Many of the streams were thought to have somewhat to highly impassable barriers, both 

natural and anthropogenic, and in their upper reaches to harbor populations of resident trout. 

The relationship between anadromous and resident O. mykiss is poorly understood in this ESU, 

but was thought to play an important role in its population dynamics and evolutionary potential. 

A status review update conducted in 1997 (NMFS 1997b) listed numerous reports of juvenile O. 

mykiss in many coastal basins, but noted that the implications for adult numbers were unclear. 

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22. SOUTH-CENTRAL CALIFORNIA COAST STEELHEAD ESU 

The review also discussed the fact that certain inland basins (the Salinas and Pajaro systems) are 

rather different ecologically from coastal basins. 

Previous BRT Conclusions 

The original BRT (Busby et al. 1996) concluded that the ESU was in danger of 

extinction, due to 1) low total abundance and 2) downward trends in abundance in those stocks 

for which data existed. The negative effects of poor land-use practices and trout stocking were 

also noted. The major area of uncertainty was the lack of data on steelhead run sizes, past and 

present. The status review update (NMFS 1997b) concluded that abundance had slightly 

increased in the years immediately preceding the review, but that overall abundance was still low 

relative to historical numbers. They also expressed concern that high juvenile abundance and 

low adult abundance observed in some data sets suggested that many or most juveniles were 

potentially resident fish (i.e., rainbow trout). The BRT convened for the update was nearly split 

on whether the fish were in danger of extinction, or currently not endangered but likely to 

become so in the foreseeable future, with the latter view holding a slight majority. 

Listing status: Threatened. 

New Data and Updated Analyses 

There are three new significant pieces of information: 1) updated time-series data 

concerning dam counts made on the Carmel River (MPWMD 2001; see analyses section below 

for further discussion); 2) a comprehensive assessment of the current geographic distribution of 

O. mykiss within the ESU’s historical range (Boughton and Fish 2003, see next paragraph); and 

3) changes in harvest regulations since the last status review (see next subsection). 

Current versus Historical Distribution 

In 2002, an extensive study was made of steelhead occurrence in most of the coastal 

drainages between the northern and southern geographic boundaries of the South-Central 

California Coast steelhead ESU (Boughton and Fish 2003). Steelhead were considered to be 

present in a basin if adult or juvenile O. mykiss were observed in any stream reach that had 

access to the ocean (i.e., no impassable barriers between the ocean and the survey site), in any of 

the years 2000–2002 (i.e., within one steelhead generation). Of 36 drainages in which steelhead 

were known to have occurred historically, between 86% and 94% were currently occupied by O. 

mykiss. The range in the estimate of occupancy occurs because three basins could not be 

assessed due to restricted access. Of the vacant basins, two were considered to be vacant 

because they were dry in 2002, and one was found to be watered, but a snorkel survey revealed 

no O. mykiss. One of the “dry” basins—Old Creek—is dry because no releases were made from 

Whale Rock Reservoir; however, a landlocked population of steelhead is known to occur in the 

reservoir above the dam. 

Occupancy was also determined for 18 basins with no historical record of steelhead 

occurrence. Three of these basins—Los Osos, Vicente, and Villa creeks—were found to be 

occupied by O. mykiss. It is somewhat surprising that no previous record of steelhead seems to 

exist for Los Osos Creek, near Morro Bay and San Luis Obispo. 

269
STEELHEAD

The distribution of steelhead among the basins of the region is not much less than what 

occurred historically, so despite the widespread declines in habitat quality and population sizes, 

regional extirpations have not yet occurred. This conclusion rests on the assumption that 

juveniles inhabiting stream reaches with access to the ocean will undergo smoltification, and thus 

are truly steelhead. 

Three analyses are made below: 1) a critical review of the historical run sizes cited in the 

previous status review, 2) an assessment of recent trends observed in the adult counts being made 

on the Carmel River; and 3) a summary of new sport-fishing regulations in the region. 

Review of Historical Run Sizes 

Estimates of historical sizes for a few runs were described in the previous status review 

(Busby et al. 1996), and are here reproduced in Table 56. 

The recent estimates for the Pajaro River (1,500, 1,000, 2,000) were reported in McEwan 

and Jackson (1996), but the methodology and data set used to produce the estimates were not 

described. CACSS (1988) suggested an annual run size of 20,000 adults in the Carmel River in 

the 1920s, but gave no supporting evidence for the estimate. Their 1988 estimate of 2,000 adults 

also lacked supporting evidence. Meyer Resources (1988) provides an estimate of run size, but 

was not available for review at the time of this writing. 

Snider (1983) examined the Carmel River and produced many useful data. In the abstract 

of his report he gave an estimate of 3,177 fish as the mean annual smolt production for 1964 

through 1975; Busby et al. (1996) mistakenly cited this estimate as an estimate of run size. 

Snider’s 3,177 figure may itself be a mistake, as it disagrees with information in the body of the 

report, which estimates annual smolt production in 1973 at 2,708 and in the year 1974 at 2,043. 

Snider (1983) gives adult counts for fish migrating upstream through the fish ladder at San 

Clemente Dam for 1964 through 1975 (data were not reported in Busby et al. [1996], but were 

apparently the basis for the 22% decline they reported). (See Figure 189 for the actual counts.) 

Table 56. Estimates of historical steelhead run sizes from the previous status review (Busby et al. 1996). 

River basin Run size estimate Year Reference 

Pajaro River 1,500 1964 McEwan and Jackson (1996) 

1,000 1965 McEwan and Jackson (1996) 

2,000 1966 McEwan and Jackson (1996) 

Carmel River 20,000 1928 CACSS (1988) 

3,177 1964–1975 Snider (1983) 

2,000 1988 CACSS (1988) 

<4,000 1988 Meyer Resources (1988) 

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22. SOUTH-CENTRAL CALIFORNIA COAST STEELHEAD ESU 

Year

1960 1970 1980 1990 2000 2010

Number of Adults

-200

0

200

400

600

800

1000

1200

1400

1600

Adult Counts

Linear Regression

Figure 189. Adult steelhead counts at San Clemente Dam, Carmel River. Data from the Monterey 

Peninsula Water Management District. See Snider (1983) for methods of counting fish before 

1980; these early data are subject to substantial observation error (note: the regression line is not 

significantly different from flat). The increase during the 1990s followed a severe drought (and 

concurrent dewatering of the main stem by a water district) in the late 1980s and early 1990s. 

The mean run size from these data is 821 adults. To make these estimates, visual counts 

were made twice a day by reducing the flow through the ladder and counting the fish in each 

step; thus they may underestimate the run size by some unknown amount if fish moved 

completely through the ladder between counts (an electronic counter was used in 1974 and 1975 

and presumably is more accurate). In addition, San Clemente Dam is 31 km from the mouth of 

the river, and a fraction of the run spawns below the dam (CDFG biologists estimate the fraction 

to be one third of the run, based on redd surveys). 

Thus, much historical data used in the previous status review are highly uncertain. The 

most reliable data are the Carmel River Dam counts, which were not reported in the previous 

status review. Further analyses of these data are described below. 

Abundance in the Carmel River 

The Carmel River data are the only time series for the South-Central California Coast 

steelhead ESU. The data suggest that the abundance of adult spawners in the Carmel River has 

increased since the last status review (Figure 189). A continuous series of data exists for 1964 

through 1977, although the data are probably incomplete to various degrees for each year (i.e., 

the counts are probably incomplete, and the year-to-year fluctuations may be mostly due to 

observation error rather than population variability). A regression line drawn through the data 

indicates a downward trend, but the trend is not statistically significant (slope = –28.45; R2

 = 

0.075; F = 1.137; p = 0.304). The 22% decline reported by Busby et al. (1996) is apparently 

based on these data, in comparison with the low numbers of the early 1990s. 

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STEELHEAD

Continuous data have also been collected for the period 1988 through 2002. The 

beginning of this time series has counts of zero adults for 3 consecutive years, then shows a rapid 

increase in abundance. The trend is strongly upward (see Table 57). The time series is too short 

to make a reliable estimate of mean lambda. The observed positive trend could conceivably be 

due either to improved conditions (i.e., mean lambda greater than 1), substantial immigration or 

transplantation, or the transient effects of age structure. Improved conditions seem by far the 

most likely explanation, as the basin has been the subject of intensive fisheries management 

since the early 1990s. According to the Monterey Peninsula Water Management District, the 

entity conducting much of the restoration of the basin’s steelhead fishery, the likely reasons for 

the positive trend are due to improved conditions, namely 

Improvements in streamflow patterns, due to favorable natural fluctuations ... since 

1995; ... actively manag[ing] the rate and distribution of groundwater extractions and 

direct surface diversions within the basin; changes to Cal-Am’s [dam] operations ... 

providing increased streamflow below San Clemente Dam; improved conditions for fish 

passage at Los Padres and San Clemente Dams ...; recovery of riparian habitats, tree 

cover along the stream, and increases in woody debris ...; extensive rescues ... of 

juvenile steelhead over the last ten years ... ; transplantation of the younger juveniles to 

viable habitat upstream and of older smolts to the lagoon or ocean; and implementation of 

a captive broodstock program by Carmel River Steelhead Association and California 

Department of Fish & Game (CDFG), [including] planting ... from 1991 to1994. 

(MPWMD 2001) 

Even so, the rapid increase in adult abundance from 1991 (one adult) to 1997 (775 adults) 

seems too great to attribute simply to improved reproduction and survival of the local steelhead. 

There are a number of possibilities: substantial immigration or transplantation may have boosted 

abundance, or perhaps there was a large population of resident trout that has begun producing 

smolts at a higher rate under improved freshwater conditions. The transplantation hypothesis is 

thought unlikely: although transplantation of juveniles occurred (in the form of rescues from the 

lower main stem during periods in which it was dewatered), CDFG biologists consider the scale 

of these efforts to be too small to cause the large increase in run size that has been observed. The 

scale of immigration (i.e., straying) is not known but may be a significant factor. As for the role 

of resident trout in producing smolts, the phenomenon is known to occur but the environmental 

triggers have not yet been worked out. One hypothesis, congruent with the Carmel River 

situation, is that environmental conditions affect growth rate of juveniles, which affects 

Table 57. Summary of time-series data for the South-Central California Coast steelhead ESU. 

5-year meana

Population 

Time 

series Record Min. Max. λb

Long-term trend 

(95% confidence 

interval) 

Short-term trend

(95% confidence 

interval) 

Carmel River 

(winter run) 

1962–

2002 611 1.13 881 Insufficient data 

0.488 

(0.442, 0.538)c

0.488 

(0.442, 0.538) a Geometric means. The value 0.5 was used for years in which the count was zero. 

b Lambda calculated using the method of Lindley (2003). Note that a population with λ greater than 1.0 can 

nevertheless be declining, due to environmental stochasticity. 

c

 Exceptionally high observation error; not used in calculations. 

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22. SOUTH-CENTRAL CALIFORNIA COAST STEELHEAD ESU 

propensity to smolt into the anadromous form. The rapid increase in adult abundance in the 

Carmel River system is thus very interesting. At this point two conclusions seem warranted: 

1. Upon improvement of freshwater conditions such as those described above, the adult runs 

are capable of rapid increase in the South-Central California Coast steelhead ESU, due 

either to resilience of steelhead populations, high stray rates, or ability of resident trout to 

produce smolts. Either mechanism might allow the fish to rapidly take advantage of 

improved conditions, suggesting a high potential for rapid recovery in this ESU if the 

proper actions were taken. 

2. Although some component of the increase is probably due to improved ocean conditions, 

it would be a mistake to assume comparable increases have occurred in other basins of 

the ESU, as they have not been the focus of such intensive management efforts. 

Possible Changes in Harvest Impacts 

Since the original status review of Busby et al. (1996), regulations concerning sport 

fishing have been changed in a way that probably reduces extinction risk for the South-Central 

California Coast steelhead ESU. 

The CDFG (2002a) has prohibited sport harvest of steelhead in the ocean, and ocean 

harvest is a rare event,28 so effects on extinction risk are probably negligible. For freshwaters, 

CDFG (2002b) describes the current regulations. Summer trout fishing is allowed in some 

systems, often with a two or five per bag limit. These areas include significant parts of the 

Salinas system (upper Arroyo Seco and Nacimiento above barriers, the upper Salinas, Salmon 

Creek, and the San Benito River in the Pajaro system all have a bag limit of five trout). Also 

included in the summer fisheries is the Carmel River above Los Padres Dam (bag limit is two 

trout, between 10 inches and 16 inches). A few other creeks have summer catch-and-release 

regulations. The original draft of the Fishery Management and Evaluation Plan (CDFG 2000a) 

recommended complete closure of the Salinas system to protect the steelhead there, but the final 

regulations did not implement this recommendation, allowing both summer trout angling and 

winter-run catch-and-release steelhead angling in selected parts of the system (CDFG 2002b). 

The regulations allow catch-and-release winter-run steelhead angling in many of the river 

basins occupied by the South-Central California Coast steelhead ESU, specifying that all wild 

steelhead must be released unharmed. There are significant restrictions on timing, location, and 

gear used for angling. A recent draft of the Fishery Evaluation and Management Plan (CDFG 

2001b) argues that the only mortality expected from a no-harvest fishery is from hooking and 

handling injury or stress. They estimate this mortality rate to be about 0.25–1.4%. This estimate 

is based on angler capture rates measured in other river systems throughout California (range of 

5–28%), multiplied by an estimated mortality rate of 5% once a fish is hooked. The latter 

mortality estimate is consistent with a published metaanalysis of hooking mortality (Schill and 

Scarpella 1997), but experimental studies on the subject—from which the estimates are made— 

 

28See Footnote 25.

273
STEELHEAD

tend to measure mortality only for a period of a few days or a week after capture (e.g., Titus and 

Vanicek 1988). 

The Fishery Management and Evaluation Plan contains no extensive plans for monitoring 

fish abundance. Although the closure of many areas and institution of catch-and-release 

elsewhere is expected to reduce extinction risk for the ESU, this risk reduction cannot be 

estimated quantitatively from the existing data, due to the fact that natural abundance is not being 

measured. 

Resident O. mykiss Considerations 

Resident (nonanadromous) populations of O. mykiss were assigned to one of three 

categories for the purpose of provisionally determining ESU membership (see subsection, 

Resident Fish, in Section 1 for a description of the three categories and default assumptions 

about ESU membership). The third category consists of resident populations that are separated 

from anadromous conspecifics by recent man-made barriers such as dams without fish ladders. 

No default assumption about ESU membership was possible for case 3 populations, so they are 

considered here case by case, according to available information. 

As of this writing we have few data on occurrence of resident populations and even fewer 

on genetic relationships. A provisional survey of the occurrence of case 3 populations in the 

South-Central California Coast steelhead ESU (see Appendix B, Table B-2) revealed the 

following: There are four significant case 3 populations within the ESU’s original geographic 

range (Appendix B, Table B-2)—two in the Salinas system, one behind Whale Rock Dam near 

Cayucos, and one behind the Lopez Reservoir on Arroyo Grande Creek. The two in the Salinas 

system occur behind the dams on the Nacimiento and San Antonio rivers, which currently block 

what were reported to be two of the three principal steelhead spawning areas in the basin (the 

other being in Arroyo Seco; Titus et al. [2002]). Resident populations occur above these dams 

and stocking is ongoing (Appendix B, Table B-2). A third major barrier occurs in the 

headwaters of the Salinas itself; stocking currently occurs above this dam. Steelhead reportedly 

spawned in these streams before the dam was built, but the runs were probably relatively small 

and sporadic. 

The Whale Rock Reservoir has a resident population that is reported to make steelheadlike runs up several tributaries for spawning. The reservoir has an associated hatchery program 

(see the previous section for details on genetic studies, stocking records, and so on). 

According to David Starr Jordan (cited in Titus et al. 2002), the area now blocked by the 

Lopez Dam on Arroyo Grande Creek was originally well known as a significant steelhead area. 

A resident population currently exists above this dam, and stocking is ongoing (Table B-1). We 

are not aware of any studies of the population’s genetic affinities. 

Minor Barriers 

Defined here as blocking less than 259 sq. km (100 sq. mi.) of watershed, minor barriers 

are numerous within the geographic range of the South-Central California Coast steelhead ESU. 

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22. SOUTH-CENTRAL CALIFORNIA COAST STEELHEAD ESU 

A nonzero number of case 3 populations undoubtedly exist above these barriers, but at the 

present time data are insufficient to make a comprehensive assessment. 

New Hatchery Information 

The only hatchery stock considered in the South-Central California Coast steelhead ESU 

is the one at Whale Rock Hatchery. This stock was assigned to one of three categories for the 

purpose of determining ESU membership at some future date (see subsection, Artificial 

Propagation, in Section 1 for a description of the three categories and related issues regarding 

ESU membership). To make the assignment, data about broodstock origin, size, management, 

and genetics were gathered from fisheries biologists and are summarized below. 

Whale Rock Hatchery 

(Whale Rock Steelhead, CDFG) 

Whale Rock Reservoir was created in 1961 by placing a dam on Old Creek, 2 km 

upstream from the coast. Old Creek had supported a large steelhead run prior to construction of 

the dam, and these fish were presumably trapped behind the dam (the creek is usually dewatered 

below the dam so no population occurs there at all). Whale Rock Hatchery was established in 

1992 as an effort to improve the sport fishery in the reservoir after anglers reported a decline in 

fishing success. The original Whale Rock broodstock (40 fish) were collected at a temporary 

weir placed in the reservoir at the mouth of Old Creek Cove (Nielsen 2003). Adult fish were 

trapped in the shallows of the reservoir using nets set during late winter and spring as the fish 

begin their migration upstream from the reservoir into Old Creek. The fish are held in an 

enclosure while they are monitored for ripeness. Eggs and sperm are collected from fish using 

nonlethal techniques, then the adult fish are returned to the reservoir. Fish were originally 

hatched and raised at the Whale Rock Hatchery located below the dam at the maintenance 

facility, but are now raised at the Fillmore Hatchery in Ventura County. The fry are cared for 

until September or November, at which time they are released back into the reservoir as 3- to 5-

inch fingerling trout. 

Broodstock origin and history

Hatchery operations began in 1992 and have been sporadic since. The project is a 

cooperative venture between CDFG and private parties. Fish were raised in 1992, 1994, 2000, 

and 2002.29 All broodstock are taken from the reservoir. 

Broodstock size/natural population size

An average of 121 fish were spawned. Spawning success has been poor. There are no 

population estimates for the reservoir, and the hatchery fish are not marked. 

Management

The current program goal is to increase angling success in Whale Rock Reservoir. 

 

29H. Fish, Southwest Fisheries Science Center, Santa Cruz, CA. Pers. commun., 25 February 2003. 

275
STEELHEAD

Population genetics

Neilsen et al. (1997) found that significant genetic relatedness occurs between the Whale 

Rock Hatchery stock and wild steelhead in the Santa Ynez River and Malibu Creek, two basins 

to the south. They reported a loss of genetic diversity within the hatchery stock. 

Category

The hatchery was determined to belong to case 2 (SSHAG 2003; Appendix B, Table 

B-3). Broodstock are taken from the source population, but the small population could easily 

lead to significant genetic bottlenecks. 

276
23. Southern California Steelhead ESU 

Summary of Previous BRT Conclusions 

The geographic range of the Southern California steelhead ESU extends from the Santa 

Maria River basin near the town of Santa Maria, south to the U.S. border with Mexico. 

O. mykiss populations are reported in Baja California del Norte (Ruiz-Campos and Pister 1995); 

these populations are thought to be resident trout, but could be found to have an anadromous 

component with further study (note that they do not lie within the jurisdiction of the ESA). 

NMFS (1997b) cites reports of several other steelhead populations south of the border. The 

Southern California steelhead ESU is the extreme southern limit of the anadromous form of 

O. mykiss. It was separated from steelhead populations to the north on the basis of a general 

faunal transition (in the fauna of both freshwater and marine systems) in the vicinity of Point 

Conception. The genetic differentiation of steelhead populations within the ESU, and from other 

ESUs in northern California or the Pacific Northwest appears to be great; however, the 

conclusion is based on genetic data from a small number of populations. 

Summary of Major Risks and Status Indicators 

Risks and limiting factors 

The original BRT (Busby et al. 1996) noted that there has been extensive loss of 

populations, especially south of Malibu Creek, due to urbanization, dewatering, channelization 

of creeks, man-made barriers to migration, and the introduction of exotic fish and riparian plants. 

Many of these southernmost populations may have originally been marginal or intermittent (i.e., 

exhibiting repeated local extinctions and recolonizations in bad and good years, respectively). 

No hatchery production exists for the ESU. The relationship between anadromous and resident 

O. mykiss is poorly understood in this region, but likely plays an important role in population 

dynamics and evolutionary potential of the fish. 

Status indicators 

Historical data on the Southern California steelhead ESU were sparse. The historical run 

size for the ESU (Busby et al. 1996) was roughly estimated to be at least 32,000–46,000 

(estimates for the four systems comprising the Santa Ynez, Ventura, and Santa Clara rivers and 

Malibu Creek, which omits the Santa Maria system and points south of Malibu Creek). Recent 

run sizes for the same four systems were roughly estimated to be less than 500 adults total. No 

time-series data were found for any populations. 

277 
STEELHEAD

Previous BRT Conclusions 

The original BRT concluded that the Southern California steelhead ESU was in danger of 

extinction, noting that populations were extirpated from much of their historical range (Busby 

et al. 1996). The BRT had strong concern about widespread degradation, destruction, and 

blockage of freshwater habitats, and concern about stocking of rainbow trout. The two major 

areas of uncertainty were 1) lack of data on run sizes, past and present, and 2) the relationship 

between resident and anadromous forms of the species in the region. A second BRT convened 

for an update (NMFS 1997b) found that the small amount of new data did not suggest that the 

situation had improved, and the majority view was that the ESU was still in danger of extinction. 

The Southern California steelhead ESU was listed as endangered in 1997. The original 

listing defined the ESU as having its southern geographic limits in Malibu Creek. Two small 

populations were subsequently discovered south of this point, and in 2002 a notice was published 

in the Federal Register (Hogarth 2002), extending the range to include all steelhead found in 

drainages south to the U.S. border with Mexico. 

Listing status: Endangered. 

New Data and Updated Analyses 

There are four new significant pieces of information regarding the Southern California 

steelhead ESU: 

1. Four years of adult counts in the Santa Clara River 

2. Observed recolonizations of vacant watersheds, notably Topanga Creek in Los Angeles 

County and San Mateo Creek in Orange County 

3. A comprehensive assessment of the current distribution of O. mykiss within the historical 

range of the ESU (Boughton and Fish 2003) 

4. Changes in the harvest regulations of the sport fishery 

Discussion of this new information follows. 

Current Distribution versus Historical Distribution 

In 2002, an extensive study was made of steelhead occurrence in most of the coastal 

drainages within the geographic boundaries of the Southern California steelhead ESU (Boughton 

and Fish 2003). Steelhead were considered to be present in a basin if adult or juvenile O. mykiss

were observed in any stream reach that had access to the ocean (i.e., no impassable barriers 

between the ocean and the survey site), in any of the years 2000–2002 (i.e., within one steelhead 

generation). Of 46 drainages in which steelhead were known to have occurred historically, 

O. mykiss still occupied between 37% and 43%. The range in the occupancy estimate occurs 

because a number of basins could not be surveyed due to logistical problems, pollution, or lack 

of permission to survey on private land. Three basins were considered vacant because they were 

dry, 17 were considered vacant due to impassable barriers below all spawning habitat, and 6 

278 
23. SOUTHERN CALIFORNIA STEELHEAD ESU 

were considered vacant because a snorkel survey found no evidence of O. mykiss. The snorkel 

surveys consisted of spot checks in likely habitats and did not involve a comprehensive 

assessment of each basin. 

One of the “dry” basins—the San Diego River—may have water in some tributaries; it 

was difficult to establish that the entire basin below the dam was completely dry. Numerous 

anecdotal accounts suggest that several of the basins that had complete barriers to anadromy may 

have landlocked populations of native steelhead and rainbow trout in the upper tributaries. 

These basins include the San Diego, Otay, San Gabriel, Santa Ana, and San Luis Rey rivers. 

Occupancy was also determined for 17 basins with no historical record of steelhead occurrence; 

none was found to be currently occupied. 

Nehlsen et al. (1991) listed the following southern California stocks as extinct: Gaviota 

Creek, Rincon Creek, Los Angeles River, San Gabriel River, Santa Ana River, San Diego River, 

San Luis Rey River, San Mateo Creek, Santa Margarita River, Sweetwater River, and Maria 

Ygnacio River. The distributional study of 2002 determined that steelhead were present in two 

of these systems, namely Gaviota Creek (Stoecker and CCP 2002) and San Mateo Creek (a 

recent colonization; see below). Nevertheless, the current distribution of steelhead among the 

region’s basins appears to be substantially less than what occurred historically. Except for the 

small population in San Mateo Creek in northern San Diego County, the anadromous form of the 

species appears to be completely extirpated from all systems between the Santa Monica 

Mountains and the Mexican border. Additional years of observations, either of presence or 

absence, would reduce the uncertainty of this conclusion. 

Recent Colonization Events 

Several colonization events were reported during the interval from 1996 to 2002. 

Steelhead colonized Topanga Creek in 1998 and San Mateo Creek in 1997.30 As of October 

2002, both colonizations persist, although the San Mateo Creek colonization appears to be 

declining. T. Hovey31 used genetic analyses to establish that the colonization in San Mateo 

Creek was made by two spawning pairs in 1997. In the summer of 2002 a dead mature female 

was found in the channelized portion of the San Gabriel River in the Los Angeles area.32 A 

single live adult was found trapped and oversummering in a small watered stretch of Arroyo 

Sequit in the Santa Monica Mountains.33 The run sizes of these colonization attempts are of the 

same order as recent run sizes in the Santa Clara system—namely, less than five adults per year. 

Each of the four colonization events reported above occurred in a basin in which the presence of 

steelhead had been documented historically (Titus et al. 2002). 

 

30Tim Hovey, California Department of Fish and Game, San Diego, CA. Pers. commun., 28 March 2003. 

31See Footnote 30. 

32M. Larsen, California Department of Fish and Game, Los Alamitos, CA. Pers. commun., 

13 October 2002. 

33K. Pipal and D. Boughton, Southwest Fisheries Science Center, Santa Cruz, CA. Pers. commun., 

9 September 2002. 

279 
STEELHEAD

Table 58. Estimates from Busby et al. (1996) for run sizes in the major river systems of the Southern 

California steelhead ESU. 

River basin Run-size estimate Year Reference 

Santa Ynez 20,000–30,000 Historical Reavis (1991) 

12,995–25,032 1940s Shapovalov and Taft (1954) 

20,000 Historical Titus et al. (2002) 

20,000 1952 CDFG (1982) 

Ventura 4,000–6,000 Historical AFS (1991) 

4,000–6,000 Historical Hunt et al. (1992) 

4,000–6,000 Historical Henke (1994) 

4,000–6,000 Historical Titus et al. (2002) 

Matilija 

Creek 

2,000–2,500 Historical Clanton and Jarvis (1946) 

Santa Clara 7,000–9,000 Historical Moore (1980) 

9,000 Historical Comstock (1992) 

9,000 Historical Henke (1994) 

Two significant analyses exist: 1) a critical review of the historical run sizes cited in the 

previous status review (Busby et al. 1996), and 2) a few new data on run size and population 

distribution in three of the larger basins. 

Review of Historical Run Sizes

Few quantitative data exist on historical run sizes of southern California steelhead. Based 

on the available information at the time, the previous status review made rough estimates for 

three of the large river systems (Table 58), and a few of the smaller ones (Busby et al. 1996). 

The Santa Ynez River 

The run size in the Santa Ynez system—probably the largest run historically—was 

estimated to originally lie between 20,000 and 30,000 spawners (Busby et al. 1996). This 

estimate was based primarily on four references cited in the status review: Reavis (1991), 

20,000–30,000 spawners; Titus et al. (2002), 20,000 spawners; Shapovalov and Taft (1954), 

12,995–25,032 spawners; and CDFG (1982), 20,000 spawners. Examination of these references 

revealed the following: Reavis (1991) asserted a run size of 20,000–30,000, but provided no 

supporting evidence. Titus et al. (2002) reviewed evidence described by Shapovalov (1944), 

described below. Shapovalov and Taft (1954) did not address run sizes in this geographic 

region; the citation is probably a miscitation for Shapovalov (1944). CDFG (1982) makes no 

reference to salmonid fishes in southern California. 

Entrix Environmental Consultants (1995) argued that the estimate of 20,000–30,000 is 

too large. They argued that the only direct observations of run size are from Shapovalov (1944), 

an assertion that appears to be correct. These data are based on a CDFG employee’s visual 

280 
23. SOUTHERN CALIFORNIA STEELHEAD ESU 

estimate that the 1944 run was “at least as large” as runs in the Eel River (northern California), 

which the employee had observed in previous years. Estimated run sizes for the Eel River 

ranged between 12,995 and 25,032 during the years 1939 to 1944 (Shapovalov 1944), and this 

has thus been reported as the estimated run size of the Santa Ynez. Entrix (1995) observed, 

however, that the employee who made the comparison was only present at the Eel River during 

two seasons, 1938–1939 and 1939–1940. The estimates for run sizes in those years were 12,995 

and 14,476, respectively, which suggests that a more realistic estimate for the Santa Ynez run of 

1944 would be 13,000–14,500. Taking this chain of reasoning to its logical conclusion, the 

range 13,000–14,500 should be regarded as a minimum run size for the year in question, since 

the employee used the phrase “at least as large.” 

It is perhaps useful to place the year 1944 in context, since expert opinion about run size 

is based solely on observations made in that year. Entrix (1995) reports that 1944 occurred 

toward the end of a wet period, which may have provided especially favorable spawning and 

rearing conditions for steelhead. Rainfall data from Santa Barbara County historical records give 

a different picture from Entrix (1995): only 2 of the preceding 8 years (1940 and 1943) were 

wetter than the 107-year average for the area,34 1944 was near average; and otherwise, rainfall 

was below average. 

In addition, 1944 occurred toward the end of a period in which it seems extensive rescues 

of juvenile steelhead were made during low-flow years (Shapovalov 1944, Titus et al. 2002). 

Over the interval 1939–1946, a total of 4.3 million juveniles were rescued from drying portions 

of the main stem, and they were usually replanted elsewhere in the system. This process 

averages to about 61,400 juveniles rescued per year. Assuming that rescue operations lowered 

the mean mortality rate, as intended, during the 1939–1946 interval, the Santa Ynez population 

may have increased somewhat (or failed to undergo a decline) due to the rescue operations. A 

rough estimate of magnitude can be made: Assuming deterministic population growth (as 

opposed to stochastic), and a survival to spawning of about 1%, the rescues would have 

increased the run size by about 4% per generation. High environmental stochasticity in survival 

of the rescued fish and in the overall population growth—which almost certainly was the case—

would have reduced the size to much lower than 4%. 

The counterargument to the argument that the 1944 estimate is too high is that it is too 

low. The estimate was not made until 24 years after a significant proportion of spawning and 

rearing habitat had been blocked behind dams. The Santa Ynez system currently has three major 

mainstem dams, which block portions of spawning and rearing habitat. The middle dam 

(Gibraltar), built in 1920, blocked access to 721 km of stream, much of which was widely 

regarded to be high-quality spawning and rearing habitat (Appendix B, Table B-1; Titus et al. 

2002). At that time, no estimates of run size had been made for the Santa Ynez. An upper dam 

(Juncal) was constructed in 1930 and may have had a negative effect on run size through 

reduction of flows to the lower main stem. Only the lower dam (Cachuma or Bradbury) was 

built late enough (1953) to not cause the 1944 estimate to be a biased estimate of historical run 

size. 

 

34M. Capelli, Southwest Regional Office, Santa Barbara, CA. Pers. commun., 29 May 2003. 

281 
STEELHEAD

Ventura River 

According to Titus et al. (2002), the Ventura River was estimated to have a run size of 

4,000–5,000 adults during a normal water year. This estimate was made in 1946, although it is 

likely that the estimate is an expert opinion based on numerous years of observation. The system 

had received numerous plantings of juveniles in the preceding period (27,200 in 1943, 20,800 in 

1944, and 45,440 in 1945, as well as 40,000 in 1930, 34,000 in 1931, and 15,000 in 1938). 

These rescues probably had small effect, for reasons similar to those cited above for the Santa 

Ynez. As in the Santa Ynez, anecdotal accounts suggest that run sizes declined precipitously 

during the late 1940s and 1950s, due possibly to both drought and to anthropogenic changes to 

the river system such as dam construction. Similar considerations apply to the estimate made by 

Clanton and Jarvis (1946), of 2,000–2,500 adults in the Matilija Basin, a major tributary of the 

Ventura River. 

Santa Clara River 

Moore’s (1980) estimate of 9,000 spawners in the Santa Clara Basin is an extrapolation 

of the estimate of Clanton and Jarvis’s (1946) estimate for Matilija Creek. Moore assumed 

similar levels of production per stream mile in the two systems, and noted that at least five times 

more spawning and rearing habitat exists in the Santa Clara. Moore (1980) regarded his estimate 

as biased downward because, although it included the major spawning areas (Santa Paula, Sespe, 

and Piru creeks), it omitted numerous small side tributaries. 

Ed Henke (cited in NMFS 1997b, p. 9) stated that abundance of steelhead in the Southern 

California steelhead ESU was probably about 250,000 adults prior to European settlement of the 

region. His argument is based on historical methods of research involving interviews of older 

residents of the area as well as written records. The original analysis producing the cited 

estimate is part of ongoing research and was not made available for review at the time of this 

writing.35

In summary, the estimates of historical run sizes for the Southern California steelhead 

ESU are based on very sparse data and long chains of assumptions that are plausible but have not 

been adequately tested. It seems reasonable to say that the existing estimates are biased upward 

or downward by some unknown amount. It is certainly clear from the historical record that adult 

run sizes of the past could be two or three orders of magnitude greater in size than those of recent 

years, but the long-term mean or variance in run size is not known with any reasonable precision. 

Assuming that spawning and rearing success are related to rainfall, the variance between years 

was likely high due to climatic variability in southern California; and variance among decades 

high due to the Pacific Decadal Oscillation. In addition, long-term climate change in the region 

likely causes the running mean of run size (whatever it may be) to exhibit drift over time. If one 

were interested in the true potential productivity of these systems, much could be learned by 

targeted field studies on the current habitat-productivity relationships for the fish, and by studies 

 

35E. Henke, Historical Research, Ashland, OR. Pers. commun., 28 January 2003. 

282 
23. SOUTHERN CALIFORNIA STEELHEAD ESU 

of the influence of climate, water management practices, and their interaction. It does not seem 

likely that further historical research will turn up information useful for making more refined 

estimates, despite the fact that it is useful for determining where exactly the fish occurred. 

Recent Run Sizes of Large River Systems

It seems likely that the larger river systems were originally the mainstay of the Southern 

California steelhead ESU. Large river systems that harbored steelhead populations in the past 

are (from north to south) the Santa Maria, Santa Ynez, Ventura, Santa Clara, Los Angeles, 

San Gabriel, Santa Ana, and possibly the San Diego. Of these eight systems, the data suggest 

that steelhead currently occur in only four—the Santa Maria, Santa Ynez, Ventura, and 

Santa Clara. 

Santa Maria River 

There do not appear to be any estimates for recent run sizes in the Santa Maria system. 

Twitchell Dam blocks access to a significant proportion of historical spawning habitat, the 

Cuyama River, one of the two major branches of the Santa Maria. The other major branch, the 

Sisquoc River, appears to still have substantial spawning and rearing habitat that is accessible 

from the ocean; juvenile steelhead have recently been observed in these areas (Cardenas 1996, 

Stoecker and Stoecker 2003). 

Santa Ynez River 

Most of the historical spawning habitat is blocked by Cachuma and Gibraltar dams. 

However, extensive documentation exists for steelhead and rainbow trout populations in a 

number of ocean-accessible sites below Cachuma Dam (Table 59): Salsipuedes/El Jaro, Hilton, 

Alisal, Quiota, San Miguelito creeks, and three reaches in the main stem (Hanson et al. 1996 and 

Engblom 1997, 1999, 2001). Various life stages of steelhead, including upstream migrants and 

smolts, have been consistently observed at some of these sites (Table 59), suggesting the 

occurrence of persistent populations. Run sizes are unknown, but likely small (<100 adults 

total), implying the populations are not viable over the long term. A third dam, Juncal Dam, 

occurs above the other two dams in the watershed, and is reported to support a small population 

of landlocked steelhead that annually enter the reservoirs’ tributaries to spawn.36

Ventura River 

There are no estimates of recent run sizes in the Ventura River. Casitas Dam on Coyote 

Creek and Matilija Dam on Matilija Creek block access to significant portions of the historical 

spawning habitat. There are recent individual reports of sightings of steelhead in the Ventura 

River and San Antonio Creek (Capelli 1997), but no quantitative estimates. 

 

36 See Footnote 34. 

283 
STEELHEAD

Table 59. Presence of steelhead in the lower Santa Ynez River system. 

Tributary Redds <6” >6” Smolts Adults

Year 

(spring) Source 

– Y Y Y Ya 1994 Hanson et al. (1996) 

– – – Y Ya 1995 Hanson et al. (1996) 

Y Y Y Y Ya 1996 Hanson et al. (1996), Engblom (1997)

Y Y Y Y Ya 1997 Engblom (1997) 

Y Y Y – Ya 1998 Engblom (1999) 

Y Y Y – Ya 1999 Engblom (1999) 

– – – – Ya 2000 Engblom (2001) 

Salsipuedes/ 

El Jaro 

– Y Y Y Ya 2001 Engblom (2001) 

– N N – Ya 1994 Hanson et al. (1996) 

– Y Yb Y Ya 1995 Hanson et al. (1996) 

– – – N Ya 1996 Hanson et al. (1996), Engblom (1997)

N Y Y N Ya 1997 Engblom (1997) 

Y Y – – Ya 1998 Engblom (1999) 

– – – – Na 1999 Engblom (1999) 

Hilton Creek 

– Y Y – Ya 2001 Engblom (2001) 

Alisal Creek – Y Y – Ya 1995 Hanson et al. (1996) 

– N N – Na 1994 Hanson et al. (1996) 

– – – N Na 1995 Hanson et al. (1996) 

– – – N – 1997 Engblom (1997) 

– N Y – Ya 1998 Engblom (1999) 

Nojoqui 

Creek 

– – – – Na 1999 Engblom (1999) 

Y – Y – Na 1995 Hanson et al. (1996) 

– Y Y – – 1994 Hanson et al. (1996) 

– Y – – – 1998 Engblom (1999) 

Quiota Creek 

(and 

tributaries) 

– Y Y – – 2001 Engblom (2001) 

– Y Y – – 1996 Hanson et al. (1996) 

Y – – Y – 1997 Engblom (1997) 

– Y – N Na 1998 Engblom (1999) 

San 

Miguelito 

Creek 

Y – – N Na 1999 Engblom (1999) 

– Y Y – – 1995 Hanson et al. (1996) 

– Y Y – – 1996 Hanson et al. (1996) 

– – – – Y 1994 Hanson et al. (1996) 

– Y Y – – 1998 Engblom (1999) 

Y – – – – 1999 Engblom (1999) 

Main stem/

Hwy 154 

– Y Y – – 2001 Engblom (2001) 

– Y Y – – 1995 Hanson et al. (1996) 

– N Y – – 1996 Hanson et al. (1996) 

– Y Y – – 1998 Engblom (1999) 

Y N Y – – 1999 Engblom (1999) 

Main stem/ 

Refugio 

– Y Y – – 2001 Engblom (2001) 

Main stem/ – Y Y – – 1995 Hanson et al. (1996) 

Alisal reach – N Y – – 1996 Hanson et al. (1996) 

– Y Y – – 1998 Engblom (1999) 

– Y Y – – 1999 Engblom (1999) 

– Y Y – – 2001 Engblom (2001) 

Main stem/ – N N – – 1995 Hanson et al. (1996) 

Cargasachi – N N – – 1996 Hanson et al. (1996) a Caught in upstream migrant trap. 

b Actual lengths 5′′ < x < 6′′ but assumed to be 1+ fish. 

284 
23. SOUTHERN CALIFORNIA STEELHEAD ESU 

Santa Clara River 

A few estimates of recent run sizes exist for the Santa Clara system, due to the presence 

of a fish ladder and counting trap at the Vern Freeman Diversion Dam on the main stem. This 

diversion dam lies between the ocean and what is widely believed to be one of the largest extant 

populations of steelhead in the Southern California steelhead ESU (the Sespe Canyon 

population). The run size of upstream migrants in each was one adult in 1994 and 1995, two 

adults in 1996, and no adults in 1997. No data have been collected since that date, and the fish 

ladder is thought to be dysfunctional. 

Harvest Impacts 

Since the original status review of Busby et al. (1996), regulations concerning sport 

fishing have been changed in a way that may potentially reduce extinction risk for the Southern 

California steelhead ESU. 

The CDFG currently prohibits sport harvest of steelhead in the ocean (CDFG 2002a), and 

ocean harvest is a rare event.37 For freshwaters (CDFG 2002b), summer/fall catch-and-release 

angling is allowed in Piru Creek below the dam, San Juan Creek (Orange County), San Mateo 

Creek (one section), Santa Margarita River and tributaries, and Topanga Creek. Year-round 

catch and release is allowed in the San Gabriel River (below Cogswell Dam) and Sespe Creek 

and tributaries. All of the above are historical steelhead streams, and many of the stretches open 

to fishing are potentially used both by anadromous runs and resident populations. 

Year-round trout fisheries are allowed in Calleguas Creek and tributaries (limit 5), Piru 

Creek above the dam (limit 2), San Luis Rey River (limit 5), Santa Paula Creek above the falls 

(limit 5), the Santa Ynez River above Gibraltar Dam (limit 2), Sisquoc River (limit 5), and 

Sweetwater River (limit 5). With the exception of the Sisquoc River, these take-fisheries appear 

to be isolated from the ocean by natural or man-made barriers. Except for Calleguas Creek and 

possibly the Sweetwater, the above drainages are listed as historical steelhead streams by Titus et 

al. (2002). It is certainly possible, and indeed likely, that some currently harbor native trout with 

the potential to exhibit anadromy. 

At catch-and-release streams, all wild steelhead must be released unharmed. There are 

significant restrictions on gear used for angling. The CDFG monitors angling effort and catchper-unit effort in selected basins by way of a “report card” system in which sport anglers selfreport their catch, gear used, and so forth, and in selected other basins by way of creel censuses. 

Although the closure of many areas and institution of catch-and-release elsewhere is 

expected to reduce extinction risk for the ESU, this risk reduction cannot be estimated 

quantitatively from the existing data sets (due to the fact that natural abundance is not being 

estimated). After the federal listing decisions, NMFS requested that CDFG prepare a Fishery 

Management and Evaluation Plan (FMEP) for the listed steelhead ESUs in California. This plan 

 

37See Footnote 25. 

285 
STEELHEAD

has not yet been done for the Southern California steelhead ESU, so the rationale for the set of 

regulations summarized above is not transparent. 

Resident O. mykiss Considerations 

Resident (nonanadromous) populations of O. mykiss were assigned to one of three 

categories for the purpose of provisionally determining ESU membership (see subsection, 

Resident Fish, in Section 1 for a description of the three categories and default assumptions 

about ESU membership). The third category consists of resident populations that are separated 

from anadromous conspecifics by recent man-made barriers such as dams without fish ladders. 

No default assumption about ESU membership was possible for case 3 populations, so here they 

are considered case by case according to available information. 

As of this writing we have few data on occurrence of resident populations and even fewer 

on genetic relationships. A provisional survey of the occurrence of case 3 populations in the 

ESU (see Appendix B, Table B-1) revealed the following: Numerous case 3 populations occur 

within the original geographic range of the Southern California steelhead ESU. All of the larger 

watersheds originally inhabited by the ESU now have major barriers completely blocking 

substantial portions of habitat (Table B-1; a major barrier is defined as a complete barrier to 

migration that has greater than 260 sq. km of watershed area lying above it). In the watershed of 

the Santa Maria River, 71% of total stream kilometers are above Twitchell Dam. The Santa 

Clara watershed has 99% of stream kilometers above Vern Freeman diversion dam. This facility 

has a fish ladder, but the ladder is currently dysfunctional due to channel migration, which has 

disconnected the ladder intake from the river’s thalweg, combined with deficient quantities and 

configurations of water releases through the facility.38 The Santa Ynez watershed, which 

probably originally harbored the strongest run of steelhead in the Southern California steelhead 

ESU, has 58% of its stream kilometers above Cachuma Dam. In each case the historical record 

has reports of steelhead ascending to and spawning in areas that are now blocked behind the 

above-mentioned dams (Titus et al. 2002). In the case of the Santa Ynez, adult O. mykiss have 

been observed to make “steelhead-like” runs from the uppermost reservoir (behind Juncal Dam) 

into the North Fork Juncal and the upper Santa Ynez for at least the past 7 years.39

All the large watersheds farther south have major barriers blocking substantial portions of 

stream habitat. Consequently, in the set of major watersheds originally inhabited by the ESU, at 

least 48% of stream kilometers are now behind barriers impassable to anadromous fish (the value 

is probably somewhat higher due to minor barriers not considered in Appendix B, Table B-1). 

At least 11 of these 15 major watersheds are known to have resident populations above the 

barriers (Table B-1). 

We do not know much about the genetic relationships of these resident populations. One 

study of genetic relationships among hatchery stocks, anadromous fish, and resident populations 

above barriers (Nielsen 2003) used selectively neutral genetic markers to assess genetic distances 

among the various categories of fish (anadromous, residualized, hatchery, etc.), but the results 

were inconclusive. However, according to the provisional survey described in Appendix B, 

 

38M. Whitman, California Department of Fish and Game, Sacramento, CA 95814. Pers. commun., 29 May 2003. 39M. Capelli, Southwest Regional Office, Santa Barbara, CA 93101. Pers. commun., 21 May 2003. 

286 
23. SOUTHERN CALIFORNIA STEELHEAD ESU 

Table B-1, at least 7 of the 11 watersheds with resident populations above major barriers are 

currently stocked with hatchery fish. It is not clear whether the stocked fish have successfully 

interbred with native fish, whether such interbreeding would have led to significant gene flow 

between the introduced and native fish, or to what extent local adaptations of the native fish 

would have been maintained by selection even if gene flow occurred. 

287 
24. California Central Valley Steelhead ESU

Summary of Previous BRT Conclusions 

Major Risk Factors and Status Indicators 

Steelhead were once widespread throughout the Central Valley (CACSS 1988, Reynolds 

et al. 1993). Steelhead require cool water in which to oversummer, and much of this habitat is 

now above impassable dams. Where steelhead are still extant, natural populations are subject to 

habitat degradation, including various effects of water development and land use practices. The 

BRT’s concerns include extirpation from most of the historical range, a monotonic decline in the 

single available time series of abundance (Table 60, Figure 190), declining proportion of wild 

fish in spawning runs, substantial opportunity for deleterious interactions with hatchery fish 

(including out-of-basin-origin stocks), various habitat problems, and lack of ongoing population 

assessments. Compared to most Chinook salmon populations in the Central Valley, steelhead 

spawning above Red Bluff Diversion Dam (RBDD) had a fairly strong negative population 

growth rate and small population size at the time of last census (1993) (Figure 191). 

Previous BRT Conclusions 

The BRT previously concluded that the California Central Valley steelhead ESU was in 

danger of extinction (Busby et al. 1996), and this opinion did not change in two status review 

updates (NMFS 1997b, 1998b). The Nimbus Hatchery and Mokelumne River Hatchery 

Table 60. Summary statistics for California Central Valley steelhead ESU trend analyses (are 90% 

confidence intervals in parentheses). 

Populationa

5-year 

meanb

5-year 

min. 

5-year 

max. λ μ

Long-term 

trend 

Short-term 

trend 

Sacramento River 

steelhead 

1,952 1,425 12,320 0.95 

(0.90, 1.02)

–0.07 

(–0.13, 0.00)

–0.09 

(–0.13, –0.06) 

NA 

Sacramento River 

winter-run Chinook 

2,191 364 65,683 0.97 

(0.87, 1.09)

–0.10 

(–0.21, 0.01)

–0.14 

(–0.19, –0.09) 

0.26 

(0.04, 0.48) 

Butte Creek springrun Chinook 4,513 67 4,513 1.30 

(1.09, 1.60)

0.11 

(–0.05, 0.28)

0.11 

(0.03, 0.19) 

0.36 

(0.03, 0.70) 

Deer Creek springrun Chinook 1,076 243 1,076 1.17 

(1.04, 1.35)

0.12 

(–0.02, 0.25)

0.11 

(0.02, 0.21) 

0.16 

(–0.01, 0.33)

Mill Creek springrun Chinook 491 203 491 1.19 

(1.00, 1.47)

0.09 

(–0.07, 0.26)

0.06 

(–0.04, 0.16) 

0.13 

(–0.07, 0.34)

a Threatened and endangered Chinook salmon populations are shown for comparison. 

b

 Note that for steelhead, the 5-year geometric mean refers to the period ending in 1993. There is insufficient recent 

data to calculate a short-term trend in abundance. 

288 
24. CALIFORNIA CENTRAL VALLEY STEELHEAD ESU 

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

2 2.5 3 3.5 4 4.5

Log10 (5-year mean population size)

μ

5

Figure 190. Abundance and growth rate of Central Valley salmonid populations. z = steelhead (above 

Red Bluff Diversion Dam); □ = spring-run Chinook; U = winter-run Chinook; ■ = other 

Chinook stocks (mostly fall runs). Error bars represent central 0.90 probability intervals for μ

estimates. Note: as defined in other sections of the status reviews, μ ≈ log (λ). 

1965 1970 1975 1980 1985 1990 1995

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2 x 104

Year

Returns

Figure 191. Returns of steelhead passing the Red Bluff Diversion Dam fish ladders, 1966–1994. These 

fish include hatchery fish from Coleman National Fish Hatchery. 

289 
STEELHEAD

steelhead stocks were excluded from the California Central Valley steelhead ESU (NMFS 

1998c). 

Listing status: Threatened. 

New Data and Updated Analyses 

Historical Distribution and Abundance 

McEwan (2001a) reviewed the status of Central Valley steelhead. Steelhead probably 

occurred from the McCloud River and other northern tributaries to Tulare Lake and the Kings 

River in the southern San Joaquin Valley. McEwan also guessed that more than 95% of 

historical spawning habitat is now inaccessible. He did not hazard a guess about current 

abundance. He guessed, on the basis of the fairly uncertain historical abundance estimates of 

Central Valley Chinook salmon reported by Yoshiyama et al. (1998), that between 1 million and 

2 million steelhead may have once spawned in the Central Valley. McEwan’s estimate is based 

on the observation that, presently, steelhead are found in almost all systems where spring-run 

Chinook salmon occur and can use elevations and gradients even more extreme than those 

spring-run Chinook use, as well as mid-elevation areas not used by spring-run Chinook. 

Steelhead should therefore have had more freshwater habitat than spring-run Chinook, and the 

sizes of steelhead populations should therefore have been roughly comparable those of springrun Chinook. 

Current Abundance 

One source of new abundance information since the last status review comes from 

midwater trawling below the confluence of the Sacramento and San Joaquin Rivers at Chipps 

Island. This trawling targets juvenile Chinook salmon; catches of steelhead are incidental. In a 

trawling season, over 2,000 20-minute tows are made. Trawling occurred from the beginning of 

August through the end of June in 1997–1998 and 1998–1999, after which trawling has occurred 

year round. Usually, 10 tows are made per day, and trawling occurs several days per week. 

Since the 1998 broodyear, all hatchery steelhead have been ad-clipped. Trawl catches of 

steelhead provide an estimate of the proportion of wild to hatchery fish, which, combined with 

estimates of basinwide hatchery releases, provide an estimator for wild steelhead production: 

N

C

N

w

= C w

h

h (24)

where Nw is the number of wild steelhead, Cw and Ch are the total catches of wild and hatchery 

steelhead, and Nh is the number of hatchery fish released. The accuracy of the estimate depends 

on the assumption that hatchery and natural steelhead are equally vulnerable to the trawl gear. In 

particular, if hatchery fish are more vulnerable to the gear, natural production is underestimated. 

290 
24. CALIFORNIA CENTRAL VALLEY STEELHEAD ESU 

Table 61. Estimated natural production of steelhead juveniles from the Central Valley. 

Wild female spawners 

Year Cw/Ch 

a Nr (millions)b Nw (thousands)c ESSd

 = 1% ESSd = 5% ESSd = 10%

1998 0.300 1.12 336 6,720 1,344 672 

1999 0.062 1.51 94 1,872 374 187 

2000 0.083 1.38 115 2,291 458 229 

Average 0.148 1.34 181 3,628 726 363 a Cw/Ch = ratio of unclipped to clipped steelhead. 

b Nr = total hatchery releases. c Nw = estimated natural production. 

d

 ESS = egg-to-smolt survival. 

Catches of steelhead are sporadic—most sets catch no steelhead, but a few sets catch up 

to four steelhead. To estimate the mean and variance of Cw/Ch, the trawl data sets were 

resampled with replacement 1,000 times. The mean Cw/Ch ranged from 0.06 to 0.30, and 

coefficients of variation ranged from 16% to 37% of the means. 

From such calculations, it appears that about 100,000–300,000 steelhead juveniles 

(roughly, smolts) are produced naturally each year in the Central Valley (Table 61). If we make 

the fairly generous assumptions (in the sense of generating large estimates of spawners) that 

average fecundity is 5,000 eggs per female, 1% of eggs survive to reach Chipps Island, and 

181,000 smolts are produced (the 1998–2000 average); about 3,628 female steelhead spawn 

naturally in the entire Central Valley. This can be compared with McEwan’s (2001a) estimate of 

1 million to 2 million spawners before 1850 and 40,000 spawners in the 1960s. Table 61 shows 

the effects of different assumptions about survival on estimates of female spawner abundance. 

Another source of information comes from screw trap operations at Knights Landing on 

the lower Sacramento River, just above the confluence with the Feather River (Snider and Titus 

2000a, 2000b, 2000c). Over the period 1995–1999, estimates of the natural production for the 

areas above Knights Landing averaged 9,800 yearling steelhead outmigrants (a range of 7,260–

11,700). This level of production is about 5% of the total production as estimated above, and 

may be a substantial underestimate due to the application of trap efficiency estimates generated 

from recaptures of marked Chinook juveniles, which probably are less able to avoid traps. 

Nobriga and Cadrett (2001) analyzed captures of steelhead in trawls at Chipps Island and 

in fish salvage facilities associated with water diversions in the southern delta. They computed 

average daily catch of hatchery and wild steelhead per unit effort and used these numbers to 

estimate the percentage of hatchery fish. They found that hatchery steelhead comprised 63–77% 

of the trawl catch of steelhead at Chipps Island (compared to 77–92% estimated from the 

resampling method described above) and generally lower percentages in the south delta, which is 

not surprising because the bulk of hatchery production comes out of the Sacramento River basin. 

This alternative analysis of the Chipps Island trawl data suggests that wild steelhead are roughly 

threefold more abundant than the resampling analysis discussed above. 

291 
STEELHEAD

Current Distribution 

Recent spawner surveys of small Sacramento River tributaries (Mill, Deer, Antelope, 

Clear, and Beegum creeks; Moore 2001) and incidental captures of juvenile steelhead during 

Chinook salmon monitoring (Calaveras, Cosumnes, Stanislaus, Tuolumne, and Merced rivers) 

confirmed that steelhead are widespread, if not abundant, throughout accessible streams and 

rivers. McEwan (2001a) reviews much of this information. Figure 192 cartographically 

summarizes the information on steelhead distribution in Central Valley streams; details are listed 

in Table 62. 

CDFG (2003a) reported trawl captures of O. mykiss at Mossdale on the lower San 

Joaquin River (below the confluence of the Tuolumne, Stanislaus, and Merced rivers). Because 

the Mossdale area is not suitable habitat for resident O. mykiss, these fish are assumed to be 

steelhead smolts. Between 2 and 30 fish per year were captured from 1988 to 2002. Rotary 

screw trap data suggests that the bulk of this production comes from the Stanislaus River, 

although some smolts were captured in the Merced and Tuolumne rivers as well. 

Resident O. mykiss Considerations 

Coastal O. mykiss is widely distributed in the Central Valley Basin. Roughly half of the 

trout habitat (by area) in the Central Valley is above dams that are impassable to fish; higher 

elevation habitats appear to support quite high densities of trout, ranging from a few hundred to a 

few thousand 4′′–6′′ fish per kilometer (see Appendix B, Table B-2). 

Several areas of substantial uncertainty make interpreting this information difficult. First, 

it is not clear how anadromous and nonanadromous coastal O. mykiss interacted in the Central 

Valley before the dam-building era. In other systems, anadromous and nonanadromous 

O. mykiss forms can exist within populations, while in other systems these groups can be 

reproductively isolated despite nearly sympatric distributions within rivers (Zimmerman and 

Reeves 2000). Second, hatchery produced O. mykiss have been widely stocked throughout the 

Central Valley, Sierra Nevada, and southern Cascades. It is possible that this stocking has had 

deleterious effects on native wild trout populations, although limited information indicates that 

native trout populations remain in some areas that have received stocked fish (Nielsen et al. 

2000). 

We suspect that some coastal O. mykiss populations that are above man-made barriers 

could be part of the California Central Valley steelhead ESU, because these populations were 

probably exhibiting some degree of anadromy and interacting with each other on evolutionary 

time scales prior to barrier construction. Due to a lack of data, we cannot, however, identify any 

particular resident populations as part of the California Central Valley steelhead ESU. 

292 
24. CALIFORNIA CENTRAL VALLEY STEELHEAD ESU 

Butte Creek

Mill Creek

Feathe River

Dr Creek

Tuolumne River

Paynes Creek

Cosumnes River

Clea Creek

Antelope Creek

American River

Beegum Creek

Battl Creek

Thomes Creek

Merced River

Salt Creek

0 6 30 0 120 Kilometers

Figure 192. Central Valley tributaries known (dark gray lines) or suspected (medium gray lines) to be 

used by steelhead adults. Source: Kerrie Pipal (National Marine Fisheries Service, Santa Cruz 

Laboratory) assembled this information from agency and consultant reports and discussions with 

California Department of Fish and Game field biologists. 

293 
Table 62. Summary of distribution information for steelhead in the California Central Valley steelhead ESU. 

System /tributary 

Current 

presence 

Most recent 

documented 

date of 

presence 

Count/ 

life stage Comments 

Sacramento River 

Clear Creek Yes 2001 Adults/ 

juveniles 

Snorkel surveys and redd counts, rotary screw traps 

J. Newton

Rock Creek Probable 2001 Adults/ 

juveniles 

Creek used for spawning M. Berryb

Salt Creek Probable 2001 Adults/ 

juveniles 

Possible spawning; non-natal rearing M. Berryb

Sulphur Creek Probable 2001 Adults/ 

juveniles 

Creek used for spawning M. Berryb

Olney Creek Probable 2001 Adults/ 

juveniles 

Spawning, nonnatal rearing M. Berryb

Stillwater Creek Probable – – Nonnatal rearing M. Berryb Cow Creek + tributaries Probable 1992 – Suitable habitat, access problems CDFG (19

Cottonwood Creek Probable – – CDFG (19Beegum Creek Yes 2001 Adults Moore (20South Fork Cottonwood Creek 

Possible – – Large populations of “rainbow trout” M. Berryb

Bear Creek Possible – – CDFG (19

Battle Creek Yes 2002 – Kier & As

Newtona

Paynes Creek Yes 2002 Adults Self-sustaining population unlikely M. Berryb

Antelope Creek Yes 2001 Adults + 

redds 

Moore (20

Mill Creek Yes 2001 Adults + 

redds 

Small numbers counted. Moore (20

Elder Creek Possible No recent 

surveys 

– Resident trout present CDFG (19

Thomes Creek Probable 1969 and 

2002 

– Used by Chinook salmon, “trout” 

observed 

Puckett (1M. Berryb

294 
Table 62 continued. Summary of distribution information for steelhead in the California Central Valley steelhead ESU. 

System /tributary 

Current 

presence 

Most recent 

documented 

date of 

presence 

Count/ 

life stage Comments 

Deer Creek Yes 2001 Adults + 

redds 

Moore (20

Rice Creek Yes 1998 Juveniles Maslin et Big Chico Creek Yes – – CDFG (19

Butte Creek Yes 2000 – Report confirms steelhead presence, no 

details 

USFWS (2

Feather River Yes 1998 Young of year 

+ Juveniles 

Screw trap captures CDWR (1

Yuba River Yes 1998 – Report confirms steelhead presence, no 

details 

IEP (1998

Deer Creek (Yuba tributary) 

Yes 1993 Adults Dive survey StreamNet 

(http://ww

Dry Creek Yes – – Secret and Miners Ravines CDWR (2

American River Yes 2002 Adults + 

redds 

Counted redds, estimated number of adults based on redd counts 

Hannon an

Putah Creek Yes 2000 – Very small numbers of adult steelhead 

make their way to the base of Monticello Dam 

Moore (20

San Joaquin River

Cosumnes River Yes 1995 – Smolts salvaged from drying pools Nobriga (1

Mokelumne River Yes 2001 Adults + 

juveniles 

Workman 

Calaveras River Yes 2001 Adults + 

juveniles 

Several reports list presence, but do not give any details; angler reports/photos. 

G. Castillo

Stanislaus River Yes 2001 Young of year 

and age-1+ 

Kennedy (

Tuolumne River Yes 2001 Juveniles Incidental rotary screw trap captures J. NewtonMerced River Possible 2002 Juveniles Incidental rotary screw trap captures, 

large trout caught by anglers, enter hatchery 

D. Vogeld 

295 
Table 62 continued. Summary of distribution information for steelhead in the California Central Valley steelhead ESU. 

a J. Newton, USFWS, Red Bluff Fish and Wildlife Office, Red Bluff, CA. Pers. commun., 27August 2002. b M. Berry, California Department of Fish and Game, Redding, CA. Pers. commun., 8 October 2002. c G. Castillo, USFWS, Stockton, CA. Pers. commun., 3 Mar 2004. d D. Vogel, NRC, Red Bluff, CA. Pers. commun., 7 June 2002. e M. Cozart, Merced River Hatchery, Snelling, CA. Pers. commun., 5 September 2002. 

296 
24. CALIFORNIA CENTRAL VALLEY STEELHEAD ESU 

Harvest Impacts 

Steelhead are caught in freshwater recreational fisheries, and CDFG estimates the number 

of fish caught. Because the sizes of Central Valley steelhead populations are unknown, however, 

the impact of these fisheries is unknown. According to a CDFG creel census, the great majority 

(93%) of steelhead catches occur on the American and Feather rivers, sites of steelhead 

hatcheries (CDFG 2001d). In 2000, 1,800 steelhead were retained, and 14,300 were caught and 

released. The total number of steelhead contacted might be a significant fraction of basinwide 

escapement, so even low catch-and-release mortality may pose a problem for wild populations. 

Additionally, steelhead trout fisheries on some tributaries and the mainstem Sacramento River 

may affect some steelhead juveniles. 

The State of California’s proposed Fishery Management and Evaluation Plan (part of the 

requirements to obtain ESA coverage for in-river sport fisheries) was recently rejected by NOAA 

Fisheries, mostly because of the inadequacy of existing and proposed monitoring of fisheries 

impacts. 

New Hatchery Information 

There is little new information pertaining to hatchery stocks of steelhead in the Central 

Valley. Figures 193 and 194 show the releases and returns of steelhead to and from Central 

Valley hatcheries. As discussed in the subsection, Current Abundance, hatchery steelhead 

juveniles dominate catches in the Chipps Island trawl, suggesting that hatchery production is 

large relative to natural production. Note that Mokelumne River Hatchery and Nimbus Hatchery 

stocks are not part of the California Central Valley steelhead ESU due to broodstock source and 

genetic, behavioral, and morphological similarity to Eel River stocks. Categorization of Central 

Valley steelhead hatchery stocks (SSHAG 2003) can be found in Appendix B, Table B-3. 

Comparison with Previous Data 

The few new pieces of information do not indicate a dramatic change in the status of the 

California Central Valley steelhead ESU. The Chipps Island trawl data suggest that the 

population decline evident in the Red Bluff Diversion Dam counts, and the previously noted 

decline in the proportion of wild fish, is continuing. The fundamental habitat problems are little 

changed, with the exception of some significant restoration actions on Butte Creek. There is still 

a nearly complete lack of steelhead monitoring in the Central Valley. 

297 
STEELHEAD

Coleman National Fish Hatchery

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

3,000,000

1948 1958 1968 1978 1988 1998

Releases

Mokelumne Fish Hatchery

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

3,000,000

1948 1958 1968 1978 1988

Year

Releases

Feather Fish Hatchery

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

3,000,000

1948 1958 1968 1978 1988 1998

Nimbus Fish Hatchery

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

3,000,000

1948 1958 1968 1978 1988 1998

Year

Figure 193. Releases of steelhead from Central Valley hatcheries. 

298 
24. CALIFORNIA CENTRAL VALLEY STEELHEAD ESU 

Coleman National Fish Hatchery

0

1,000

2,000

3,000

4,000

5,000

6,000

1950 1960 1970 1980 1990 2000

Returns

Mokelumne Fish Hatchery

0

1,000

2,000

3,000

4,000

5,000

6,000

1950 1960 1970 1980 1990

Year

Returns

Feather Fish Hatchery

0

1,000

2,000

3,000

4,000

5,000

6,000

1950 1960 1970 1980 1990 2000

Nimbus Fish Hatchery

0

1,000

2,000

3,000

4,000

5,000

6,000

1950 1960 1970 1980 1990 2000

Year

Figure 194. Returns of steelhead to Central Valley hatcheries. 

299 
25. Steelhead BRT Conclusions 

Section 3 of the ESA allows listing of “species, subspecies, and distinct population 

segments.” The option to list subspecies is not available for Pacific salmon, since no formally 

recognized subspecies exist. However, a number of subspecies have been identified for 

O. mykiss, including two that occur in North America and have anadromous populations. 

According to Behnke (1992), O. mykiss irideus (the “coastal” subspecies) includes coastal 

populations from Alaska to California (including the Sacramento River), while O. mykiss 

gairdneri (the “inland” subspecies) includes populations from the interior Columbia, Snake, and 

Fraser rivers. Both subspecies thus include populations within the geographic range of this 

updated status review, but both also include northern populations outside the geographic range 

considered here. The BRT did not attempt to evaluate extinction risk to O. mykiss at the species 

or subspecies level; instead, we evaluated risk at the distinct population segment or ESU level, as 

for the other species considered in this report. 

Snake River Basin Steelhead ESU 

A majority (over 70%) of the BRT votes for this ESU fell in the “likely to become 

endangered” category, with small minorities falling in the “danger of extinction” and “not likely 

to become endangered” categories (Table 63). The BRT did not identify any extreme risks for 

this ESU but found moderate risks in all the VSP categories (mean risk matrix scores ranged 

from 2.5 for spatial structure to 3.2 for growth rate/productivity) (Table 64). The continuing 

depressed status of B-run populations was a particular concern. Paucity of information on adult 

spawning escapements to specific tributary production areas makes a quantitative assessment of 

viability for this ESU difficult. As indicated in previous status reviews, the BRT remained 

Table 63. Tally of FEMAT vote distribution regarding the status of 10 steelhead ESUs reviewed. Each 

of 16 BRT members allocated 10 points among the three status categories. 

ESU 

Danger of 

extinction 

Likely to become 

endangered 

Not likely to become 

endangered 

Snake Rivera 14 103 23 

Upper Columbiaa 75 62 3 

Middle Columbiaa 1 71 68 

Lower Columbiab 10 110 30 

Upper Willametteb 7 106 37 

Northern California 18 119 23 

Central California Coast 40 111 9 

South-Central California 40 109 11 

Southern California 129 31 0 

Central Valley 106 54 0 a Votes tallied for 14 BRT members.

b

 Votes tallied for 15 BRT members. 

300 
25. STEELHEAD BRT CONCLUSIONS

Table 64. Summary of risk scores (1 = low to 5 = high) for four VSP categories (see subsection, Factors 

Considered in Status Assessments, for a description of the risk categories) for the 10 steelhead 

ESUs reviewed. Data presented are means (range). 

ESU Abundance 

Growth 

rate/productivity 

Spatial structure 

and connectivity Diversity 

Snake River 3.1 (2–4) 3.2 (2–4) 2.5 (1–4) 3.1 (2–4) 

Upper Columbia 3.5 (2–4) 4.3 (3–5) 3.1 (2–4) 3.6 (2–5) 

Middle Columbia 2.7 (2–4) 2.6 (2–3) 2.6 (2–4) 2.5 (2–4) 

Lower Columbia 3.3 (2–5) 3.3 (3–4) 2.7 (2–4) 3.0 (2–4) 

Upper Willamette 2.8 (2–4) 2.9 (2–4) 2.9 (2–4) 2.6 (2–3) 

Northern California 3.7 (3–5) 3.3 (2–4) 2.2 (1–4) 2.5 (1–4) 

Central California Coast 3.9 (3–5) 3.9 (3–5) 3.6 (2–5) 2.8 (2–4) 

South-Central California 3.7 (2–5) 3.3 (2–4) 3.9 (3–5) 2.9 (2–4) 

Southern California 4.8 (4–5) 4.3 (3–5) 4.8 (4–5) 3.6 (2–5) 

Central Valley 4.4 (4–5) 4.3 (4–3) 4.2 (2–5) 3.6 (2–5) 

concerned about the replacement of naturally produced fish by hatchery fish in this ESU; 

naturally produced fish now make up only a small fraction of the total adult run. Again, lack of 

key information considerably complicates the risk analysis. Although several large production 

hatcheries for steelhead exist throughout this ESU, relatively few data exist regarding the 

numbers and relative distribution of hatchery fish that spawn naturally, or the consequences of 

such spawnings when they do occur. 

On a more positive note, sharp upturns in 2000 and 2001 in adult returns in some 

populations and evidence for high smolt-adult survival indicate that populations in this ESU are 

still capable of responding to favorable environmental conditions. In spite of the recent 

increases, however, abundance in most populations for which there are adequate data are well 

below interim recovery targets (NMFS 2002b). 

Based on the provisional framework discussed in the general Introduction to this report, 

the BRT assumed as a working hypothesis that resident fish below historical barriers are part of 

this ESU, while those above long-standing natural barriers (e.g., in the Palouse and Malad rivers) 

are not. Recent genetic data suggest that native resident O. mykiss above Dworshak Dam on the 

North Fork Clearwater River should be considered part of this ESU, but hatchery rainbow trout 

that have been introduced to that and other areas would not. The BRT did not attempt to resolve 

the ESU status of resident fish residing above the Hells Canyon Dam complex, as little new 

information is available relevant to this issue. However, Kostow (2003) suggested that, based on 

substantial ecological differences in habitat, the anadromous O. mykiss that historically occupied 

basins upstream of Hells Canyon (e.g., Powder, Burnt, Malheur, Owhyee rivers) may have been 

in a separate ESU. For many BRT members, the presence of relatively numerous resident fish 

mitigated the assessment of extinction risk for the ESU as a whole. 

Upper Columbia River Steelhead ESU 

A slight majority (54%) of the BRT votes for this ESU fell in the “danger of extinction” 

category, with most of the rest falling in the “likely to become endangered” category (Table 63). 

301 
STEELHEAD

The most serious risk identified for this ESU was growth rate/productivity (mean score 4.3); 

scores for the other VSP factors were also relatively high, ranging from 3.1 (spatial structure) to 

3.6 (diversity) (Table 64). The last 2 to 3 years have seen an encouraging increase in the number 

of naturally produced fish in this ESU. However, the recent mean abundance in the major basins 

is still only a fraction of interim recovery targets (NMFS 2002b). Furthermore, overall adult 

returns are still dominated by hatchery fish, and detailed information is lacking regarding 

productivity of natural populations. The ratio of naturally produced adults to the number of 

parental spawners (including hatchery fish) remains low for upper Columbia steelhead. The 

BRT did not find data to suggest that the extremely low replacement rate of naturally spawning 

fish (estimated adult:adult ratio was only 0.25–0.3 at the time of the last status review update) 

has improved substantially.

Based on the provisional framework discussed in Section 1, Introduction, the BRT 

assumed as a working hypothesis that resident fish below historical barriers are part of this ESU, 

while those above long-standing natural barriers (e.g., in the Entiat, Methow, and perhaps 

Okanogan basins) are not. Resident fish potentially occur in all areas in the ESU used by 

steelhead. Case 3 resident fish above Conconully Dam are of uncertain ESU affinity. The BRT 

did not attempt to resolve the ESU status of resident fish residing above Grand Coulee Dam, 

because little new information is available relevant to this issue. Possible ESU scenarios for 

these fish include 1) they were historically part of the ESU and many of the remnant resident 

populations still are part of this ESU; 2) they were historically part of the ESU but no longer are, 

due to either introductions of hatchery rainbow trout or rapid evolution in a novel environment; 

or 3) they were historically part of a separate ESU. For many BRT members, the presence of 

relatively numerous resident fish mitigated the assessment of extinction risk for the ESU as 

a whole. 

Middle Columbia River Steelhead ESU 

A slight majority (51%) of the BRT votes for this ESU fell in the “likely to become 

endangered” category, with a substantial minority (49%) falling in the “not likely to become 

endangered” category (Table 63). The BRT did not identify any extreme risks for this ESU but 

found moderate risks in all the VSP categories (mean risk matrix scores ranged from 2.5 for 

diversity to 2.7 for abundance) (Table 64). 

This ESU proved difficult to evaluate for two reasons. First, the status of different 

populations within the ESU varies greatly. On the one hand, abundance in two major basins, the 

Deschutes and John Day, is relatively high and over the last 5 years is close to or slightly over 

the interim recovery targets (NMFS 2002b). On the other hand, steelhead in the Yakima Basin, 

once a large producer of steelhead, remain severely depressed (10% of the interim recovery 

target), in spite of increases in the last 2 years. Furthermore, in recent years escapement to 

spawning grounds in the Deschutes River has been dominated by stray, out-of-basin (and largely 

out-of-ESU) fish—which raises substantial questions about genetic integrity and productivity of 

the Deschutes population. The John Day is the only basin of substantial size in which production 

is clearly driven by natural spawners. For the other major basin in the ESU (the Klickitat), no 

quantitative abundance information is available. The other difficult issue centered on how to 

evaluate contribution of resident fish, which according to Kostow (2003) and other sources are 

302 
25. STEELHEAD BRT CONCLUSIONS

very common in this ESU and may greatly outnumber anadromous fish. The BRT concluded 

that the relatively abundant and widely distributed resident fish mitigated extinction risk in this 

ESU somewhat. However, due to significant threats to the anadromous component the majority 

of BRT members concluded the ESU was likely to become endangered. 

Historically, resident fish are believed to have occurred in all areas in the ESU used by 

steelhead, although current distribution is more restricted. Based on the provisional framework 

discussed in Section 1, Introduction, the BRT assumed as a working hypothesis that resident fish 

below historical barriers are part of this ESU, while those above long-standing natural barriers 

(e.g., in Deschutes and John Day basins) are not. Case 3 resident fish above Condit Dam in the 

Little White Salmon, above Pelton and Round Butte dams (but below natural barriers) in the 

Deschutes, and above irrigation dams in the Umatilla rivers are of uncertain ESU status. 

Lower Columbia River Steelhead ESU 

A large majority (over 73%) of the BRT votes for this ESU fell in the “likely to become 

endangered” category, with small minorities falling in the “danger of extinction” and “not likely 

to become endangered” categories (Table 63). The BRT found moderate risks in all the VSP 

categories, with mean risk matrix scores ranging from 2.7 for spatial structure to 3.3 for both 

abundance and growth rate/productivity) (Table 64). All of the major risk factors identified by 

previous BRTs still remain. Most populations are at relatively low abundance, and those with 

adequate data for modeling are estimated to have a relatively high extinction probability. Some 

populations, particularly summer run, have shown higher returns in the last 2 to 3 years. The 

WLC-TRT (Myers et al. 2002) has estimated that at least four historical populations are now 

extinct. The hatchery contribution to natural spawning remains high in many populations. 

Based on the provisional framework discussed in the general introduction to this report, 

the BRT assumed as a working hypothesis that resident fish below historical barriers are part of 

this ESU, while those above long-standing natural barriers (e.g., in upper Clackamas, Sandy, and 

some of the small tributaries of the Columbia River gorge) are not. Case 3 resident fish above 

dams on the Cowlitz, Lewis, and Sandy rivers are of uncertain ESU status. 

Upper Willamette River Steelhead ESU 

The majority (over 71%) of the BRT votes for this ESU fell in the “likely to become 

endangered” category, with small minorities falling in the “danger of extinction” and “not likely 

to become endangered” categories (Table 63). The BRT did not identify any extreme risks for 

this ESU but found moderate risks in all the VSP categories (mean risk matrix scores ranged 

from 2.6 for diversity to 2.9 for both spatial structure and growth rate/productivity) (Table 64). 

On a positive note, after a decade in which overall abundance (Willamette Falls count) hovered 

around the lowest levels on record, adult returns for 2001 and 2002 were up significantly, on par 

with levels seen in the 1980s. Still, the total abundance is small for an entire ESU, resulting in a 

number of populations that are each at relatively low abundance. The recent increases are 

encouraging, but whether they can be sustained is uncertain. The BRT considered it a positive 

sign that releases of the “early” winter-run hatchery population have been discontinued, but 

remained concerned that releases of nonnative summer-run steelhead continue. 

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STEELHEAD

Because coastal cutthroat trout is a dominant species in the basin, resident O. mykiss are 

not as widespread here as in areas east of the Cascades. Resident fish below barriers are found in 

the Pudding/Molalla, Lower Santiam, Calapooia, and Tualatin drainages, and these would be 

considered part of the steelhead ESU based on the provisional framework discussed in the 

Introduction (page 1). Resident fish above Big Cliff and Detroit Dams on the North Fork 

Santiam and above Green Peter Dam on the South Fork Santiam are of uncertain ESU affinity. 

Although no obvious physical barrier separates populations upstream of the Calapooia from 

those lower in the basin, resident O. mykiss in these upper reaches of the Willamette Basin are 

quite distinctive both phenotypically and genetically and are not considered part of the Upper 

Willamette River steelhead ESU. 

Northern California Steelhead ESU 

The majority (74%) of BRT votes were for “likely to become endangered,” with the 

remaining votes split about equally between “in danger of extinction” and “not warranted” 

(Table 63). Abundance and productivity were of some concern (scores of 3.7 and 3.3 in the risk 

matrix); spatial structure and diversity were of lower concern (scores of 2.2 and 2.5); although at 

least one BRT member gave scores as high as 4 for each of these risk metrics (Table 64). 

The BRT considered the lack of data for this ESU to be a source of risk due to 

uncertainty. The lack of recent data is particularly acute for winter runs. Although there are 

older data for several of the larger river systems that imply run sizes became much reduced since 

the early 20th century, there are no recent data suggesting much of an improvement. 

Based on the provisional framework discussed in Section 1, Introduction, the BRT 

assumed as a working hypothesis that resident fish below historical barriers are part of the 

Northern California Coast steelhead ESU, while those above long-standing natural barriers are 

not. Historically, resident fish are believed to have occurred in all areas in the ESU steelhead 

use, although current distribution is more restricted. Resident fish above recent (usually manmade) barriers—including Robert W. Matthews Dam on the Mad River and Scott Dam on the 

Eel River—but below natural barriers are of uncertain ESU affinity. In this ESU, the inclusion 

of resident fish would not greatly increase the total numbers of fish, and the resident fish have 

not been exposed to large amounts of hatchery stocking. 

Central California Coast Steelhead ESU 

The majority (69%) of BRT votes were for “likely to become endangered,” and another 

25% were for “in danger of extinction” (Table 63). Abundance and productivity were of 

relatively high concern (mean score of 3.9 for each, with a range of 3 to 5 for each), and spatial 

structure was also of concern (score 3.6) (Table 64). Predation by pinnipeds at river mouths and 

during the ocean phase was noted as a recent development posing significant risk. 

There were no time-series data for the Central California Coast steelhead ESU. A variety 

of evidence suggested the ESU’s largest run (the Russian River winter steelhead run) has been, 

and continues to be, reduced in size. Concern was also expressed about populations in the 

southern part of the ESU’s range—notably those in Santa Cruz County and the South Bay area. 

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25. STEELHEAD BRT CONCLUSIONS

Based on the provisional framework discussed in Section 1, Introduction, the BRT 

assumed as a working hypothesis that resident fish below historical barriers are part of the 

Central California Coast steelhead ESU, while those above long-standing natural barriers are not. 

Historically, resident fish are believed to have occurred in all areas in the ESU used by steelhead, 

although current distribution is more restricted. Resident fish above recent (usually man-made) 

barriers—including Warm Springs Dam on Dry Creek, Russian River; Coyote Dam on the East 

Fork Russian River; Seeger Dam on Lagunitas Creek; Peters Dam on Nicasio Creek, Lagunitas 

Creek; and Standish Dam on Coyote Creek—but below natural barriers are of uncertain ESU 

affinity. In this ESU, an estimated 22% of historical habitat is behind recent barriers. The only 

relevant biological information about the populations above these barriers pertains to Alameda 

Creek, and suggests that some but not all populations above dam 1 are genetically similar to 

populations within the ESU. For some BRT members, the presence of resident fish mitigated the 

assessment of extinction risk for the ESU as a whole. 

South-Central California Coast Steelhead ESU 

The majority (68%) of BRT votes were for “likely to become endangered,” and another 

25% were for “in danger of extinction” (Table 63). The strongest concern was for spatial 

structure (score 3.9; range 3–5), but abundance and productivity were also a concern (Table 64). 

The cessation of plants to the South-Central California Coast steelhead ESU from the Big Creek 

Hatchery (Central California Coast steelhead ESU) was noted as a positive development, 

whereas continued predation from sport fishers was considered negative. 

New data suggest that steelhead populations exist in most streams within the geographic 

boundaries of the ESU; however, the BRT was concerned that the two largest river systems—the 

Pajaro and Salinas basins—are much degraded and have steelhead runs much reduced in size. 

The BRT also expressed concern that these two large systems are ecologically distinct from the 

populations in the Big Sur area and San Luis Obispo County; thus their degradation affects the 

ESU’s spatial structure and diversity. Much discussion centered on the Carmel River data set, 

including the effects of drought in the 1980s, the population’s current dependence on intensive 

management of the river system, and the population’s vulnerability to future droughts. 

Based on the provisional framework discussed in Section 1, Introduction, the BRT 

assumed as a working hypothesis that resident fish below historical barriers are part of the SouthCentral California Coast steelhead ESU, while those above long-standing natural barriers are not. 

Historically, resident fish are believed to have occurred in all areas in the ESU steelhead use, 

although current distribution is more restricted. Resident fish above recent (usually man-made) 

barriers—including San Antonia, Nacimiento, and Salinas dams on the Salinas River; Los Padres 

Dam on the Carmel River; Whale Rock Dam on Old Creek; and Lopez Dam on Arroyo Grande 

Creek—but below natural barriers are of uncertain ESU affinity. In this ESU, little of the 

historical habitat is behind recent barriers, and most of that is on the Salinas River. For some 

BRT members, the presence of resident fish mitigated the assessment of extinction risk for the 

ESU as a whole. 

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STEELHEAD

Southern California Steelhead ESU 

The majority (81%) of BRT votes were for “in danger of extinction,” with the remaining 

19% of votes for “likely to become endangered” (Table 63). Extremely strong concern was 

expressed for abundance, productivity, and spatial structure (mean scores of 4.8, 4.3, and 4.8, 

respectively, in the risk matrix); diversity was also of concern (mean score of 3.6) (Table 64). 

The BRT expressed concern about the lack of data on the Southern California steelhead 

ESU, about uncertainty as to the metapopulation dynamics in the southern part of the ESU’s 

range, and about the fish’s nearly complete extirpation from the southern part of the range. 

Several members were concerned and uncertain about the relationship between the population in 

Sespe Canyon, which is supposedly a sizeable population, and the small run size passing through 

the Santa Clara River, which connects the Sespe to the ocean. There was some skepticism that 

flows in the Santa Maria River were sufficient to allow fish passage from the ocean to the 

Sisquoc River, another “stronghold” of O. mykiss in the ESU. 

Based on the provisional framework discussed in Section 1, Introduction, the BRT 

assumed as a working hypothesis that resident fish below historical barriers are part of the 

Southern California steelhead ESU, while those above long-standing natural barriers are not. 

Historically, resident fish are believed to have occurred in all areas in the ESU steelhead use, 

although current distribution is more restricted. Resident fish above recent (usually man-made) 

barriers—including Twitchell Dam on the Cuyama River, Bradbury Dam on the Santa Ynez 

River, Casitas Dam on Coyote Creek and Ventura River, Matilija Dam on Matilija Creek and 

Ventura River, Santa Felicia Dam on Piru Creek and Santa Clara River, and Casitac Dam on 

Casitac Creek and Santa Clara River—but below natural barriers are of uncertain ESU affinity. 

In this ESU, a large portion of the original area is behind barriers, and the few density estimates 

that are available from this ESU indicate that the inclusion of area above recent barriers would 

substantially increase the number of fish in the ESU. Due to the extremely low numbers of 

anadromous fish in this ESU, it is possible that above-barrier populations contribute a significant 

number of fish to the below-barrier population by spill over. For some BRT members, the 

presence of resident fish mitigated the assessment of extinction risk for the ESU as a whole. 

California Central Valley Steelhead ESU 

The majority (66%) of BRT votes were for “in danger of extinction,” and the remainder 

was for “likely to become endangered” (Table 63). Abundance, productivity, and spatial 

structure were of highest concern (4.2–4.4), although diversity considerations were of significant 

concern (3.6) (Table 64). All categories received a 5 from at least one BRT member. 

The BRT was highly concerned that what little new information was available indicated 

that the monotonic decline in total abundance and in the proportion of wild fish in the California 

Central Valley steelhead ESU was continuing. Other major concerns included the loss of the 

vast majority of historical spawning areas above impassable dams, the lack of any steelheadspecific status monitoring, and the significant production of out-of-ESU steelhead by the Nimbus 

and Mokelumne river fish hatcheries. The BRT viewed the anadromous life history form as a 

critical component of diversity within the ESU and did not place much importance on sparse 

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information suggesting widespread and abundant O. mykiss populations in areas above 

impassable dams. Dams both reduce the scope for expression of the anadromous life history 

form, thereby greatly reducing the abundance of anadromous O. mykiss, and prevent exchange of 

migrants among resident populations, a process presumably mediated by anadromous fish. 

Based on the provisional framework discussed in the general Introduction to this report, 

the BRT assumed as a working hypothesis that resident fish below historical barriers are part of 

the California Central Valley steelhead ESU, while those above long-standing natural barriers 

are not. Historically, resident fish are believed to have occurred in all areas in the ESU steelhead 

use, although current distribution is more restricted. Resident fish above recent (usually manmade) barriers—including Shasta Dam on the Upper Sacramento River, Whiskeytown Dam on 

Clear Creek, Black Butte Dam on Stony Creek, Oroville Dam on the Feather River, Englebright 

Dam on the Yuba River, Camp Far West Dam on the Bear River, Nimbus Dam on the American 

River, Commanche Dam on the Mokelumne River, New Hogan Dam on the Calaveras River, 

Goodwin Dam on the Stanislaus River, La Grange Dam on the Tuolumne River, and Crocker 

Diversion Dam on the Merced River—but below natural barriers are of uncertain ESU affinity. 

As noted above, collectively these dams have isolated a large fraction of historical steelhead 

habitat, and resident fish above the dams may outnumber ESU fish from below the dams. 

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308 
COHO SALMON

309 
STEELHEAD

310 
26. Background and History 

of Coho Salmon Listings 

Coho salmon (Oncorhynchus kisutch) is a widespread species of Pacific salmon, 

occurring in most major river basins around the Pacific Rim from Monterey Bay in California 

north to Point Hope, Alaska; through the Aleutians; and from the Anadyr River in Russia south 

to Korea and northern Hokkaido, Japan (Laufle et al. 1986). From central British Columbia 

south, the vast majority of coho salmon adults are 3-year-olds, having spent approximately 18 

months in freshwater and 18 months in salt water (Gilbert 1912, Pritchard 1940, Sandercock 

1991). The primary exceptions to this pattern are “jacks,” sexually mature males that return to 

freshwater to spawn after only 5 to 7 months in the ocean. However, in southeast and central 

Alaska, the majority of coho salmon adults are 4-year-olds, having spent an additional year in 

freshwater before going to sea (Godfrey et al. 1975, Crone and Bond 1976). The transition zone 

between predominantly 3- and 4-year-old adults occurs somewhere between central British 

Columbia and southeast Alaska. 

With the exception of spawning habitat, which consists of small streams with stable 

gravels, summer and winter freshwater habitats most preferred by coho salmon consist of quiet 

areas with low flow, such as backwater pools, beaver ponds, dam pools, and side channels 

(Reeves et al. 1989). Habitats used during winter generally have greater water depth than those 

used in summer and also have greater amounts of large woody debris. West Coast coho smolts 

typically leave freshwater in the spring (April to June) and when sexually mature re-enter 

freshwater from September to November and spawn from November to December and 

occasionally into January (Sandercock 1991). Stocks from British Columbia, Washington, and 

the Columbia River often have very early runs (entering rivers in July or August) or late runs 

(spawning into March), in addition to normally timed runs. 

For purposes of ESA listings, the status of coho salmon has been reviewed many times, 

beginning in 1990. The first two reviews occurred in response to petitions to list coho salmon in 

the lower Columbia River and Scott and Waddell creeks in central California. These reviews 

concluded that NMFS could not identify any populations that warranted protection under the 

ESA in the lower Columbia River (Johnson et al. 1991, NMFS 1991d), and that the Scott and 

Waddell Creek populations were part of a larger, undescribed ESU (Bryant 1994, NMFS 1994b). 

A review of West Coast (Washington, Oregon, and California) coho salmon populations 

began in 1993 in response to several petitions to list numerous coho salmon populations and 

NMFS’s own initiative to conduct a coastwide status review of the species. This coastwide 

review identified six coho salmon ESUs: the three southernmost ESUs were proposed for listing, 

two were candidates for listing, and one was deemed “not warranted” for listing (NMFS 1995a, 

Weitkamp et al. 1995). In October 1996, the BRT updated the status review for the Central 

California coho ESU and concluded that it was at risk of extinction (NMFS 1996c): NMFS listed 

this ESU as threatened in October 1996 (NMFS 1996c). 

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In December 1996, the BRT updated the status review for both proposed and candidate 

coho salmon ESUs (NMFS 1996b). However, because of the scale of the review, requests from 

comanagers for additional time to comment on the preliminary conclusions, and the legal 

obligations of the NMFS, the status review was finalized for proposed coho salmon ESUs in 

1997 (NMFS 1997c) but not for candidate ESUs. In May 1997, NMFS listed the Southern 

Oregon/Northern California Coast (SONCC) coho salmon ESU as threatened, while it 

announced that listing of the Oregon Coast coho salmon ESU was not warranted due to measures 

in the Oregon Coastal Salmon Restoration Initiative (OCSRI) plan (NMFS 1997d). This finding 

for Oregon coast coho salmon was overturned in August 1998, and the ESU was listed as 

threatened (NMFS 1998e). 

The process of updating the coho salmon status review began again in October 1998 for 

coho salmon in Washington and the lower Columbia River. However, due to competing 

activities with higher priorities, this effort was terminated before the BRT could meet. 

In response to a petition by Oregon Trout et al. (2000), the BRT revisited the status of 

lower Columbia River coho salmon in 2000, with BRT meetings held in March and May 2001 

(NMFS 2001a). The BRT concluded that splitting the Lower Columbia River/Southwest 

Washington coho salmon ESU to form separate Lower Columbia River and Southwest 

Washington coast coho salmon ESUs was most consistent with available information, and that 

the Lower Columbia River coho salmon ESU was at risk of extinction. Like the 1996 status 

review update, these results were never finalized. 

The coho salmon BRT40 met in January, March, and April 2003 to discuss new data and 

determine whether conclusions of the original BRTs should be modified as the result of the new 

information. This report summarizes new information and the preliminary BRT conclusions on 

the following ESUs, Oregon Coast, Southern Oregon/Northern California Coast, Central 

California Coast, and Lower Columbia River. 

 

40The BRT for the updated status review for West Coast coho salmon included Dr. Robert Iwamoto, Dr. Orlay 

Johnson, Dr. Pete Lawson, Gene Matthews, Dr. Paul McElhany, Dr. Thomas Wainwright, Dr. Robin Waples, 

Laurie Weitkamp, and Dr. John Williams from the Northwest Fisheries Science Center (NWFSC); Dr. Peter 

Adams, Dr. Eric Bjorkstedt, and Dr. Brian Spence from the Southwest Fisheries Science Center (SWFSC); and 

Dr. Reginald Reisenbichler from the Northwest Biological Science Center, USGS Biological Resources Division, 

Seattle. 

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27. Oregon Coast Coho Salmon ESU 

Summary of Previous BRT Conclusions 

Major Risk Factors and Status Indicators 

The Oregon Coast coho salmon ESU was assessed in two previous status reviews—one 

in 1995 (Weitkamp et al. 1995) and another in 1997 (NMFS 1997c). In the 1995 status review 

(Weitkamp et al. 1995), the BRT considered evidence from many sources to identify ESU 

boundaries in coho populations from Washington to California. For the most part, the most 

informative evidence for the ESU delineation process was that from the physical environment, 

ocean conditions and upwelling patterns, marine and coded-wire-tag recovery patterns, coho 

salmon river entry and spawn timing, and estuarine and freshwater fish and terrestrial vegetation 

distribution. Genetic information was used to indicate reproductive isolation between 

populations and groups of populations. Based on this assessment, six ESUs were identified, 

including the Oregon Coast coho salmon ESU, which includes naturally spawning populations in 

Oregon coastal streams north of Cape Blanco to south of the Columbia River. 

Evaluation of ESU under Conditions in 1997 

In 1997, extensive survey data were available for coho salmon in the Oregon coast 

region. Overall, spawning escapements had declined substantially during the 20th century and 

may have been at less than 5% of their abundance of the early 1900s. Average spawner 

abundance had been relatively constant since the late 1970s, but preharvest abundance had 

declined. Average recruits per spawner may also have declined. Coho salmon populations in 

most major rivers appear to have been heavily influenced by hatchery stocks, but some 

tributaries may have sustained native stocks. 

For this ESU, information on trends and abundance was better than for the more 

southerly ESUs. Main uncertainties in the assessment included the extent of straying of hatchery 

fish, the influence of such straying on natural population trends and sustainability, the condition 

of freshwater habitat, and the influence of ocean conditions on population sustainability. In 

1996, total average (5-year geometric mean) spawner abundance for this ESU was estimated at 

about 52,000. Corresponding ocean run size for that year was estimated to be about 72,000—

which corresponds to less than one-tenth of ocean run sizes estimated in the late 1800s and early 

1900s, and only about one-third of 1950s ocean run sizes (ODFW 1995a). Total freshwater 

habitat production capacity for this ESU was estimated to correspond to ocean run sizes between 

141,000 under poor ocean conditions and 924,000 under good ocean conditions (OCSRI Science 

Team 1996). Abundance was unevenly distributed within the ESU through the early to mid1990s, with the largest total escapement in the relatively small mid- to south-coast gene 

conservation group (GCG) and lower numbers in the north to mid-coast and Umpqua GCGs. 

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COHO SALMON

Trend estimates using data through 1996 showed that for all three measures (escapement, 

run size, and recruits per spawner), long-term trend estimates were negative. More recent 

escapement trend estimates were positive for the Umpqua River and mid- to south coast 

monitoring areas, but negative in the north to mid-coast. Recent trend estimates for recruitment 

and recruits per spawner were negative in all three areas and exceeded 12% annual decline in the 

two northern areas. Six years of stratified random survey (SRS) population estimates showed an 

increase in escapement and decrease in recruitment. 

To put these data in a longer-term perspective, ESU-wide averages in 1996, which were 

based on peak index and area under the curve (AUC) escapement indices, showed an increase in 

spawners up to levels of the mid- to late 1980s but much more moderate increases in recruitment. 

Recruitment remained only a small fraction of average levels in the 1970s. An examination of 

return ratios showed that spawner:spawner ratios had remained above replacement since the 

1990 broodyear, as a result of higher productivity of the 1990 broodyear and sharp reductions in 

harvest for subsequent broodyears. As of 1996, recruit:spawner ratios for 1991–1994 broodyears 

were the lowest on record, except for 1988 and, possibly, 1984. The 1997 BRT considered risk 

of extinction for this ESU under two scenarios: first, if present conditions and existing 

management continued into the foreseeable future; and second, if certain aspects of the Oregon 

OCSRI Draft Conservation Plan (Oregon Plan 1997, Governor’s Natural Resources Office 1997) 

relating to harvest and hatchery production were implemented. As of 2003, the OCSRI is called 

The Oregon Plan for Salmon and Watersheds.

Population Abundance 

Between the 1995 and 1997 status reviews, escapement increased for the Oregon Coast 

coho salmon ESU as a whole, but recruitment and recruits per spawner remained a small fraction 

of historical abundance. Spawning was distributed over a relatively large number of basins, both 

large and small. Natural escapement from 1990 to 1996 was estimated to be on the order of 

50,000 fish per year in this ESU, reaching nearly 80,000 fish in 1996 coincident with drastic 

reductions in harvest. Prefishery recruitment was higher in 1996 than in either 1994 or 1995, but 

exhibited a fairly flat trend after 1990. The 1996 estimate of ESU-wide escapement indicated an 

approximately fourfold increase since 1990. When looked at on a finer geographic scale, as of 

1996 the northern Oregon coast still had very poor escapement, the north/central coast showed 

mixed escapement with strong increases in some streams but continued very poor escapement in 

others, and the south/central coast continued to have increasing escapement. 

Both recruitment and recruits per spawner declined rapidly (12% to 20% annual declines 

from 1986 to 1996) in two of the three Oregon Department of Fish and Wildlife GCGs in this 

ESU. These declines were steeper and more widespread in this ESU than in any other coho 

salmon ESU for which data were available, and recruits per spawner continued to decline after 

this ESU was reviewed in 1994. The new data, from 1994 to 1996, did not change the overall 

pattern of decline coupled with peaks in recruits per spawner every 4 to 5 years, with the height 

of the peaks declining over time. 

Risks that this decline in recruits per spawner posed to sustainability of natural 

populations, in combination with strong sensitivity to unpredictable ocean conditions, were the 

most serious concern the BRT identified in 1997 for this ESU. Examining the results of the 

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27. OREGON COAST COHO SALMON ESU 

viability models addressed some aspects of this concern, although none of the models 

incorporated declining recruits per spawner, except as a consequence of changing ocean 

conditions. Preliminary results of viability models provided a wide range of results, with one 

model suggesting that most Oregon coast stocks could not sustain themselves at ocean survivals 

observed in the last 5 years, even in the absence of harvest, and another suggesting that stocks 

are highly resilient and would be at significant risk of extinction only if habitat degradation 

continues into the future. Consequently, a major question in evaluating extinction risk for this 

ESU was whether recent ocean and freshwater conditions would continue into the future. 

Population Trends and Production 

For this ESU, fishery recruitment forecasts for 1997 were slightly below the actual 1996 

recruitment (PFMC 1997a), and actual returns were drastically lower, about 25% of 1996 

recruitment and the second lowest on record after 1977. Stream production studies conducted by 

ODFW (Solazzi and Johnson 1996) indicated that 1996 smolt production in four central coast 

study streams was lower than recent averages, with overwinter survival the lowest or secondlowest on record for the two streams for which estimates were made, and that age-0 fish 

production was also low. They concluded that the “most significant impact was on juvenile coho 

salmon eggs that were in the gravel at the time of the [1995–1996] flood.” Although these 

results were based on a small sample of streams and may not reflect average effects of the flood, 

they suggested that 1997 and 1998 adult returns to some coastal basins would be reduced by the 

floods. Longer-term effects of the floods can also be expected to vary among basins, but most 

reports available to the BRT suggest that long-term effects should generally be neutral or slightly 

beneficial (e.g., from sediment removal and increased off-channel habitat) to coho salmon. 

Hatchery Production and Genetic Risks 

Widespread spawning by hatchery fish, as indicated by scale data, was also a major 

concern to the BRT. Scale analysis to determine hatchery:wild ratios of naturally spawning fish 

indicate moderate to high levels of hatchery fish spawning naturally in many basins on the 

Oregon coast, and at least a few hatchery fish were identified in almost every basin examined. 

Although it is possible that these data do not provide a representative picture of the extent of this 

problem, they represented the best information available at the time. In addition to concerns for 

genetic and ecological interactions with wild fish, these data also suggest ODFW may have 

overestimated natural spawner abundance and that the declines in recruits per spawner in many 

areas may have been even more alarming than current estimates indicate. However, by 1997 

Oregon had made some significant changes in its hatchery practices, such as substantially 

reducing coho production levels in some basins, switching to on-station smolt releases, and 

minimizing fry releases. Uncertainty regarding the true extent of hatchery influence on natural 

populations, however, was a strong concern. 

Another concern the BRT discussed in 1997 was asymmetry in the distribution of natural 

spawning in this ESU; a large fraction of the fish occurred in the southern portion and relatively 

few in northern drainages. Northern populations were also relatively worse off by almost every 

other measure: steeper declines in abundance and recruits per spawner, higher proportion of 

naturally spawning hatchery fish, and more extensive habitat degradation. 

315 
COHO SALMON

Habitat Conditions 

With respect to habitat, the BRT had two primary concerns: 1) that the habitat capacity 

for coho salmon within this ESU has significantly decreased from historical levels; and 2) that 

the Nickelson and Lawson (1998) model predicted that, during poor ocean survival, only highquality habitat is capable of sustaining coho populations, and subpopulations dependent on 

medium- and low-quality habitats would likely become extinct. Both of these concerns caused 

the BRT to consider risks from habitat loss and degradation to be relatively high for this ESU. 

Influence of OCSRI 

The 1997 BRT considered only two sets of measures from the OCSRI: 1) harvest 

management reforms and 2) hatchery management reforms. The BRT did not consider the 

likelihood that these measures would be implemented; rather, it only considered the implications 

for ESU status if these measures were fully implemented as described. In order to carry out 

these evaluations, the BRT made the following assumptions: 

• The ocean harvest management regime would be continued as proposed into the 

foreseeable future, not revised in 2000 as stated in the plan. Without this assumption, 

effects of the plan beyond 2000 could not be evaluated. 

• Hatchery releases would continue at or below 1997 release levels (including 

approximately 1 million annual fry releases) into the foreseeable future. 

• The goals of maintaining naturally spawning hatchery fish at less than 10% or 50% of 

natural escapement (depending on genetic similarity with natural fish) would be achieved 

and demonstrated by effective monitoring. 

Some members were very concerned that not enough is known about the causes of 

declines in run size and recruits per spawner to be able to directly assess the effectiveness of 

specific management measures. 

Harvest Measures 

Some BRT members felt that the harvest measures were the most encouraging part of the 

plan, representing a major change from previous management. However, some members were 

concerned that the harvest plan might be seriously weakened when it was reevaluated in 2000 

and were concerned that combining the Umpqua and south-central coast GCGs into a larger 

aggregate (as would occur in the proposed harvest plan) might not adequately protect genetic 

diversity. In addition, concern was expressed about our ability to effectively monitor nontarget 

harvest mortality and to control overall harvest impacts. 

Hatchery Measures 

Of the proposed hatchery measures, the BRT thought substantial reductions in smolt 

releases would have the most predictable benefit for natural populations; all else being equal, 

fewer fish released should result in fewer genetic and ecological interactions with natural fish. 

Marking all hatchery fish should also help to resolve present uncertainties about the magnitude 

of these interactions. However, the BRT expressed concerns regarding some aspects of the 

316 
27. OREGON COAST COHO SALMON ESU 

proposed hatchery measures. The plan was vague on several key areas, including plans for 

incorporation of wild broodstock and how production would be distributed among facilities after 

1997. One concern was that the recent and proposed reductions appear to be largely motivated 

by economic constraints and the present inability to harvest fish if they were produced rather 

than by recognition of negative effects of stray hatchery fish on wild populations. The BRT 

expressed other concerns, including no reductions in fry releases in many basins, substantially 

higher releases of smolts in the Yaquina River basin (which, by ODFW’s own assessment, has 

more high-quality habitat than any other coastal basin), and no consideration of alternative 

culture methods that could be used to produce higher-quality hatchery smolts, which may have 

less impact on wild fish. Another concern was the plan’s lack of recognition that hatchery-wild 

interactions reduce genetic diversity among populations. 

Previous BRT Conclusions 

In 1997, the BRT concluded that, assuming that 1997 conditions continued into the future 

(and that proposed harvest and hatchery reforms were not implemented), the Oregon Coast coho 

salmon ESU was not at significant short-term risk of extinction, but it was likely to become 

endangered in the foreseeable future. A minority felt that the ESU was not likely to become 

endangered. Of those members who concluded that this ESU was likely to become endangered, 

several expressed the opinion that it was near the border between this category and “not at risk.” 

The BRT generally agreed that implementation of the OCSRI’s harvest and hatchery proposals 

would have a positive effect on the ESU’s status, but the panel was about evenly split as to 

whether the effects would be substantial enough to move the ESU out of the “likely to become 

endangered” category. Some members felt that, in addition to the extinction buffer provided by 

the estimated 80,000 naturally produced spawners in 1996, the proposed reforms would promote 

higher escapements and alleviate genetic concerns so that the ESU would not be at significant 

risk of extinction or endangerment. Other members saw little reason to expect that the hatchery 

and harvest reforms by themselves would be effective in reducing what they viewed as the most 

serious threat to this ESU—declining recruits per spawner. If the severe declines in recruits per 

spawner of natural populations in this ESU were partly a reflection of continuing habitat 

degradation, then risks to this ESU might remain high even with full implementation of the 

hatchery and harvest reforms. Although harvest and hatchery reforms may substantially reduce 

short-term risk of extinction, habitat protection and restoration were viewed as key to ensuring 

long-term survival of the ESU, especially under variable and unpredictable future climate 

conditions. The BRT therefore concluded that these measures would not be sufficient to alter the 

previous conclusion, that the ESU is likely to become endangered in the foreseeable future. 

The Oregon Coast coho salmon ESU was listed as a threatened species on 10 August 

1998. The ESU includes all naturally spawned populations of coho salmon in Oregon coastal 

streams south of the Columbia River and north of Cape Blanco (Figure 195). 

Listing status: Proposed Threatened. 

317 
COHO SALMON

Figure 195. Map of Oregon and Washington coasts showing the 11 major river systems and three coastal 

lakes that comprise the Oregon Coast coho salmon ESU. 

318 
27. OREGON COAST COHO SALMON ESU 

New Comments 

Alsea Valley Alliance v. Evans 

On 10 September 2001, Judge Michael R. Hogan, ruling in Alsea Valley Alliance v. 

Evans for the U.S. District Court for the District of Oregon, found that, for the Oregon Coast 

coho salmon ESU, “NMFS’s listing decision is arbitrary and capricious, because the Oregon 

Coast ESU includes both ‘hatchery spawned’ and ‘naturally spawned’ coho salmon, but the 

agency’s listing decision arbitrarily excludes ‘hatchery spawned’ coho. Consequently, the listing 

is unlawful” (161 F. Supp. 2d 1154, D. Oreg. 2001). The lawsuit was brought by the Alsea 

Valley Alliance, partly in response to an action by ODFW to terminate a domesticated coho 

salmon broodstock at the Fall River Hatchery on the Alsea River. 

The effect of the ruling was to delist the Oregon Coast coho salmon ESU. The ruling was 

appealed by the appellant interveners to the U.S. Court of Appeals for the Ninth Circuit. On 14 

December 2001 the Court stayed the District Court ruling pending final disposition of the appeal 

(Alsea Valley Alliance v. Evans, Ninth Circuit appeal, No. 01-36071, 14 December 2001). This 

returned the status of the Oregon Coast ESU to threatened under the ESA. NMFS is currently 

reviewing its listing policy with regard to hatchery and wild salmon. 

Petition for Listing 

On 25 April 2002, NMFS Regional Administrator D. Robert Lohn received a petition to 

define and list the wild stocks of coho salmon along the Oregon coast as a threatened species, 

pursuant to the ESA. The petitioners presented recent scientific reports relating to the 

“behavioral, physiological, ecological, reproductive and evolutionary differences between the 

hatchery and wild stocks” of Oregon coast coho salmon. The petition was in response to the 

findings of Alsea Valley Alliance v. Evans. The petitioners were Trout Unlimited, Oregon 

Council of Trout Unlimited, Washington Council of Trout Unlimited, Oregon Trout, Washington 

Trout, Native Fish Society, Oregon Council of Fly Fishers, Pacific Coast Federation of 

Fisherman’s Associations and the Institute for Fisheries Resources, Oregon Natural Resources 

Council, Save Our Wild Salmon, Orange Ribbon Foundation, American Rivers, Audubon 

Society of Portland, National Wildlife Federation, and the Siskiyou Regional Education Project. 

The petitioners stated: 

NMFS has previously made findings of the detrimental impact that the artificial production of 

localized, but rather widespread in every basin in the Oregon coast where wild coho are present, 

based on the presence of hatchery coho in every stream system (ODFW 1995b; Jacobs et al. 

2001). Additionally, the fluctuations in the ocean conditions, and the changes in the ocean 

carrying capacity, may exacerbate the impacts in certain years (NWPPC 1999). Additional 

reports suggest that the impact of these hatchery programs is resulting in at least phenotypic 

differences (genetic and environmental) between coho, and is not limited to hatchery 

management practices alone, but due to other direct biological and environmental effects (IMST 

2001; Flagg et al. 2000; Chilcote 2002). 

319 
COHO SALMON

The petitioners cited substantial updated information on current abundance, historical 

abundance and carrying capacity, trends in abundance, natural and human-influenced factors that 

cause variability in survival and abundance, possible threats to genetic integrity, and recent 

events such as the extended period of El Niño–like conditions prior to 1997, significant flood 

events in 1995–1996 and 1998, and recently improved ocean conditions (Trout Unlimited 2002). 

Independent Multidisciplinary Science Team 

Since the 1997 status review, the Oregon Plan for Salmon and Watersheds (formerly 

Oregon Coastal Salmon Restoration Initiative Conservation Plan) has developed into an 

extensive effort to recover threatened or endangered salmonid populations through a 

combination of grassroots actions using watershed councils, refocusing effort and resources of 

fisheries and other state agencies, and convening a group of scientists to “advise the state on 

matters of science related to the Oregon Plan for Salmon and Watersheds” (IMST 2002b). This 

group of scientists consists of a seven-member team with “recognized expertise in fisheries 

artificial propagation, stream ecology, forestry, range, watershed and agricultural management”; 

it is known as the Independent Multidisciplinary Science Team (IMST). The IMST has been 

responsible for a series of review documents on the science relating to recovery of Oregon 

coastal coho salmon stocks. The first of these efforts was a workshop of agency and university 

fisheries professionals convened to help in the “Defining and Evaluating Recovery of OCN 

[Oregon Coast Natural] Coho Salmon Stocks: Implications for Rebuilding Stocks under the 

Oregon Plan for Salmon and Watersheds” (IMST 1999). Alternative recovery definitions are 

proposed and criteria for evaluating recovery are discussed. 

Additional reports issued by this team germane to the deliberations of the Oregon coastal 

coho salmon BRT include “Conservation Hatcheries and Supplementation Strategies for 

Recovery of Wild Stocks of Salmonids: Report of a Workshop” (IMST 2000) and “The 

Scientific basis for Artificial Propagation in the Recovery of Wild anadromous Salmonids in 

Oregon” (IMST 2001), which analyzes the hatchery programs of ODFW, presents 3 substantial 

conclusions, and puts forth a series of 10 recommendations based on these conclusions. In 

addition, a comprehensive look at the “Recovery of Wild Salmonids in Western Oregon 

Lowlands” (IMST 2002a) provides an extensive analysis of 5 science questions relating to the 

importance of lowlands to the recovery of salmonids, with 21 recommendations relating to 

recommended actions by state agencies to contribute to the recovery of salmonids in lowland 

areas. They do not, however, present substantially new information that can shed light on the 

evaluation of risk to the Oregon Coast coho salmon ESU. 

Douglas County Board of Commissioners 

The Douglas County Board of Commissioners submitted a report titled “Viability of 

Coho Salmon Populations on the Oregon and Northern California Coasts,” to NMFS Protected 

Resources Division on 12 April 2002 (Cramer and Ackerman 2002). This report analyzes 

information available for both the Oregon Coast coho salmon ESU and the Southern 

Oregon/Northern California Coast coho salmon ESU in several areas: trends in abundance and 

distribution, trends in survival, freshwater habitat condition, potential hatchery-wild interactions, 

changes in harvest regulation, and extinction risk modeling. Few data presented in the report are 

new, but independent analyses focus on unique aspects of the data: changes in fishery 

320 
27. OREGON COAST COHO SALMON ESU 

management, increasing spawning escapements, reduced hatchery releases, habitat restoration, 

and evidence of successful rearing of fry outmigrants throughout the Oregon coast. Although the 

report reached no conclusions regarding the ESU’s overall status, the Douglas County Board of 

Commissioners cites the report in concluding that coho salmon populations in this ESU are 

“strongly viable.” 

New Data and Updated Analyses 

Population Abundance 

For the Oregon Coast coho salmon ESU, the BRT received updated estimates of total 

natural spawner abundance based on stratified random survey (SRS) techniques, broken down by 

ODFW’s monitoring areas (MAs), for 11 major river basins and for the coastal lakes system.41

(ODFW’s monitoring areas are similar, but not identical to, the GCGs that were the population 

units in the 1997 update.) These data are for the return years 1990–2002 and are presented in 

Table 65 (for consistency with the previous status review for this ESU, abundance and trend 

analysis in this update are expressed in terms of naturally produced fish, rather than the standard 

of naturally spawning fish used in other status review updates). Total recent average (3-year 

geometric mean) spawner abundance for this ESU is estimated at about 140,600, up from the 5-

year geometric mean of 52,000 in the 1997 update and higher than the estimate at the time of the 

status review. In 2001, the ocean run size was estimated to be about 178,000; this corresponds to 

one-tenth of ocean run sizes estimated in the late 1800s and early 1900s, and only about onethird of those in the 1950s (ODFW 1995a). In 2002, the ocean run size increased to 304,500, 

fourth highest since 1970 and perhaps 25% of historical abundance. Present abundance is more 

evenly distributed within the ESU than it was in 1997. Escapement in the relatively small 

mid/south coast monitoring area was the strongest in the ESU until 2001. In 2002, escapements 

in the mid/south were down about 25%, while the north and mid-coast monitoring areas showed 

strong gains. The Umpqua monitoring area is up by a factor of 4 since 1996 (Table 65). 

We have updated ocean exploitation estimates based on Oregon Productivity Index (OPI) 

estimated catch and escapement, which is based on SRS methods (OPI-SRS) for 1970–1993; 

postseason results of the coho FRAM for 1994–2001; and the preseason FRAM estimate for 

2002 (OPI-SRS and FRAM from PFMC 2002b). The ODFW Standard Index spawner 

escapement estimates were discontinued in 1999 and data from 1970 to 1989 were standardized 

to the SRS data. All analyses were done using this updated time series. Exploitation rates are 

based on ocean catch and incidental mortality plus escapement. Recruits are calculated as 

spawners divided by 1 minus the ocean exploitation rate. A major assumption is that progeny of 

natural spawners are affected by fishing gear the same as hatchery fish, so that ocean mortalities 

are in the same proportion as escapement. Freshwater harvest and mortality is not directly 

assessed, but is conventionally considered to be 10% of ocean escapement for retention fisheries 

and 1% for catch-and-release fisheries. The BRT also did not attempt to adjust trends for the 

contribution of stray hatchery fish; sufficient data for such an adjustment are not available for 

these populations.

 

41S. Jacobs, Oregon Department of Fish and Wildlife, Corvallis, OR. Pers. commun., 14 November 2002. 

321 
Table 65. Numbers of natural-origin spawners in the Oregon Coast coho salmon ESU, 1990–2002, subtotaled by ODFW m

lakes, and coastwide. Source: Estimated from Oregon Department of Fish and Wildlife stratified random surveys, 

years. 

ODFW monitoring Return year area/location 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 20North co ast

Necanicum and Elk 

creeks 191 1,135 185 941 408 211 768 253 946 728 4

Nehalem 1,552 3,975 1,268 2,265 2,007 1,463 1,057 1,173 1,190 3,713 14,2Tillamook Bay 265 3,000 261 860 652 289 661 388 271 2,175 1,9Nestucca 189 728 684 401 313 1,811 519 271 169 2,201 1,Sand Lake and 

Neskowin Creek 0 240 24 41 77 108 275 61 0 47 

Miscellaneous 0 204 0 0 0 0 0 0 0 0 

North coast total* 2,197 9,282 2,422 4,508 3,457 3,882 3,280 2,148 2,576 8,864 17,9

Mid-n orth

Salmon 385 39 28 364 107 212 271 237 8 175 Siletz 441 984 2,447 400 1,200 607 763 336 394 706 3,5Yaquina 381 380 633 549 2,448 5,668 5,127 384 365 2,588 6Beaver Creek 23 0 756 500 1,259 0 1,340 425 1,041 3,366 7Alsea 1,189 1,561 7,029 1,071 1,279 681 1,637 680 213 2,050 2,4Yachats 280 28 337 287 67 117 176 99 102 150 Siuslaw 2,685 3,740 3,440 4,428 3,205 6,089 7,625 668 1,089 2,724 6,7Miscellaneous 207 0 700 180 251 231 1,188 13 71 0 

Mid-north total* 5,591 6,732 15,372 7,779 9,816 13,605 18,127 2,842 3,283 11,759 14,2Umpqua 

Lower Umpqua and 

Smith 589 1,316 1,759 4,804 1,689 6,803 4,904 935 5,118 2,323 3,6

Umpqua 455 0 192 1,431 1,240 352 339 397 444 1,289 2,7Elk and Calapooya 

creeks 185 0 0 0 708 2,315 1,709 196 379 434 1,

South Umpqua 2,508 2,284 0 2,415 579 755 1,685 512 678 1,219 4Cow Creek 0 0 201 661 269 1,124 1,112 193 1,807 1,234 1,5

Umpqua total* 3,737 3,600 2,152 9,311 4,485 11,349 9,749 2,233 8,426 6,499 10,3

322 
Table 65 continued. Numbers of natural-origin spawners in the Oregon Coast coho salmon ESU, 1990–2002, subtotaled by 

a, rivers, lakes, and coastwide. Source: Estimated from Oregon Department of Fish and Wildlife stratified random 

return years. 

ODFW monitoring Return year area/location 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 20Mid-south 

Coos Bay and Big Creek 2,273 3,813 16,545 15,284 14,685 10,351 12,128 1,127 3,167 4,945 5,3Coquille 2,712 5,651 2,115 7,384 5,035 2,116 16,169 5,720 2,466 3,001 6,1

Miscellaneous 0 1 2 3 4 5 6 7 8 9 

Mid-south total* 4,985 9,465 18,662 22,671 19,724 12,472 28,303 6,854 5,641 7,946 11,5

Coastwide rivers 16,512 29,078 38,607 44,270 37,481 41,306 59,459 14,076 19,926 34,696 54,0Lakes 4,394 7,251 1,986 10,145 5,842 11,216 13,494 8,603 11,108 12,711 12,7Coastwide total* 20,906 36,329 40,593 54,415 43,323 52,522 72,953 22,679 31,034 47,407 66,8

* Monitoring area totals from 1999 to 2002 are estimated by monitoring area and may differ from the sums of the individual rivers. 

323 
COHO SALMON

The BRT determined that the coded-wire-tag-based index (CWT) became less useful 

after the implementation of coho nonretention fisheries in 1994. The CWT index depends on 

ocean recoveries of coded-wire tags, and there are no tag recoveries in nonretention fisheries. 

Noncatch mortalities (hook-and-release, drop-off, illegal retention) are either estimated in the 

coho FRAM or estimated externally and input directly in the model. 

The BRT used escapement estimates provided by ODFW (Table 65).42 The SRS 

escapement data indicate that, ESU-wide, spawning escapement reached a 30-year high in 2001 

and continued to climb in 2002 (Figures 196 and 197). This high escapement is due to a 

combination of improved marine survival and sharply curtailed ocean fisheries. When viewed 

on a finer geographic scale, the north coast has responded well after a very weak period through 

1999. The mid-coast was mixed in 2001, with strong increases in some streams but continued 

very poor escapement in others. Substantial increases in 2002 made it the strongest area on the 

coast. The mid/south coast rebounded in 2002 after a 4-year drop (Table 65). 

Three-year statistics (geometric mean, arithmetic mean, minimum and maximum 

spawners, and recruits) in individual river basins are strongly affected by the recent 2 years of 

high marine survival (Table 66). Abundance grew exponentially in the past 3 years, so 

arithmetic means are uniformly higher than geometric means. The minimum and maximum 

abundances show that, with a few exceptions, abundances in individual basins have increased 

about tenfold in the past 3 years. Abundance in the Nehalem River ranged only from 14,285 to 

22,310, indicating that this system may have been near capacity before survival improved. On 

the other hand, the Yaquina River grew from 647 to 25,039—nearly a fortyfold increase. 

Statistics for the combined systems (Table 67) are more stable, but they indicate an overall 

fourfold increase in spawners over the past 3 years. 

In the return years 1997–1999 (broodyears 1994–1996), and for the first time on record 

(since 1950), recruits failed to replace the parental spawners: a recruitment failure occurred in all 

three brood cycles, even before accounting for harvest-related mortalities (Figure 196). Since 

1999, improving marine survival and higher rainfall are thought to be the factors contributing to 

an upswing in wild recruitment. Fishery recruitment for 2002 was up over fourfold from 2000, 

with about 304,000 recruits, but below the 30-year high of 450,000 observed in 1973. Given 

current habitat conditions, OCN coho are thought to require an overall marine survival rate of 

0.03 to achieve a spawner:recruit ratio of 1:1 in the best quality habitat (Nickelson and Lawson 

1998). Less productive habitats require higher marine survivals to sustain populations. Based on 

OPI hatchery survival rates, marine survival after exploitation exceeded 0.03 only in 2001. 

Assuming natural spawners survive at twice the hatchery rate, in 7 out of 13 years since 1990 

marine survivals after exploitation were high enough to sustain the strongest populations. 

Increases in recruits and spawners (Figures 196 and 197) reflect improved marine survival for 

the 2000 and 2001 smolt years. It is far from certain that these favorable marine conditions will 

continue and, with the current freshwater habitat conditions, the ability of OCN coho to survive 

another prolonged period of poor marine survival remains in doubt. 

 

42See Footnote 41. 

324 
Table 66. Three-year statistics and 13-year trends for 11 major river basins in the Oregon Coast coho salmon ESU. 

Spawnersa Recruitsb

3-year mean 3-year range 13 year 3-year mean 3-year range 

Basin Geometric Arithmetic Minimum Maximum Trend SE Geometric Arithmetic Minimum MaxiNecanicum 1,889 2,810 474 5,247 1.169 0.860 2,096 3,101 522 5,Nehalem 18,741 19,083 14,285 22,310 1.206 0.889 20,799 21,188 15,728 24,Tillamook 3,949 6,785 1,883 16,488 1.191 1.084 4,382 7,723 2,034 18,Nestucca 3,846 5,815 1,171 12,334 1.230 1.015 4,269 6,574 1,289 14,Siletz 2,295 2,453 1,437 3,553 1.070 0.760 2,547 2,729 1,552 3,Yaquina 3,665 9,575 647 25,039 1.204 1.205 4,067 10,925 712 28,Alsea 3,621 3,857 2,465 5,767 1.042 0.960 4,018 4,316 2,714 6,

Siuslaw 16,213 24,972 6,767 57,125 1.120 1.037 17,993 28,339 7,450 65,Umpqua 24,351 28,520 10,395 42,415 1.182 0.662 27,025 31,857 11,445 48,Coos 20,136 27,897 5,386 43,301 1.088 1.066 22,346 30,978 5,930 46,Coquille 8,847 9,309 6,130 13,310 1.070 0.649 9,819 10,294 6,749 14,

a Spawners are natural-origin spawners only. b Recruits are natural-origin adults before ocean harvest. Table 67. Three-year statistics and 33-year trends for Oregon Coast coho salmon ESU rivers, lakes, and combined rivers a

Spawnersa Recruitsb

3-year mean 3-year range 33 year 3-year mean 3-year ran

Geometric Arithmetic Minimum MaximumMinimum Maximum Geometric Arithmetic Minimum Ma

Rivers 122,718 147,933 50,500 242,200 1.017 0.600 136,291 165,933 55,600 27Lakes 16,189 16,635 12,747 22,097 1.013 0.735 17,966 18,567 14,034 2Combined 140,568 164,569 63,247 264,297 1.016 0.566 156,105 184,500 69,634 304a Spawners are natural-origin spawners only. b Recruits are natural-origin adults before ocean harvest. 

. 

325 
COHO SALMON

326 

0

50000

100000

150000

200000

250000

300000

350000

400000

450000

500000

1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Preharvest lagged recruits Spawners

Figure 196. Time series of spawners and preharvest recruits, by broodyear, for rivers in the Oregon Coast 

coho salmon ESU, 1970–2002. 

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

200000

1950 1960 1970 1980

Year

Abundance

1990 2000 2010

Preharvest lagged recruits Spawners

Figure 197. Time series of spawners and preharvest recruits, by broodyear, for lakes in the Oregon Coast 

coho salmon ESU, 1960–2002. 
27. OREGON COAST COHO SALMON ESU 

0.900

1.000

1.100

1.200

0 5000 10000 15000 20000 25000 30000

Spawners or recruits (most recent 3-year geometric mean)

Short-term trend

Spawners Recruits

Figure 198. Short-term (13-year, 1990–2002) trends in spawners and recruits versus the recent 3-year 

geometric mean abundance plotted for 11 major river populations in the Oregon Coast coho 

salmon ESU. 

0.9

1.0

1.1

1.2

Necanicum

Nehalem

Tillamook

Nestucca

Siletz

Yaquina

Alsea

Siuslaw

Umpqua

Coos

Coquille

Short-term trend

Figure 199. Short-term (13-year, 1990–2002) trends in spawner abundance for 11 major river basins in 

the Oregon Coast coho salmon ESU. Basins are ordered from north to south. 

Growth Rates and Productivity 

Trend analyses were performed on short- and long-term time series of spawner 

abundance and preharvest recruit abundance calculated as described above. Short-term trends 

were based on SRS estimates of abundance in 11 major river basins considered to be the 

principal populations in this ESU. Short-term trends used data from 1990 to 2002 return years. 

Long-term trends were estimated separately for the aggregated coastal rivers (including several 

327 
COHO SALMON

small systems outside the 11 major river basins) and for the coastal lakes. The river trends were 

based on data calibrated to the SRS time series from 1970 to 2002. The lake trends were based 

on the historical time series of lakes abundance from 1970 to 2002. 

Thirteen-year trends of spawner abundance for 11 major river systems are presented in 

Table 65 and illustrated in Figures 198 and 199. Spawner trends were positive in all 11 basins, 

with the biggest increases (>10% per year) on the north coast (Necanicum, Nehalem, Tillamook, 

Nestucca), mid coast (Yaquina, Siuslaw), and the Umpqua, and with smaller increases on the 

central (Siletz, Siuslaw) and south (Coos, Coquille) coasts. The Alsea showed the weakest trend; 

it was greater than 1 as of the 2002 spawning returns (Figure 199). 

Thirteen-year trends in preharvest recruits (Figures 198 and 200) show a less favorable 

picture. Necanicum, Nehalem, Tillamook, Nestucca, Yaquina, and Umpqua all showed positive 

trends of about 8% to 13% per year. Siletz, Alsea, and Coquille showed declines ranging from 

1% to 4% per year. Upward trends in the Tillamook, Siuslaw, and Coos hinge on the high 2002 

escapements. The most recent 3-year geometric mean abundance showed little relationship to 

trend (Figure 198). 

Long-term (33-year) trends in spawner abundance for both the lakes and rivers have been 

relatively flat (Table 66, Figure 201), with lakes increasing about 2% per year and rivers 

increasing about 1% per year. In both the lakes and rivers, long-term trends in recruits have 

declined about 5% per year since 1970. For the ESU as a whole, spawners and recruits have 

declined at a 5% rate over the past 33 years. 

Population Spatial Structure 

We have very limited direct information about the spatial structure of the Oregon Coast 

coho salmon populations. Recent analyses (Nickelson and Lawson 1998, Nickelson 2001) 

assumed that spawners from major river basins are largely isolated, and that each basin 

comprises at least one population. The Umpqua River is large and diverse enough to hold 

several populations, but for the purposes of this analysis it was considered as one. The three 

coastal lakes, Siltcoos, Tahkenitch, and Tenmile, are considered to be a single population, but 

may actually be separate. Genetic analyses are being conducted to resolve these questions, but 

results were not available at the time of this review. This is a change from the status review 

update in 1997 (Schiewe 1997), when the Oregon coast was considered to consist of four 

populations, called gene conservation groups. Three of these groups (north/mid coast, mid/south 

coast, and Umpqua) were in the Oregon Coast coho salmon ESU and the fourth (south coast) 

was in the Southern Oregon/Northern California Coast coho salmon ESU. 

Population Diversity 

New information on population diversity is anecdotal. With extremely low escapements 

in recent years, many small systems have shown local extirpations. For example, Cummins 

328 
27. OREGON COAST COHO SALMON ESU 

0.9

1.0

1.1

Necanicum

Nehalem

Tillamook

Nestucca

Siletz

Yaquina

Alsea

Siuslaw

Umpqua

Coos

Coquille

Short-term trend

Figure 200. Short-term (13-years, 1990–2002) trends in recruit abundance for 11 major river basins in the 

Oregon Coast coho salmon ESU. Basins are in order from north to south. 

0.9

1.0

1.1

Lakes Rivers Total Lakes Rivers Total

Long-term trend

Spawners Recruits

Figure 201. Long-term trends (33 years, 1970–2002) for spawners and recruits in coastal lakes (lakes), 

river basins (rivers), and total in the Oregon Coast coho salmon ESU. 

Creek, on the central coast, had zero spawners in 1998,43 indicating the loss of a brood cycle. 

These systems are apt to be repopulated by stray spawners if abundances increase. Whether 

these events represent loss of genetic diversity, or are indications of normal metapopulation 

function, is not known. 

Harvest Impacts 

Historical harvest rates on OPI area coho salmon were in the range of 60% to 90% from 

the 1960s into the 1980s. Modest harvest reductions were achieved in the late 1980s, but rates 

remained high until a crisis was perceived, and most directed coho salmon harvest was 

prohibited in 1994. Subsequent fisheries have been severely restricted, and most reported 

 

43S. Johnson, Oregon Department of Fish and Wildlife, Newport, OR. Pers. commun., 15 January 2003. 

329 
COHO SALMON

mortalities are estimates of indirect (noncatch) mortality in Chinook fisheries and selective 

fisheries for marked (hatchery) coho. Estimates of these indirect mortalities are somewhat 

speculative, and there is a risk of substantial underestimation. 

Amendment 13 

The Pacific Fishery Management Council adopted Amendment 13 (PFMC 1998) to its 

Salmon Fishery Management Plan in 1998. This amendment was developed as part of the 

Oregon Plan for Salmon and Watersheds (formerly OCSRI). It specified an exploitation rate 

harvest management regime with rates for OCN dependent on marine survival (as indexed by 

hatchery jack:smolt ratios) and parental and grandparental spawning escapements. Exploitation 

rates ranged from 13% to a maximum of 35%. In 2000, Amendment 13 was reviewed, and the 

harvest rate matrix was modified to include a 0–8% category under conditions of extremely poor 

marine survival, as was observed in the late 1990s. At the same time, the maximum exploitation 

rate was increased to 45%. Exploitation rates were calculated to allow a doubling of spawners 

under conditions of moderate-to-good ocean survival. 

Risk assessment was conducted for Amendment 13 (PFMC 1998) and the 2000 

Amendment 13 Review (PFMC 2000) using the Nickelson/Lawson coho salmon habitat-based 

life-cycle model (Nickelson and Lawson 1998). The models were augmented to include a 

simulation of the fishery management process, including errors in spawner assessment, 

prediction, and harvest management. In general, the exploitation-rate management with a 35% 

cap showed a lower risk of pseudo-extinction than managing for an escapement goal of 200,000 

spawners, but higher risk than a zero-harvest scenario. Starting from the very low escapements 

of 1994, basins on the north coast had higher extinction risks than those on the mid-north and 

mid-south coasts. 

Mark-selective fisheries 

Beginning in 1998 most adult hatchery-origin coho salmon in the OPI area were marked 

with an adipose fin clip. This marking allowed the implementation of mark-selective fisheries, 

with legal retention only of marked fish. Unmarked fish were to be released unharmed. 

Recreational mark-selective fisheries have been conducted on the Oregon coast in each year 

since 1998, with quotas ranging from 13,000 to 24,000 marked fish. Commercial troll fisheries 

targeting Chinook salmon were also operating. 

Both the mark-selective coho and commercial troll Chinook salmon fisheries catch and 

release coho salmon, resulting in incidental mortalities. In addition, some coho encounter the 

gear but escape or are eaten by predators—so-called drop-offs. Estimates of noncatch mortalities 

from hook and release and drop-off are difficult because they are, by their nature, unobserved. 

Field studies in the 1990s (NRC 1996) and a literature review and metaanalysis resulted in the 

adoption, by the Pacific Fishery Management Council (PFMC), of hooking mortality rates of 

13% for recreational fisheries and 24% for commercial fisheries. In addition, drop-off 

mortalities were assumed to equal 5% of the number of fish brought to the boat. Based on 

these mortality rates, the PFMC uses a coho FRAM to estimate noncatch mortalities in 

330 
27. OREGON COAST COHO SALMON ESU 

Table 68. Oregon Productivity Index (OPI) area hatchery marine survival, Oregon coastal hatchery adult 

returns per smolt, and OPI area exploitation rate on unmarked coho salmon, 1990–2002. All 

values are lagged to adult return year. 

Year 

OPI hatchery 

adults per smolt 

Coastal hatchery 

adults per smolt 

OPI area 

unmarked 

exploitation rate 

OPI marine 

survival after 

exploitation 

1990 0.020 0.003 0.72 0.006 

1991 0.050 0.007 0.57 0.022 

1992 0.026 0.004 0.56 0.011 

1993 0.011 0.003 0.45 0.006 

1994 0.018 0.005 0.03 0.017 

1995 0.024 0.005 0.23 0.018 

1996 0.021 0.006 0.15 0.018 

1997 0.006 0.005 0.13 0.005 

1998 0.008 0.005 0.07 0.007 

1999 0.011 0.008 0.08 0.010 

2000 0.023 0.014 0.09 0.021 

2001 0.050 0.044 0.07 0.046 

2002 0.026 0.033 0.12* 0.023 

*

 Preseason estimate. 

council-managed fisheries. Postseason estimates of OCN exploitation rates based on FRAM 

modeling have ranged from 0.07 to 0.12 since the cessation on directed coho salmon fishing in 

1994 (Table 68). The BRT is concerned that these rates may be underestimates, and that actual 

mortalities may be greater. It is difficult to assess the risk to these stocks resulting from harvest 

at these levels. 

Despite these uncertainties, there is no doubt that harvest-related mortalities have been 

reduced substantially over the past decade. This reduction is reflected in positive short-term 

trends in spawner escapements (Figure 199) despite continued downward trends in preharvest 

recruits for 6 of the 11 major river basins (Figure 200). Harvest management has succeeded in 

maintaining spawner abundance in the face of a continuing downward trend in productivity of 

these stocks. Further harvest reductions can have little effect on spawning escapements. Future 

remedies must be found outside of harvest management until the decline in productivity is 

reversed. 

Habitat Condition 

Freshwater 

The Oregon Plan for Salmon and Watersheds (Oregon Plan 1997) is the most ambitious 

and far-reaching program to improve watersheds and recover salmon runs in the Pacific 

Northwest. It is a voluntary program focused on building community involvement, habitat 

restoration, and monitoring. All state agencies with activities affecting watersheds are required 

to evaluate their operations with respect to salmon impacts and report on actions taken to reduce 

these impacts to the governor on a regular basis. The original Coastal Salmon Restoration 

331 
COHO SALMON

Initiative was written in 1997, so the plan has been in operation for several years. As a result of 

the plan, watershed councils across the state have produced watershed assessments of limiting 

factors for anadromous salmonids on both public and private land. The State of Oregon has 

dedicated about $20 million per year to implement restoration projects and is developing a 

system to link project development with whole-watershed assessments. The Oregon Department 

of Environmental Quality and the Oregon Department of Agriculture are implementing 

regulatory mechanisms to reduce non-point-source pollution. If these efforts are successful, 

Oregon could see a widespread improvement in water quality. There is room for improvement in 

the reporting of watershed assessment results and limiting factors, and identification of actions to 

be taken or progress made in addressing these limiting factors. Although this is a significant 

recovery effort in the Pacific Northwest, and an extensive, coordinated monitoring program is in 

place, measurable results of the program will take years or decades to materialize. 

Marine 

The climate regime shift in 1976 was the beginning of an extended period of poor marine 

survival for coho salmon in Oregon. Conditions worsened in the 1990s, and OPI hatchery 

survival reached a low of 0.006 adults per smolt in 1997 (1996 ocean entry, Table 68). Coastal 

hatcheries appear to have fared even worse, although adult counts at these facilities are often 

incomplete, biasing these estimates low. Following an apparent shift to a more productive 

climate regime in 1998, marine survival started to improve, reaching 0.05 for adults returning in 

2001 (Table 68). The Pacific Decadal Oscillation (PDO) had been in a cold, productive phase 

for about 4 years, and in August 2001 it reversed, indicating a warm, unproductive period. This 

reversal may be short-lived; the PDO historically has shown a 20- to 60-year cycle. However, 

“the rising influence of global warming should throw up a big caution sign to us when trying to 

use past decadal patterns as predictive models for the future.”44

A long-term understanding of the prospects for OCN coho can be constructed from a 

simple conceptual model incorporating a trend in habitat quality and cyclical ocean survival 

(Figure 202, Lawson 1993). Short-term increases in abundance driven by marine survival cycles 

can mask longer-term downward trends resulting from freshwater habitat degradation (as in 

Figure 202) or longer-term trends in marine survival that may be a consequence of global climate 

change. Decreases in harvest rates (C in Figure 202) can increase escapements and delay 

ultimate extinction (D in Figure 202). Harvest rates have been reduced to the point where no 

further meaningful reductions are possible. The current upswing in marine survival is a good 

thing for OCN coho, but will only provide a temporary respite unless other downward trends are 

reversed. 

New Hatchery Information 

Interactions between hatchery and wild fish are generally considered to have negative 

outcomes for the wild fish. A growing body of literature documents reduced spawning success, 

freshwater survival, and production of wild fish when hatchery fish are present (NRC 1996, 

Flagg and Nash 1999, Flagg et al. 2000, Independent Scientific Group [ISG] 2000, IMST 2001, 

 

44N. Mantua, School of Marine Affairs/Joint Institute for the Study of Atmospheric and Oceanic Climate Impacts 

Group, University of Washington, Seattle. Pers. commun., 7 January 2003. 

332 
27. OREGON COAST COHO SALMON ESU 

Einum and Fleming 2001, Chilcote 2002). Additional negative interactions are associated with 

mark-selective fisheries directed at hatchery coho salmon in the ocean. In the past 12 years there 

have been closures of some Oregon coastal hatchery facilities, reduction in numbers of smolts 

released from the remaining facilities, and efforts to include more native broodstock. In 

principle, these changes should somewhat reduce risks to naturally spawning coho on the Oregon 

coast. Starting in 1999 most adult coho salmon of hatchery origin were marked with an adipose 

fin clip. This marking enabled the introduction of mark-selective fisheries for hatchery (finclipped) coho salmon. An additional benefit is better accounting of hatchery fish spawning in 

the wild. 

Hatchery smolts released are reported in Table 69. Numbers have dropped from a high of 

6.2 million in 1992 to 0.93 million in 2001. Over that time period, several small hatcheries 

closed or stopped releasing coho. For 3 years (1995–1997) coho smolts were released from the 

acclimation facility on Yaquina Bay. In 1999, Fall Creek Hatchery on the Alsea River stopped 

releasing coho salmon smolts. The percentage of hatchery-origin spawners on natural spawning 

Figure 202. Conceptual model of effects of declining habitat quality and cyclic changes in ocean 

productivity on the abundance of Oregon’s coastal natural coho salmon: a. Trajectory over time 

of habitat quality. The dotted line represents possible effects of habitat restoration projects. 

b. Generalized time series of ocean productivity. c. Sum of top two panels; labeled points are 

A = situation in the mid 1990s, B = current situation, C = change in escapement from increasing 

or decreasing harvest, and D = change in time of extinction from increasing or decreasing harvest 

(Lawson 1993). 

c: Population Size

b: Ocean Environment

a: Freshwater Habitat Quality

=

+

C D B

A

Time

Escapement

a. Freshwater habitat quality 

b. Ocean environment 

c. Population size 

0

333 
COHO SALMON

grounds also decreased (Figure 203, Tables 70 and 71). Throughout most of the1990s, the 

percentage of natural spawners that were of hatchery origin exceeded 10% in more than half of 

Oregon coast basins and exceeded 70% in three. By contrast, in the most recent 3 years the 

proportion of hatchery-origin spawners has generally been much lower (Tables 70 and 71). The 

decrease is most notable in north coast systems, which had up to 70% hatchery spawners in the 

early 1990s and have averaged below 5% since 1999. Both the Tillamook and Umpqua basins 

continue to show elevated numbers of hatchery-origin spawners in most years, and the Alsea 

River had 7% hatchery spawners in 2001 despite the closure of the Fall Creek Hatchery in that 

system. 

Overall, the reduction in hatchery activity is expected to benefit wild runs. However, it 

may take several years before these benefits become apparent, depending on the mix of 

demographic and genetic effects on natural production. In the meantime, the future of the 

hatchery program is uncertain. On one hand, public opinion and a perceived short-term benefit 

may create pressure to increase hatchery activity despite the likely negative effects on wild runs. 

On the other hand, Oregon state budget problems may force additional hatchery closures. The 

Trask and Salmon river hatcheries were scheduled to be closed in 2001 but were given a lastminute reprieve by the Oregon legislature. 

Jacobs et al. (2000) discussed potential errors associated with the change in methodology 

used to determine the origin of natural spawners. Prior to 1998, hatchery or wild origin was 

determined primarily by scale analysis, while mass marking permitted the use of adipose fin 

clips beginning in 1998. In 1998 and 1999 both methods were used. Comparison of results from 

the two methodologies show that scales tend to indicate greater proportion of hatchery fish than 

fin clips, although limitations are associated with both methodologies. The primary limitation of 

scale analysis is availability of adequate reference scales for naturally produced fish, while 

marking programs may not actually mark 100% of the fish as intended. 

Estimates of hatchery fish contribution rates from scale analysis are complicated by the 

low sample sizes collected during the extremely low coho abundances in the 1990s. ODFW 

determined that acceptable estimates of hatchery contribution rates could not be made in cases 

where fewer than 10 scales were collected in a basin in a year. These rates were reported as 0% 

hatchery fish even when hatchery scales were observed in the sample. Small sample zeros are 

not distinguishable from true zeros in Table 70, resulting in an underreporting of hatchery 

contributions that the BRT was unable to evaluate. Figure 203 attempts to minimize this 

problem by aggregating data from 1992 to 1998, and probably presents a truer overall picture for 

that time period of general patterns in hatchery fish distribution in the ESU. 

334 
27. OREGON COAST COHO SALMON ESU 

Table 69. Millions of smolts released, adult returns, and number of operating hatcheries on the Oregon 

coast, 1990–2002. 

Year 

Smolts released 

(millions) 

Adult returns to 

hatchery 

Number of 

hatcheriesa

1990b 5.70 15,489 6 

1991 5.30 39,555 6 

1992 6.20 23,307 6 

1993 4.33 20,209 6 

1994 5.02 23,435 6 

1995 3.71 25,173 6 

1996 3.28 23,422 7 

1997 2.92 17,776 7 

1998 1.66 15,287 7 

1999 1.06 13,347 6 

2000 0.86 14,984 5 

2001 0.93 38,149 5 

2002 0.98 30,862 5 a Excludes three small hatcheries: Elk River, Cedar Creek, and Eel Lake. 

b An additional 5.4 million smolts were released from private facilities in 

1990. 

335 
COHO SALMON

0% 20% 40% 60% 80% 100%

ROGUE RIVER N=506

FLORAS CREEK N=6

NEW RIVER N=4

COQUILLE RIVER N=312

COOS RIVER N=604

UMPQUA RIVER N=500

SIUSLAW RIVER N=104

SUTTON CREEK N=6

YACHATS RIVER N=6

ALSEA RIVER N=111

BEAVER CREEK N=41

YAQUINA RIVER N=47

SILETZ RIVER N=43

DEVIL'S LAKE N=20

SALMON RIVER N=155

NESKOWIN CREEK N=4

NESTUCCA RIVER N=45

SAND LAKE N=3

TILLAMOOK RIVER N=16

TRASK RIVER N=78

WILSON RIVER N=25

KILCHIS RIVER N=6

MIAMI RIVER N=2

NEHALEM RIVER N=241

NECANICUM RIVER N=34

HATCHERY WILD

Figure 203. Rearing origin of naturally spawning adult coho salmon in major Oregon coastal river basins 

over the 6-year period 1992–1998. Estimates derived from analysis of scales collected on 

random spawning surveys. Samples from the Rogue River basin are only from the most recent 

3-year period (1996–1998). Solid bars represent hatchery fish and open bars represent naturally 

produced fish. Source: Reproduced from Jacobs et al. (2000). 

336 
27. OREGON COAST COHO SALMON ESU 

Table 70. Percent of natural spawning (n) coho salmon of hatchery origin in Oregon coastal river basins, 

based on fin clips from carcasses (1998, 1999) or both carcasses and live fish (2000–2002). 

Source: Data from Jacobs et al. (2000, 2001, 2002) and S. Jacobs.a

1998 1999 2000 2001 2002 

Major basin n %Hb n %Hb n %H n %H n %H 

North Coast 

 Necanicum and Elk 

 creeks 2 0.0 8 0.0 605 6.4 280 2.9 

 Nehalemc 22 26.0 14 0.0 1,995 0.5 2,735 2.0 2,535 6.2 

 Tillamook Bay 1 0.0 18 5.6 224 10.8 124 4.1 1,874 2.0 

 Nestucca 1 0.0 20 0.0 188 2.1 212 10.4 1,034 1.6 

North Coast totals, 

average 26 22.0 60 1.7 2,407 1.6 3,676 3.3 5,723 3.8 

Mid-North 

 Salmon 142 98.6 6 17.5 145 34.5 

 Siletzd 2 100.0 5 41.9 185 2.7 153 12.4 171 1.8 

 Yaquina 16 37.5 6 0.0 239 1.7 1,579 0.3 

 Devil’s Lake and 

 Beaver Creek 19 21.1 13 0.0 193 1.6 527 0.8 

 Alsea 24 87.5 4 0.0 107 2.8 162 7.4 448 0.2 

 Siuslaw 9 11.1 15 6.7 351 0.9 782 1.2 3,240 0.3 

 Coastal lakes 647 0.0 80 1.3 54 0.0 183 0.0 3,293 0.1 

Mid-North totals, 

average 859 20.3 129 4.0 697 1.6 1,712 2.8 9,403 0.8 

Umpqua 

 Smithe 59 0.0 25 0.0 693 0.4 1,603 2.3 2,252 1.1 

 Mainstem Umpqua 7 14.3 17 5.9 209 3.3 508 40.8 617 5.8 

 Elk and Calapooya 

 creeks 10 10.0 13 15.4 231 3.9 158 1.3 204 2.9 

 South Umpqua 11 36.4 47 6.4 285 4.6 67 0.0 

 Cow Creek 21 14.0 34 3.0 124 21.8 498 5.1 192 1.6 

Umpqua totals, average 108 8.3 136 5.2 1,257 3.7 3,052 9.3 3,332 2.1 

Mid-South 

 Coos Bay 53 1.9 85 0.0 376 0.0 2,569 0.8 4,145 0.3 

 Coquille 29 0.0 40 0.0 431 0.2 1,733 6.0 880 0.9 

 Tenmile Lake 51 0.0 80 0.0 65 0.0 767 0.1 341 1.5 

 Floras Creek and 

 New River 10 0.0 4 0.0 217 5.1 2 0.0 

Mid-South totals, 

average 143 0.7 209 0.0 872 0.1 5,286 2.6 5368 0.4 

Coastwide totals, 

average 1,136 16.7 534 2.5 5,233 1.8 13,726 4.3 23,826 1.6 a Steve Jacobs, Oregon Department of Fish and Wildlife, Corvallis, OR. Pers. commun., 9 April 2003. 

b

 Hatchery percentages from 1998 and 1999 are adjusted by marked:unmarked ratios at the nearest hatchery facility. c

 2002 data are missing dead fish from North Nehalem, area of high hatchery straying. 

d

 In 2002, does not include recoveries from Steer Creek, located near Siletz Tribal Release Point. With Steer Creek 

recoveries, n = 435, %H = 49.4%. e

 Includes lower Umpqua River in 2000, 2001, and 2002. 

337 
Table 71. Proportion of natural spawning fish of hatchery origin, 1990

–2002. In some cases with insufficient data ODFW 

spawners when, in fact, hatchery spawners may have been present. 

Management area/ Return year  location 1990 a 1991 a 1992 a 1993 a 1994 a 1995 a 1996 a 1997 a 1998b 1999 b North co ast Necanicum and Elk creeks 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00  Nehalem 0.65 0.22 0.43 0.81 0.43 0.49 0.74 0.45 0.23 0.00  Tillamook Bay 0.00 0.00 0.00 0.53 0.29 0.62 0.14 0.08 0.00 0.06 

 Nestucca 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 

 Sand Lake and Neskowin Creek 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 North coast average 

orth

0.57 0.11 0.28 0.70 0.34 0.33 0.49 0.32 0.12 0.02 

Mid-n  Salmon 0.11 0.00 0.80 0.00 0.93 0.84 0.90 0.43 0.99 0.17  Siletz 0.00 0.71 0.27 0.00 0.00 0.00 0.00 0.00 0.00 0.40  Yaquina 0.38 0.00 0.00 0.00 0.00 0.00 0.16 0.27 0.38 0.00  Beaver Creek 0.00 0.00 0.00 0.00 0.00 0.00 0.21 0.00  Alsea 0.01 0.00 0.17 0.00 0.00 0.00 0.00 0.27 0.87 0.00  Yachats 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00  Siuslaw 0.00 0.00 0.00 0.04 0.38 0.00 0.26 0.00 0.11 0.07  Miscellaneous 0.00 1.00 0.00 0.00 0.00 0.00 0.00 0.00 Mid-north average 0.05 0.26 0.14 0.02 0.26 0.08 0.25 0.17 0.45 0.08 Umpqua  Lower Umpqua and Smith 0.30 0.00 0.00 0.00 0.00 0.00 0.00 0.06 0.00 0.00  Umpqua 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.14 0.06  Elk Creek and Calapooya Creek 0.00 0.00 0.00 0.00 0.00 0.10 0.15  South Umpqua 0.00 0.00 0.00 0.00 0.08 0.77 0.21 0.05 0.04  Cow Creek 0.00 0.00 0.71 0.08 0.58 0.00 0.67 0.00 Umpqua average 

uth

0.06 0.00 0.00 0.00 0.13 0.01 0.43 0.08 0.09 0.03 

Mid-so  Coos Bay and Big Creek 0.00 0.00 0.03 0.05 0.03 0.01 0.00 0.00 0.02 0.00  Coquille 0.00 0.00 0.00 0.02 0.02 0.00 0.00 0.00 0.00 0.00 Mid-south averagec 0.00 0.00 0.02 0.03 0.02 0.00 0.00 0.00 0.00 0.00 

Coastwide rivers 0.17 0.11 0.09 0.21 0.15 0.07 0.22 0.11 0.16 0.03 Lakes 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Coastwide total 0.17 0.11 0.09 0.21 0.15 0.07 0.22 0.11 0.16 0.03 

a Data from 1990 to 1997 are based on scale analysis. b Data from 1998 to 2002 are based on fin clips. c Excluding Floras Creek and Sixes River. 

338 
28. Southern Oregon/Northern California Coast 

Coho Salmon ESU 

Summary of Previous BRT Conclusions 

The Southern Oregon/Northern California Coast (SONCC) coho salmon ESU extends 

from Cape Blanco in southern Oregon to Punta Gorda in northern California (Weitkamp et al. 

1995). The status of coho salmon coastwide, including the SONCC ESU, was formally assessed 

in 1995 (Weitkamp et al. 1995). NMFS has published two subsequent status review updates, one 

addressing all West Coast coho salmon ESUs (NMFS 1996b) and a second specifically 

addressing the Oregon Coast coho salmon and SONCC coho salmon ESUs (NMFS 1997c). 

Information from those reviews regarding extinction risk, risk factors, and hatchery influences is 

summarized in the following subsections. 

Status Indicators and Major Risk Factors 

California populations 

Data on population abundance and trends were limited for the California portion of the 

SONCC coho salmon ESU. The BRT found no regular estimates of natural spawner escapement 

for coho salmon in the ESU, and most information used by the BRT came from reviews by 

California Department of Fish and Game (CDFG 1994a) and Brown et al. (1994). Historical 

point estimates of coho salmon abundance for the early 1960s and mid-1980s cited in these 

reviews were taken from CDFG (1965), Wahle and Pearson (1987), and Sheehan (1991).45 

These estimates suggest that statewide coho spawning escapement in the 1940s ranged between 

200,000 and 500,000 fish.46 By the early to mid-1960s, statewide escapement was estimated to 

have declined to just under 100,000 fish (CDFG 1965), with approximately 43,000 fish (44%) 

originating from rivers within the SONCC ESU (Table 72). Wahle and Pearson (1987) 

estimated that statewide coho salmon escapement had declined to approximately 30,000 fish by 

the mid-1980s, with about 12,400 (41%) originating within the SONCC coho salmon ESU. For 

the late 1980s, Brown et al. (1994) estimated wild and naturalized coho salmon populations at 

13,240 for the state, and 7,080 (53%) for the California portion of the SONCC coho salmon 

ESU. To derive their estimate, they employed a “20-fish rule,” in which all streams known to 

historically support coho salmon, except those for which recent surveys indicated coho salmon 

 

45For mid-1980s estimates, Brown et al. (1994) cite Wahle and Pearson (1987), who estimate 30,480 total spawners 

in California, whereas CDFG (1994) cites Sheehan’s (1991) estimate of 33,500 spawners. It is unclear how 

Sheehan’s estimates were derived, and no basin-specific estimates are presented. Thus, we have included the 

estimates of Wahle and Pearson (1987) in Table 71, rather than the Sheehan’s (1991) estimates, cited by the BRT 

(Weitkamp 1995). 

46E. Gerstung, California Depart of Fish and Game, pers. commun., cited in Brown et al. (1994). 

339 
COHO SALMON

Table 72. Historical estimates of coho salmon spawner abundance for various rivers and regions within 

the Southern Oregon/Northern California Coast (SONCC) coho salmon ESU. 

Estimated escapement 

CDFG (1965)a

Wahle and Pearson 

(1987)b

Brown et al. 

(1994)c

River/region 1965 1984–1985 1987–1991 

California rivers tributaries 

to Oregon coast streams 1,000 

Smith River 5,000 2,000 820d

Other Del Norte County 400 180d

Klamath River 15,400 3,400 1,860 

 Mainstem Klamath River 

 and tributaries 8,000 1,000 

 Shasta River 800 300 

 Scott River 800 300 

 Salmon River 800 300 

 Trinity River 5,000 1,500 

Redwood Creek 2,000 500 280 

Mad River 2,000 500 460 

Eel River 14,000 4,400 2,040d

 Mainstem Eel River 500 200 

 Van Duzen River 500 200 

 South Fork Eel River 13,000 4,000 

 North Fork Eel River 0 0 

 Middle Fork Eel River 0 0 

Mattole River 2,000 500 760d

Other Humboldt County 1,500 1,130 680d

ESU total 43,300 12,430 7,080 

California statewide totale 99,400 30,480 13,240 

a

 Excludes ocean catch. CDFG = California Department of Fish and Game. 

b

 Estimates are for wild or naturalized fish; hatchery returns excluded. 

c

 Estimates are for wild or naturalized fish; hatchery returns excluded. For streams without recent spawner estimates 

(or estimates lower than 20 fish), assumes 20 spawners. 

d Indicates high probability that natural production is by wild fish rather than naturalized hatchery stocks. e

 Estimated number of coho salmon for Central California Coast coho salmon ESU and California portion of the 

SONCC coho salmon ESU combined. 

no longer persist (19% of the total), were assumed to still support 20 spawners. For streams 

where a recent estimate of spawner abundance existed, they used either that estimate or 20 fish, 

whichever was larger. They suggested that application of the “20-fish rule” likely overestimated 

total abundance. As Brown et al. (1994) pointed out, all of these historical estimates are 

“guesses” that fishery managers and biologists generated using a combination of limited catch 

statistics, hatchery records, and personal observations. 

Additional information regarding the status of coho salmon in the SONCC coho salmon 

ESU was obtained from an analysis of recent (1987–1991) occurrence of coho salmon in streams 

340 
28. SOUTHERN OREGON/NORTHERN CALIFORNIA COAST COHO SALMON ESU 

historically known to support coho populations (Brown et al. 1994). Of 115 historical streams in 

the SONCC coho salmon ESU for which recent data were available, 73 (63%) were determined 

to still support coho salmon, whereas it was believed they had been lost from 42 (37%). The 

estimated percentage of streams with coho salmon still present was lower for Del Norte County 

(55%) than for Humboldt County (69%). NMFS (1996b) presented more recent data 

(1995–1996) on presence of coho salmon within the SONCC ESU, which suggested that the 

percentage of streams still supporting coho salmon was lower than estimated by Brown et al. 

(1994). Of 176 streams recently surveyed in the SONCC ESU, 92 (52%) were found to still 

support coho salmon (P. Adams47). The estimated percentage of streams still supporting coho 

salmon was lower (46%) in Del Norte County than in Humboldt County (55%). 

The BRT also considered two recent reviews assessing the status of coho salmon stocks 

in California. Nehlsen et al. (1991) identified coastal populations of coho salmon north of San 

Francisco Bay (includes portions of the SONCC and Central California Coast coho salmon 

ESUs) as being at moderate risk of extinction and Klamath River coho salmon as a stock of 

special concern. The Humboldt chapter of the American Fisheries Society (Higgins et al. 1992), 

using more detailed information on individual river basins, considered three stocks of coho 

salmon in the SONCC coho salmon ESU as being at high risk of extinction (Scott River 

[Klamath], Mad River, and Mattole River), and eight more stocks as being of special concern 

(Wilson Creek, lower Klamath River, Trinity River, Redwood Creek, Little River, Humboldt 

Bay tributaries, Eel River, and Bear River).48

Oregon populations 

For the 1997 status update (NMFS 1997c), the BRT was asked to evaluate the status of 

the ESU under two conditions: 1) under existing conditions; 2) assuming that hatchery and 

harvest reforms of the Oregon Coastal Salmon Restoration Initiative (OCSRI) were implemented. 

Evaluation under existing conditions 

In the Rogue River basin, natural spawner abundance in 1996 was slightly above 1994 

and 1995 levels. Abundances in the most recent 3 years were all substantially higher than 

abundances in 1989–1993 and were comparable to counts at Gold Ray Dam (upper Rogue) in the 

1940s. Estimated return ratios for 1996 were the highest on record, but this may have been 

influenced by an underestimate of parental spawners. The Rogue River run included an 

estimated 60% hatchery fish in 1996, comparable to previous years. The majority of these 

hatchery fish returned to Cole Rivers Hatchery, but there was no estimate of the number that 

strayed into natural habitat. 

 

47P. Adams, Southwest Fisheries Science Center, pers. commun., cited in NMFS (1996b). 

48Weitkamp et al. (1995), citing Higgins et al. (1992), indicate that the numbers of stocks at “moderate risk of 

extinction” and “of special concern” in the SONCC Coho salmon ESU are 6 and 10, respectively. These numbers 

appear to be in error. 

341 
COHO SALMON

Evaluation with hatchery and harvest reforms 

The BRT considered only two sets of measures from the OCSRI—harvest management 

reforms and hatchery management reforms. The BRT did not consider the likelihood that these 

measures would be implemented; rather, it only considered the implications for ESU status if 

these measures were fully implemented as described. The BRT expressed several concerns 

regarding the harvest and hatchery components of the OCSRI plan. Some BRT members were 

greatly concerned that we do not know enough about the causes of declines in run size and 

recruits per spawner to directly assess the effectiveness of specific management measures. Some 

members felt that harvest measures were the most encouraging part of the plan, representing a 

major change from previous management. However, another concern was that the harvest plan 

might have been seriously weakened when it was reevaluated in 2000 as well as concern about 

our ability to effectively monitor nontarget harvest mortality and control overall harvest impacts. 

Of the proposed hatchery measures, substantial reductions in smolt releases were thought 

to have the most predictable benefit for natural populations; all else being equal, fewer fish 

released should result in fewer genetic and ecological interactions with natural fish. Marking all 

hatchery fish should also help to resolve present uncertainties about the magnitude of these 

interactions. However, the BRT expressed concerns regarding some aspects of the proposed 

hatchery measures. The plan was vague on several key areas, including plans for incorporation 

of wild broodstock and how production was to be distributed among facilities after 1997. One 

concern was that the recent and proposed reductions appear to be largely motivated by economic 

constraints and the present inability to harvest fish if they were produced rather than by 

recognition of negative effects of stray hatchery fish on wild populations. Other BRT concerns 

included no reductions in fry releases in many basins and no consideration of alternative culture 

methods that could be used to produce higher-quality hatchery smolts, which may have less 

adverse impact on wild fish. Another concern was the plan’s lack of recognition that hatcherywild interactions reduce genetic diversity among populations. 

Specific risk factors BRT identified included low current abundance, severe decline from 

historical run size, the apparent frequency of local extinctions, long-term trends that are clearly 

downward, degraded freshwater habitat and associated reduction in carrying capacity, and 

widespread hatchery production using exotic stocks. Of particular concern to the BRT was 

evidence that hatchery releases of coho salmon heavily influenced several of the largest river 

basins in the SONCC—including the Rogue, Klamath, and Trinity rivers. Historical transfer of 

stocks back and forth between SONCC and Central California Coast coho salmon ESU streams 

was common, and SONCC streams have also received plants from stocks from hatcheries in the 

Lower Columbia River/Southwest Washington, Puget Sound/Strait of Georgia, and Oregon 

Coast coho salmon ESUs. However, the BRT considered the frequency of out-of-basin plants to 

be relatively low compared with other coho salmon ESUs. Recent (late 1980s and early 1990s) 

droughts and unfavorable ocean conditions were identified as further likely causes of decreased 

abundance. 

342 
28. SOUTHERN OREGON/NORTHERN CALIFORNIA COAST COHO SALMON ESU 

Previous BRT Conclusions 

In the 1995 status review, the BRT was unanimous in concluding that coho salmon in the 

SONCC coho salmon ESU were not in danger of extinction, but were likely to become so in the 

foreseeable future if present trends continued (Weitkamp et al. 1995). In the 1997 status update, 

estimates of natural population abundance in this ESU were based on very limited information. 

Favorable indicators included recent increases in abundance in the Rogue River and the presence 

of natural populations in both large and small basins, factors that may provide some buffer 

against extinction of the ESU. However, large hatchery programs in the two major basins 

(Rogue and Klamath/Trinity) raised serious concerns about effects on, and sustainability of, 

natural populations. New presence-absence data from northern California streams that 

historically supported coho salmon were even more disturbing than earlier results, indicating that 

a smaller percentage of streams in this ESU contained coho salmon compared to the percentage 

presence in an earlier study. However, it was unclear whether these new data represented actual 

trends in local extinctions, or were biased by sampling effort. This new information did not 

change the BRT’s conclusion regarding the status of the SONCC coho salmon ESU. Although 

the OCSRI proposals were directed specifically at the Oregon portion of this ESU, the harvest 

proposal would affect ocean harvest of fish in the California portion as well. The proposed 

hatchery reforms can be expected to have a positive effect on the status of populations in the 

Rogue River basin. However, the BRT concluded that these measures would not be sufficient to 

alter the previous conclusion that the ESU is likely to become endangered in the foreseeable 

future. 

Coho salmon in the SONCC ESU were listed as threatened in May 1997 (NMFS 1997e). 

On 18 July 1997, NMFS published an interim rule (NMFS 1997c) that identified several 

exceptions to the ESA’s Section 9 take prohibitions. 

Listing status: Threatened.

New Data and Updated Analyses 

Because data types and sources differ substantially between the California and Oregon 

portions of the ESU, we present information separately for each area. 

California Populations 

Since the status review for West Coast coho salmon (Weitkamp et al. 1995) and 

subsequent updates (NMFS 1996b, and NMFS 1997c) were completed, new data and analyses 

related to the status of coho salmon in the California portion of the SONCC ESU have become 

available. Most data are of two types: 1) compilations of presence-absence information for coho 

streams from the period 1987 to 2000, and 2) new data on densities of juvenile coho salmon in 

index reaches surveyed by private timber companies. We found no time series of adult counts 

(excepting those substantially influenced by hatchery production), and only five time series of 

adult spawner indices (maximum live/dead counts) for tributaries of the Eel River (Sprowl 

Creek), the Mad River (Canon Creek), and the Smith River (West Branch of Mill Creek [two 

data sets] and East Branch of Mill Creek) that span a period of 8 years or more, none of which 

343 
COHO SALMON

are considered reliable indicators of population trends. Limitations of these data sets are 

discussed in detail below. 

Two independent analyses of presence-absence and limited time-series data for the 

SONCC have been published recently. CDFG (2002a) analyzed coho salmon presence-absence 

data for SONCC streams spanning broodyears 1986–2000. NMFS (2001b) published an updated 

status review for coho salmon in the California portion of the SONCC, which also included 

analysis of presence-absence information. Since then, scientists at the Southwest Fisheries 

Science Center have continued compiling data on coho salmon distribution and abundance and 

reanalyzed the updated data, inclusive of data used in the CDFG (2002c) analysis. Thus, results 

presented in this report supercede those presented in NMFS (2001b). 

CDFG Presence-Absence Analysis 

Methods 

Staff at the CDFG North Coast Region attempted to gather all published and unpublished 

data collected for 392 streams identified by Brown and Moyle (1991) as historical coho salmon 

streams.49 Sources of data included field notes, planting records, and fish surveys from federal, 

state, and tribal agencies; private landowners; and academic institutions, as well as summaries 

contained in several recently published status reviews (Ellis 1997, Brownell et al. 1999, and 

NMFS 2001b). For each stream and year in which surveys were conducted, observations of 

coho salmon presence or absence were assigned to the appropriate broodyear. If more than one 

life stage was observed during a survey, then presence was assigned to more than one broodyear. 

Streams that were not surveyed during a particular year were assigned a “presence” value if fish 

were documented in an upstream tributary during that year. Overall, the CDFG data set 

encompasses records from broodyears 1986 to 2000, or five complete brood cycles. 

Additionally, CDFG (2002c) presented results of an extensive field study conducted in the 

summer of 2001 in which 287 of the 392 Brown and Moyle (1991) streams were surveyed for 

juvenile coho salmon presence-absence.50

For their broodyear analysis, CDFG (2002c) compared the percentage of streams for 

which coho salmon were detected at any time during two time periods: broodyears 1986–1991 

and 1996–2000. The first period was designed to coincide with the period encompassed by the 

Brown and Moyle (1991) study. Statistics were generated based on data from all streams within 

the SONCC on the original Brown and Moyle list, as well as the subset of these streams that 

were sampled at least once during each of the two time periods. CDFG (2002c) also calculated 

the percentage of streams for which coho salmon were detected in the 2001 field survey. 

 

49Brown and Moyle (1991) identified 396 streams in California as historical coho streams; however, four of those 

streams were dropped by CDFG, either because barriers make historical occupancy highly unlikely, because the 

record of occurrence likely reflects a hatchery outplanting, or because streams were duplicated in the Brown and 

Moyle list. 

50CDFG repeated their survey of Brown and Moyle (1991) streams in the summer of 2002; however, the Brown and 

Moyle data were unavailable at the time of the CDFG analysis. 

344 
28. SOUTHERN OREGON/NORTHERN CALIFORNIA COAST COHO SALMON ESU 

Results 

Including only streams on the Brown and Moyle list, CDFG (2002c) found that coho 

salmon were observed in 143 of 235 (61%) streams surveyed during the period covering 

broodyears 1986–1991 (Table 73). This number is similar to the value of 63% found by Brown 

and Moyle (1991) based on information on about half as many streams (115). For broodyears 

1995–2000, surveys were conducted on 355 of the 392 historical coho salmon streams. Of these, 

coho salmon were detected in 179 (50%), suggesting a decline in occupancy. However, when 

the analysis was restricted to only the 223 streams for which data were available from both time 

periods, the percent of streams in which coho were detected went from 62% in 1986–1991 to 

57% in 1995–2000, a change that was not statistically significant (Pearson chi square test, p = 

0.228; Yates corrected chi square test, p = 0 .334). 

For the 2001 field survey, presence was confirmed in only 121 (42%) of the 287 streams 

surveyed within the SONCC coho salmon ESU. CDFG (2002c) makes two cautions in 

interpreting their year-2001 results. First, CDFG considered sampling intensity to be sufficient 

to have a high likelihood of detecting fish for only 110 of the 166 streams where coho salmon 

were not found. Second, they note that absence of fish in a single year class does not mean that 

fish have been extirpated from the system. 

NMFS Presence-Absence Analysis 

Methods 

Scientists at the NMFS Southwest Fisheries Science Center compiled a presence-absence 

database for the SONCC coho salmon ESU similar to that developed by CDFG. The data set 

includes information for coho salmon streams listed on the Brown and Moyle (1991) list, as well 

as other streams for which we have found historical or recent evidence of coho salmon presence. 

The data set is a composite of information contained in the NMFS (2001b) status review update, 

additional information gathered by NMFS since publication of the 2001 status review, data used 

in the CDFG (2002c) analysis, and additional data compiled by CDFG (Jong 2002) for streams 

not on the Brown and Moyle (1991) list. As such, the database combines information taken from 

primary sources such as stream surveys, data reports, and electronic files, as well as from 

secondary sources, including recent compilations of presence-absence data by Ellis (1997), 

Brownell et al. (1999), NMFS (2001b), CDFG (2002b), and Jong (2002). In many cases, we 

were unable to obtain original sources underlying the various data compilations, so we generally 

relied on the accuracy of these secondary sources. 

There are four significant differences between the data and analytical approach used by 

NMFS as compared with CDFG’s (2002c) status review. First, the NMFS analyzed data for all 

streams with some historical record of coho salmon presence, whereas CDFG restricted their 

analysis to those streams found on the Brown and Moyle (1991) list. Second, the NMFS 

database spans a slightly different time period: broodyears 1987–2001 (rather than 1986 to 

2000). At the time these data were compiled, data from summer 2002 field surveys were only 

partially reported; thus, results from broodyear 2001 are preliminary. Third, unlike CDFG 

(2002c), we did not infer presence in streams on the basis of occurrence in upstream tributaries. 

Although there is an intuitive logic to assigning presence to streams en route to a particular 

345 
Table 73. Historical presence of coho salmon in the Southern Oregon/Northern California Coast (SONCC) ESU, as determ

Moyle (1991) and the California Department of Fish and Game’s presence-by-broodyear investigation (as of Febru

Table modified from CDFG (2002c). 

Brown and Moyle (1991) 

calendar years 1987

–1990 

CDFG (2002c) 

broodyears 1986

–1991 

CD

broody

County*/river basin 

No. of 

streams 

No. of 

streams with 

information

Coho 

present

%

No. of 

streams

No. of 

streams with 

information 

Coho 

present

%

No. of 

streams

stre

inf

Del Norte Cou nty

Coastal 9 1 1 8 5 3 8 Smith River 41 2 2 41 21 7 41 Klamath River 113 41 21 112 82 48 112 

Subtotal 163 44 24 54 161 108 58 53 161 Humboldt County 

Coastal 34 7 7 33 16 14 33 Redwood Creek 14 3 3 14 12 12 14 Mad River 23 2 2 23 10 8 23 Eel River 124 56 34 123 80 48 123 Mattole River 38 3 3 38 9 3 38 

Subtotal 233 71 49 69 231 127 85 67 231 ESU total 396 115 73 63 392 235 143 61 392 

* County classifications are based on the location of the mouth of the river system. 

346 
28. SOUTHERN OREGON/NORTHERN CALIFORNIA COAST COHO SALMON ESU 

location, including these “inferred presence” values in the analysis tends to positively bias the 

overall estimate of percent occupancy because the same rationale for inference cannot be applied 

in the case of a recorded “absence.” The magnitude of this bias on estimated occupancy rates for 

a given year depends on several factors, including the proportion of streams sampled, the true 

occupancy rate for the year, and basin size, all of which affect how many inferences of presence 

can be made. Finally, in our analysis, we present summary information both by broodyear and 

by brood cycle (3-year aggregation). In contrast, the CDFG (2002c), in its broodyear analysis 

calculated percent occupancy for 6-year time spans (two complete brood cycles): any 

observation of presence during that 6-year window resulted in a value of presence for the entire 

period. 

Concerns have been expressed (CDFG 2003b) about the validity of including certain 

streams cited as historical coho streams in various previously published status reviews. We have 

removed streams from our list that we found to be in error, including those CDFG explicitly 

identified as questionable. However, we retained information provided by secondary sources in 

the absence of contradictory information. We also compared our historical stream list with 

CDFG’s and found that, although the NMFS stream list includes some streams not found on 

CDFG’s list, most of them have limited, if any, data associated with them. We estimate that 

observations associated with these streams constitute only about 1% of the more than 9,000 

observations in the database, and the proportion of “presence” values in this subset is comparable 

to those observed for the entire data set. Thus, even if some of these streams are found to be in 

error, including them likely has minimal effect on estimated occupancy rates for the ESU. 

Results for the NMFS presence-absence analyses are presented by major watersheds or 

aggregations of adjacent watersheds (Table 74). In general, results from larger watersheds are 

presented independently, whereas data from smaller coastal streams, where data were relatively 

sparse, are grouped together. In a few cases, individual smaller coastal streams with only a few 

observations were aggregated with adjacent larger streams if there was no logical geographic 

grouping of smaller streams. We did not perform statistical analyses of temporal trends in 

estimated occupancy rates because of the substantial variation in the sampling methods and 

intensities represented in the data set, both at the level of individual observations (e.g., index 

reaches versus whole stream surveys) and among years (i.e., changes in the number of streams 

surveyed or the principal survey methods through time). Fitting a statistical model to these data 

without better understanding of the underlying error structure would be of questionable value 

and would give an illusion of analytical rigor that is likely not supported by the underlying data. 

Results 

On an annual basis, the estimated percentage of streams in the SONCC for which coho 

salmon presence was detected generally fluctuated between 36% and 61% between broodyears 

1986 and 2000 (Figure 204). Data reported for the 2001 broodyear suggest a strong year class, 

as indicated by an occupancy rate of more than 75%; however, the number of streams for which 

data were reported is small compared to previous years. The data suggest that, for the period of 

record, occupancy rates in the SONCC were highest (54–61%) between broodyears 1991 and 

1997, then declined between 1998 and 2000 (39–51%) before rebounding in 2001. The pattern 

347 
Table 74. Percent of surveyed streams within the Southern Oregon/Northern California Coast (SONCC) ESU for which co

detected for four time intervals: broodyears 1987

–1989, 1990

–1992, 1993

–1995, 1996

–1998, and 1999

–2001. Str

which historical or recent evidence of coho salmon presence exists (based on NMFS and CDFG data, excluding infCDFG data). 

1987–1989 1990–1992 1993–1995 1996–1998 

County and river basins 

No. of 

streams 

with 

historical 

presence 

No. 

surveyeda

% Coho 

presentb

% Coho 

absent

c

No. 

surveyeda

% Coho 

present

b

% Coho 

absent

c

No. 

surveyeda

% Coho 

present

b

% Coho 

absent

c

No. 

surveyeda

% Coho 

present

b

% Coho 

absent

c

Del Norte (includes Oregon tributaries) Illinois River 9 0 – – 2 100 0 2 50 50 7 100 0 Smith RiverWinchuck River 57 20 20 80 19 42 58 45 53 47 28 32 68 Klamath River - 

Trinity River 210 128 66 34 127 72 28 139 68 32 135 62 38 

Humboldt Redwood Creek 23 10 80 20 10 100 0 19 79 21 13 92 8 Stone/Big lagoons 5 1 0 100 2 100 0 1 0 100 2 50 50 Litte RiverStrawberry Creek 9 8 100 0 9 100 0 6 100 0 5 100 0 Mad River 23 8 100 0 7 86 14 7 86 14 9 78 22 Humboldt Bay 

tributaries 48 20 95 5 16 94 6 32 97 3 17 88 12 

Eel River 221 109 47 53 126 59 41 132 58 42 59 31 69 Bear RiverGuthrie Creek 5 0 – – 0 – – 3 0 100 2 0 100 Mattole RiverMcNutt Gulch 56 5 60 40 11 36 64 21 71 29 42 79 21 ESU Total 666 309 60 40 329 67 33 407 66 34 319 60 40 a Total number of steams surveyed at least once within the 3-year interval. b Percentage of surveyed streams in which coho were present in one or more years during the interval.c Percentage of surveyed streams in which coho were absent in all years of survey during the interval. 

348 
28. SOUTHERN OREGON/NORTHERN CALIFORNIA COAST COHO SALMON ESU 

0.1

0.2

0.5

0.7

0.4

0.6

0.8

1

1985 1989 1993 1995 1999 2001

Broodyear

199 227

231

263

244

239

122 396

169 165

151

167

181

0

0.9

1987

193

288 181

331

Brown & Moyle streams

0.3

1991 1997

136

208

182

214

222 209

52

172

139

170

157 182

156

205

41

All streams

Proportion of streams with coho present

Figure 204. Proportion of streams surveyed in which coho salmon presence was detected, by broodyear, 

for all historical coho streams (open triangles) and coho streams identified in Brown and Moyle’s 

(1991) historical list (closed triangles) within the Southern Oregon/Northern California Coast 

coho salmon ESU. Sample sizes (i.e., number of streams surveyed) are shown next to data 

points. Source: Spence (2001). 

is similar whether all historical coho streams or just those identified in Brown and Moyle (1991) 

are considered (Figure 204). 

When data were aggregated over complete brood cycles (3-year periods), the percentage 

of streams in which coho salmon presence was detected remained relatively constant (between 

60% and 67%) between the 1987–1989 and 1996–1998 brood cycles (Table 74). Percent 

occupancy for the 1999–2001 brood cycle was lower, at 46%; however, interpretation of this 

apparent decline is complicated by two factors. First, the number of streams surveyed was 

higher than in any other period due to CDFG’s intensive survey of the Brown and Moyle streams 

in the summer of 2001, a drought year. Second, reporting from the 2002 summer season 

(broodyear 2001) remains incomplete, and as noted above, preliminary data indicate that the 

2001 broodyear was strong. Thus, it is likely that the percent occupancy for this period will 

increase after all data from CDFG’s 2002 survey and other sources are analyzed. When analysis 

was restricted to streams on the Brown and Moyle (1991) list, the ESU-wide pattern was almost 

identical, with percent occupancy values being within 1% to 2% for all time periods (data not 

shown). Overall, it appears that, although there is considerable year-to-year variation in 

estimated occupancy rates, there has been no dramatic change in the percent of coho salmon 

streams occupied from the late 1980s and early 1990s to 2000.

In general, the proportion of streams sampled within any individual watershed (or 

grouping of watersheds) was sufficiently small or variable among time periods to make 

interpretation of local trends difficult. The most notable exception was the Eel River, which 

showed occupancy rates declining from between 48% and 58% in the period between 1987 and 

349 
COHO SALMON

1995 to about 30% in the past two brood cycles. Similarly, the percentage of streams with coho 

salmon presence in the Klamath-Trinity system appears to have declined over the five brood 

cycles examined, though the magnitude of the decline is smaller: from between 66% and 71% in 

1987 to 1995 to 62% and 55% in the past two brood cycles. In both cases, reporting from the 

2001 broodyear is incomplete, and anecdotal reports suggest that inclusion of more data from the 

2002 sampling year (2001 broodyear) may increase the observed percentages because of the 

relatively strong adult returns in the winter of 2001–2002. Thus, these apparent declines should 

be interpreted with caution. Still, the relatively low percentage of streams that still support coho 

salmon in the Eel River and the possible downward trend in the Klamath River basin, despite 

continued heavy hatchery influence, are cause for concern given that these are the largest river 

basins in the California portion of the SONCC, and, if historical estimates are accurate (Table 

72), once accounted for are well over half the coho salmon produced in the California portion of 

the SONCC ESU. 

The results of NMFS analysis are generally consistent with those of CDFG (2002c), both 

suggesting a general decline in occupancy rates in from the late 1980s and early 1990s to the end 

of the 1990s, the significance of which remains somewhat uncertain because of nonsystematic 

collection of presence-absence information and variation in sampling intensity (i.e., the number 

of streams surveyed) through the period. NMFS (2001b) suggested that declines in percent 

occupancy in the SONCC from 1989 to 2000 were significant; however, the addition of new data 

makes us more cautious in this interpretation. Although the trend remains apparent, the 

magnitude of change is less than the previous data indicated. A more exhaustive examination of 

SONCC region stream surveys compiled by CDFG substantially increased the total number of 

observations in the data set (especially in the earliest years). Those additional observations were 

strongly weighted toward “absences.” Regardless no evidence suggests that occupancy rates 

have increased since the original status review for SONCC coho salmon was published in 1995. 

Adult Time Series 

Reliable current time series of naturally produced adult migrants or spawners are not 

available for SONCC ESU rivers. CDFG has conducted annual spawner surveys on 4.5 miles of 

Sprowl Creek, tributary to the Eel River, since 1974 (except in 1976–1977) and on 2 miles of 

Cannon Creek, tributary to the Mad River, since 1981 (PFMC 2002b). However, these surveys 

are conducted primarily to generate minimum Chinook salmon counts, and the likelihood of 

detecting coho salmon is influenced strongly by the frequency of sampling and environmental 

conditions (i.e., turbidity) during those surveys (CDFG 2003b). Spawner surveys were 

conducted on the West Branch Mill Creek, a tributary to the Smith River, from 1980 to 2001 

(Waldvogel 2002). Peak live/dead counts fluctuated between 2 and 28 fish during this period, 

again making their use for trend analysis inappropriate. Surveys have also been conducted on 

the West Branch (4.7 miles) and East Branch (5.4 miles) of Mill Creek by Stimson Timber 

Company since 1993. Maximum live/dead counts recorded by Stimson on the West Branch 

averaged 62 fish between 1993 and 1996, declining to an average of 4 fish between 1997 and 

2000. On East Branch, maximum live/dead counts averaged 32 fish between 1993 and 1996, 

declining to an average of 6 fish between 1997 and 2000 (Howard 1998; Albro 2002). Howard 

(1998) notes that the reliability of these counts varies with flow conditions. 

350 
28. SOUTHERN OREGON/NORTHERN CALIFORNIA COAST COHO SALMON ESU 

Juvenile Time Series 

Methods 

Juvenile density was estimated during summer over the past 8 to 18 years at seven index 

sites within the Eel River basin: Upper Indian Creek, Moody Creek, Piercy Creek, Dutch Charlie 

Creek, and Redwood Creek in the South Fork Eel River basin (Wright and Levesque 2002), and 

at two sites on Hollow Tree Creek in the Middle Fork Eel basin (Harris 2002a, 20002b, and 

2002c). We analyzed juvenile density to determine whether such patterns observed in juveniles 

are consistent with those observed in the presence-absence information analyses. 

To estimate a trend, data were log-transformed, then normalized so that each data point 

was expressed as a deviation from the mean of that specific time series. The normalization was 

intended to prevent spurious trends that could arise from different methods of data collection. 

Following transformation, time series were aggregated, based on watershed structure, into groups 

thought to plausibly represent independent populations. Linear regression was used to estimate 

trends (i.e., slopes) for each aggregate data set. Analysis was restricted to 1) sites where a 

minimum of 8 years of data was available, and 2) putative populations where more than 65% of 

the observations were nonzero values. 

Results 

Aggregate trends were estimated separately for the South Fork and Middle Fork Eel river 

sites. In both cases, trends were positive, but not significantly different from 0 (South Fork, 

slope 0.053, 95% confidence interval from –074 to 0.180; Middle Fork, slope 0.016, 95% 

confidence interval from –0.051 to 0.180). 

Oregon Populations 

One effect of the OCSRI has been increased monitoring of salmon and habitats 

throughout the Oregon coastal region. Besides continuation of the abundance data series 

analyzed in the 1997 status update, Oregon has expanded its random survey monitoring to 

include areas south of Cape Blanco, including monitoring of spawner abundance, juvenile 

densities, and habitat condition. 

Spawner abundance 

In the Oregon portion of the ESU, spawner abundance is monitored only in the Rogue 

River basin. Other small coastal basins have limited coho salmon habitat, and are not thought to 

have sustainable local coho salmon populations (Jacobs et al. 2002). Within the Rogue Basin, 

two methods are used to monitor adult abundance: beach-seine surveys conducted at Huntley 

Park in the upper estuary and stratified-random spawning ground surveys (Jacobs et al. 2002). 

The Huntley Park seine estimates provide the best overall assessment of both naturally produced 

and hatchery coho salmon spawner abundance in the basin (Figure 206). Spawner survey–based 

abundance estimates are also available for the basin beginning in 1998, when the surveys were 

expanded south of Cape Blanco. These estimates are consistently lower than the seine-based 

estimates, which may be due in part to losses during upstream migration (Jacobs et al. 2002); 

351 
COHO SALMON

however, ODFW considers the seine-based estimates to be more accurate as an overall 

assessment of spawner abundance.51 The spawning-ground surveys allow examination of the 

distribution of spawners among subbasins: in 2001, the majority of spawners were in main 

tributaries (Illinois and Applegate rivers and Evans and Little Butte creeks). 

The occurrence of hatchery fish in natural spawning areas is also a consideration for the 

productivity of the natural population. Roughly half of the total spawning run in the Rogue 

River basin is hatchery fish; however, many of these fish return to Cole Rivers Hatchery, rather 

than spawning in natural habitat. Based on fin-mark observations during spawning-ground 

surveys, the average percent of natural spawners that are of hatchery origin has ranged from less 

than 2% (2000) to nearly 20% (1998) in recent years. These hatchery spawners are largely 

concentrated in the mainstem tributaries, with very few hatchery fish observed in major 

tributaries (Jacobs et al. 2002). 

Results 

Mean spawner abundance and trends for Rogue River coho salmon are given in Table 75. 

(Note that because estimates of hatchery-origin fish on the spawning ground are not available for 

most years, lambda (λ) was not computed for this population.) Both short- and long-term trends 

in naturally produced spawners are upward; however, this increasing trend in spawners results 

largely from reduced harvest, as trends in preharvest recruits are smaller (Figure 205, Table 75). 

Recruits per spawner fluctuate widely, with little apparent trend (Figure 205). Fluctuations in 

naturally produced spawner abundance are generally in phase with survival of hatchery fish 

(Figure 206), suggesting that ocean conditions play a large role in population dynamics. Note 

that hatchery-fish survival for the Rogue River stock is generally higher and follows a different 

pattern than the general OPI survival index (see Section 27, Oregon Coast Coho Salmon ESU). 

Juvenile density 

Regular monitoring of juvenile coho salmon in the Oregon portion of the SONCC ESU 

began in 1998, and 4 years of data are currently available, as reported in Rodgers (2002). 

Several statistics are reported, including percent occupancy and mean density. Methods differ 

from the California surveys reported above, so direct comparison of results is problematic. The 

most comparable statistic to the California presence-absence data is “percentage of sites with at 

least one pool containing coho,” which has been steadily increasing from about 30% in 1998 to 

58% in 2001; this rate compares with a range of 52% to 80% for other parts of the Oregon coast. 

Percentage of pools per site containing coho salmon has also increased, reaching 41% (SE 4.9%) 

in 2001. Mean juvenile density has also increased over the 3 years. In 2001, overall mean 

density of juveniles in surveyed pools was 0.38 fish/m2

; this compares with a range of 0.27/m2 to 

0.50/m2 for other areas of the Oregon coast. 

 

51S. Jacobs, Oregon Department of Fish and Wildlife, Corvallis, OR. Pers. commun., October 2002. 

352 
0

40008000

1200016000

1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Natural Origin

0

40008000

1200016000

1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Natural Origin

0

40008000

1200016000

1975 1980 1985 1990 

Year

Abundance

A) B) Spawners 

C) 

0.101.00

10.00

100.00

1975 1980 1985 1990 1995 2000 2005

Spawner year

Recruits/spawner

Figure 205. Trends in Rogue river coho salmon populations, based on Oregon Department of Fish and Wildlife surveys at 

al. 2002. a. natural spawner abundance with 95% confidence interval.; b. preharvest recruits and spawner abundan

years) per spawner (note logarithmic scale). 

353 
COHO SALMON

0

1

2

3

4

5

1986 1988 1990 1992 1994 1996 1998 2000 2002

Broodyear

Survival (%)

Figure 206. Percent survival of coded-wire-tag-marked coho salmon from Cole Rivers Hatchery, 

calculated from data in Lewis (2002). 

Table 75. Abundance and trend estimates for Rogue River basin coho salmon natural spawners, 

estimated from Huntley Park seine data (Jacobs et al. 2002), 1980–2001. Shown are the most 

recent geometric mean (along with minimum and maximum values for the data series) and trend 

estimates for spawners and recruits, both long and short term, along with the probability that the 

true trend is decreasing. 

Parameter Value 

95% confidence 

interval 

P 

(decrease) 

Recent spawner abundance 

Last 3 years geometric mean 10,147 

Last 3 years arithmetic mean 10,326 

Last 3 years range 7,800–12,213 

Spawner trend 

Short term (1990–2002) 1.16 (1.01, 1.34) 0.02 

Long term (1980–2002) 1.08 (1.01, 1.15) 0.01 

Preharvest recruit trend 

Short term (1990–2002) 1.08 (.94, 1.25) 0.12 

Long term (1980–2001) 1.02 (0.95, 1.08) 0.27 

Habitat condition 

The Oregon Plan Habitat Survey (OPHS) began in 1998, as part of the ODFW Aquatic 

Inventories Project begun in 1990. Information here is derived from the survey’s year 2000 

report (Flitcroft et al. 2002). The survey selects 500-m to 1,000-m sites along streams according 

to a spatially balanced random selection pattern. The survey includes both summer and winter 

habitat sampling. In addition to characterization of the site’s streamside and upland processes, 

specific attributes sampled are large wood, pools, riparian structure, and substrate. The program 

has established benchmark thresholds as indicators of habitat quality: 

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28. SOUTHERN OREGON/NORTHERN CALIFORNIA COAST COHO SALMON ESU 

• Pool area greater than 35% of total habitat area, 

• Fine sediments in riffle units less than 12% of all sediments, 

• Volume of large woody debris greater than 20 m3 per 100-m stream length, 

• Shade greater than 70%, and 

• Large riparian conifers more than 150 trees per 305-m stream length. 

For the combined 1998–2000 surveys in the Oregon portion of the SONCC ESU, 6% of 

sites surveyed met none of the benchmarks, 29% met one, 38% met two, 20% met three, 5% met 

four, and 2% met all five benchmarks. No trends in habitat condition can yet be assessed from 

these data, but it will provide a basis for future assessment of changes in habitat quality. 

The Siskiyou County Farm Bureau (2002) submitted comments arguing that SONCC 

coho salmon should not be protected under the ESA, particularly because the relationship of Iron 

Gate Hatchery fish in the Klamath River to the SONCC ESU remains uncertain. Their principal 

argument is that widespread historical outplanting of juvenile coho salmon and incorporation of 

nonnative fish into hatchery broodstock make application of the ESU concept inappropriate; they 

argue that all West Coast coho salmon should be considered a single ESU. 

The Siskiyou Project submitted comments supporting continued listing of coho salmon in 

the SONCC under the ESA (Siskiyou Project 2002). They argue that: 

1. The status of native, naturally reproducing coho salmon in the SONCC remains 

unchanged since they were listed in 1997. 

2. Increases in adult coho salmon observed in 2001 and 2002 are mostly due to improved 

ocean conditions and reduced harvest, and are not indicative of long-term trends. 

3. Severe drought in the winter 2001–2002 and summer 2001 are likely to result in lower 

smolt production in spring 2002 and adult returns in 2003. 

4. Habitat already in poor condition is likely to deteriorate with increasing human demands 

for natural resources and inadequate regulations. 

5. Continued large releases of hatchery coho salmon pose a threat to naturally produced fish 

through competition, mixed-stock fishing, and reduced fitness associated with 

interbreeding of hatchery and wild fish. 

The Siskiyou Project also included a report authored by Cindy Deacon Williams (2002), 

private consultant, titled “Review of the Status of Southern Oregon/Northern California Coho 

with Thoughts on Recovery Planning Targets.” Williams’ report presents basin-by-basin 

assessments of the status of coho salmon (using primarily previously published analyses), habitat 

conditions, and ongoing activities that pose risks to coho salmon. She also recommends numeric 

recovery criteria for SONCC coho salmon and argues that habitat targets are needed to ensure 

recovery. 

The Douglas County Board of Commissioners submitted a report titled “Viability of 

Coho Salmon Populations on the Oregon and Northern California Coasts” to NMFS Protected 

Resources Division on 12 April 2002 (Cramer and Ackerman 2002). This report analyzes 

355 
COHO SALMON

information available for the Oregon Coast Coho Salmon ESU and the SONCC ESU in several 

areas: trends in abundance and distribution, trends in survival, freshwater habitat condition, 

potential hatchery-wild interactions, changes in harvest regulation, and extinction risk modeling. 

Little information presented in the report is specific to the SONCC ESU. The report cites 

changes in fishery management, increasing spawning escapements, reduced hatchery releases, 

habitat restoration, and evidence of successful rearing of fry outmigrants throughout the Oregon 

coast, some information for the Rogue River basin, but no new information for California 

populations. 

Daniel O’Hanlon (2002a, 2000b), attorney at law, submitted comments on two occasions 

on behalf of Save Our Shasta and Scott Valley Towns (SOSS), an organization of citizens 

concerned about the effects of ESA regulations. The latter submission includes comments 

submitted to the California Fish and Game Commission regarding the petition to list coho 

salmon in northern California under the state Endangered Species Act; the comments include, by 

reference, a critique of CDFG’s (2002c) status review prepared by Dr. Charles Hanson. 

Although the critique is of the state’s analysis of coho status, some of the arguments are germane 

to the federal status review because the underlying data are comparable. The essential arguments 

from this collection of documents are: 

1. The limited data presented in the initial status reviews was insufficient to assess, in a 

scientifically rigorous way, the degree of extinction risk facing coho salmon in the 

SONCC. 

2. There is no evidence of an immediate or near-term risk of extinction based on analysis of 

either presence-absence data or abundance trend data; presence-absence data have a 

number of weaknesses, and historical trend data (abundance and harvest) are unreliable. 

3. Existing regulatory structures are adequate to protect coho salmon; new regulations 

would hinder, rather than help coho recovery. 

The Yurok Tribal Fisheries Program (2002) submitted recent data from various sampling 

efforts in the lower Klamath River and its tributaries. Included were data from downstream 

migrant traps, adult snorkel surveys, tribal harvest, and harvest catch-per-unit effort. Data on 

relative contribution of naturally produced and hatchery fish to tribal harvest and to catch at the 

lower Klamath and lower Trinity downstream migrant trapping sites are discussed in the section 

below (New Hatchery Information). Other data were incorporated into NMFS presence-absence 

analyses discussed above. None of the time series available met the minimum criterion of 8 

years, which was decided on by the BRT as the minimum needed for trend analysis. 

New Hatchery Information 

Weitkamp et al. (1995) identified four hatcheries that were producing and releasing coho 

salmon within the SONCC ESU during the mid-1990s: Mad River Hatchery, Trinity River 

Hatchery, Iron Gate Hatchery, and Cole Rivers Hatchery. Prairie Creek Hatchery produced coho 

salmon for many years, but closed in 1992 (CDFG 2002c). Rowdy Creek Hatchery is a privately 

owned hatchery that has produced coho salmon in the past; however, the facility did not produce 

356
28. SOUTHERN OREGON/NORTHERN CALIFORNIA COAST COHO SALMON ESU 

coho salmon in 1999 and 2000 due to lack of adult spawners (CDFG 2002c), and no further 

production of coho salmon at this facility is planned.52

Iron Gate Hatchery 

Iron Gate Hatchery (IGH), located on the Klamath River near Hornbrook, California, 

approximately 306 km from the ocean, was founded in 1965 and is operated by the CDFG. The 

hatchery was built by Pacific Power and Light Company to mitigate effects of the Iron Gate 

Project on wild salmonids, including coho salmon, that naturally occurred in the upper Klamath 

River (CDFG 2002c; SSHAG 2003). The IGH coho stock was developed initially from eggs 

taken from Klaskanine Hatchery in Oregon, via Trinity River Hatchery in 1966. In an effort to 

increase returns to Iron Gate Hatchery, coho salmon from Cascade River (Columbia River) were 

released in 1966, 1967, 1969, and 1970 (CDFG 2002c, 2003b). Since 1977, only Klamath Basin 

fish have been released from IGH (CDFG 2003b). 

Annual releases of coho salmon from IGH have decreased from an average of 

approximately 147,000 fish from 1987 to 1991 to about 72,000 fish from 1997 to 1999 (Table 

76); this reduction in releases reflects effort on CDFG’s part to more closely adhere to the IGH 

mitigation goal of 75,000 yearlings released per year. Adult returns averaged 1,120 fish between 

1991 and 2000, and an average of 161 females have been spawned annually during this period. 

The CDFG and NMFS Southwest Region Joint Hatchery Review Committee (2001) 

noted that no accurate estimates of the relative contribution of naturally produced versus 

hatchery fish are available for the Klamath River basin. Beginning in 1995, coho salmon 

released from IGH have been marked with left maxillary clips; however, return information was 

published for only a single year, 2000. These data indicate that 80% of 1,353 fish returning to 

IGH were marked hatchery fish, with 98% being Iron Gate releases. A few fish from the Trinity 

and Cole rivers (Rogue River, Oregon) hatcheries were also taken. The significance of this high 

percentage of hatchery fish with respect to total production in the Klamath Basin is uncertain 

since IGH lies near the upper end of the accessible habitat. 

Additional information about the composition of Klamath Basin stocks is available from 

tribal harvest and downstream migrant trap data collected by the Yurok Tribal Fisheries Program 

(2002). 

Between 1997 and 2000, tribal harvest of coho salmon ranged from 42 to 135 fish and 

then increased to 895 in 2001. During this 5-year period, hatchery fish constituted between 63% 

and 86% of the total fish harvested. Iron Gate Hatchery fish generally made up a small (8% or 

less) fraction of total hatchery fish captured, the exception being in 1997, when they constituted 

about 37% of the hatchery fish caught. In contrast, Trinity River Hatchery fish accounted for 

87% to 95% of hatchery fish harvested in 1998–2001, and 40% of the hatchery fish captured in 

1997. 

In 1997 and 1998, Yurok Tribal Fisheries operated a downstream migrant trap in the 

lower Klamath River, below the confluence of the Klamath and Trinity rivers; thus the trap 

 

52A. Van Scoyk, Rowdy Creek Hatchery, Smith River, CA. Pers. commun., December 2002. 

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COHO SALMON

Table 76. Average annual releases of coho salmon juveniles (fry and smolts) from selected hatcheries in 

the Southern Oregon/Northern California Coast (SONCC) ESU during release years 1987–1991, 

1992–1996, and 1997–2002. Hatchery classification assigned by the Salmon and Steelhead 

Hatchery Assessment Group (SSHAG 2003) is also shown. 

Average annual releases 

SSHAG 

Hatchery category 1987–1991 1992–1996 1997–2002 

Cochran Ponds (HFAC) 35,391a NAb 0b

Mad Riverc 4 372,863 91,632 82,129d

Prairie Creek 89,009e 0f 0f

Trinity Riverg 2b 496,813 385,369 527,715 

Iron Gate (Klamath)h 2c 147,272 92,150 71,932i

Rowdy Creekj 0 12,534k 10,615l

Cole River (Rogue)m 2a 271,492 239,534n 270,344o

Total 1,412,840 821,219 962,735 

a

 Average from 2 years (1987–1988). Source: Weitkamp et al. 1995. 

b

 Coho salmon were produced by the Humboldt Fish Action Council (HFAC) through the 1994 broodyear; release 

data for 1992 to 1996 are currently unavailable; no fish were released after 1996 (S. Holz, HFAC, Eureka, CA. 

Pers. commun., December 2002. 

c

 Sources: Weitkamp et al. 1995; Gallagher 1993, 1994a, 1994b, 1995; Cartwright 1996, 1997, 1998, 1999, 2000, 

2001. 

d

 CDFG ceased spawning coho salmon at Mad River Hatchery in 1999; yearling were last released in 2001. e

 Average from 4 years (1987–1988, 1990–1991). Source: Weitkamp et al. 1995. f

 Prairie Creek Hatchery ceased producing coho salmon in 1992. g

 Sources: Ramsden 1993, 1994a, 1994b, 1995, 1996, 1997, 1998, 2000, 2001. 

h

 Sources: Hiser 1993, 1994a, 1994b, 1995; Rushton 1996, 1997, 1998, 1999, 2000, 2001. 

i

 Does not include releases from year 2002 (data not available). 

j

 A. Van Scoyk, Rowdy Creek Hatchery, unpublished data from Rowdy Creek Hatchery, 255 N. Fred Haight Dr., 

PO BOX 328, Smith River, CA 95567.

k

 Average from 2 years (1995–1996); data not available for 1992–1995. l

 Rowdy Creek Hatchery ceased releasing coho in year 2001. m Source: Waknitz 2002. 

n

 Average from 1991 to 1995. 

o

 Average from 1996 to 2002; includes juvenile coho salmon released to lakes. 

captured fish from both the Iron Gate and Trinity hatcheries. During 2 years of sampling, Trinity 

hatchery fish dominated the total catch accounting for 73% and 83% of all fish caught in 1997 

and 1998, respectively. Iron Gate Hatchery fish accounted for around 5% of the catch in both 

years. Naturally produced coho salmon made up 22% of the total catch in 1997 and 12% of the 

catch in 1998. In 1998, a second trap was operated on the lower Trinity River. Only 9% of the 

smolts captured at this trap were naturally produced. Assuming that this proportion accurately 

reflected the relative contributions of naturally produced and hatchery Trinity River fish to catch 

at the lower Klamath trap, then the percentages of naturally produced and hatchery fish exiting 

the Klamath River proper (above the Trinity confluence) were approximately 42% and 58%, 

respectively. 

In previous status reviews, the BRT was uncertain whether the use of nonnative stocks to 

start the Iron Gate population was sufficiently important to have lasting effects on the present 

358
28. SOUTHERN OREGON/NORTHERN CALIFORNIA COAST COHO SALMON ESU 

population. Thus, they reached no conclusion about whether the hatchery stock should be 

included in the ESU (NMFS 1997a). Subsequently, Iron Gate was determined to be a category 2 

hatchery (SSHAG 2003). For other SSHAG hatchery stock categorizations, see Appendix C, 

Table C-1. 

Trinity River Hatchery 

Trinity River Hatchery (TRH), located below Lewiston Dam approximately 248 km from 

the ocean, first began releasing coho salmon in 1960. The TRH facility originally used Trinity 

River fish for broodstock, though coho salmon from Eel River (1965), Cascade River (1966, 

1967, and 1969), Alsea River (1970), and Noyo River (1970) have also been reared and released 

at the hatchery as well as elsewhere in the Trinity River basin. 

Trinity River Hatchery produces the largest number of coho salmon of any production 

facility in California. CDFG’s annual production target is 500,000 yearlings. Actual production 

averaged 496,813 from 1987 to 1991, decreased to 385,369 from 1992 to 1996, then increased 

again to 527,715 fish from 1997 to 2002 (Table 76). During the period 1991–2001, an average 

of 3,814 adult coho were trapped and 562 females were spawned at the TRH. 

It is commonly assumed that there is little production of wild coho salmon in the Trinity 

River system, and available data generally support this assumption. Between 1997 and 2002, 

hatchery fish constituted between 89% and 97% of the fish (adults plus grilse) returning to the 

Willow Creek weir in the lower Trinity River (Sinnen 2002). Outmigrant trapping conducted on 

the lower Trinity River indicates that marked TRH fish made up 91%, 97%, and 65% of the 

catch in years 1998, 1999, and 2000, respectively (Yurok Tribal Fisheries Program 2002). 

Additionally, it appears that a significant fraction of the naturally produced fish is likely the 

progeny of hatchery strays. By subtracting the number of hatchery and naturally produced fish 

returning to TRH from counts at Willow Creek weir, Sinnen (2002) estimated that hatchery fish 

made up between 76% and 96% of fish that spawned within the Trinity River system upstream of 

the weir from 1997 to 2002. A potential source of bias in these estimates is that fact that Willow 

Creek weir typically washes out prior to the end of the coho adult migration season. There is 

some suggestion that wild Trinity River coho salmon return later in the season than TRH fish, 

which would result in an overestimate of hatchery contribution to spawning in the wild,53

however, there are no data by which to assess whether such bias exists. Additionally, we are 

aware of no information from which to assess 1) the degree to which TRH fish that pass over the 

weir are straying into various subbasins within the Trinity River (Hoopa Valley Tribe 2003), or 

2) whether hatchery and wild fish have an equal probability of successfully spawning in the wild. 

The BRT concluded that coho salmon from the Trinity River Hatchery should be 

considered part of the SONCC ESU since out-of-basin and out-of-ESU transfers ceased by 1970, 

and production since that time has been exclusively from fish within the basin. The lack of 

natural production within the Trinity Basin, however, remains a significant concern. The Trinity 

Hatchery is a category 2 hatchery (SSHAG 2003). 

 

53G. Kautsky, Hoopa Valley Tribal Fisheries, Hoopa, CA. Pers. commun., April 2003. 

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COHO SALMON

Mad River Hatchery 

Mad River Hatchery (MRH), located approximately 20 km upriver near the town of Blue 

Lake, first began producing coho salmon in 1970. The original broodstock (1970) was from the 

Noyo River, which lies outside of the SONCC ESU, and Noyo fish were released from the 

hatchery during 12 additional years between 1971 and 1996. Other stocks released from the 

hatchery include out-of-ESU transfers from the Trask River (1972), Alsea River (1973), 

Klaskanine River (1973), Green River (1979), and Sandy River (1980), as well as out-of-basin, 

within-ESU transfers from the Trinity River (1971), Klamath River (1981, 1983, 1986–1989), 

and Prairie Creek (1988, 1990). 

Releases of Mad River fish declined substantially during the past decade, from an 

average of 372,8643 fish from 1987 to 1991 to just over 82,000 in the period from 1997 to 2001 

(Table 76). Production of coho salmon at MRH ceased after broodyear 1999, thus 2001 releases 

represent the final year of hatchery production. Adult returns were low during the 1990s, with an 

average of 38 adults trapped and 16 females spawned during the period between 1991 and 1999. 

No information was available regarding the relative contribution of naturally produced and 

artificially propagated fish within the Mad River basin. However, concern about both 

out-of-ESU and out-of-basin stock transfers, as late as 1996, was sufficiently great that the Mad 

River Hatchery was excluded from the SONCC ESU by NMFS (1997). The decision to cease 

producing coho salmon at the Mad River facility rendered this conclusion moot. 

Rowdy Creek Hatchery 

Rowdy Creek Hatchery is a privately owned hatchery in the Smith River basin 

constructed in 1977. Production emphasis has been on Chinook and steelhead, but small 

numbers of coho salmon were trapped and bred during the period 1990 to 1998. Only local coho 

salmon broodstock have been used at the Rowdy Creek facility (NMFS 1997a). 

Annual releases of coho salmon yearlings averaged 12,534 between 1995 and 1996, and 

15,923 from 1997 to 2000, when releases were terminated (Table 76). Adult returns to the 

hatchery averaged just 26 fish in the 11 years that coho salmon were trapped (A. Van Scoyk, 

Rowdy Creek Hatchery, unpublished data). No information was available on the relative 

contribution of Rowdy Creek Hatchery coho salmon to the Smith River population as a whole, 

but it was undoubtedly a minor component during the period of operation. 

In its status review update, the BRT (NMFS 1997a) concluded that the Rowdy Creek 

Hatchery population should be considered part of the ESU, but that it was not essential for ESU 

recovery. The decision to cease producing coho salmon at the facility has rendered this 

conclusion moot. 

Cole Rivers Hatchery 

The Cole Rivers Hatchery has raised Rogue River (Oregon stock #52) coho salmon since 

1973 to mitigate for lost production due to construction of Lost Creek Dam. This stock was 

developed from local salmon trapped in the river, and has no history of out-of-basin fish being 

incorporated. Recent releases (1996–2002) have averaged 270,000 per year, compared to a 

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28. SOUTHERN OREGON/NORTHERN CALIFORNIA COAST COHO SALMON ESU 

1991–1995 average of 240,000 per year (Table 76); the increase is due to inclusion in the data of 

large-sized coho salmon released to lakes in the basin in recent years (Waknitz 2002). Spawning 

of hatchery fish in nature is essentially limited to mainstem tributaries and (to a lesser extent) the 

Applegate River, and interbreeding with natural fish is limited by separation in spawning time 

(Jacobs et al. 2002). The hatchery is rated as a category 1 hatchery (SSHAG 2003). 

Summary 

Artificial propagation of coho salmon within the SONCC has been substantially reduced 

in the past 8 to 10 years, with the exception of Cole Rivers Hatchery on the Rogue River and the 

Trinity River Hatchery. Annual releases from the Cole Rivers and Trinity hatcheries have 

recently averaged 270,000 and 528,000 fish, respectively. Production has ceased at one major 

facility (Mad River), as well as well as several minor facilities (Rowdy Creek, Eel River, and 

Mattole River). Production at Iron Gate Hatchery on the Klamath River has been reduced by 

approximately 50%. Genetic risks associated with out-of-basin and out-of-ESU stock transfers 

have largely been eliminated. However, two significant genetic concerns remain: 1) the potential 

for domestication selection in hatchery populations such as Trinity River, where there is little or 

no infusion of wild genes, and 2) out-of-basin straying by large numbers of hatchery coho 

salmon. 

Harvest impacts 

Historically, ocean harvest of SONCC coho salmon has occurred in coho- and 

Chinook-directed commercial and recreational fisheries off the coasts of California and Oregon. 

Significant changes in harvest management have occurred since the late 1980s, which have 

resulted in substantial reductions in ocean harvest of SONCC coho salmon. In establishing 

fishing seasons and regulations each year, the Pacific Fishery Management Council (PFMC) 

considers the potential impacts on various ESA-listed stocks within the region. Because there 

are no data on exploitation rates on wild SONCC coho salmon, Rogue and Klamath River (RK) 

hatchery stocks are used as a fishery surrogate stock for estimating exploitation rates on SONCC 

coho. The PFMC estimates that most ocean harvest of RK coho salmon (and presumably 

SONCC coho salmon) occurs south of Humbug Mountain, Oregon, which lies near the northern 

boundary of the SONCC ESU. 

During the 1970s and early 1980s, commercial fishing seasons for coho salmon south of 

Humbug Mountain generally lasted from 4 to 5 months or more (PFMC 2003b). These seasons 

were substantially shortened in the late 1980s and early 1990s, particularly between Humbug 

Mountain and Point Arena, California, due to changes in allocation fall-run Chinook salmon to 

tribal and nontribal fall fisheries in the Klamath Management Zone. Retention of coho salmon in 

ocean commercial fisheries south of Cape Falcon, Oregon, has been prohibited since 1993 

(PFMC 2002b). In 1994, retention of coho salmon in ocean recreational fisheries was prohibited 

from Cape Falcon south to Horse Mountain, California, and this prohibition was extended to 

include all California waters in 1995. The retention prohibition has remained in effect south of 

Humbug Mountain since that time. 

Mass-marking (adipose fin clips) of hatchery coho salmon throughout much of the 

Oregon Production Index area led to the implementation of mark-selective recreational fisheries 

361 
COHO SALMON

for hatchery fish along portions of the coast north of Humbug Mountain beginning in 1998 and 

continuing through 2002. Marked fish may be legally retained, while unmarked fish must be 

released unharmed. SONCC-origin coho salmon that migrate north of Cape Blanco experience 

incidental morality due to hooking and handling in this fishery; however, total incidental 

mortality from this fishery and Chinook-directed fisheries north of Humbug Mountain has been 

estimated to be less than 7% of the total mortality of RK hatchery coho salmon since 1999 

(PFMC 1999, 2000, 2001a, 2002c, 2003b). 

In 1999, NMFS issued a biological opinion establishing a consultation standard requiring 

that overall annual ocean exploitation rate not exceed 13% on RK stocks. To conform to this 

standard, the Pacific Fishery Management Council (PFMC) adopted fishing seasons in 

1999–2002 for which the projected coastwide marine exploitation rate on RK stocks ranged 

between 3.0% and 7.7%. During that time, an estimated 93% to 97% of this mortality occurred 

in Chinook-directed fisheries south of Humbug Mountain (PFMC 1999, 2000, 2001a, 2002c, 

2003b). 

Estimates of ocean exploitation rates on SONCC coho salmon for years prior to their 

listing under ESA are not available. Harvest estimates for various landing ports in California are 

available dating back to the early 1950s and indicate that annual harvest in the commercial 

fishery ranged averaged about 163,000 between 1952 and 1991 (PFMC 2003b). Between 1962 

and 1993, recreational harvest in California averaged about 34,000 fish. In both cases, these 

totals represent a mixture of natural- and hatchery-produced fish originating from Oregon and 

California. Neither escapement estimates nor estimates of the contribution of SONCC fish to 

total harvest, from which exploitation rates could be derived, are available. However, there is no 

doubt that ocean exploitation rates have dropped substantially in response to the nonretention 

regulations put in place in 1994 as well as general reductions in Chinook-directed effort. 

Directed river harvest of coho salmon has not been allowed within the SONCC ESU 

since 1994, with the exception of sanctioned tribal harvest for subsistence, ceremonial, and 

commercial purposes by the Yurok, Hoopa Valley, and Karuk tribes (CDFG 2002c). Harvest 

data are only available for the Yurok Tribal Fisheries Program (2002), which reports that annual 

harvest of coho salmon from reservation lands on the lower Klamath River averaged 244 fish 

(67% marked hatchery fish) between 1997 and 2001, though this average is strongly influenced 

by a harvest of almost 900 fish in 2001. In the other 4 years, harvest did not exceed 135 fish. 

Mortality associated with incidental or illegal catch of naturally produced coho salmon in 

SONCC rivers is uncertain, but believed to be low (CDFG 2002c). 

Comparison with Previous Data 

New data for the SONCC coho salmon ESU includes expansion of presence-absence 

analyses; a limited analysis of juvenile abundance in the Eel River basin; a few indices of 

spawner abundance in the Smith, Mad, and Eel river basins; and substantially expanded 

monitoring of adults, juveniles, and habitat in southern Oregon. None of these data contradict 

conclusions the BRT reached previously. Nor do any recent data (1995 to present) suggest any 

marked change, either positive or negative, in the abundance or distribution of coho salmon 

within the SONCC ESU. Coho salmon populations continued to be depressed relative to 

362
28. SOUTHERN OREGON/NORTHERN CALIFORNIA COAST COHO SALMON ESU 

historical numbers, and we have strong indications that breeding groups have been lost from a 

significant percentage of streams within their historical range. Although the 2001 broodyear 

appears to be the one of the strongest perhaps of the last decade, it follows a number of relatively 

weak years. The Rogue River stock is an exception; it had an average increase in spawners over 

the last several years, despite two low years (1998 and 1999). 

Risk factors identified in previous status reviews, including severe declines from 

historical run sizes, the apparent frequency of local extinctions, long-term trends that are clearly 

downward, and degraded freshwater habitat and associated reduction in carrying capacity 

continue to be of concern to the BRT. Termination of hatchery production of coho salmon at the 

Mad River and Rowdy Creek facilities eliminated potential adverse risk associated with hatchery 

releases from these facilities. Likewise, restrictions on recreational and commercial harvest of 

coho salmon since 1994 undoubtedly had a substantial positive impact on coho salmon adult 

returns to SONCC streams. An additional risk factor identified within the SONCC ESU is 

predation resulting from the illegal introduction of nonnative Sacramento pikeminnow 

(Ptychocheilus grandis) to the Eel River basin (NMFS 1998f). Sacramento pikeminnow were 

introduced to the Eel River via Pillsbury Lake in the early 1980s and have subsequently spread to 

most areas within the basin. The rapid expansion of pikeminnow populations is believed to have 

been facilitated by alterations in habitat conditions (particularly increased water temperatures) 

that favor pikeminnow (Brown et al. 1994, NMFS 1998f).

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29. Central California Coast Coho Salmon ESU 

Summary of Previous BRT Conclusions 

The Central California Coast coho salmon ESU extends from Punta Gorda in northern 

California south to and including the San Lorenzo River in central California (Weitkamp et al. 

1995). The status of coho salmon throughout their West Coast range, including the Central 

California Coast coho salmon ESU, was formally assessed in 1995 (Weitkamp et al. 1995). 

NFMS published two subsequent status review updates with information pertaining to the 

Central California Coast coho salmon ESU in 1996 (NMFS 1996b, 1996d). Analyses from those 

reviews regarding extinction risk, risk factors, and hatchery influences are summarized in the 

following sections. 

Status Indicators and Major Risk Factors 

Data on abundance and population trends of coho salmon within the Central California 

Coast coho salmon ESU were limited. Historical time series of spawner abundance for 

individual river systems were unavailable. Brown et al. (1994) presented several historical point 

estimates of coho salmon spawner abundance (excluding ocean catch) for the entire state of 

California for 1940 and for various rivers and regions in the early 1960s and mid-1980s 

(Table 77). Coho salmon were estimated to number between 200,000 and 500,000 statewide in 

the 1940s.54 Coho salmon spawning escapement was estimated to have declined to about 99,400 

fish by the mid-1960s, with approximately 56,100 (56%) originating from streams within the 

Central California Coast coho salmon ESU (Table 77). In the mid-1980s, spawning escapement 

was estimated to have dropped to approximately 30,480 in California and 18,050 (59%) within 

the Central California Coast coho salmon ESU. Employing the “20-fish rule” (see status review 

update for Southern Oregon/Northern California Coast coho salmon ESU for details), Brown 

et al. (1994) estimated wild and naturalized coho salmon populations at 6,160 (47% of the 

statewide total) for the Central California Coast coho salmon ESU during the late 1980s 

(Table 77). All of these estimates are considered to be “best guesses” based on a combination of 

limited catch statistics, hatchery records, and personal observations of local biologists (Brown et 

al. 1994). 

Further information regarding status was obtained from Brown et al.’s (1994) analysis of 

recent (1987–1991) occurrence of coho salmon in streams historically known to support 

populations. Of 133 historical coho salmon streams in the Central California Coast coho salmon 

ESU for which recent data were available, 62 (47%) were determined to still support coho runs 

while 71 (53%) apparently no longer support coho salmon (Table 78). A subsequent analysis of 

 

54E. Gerstung, California Department of Fish and Game, pers. commun., cited in Brown et al. 1994. 

364 
29. CENTRAL CALIFORNIA COAST COHO SALMON ESU 

Table 77. Historical estimates of coho salmon spawner abundance for various rivers and regions within 

the Central California Coast ESU. 

Estimated escapement 

River/region 

CDFG (1965)a

1963 

Wahle & 

Pearson (1987)b

1984–1985 

Brown et al. 

(1994)c

1987–1991 

Ten Mile River 6,000 2,000 160d

Noyo River 6,000 2,000 3,740 

Big River 6,000 2,000 280 

Navarro River 7,000 2,000 300 

Garcia River 2,000 500 

Other Mendocino County 10,000 7,000e 470f

Gualala River 4,000 1,000 200 

Russian River 5,000 1,000 255 

Other Sonoma County 1,000 180 

Marin County 5,000 435 

San Mateo and Santa Cruz counties 4,100 550 140 

 San Mateo County 1,000 

 Santa Cruz County (excluding San Lorenzo 

River) 1,500 50 

 San Lorenzo River 1,600 500 

ESU total 56,100 18,050 6,160 

California statewide totalg 99,400 30,480 13,240 a Values exclude ocean catch. 

b Estimates are for wild or naturalized fish; hatchery returns excluded. 

c Estimates are for wild or naturalized fish; hatchery returns excluded. For streams without recent spawner estimates 

(or estimates lower than 20 fish), assumes 20 spawners. 

d Indicates high probability that natural production is by wild fish rather than naturalized hatchery stocks. e Value may include Marin and Sonoma County fish. 

f Appears to include Garcia River fish. 

g Estimated number of coho salmon for Central California Coast ESU and California portion of the Southern 

Oregon/Northern California Coasts ESU combined. 

surveys from 1995 to 1996 found a somewhat higher percentage (57%) of occupied streams 

(NMFS 1996b).55

Nehlsen et al. (1991) provided no specific information on individual coho salmon 

populations in their 1991 status review, but concluded that salmon stocks in small coastal 

streams north of San Francisco were at moderate risk of extinction and those in coastal streams 

south of San Francisco Bay were at high risk of extinction. A subsequent status review by the 

Humboldt Chapter of the American Fisheries Society (Higgins et al. 1992) found four 

populations (Pudding Creek, Garcia River, Gualala River, and Russian River) to be at high risk 

of extinction and five (Ten Mile, Noyo, Big, Navarro, and Albion rivers) as stocks of concern. 

 

55P. Adams, Southwest Fisheries Science Center, Seattle. Pers. commun. 

365 
Table 78. Historical presence of coho salmon in the Central California Coast ESU, as determined by Brown et al. (1994) a

of recent presence (1995

–2001). Note that methods for estimating occupancy rates differed between Brown et al. (

(2002c); thus, direct comparisons across time periods are inappropriate. Source: Data from CDFG (2002c). 

Brown et al. (1994) 

calendar years 1987

–1990 

CDFG (2002c) 

years 1995

–2001 

Countya/ 

river basin 

No. of 

streams 

No. of streams 

with 

information 

Coho 

present % 

No. of 

streams 

surveyed in 

2001 

No. of streams 

with coho 

present 

No. of streams 

with coho 

assumed present

No. o

with 

detect

Mendocino County 

Coastal 44 35 13 37 30 11 10 Ten Mile River 11 10 7 79 11 9 0 Noyo River 13 12 11 92 8 7 5 Big River 16 13 11 85 8 3 6 Navarro River 19 8 4 50 14 6 1 Subtotal 103 78 46 59 71 36 22 

Sonoma County 

Coastal 10 2 1 50 4 0 0 Gualala River 11 2 1 50 10 0 0 Russian River 32 24 2 8 29 1 1 Subtotal 53 28 4 14 43 1 1 

Marin County 

Coastalb 10 7 7 100 15 6 0 Subtotal 10 7 7 100 15 6 0 

Tributaries to San Francisco Bay 

Coastal 7 7 0 0 0 0 0 Subtotal 7 7 0 0 0 0 0 

South of San Francisco Bay 

Coastal 13 13 5 38 Subtotal 13 13 5 38 

ESU total 186 133 62 47 135 43 23 

a County classifications are based on the location of the mouth of the river system. b CDFG (2002d) included five tributaries of Salmon Creek, a Sonoma County stream that empties into Tomales Bay, in their totals for M

366 
29. CENTRAL CALIFORNIA COAST COHO SALMON ESU 

The BRT identified risk factors that included extremely low contemporary abundance 

compared to historical abundance, widespread local extinctions, clear downward trends in 

abundance, extensive habitat degradation, and associated decreases in carrying capacity. The 

BRT concluded that in the Central California Coast ESU that hatcheries have heavily influenced 

the main stocks of coho salmon and that relatively few native coho salmon were left (Weitkamp 

et al. 1995). Most existing stocks have a history of hatchery planting, with many out-of-ESU 

stock transfers. A subsequent status review (NMFS 1996a), which focused on existing 

hatcheries, concluded that, despite the historical introduction of nonnative fish, the Scott Creek 

(Kingfisher Flat) and Noyo River broodstocks have regularly incorporated wild broodstock, and 

thus were unlikely to differ from naturally spawning fish within the ESU. Recent droughts and 

unfavorable ocean conditions were identified as natural factors contributing to reduced run size. 

Previous BRT Conclusions 

Based on the data presented above, the BRT concluded that all coho salmon stocks in the 

Central California Coast coho salmon ESU are depressed relative to historical abundance, and 

that most extant populations have been heavily influenced by hatchery operations. They 

unanimously concluded that natural populations of coho salmon in this ESU are in danger of 

extinction (Weitkamp et al. 1995). After considering new information on coho salmon presence 

within the ESU, the majority of the BRT concluded that the ESU is in danger of extinction, while 

a minority concluded the ESU is not presently in danger of extinction but is likely to become so 

in the foreseeable future (NMFS 1996b). 

 Listing status: Threatened. 

New Data and Updated Analyses 

Significant new information on recent abundance and distribution of coho salmon within 

the Central California Coast ESU has become available, much of which was summarized in two 

recent status reviews (NMFS 2001b; CDFG 2002c). Most of these data are of two types: 

1) compilations of presence-absence information for coho salmon throughout the Central 

California Coast coho salmon ESU from 1987 to the present, and 2) new data on densities of 

juvenile coho salmon collected at a number of index reaches surveyed by private timber 

companies, the CDFG, and other researchers. Except for adult counts made at the Noyo Egg 

Collecting Station, which are both incomplete and strongly influenced by hatchery returns, there 

are no current time series of adult abundance within this ESU that span 8 years or more. 

Outmigrating smolts have been trapped at two trapping facilities in Caspar Creek and Little 

River since the mid-1980s; however, these are partial counts and only recently have markrecapture studies been performed that allow correction for capture efficiency at these two sites. 

Thus, these smolt counts can only be considered indices of abundance. 

Two analyses of presence-absence data were recently published. CDFG (2002c) focused 

on recent (1995–2001) presence of coho salmon in streams identified as historical producers of 

coho salmon by Brown and Moyle (1991). NMFS (2001b) published an updated status review of 

coho salmon presence in streams throughout the Central California Coast coho salmon ESU from 

1989 to 2000. Scientists at the NMFS Southwest Fisheries Science Center continued to compile 

367 
COHO SALMON

data on coho salmon presence-absence, which were incorporated into a database summarized by 

broodyear (rather than year of sampling) and covers broodyears 1986–2001. Data from CDFG’s 

2001 field survey of the Brown and Moyle (1991) streams were incorporated into this database. 

Analyses in this status review update supercede those in NMFS (2001b). 

CDFG Presence-Absence Analysis 

Methods 

Methods used by CDFG (2002c) to analyze presence-absence information in the Central 

California Coast coho salmon ESU differed from those used for the SONCC analysis. Analysis 

focused on results from CDFG’s 2001 summer juvenile sampling effort, in which 135 of 173 

streams identified by Brown and Moyle (1991) as historical coho salmon streams within the 

Central California Coast coho salmon ESU were sampled. Additionally, CDFG assumed coho 

salmon were present in any stream where their presence was detected during any 3 consecutive 

years during the period 1995–2001. An estimate of percent coho salmon presence was 

calculated by totaling the number of streams for which presence was either observed or assumed, 

and dividing by the total number of streams surveyed, including those where presence was 

assumed. No formal statistical analysis of trends was performed because of the lack of 

comparable data from previous time periods. 

Results 

For the Central California Coast coho salmon ESU as a whole, CDFG (2002c) estimated 

that coho salmon were present in 42% of streams historically known to contain coho salmon. 

Estimated occupancy was highest in Mendocino County (62%), followed by Marin County 

(40%), Sonoma County (4%), and San Francisco Bay tributaries (0%) (Table 78). Because of 

differences in the specific streams considered and methods for estimating occupancy rates, these 

numbers are not directly comparable with those derived by Brown et al. (1994). Nevertheless, 

the regional and overall ESU patterns are generally concordant for the two studies, indicating 

substantial variation in occupancy rates across the ESU, with lower occupancy rates in the 

southern portion of the ESU (Table 78). 

NMFS Presence-Absence Analysis 

Methods 

Scientists at NMFS’s Southwest Fisheries Science Center compiled survey information 

from streams with historical or recent evidence of coho salmon presence within the Central 

California Coast coho salmon ESU. Data were provided primarily by the CDFG, private 

landowners, consultants, academic researchers, and others who conducted sampling within the 

Central California Coast coho salmon ESU from 1988 to 2002. The majority of data came from 

summer juvenile surveys, though information from downstream migrant trapping and adult 

spawner surveys was also included. Observations of presence or absence for a particular stream 

were assigned to the appropriate broodyear based on life stages observed (or expected, in the 

case of absences). The resulting data set spans broodyears 1987 to 2001, though data from the 

368 
29. CENTRAL CALIFORNIA COAST COHO SALMON ESU 

2002 summer field season (broodyear 2001) were not fully reported when the analysis was 

performed. 

Results for NMFS’s presence-absence analysis are presented by major watersheds or 

aggregations of adjacent watersheds. Results from larger watersheds are typically presented 

independently, whereas data from contiguous smaller coastal streams, where data were relatively 

sparse, are grouped together. In a few cases, individual smaller coastal streams with only a few 

observations were aggregated with adjacent larger streams if there was no logical geographic 

grouping of smaller streams. 

Results 

The estimated percentage of streams in which coho salmon were detected shows a 

general downward trend from 1987 to 2000, followed by a substantial increase in 2001 (Figure 

207). Several caveats, however, warrant discussion. First, the number of streams surveyed per 

year also shows a general increase from 1987 to 2000; thus, there may be a confounding 

influence of sampling size if sites surveyed in the first half of the time period are skewed 

disproportionately toward observations in streams where presence was more likely. Second, 

sample size from broodyear 2001 was relatively small and the data were weighted heavily 

toward certain geographic areas (Mendocino County and systems south of the Russian River). 

The data for broodyear 2001 included almost no observations from watersheds from the Navarro 

River to the Russian River, or tributaries to San Francisco Bay, areas where coho salmon have 

been scarce or absent in recent years. Thus, although 2001 appears to have been a relatively 

strong year for coho salmon in the Central California Coast ESU as a whole, the high percentage 

of streams where presence was detected that is shown in Figure 207 is likely inflated. 

Two other patterns were noteworthy. First, compared with percent presence values for 

the SONCC ESU, values in the Central California Coast coho salmon ESU were more highly 

variable and showed a somewhat more cyclical pattern. In general, percent occupancy was 

relatively low in broodyears 1990, 1993, 1996, and 1999, suggesting that this brood lineage is in 

the poorest condition. In contrast, during the 1990s, percent occupancy tended to be high in 

broodyears 1992, 1995, 1998, and 2001, suggesting that this is the strongest brood lineage of the 

three. Second, there is a general tendency for percent occupancy to be slightly higher (2–15%) 

for the Brown and Moyle streams compared with the ESU as a whole. We speculate that this 

pattern may reflect the fact that increased concern over Central California Coast coho salmon in 

the mid-1990s prompted increased stream sampling, including streams other than those 

traditionally known to support coho salmon. Lower occupancy rates at these sites might be 

expected if they represent habitats that are generally less suitable for coho salmon. 

When data are aggregated over brood cycles (3-year periods), the percentage of streams 

with coho salmon detected shows a similar downward trend, from 72% in 1987–1989, to 62% in 

1990–1992, to less than 55% in the last three brood cycles (Table 79). Again there are 

confounding influences of increased sampling fraction through time and incomplete reporting for 

369 
COHO SALMON

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Proportion of streams with coho present

1986 1988 1990 1992 1994 1996 1998 2000 2002

Broodyear

26

36

34

47

74

125 172

202

119

80 79

170 226

65

19

18

26

23

34

54

81 115

127

86

53

51

96 150

All streams Brown & Moyle streams only 37

Figure 207. Proportion of streams surveyed in which coho salmon presence was detected, by broodyear, 

for all historical coho streams and coho streams identified in Brown and Moyle’s (1991) 

historical list within the Central California Coast coho salmon ESU. Sample sizes (i.e., number 

of streams surveyed) are shown next to data points. Source: Data are from combined NMFS and 

CDFG data sets. 

the 2001 broodyear. Nevertheless, it appears that the percent of historical streams occupied 

continued to decline from the late 1980s to the mid-1990s and remains below 50% for the ESU 

as a whole. Additionally, coho salmon appear to be extinct or nearing extinction in several 

geographic areas including the Garcia River, the Gualala River, the Russian River, and San 

Francisco Bay tributaries. There is also evidence that some populations that still persist in the 

southern portion of the range, including Waddell and Gazos creeks, have lost one or more brood 

lineages (Smith 2001a). 

Results from our presence-absence analysis are generally concordant with CDFG’s 

analysis. The two studies show consistent regional patterns suggesting that within the Central 

California Coast coho salmon ESU the proportion of streams occupied is highest in Mendocino 

County, but that populations in streams in the southern portion of the range (excluding portions 

of Marin County) have suffered substantial reductions in range. NMFS analysis is more 

suggestive of a continued decline in percent occupancy from the late 1980s to the present; 

however, increased sampling in recent years may be confounding any trends. 

370 
Table 79. Percent of surveyed streams within the Central California Coast ESU in which coho salmon were detected for fo

broodyears 1987

–1989, 1990

–1992, 1993

–1995, 1996

–1998, and 1999

–2001. Streams include those for which hi

evidence of coho salmon presence exists (based on combined NMFS and CDFG data). 

1987–1989 1990–1992 1993–1995 1996–1998 

County and river basins 

No. of 

streams 

with 

historical 

presence

No. 

surveyeda

% Coho 

presentb

% Coho 

absentc

No. 

surveyeda

% Coho 

presentb

% Coho 

absentc

No. 

surveyeda

% Coho 

presentb

% Coho 

absentc

No. 

surveyeda

% Coho 

presentb

% Coho 

Mendocino 

Coastal (Punta Gorda to Abolabodiah Creek) 24 4 75 25 6 50 50 16 50 50 11 18 Ten Mile River 25 6 50 50 15 53 47 17 65 35 14 57 Pudding Creek to Noyo River 43 4 75 25 8 88 12 35 66 34 15 80 Coastal (Hare Creek to Russian Gulch) 14 8 100 0 4 100 0 9 67 33 9 67 Big and Little rivers 28 5 20 80 7 57 43 20 75 25 16 81 Albion River 16 3 100 0 3 100 0 15 80 20 1 100 Little Salmon and Big Salmon creek 

er

6 0 – – 3 100 0 4 75 25 4 75 

Navarro Riv 3 0 1 00 0 1 0

8 3 00 0 2 0

er 5 1 00 0 1 0

1 100 24 58 42 6 67 

Coastal (Greenwood Creek to Brush Creek) 

ek

8 3 0 100 2 50 50 8 13 87 0 – 

Garcia River to Digger Cre 1 100 8 13 87 5 20 

Sonoma 

Gualala Riv 1 1 100 11 0 100 1 0 Fort Ross to Russian River 55 5 40 60 14 50 50 37 54 46 29 24 

Marin 

Tomales Bay rivers 25 3 100 0 4 100 0 14 36 64 10 90 Coastal (Redwood Creek to Bolinas Lagoon) 6 0 – – 1 100 0 2 50 50 4 75 

San Francisco Bay 

San Francisco Bay River 6 0 – – 4 100 6 0 100 4 0 

San Mateo/Santa Cruz 

Coastal (San Francisco Bay to Aptos Creek) 17 7 100 0 7 100 0 13 69 31 14 57 

Monterey 

Coastal (Carmel River to Big Sur River) 2 0 – – 0 – – 2 0 100 0 – 

ESU Total 328 53 72 28 82 63 37 241 54 46 143 54 

a Total number of steams surveyed at least once within the 3-year interval. b Percentage of surveyed streams in which coho were present in one or more years during the interval.c Percentage of surveyed streams in which coho were absent in all years of survey during the interval. 

371 
COHO SALMON

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

1962 1965 1968 1971 1974 1977 1980 1983 1986 1989 1992 1995 1998 2001

Year

Adult counts

Adult males + females All returning fish

Figure 208. Counts of adult coho salmon at Noyo Egg Collecting Station, 1962–001. Solid line with 

closed symbol indicates total fish captured (including grilse); dashed line with open symbols 

indicates adult males and females only. Counts are partial counts and thus are only a crude index 

of adult abundance. Source: Grass (2002). 

Adult Time Series 

No time series of adult abundance free of hatchery influence and spanning 8 or more 

years are available for the Central California Coast coho salmon ESU. Adult counts from the 

Noyo Egg Collecting Station (ECS) dating back to 1962 represent a mixture of naturally 

produced and hatchery fish, and counts are incomplete most years because trap operation was 

sporadic during the season and typically ceased after broodstock needs were met. Thus, at best 

they represent an index of abundance. Assuming that these counts reflect general population 

trends, there appears to have been a significant decline in abundance of coho salmon in the South 

Fork Noyo River beginning in 1977 (Figure 208). No formal analysis of trends was conducted 

because of the uncertainty of the relationship between catch statistics and population size, as well 

as the relative contribution of hatchery fish to total numbers during the entire period of record. 

Smolt Time Series 

CDFG personnel have trapped outmigrating smolts at Caspar Creek and Little River since 

1986. These counts are partial counts, uncorrected for capture efficiency. As such, they provide 

only indices of abundance. However, they likely capture gross changes in smolt abundance over 

the years (Figure 209). For Caspar Creek, the highest smolt counts occurred in the late 1980s 

and early 1990s, decreased in the mid-1990s, then increased in the past 3 years to levels 

372 
29. CENTRAL CALIFORNIA COAST COHO SALMON ESU 

0

500

1000

1500

2000

2500

1986 1988 1990 1992 1994 1996 1998 2000 2002 2004

Year

0

500

1000

1500

2000

2500

1986 1988 1990 1992 1994 1996 1998 2000 2002 2004

Smolt count

1987 +3 brood lineage

1988 +3 brood lineage

1989 +3 brood lineage

0

500

1000

1500

2000

2500

1986 1988 1990 1992 1994 1996 1998 2000 2002 2004

Smolt count

1987 +3 brood lineage

1988 +3 brood lineage

1989 +3 brood lineage

Smolt count

Figure 209. Coho salmon smolt counts (1987–2002) at (top) Little River and (bottom) Caspar Creek, 

Mendocino County. Lines track brood lineages. Data are counts of smolts uncorrected for trap 

efficiency and thus should be viewed as coarse indices of abundance. Source: Harris (2002b). 

approaching those of the late 1980s (Figure 209). For Little River, a similar pattern was 

observed from the late 1980s to the mid-1990s; however, only a slight increase in numbers was 

observed in the last 3 years of records. Smolt counts were higher in each year from 1986 to 1989 

than in any year since (Figure 209). When individual brood lineages are tracked, Little River 

shows a decline in all three brood lineages over the period of record. In contrast, Caspar Creek 

shows a decline in the 1987 brood lineage, relatively consistent numbers in the 1988 brood 

lineage, and a decrease in the early to mid-1990s followed by an increase over the last two brood 

cycles to levels comparable to those observed in 1989 (Figure 209). For both locations, the 

estimated long-term trend is negative but not significantly different from 0 (Table 80). Likewise, 

λ values are not significantly different from 1. 

373 
COHO SALMON

Table 80. Population trend analysis for Caspar Creek and Little River smolt outmigrant data. Trends are 

based on smolt counts uncorrected for trap efficiency (see text). Source: Harris (2002b). 

Geometric meansa

Stream 

Recent 

3-year mean 

3-year 

minimum 

3-year 

maximum λb

Long-term 

trend

b

Caspar Creek 1,278 

(829–1,871) 

723 

(530-953) 

1,383 

(1,182–2,121) 

1.002 

(0.851, 1.178) 

–0.017 

(–0.081, 0.048) 

Little River 504 

(198–946) 

94 

(4–640) 

1,750 

(1,111–2,161) 

0.919 

(0.669, 1.347) 

–0.063 

(–0.358, 0.232) a Values in parentheses for geometric means are the range of values observed over the 3-year period. 

b Values in parentheses for λ and trends are lower and upper bounds for 95% confidence limits. 

Juvenile Time Series 

Methods 

Although recent estimates of adult and smolt abundance are scarce for the Central 

California Coast coho salmon ESU, estimates (or indices) of juvenile density during summer 

were made at more than 50 index sites in the past 8 to 18 years. Methods for analyzing these 

data are described in detail in Section 28. Briefly, data from individual sampling sites were 

natural log-transformed and normalized to prevent spurious trends arising from different data 

collection methods or reporting units. Data were then grouped into units thought to represent 

plausible independent populations based on watershed structure. Trends were then estimated for 

putative populations by estimating the slope (and associated 95% confidence intervals) for the 

aggregated data. Analysis was restricted to 1) sites where a minimum of 6 years of data were 

available, and 2) putative populations where more than 65% of all observations were nonzero 

values. 

Nine geographic areas (putative populations) were represented in the aggregated data, 

including Pudding Creek, Noyo River, Caspar Creek, Big River, Little River, Big Salmon Creek, 

Lagunitas Creek, Redwood Creek, and coastal streams south of San Francisco Bay, including 

Waddell, Scott, and Gazos creeks. Spatially, these sites cover much of the Central California 

Coast coho salmon ESU; however, several key watersheds are not represented, including the Ten 

Mile, Navarro, Garcia, Gualala, and Russian rivers. Although considerable sampling has been 

done in the Ten Mile River basin, the high proportion of zero values precluded analysis of these 

data. 

Results 

Overall, analysis of juvenile data provided little evidence of either positive or negative 

trends for the putative populations examined. Estimated slopes were negative for six populations 

and positive for three; however, none of the estimated slopes differed significantly from zero 

(Table 81). 

374 
29. CENTRAL CALIFORNIA COAST COHO SALMON ESU 

Table 81. Trend slopes and confidence intervals for nine putative coho populations in the Central 

California Coast coho salmon ESU. 

95% confidence interval 

Watershed 

No. 

sites 

Aggregate 

slope Lower bound Upper bound 

Pudding Creek 1 –0.019 –0.103 0.065 

Noyo River 8 –0.091 –0.195 0.013 

Caspar Creek 2 –0.039 –0.109 0.030 

Little River 2 –0.044 –0.118 0.029 

Big River 2 0.146 –0.001 0.293 

Big Salmon Creek 5 –0.005 –0.110 0.100 

Lagunitas Creek 3 0.095 –0.123 0.312 

Redwood Creek 1 0.091 –0.345 0.527 

Waddell/Scott/Gazos creeks 3 –0.111 –0.239 0.018 

New Comments 

Homer T. McCrary, vice president of Big Creek Lumber, submitted 375 pages primarily 

composed of excerpts from historical documents related to operation of hatcheries in Santa Cruz 

County from the early 1900s to 1990 (McCrary 2002). The expressed intent of this compilation 

was “to assist the efforts of resource professionals, scientists, regulators, fisheries restoration 

advocates and all interested parties in establishing a more complete historical perspective on 

salmonid populations.” Quantitative information regarding hatchery and stocking histories is 

discussed in Section 25, subsection, Harvest Impact. 

New Hatchery Information 

The BRT (Weitkamp et al. 1995) identified four production facilities that had recently 

produced for release in the Central California Coast coho salmon ESU: the Noyo Egg Collecting 

Station (reared at Mad River Hatchery) and Don Clausen (Warm Springs) hatchery, both 

operated by CDFG; Big Creek Hatchery (Kingfisher Flat Hatchery), operated by the Monterey 

Bay Salmon and Trout Program; and the Silver-King ocean ranching operation. The latter 

facility closed in the late 1980s. 

Noyo Egg Collecting Station 

The Noyo Egg Collecting Station (ECS), located on the South Fork Noyo River 

approximately 17 km inland of Fort Bragg, began operating in 1961 and has collected coho 

salmon in all but a few years since that time. Fish have historically been reared at the Mad River 

Hatchery, Don Clausen (Warm Springs) Hatchery, and the Silverado Fish Transfer Station. 

There are no records of broodstock from other locations being propagated with Noyo fish for 

release back into the Noyo River system, but a few out-of-ESU transfers directly into the Noyo 

River system have been recorded, including Alsea and Klaskanine, Oregon, stocks (SSHAG 

2003). 

375 
COHO SALMON

Average annual release of coho salmon yearlings was 108,000 from 1987 to 1991 

(Weitkamp et al. 1995), declined to about 52,000 between 1992 and 1996, then increased again 

to about 72,000 fish between 1997 and 2002, inclusive of 2 years during which no yearlings were 

released (Table 82). Releases were made exclusively to the ECS or elsewhere in the South Fork 

Noyo River drainage in the past decade. Between 1991 and 2001, adult returns averaged 572 

individuals, though these represent incomplete counts in most years, as counting typically ceased 

after broodstock needs were met (Grass 2002). On average, 91 females were spawned annually 

during this 11-year period (Grass 1992, 1993, 1995a, 1995b, 1996, 1997, 1998, 1999, 2000, 

2001, 2002). 

There are no basinwide estimates of natural and artificial production for the Noyo River 

basin as a whole; however, marking of coho salmon juveniles released from the Noyo ECS on 

the South Fork Noyo River began in 1997, and returns have been monitored since the 1998–1999 

spawning season. In the 1998, 1999, and 2000 broodyears, marked hatchery fish constituted 

85%, 70%, and 80%, respectively, of returning adults captured at the ECS. 

The BRT (NMFS 1996a) concluded that, although exotic stocks have occasionally been 

introduced into the Noyo system, the regular incorporation of local natural fish into the hatchery 

population made the likelihood that this population differs substantially from naturally spawning 

fish in the ESU low; therefore, the BRT included them in the ESU. Because Central California 

Coast coho salmon were listed, no significant changes in hatchery practices have occurred. The 

Noyo ECS operation has been classified as a category 1 hatchery (SSHAG 2003). 

Don Clausen (Warm Springs) Hatchery 

The Don Clausen Hatchery (also known as Warm Springs stock), located on Dry Creek 

in the Russian River system 72 km upstream of the mouth, began operating in 1980. Initial 

broodstock used were from the Noyo River system, and Noyo fish were planted heavily from 

1981 to 1996. 

Average annual releases of coho salmon from the hatchery decreased from just over 

123,000 in the 1987–1991 period to about 57,000 in the years between 1992 and 1996, and Noyo 

River broodstock continued to constitute about 30% of the releases during the latter period. 

Production of coho salmon at the facility ceased entirely after 1996 (Table 82). Adult returns 

averaged 245 fish between 1991 and 1996, but following the cessation of releases, no more than 

four coho salmon have been trapped at the hatchery in any subsequent year. 

Because the Warm Springs population was originally derived from Noyo River stock and 

continued to receive transfers from the Noyo system throughout its operation, the BRT 

concluded that the hatchery population was not a part of the ESU. 

Beginning in 2001, however, a captive broodstock program was initiated at the Don 

Clausen facility. A total of 337 juveniles were electro-fished from Green Valley and Mark West 

Springs creeks, two Russian River tributaries that still appear to support coho salmon, as well as 

Olema Creek, a tributary to Lagunitas Creek. Specific mating protocols for these fish have not 

yet been determined. The captive broodstock program proposes to eventually release 50,000 

fingerlings and 50,000 yearlings into five Russian River tributaries. Under the captive 

376 
29. CENTRAL CALIFORNIA COAST COHO SALMON ESU 

broodstock program, the Don Clausen Hatchery has been classified as a category 1 hatchery 

(SSHAG 2003). 

Kingfisher Flat (Big Creek) Hatchery 

The Monterey Bay Salmon and Trout Project (MBSTP) has operated Kingfisher Flat 

Hatchery, located on Big Creek, a tributary to Scott Creek, since 1976. The facility is near the 

site of the former Big Creek Hatchery, which was operated from 1927 to 1942, when a flood 

destroyed the facility. An additional facility in Santa Cruz County, the Brookdale Hatchery on 

the San Lorenzo River, operated from 1905 to 1953. Both the Big Creek and Brookdale 

hatcheries were supplied with eggs taken at an egg-collection facility located on Scott Creek; 

additional eggs were provided from other hatcheries around the state. Production of coho 

salmon at both hatcheries was sporadic. There is evidence that coho salmon eggs from Baker 

Hatchery (Birdsview Station) in Washington State were transferred to Brookdale Hatchery in 

1906–1910. Although records documenting where these fish were distributed are unavailable, it 

is possible that some were released into Scott Creek. In subsequent years, releases from both 

facilities back into Scott Creek included both Scott Creek fish (1913, 1915, 1929, 1930, 1934, 

and 1936–1939), as well as fish from Fort Seward, Mendocino County (1932), and Prairie Creek, 

Humboldt County (1933, 1935, and 1939). Throughout these years, only fry were (generally 

during July through September) and numbers of fish were relatively small. In the 10 years 

between 1929 and 1939, during which coho salmon were planted in Scott Creek, the total fry 

release averaged about 34,000 fish. During the Silver-King operation, broodstock was obtained 

from Oregon, Washington, British Columbia, and Alaska.

Since 1976, when MBSTP began operating the Kingfisher Flat Hatchery, only local 

broodstock have been released back into Scott Creek. Some Noyo, Prairie Creek, and San 

Lorenzo coho salmon were reared at the hatchery in the early 1990s, but were released into the 

San Lorenzo River rather than Scott Creek. Mating protocols at the hatchery follow a priority 

scheme in which wild × wild broodstock are used in years of relatively high abundance, wild ×

hatchery crosses are done when wild fish are less available, and hatchery × hatchery crosses are 

made when wild fish are unavailable.56 Under the current management plan, up to 30 females 

and 45 males can be taken with the restriction that the first 10 spawning pairs observed must be 

allowed to spawn undisturbed in their natural habitat, and then only 1 in 4 females may be taken 

to spawn. In recent years, few or no fish have been taken, due to low abundance; however, in 

2001, 123 coho were observed and 26 “wild” females were taken for spawning. Of the 123 coho 

observed, 40% were marked hatchery fish. No other data are available to assess the relative 

contribution of hatchery versus naturally produced coho salmon. 

In its 1996 coho status review update, the BRT concluded that the Kingfisher Flat (Scott 

Creek) hatchery population should be considered part of the ESU and was essential for ESU 

recovery (NMFS 1996a). This conclusion was based on the fact that local broodstock was 

regularly incorporated into the hatchery population in the years that coho were produced between 

1905 and 1943, and there have been no out-of-basin or out-of-ESU transfers since the hatchery 

was restarted in 1976. The MBSTP operation is classified as a category 1 hatchery (SSHAG 

2003). For other SSHAG categorizations of hatchery stocks, see Appendix C, Table C-1. 

 

56D. Streig, MBSTP, Davenport, CA. Pers. commun. 

377 
COHO SALMON

Table 82. Average annual releases of coho salmon juveniles (fry and smolts) from hatcheries in the 

Central California Coast ESU during release years 1987–1991, 1992–1996, and 1997–2003. 

SSHAG Annual average releases 

category Hatchery 1987–1991 1992–1996 1997–2002 

Monterey Bay Salmon and Trout 1 25,764a 8,645b 1,901b

Silver-King 95,074c 0d 0d

Noyo Egg Collecting Station 1 107,918 a 52,012e 72,363e

Don Clausen (Warm Springs) Hatchery 1 123,157 a 81,666f 

12,104f

Total 351,913 142,323 86,368 

a

 Source: Weitkamp et al. (1995). 

b

 No coho salmon released in 1991, 1994, 1997, and 2000; all releases are smolts except for 10,095 fry released in 

1996; smolts from San Lorenzo River, Noyo River, and Prairie Creek reared at Big Creek and released into San 

Lorenzo River are excluded from totals. Sources: MBSTP (1992, 1993, 1994, 1995, 1996); Anderson (1996); 

Ayers (2004). c

 Average from 4 years of data (1984–1988). Source: Weitkamp et al. (1995). 

d

 Ceased operating in the 1980s. 

e

 No yearling coho were released in 1995, 2000, or 2001. Sources: Grass (1992, 1993, 1995a, 1995b, 1996, 1997, 

1998, 1999, 2000, 2001, 2002). f Releases included both Warm Springs Hatchery and Noyo River ECS fish. Warm Springs Hatchery ceased 

releasing coho salmon in 1996. Sources: Cartwright (1994); Williams (1993); Quinones (1994, 1995, 1996, 1997, 

1998, 1999); CDFG (2000c); Wilson (2001, 2002). 

A captive broodstock program for Scott Creek was initiated at the NMFS Santa Cruz 

Laboratory in 2003. 

Summary 

Artificial Propagation 

Artificial propagation of coho salmon within the Central California Coast coho salmon 

ESU has been reduced since it was listed in 1996 (Table 82). The Don Clausen Hatchery ceased 

production of coho salmon, and releases from the Noyo ECS operation declined over the past 6 

years, in part because coho were not produced during 2 of those 6 years. The Monterey Bay 

Salmon and Trout Program produced few coho salmon for release in the last 6 years due to low 

adult returns to Scott Creek. Genetic risks associated with out-of-basin transfers appear minimal. 

However, potential genetic modification in hatchery stocks resulting from domestication 

selection or low effective population size remains a concern. 

Harvest Impacts 

Harvest of Central California Coast–origin coho salmon historically occurred in cohoand Chinook-directed commercial and recreational fisheries off the coast of California. Coho 

landing information for various ports in California is available dating back to the 1950s for 

commercial harvest and the early 1960s for recreational harvest; however, there are no historical 

estimates of either harvest or exploitation rates specific to Central California Coast coho salmon. 

378 
29. CENTRAL CALIFORNIA COAST COHO SALMON ESU 

Likewise, no direct information is available about the ocean distribution of coho salmon; 

however, it is likely that most Central California Coast–origin coho salmon remain in waters off 

California and southern Oregon. Thus, harvest management within this region is most relevant 

for evaluating harvest impacts. 

57

Through the mid-1980s, the season for directed commercial harvest of coho salmon 

typically lasted 3 to almost 5 months throughout California. In the late 1980s and early 1990s, 

the commercial salmon seasons throughout California were generally shorter, particular in the 

region south of Point Delgada. By 1992, the commercial coho salmon season was closed 

completely from the Oregon border south to Horse Mountain, California, and open only 7 days 

from Point Arena to San Pedro. Retention of coho salmon by commercial fishers south of Cape 

Falcon, Oregon, including all of California, has been prohibited since 1993 (PFMC 2002b). 

Likewise, retention of coho salmon in recreational fisheries was prohibited in 1994 from Cape 

Falcon, Oregon, south to Horse Mountain, California. This prohibition was extended to include 

all California waters in 1996 (PFMC 2003b). Nonretention regulations in both commercial and 

recreational fisheries remain in place throughout coastal California and southern Oregon, but 

selective fishing for marked hatchery coho salmon has been allowed north of Humbug Mountain, 

Oregon, since 1999, and some incidental mortality of Central California Coast coho salmon may 

occur in this fishery. Additionally, coho salmon are also incidentally caught or hooked in 

Chinook salmon fisheries off California. 

Although no estimates of incidental mortality associated with Chinook salmon fisheries 

are available (PFMC 2003b), nonretention regulations undoubtedly have resulted in a substantial 

reduction in harvest-related mortality since 1993. The PFMC (2003b) estimates that statewide 

commercial harvest of coho salmon averaged about 163,000 fish between 1952 and 1991; since 

1992 there have been no known landings of coho salmon. Ocean recreational harvest of coho 

salmon averaged about 34,000 fish from 1962 to 1993. Total estimated incidental and illegal 

harvest of coho salmon has not exceeded 1,000 fish in any year since nonretention regulations 

were put in place. 

There is no legal inside harvest of coho salmon within the Central California Coast coho 

salmon ESU; any fishery mortality results from incidental catch-and-release hooking mortality in 

other fisheries. There are no estimates of inside harvest or mortality of coho salmon in the 

Central California Coast coho salmon ESU (PFMC 2003b); however, CDFG (2003b) considers 

the potential for significant incidental mortality (and poaching) to be low because of the minimal 

overlap between the coho migration season and the steelhead season (CDFG 2003b). 

Comparison with Previous Data 

New data for the Central California Coast coho salmon ESU includes expansion of 

presence-absence analyses, an analysis of juvenile abundance in 13 river basins, smolt counts 

from two streams in the central portion of the ESU, and one adult time series for a population 

with mixed wild and hatchery fish. The presence-absence analysis suggests possible continued 

 

57Rogue/Klamath hatchery stocks, which serve as fishery surrogate stocks for SONCC coho salmon, are generally 

distributed south of Humbug Mountain, Oregon. It is likely that Central California Coast coho salmon exhibit a 

more southerly ocean distribution. 

379 
COHO SALMON

decline of coho salmon between the late 1980s and the late 1990s, a pattern that is mirrored in 

the limited smolt and adult counts. Juvenile time series suggest no obvious recent change in 

status, but most observations underlying that analysis were made in the period from 1993 to 

2002. Coho salmon populations continue to be depressed relative to historical numbers, and 

strong indications show that breeding groups have been lost from a significant percentage of 

streams within their historical range. A number of coho populations in the southern portion of 

the range appear to be either extinct or nearly so, including those in the Gualala, Garcia, and 

Russian rivers, as well as smaller coastal streams in and south of San Francisco Bay. Although 

the 2001 broodyear appeared to be relatively strong, data were not yet available from many of 

the most at-risk populations within the Central California Coast coho salmon. 

No new information has been provided that suggests additional risks beyond those 

identified in previous status reviews. Termination of hatchery production at the Don Clausen 

(Warm Springs) Hatchery and reductions in production at the Noyo and Kingfisher Flat (Big 

Creek) facilities suggest a decrease in potential risks associated with hatcheries; however, the 

lack of substantive information regarding the relative contribution of hatchery and naturally 

produced fish at these facilities adds uncertainty as to the potential risks these operations may 

pose to the genetic integrity of the Noyo River and Scott Creek stocks. Restrictions on 

recreational and commercial harvest of coho salmon since 1993–1994 have substantially reduced 

the exploitation rate on Central California Coast coho salmon. 

380 
30. Lower Columbia River 

Coho Salmon ESU 

Summary of Previous BRT Conclusions 

NMFS reviewed the status of the Lower Columbia River coho salmon ESU in 1996 

(NMFS 1996b) and most recently in 2001 (NMFS 2001a). In the 2001 review, the BRT was 

very concerned that the vast majority (over 90%) of historical populations in the Lower 

Columbia River coho salmon ESU appear to be either extirpated or nearly so. The two 

populations with any significant production (Sandy and Clackamas rivers) were at appreciable 

risk because of low abundance, declining trends, and failure to respond after a dramatic reduction 

in harvest. The large number of hatchery coho salmon in the ESU was also considered an 

important risk factor. The majority of the 2001 BRT votes were for “at risk of extinction” with a 

substantial minority “likely to become endangered.” 

Listing status: Proposed Threatened. 

New Data and Updated Analyses 

New data include spawner abundance estimates through 2002 for Clackamas and Sandy 

river populations (the previous status review had data through 1999 only). In addition, the 

ODFW conducted surveys of Oregon lower Columbia River coho salmon using a stratified 

random sampling design in 2002, which provided the first abundance estimates for lower 

tributary populations (previously only limited index surveys were available. Estimates of the 

fraction of hatchery-origin spawners accompany the new abundance estimates. In Washington, 

no surveys of natural-origin adult coho salmon abundance are conducted. WDFW provided 

updated information through 2002 on natural-origin smolt production from Cedar, Mill, 

Germany, and Abernathy creeks and the upper Cowlitz River. 

New analyses include tentative designation of demographically independent populations, 

recalculation of metrics reviewed by previous BRTs using additional years of data, estimates of 

median annual growth rate (λ) using different assumptions about the reproductive success of 

hatchery fish, a new stock assessment of Clackamas River coho by ODFW (Zhou and Chilcote 

2003), and estimates of current and historically available stream kilometers. 

Historical Population Structure 

As part of its effort to develop viability criteria for lower Columbia River salmon and 

steelhead, the Willamette/Lower Columbia Technical Recovery Team (WLC-TRT) identified 

historically demographically independent populations of salmon and steelhead in the lower 

381 
COHO SALMON

Figure 210. Tentative historical populations of the Lower Columbia River coho salmon ESU. Source: 

based on work by Willamette/Lower Columbia Technical Recovery Team for Chinook salmon 

and steelhead (Myers et al. 2002). 

Columbia River listed under the ESA (Myers et al. 2002). Population boundaries are based on 

the definition of VSPs developed by NMFS (McElhany et al. 2000). Based on the WLC-TRT’s 

framework for Chinook salmon and steelhead, the BRT tentatively designated populations of 

Lower Columbia River ESU coho salmon (Figure 210). A working group at the Northwest 

Fisheries Science Center hypothesized that the Lower Columbia River coho salmon ESU 

historically consisted of 23 populations. The WLC-TRT has not yet reviewed these population 

designations. With the exception of the Clackamas coho, the populations shown in Figure 210 

are used as the units for the new analyses in this report. 

Previous BRT and ODFW analyses have treated the coho salmon in the Clackamas River 

as a single population (see previous status review updates [Weitkamp et al. 1995 and NMFS 

1996b] for more complete discussion and references). However, recent ODFW analysis (Zhou 

and Chilcote 2003) supports the hypothesis that coho salmon in the Clackamas River consist of 

two populations, an early run and a late run. The late-run population is believed to be descended 

from the native Clackamas River population, and the early run is believed to descend from 

382
30. LOWER COLUMBIA RIVER COHO SALMON ESU 

hatchery fish introduced from Columbia River populations outside the Clackamas River basin. 

There is uncertainty about the population structure of Clackamas River coho; therefore, in this 

report, analyses of Clackamas River coho are conducted under both the single-population and 

two-population hypotheses for comparison. 

For other salmonid species, the WLC-TRT partitioned lower Columbia River populations 

into a number of strata based on major life-history characteristics and ecological zones 

(McElhany et al. 2003). These analyses suggest that a viable ESU would require a number of 

viable populations in each stratum. Coho salmon do not have the major life-history variation 

seen in lower Columbia River steelhead or Chinook salmon, and would thus be divided into 

strata based only on ecological zones. The strata and associated populations for coho salmon are 

identified in Table 83. 

Abundance and Trends 

Recent abundance of natural-origin spawners, and recent fraction of hatchery-origin 

spawners for Lower Columbia River coho salmon ESU populations are summarized in Table 83. 

Natural-origin fish are defined as those whose parents spawned in the wild, while hatchery-origin 

fish are defined as those whose parents were spawned in a hatchery. Some populations (e.g., 

North Fork Lewis River) spawned above now-impassable barriers; they are completely 

extirpated. Most other populations, except for the Clackamas and Sandy River populations, are 

believed to have very little, if any, natural production. References for abundance time series and 

related data are found in Appendix C, Table C-2. 

Clackamas 

The Clackamas River population above North Fork Dam is one of only two populations 

in the ESU for which natural production trends can be estimated. The portion of the population 

above the dam has a relatively low fraction of hatchery-origin spawners, while they dominate the 

area below the dam (Table 83). The recent average number of coho salmon above the dam is 

shown in Table 84, and counts of total adults and natural-origin adults passing North Fork Dam 

is shown in Figure 211. Prior to 1973, hatchery-origin adults and juveniles were released above 

North Fork Dam; the time series from 1957 to 1972 contains an unknown fraction of hatcheryorigin spawners. Because almost all Lower Columbia River ESU coho salmon females and most 

males spawn at 3 years of age, a strong cohort structure is produced. Figure 212 shows the three 

adult cohorts on the Clackamas. As discussed in the section on population structure, multiple 

hypotheses exist regarding the number of historical and current populations in the Clackamas 

Basin. Zhou and Chilcote (2003) partitioned current Clackamas River coho above the North 

Fork Clackamas into two populations (Figure 213). Figure 214 shows the number of juvenile 

coho outmigrants passing North Fork Dam from 1957 to 2002. The long-term trends and growth 

rate (λ) estimates over the entire time series for the total count at North Fork Dam and the early 

run portion have been slightly positive and the short-term trends and λ have been slightly 

negative (Tables 85 and 86). 

The late-run portion of the North Fork Dam count (hypothesized to be the remains of the 

historical Clackamas River coho population) shows negative trends and growth rates over both 

383 
COHO SALMON

Table 83. Recent abundance of natural-origin spawners and recent fraction of hatchery-origin spawners 

for Lower Columbia River ESU coho salmon populations (based on ODFW and PGE data). 

Ecological zonea

 

 Putative population 2002 total spawners 

2002 hatchery 

fraction (%) 

2002 naturalorigin smolts 

Coastal 

Youngs Bay & Big Creek 4,473 91 nd 

Grays River nd nd nd 

Elochoman River nd nd nd 

Clatskanie River 229 60 nd 

Mill, Germany, 

Abernathy creeks 

nd nd 22,700 

Scappoose River 458 0 nd 

Cascade 

Cispus River nd nd 

Tilton River nd nd 

Upper Cowlitz River nd nd 

168,281 

Lower Cowlitz River nd nd nd 

North Fork Toutle River nd nd nd 

South Fork Toutle River nd nd nd 

Coweeman River nd nd nd 

Kalama River nd nd nd 

North Fork Lewis River nd nd 32,695 (Cedar 

Creek only) 

East Fork Lewis River nd nd nd 

Clackamas River 1,001 (above North Fork) 

2,402 (below North Fork) 

12 (above North Fork) 

78 (below North Fork) 

nd 

Salmon Creek nd nd 

Sandy River 310 (above Marmot) 

271 (below Marmot) 

0 (above Marmot) 

97 (below Marmot) 

nd 

Washougal River nd nd nd 

Columbia Gorge 

Lower gorge tributaries nd nd nd 

White Salmon nd nd nd 

Upper gorge tributaries 1,317 (Combined Hood >65b nd 

Hood River River and Oregon only, nd 

upper gorge) a

Ecological zones are based on ecological community and hydrodynamic patterns. 

b

Contains an unknown (i.e., unmarked) additional fraction of hatchery-origin coho from upstream releases. 

the long and short term. However, the confidence intervals on trend and growth rate are large, so 

there is a great deal of uncertainty. Both the long-term and short-term trends and λ have 

relatively high probabilities of being less than one (Tables 87 and 88). 

Since the late 1980s, the number of preharvest recruits has declined relative to the 

number of spawners (Figures 215 and 216). Despite upturns in the last 2 years, the population 

has had more years below replacement since 1990 than above. Thus, even with the dramatic 

reductions in harvest rate (Figure 217), the population failed to respond during the 1990s because 

of this recruitment failure. Although the recent increases in recruitment are encouraging, the 

384
30. LOWER COLUMBIA RIVER COHO SALMON ESU 

Table 84. Recent abundance estimates for subset of Lower Columbia River ESU coho populations. 

Population 

Recent 

geometric mean 

Recent 

Years for recent means arithmetic mean 

Clackamas (above North Fork Dam) 

Total 2000–2002 2,122 2,453 

Early run 1996–1999 302 531 

Late run 1996–1999 35 100 

Sandy (above Marmot Dam) 2000–2002 643 739 

population has not regained earlier levels, and whether they will persist is not known. The recent 

increases in recruitment are attributable in some part to increased marine survival, which cannot 

be predicted with any certainty. Based on stock assessment analysis that assumes the Clackamas 

River coho consist of two populations, Zhou and Chilcote (2003) concluded that the early 

(introduced) run had a relatively low risk of extinction, whereas the late (native) run had a 

relatively high risk of extinction. 

Sandy 

The Sandy River population above Marmot Dam and the Clackamas River populations 

above North Fork Dam are the only populations in the Lower Columbia River coho salmon ESU 

for which natural production trends can be estimated. The portion of the Sandy River population 

above Marmot Dam has almost no hatchery-origin spawners, while they dominate the area below 

the dam (Table 83). The recent average number of coho salmon above Marmot Dam is shown in 

Table 84. Figure 217 shows the total adult count passing the dam, while Figure 218 shows the 

three adult cohorts on the Sandy River. 

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

1955 1965 1975 1985 1995 2005

Year

Adult coho salmon at North Fork Dam

Total adults Natural-origin adults

Figure 211. Clackamas North Fork Dam counts of adult (3-year-old) coho salmon, 1957–2002. 

385 
COHO SALMON

Table 85. Long-term trend and growth rate for subset of Lower Columbia River ESU coho salmon 

populations (95% confidence intervals are in parentheses). The long-term analysis used the entire 

data set. 

Median growth rate (λ)

c

Population 

Years for 

trenda

Years 

for λb Hatchery = 0 

Trend of total 

spawners Hatchery = wild 

Clackamas (above North Fork Dam)

Total 1957–2002 1.009 

(0.994–1.024) 

1973–2002 1.028 

(0.898–1.177) 

1.026 

(0.897–1.174) 

Early run 1973–1998 1.080 

(1.015–1.149) 

1973–1998 1.085 

(0.944–1.248) 

1.085 

(0.944–1.248) 

Late run 1973–1998 0.926 

(0.863– 0.993) 

1973–1998 0.958 

(0.834– 1.102) 

0.958 

(0.834–1.102) 

Sandy 1977–2002 0.997 

(0.941–1.056) 

1977–2002 1.012 

(0.874–1.172) 

1.012 

(0.874–1.172) 

a

 See Table 84 for years. 

b

 Since the fraction of hatchery-origin spawners prior to 1973 in the Clackamas River is unknown, λ estimates for 

the Clackamas River use data from 1973 onward. 

c

 The λ calculation estimates the natural growth rate after accounting for hatchery-origin spawners. The λ estimate 

is calculated under two hypotheses about the reproductive success of hatchery-origin spawners: Hatchery = 0, 

hatchery fish are assumed to have zero reproductive success; Hatchery = wild, hatchery fish are assumed to have 

the same reproductive success as natural-origin fish. 

The long-term and short-term trends for the counts at Marmot Dams are both slightly 

negative (Tables 85 and 86). The long-term λ is slightly positive and the short-term λ is slightly 

negative (Tables 85 and 86). However, the confidence intervals on trend and growth rate are 

large, so there is a great deal of uncertainty. Both the long-term and short-term trends and λ

have relatively high probabilities of being less than one (Tables 87 and 88). The late 1980s 

recruitment failure observed in the Clackamas River is also present in the Sandy River 

population (Figures 219 and 220). If anything, it may be more pronounced in the Sandy River 

system; overall coho salmon abundance levels are lower. Again, despite reductions in harvest 

(Figure 221), the Sandy River coho population has failed to recover to earlier recruitment levels. 

The 2002 return showed a decline from 2000 and 2001 abundance levels (Figure 217). 

Other Oregon Populations 

ODFW initiated a large effort in 2002 to obtain abundance estimates of lower Columbia 

River coho salmon using a random stratified sampling protocol similar to that used to estimate 

abundance of Oregon coastal coho salmon. Results from this survey are presented in Table 83. 

These surveys indicate that hatchery-origin spawners dominate Oregon Lower Columbia River 

ESU coho salmon, but there are some potential pockets of natural production (e.g., Scappoose 

Creek). With data for one year only, it is difficult reach conclusions about the abundance of 

coho salmon in Oregon populations downstream of the Willamette River. Marine survival for 

Lower Columbia River ESU coho salmon returning in 2002 was relatively high and the lower 

Columbia River tributary counts in 2002 are likely to be higher than in low marine survival 

years. Prior to 2002, ODFW conducted coho salmon spawner surveys in the lower Columbia 

River. We combined these surveys to obtain spawners-per-mile information at the scale of our 

386
30. LOWER COLUMBIA RIVER COHO SALMON ESU 

Table 86. Short-term trend and growth rate for subset of Lower Columbia River ESU coho populations 

(95% confidence intervals are in parentheses). 

Median growth rate (λ)

b

Population 

Years for 

trenda

Trend of total 

spawners Years for λ Hatchery = 0 Hatchery = wild 

Clackamas (above North Fork Dam)

Total 1990–2002 0.949 

(0.832–1.083) 

1990–2002 0.975 

(0.852–1.116) 

0.970 

(0.848–1.110) 

Early run 1990–1998 0.884 

(0.601–1.302) 

1990–1998 0.902 

(0.785–1.037) 

0.902 

(0.785–1.037) 

Late run 1990–1998 0.734 

(0.406–1.325) 

1990–1998 0.843 

(0.734–0.969) 

0.843 

(0.734– 0.969) 

Sandy 1990–2002 0.964 

(0.841–1.105) 

1977–2002 0.979 0.978 

(0.845–1.133) (0.845–1.132) a Short-term data sets include data from 1990 to the most recent available year. 

b The λ calculation estimates the natural growth rate after accounting for hatchery-origin spawners. The λ

estimate is calculated under two hypotheses about the reproductive success of hatchery-origin spawners: 

Hatchery = 0, hatchery fish are assumed to have zero reproductive success; Hatchery = wild, hatchery fish are 

assumed to have the same reproductive success as natural-origin fish.

Table 87. Probability that the long-term abundance trend or growth rate of Lower Columbia River ESU 

coho salmon is less than 1. 

Probability λ < 1*

Population 

Years for 

trend 

Probability 

trend < 1 Years for λ Hatchery = 0 Hatchery = wild 

Clackamas (above North Fork Dam) 

Total 1957–2002 0.123 1973–2002 0.283 0.296 

Early run 1993–1998 0.008 1973–1998 0.148 0.148 

Late run 1973–1998 0.984 1973–1998 0.724 0.724 

Sandy 1977–2002 0.544 1977–2002 0.426 0.427 

* Hatchery = 0, hatchery fish are assumed to have zero reproductive success; Hatchery = wild, hatchery fish are 

assumed to have the same reproductive success as natural-origin fish. 

Table 88. Probability that the short-term abundance trend or growth rate of Lower Columbia River ESU 

coho salmon is less than 1. 

Probability λ < 1*

Population 

Years for 

trend 

Probability 

trend < 1 Years for λ Hatchery = 0 Hatchery = wild 

Clackamas (above North Fork Dam) 

Total 1990–2002 0.799 1990–2002 0.582 0.600 

Early run 1990–1998 0.762 1990–1998 0.711 0.711 

Late run 1990–1998 0.872 1990–1998 0.836 0.836 

Sandy 1990–2002 0.716 1990–2002 0.564 0.566 

*

 Hatchery = 0, hatchery fish are assumed to have zero reproductive success; Hatchery = wild, hatchery fish are 

assumed to have the same reproductive success as natural-origin fish. 

387 
COHO SALMON

Table 89. Estimates of natural coho salmon juvenile outmigrants from Washington Lower Columbia 

River streams. Estimates are based on expansions from smolt traps, not total census. 

Outmigrant 

year 

Cowlitz River 

above Cowlitz 

Fallsd

Cedar 

Creeka

Mill 

Creekb

Abernathy 

Creekb

Germany 

Creekb

East Fork 

Lewis Riverc

1997 – – – – – 17,490 

1998 38,354 – – – – 196,520 

1999 27,987 – – – – 88,788 

2000 20,282 – – – 4,514–9,028 236,960 

2001 20,695 6,324 6,991 8,157 – 796,948 

2002 32,695 9,500 6,200 7,000 – 168,281 a Cedar Creek is a tributary of the North Fork Lewis River population. 

b Mill, Germany, and Abernathy creeks are combined into a single population unit for BRT analysis. 

c The East Fork Lewis River estimate shows a range based on uncertainties about trap efficiency. 

d The Cowlitz River above Cowlitz Falls is partitioned into three independent populations (upper Cowlitz, Cispus, 

and Tilton rivers). 

population units (Figures 222–225). In many years over the last two decades, these surveys have 

observed no natural-origin coho salmon spawners. Based on the spawners-per-mile survey data, 

previous assessments have concluded that coho salmon in these populations are extinct or nearly 

so (ODFW 1995a, NMFS 2001a). 

Washington Populations 

Hatchery production also dominates the Washington side of this ESU, and no populations 

are known to be naturally self-sustaining. A National Research Council study (NRC 1996) 

indicated that 97% of 425 fish surveyed on the spawning grounds were first-generation hatchery 

fish. There are no estimates of spawner abundance for Washington Lower Columbia River coho 

salmon ESU populations. However, WDFW recently conducted trapping of juvenile outmigrant 

coho (Table 89), and these data indicate that some natural production is occurring in the Lewis 

River and Mill-Germany-Abernathy creek populations. However, there is no direct way to 

determine whether these populations would be naturally self-sustaining in the absence of 

hatchery-origin spawners. WDFW suggests that juvenile outmigrant production seen in the 

monitored streams is typical of other Washington Lower Columbia River ESU streams and that a 

fairly substantial number of natural-origin spawners may return to the lower Columbia River 

each year. Preliminary WDFW calculations suggest that the natural preharvest recruitment from 

the monitored streams alone may be 17,000 adults (assuming 4% marine survival) (Haymes 

2003). 

The population above Cowlitz Falls is also capable of natural outmigrant production 

(Table 89). However, these populations are not considered currently self-sustaining.58 Three 

dams block anadromous passage to the upper Cowlitz River. Currently, adult coho salmon 

 

58See Footnote 9. 

388
30. LOWER COLUMBIA RIVER COHO SALMON ESU 

Table 90. Total coho salmon hatchery releases into the Columbia River basin (data from Fish Passage 

Center 2001, 2002, 2003). 

Year Hatchery releases 

2000 29,902,509 

2001 25,730,650 

2002 20,011,742 

(some of hatchery origin) are collected below the lower dam (Mayfield Dam) and trucked to the 

area above the upper dam (Cowlitz Falls Dam). There is no appreciable downstream passage 

through the dams, so juvenile outmigrants are collected at Cowlitz Falls Dam and trucked below 

Mayfield Dam. At this time, collection efficiency of outmigrating juveniles at Cowlitz Falls is 

so low (40–60%) that the spawners cannot replace themselves (i.e., fewer adult coho salmon 

return from the relatively low number of outmigrants that are released below Mayfield Dam than 

are planted above Cowlitz Falls Dam). Thus, hatchery production (in addition to the trap-andhaul operation) maintains the populations. 

New Hatchery Information 

Hatchery Production 

Hatchery production dominates the Lower Columbia River coho salmon ESU. Recent 

coho salmon releases in the Columbia River basin (including releases upstream of the ESU 

boundary) are shown in Table 90. The total expected return of hatchery coho salmon to the 

Columbia River basin in 2002 was over a million adults (ODFW News Release, 13 September 

2002; at the time of this report, final 2002 return data were not available). 

Loss of Habitat from Barriers 

Steel and Sheer (2003) analyzed the number of stream kilometers historically and 

currently available to salmon populations in the lower Columbia River (Table 91). Stream 

kilometers usable by salmon are determined based on simple gradient cutoffs and on the 

presence of impassable barriers. This approach overestimates the number of usable stream 

kilometers, because it does not take into consideration aspects of habitat quality other than 

gradient. However, the analysis does indicate that the number of kilometers of stream habitat 

currently accessible is greatly reduced from the historical condition for some populations. 

ESU Summary 

Based on the updated information provided in this report, information contained in 

previous status reviews, and the WLC-TRT’s preliminary analyses, we have tentatively 

identified the number of historical and currently viable populations for the Lower Columbia 

River coho salmon ESU. Only two putative populations have demonstrated appreciable levels of 

natural production (Clackamas and Sandy rivers). There is only very limited information on the 

389 
COHO SALMON

Table 91. Loss of habitat from barriers in the Lower Columbia River coho salmon ESU. 

Population 

Potential 

current habitat 

(%)a

Potential 

historical 

habitat (km)b

Current/ 

historical 

habitat ratioc

Youngs Bay 178 195 91 

Grays River 133 133 100 

Big Creek 92 129 71 

Elochoman River 85 116 74 

Clatskanie River 159 159 100 

Mill, Germany, Abernathy creeks 117 123 96 

Scappoose Creek 122 157 78 

Cispus Riverd 0 76 0 

Tilton Riverd 0 93 0 

Upper Cowlitz Riverd 4 276 1 

Lower Cowlitz River 418 919 45 

North Fork Toutle River 209 330 63 

South Fork Toutle River 82 92 89 

Coweeman River 61 71 86 

Kalama River 78 83 94 

North Fork Lewis River 115 525 22 

East Fork Lewis River 239 315 76 

Clackamas River 568 613 93 

Salmon Creek 222 252 88 

Sandy River 227 286 79 

Washougal River 84 164 51 

Lower gorge tributaries 34 35 99 

Upper gorge tributaries 23 27 84 

White Salmon River 0 71 0 

Hood River 35 35 100 

Total 3,285 5,275 62 

a

 The potential current habitat is the kilometers of stream below all currently impassable barriers 

between a gradient of 0.5% and 4%. 

b The potential historical habitat is the kilometers of stream below historically impassable barriers 

between a gradient of 0.5% and 4%. c The current:historical habitat ratio is the percent of the historical habitat that is currently available. 

This table does not consider habitat quality. 

d The Cispus, Tilton, and upper Cowlitz habitats are listed in this analysis as currently inaccessible 

because volitional passage is not possible. However, a trap-and-haul reintroduction program for 

these populations has been initiated. 

remainder of the 21 putative populations, but most were considered extirpated, or nearly so, 

during the low marine survival period of the 1990s (reviewed in NMFS 2001a). Recently 

initiated spawner surveys by ODFW and juvenile outmigrant trapping by WDFW indicate there 

is some natural coho salmon production in the lower Columbia River. However, hatchery-origin 

390
30. LOWER COLUMBIA RIVER COHO SALMON ESU 

Cohort 2

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

1955 1965 1975 1985 1995 2005

Adult coho salmon at North Fork Dam

Cohort 1

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

1950 1960 1970 1980 1990 2000 2010

Total adults Natural-origin adults

Cohort 3

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

1950 1960 1970 1980 1990 2000 2010

Year

Figure 212. Clackamas North Fork Dam counts of adult (3-year-old) coho salmon by cohort, 1957–2002. 

spawners dominate the majority of populations, and little data indicates they would naturally 

persist in the long term. Of the two populations where natural production can be evaluated, both 

have experienced recruitment failure over the last decade. Recent abundances of the two 

populations are relatively low (especially the Sandy River), placing them in a range where 

environmental, demographic, and genetic stochasticity can be significant risk factors. 

391 
COHO SALMON

0

500

1,000

1,500

2,000

2,500

3,000

3,500

1970 1975 1980 1985 1990 1995 2000

Year

Spawners

Early run Late run

Figure 213. Clackamas River early and late-run coho salmon, 1973–1998. Run designation is based on a 

maximum likelihood approach, assuming two populations with different mean run times. Source: 

Zhou and Chilcote (2003). 

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

160,000

180,000

200,000

1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Outmigrants at North Fork Dam

Figure 214. Total outmigrating juvenile coho salmon passing Clackamas North Fork Dam, 1959–2003.59

 

59D. Cramer, Portland General Electric, Portland, OR. Pers. commun., 5 June 2003. 

392
30. LOWER COLUMBIA RIVER COHO SALMON ESU 

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

1955 1965 1975 1985 1995 2005

Broodyear

Abundance

Adult spawners Preharvest recruits

Figure 215. Estimate of preharvest coho salmon recruits and spawners in the Clackamas River, 

1957–1998. Source: Based on adult counts at North Fork Dam.60

0

5

10

15

20

25

30

1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Broodyear

Preharvest recruits per spawner

Figure 216. Estimate of preharvest coho salmon recruits per spawner in the Clackamas River, 

1957–1998. The dashed line indicates the replacement level. Source: Based on adult counts at 

North Fork Dam.61

 

60See Footnote 59. 

61See Footnote 59. 

393 
COHO SALMON

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1955 1965 1975 1985 1995 2005

Year

Harvest rate

Figure 217. Clackamas River natural-origin coho salmon harvest rate, 1957–1999. The reduction in 

harvest rate was achieved by a switch to retention-only marked hatchery fish and timing the 

fishery to protect natural runs.62 

0

500

1,000

1,500

2,000

2,500

1975 1980 1985 1990 1995 2000 2005

Year

Adults above Marmot Dam

Figure 218. Count of adult (≥3 year old) coho salmon at the Marmot Dam on the Sandy River, 

1977–2002. Almost all spawners above Marmot Dam are of natural origin. For no year is the 

proportion of hatchery-origin spawners estimated to be greater than 2.5%. 

 

62M. Chilcote, Oregon Department of Fish and Wildlife, Fish Division/conservation and recovery, Salem, OR. Pers. 

commun. 

394
30. LOWER COLUMBIA RIVER COHO SALMON ESU 

Cohort 1

0

500

1,000

1,500

2,000

2,500

1975 1980 1985 1990 1995 2000 2005

Cohort 2

0

500

1,000

1,500

2,000

2,500

1975 1980 1985 1990 1995 2000 2005

Adult coho salmon above Marmot Dam

Cohort 3

0

500

1,000

1,500

2,000

2,500

1975 1980 1985 1990 1995 2000 2005

Year

Figure 219. Count of adult (≥3 year old) coho salmon at Marmot Dam on the Sandy River by cohort. 

Almost all spawners above Marmot Dam are of natural origin. For no year is the proportion of 

hatchery-origin spawners estimated to be greater than 2.5%. 

395 
COHO SALMON

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

1975 1980 1985 1990 1995 2000 2005

Broodyear

Abundance

Spawners Preharvest recruits

Figure 220. Estimate of preharvest coho salmon recruits and spawners in the Sandy River, 1977–2002. 

Source: Based on adult counts at Marmot Dam.63

0

2

4

6

8

10

12

14

1975 1980 1985 1990 1995 2000

Broodyear

Preharvest recruits per spawner

Figure 221. Estimate of preharvest coho salmon recruits per spawners in the Sandy River, 1977–2002. 

The dashed line indicates the replacement level. The 1977 broodyear preharvest recruits-perspawner estimate is 68, and the 1983 broodyear estimate is 318. Source: Based on adult counts at 

Marmot Dam.64

 

63See Footnote 59. 

64See Footnote 59. 

396
30. LOWER COLUMBIA RIVER COHO SALMON ESU 

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1975 1980 1985 1990 1995 2000 2005

Year

Harvest rate

Figure 222. Sandy River natural-origin coho salmon harvest rate, 1977–2002. The reduction in harvest 

rate was achieved by switch to retention-only marked hatchery fish and timing the fishery to 

protect natural runs.65

0

50

100

150

200

250

300

1940 1950 1960 1970 1980 1990 2000 2010

Year

Spawners per mile

Figure 223. Youngs Bay coho salmon spawners per mile, 1949–2001. 

 

65See Footnote 62. 

397 
COHO SALMON

0

10

20

30

40

50

60

70

80

1940 1950 1960 1970 1980 1990 2000 2010

Year

Spawners per mile

Figure 224. Big Creek coho salmon spawners per mile, 1949–2001. 

0

5

10

15

20

25

30

35

40

45

50

1940 1950 1960 1970 1980 1990 2000 2010

Year

Spawners per mile

Figure 225. Clatskanie River coho salmon spawners per mile, 1949–2001. 

398
30. LOWER COLUMBIA RIVER COHO SALMON ESU 

0

50

100

150

200

250

300

350

1940 1950 1960 1970 1980 1990 2000 2010

Year

Spawners per mile

Figure 226. Scappoose River spawners per mile, 1949–2001. 

399 
31. Coho Salmon BRT Conclusions 

Oregon Coast Coho Salmon ESU 

The Oregon Coast coho salmon ESU continues to present challenges to those assessing 

extinction risk. The BRT found several positive features compared to the previous assessment in 

1997. Adult spawners for the ESU in 2001 and 2002 exceeded the number observed for any year 

in the past several decades, and preharvest run size rivaled some of the high values seen in the 

1970s. Some notable increases in spawners have occurred in many streams in the northern part 

of the ESU, which was the most depressed area at the time of the last status review evaluation. 

Hatchery reforms have continued, and the fraction of natural spawners that are first-generation 

hatchery fish has been reduced in many areas, compared to highs in the early to mid-1990s. 

On the other hand, the recent years of good returns were preceded by 3 years of low 

spawner escapements—the result of 3 consecutive years of recruitment failure, in which the 

natural spawners did not replace themselves, even in the absence of any directed harvest. These 

3 years of recruitment failure, which immediately followed the last status review in 1997, are the 

only such instances that have been observed in the entire time series of data collected for Oregon 

Coast coho salmon. Whereas the recent increases in spawner escapement have resulted in 

long-term trends in spawners that are generally positive, the long-term trends in productivity in 

this ESU are still strongly negative. 

The BRT votes reflected ongoing concerns for the long-term health of this ESU: a 

majority (56%) of the FEMAT votes were cast in the “likely to become endangered” category, 

with a substantial minority (44%) falling in the “not likely to become endangered” category 

(Table 92). Although the BRT considered the significantly higher returns in recent years to be 

encouraging, most members felt that the factor responsible for the increases was more likely to 

be unusually favorable marine productivity conditions than improvement in freshwater 

productivity. The majority of BRT members felt that to have a high degree of confidence that 

the ESU is healthy, high spawner escapements should be maintained for a number of years, and 

the freshwater habitat should demonstrate the capability of supporting high juvenile production 

from years of high spawner abundance. As indicated in the risk matrix results, the BRT 

considered the decline in productivity to be the most serious concern for this ESU (mean score 

3.2; Table 93). With all directed harvest for these populations already eliminated, harvest 

management (i.e., reducing harvest rates) can no longer compensate for declining productivity. 

The BRT was concerned that if the long-term decline in productivity reflects deteriorating 

conditions in freshwater habitat, this ESU could face very serious risks of local extinctions 

during the next cycle of poor ocean conditions. With the cushion provided by strong returns in 

the last 2 to 3 years, the BRT had much less concern about short-term risks associated with 

abundance (mean score 1.9). 

400 
31. COHO SALMON BRT CONCLUSIONS

Table 92. Tally of FEMAT vote distribution regarding the status of four coho salmon ESUs reviewed by 

the coho salmon BRT. Each of 13 BRT members allocated 10 points among the three status 

categories. 

ESU 

Danger of 

extinction 

Likely to become 

endangered 

Not likely to become 

endangered 

Oregon Coast 0 73 57 

Southern Oregon/Northern 

California Coast 29 87 14 

Central California Coast 96 34 0 

Lower Columbia River 88 42 0 

Table 93. Summary of risk scores (1 = low to 5 = high) for four VSP categories (see Factors Considered 

in Status Assessments subsection for a description of the risk categories) for the four coho salmon 

ESUs reviewed. Data presented are means (range). 

ESU Abundance 

Growth 

rate/productivity 

Spatial structure 

and connectivity Diversity 

Oregon Coast 1.9 (1–3) 3.2 (2–4) 2.3 (1–3) 2.5 (2–3) 

Southern Oregon/Northern 

California Coast 3.8 (2–5) 3.5 (2–5) 3.1 (2–4) 2.8 (2–4) 

Central California Coast 4.8 (4–5) 4.5 (4–5) 4.7 (4–5) 3.6 (2–5) 

Lower Columbia River 4.4 (4–5) 4.2 (3–5) 4.2 (2–5) 4.5 (4–5) 

A minority of BRT members felt that the large number of spawners in the last few years 

demonstrate that this ESU is currently not at significant risk of extinction or likely to become 

endangered. Furthermore, these members felt that the recent years of high escapements, closely 

following years of recruitment failure, demonstrate that populations in this ESU have the 

resilience to bounce back from years of depressed runs. 

Southern Oregon/Northern California Coast Coho Salmon ESU 

A majority (67%) of BRT votes fell in the “likely to become endangered” category, 

although votes in the endangered category outnumbered those in the “not warranted” category by 

2 to 1 (Table 92). The BRT found moderately high risks for abundance and growth 

rate/production, with mean matrix scores of 3.5 to 3.8, respectively, for these two categories. 

The BRT considered risks to spatial structure (mean score = 3.1) and diversity (mean score = 

2.8) to be moderate (Table 93). 

The BRT remained concerned about low population abundance throughout the Southern 

Oregon/Northern California Coast coho salmon ESU relative to historical numbers and longterm downward trends in abundance; however, the paucity of data on escapement of naturally 

produced spawners in most basins continued to hinder risk assessment. A reliable time series of 

adult abundance is available only for the Rogue River. These data indicate that long-term 

401
COHO SALMON

(22-year) and short-term (10-year) trends in mean spawner abundance are upward in the Rogue; 

however, the positive trends reflect effects of reduced harvest (rather than improved freshwater 

conditions) because trends in preharvest recruits are flat. Less-reliable indices of spawner 

abundance in several California populations reveal no apparent trends in some populations and 

suggest possible continued declines in others. Additionally, the BRT considered the relatively 

low occupancy rates of historical coho salmon streams (between 37% and 61% from broodyears 

1986 to 2000) as an indication of continued low abundance in the California portion of this ESU. 

The relatively strong 2001 broodyear, likely the result of favorable conditions in both freshwater 

and marine environments, was viewed as a positive sign, but was a single strong year following 

more than a decade of generally poor years. 

The moderate risk matrix scores for spatial structure reflected a balancing of several 

factors. On the negative side was the modest percentage of historical streams still occupied by 

coho salmon (suggestive of local extirpations or depressed populations). The BRT also remains 

concerned about the possibility that losses of local populations have been masked in basins with 

high hatchery output, including the Trinity, Klamath, and Rogue systems. The extent to which 

strays from hatcheries in these systems are contributing to natural production remains uncertain; 

however, we generally believe that hatchery fish and progeny of hatchery fish constitute the 

majority of production in the Trinity River and may be a significant concern in parts of the 

Klamath and Rogue systems as well. On the positive side, extant populations can still be found 

in all major river basins within the ESU. Additionally, the relatively high occupancy rate of 

historical streams observed in broodyear 2001 suggests that much habitat remains accessible to 

coho salmon. The BRT’s concern for the large number of hatchery fish in the Rogue, Klamath, 

and Trinity river systems was also evident in the risk rating of moderate for diversity. 

Central California Coast Coho Salmon ESU 

A large majority (74%) of the BRT votes fell into the endangered category, with the 

remainder falling into the “likely to become endangered” category (Table 92). The BRT found 

Central California Coast coho salmon to be at very high risk in three of four risk categories, with 

mean scores of 4.8, 4.5, and 4.7 for abundance, growth rate/productivity, and spatial structure, 

respectively (Table 93). Scores for diversity (mean 3.6) indicated BRT members considered 

Central California Coast coho salmon to be at moderate or increasing risk with respect to this 

risk category. The BRT’s principal concerns continue to be low abundance and long-term 

downward trends in abundance of coho salmon throughout the ESU, as well as extirpation or 

near extirpation of populations across most of the southern two-thirds of the ESU’s historical 

range, including several major river basins. Potential loss of genetic diversity associated with 

range reductions or loss of one or more brood lineages, coupled with historical influence of 

hatchery fish, were primary risks to diversity identified by the BRT. Improved oceanic 

conditions, coupled with favorable stream flows, apparently contributed to a strong year class in 

broodyear 2001, as evidenced by an increase in detected occupancy of historical streams. 

However, data were lacking for many river basins in the southern two-thirds of the ESU, where 

populations are considered at greatest risk. Although viewed as a positive sign, the strong year 

follows more than a decade of relatively poor returns. The lack of current estimates of naturally 

produced spawners for any populations within the ESU—and hence the need to use primarily 

presence-absence information to assess risk—continues to concern the BRT. 

402
31. COHO SALMON BRT CONCLUSIONS

Lower Columbia River Coho Salmon ESU 

The BRT reviewed the status of the Lower Columbia River coho salmon ESU in 2000, so 

relatively little new information was available. A majority (68%) of the likelihood votes for 

Lower Columbia River coho salmon ESU fell in the “danger of extinction” category, with the 

remainder falling in the “likely to become endangered” category (Table 92). As indicated by the 

risk matrix totals (Table 93), the BRT had major concerns for this ESU in all VSP risk categories 

(mean scores ranged from 4.2 for spatial structure/connectivity and growth rate/productivity to 

4.5 for diversity). The most serious overall concern was the scarcity of naturally produced 

spawners throughout the ESU, with attendant risks associated with small population, loss of 

diversity, and fragmentation and isolation of the remaining naturally produced fish. In the only 

two populations with significant natural production (Sandy and Clackamas rivers), short- and 

long-term trends are negative, and productivity (as gauged by preharvest recruits) is down 

sharply from recent (1980s) levels. On the positive side, adult returns in 2000 and 2001 were up 

noticeably in some areas, and evidence for limited natural production has been found in some 

areas outside the Sandy and Clackamas rivers. 

The paucity of naturally produced spawners in this ESU can be contrasted with the very 

large number of hatchery-produced adults. Although the scale of the hatchery programs, and the 

great disparity in relative numbers of hatchery and wild fish, produce many genetic and 

ecological threats to the natural populations, collectively these hatchery populations contain a 

great deal of genetic resources that might be tapped to help promote restoration of more 

widespread naturally spawning populations. 

403
COHO SALMON

404
SOCKEYE SALMON

405 
COHO SALMON

406
32. Background and History 

of Sockeye Salmon Listings

Sockeye salmon (Oncorhynchus nerka) spawn in North America from the Columbia 

River in Oregon north to the Noatak River in Alaska; and in Asia from Hokkaido, Japan, north to 

the Anadyr River in Russia (Atkinson et al. 1967, Burgner 1991). The vast majority of sockeye 

salmon spawn in inlet or outlet streams of lakes or in lakes themselves. The juveniles of these 

“lake-type” sockeye salmon rear in lake environments for 1 to 3 years, migrate to sea, and return 

to natal lake systems to spawn after 1 to 4 years in the ocean. However, some sockeye salmon 

populations spawn in rivers without juvenile lake-rearing habitat. Their juveniles rear in slowvelocity sections of rivers for 1 or 2 years (river-type) or migrate to sea as underyearlings, and 

thus rear primarily in salt water (sea-type) (Wood 1995). As with lake-type sockeye salmon, 

river- and sea-type sockeye salmon return to natal spawning habitat after 1 to 4 years in the 

ocean. 

Certain self-perpetuating, nonanadromous populations of O. nerka that become resident 

in lake environments over long periods of time are called kokanee in North America. Genetic 

differentiation among sockeye salmon and kokanee populations indicates that kokanee are 

polyphyletic, having arisen from sockeye salmon on multiple independent occasions, and that 

kokanee may occur sympatrically or allopatrically with sockeye salmon. Numerous studies 

(reviewed in Gustafson et al. 1997) indicate that sockeye salmon and kokanee exhibit a suite of 

heritable differences in morphology, early development rate, seawater adaptability, growth, and 

maturation. These differences appear to be divergent adaptations, which arose from different 

selective regimes associated with anadromous versus nonanadromous life histories. These 

studies also provide evidence that sympatric populations of sockeye salmon and kokanee can be 

both genetically distinct and reproductively isolated (see citations in Gustafson et al. 1997). 

Occasionally, a proportion of juveniles in an anadromous sockeye population remains in the 

rearing lake environment throughout life and is observed on the spawning grounds together with 

their anadromous siblings. Ricker (1938) first used the terms residual sockeye and residuals to 

refer to these resident, nonmigratory progeny of anadromous sockeye salmon. 

In April 1990 NMFS initiated a status review of sockeye salmon in the Salmon River 

basin and received a petition from the Shoshone-Bannock Tribes of the Fort Hall Indian 

Reservation to list Snake River sockeye salmon as endangered under ESA (NMFS 1990, 1991b). 

The NMFS BRT conducted a status review and unanimously agreed that there was insufficient 

information available to determine, with a reasonable degree of certainty, the origin of the 

current sockeye salmon gene pool in Redfish Lake (Waples et al. 1991a). After some discussion, 

the BRT reached a strong consensus that, in this instance, obligations as resource stewards 

required them to proceed under the assumption that recent sockeye salmon in Redfish Lake were 

descended from the original sockeye salmon gene pool. Therefore, as stipulated in the species 

definition paper (Waples 1991), the anadromous component of O. nerka was considered 

separately from the nonanadromous (kokanee) component in determining whether an ESA listing 

407 
SOCKEYE SALMON

was warranted. The decision to treat Redfish Lake sockeye salmon as distinct from kokanee led 

the BRT to conclude that the Redfish Lake sockeye salmon were in danger of extinction (Waples 

et al. 1991a). Subsequently, a proposed rule to list Snake River sockeye salmon as endangered 

was published (NMFS 1991b). After considering 183 written comments and testimony from 

public hearings, NMFS published its final listing determination (NMFS 1991c), which 

designated Snake River sockeye salmon as an endangered species. 

In September 1994, in response to a petition seeking protection for Baker Lake, 

Washington, sockeye salmon under the ESA and more general concerns about the status of West 

Coast salmon and steelhead, NMFS initiated a coastwide status review of sockeye salmon in 

Washington, Oregon, and California, and formed a BRT to conduct the review. After 

considering available information on genetics, phylogeny and life history, freshwater 

ichthyogeography, and environmental features that may affect sockeye salmon, the BRT 

identified six sockeye salmon ESUs―Ozette Lake, Okanogan River, Lake Wenatchee, Quinault 

Lake, Baker River, and Lake Pleasant―and one provisional ESU, Big Bear Creek. The BRT 

reviewed population abundance data and other risk factors for these ESUs. They concluded that 

one (Ozette Lake) was likely to become endangered in the foreseeable future and that the 

remaining ESUs were not in significant danger of becoming extinct or endangered, although the 

team had substantial conservation concerns for some of them (Gustafson et al. 1997). In March 

1998, NMFS published a proposed rule to list the Ozette Lake sockeye salmon ESU as 

threatened under the ESA, and to place the Baker River sockeye salmon ESU on the candidate 

list. Due to the lack of natural spawning habitat and the vulnerability of the entire population to 

problems in artificial habitats, NMFS proposed to add the Baker River ESU to the list of 

candidate species (NMFS 1998g). Subsequently, based on the updated NMFS status review 

(NMFS 1999d) and other information received, NMFS published its final listing determination 

(NMFS 1999e), which designated the Ozette Lake sockeye salmon ESU as threatened and 

removed the Baker River ESU from the candidate list. 

In considering the ESU status of resident of O. nerka forms, the key issue is evaluating 

the strength and duration of reproductive isolation between resident and anadromous forms. 

Many kokanee populations appear to have been strongly isolated from sympatric sockeye 

populations for long periods. Because the two forms experience very different selective regimes 

over their life cycles, reproductive isolation provides an opportunity for adaptive divergence in 

sympatry. Kokanee populations that fall into this category are not generally considered part of 

sockeye ESUs. On the other hand, resident fish appear to be much more closely integrated into 

some sockeye populations. For example, in some situations, anadromous fish may give rise to 

progeny that mature in freshwater (as is the case with residual sockeye), and some resident fish 

may have anadromous offspring. In these cases, where there is presumably some regular, or at 

least episodic, genetic exchange between resident and anadromous forms, they should be 

considered part of the same ESU. 

408
32. BACKGROUND AND HISTORY OF SOCKEYE SALMON LISTINGS

The sockeye salmon BRT met in January, March, and April 2003 to discuss new data and to 

determine whether any modification of the original BRT’s conclusions were warranted as a 

result of the new information. This report summarizes new information and the preliminary 

BRT conclusions on the Snake River sockeye salmon ESU in Idaho and the Ozette Lake sockeye 

salmon ESU in Washington

66

.

 66BRT for the updated status review for West Coast sockeye salmon included Thomas Cooney, Dr. Richard 

Gustafson, Dr. Robert Iwamoto, Gene Matthews, Dr. Paul McElhany, Dr. Mary Ruckelshaus, Dr. Thomas 

Wainwright, Dr. Robin Waples, Dr. John Williams, and Dr. Gary Winans, from Northwest Fisheries Science 

Center (NWFSC); Dr. Peter Adams and Dr. Eric Bjorkstedt, from Southwest Fisheries Science Center (SWFSC); 

and Dr. Reginald Reisenbichler from the Northwest Biological Science Center, U.S. Geological Survey, 

Biological Resources Division, Seattle. 

409
33. Snake River Sockeye Salmon ESU 

Summary of Previous BRT Conclusions 

NMFS conducted the first formal ESA status review for salmon in the Pacific Northwest 

in response to a 1990 petition to list sockeye salmon from Redfish Lake in Idaho as an 

endangered species. The distinctiveness of this population became apparent early in the process: 

it spawns at a higher elevation (2,000 m) and has a longer freshwater migration (1,500 km) than 

any other sockeye salmon population in the world (Waples et al. 1991a). Nor was the precarious 

nature of the anadromous run in doubt: in the fall of 1990, during the course of the status review, 

no adults were observed at Lower Granite Dam or entering the lake, and only one fish was 

observed in each of the 2 previous years. However, a population of kokanee also existed in 

Redfish Lake, and the relationship between the sockeye and kokanee was not well understood. 

This issue was complicated by uncertainty regarding the effects of Sunbeam Dam, which stood 

for over 2 decades about 32 km downstream from Redfish Lake. By all accounts, the dam was a 

serious impediment to anadromous fish, but opinions differed as to whether it was an absolute 

barrier. Some argued that the original sockeye population in Redfish Lake was extirpated as a 

result of Sunbeam Dam and that adult returns in recent decades were simply the result of 

sporadic seaward drift of kokanee (Chapman et al. 1990). According to this hypothesis, the 

original sockeye gene pool was extinct and the remaining kokanee population was not at risk 

because of its reasonably large size (approximately 5,000 to 10,000 spawners per year). An 

alternative hypothesis held that the original sockeye salmon population managed to persist in 

spite of Sunbeam Dam, either by intermittent passage of adults or recolonization from holding 

areas downstream of the dam. The fact that the kokanee population spawns in the inlet stream 

(Fishhook Creek) in August and September and that all the recent observations of sockeye 

spawning have been on the lake shore in October and November was cited as evidence that the 

sockeye and kokanee represent separate populations. According to this hypothesis, the sockeye 

population was critically endangered and perhaps on the brink of extinction. 

At the time of the status review, the BRT unanimously agreed that there was not enough 

information to determine which of the above hypotheses were true (Waples 1991). Although the 

kokanee population had been genetically characterized and determined to be quite distinctive 

compared to other O. nerka populations in the Pacific Northwest, no adult sockeye were 

available for sampling, so the BRT could not evaluate whether the two forms shared a common 

gene pool. When pressed to make a decision regarding the ESU status of Redfish Lake O. nerka, 

the BRT concluded that, because they could not determine with any certainty that the original 

sockeye gene pool was extinct, they should assume that it did persist and was separate from the 

kokanee gene pool. This conclusion was strongly influenced by consideration of the irreversible 

consequences of erring in the other direction (i.e., not listing the species based on the assumption 

that kokanee and sockeye populations were a single gene pool, which later proved not to be the 

case, the species could easily go extinct before the error was detected). 

410 
33. SNAKE RIVER SOCKEYE SALMON ESU 

The status review of Redfish Lake sockeye salmon is the only instance in which the BRT 

was asked to apply the precautionary principle in its deliberations. In subsequent evaluations, 

when the “best available scientific information” was insufficient to distinguish with any certainty 

among competing hypotheses regarding key ESA questions, the BRT has simply reported this 

result and tried to characterize the degree of uncertainty in the team’s conclusions. Decisions 

about how best to apply the precautionary principle in the face of uncertainty in making listing 

determinations were left to the NMFS management and policy arm. 

Based on results of the status review, NMFS proposed a listing of Redfish Lake sockeye 

as endangered in April 1991. When finalized in late 1991, this decision represented the first 

ESA listing of a Pacific salmon population in the Pacific Northwest. At the time of the listing, 

the only population that the BRT and NMFS were confident belonged in this ESU was the 

beach-spawning population of sockeye from Redfish Lake. Historical records indicated that 

sockeye once occurred in several other lakes in the Stanley Basin, but no adults were observed in 

these lakes for many decades and their relationship to the Redfish Lake ESU was uncertain. 

Listing status: Endangered. 

New Data and Updated Analyses 

Four adult sockeye salmon returned to Redfish Lake in 1991; they were taken into 

captivity to join several hundred smolts collected in spring 1991 as they outmigrated from 

Redfish Lake. The adults were spawned and their progeny reared to adulthood along with the 

outmigrants as part of a captive broodstock program, whose major goal was to perpetuate the 

gene pool for a short period of time (one or two generations) to give managers a chance to 

identify and address the most pressing threats to the population. As a result of this program and 

related research, a great deal of new information was gained about the biology of Redfish Lake 

O. nerka and limnology of the lakes in the Stanley Basin. Genetic data collected from the 

returning adults and the outmigrants showed that they were genetically similar but distinct from 

the Fishhook Creek kokanee. However, otolith microchemistry data (Rieman et al. 1994) 

indicated that many of the outmigrants had a resident female parent. These results inspired a 

search of the lake for another population of resident fish that was genetically similar to the 

sockeye. These efforts led to discovery of a relatively small number (perhaps a few hundred) 

kokanee-sized fish that spawn at approximately the same time and place as the sockeye. These 

fish, termed residual sockeye salmon, are considered to be part of the listed ESU. Subsequent 

genetic analysis (Winans et al. 1996, Waples et al. 1997) established the following relationships 

between extant populations of O. nerka from the Stanley Basin and other populations in the 

Pacific Northwest: 

• Native populations of O. nerka from the Stanley Basin (including Redfish Lake sockeye 

salmon and kokanee and Alturas Lake kokanee) are genetically quite divergent from all 

other North American O. nerka populations that have been examined. 

• Within this group, Redfish Lake sockeye and kokanee are genetically distinct, and 

Alturas Lake kokanee are most similar to Redfish Lake kokanee. 

411
SOCKEYE SALMON

• Two gene pools of O. nerka were identified in Stanley Lake—one may be the remnant of 

a native gene pool that survived rotenone treatments in the lake, while the other can be 

traced to introductions from Wizard Falls Hatchery in Oregon. 

• No trace of the original gene pool of O. nerka has been found in Pettit Lake. 

The population that spawned in Pettit Lake in recent decades can be traced to introductions of 

kokanee from northern Idaho; those populations in turn can be traced to stock transfers of Lake 

Whatcom (Washington) kokanee early in the last century. 

Between 1991 and 1998, 16 naturally produced adult sockeye salmon returned to the weir 

at Redfish Lake (Table 94) and were incorporated into the captive broodstock program. This 

program, overseen by the Stanley Basin Sockeye Technical Oversight Committee, produced 

groundbreaking research in captive broodstock technology (Hebdon et al. 1999, Kline and 

Willard 2001, Frost et al. 2002) and limnology (Kohler et al. 2002). The program used three 

different rearing sites to minimize chances of catastrophic failure and produced several hundred 

thousand eggs and juveniles, as well as several hundred adults, for release into the wild (Table 

95). The program reached a milestone in 2000, when more than 200 adults from the program 

returned to Redfish Lake. Currently, the captive broodstock program is being maintained as a 

short-term safety net, pending decisions about longer-term approaches to recovery of the ESU. 

Table 94. Adult anadromous sockeye salmon returns to the Redfish Lake Creek weir, 1954–1968, and 

the Redfish Lake Creek trap and Sawtooth Fish Hatchery weir, 1991–2002. Sources: Redfish 

Lake Creek weir data are from Bjornn et al. (1968).a

Year Adults Year Adults 

1954 998 1987 16 

1955 4,361 1988 1 

1956 1,381 1989 1 

1957 523 1990 0 

1958 55 1991 4 

1959 290 1992 1 

1960 75 1993 8 

1961 11 1994 1 

1962 39 1995 0 

1963 395 1996 1 

1964 335 1997 0 

1965 17 1998 1 

1966 61 1999 7c

1967–1984 ndb 2000 257c

1985 11 2001 26c

1986 29 2002 22c

a Data for 1991–2001 are from L. Hebdon, Idaho Department of Fish and Game, Nampa, 

ID. Pers. commun., 6 January 2003.

b

 No data are available for 1967–1984. 

c Progeny of captive broodstock program. 

412
33. SNAKE RIVER SOCKEYE SALMON ESU 

Table 95. Releases of progeny from the Redfish Lake sockeye salmon captive broodstock program into 

Redfish, Alturas, and Pettit lakes, 1993–2002.*

Year Eggs Presmolts Smolts Adults 

Redfish Lake 

1993 – – – 20 

1994 – 14,000 – 65 

1995 – 82,000 4,000 –

1996 105,000 2,000 12,000 120 

1997 85,000 152,000 – 80 

1998 – 95,000 38,000 –

1999 – 24,000 5,000 21 

2000 – 48,000 – 120 

2001 – 43,000 14,000 69 

2002 – 107,000 39,000 190 

Alturas Lake 

1995 – – – –

1996 – – – –

1997 20,000 100,000 – 20 

1998 – 39,000 – –

1999 – 13,000 – –

2000 – 12,000 – 77 

2001 – 12,000 – –

2002 – 6,000 – –

Pettit Lake 

1995 – 9,000 – –

1996 – – – –

1997 – 9 ,000 – –

1998 – 7,000 – –

1999 20,000 3,000 – –

2000 65,000 6,000 – –

2001 – 11,000 – –

2002 31,000 28,000 – –

*

 L. Hebdon, Idaho Department of Fish and Game, Nampa, ID. 

Pers. commun., 6 January 2003. 

The Snake River Salmon Recovery Team (Bevan et al. 1994; NMFS 1995a) suggested 

that to be considered recovered under ESA, the Snake River sockeye salmon ESU should have 

viable populations in three different lakes, with at least 1,000 naturally produced spawners per 

year in Redfish Lake and at least 500 in each of two other Stanley Basin lakes. As a step toward 

addressing this recommendation, progeny from the Redfish Lake captive broodstock program 

413
SOCKEYE SALMON

were released in Pettit and Alturas lakes as well. In 1991, about 100 outmigrants from Alturas 

Lake were collected at the same time as the Redfish Lake outmigrants and reared to maturity as a 

separate population in captivity. However, because of funding and space limitations and 

uncertainties about priorities for propagating this population, the resulting adults were released 

into the lake rather than being kept for spawning and another generation of captive rearing. 

Because the Alturas Lake kokanee spawn earlier than Redfish Lake sockeye salmon, and the 

kokanee spawn in the inlet stream, it is hoped that the introduction of Redfish Lake sockeye into 

Alturas Lake will not adversely affect this native gene pool.

414
34. Ozette Lake Sockeye SalmonESU

Summary of Previous BRT Conclusions 

Status and Trends 

The 5-year average (geometric mean) estimated abundance of Ozette Lake sockeye 

salmon ESU for the period 1994–1998 was 580, slightly below the average of 700 (for the years 

1992–1996) reported by Gustafson et al. (1997). This decrease is largely because the earlier 

average included two dominant brood-cycle years, although the recent average includes only 

one. The 1998 count of 984 was substantially higher than the count of 498 that was observed 4 

years (one generation) earlier. This count may result primarily from a change in counting 

methods; a video camera was installed in 1998, and the operation period of the weir was 

expanded (7 May–14 August), resulting in a more complete count of all fish passing the weir.67 

It is likely that counts for previous years underestimated total spawner abundance, but the 

magnitude of this bias is unknown. 

Analyses of trends using data through 1998 indicate that the short-term (10-year) trend 

improved from a decline of 9.9% per year in Gustafson et al. (1997) to a relatively low, 2%, 

annual increase. How much this increase was influenced by the change in counting methods in 

1998 is not known. The long-term trend remained slightly downward (–2%). 

Threats 

The BRT identified a variety of threats to the continued existence of sockeye salmon 

populations in Ozette Lake ESU, including siltation of beach-spawning habitat and potential 

genetic effects of past interbreeding with genetically dissimilar kokanee. The BRT received an 

analysis of logging history in the Ozette Basin from Rayonier Northwest Forest Resources 

(Meier 1998). This analysis indicated that most logging in the basin has occurred since the mid1950s: in 1953, only 8.7% of the basin had been logged, while 60% had been logged by 1981. 

Thus, logging occurred largely after the substantial decline in sockeye salmon catch in the early 

1950s.

Previous BRT Conclusions 

The BRT last reviewed the Ozette Lake sockeye salmon ESU status in November 1998. 

Their conclusion was that the ESU was likely to become endangered in the foreseeable future. 

The main uncertainties arose from questions about the reliability of abundance estimates and the 

historical presence of inlet-spawning sockeye salmon in the basin. Perceived risks were focused 

on low current abundance and trends and variability in abundance. At the time of the last status 

assessment, escapements averaging less than 1,000 adults per year implied a moderate degree of 

 

67M. Crewson, Makah Indian Tribe, Neah Bay, WA. Pers. commun., 21 August 1998. 

415 
SOCKEYE SALMON

risk from small-population genetic and demographic variability, with little room for further 

declines before abundances reach critically low levels. Other concerns included siltation of 

beach-spawning habitat, very low current abundance, as compared to harvests in the 1950s, and 

potential genetic effects of past interbreeding with genetically dissimilar kokanee. 

Listing status: Threatened. 

New Data and Updated Analyses 

ESU Status at a Glance 

Historical peak abundance 3,000–18,000 

Historical populations 1+ 

Extant populations 1 

5-year geometric mean escapement 2,267 

ESU Structure 

The Puget Sound TRT considers the Lake Ozette sockeye salmon ESU to be composed of 

one historical population, with substantial substructuring of individuals into multiple spawning 

aggregations. The primary existing spawning aggregations occur in two beach locations—

Allen’s and Olsen’s beaches, and in two tributaries, Umbrella Creek and Big River (both 

tributary-spawning groups were initiated through a hatchery introduction program). Recently, 

mature adults have been located at other beach locations within the lake (e.g., Umbrella Beach, 

Ericson’s Bay, Baby Island, and Boot Bay), but whether spawning occurred in those locations is 

not known (Makah Fisheries Management 2000). Similarly, occasional spawners are found 

sporadically in other tributaries to the lake, but not in as high numbers or as consistently as in 

Umbrella Creek. The Umbrella Creek spawning aggregation was started through collections of 

lake-spawning adults as initial broodstock, and in recent years all broodstock has been collected 

from returning adults to Umbrella Creek (Makah Fisheries Management 2000). The extent to 

which sockeye spawned historically in tributaries to the lake is controversial (Gustafson et al. 

1997), but it is clear that multiple beach-spawning aggregations of sockeye occurred historically, 

and that genetically distinct kokanee currently spawn in large numbers in all surveyed lake 

tributaries (except Umbrella Creek and Big River). The two remaining beach-spawning 

aggregations are probably fewer than the number of aggregations that occurred historically, but 

there is insufficient evidence to determine how many subpopulations occurred in the ESU 

historically. 

Much of the existing spawning in recent years occurs in the spawning aggregation 

created via fry releases into Umbrella Creek. The status of the historically well-documented 

spawning aggregations at Allen’s and Olsen’s beaches is not well understood because of the 

difficulties in observing spawners and sampling carcasses in the tannin-rich lake. 

Updated Status Information 

Because of the concerns about the status of Ozette Lake sockeye salmon ESU, the Lake 

Ozette steering committee was established (composed of representatives from the Makah Tribe, 

416 
34. OZETTE LAKE SOCKEYE SALMON ESU 

Olympic National Park, WDFW, and citizen’s groups) to organize recovery activities for 

sockeye. Makah Fisheries initiated a hatchery program designed to supplement existing beach 

spawners in 1983 (beach spawner supplementation ceased with the 1995 broodyear) and later to 

introduce sockeye to lake tributaries (intentional releases to tributaries began in broodyear 1992) 

(see subsection, Updated Threats Information). Therefore, all the abundance information 

presented contains an unknown fraction of hatchery fish. 

Information on abundance of Ozette Lake sockeye salmon ESU comes from visual counts 

at a weir across the lake outlet; therefore the counts represent total run size. The estimates of 

total run size were revised upward after the 1997 status review due to resampling of data using 

new video counting technology (Figure 227). 

The Makah Fisheries biologists estimate that previous counts of adult sockeye salmon 

returning to the lake were underestimates, and they have attempted to correct run-size estimates 

based on their assessments of human error and variations in interannual run timing (Makah 

Fisheries Management 2000; Table 96). The run-size estimates are very uncertain—an estimate 

of the 95% confidence interval around the 2001 count is N = 3,717 (2,815–5,416) (Fieberg 

2002). The most recent 5-year geometric mean of sockeye salmon returning to Lake Ozette is 

2,267 adults. Because run-size estimates before 1998 are likely to be even more unreliable than 

recent counts, and new counting technology has resulted in an increase in estimated run sizes, no 

statistical estimation of trends is reported. The current trends in abundance are unknown for the 

beach spawning aggregations. Although overall abundance appears to have declined from 

historical levels, whether this resulted in fewer spawning aggregations, lower abundances at each 

aggregation, or both, is not known. 

0

1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000

Year

1000

2000

3000

4000

5000

No. of adults 

Video sampling begins 

Figure 227. Estimated numbers of adult sockeye salmon entering Lake Ozette, 1978–2001. Sources: 

Makah Fisheries Management (2000) and Crewson (2003). 

417 
SOCKEYE SALMON

The adults remain in the lake for an extended period of time (return April–August; spawn 

late October–February) before spawning on beaches or in the tributaries, and the prespawning 

mortality is not known. Therefore, it is not clear what escapement levels to the spawning 

aggregations might be. 

The sockeye salmon returning to Umbrella Creek have averaged more than 10% of the 

total run size to Lake Ozette from 1995 to 1999, and possibly this fraction has been higher in the 

last 2 years (Makah Fisheries Management 2000, M. Crewson68). A portion of the Umbrella 

Creek hatchery sockeye were marked as juveniles beginning in the late 1980s, and results of 

monitoring these marks on returning adults indicates that natural-origin spawners in Umbrella 

Creek in 1999 ranged from 21.4% to 52.9% (Makah Fisheries Management 2000). 

Table 96. Estimated run size of natural-origin recruits to Lake Ozette and Umbrella Creek, and the 

fraction of hatchery-origin fish returning to Umbrella Creek for Lake Ozette sockeye salmon, 

1978–2001. Sources: Makah Fisheries Management (2000) and Crewson (2003). 

Year Total 

run size 

Lake Ozette 

natural origin 

Umbrella Creek 

natural origin 

Umbrella Creek 

hatchery origin 

1978 1,690 nd nd nd 

1979 nd nd nd nd 

1980 nd nd nd nd 

1981 350 nd nd nd 

1982 2,123 nd nd nd 

1983 nd nd nd nd 

1984 502 nd nd nd 

1985 nd nd nd nd 

1986 nd nd nd nd 

1987 nd nd nd nd 

1988 3,599 nd nd nd 

1989 603 nd nd nd 

1990 385 nd nd nd 

1991 684 nd nd nd 

1992 2,548 nd nd nd 

1993 nd nd nd nd 

1994 585 nd nd nd 

1995 nd nd nd 44 

1996 1,778 1,699 79 0 

1997 1,133 998 nd 135 

1998 1,406 1,310 nd 96 

1999 2,076 1,676 149 251 

2000 4,399 1,293a 3,106 

2001 591 3,525b 4,116 

nd = no data. 

a

 Total combines Lake Ozette natural origin and Umbrella Creek natural origin. 

b

 Total combines Umbrella Creek natural origin and Umbrella Creek hatchery origin. 

 

68See Footnote 67. 

418 
34. OZETTE LAKE SOCKEYE SALMON ESU 

Table 97. Percentages of 5-year-old fish sampled from otoliths in carcasses in sockeye salmon 

subpopulations in Lake Ozette, 2000–2001.a

2000 2001 

Subpopulation 

Percent 

5-year-olds No. of samples 

Percent 

5-year-olds No. of samples 

Olsen’s Beach 2.1 47 1.2 81 

Allen’s Beach 0 51 0 7 

Umbrella Creek 3.8 18.5b 183 195 a

 M. Crewson, Makah Fisheries, Neah Bay, WA. Pers. commun., 21 August 1998.

b One out of 195 fish sampled from Umbrella Creek was a 6-year-old. 

Age data from otolith samples in 2000 and 2001 in Umbrella Creek and Allen’s and 

Olsen’s beaches suggest that a small fraction of 5-year-old fish do occur in Umbrella Creek and 

Olsen’s Beach subpopulations (Table 97). These age data affect previous estimates of returns 

from different broodyears, since early analyses assumed 100% 4-year-old sockeye. 

Based on examination of carcasses retrieved from Allen’s and Olsen’s beaches for otolith 

marks applied to hatchery fish, straying of hatchery fish from the Umbrella Creek program 

appears to be very low (Makah Fisheries Management 2000). 

Updated Threats Information 

The Makah Fisheries staff has been working with the Lake Ozette steering committee to 

identify factors for decline in Lake Ozette sockeye salmon. Thus far, primary sources of threats 

to VSP parameters include: 

• loss of adequate quality and quantity of spawning and rearing habitat, 

• predation and disruption of natural predator-prey relationships, 

• introduction of nonnative fish and plant species, 

• past overexploitation, 

• poor ocean conditions, and 

• interactions among those factors. 

There has been no directed harvest on Lake Ozette sockeye salmon since 1982, and commercial 

fisheries stopped in 1974 (Gustafson et al. 1997, Makah Fisheries Management 2000). 

Previous releases of hatchery fish in Lake Ozette have been relatively low magnitude, but 

some of the releases were from sockeye salmon stocks outside the ESU or were from Ozette 

kokanee-sockeye hybrids (Gustafson et al. 1997). The latest artificial propagation program in 

Lake Ozette focused on sockeye salmon introductions into Big River and Umbrella Creek 

tributaries; chosen because of their apparent suitable spawning habitat and relatively low 

numbers of naturally spawning kokanee. The Umbrella Creek Hatchery has been in place since 

419 
SOCKEYE SALMON

1982. The first egg source was from the Quinault River, and progeny were hatched at Umbrella 

Creek, reared in a net pen in Lake Ozette, and released in June 1983. From 1983 to 1999, all 

eggs were collected from Olsen’s or Allen’s beach spawners. Beginning in 2000, the source for 

future broodstock for tributary releases will be from returns to tributaries, primarily Umbrella 

Creek. The SSHAG group (SSHAG 2003) determined that the Umbrella Creek Hatchery stock 

would have a category score of 1 or 2 (see Appendix D, Table D-1). 

The Makah Tribe and the NMFS Marine Mammal Lab have monitored predation on Lake 

Ozette sockeye salmon by harbor seals and river otters, and biologists believe that prespawning 

predation rates could be significant. Predation by otters and seals has been observed in the lake 

and in the outlet river, especially in the vicinity of the counting weir (Makah Fisheries 

Management 2000). In addition, predation scars (ranging from scratches to bite marks to lack of 

heads) on carcasses sampled and adults counted are noted. 

The majority of Lake Ozette and the Ozette River lie within the boundaries of Olympic 

National Park, but private timber companies own the majority of the land in the Lake Ozette 

watershed (Makah Fisheries Management 2000). Recent accelerated timber harvest, roadbuilding activity, and forest-practice and water-quality violations are reported in an analysis by 

the Makah Tribe (Makah Fisheries Management 2000). New activities related to mitigating and 

improving degraded habitat quality could include the Forest and Fish Agreement (if 

implemented). 

420 
35. Sockeye Salmon BRT Conclusions 

Snake River Sockeye Salmon ESU 

The BRT members were unanimous in their assessment this ESU’s status: 100% of the 

likelihood votes were in the “danger of extinction” category (Table 98). Mean risk matrix scores 

were extremely high (4.9–5.0) for every VSP element (Table 99). On the positive side, the 

captive broodstock program initiated as an emergency measure in 1991 has, at least temporarily, 

rescued this ESU from the brink of extinction, and associated research has provided a great deal 

of information about the biology of this species and its environment. The return of over 200 

adults from the hatchery program in 2000 is considered encouraging, but the status of the natural 

population remains extremely precarious. Only 16 naturally produced adults have returned since 

the listing in 1991, and all were taken into the captive program. 

Ozette Lake Sockeye Salmon ESU 

A majority (70%) of the BRT votes for the Ozette Lake sockeye salmon ESU were cast in 

the “likely to become endangered” category, with the remainder about equally split between the 

“danger of extinction” and “not likely to become endangered” categories (Table 98). Moderately 

high concerns for all VSP elements are indicated by mean risk matrix scores ranging from 3.0 for 

diversity to 3.8 for spatial structure (Table 99). Risk assessment for this ESU continues to be 

hampered by very incomplete data. Although significant efforts to improve this situation have 

Table 98. Tally of FEMAT vote distribution regarding the status of two sockeye salmon ESUs reviewed. 

Thirteen BRT members allocated 10 points among the three status categories. 

ESU Danger of extinction 

Likely to become 

endangered 

Not likely to become 

endangered 

Snake River 130 0 0 

Ozette Lake 21 91 18 

Table 99. Summary of risk scores (1 = low to 5 = high) for four viable salmonid population categories for 

the Snake River and Ozette Lake sockeye salmon ESUs. Data presented are means (range). 

ESU Abundance 

Growth 

rate/productivity 

Spatial structure 

and connectivity Diversity 

Snake River 5.0 (5–5) 5.0 (5–5) 4.9 (4–5) 5.0 (5–5) 

Ozette Lake 3.7 (3–4) 3.5 (3–4) 3.8 (3–5) 3.0 (2–4) *

 For a description of the risk categories, see the subsection, Factors Considered in Status Assessments, in Section 1, 

Introduction. 

421 
SOCKEYE SALMON

been taken recently, the process of perfecting the new techniques and adjusting for biases in 

previous data is still in progress. Recent evaluations have cast even more doubt on the 

usefulness of population data prior to about 1997, which further complicates the assessment of 

an ESU for which data are already very limited. 

It appears that overall abundance is low for this population, which represents an entire 

ESU, and may be substantially below historical levels. The BRT was concerned about reports 

that habitat degradation in the lake has resulted in loss of numerous sites suitable for beach 

spawners, but accurately assessing the situation is difficult because of poor visibility in the lake. 

The number of returning adults in the last few years has increased, but a substantial (but 

uncertain) fraction of these appear to be of hatchery origin, leading again to uncertainty 

regarding growth rate and productivity of the natural component of the ESU. Another 

uncertainty noted by the BRT related to reports that prespawning predation by harbor seals and 

river otters may be significant, but how large a factor this is and how it compares with historical 

patterns is not known. 

422 
CHUM SALMON

423 
SOCKEYE SALMON

424 
36. Background and History 

of Chum Salmon Listings 

Chum salmon (Oncorhynchus keta) are semelparous, spawn primarily in freshwater, and 

apparently exhibit obligatory anadromy, as there are no recorded landlocked or naturalized 

freshwater populations (Randall et al. 1987). The species is known for the enormous canine-like 

fangs and striking body color (a calico pattern, with the anterior two-thirds of the flank marked 

by a bold, jagged, reddish line and the posterior third by a jagged black line) of spawning males. 

Females are less flamboyantly colored and lack the extreme dentition of the males. 

The species has the widest natural geographic and spawning distribution of any Pacific 

salmonid, primarily because its range extends farther along the shores of the Arctic Ocean than 

other salmonids. Chum salmon have been documented to spawn from Korea and the Japanese 

island of Honshu, east around the rim of the North Pacific Ocean to Monterey Bay in California. 

Presently, major spawning populations are found only as far south as Tillamook Bay on the 

northern Oregon coast. The species’ range in the Arctic Ocean extends from the Laptev Sea in 

Russia to the Mackenzie River in Canada. Chum salmon may historically have been the most 

abundant of all salmonids: Neave (1961) estimated that prior to the 1940s, chum salmon 

contributed almost 50% of the total biomass of all salmonids in the Pacific Ocean. Chum salmon 

also grow to be among the largest of Pacific salmon, second only to Chinook salmon in adult 

size, with individual chum salmon reported up to 108.9 cm in length and 20.8 kg in weight 

(Pacific Fisherman 1928). Average size for the species is around 3.6–6.8 kg (Salo 1991). 

Chum salmon spend more of their life history in marine waters than other Pacific 

salmonids. Chum salmon, like pink salmon, usually spawn in coastal areas, and juveniles 

outmigrate to sea water almost immediately after emerging from the gravel that covers their 

redds (Salo 1991). This ocean-type migratory behavior contrasts with the stream-type behavior 

of some other species of the genus Oncorhynchus (e.g., coastal cutthroat trout, steelhead, coho 

salmon, and most types of Chinook and sockeye salmon), which usually migrate to sea at a larger 

size, after months or years of freshwater rearing. This means survival and growth in juvenile 

chum salmon depends less on freshwater conditions than on favorable estuarine conditions. 

Another behavioral difference between chum salmon and species that rear extensively in 

freshwater is that chum salmon form schools, presumably to reduce predation (Pitcher 1986), 

especially if their movements are synchronized to swamp predators (Miller and Brannon 1982). 

The first ESA status review of West Coast chum salmon (Johnson et al. 1997) was 

published in December 1997. It identified four ESUs: 1) Puget Sound/Strait of Georgia chum 

salmon ESU, which includes all chum salmon populations from Puget Sound, the Strait of 

Georgia, and the Strait of Juan de Fuca up to and including the Elwha River, with the exception 

of summer-run chum salmon from Hood Canal; 2) Hood Canal summer-run chum salmon ESU, 

which includes summer-run populations from Hood Canal and Discovery and Sequim bays on 

425 
CHUM SALMON

the Strait of Juan de Fuca; 3) Pacific Coast chum salmon ESU, which includes all natural 

populations from the Pacific coasts of California, Oregon, and Washington, west of the Elwha 

River on the Strait of Juan de Fuca; and 4) Columbia River chum salmon ESU. 

In March 1998, NMFS published a Federal Register notice describing the four ESUs and 

proposed a rule to list two―Hood Canal summer-run and Columbia River ESUs―as threatened 

under ESA (NMFS 1998h). In March 1999, the two ESUs were listed as proposed, with the 

exception that the Hood Canal summer-run ESU was extended westward to include summer-run 

fish recently documented in the Dungeness River (NMFS 1999f).

NMFS convened a BRT to update the status of listed chum salmon ESUs coastwide. The 

chum salmon BRT69 met in January 2003 in Seattle, Washington, to review updated information 

on each ESU under consideration. 

 

69The BRT for the updated chum salmon status review included, from the Northwest Fisheries Science Center: Tom 

Cooney, Dr. Robert Iwamoto, Dr. Robert Kope, Gene Matthews, Dr. Paul McElhany, Dr. James Myers, Dr. Mary 

Ruckelshaus, Dr. Thomas Wainwright, Dr. Robin Waples, and Dr. John Williams; from the Southwest Fisheries 

Science Center: Dr. Peter Adams, Dr. Eric Bjorkstedt, and Dr. Steve Lindley; from the Alaska Fisheries Science 

Center (Auke Bay Laboratory): Alex Wertheimer; and from the U.S. Geological Survey Biological Resource 

Division: Dr. Reginald Reisenbichler. 

426 
37. Hood Canal Summer-Run Chum Salmon ESU 

Summary of Previous BRT Conclusions 

The status of Hood Canal summer-run chum salmon was formally assessed during a 

coastwide status review (Johnson et al. 1997). In November 1998, a BRT was convened to 

update the status of the ESU by summarizing information received after that review and 

comments on the 1997 status review and to present BRT conclusions concerning ESU 

delineation and risk assessment for chum salmon in Washington, Oregon, and California (NMFS 

1999f). 

Status and Trends 

In 1994, petitioners identified 12 streams draining into Hood Canal as recently supporting 

spawning populations of summer-run chum salmon. At the time of the petition, summer-run 

chum salmon runs in five of these streams may already have been extinct, and those in six of the 

remaining seven showed strong downward trends. Similarly, summer-run chum salmon in 

Discovery and Sequim bays were also at low levels of abundance. Spawner surveys in 1995 and 

1996 revealed substantial increases in the number of summer-run chum salmon returning to 

some streams in Hood Canal and the Strait of Juan de Fuca. However, serious concerns 

remained (Johnson et al. 1997). First, the population increases in 1995 and 1996 were limited to 

streams on the western side of Hood Canal, especially the Quilcene River system, while streams 

on the southern and eastern sides of Hood Canal continued to have few or no returning spawners. 

Second, a hatchery program initiated in 1992 was at least partially responsible for adult returns to 

the Quilcene River system. Third, the strong returns to the west side streams were the result of a 

single, strong year class, although declines in most of these streams were severe and spanned two 

decades. Last, greatly reduced incidental harvest rates in recent years probably contributed to the 

increased abundance of summer-run chum salmon in this ESU. Spawning escapement to the 

ESU was estimated to be 10,013 fish in 1997 and 5,290 fish in 1998. Of these totals, 8,734 

spawners in 1997 and 3,959 spawners in 1998 returned to streams with supplementation 

programs. 

Previously Reported Threats 

A variety of threats to the continued existence of summer-run chum salmon populations 

in Hood Canal were identified in the status review (Johnson et al. 1997), including degradation 

of spawning habitat, low river flows, possible competition among hatchery fall-run chum salmon 

juveniles and naturally produced summer-run chum salmon juveniles in Hood Canal, and high 

levels of incidental harvest in salmon fisheries in Hood Canal and the Strait of Juan de Fuca. 

427 
CHUM SALMON

Previous BRT Conclusions 

The status of the Hood Canal summer-run chum salmon ESU was last reviewed in 

November 1998, when the BRT concluded that the ESU was likely to become endangered in the 

foreseeable future. The BRT’s primary concerns relating to this ESU’s status were low current 

abundance relative to historical numbers, extirpation of historical populations on the east side of 

Hood Canal, declining trends, and low productivity. Other concerns included the increasing 

urbanization of the Kitsap Peninsula, recent increases in pinniped populations in Hood Canal, 

and recent increases in spawning escapement that were associated primarily with hatchery 

supplementation programs. Concerns were mitigated to some extent by recent reforms in 

hatchery practices for fall-run chum salmon and measures taken by the state and tribes to reduce 

harvest impacts on summer-run chum salmon. 

Listing status: Threatened. 

New Data and Updated Analyses 

ESU Status at a Glance 

Historical peak abundance N/A 

Historical populations 16 

Extant populations 8 

1999–2002 geometric mean escapement per 

extant population 

10–4,500 

1999–2002 arithmetic mean escapement per 

extant population 

52–4,700 

Recent (1990–2002) trend per extant 

population 

0.82–1.62 (median = 1.17) 

Long-term trend per extant population 0.88–1.08 (median = 0.94) 

ESU Structure 

The Hood Canal summer-run chum salmon ESU is composed of 16 historically 

independent populations, 8 of which are presumed to be extant currently (Table 100). Most of 

the extirpated populations occur on the eastern side of Hood Canal, and some of the 7 putatively 

extinct stocks are the focus of extensive supplementation programs under way in the ESU 

(WDFW and PNPTT 2000, 2001). 

Hood Canal summer-run chum salmon are part of an extensive rebuilding program 

developed and implemented beginning in 1992 by the state and tribal comanagers (WDFW and 

PNPTT 2000, 2001.) The Summer-Run Chum Salmon Conservation Initiative involves six 

supplementation and two reintroduction projects. The largest supplementation program occurs at 

428 
37. HOOD CANAL SUMMER-RUN CHUM SALMON ESU 

Table 100. Historical populations of summer-run chum salmon in the Hood Canal chum salmon ESU. 

Source: WDFW and PNPTT (2001). 

Stock Status 

Union River Extant 

Lilliwaup Creek Extant 

Hamma Hamma River Extant 

Duckabush River Extant 

Dosewallips River Extant 

Big/Little Quilcene rivers Extant 

Snow/Salmon creeks Extant 

Jimmycomelately Creek Extant 

Dungeness River Unknown 

Big Beef Creek Extinct 

Anderson Creek Extinct 

Dewatto Creek Extinct 

Tahuya River Extinct 

Skokomish River Extinct 

Finch Creek Extinct 

Chimacum Creek Extinct 

the Big Quilcene River fish hatchery; beginning with the 1997 broodyear, all fry from the 

Quilcene facility have been adipose fin clipped. Summer-run chum salmon hatchery fish in 

Salmon Creek have been thermally marked since 1992, and other supplementation programs in 

Hood Canal recently instigated thermal mass marking of otoliths to distinguish between 

hatchery- and natural-origin spawners. Reintroduction programs were initiated in Big Beef and 

Chimacum creeks. Small numbers of marked fish collected in streams (i.e., <3 per stream) over 

the 1999–2000 season indicate that some straying of summer-run chum salmon from the Big 

Quilcene River supplementation program is occurring in other Hood Canal streams (WDFW and 

PNPTT 2001). 

The methods for summary statistics reported below are described in Section 2 of this 

report. We report summary statistics only for the eight extant populations of summer-run chum 

salmon in Hood Canal; where information is available, a few additional populations experiencing 

hatchery reintroductions or natural recolonization are included in some tables for completeness. 

More detailed information on the sources, data years, and nature of the information reported 

below is summarized in Appendix E for each population. 

Abundance of Natural Spawners 

Recent 4-year (1999–2002) geometric mean abundance of summer-run chum salmon in 

Hood Canal streams containing extant populations ranges from 10 to just over 4,500 spawners 

(median = 576, mean = 1,064) (Table 101, Figures 228–241). Estimates for the fraction of 

hatchery fish in the combined Quilcene and Salmon/Snow populations are as high as 28–51%, 

indicating that the supplementation program is resulting in spawners in streams (Table 101). In 

addition to the supplementation programs, reintroduction of hatchery fish to previously occupied 

streams is occurring in Big Beef and Chimacum creeks. Recent geometric mean escapements 

429 
CHUM SALMON

Table 101. Abundance and estimated fraction of hatchery fish in natural escapements of Hood Canal 

summer-run chum salmon spawning populations. Source: Data are from WDFW and PNPTT 

(2000, 2001); Puget Sound TRT database, unpublished data available from N. Sands, Northwest 

Fisheries Science Center, Seattle. 

4-year escapement (1999–2002) 

Population Current status 

Geometric mean 

(min.–max.) 

Arithmetic 

mean 

Percent hatchery 

origin in natural 

escapement 

(1995–2001) 

Jimmycomelatelyd Extant 10 (1–192) 52 na 

Salmona/Snow Extant 1,521 (463–5,921) 2,441 0–69 

Combined Quilcene Extant 4,512 (3,065–6,067) 4,665 5–51 

Lilliwaupa Extant 13 (1–775) 202 na 

Hamma Hammac Extant 558 (173–2,260) 783 na 

Duckabush Extant 382 (92–942) 507 na 

Dosewallips Extant 919 (351–1,627) 1,057 na 

Unione Extant 594 (159–1,426) 769 na 

Chimacum Extinct, 

reintroduction 

198 (0–903) 464 100 (>1999) 

Big Beefb Extinct, 

reintroduction 

17 (0–826) 376 100 (>1999) 

Dewatto Extinct, natural 

recolonization 

9 (2–32) 14 na 

a Supplementation program began in 1992; recent low spawner numbers in Lilliwaup due in part to large fraction of 

return used for broodstock (J. Ames, Washington Department of Fish and Wildlife, Olympia, WA. Pers. 

commun., 28 March 2003). 

b

 Reintroduction program began in 1996. 

c

 Supplementation program began in 1997. 

d

 Supplementation program began in 1999; recent low spawner numbers were due in part to large fraction of return 

used for broodstock (J. Ames, Washington Department of Fish and Wildlife, Olympia, WA. Pers. commun., 28 

March 2003). 

e

 Supplementation program began in 2000.

from those programs are 17 and 198 adults respectively (over 800 adults in a single year returned 

to each stream), suggesting that hatchery juveniles released several years ago are successfully 

returning as adults to spawn. 

The eight extant summer-run chum salmon stocks in Hood Canal are spawning in 13 

streams, primarily on the western side of Hood Canal. The spatial distribution of the summerrun chum salmon populations in Hood Canal is being extended through reintroduction programs 

in Big Beef and Chimacum creeks, and through an apparent natural recolonization in the 

Dewatto River.70

 

70J. Ames, Washington Department of Fish and Wildlife, Olympia. Pers. commun., 28 March 2003. 

430 
37. HOOD CANAL SUMMER-RUN CHUM SALMON ESU 

0

1000

2000

3000

4000

5000

6000

7000

1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total Hatchery origin

Figure 228. Salmon/Snow creeks summer-run chum salmon annual spawner abundance versus year by 

population, 1974–2002. 

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Figure 229. Dosewallips River summer-run chum salmon annual spawner abundance versus year by 

population, 1972–2002. 

431 
CHUM SALMON

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Total Hatchery origin

Figure 230. Combined Quilcene River summer-run chum salmon annual spawner abundance versus year 

by population, 1974–2002. 

0

200

400

600

800

1000

1200

1400

1600

1800

1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Figure 231. Jimmycomelately Creek summer-run chum salmon annual spawner abundance versus year 

by population, 1974–2002. 

432 
37. HOOD CANAL SUMMER-RUN CHUM SALMON ESU 

0

2000

4000

6000

8000

10000

12000

14000

16000

1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Figure 232. Hamma Hamma River summer-run chum salmon annual spawner abundance versus year by 

population, 1968–2002. 

0

500

1000

1500

2000

2500

1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Figure 233. Lilliwaup River summer-run chum salmon annual spawner abundance versus year by 

population, 1971–2002. 

433 
CHUM SALMON

0

500

1000

1500

2000

2500

3000

3500

1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Figure 234. Union River summer-run chum salmon annual spawner abundance versus year by 

population, 1974–2002. 

0

1000

2000

3000

4000

5000

6000

7000

1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 235. Salmon/Snow creeks summer-run chum salmon recruit and spawner abundance versus year 

by population, 1974–2002. 

434 
37. HOOD CANAL SUMMER-RUN CHUM SALMON ESU 

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 236. Dosewallips River summer-run chum salmon recruit and spawner abundance versus year by 

population, 1972–2002. 

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 237. Combined Quilcene River summer-run chum salmon recruit and spawner abundance versus 

year by population, 1974–2002. 

435 
CHUM SALMON

0

200

400

600

800

1000

1200

1400

1600

1800

1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 238. Jimmycomelately Creek summer-run chum salmon recruit and spawner abundance versus 

year by population, 1974–2002. 

0

2000

4000

6000

8000

10000

12000

14000

16000

1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 239. Hamma Hamma River summer-run chum salmon recruit and spawner abundance versus year 

by population, 1968–2002. 

436 
37. HOOD CANAL SUMMER-RUN CHUM SALMON ESU 

0

500

1000

1500

2000

2500

1965 1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 240. Lilliwaup River summer-run chum salmon recruit and spawner abundance versus year by 

population, 1971–2002. 

0

500

1000

1500

2000

2500

3000

3500

1970 1975 1980 1985 1990 1995 2000 2005

Year

Abundance

Preharvest recruits Spawners

Figure 241. Union River summer-run chum salmon recruit and spawner abundance versus year by 

population, 1974–2002. 

437 
CHUM SALMON

Trends in Natural Spawners 

Long-term trends in abundance for extant naturally spawning populations of summer-run 

chum salmon in Hood Canal indicate that only two populations (combined Quilcene and Union 

rivers) are increasing in abundance over the length of available time series (Table 102). The 

median long-term trend over all populations is 0.94, indicating that most populations are 

declining at a rate of 6% per year. The range in long-term trend across the extant populations in 

Hood Canal is from 0.88 in the Jimmycomelately and Lilliwaup populations to 1.08 in the Union 

population. The Quilcene population’s positive growth rate is almost surely due to the 

supplementation program on that stream. 

In contrast to long-term trends, most of the naturally spawning populations of Hood 

Canal summer-run chum salmon exhibit increasing abundance over the short term—seven of 

eight extant populations in the ESU increased in abundance from 1990 to 2002 (Table 102). 

These recent increases likely reflect the supplementation programs in some streams and possibly 

recent improvements in ocean conditions. Short-term median population growth rates (λ) were 

calculated using two assumptions about the reproductive success of naturally spawning hatchery 

fish: the reproductive success was 0 (i.e., H0), or the reproductive success was equal to that of 

wild fish (i.e., H1). Differing assumptions about the reproductive success of hatchery fish only 

affected calculations of short-term λ for two populations because of the dearth of information on 

the fraction of hatchery fish in time series (Table 102). The median short-term λ (1.18) and 

short-term trend (1.17) over all populations are very similar. The most impressive short-term 

Table 102. Estimates of long- and short-term trends, short-term median population growth rate (λ), and 

their 95% confidence intervals (CI) for natural spawners in extant Hood Canal summer-run chum 

salmon populations. Source: Data are from WDFW and PNPTT (2000, 2001); Puget Sound TRT 

database, unpublished data, available from N. Sands, Northwest Fisheries Science Center, Seattle, 

WA 98119. 

Population Data years 

Long-term trend 

(95% CI) 

Short-term trenda

(95% CI) 

Short-term λb

(+ lnSE) 

Big/Little Quilcenec 1974–2002 1.05 (0.96–1.16) 1.62 (1.31–2.01) 1.39 (0.22) 

Dosewallips 1972–2002 0.96 (0.90–1.04) 1.25 (0.94–1.63) 1.17 (0.24) 

Duckabush 1968–2002 0.91 (0.87–0.96) 1.14 (0.96–1.36) 1.1 (0.17) 

Hamma Hamma 1968–2002 0.90 (0.86–0.94) 1.20 (1.04–1.40) 1.3 (0.19) 

Jimmycomelately 1974–2002 0.88 (0.84–0.93) 0.815 (0.64–1.03) 0.85 (0.16) 

Lilliwaup 1971–2002 0.88 (0.83–0.92) 1.00 (0.74–1.37) 1.19 (0.44) 

Salmon/Snowc 1974–2002 0.99 (0.94–1.03) 1.24 (1.12–1.37) 1.23 (0.10)c

Union 1974–2002 1.08 (1.05–1.12) 1.10 (1.00–1.22) 1.15 (0.10) a Short term is 1990 to 2002. 

b

 Short-term λ is calculated assuming the reproductive success of hatchery-origin spawners is equivalent to that of 

wild-origin spawners (in cases where information on hatchery fish is available). 

c Estimates of the fraction of hatchery fish are available only for the combined Quilcene and Salmon/Snow 

populations for the years 1995–2000. 

438 
37. HOOD CANAL SUMMER-RUN CHUM SALMON ESU 

increase in natural spawner abundance occurred in the Quilcene population (trend = 1.62, λ = 

1.39), where the supplementation program appears to be succeeding in returning natural 

spawners to the Big and Little Quilcene rivers. The only population with a declining short-term 

trend and growth rate is the Lilliwaup, where many of the returning spawners have been 

collected for broodstock in the supplementation program. 

Updated Information on Potential Threats 

The Puget Sound TRT estimated annual fishery exploitation rates for each summer-run 

chum salmon population in the Hood Canal ESU (Table 103). Exploitation rates are calculated 

as the percentage of the total return that is caught in fisheries (i.e., total return = catch + 

broodstock take + escapement). The estimated numbers of adults harvested (i.e., catch) from 

Washington and Canadian fisheries are supplied by the comanagers.71 Catch data are available 

for Hood Canal summer-run chum salmon from 1974 to the present. 

Exploitation rates on the eight extant Hood Canal summer-run chum salmon populations 

averaged 25% (median = 15%; range 8%–56%) in the earliest 5 years of data availability 

(1974–1978). The annual exploitation rates increased in the 1980s as a result of increased coho 

Table 103. Average annual exploitation rates on populations of Hood Canal summer-run chum salmon 

during three time periods, 1974–2002. Sources: Data are from WDFW and PNPTT (2000, 

2001).*

Population 

1974–1978 mean 

exploitation rate (%) 

1979–1997 mean 

exploitation rate (%) 

1998–2002 mean 

exploitation rate (%) 

Big/Little Quilcene 28 64 13 

Lilliwaup 55 43 3 

Dosewallips 15 34 3 

Duckabush 15 34 3 

Hamma Hamma 15 34 3 

Jimmycomelately 8 17 1 

Union 56 43 5 

Salmon/Snow 11 18 1 

Mean 25 36 4 

Median 15 34 3 

Anderson 13 34 Extinct 

Big Beef 15 10 Extinct 

Dewatto 55 37 Extinct 

Tahuya 56 39 Extinct 

Mean 35 30 – 

Median 35 36 – *

Puget Sound TRT database, unpublished data, available from N. Sands, Northwest Fisheries Science Center, 

Seattle, WA; N. Lampsakis, Point No Point Treaty Council, Kingston, WA. Pers. commun., 28 March 2003. 

 

71N. Lampsakis, Point No Point Treaty Council, Kingston, WA. Pers. commun., 28 March 2003. 

439 
CHUM SALMON

fisheries in the area, and they have since dropped to an average of 4% (median = 3%; range 

1%–13%) in the most recent 5-year period, 1998–2002 (Table 103). The most intensive harvest 

occurred on Hood Canal summer-run chum salmon during the period 1979–1991, when the total 

exploitation rate on the aggregate of Hood Canal summer-run stocks reached up to 81% in 1989 

(WDFW and PNPTT 2000, 2001) and most recent run reconstruction from N. Lampsakis.72 

During the high harvest years (1979–1991), exploitation rates on the eight extant individual 

summer-run chum salmon populations averaged 47% (median = 44%; range 21%–86%). 

Estimates of hatchery strays to Hood Canal tributaries were made only recently, 

coinciding with the instigation of hatchery programs to supplement summer-run chum salmon 

spawning on some streams. Releases of hatchery fish in the tributaries began in 1992 for the Big 

Quilcene River and Salmon Creek, so estimates of returning adult hatchery fish presently are 

available only for those streams (Table 104). The marking of hatchery-origin fish began recently 

in a number of streams (fin clips began in Quilcene in 1997, and otolith marks began in 1992 in 

Salmon Creek, 1997 in Lilliwaup and Hamma Hamma, 1998 in Big Beef Creek, 1999 in 

Chimacum and Jimmycomelately creeks, and 2000 in Union River). Therefore, distinguishing 

hatchery-produced from naturally born summer-run chum salmon was not possible in most Hood 

Canal streams until 2001. 

Information on recent releases of hatchery juvenile summer-run chum salmon into Hood 

Canal streams is reported in Table 105. Average annual juvenile summer-run chum salmon 

releases in streams receiving hatchery fish ranged from 15,000 to 320,000 (average = 92,000) 

juveniles per year between 1993 and 2001. SSHAG identified all hatchery stocks of Hood Canal 

summer-run chum salmon as category 1a or 1b (Appendix E, Table E-1). 

Table 104. Average estimated annual returns of hatchery summer-run chum salmon to the spawning 

grounds of extant populations of summer-run chum salmon in Hood Canal. Source: WDFW and 

PNPTT (2000, 2001); Puget Sound TRT, unpublished data, available from N. Sands, Northwest 

Fisheries Science Center, Seattle, WA 98119. 

Year supplementation 

program started with 

Population broodstock takes 

Average annual hatchery 

return to stream 

(minimum–maximum) 

Hatchery 

return years

Big/Little Quilcene 1992 941 (241–1619) 1995–2002 

Dosewallips None NA 

Duckabush None NA 

Hamma Hamma 1998 NA 

Jimmycomelately 1999 NA 

Lilliwaup 1992 NA 

Salmon/Snow 1992 78 (2–319)* 1995–2002 

Union 2000 NA 

*

 Estimated from Salmon Creek only. 

 

72See Footnote 71. 

440 
37. HOOD CANAL SUMMER-RUN CHUM SALMON ESU 

Table 105. Numbers of hatchery-origin juvenile summer-run chum salmon released into Hood Canal 

streams, 1993–2001. Source: Waknitz (2002). 

Watershed Years Hatchery/stock Release site Total 

Annual 

mean 

Salmon Creek 1995–2001 Salmon Creek/Salmon Creek Salmon Creek 366,743 52,391

Jimmycomelately 

Creek 

2000–2001 Jimmycomelately 

Creek/Jimmycomelately Creek 

Jimmycomelately 

Creek 

29,780 14,890

Chimacum Creek 1999–2001 Chimacum Creek/Salmon Creek Chimacum Creek 248,148 82,716

Big Quilcene 

River 

1993–2001 Quilcene National Fish 

Hatchery/Big Quilcene River 

Big Quilcene 

River 

2,918,878 324,319

Hamma Hamma 

River 

1998–2001 Hood Canal/Hamma Hamma John Creek 121,000 30,250

Lilliwaup Creek 1995–1997 Long Live the Kings, Lilliwaup/ 

Lilliwaup Creek 

Lilliwaup Creek 93,600 31,200

Big Beef Creek 1997–2001 Big Beef Creek/Big Quilcene 

River 

Big Beef Creek 621,332 124,266

Union River 2001 Hood Canal/Union River Union River 75,876 75,876

Additional potential threats to Hood Canal summer-run chum salmon include negative 

interactions with hatchery fish (fall-run Chinook, coho, pink, and fall-run chum salmon) through 

predation, competition and behavior modification, or disease transfer. The Hood Canal SummerRun Chum Salmon Conservation Initiative reports annually on the predicted risks associated 

with each of the hatchery species on summer-run chum salmon (WDFW and PNPTT 2000, 

2001). In the original report, the comanagers summarized what they considered to be the most 

important historical factors for decline for Hood Canal summer-run chum salmon (Table 106). 

Specific mitigation measures were identified for those hatchery programs deemed to pose a risk 

to summer-run chum salmon, and most of the mitigation measures had been implemented by 

2000. In addition, some programs were discontinued. 

Marine mammal predation on summer-run chum salmon in Hood Canal has been 

monitored by the Washington Department of Fish and Wildlife (WDFW) since 1998. The most 

recent results from these studies estimate that a few harbor seals are killing hundreds of summerrun chum salmon each year (WDFW and PNPTT 2001). Estimates of seal predation ranged 

from 2% to 29% of the summer-run chum salmon returning to each river annually. 

New activities related to mitigating and improving degraded habitat quality in Hood 

Canal are reported in the Supplemental Report No. 3 under the comanagers’ Summer-Run Chum 

Salmon Conservation Initiative (WDFW and PNPTT 2001). Such activities include new 

shoreline management rules issued by Washington Department of Ecology (but no resulting 

change in shoreline master programs yet), Jefferson County improved some development codes 

under the Growth Management Act, Clallam County provided limited improvements in 

upgrading its Critical Areas Ordinance in 1999, and Washington State Salmon Recovery 

441 
CHUM SALMON

Funding Board has funded several habitat improvement projects. The BRT did not attempt to 

estimate the collective impacts of these projects on the status of Hood Canal summer-run chum 

salmon. 

Table 106. Impact ratings of regionwide historical factors for decline of summer-run chum salmon in 

Hood Canal and Strait of Juan de Fuca streams. Source: Impact ratings from WDFW and 

PNPTT (2000).

Factor Hood Canal Strait of Juan de Fuca 

Climate Ocean conditions Undetermined Undetermined

Estuarine conditions Undetermined Undetermined

Freshwater conditions Moderate Major

Ecological 

interactions 

Wild fall-run chum salmon Low or not likely Low or not likely

Hatchery fall-run chum salmon Low or not likely Low or not likely

Other salmonids (including 

hatchery) 

Moderate Low or not likely

Marine fish Low or not likely Low or not likely

Birds Low or not likely Low or not likely

Marine mammals Low or not likely Low or not likely

Habitat Cumulative impacts Major Major

Harvest Canadian preterminal catch Low or not likely Moderate

U.S. preterminal catch Low or not likely Low or not likely

Terminal catch Major Low or not likely

442 
38. Columbia River Chum Salmon ESU 

Summary of Previous BRT Conclusions 

NMFS last provided an updated status report on the Columbia River chum salmon ESU 

in 1999 (NMFS 1999g). As documented in the 1999 report, the previous BRT was concerned 

about the dramatic declines in abundance and contraction in distribution from historical levels. 

The previous BRT was also concerned about the low productivity of the extant populations, as 

evidenced by flat trend lines at low population sizes. A majority of the previous BRT concluded 

that the Columbia River chum salmon ESU was likely to become endangered in the foreseeable 

future, and a minority concluded that the ESU was currently in danger of extinction. 

Listing status: Threatened. 

New Data and Updated Analyses 

New data include spawner abundance through 2000, with a preliminary estimate for 

2002, new information on the hatchery program, and new genetic data describing the current 

relationship of spawning groups. New analyses include designation of relatively 

demographically independent populations, recalculation of previous BRT metrics with additional 

years’ data, estimates of median annual growth rate (λ), and estimates of current and historically 

available stream kilometers. 

Results of New Analyses 

Historical population structure 

As part of its effort to develop viability criteria for Columbia River ESU chum salmon, 

the WLC-TRT identified historical demographically independent populations (Myers et al. 

2002). Population boundaries are based on the definition of VSPs developed by McElhany et al. 

2000. Myers et al. (2002) hypothesized that the ESU historically consisted of 16 populations 

(Figure 242). These populations are the units used for the new analyses in this report. 

The WLC-TRT partitioned Columbia River chum salmon populations into a number of 

strata based on ecological zones (McElhany et al. 2002). The WLC-TRT analysis suggests that a 

viable ESU would need multiple viable populations in each stratum. The strata and associated 

chum salmon populations are identified in Table 107. 

443 
CHUM SALMON

 Figure 242. Historical chum salmon populations in the Columbia River chum salmon ESU. This map 

does not reflect the most recent modification of the population designation, which merged Grays 

River and Chinook River chum salmon into a single population for a total of 16 populations 

(Myers et al. 2002). 

Abundance, Distribution, and Trends 

Chum salmon in the Columbia River once numbered in the hundreds of thousands of 

adults, and at times approached a million per year (Figure 243). The total number of chum 

salmon returning to the Columbia River in the last 50 years averaged perhaps a few thousand per 

year, returning to a very restricted subset of the historical range (Table 108 and Figures 243 and 

244). The status of individual populations is discussed below. References for abundance time 

series and related data are in Appendix E, Table E-2. Significant spawning occurs in only 2 of 

the 16 historical populations, meaning that 88% of the historical populations are extirpated, or 

nearly so. The two extant populations are at Grays River and the lower Columbia Gorge 

(Figure 243). The status of individual populations and groups of populations are discussed 

below. 

444 
38. COLUMBIA RIVER CHUM SALMON ESU 

Table 107. Historical population structure of Columbia River chum salmon. The populations are 

portioned into ecological zones, which are based on ecological community and hydrodynamic 

patterns. 

Ecological zone Population 

EDT estimate of 

historical 

abundancea

Youngs Bay ndb

Grays River 7,511 

Big Creek nd 

Elochoman River nd 

Clatskanie River nd 

Mill, Abernathy, Germany creeks nd 

Coastal 

Scappoose Creek nd 

Cowlitz River 141,582 

Kalama River 9,953 

Lewis River 89,671 

Salmon Creek nd 

Clackamas River nd 

Sandy River nd 

Cascade 

Washougal River 15,140 

Columbia Gorge Lower gorge tributaries >3,141 

Upper gorge tributaries >8,912 

Total >283,421 a

 The EDT estimate of historical abundance is based on analysis by WDFW of 

equilibrium abundance under historical habitat conditions (Busack and Rawding 2003). 

b

 nd = no data.

Table 108. Recent abundance estimates for lower Columbia Gorge and two Grays River chum salmon 

populations. The majority of Columbia River chum salmon spawn as part of these populations. 

Population 

Years for 

recent means 

Recent geometric 

mean 

Recent 

arithmetic mean 

Grays River*

Rawding estimate 1994–1998 704 812 

Hymer estimate 1996–2000 331 576 

Lower Columbia Gorge 1996–2000 425 490 *

 Two different time series estimates are available for the Grays River population, Rawding (2001c) and Hymer 

(2000). 

445 
CHUM SALMON

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

800,000

900,000

1,000,000

1904190919141919192419291934193919441949195419591964196919741979198419891994

Year

Run size

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Harvest rate

Escapement Catch Harvest rate

Figure 243. Columbia River chum salmon returns, 1904–1994. 

Figure 244. Extant Columbia River chum salmon populations. 

446 
38. COLUMBIA RIVER CHUM SALMON ESU 

Grays River 

The majority of chum salmon spawning in the Grays River currently occurs in less than 

1.1 km of the river. Prior to its destruction in a 1998 flood, approximately 50% of the Grays 

River population spawning occurred in an artificial spawning channel created by WDFW in 

1986. Two time series of abundance were available for the Grays River chum salmon population 

(Tables 109 and 110 and Figures 245 and 246). One data set by Hymer (2000) covers the years 

1944–2000. The other data set covers 1967–1998; it was provided by Dan Rawding of WDFW 

(Rawding 2001c) to correct some perceived errors in the expansions used in the Hymer (2000) 

data set. The Rawding estimates are believed to be more accurate, but both data sets are 

included in this report because the Hymer series includes estimates both earlier and more recent 

than the Rawding data set. The Rawding data set shows a small upward trend (λ) from 1967 to 

1998 (Table 109), and a low probability that the population is declining (Table 110). However, 

the longer Hymer data set indicates that both long- and short-term trends are negative over the 

period 1950–2000, with a high probability that the trend and λ values are less than one. The 

Rawding data were insufficient to estimate the short-term trend (i.e., since 1990). 

Table 109. Trend and growth rate for a Lower Columbia Gorge and two Grays River chum salmon 

populations (95% confidence intervals are in parentheses). 

Long terma Short termb

Population 

Years of time 

series 

Median growth 

rate (λc

) 

Median growth 

rate (λc

) 

Trend in 

abundance 

Trend in 

abundance 

Grays Riverd

Rawding 

estimate 

1967–1998 1.058 

(1.021–1.096) 

1.043 

(0.957–1.137) 

Not enough data Not enough data

Hymer estimate 1951–2000 0.990 

(0.965–1.016) 

0.954 

(0.855–1.064) 

0.904 

(0.661–1.235) 

0.807 

(0.723–0.900) 

Lower Columbia 

Gorge 

1950–2000 0.979 

(0.961–0.997) 

0.984 

(0.883–1.096) 

1.003 

(0.882–1.141) 

1.001 

(0.899–1.116) a The long-term analysis used the entire data set (see Table 74 for years). 

b Short-term data sets include data from 1990 to the most recent available year. 

c The λ calculation is an estimate of what the natural growth rate would have been after accounting for hatcheryorigin spawners. 

d Two different time series estimates are available for the Grays River population, Rawding (2001c) and Hymer 

(2000). 

447 
CHUM SALMON

Table 110. Probability that the abundance trend or growth rate of Columbia River chum salmon is less 

than 1. 

Long term Short term 

Population Years of 

time series 

Probability 

λ < 1a

Probability 

λ < 1a

Probability 

trend < 1 

Probability 

trend < 1 

Grays Riverb

Rawding estimate 1967–1998 0.001 0.197 Not enough data Not enough data

Hymer estimate 1951–2000 0.776 0.774 0.759 0.934 

Lower Columbia Gorge 1950–2000 0.987 0.657 0.478 0.494 a The λ calculation is an estimate of what the natural growth rate would have been after accounting for hatcheryorigin spawners. 

b

 Two different time series estimates are available for the Grays River population, Rawding (2001c) and Hymer 

(2000). 

Final abundance estimates for 2002 were also not available, but preliminary estimates 

were received.73 The preliminary estimates suggest a substantial increase in abundance in 2002 

over what was observed over the last 50 years. Survey crews handled over 7,000 chum salmon 

carcasses in the Grays River in 2002, but the total population size is in the neighborhood of 

10,000 adults (Figure 245). However, a new chum salmon hatchery program in the Grays River 

that started in 1999 confounds the abundance estimates because hatchery returns are included in 

the 10,000-adult estimate. The hatchery fish were otolith marked, so it will be possible to 

determine the fraction of hatchery-origin spawners once the otoliths are read; however, that 

information is not available at this time. The Chinook River population, a subpopulation of the 

Grays River population, had essentially no chum salmon in recent years until hatchery fish 

returned in 2002. In 2002, a preliminary estimate of 600 chum salmon returned to the Chinook 

River, suggesting a 1% return of 3-year-olds from the hatchery fish. Potential causes of this 

increase in 2002 are discussed below. No estimates of 2001 abundance were available from 

WDFW at the time of this report, although the run was described as “large, though not as large as 

2002.” 

Lower Columbia Gorge population 

The lower Columbia Gorge population consists of a number of subpopulations 

immediately below Bonneville Dam. The subpopulations include Hardy Creek, Hamilton Creek, 

Ives Island, and the Multnomah area. Both the Ives Island and Multnomah area subpopulations 

spawn in the Columbia main stem. The time series used for analysis of the lower Columbia 

Gorge population is based on summing the abundance in Hardy Creek, Hamilton Creek, and the 

artificial spawning channel in Hamilton Creek (Tables 107–109, Figures 247–248). There is 

some question about whether or not these data provided a representative index of the population, 

because it does not include the mainstem spawning areas. Depending on flow conditions, chum 

salmon may alternate between the tributaries and the main stem, causing counts in only a subset 

 

73See Footnote 9. 

448 
38. COLUMBIA RIVER CHUM SALMON ESU 

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

10,000

11,000

1940 1950 1960 1970 1980 1990 2000 2010

Year

Abundance

Hymer Rawding Preliminary 2002

Figure 245. Grays River chum salmon abundance estimates, 1945–2000. The two data sets (Rawding, 

2001c, and Hymer, 2000) use different information and expansions to estimate the Grays River 

chum salmon abundance. The 2002 data are preliminary and include an unknown number of 

hatchery-origin spawners. Source: D. Rawding, Washington Department of Fish and Wildlife, 

Vancouver. 

0

500

1,000

1,500

2,000

2,500

1965 1970 1975 1980 1985 1990 1995 2000

Year

Abundance

Preharvest recruits Spawners

Figure 246. Grays River chum salmon recruits and spawners, 1966–1998. Source: Based on a data set 

provided by D. Rawding, Washington Department of Fish and Wildlife, Region 5, 2108 Grand 

Ave., Vancouver (2002; see Appendix E, Table E-2). 

449 
CHUM SALMON

0

500

1000

1500

2000

2500

1940 1950 1960 1970 1980 1990 2000

Year

Abundance

Figure 247. Hamilton and Hardy creeks (lower Columbia Gorge population) chum salmon spawner 

abundance, 1944–2000. 

0

500

1000

1500

2000

2500

3000

1940 1950 1960 1970 1980 1990 2000

Year

Abundance

Recruits Spawners

Figure 248. Hamilton and Hardy creeks (lower Columbia Gorge population) chum salmon recruits and 

spawners, 1950–2000. 

450 
38. COLUMBIA RIVER CHUM SALMON ESU 

of the population to act as poor indicators of total population abundance in any given year. 

Based on these data, the population showed a downward trend since the 1950s and was at 

relatively low abundance up to 2000. However, preliminary data indicate that the 2002 

abundance showed a substantial increase, estimated to be more than 2,000 chum salmon in 

Hamilton and Hardy creeks, plus another 8,000 or more in the main stem. There have been no 

hatchery releases in the lower gorge population, so hatcheries are not responsible for this 2002 

increase, unless there was long distance straying from Grays River (>100 km). Potential causes 

of the 2002 increase are discussed below. No estimate of 2001 abundance was available from 

WDFW at the time of this report, although the run was described as “large, though not as large 

as 2002.” 

Washougal River population 

Chum salmon were observed within the last 3–4 years spawning in the mainstem Columbia 

River on the Washington side, near the I-205 bridge (at Woods Landing and Rivershore). These 

spawners would be considered part of the WLC-TRT’s Washougal population, the nearest 

tributary mouth, but whether this population is recently established or only recently discovered 

by WDFW is not clear. Genetic analysis indicates that the fish currently spawning in this area 

are more closely related to fish in the lower Columbia Gorge than to fish in Grays River 

(Marshall 2001). In 2000, WDFW estimated 354 spawners at this location (Figure 249). As 

with the two other Columbia River chum salmon spawning populations, preliminary data 

indicate a dramatic increase in 2002. Preliminary estimates of this population for 2002 put its 

abundance in the range of several thousand spawners. 

0

50

100

150

200

250

300

350

400

Abernathy

Ashes Lake

Bonneville Dam

Cameron

Carson Creek

Coal Creek

CowlitzCowlitz

Crooked Creek

Dog Creek

Duncan Creek

EF Lewis

ElochomanElochoman

Germany

Good Bear

I-205

Jim Crow

Kalama

Kanaka Creek

Klintz

LaCamas

Lawton Creek

Mill Creek

Nelson Creek

NF Lewis

Rock Creek

Salmon Creek

Skamakawa

Smith Creek

St Cloud

Washougal

Wind

Woodard

Sample Location

Fish Observed

Figure 249. Abundance of chum salmon observed in 2000 Pacific States Marine Fisheries Commission 

surveys. 

451 
CHUM SALMON

Upper Columbia Gorge population 

A large portion of the upper gorge population chum salmon habitat is believed to have 

been inundated by Bonneville Dam. However, small numbers of chum salmon still pass 

Bonneville Dam (Figure 250). The number of fish passing the dam showed some increase in 

2002, but not the dramatic increases estimated in the other three populations. 

Other Washington populations 

In 2000, the Pacific States Marine Fisheries Commission conducted a study to determine 

the distribution and abundance of chum salmon on the Washington side of the Columbia River. 

The results of that survey are shown in Figure 249.74 Very small numbers of chum salmon were 

observed in several locations. However, with the possible exception of the Washougal River 

mainstem (I-205) population (discussed above), none is considered close to self-sustaining 

abundance. 

Oregon populations 

Chum salmon spawn on the Oregon side of the lower Columbia Gorge (Multnomah area), 

but appear to be essentially absent from other populations in the Oregon portion of the Columbia 

River chum salmon ESU. In 2000, ODFW conducted surveys with a similar purpose to the 

WDFW 2000 surveys (i.e., to determine the abundance and distribution of chum salmon in the 

Columbia). Out of 30 sites surveyed, only one chum salmon was observed. With the exception 

of the lower Columbia Gorge population, Columbia River chum salmon are considered 

extirpated, or nearly so, in Oregon. 

0

10

20

30

40

50

60

70

80

1990 1992 1994 1996 1998 2000 2002 2004

Year

Fish count

Figure 250. Adult chum salmon passing Bonneville Dam, 1992–2002. 

 

74Pers. commun. from Lynne Krasnow, Northwest Fisheries Science Center, Portland, OR, to P. McElhany, 1 March 

2002. Data available from P. McElhany, NWFSC, 2725 Montlake Blvd. E., Seattle, WA 98112. 

452 
38. COLUMBIA RIVER CHUM SALMON ESU 

Reasons for 2002 Increase in Abundance 

It is not known why Columbia River chum salmon dramatically increased in abundance 

in 2002. As of the writing of this memo, the run had just ended and firm abundance estimates 

were not available. However, several hypotheses were floated regarding this increase, including: 

• improved ocean conditions, 

• Grays River and Chinook River hatchery programs, 

• Columbia River mainstem flow agreements (the lower Columbia Gorge population is in 

the tailrace of Bonneville Dam and subject to hydrosystem induced flow fluctuations), 

• favorable freshwater conditions, and 

• increased sampling effort (since the 2000 survey, effort seems to have increased, though 

this alone certainly does not explain the apparent increase). 

These factors are all possible contributors to the increase, but the reason for the increase 

is not known. Similarly, why chum salmon were restricted to low abundance and limited 

distribution for the last 50 years is also not known. It did not appear in 2002 that chum salmon 

had expanded their range beyond the Grays River, lower Columbia Gorge, and I-205 areas, 

though not all the 2002 survey data had been reported. Because the cause of the 2002 increase is 

unknown, it is impossible to know whether it will continue. The 2002 increase in Columbia 

River chum parallels a recent increase in Puget Sound chum. It is not known whether the 

reasons for the increase in the two regions are the same. 

EDT-Based Estimates of Historical Abundance 

The WDFW conducted analyses of Columbia River chum salmon populations using the 

EDT model (http://www.olympus.net/community/dungenesswc/EDT-primer.pdf), which 

attempts to predict fish population performance based on information about reach-specific 

habitat attributes. WDFW populated this model with estimates of historical habitat conditions, 

which produced the estimates of average historical abundance shown in Table 107. There is a 

great deal of unquantified uncertainty in the EDT historical abundance estimates, and this 

uncertainty should be considered when interpreting these data. In addition, the habitat scenarios 

evaluated as historical may not reflect historical distributions, because some areas that were 

accessible historically but now are blocked by large dams were omitted from the analyses, and 

some areas that were historically inaccessible but now made passable by human intervention are 

included. The EDT outputs are provided here to give a sense of the historical abundance of 

populations relative to each other and an estimate of the historical abundance relative to the 

current abundance. 

453 
CHUM SALMON

Table 111. Loss of habitat from barriers for the Columbia River chum salmon ESU. 

Population 

Potential current 

habitat (%)a

Potential historical 

habitat (km)b

Current to historical 

habitat ratioc

Youngs Bay 269 287 94 

Grays Riverd 229 230 100 

Grays Rivere 229 230 100 

Big Creek 369 407 91 

Elochoman River 242 242 100 

Clatskanie River 160 165 97 

Mill, Abernathy, Germany creeks 266 306 87 

Scappoose Creek 888 1,048 85 

Cowlitz River 114 120 95 

Kalama River 382 579 66 

Lewis River 319 362 88 

Salmon Creek 416 471 88 

Clackamas River 148 194 76 

Sandy River 125 240 52 

Washougal River 81 82 99 

Lower Columbia Gorge tributaries 55 77 71 

Upper Columbia Gorge tributaries NA NA NA 

Total 4,292 5,040 85 a The potential current habitat is the kilometers of stream below all currently impassable barriers between a gradient 

of 0% and 3.5%. 

b

 The potential historical habitat is the kilometers of stream below historically impassable barriers with a gradient of 

between 0% and 3.5%. 

c

 The current:historical habitat ratio is the percent of the historical habitat that is currently available. This table does 

not consider habitat quality. 

d

 Hymer (2000). 

e

 Rawding (2001c). 

Loss of Habitat from Barriers 

Steel and Sheer (2003) assessed the number of stream kilometers historically and 

currently available to salmon populations in the lower Columbia River (Table 111). Stream 

kilometers usable by salmon are determined based on simple gradient cutoffs and the presence of 

impassable barriers. This approach overestimates the number of usable stream kilometers, 

because it does not take into consideration habitat quality (other than gradient). This is likely 

especially true of chum salmon, which seem to prefer particular microhabitats for spawning. 

New ESU Information 

Updated information in this report, the information contained in previous lower Columbia 

River status reviews, and preliminary WLC-TRT analyses suggest that 14 of the 16 historical 

populations (88%) are extinct or nearly so. The two extant populations have been at low 

abundance for the last 50 years in the range where stochastic processes could lead to extinction. 

Encouragingly, the abundance of these two populations has substantially increased. In addition, 

454 
38. COLUMBIA RIVER CHUM SALMON ESU 

there are new (or newly discovered) Washougal River mainstem spawning groups. However, 

whether the increase will continue and whether the abundance is still substantially below the 

historical levels are not known.

455 
39. Chum Salmon BRT Conclusions 

Hood Canal Summer-Run Chum Salmon ESU 

Most of the BRT votes for the Hood Canal summer-run chum salmon ESU fell in the 

“likely to become endangered” category (74%), with a minority in the “danger of extinction” 

category (21%) and the balance in the “not likely to become endangered” category (Table 112). 

Mean risk matrix scores were moderately high (3.4–3.7) for each VSP element (Table 113), 

reflecting ongoing BRT concerns for the major risks identified in previous assessments. An 

estimated 7 of 16 historical populations in this ESU have been extirpated, with most of the 

population losses occurring on the eastern side of Hood Canal. Although many of the remaining 

populations remain at very depressed levels, adult returns in a number of streams increased in 

2000–2002. Harvest rates are reduced considerably from their peaks in the 1980s, which should 

facilitate recovery if other limiting factors are addressed. The BRT felt that the joint state and 

tribal Summer Chum Salmon Conservation Initiative represented a positive step toward recovery 

of the Hood Canal ESU. However, although the initiative includes guidelines for habitat 

restoration, implementation of habitat actions is largely outside its jurisdiction. In particular, the 

BRT remains concerned that widespread loss of estuary and lower floodplain habitat is an 

ongoing risk factor for this ESU. A number of supplementation programs have been initiated in 

recent years to help boost abundance of local populations. Although these programs may help 

Table 112. FEMAT votes regarding status of the Hood Canal summer-run and Columbia River chum 

salmon ESUs. Thirteen BRT members allocated 10 points among the three status categories for 

the Columbia River population, 12 members for Hood Canal. 

ESU Danger of extinction Likely to become 

endangered 

Not likely to become 

endangered 

Hood Canal summer-run 25 89 6 

Columbia River 44 82 4 

Table 113. Summary of risk scores (1 = low to 5 = high) for four viable salmonid population categories*

for the Hood Canal summer-run and Columbia River chum salmon ESUs. Data presented are 

means (range). 

ESU Abundance 

Growth 

rate/productivity 

Spatial structure and 

connectivity Diversity 

Hood Canal summer-run 3.7 (3–4) 3.4 (2–4) 3.7 (3–5) 3.5 (2–4) 

Columbia River 3.6 (3–4) 3.5 (2–4) 4.4 (4–5) 3.8 (3–5) *

See subsection, Factors Considered in Status Assessments, for a description of the risk categories. 

456 
39. CHUM SALMON BRT CONCLUSIONS

speed recovery of existing populations or reseed vacant habitat, the BRT found it difficult to 

assess the current effects of these programs because of the inability to distinguish most hatchery 

and wild fish. More intensive marking programs have been implemented recently, which should 

make it easier to monitor natural production of summer-run chum salmon in the future. 

Columbia River Chum Salmon ESU 

Nearly all votes for the Columbia River chum salmon ESU fell in the “likely to become 

endangered” (63%) or “danger of extinction” (34%) categories (Table 112). The BRT had 

substantial concerns about every VSP element, as indicated by mean risk matrix scores that 

ranged from 3.5 for growth rate/productivity to 4.4 for spatial structure (Table 113). Most or all 

risk factors the BRT previously identified remain important concerns. The WLC-TRT estimated 

that close to 90% of this ESU’s historical populations are extinct or nearly so, resulting in loss of 

much diversity and connectivity between populations. The populations that remain are small, 

and overall abundance for the ESU is low. This ESU has shown low productivity for many 

decades, even though the remaining populations are at low abundance and density-dependent 

compensation might be expected. The BRT was encouraged that unofficial reports for 2002 

suggest a large increase in abundance in some (perhaps many) locations. Whether this large 

increase is due to any recent management actions or simply reflects unusually good conditions in 

the marine environment is not known at this time, but the result is encouraging, particularly if it 

were to be sustained for a number of years.

457 
REFERENCES AND APPENDICES

458
REFERENCES AND APPENDICES

459
 

460
 

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512
 

Appendix A: Chinook Salmon 

Table A-1. SSHAG (2003) categorizations of hatchery stocks of the nine Chinook salmon ESUs 

reviewed. 

ESU/Stock Run Basin SSHAG category*

Snake River fall run 

Lyons Ferry Hatchery Fall Snake 2a 

Snake River spring/summer run 

McCall (supplementation) Spring Salmon 1a 

McCall (production) Spring Salmon 2a 

Rapid River Spring Little Salmon 3c 

Sawtooth Spring Salmon 1a 

Pahsimeroi Summer Salmon 1a and 2a 

Captive broodstock 

Catherine Creek Summer Grande Ronde 1a 

Upper Grande Ronde Summer Grande Ronde 1a 

Lostine River Summer Grande Ronde 1a 

Clearwater Spring Clearwater 2b 

Imnaha (#29) Spring/summer Imnaha 1a 

Dworshak Spring Clearwater 3b or 4 

Kooskia Spring Clearwater 3b or 4 

Tucannon Spring Tucannon 1a 

Upper Columbia River spring run 

Leavenworth National Fish Hatchery Spring Wenatchee 3c or 4 

Entiat National Fish Hatchery Spring Entiat 3c, 4, or 2b 

Winthrop National Fish Hatchery Spring Methow 3c or 4 

Chiwawa Spring Wenatchee 1a 

Methow composite Spring Methow 2a/c 

Twisp Spring Methow 1a 

Chewuch Spring Methow 1a 

Methow Spring Methow 3c or 4 

Upper Columbia River captive 

Nason Spring Wenatchee 1a 

White River Spring Wenatchee 1a 

Twisp Spring Methow 1a 

Methow Spring Methow 1a 

Ringold Hatchery Spring Upper Columbia River 3c or 4 

Carson Hatchery Spring Wind 3c or 4 

Puget Sound 

Kendall Creek Spring Nooksack 2a 

Lummi Bay Fall Nooksack 3b or 3c 

Samish River Fall Samish 3b 

513
REFERENCES AND APPENDICES

Table A-1 continued. SSHAG (2003) categorizations of hatchery stocks of the nine Chinook salmon 

ESUs reviewed. 

Stock Run Basin SSHAG category*

Puget Sound (continued) 

Marblemount Spring Skagit 2c 

Marblemount Summer Skagit 1a 

Marblemount Fall Skagit 1a 

Tulalip Spring Tulalip Bay 3b or 3c 

Tulalip Summer Tulalip Bay 2b or 2c 

Tulalip Fall Tulalip Bay 3b or 3c 

North Fork Stillaguamish Summer Stillaguamish 1a 

Wallace River Summer Snohomish 2a 

Issaquah Hatchery Fall Lake Washington 2b 

University of Washington Portage Bay Fall Lake Washington 3b or 4 

Soos Creek Fall Green 2a 

Keta Creek Fall Green 2a 

Grover’s Creek Fall East Kitsap 2b 

Garrison Springs Fall Chambers Creek 2b 

Voights Creek Fall Puyallup 2b or 2c 

Diru Creek Fall Puyallup 2b or 2c 

White River Spring Puyallup 2a 

Clear/Kalama creeks Fall Nisqually 2a or 2b 

Minter Creek Fall South Sound 2b 

Tumwater Falls Fall Deschutes 2b 

George Adams Fall Skokomish 2b or 3c 

WSC Hood Canal Fall Skokomish 2b or 3c 

Finch Creek Fall South Hood Canal 2b or 3c 

Hamma Hamma Fall South Hood Canal 2b or 3c 

Big Beef Creek Fall North Hood Canal 2b 

Dungeness Spring Dungeness 1a 

Elwha Fall Elwha 2a 

Glenwood Springs Fall San Juan Islands 2b 

Lower Columbia River 

Sea Resources Fall Chinook River 2b 

Abernathy National Fish Hatchery Fall Abernathy Creek 2b 

Grays River Fall Grays 2b 

Elochoman Fall Elochoman 2b 

Cowlitz Fall Cowlitz 2a 

Cowlitz Spring Cowlitz 2a 

Toutle Spring Cowlitz 2c 

Kalama Fall Kalama 2a 

Kalama Spring Kalama 2b 

Lewis Spring Lewis 2a or 2b 

Washougal Fall Washougal 2a or 2b 

Carson Spring Wind 4 

Little White Salmon Fish Hatchery Fall Little White 4 

514
APPENDIX A 

Table A-1 continued. SSHAG (2003) categorizations of hatchery stocks of the nine Chinook salmon 

ESUs reviewed. 

Stock Run Basin SSHAG category*

Spring Creek National Fish Hatchery Fall Spring Creek 2a 

Klickitat Fall Klickitat 4 

Willamette Spring Youngs Bay 4 

Big Creek Fall Big Creek 3b 

Rogue River (#52) Fall Youngs Bay 4 

Klaskanine (#15) Fall Klaskanine 2b 

Willamette Spring Klaskanine 4 

Bonneville (#14) Fall Gorge 3a 

Bonneville (#95) Fall Gorge 4 

Hood River Spring Hood 4 

Upper Willamette River 

North Fork Santiam (#21) Spring Santiam 2a and 2b 

Willamette Hatchery (#22) Spring Middle Fork 

Willamette 

2b or 2c 

McKenzie (#24) Spring McKenzie 2a 

South Fork Santiam (#23) Spring Santiam 2b 

Clackamas (#19) Spring Clackamas 2b or 2c 

California Coastal 

Mad River Fall Mad River 2q,b,c 

Freshwater Creek Fall Humboldt Bay 1a 

Yaeger Creek Fall Van Duzen 1a 

Redwood Creek Fall Redwood Creek 1a 

Hollow Tree Creek Fall Eel River 1a 

Van Arsdale Fall Eel River 2a 

Mattole Fall Mattole River 1a 

Sacramento River winter run 

Livingston Stone National Fish Hatchery Winter Sacramento River 1a 

California Central Valley spring run 

Feather River Spring Feather River 4 or 2b 

*

See the subsection, Artificial Propagation, in Section 1, Introduction, for an explanation of the categories. 

515
REFERENCES AND APPENDICES

Table A-2. Chinook salmon time-series data sources. 

Data type Data source 

Snake River Fall-Run Chinook Salmon ESU 

Population Snake River fall run 

Years of data, length of series 1975–2001, 27 years 

Abundance type Dam count 

Abundance, hatchery, harvest, 

age notes, reference 

Used run reconstructions spreadsheet to update PATH 

data set. Yuen (2002), Marmorek et al. (1998). 

Snake River Spring/Summer-Run Chinook Salmon ESU 

Population Snake River spring-run total 

Years of data, length of series 1979–2001, 23 years 

Abundance type Dam count 

Abundance and hatchery reference Beamesderfer et al. (1998); recent years from Yuen (2002). 

Harvest reference Yuen (2002) 

Age notes, reference Average from Beamesderfer et al. (1998). 

Population Snake River summer-run total 

Years of data, length of series 1979–2001, 23 years 

Abundance type Dam count 

Abundance and hatchery notes, 

reference 

Beamesderfer et al. (1998); recent years from Yuen (2002) 

Harvest reference Yuen (2002) 

Age notes, reference Yearly data from Beamesderfer et al. (1998); recent years 

updated with an average. 

Population Alturas Lake Creek 

Years of data, length of series 1957–2001, 45 years 

Abundance type, notes, reference Redd count. Elms-Cockrum (1998); Kiefer (2002) for years 

1999–2001. 

Harvest notes, reference Regional Analytical Advisory Committee (Northwest Power 

Planning Council) run reconstructions, Ecosystem Diagnosis 

Treatment Validation project. Data summary (compact disk). 

Formula used: Harvest multiplier = 1 – (1 – Columbia River 

harvest rate)/(tributary harvest rate). 

Age notes, reference Aggregate salmon age structure from 

Beamesderfer et al. (1998). 

Population Bear Valley/Elk Creek 

Years of data, length of series 1960–2001, 42 years 

Abundance type, notes, reference Expanded redd count. IDFG updated redd counts from 

Beamesderfer et al. (1998). 

516
APPENDIX A 

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source 

Hatchery reference Beamesderfer et al. (1998) 

Harvest reference Yuen (2002) 

Age notes, reference Used Middle Fork Salmon River composite to fill 

in missing years. Beamesderfer et al. (1998) 

Population Big Creek summer run 

Years of data, length of series 1957–2001, 45 years 

Abundance type, notes, reference Redd count. StreamNet trend no. 40145 

(http://www.streamet.org) for data prior to 1997; Brown 

(2002) for data years 1998–2001. 

Harvest notes, reference Regional Analytical Advisory Committee (Northwest Power 

Planning Council) run reconstructions, Ecosystem Diagnosis 

Treatment Validation project. Data summary (compact disk). 

Formula used: Harvest multiplier = 1 – (1 – Columbia River 

harvest rate)/(tributary harvest rate). 

Age notes, reference Aggregate for Middle Fork age structure 

from Beamesderfer et al. (1998). 

Population Big Sheep Creek 

Years of data, length of series 1957–2001, 39 years 

Abundance type, notes, reference Redd count. StreamNet trend no. 50121 

(http://www.streamnet.org) for data prior to 1997; Keniry 

et al. (2002) for years 1997–2001. 

Hatchery notes, reference Holmes (2002) 

Harvest notes, reference Recent years from Yuen (2002), Beamesderfer et al. (1998). 

Age reference Beamesderfer et al. (1998) 

Population Camas Creek 

Years of data, length of series 1972–2001, 29 years 

Abundance type, notes, reference Redd counts. Kiefer (2002) 

Hatchery reference Holmes (2002) 

Harvest notes, reference Regional Analytical Advisory Committee (Northwest Power 

Planning Council) run reconstructions, Ecosystem Diagnosis 

Treatment Validation project. Data summary (compact disk). 

Formula used: Harvest multiplier = 1 – (1 – Columbia River 

harvest rate)/(tributary harvest rate). 

Age notes, reference Aggregate for Middle Fork age structure 

from Beamesderfer et al. (1998). 

517
REFERENCES AND APPENDICES

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source 

Population Catherine Creek (index area) 

Years of data, length of series 1957–2001, 45 years 

Abundance type, notes, reference Redd count. StreamNet (http://www.streamnet.org) for data 

prior to 1996; Keniry et al. (2002) for 1997–2001. 

Hatchery reference Holmes (2002) 

Harvest notes, reference Beamesderfer et al. (1998); recent years from Yuen (2002). 

Age notes, reference Beamesderfer et al. (1998); used Grande Ronde River 

aggregate to fill in missing years. 

Population Chamberlain Creek 

Years of data, length of series 1952–1997, 22 years 

Abundance type, notes, reference Redds per mile. StreamNet trend no. 41052 

(http://www.streamnet.org). 

Age notes, reference Aggregate Salmon River age structure from 

Beamesderfer et al. (1998). 

Population Grande Ronde River, upper (index area) 

Years of data, length of series 1960–2001, 42 years 

Abundance type, notes, reference Redd count. StreamNet (http://www.streamnet.org) for data 

prior to 1997; Keniry et al. (2002) for 1997–2001. 

Hatchery reference Holmes (2002) 

Harvest reference R. Carmichaela

Age notes, reference Beamesderfer et al. (1998); used Grande Ronde River 

aggregate to fill in missing years. 

Population Herd Creek 

Years of data, length of series 1958–1986, 28 years 

Abundance type, notes, reference Redds per mile. StreamNet trend no. 41018 

(http://www.streamnet.org). 

Harvest notes, reference Regional Analytical Advisory Committee (Northwest Power 

Planning Council) run reconstructions, Ecosystem Diagnosis 

Treatment Validation project. Data summary (compact disk). 

Formula used: Harvest multiplier = 1 – (1 – Columbia River 

harvest rate)/(tributary harvest rate). 

Age notes Valley Creek age estimates (McClure et al. 2003). 

Population Imnaha River 

Years of data, length of series 1953–2001, 49 years 

518
APPENDIX A 

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Abundance type Expanded redd count 

Abundance, hatchery, age reference Beamesderfer et al. (1998) 

Harvest reference R. Carmichaela

Population Johnson Creek 

Years of data, length of series 1957–2001, 45 years 

Abundance type Expanded redd count 

Abundance and hatchery reference Beamesderfer et al. (1998) 

Harvest notes, reference Yuen (2002) 

Age notes, reference Beamesderfer et al. (1998); used South Fork Salmon River 

aggregate data to fill in missing years (McClure et al. 2003). 

Population Lake Creek summer run 

Years of data, length of series 1952–2000, 49 years 

Abundance type, notes, reference Redds per mile. StreamNet trend no. 41059 

(http://www.streamnet.org). 

Hatchery notes, reference Regional Analytical Advisory Committee (Northwest Power 

Planning Council) run reconstructions, Ecosystem Diagnosis 

Treatment Validation project. Compact disk 1. 

Harvest notes, reference Regional Analytical Advisory Committee (Northwest Power 

Planning Council) run reconstructions, Ecosystem Diagnosis 

Treatment Validation project. Data summary (compact disk). 

Formula used: Harvest multiplier = 1 – (1 – Columbia River 

harvest rate)/(tributary harvest rate). 

Age notes, reference Used South Fork Salmon River aggregate data to fill in 

missing years (McClure et al. 2003). 

Population Lemhi River 

Years of data, length of series 1957–2001, 45 years 

Abundance type, notes, reference Redd count. Elms-Cockrum (1998); Kiefer (2002) for 

1999–2001. 

Hatchery, harvest notes reference Regional Analytical Advisory Committee (Northwest Power 

Planning Council) run reconstructions, Ecosystem Diagnosis 

Treatment Validation project. Data summary (compact disk). 

Formula used: Harvest multiplier = 1 – (1 – Columbia River 

harvest rate)/(tributary harvest rate). 

Age notes, reference Kiefer (2002); used a weighted average to fill in missing 

years (McClure et al. 2003). 

Population Lick Creek (Imnaha River) 

Years of data, length of series 1964–2001, 38 years 

519
REFERENCES AND APPENDICES

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Abundance type, notes, reference Redd count. StreamNet trend no. 50123 

(http://www.streamnet.org) for data prior to 1997; Keniry 

et al. (2002) for 1997–2001. 

Hatchery, harvest notes, reference Beamesderfer et al. (1998); recent years from Yuen (2002). 

Age reference Beamesderfer et al. (1998) 

Population Lookingglass Creek 

Years of data, length of series 1957–2001, 44 years 

Abundance type, reference Redd count. StreamNet data (http://www.streamnet.org) 

prior to 1997; Keniry et al. (2002) for 1997–2001. 

Hatchery reference Holmes (2002) 

Age notes, reference Beamesderfer et al. (1998); used Grande Ronde River 

aggregate to fill in missing years. 

Population Loon Creek 

Years of data, length of series 1957–2001, 43 years 

Abundance type, reference Redd count. Elms-Cockrum (1998); Kiefer (2002) 

for years 1999–2001. 

Hatchery notes No annual sampling, assumed natural returns. 

Harvest notes, reference Regional Analytical Advisory Committee (Northwest Power 

Planning Council) run reconstructions, Ecosystem Diagnosis 

Treatment Validation project. Data summary (compact disk). 

Formula used: Harvest multiplier = 1 – (1 – Columbia River 

harvest rate)/(tributary harvest rate). 

Age reference Beamesderfer et al. (1998) 

Population Lostine River (index area) 

Years of data, length of series 1964–2001, 38 years 

Abundance type, reference Redd count. Abundance database reference no. 52 from 

ODFW (1997); Keniry et al. (2002) for 1997–2001. 

Hatchery reference Holmes (2002) 

Harvest notes, reference Beamesderfer et al. (1998); recent years from Yuen (2002). 

Age notes, reference Beamesderfer et al. (1998); used Grande Ronde River 

aggregate to fill in missing years. 

Population Marsh Creek 

Years of data, length of series 1957–2001, 45 years 

Abundance type, reference Total live count. Beamesderfer et al. (1998). 

Hatchery reference Beamesderfer et al. (1998) 

520
APPENDIX A 

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Harvest reference Yuen (2002) 

Age notes, reference Kiefer (2002); used Middle Fork Salmon River 

composite to fill in missing years. 

Population Minam River 

Years of data, length of series 1964–2001, 38 years 

Abundance type, reference Total live count. Beamesderfer et al. (1998). 

Hatchery reference Beamesderfer et al. (1998) 

Harvest reference Data available from Northwest Fisheries Science Center 

Salmonid Database, 2725 Montlake Blvd. E., Seattle, WA 

98112. 

Age notes, reference Beamesderfer et al. (1998); used Grande Ronde River 

aggregate to fill in missing years. 

Population Pahsimeroi River 

Years of data, length of series 1980–2001, 22 years 

Abundance type, reference Total live count. StreamNet trend no. 43002 

(http://www.streamnet.org) for 1980–2000; Rogers (2002) 

for 2001. 

Harvest notes, reference Regional Analytical Advisory Committee (Northwest Power 

Planning Council) run reconstructions, Ecosystem Diagnosis 

Treatment Validation project. Data summary (compact disk). 

Formula used: Harvest multiplier = 1 – (1 – Columbia River 

harvest rate)/(tributary harvest rate). 

Age notes Kiefer (2002); used a weighted average to fill in missing 

years (McClure et al. 2003). 

Population Poverty Flat 

Years of data, length of series 1957–2001, 45 years 

Abundance type, reference Total live count. Beamesderfer et al. (1998). 

Hatchery reference Beamesderfer et al. (1998) 

Harvest notes, reference Yuen (2002) 

Age notes, reference Kiefer (2002); used South Fork Salmon River aggregate to 

fill in missing years. 

Population Rapid River (lower Salmon River) 

Years of data, length of series 1972–2001, 30 years 

Abundance type, reference Redds per mile. StreamNet trend no. 43002 

(http://www.streamnet.org) for 1972–2000; Rogers (2002) 

for year 2001. 

521
REFERENCES AND APPENDICES

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Population East Fork Salmon River summer run 

Years of data, length of series 1957–2001, 45 years 

Abundance type, reference Redds per mile. StreamNet trend no. 41016 

(http://www.streamnet.org). 

Hatchery notes No annual sampling, assumed natural returns. 

Harvest notes, reference Regional Analytical Advisory Committee (Northwest Power 

Planning Council) run reconstructions, Ecosystem Diagnosis 

Treatment Validation project. Data summary (compact disk). 

Formula used: Harvest multiplier = 1 – (1 – Columbia River 

harvest rate)/(tributary harvest rate). 

Age notes, reference Used Poverty Flat summer run from Beamesderfer et al. 

(1998). 

Population South Fork Salmon River summer run 

Years of data, length of series 1957–2001, 45 years 

Abundance type, reference Redd count. Elms-Cockrum (1998); Kiefer (2002) 

for years 1999–2001. 

Hatchery notes, reference Regional Analytical Advisory Committee (Northwest Power 

Planning Council) run reconstructions, Ecosystem Diagnosis 

Treatment Validation project. Compact disk 1. 

Harvest notes, reference Regional Analytical Advisory Committee (Northwest Power 

Planning Council) run reconstructions, Ecosystem Diagnosis 

Treatment Validation project. Data summary (compact disk). 

Formula used: Harvest multiplier = 1 – (1 – Columbia River 

harvest rate)/(tributary harvest rate). 

Age notes, reference C. Petroskyb

Population North Fork Salmon River spring run 

Years of data, length of series 1960–2000, 27 years 

Abundance type, reference Redd count. StreamNet (http://www.streamnet.org) for years 

1996–2000. 

Population Upper Salmon River spring run 

Years of data, length of series 1954–2001, 48 years 

Abundance type, reference Redd count. Elms-Cockrum (1998); Kiefer (2002) for years 

1999–2001. 

Harvest notes, reference Regional Analytical Advisory Committee (Northwest Power 

Planning Council) run reconstructions, Ecosystem Diagnosis 

Treatment Validation project. Data summary (compact disk). 

Formula used: Harvest multiplier = 1 – (1 – Columbia River 

harvest rate)/(tributary harvest rate). 

Age notes, reference C. Petroskyb

522
APPENDIX A 

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Population Upper Salmon River summer run 

Years of data, length of series 1957–1997, 40 years 

Abundance type, reference Redds per mile. StreamNet trend no. 41002 

(http://www.streamnet.org) 

Harvest notes, reference Regional Analytical Advisory Committee (Northwest Power 

Planning Council) run reconstructions, Ecosystem Diagnosis 

Treatment Validation project. Data summary (compact disk). 

Formula used: Harvest multiplier = 1 – (1 – Columbia River 

harvest rate)/(tributary harvest rate). 

Age notes, reference Used Poverty Flat age structure from Beamesderfer et al. 

(1998). 

Population Secesh River summer run 

Years of data, length of series 1957–2001, 45 years 

Abundance type, reference Redd count. Elms-Cockrum (1998); Kiefer (2002) for years 

1999–2001. 

Hatchery notes, reference Regional Analytical Advisory Committee (Northwest Power 

Planning Council) run reconstructions, Ecosystem Diagnosis 

Treatment Validation project. Compact disk 1. 

Harvest notes, reference Regional Analytical Advisory Committee (Northwest Power 

Planning Council) run reconstructions, Ecosystem Diagnosis 

Treatment Validation project. Data summary (compact disk). 

Formula used: Harvest multiplier = 1 – (1 – Columbia River 

harvest rate)/(tributary harvest rate). 

Age notes, reference Kiefer (2002); used South Fork Salmon River aggregate 

to fill in missing years. 

Population Snake River spring run 

Years of data, length of series 1979–2001, 23 years 

Abundance type Total live count 

Abundance, hatchery, harvest reference Yuen (2002) 

Age reference Beamesderfer et al. (1998) 

Population Snake River summer run 

Years of data, length of series 1979–2002, 24 years 

Abundance type, reference Dam count. Pacific Salmon Commission CTC Report 

(2002). 

Hatchery reference Yuen (2002) 

Harvest reference Pacific Salmon Commission CTC Report (2002) 

Age reference Beamesderfer et al. (1998) 

523
REFERENCES AND APPENDICES

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Population Sulphur Creek 

Years of data, length of series 1957–2001, 45 years 

Abundance type, notes, reference Total live count. Kiefer (2002). 

Hatchery reference Beamesderfer et al. (1998) 

Harvest notes, reference Regional Analytical Advisory Committee (Northwest Power 

Planning Council) run reconstructions, Ecosystem Diagnosis 

Treatment Validation project. Data summary (compact disk). 

Formula used: Harvest multiplier = 1 – (1 – Columbia River 

harvest rate)/(tributary harvest rate). 

Age notes, reference IDFG (Kiefer 2002); used Middle Fork Salmon River 

composite to fill in missing years. 

Population Tucannon River 

Years of data, length of series 1979–2001, 23 years 

Abundance type Total live count 

Abundance, hatchery reference NMFS (2003) 

Harvest reference Yuen (2002) 

Age notes, reference 1985–1999 average and 2000 estimate of spring-run Chinook 

salmon age composition from WDFW (Gallinat et al. 2001). 

Population Upper Valley Creek spring run 

Years of data, length of series 1957–2001, 44 years 

Abundance type, reference Redd count. Elms-Cockrum (1998); Kiefer (2002) 

for years 1999–2001. 

Hatchery notes No annual sampling, assumed natural returns. 

Harvest notes, reference Regional Analytical Advisory Committee (Northwest Power 

Planning Council) run reconstructions, Ecosystem Diagnosis 

Treatment Validation project. Data summary (compact disk). 

Formula used: Harvest multiplier = 1 – (1 – Columbia River 

harvest rate)/(tributary harvest rate). 

Age notes, reference IDFG (Kiefer 2002); used Salmon River aggregate to fill in 

missing years. 

Population Upper Valley Creek summer run 

Years of data, length of series 1952–1997, 49 years 

Abundance type, reference Redds per mile. StreamNet trend no. 41009 

(http://www.streamnet.org). 

Population Wallowa River 

Years of data, length of series 1963–2001, 39 years 

524
APPENDIX A 

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Abundance type, notes, reference Redd count. StreamNet trend no. 50119 

(http://www.streamnet.org) for data prior to 1997; Keniry 

et al. (2002) for 1997–2001. 

Hatchery reference R. Carmichaela

Harvest notes, reference Beamesderfer et al. (1998); recent years from Yuen (2002). 

Age notes, reference Used Grande Ronde age structure from Beamesderfer et al. 

(1998) 

Population Wenaha River (index area) 

Years of data, length of series 1963–2001, 39 years 

Abundance type, notes, reference Redd count. StreamNet (http://www.streamnet.org) for data 

prior to 1997; Keniry et al. (2002) for 1997–2001. 

Hatchery notes, reference Used South Fork Wenaha; Holmes (2002) 

Harvest notes, reference Beamesderfer et al. (1998); recent years from Yuen (2002). 

Age notes, reference Used pooled Grande Ronde River age structure values from 

Beamesderfer et al. (1998). 

Population Yankee Fork River summer run 

Years of data, length of series 1960–2001, 42 years 

Abundance type, reference Redd count. Elms-Cockrum (1998) for years 1994–1997; 

Brown (2002) for data years 1998–2001. 

Hatchery notes No annual sampling; assumed natural returns. 

Harvest notes, reference Regional Analytical Advisory Committee (Northwest Power 

Planning Council) run reconstructions, Ecosystem Diagnosis 

Treatment Validation project. Data summary (compact disk). 

Formula used: Harvest multiplier = 1 – (1 – Columbia River 

harvest rate)/(tributary harvest rate). 

Age notes, reference Used Poverty Flat age structure from Beamesderfer et al. 

(1998). 

Population West Fork Yankee Fork spring run 

Years of data, length of series 1960–2001, 41 years 

Abundance type, reference Redd count. StreamNet (http://www.streamnet.org); Brown 

(2002) for data years 1998–2001. 

Harvest notes, reference Regional Analytical Advisory Committee (Northwest Power 

Planning Council) run reconstructions, Ecosystem Diagnosis 

Treatment Validation project. Data summary (compact disk). 

Formula used: Harvest multiplier = 1 – (1 – Columbia River 

harvest rate)/(tributary harvest rate). 

Age notes, reference Used aggregate Salmon River age structure from 

Beamesderfer et al. (1998). 

525
REFERENCES AND APPENDICES

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source 

Upper Columbia River Chinook Salmon ESU 

Population Methow River 

Years of data, length of series 1960–2001, 41 years 

Abundance type, notes, reference Estimated total count. Sum of expanded redd counts by area, 

extended series described in Cooney (2001); 1999–2001 data 

from J. Hubble, Yakama Indian Nation, P.O. Box 151, 

Toppenish, WA 98948. 

Hatchery notes, reference Beamesderfer et al. (1998), Cooney (2001), assumed 

equivalent of 25% of the Winthrop NFH returns strayed into 

natural spawning areas; Yakama Indian Nation carcass 

sampling for recent years. 

Harvest notes, reference Beamesderfer et al. (1998), Yuen (2002). 

Age notes, reference Yearly. Beamesderfer et al. (1998); update data from J. 

Hubble, Yakama Indian Nation, P.O. Box 151, Toppenish, 

WA 98948. 

Population Chewack River 

Years of data, length of series 1960–2001, 40 years 

Abundance type, notes, reference Redd count. Cooney (2001); 1999–2001 data from J. 

Hubble, Yakama Indian Nation, P.O. Box 151, Toppenish, 

WA 98948. 

Hatchery notes, reference Beamesderfer et al. (1998), Cooney (2001) 

Harvest notes, reference Beamesderfer et al. (1998), Yuen (2002) 

Age notes, reference Yearly. Used Methow River age data. 

Population Lost River/Early Winters Creek 

Years of data, length of series 1958–2001, 42 years 

Abundance type, notes, reference Total live count. Cooney (2001); 1999–2001 data from J. 

Hubble, Yakama Indian Nation, P.O. Box 151, Toppenish, 

WA 98948. 

Hatchery notes, reference Beamesderfer et al. (1998), Cooney (2001). 

Harvest notes, reference Beamesderfer et al. (1998), Yuen (2002). 

Age notes, reference Yearly. Used Methow River age data. 

Population Methow River (main stem) 

Years of data, length of series 1958–2001, 43 years 

Abundance type, notes, reference Redd count. Cooney (2001); 1999–2001 data from J. 

Hubble, Yakama Indian Nation, P.O. Box 151, Toppenish, 

WA 98948. 

526
APPENDIX A 

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Hatchery notes, reference Used Methow River estimates for hatchery fraction. 

Harvest notes, reference Beamesderfer et al. (1998), Yuen (2002). 

Age notes, reference Yearly. Beamesderfer et al. (1998); update data from J. 

Hubble, Yakama Indian Nation, P.O. Box 151, Toppenish, 

WA 98948. 

Population Twisp River 

Years of data, length of series 1958–2001, 42 years 

Abundance type, notes, reference Redd count. Cooney (2001); 1999–2001 from J. Hubble, 

Yakama Indian Nation, P.O. Box 151, Toppenish, WA 

98948. 

Hatchery notes, reference Cooney (2001) 

Harvest notes, reference Beamesderfer et al. (1998), Yuen (2002). 

Age notes, reference Yearly. Beamesderfer et al. (1998), update data from J. 

Hubble, Yakama Indian Nation, P.O. Box 151, Toppenish, 

WA 98948. 

Population Wenatchee River 

Years of data, length of series 1960–2001, 42 years 

Abundance type, notes, reference Estimated total count. Sum of expanded redd counts by area, 

extended series described in Cooney (2001). Mosey and 

Murphy (2002). 

Hatchery notes, reference Cooney (2001) for prior to 1999; assumed 5% of Icicle Creek 

(Leavenworth National Fish Hatchery) returns strayed into 

upriver areas; 1999–2001 data based on annual WDFW 

carcass surveys (e.g., Mosey and Murphy 2002). 

Harvest notes, reference Beamesderfer et al. (1998), Yuen (2002) 

Age notes, reference Yearly. Beamesderfer et al. (1998); updates from WDFW 

annual sampling reports (e.g., Mosey and Murphy 2002). 

Population Little Wenatchee River 

Years of data, length of series 1958–2001, 42 years 

Abundance type, notes, reference Redd count. Cooney (2001), Mosey and Murphy (2002). 

Hatchery notes, reference Data prior to 1999 (Cooney 2001). Data for 1999–2001 from 

WDFW annual carcass sampling (e.g., Mosey and Murphy 

2002). 

Harvest notes, reference Applied aggregate Wenatchee River estimates. 

Age notes, reference Yearly. Applied aggregate Wenatchee River estimates. 

Population White River 

Years of data, length of series 1958–2001, 42 years 

527
REFERENCES AND APPENDICES

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Abundance type, notes, reference Redd count. Cooney (2001), Mosey and Murphy (2002). 

Hatchery notes, reference Data prior to 1999 (Cooney 2001). Data for 1999–2001 from 

WDFW annual carcass sampling (e.g., Mosey and Murphy 

2002). 

Age notes, reference Yearly. Applied aggregate Wenatchee estimates. 

Population Nason Creek 

Years of data, length of series 1958–1996, 44 years 

Abundance type, notes, reference Redd count. Cooney (2001), Mosey and Murphy (2002) 

Hatchery notes, reference Data prior to 1999 (Cooney 2001). Data for 1999–2001 from 

WDFW annual carcass sampling (e.g., Mosey and Murphy 

2002). 

Harvest notes, reference Applied aggregate Wenatchee estimates. 

Age notes, reference Yearly. Applied aggregate Wenatchee estimates. 

Population Chiwawa River 

Years of data, length of series 1958–2001, 44 years 

Abundance type, notes, reference Redd count. Cooney (2001), Mosey and Murphy (2002). 

Hatchery notes, reference Data prior to 1999 (Cooney 2001). Data for 1999–2001 from 

WDFW annual carcass sampling (e.g., Mosey and Murphy 

2002). 

Harvest notes, reference Applied aggregate Wenatchee estimates. 

Age notes, reference Yearly. Applied aggregate Wenatchee estimates. 

Population Upper mainstem Wenatchee 

Years of data, length of series 1959–2001, 40 years 

Abundance type, notes, reference Redd count. Cooney (2001), Mosey and Murphy (2002). 

Hatchery notes, reference Data prior to 1999 (Cooney 2001); 1999–2001, WDFW 

annual carcass sampling (e.g., Mosey and Murphy 2002). 

Harvest notes, reference Applied aggregate Wenatchee estimates. 

Age notes, reference Yearly. Applied aggregate Wenatchee estimates. 

Population Entiat River 

Years of data, length of series 1960–1998, 42 years 

Abundance type, notes, reference Estimated total count. Cooney (2001), Carie (2002). 

Hatchery notes, reference Assumed equivalent of 5% of the rack returns at Entiat NFH 

strayed up into natural spawning areas each year. Cooney 

(2001), Carie (2002). 

528
APPENDIX A 

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Harvest notes, reference Cooney (2001), updated using (Yuen 2002). 

Age notes, reference Yearly. Beamesderfer et al. (1998); updated using data from 

USFWS (e.g., Carie 2002). 

Puget Sound Chinook Salmon ESU 

Population South Fork Nooksack River 

Years of data 1984–2001 

Abundance type, notes Carcass/redd counts. Escapements are an expansion of 

carcass spawning surveys in the upper South Fork and in 

Huchinson and Skookum creeks prior to 1999 and redd 

counts × 2.5 from 1999 on. They are designated early 

spawners; counts stop on 1 October (fish counted after that 

date are thought to be out-of-basin strays). 

Hatchery notes Contribution rate of hatchery fish to natural spawning only 

estimated since 1999 (carcass surveys looking for marked 

fish). It is assumed that the number of hatchery fish on 

spawning grounds is correlated with number of hatchery fish 

returning rather than number of fish on spawning grounds. 

Therefore, the stray rate of hatchery to spawning grounds for 

years without data is estimated as the average of the 3 years 

observed, not to exceed 43% of the spawning fish. 

Abundance, hatchery reference Puget Sound Indian Tribes and WDFW (2001, 2003); Castle 

and Currence (2001); NMFS/Nooksack Comanagers 

meeting, Point No Point, WA, 29 July 2002; Sanford 

(2003a). 

Harvest notes, reference Fishing rates are calculated using the method used by the 

Pacific Salmon Commission (PSC). Coded-wire-tag (CWT) 

recoveries of indicator hatchery stocks (South Fork 

fingerlings 1974–1988 and North Fork fingerlings 1988–

1998) were used in combination to give the longer time series 

of estimates. Estimates included both landed and incidental 

mortalities. PSC (1999, 2000). 

Age notes, reference Scale sampling; n = 213 fish sampled, 3 years (1993–2001, 

using years with sample sizes >40 fish). Age distribution 

reconstructed for other years using average cohort 

distribution weighted by annual abundance of contributing 

years (Sands 2002, in prep). Age database, WDFW (2001). 

Population Cedar River 

Years of data 1965–2002 

529
REFERENCES AND APPENDICES

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Abundance type, notes, reference Live counts. Escapement estimates are from live count 

surveys and expanded by area under the curve method. 

Puget Sound Indian Tribes and WDFW (2001, 2003); 

NMFS/Comanagers meeting, Seattle, WA, 8 November 

2002; Sanford (2003a). 

Hatchery notes, reference There is no estimate of the contribution rate of hatchery fish 

to natural spawning. Hatchery Chinook salmon are produced 

at the Issaquah Hatchery primarily for producing fish for 

harvest. 

Harvest notes, reference Fishing rates are calculated using the method used by the 

PSC. CWT recoveries of the South Puget Sound index 

indicator hatchery stock group (1971–1995) were used. 

Estimates included both landed and incidental mortalities. 

PSC (1999, 2000). 

Scale sampling; n = 9 fish sampled in 1988. Age distribution 

reconstructed for other years using average cohort 

distribution weighted by annual abundance of contributing 

years (Sands 2002, in prep.); age database (WDFW 2001). 

Age notes, reference 

Population Dosewallips River 

Years of data 1968–2002 

Abundance type, notes, reference Live/dead surveys and redd counts. Three years reported no 

escapement; the TRT is using one fish each for those years 

(the surveyors could easily have missed one fish, and it 

makes calculations easier). Puget Sound Indian Tribes and 

WDFW (2001, 2003); NMFS/Comanagers meeting, Point No 

Point, WA, 8 August 2002; Sanford (2003a). 

Hatchery notes, reference Probably few, if any, hatchery strays in the Dosewallips. 

Puget Sound Indian Tribes and WDFW (2001, 2003); 

NMFS/Comanagers meeting, Point No Point, WA, 8 August 

2002. 

Harvest notes, reference Fishing rates are calculated using the method used by the 

PSC. CWT recoveries of George Adams indicator hatchery 

stock (1972–1994) were used. Estimates included both 

landed and incidental mortalities. PSC (1999, 2000); 

D. Simmons.c

Age notes, reference Used average age distribution from Green River Chinook 

salmon. Age distribution reconstructed for Dosewallips 

using average cohort distribution weighted by annual 

abundance of contributing years (Sands 2002, in prep.). 

Population Dungeness River 

Years of data 1986–2002 

530
APPENDIX A 

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Abundance type, notes, reference Redd counts. Escapements for Dungeness are for 

spring/summer-run stock with spawning from August to midOctober. Puget Sound Indian Tribes and WDFW (2001, 

2003); NMFS/Comanagers meeting, Point No Point, WA, 

8 August 2002. 

Hatchery notes, reference There are no estimates of contribution rate of hatchery fish to 

natural spawners. 

Harvest notes, reference There is assumed to be no harvest in mixed-maturity fishery. 

The mature fishery (fishing on mature fish or fish on their 

spawning migration) normally includes all freshwater or 

terminal fisheries. Terminal fisheries include sport, 

ceremonial, subsistence, and incidental (in coho fishery). 

Incidental catch averages 19 fish per year and sport: 34 fish 

gives a terminal fishing rate of .32, and a very slight 

randomization with negative trend was added. N. Sands.d

Age notes, reference Scale sampling; n = 159 fish sampled from 1987 to 1998 

(9 years with sample sizes >10 fish; all years with sample 

sizes <40 fish). Age distribution reconstructed for other 

years using average cohort distribution weighted by annual 

abundance of contributing years (Sands 2002, in prep.). Age 

database (WDFW 2001). 

Population Elwha River 

Years of data 1986–2002 

Abundance type, notes, reference Redd counts. Escapement to natural grounds equals total 

post-fishery escapement minus broodstock take and rack 

return, and includes prespawning mortality. Puget Sound 

Indian Tribes and WDFW (2001, 2003); NMFS/Comanagers 

meeting, Point No Point, WA, 8 August 2002. 

Hatchery notes There is no estimate of the contribution rate of hatchery fish 

to natural spawning. 

Hatchery reference WDFW et al. (2001); NMFS and Comanagers meeting, Point 

No Point, WA, 8 August 2002. 

Harvest notes, reference Fishing rates are calculated using the method used by the 

PSC. CWT recoveries of Elwha indicator hatchery stock 

(1982–1994) were used. Estimates included both landed and 

incidental mortalities. PSC (1999, 2000); D. Simmons. e

Age notes, reference Scale sampling; n = 2,322 fish sampled from 1989 to 1998 

(9 years, all with large sample sizes). Age distribution 

reconstructed for other years using average cohort 

distribution weighted by annual abundance of contributing 

years (Sands 2002, in prep.). Age database WDFW (2001). 

531
REFERENCES AND APPENDICES

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Population Green River 

Years of data 1968–2002 

Abundance type, notes, reference Redd counts. Escapements for this population do not include 

spawning in Newaukum Creek. Escapement estimates are 

based on redd counts in specified sections of the river and 

expanded by a factor to reflect the total spawning habitat of 

the river. Puget Sound Indian Tribes and WDFW (2001, 

2003); NMFS/Comanagers meeting, Seattle, WA, 

8 November 2002. 

Hatchery notes, reference Hatchery contribution estimates from Soos, Icy, and Keta 

creeks hatcheries. Alexandersdottir (2001). 

Harvest notes, reference Fishing rates are calculated using the method used by the 

PSC. CWT recoveries of the South Puget Sound index 

indicator hatchery stock group (1971–1995) were used. 

Estimates included both landed and incidental mortalities. 

PSC (1999, 2000); D. Simmons.c

Age notes, reference Scale sampling; n = 2,454 fish sampled from 1988 to 1998. 

Age distribution reconstructed for other years using average 

cohort distribution weighted by annual abundance of 

contributing years (Sands 2002, in prep.). Age database 

WDFW (2001). 

Population Lower Sauk River 

Years of data 1952–2002 

Abundance type, reference Redd counts. Puget Sound Indian Tribes and WDFW (2001, 

2003); NMFS/Comanagers meetings, La Conner, WA, 

9 August 2002 and 10–11 June 2003; B. Hayman.f

Hatchery notes, reference Assume the hatchery releases from the Marblemount 

Hatchery do not influence the Sauk River populations. 

NMFS/Comanagers Meetings, La Conner, WA, 9 August 

2002 and 10–11 June 2003. 

Harvest notes, reference Fishing rates are calculated using the PSC method. CWT 

recoveries of an aggregate of fall indicator hatchery stocks 

(Samish, Stillaguamish, Grovers, Green, Nisqually, and 

George Adams) 1971–1997 were used for ocean fisheries, 

and terminal run reconstruction was used for terminal 

fisheries. Estimates included both landed and incidental 

mortalities. J. Scott and D. Simmonsg

 analysis for TRT after 

method of PSC (1999). 

Age notes, reference Scale sampling from the upper Skagit River; n = 1,332 fish 

sampled from 7 years between 1992 to 2000 (where sample 

sizes were >40 fish). Age distribution reconstructed for other 

years using average cohort distribution weighted by annual 

abundance of contributing years (Sands 2002, in prep.). Age 

database, WDFW (2001). 

532
APPENDIX A 

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Population Lower Skagit River 

Years of data 1952–2002 

Abundance type, reference Redd counts, Puget Sound Indian Tribes and WDFW (2001, 

2003); NMFS/Comanagers Meetings, La Conner, WA, 

9 August 2002 and 10 June–3 November; B. Hayman.f

Hatchery notes, reference Marblemount Hatchery rack returns. Some sampling for 

hatchery contributions to spawning grounds 1998–2001. 

NMFS/Comanagers Meetings, La Conner, WA, 9 August 

2002 and 10–11 June 2003. 

Harvest notes, reference Fishing rates are calculated using the PSC method. CWT 

recoveries of an aggregate of fall indicator hatchery stocks 

(Samish, Stillaguamish, Grovers, Green, Nisqually, and 

George Adams) were used for ocean fisheries, and terminal 

run reconstruction was used for terminal fisheries. Estimates 

included both landed and incidental mortalities. J. Scott and 

D. Simmonsg

 analysis for TRT after method of PSC (1999). 

Age notes, reference Scale sampling; n = 392 fish sampled from 4 years between 

1992 to 2001 (where sample sizes >40 fish). Age 

distribution reconstructed for other years using average 

cohort distribution weighted by annual abundance of 

contributing years (Sands 2002, in prep.). Age database 

WDFW (2001). 

Population Nisqually River 

Years of data 1968–2002 

Abundance type, notes, reference Carcass counts. Escapements are an expansion of spawning 

surveys in Prairie River/Creek. Puget Sound Indian Tribes 

and WDFW (2001, 2003); NMFS/Comanagers Meeting, 

Puyallup, WA, 21 November 2002; Sanford (2003b). 

Hatchery notes, reference No estimates of contribution of hatchery fish to natural 

spawning have been made in past, but these were started in 

2002. Puget Sound Indian Tribes and WDFW (2001, 2003). 

Harvest notes, reference Fishing rates are calculated using the PSC method. CWT 

recoveries of Kalama River fingerling indicator hatchery 

stock 1979−1995 were used. Estimates included both landed 

and incidental mortalities. D. Simmons estimates based on 

method of PSC (1999).h

Age notes, reference Scale sampling from upper Skagit River; n = 1,313 fish 

sampled from 1992 and 1993. Age distribution reconstructed 

for other years using average cohort distribution weighted by 

annual abundance of contributing years (Sands 2002, in 

prep.). Age database WDFW (2001). 

533
REFERENCES AND APPENDICES

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Population North Fork Nooksack River 

Years of data 1984–2001 

Abundance type, notes, reference Carcass counts. Total Chinook salmon on the spawning 

grounds = expanded carcass counts on spawning grounds 

plus turnback hatchery fish. Puget Sound Indian Tribes and 

WDFW (2001, 2003); Castle and Currence (2001); 

NMFS/Nooksack Comanagers meeting, La Conner, WA 

29 July 2002; Sanford (2003a). 

Hatchery notes, reference Contribution rate of cultured fish (hatchery and acclimation 

releases) to natural spawning started in 1988 with significant 

returns from the hatchery program. Puget Sound Indian 

Tribes and WDFW (2001, 2003); NMFS/Nooksack 

Comanagers meeting, La Conner, WA, 29 July 2002. 

Harvest notes, reference Fishing rates are calculated using the PSC method. Codedwire-tag recoveries of indicator hatchery stocks (South Fork 

Nooksack fingerling 1974–1988 and North Fork Nooksack 

fingerling 1988–1998) were used in combination to give the 

longer time series of estimates. Estimates included both 

landed and incidental mortalities. PSC (1999, 2000), 

Goodman 2002, D. Simmons.c

Age notes, reference Scale sampling; n = 336 fish sampled from 4 years between 

1992 to 2000 (where sample sizes >40 fish). Age 

distribution reconstructed for other years using average 

cohort distribution weighted by annual abundance of 

contributing years (Sands 2002, in prep.). Age database 

WDFW (2001). 

Population Lake Washington tributaries 

Years of data 1983–2002 

Abundance type, notes, reference Live counts. Escapement estimates are from live counts 

expanded for area under the curve. Escapement numbers are 

an index of part of Cottage Creek and all of Bear Creek that 

represents about 95% of the northern tributaries (not 

including Issaquah). Puget Sound Indian Tribes and WDFW 

(2001, 2003); NMFS/Comanagers meeting, Seattle, WA, 

8 November 2002; Sanford (2003a). 

Hatchery notes, reference No estimate of contribution rate of hatchery fish to spawning. 

There are trapping data that indicate the presence of hatchery 

strays. NMFS/Comanagers meeting, Seattle, WA, 

8 November 2002. 

Harvest notes, reference Fishing rates are calculated using the PSC method. CWT 

recoveries of the South Puget Sound index indicator hatchery 

stock group (1971–1995) were used. Estimates included 

both landed and incidental mortalities. PSC (1999, 2000); D. 

Simmons.c

534
APPENDIX A 

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Age notes, reference Scale sampling; n = 75 fish sampled in 1988 (in 1995, only 7 

fish were sampled and these were not used). Age distribution 

reconstructed for other years using average cohort 

distribution weighted by annual abundance of contributing 

years (Sands 2002, in prep.). Age database WDFW (2001). 

Population North Fork Stillaguamish River 

Years of data 1974–2002 

Abundance type, notes, reference Redd counts. Escapement estimates are from foot and boat 

surveys of the main stem and foot surveys of the tributaries 

of redd counts. Puget Sound Indian Tribes and WDFW 

(2001, 2003); Rawson and Kraemer (2001). 

Hatchery notes, reference Stillaguamish Tribal Harvey Creek Hatchery 

supplementation program does not have rack returns. Return 

to hatchery is actual broodstock take, which occurs in the 

North Fork. Hatchery supplementation program began in 

early 1980s. Returns started in 1986. Puget Sound Indian 

Tribes and WDFW (2001, 2003), Rawson and Kraemer 

(2001). 

Harvest notes, reference Fishing rates are calculated using the PSC method. CWT 

recoveries of the Stillaguamish indicator hatchery stock are 

used when available; otherwise an aggregate of fall indicator 

hatchery stocks (Samish, Stillaguamish, Grovers, Green, 

Nisqually, and George Adams) was used for ocean fisheries, 

and terminal run reconstruction was used for terminal 

fisheries. Estimates included both landed and incidental 

mortalities. Fishing rate estimates derived from D. Simmons 

and J. Scotti

 after method of PSC (1999). 

Age notes, reference Otolith project; n = 2,772 fish sampled from 12 years 

between 1987 and 2001 (where sample sizes >40 fish). Age 

distribution reconstructed for other years using average 

cohort distribution weighted by annual abundance of 

contributing years (Sands 2002, in prep.). Age database 

WDFW (2001). 

Population Puyallup River 

Years of data 1968–2002 

535
REFERENCES AND APPENDICES

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Abundance type, notes, reference Redd and live/dead fish counts. Index counts of spawning 

from South Prairie Creek, which in the past were from a 

limited area and not a good index of the system. Surveys 

now are from the entire South Prairie Creek basin. These 

started in 1992 by float and foot surveys of redds and 

live/dead fish. However, estimates given here are based on 

index count only through 1998. Revisions are being made 

back to 1992 and should be available soon. Puget Sound 

Tribes and WDFW (2001, 2003); NMFS/Comanagers 

meeting, Puyallup, WA, 21 November 2002; Sanford 

(2003a). 

Hatchery notes, reference There is no estimate of the contribution rate of hatchery fish 

to natural spawning. Puget Sound Tribes and WDFW (2001, 

2003). 

Harvest notes, reference Fishing rates are calculated using the PSC method. CWT 

recoveries of the south Puget Sound fingerling indicator 

hatchery stock group, 1971–1995, were used. Estimates 

included both landed and incidental mortalities. 

D. Simmonsc

 estimates based on method of PSC (1999). 

Age notes, reference Scale sampling; n = 895 fish sampled from 8 years between 

1992 and 2000. Age distribution reconstructed for other 

years using average cohort distribution weighted by annual 

abundance of contributing years (Sands 2002, in prep.). Age 

database, WDFW (2001). 

Population Skokomish River 

Years of data 1987–2002 

Abundance type, notes, reference Various. Escapements are from the co-managers. Estimates 

should be available from 1976 although there is concern 

about data prior to 1990 (T. Johnsonj

) (see 

http://www.nwifc.wa.gov). This population includes index 

survey sites in both the main river, including the North Fork, 

and several tributaries; mainly foot, sometimes float. 

Escapement estimates vary from year to year in survey type 

and expansion (from 1990 on, no expansion for unsurveyed 

areas—in other words, all spawning areas are surveyed). 

Quality of escapement data considered good (WDF, WDW, 

and WWTIT 1993). Puget Sound Indian Tribes and WDFW 

(2001, 2003); NMFS/Comanagers meeting, Point No Point, 

WA, 8 August 2002; Sanford (2003a). 

Hatchery notes, reference Hatchery strays from the George Adams Hatchery, Hood 

Canal (Hoodsport Hatchery and Enetai Hatchery) are found 

on the spawning grounds, but there is no estimate of the 

contribution rate of hatchery fish to natural spawning. Puget 

Sound Tribes and WDFW (2001, 2003); NMFS/Comanagers 

meeting, Point No Point, WA, 8 August 2002. 

536
APPENDIX A 

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Harvest notes, reference Fishing rates are calculated using the method used by the 

PSC. CWT recoveries of the George Adams indicator 

hatchery stock group (1972–1994) were used. Estimates 

included both landed and incidental mortalities. PSC (1999, 

2000), D. Simmons.e

Age notes, reference Scale sampling; 1999–2001; sample size not given. Age 

distribution reconstructed for other years using average 

cohort distribution weighted by annual abundance of 

contributing years (Sands 2002, in prep.). Puget Sound 

Indian Tribes and WDFW (2003). 

Population Skykomish River 

Years of data 1965–2002 

Abundance type, notes, reference Aerial surveys, redd counts. Escapements for the Skykomish 

population were updated by the comanagersk

 for 1979–2001. 

The Skykomish population includes 10 survey sites in the 

Skykomish, Wallace, Bridal Veil, Sunset Falls, Pilchuck, and 

Sultan rivers. Escapement estimates are from aerial surveys 

of the main stem and foot surveys of the tributaries (redd 

counts). Escapement estimates for the total Snohomish 

system are available from 1965. Skykomish estimates for 

1965–1978 are made by subtracting Skykomish population 

escapements from the total system escapements. Puget 

Sound Tribes and WDFW (2001, 2003); NMFS/Comanagers 

meeting, Mill Creek, WA, 18 November 2002; Sanford 

(2003a). 

Hatchery notes, reference From 1997 to the present, contribution rate of hatchery fish 

to natural spawning is estimated by sampling spawning 

grounds for otolith-marked hatchery fish from Tulalip and 

Wallace hatcheries. Prior to 1997, the hatchery contribution 

is estimated from “run reconstruction” of hatchery returns 

(Rawson 2001). Puget Sound Tribes and WDFW (2001, 

2003). 

Harvest notes, reference Fishing rates are calculated using the PSC method. CWT 

recoveries of an aggregate of fall indicator hatchery stocks 

(Samish, Stillaguamish, Grovers, Green, Nisqually, and 

George Adams), 1971–1994, were used for ocean fisheries 

and terminal run reconstruction was used for terminal 

fisheries. Estimates included both landed and incidental 

mortalities. Analysis for TRTl

 after method of PSC (1999); 

Rawson (2001). 

Age notes, reference Scale or otolith sampling; n = 510 fish sampled from 5 years 

between 1989 and 1999, where sample sizes >40 fish. Age 

distribution was reconstructed for other years using average 

cohort distribution weighted by annual abundance of 

contributing years (Sands 2002, in prep.). Rawson and 

Kraemer (2001); age database WDFW (2001). 

537
REFERENCES AND APPENDICES

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Population Snoqualmie River 

Years of data 1965–2002 

Abundance type, notes Hatchery straying estimates and otolith sampling. 

Escapements for the Snoqualmie population were updated 

from the comanagers for 1979–2000.k

 The Snoqualmie 

population includes six survey sites in the Snoqualmie River 

and tributaries of the Snoqualmie River. Escapement for the 

SASSI Snohomish fall-run stock are available from 1965m

and, on average, the Snoqualmie portion represented 62% of 

the Snohomish fall-run escapement. Thus, estimates of 

Snoqualmie escapement prior to 1979 are estimated as 62% 

of the Snohomish fall-run escapement. Puget Sound Tribes 

and WDFW (2001, 2003); NMFS/Comanagers meeting, Mill 

Creek, WA, 18 November 2002; Sanford (2003a). 

Hatchery notes, reference From 1997 to the present, contribution rate of hatchery fish 

to natural spawning is estimated by sampling spawning 

grounds for otolith-marked hatchery fish from Tulalip and 

Wallace hatcheries. Prior to 1997, the hatchery contribution 

is estimated from “run reconstruction” of hatchery returns 

(Rawson 2001); Puget Sound Tribes and WDFW (2001, 

2003); NMFS/Comanagers meeting, Mill Creek, WA, 

18 November 2002. 

Harvest notes, reference Fishing rates are calculated using the PSC method. CWT 

recoveries of an aggregate of fall indicator hatchery stocks 

(Samish, Stillaguamish, Grovers, Green, Nisqually, and 

George Adams), 1971–1994, were used for ocean fisheries, 

and terminal run reconstruction was used for terminal 

fisheries. Estimates included both landed and incidental 

mortalities. Analysis for TRTl

 after method of PSC (1999); 

Rawson (2001). 

Age notes, reference Scale sampling and scale/otolith sampling; n = 493 fish 

sampled from 6 years between 1989 and 1999, where 

samples were >40 fish. Age distribution was reconstructed 

for other years using average cohort distribution weighted by 

annual abundance of contributing years (Sands 2002, in 

prep.). Otolith sampling on spawning grounds (Rawson and 

Kraemer 2001). Age database WDFW (2001). 

Population South Fork Stillaguamish River 

Years of data 1974–2002 

Abundance type, notes, reference Redd counts. Escapement estimates are from foot and boat 

surveys of the main stem and from foot surveys of redd 

counts of the tributaries. Puget Sound Tribes and WDFW 

(2001, 2003), Rawson and Kraemer (2001). 

538
APPENDIX A 

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Hatchery notes, reference It is assumed that no hatchery fish stray to the spawning 

grounds of the South Fork Stillaguamish River. Puget Sound 

Tribes and WDFW (2001, 2003); C. Kraemer and 

K. Rawson.n

Harvest notes, reference Fishing rates are calculated using the PSC method. CWT 

recoveries of the Stillaguamish indicator hatchery stock, 

1971–1994, were used when available, otherwise an 

aggregate of fall indicator hatchery stocks (Samish, 

Stillaguamish, Grovers, Green, Nisqually, and George 

Adams) was used for ocean fisheries, and terminal run 

reconstruction was used for terminal fisheries. Estimates 

included both landed and incidental mortalities. Fishing rate 

estimates derived after method of PSC (1999). 

Age notes, reference Otolith project; n = 1,516 fish sampled from 9 years between 

1987 and 2001, where sample sizes >40 fish. Age 

distribution reconstructed for other years using average 

cohort distribution weighted by annual abundance of 

contributing years (Sands 2002, in prep.). Age database 

WDFW (2001). 

Population Suiattle River 

Years of data 1952–2002 

Abundance type, notes, reference Peak live/dead counts/redd counts. Before 1994 escapement 

estimation method was peak live/dead counts for partial 

spawning grounds to get fish per mile, then expand by 8.5 for 

total spawning grounds. From 1994 on, redd counts are used 

to cover entire spawning area. Puget Sound Tribes and 

WDFW (2001, 2003); R. Hayman;f

 J. Scott.l

Hatchery notes, reference No hatchery in basin; broodstock take from the Suiattle, 

1974–1988, to the Marblemount Hatchery (and fry released 

at hatchery). Assume no hatchery contribution on spawning 

grounds. NMFS/Comanagers meetings, La Conner, WA, 

9 August 2002 and 10–11 June 2003. 

Harvest notes, reference Fishing rates are calculated using the PSC method. CWT 

recoveries of Skagit spring-run yearling indicator hatchery 

stock, 1981–1996, were used. Estimates included both 

landed and incidental mortalities. PSC (1999); D. Simmons, 

NMFS provided worksheet of estimates.o

Age notes, reference Scale sampling; n = 536 fish sampled from 8 years between 

1986 and 2001, where sample sizes >40 fish. Age 

distribution reconstructed for other years using average 

cohort distribution weighted by annual abundance of 

contributing years (Sands 2002, in prep.). Age database 

WDFW (2001). 

539
REFERENCES AND APPENDICES

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Population Upper Cascade River 

Years of data 1984–2002 

Abundance type, notes, reference Live/dead counts expanded for area/redd counts. Before 

1992, escapement estimation method was peak live/dead 

counts with expansion for uncovered ground. From 1992 on, 

redd counts have been used to cover entire spawning area. 

Puget Sound Tribes and WDFW (2001, 2003); 

NMFS/Comanagers meetings, La Conner, WA, 9 August 

2002 and 10–11 June 2003; R. Hayman.p

Hatchery notes, reference The hatchery is at the mouth of the Cascade River, but 

releases fish into the Suiattle River. Negligible hatchery 

contribution assumed on spawning grounds. 

NMFS/Comanagers meetings, La Conner, WA, 9 August 

2002 and 10–11 June 2003.p

Harvest notes, reference Fishing rates are calculated using the PSC method. CWT 

recoveries of Skagit spring-run yearling indicator hatchery 

stock, 1981–1996, were used. Estimates included both 

landed and incidental mortalities. 

Age notes, reference Scale sampling; n = 227 fish sampled from 3 years between 

1992 and 2001. Age distribution was reconstructed for other 

years using an average cohort distribution weighted by the 

annual abundance of contributing years (Sands 2002, in 

prep.). Age database WDFW (2001). 

Population Upper Sauk River 

Years of data 1952–2002 

Abundance type, notes, reference Peak live/dead counts/redd counts. Before 1994, escapement 

estimation method was peak live/dead counts with expansion 

for uncovered ground. For 1994 and after, used redd counts 

and cover entire spawning area. Puget Sound Tribes and 

WDFW (2001, 2003); NMFS/Comanagers meetings, 

La Conner, WA, 9 August 2002 and 10–11 June 2003.p

Hatchery notes, reference No hatchery in Upper Sauk. Assume the hatchery releases 

from the Marblemount Hatchery do not influence the Sauk 

River populations. NMFS/Comanagers meetings, La 

Conner, WA, 9 August 2002 and 10–11 June 2003. 

Harvest notes, reference Fishing rates are calculated using the method used by the 

PSC. CWT recoveries of Skagit spring-run yearling 

indicator hatchery stock were used. Estimates included both 

landed and incidental mortalities. PSC (1999), D. Simmons.o

Age notes, reference Scale sampling; n = 275 fish sampled from 5 years 1986–

2001, where sample sizes >40 fish. Age distribution reconstructed for other years using an average cohort distribution 

weighted by the annual abundance of contributing years 

(Sands 2002, in prep.). Age database WDFW (2001). 

540
APPENDIX A 

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Population Upper Skagit River 

Years of data 1952–2002 

Abundance type, notes, reference Redd counts. Escapements are based on redd counts and are 

considered a good measure of relative abundance from year 

to year. Puget Sound Tribes and WDFW (2001, 2003); 

NMFS/Comanagers meetings, La Conner, WA, 9 August 

2002 and 10–11 June 2003; R. Hayman.p

Hatchery notes, reference Marblemount Hatchery rack returns. The Marblemount 

Hatchery is situated at the mouth of the Cascade River, such 

that returns pass through the lower and upper Skagit River. 

Some samples for hatchery contribution, 1995–2001. 

NMFS/Comanagers Meetings, La Conner, WA, 9 August 

2002 and 10–11 June 2003. 

Harvest notes, reference Fishing rates calculated using the PSC method. CWT 

recoveries of an aggregate of fall indicator hatchery stocks 

(Samish, Stillaguamish, Grovers, Green, Nisqually, and 

George Adams) were used for ocean fisheries, and terminal 

run reconstruction was used for terminal fisheries. Estimates 

included both landed and incidental mortalities. Analysis for 

TRTg

 after method of PSC (1999). 

Age notes, reference Scale sampling; n = 1,691 fish sampled from 8 years between 

1992 and 2001, where sample sizes > 40 fish. Age 

distribution was reconstructed for other years using an 

average cohort distribution weighted by the annual 

abundance of contributing years (Sands 2002, in prep.). Age 

database WDFW (2001). 

Population White River 

Years of data 1970–2002 

Abundance type, notes, reference Trap counts. Chinook counts from 1970 to present are from 

Buckley trap for the entire season (year round). Counts do 

not include spawners below the dam, which may be about 

25% of total spawning (21 November 2002). Spawning 

ground surveys are difficult due to it being a glacial system. 

Starting 2003, rejecting (not passing upstream) tagged or 

marked fish (except acclimated fish). Earlier years may 

include fall-run hatchery fish. WDF et al. (1993); C. 

Phinney;q

 Puget Sound Tribes and WDFW (2001, 2003); 

NMFS/Comanagers meeting, Puyallup, WA, 21 November 

2002. 

Hatchery notes, reference There is a program to put acclimated hatchery fish on the 

spawning grounds; we will begin to estimate this. No 

estimates of hatchery contribution prior to 2001. Assume no 

contribution of hatchery fish to natural spawning. Puget 

Sound Tribes and WDFW (2001, 2003). 

541
REFERENCES AND APPENDICES

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Harvest notes, reference Fishing rates are calculated using the method used by the 

PSC. CWT recoveries of the White River yearling indicator 

hatchery stock, 1974–1994, were used. Estimates include 

both landed and incidental mortalities. Estimates based on 

method of PSC (1999).h

Age notes, reference Scale sampling; n = 1,327 fish sampled from 1993 to 1998. 

Age distribution was reconstructed for other years using 

average cohort distribution weighted by annual abundance of 

contributing years (Sands 2002, in prep.). WDFW (2001). 

Lower Columbia River Chinook Salmon ESU

Population Big White Salmon River fall run 

Years of data, length of series 1967–2001, 38 years 

Abundance type, notes, reference Peak count. Abundance data are for adults and jacks. 

Estimates of spawner abundance are extrapolations made 

using peak count data and marking rate. Data for 1980–2000 

from Rawding (2001a). Data for 1964–1979 from Norman 

(1982). Rawding (2001a); Sanford (2003b) 

Hatchery notes, reference Hatchery data are part of the escapement data from Rawding 

(2001a). 

Harvest reference stock Spring Creek 

Harvest notes, reference Estimated exploitation rate on hatchery stocks applied to 

natural stocks. PSC (2002). 

Age notes, reference Age distribution for 1982–1990 based on an average of 

1991–2000. Rawding (2001a). 

Population Clackamas River fall run 

Years of data, length of series 1967–2001, 35 years 

Abundance type, reference Peak count. ODFW (1998a). 

Hatchery notes, reference No hatchery data 

Harvest reference No harvest data available 

Age notes, reference Generic fall-run age structure. Myers et al. (1998). 

Population Coweeman River fall run 

Years of data, length of series 1964–2001, 38 years 

Abundance type, notes, reference Peak count. Abundance data are for adults and jacks. 

Estimates extrapolated from peak count data and marking 

rate. Years 1964–1979 spawning data from are from 

Kreitman (1981); 1980–2000 data from Rawding (2001a). 

Hatchery notes, reference Hatchery data are part of the escapement data from Rawding 

(2001a). 

542
APPENDIX A 

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Harvest reference stock Coweeman 

Harvest notes, reference Harvest data based on Pacific Fisheries Management Council 

(PFMC) models provided by D. Simmons.r

Age notes, reference Age distribution for 1980–1990 and estimate based on 

average for 1991–2000. Rawding (2001a). 

Population East Fork Lewis River fall run 

Years of data, length of series 1980–2001, 22 years 

Abundance type, notes, reference Peak count. Abundance data are for adults and jacks. 

Estimates of spawner abundance are extrapolations made 

using peak count data and marking rate. Rawding (2001a); 

Sanford (2003b). 

Harvest reference stock, reference Lewis River wild. Rawding (2001a). 

Harvest notes, reference Adult equivalent exploitation rate for Lewis River from 

D. Simmons.r

 Rawding (2001a). 

Age distribution for 1980–1983 based on an average for 

1984–2000. Rawding (2001a). 

Age notes, reference 

Population Lewis River (brights) fall run 

Years of data, length of series 1964–2001, 38 years 

Abundance type, notes, reference Peak count. Abundance data are for adults and jacks. 

Estimates of spawner abundance are extrapolations made 

using peak count data and marking rate. Spawning data for 

1964–1979 from Kreitman (1981); 1980–2000 from 

Rawding (2001a). 

Hatchery notes, reference Hatchery data are part of the escapement data from Rawding 

(2001a). 

Harvest reference stock Lewis River wild 

Harvest notes, reference Adult equivalent exploitation rate for Lewis River from 

D. Simmons. 

Age notes, reference Age distribution for 1980–1990 and estimate based on 

average from 1991 to 2000. Rawding (2001a). 

Population Middle Columbia Gorge tributaries fall run 

Years of data, length of series 1964–2001, 38 years 

Abundance type, notes, reference Peak count. Abundance data are for adults and jacks. 

Estimates of spawner abundance are extrapolations made 

using peak count data and marking rate. Data for 1980–2000 

are from Rawding (2001a); 1964–1979 data are from 

Norman (1982); Sanford (2003b). 

Hatchery notes, reference Hatchery data are part of the escapement data from Rawding 

(2001a). 

543
REFERENCES AND APPENDICES

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Harvest reference No harvest data available. 

Age notes, reference Age distribution for 1980–1990 and estimate based on 

average from 1991 to 2000. Age distribution data missing 

for 1993. Rawding (2001a). 

Population Mill Creek fall run 

Years of data, length of series 1980–2000, 21 years 

Abundance type, notes, reference Peak count. Abundance data are for adults and jacks. 

Estimates of spawner abundance are extrapolations made 

using peak count data and marking rate. Rawding (2001a). 

Hatchery notes, reference Hatchery data are part of the escapement data from Rawding 

(2001a). 

Harvest reference Coweeman River. PSC (2002). 

Age distribution for 1982–1990 based on an average of years 

1991–2000. Rawding (2001a) 

Age notes, reference 

Population Sandy River fall run 

Years of data, length of series 1988–2001, 14 years 

Abundance type, notes, reference Total from redd count. The estimate of spawning abundance 

is based on a one-time peak count of live fish on the Sandy 

River. The index area is 10 miles from the mouth of Gordon 

Creek to Lewis and Clark ramp. The number of fish is then 

multiplied by 2.5 to get the estimate (StreamNet, trend no. 

50070, http://www.streamet.org). Fish counts are provided 

in StreamNet (trend no. 57517). Surveys were not 

conducted prior to 1988. ODFW (1998a). 

Hatchery notes, reference McClure et al. (2003) reference ODFW (1998a) for 

proportion of natural spawners. 

Harvest notes, reference No harvest data available. 

Age notes, reference Generic fall-run age structure. Myers et al. (1998). 

Population Sandy River late fall run 

Years of data, length of series 1984–2001, 18 years 

Abundance type, reference Total from redd count (ODFW 1990a, 2002); Murtagh 

et al. (1997). 

Hatchery notes, reference McClure et al. (2003), reference ODFW (1998a) for 

proportion of natural spawners. 

Harvest notes, reference No harvest data available. 

Age notes, reference Generic fall-run age structure. Myers et al. (1998). 

544
APPENDIX A 

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Population Washougal River fall run 

Years of data, length of series 1964–2001, 38 years 

Abundance type, notes, reference Peak count. Abundance data are for adults and jacks. 

Estimates of spawner abundance are extrapolations made 

using peak count data and marking rate. Spawning data for 

1964–1979 are from Kreitman (1981); 1980–2000 are from 

Rawding (2001a); Sanford (2003b). 

Hatchery notes, reference Hatchery data are part of the escapement data from Rawding 

(2001a). 

Harvest reference stock Cowlitz Hatchery 

Harvest notes, reference Adult equivalent exploitation rate for Lewis River from 

D. Simmons.r

Age distribution for 1982–1990 based on an average for 

1991–2000. Rawding (2001a) 

Age notes, reference 

Population Kalama River spring run 

Years of data, length of series 1980–2001, 22 years 

Abundance type, notes, reference Peak count. Abundance data are for adults and jacks. 

Estimates of spawner abundance are extrapolations made 

using peak count data and marking rate. Rawding (2001a); 

Sanford (2003b). 

Hatchery notes, reference Hatchery data are part of the escapement data from Rawding 

(2001a). 

Harvest reference No harvest data available. 

Age reference No age data available. 

Population Lewis River spring run 

Years of data, length of series 1980–2001, 22 years 

Abundance type, notes, reference Peak count. Abundance data are for adults and jacks. 

Estimates of spawner abundance are extrapolations made 

using peak count data and marking rate. Rawding (2001a); 

Sanford (2003b) 

Hatchery notes, reference Hatchery data are part of the escapement data from Rawding 

(2001a). 

Harvest reference No harvest data available. 

Age reference No age data available. 

Population Upper Cowlitz River spring run 

Years of data, length of series 1980–2001, 22 years 

545
REFERENCES AND APPENDICES

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Abundance type, notes, reference Peak count. Abundance data are for adults and jacks. 

Estimates of spawner abundance are extrapolations made 

using peak count data and marking rate. Rawding (2001a); 

Sanford (2003b). 

Hatchery notes, reference Hatchery data are part of the escapement data from Rawding 

(2001a). 

Harvest reference No harvest data available. 

Age reference Myers et al. (1998). 

Population Youngs Bay fall run 

Years of data, length of series 1950–2001, 52 years 

Abundance type, reference Fish per mile. Fulop (2002, 2003). 

Population Big Creek fall run 

Years of data, length of series 1970–2001, 32 years 

Abundance type, reference Fish per mile. Fulop (2003). 

Population Clatskanie River fall run 

Years of data, length of series 1970–2001, 32 years 

Abundance type, reference Fish per mile. Fulop (2003). 

Upper Willamette River Chinook Salmon ESU 

Population Clackamas River spring run 

Years of data, length of series 1958–2002, 45 years 

Abundance type, notes, reference Dam/weir count. Data are dam counts for North Fork Dam; 

adults only, production is mixed. Cramer (2002b). 

Hatchery notes, reference Counts of hatchery vs. wild fish are for 2001–2002; the 

number of marked hatchery fish is estimated to be 50% 

(Cramer 2002a). 

Harvest reference No harvest data available. 

Age notes, reference Age distribution is taken from the upper Willamette Chinook 

salmon totals, not specific to Clackamas River spring-run 

Chinook. McClure et al. (2003). 

Population McKenzie River spring run 

Years of data, length of series 1970–2001, 32 years 

Abundance type, notes, reference Dam/weir count. Data come from dam counts at Leaburg 

Dam. Spawning also occurs below the dam. Kostow (2002). 

546
APPENDIX A 

Table A-2 continued. Chinook salmon time-series data sources. 

Data type Data source

Hatchery notes, reference Hatchery fish have only been 100% marked in recent years. 

The hatchery marks are not 100% detectable at the dam 

because a portion of the hatchery fish is double index marked 

to evaluate the fishery impact to wild fish. Double index 

marked means that the hatchery fish has a coded-wire tag but 

it is not externally marked (that is, no fin clip). Therefore, 

the fish “looks wild” both to the fisherman (who must release 

the fish) and in the raw dam count. The McKenzie fish 

managers therefore do several expansions to deal with these 

issues. Kostow (2002). 

Harvest notes No harvest data available. 

Age notes, reference Age distribution is taken from the Upper Willamette Chinook 

salmon ESU totals, not specific to McKenzie River springrun Chinook salmon. McClure et al. (2003). 

Population Sandy River spring run 

Years of data, length of series 1977–2001, 25 years 

Abundance type, notes, reference Dam/weir count. Abundance estimates only. Cramer 

(2002a). 

Hatchery reference No hatchery data. 

Harvest reference No harvest data available. 

Age reference No age data available. 

Years of data, length of series 1946–2001, 56 years 

Abundance type, notes, reference Dam/weir count. Data are for adults and jacks. Two 

additional references are Foster (2000, 2002). Howell 

(1986), Bennett (1986), Bennett and Foster (1990, 1994, 

1995), Foster (1998). 

Population Willamette Falls spring run 

Years of data, length of series 1946–2001, 56 years 

Abundance type, notes, reference Dam/weir count. Data are for adults and jacks. ODFW 

(1998b), Foster (1998, 2000). 

a R. Carmichael, ODFW, La Grande, OR. Pers. commun., January 2003. 

b

 C. Petrosky, IDFG, Fish Division, Boise, ID. Pers. commun., November 2002. 

c

 D. Simmons, NMFS, Lacey, WA. Pers. commun., 3 July 2003. 

d N. Sands, Northwest Fisheries Science Center, Seattle, WA. Pers. commun., 7 January 2002. e

 D. Simmons, NMFS, Lacey, WA. Pers. commun., 7 January 2002. f

 R. Hayman, Skagit Coop. BRT/Comanagers meeting to review draft ESU status report, NWFSC, Seattle, WA. 

Pers. commun. 28 March 2003. 

g

 J. Scott, WDFW, and D. Simmons, NMFS, Lacey, WA. Pers. commun., 12 March 2001. h

 D. Simmons, NMFS, Lacey, WA. Pers. commun., 31 July 2001. i

 D. Simmons, NMFS, and J. Scott, WDFW, Lacey, WA. Pers. commun., 12 March 2002. 

j

 T. Johnson, WDFW, Olympia, WA. Pers. commun., 27 March 2003. 

547
REFERENCES AND APPENDICES

k

 C. Kraemer, WDFW, Olympia, WA, and K. Rawson, Tulalip Tribal Nation, Tulalip, WA. Pers. commun., 19 

November 2002. 

l

 J. Scott, WDFW, and D. Simmons, NMFS, Lacey, WA. Pers. commun., 7 February 2002. 

m J. Scott, WDFW, Olympia, WA. Pers. commun. January 2002. 

n

 C. Kraemer, WDFW, Olympia, WA, and K. Rawson, Tulalip Tribal Nation, Tulalip, WA. Pers. commun., 9 

January 2002. 

o

 D. Simmons, NMFS, Lacey, WA. Pers. commun., 12 June 2003. p

 R. Hayman, Skagit River System Cooperative, La Conner, WA. Pers. commun., January 2002. 

q

 C. Phinney, Puyallup Indian Fisheries, Tacoma, WA. Pers. commun., 25 January 2001. 

r

 D. Simmons, NMFS, Lacey, WA. Pers. commun., 9 January 2002. 

548
APPENDIX A 

Table A-3. Lower Columbia River hatchery releases. 

Watershed Years Hatchery Stock Release site Total 

Lower Columbia River Fall-Run Chinook Salmon (Washington) 

1990–1994 Sea Resources Chinook River Chinook River 2,598,400

1990 Sea Resources Washougal Chinook River 629,500

Chinook River 

1997–2000 Sea Resources Chinook River Chinook River 820,627

1993 Lower Columbia Kalama Falls Deep River 49,400

1990–1994 Grays River Grays River Grays River 2,767,900

1991, 1993 Grays River Kalama Falls Grays River 1,332,380

1992 Grays River Spring Creek Grays River 1,107,000

1995–1997 Grays River Kalama Grays River 764,550

Grays River 

1996, 1997 Grays River Washougal Grays River 1,745,500

1990–1994 Elochoman Elochoman Elochoman River 17,809,719

1991 Elochoman Kalama Falls Elochoman River 1,046,700

1995 Beaver Creek Abernathy Beaver Creek 377,252

1997 Beaver Creek Big Creek Beaver Creek 1,096,198

1996–1999 Beaver Creek Elochoman Elochoman River 2,081,670

1995 Beaver Creek Kalama Beaver Creek 760,039

1995–2001 Elochoman Elochoman Elochoman River 15,280,038

1999 Elochoman Grays River Elochoman River 174,500

Elochoman River 

1997–1998 Elochoman Washougal Elochoman River 1,633,200

Lower Columbia 

River 

1996–1998 Cathlamet FFA Washougal Columbia River 1,132,500

Cowlitz River 1990–1994 Cowlitz Cowlitz Cowlitz River 28,757,600

1995–2001 Cowlitz Cowlitz Cowlitz River 42,322,920

1990–1993 Toutle Kalama Falls Green River 5,718,000

1991–1993 Toutle Toutle Green River 2,941,000

1994 Toutle Tule Green River 2,044,500

1990–1993 Toutle Washougal Green River 2,693,400

2000 North Toutle Elochoman Green River 618,266

1996 North Toutle Kalama Green River 1,588,937

1996–2001 North Toutle Toutle Green River 10,584,543

Toutle River 

1996 North Toutle Washougal Green River 633,414

1991–1994 Lower Kalama Kalama Kalama River 10,701,203

1990–1994 Kalama Falls Kalama Falls Kalama River 17,600,800

1996–2001 Fallert Creek Kalama Fallert Creek 13,998,602

Kalama River 

1995–2001 Kalama Falls Kalama Kalama River 20,198,653

1994 Washougal Kalama Falls Washougal 2,443,100

1992 Washougal Spring Creek Washougal 1,409,300

1991–1994 Washougal Washougal Washougal 27,002,103

2000 Washougal Elochoman Washougal 1,312,680

Washougal River 

1995–2001 Washougal Washougal Washougal 32,878,694

Spring Creek 1992 Ringold Little White 

Salmon 

Spring Creek 82,511

549
REFERENCES AND APPENDICES

Table A-3 continued. Lower Columbia River hatchery releases. 

Watershed Years Hatchery Stock Release site Total 

Lower Columbia River Fall-Run Chinook Salmon (Oregon) 

1991–1995 Astoria H.S. Big Creek Youngs Bay 15,500 

1991–1994 CEDC Rogue River Youngs Bay 394,382 

1991, 1992 STEP Big Creek Youngs Bay 13,758 

1992, 1993 STEP Klaskanine Youngs Bay 15,700 

1996–1998 STEP Big Creek Youngs Bay 63,050 

1997, 1998 STEP Unknown Youngs Bay 16,500 

1995–2002 Youngs Bay Rogue River Youngs Bay 4,248,147 

1996–1998 Youngs Bay URB Youngs Bay 828,884 

1991 STEP Unknown Lower Columbia 25,000 

1996, 1997 Tongue Point Rogue River Tongue Point 54,274 

1996, 1997 Tongue Point URB Tongue Point 299,715 

Lower Columbia 

River 

1995–1997 Blind Slough Rogue River Blind Slough 54,793 

Skipanon River 1992–1993 STEP Klaskanine Skipanon 3,550 

1996–1999 STEP Big Creek Skipanon 15,193 

Plympton Creek 1991 Big Creek Big Creek Plympton Creek 50,278 

1991–1994 Big Creek Big Creek Big Creek 34,675,446 

1991–1994 Big Creek Rogue River Big Creek 2,798,710 

1993 Big Creek Kalama Falls Big Creek 886,471 

1995–2002 Big Creek Big Creek Big Creek 40,633,091 

Big Creek 

1995–1996 Big Creek Rogue River Big Creek 1,530,550 

Klaskanine 1995 CEDC Rogue River Klaskanine 15,758 

River 1996–1999 Klaskanine Rogue River Klaskanine 3,694,245 

Wahkeena Pond 1991–1993 Bonneville URB Columbia River 1,183,764 

Johnson Creek 1994, 1995 Step Tanner Creek Johnson Creek 99,008 

1991 Bonneville Big Creek Tanner Creek 2,580,763 

1991–1994 Bonneville Tanner Creek Tanner Creek 32,862,338 

1991 Bonneville WA Tule Tanner Creek 1,534,122 

1991–1994 Bonneville URB Tanner Creek 26,877,822 

1993 Bonneville Kalama Falls Tanner Creek 1,505,421 

1995–1996 Bonneville Tanner Creek Tanner Creek 15,369,642 

1995–1996 Bonneville WA Tule Tanner Creek 10,922,745 

1995–2002 Bonneville URB Tanner Creek 43,729,497 

Tanner Creek 

2000–2001 Bonneville WA URB Tanner Creek 328,426 

Lower Columbia River Spring-Run Chinook Salmon (Washington) 

Deep River 1999–2001 Deep River Cowlitz Deep Creek 255,657

1991–1996 Abernathy NFH Abernathy 

Creek 

Abernathy 

Creek 

Abernathy 6,853,504

Creek 

1997–1999 Abernathy NFH Abernathy 

Creek 

Abernathy 

Creek 

1,223,647

1990–1994 Cowlitz Cowlitz Cowlitz River 9,016,451

1992–1994 Friends of 

Cowlitz 

Cowlitz Cowlitz River 115,800

1995–2001 Cowlitz Cowlitz Cowlitz River 8,870,002

Cowlitz River 

1995, 1997 Cowlitz Cowlitz Tilton River 3,074 adults

1996, 1999 Friends of 

Cowlitz 

Cowlitz Cowlitz River 53,800

550
APPENDIX A 

Table A-3 continued. Lower Columbia River hatchery releases. 

Watershed Years Hatchery Stock Release site Total

1991, 1993 Toutle Cowlitz Green River 641,382

1995 North Toutle Toutle Green River 1,412,100

1995 North Toutle Washougal Green River 1,086,100

Toutle River 

1995–2001 North Toutle Cowlitz Green River 766,740

1990–1993 Speelyai Lewis Lewis River 1,229,262

1994 Lewis River Kalama North Fork 

Lewis River 

975,700

1991, 1992 Lewis River Lewis Lewis River 1,885,900

1990–1994 Lewis River North Fork 

Lewis 

North Fork 

Lewis River 

1,801,800

1996 Fish First NP Lewis Lewis River 55,872

1997–2000 Fish First NP Lewis Lewis River 570,857

1996, 1998 Lewis River Lewis Lewis River 2,074,841

2001 Lewis River Lewis Lewis River 34 adults

1995–2001 Lewis River Lewis Lewis River 4,692,781

Lewis River 

2001 Speelyai Lewis Lewis River 566,373

1990–1994 Lower Kalama Kalama Hatchery Creek 2,455,252

1995–2001 Fallert Creek Kalama Fallert Creek 2,129,550

1998, 2000 Fallert Creek Lewis Fallert Creek 615,463

1999 Gobar Pond Kalama Gobar Creek 87,500

Kalama River 

1997, 2001 Kalama Falls Kalama Gobar Creek 332,281

1993 Ringold Carson Spring Creek 68,900

1993 Ringold Kalama Spring Creek 462,700

1990 Ringold Klickitat Spring Creek 40,264

1994 Ringold Little White 

Salmon 

Spring Creek 336,268

1993–1994 Ringold Ringold Spring Creek 596,274

Spring Creek 

1992–1994 Ringold Wind River Spring Creek 2,250,000

Wind River 1991–1996 Carson NFH Carson Wind River 13,350,658

1997–2001 Carson NFH Carson Wind River 7,096,346

1991–1994 Little White 

Salmon NFH 

Spring Creek Little White 

Salmon River 

2,757,539

1992 Willard NFH Carson Little White 

Salmon River 

869,952

1991–1994 Little White 

Salmon NFH 

Carson Little White 

Salmon River 

4,780,148

1997 Little White 

Salmon NFH 

Carson Little White 

Salmon River 

2,835,741

1998–2001 Little White 

Salmon NFH 

Little White 

Salmon 

Little White 

Salmon River 

4,272,833

Little White 

Salmon River 

1998–2001 Little White 

Salmon NFH 

URB-Mixed Little White 

Salmon River 

8,057,188

Drano Lake Abernathy 

NFH 

Spring Creek Drano Lake 40,756

1991 Spring Creek 

NFH 

URB-Bonn 

Dam 

Spring Creek Spring Creek 14,348,604

1991 Spring Creek 

NFH 

Clackamas Spring Creek 3,292,304

1992–1996 Spring Creek 

NFH 

Spring Creek Spring Creek 89,083,822

551
REFERENCES AND APPENDICES

Table A-3 continued. Lower Columbia River hatchery releases. 

Watershed Years Hatchery Stock Release site Total

1997–2001 Spring Creek 

NFH 

Spring Creek Spring Creek 70,435,986

Big White Salmon 

River 

1991–1996 Big White 

Salmon NFH 

Carson Big White 

Salmon River 

3,581,536

1997–1999 Big White 

Salmon NFH 

Carson Big White 

Salmon River 

2,795,464

2001 Big White 

Salmon NFH 

Methow Big White 

Salmon River 

1,238,764

1997 Spring Creek 

NFH 

Carson Big White 

Salmon River 

543,270

Deep River 1999–2001 Deep River Cowlitz Deep River 255,657

1991–1996 Abernathy 

NFH 

Abernathy 

Creek 

Abernathy 

Creek 

Abernathy Creek 6,853,504

1997–1999 Abernathy 

NFH 

Abernathy 

Creek 

Abernathy 

Creek 

1,223,647

1990–1994 Cowlitz Cowlitz Cowlitz River 9,016,451

1992–1994 Friends of 

Cowlitz 

Cowlitz Cowlitz River 115,800

1995–2001 Cowlitz Cowlitz Cowlitz River 8,870,002

1995, 1997 Cowlitz Cowlitz Tilton River 3,074 

adults

Cowlitz River 

1996, 1999 Friends of 

Cowlitz 

Cowlitz Cowlitz River 53,800

1991, 1993 Toutle Cowlitz Green River 641,382

1995 North Toutle Toutle Green River 1,412,100

1995 North Toutle Washougal Green River 1,086,100

Toutle River 

1995– 2001 North Toutle Cowlitz Green River 766,740

1990–1993 Speelyai Lewis Lewis River 1,229,262

1994 Lewis River Kalama North Fork 

Lewis River 

975,700

1991, 1992 Lewis River Lewis Lewis River 1,885,900

1990–1994 Lewis River North Fork 

Lewis 

North Fork 

Lewis River 

1,801,800

1996 Fish First NP Lewis Lewis River 55,872

1997–2000 Fish First NP Lewis Lewis River 570,857

1996, 1998 Lewis River Lewis Lewis River 2,074,841

2001 Lewis River Lewis Lewis River 34 Adults

1995–2001 Lewis River Lewis Lewis River 4,692,781

Lewis River 

2001 Speelyai Lewis Lewis River 566,373

1990–1994 Lower Kalama Kalama Hatchery Creek 2,455,252

1995–2001 Fallert Creek Kalama Fallert Creek 2,129,550

1998, 2000 Fallert Creek Lewis Fallert Creek 615,463

1999 Gobar Pond Kalama Gobar Creek 87,500

Kalama River 

1997, 2001 Kalama Falls Kalama Gobar Creek 332,281

1993 Ringold Carson Spring Creek 68,900

1993 Ringold Kalama Spring Creek 462,700

1990 Ringold Klickitat Spring Creek 40,264

Spring Creek 

1994 Ringold Little White 

Salmon 

Spring Creek 336,268

1993–1994 Ringold Ringold Spring Creek 596,274

1992–1994 Ringold Wind River Spring Creek 2,250,000

552
APPENDIX A 

Table A-3 continued. Lower Columbia River hatchery releases. 

Watershed Years Hatchery Stock Release site Total 

Wind River 1991–1996 Carson NFH Carson Wind River 13,350,658

1997–2001 Carson NFH Carson Wind River 7,096,346

1991–1994 Little White 

Salmon NFH 

Spring Creek Little White 

Salmon River 

2,757,539

1992 Willard NFH Carson Little White 

Salmon River 

869,952

1991–1994 Little White 

Salmon NFH 

Carson Little White 

Salmon River 

4,780,148

1997 Little White 

Salmon NFH 

Carson Little White 

Salmon River 

2,835,741

1998–2001 Little White 

Salmon NFH 

Little White 

Salmon 

Little White 

Salmon River 

4,272,833

Little White 

Salmon River 

1998–2001 Little White 

Salmon NFH 

URB-Mixed Little White 

Salmon River 

8,057,188

Drano Lake Abernathy 

NFH 

Spring Creek Drano Lake 40,756

1991 Spring Creek 

NFH 

URBBonneville 

Dam 

Spring Creek 14,348,604

1991 Spring Creek 

NFH 

Clackamas Spring Creek 3,292,304

1992–1996 Spring Creek 

NFH 

Spring Creek Spring Creek 89,083,822

Spring Creek 

1997–2001 Spring Creek 

NFH 

Spring Creek Spring Creek 70,435,986

1991–1996 Big White 

Salmon NFH 

Carson Big White 

Salmon River 

3,581,536

1997–1999 Big White 

Salmon NFH 

Carson Big White 

Salmon River 

2,795,464

2001 Big White 

Salmon NFH 

Methow Big White 

Salmon River 

1,238,764

Big White Salmon 

River 

1997 Spring Creek 

NFH 

Carson Big White 

Salmon River 

543,270

Lower Columbia River Spring-Run Chinook Salmon (Oregon)

Youngs Bay 1991–1992 CEDC Clackamas Youngs Bay 242,534 

1994 CEDC North Santiam Youngs Bay 301,361 

1992 CEDC Willamette Youngs Bay 301,786 

1996 Youngs Bay Clackamas Youngs Bay 97,945 

1995–1999 Youngs Bay Willamette Youngs Bay 3,114,060 

1996 Youngs Bay South Santiam Youngs Bay 276,493 

Lower Columbia 

River 

1996 Blind Slough South Santiam Blind Slough 199,389 

1995–2002 Blind Slough Willamette Blind Slough 1,457,655 

1996 Tongue Point South Santiam Tongue Point 242,319 

1997–2000 Tongue Point Willamette Tongue Point 1,029,850 

553
REFERENCES AND APPENDICES

Table A-3 continued. Lower Columbia River hatchery releases. 

Lower Columbia River Upriver Bright Chinook Salmon (Washington) Note: Upriver bright Chinook 

salmon are not in the Lower Columbia River Chinook salmon ESU.

1991–1993 Little White 

Salmon NFH 

Watershed Years Hatchery Stock Release site Total

Klaskanine River 1991 CEDC Clackamas South Fork 

Klaskanine 

119,627 

1994 CEDC North Santiam South Fork 

Klaskanine 

109,974 

1992, 1997 CEDC Willamette South Fork 

Klaskanine 

238,316 

1996 CEDC South Santiam South Fork 

Klaskanine 

76,618 

Multnomah 

Channel 

1997–1998 STEP McKenzie Little Willamette 123,134 

1991–1994 Clackamas Clackamas Sandy River 1,316,973 

1991–1993 Clackamas Clackamas Salmon River 594,656 

Sandy River 

1995–2002 Clackamas Clackamas Sandy River 3,539,458 

1991–1992 Bonneville Lookingglass Hood River 288,727 

1993–1995 Bonneville Deschutes Hood River 245,209 

1996–2001 Various (3) Deschutes Hood River 677,652 

2000–2002 Parkdale Wild origin Hood River 101,883 

Hood River 

2000 Parkdale Hood River Hood River 4,126

URB-Eggbank Little White 

Salmon River 

8,758,842 

1994–1996 Little White 

Salmon NFH 

Carson Little White 

Salmon River 

8,453,502 

Little White 

Salmon River 

1994–1996 Little White 

Salmon NFH 

Carson Little White 

Salmon River 

1,225

Adults 

Spring Creek 1994 Ringold URBBonneville 

Dam 

Spring Creek 4,217,491 

554
 

Appendix B: Steelhead 

Table B-1. Distribution of O. mykiss trout by category in the Columbia Basin steelhead ESUs. Only 

major barriers are noted; numerous small barriers, both natural and artificial, also exist. Many 

other natural barriers are present but have O. clarki trout, rather than O. mykiss trout, above them. 

O. mykiss trout distribution in areas of sympatry with steelhead may be restricted in some areas if 

native O. clarki trout are also in the basin. The generalized listing of basins and subbasins does 

not imply that these constitute single trout populations or that trout distribution is continuous 

throughout the areas listed. Detailed trout distribution is usually unknown and actual 

demographically independent trout populations have not been described. All current trout 

distributions are decreased from historical distributions. In particular, many mainstem and lower 

basin tributaries are no longer used but probably were historically. Many current trout 

populations are only in upper basins and are highly fragmented (from Kostow 2003). 

ESU 

Category 1 trout populations 

(sympatric) 

Category 2 trout populations 

(major natural barriers) 

Category 3 trout populations 

(major artificial barriers) 

Willamette River 

Pudding/Molalla 

Lower Santiam 

Calapooia 

Tualatin (Gales Creek) 

All populations upstream of 

Calapooia 

McKenzie 

North Fork Santiam (Big 

Cliff/Detroit Dams) 

South Fork Santiam (Green 

Middle Fork Willamette Peter Dam) 

Lower Columbia River 

Historical use of lower basins 

by trout may have been greater 

Wind 

Clackamas: 

Callowash 

Other areas *

Hood: 

West Fork 

Middle Fork 

Sandy*

Upper Cowlitz 

Upper Kalama 

Upper Lewis 

Upper Washougal 

Clackamas: 

Roaring River 

North Fork 

South Fork 

Memaloose*

Sandy: 

Little Sandy 

Salmon*

Some of the Columbia Gorge 

small tributaries 

Cowlitz (Mayfield Dam) 

Lewis (Merwin Dam) 

Sandy (Bull Run Dams) 

Middle Columbia River 

Historically all areas where 

steelhead are/were present. 

Trout distributions currently 

more restricted. 

Fifteenmile 

Eightmile 

Deschutes 

Klickitat 

Umatilla 

Upper Umatilla 

All natural barriers upstream of 

Klickitat and Deschutes basins 

Deschutes: 

White River 

Upper Deschutes (Big Falls) 

Upper North Fork Crooked River

John Day: 

Upper South Fork John Day 

Trout distributions currently 

more restricted than 

historically 

Little White Salmon (Conduit 

Dam) 

Deschutes (Pelton/Round Butte 

dams) 

Metolius 

Squaw Creek 

555
REFERENCES AND APPENDICES

Table B-1 continued. Distribution of O. mykiss trout by category in the Columbia Basin steelhead ESUs. 

ESU 

Category 1 trout populations 

(sympatric) 

Category 2 trout populations 

(major natural barriers) 

Category 3 trout populations 

(major artificial barriers) 

John Day 

Upper tributaries 

Walla Walla 

Upper tributaries 

Yakima 

Upper Yakima 

Naches 

Some other small tributaries 

Crooked River 

Umatilla (Irrigation dams) 

Willow Creek 

Butter Creek 

McKay Creek 

Snake River 

Potentially all areas that 

are/were 

used by steelhead. 

Tucannon 

Asotin 

Grande Ronde 

Imnaha 

Salmon found in about 43% 

of streams 

Clearwater 

Selway 

Other areas*

Palouse River 

Malad River 

Several Hells Canyon tributaries 

Upper Malheur basin “recent” 

disconnect from lower Malheur 

Lakes basin 

Trout distributions currently 

more restricted than historically

North Fork Clearwater 

(Dworshak Dam) 

Mainstem Snake (Hells Canyon 

Dam) 

Powder 

Burnt 

Malheur 

Owhyee 

Weiser 

Payette 

Boise 

Burneau 

Salmon Falls Creek 

Several small tributaries

Upper Columbia River 

Potentially all areas that 

are/were used by steelhead 

Wenatchee 

Lower Entiat 

Methow 

Okanogan 

Upper Entiat 

Upper Kootenay 

Okanogan: 

Enlow Falls*

Methow: 

Chewuch*

Lost 

Trout distributions currently 

more restricted than historically

Okanogan Basin: 

Conconully Dam/Enlow Dam*

Chief Joseph Dam 

Lower Spokane to Post Falls 

Sanpoil 

Several small tributaries 

Lower Pend Oreille to Z 

Canyon 

Columbia headwaters in 

Canada 

*

Expected presence of O. mykiss trout, but not confirmed by reliable sources. 

556
APPENDIX B 

Distribution, Abundance, and Stocking 

in Five California Steelhead ESUs 

Overview 

Table B-2 summarizes available information on the distribution, abundance, and stocking 

of O. mykiss above recent barriers (case 3) within the five listed steelhead ESUs in California. 

Populations above longstanding natural barriers (case 2) and below barriers (case 1) are not 

listed. Historically, coastal O. mykiss were broadly distributed in coastal watersheds and within 

the Central Valley (Behnke 1992, McEwan and Jackson 1996). Hatchery-produced O. mykiss

have been stocked for over 100 years (Behnke 1992) into streams and lakes throughout 

California by numerous state and federal agencies, private groups, and individuals. Given their 

broad historical range and widespread stocking over the last century, O. mykiss probably occur 

above all major recent barriers in California. However, little specific information is available on 

their distribution and abundance above these barriers, and stocking records are incomplete and 

not centralized. Because of these limitations, this table is necessarily incomplete and is intended 

to provide information at the level of the ESU. 

Methods and Scope 

Data were obtained from several sources. Barrier data were derived primarily from the 

California Department of Water Resources (DWR 1993) and the National Inventory of Dams 

(NID) compiled by the U.S. Army Corps of Engineers. Data for a few dams were missing from 

these databases and were obtained from other sources. These databases list over 1,400 unique 

dams on rivers and streams in California. Of these, fewer than 200 were classified as major 

barriers. A major barrier was arbitrarily defined as one that blocks or restricts access to greater 

than or equal to 100 sqaure miles of a watershed. Keystone barriers are the lowermost complete 

barrier to upstream migration in a watershed. For brevity, major barriers upstream of keystone 

barriers are not shown for the Central Valley ESU if there is no associated data on O. mykiss. A 

few minor barriers were included if information was available. 

Stream lengths were derived from the National Hydrography Dataset (NHD) produced by 

the U.S. Geological Survey and U.S. Environmental Protection Agency. Total stream length for 

a watershed (or ESU) is the sum for all streams within the watershed (or ESU), not just streams 

or watersheds that are listed. Above barrier totals are the sum for all streams above the barrier 

(watershed) or above listed keystone barriers (ESU). The above barrier totals include sections of 

streams that may be above longstanding natural barriers and exclude streams above smaller 

keystone barriers that are not listed in the table. 

Data on the distribution, abundance, and stocking of O. mykiss were obtained from the 

literature and from interviews with regional fish biologists with the CDFG, NMFS, and other 

agencies and academic institutions. Data on O. mykiss refer to fish that occur above the 

associated barrier but below the next upstream barrier, if it exists. Fish densities were converted 

from number per mile, but were not rounded to reflect true precision of estimate. 

557
REFERENCES AND APPENDICES

Table B-2. Distribution, abundance, and stocking of O. mykiss above major recent barriers (case 3 

situations) within five steelhead ESUs in California, listed by ESU and watershed. A major 

barrier blocks or restricts access to greater thanor equal to 100 square miles of a watershed. 

Names of keystone (lowermost complete) barriers are shown in bold; partial or seasonal barriers 

are in italics. SH = steelhead, RT = rainbow trout (usually means resident), ? = unknown. Blanks 

indicate no data. 

ESU Stream length O. mykiss above barrier

Basin 

Subbasin 

dam name /year built 

Total 

km 

Above 

barrier

km (%) Sourcea Distribution and abundance Hatchery stocking notes 

Northern California steelhead ESU 

 Mad River 1,188 

 Mad River: Robert W. 

Matthews Dam, 1962 

282 (24) Present above barrier. Low 

abundance (gets warm in 

summer). 

Stocking is ongoing, 

18,000/year, using stock 

from various hatcheries. 

3 

Eel River 8,654 No data 

 Eel River 

Van Arsdale Dam, 1907 1,106 (13) Steelhead, rainbow trout present

 Scott Dam, 1921 963 (11) Steelhead present 15, 4 

 

 

South Fork Eel River 

Benbow Dam, 1932 949 (11) Steelhead present 

ESU Total 15,496 1,245 (8)

Central California Coast steelhead ESU 

Russian River 3,129 

 Russian River 

Russian R. No 1, 1963 2,878 (92) No data 

 Healdsburg Rec, 1953 2,591 (83) No data 

 Dry Creek, Warm Springs 

Dam, 1982 

271 (9) Present in all tributaries. Stocked ≈1984–1987 by 

private hatchery (Warm 

Springs), Russian River 

steelhead from Warm 

Springs Hatchery released 

above Warm Springs 

Dam. 

5 

 East Fork Russian River 

Coyote Valley, 1959 

269 (9) Present Stocked 

Lagunitas Creek 202 

 Seeger, 1961 100 (50) Present in headwaters of 

Halleck Creek, probably in 

western portion of Nicasio 

Creek. 

5 

 Peters, 1954 61 (30) Present Ongoing stocking from 

Silverado Fisheries Base. 

5 

Alameda Creek 1,658 No data 

 Alameda Creek 

Rubber Dam 1 1,578 (95) Present Stocked 

 Rubber Dam 3, 1990 1,578 (95) No data 

 Calaveras Creek 

Calaveras, 1925 

283 (17) No data 

 Arroyo Valle 

Del Valle, 1968 

413 (25) No data Stocked 

Coyote Creek 757 No data 

 Coyote 

Standish, 1994 747 (99) No data 

 Coyote Creek 

Coyote Percol, 1934 532 (70) No data 

558
APPENDIX B 

Table B-2 continued. Distribution, abundance, and stocking of O. mykiss above major recent barriers 

(case 3 situations) within five steelhead ESUs in California, listed by ESU and watershed. A 

major barrier blocks or restricts access to greater thanor equal to 100 square miles of a watershed. 

Names of keystone (lowermost complete) barriers are shown in bold; partial or seasonal barriers 

are in italics. SH = steelhead, RT = rainbow trout (usually means resident), ? = unknown. Blanks 

indicate no data. 

ESU Stream length O. mykiss above barrier

Basin 

Subbasin 

dam name /year built 

Total 

km

Above 

barrier

km (%) Distribution and abundance Hatchery stocking notes Sourcea

Coyote River 

Leroy Anderson, 1950 487 (64) No data 

 Coyote Creek 

Coyote, 1936 278 (37) No data 

ESU total 11,447 3,026 (26)

South-Central California Coast steelhead ESU 

Salinas River 9,966 

 San Antonio River 

San Antonio, 1965 

1,102 (11) Present in reservoir, unknown 

if in stream. 

Stocking ongoing from 

Silverado Fisheries Base 

1, 6 

 Nacimiento River 

Nacimiento, 1957 

761 (8) Present; density is 330–390 

per km. 

Stocking ongoing from 

Silverado Fisheries Base 

6, 7 

 Salinas River 

Salinas, 1942 

293 (3) Present Stocking ongoing from 

Silverado Fisheries Base. 

Hatchery stock released at 

Lake Margarita marina. 

1, 6 

Carmel River 656 

 San Clemente, 1921 337 (51) Steelhead present 1, 6 

 Los Padres, 1949 128 (20) Steelhead, rainbow trout 

present. 

No hatchery stocking. 

Trap and truck of steelhead 

around Los Padres Dam for 

20 years. 

1, 6 

Big Sur Coastal 711 No data 

Estero Bay Coastal 1,521 No data 

 Old Creek 

Whale Rock, 1960 

44 42 (95) Present Stocking from Whale Rock 

Hatchery; 55,000 total 

1992–2002; broodfish 

taken from Whale Rock 

Reservoir. 

26 

Arroyo Grande Creek 

Lopez, 1969 

282 143 (51) Present Stocking ongoing from 

Silverado Fisheries Base 

1 

ESU Total 19,213 2,469 (13)

Southern California steelhead ESU 

Santa Maria River 5,775 

 Cuyama River 

Twitchell, 1958 

4,088 (71) Present in all tributaries Stocked 10–15 years ago 

(≈1987–1992) 

2 

Santa Ynez River 2,619 No data 

 Santa Ynez River 

Bradbury, 1953 

1,517 (58) Present in all tributaries Stocking ongoing from 

Fillmore Hatchery into 

Lake Cachuma. 

2, 8, 9 

 Gibraltar, 1920 721 (28) Present in all tributaries Stocking ongoing from 

Fillmore Hatchery. Not 

open to fishing? 

2, 9 

 Juncal, 1930 49 (2) Present in all tributaries. A lot 

of rainbow trout, up to 26". 

No stocking in last 30 

years. 

2, 9, 25

559
REFERENCES AND APPENDICES

Table B-2 continued. Distribution, abundance, and stocking of O. mykiss above major recent barriers 

(case 3 situations) within five steelhead ESUs in California, listed by ESU and watershed. A 

major barrier blocks or restricts access to greater thanor equal to 100 square miles of a 

watershed. Names of keystone (lowermost complete) barriers are shown in bold; partial or 

seasonal barriers are in italics. SH = steelhead, RT = rainbow trout (usually means resident), ? 

= unknown. Blanks indicate no data.

ESU Stream length O. mykiss above barrier

Basin 

Subbasin 

dam name /year built 

Total 

km

Above 

barrier

km (%) Distribution and abundance Hatchery stocking notes Sourcea

Ventura River 644 

 Coyote Creek 

Casitas, 1959 

131 (20) Present where water present, 

note seasonal streams. 

Stocking ongoing from 

Fillmore Hatchery; 32,000 

pounds in 2002. 

2 

 Matilija Creek 

Robles Diversion, 1958 

224 (35) Present 

 Matilija, 1949 157 (24) Present Stocked 5–6 years ago 

(≈1996–1997) from 

Fillmore Hatchery. 

2, 10 

Santa Clara River 3,851 

 Santa Clara River 

Vern Freeman Diversion, 

1991 

3,830 (99) Present 2, 16 

 Piru Creek 

Santa Felicia, 1955 

1,192 (31) Present in all tributaries; 

2,371–2,940 per km; 107–143 

(>8") per km; 0 (>12") per km 

Stocking ongoing from 

Fillmore Hatchery, Hot 

Creek strain, into Lake 

Piru and Frenchman’s Flat.

2 

 Pyramid, 1973 825 (21) Present in all tributaries Stocking ongoing from 

Fillmore Hatchery. 

2 

 Castaic Creek 

Castaic, 1973 

378 (10) Present in reservoir and where 

water present, note seasonal 

streams. 

Stocking ongoing into 

Castaic Lake and Castaic 

Lagoon (below dam). 

2 

Malibu Creek 

 Rindge 

269 

264 (98) No data 

 

Subtotal 15,490 7,463 (48)

Los Angeles River 1,220 

 Los Angeles River 

Sepulvedab, 1941 215 (18) No data 2 

 Tujunga Wash 

Hansen, 1940 408 (33

Present ≈5 miles or where water 

present. Few fish. 

Stocking ongoing from 

Fillmore Hatchery. 2 

San Gabriel River 1,270 No data 

 San Gabriel River 

Whittier Narrows,b 1957 1,192 (94) 

Present in reservoir, but 

probably not far upstream. 

Stocking ongoing from 

Fillmore Hatchery. 2 

 Santa Fe, 1949 692 (54) Present in reservoir, but 

probably not far upstream. 

Stocking ongoing from 

Fillmore Hatchery. 

2 

 Morris, 1935 626 (49) Present in reservoir. No, washdown from above 2 

 San Gabriel No 1, 1938 577 (45) Present in all tributaries where 

there is water, East Fork usually 

perennial. Density is 1,550–

2,706 per km; 129–198 (>8") 

per km; 0 (>12") per km. 

Stocking ongoing from 

Fillmore Hatchery. In 

West Fork below Cogswell, North Fork, and East 

Fork of San Gabriel River.

2, 19 

 Cogswell, 1935 121 (10) Present 2 

Santa Ana River 4,620 

 Santa Ana River 

Prado,b 1941 

3,158 (68) Present 

560
APPENDIX B 

Table B-2 continued. Distribution, abundance, and stocking of O. mykiss above major recent barriers 

(case 3 situations) within five steelhead ESUs in California, listed by ESU and watershed. A 

major barrier blocks or restricts access to greater thanor equal to 100 square miles of a 

watershed. Names of keystone (lowermost complete) barriers are shown in bold; partial or 

seasonal barriers are in italics. SH = steelhead, RT = rainbow trout (usually means resident), ? = 

unknown. Blanks indicate no data.

ESU Stream length O. mykiss above barrier

Basin 

Subbasin 

dam name /year built 

Total 

km

Above 

barrier

km (%) Distribution and abundance Hatchery stocking notes Sourcea

 Bear Creek Present at density 96–732 per 

km; 14–15 (>8") per km; 0 

(>12") per km. 

18, 19 

 Upper Santa Ana River Present at density 29–43 per 

km; 0–14 (>8") per km; 0 

(>12") per km. 

19 

 San Antonio Creek 

San Antonio, 1956 

73 (2)

 Santa Ana River 

Seven Oaks, under 

construction 

594 (13)

 Cajalco Creek 

Mathews, 1938 

95 (2)

Santa Margarita River 1,604 

 Temecula Creek 

Vail, 1949 

655 (41) Present Private stocking 2 

San Luis Rey River 

 Henshaw, 1923 

1,184 447 (38) Stocking is ongoing from 

Mojave Hatchery into 

West Fork of San Luis Rey 

River. 

2 

San Dieguito River 

 Lake Hodges, 1918 

693 618 (89) None Not stocked. Bass and 

catfish in Lake Hodges 

2 

San Diego River 

 El Capitan, 1934 

1,013 558 (55) Present in reservoir: few fish. No hatchery stocking. 2 

Sweetwater River 

 Sweetwater Main, 1888 

440 367 (83) Stocking is ongoing 2 

Otay River 

 Savage, 1919 

410 333 (81)

Tijuana Riverd 734 

 Cottonwood Creek 

Barrett, 1922 

506

 Morena, 1912 210

ESU total 31,964 15,414 (48)

Central Valley steelhead ESU 

Sacramento River 52,206 

 Red Bluff Diversion, 1964 14,261 (27) SH 

 Anderson Cottonwood, 

1917 

9,224 (18) SH 

 Keswick, 1950 9,189 (18) Present Steelhead from below dam 

are transported above dam.

 Shasta, 1945 9,106 (17) Present See below. 

Upper Sacramento 568 

561
REFERENCES AND APPENDICES

Table B-2 continued. Distribution, abundance, and stocking of O. mykiss above major recent barriers 

(case 3 situations) within five steelhead ESUs in California, listed by ESU and watershed. A 

major barrier blocks or restricts access to greater thanor equal to 100 square miles of a 

watershed. Names of keystone (lowermost complete) barriers are shown in bold; partial or 

seasonal barriers are in italics. SH = steelhead, RT = rainbow trout (usually means resident), ? = 

unknown. Blanks indicate no data.

ESU Stream length O. mykiss above barrier

Basin 

Subbasin 

dam name /year built 

Total 

km

Above 

barrier

km (%) Distribution and abundance Hatchery stocking notes Sourcea

 Shasta, 1945 Present population is 4,163–

5,468 (fish kill); 420–1,670 

(>4") 

Stocking from Mt. Shasta; 

Sacramento and McCloud 

River stocks. Average was 

15,000 from 1994 to 1998; 

stocked at least since 1930, 

average of ≈80,000/year; 

maximum of 4M RT 

planted in 1936. 

14 

 Box Canyon, 1969 127 (22) Yes 

McCloud River 949 

 Shasta, 1945 Present density is 2,361 (>5") 3 

 McCloud, 1965 474 (50) Present in all tributaries; 1,864 

in Squaw Valley Creek. 

Stocking is ongoing below 

McCloud Falls, ≈7 years 

ago (≈1994) above falls; 

15,000/year into McCloud 

reservoir 

3 

Pit River 6,979 

 Shasta, 1945 Present 

 Fall River 

Pit No 1 Diversion, 1922 

Present density is 1,021–2,541 

(>6") 

20 

 Pit No 1 Forebay, 1947 Present 

 Hat Creek Present density is 159–2,539 

(>8"); 32–1,335 (>12") 

17 

 Burney 

Hat Cr. No 2 Diversion, 

1942 

 Clear Creek 

Whiskeytown, 1963 

462 377 (82) Present in Whiskey and Clear 

Creeks. Density is 1,553–

3,107 per km. 

Stocking is ongoing from 

private hatchery. 

Stony Creek 2,707 

 Stony Creek 

Stony Creek Gravel, 1906 

 Black Butte, 1963 2,427 (90) Presently migrate through 

Stony and Grindstone creeks, 

too warm in summer. 

12 

 Stony Gorge, 1928 Present in all tributaries. Stocking is ongoing. 12 

 Little Stony Creek 

East Park, 1910 

Present seasonally in Trout 

and Stony creeks. 

Stocked 12 

Cache Creek 3,362 

 Cache Creek 

Cache Creek Settling 

Basin 

3,362 (100)

Putah Creek 1,200 

 Putah Creek 

Putah Diversion, 1957 

1,087 (91)

 Monticello 1,010 (84)

Feather River 1957 9,094 

562
APPENDIX B 

Table B-2 continued. Distribution, abundance, and stocking of O. mykiss above major recent barriers 

(case 3 situations) within five steelhead ESUs in California, listed by ESU and watershed. A 

major barrier blocks or restricts access to greater thanor equal to 100 square miles of a 

watershed. Names of keystone (lowermost complete) barriers are shown in bold; partial or 

seasonal barriers are in italics. SH = steelhead, RT = rainbow trout (usually means resident), ? = 

unknown. Blanks indicate no data.

ESU Stream length O. mykiss above barrier

Basin 

Subbasin 

dam name /year built 

Total 

km

Above 

barrier

km (%) Distribution and abundance Hatchery stocking notes Sourcea

 Feather River 

Thermalito Diversion, 

1967 

 Feather River Hatchery, 

1964 

 Oroville, 1968 7,702 (85)

 North Fork Feather River 

Poe, 1959 

Present Stocked at North Fork 

below Lake Almanor; 

rotenoned at least 3 times. 

11 

 Lake Almanor, 1927 Present Stocking is ongoing; Eagle 

Lake strain 80,000/year 

during last 15 years. 

11 

 Bucks Creek 

Bucks Storage, 1928 

Present Stocking is ongoing at 

15,000–30,000/year. 

11 

 Middle Fork Feather River Present Stocked above wild trout 

section of Middle Fork. 

11 

 Nelson Creek Present density is 155–621 

(>6"). 

13 

Yuba River 3,510 

 Yuba River 

Englebright1941 

2,923 (83)

Bear River 1,180 

 Camp Far West1963 719 (61)

American River 4,480 

 American River 

Nimbus, 1955 

4,351 (97)

 Rubicon River Yes 

 Cosumnes River 

Granlees,c

 1921 

2,426 1,322 (54) 22 

Mokelumne River 1,877 

 Mokelumne River 

Woodbridge Diversion, 

1910 

1,858 (99)

 Camanche, 1963 1,800 (96)

 Calaveras River 

New Hogan, 1963 

1,740 1,277 (73)

Stanislaus River 3,269 

 Stanislaus River 

Goodwin, 1912 

3,074 (94)

Tuolumne River 3,362 

 Tuolumne River 

La Grange, 1894 

3,170 (94)

 Clavey River Present density is 1,317 per 

km. 

21 

Merced River 2,574 

 Merced River 

Crocker Diversion, 1910 

2,129 (83)

Subtotal 73,558 43,587 (59)

563
REFERENCES AND APPENDICES

Table B-2 continued. Distribution, abundance, and stocking of O. mykiss above major recent barriers 

(case 3 situations) within five steelhead ESUs in California, listed by ESU and watershed. A 

major barrier blocks or restricts access to greater thanor equal to 100 square miles of a 

watershed. Names of keystone (lowermost complete) barriers are shown in bold; partial or 

seasonal barriers are in italics. SH = steelhead, RT = rainbow trout (usually means resident), ? = 

unknown. Blanks indicate no data.

ESU Stream length O. mykiss above barrier

Basin 

Subbasin 

dam name /year built 

Total 

km

Above 

barrier

km (%) Distribution and abundance Hatchery stocking notes Sourcea

San Joaquin River 3,238 

 San Joaquin River 

Mendota Diversion, 1917 

 2,876 (89)

 

 Friant, 1942 

Upper Middle Fork San 

Joaquin 

Present density is 273–2,985 

per km; 119–695 (>6") per km.

Stocked; RT probably not 

native 

23 

Kings River 3,570 

 Kings River 

Pine Flat 1954 

2,819 (79)

Kern River 4,467 

 Kern River 

Diversion No. 11906 

3,952 (88)

 Isabella, 1953 3,547 (79) Present density is 43–620. Stocked; Kern River 

Planting Base; 

50,500 lb/year above 

Isabella. 

24 

ESU total 103,504 53,234 (51) a

 Sources: 1 Jennifer Nelson, CDFG, Yountville, CA. Pers. commun., 12 November 2002. 2 Dwayne Maxwell, CDFG, Los Alamitos, CA. Pers. commun., 15 January 2003. 3 CDFG Region 1 biologists (Mike Dean, Mike Berry, Randy Benthin, Bob McAllister, Bill Jong, Phil Bairrington), 

Redding, CA. Pers. commun., 2 December 2002. 4 Scott Downie, CDFG, Fortuna, CA. Pers. commun., 25 January 2003.

5 Bill Cox, CDFG, Yountville, CA. Pers. commun., 12 December 2002.

6 Mike Hill, CDFG, Monterey, CA. Pers. commun., 1 June 2003.

7 Joel Casagrande, Watershed Institute, CSUMB, Seaside, CA. Pers. commun., 2 March 2003. 8 Mauricio Cardenas, CDFG, Ojai, CA. Pers. commun., 16 November 2002. 9 Scott Engblom, Cachuma Operation and Maintenance Board, Santa Barbara, CA. Pers. commun., 2 April 2003. 10 Rick Rogers, NMFS, Arcata, CA. Pers. commun., 3 February 2003. 11 Ken Kundargi, CDFG, Chico, CA. Pers. commun., 18 November 2002. 12 Emil Ekman, USFS, Mendocino National Forest, Willows, CA. Pers. commun., 12 December 2002. 13 CDFG (1979). 14 CDFG (2000b. 15 Jones (2001). 16 McEwan and Jackson (1996). 17 Deinstadt and Berry (1999). 18 Deinstadt et al. (1993). 19 Deinstadt et al. (1990). 20 Rode and Weidlein (1986). 21 Robertson (1985). 22 Yoshiyama et al. (2001). 23 Deinstadt et al. (1995). 24 Stephens et al. (1995). b Extensive portions of river below dam are channelized or concrete apron. c Granlees Dam is not considered a keystone barrier for steelhead, impassable natural falls below dam. d Portion in California.

564
APPENDIX B 

Table B-3. SSHAG (2003) categorizations of hatchery populations of nine steelhead ESUs reviewed. 

ESU Stock Run Basin 

SSHAG 

category*

Snake River Wallowa Summer Wallowa 3c 

Cottonwood Summer Grande Ronde 3c 

Little Sheep Creek Summer Imnaha 2a 

Oxbow Summer Snake 3c 

Sawtooth Summer Salmon 3c 

Pahsimeroi Summer Salmon 3c 

Dworshak Summer Clearwater 2a 

Lyons Ferry Summer Snake 3c or 4 

Tucannon (Lyons Ferry) Summer Tucannon 3c or 4 

Tucannon (new) Summer Tucannon 1a 

Curl Lake Summer Snake 3 or 4 

Upper Columbia River Wells Summer Upper Columbia 2b 

Wenatchee Summer Wenatchee 1b 

Middle Columbia River Deschutes (#66) Summer Deschutes 2a or 2c 

Umatilla (#91) Summer Umatilla 1a 

Dayton Pond Summer Touchet 4 

Dayton Pond (new) Summer Touchet 1a 

Lower Columbia River Skamania Summer Washougal 4 

Sandy (ODFW #11) Winter Sandy 1a 

Clackamas (#122) Winter Clackamas 1a 

Hood (ODFW #50) Winter Hood 1a 

Hood (ODFW #50) Summer Hood 1a 

Big Creek/Eagle Creek Winter Clackamas 4 

Chambers Creek Winter various 4 

Cowlitz Late-winter Cowlitz 2a 

Kalama Winter Kalama 1a 

Kalama Summer Kalama 1a 

Upper Willamette River Skamania (#24) Summer Santiam 4 

Northern California Mad River Winter Mad 3c 

Yager Creek Winter Yager 1a 

North Fork Gualala Winter Gualala 1a 

Central California Coast Don Clausen Winter Russian 2a 

Monterey Bay Winter Scott Creek 1a 

South-Central California Coast Whale Rock Winter Old Creek 1a or 2a 

California Central Valley Coleman NFH Winter Sacramento 2a 

Feather River Winter Feather 2a 

Nimbus Hatchery Winter American 4 

Mokelumne Hatchery Winter Mokelumne 4 *

 See subsection, Artificial Propagation, in Section 1, Introduction, for explanation of the categories. 

565
REFERENCES AND APPENDICES

Table B-4. Steelhead time-series references. 

Data type Data source 

Snake River Steelhead ESU 

Population Snake River Steelhead (total) 

Years of data, length of series 1980–2001, 22 years 

Abundance type Total live count 

Abundance and hatchery reference E. Holmes, unpublished data (available from E. Holmes, 

NWFSC, 2725 Montlake Blvd. E., Seattle, WA 98112) 

Harvest reference Yuen (2002) 

Age notes, reference E. Holmes, unpublished data (available from E. Holmes, 

NWFSC, 2725 Montlake Blvd. E., Seattle, WA 98112) 

Population Imnaha River (Zumwalt/Camp Creek) 

Years of data, length of series 1974–2000, 27 years 

Abundance type, reference Redds per mile. Chilcote (2002). 

Hatchery and harvest reference Chilcote (2001) 

Age notes, reference Average. Chilcote (2001). 

Population Camp Creek (Imnaha) 

Years of data, length of series 1974–2002, 29 years 

Abundance type Total live count 

Abundance, hatchery, 

and harvest reference 

Chilcote (2002) 

Age notes, reference Average. Used Grande Ronde River aggregate. 

Population Upper Grande Ronde River 

Years of data, length of series 1967–2000, 34 years 

Abundance type Redds per mile 

Abundance, hatchery, 

and harvest reference 

Chilcote (2001) 

Age notes, reference Average. Chilcote (2001) 

Population Joseph Creek 

Years of data, length of series 1974–2002, 29 years 

Abundance type Total live count 

Abundance, hatchery, 

and harvest reference 

Chilcote (2002) 

Age notes, reference Average. Chilcote (2002). 

Population Little Sheep Creek (Imnaha River) hatchery 

Years of data, length of series 1985–2002, 18 years 

Abundance type, reference Total live count, Chilcote (2002). 

Hatchery reference Chilcote (2002) 

Population Little Sheep Creek (Imnaha River) wild 

Years of data, length of series 1985–2002, 18 years 

Abundance type, reference Total live count. Chilcote (2002). 

Hatchery and harvest reference Chilcote (2002) 

Age notes, reference Average. Chilcote (2002). 

566
APPENDIX B 

Table B-4 continued. Steelhead time-series references. 

Data type Data source

Population Snake River A-run total 

Years of data, length of series 1985–2001, 17 years 

Abundance type Total live count 

Abundance and hatchery reference Yuen (2002) 

Harvest and age reference Yuen (2002) 

Age notes Yearly 

Population Snake River B-run total 

Years of data, length of series 1985–2001, 17 years 

Abundance type Total live count 

Abundance and hatchery reference Yuen (2002) 

Harvest and age reference Yuen (2002) 

Age notes Yearly 

Population Tucannon River 

Years of data, length of series 1987–2001, 13 years 

Abundance type Total live count 

Abundance reference Gallinat et al. (2001); 2001 estimate from M. Shuck.a

Hatchery reference Gallinat et al. (2001) 

Harvest reference Yuen (2002) 

Age notes, reference Average. Gallinat et al. (2001) 

Population Wallowa River (Grande Ronde River) 

Years of data, length of series 1965–1996, 31 years 

Abundance type Redds per mile 

Population Asotin Creek 

Years of data, length of series 1986–2001, 13 years 

Abundance type Expanded redd count 

Abundance reference M. Schucka

 

Upper Columbia Steelhead 

Population Above Wells Dam 

Years of data, length of series 1976–2001, 26 years 

Abundance type, reference Total live count (Cooney 2001) 

Hatchery reference Douglas PUD, Wells Dam broodstock sampling 

Harvest reference Cooney (2001); mainstem harvest rates from Yuen (2002); 

tributary rates from Brown (1995). 

Age notes, reference Yearly. Cooney (2001); Brown (1995); annual update 

memos for Priest Rapids steelhead sampling program from 

WDFW (Fish Program, 600 Capitol Way N., Olympia, WA 

98501). 

Population Wenatchee and Entiat rivers 

Years of data, length of series 1976–2001, 26 years 

Abundance type, reference Total live count (Cooney 2001) 

567
REFERENCES AND APPENDICES

Table B-4 continued. Steelhead time-series references. 

Data type Data source

Hatchery reference Cooney (2001); Brown (1995); annual update memos for 

Priest Rapids steelhead sampling program from WDFW (Fish 

Program, 600 Capitol Way N., Olympia, WA 98501). 

Harvest reference Cooney (2001); mainstem harvest rates from Yuen (2002); 

tributary rates from Brown (1995). 

Age notes, reference Yearly. Cooney (2001); WDFW, Priest Rapids steelhead 

sampling program 

Population Methow River 

Years of data, length of series 1976–2001, 26 years 

Abundance type, reference Total live count for years 1999–2001. Cooney (2001). 

Hatchery reference Douglas County PUD, Wells Dam broodstock sampling 

Harvest reference Cooney (2001); mainstem harvest rates from Yuen (2002); 

tributary rates from Brown (1995). 

Age notes, reference Yearly. Cooney (2001); Brown (1995); annual update 

memos for Priest Rapids steelhead sampling program from 

WDFW (Fish Program, 600 Capitol Way N., Olympia, WA). 

Population John Day River, upper north fork 

Years of data, length of series 1977–2002, 26 years 

Abundance type, notes, reference Redds per mile. Chilcote (2001, 2002) 

Hatchery reference E. Holmes, unpublished data (available from E. Holmes, 

NWFSC, 2725 Montlake Blvd. E., Seattle, WA 98112) 

Harvest reference Chilcote (2002) 

Age notes, reference Average. Chilcote (2001). 

Population John Day River, middle fork 

Years of data, length of series 1974–2001, 28 years 

Abundance type, notes, reference Redds per mile. Chilcote (2001, 2002) 

Hatchery reference E. Holmes, unpublished data (available from E. Holmes, 

NWFSC, 2725 Montlake Blvd. E., Seattle, WA 98112). 

Harvest reference Chilcote (2002) 

Age notes, reference Average. Chilcote (2001). 

Population Deschutes River 

Years of data, length of series 1978–2002, 25 years 

Abundance type, reference Dam count (Sherars Dam). Chilcote (2002). 

Hatchery and harvest reference Chilcote (2002) 

Age notes, reference Average. Chilcote (2001). 

Population Fifteenmile Creek (winter) 

Years of data, length of series 1964–2001, 24 years 

Abundance type, reference Redds per mile. StreamNet (http://www.streamet.org). 

Hatchery reference No annual sampling, assumed natural returns 

Harvest reference Chilcote (2001) 

Age notes, reference Average. Chilcote (2001). 

568
APPENDIX B 

Table B-4 continued. Steelhead time-series references. 

Data type Data source

Population John Day River, lower main stem 

Years of data, length of series 1965–2002, 37 years 

Abundance type, notes, reference Redds per mile. Chilcote (2001, 2002). 

Hatchery reference Chilcote (2001) 

Harvest reference Chilcote (2002) 

Age notes, reference Average. Chilcote (2001). 

Population John Day River, upper main stem 

Years of data, length of series 1974–2002, 29 years 

Abundance type, reference Total live count. Chilcote (2002). 

Hatchery and harvest reference Chilcote (2002) 

Age notes, reference Average. Chilcote (2001). 

Population Shitike Creek (Deschutes) 

Years of data, length of series 1976–2002, 26 years 

Abundance type, reference Redds per mile. Chilcote (2002, 2001). 

Age notes, reference Average. Used Deschutes River ages. 

Population South Fork John Day River 

Years of data, length of series 1974–2002, 29 years 

Abundance type, notes, reference Redds per mile. Chilcote (2002, 2001) 

Hatchery reference Chilcote (2001) 

Harvest reference Chilcote (2002) 

Age notes, reference Average. Chilcote (2001). 

Population Touchet River 

Years of data, length of series 1987–2001, 13 years 

Abundance type, reference Total live count. Leland (2003); Bumgarner (2002) for data 

years 1996–2001, 

Hatchery reference StreamNet (http://www.streamet.org) : Touchet River natural 

(180,065) divided by total (180,065 + 180,002) 

Harvest reference Mainstem harvest rates from Yuen (2002); tributary rates 

from Brown 1995. 

Age notes Average 

Population Umatilla River 

Years of data, length of series 1966–2002, 35 years 

Abundance type, reference Total live count. StreamNet (1966–2000, available online at 

http://www.streamnet.org); M. Chilcote.b

Hatchery and harvest reference Chilcote (2002) 

Age notes, reference Average. Chilcote (2002). 

Population Lower North Fork John Day River 

Years of data, length of series 1976–2002, 27 years 

Abundance type Redds per mile 

Abundance notes, reference Updated spreadsheets. Chilcote (2002, 2001). 

569
REFERENCES AND APPENDICES

Table B-4 continued. Steelhead time-series references. 

Data type Data source

Hatchery and harvest reference Chilcote (2002) 

Age notes, reference Average. Chilcote (2002). 

Population Walla Walla River 

Years of data, length of series 1993–2000, 8 years 

Abundance type, reference Total live count. M. Chilcote.b

Hatchery and harvest reference Chilcote (2001) 

Age notes, reference Average. Chilcote (2001). 

Population Warm Springs National Fish Hatchery 

Years of data, length of series 1980–1999, 20 years 

Abundance type, reference Total live count. Chilcote (2001). 

Hatchery and harvest reference Chilcote (2001) 

Age notes, reference Average. Chilcote (2001). 

Population Yakima River 

Years of data, length of series 1980–2001, 23 years 

Abundance type Total live count 

Abundance and hatchery reference Leland (2002)

Harvest reference Table 4-3 in U.S. Bureau of Reclamation (2000) 

Age notes, reference Average (Leland 2003) 

Years of data, length of series 1990–2002, 9 years 

Abundance type, reference Redd countc

Hatchery notes, reference No recent year data available 

Lower Columbia River Steelhead ESU 

Population Hood River summer run 

Years of data, length of series 1992–2000, 9 years 

Abundance type, notes, reference Dam/weir count. Dam counts at Powerdale Dam. 

Gorman (unpublished data). 

Hatchery reference Gorman (unpublished data) 

Harvest reference No harvest data available. 

Age notes, reference Repeat % total ranged from 2% to 10%. Gorman 

(unpublished data). 

Population Kalama River summer run 

Years of data, length of series 1977–2003, 27 years 

Abundance type, notes, reference Trap count. Trap count plus correction estimate for jumpers. 

Rawding (2002). 

Hatchery notes, reference Work done at River Mile 10 above the two hatcheries to 

minimize handling of hatchery fish. Substantial rearing may 

occur below; trapping takes place during spring. Rawding 

(2002). 

Harvest reference Rawding (2002) 

Age notes, reference From 1998 on, no scales have been aged, and mean ages are 

used for these years. Rawding (2002). 

570
APPENDIX B 

Table B-4 continued. Steelhead time-series references. 

Data type Data source

Population Washougal River summer run 

Years of data, length of series 1986–2003, 18 years 

Abundance type, reference Index. WDFW (1997); Rawding (2002). 

Hatchery reference No hatchery data 

Harvest reference No harvest data available 

Age notes, reference Generic sum age structure. Busby et al. (1996), Chilcote 

(2001), Hulett et al. (1995). 

Population Wind River summer run 

Years of data, length of series 1989–2003, 15 years 

Abundance type, notes, reference Mark-recapture. Estimates made from mark-recapture from 

trap efficiency method. Adult trap at Shipherd Falls, but 

adult population is estimated by mark-recapture, since fish 

jump the falls. Not able to differentiate winter- and summerrun steelhead smolts. Rawding (2001b, 2002). 

Hatchery, harvest, age reference Rawding (2001b) 

Population Clackamas River winter run 

Years of data, length of series 1958–2001, 44 years 

Abundance type, notes, reference Dam/weir count. Cramer (2002a, 2002c). 

Hatchery notes, reference Pre-1997 wild fraction determined by run timing; all fish 

counted on or after March 1 assumed to be wild. Additional 

reference for 1997–2001 from D. Cramer;d

 PGE has numbers 

for wild and hatchery fish as of 1996–1997 run; all winterrun steelhead trapped and identified as wild or hatchery. 

Cramer (2002a). 

Harvest notes, reference Reconstructed run year estimates from punch cards for 

steelhead from M. Chilcote.e

Age notes, reference Generic sum age structure. Busby et al. (1996), Chilcote 

(2001), Hulett et al. (1995) 

Population Upper Cowlitz, Cispus, and Tilton winter run 

Years of data, length of series 2002, 1 year 

Abundance type, notes, reference Dam/weir count. Cramer (2002c), Serl and Morrill (2002). 

Population East Fork Lewis River winter run 

Years of data, length of series 1985–1994, 10 years 

Abundance type, notes, reference Peak count. Natural population only; East Fork Lewis River, 

tributary to Lewis River from river mile 0.0 to 41.8. Johnson 

and Cooper (1995). 

Hatchery reference Busby et al. (1996) 

Harvest reference No harvest data available. 

Age reference Busby et al. (1996), Chilcote (2001), Hulett et al. (1995) 

Population Hood River summer run 

Years of data, length of series 1992–2000, 9 years 

571
REFERENCES AND APPENDICES

Table B-4 continued. Steelhead time-series references. 

Data type Data source

Abundance type, notes, reference Dam/weir count. Dam counts at Powerdale Dam. Gorman 

(unpublished data). 

Hatchery reference Gorman (unpublished data) 

Harvest reference No harvest data available. 

Age reference Gorman (unpublished data) 

Population Kalama River winter run 

Years of data, length of series 1977–2002, 26 years 

Abundance type, notes, reference Trap count. Trap count plus correction estimate for jumpers. 

Rawding (2001b, 2002). 

Hatchery notes, reference Work done at river mile 10 above the two hatcheries to 

minimize handling of hatchery fish. Substantial rearing may 

occur below; trapping takes place during spring. Rawding 

(2001b). 

Harvest reference Leland (2003) 

Age notes, reference From 1998 on no scales have been aged, and mean ages are 

used for these years. Rawding (2001b). 

Population North Fork Toutle River winter run 

Years of data, length of series 1989–2002, 14 years 

Abundance type, notes, reference Total from redd count; 100% trap count. Rawding (2001b, 

2002). 

Hatchery and age reference Rawding (2001b) 

Harvest reference Rawding (2002) 

Population Sandy River winter run 

Years of data, length of series 1978–2001, 24 years 

Abundance type, notes, reference Dam/weir count. Dam counts made at Marmot Dam. 

Cramer (2002d). 

Hatchery notes, reference Used average hatchery fraction from 1978 to 1997 for years 

1998–2001. Chilcote (1998). 

Harvest notes, reference Natural population catch is determined by multiplying 

harvest by wild fraction. Berry (1978). 

Age notes, reference Generic winter age structure. Busby et al. (1996), Chilcote 

(1998), Hulett et al. (1995). 

Population South Fork Toutle River winter run 

Years of data, length of series 1981–2002, 19 years 

Abundance type, notes, reference Redd surveys. Winter-run steelhead in South Fork Toutle 

River are by redd surveys from 15 March to 31 May. Redd 

surveys assume 100% of the redds are seen; only wild 

steelhead spawn after March 15, sex ratio is 1:1, and each 

redd represents 0.8 females. Assumed stray rate is 2%. 

Leland (2003), Rawding (2001b, 2002). 

Hatchery and harvest reference Rawding (2001b) 

572
APPENDIX B 

Table B-4 continued. Steelhead time-series references. 

Data type Data source

Age notes, reference Applied Kalama estimates to South Fork Toutle River. 

Pooled ages 6 and 7 into age 6 to increase redd survey sample 

size. Rawding (2001b). 

Population Washougal River winter run 

Years of data, length of series 1991–2002, 5 years 

Abundance type, reference Redd index. Leland (2003), WDF and WDW (1993). 

Hatchery notes, reference Reports little hatchery impact. Leland (2003), WDF and 

WDW (1993). 

Harvest reference No harvest data available. 

Age notes, reference Generic winter age structure. Busby et al. (1996), Chilcote 

(2001), Hulett et al. 1995. 

Population Coweeman River winter run 

Years of data, length of series 1987–2002, 16 years 

Abundance type, notes, reference Redd surveys. Winter-run steelhead estimates in the 

Coweeman River are by redd surveys from March 15 to May 

31. Redd surveys assume 100% of redds are seen; only wild 

steelhead spawn after March 15, sex ratio is 1:1, and each 

redd represents 0.8 females. Leland (2003), Rawding 

(2001b, 2002). 

Hatchery notes, reference Data on hatchery fraction for 1987–1989 were provided by 

Leland (2003). Estimate for 1990–2002 based on estimate 

from Rawding (2001b) of 50% hatchery fish. Leland (2003), 

Rawding (2001b). 

Harvest reference Leland (2003), Rawding (2001b) 

Age notes, reference Only age structure data is for winter run in North Fork Toutle 

and Kalama, and summer run in the Kalama. Age structure is 

very similar in Toutle and Kalama river winter run. Toutle 

River has fewer repeats 5.3% to 8.9%, possibly because kelts 

must pass through PVC tubes on the sediment dam, which 

negatively impacts their survival. Rawding (2001b) applied 

the Kalama River winter run to the Coweeman and South 

Forth Toutle rivers populations. Rawding (2001b). 

Population East Fork Lewis River summer run 

Years of data, length of series 1996–2003, 8 years 

Abundance type, reference Snorkel survey. Rawding (2002). 

Hatchery, harvest, and age reference Rawding (2002) 

Upper Willamette River Steelhead ESU 

Population Calapooia River winter run 

Years of data, length of series 1980–2000, 21 years 

Abundance type, notes, reference Redd count. Data from StreamNet 

(http://www.streamnet.org). ODFW (1994), Hunt (1999). 

Harvest and hatchery reference Chilcote (2001) 

573
REFERENCES AND APPENDICES

Table B-4 continued. Steelhead time-series references. 

Data type Data source

Population South Santiam River winter run 

Years of data, length of series 1983–2000, 18 years 

Abundance type, notes, reference Redd count. Data from StreamNet 

(http://www.streamnet.org). StreamNet (1995, 1997). 

Harvest and hatchery reference Chilcote (2001) 

Population North Santiam River winter run 

Years of data, length of series 1983–2000, 18 years 

Abundance type, notes, reference Redd count. Data from StreamNet (http://www. 

streamnet.org). StreamNet (1998), ODFW (1998b). 

Harvest and hatchery reference Chilcote (2001) 

Population Molalla River winter run 

Years of data, length of series 1980–2000, 21 years 

Abundance type, reference Redd count. StreamNet (1997), Hunt (1999). 

Harvest and hatchery reference Chilcote (2001) 

Population South Santiam (Foster Dam) 

Years of data, length of series 1973–2000, 28 years 

Abundance type, reference Total live fish. ODFW (1990b), StreamNet (1997), Hunt 

(1999). 

Harvest reference Chilcote (2001) 

Population Willamette Falls Dam winter run 

Years of data, length of series 1971–2002, 32 years 

Abundance type, reference Dam/weir count. Serl and Merrill (2002) 

Northern California Steelhead ESU 

Population South Fork Eel River winter run above Benbow 

Years of data, length of series 1938–1975, 38 years 

Abundance type Dam count 

Abundance notes, reference CDFG (1994b) 

Population Mad River, winter run, above Sweasy 

Years of data, length of series 1938–1963, 26 years (some years no data) 

Abundance type Dam count 

Abundance notes, reference StreamNet (1964) 

Population Middle Fork Eel River, summer run 

Years of data, length of series 1966–2002, 37 years (some years no data) 

Abundance type Reach surveys, adult 

Abundance notes, reference Harris (2002c) 

Population Mad River, summer run 

Years of data, length of series 1994–2002, 9 years 

Abundance type Reach surveys, adult 

Sparkman (2002); CDFG (2002c), M. House.f Abundance notes, reference 

574
APPENDIX B 

Table B-4 continued. Steelhead time-series references. 

Data type Data source

Population Freshwater Creek, winter run 

Years of data, length of series 1994–2001, 8 years 

Abundance type Upstream trap 

Abundance notes, reference Humboldt Fish Action Council (2002) 

Population Redwood Creek, summer run 

Years of data, length of series 1981–2002, 22 years 

Abundance type Reach surveys, adult 

Abundance notes, reference Anderson (2000, 2002) 

Population Abalobadiah Creek, one reach 

Years of data, length of series 1993–2002, 10 years (one year no data) 

Abundance type Reach surveys, juveniles per sq. mi. 

Abundance notes, reference NMFS (2002g) 

Population Usal Creek, three reaches 

Years of data, length of series 1993–2002, 10 years (some years no data) 

Abundance type Reach surveys, juveniles per sq. mi. 

Abundance notes, reference NMFS (2002g) 

Population South Fork Tenmile Creek, nine reaches 

Years of data, length of series 1993–2002, 10 years (some years no data) 

Abundance type Reach surveys, juveniles per sq. mi. 

Abundance notes, reference NMFS (2002g) 

Population North Fork Tenmile Creek, eight reaches 

Years of data, length of series 1993–2002, 10 years (some years no data) 

Abundance type Reach surveys, juveniles per sq. mi. 

Abundance notes, reference NMFS (2002g) 

Population Middle Fork Tenmile Creek, seven reaches 

Years of data, length of series 1993–2002, 10 years (some years no data) 

Abundance type Reach surveys, juveniles per sq. mi. 

Abundance notes, reference NMFS (2002g) 

Population Pudding Creek, two reaches 

Years of data, length of series 1993–2002, 10 years (some years no data) 

Abundance type Reach surveys, juveniles per sq. mi. 

Abundance notes, reference NMFS (2002g) 

Population North Fork Noyo River, seven reaches 

Years of data, length of series 1993–2002, 10 years (some years no data) 

Abundance type Reach surveys, juveniles per sq. mi. 

Abundance notes, reference NMFS (2002g) 

Population Big River, two reaches 

Years of data, length of series 1993–2002, 10 years (some years no data) 

575
REFERENCES AND APPENDICES

Table B-4 continued. Steelhead time-series references. 

Data type Data source

Abundance type Reach surveys, juveniles per sq. mi. 

Abundance notes, reference NMFS (2002g) 

Population Big Salmon River, five reaches 

Years of data, length of series 1993–2002, 10 years (some years no data) 

Abundance type Reach surveys, juveniles per sq. mi. 

Abundance notes, reference NMFS (2002g) 

Population South Fork Eel Creek, five reaches 

Years of data, length of series 1994–2002, 9 years (some years no data) 

Abundance type Reach surveys, juveniles per sq. mi. 

Abundance notes, reference NMFS (2002g) 

Central California Coast Steelhead ESU 

Population San Lorenzo River, various reaches 

Years of data, length of series 1996–2001, 6 years 

Abundance type Reach surveys, juveniles per 30 m 

Abundance notes, reference Data from D. W. Alley & Associates, Brookdale, Calif.; see 

NMFS (2002g). 

Population Scott Creek, various reaches 

Years of data, length of series 1994–2001, 8 years (some years, some reaches no data) 

Abundance type Reach surveys, juveniles per 30 m 

Abundance notes, reference Data from J. Smith, San Jose State University, San Jose; see 

NMFS (2002g). 

Population Waddell Creek, various reaches 

Years of data, length of series 1992–2001, 10 years (some years, some reaches no data) 

Abundance type Reach surveys, juveniles per 30 m 

Abundance notes, reference Data from J. Smith, San Jose State University, San Jose; see 

NMFS (2002g). 

Population Gazos Creek, various reaches 

Years of data, length of series 1994–2001, 8 years (some years, some reaches no data) 

Abundance type Reach surveys, juveniles per 30 m 

Abundance notes, reference Data from J. Smith, San Jose State University, San Jose; see 

NMFS (2002g). 

Population Redwood Creek, various reaches 

Years of data, length of series 1992–2001, 10 years (some years, some reaches no data) 

Abundance type Reach surveys, juveniles per 30 m. 

Abundance notes, reference Data from J. Smith, San Jose State University, San Jose; see 

NMFS (2002g). 

South-Central California Coast Steelhead ESU 

Population Carmel River, winter run, above San Clemente Dam 

Years of data, length of series 1964–2002, 39 years (significant gaps in the time series) 

576
APPENDIX B 

Table B-4 continued. Steelhead time-series references. 

Data type Data source

Abundance type Dam count 

Abundance notes, reference Data from Monterey Peninsula Water Management District 

(2002)

a M. Schuck, WDFW. Pers. commun., 1 April 2003. b M. Chilcote, ODFW, Fish Division, Salem, OR. Pers. commun., December 2002. c R. Evenson, Confederated Tribes of the Yakama Nation, Fisheries Resource Management, Toppenish, WA. Pers. commun., 

November 2002. d D. Cramer, Portland General Electric, Portland, OR. Pers. commun., 6 November 2002. e M. Chilcote, ODFW, Fish Division, Salem, OR. Pers. commun., 27 November 2002. f M. House, Simpson Resource Company, Korbel, CA, and A. Bundschuh, Six Rivers National Forest, Eureka, CA. Pers. 

commun., October 2002. 

577
578
Appendix C: Coho Salmon 

Table C-1. Preliminary SSHAG (2003) categorizations of hatchery populations of the four coho salmon 

ESUs reviewed.*

Stock Run Basin 

SSHAG 

category*

North Fork Nehalem (#32) Nehalem 2c 

Fishhawk Lake (#99) Nehalem 2a or 3a 

Trask River (#34) Trask 2c or 3c 

Siletz (#33) Siletz 2a or 3a 

Umpqua (#55) Umpqua 2a 

Cow Creek (#18) Umpqua 2a 

Woahink Siltcoos 1a 

Coos (#37) Coos 2a 

Oregon Coast 

Coquille (#44) Coquille 2a 

Rogue River (#52) Rogue River 2a 

Iron Gate Klamath 2c 

Trinity River Trinity 2b 

Southern Oregon/Northern 

California Coast 

Mad River Mad River 4 

Noyo River Noyo River 2a 

Don Clausen Russian 1a 

Central California 

Monterey Bay Scott Creek 1a 

Lower Columbia River Big Creek Big Creek 2a 

Klaskanine Klaskanine 4 

Tanner Creek Lower gorge 2b 

Sandy River Late Sandy 2a 

Eagle Creek Clackamas 2c 

Little White Salmon Upper gorge 3c 

Toutle Type S Cowlitz 2a 

Type S complex Type S Various 2c or 3c 

Cowlitz Type N Cowlitz 2a 

Type N complex Type N Various 2b or 2c *

See subsection, Artificial Propagation, in Section 1, Introduction, for an explanation of the categories. 

579
REFERENCES AND APPENDICES

Table C-2. Coho salmon time-series data sources. 

Data type Data source 

Oregon Coast Coho Salmon ESU 

Population Oregon Coast 

Years of data, length of series 1970–2002, 33 years 

Abundance type, notes, reference Rivers: 1970–1989 index live spawner surveys expanded by 

stream miles; 1990–2002 stratified random sample (SRS) 

survey design. Pre-1990 calibrated to SRS estimates. 

Lakes: index surveys expanded by historical mark-recapture 

data. Jacobs et al. (2000, 2001, 2002), PFMC (2002a, 

2003b). 

Southern Oregon/Northern California Coast (SONCC) Coho Salmon ESU 

Population Rogue River 

Years of data, length of series 1980–2002 

Abundance type, notes, reference Adult fish. Abundance estimates based on expansion of 

beach seine abundance index based on hatchery fraction and 

returns of hatchery fish to Cole Rivers Hatchery; Jacobs 

et al. (2002) 

Population Hollow Tree Creek (Mendocino County) 

Years of data; length of series 1986–2002 (1983 included for one site; 1992 excluded from 

one site); 16–18 years 

Abundance type, notes, reference Juvenile density estimates (index reaches). Juvenile density 

estimates are derived based on multiple-pass depletion 

estimates at index reaches established by CDFG. Harris 

(2002a). 

Population South Fork Eel River basin (5 sites) (Mendocino County) 

Years of data; length of series 1994–2002 for one site, 1995–2002 for all others; 8–9 years 

Abundance type, notes, reference Juvenile density estimates (index reaches). Juvenile density 

estimates are derived based on multiple-pass depletion 

estimates (Wright and Levesque 2002) at index reaches 

established by Campbell Timberland Management, Fort 

Bragg, CA. Most index reaches range from approximately 

30 to 60 m in length. 

Population Numerous throughout SONCC ESU 

Years of data; length of series Variable, extending back to 1987 

Abundance type, notes, reference Presence-absence observations. Database contains 

information on coho salmon occurrence in streams 

throughout the SONCC ESU. Original sources include a 

variety of surveys, reports, and other documents produced 

by CDFG, NMFS, tribes, private landowners, academic 

institutions, and others doing research or monitoring of coho 

salmon or other salmonids in streams believed to have 

historically supported coho salmon. Original sources are 

documented in databases housed at SWFSC. Spence (2001). 

580
APPENDIX C 

Table C-2 continued. Coho salmon time-series data sources. 

Data type Data source 

Central California Coast Coho Salmon ESU 

Population Caspar Creek and Little River (Mendocino County) 

Years of data, length of series 1987–2002; 16 years 

Abundance type, notes, reference Smolt counts (partial). Smolt counts are partial counts made 

at downstream migrant traps and are not corrected for trap 

efficiency; numbers should be viewed as indices of 

abundance rather than population estimates. Harris (2002b). 

Population Noyo River Egg Collecting Station (Mendocino County) 

Years of data, length of series 1962–2001; 40 years 

Abundance type, notes, reference Adult counts (partial). Counts of adult coho salmon are 

partial counts made at the Noyo Egg Collecting Station on 

the South Fork Noyo River. In most years, the trap was not 

operated continuously during the spawning season. 

Furthermore, trapping usually ceased when egg take goals 

were met. Thus, counts should be viewed as indices of 

abundance rather than population estimates. Grass (2002). 

Population Pudding Creek, Caspar Creek, and Little River (Mendocino 

County) 

Years of data; length of series Pudding Creek, 1983–2002 (except 1990), 19 years. Caspar 

Creek (two sites), 1986–2002, 17 years. Little River (two 

sites), 1986–2002 (except 2000), 16 years. 

Abundance type, notes, reference Juvenile density estimates (index reaches). Juvenile density 

estimates are derived based on multiple-pass depletion 

estimates at index reaches established by CDFG. Pudding 

Creek site has been sampled in recent years by Campbell 

Timberland Management. Harris (2002a). 

Population Noyo River, Big River, and Big Salmon Creek (Mendocino 

County) 

Years of data; length of series Noyo River (eight sites), generally 1993–2002 (variable 

among sites), 6–10 years. Big River (two sites), 1993–2002, 

10 years. Big Salmon Creek (5 sites), generally 1993–2002 

(variable among sites), 7–10 years. 

Abundance type, notes, reference Juvenile density estimates (index reaches). Juvenile density 

estimates are derived based on multiple-pass depletion 

estimates at index reaches established by Campbell 

Timberland Management. Most index reaches range from 

approximately 30 to 60 m in length Wright and Levesque 

(2002). 

Population Lagunitas Creek (Marin County) 

Years of data; length of series 1995–2001; 7 years 

581
REFERENCES AND APPENDICES

Table C-2 continued. Coho salmon time-series data sources. 

Data type Data source

Abundance type, notes, reference Juvenile population estimates (expanded from index 

reaches). Juvenile density estimates for different habitat unit 

types are derived based on multiple-pass depletion estimates 

at index reaches. Unit-specific density estimates are then 

used in conjunction with habitat typing for the entire stream 

reach to obtain an overall population estimate for juveniles 

within the stream. Ettlinger (2002). 

Population Redwood Creek (Marin County) 

Years of data; length of series 1994–2001 (excluding 1999); 7 years 

Abundance type, notes, reference Juvenile population index. Juvenile counts are made 

annually at multiple index sites in Redwood Creek using 

single-pass electro-fishing. Mean numbers of fish per linear 

distance of stream were calculated based only on sites that 

were sampled each year during the period of record (i.e., 

sites sampled sporadically were not included in the overall 

estimate). Smith (1994a, 1996a, 1997, 1998a, 2000b, 

2001b). 

Population Waddell and Scott Creeks (Santa Cruz County), and Gazos 

Creek (San Mateo County) 

Years of data; length of series Waddell Creek and Scott Creek, 1992–2001; 10 years Gazos 

Creek, 1993-2001 (excluding 1994); 8 years 

Abundance type, notes, reference Juvenile population index. Juvenile counts are made 

annually at multiple index sites in each creek using singlepass electro-fishing. Mean numbers of fish per linear 

distance of stream were calculated based only on sites that 

were sampled each year during the period of record (i.e., 

sites sampled sporadically were not included in the overall 

estimate). Smith (1992, 1994b, 1994c, 1996b, 1996c, 1997, 

1998b, 1998c, 1999, 2000a, 2001a) 

Population Numerous throughout Central California Coast ESU 

Years of data; length of series Variable, extending back to 1987 

Abundance type, notes, reference Presence-absence observations. Database contains 

information on coho salmon occurrence in streams 

throughout the Central California Coast ESU. Original 

sources include a variety of surveys, reports, and other 

documents produced by CDFG, NMFS, private landowners, 

water districts, academic institutions, and others doing 

research or monitoring of coho salmon or other salmonids in 

streams believed to have historically supported coho salmon. 

Original sources are documented in databases housed at the 

NMFS SWFSC. Spence (2001). 

582
APPENDIX C 

Table C-2 continued. Coho salmon time-series data sources. 

Data type Data source 

Lower Columbia River Coho Salmon ESU 

Population Clatskanie River 

Years of data, length of series 1949–2001, 53 years 

Abundance type, notes, reference Fish per mile. Data from StreamNet (available online at 

http://www.streamet.org). Fulop et al. (1998a, 1998b), 

White et al. (1999), Ollerenshaw (2002). 

Population Scappoose Creek 

Years of data, length of series 1949–2001, 53 years 

Abundance type, notes, reference Fish per mile. Data from StreamNet (available online at 

http://www.streamet.org). Fulop et al. (1998a, 1998b), 

White et al. (1999), Ollerenshaw (2002). 

Population Big Creek 

Years of data, length of series 1950–2001, 52 years 

Abundance type, notes, reference Fish per mile. Data from StreamNet (available online at 

http://www.streamet.org). Fulop et al. (1998a, 1998b), 

White et al. (1999), Ollerenshaw (2002) 

Population Clackamas River 

Years of data, length of series 1950–2001, 52 years 

Abundance type, notes, reference Fish per mile. Data from StreamNet (available online at 

http://www.streamet.org). Fulop et al. (1998a, 1998b), 

White et al. (1999), Ollerenshaw (2002). 

Population Youngs Bay 

Years of data, length of series 1949–2001, 53 years 

Abundance type, notes, reference Fish per mile. Data from StreamNet (available online at 

http://www.streamet.org). Fulop et al. (1998a); Fulop et al. 

(1998b); White et al. (1999), Ollerenshaw (2002). 

Population Sandy River (Marmot Dam) 

Years of data, length of series 1977–2001, 25 years 

Abundance type, reference Dam count. Cramer (2002b). 

Population Clackamas River (North Fork Dam) 

Years of data, length of series 1957–2001, 45 years 

Abundance type, reference Dam count. Cramer (2002a). 

583
584
Appendix D: Sockeye Salmon 

Table D-1. Preliminary SSHAG (2003) categorizations of hatchery populations of the Ozette Lake 

sockeye ESU. 

ESU Stock Run Basin SSHAG category*

Ozette Lake Umbrella Creek Ozette 1a or 2a, or 1b or 2b 

*

See subsection, Artificial Propagation, in Section 1, Introduction, for an 

explanation of the categories. 

585
586
Appendix E: Chum Salmon 

Table E-1. Preliminary SSHAG (2003) categorizations of hatchery populations of chum salmon of the 

Hood Canal summer-run and Columbia River chum salmon ESUs. 

ESU Stock Run Basin 

SSHAG 

category*

Big Quilcene Summer Quilcene River 1a 

Lilliwaup Creek Summer South Hood Canal 1a 

Hamma Hamma River Summer South Hood Canal 1a 

Big Beef Creek Summer North Hood Canal 1b 

Salmon Creek Summer Dungeness River 1a 

Chimacum Creek Summer Dungeness River 1b 

Union River Summer Union River 1a 

Hood Canal summer run 

Jimmycomelately Creek Summer Dungeness River 1a 

Columbia River Sea Resources Fall Chinook River 1a 

Gorley Creek Fall Grays River 1a 

Hamilton Creek Fall Columbia Gorge 1a 

Washougal/Duncan Creek Fall Washougal River 1a 

*

See subsection, Artificial Propagation, in Section 1, Introduction, for an explanation of the categories. 

587
REFERENCES AND APPENDICES

Table E-2. Chum salmon time-series data sources. 

Data type Data source 

Hood Canal Summer-Run Chum Salmon ESU 

Population Anderson Creek 

Years of data, length of series 1970–2002 

Abundance type Trap counts (excluding broodstock take adjustment) plus redd 

counts downstream of trap. 

Abundance notes, reference Redd count expanded by 2 (assumes 1:1 male to female ratio). 

Counts include all ages. WDFW and Point No Point Treaty 

Tribes (2000, 2001), Lampsakis (2003). 

Hatchery notes, reference No supplemental hatchery program. 

Harvest notes, reference The offshore catch includes marine catch from Seattle Area 10, 

Admiralty Area 9, U.S. Convention Areas, and Canadian Area 

20. For summer-run chum these are assumed to be mature fish 

returning to spawning grounds. Catches by population/stock are 

determined from the run reconstruction tables given in WDFW 

and Point No Point Treaty Tribes (2001). The terminal catch for 

Anderson is that from the areas 12B, 12, and 9A. WDFW and 

Point No Point Treaty Tribes (2000, 2001); Lampsakis (2003). 

Age notes, reference Spawner survey; n = 10 fish sampled from 2001 to 2002. Age 

distribution reconstructed for other years using average cohort 

distribution weighted by annual abundance of contributing years 

(Sands 2002, in prep.). Johnson (2003a, 2003b). 

Population Big Beef Creek 

Years of data, length of series 1968–2002 

Abundance type Trap counts (excluding broodstock take adjustment) plus redd 

counts downstream of trap. Includes all ages. 

Abundance notes, reference Redd count expanded by 2 (assumes 1:1 male female ratio). 

Counts include all ages. WDFW and Point No Point Treaty 

Tribes (2000, 2001); Johnson (2003b). 

Hatchery notes, reference Supplementation program was started with releases in basin in 

1996. No sampling for hatchery marks on escapement grounds, 

but assume that all returns after 1996 are from hatchery plants 

since there had been no returns for several years prior. WDFW 

and Point No Point Treaty Tribes (2001). 

Harvest notes, reference The offshore catch includes marine catch from Seattle Area 10, 

Admiralty Area 9, U.S. Convention Areas, and Canadian Area 

20. For summer-run chum these are assumed to be mature fish 

returning to spawning grounds. Catches by population/stock are 

determined from the run reconstruction tables given in WDFW 

and Point No Point Treaty Tribes (2001). The terminal catch for 

Big Beef is from areas 12B, 12, and 9A. WDFW and Point No 

Point Treaty Tribes (2000, 2001); Lampsakis (2003). 

588
APPENDIX E 

Table E-2 continued. Chum salmon time-series data sources. 

Data type Data source

Age notes, reference Trap, spawner survey; n = 396 fish sampled from 2000 to 2002. 

Age distribution reconstructed for other years using average 

cohort distribution weighted by annual abundance of 

contributing years (Sands 2002, in prep.). WDFW and Point No 

Point Treaty Tribes (2001), Johnson (2003a, 2003b). 

Population Big Quilcene River 

Years of data, length of series 1968–2002 

Abundance type Trap counts (excluding broodstock take adjustment) plus redd 

counts downstream of trap. 

Abundance notes, reference Redd count expanded by 2 (assumes 1:1 male female ratio) 

Method—area under the curve, 10-day stream life. Escapement 

counts include all ages. WDFW and Point No Point Treaty 

Tribes (2000, 2001), Lampsakis (2003). 

Hatchery notes, reference Supplementation program started in 1992 in the Big Quilcene 

River. Broodstock is taken from returning fish; eggs are 

incubated, and fry released into the Big Quilcene. WDFW and 

Point No Point Treaty Tribes (2001). 

Harvest notes, reference The offshore catch includes marine catch from Seattle Area 10, 

Admiralty Area 9, U.S. Convention Areas, and Canadian Area 

20. For summer-run chum these are assumed to be mature fish 

returning to spawning grounds. Catches by population/stock are 

determined from the run reconstruction tables given in WDFW 

and Point No Point Treaty Tribes (2001). The terminal catch for 

Big Quilcene is from areas 82F, 12A, 12B, 12, and 9A. WDFW 

and Point No Point Treaty Tribes (2000, 2001), Lampsakis 

(2003). 

Age notes, reference From bay fisheries, spawner surveys; n = 3,770 fish sampled 

from 1992 to 2002. Age distribution reconstructed for other 

years using average cohort distribution weighted by annual 

abundance of contributing years (Sands 2002, in prep.). WDFW 

and Point No Point Treaty Tribes (2000, 2001), Johnson (2003a, 

2003b). 

Population Chimacum River 

Years of data, length of series 1999–2002 

Abundance notes, reference Returns come from recent hatchery plants to system. 

Escapement counts include all ages. WDFW and Point No 

Point Treaty Tribes (2000, 2001), Johnson (2003b). 

Hatchery notes, reference Reintroduction program started in 1996 when eyed eggs were 

transferred in from Salmon Creek. WDFW and Point No Point 

Treaty Tribes (2001). 

589
REFERENCES AND APPENDICES

Table E-2 continued. Chum salmon time-series data sources. 

Data type Data source

Harvest notes, reference The offshore catch includes marine catch from Seattle Area 10, 

Admiralty Area 9, U.S. Convention Areas, and Canadian Area 

20. For summer-run chum these are assumed to be mature fish 

returning to spawning grounds. Catches by population/stock are 

determined from the run reconstruction tables given in WDFW 

and Point No Point Treaty Tribes (2001). There is no terminal 

catch area for Chimacum. WDFW and Point No Point Treaty 

Tribes (2000, 2001), Lampsakis (2003). 

Age notes, reference Trap, spawner survey; n = 537 fish sampled from 1999 to 2002. 

Age distribution reconstructed for other years using average 

cohort distribution weighted by annual abundance of 

contributing years (Sands 2002, in prep.). WDFW and Point No 

Point Treaty Tribes (2000, 2001), Johnson (2003a, 2003b). 

Population Combined Quilcene River 

Years of data, length of series 1974–2002 

Abundance type Trap counts (excluding broodstock take adjustment) plus redd 

counts downstream of trap. 

Abundance notes, reference Redd count expanded by 2 (assumes 1:1 male female ratio). 

Escapement counts include all ages. WDFW and Point No 

Point Treaty Tribes (2000, 2001), Lampsakis (2003). 

Hatchery notes, reference Coded-wire-tag otolith sampling for hatchery marks. WDFW 

and Point No Point Treaty Tribes (2001). 

Harvest notes, reference The offshore catch includes marine catch from Seattle Area 10, 

Admiralty Area 9, U.S. Convention Areas, and Canadian Area 

20. For summer-run chum these are assumed to be mature fish 

returning to spawning grounds. Catches by population/stock are 

determined from the run reconstruction tables given in WDFW 

and Point No Point Treaty Tribes (2001). The terminal catch for 

Quilcene is from areas 82F, 12A, 12B, 12, and 9A. WDFW and 

Point No Point Treaty Tribes (2000, 2001), Lampsakis (2003). 

Age notes, reference From bay fisheries, trap, spawner surveys; n = 4,076 fish 

sampled from 1992 to 2002. Age distribution reconstructed for 

other years using average cohort distribution weighted by 

annual abundance of contributing years (Sands 2002, in prep.). 

WDFW and Point No Point Treaty Tribes (2000, 2001), Johnson 

(2003a, 2003b). 

Population Dewatto River 

Years of data, length of series 1968–2002 

Abundance type Trap counts (excluding broodstock take adjustment) plus redd 

counts downstream of trap. 

590
APPENDIX E 

Table E-2 continued. Chum salmon time-series data sources. 

Data type Data source

Abundance notes, reference Redd count expanded by 2 (assumes 1:1 male female ratio). 

Escapement counts include all ages. WDFW and Point No 

Point Treaty Tribes (2000, 2001), Lampsakis (2003). 

Hatchery notes, reference No broodstock take. WDFW and Point No Point Treaty Tribes 

(2001). 

Harvest notes, reference The offshore catch includes marine catch from Seattle Area 10, 

Admiralty Area 9, U.S. Convention Areas, and Canadian Area 

20. For summer-run chum these are assumed to be mature fish 

returning to spawning grounds. Catches by population/stock are 

determined from the run reconstruction tables given in WDFW 

and Point No Point Treaty Tribes (2001). The terminal catch for 

Dewatto is that from the areas 12C, 12B, 12, and 9A. WDFW 

and Point No Point Treaty Tribes (2000, 2001), Lampsakis 

(2003). 

Age notes, reference Spawner survey; n = 5 fish sampled from 2000 to 2001. Age 

distribution reconstructed for other years using average cohort 

distribution weighted by annual abundance of contributing years 

(Sands 2002, in prep.). Johnson (2003a, 2003b). 

Population Dosewallips River 

Years of data, length of series 1972–2002 

Abundance type Trap counts (excluding broodstock take adjustment) plus redd 

counts downstream of trap. 

Abundance notes, reference Redd count expanded by 2 (assumes 1:1 male female ratio). 

Escapement counts include all ages. WDFW and Point No 

Point Treaty Tribes (2000, 2001), Lampsakis (2003). 

Hatchery notes, reference There are no hatchery releases in basin. There may be some 

from nearby hatchery summer-run chum releases, but the basin 

is not sampled. Hatchery impact on natural spawners is 

assumed to be zero. WDFW and Point No Point Treaty Tribes 

(2001). 

Harvest notes, reference The offshore catch includes marine catch from Seattle Area 10, 

Admiralty Area 9, U.S. Convention Areas, and Canadian Area 

20. For summer-run chum these are assumed to be mature fish 

returning to spawning grounds. Catches by population/stock are 

determined from the run reconstruction tables given in WDFW 

and Point No Point Treaty Tribes (2001). The terminal catch for 

Dosewallips is from the areas 12B, 12, and 9A. WDFW and 

Point No Point Treaty Tribes (2000, 2001), Lampsakis (2003). 

Age notes, reference Trap, spawner survey; n = 500 fish sampled from 1999 to 2002. 

Age distribution reconstructed for other years using average 

cohort distribution weighted by annual abundance of 

contributing years (Sands 2002, in prep.). WDFW and Point No 

Point Treaty Tribes (2001), Johnson (2003a, 2003b). 

591
REFERENCES AND APPENDICES

Table E-2 continued. Chum salmon time-series data sources. 

Data type Data source

Population Duckabush River 

Years of data, length of series 1968–2002 

Abundance type Trap counts (excluding broodstock take adjustment) plus redd 

counts downstream of trap. 

Abundance notes, reference Redd count expanded by 2 (assumes 1:1 male female ratio). 

Escapement counts include all ages. WDFW and Point No 

Point Treaty Tribes (2000, 2001), Lampsakis (2003). 

Hatchery notes, reference No hatchery releases or broodstock take in the Duckabush. 

WDFW and Point No Point Treaty Tribes (2001). 

Harvest notes, reference The offshore catch includes marine catch from Seattle Area 10, 

Admiralty Area 9, U.S. Convention Areas, and Canadian Area 

20. For summer-run chum these are assumed to be mature fish 

returning to spawning grounds. Catches by population/stock are 

determined from the run reconstruction tables given in WDFW 

and Point No Point Treaty Tribes (2001). The terminal catch for 

Duckabush is that from fishing areas 12B, 12, 9A. WDFW and 

Point No Point Treaty Tribes (2000, 2001); Lampsakis (2003). 

Age notes, reference Trap, spawner survey; n = 326 fish sampled from 1999 to 2002. 

Age distribution reconstructed for other years using average 

cohort distribution weighted by annual abundance of 

contributing years (Sands 2002, in prep.). WDFW and Point No 

Point Treaty Tribes (2001), Johnson (2003a, 2003b). 

Population Hamma Hamma River 

Years of data, length of series 1968–2002 

Abundance type Trap counts (excluding broodstock take adjustment) plus redd 

counts downstream of trap. 

Abundance notes, reference Redd count expanded by 2 (assumes 1:1 male female ratio). 

Escapement counts include all ages. WDFW and Point No 

Point Treaty Tribes (2000, 2001), Lampsakis (2003). 

Hatchery notes, reference Supplementation program was started with broodstock takes in 

1998; assumed that there was no hatchery straying into basin 

prior to hatchery releases in basin. WDFW and Point No Point 

Treaty Tribes (2001). 

Harvest notes, reference The offshore catch includes marine catch from Seattle Area 10, 

Admiralty Area 9, U.S. Convention Areas, and Canadian Area 

20. For summer-run chum these are assumed to be mature fish 

returning to spawning grounds. Catches by population/stock are 

determined from the run reconstruction tables given in WDFW 

and Point No Point Treaty Tribes (2001). The terminal catch for 

Hamma Hamma is from the areas 12B, 12, 9A. WDFW and 

Point No Point Treaty Tribes (2000, 2001); Lampsakis (2003). 

592
APPENDIX E 

Table E-2 continued. Chum salmon time-series data sources. 

Data type Data source

Age notes, reference Trap, seine, spawner survey; n = 386 fish sampled from 1999 to 

2002. Age distribution reconstructed for other years using 

average cohort distribution weighted by annual abundance of 

contributing years (Sands 2002, in prep.). WDFW and Point No 

Point Treaty Tribes (2001), Johnson (2003a, 2003b). 

Population Jimmycomelately Creek 

Years of data, length of series 1974–2002 

Abundance type Trap counts (excluding broodstock take adjustment) plus redd 

counts downstream of trap. 

Abundance notes, reference Escapement counts include all ages. WDFW and Point No 

Point Treaty Tribes (2000, 2001), Johnson (2003b). 

Hatchery notes, reference Supplementation program started with 1999 broodyear. WDFW 

and Point No Point Treaty Tribes (2001). 

Harvest notes, reference The offshore catch includes marine catch from Seattle Area 10, 

Admiralty Area 9, U.S. Convention Areas, and Canadian Area 

20. For summer-run chum these are assumed to be mature fish 

returning to spawning grounds. Catches by population/stock are 

determined from the run reconstruction tables given in WDFW 

and Point No Point Treaty Tribes (2001). The terminal catch for 

Jimmycomelately is from the Sequim area. WDFW and Point 

No Point Treaty Tribes (2000, 2001), Lampsakis (2003). 

Age notes, reference Trap, spawner survey; n = 233 fish sampled from 1999 to 2002. 

Age distribution reconstructed for other years using average 

cohort distribution weighted by annual abundance of 

contributing years (Sands 2002, in prep.). WDFW and Point No 

Point Treaty Tribes (2001), Johnson (2003a, 2003b). 

Population Lilliwaup River 

Years of data, length of series 1971–2002 

Abundance type Trap counts (excluding broodstock take adjustment) plus redd 

counts downstream of trap. 

Abundance notes, reference Redd count expanded by 2 (assumes 1:1 male to female ratio). 

Escapement counts include all ages. WDFW and Point No 

Point Treaty Tribes (2000, 2001), Lampsakis (2003). 

Hatchery notes, reference Supplementation program was started with broodstock take in 

1992. WDFW and Point No Point Treaty Tribes (2001). 

593
REFERENCES AND APPENDICES

Table E-2 continued. Chum salmon time-series data sources. 

Data type Data source

Harvest notes, reference The offshore catch includes marine catch from Seattle Area 10, 

Admiralty Area 9, U.S. Convention Areas, and Canadian Area 

20. For summer-run chum these are assumed to be mature fish 

returning to spawning grounds. Catches by population/stock are 

determined from the run reconstruction tables given in WDFW 

and Point No Point Treaty Tribes (2001). The terminal catch for 

Lilliwaup is from the areas 12C, 12B, 12, and 9A. WDFW and 

Point No Point Treaty Tribes (2000, 2001), Lampsakis (2003). 

Age notes, reference Trap, spawner survey; n = 233 fish sampled from 1999 to 2002. 

Age distribution reconstructed for other years using average 

cohort distribution weighted by annual abundance of 

contributing years (Sands 2002, in prep.). WDFW and Point No 

Point Treaty Tribes (2001) Johnson (2003a, 2003b). 

Population Little Quilcene River 

Years of data, length of series 1968–2002 

Abundance type Method—area under the curve, 10-day stream life. 

Abundance notes, reference Redd counts expanded by 2 (assumes 1:1 male to female ratio). 

Escapement counts include all ages. WDFW and Point No 

Point Treaty Tribes (2000, 2001), Lampsakis (2003). 

Hatchery notes, reference Supplementation program started in 1992 in the Big Quilcene 

River. Broodstock is taken from Big Quilcene and fry released 

into the Big Quilcene. Some return to Little Quilcene. WDFW 

and Point No Point Treaty Tribes (2001). 

Harvest notes, reference The offshore catch includes marine catch from Seattle Area 10, 

Admiralty Area 9, U.S. Convention Areas, and Canadian Area 

20. For summer-run chum these are assumed to be mature fish 

returning to spawning grounds. Catches by population/stock are 

determined from the run reconstruction tables given in WDFW 

and Point No Point Treaty Tribes (2001). The terminal catch for 

Little Quilcene is that from the areas 12A, 12B, 12, and 9A. 

WDFW and Point No Point Treaty Tribes (2000, 2001); 

Lampsakis (2003). 

Age notes, reference From bay fisheries, spawner survey, seine in bay, rack; n = 

2,599 fish sampled from 1992 to 2002. Age distribution 

reconstructed for other years using average cohort distribution 

weighted by annual abundance of contributing years (Sands 

2002, in prep.). WDFW and Point No Point Treaty Tribes 

(2001), Johnson (2003a, 2003b). 

Population Salmon River 

Years of data, length of series 1971–2002 

Abundance type Trap counts (excluding broodstock take adjustment) plus redd 

counts downstream of trap. 

594
APPENDIX E 

Table E-2 continued. Chum salmon time-series data sources. 

Data type Data source

Abundance notes, reference Redd count expanded by 2 (assumes 1:1 male to female ratio). 

Escapement counts include all ages. WDFW and Point No 

Point Treaty Tribes (2000, 2001), Johnson (2003b). 

Hatchery notes, reference Supplementation program was started in 1992. WDFW and 

Point No Point Treaty Tribes (2001). 

Harvest notes, reference The offshore catch includes marine catch from Seattle Area 10, 

Admiralty Area 9, U.S. Convention Areas, and Canadian Area 

20. For summer-run chum these are assumed to be mature fish 

returning to spawning grounds. Catches by population/stock are 

determined from the run reconstruction tables given in WDFW 

and Point No Point Treaty Tribes (2001). The terminal catch for 

Salmon is that from the Discovery Bay. WDFW and Point No 

Point Treaty Tribes (2000, 2001), Lampsakis (2003). 

Age notes, reference Trap, spawner survey; n = 1,087 fish sampled from 1999 to 

2002. Age distribution reconstructed for other years using 

average cohort distribution weighted by annual abundance of 

contributing years (Sands 2002, in prep.). WDFW and Point No 

Point Treaty Tribes (2001), Johnson (2003a, 2003b). 

Population Salmon/Snow 

Years of data, length of series 1974–2002 

Abundance type Trap counts (excluding broodstock take adjustment) plus redd 

counts downstream of trap. 

Abundance notes, reference Redd count expanded by 2 (assumes 1:1 male to female ratio). 

Escapement counts include all ages. WDFW and Point No 

Point Treaty Tribes (2000, 2001), Lampsakis (2003). 

Hatchery reference WDFW and Point No Point Treaty Tribes (2001) 

Harvest notes, reference The offshore catch includes marine catch from Seattle Area 10, 

Admiralty Area 9, U.S. Convention Areas, and Canadian Area 

20. For summer-run chum these are assumed to be mature fish 

returning to spawning grounds. Catches by population/stock are 

determined from the run reconstruction tables given in WDFW 

and Point No Point Treaty Tribes (2001). The terminal catch for 

Salmon and Snow is that from Discovery Bay. WDFW and 

Point No Point Treaty Tribes (2000, 2001), Lampsakis (2003). 

Age notes, reference Trap, spawner survey; n = 1,227 fish sampled from 1999 to 

2002. Age distribution reconstructed for other years using 

average cohort distribution weighted by annual abundance of 

contributing years (Sands 2002, in prep.). WDFW and Point No 

Point Treaty Tribes (2001), Johnson (2003a, 2003b). 

Population Snow River 

Years of data, length of series 1972–2002 

595
REFERENCES AND APPENDICES

Table E-2 continued. Chum salmon time-series data sources. 

Data type Data source

Abundance type Trap counts (excluding broodstock take adjustment) plus redd 

counts downstream of trap. 

Abundance notes, reference Redd count expanded by 2 (assumes 1:1 male to female ratio). 

Escapement counts include all ages. WDFW and Point No 

Point Treaty Tribes (2000, 2001), Johnson (2003). 

Hatchery notes, reference No estimate of hatchery fish contribution to spawners. WDFW 

and Point No Point Treaty Tribes (2001). 

Harvest notes, reference The offshore catch includes marine catch from Seattle Area 10, 

Admiralty Area 9, U.S. Convention Areas, and Canadian Area 

20. For summer-run chum these are assumed to be mature fish 

returning to spawning grounds. Catches by population/stock are 

determined from the run reconstruction tables given in WDFW 

and Point No Point Treaty Tribes (2001). The terminal catch for 

Salmon and Snow is that from Discovery Bay. WDFW and 

Point No Point Treaty Tribes (2000, 2001), Lampsakis (2003). 

Age notes, reference Trap, spawner survey; n = 140 fish sampled from 1999 to 2002. 

Age distribution reconstructed for other years using average 

cohort distribution weighted by annual abundance of 

contributing years (Sands 2002, in prep.). WDFW and Point No 

Point Treaty Tribes (2001), Johnson (2003a, 2003b). 

Population Tahuya River 

Years of data, length of series 1972–2002 

Abundance type Trap counts (excluding broodstock take adjustment) plus redd 

counts downstream of trap. 

Abundance notes, reference Redd count expanded by 2 (assumes 1:1 male to female ratio). 

Escapement counts include all ages. WDFW and Point No 

Point Treaty Tribes (2000, 2001); T. Johnson (WDFW, pers. 

commun., 28 March 2003); Johnson (2003b). 

Hatchery notes, reference No estimate of hatchery contribution to spawners. WDFW and 

Point No Point Treaty Tribes (2001). 

Harvest notes, reference The offshore catch includes marine catch from Seattle Area 10, 

Admiralty Area 9, U.S. Convention Areas, and Canadian Area 

20. For summer-run chum these are assumed to be mature fish 

returning to spawning grounds. Catches by population/stock are 

determined from the run reconstruction tables given in WDFW 

and Point No Point Treaty Tribes (2001). The terminal catch for 

Tahuya is from areas 12D, 12C, 12B, 12, and 9A. WDFW and 

Point No Point Treaty Tribes (2000, 2001), Lampsakis (2003). 

Age notes No surveys 

Population Union River 

Years of data, length of series 1974–2002 

596
APPENDIX E 

Table E-2 continued. Chum salmon time-series data sources. 

Data type Data source

Abundance type Trap counts (excluding broodstock take adjustment) plus redd 

counts downstream of trap. 

Abundance notes, reference Redd count expanded by 2 (assumes 1:1 male to female ratio). 

Escapement counts include all ages. WDFW and Point No 

Point Treaty Tribes (2000, 2001), Lampsakis (2003). 

Hatchery notes, reference Supplementation program was started with broodstock take in 

2000. WDFW and Point No Point Treaty Tribes (2001). 

Harvest notes, reference The offshore catch includes marine catch from Seattle Area 10, 

Admiralty Area 9, U.S. Convention Areas, and Canadian Area 

20. For summer-run chum these are assumed to be mature fish 

returning to spawning grounds. Catches by population/stock are 

determined from the run reconstruction tables given in WDFW 

and Point No Point Treaty Tribes (2001). The terminal catch for 

Union is that from the Sequim area. WDFW and Point No Point 

Treaty Tribes (2000, 2001). 

Age notes, reference Trap, spawner survey; n = 317 fish sampled from 1999 to 2002. 

Age distribution reconstructed for other years using average 

cohort distribution weighted by annual abundance of 

contributing years (Sands 2002, in prep.). WDFW and Point No 

Point Treaty Tribes (2001), Johnson (2003a, 2003b). 

Columbia River Chum Salmon ESU 

Population Grays River 

Years of data, length of series 1951–2000, 50 years 

Abundance type Live/dead index 

Abundance notes, reference 1999 and 2000 data from Keller (2001) and Keller and Bruce 

(2001). Hymer (2000). 

Hatchery notes, reference There has been no significant contribution of hatchery fish to 

the Grays River chum salmon population. Rawding (2001c). 

Harvest notes, reference There has been no significant directed harvest on Columbia 

chum salmon for the duration of the time series. Indirect 

harvest is believed to be negligible. Rawding (2001c). 

Age reference Salo (1991) 

Age notes, reference McClure et al. (2003) 

Population Grays River 

Years of data, length of series 1967–1998, 32 years 

Abundance type, reference Live/dead index. Rawding (2003). 

Hatchery notes, reference There has been no significant contribution of hatchery fish to 

the Grays River chum salmon population. Rawding (2001c). 

597
REFERENCES AND APPENDICES

Table E-2 continued. Chum salmon time-series data sources. 

Data type Data source

Harvest notes, reference There has been no significant directed harvest on Columbia 

chum salmon for the duration of the time series. Indirect 

harvest is believed to be negligible. Rawding (2001c). 

Age notes, reference McClure et al. (2003), Salo (1991). 

Population Lower gorge tributaries (Hamilton Creek, Hamilton Springs, 

and Hardy Creek) 

Years of data, length of series 1944–2000, 57 years 

Abundance type Live/dead index 

Abundance notes, reference Separate time series for each subpopulation were combined for 

analysis (Rawding 2001c, 2003). 

Hatchery notes, reference There has been no (or extremely little) hatchery impact on 

Hardy Creek chum salmon. Rawding (2001c). 

Harvest notes, reference There has been no significant directed harvest on Columbia 

chum salmon for the duration of the time series. Indirect 

harvest is believed to be negligible. Rawding (2001c). 

Age notes, reference McClure et al. (2003), Salo (1991). 

598
Most NOAA Technical Memorandums NMFS-NWFSC are available online at the

Northwest Fisheries Science Center web site (http://www.nwfsc.noaa.gov).

Recent NOAA Technical Memorandums NMFS

published by the

Northwest Fisheries Science Center

NOAA Tech. Memo.

NMFS-NWFSC65 Fleischer, G.W., K.D. Cooke, P.H. Ressler, R.E. Thomas, S.K. de Blois, L.C. Hufnagle, A.R. Kronlund,

J.A. Holmes, and C.D. Wilson. 2005. The 2003 integrated acoustic and trawl survey of Pacific hake,

Merluccius productus, in U.S. and Canadian waters off the Pacific coast. U.S. Dept. Commer., NOAA

Tech. Memo. NMFS-NWFSC-65, 45 p. NTIS number pending.

64 Ferguson, J.W., G.M. Matthews, R.L. McComas, R.F. Absolon, D.A. Brege, M.H. Gessel, and L.G.

Gilbreath. 2005. Passage of adult and juvenile salmonids through federal Columbia River power system

dams. U.S. Dept. Commer., NOAA Tech. Memo. NMFS-NWFSC-64, 160 p. NTIS PB2005-104828.

63 Williams, J.G., S.G. Smith, R.W. Zabel, W.D. Muir, M.D. Scheuerell, B.P. Sandford, D.M. Marsh,

R.A. McNatt, and S. Achord. 2005. Effects of the federal Columbia River power system on salmonid

populations. U.S. Dept. Commer., NOAA Tech. Memo. NMFS-NWFSC-63, 150 p. NTIS PB2005-107352.

62 Krahn, M.M., M.J. Ford, W.F. Perrin, P.R. Wade, R.P. Angliss, M.B. Hanson, B.L. Taylor,

G.M. Ylitalo, M.E. Dahlheim, J.E. Stein, and R.S. Waples. 2004. 2004 Status review of Southern

Resident killer whales (Orcinus orca) under the Endangered Species Act. U.S. Dept. Commer., NOAA

Tech. Memo. NMFS-NWFSC-62, 73 p. NTIS PB2005-106089.

61 Berejikian, B.A., and M.J. Ford. 2004. Review of relative fitness of hatchery and natural salmon. U.S.

Dept. Commer., NOAA Tech. Memo. NMFS-NWFSC-61, 28 p. NTIS PB2005-106090.

60 Ford, M.J., T.A. Lundrigan, and P.C. Moran. 2004. Population genetics of Entiat River spring Chinook

salmon. U.S. Dept. Commer., NOAA Tech. Memo. NMFS-NWFSC-60, 45 p. NTIS PB2004-107039.

59 Sloan, C.A., D.W. Brown, R.W. Pearce, R.H. Boyer, J.L. Bolton, D.G. Burrows, D.P. Herman, and

M.M. Krahn. 2004. Extraction, cleanup, and gas chromatography/mass spectrometry analysis of

sediments and tissues for organic contaminants. U.S. Dept. Commer., NOAA Tech. Memo. NMFSNWFSC-59, 47 p. NTIS PB2004-105739.

58 Beechie, T.J., E.A. Steel, P. Roni, and E. Quimby (editors). 2003. Ecosystem recovery planning for

listed salmon: an integrated assessment approach for salmon habitat. U.S. Dept. Commer., NOAA Tech.

Memo. NMFS-NWFSC-58, 183 p. NTIS PB2004-105734.

57 Rogers, J.B. 2003. Species allocation of Sebastes and Sebastolobus sp. caught by foreign

countries from 1965 through 1976 off Washington, Oregon, and California, USA. U.S. Dept. Commer.,

NOAA Tech. Memo. NMFS-NWFSC-57, 117 p. NTIS PB2004-105737.

56 MacCall, A.D., and T.C. Wainwright (editors). 2003. Assessing extinction risk for West Coast salmon.

U.S. Dept. Commer., NOAA Tech. Memo. NMFS-NWFSC-56, 198 p. NTIS PB2003-104642.