NOAA Technical Memorandum NMFS-NWFSC-24

Status Review of Coho Salmon from Washington, Oregon, and California Laurie A. Weitkamp, Thomas C. Wainwright, Gregory J. Bryant*, George B. Milner, David J. Teel, Robert G. Kope, and Robin S. Waples National Marine Fisheries Service Northwest Fisheries Science Center Coastal Zone and Estuarine Studies Division 2725 Montlake Blvd. E. Seattle WA 98112-2097 and *National Marine Fisheries Service Southwest Region Protected Species Management Division 501 W. Ocean Blvd., Suite 4200, Long Beach, CA 90802-4213 September 1995 U.S. DEPARTMENT OF COMMERCE Ronald H. Brown, Secretary National Oceanic and Atmospheric Administration D. James Baker, Administrator National Marine Fisheries Service Rolland A. Schmitten, Assistant Administrator for Fisheries

Executive Summary

Acknowledgments

Introduction

Scope and Intent of the Present Document

Key Questions in ESA Evaluations

The Species Question

The Extinction Risk Question

Summary of Information Presented by the Petitioners

Distinct Population Segments

Population Abundance

Causes of Decline for Coho Salmon

Information Relating to the Species Question

Environmental Features

Physical Features of the Freshwater Environment

Vegetation

Upwelling

Zoogeography

Other Ecological Factors

Coho Salmon Life History

Age

Fecundity

Smolt Size and Outmigration Timing

Adult Run Timing

Spawner Size

Ocean Migration

Disease

Clackamas River Late-Run Coho Salmon

Genetics

Previous Genetic Studies

New Data

Discussion and Conclusions on ESU Determinations

Reproductive Isolation

Ecological/Genetic Diversity

Conclusions

Additional comments

Artificial Propagation

Patterns of Artificial Propagation and Stock Transfers

Run Timing

Juvenile Outplants

Assessment of Extinction Risk

Background

Absolute Numbers

Historical Abundance and Carrying Capacity

Trends in Abundance

Factors Causing Variability

Threats to Genetic Integrity

Recent Events

Other Risk Factors

Approach

Quantitative Methods

Data Types

Computed Statistics

Analyses of Extinction Risk by ESU

1) Central California Coast

2) Southern Oregon/Northern California Coasts

3) Oregon Coast

4) Lower Columbia River/Southwest Washington Coast

5) Olympic Peninsula

6) Puget Sound/Strait of Georgia

Conclusions

1) Central California Coast

2) Southern Oregon/Northern California Coasts

3) Oregon Coast

4) Lower Columbia River/Southwest Washington Coast

5) Olympic Peninsula

6) Puget Sound/Strait of Georgia

Citations

Appendix A: Glossary

Appendix B - Environmental Information

Appendix B-1: Gauging Stations

Appendix B-2: Sampling Stations

Appendix C - Life History Trait Information

Appendix C-1: Smolt Outmigration Timing

Appendix C-2: Coho Salmon Smolt Sizes

Appendix C-3: River Entry Timing of Coho Salmon

Appendix C-4: Coho Salmon Spawn Timing

Appendix C-5: Coho Salmon Spawner Sizes

Appendix C-6: Marine Recoveries of Coded-wire Tags

Appendix D: Personal Communication and Unpublished Information

Citations and Questionnaire Responses

Appendix E - Records of Hatchery Outplants

Appendix E-1: Releases of fry and yearlings in selected Washington and Oregon river basins

Appendix E-2: Releases of adults in selected Oregon river basins

In October 1993, in response to three petitions seeking protection for coho salmon under the ESA, NMFS initiated a status review of coho salmon in Washington, Oregon, and California, and formed a Biological Review Team (BRT) to conduct the review. This report summarizes biological and environmental information gathered in that process.

The BRT examined genetic, life history, biogeographic, geologic, and environmental information to identify where ESU boundaries should be located. In particular, physical environment and ocean conditions/upwelling patterns, estuarine and freshwater fish distributions, and coho salmon river entry and spawn timing and marine coded-wire-tag recovery patterns were found to be the most informative for this process. Based on this examination, the BRT identified six coho salmon ESUs in Washington, Oregon, and California. The geographic boundaries of the six proposed ESUs are as follows:

1. Central California coast. The geographic boundaries of this ESU extend from Punta Gorda in northern California south to and including the San Lorenzo River in central California, and include tributaries to San Francisco Bay, excluding the Sacramento-San Joaquin River system.
   
2. Southern Oregon/northern California coasts. This ESU includes coho salmon from Cape Blanco in southern Oregon to Punta Gorda in northern California.
   
3. Oregon coast. This ESU covers coastal drainages along most of the Oregon coast from Cape Blanco to the mouth of the Columbia River.
   
4. Lower Columbia River/southwest Washington coast. Historically, this ESU probably included coho salmon from all tributaries of the Columbia River below the Klickitat River on the Washington side and below the Deschutes River on the Oregon side (including Willamette River as far upriver as the Willamette Falls), as well as coastal drainages in southwest Washington between the Columbia River and Point Grenville (between the Copalis and Quinault Rivers).
   
5. Olympic Peninsula. The geographic boundaries of this ESU are entirely within Washington, including coastal drainages from Point Grenville to and including Salt Creek (directly west of the Elwha River).
   
6. Puget Sound/Strait of Georgia. This ESU includes coho salmon from drainages of Puget Sound and Hood Canal, the eastern Olympic Peninsula (east of Salt Creek), and the Strait of Georgia from the eastern side of Vancouver Island and the British Columbia mainland (north to and including Campbell and Powell Rivers), excluding the upper Fraser River above Hope.

The ESA (section 3) defines the term 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. According to the ESA, the determination whether a species is threatened or endangered should be made on the basis of the best scientific information available regarding its current status, after taking into consideration conservation measures that are proposed or are in place. In this review, the BRT did not evaluate likely or possible effects of conservation measures and, therefore, did not make recommendations as to whether identified ESUs should be listed as threatened or endangered species; rather, the BRT drew scientific conclusions about the risk of extinction faced by identified ESUs under the assumption that present conditions will continue. The resulting conclusions for each ESU follow.

1. Central California coast. There was unanimous agreement among the BRT that natural populations of coho salmon in this ESU are presently in danger of extinction. The chief reasons for this assessment were extremely low current abundance, especially compared to historical abundance, widespread local extinctions, clear downward trends in abundance, extensive habitat degradation and associated decreased carrying capacity, and a long history of artificial propagation with the use of non-native stocks. In addition, recent droughts and current ocean conditions may have further reduced run sizes.

2. Southern Oregon/northern California coasts. There was unanimous agreement among the BRT that coho salmon in this ESU are not in danger of extinction but are likely to become endangered in the foreseeable future if present trends continue. Current run size, the severe decline from historical run size, the frequency of local extinctions, long-term trends that are clearly downward, degraded habitat and associated reduction in carrying capacity, and widespread hatchery production using exotic stocks are all factors that contributed to the assessment. Like the central California ESU, recent droughts and current ocean conditions may have further reduced run sizes.

3. Oregon coast. The BRT concluded that coho salmon in this ESU are not in danger of extinction but are likely to become endangered in the future if present trends continue. The BRT reached this conclusion based on low recent abundance estimates that are 5-10% of historical abundance estimates, clearly downward long-term trends, recent spawner-to-spawner ratios that are below replacement, extensive habitat degradation, and widespread hatchery production of coho salmon. Drought and current ocean conditions may have also reduced run sizes.

4. Lower Columbia River/southwest Washington coast. Previously, NMFS concluded that it could not identify any remaining natural populations of coho salmon in the lower Columbia River (excluding the Clackamas River) that warranted protection under the ESA. The Clackamas River produces moderate numbers of natural coho salmon. The BRT could not reach a definite conclusion regarding the relationship of Clackamas River late-run coho salmon to the historic lower Columbia River ESU. However, the BRT did conclude that if the Clackamas River late-run coho salmon is a native run that represents a remnant of a lower Columbia River ESU, the ESU is not presently in danger of extinction but is likely to become so in the foreseeable future if present conditions continue.

   For southwest Washington coho salmon, uncertainty about the ancestry of coho salmon runs given high historical and current levels of artificial production prevented the BRT from reaching a definite conclusion regarding the relationship between coho salmon in that area and the historical lower Columbia River/southwest Washington ESU. If new information becomes available, the relationship and status of the ESU will be reexamined.

5. Olympic Peninsula. While there is continuing cause for concern about habitat destruction and hatchery practices within this ESU, the BRT concluded that there is sufficient native, natural, self-sustaining production of coho salmon that this ESU is not in danger of extinction and is not likely to become endangered in the foreseeable future unless conditions change substantially.

6. Puget Sound/Strait of Georgia. The BRT was concerned that if present trends continue, this ESU is likely to become endangered in the foreseeable future. Although current population abundance is near historical levels and recent trends in overall population abundance have not been downward, there is substantial uncertainty relating to several of the risk factors considered. These risk factors include widespread and intensive artificial propagation, high harvest rates, extensive habitat degradation, a recent dramatic decline in adult size, and unfavorable ocean conditions. Further consideration of this ESU is warranted to attempt to clarify some of these uncertainties.

The status review for west coast coho salmon was conducted by a team of researchers from the National Marine Fisheries Service (NMFS). This biological review team relied on information in the Endangered Species Act Administrative Record for West Coast Coho Salmon, which was developed pursuant to this review and includes comments, data, and reports submitted by the public and by state, tribal, and federal agencies. The authors acknowledge the efforts of all who contributed to this record, especially the Washington Department of Fish and Wildlife, Oregon Department of Fish and Wildlife, California Department of Fish and Game, U.S. Fish and Wildlife Service, and Northwest Indian Fisheries Commission.

The biological review team for this status review included: Peggy Busby, Dr. David Damkaer, Robert Emmett, Dr. Jeffrey Hard, Dr. Orlay Johnson, Dr. Robert Kope (formerly with the Southwest Fisheries Science Center), Dr. Conrad Mahnken, Gene Matthews, George Milner, Dr. Michael Schiewe, David Teel, Dr. Thomas Wainwright, William Waknitz, Dr. Robin Waples, Laurie Weitkamp, Dr. John Williams, and Dr. Gary Winans, all from the Northwest Fisheries Science Center (NWFSC), and Gregory Bryant from the NMFS Southwest Region. Craig Wingert, from the NMFS Southwest Region, and Steven Stone, from the NMFS Northwest Regional Office, also participated in the discussions and provided information on coho salmon life history and abundance.

Jason Griffith and Megan Ferguson, students from the University of Washington, were instrumental in compiling information on coho salmon hatcheries. Don Vandoornik and Dave Kuligowski (NWFSC) collected new genetic data for the status review, and Kathleen Neely (NWFSC) provided most of the graphics for this document and assisted in the completion of this status review in numerous other ways.