Fishery Manuscript No. 00-2 Optimal Production of Chinook Salmon from the Taku River by Scott A. McPherson David R. Bernard and John H. Clark May 2000 Alaska Department of Fish and Game Division of Sport Fish FISHERY MANUSCRIPT NO. 00-2 OPTIMAL PRODUCTION OF CHINOOK SALMON FROM THE TAKU RIVER by Scott A. McPherson Division of Sport Fish, Douglas, AK David R. Bernard Division of Sport Fish, Anchorage, AK and John H. Clark Commercial Fisheries Division, Helena, MT Alaska Department of Fish and Game Division of Sport Fish-Policy and Technical Services 333 Raspberry Road Anchorage, AK 99518-1599 May 2000 This investigation was made possible, in part, by funding under the Federal Aid in Sport Fish Restoration Act (16 U.S.C. 777-777K). The Fishery Data Series was established in 1987 for the publication of technically-oriented results for a single project or group of closely related projects. Fishery Data Series reports are intended for fishery and other technical professionals. Fishery Data Series reports are available through the Alaska State Library and on the Internet: http://www.sf.adfg.state.ak.us/statewide/divreports/html/intersearch.cfm This publication has undergone editorial and peer review. Scott A. McPherson a Alaska Department of Fish and Game, Division of Sport Fish, Region I P. O. Box 240020, Douglas, AK 99824-0020, USA David R.. Bernard Alaska Department of Fish and Game, Division of Sport Fish, Region II 333 Raspberry Road, Anchorage, AK 99518-1599, USA John H. Clark Alaska Department of Fish and Game, Division of Commercial Fisheries , Headquarters 4240 Jimtown Road, Helena, MT 59602 aAuthor to whom all correspondence should be addressed: e-mail: [email protected] This document should be cited as: McPherson, S. A., D. R. Bernard, and J. H. Clark. 2000. Optimal production of chinook salmon from the Taku River. Alaska Department of Fish and Game, Fishery Manuscript No. 00-2, Anchorage. 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TABLE OF CONTENTS Page LIST OF TABLES ................................................................................................................................................................ ii LIST OF FIGURES............................................................................................................................................................... ii LIST OF APPENDICES...................................................................................................................................................... iii ACKNOWLEDGMENTS ................................................................................................................................................... iv ABSTRACT .......................................................................................................................................................................... 1 INTRODUCTION................................................................................................................................................................. 1 STATISTICS......................................................................................................................................................................... 3 Spawning Abundance .................................................................................................................................................... 3 Smolt Abundance........................................................................................................................................................... 6 Marine Harvests............................................................................................................................................................. 8 Inriver Harvests ........................................................................................................................................................... 10 Production ................................................................................................................................................................... 10 Exploitation Rate ........................................................................................................................................................ 10 ANALYSIS ......................................................................................................................................................................... 10 Measurement Error...................................................................................................................................................... 10 Parameter Estimates .................................................................................................................................................... 13 Smolt Production ......................................................................................................................................................... 16 CONCLUSIONS................................................................................................................................................................. 17 DISCUSSION ..................................................................................................................................................................... 18 RECOMMENDATIONS.................................................................................................................................................... 19 LITERATURE CITED ....................................................................................................................................................... 20 APPENDIX A ..................................................................................................................................................................... 23 APPENDIX B...................................................................................................................................................................... 31 APPENDIX C...................................................................................................................................................................... 37 APPENDIX D ..................................................................................................................................................................... 41 APPENDIX E...................................................................................................................................................................... 49 i LIST OF TABLES Table Page 1. Pearson correlation coefficients among counts of large chinook salmon in five tributaries to the Taku River from 1973 to 1997.................................................................................................................................... 5 2. Combined peak counts from aerial surveys, estimated abundance Nˆ with associated standard errors and estimated 95% confidence intervals for large (O660 mm FL) chinook salmon spawning in the Taku River from 1973 through 1997.................................................................................................................. 5 3. Equations used to expand counts Ct into estimates of abundance Nt of large (O660 mm MEF) chinook salmon spawning in the Taku River .................................................................................................... 6 ˆ O 4. Estimated numbers N a of chinook salmon by age and by large ( 660 mm MEF) females and males spawning in the Taku River from 1973 through 1997 ...................................................................................... 7 5. Estimated abundance of females, smolts, subsequent production of adult salmon, and estimated mean fork length for smolts for several year classes of chinook salmon in the Taku River. ........................ 8 6. Estimated harvests by year and age of chinook salmon bound for the Taku River caught in commercial gillnet fisheries in Taku Inlet and in Canada, in the recreational fishery near Juneau, and in the commercial troll fishery in Southeast Alaska........................................................................................ 11 ˆ 7. Estimated production Ry by age and year class for chinook salmon in the Taku River.............................. 11 ˆ ˆ ˆ ˆ ˆ 8. Estimated large spawners N y , large female spawners N y , production Ry , return rate ( Ry / N y ) ˆ and exploitation rate E y by year class for chinook salmon in the Taku River ............................................