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Factors Affecting the Abundance of Fall Chinook Salmon in the Columbia River

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Factors Affecting the Abundance of Fall Chinook Salmon in the Columbia River AN ABSTRACT OF THE THESIS OF Jack M. Van Hyning for the Ph. D. in Fisheries (Name) (Degree) (Major) Date thesis is presented '' \cxi t8 in (C+( Title FACTORS AFFECTING THE ABUNDANCE OF FALL CHINOOK SALMON IN THE COLUMBIA RIVER Abstract approved (Major professor) A study of the population ecology of Columbia River fall chi- nook salmon, Oncorhynchus tshawytscha (Walbaum), was made in an attempt to determine the cause of a serious decline in this run which occurred runs in the early 1950's. Fluctuations in abundance of major salmon of the North Pacific were examined to detect any coastwide. pattern. Only chinook salmon in Cook Inlet, Alaska, and chum salmon from Oregon to southwestern Alaska showed a similar trend. The following life history stages broken down into pre- and post -decline years were examined: (1) marine life including distribution and migration, growth and maturity, survival rate, oceanography, and commercial and sport fisheries; (2) upstream migration including river fish- eries, gear selectivity, size and age composition of the run, es- capement, and influence of dams, diseases, and water quality; (3) reproduction and incubation including spawning areas and spawning and incubation conditions; and (4) downstream migration which in- cluded predation, dams; and reservoirs, diseases, flow, turbidity and temperature, and estuary life. Salient points of the analysis were: (1) a change in the maturity and survival pattern based on tagged and fin -clipped fish recovered before and after 1950; (2) a signifi- cant negative correlation between sea -water temperature during a year class' first year at sea and subsequent survival; (3) a large increase in the ocean fisheries coincident with the decline in the run; (4) catch -effort statistics of the ocean fishery show a near classic example of the effect of overexploitation; (5) estimates of the contribution of Columbia River chinook to the ocean fisheries based on tag recoveries could be underestimates rather than over- estimates; (6) a significant inverse correlation between estimated ocean catch of Columbia River fall chinook and numbers entering the river; (7) size and age composition of the ocean and river catches decreased coincident with the decline in the run; (8) the gill -net fishery shows little size selectivity by age, size, or sex in the dominant group; (9) fluctuations in abundance of hatchery stocks are related to differences in survival between fingerling and adult; (10) hatchery, lower river, and upriver populations fluctuate in abundance in much the same pattern; (11) optimum escapement is be- tween 90,000 and 100,000 adults, a value that was exceeded during most years; (12) a highly significant negative correlation between numbers of spawners and return per spawner; (13) most of the early dams had no direct effect on fall chinook and the decline in pro- ductivity occurred when river conditions were relatively stable; (14) temperatures at time of migration and spawning for fall chinook have not increased enough to be a serious mortality factor; (15) little relationship between flow, turbidity, and temperature at time of downstream migration and subsequent return was evident ex- cept that high temperatures and high flows (and turbidities) tended to produce poorer runs during certain time periods; and (16) predation and delay of smolts in reservoirs are largely unknown factors, but cir- cumstantial evidence suggests that they were not important in regula- ting fall chinook numbers during the period of the study. Finally, variables that appeared to bear some relationship to fluctuations in abundance of fall chinook were submitted to multiple regression analysis. For the predecline period (1938 -46 brood years), sea -water temperature and ocean troll fishing effort were significant variables (R2 = 0.74). For post decline years (l947 -59 broods), troll had the most influence on total return with ocean temperature and es- capement having lesser effects. For the combined years, troll in- tensity and ocean temperature were the significant variables (R2 = 0.572). Entering interaction of river flow at downstream migration with the other variables brought R2 to 0.754 which means that 75% of the variability in the returning run could be accounted for by these three factors. Return per spawner was so heavily influenced by numbers of spawners that the other factors assumed negligible im- portance. Equations were derived that predicted the returning run in close agreement with the actual run size. Substituting a low and constant troll fishing effort in the equation resulted in the predicted run maintaining the average predecline level. The increase in ocean fishing was the main contributor to the decline of the Columbia River fall chinook run as shown by correlation, by analogy, and by the process of elimination. To demon- strate why other chinook runs have not shown similar declines, it was shown that due to several unique features in Columbia River fall chinook life history they are exposed to much more ocean fishing than other populations. It was emphasized that these conclusions should not be extrapolated to the future or to other species or runs of salmon. FACTORS AFFECTING THE ABUNDANCE OF FALL CHINOOK SALMON IN THE COLUMBIA RIVER by JACK MATTSON VAN HYNING A THESIS submitted to OREGON STATE UNIVERSITY in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY March 1968 APPROVED: Professor of Fisheries In Charge of Major Head o Department of Fisheries and Wildlife AIMOMMDean of Graduate School Date thesis is presented j\WV-k-V q(1 Typed by Shirley Arnett and Janice Jennings ACKNOWLEDGMENTS Many people unknowingly contributed to the development of this thesis by faithfully collecting data over a period of many years. Although too numerous to individually mention, the study would not have been possible without the backlog of information they collected. I particularly appreciate the cooperation of Messrs. Henry Wendler and Donald Kauffman of the Washington Department of Fisheries for making available unpublished reports and data from their department and re- viewing the manuscript. Likewise, Messrs. Arthur L. Oakley and Robert E. Loeffel of the Fish Commission of Oregon were most helpful in supplying material from their files. I am greatly indebted to Messrs. Earl F. Pulford and Charles O. Junge of the Fish Commission of Oregon for advice and guidance on the statistical analysis. Drs. Carl Bond and Charles E. Warren of Oregon State University rendered valuable assistance during preparation and review of the dissertation. Dr. Frederick C. Cleaver reviewed the manuscript, and I appreciate his penetrating comments. I appreciate the early aid and encouragement of Dr. Donald W. Chapman and the patience and assistance of Dr. Thomas E. Kruse and Mr. Robert W. Schoning. Mr. Anthony Netboy of Portland State College read the manuscript and offered editorial comments and the assistance of Mrs. Winona Richey, Fish Commission Librarian, was in- valuable. This study was largely financed by monies received from the sale of salmon -steelhead tags (punch cards) required for persons angling for anadromous fish in Oregon. These funds are to be used for salmon and steelhead research and management projects. TABLE OF CONTENTS Page INTRODUCTION................... ....0.0.........00.00.0.00....0 1 LIFE HISTORY AND RACIAL IDENTIFICATION ...........0000......... 4 Life History of Chinook Salmon 4 Runs and Races of Columbia River Chinook Salmon 9 REVIEW OF POPULATION FLUCTUATIONS IN OTHER SALMON RUNS 17 Chinook Salmon 18 Coho Salmon ................... ...........c 27 Chum Salmon 30 Pink Salmon 000 35 Sockeye Salmon . .. 38 Summary 42 MARINE LIFE OF CHINOOK SALMON 47 Range and Migration 47 Tagging 47 Marking 83 Growth and Maturity 92 Variation in Survival Rate 103 Tagging Experiments 104 Marking Experiments 116 Hatchery Returns 121 Ecology 125 General Oceanography 125 Oceanography and Salmon Ecology 133 Application to Columbia River Fall Chinook Salmon 135 Ocean Fisheries 142 Commercial Troll Fishery 142 Japanese Fishery 172 Sport Fishery 173 Hooking Mortality 183 Recapitulation of Ocean Fisheries 187 UPSTREAM MIGRATION 203 River Fisheries 203 Commercial Fishery 203 Indian Fishery 219 Sport Fishery 224 Size and Age Composition of the Run 225 Escapement 245 Dam Counts 245 Spawning Ground Counts 259 Hatchery Enumeration 263 TABLE OF CONTENTS (Cont'd) Page Gear Selectivity OOOOO OOOOO 271 Optimum Escapement 282 Dams 291 Parasites and Diseases 299 Water Quality. .... OOOOOOOOOOOOOOOOOO ............... OOOOOO . 308 REPRODUCTION AND INCUBATION ... ..e ...............e......e..... 312 Spawning Areas 312 Spawning and Incubation Conditions .......... ......... .....o 318 Time of Spawning and Emergence ......... OOOOOOOOOOOOOOO 0 318 Temperature ............... .................C..........01C 321 Oxygen and Flow. ......... OOOOOOOOOOO ..... OOOOOO 0 OOOOO 326 Pollution and Predation ... ..e.e...eeeeeeee000eeoeeeeoeooe 329 STREAM RESIDENCE AND DOWNSTREAM MIGRATION. ............. OOOOOO 331 General 331 Ecological Factors Affecting Survival 335 Predation 335 Parasites and Diseases 338 Dams and Reservoirs 340 Flow, Turbidity, and Temperature 343 Estuary Conditions 347 MULTIPLE REGRESSION AND RESPONSE SURFACE ANALYSIS............ 351 DISCUSSION....... OOOOOOOOOOOOOOOOOOO O . 0 OOOOOOOO 000 OOOOO 371 S UM MA RY e . o . e e e o e O 80e . o o.. e e. o.. o.. e e. 0. e.. 0 0 0 o e. 386 BIBLIOGRAPHY 402 LIST OF TABLES Table Page 1. Comparison of early and recent tagging of chinook
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