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Home My WebLink AboutAPA353~ ' ' ' ' ...... i '~,-, / ,o e/' ~ ,:' ~~ .)!' .<.' :i' ,, ·, ASSESSMENT OF THE RESERVOIR-RELATED EFFECTS OF THE SKAGIT PROJECT ON DOWNSTREAM FISHERY RESOURCES OF THE SKAGIT RIVER, WASHINGTON by J P. Graybill, R. L. Burgner, J. C. Gislason, P. E. Huffman, K. H. Wyman, R. G. Gibbons, K. W. Kurka, Q. J. Stober, T. W. Fagnan, A. P. Stayman, and D. M. Eggers Final Report for City of Seattle Department of Lighting Seattle, Washington UNIVERSITY OF WASHINGTON COLLEGE OF FISHERIES FISHERIES RESEARCH INSTITUTE UNN:.:r:::::~rr't o~ AL/\C'(A ARCTiC E~1f:Rc:-:: · -·., ·:_ r>1?·:JRMATION Q AN; .. ~1.::H 707 /, ST'<fCET ANCHORAGE, AK 99501 'e' - - - - - ~H ,5Yl·S Sll (; 17 A-8 FISHERIES RESEARCH INSTITUTE College of Fisheries University of Washington Seattle, Washington 98195 FRI-UW-7905 March 1979 ASSESSMENT OF THE RESERVOIR-RELATED EFFECTS OF THE SKAGIT PROJECT ON DOWNSTREAM FISHERY RESOURCES OF THE SKAGIT RIVER, WASHINGTON J P. Graybill, R. L. Burgner, J. C. Gislason, P. E. Huffman, K. H. Wyman, R. G. Gibbons, K. W. Kurka, Q. J. Stober, T; W. Fagnan, A. P. Stayman, and D. M. Eggers Final Report for City of Seattle Department of Lighting Seattle, Washington ARLIS n< 14-:lS <:::'""' .. ...J '6 A'J.~· no. 3S3 Alaska Resources Librar; & Infonnation Services Anchorage, Alaska Approved Submitted March 21, 1979 - - -' -) - - co 00 0) ('I) ~ 0 0 0 LD LD r-- ('1) ('I) 1.0 2.0 3.0 iii CONTENTS INTRODUCTION 1.1 1.2 1.3 1.4 History of the Skagit Project . General Study Objectives Study Area • • . . Acknowledgments . PHYSICAL ENVIRONMENT 2.1 2.2 2.3 Discharge • • . Temperature . 2.2.1 2.2.2 General Discussion Potential Effect of Copper Creek Dam Profile and Gradient PERIPHYTON AND BENTHIC INSECTS 3.1 3.2 3.3 3.4 Introduction Study Area 3.2.1 3.2.2 Sampling Sites Artificial Stream Site Materials and Methods . • . 3.3.1 3.3.2 3.3.3 3.3.4 Physical Parameters . Periphyton . . • . Benthic Insects • • • Experimental Studies Artificial Stream . . . . 3.3.4.1 3.3.4.2 3.3.4.3 3.3.4.4 Flow Fluctuation Experiments Stranding Avoidance Desiccation Survival • Results and Discussion 3.4.1 3.4.2 Physical Parameters 3.4.1.1 3.4.1.2 3.4.1.3 Flow Pattern . Exposure Time Turbidity Periphyton Page 1 1 1 1 4 7 7 36 36 43 51 53 53 53 53 54 57 57 58 59 61 61 61 61 62 62 62 62 66 67 74 ~II iv Page 3.4.2.1 Flow Fluctuation Effects 74 3.4.2.2 Sea:sonal Variation 80 ~ 3. 4. 3 Benthic Insects . . . . . 85 ...,. 3.4.3.1 Flow Fluctuation Effects 85 3.4.3.2 Seasonal Variation 93 3.4.3.3 Composition 97 - 3.4.4 Experimental Studies 101 3.4.4.1 Flow Fluctuation Experiments . 101 3.4.4.2 Stranding Avoidance 111 3.4.4.3 Desiccation Survival . 111 ~ 4.0 PLANKTON DRIFT 115 4.1 Introduction . . . . . . . . . . . . 115 4.2 Study Stations . . . . . 116 4.3 Materials and Methods . . . . 118 4.4 Results and Discussion 119 -5.0 SALMON AND STEELHEAD . .. . . 141 5.1 General Freshwater Life History 141 -5.2 Hatchery Production . . . . . . . 141 5.3 Escapement . . . . . . . . . . 146 5.4 Relationships between Skagit River Flows and Chinook Salmon Returns 146 5.4.1 Introduction 146 5.4.2 Materials and Methods 151 -· 5.4.2.1 Flow Data . . . . 151 5.4.2.2 Fisheries Data . 151 - 5.4.3 Results and Discussion . . . . 151 5.4.3.1 Spawning Flows 151 5.4.3.2 Incubation Flows . 151 5.4.3.3 Rearing Flows 155 -·, 5.5 Steelhead Catch . . . . . . . . . . 155 5.6 Angler Survey 160 5.6.1 Introduction . . . . . . . . . . . 160 5.6.2 Materials and Methods . . . . . 160 5.6.3 Results and Discussion 161 """" v ,_,., Page 6.0 SPAWNING . . . . . . . . . . . . . . . 165 -6.1 Introduction 165 . . . . . . . . . . 6.2 Description of Study Area . 165 6.3 Materials and Methods . . . . . 170 6.3.1 Spawning Depths and Velocities 170 6.3.2 Spawner Observations . . . . . . 170 F 6.3.3 Relationships of Spawnable Area to Discharge 171 6.3.4 Potential Spawnable Area 171 6.4 Results and Discussion . . . . 172 6.4.1 Spawning Depths and. Velocities 172 ~ 6.4.1.1 Chinook Salmon . . . . . 172 6.4.1.2 Pink Salmon . . . . . . . . 172 6.4.1.3 Chum Salmon 177 6.4.1.4 Steelhead Trout 177 6.4.1.5 Comparison to Literature Value 177 6.4.2 Timing of Spawning 177 -6.4.2.1 Chinook Salmon 177 . . . . 6.4.2.2 Pink Salmon . . . . 188 6.4.2.3 Chum Salmon 188 ·-6.4.2.4 Coho Salmon 192 6.4.2.5 Steelhead Trout 192 6.4.3 Spawner Distribution 192 - 6.4.3.1 Chinook Salmon . . . 192 6.4.3.2 Pink Salmon . . . . . . . . 196 F 6.4.3.3 Chum Salmon 204 6.4.3.4 Coho Salmon . . . . . . . . . 206 6.4.3.5 Steelhead Trout 206 6.4.3.6 Spawner Surveys--Goodell Creek 207 -6.4.4 Low Flow Observations . 207 6.4.4.1 Chinook Salmon . 207 6.4.4.2 Pink Salmon 209 6.4.5 Relations hips of Spawnable Area to Discharge . . . . . . . . . . . . . . . 211 ""'" vi Page ,.., 6.4.5.1 Chinook Salmon 211 6.4.5.2 Pink Salmon 224 -6.4.5.3 Chum Salmon . . . . 224 6.4.5.4 Steelhead Trout 225 6.4.6 Potential Spawnable AI'ea 225 ~ 6.4.6.1 Chinook Salmon . . . 228 6.4.6.2 Pinlt Salmon 232 6.4.6.3 Chum Salmon 234 6.4.6.4 Steelhead Trout 237 6.4.6.5 Potential Spawnable Area ~ and Escapement 241 7.0 INCUBATION AND EMERGENCE 243 iii!IF."'l· 7.1 Introduction 243 7.2 Literature Review . . 245 7.3 Study Area 247 -7.4 Materials and Methods 249 7.4.1 Embryonic Development 249 -7.4.2 Timing of Emergence 252 7.5 Results . . . . . . . . . . 253 - 7.5.1 Embryonic Development 253 7.5.1.1 Chinook Salmon 253 """' 7.5.1.2 Pink Salmon 273 7.5.1.3 Chum Salmon . . . . 276 7.5.1.4 Coho Salmon 276 7.5.1.5 Theoretical Timing to Yolk Absorption 281 288 -7.5.2 Timing of Emergence . . . 7.5.3 Fry Condition at Emergence 293 7.6 Discussion 297 7.6.1 Hatching 297 7.6.2 Yolk Absorption and Emergence 299 7.6.3 Temperature Unit Compensation . 300 7.6.4 Fry Condition at Emergence 301 7.6.5 Effects of Altered Temperature ~ Regimes . . . . . . . . . . . . . 302 7.6.5.1 Chinook Salmon 302 7.6.5.2 Pink, Chum, and Coho Salmon 111!¥·' and Steelhead Trout . . . . 303 .~ vii - Page 7.6.6 Potential Effects of Copper Creek Dam 304 8.0 FRY REARING . . . . . . . . . . . . . . 307 8.1 Fry Availability, Growth, and Feeding 307 8.1.1 Introduction . . . . 307 8.1.2 Fry Electrofishing Sampling Stations 308 8.1. 3 Materials and Methods . . . . . . . 310 ~ 8.1.3.1 Electroshocking for Fry 310 8.1.3.2 Fry Availability . . . . . . . . . 311 -8.1.3.3 Fry Size and Condition 312 . 8.1.3.4 Fry Diet . 312 ,.. .... 8.1.4 Results and Discussion . . . . . . 312 8.1.4.1 Chinook Salmon Fry Availability . . . . . . 312 8.1.4.2 Chinook Salmon Fry Size and Condition after Emergence 323 8.1.4.3 Chinook Salmon Fry Diet 360 .-8.1.4.4 Pink Salmon Fry Availability 377 . 8.1.4.5 Pink Salmon Fry Size and Condition after Emergence 377 -8.1.4.6 Pink Salmon Fry Diet 385 . . . 8.1.4. 7 Chum Salmon Fry Availability . 385 8.1.4.8 Chum Salmon Fry Size and ,.,.... Condition after Emergence 391 8.1.4.9 Chum Salmon Fry Diet . . . . . . . 391 8 .1.4 .10 Coho Salmon Fry Availability . 410 8.1.4.11 Coho Salmon Fry Size and !"""' Condition after Emergence 423 8.1.4.12 Coho Salmon Fry Diet . . 447 .8.1.4.13 Rainbow-Steelhead Trout -Fry Availability 447 . . . . 8.1.4 .14 Rainbow-Steelhead Trout Fry Size and Condition after : ·-Emergence . . . . . . . 447 8.1.4.15 Rainbow-Steelhead Trout . Fry Diet . . . . . 481 8.2 Fry Stranding . . . . . . . . . . 481 8.2.1 Introduction . . . . 481 8.2.2 Materials and :Hethods . . • . 492 ..... - viii Page ~· 8.2.2.1 Mortality Due to Stranding 492 8.2.2.2 Stranding Selectivity 493 _,._ 8.2.2.3 Ramping Rates . . . . 494 8.2.2.4 Experimental Studies 494 8.2.3 Results and Discussion 497 - 8.2.3.1 Mortality Due to Stranding . 497 8.2.3.2 Stranding Selectivi.ty 509 ~' 8.2.3.3 Ramping Rate . . . . 512 8.2.3.4 Experimental Studies 517 ~ 8.3 Residence Time of Chinook Salmon Fry 520 8.3.1 Introduction . . . . . . 520 8.3.2 Details of the Fry Marking Study 520 ~ 8.3.3 Results . . . . . . . . . . 522 8.3.3.1 Marking Mortality and """" Mark Retention . . . . . 522 8.3.3.2 Estimation of Pattern Emergence . . . . . . 522 --8.3.3.3 Estimated Residence Time - Steady State Model . . 527 8.3.3.4 Estimated Residence Time - Simulation Model . 534 8.3.4 Discussion . . . . 542 ~ 8.3.4.1 Future Work 543 8.4 Creek Surveys . . . 544 ~ . 8.4.1 Introduction . . . . . . . . . . 544 8.4.2 Study Sites 544 -8.4.3 Materials and Methods . 544 8.4.4 Results and Discussion . . . . 545 8.4.4.1 Newhalem Creek 545 ~! . 8.4.4.2 Goodell Creek 545 8.4.4.3 Thornton Creek . 548 8.4.4.4 Sky Creek 548 -·· 8.4.4.5 Damnation Creek . . . . . 548 8.4.4.6 Alma Creek . . . . 548 8.4.4.7 Copper Creek . . . 548 """'' 8.4.4.8 General Discussion . . 548 t~~Jlf:•. ·- ·- - - - - - - 9.0 ix OTHER FISHES 9.1 Introduction .••• 9.2 Study Sites . 9.3 Materials and Methods . 9.4 Results and Discussion 9.4.1 9.4.2 9.4.3 9.4.4 9.4.5 Availability . , • . Length and Weight • Sexual Maturity . Diet . . . . . . Incidental Species 10.0 SUMMARY AND CONCLUSIONS ...... . 10.1 Periphyton and Benthic Insects 10.2 10.3 10.4 10.5 10.6 10 .1.1 10 .1. 2 10 .1. 3 Periphyton . . . . . Benthic Insects • . . Experimental Studies Plankton Drift . . . . . . . . Relationships Between Skagit Flows and Chinook Salmon Returns . Angler Survey . . Spawning . . . . . . . . . . . . . . . . . . 10.5.1 Spawning Depths and Velocities 10.5.2 Timing of Spawning 10.5.3 Spawner Distribution 10.5.4 Low Flow Observations . . 10.5.5 Relationship of Spawnable Area to Discharge 10.5.6 Potential Spawnable Area Incubation and Emergence Chinook Salmon . . . . . 10.6.1 10.6. 2 10.6.3 Pink, Chum, and Coho Salmon and Steelhead Trout • • • ~ . Temperature Effects of Copper Creek Dam . 10.7 Fry Rearing .• 10.7.1 10.7.2 10.7.3 10.7.4 Fry Availability Fry Size and Condition after Emergence •• Fry Diet Fry Stranding • . . . . . . . . . . . . . . . . . . . . . . Page 551 551 551 551 552 552 554 554 554 561 563 563 563 563 564 564 565 565 566 566 566 566 567 567 568 569 569 571 572 572 572 573 575 575 X - Page ~j 10.7.5 Residence Time of Chinook Salmon Fry . . . . . . 576 10.7.6 Creek Surveys . . . . . . . 576 - 10.8 Other Fishes . . . . . . . . . . . . 577 11.0 IMPACT . . . . . . . . . . . . . . . . . 579 11.1 Copper Creek Project . . . . 579 11.1.1 Periphyton and Benthic Insects 579 11.1. 2 Plankton Drift . . . . . . . . . 583 11.1.3 Spawning Area . . . . . . . . . . . 583 11.1.4 Incubation and Emergence 585 11.1.5 Fry Rearing . . . . . . . . . . . 585 11.1.6 Creeks in Project Area 591 -· 11.1. 7 Other Fishes 591 12.0 REFERENCES . . . . . . . . . 592 ~ 12.1 Physical Environment . . . . . 592 12.2 Periphyton and Benthic Insects . . . . . 592 12.3 Plankton Drift . . . . 594 ~I 12.4 Salmon and Steelhead . . . . . . . . 596 12.5 Spawning . . . . . . 597 12.6 Incubation and Emergence . . . . 599 f'RI,~.., 12.7 Fry Rearing . . . . . . . . . 600 12.8 Other Fishes . . . . . . . 601 - - - '~ ..... Table No. 1.1 1.2 2.1 xi LIST OF TABLES 1.0 INTRODUCTION Events in the development of the Skagit Project affecting downstream flow and temperature patterns in the Skagit River . . . . . . . Physical data for the present and proposed reservoirs on Skagit River . . . . . . . . 2.0 PHYSICJ\L ENVIRONHENT Compilation of extreme daily discharges and ratio of maximum to minimum discharge for water years 1970 to 1976 ..... , .... 2.2 Mean annual discharge, drainage area, and discharge ~er square mile of drainage area for selected sites on the mainstem Skagit River . . . . . . . . . . . . . . . . 2.3 Mean annual discharge and drainage area for selected Skagit River tributaries . . . . . . 2.4 Specifications of Copper Creek (to 495-ft elevation) and Diablo reservoirs . . . 2.5 Temperature difference between surface and bottom in degrees F. for Diablo Reservoir . . 3.0 PERIPHYTON AND BENTHIC INSECTS 3.1 Physical characteristics at sampling stations 3.2 Mean daily range in water level ( ft) during .each month in 1976 at the Skagit at Newhalem and Marblemount, the Sauk, and the Cascade gaging stations . . . . . . . . . . . . . . 3.3 Mean daily range in water level (ft) during each month in 1977 at the Skagit at Newhalem and Marblemount, the Sauk, and the Cascade gaging stations . . . . . . . . . . . . . . Page 3 35 . . 37 . . . 37 . . . . 47 . . . . 47 . . . 56 . . 64 . . . . 65 Table No. 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 xii Percentage of time that the artificial sub- strate periphyton samplers were exposed to desiccation during the six-week period prior to sampling • • • • . . . . . . . . . . . . . . Percentage of time that the streambed at periphyton sampling locations was exposed to desiccation during the six-week period prior to sampling . . . • . . . . . . . Percentage of time that the streambed at benthic sampling locations was exposed to desiccation during the two-week period prior to sampling . . . . . Distance (ft) from the permanent marker near the high water line to benthic insect and periphyton sample sites along the transects at sampling stations . . . . . . Mean monthly turbidity (J.T.U.) at stations on the Skagit, Cascade, and Sauk rivers during 1976 . . . . . . . . . . . . . . . Mean monthly turbidity (J.T.U.) at stations on the Skagit, Cascade, and Sauk rivers during 1977 . . . . . . . . . . . . . . . . Range of chlorophyll ~ values in the Skagit, . . . . Sauk, and several other North Americ!'ln streams Percent composition of benthic insects at sampling stations during May 1976 . . . .. . Percent composition of benthic insects at sampling stations during July 1976 . . . . Percent composition of benthis insects at sampling stations during September 1976 . . . Percent composition of benthic insects at sampling stations during November 1976 . . Mean number of insects per substrate tray in experimental and control artificial stream channels before and after experi- mental flow fluctuation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 68 69 ~ 70 71 ~ 72 73 84 ~. 99 99 ....... 100 lfiSB-~\ 100 -· 107 '"'"" xiii ~ Table No. Page -3.16 Percent composition of benthic insects in experimental and control artificial stream channels before and after one week of periodic exposure . . . . 109 3.17 Percent composition of benthic insects in -experimental and control artificial stream channels before and after 48 hr of continuous exposure . . 109 3.18 Percent composition of drifting aquatic insects in the experimental artificial stream channel during dewatering and rising water and in the control channel during the same time period . . . . . 110 3.19 Percentage of aquatic insect larvae stranded and not stranded during experimental flow reductions . . . . . . . 112 3.20 Percent mortality of aquatic insect larvae exposed to desiccation for 24 hr on dry and damp substrates . . . . . 112 4.0 PLANKTON DRIFT -Numbers of organisms/m3 from 4.1 plankton pump samples, April 28-29, 1977 . . . . . . . . . . . 120 ,_ 4.2 Numbers of organisms/m 3 from plankton pump samples, May 23-24, 1977 . . . . . . . . . . . 121 -4.3 Numbers of organisms/m3 from plankton pump samples, June 23-24, 1977 . . . . . . . •· . . 122 4.4 Numbers of organisms/m3 from plankton pump samples, July 27-28, 1977 . . . . . . . . . . . 123 4.5 Numbers of organisms/m 3 from plankton pump ·-samples, August 23-24, 1977 . . . . . . . . . 124 4.6 Numbers of organisms/m3 from plankton pump ""'"" samples, September 20-21, 1971 125 . . . . . . . 4.7 Numbers of organisms/m 3 from plankton pump -samples, October 22-23, 1977 . . . 126 - Table No. 4.8 4.9 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 5.1 5.2 xiv Numbers of organisms/m3 from plankton pump samples, November 19-20, 1977 .... 3 Numbers of organisms/m from plankton pump samples, December 19-20, 1977 Seattle City Light flow data for the Skagit plants, 1977 . . . SeasonRl fluctuations in numbers of organ- isms/m3 at the Ross Tailrace Station . . . Seasonal fluctuations in numbers of organ- isms/m3 at the Diablo Forebay Station Seasonal fluctuations in numbers of organ- isms/m3 at the Diablo Tailrace Station .• Seasonal fluctuations in numbers of organ- isms/m3 at the Gorge Forebay Station . . . Seasonal fluctuations in numbers of organ- isms/m3 at the County Line Station .... Seasonal fluctuations in numbers of organ- isms/m3 at the Talc Mine Station . . . . . Seasonal fluctuations in numbers of organ- ismsfm3 at the Marblemount Station . . . . Seasonal fluctuations in numbers of organ- ismsfm3 at the Concrete Station . . . 5.0 SALMON AND STEELHEAD Fish production of the Skagit Hatchery and fish plants by WDF in the Skagit system from Boyd Creek (river mile 44.7) to Newhalem, 1952-1977 . . . . . . . . . . . Summary of fish plants in the Skagit River system between Concrete and Ross Dam, 1974-1977 5.3 Estimated Skagit River system spawning escapements 5.4 Salmon escapement to the Skagit Hatchery racks, 1949-1977 . . . ..... . Page 127 128 129 ~' 131 132 -133 134 135 136 137 138 142 147 149 150 Table No. 5.5 5.6 5.7 - 5.8 5.9 6.1 ..... 6.2 , .... 6.3 6.4 - 6.5 - 6.6 6.7 XV Compilation of selected streamflow data for Skagit River near Alma Creek and at Newhalem (USGS) and Skagit River escapement and rela- tive run size data (WDF) . . . . . . . . . . Sport harvest of Skagit system winter-run (Nov- Apr) steelhead trout, 1961-1962 through 1976- 1977 1 e 1 a I 1 I 1 I I 4l I e I I II I 1 I Sport harvest of Skagit system summer-run (May-Oct) steelhead trout, 1962 through 1976 (WDF) . . . . • . . • . . . • . . Skagit system Treaty Indian harvest of winter- run steelhead, 1953-1954 through 1976-1977 (WDG) Summary of Skagit River angler survey conducted between Newhalem and Rockport, 15 June 1977 to 13 January 1978 ...•..•....... 6.0 SPAWNING Location of Skagit River sample transects by river mile . . . . . . . . . . . Depth and velocity criteria for depths and velo- cities preferred by spawning salmon and trout including the 80% ranges for Skagit River chinook, pink, and chum salmon, and steelhead trout ..• Secchi disk readings (in inches) at three study locations in the Skagit River, 1977 ..•.•. Summary of steelhead trout redd counts from aerial surveys of mainstem Skagit and Sauk rivers, 1975- 19 7 8 (WDG) • • • .. • • • • . • . • • • . • • • Chinook salmon redd counts from aerial photographs of the Skagit River from Newhalem to th~ Sauk River Chinook salmon redd counts made by the Washington Department of Fisheries from helicopter surveys of the Skagit River from Newhalem 'to the Sauk River . Area spawned by pink salmon as determined from hel- icopter survey of the Skagit River from Newhalem to the Sauk River, October 11, 1977 .•..•.•..• Page 152 157 158 159 162 169 182 187 193 195 197 203 Table No. 6.8 6.9 6.10 6.11 6.12 6.13 6.14 6.15 6.16 6.17 xvi Spawner surveys for Goodell Creek, 1975, 1976, and 1977 •.• The peak spawning discharges and associated areas suitable for spawning for chinook, pink, and chum salmon, and steelhead trout, in each of the four reference reaches Discharge classification system and sampling scheme for the 20 sample transects in the upper Skagit River ••...•• , Mean spawnable widths for chinook, pink, and chum salmon in the Skagit River between Newhalem and the Baker River . . . . , . , . , . , Estimated spawnable area for chinook, pink, and chum salmon in the Skagit River between Newhalem and the Baker River . • . • • • • . . , . • • . Percentage of the total estimated spawnable area for chinook salmon in various sections of the Skagit River between Newhalem and the Baker River, compared to the percentage of the total river miles in each section . . . . . . . . . . . . . . . . Percentage of the total estimated spawnable area for chinook salmon in various sections of the Skagit River between N.ewhalem and the Sauk River, · compared to the percentage of the total river miles in each section . • . . . • . . • . . . • . • Percentage of the total estimated spawnable area for pink salmon in various sections of the Skagit River between Newhalem and the Baker River, com- pared to the percentage of the total river miles in each section . • . . . • . . . . Percentage of the total estimated spawnable area for pink salmon in various sections of the Skagit River between Newhalem and the Sauk River, com- pared to the percentage of the total river miles in each section • • . . , • , , • , • Percentage of the total estimated spawnable area for chum salmon in various sections of the Skagit River between Newhalem and the Baker River • • . , - -' Page 208 -223 227 229 230 231 233 235 236 238 Table No. 6ol8 6.19 7.1 7.2 7o3 7o4 7.5 7.6 - 7.7 7.8 xvii Mean spawnable width and estimated spawnable area for steelhead trout in the Skagit River between Newhalem and the Baker River o o o o Percentage of the total estimated spawnable area for steelhead trout in various sections of the Skagit River between Newhalem and the Baker River, compared to the percentage of the total river miles in each section o o . o 7o0 INCUBATION AND EMERGENCE Summary of literature information on the timing of the early life history of summer- fall chinooks under natural conditions Summary of incubation studies for 1974-75 and 1976-77 cycles for eggs from Skagit River chinook salmon incubated near Newhalem Hatching data from 1977-1978 incubation studies for eggs from Skagit River chinook, pink, chum, and coho salmon incubated in the Skagit (near Newhalem), Cascade, and Sauk rivers o o ... Yolk absorption data from 1977-1978 incubation studies for eggs from Skagit River chinook, pink, chum, and coho salmon incubated in the Skagit (near Newhalem), Cascade, and Sauk rivers Egg weight, egg diameter, number of temperature units required to mean yolk absorption and to mean hatching, and mean incubation temperature to yolk absorption, for eggs taken fLam four chinook females in 1976 o o o . • Summary of incubation studies using eggs from chinook female #3-76 fertilized on October 6, 1976 and incubated at four sites o .• o o . o Summary of incubation studies for eggs from Skagit River chinook salmon incubated at the University of Washington Hatchery for 1976-77 cycle . . . . . . . . . . . . . . . . . Length, weight, and condition factor, of juvenile chinook salmon from one female and sampled from incubation box located in Skagit River near Newhalem, 1974-75 o o o o o o . o . Page 239 240 246 255 257 258 260 262 266 269 Table No. 7.9 7.10 7.11 7.12 7.13 xviii Length, weight, and condition factor of juvenile chinook salmon from four females and sampled from incubation boxes located in Skagit River near Newhalem, 1976-77 Length, weight, and condition factor of juvenile chinook salmon from female #3-76 and sampled from incubation boxes located in Cascade and Sauk rivers, 1976-77 Length, weight, and condition factor of juvenile chinook salmon from two females and sampled from incubation boxes located University of Washington Hatchery, 1976-77 Lengths and weights of four pink salmon females with respective egg weights and diameters Lengths and weights of four chum females with respective egg weights and diameters 7.14 Summary of incubation studies using eggs from four chum females incubated under three different constant temperature re- gimes at the University of Washington 7.15 7.16 7.17 7.18 7.19 Hatchery . . . . • . . . • . . . . Su~~ary of incubation studies using eggs from two coho females incubated under three different constant temperature re- gimes Comparison of calculated dates to mean yolk absorption for chinook, pink, and chum s a lmon . . . . . . .. . . . .. • o • • • Comparison of calculated mean dates of completion of yolk absorption for steelhead trout based on temperature records • . Comparison of calculated mean dates of com- pletion of yolk absorption for chinook, pink, and chum salmon based on temperature records Comparison of calculated mean dates of com- pletion of yolk absorption for chinook, pink, and chum salmon based on temperature records • . • . • . • . • • . • . . • . Page 270 271 272 274 277 279 282 283 285 286 287 /FP.".· J - - )., - Table No. 7.20 7.21 7.22 7.23 7.24 xi X: Comparison of calculated mean dates of completion of yolk absorption for steelhead trout based on temperature records .. Comparison of calculated mean dates of completion of yolk absorption for steelhead trout based on temperature records •.• Data on juvenile chinook salmon captured in emergent nets over natural redds, 1975 .. Comparison of juvenile chinook salmon held in incubation box after yolk absorption and natural fry captured by electrofishing, 1975 Length, weight, and condition factor of chinook alevins emerging from gravel sub- strate at University of Washington Hatchery, 19 7 6-77 . . . . . . . ; . . • . . . 7.25 Comparison of calculated dates to mean yolk absorption for chinook, pink, and chum sal- mon, and steelhead trout, based on tempera- 8.1 8.2 8.3 8.4 8.5 8.6 ture records ~ . . • • • . . . . . . . • • 8.0 FRY REARING Chinook fry catches at Skagit Basin sampling sites using electrofisher, 1975 brood .•.• Summary of chinook fry catch and density data data from standardized electrofishing efforts at two Skagit River sampling sites, 1975 brood Chinook fry catches at Skagit Basin sampling sites using electrofisher, 1976 brood Summary of chinook fry catch and density data from standardi~ed electrofishing efforts at three Skagit River sampling sites, 1976 brood Chinook fry catches at Skagit Basin sampling sites using electrofisher, 1977 brood Summary of chinook fry catch and density data from standardized electrofishing efforts at three Skagit River sampling sites, 1977 brood Page 289 290 291 296 298 305 314 316 317 318 320 322 Table No. 8.7 8.8 8.9 8.10 8.11 8.12 8.13 8.14 8.15 8.16 8.17 XX Mean lengths, weights, and condition of Skagit River chinook fry captured electroshocking at sites near County 1973 brood . • • • . • , • . • . factors by Line, . . . . . . .. Mean lengths, weights, and condition factors of Skagit River chinook fry captured by elec- troshocking at sites near Talc Mine, 1973 brood Mean lengths, weights, and condition factors of Skagit River chinook fry captured by elec- troshocking at sites near Marblemount, 1973 brood Mean lengths, weights, and condition factors of Cascade River chinook fry captured by electro- shocking, 1973 brood , •....••..... Mean lengths, weights, and condition factors of Sauk River chinook fry captured by electro- shocking, 1973 brood . . • . . . . . • . . . Mean lengths, weights, and condition factors of Goodell Creek chinook fry captured by either e1ectroshocking or fyke netting, 1973 brood • . . . • . . . • . Mean lengths, weights, and condition factors of Bacon Creek chinook fry captured by either electroshocking or fyke ne~ting, 1973 brood . • . . • . • . . . . Mean lengths, weights, and condition factors of Diobsud Creek chinook fry captured by either electroshocking or fyke netting, 1973 brood .. Mean lengths, weights, and condition factors of chi~ook fry from the upper three Skagit sites captured by electroshocking, 1974 brood .• Mean lengths, weights, and condition factors of Sauk chinook fry captured by electroshocking, 197 4 brood . . . . . . . . . • . . . . . . Mean lengths, weights, and condition factors of Cascade chinook fry captured by electroshocking, 1974 brood •..•...•.•.....•... $'T'i Page 324 325 326 327 328 329 330 - 331 332 333 334 xxi Table No. Page 8.18 Mean lengths, dry weights, and condition factors of chinook fry captured by elec- troshocking, 1974 brood . . . . . . . . . . . . . . 335 8.19 Chinook fry stomach contents, Skagit River, 1974 brood . . . . . . . . . . . . . . . . . . 361 8.20 Chinook fry stomach contents, Cascade River, 1974 brood . . . . . . . . . . . . . . . . 363 8.21 Chinook fry stomach contents, Sauk River, 1974 brood . . . . . . . . . . . . . . . . . . . . . 365 •""~'\ 8.22 Chinook fry stomach contents, Skagit River, 1975 brood . . . . . . . . . . . . . . . . . . . . 368 8.23 Chinook fry stomach contents, Cascade River, 1975 brood . . . . . . . . . . . . . . 369 8.24 Chinook fry stomach contents, Sauk River, ~-1975 brood . . . . . . . . . . . . . . . . . . . 370 8.25 Chinook fry stomach contents, Skagit River, 1976 brood . . . . . . . . . . .. . . . . . . 371 8.26 Chinook fry stomach contents, Cascade River, ·-1976 brood . . . . . . . . . . . . . . . . 372 8.27 Chinook fry stomach contents, Sauk River, 1976 brood . . . . . . . . . . . . . . . . . . 373 8.28 Chinook fry stomach contents, summary of 1975 and 1976 broods . . . . . . . . . . . . . . . 374 . ~ 8.29 Yolk in emerged chinook fry, upper three Skagit sites, 1975 brood . . . . . . . . . . . . 375 8.30 Yolk in emerged chinook fry, Cascade River, 1975 brood . . . . . . . . . . . . . . . . . . 375 8.31 Yolk in emerged chinook fry, Sauk River, 1975 brood . . . . . . . . . . . . . . . . . . . . 375 """ 8.32 Yolk in emerged chinook fry, upper three Skagit sites, 1976 brood . . . . . . . . . . . . 376 ~ 8.33 Yolk in emerged chinook fry, Cascade River, 1976 brood . . . . . . . . . . . . . . . . . 376 Table No. 8.34 8.35 8.36 8.37 8.38 8.39 8.40 8.41 8.42 8.43 8.44 8.45 8.46 xxii Yolk in emerged chinook fry, Sauk River, 1976 brood . • • . . . • . . . . . • . • Mean lengths, weights, and condition factors of pink salmon fry captured by electroshocking in the Skagit River, 1973 brood . . . . • . Mean lengths, weights, and condition factors of pink salmon fry captured by either electro- shocking or fyke netting in Skagit tribu- taries, 1973 brood • . • . ..• Pink fry catches at Skagit Basin sampling sites using electrofisher, 1975 brood Pink salmon catches at Skagit Basin sampling sites using electrofisher, 1977 brood . • • Summary of pink fry catch and density data from standardized electrofishing efforts at three Skagit River sampling sites, 1977 brood . . . . . . . . . . . . . . . . . . Mean lengths, weights, and condition factors of Skagit and Sauk rivers pink salmon fry captured by electroshocking, 1975 brood • • Mean lengths, weights, and condition factors of pink salmon fry captured by electroshocking at the County Line Station in 1978 . . . • Mean lengths, weights, and condition factors of pink salmon fry captured by electroshocking at the Marblemount Station in 1978 • • . . . Mean lengths, weights, and condition factors of pink salmon fry captured by electroshocking at the Rockport Station in 1978 . • . . • . . . Mean lengths, weights, and condition factors of pink salmon fry captured by electroshocking at the Concrete Station in 1978 . . . • Yolk in emerged pink salmon fry, 1977 brood Pink salmon fry stomach contents, Skagit River and Cascade River, 1977 brood •••••.... - Page 376 378 379 Mll"· 380 381 383 384 386 387 388 389 389 390 Table No. 8.47 8. 48 8.49 8.50 8.51 8.52 8. 53 8.54 8.55 -8.56 8.57 8.58 8.59 8.60 xxiii Mean lengths, weights, and condition factors of chum salmon fry captured by electroshocking, 1973 brood •• o •• o ••• o ••••• Chum fry catches at Skagit Basin sampling sites using electrofisher, 1975 brood .... o Chum fry catches at Skagit Basin sampling sites using electro fisher, 1976 brood . . , Summary of chum fry catch and density data from standardized electrofishing efforts at three Skagit River sampling sites, 1976 brood o ••• Chum salmon catches at Skagit Basin sampling sites using electrofisher, 1977 brood Summary of chum fry catch and density data from standardized electrofishing efforts at three Skagit River sampling sites, 1977 brood Mean lengths, weights, and condition factors of Skagit and Sauk rivers chum salmon fry captured by electroshocking, 1975 brood ... Mean lengths, weights, and condition factors of chum salmon fry captured by electrofishing at the County Line Station, '1976 brood Mean lengths, weights, and condition factors of chum salmon fry captured by electrofishing at the Talc Mine Station, 1976 brood ...• Mean lengths, weights, and condition factors of chum salmon :ry captured by electrofishing at the Marblemount Station, 1976 brood Mean lengths, weights, and condition factors of chum salmon fry captured by electrofish- ing at the Rockport Station, 1976 brood o •• Mean lengths, weights, and condition factors of Cascade and Sauk River chum salmon fry captured by electrofishing, 1976 brood Chum fry stomach contents, 1975 brood, April through June, 1976 . o • • o • • • • o • • • Chum fry stomach contents, 1976 brood, April through June, 1977 .......•.... o Page 392 393 394 396 397 398 399 400 401 402 403 404 408 409 Table No. 8.61 8.62 8.63 8. 64 8.65 8.66 8.67 8.68 8.69 8.70 8. 71 8. 72 8.73 xxiv Mean lengths, weights, and condition factors of Skagit River coho fry captured by electroshocking at sites near County Line, 1973-74 brood ..••••••... Mean lengths, weights, and condition factors of Skagit River coho fry captured by elec- troshocking near Talc Mine, 1973-74 brood Mean lengths, weights, and condition factors of Skagit River coho fry captured by elec- troshocking near Marblemount, 1973-74 brood . Mean lengths, weights, and condition factors of Cascade River coho fry captured by elec- troshocking, 1973-74 brood • • • • . . . . . Mean lengths, weights, and condition factors of Sauk River coho fry captured by electro- shocking3 1973-74 brood .••••••.••. Mean lengths, weights, and condition factors of Goodell Creek coho fry captured by either electroshocking or fyke netting, 1973-74 brood Mean lengths, weights, and conditjon factors of Bacon Creek coho fry captured by either electroshocking or fyke netting, 1973-74 brood . . . . . . . . . . . . . . . . . . . . Mean lengths, weights, and condition factors of Diobsud Creek coho fry captured by either electroshocking or fyke netting, 1973-74 brood Coho fry catches at Skagit Basin sampling sites using electrofisher, 1975-76 brood· Coho fry catches at Skagit Basin sampling sites using electrofisher, 1976-77 brood Coho salmon catches at Skagit Basin sampling sites using electrofisher, 1977-78 brood Mean lengths, weights, and condition factors of coho salmon fry captured by electroshocking at the County Line Station in 1977 • • • • • . Mean lengths, weights, and condition factors of coho salmon fry captured by electroshocking at Talc Mine Station in 1977 . • . • • • . . • . . Page 411 412 413 414 415 416 417 ~· 418 419 421 422 427 428 """'' XXV '""" Table No. Page PI' 8.74 Mean lengths, weights, and condition factors of coho salmon fry captured by electroshock- ing at Marblemount Station in 1977 . . . . . . . . . . 429 '""" 8.75 Mean lengths, weights, and condition factors of coho salmon fry captured by electroshocking at Rockport Station in 1977 . . . . . . . . . . . . . 430 8.76 Mean lengths, weights, and condition factors !"""' of coho salmon fry captured by electroshocking at Cascade River in 1977 . . . . . . . . . . . . . . 431 8. 77 Mean lengths, weights, and condition factors of coho salmon fry captured by electroshocking at Sauk River in 1977 . . . . . . . . . . . . . . . . 433 8. 78 Mean lengths, weights, and condition factors of coho salmon fry captured by electroshocking at Goodell Creek in 1977 . . . . . . . . . . . . . 434 8.79 Nean lengths, weights, and condition factors of coho salmon fry captured by electroshocking at Bacon Creek in 1977 . . . . . . . . . . . . . . . . 435 - 8.80 Nean lengths, weight::;, and condition factors of coho salmon fry captured by e1ectroshocking at Diobsud Creek in 1977 . . . . . . . . . . . . 436 8. 81 Coho fry stomach contents, 1975-76 brood, upper ~ three Skagit sites . . . . . . . . . . . . . . . 448 8.82 Coho fry stomach contents, 1975-76 brood, lower two Skagit sites . . . . . . . . . . . . . . . . 450 8.83 Coho fry stomach contents, 1975-76 brood, Cascade River . . . . . . . . . . . . . . . . . . . . . 452 8.84 Coho fry stomach contents, 1975-76 brood, Sauk River . . . . . . . . . . . . . . . . . . 454 -8.85 Coho fry stomach contents, summary of 1975,-76 brood . . . . . . . . . . . . . . . . . . . . . . . . . 455 I ,o:;li~ 8.86 Mean lengths, weights, and condition factors of rainbow-steelhead fry captured by either electroshocking or fyke netting, 1974 brood . . . . . 456 '""" 8.87 Rainbow-steelhead fry catches at Skagit Basin sampling sites using e1ectrofisher, 1976 brood . . . . 457 "'""' Table No. 8.88 8.89 8.90 8.91 8.92 8.93 8.94 8.95 8.96 8.97 8.98 8.99 8.100 xxvi Rainbow-steelhead fry catches at Skagit Basin sampling sites using electrofisher, 1977 brood Mean lengths, weights, and condition factors of rainbow-steelhead fry captured by electro- shocking at the County Line Station in 1977 • Mean lengths, weights, and condition factors of rainbow-steelhead fry captured by electro- shocking at the Talc Mine Station in 1977 • • Mean lengths, weights, and condition factors of rainbow-steelhead fry captured by electro- shocking at the Marblemount Station in 1977 . Mean lengths, weights, and condition factors of rainbow-steelhead fry captured by electro- shocking at the Rockport Station in 1977 Mean lengths, weights, and condition factors of rainbow-steelhead fry captured by electro- shocking at Cascade River in 1977 . • . . • • Mean lengths, weights, and condition factors of rainbow-steelhead fry captured by electro- shocking at Sauk River in 1977 . . . • . • . Mean lengths, weights, and condition factors of rainbow-steelhead fry captured by electro- shocking at Goodell Creek in 1977 . . . . . Mean lengths, weights, and condition factors of rainbow-steelhead fry captured by electro- shocking at Bacon Creek in 1977 . . . . . . . Mean lengths, ~eights, and condition factors of rainbow-steelhead fry captured by electro- shocking at Diobsud Creek-in 1977 ••. Rainbow-steelhead fry stomach contents, 1976 brood, upper three Skagit sites ..•. Rainbow-steelhead fry stomach contents, 1976 brood, lower two Skagit sites . . • • • Rainbow-steelhead fry stomach contents, 1976 brood, Cascade River • . . • . . • • • ~- Page 459 464 ~I 465 466 467 468 470 472 473 474 - 482 484 486 Table No. 8.101 8.102 8.103 8.104 8.105 8.106 I """ 8.107 8.109 8.110 8.111 8.112 8.113 8.114 xxvii Rainbow-steelhead fry stomach contents, 1976 brood, Sauk River 0 0 0 . . 0 . . . Rainbow-steelhead fry stomach contents, summary of 1976 brood 0 . 0 . . . . Fry stranding observations, 1976 Fry stranding observations, 1977 Classification of flow reductions for Skagit River at Newhalem (USGS) between January 1 and April 21, 1977, according to minimum elevation attained and number of feet dropped Observed and corrected length, weight, and condition factors of stranded and unstranded chinook fry from surveys conducted in 1976 and 1977 . . . • . . . •.•..••. The lengths, weights, and condition factors of 49 rainbow-steelhead trout fry measured fresh, rrstranded" ·for two hours, and then soaked in water for one hour . . . . . . . . . • . • • 0 . Ca.1culated ramping rate and time at maximum flow prior to flow reduction for flow reductions to approximately 82 and 83 ft at the Newhalem gaging station for surveys conducted at County . . 0 . 0 0 Line and Marblemount bars in 1973, 1976, 1977 ..•.. Summary of chinook fry stranding trials con- ducted at Big Beef Creek Research Station during 1978 ........ . Raw data from Skagit River marking study, Marblemount sampling station . • . . . . • Raw data from Skagit River marking studies, County Line sampling station . . . . Relevant parameters for each week of spawning Data used in the regressions of ln(r /C ) versus t for the various stations and markstoftthe study Mean residence times and rates of disappearance estimated using the steady-state model . . . . . Page 488 . 490 498 504 510 511 513 514 518 523 525 531 535 537 Table No. 8.115 8.116 8.117 8.118 8.119 9.1 9.2 9.4 9.5 9.6 9.7 9.8 11.1 xx:viii Petersen estimate of initial population size for the tagging experiments at Marblemount and County Line . . . . . . . . • . . . Results of simulation of the tagging experiment at Marblemount station Results of the simulation of the tagging experiment at County Line station . . Summary of fish population surveys in 100-ft sec- tions of Skagit River tributaries upstream of Copper Creek Dam site conducted during August, 1977 I I I I I I I I i I I I I 1 I I I Summary of physical data for Skagit River tributaries upstream of Copper Creek Dam site I I I I I I I I I I I I I I I I I I. • 9.0 OTHER FISHES Catch of non-salmon fishes at three sites on the Skagit River during 1977-1978 • . • • • Length and weight of mountain whitefish captured at three locations in the mainstem Skagit River during quarterly sampling in 1977 and 1978 . . . . . Length and weight data for fishes captured at three locations in the mainstem Skagit River during quarterly sampling in 1977 and 1978 Sexual maturity of"Skagit River whitefish, 1977-1978 • • • . • . . • • • • • • Newhalem whitefish stomach contents Marblemount whitefish stomach contents • . Rockport whitefish stomach contents Dolly Varden stomach contents 11.0 IMPACT Mean annual (1977) periphyton standing crop, as indicated by amount of chlorophyll ~, in . . . Page 539 540 541 546 547 553 555 556 557 558 559 560 562 the Skagit River • • • • • • • • . • . • • . • . . • • . 5 80 -- '"'~ ! ! Table No. 11.2 11.3 xxix Mean annual (1977) benthic insect standing crop in the Skagit River between Gorge Powerhouse and the Sauk River . • • • • • • • • • • • • Predicted average monthly discharge from proposed Copper Creek Reservoir in acre-ft based on USGS records of Skagit River discharge at Alma Creek, 1951-1976 . . • • • • • • . 11.4 Estimated coho smelt production potential above the proposed Copper Creek Dam site 11.5 11.6 at R11 84.0 • 41 • I I a I • I • 1 I Estimated chinook smelt production potential below the proposed Copper Creek Dam site at R}1 84 Ill 0 I I I I • I I I I II I • I Estimated chinook smelt production potential above the proposed Copper Creek Dam site at RM 84.0 and its comparison with the estimated production potential of the total accessible Skagit drainage .....•.• , ..••.• Page 582 584 587 588 589 XXX LIST OF FIGURES Figure No. Page 1.1 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 1.0 INTRODUCTION Skagit Basin study area 2.0 PHYSICAL ENVIRONMENT Long-term natural streamflow patterns for Sauk and Cascade rivers (USGS 1929-1976) and for Skagit River at Newhalem (SCL 1910-1975) Long-term natural and regulated streamflow patterns for Skagit River at Newhalem (1974-1975) (SCL and USGS) .• , .. Hydrographs of mean daily discharges at gaging sites on the Sauk, Cascade, and Skagit rivers for 1974 (USGS) . Hydrographs of mean daily discharges at gaging sites on the Sauk, Cascade, and Skagit rivers for 1975 (USGS) . Hydro graphs of mean daily discharges at gaging sites on the Sauk, Cascade, and Skagit rivers for 1976 (USGS) Hydrographs of mean daily discharges at gaging sites on the Sauk, Cascade, and Skagit rivers for 1977 (USGS) . Hydrographs of mean daily discharges at gaging sites on the Sauk, Cascade, and Skagit rivers from January through June 1978 (USGS) . . . . . . . . . . Daily range of flow fluctuations in ft and cfs for Skagit River at Newhalem (USGS) for July through December, 1974 Daily range of flow fluctuations in ft ana cfs for Skagit River at Newhalem (USGS) for 1975 . . . . . . . . . . . . . Daily range of flow fluctuations in ft and cfs for Skagit River at Newhalem (USGS) for 1976 . . . . . . . . . . . . . . . . . . . . . . . 5 8 9 . . . . . . 10 . . . 11 . . . 12 . . . . . . 13 . . . . . 14 . . . . . . 15 . . . . 16 . . . . . . 17 ~) ~· ~-· -' ~1!1!!1<'(> _-;o:- If""' ,....-, xxxi Figure No. Page 2.11 Daily range of flow fluctuations in ft and cfs for Skagit River at Newhalem (USGS) for 1977 . . . . . 0 . . . . . . . . . . . 18 - 2.12 Daily range of flow fluctuations in ft and cfs for Skagit River at Newhalem (USGS) from "'"" January through June 1978 . . . 19 2.13 Daily range of flow fluctuations in ft and cfs for Skagit River at Marblemount (USGS) for June through December, 1976 . . . . . . . 21 2.14 Daily range of flow fluctuations in ft and cfs for Skagit River at Marblemount (USGS) for 1977 . . . . . . . . . 22 '""1' 2.15 Daily range of flow fluctuations in ft and cfs for Sauk River (USGS) for July through November, 1974 . . . . . . . . . . . . . . . 23 2.16 Daily range of flow fluctuations in ft and cfs for Sauk River (USGS) for 1975 . . . . . . . . 24 2.17 Daily qmge of flow fluctuations in ft and cfs for Sauk River (USGS) for 1976 . . . . . . . . . 25 2.18 Daily range of flow fluctuations in ft and cfs for Sauk River (USGS) for 1977 . . . . . . . . . 26 2.19 Daily range of flow fluctuations in ft and cfs for Cascade River (USGS) for July through December, 1974 . . . . . . . . . . . . 27 :""'l' 2.20 Daily of flow fluctuations in ft and range cfs for Cascade River (USGS) for January through November, 1975 . . . . . . . . . . . . 28 .~ 2.21 Daily range of flow fluctuations in ft and cfs for Cascade River (USGS) for August ~~ through December, 1976 . . . . . . . . . . 29 2.22 Daily range of flow fluctuations in ft and cfs for Cascade River (USGS) for 1977 . . . . . . . 30 ~ 2 .. 23 Natural and regulated streamflows in cfs for Skagit River at Newhalem for 1974 i fl~ (SCL and USGS) . . 31 . . . . . . . . . . Figure No. 2.24 2.25 xxxii Natural and regulated streamflows in cfs for Skagit River at Newhalem for 1975 (SCL and USGS) . . . . . . . . . . • Natural and regulated streamflows in cfs for Skagit River at Newhalem for 1976 ( SCL and USGS) . . . . . . . . . . . 2.26 Natural and regulated streamflows in cfs for Skagit River at Newhalem for 1977 2.27 2.28 2.29 2.30 2.31 2.32 2.33 2.34 2.35 ( SCL and USGS) . . . . • . . • • . . . • . . . • • • . . Long-term mean water temperatures for Skagit River above Alma Creek (USGS, 23-year mean), Sauk River (SCL and USGS, 7-year mean) and Cascade River (USGS, 18-year mean) . . . • • . . . . . . Semi-monthly water temperature (°F) for Skagit (above Alma Creek), Sauk, and Cascade rivers during 1976 (SCL) . . . . Semi-monthly water temperature (°F) for Skagit (above Alma Creek), Sauk, and Cascade rivers during 19 77 (SCL) . • . • . . • . . . . . . . Semi-monthly water temperature (°F) for Skagit (above Alma Creek), Sauk, and Cascade rivers during 1978 (USGS and SCL) • . . • . , • . Semi-monthly ~ean water temperatures for sites on the Skagit River at Newhalem, Marblemount, and Rockport Semi-monthly mean water temperature (°F) for Skagit River above Alma Creek from September 1974 to September 1978 (USGS) ...•. Semi-monthly mean water temperature (°F) for Sauk River _from January 1975 to May 1978 (SCL) Semi-monthly mean water temperature (°F) for Cascade River from May 1976 to May 1978 (SCL) Mean monthly temperature change from Ross tailrace to Diablo intake . . . • • • • • • • 2.36 Mean monthly temperature at Gorge intake and ap- proximated mean monthly temperature at Copper Creek in take . . . . . . • • . • . • . . . . . . Page 32 ~ "''" 33 -· 34 ~., 38 39 40 41 ~\ 42 44 45 46 49 50 -·· !""'' I Figure No. 2.37 3.1 3.2 3 ·~ ·~ 3.4 3.5 3.6 3.7 3.8 3.9 3.10 xxxiii Skagit River profile illustrating the change in elevation from Gorge Power- house to the Baker River . . • • • . • 3.0 PERIPHYTON AND BENTHIC INSECTS Map of the Skagit study area showing benthos and periphyton sampling stations . . • . • • Stream profiles at the Skagit Lower station showing maximum and minimum water levels dur- ing the six-week colonization periods Chlorophyll ~ content of periphyton samples collected at the Skagit Lower, Sauk Lower, and Cascade stations in October 1976 . . . . . • . Chlorophyll ~ content of periphyton samples collected at the Skagit Lower, Sauk Lower, and Cascade stations in November 1976 . . • . • . Chlorophyll ~ content of periphyton samples col- lected at the Skagit Lower, Sauk Lower, and Cas- cade stations in January 1977 . . • . . . • . . Chlorophyll ~ content of periphyton samples col- lected at the Skagit Lower Station in February 19 7 7 • • • • • • • • • • • • • • • • .. • • • • Periphyton standing crop, as indicated by chlo- rophyll~ content, at the Skagit Lower and Sauk Lower stations . . • • . . . • . . . . . • . . . Periphyton standing crop as indicated bi chlo- rophyll ~ content of samples collected at the Skagit Upper and Cascade stations ....••••... Stream profiles at the Skagit Lower Station showing maximum and minimum water levels during the two weeks prior to benthic insect sampling in May and July 1976 . • . . . . . . . . . . . . Stream profiles at the Skagit Lower Station show- ing maximum and minimum water levels during the two weeks prior to benthic insect sampling in September and November 1976 . . . . . . . . • • Page 52 55 75 76 77 78 79 81 82 87 88 Figure No. 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 3.20 3.21 3.22 4.1 5.1 xxxiv Density and biomass of benthic insects at the Skagit Lower Station in May 1976 . Density and biomass of benthic insects at the Skagit Lower Station in July 1976 Density and biomass of benthic insects at the Skagit Lower Station in September 1976 Density and biomass of benthic insects at the Skagit Lower Station in November 1976 Benthic insect standing crop at the Skagit Lower and Sauk Lower sampling stations . . Benthic insect standing crop at the Skagit Upper, Sauk Upper, and Cascade sampling stations . . . . . . ....... . Seasonal variation in benthic macroinverte- brate density in the Skagit, Sauk, and two other rivers in western North America Percent composition of benthic insects col- lected at the Skagit Upper Station .• Percent compos~tion of benthic insects col- lected at the Skagit Lower Station . . Percent composition of benthic insects col- lected at the Sauk Lower Station Percent composition of benthic insects col- lected at the Cascade River Station • . . • Percent composition of benthic insects col- lected at the Sauk Upper Station ... 4.0 PLANKTON DRIFT Plankton drift sampling stations, 1977 5. 0 SALMON AND STEELHEAD Scattergram of mean September discharge (cfs) at Skagit River near Alma Creek (USGS) versus relative Skagit chinook run size 4 years later Page 89 90 91 92 94 95 p!WP"' 98 102 103 104 105 106 117 """'- 153 -' - Figure No. 5.2 5.3 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 XXXV Scattergram of daily maximum discharge (cfs) at Skagit River near Alma Creek (USGS) during September through February versus relative Skagit chinook run size 4 years later •••• Scattergram of number of days when flows dropped below 82 ft at Skagit River at Newhalem (USGS) versus relative Skagit chinook run size 4 years later e a a I I I I I I I I I I I I I .. I I 6.0 SPAWNING Skagit River sample transects (1-20, lighter numbers) and reference reaches (1-4, bold num- bers) between the Gorge Powerhouse (Newhalem) and the Baker River (Concrete) • • •••. Skagit River hydrographs of mean daily discharge at two gaging sites for the period from July to December 1975 . . . . . . . . • . .... Skagit River hydrographs of mean daily discharge at three gaging sites for the period from July to December 1976 .......•.......... Frequency distribution of chinook salmon spawning depths in the Skagit River measured at 436 redds • Frequency distribution of chinook salmon spawning velocities in the Skagit River measured at 436 redd s . . . . . . . . . . . . . . . . . . . . Frequency distribution of pink salmon spawning depths in the Skagit River measured at 347 redds Frequency distribution of pink salmon spawning velocities in the Skagit River measured at 347 redds . . . . . . . . . . . . . Frequency distribution of chum salmon spawning depths in the Skagit River measured at 227 redds Frequency distribution of chum salmon spawning velocities in the Skagit River measured at 227 redds . . . . . . . . . . . . . . . · · · · · Page 154 156 166 167 168 173 174 175 176 178 179 Figure No. 6.10 xxxvi Frequency distribution of steelhead trout spawning depths in the Skagit River measured at 164 redds . . . . . . . . . . . . . . . . . . . . . . 6.11 6.12 6.13 6.14 6.15 6.16 6.17 6.18 6.19 6.20 6.21 Frequency distribution of steelhead trout spawning velocities in the Skagit River mea- sured at 164 redds • • . . • . . . • • . Numbers of chinook salmon observed in the reference reaches over the 1975 spawning season . . . . . . . . . . . . . . . . . . . Numbers of chinook salmon observed in the reference reaches ·aver the 1976 spawning season . . . . . . . . . . . . . . . . . Numbers of chinook salmon redds observed per day in 1976 and numbers of new redds con- structed per day in the reference reaches over the 1976 and 1977 spawning season . . Pink salmon counts in 1975 at three reference reaches on the Skagit River . . . . . . Pink salmon counts in 1977 at three reference reaches on the Skagit River . . . . . . . Numbers of chum salmon observed in the Marble- mount side channel over the 1976 spawning season . . . . . . . . . . . . . . . . Locations of chinook salmon redds at Newhalen Reference Reach during 1975, 1976, and 1977 spawning seasons . . . . . . . . . . . . . . . Locations of chinook salmon redds at Talc Mine Reference Reach during 1975, 1976, and 1977 spawning seasons . . . . . . . . Locations of chinook salmon redds at Marble- mount Reference Reach during 1975, 1976, and 1977 spawning seasons . . . . . . . . . . . . Locations of chinook salmon redds and pink ·salmon mass spawned area at Newhalem Reference Reach during 1977 spawning seasons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page ~~ 180 181 183 ~ 185 - 186 ~ 189 190 - ~ 191 ~ 198 199 ~ 200 201 - Figure No. 6.22 6.23 ""!"' . I 6.24 6.25 6.26 6.27 6.28 6,29 6.30 6.31 xxxvii Locations of pink salmon mass spawned areas in Newhalern Reference Reach dur- ing 1975 and 1977 spawning seasons . . Locations of chinook salmon redds in Marblemount Reference Reach (3) construc- ted before and after 20 September 1976 . Relationship between estimated spawnable area, polynomial regression on the es- timated spawnable area, and total wetted area for chinook salmon at Reference Reaches 1-2 Relationship between estimated spawnable area, polynomial regression on the esti- mated spawnable area, and total wetted area for chinook salmon at Reference Reaches 3-4 . . • . . • . • . • . . . • Relationship between estimated spawnable area, polynomial regression on the esti- mated spawnable area, and total wetted area for pink salmon at Reference Reaches 1-2 Relationship between estimated spawnable area, polynomial regression on the estimated spawn- able area, and total wetted area for pink salmon at Reference Reaches 3-4 . . Relationship between estimated spawnable area, polynomial regression on the esti- mated spawnable area, and total wetted area for churn salmon at Reference Reaches 1-2 Relationship between estimated spawnable area, polynomial regression on the estimated spawn- able area, and total wetted area for churn salmon at Reference Reaches 3-4 . . , . Relationship between estimated spawnable area, polynomial regression on the estimated spawn- able area, and total wetted area for steelhead trout at Reference Reaches 1-2 Relationship between estimated spawnable area, polynomial regression on the estimated spawn- able area, and total wetted area for steelhead trout at Reference Reaches 3-4 . . . ..•. Page 205 210 212 213 214 215 216 217 218 219 Figure No. 6.32 6.33 6.34 7·.1 7.2 7.3 7.4 7.5 7.6 7.7 xxxviii Plan views of Reference Reach 1 (Newhalem) showing changes and movement of the esti- mated spawnable area for pink salmon (shaded) at three discharges . . . • • . . Plan views of Reference Reach 2 (Talc Mine) showing changes and movement of the esti- mated spawnable area for chinook salmon (shaded) at three discharges • . . . . . . • . . . . . Plan views of Reference Reach 3 (Marble- mount) showing changes and movement of the estimated spawnable area for chum salmon (shaded) at three discharges 7.0 INCUBATION AND EMERGENCE Observed and forecast water temperatures for Skagit River • . . . . . . . .• Study stations on the Skagit, Sauk, and Cascade rivers . . . . . ..... Cumulative temperature units (Fahrenheit) ex- perienced by Skagit River chinook eggs in the Station 1 incubation box, commencing Septem- ber 16, 1974 . . . .. • • .• , •... Cumulative temperature units (Fahrenheit) ex- perienced by Skagit River chinook eggs in the Station 1 incubation boxes, commencing Septem- ber 8 and 16, and October 6 and 12, 1976 Daily temperatures in degrees Fahrenheit for the Skagit (near Newhalem), Sauk, and Cascade rivers and University of Washington Hatchery from August 1976 to April 1977 • . . • . • . . Cumulative temperature units (Fahrenheit) ex- perienced by chinook eggs from female #3-76 at selected sites, commencing October 6, 1976 Cumulative Fahrenheit temperature units ex- perienced by chinook eggs incubated in the Skagit and Cascade rivers, commencing Septem- ber 6, 1977 ................ . - Page 220 221 222 244 248 254 - 256 261 -· 264 265 Figure No. 7.8 7.9 "'i" 7.10 7.11 .... 7.12 ,"'!"' 7.13 7.14 "'F "'""' 8.1 8.2 8.3 - xxxix Cumulative temperature units (Fahrenheit) experienced by Skagit River chinook eggs at the University of Washington Hatchery, commencing October 6 and 12, 1976 Cumulative Fahrenheit temperature units experienced by pink eggs incubated in the Skagit, Sauk, and Cascade rivers, com- rnencing October 5, 1977 . . . . . . . . Cumulative Fahrenheit temperature units ex- perienced by chum eggs incubated in the Skagit, Sauk, and Cascade rivers, commenc- ing December 7, 1977 . . . . . . . . . . Egg mortalities between fertilization and mean hatching for Skagit River churn eggs incubated under three constant temperature regimes at the University of Washington Hatchery, 1977-1978 . . . . . . . . . . . Estimated emergence curve of 1974 chinook salmon fry assuming 1930 temperature units to emergence and peak spawning to be Sep- tember 9th . . . . . . . . . . . . Timing and relative magnitude of chinook spawning and expected emergence for 1976- 1977 based on the accumulation of 1930 temperature units . . . . . . . . . . Number of chinook fry emerged per day when incubated in gravel substrate at University of Washington Hatchery during 1976-1977 8.0 FRY REARING . . . . . Electrofishing stations for stomach and con- dition samples, Skagit Basin, Washington Chinook fry availability at Skagit River sampling sites from standardized electro- fishing effort, 1976, 1977, and 1978 Mean dry weight condition factors of Skagit, Sauk, and Cascade chinook fry taken by electrofishing, 1974 brood Page 267 . . . . . . 275 . . . . . 278 . . . . . 280 . . . . . 292 . . . . . 294 . . . . . . 295 309 315 336 Figure No. 8.4 8.5 8.6 8.7 8.8 8.9 8.10 8.11 8.12 8.13 8.14 8.15 8.16 8.17 xxxx Mean lengths of chinook fry from the four Skagit sites, 1975 brood Mean lengths of chinook fry from the four Skagit sites, 1976 brood . . . . Mean lengths of chinook fry for Skagit . sites, combined, 1975 brood compared with 1976 brood . . . . . . . . . . . . . Mean lengths of chinook fry from Skagit creeks, 1975 brood . . . . . . . . . . . Mean lengths of chinook fry from Skagit creeks, 1976 brood . . . . . . . . . . . . . Mean lengths of chinook fry, Skagit sites, combined, and Skagit creeks, combined, 1975 brood . . . . . . . . . . . . . . . Mean lengths of chinook fry, Skagit sites, combined, and Skagit creeks, combined, 1976 brood . . . . . . . . . Mean lengths of chinook fry from the Cascade River, 1975 and 1976 broods . Mean lengths of chinook fry from the Sauk River, 1975 and 1976 broods . . . Mean lengths of chinook fry from the Skagit sites, combined, and from the Cascade and Sauk rivers, 1975 brood . . . . .. . . Mean lengths of chinook fry from the Skagit sites, combined, and from the Cascade and Sauk rivers, 1976 brood . . . . Mean weights of chinook fry from the four Skagit sites, 1975 brood . . . . Mean weights of chinook fry from the four Skagit sites, 1976 brood . . . . Mean weights of chinook fry for Skagit sites, combined, 1975 brood compared with 1976 brood . . . . . . 0 . . . . . . . . . Page 338 - . . . . . . . 338 ~· . . . . . 339 . . . . . . . 340 ~ . . . . . 340 - . . . . . . . 341 . . . . . 341 . . . . . . . 342 . . . . . . . 342 . . . . . . . 343 --. . . . . . . 343 . . . . . . . 344 -~ . . . . . . . 344 . . . . . 0 . 345 - i"""' xxxxi Figure No. Page 8.18 Mean weights of chinook fry from Skagit creeks, 1975 brood . . . . . . . 0 . 0 . . . . . 346 8o19 Mean weights of chinook fry from Skagit creeks, 1976 brood 0 . 0 . 0 . . . 0 0 0 0 0 . 0 . 346 8.20 Mean weights of chinook fry, Skagit sites, combined, and Skagit creeks, combined, 1975 brood 0 0 . . . 0 0 . 0 0 0 0 0 0 . . 0 0 347 8o21 Mean weights of chinook fry, Skagit sites, combined, and Skagit creeks, combined, 1976 brood 0 0 . 0 0 . . 0 0 0 0 . . 0 . . . 0 347 8o22 Mean weights of chinook fry from the Cascade River, 1975 and 1976 broods . . . 0 0 0 0 0 0 348 ' T 8.23 Mean weights of chinook fry from the Sauk River, 1975 and 1976 broods . 0 0 0 0 0 0 0 . . 348 ~ 8o24 of chinook fry from the I Mean weights Skagit sites, combined, and from the Cascade and Sauk rivers, 1975 brood 0 0 0 0 0 0 . 0 0 0 0 . 0 349 8o25 Mean weights of chinook fry from the Skagit sites, combined, and from the Cascade and Sauk rivers, 1976 brood 0 . . . 0 . 0 0 0 . 0 0 0 0 . . 349 8.26 Mean condition factors from the four Skagit sites, 1975 brood 0 . 0 0 . 0 0 0 . 0 0 0 0 0 0 0 . 350 8o27 Mean condition factors from the four Skagit sites, 1976 brood 0 0 0 0 0 0 0 0 0 0 0 0 . .. 350 8.28 Mean condition factors of chinook fry for the Skagit sites, combined, 1975 brood compared with 1976 brood . . 0 0 . 0 0 0 0 0 0 0 . . 0 0 351 8.29 Mean condition factors of chinook fry from ."f" Skagit creeks, 1975 brood 0 . 0 0 0 0 0 0 0 0 0 0 . . 0 352 I I 8o30 Mean condition factors of chinook fry from Skagit creeks, 1976 brood. . . . 0 0 0 . . . 0 0 . 352 8o31 Mean condition factors of chinook fry, Skagit sites, combined, and Skagit creeks, combined, ·""" 1975 brood 0 0 0 . 0 0 0 0 0 0 0 . . . 0 0 . 0 0 0 . 0 353 Figure No. 8.32 8.33 8.34 8.35 8.36 8.37 8.38 8.39 8.40 8.41 8.42 8.43 xxxxii Mean condition factors of chinook fry, Skagit sites, combined, and Skagit creeks, combined, 1976 brood •.•.• Mean condition factors of chinook fry from the Cascade River, 1975 and 1976 broods . . . . . . . . . . . . . . . . Mean condition factors of chinook fry from the Sauk River, 1975 and 1976 broods Mean condition factors of chinook fry from the Skagit sites, combined, and from the Cascade and Sauk rivers, 1975 brood Mean condition factors of chinook fry from the Skagit sites, combined, and from the Cascade and Sauk rivers, 1976 brood •••.. Sizes of length, weight, and condition factor samples of chinook fry from the 1975 brood from the upper three Skagit River stations • • Sizes of length, weight, and condition factor samples of chinook fry from the 1975 brood from the Rockport station on the Skagit River, the Cascade River, and the Sauk River •••. Sizes of length, weight, and condition factor samples of chinook fry from the 1975 brood from two Skagit creeks .•.•..•.. Sizes of length, weight, and condition factor samples of chinook fry from the 1976 brood from the upper three Skagit River stations •• Sizes of length, weight, and condition factor samples of chinook fry from the 1976 brood from the Rockport station on the Skagit River, the Cascade River, and the Sauk River .••. Sizes of length, weight, and condition factor samples of chinook fry from the 1976 brood from three Skagit creeks . • • • • . . . • • Pink salmon availability at Skagit River sampling sites from standardized electrofishing effort, 19 7 8 . . . . . . . . . . . . . . . . . . . . . . . Page 353 354 ~' 354 355 355 356 356 357 - 357 358 358 - 382 Figure No. 8.44 8.45 8.46 8.47 8.48 8.49 8.50 8.51 8.52 8.53 8.54 8.55 """ 8.56 xxxxiii Chum salmon availability at Skagit River sampling sites from standardized electrofish- ing effort, 1977 and 1978 •••••• Mean lengths of chum fry taken by electrofishing from five Skagit River stations, 1976 brood •••. Mean weights of chum fry taken by electro- fishing from five Skagit River stations, 1976 brood • • • • • • • Mean condition factors of chum fry taken by electrofishing from five Skagit River stations . • . • • . • • . . • . . Mean lengths of Skagit, Cascade, and Sauk coho fry taken by electrofishing, 1975-76 brood . . . . . . . . . . . . . . . Mean wet weights of Skagit, Cascade, and Sauk coho fry taken by electrofishing, 1975-76 brood • • • . . . • . • • . . . Mean condition factors of Skagit, Cascade, and Sauk coho fry taken by electrofishing, 1975-76 brood • • • • . • Mean lengths of coho fry taken by electro- fishing from four Skagit River stations, 1976-1977 brood • • • • • Mean weights of coho fry taken by electro- fishing from four Skagit River stations, 1976-77 brood . • . • • • • • Mean condition factors of coho fry taken by electrofishing from four Skagit River stations, 1976-77 brood ••.• Mean lengths of Skagit, Cascade, and Sauk coho fry taken by electrofishing, 1976-77 brood . . . . . . . . . . Mean weights of Skagit, Cascade, and Sauk coho fry taken by electrofishing, 1976-77 brood . . . . . . . . . . . . . . . . . . Mean condition factors of Skagit, Cascade, and Sauk coho fry taken by electrofishing, 1976-77 brood . . . . . . . . . . . . . . . . . . . . Page 395 405 406 407 424 425 426 437 438 439 . . . . . 440 . . . . . 441 . . . . . 442 Figure No. 8.57 8.58 8.59 8.60 8.61 8.62 8.63 8.64 8.65 8.66 8.67 8.68 xxxxiv Mean lengths of coho fry taken by elec- trofishing from three Skagit creeks, 1976-77 brood ..•.• Mean weights of coho fry taken by elec- trofishing from three Skagit creeks, 1976-77 brood ..•.•.•. Mean condition factors of coho fry taken by electrofishing from three Skagit creeks, 1976-77 brood • • • • • . • . . . ••• Mean lengths of Skagit, Cascade, and Sauk rainbow-steelhead fry taken by electrofish- ing, 1976 brood ••.•••.. Mean weights of Skagit, Cascade, and Sauk rainbow-steelhead fry taken by electro- fishing, 1976 brood •..•••••.. Mean condition factors of Skagit, Cascade, and Sauk rainbow-steelhead fry taken by elec- trofishing, 1976 brood • . . • . • • • . • . . Mean lengths of rainbow-steelhead fry taken by electrofishing from four Skagit River stations, 1977 brood . . . . . . . . . . . . . . . . . . Mean weights of rainbow-steelhead fry taken by electrofishing from four Skagit River stations, 1977 brood . . . . . . . . . . . . . . . . . Mean condition factors of rainbow-steel head fry taken by electrofishing from four Skagit River stations, 1977 brood . . . . . . . . . . . Mean lengths of Skagit, Cascade, and Sauk rain- bow-steelhead fry taken by electrofishing, 1977 brood . . . . . . . . . . . . . . . Mean weights of Skagit, Cascade, and Sauk rain- bow-steelhead fry taken by electrofishing, 1977 brood . . . . . . . . . . . . . . . . . . Mean condition factors of Skagit, Cascade, and Sauk rainbow-steelhead fry taken by electro~ fishing, 1977 brood . . . . . • , , . • • . , Page 443 444 ~I 445 460 461 462 -. . . . . 475 . . . . . 476 - . . . . . 477 - . . . . 478 -, . 479 480 ·.~. - - - Figure No. 8.69 8.70 8. 71 8. 72 8.73 XX XXV Experimental stranding channel at Big Beef Creek Research Station Hourly gage height data for Skagit River at Newhalem (USGS), January- May, 1976 . . . • . · • • . • . . . Hourly gage height data for Skagit River at Newhalem (USGS), January- April 14, 1977 •..•.•.• I I • • I I I I I Relationship between stranding mortality and ramping rate for flow reductions to 82 feet with 95 percent confidence inter- vals shown as dotted lines . . . . . . . • Relationship between stranding mortality and ramping rate for flow reductions to 83 feet with 95 percent confidence intervals shown as dotted lines • . . . . . . . 8.74 Locations of stranded fish in experimental 8.75 8.76 8. 77 8.78 8.79 8.80 channel Study area with the Marblemount and County Line stations •.•... Timing and relative magnitude of chinook spawning and expected emergence for 1977- 1978 based on the accumulation of 1,930 temperature units Distribution of emergence (yolk absorption) for various in situ experiments The assumed time distribution of egg depo- sition within each week ••.• Estimated timing of chinook emergence, 1977-1978 ...••.••..• Length-frequency histograms of rainbow trout in upper Skagit tributaries ..•.. Page 495 499 505 515 516 519 521 528 529 530 533 549 - - 1.0 INTRODUCTION 1.1 History of the Skagit Project The City of Seattle began development of the hydroelectric potential of the Skagit River in the early 1900's. The Lighting Department of the City undertook a staged development of three dams: Gorge, Diablo, and Ross, which were begun ip 1919, 1927, and 1937, respectively. Plans for development included the multistage construction of Ross Dam which was completed to an elevation of 1,365 ft in 1940, to 1,550 ft in 1946, and to its present elevation of 1,615 ft in 1949. The presence and operation of these dams has altered the general streamflow and temperature patterns in the Skagit River downstream of the Skagit Project. Operational constraints in addition to those specified by Federal license were implemented in 1972. By informal agreement between the Washington Department of Fisheries (WDF) and Seattle City Light (SCL), minimum flows were established during the period of peak juvenile salmon abundance in an effort to reduce the impact of dam operation on the downstream fisheries. These events and others affecting the downstream flow and temperature are listed in Table 1.1. Present plans include raising the full pool elevation of Ross Reservoir from the present 1,602.5 ft to 1,725 ft and construction of Copper Creek Dam on the Skagit River 10.2 mi downstream of Gorge Powerhouse. Physical data for the present and proposed reservoirs are presented in Table 1.2. 1.2 General Study Objectives The aim of these studies was to establish ecological baseline data for the aquatic environment of the Skagit River between Newhalem and Concrete. Studies were designed to contribute information relevant to three SCL projects: High Ross Dam, Copper Creek Dam, and relicensing of the Skagit Project. The results provide a basis to assess the present and predicted reservoir-related effects of the Skagit Project on the downstream fishery resources of the Skagit River. 1.3 Study Area The Skagit River, with headwaters in Canada, flows south across the international boundary through a reservoir complex made up of Ross, Diablo, and Gorge reservoirs, then continues generally west where it enters saltwater near Mount Vernon, Washington. The Skagit is one of the largest streams flowing into Puget Sound. There are three major tributaries to the Skagit River: the Cascade River, which flows in at the town of Marblemount at river mile (RM) 78.1; the Sauk River, which enters near Rockport at RM 67.0; and the Baker River, which flows in at Concrete at RM 56.5. Numerous smaller tributaries enter the Skagit River also. These studies were conducted primarily in the Skagit River between Newhalem and the confluence of the Sauk River, and in the lower Cascade 2 Table 1.1 Events in the development of the Skagit Project affecting downstream flow and temperature patterns in the Skagit River. Adapted from Seattle City Light information. 1919 1924 1927 1929 1936 1937 1940 1946 1949 1950 1951 1953 1959 1960 1972 Construction began on Gorge Dam Gorge Dam began generating (1st & 2nd generator) Construction began on Diablo Dam Gorge Dam generation expanded (3rd generator) Diablo Dam began generating Construction began on Ross Dam Ross completed to 1365 ft Ross completed to 1550 ft Ross completed to 1615 ft (full pool elevation = 1600 ft) Gorge crib dam replaced with concrete Gorge Dam generation expanded (4th generator) Spillway gates installed at Ross Dam Ross full pool elevation raised to 1602.5 ft Gorge Dam replaced by present dam Informal agreement with WDF on minimum flows during peak fry abundance ~1 ~· - - - ~I - - ~ - - - - - 3 Table 1.2. Physical data for the present and proposed reservoirs on SkaRit River. Data taken from SCL information. Maximum Length at Total Capacity Surface Area Elevation Maximum at Maximum at Haximum (ft above Elevation Elevation Elevation Reservoir mean sea level) (mi) (acre-ft) (acres) Ross 1,602.5 23.9 1,435,000 11' 680 High Ross 1, 725 29.5 3,450,000 20,000 Diablo 1 '205 4.2 90,000 910 Gorge 875 4.4 9,760 241.2 Copper Creek 495 10.2 123,000 2,180 (495 ft) Copper Creek 480 9. 7 92,500 1,834 (480 ft) 4 and Sauk rivers. This area of the Skagit River immediately downstream of Newhalem is most affected by operation of present SCL dams and a portio~ of this area would be inundated by the proposed Copper Creek Dam. The Cascade and Sauk rivers represented natural (unregulated) systems for comparison with the Skagit River. In addition, some sampling was conducted in the Skagit River between the confluences of the Sauk and Baker rivers, in Gorge and Diablo reservoirs, and in selected small tributaries between Newhalem and Marblemount including Newhalem, Goodell, Thornton, Sky, Damnation, Alma, Copper, Bacon, and Diobsud creeks. A map showing the general Skagit Basin study area is presented as Fig. 1.1. Also shown are the locations of U.S. Geological Survey (USGS) gaging stations, fish hatchery and rearing facilities operated by WDF and WDG, and river miles (RM). 1.4 Acknowledgments This report presents the results of studies conducted by the Fisheries Research Institute (FRI), University of Washington, for the City of Seattle, Department of Lighting. The FRI personnel responsible for the studies reported herein are as follows: Dr. R. L. Burgner, Principal Investigator Dr. Q. J. Stober, Co-Principal Investigator Mr. J P. Graybill, Project Leader Mr. K. H. Wyman, Field Project Biologist, fry stranding and fish rearing Mr. P. E. Huffman, Field Biologist and Research Assistant, fish rearing and zooplankton studies Mr. T. W. Fagnan, Research Aide and Field Biologist, fish rearing and angler survey Dr. D. M. Eggers, Research Assistant Professor, chinook fry residence time Mr. J. C. Gislason, Pre-Doctoral Research Associate, periphyton and benthic insects Nr. R. G. Gibbons, Research Assistant, incubation and emergence - 1974-75 studies Hr. K. w. Kurka, Research Assistant, spawning studies -1975-76 Mr. A. P. Stayman, Research Assistant, experimental fry stranding studies Other FRI personnel who provided field and laboratory assistance are Ms. L. Jensen and Mr. J. Glock. The cooperation received from the Washington Departments of Fisheries (WDF) and Game (WDG) is greatly appreciated. Mr. R. Orrell from WDF's Skagit Lab provided information on Skagit River salmon and Messrs. Cook and Young, at the Skagit Hatchery, provided facilities and assistance for taking eggs and holding juvenile salmon. Messrs. Engman and Oppermann, WDG, conducted aerial surveys and provided other information about Skagit River game fish. Mr. 0. Hettick, USGS, provided timely streamflow and temperature data from USGS gaging stations. Thanks are due Dr. E. Brannon, University of Washington Fisheries, for technical advice on salmon egg development and handling; Mr. G. Yokoyama, University of - - I I ) Fig. 1.1 II) ~ 75 w :. • ...t LfGfNO USGS GAGING STATION .IVf. MILl ""'" STATE IISH HATCHin STAT! l!AIINC ~0~ ~ I Skagit Basin study area. 6 Washington Hatchery, for providing hatchery space and technical assistance for our incubation studies; and Mr. J. Dong, University of Washington Hatchery, for monitoring our incubation experiments during 1977 and 1978. Mr. B. Snyder, FRI, provided space and assistance for experimental stranding studies at Big Beef Creek Research Station. Mr. C. Simenstad, FRI, and Ms. A. Litt, University of Washington Zoology Department, assisted by the loan of zooplankton sampling gear. We greatly appreciate the assistance of SCL personnel in the Engineering section and Office of Environmental Affairs by providing needed data and technical support, and the Power Control Center for providing flow information and controlled flows; we also appreciate the valuable support at Newhalem throughout our field studies. - - - ~' - - - 7 2.0 PHYSICAL ENVIRO~mENT 2.1 Discharge_ The waters affected by the Skagit Project are the 94.2 river miles of the mainstem Skagit River between Gorge Powerhouse (near Newhalem) and Puget Sound. The three major tributaries of the Skagit River are the Cascade, Sauk, and Baker rivers with mean annual flows of 1,040, 4,42R, and 2,700 cfs, respectively (U.S. Geological Survey--USGS). As a result of inflow from the smaller tributaries, the mean annual Skagit River discharge (USGS) increased from 4,511 cfs at Newhalem to 5,688 cfs above Alma Creek and to 6,580 cfs near Marblemount just above the confluence with the Cascade River. Continuing downstream the mean annual flow (USGS) at Concrete, just below the Baker River, was 15,2RO cfs and finally became 16,980 cfs near Mount Vernon. The long-term seasonal flow patterns for the Skagit at Newhalem (natural), Sauk, and Cascade rivers (Fig. 2.1) were characterized by hi?h flows during late spring and early summer and by low flows during late winter and late summer. The effect of regulation by the Skagit Project on Skagit River discharge (Fig. 2.2) has been to reduce the unregulated flows during Hay, June, and July resulting primarily from snowmelt, and increase them for the remaining 9 months, particularly from November through f1arch. The 1974-mid 1978 hydrographs (Figs. 2.3-2,7) for the Skagit (at Newhalem, Marblemount, and Concrete), Cascade, and Sauk rivers generally reflect the seasonal patterns where consistently higher flows usually occurred in May, June, and July while during late fall and winter, the high flow events were more transient in nature. Beginning in September 1976 (Fig. 2.5), the streamflows were markedly reduced from previous years reflecting the low flow conditions generally experienced in the Pacific Northwest. This general condition continued until late October 1977 (Fig. 2.6) when the more normal streamflow pattern was resumed. Operation of hydroelectric power plants tended to make the Skagit River flow pattern more irregular than the flow patterns of the unregulated Cascade and Sauk rivers. Flow patterns at Newhalem gaging station were influenced by Seattle City Light's (SCL) Skagit Project while Concrete gaging station being downstream of the Raker River, was influenced by the discharges from Puget Sound Power and Light's Baker River developments as well. Skagit River flows were commonly lower on the weekends because of the reduced demand for power. The weekend periods are indicated in Figs. 2.3-2.7 by the dashes along the time axis. The predominant features of the short-term Skagit River flow pattern were the hourly and daily flow fluctuations resulting from cycling the Skagit hydroelectric plants. Daily flow releases from Gorge Power~ouse usually reflected the typical power demand cycle by increasing in the morning, remaining high during the daytime period of peak demand, decreasing in the evening, and remaining low during the night. Figures 2.8-2.12 show the magnitude of the daily fluctuations in both gage -(I) ~ -~ bj -c 12000----------------------------------------------------------~ 10000 r------ 8000 '" I I I I I -----· I I • 6000 t-L----- _.,.. ____ I t-~~l!_K_~1 1VER ·------' 4000 "' I ----..1 I --.-.... --. I I I ........ _..,. __ I I L-----,..-----· GORGE-NATURAL i I I ._ ____ .... , 2000 CASCADE RIVER I 0 I • I I l . l JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV Fig.2.1 Long-term natural streamflow patterns for Sauk and Cascade rivers (USGS 1929-1976) and for Skagit River at Newhalem (SCL 1910-1975). -J .I • DEC I J ........ (/) lL. u ....., ~ 0:: a: :I: u (/) ...... CJ ) 14000 12000 10000 8000 -.------L-----I I I 6000 I I I REGULATED I -----. I r----- ~-----. I r-----1 ------1 -----1 ~-----I 4000 -----1 I ,------1 I NATURAL _____ , I I 2000 r 0 _j_ AUG SEP lJCT t1AY JUL JUN t~AR APR JAN FEB NOV Fig. 2.2 Long-term natural and regulated streamflow patterns for Skagit River at Newhalem (1954-1975) (SCL and USGS). l. DEC 1974 DISCHARGE ~ 15~~-----------.----------------4-~------~---------------------+----~~ (f) u.. u ~ 10~4-~--------~--------------~~--~~~~~----~--------------~r---~~ D D 8 s~~~~r---~--++~~~~~~~~--~--~----~~~~~~-------------r~~-tfL~ X ~ 0~~~==~~~~~~~~---L--~~~~==~~~~~~~ ~ 30.-orr-----------~--------------rr-nrr-----~--y-,---~==~~~----------,.----~-, :r: u (f) 0 25~~+-~--------~----------~--~~r------------r~~~====~----------~----~~ >-...J · · ··;:E 20·~-+----lft-+A--------+'li---Hh------f-HHf------f---+---------\r--,f----------------+--tHt-----ttt-l 0 DATE Fig. 2.3 Hydrographs of mean daily discharges at gaging sites on the Sauk, Cascad~ and Skagit rivers for 1974 (USGS). J .... 0 25 20 15 (/) LL u 10 0 0 0 ..... 5 X ~ 0 0::: a: 30 ::c u (/) 0 25 >- _J ~ 20 D :z a: w l: Fig. 2.4 1975 DISCHARGE DRTE Hydrographs of mean daily discharges at gaging sites on the Sauk, Cascade, and Skagit r.ivers for 1975 (USGS). 1976 MERN DRILY DISCHARGE ~---------------------------------------------------------------------------. ~ t5~-----------------------------------------7L-~~----------------------------, (/) ...._ u ~ 10~~~--------------------~+-----~~--~~~------------------------------__, D 0 0 ...... X ~ 0~~~==~==~~~~~~~~~~~~~~~~~~~~~ ~ ~~~------------------------~~~--~~~~~--------------------------------~ I u (f) 0 25~-H~--------------------~~-*~~~4+~--~4H~~~~~~------------------, . . J O -JAN TIME IN DAYS Fig. 2.5 Hydrographs of mean daily discharges at gaging sites on the Sauk, Cascade, and Skagit rivers for.l976 (USGS) . DEC I-' N 1 J 1977 MEAN DRILY DISCHARGE 25r-------------------------------------------------------------------~----~ X ~ et:: ~ 30.-~,---------------------------------------------~------------~~--~~~--~ u UJ 8 2Sr--it-------------------~----------------------~~~~~~------~--~~~~~ >- _j ~ 20r--it-------------------~~------~--------~~~~----------~--~--~--~+-~ 0 z ffi 15~~~--~----~~--~--+--r----~~~--~~~~----~----------~~~~~~-+~ L: TIME IN DAYS Fig. 2.6 Hydrographs o~ mean daily discharges at gaging sites on the Sauk, Cascade, and Skagit rivers for 1977 (USGS). NDV DEC ") .) J J J .... < ~ 0 ::: 30 25 1978 MEAN DRILY DISCHARGE TIME IN DAYS SAUK R. CASCADE R. Fig. 2.7 Hydrographs of mean daily discharges at gaging sites on the Sauk, Cascade, and Skagit rivers from January through June 1978 (USGS). l 1-' c-. 91 ...... ~85 ~84 § 83 82 81 • ... j -j 1974 SKRGIT RIVER RT NEWHRLEM 80~~----~---L-----L----~----L---~----~-----L----~----L---~----~~ JAN FEB Fig. 2.8 MAR APR MAY JUN JUL AUG SEP OCT NOV TIME IN DAYS Daily range of flow fluctuations in ft and cfs for Skagit River at Newhalem (USGS) for July through December, 1974. The mean daily discharges for this period and the mean monthly discharges for the year are also shown. DEC D ...... en 15 Q 5l ~ 10 >< 9 -B 0 D 7 0 6 n , 5 en 4 2 1 l GAGE HEIGHT DAILY RRNGE 1975 -SKRGIT RIVER RT NEWHRLEM TIME IN DAYS Fig. 2.9 Daily range of flow fluctuations in ft and cfs for Skagit River at Newhalem (USGS) for 1975. The mean daily discharges and the mean monthly discharges are also shown. 35 30 25 10 9 8 7 6 5 4 3 2 1 t::::l (/) n = 3:> ;;:o ;::;-, rn >< 1-' (7\ ,...... ... 0 0 0 ........ n 11 (/) - 91 ] GAGE HEIGHT DRILY RANGE 1976 -SKAGIT RIVER AT NEWHRLEM TIME IN DAYS Fig. 2.10 Daily range of flow fluctuations in ft and cfs for Skagit River at Newhalem (USGS) for 1976. The mean daily discharges and the mean monthly discharges are also shown. = = <;> = 1-' ::;-, rn '-J >< 1----' ~ a C) C) " --n (/) Fig. 2.11 GRGE HEIGHT DRILY RANGE 1977 -SKAGIT RIVER RT NEWHRLEM TIME IN DAYS Daily range of flow fluctuations in ft and cfs for Skagit River at Newhalem (USGS) for 1977. The mean daily discharges and the mean monthly discharges are also shown. 10 9 8 7 6 5 4 3 2 1 t::1 (/) n ::r:: > ;.;o ·~ n1 >< ..... ....... ~ .. a 0 a n , (/) 91 ~84 g 81 80 GAGE HEIGHT DRILY RANGE 1978 -SKAGIT RIVER RT NEWHRLEM TIME IN DAYS Fig. 2.12 Daily range of flow fluctuations in ft and cfs for Skagit River at Newhalern (USGS) from January through June 1978. 35 30 25 20 ~ 15 VI (""") ::r: l> ;J:J "' ,., 10 X 9 ~ f-' 8 0 -o 0 7 0 6 (""") .., 5 VI 4 3 2 20 height and discharge for the Skagit River at Newhalem (USGS) for 1974-mid 1978. Daily fluctuations at the USGS gaging station near Marblemount are shown in Figs. 2.13 and 2.14 for 1976 and 1977. For the period from June to December 1976 the mean daily range in water level was 1.76 ft at Newhalem, 1.38 ft above Alma Creek, and 1.01 ft near Marblemount. The potential effect on aquatic life of flow regulation by the Skagit Project would be greatest, therefore, at Newhalem, and would become progressively dampened downstream as inflow increased. The flow patterns in the Sauk and Cascade rivers resulted entirely from natural factors such as precipitation and snowmelt. The magnitudes of the daily Sauk (Figs. 2.15-2~18) and Cascade (Figs. 2.19-2.22) river fluctuations in gage height and discharge are shown for 1974-1977. The mean difference between daily maximum and minimum water levels during 1976 was 1.89 ft in the Skagit (at Newhalem) while it was 0.30 ft in the Sauk River. Beginning in mid-April 1977, flow releases from Gorge Powerhouse were essentially nonfluctuating until mid-November (Fig. 2.11). Releases were stepped down during this period beginning at about 2,300 cfs and then successively reduced to about 2,100, 1,700, and finally 1,400 cfs. These measures were carried out by SCL because of the general water shortage in the area and to protect fish life from fluctuating flows to low levels. The Skagit Project provides flood control for the Skagit River below Newhalem by reducing the flows resulting primarily from snowmelt during May, June, and July. During the remainder of the year, the Skagit Project generally augments streamflow, but it can-also be used to reduce the peak flows resulting from transient storm events. The estimated "natural" streamflow at Newhalem is compared to the regulated flow pattern at Newhalem in Figs. 2.23-2.26 for 1974-1977. "Natural" streamflow data were obtained from SCL which were calculated by progressively adjusting the discharge at the three dams by the changes in elevation in the respective reservoirs. The extreme daily discharges were compiled from USGS and SCL records for the Skagit (regulated and natural) and Sauk rivers for water years 1970-1976 (Table 2.1). The ratio of maximum to minimum discharge was calculated to show relative stability of systems. The effect of Skagit dams has been to lessen the extremes so that the regulated discharge at Newhalem was more stable with a ratio of 15:1 than the natural streamflow with a ratio of 41:1. The improved stability came about by reducing the maximum flows as well as by increasing the minimum flows. The flow stability of Sauk River with a ratio of 25:1 was intermedi- ate to the Skagit regulated and natural flows at Newhalem. The difference between ratios for Sauk and Skagit-regulated resulted from the difference between maximum discharge while the difference between ratios for Sauk and Skagit-natural resulted primarily from differences between minimum discharge. z ...... ...... w :r: ~4 ~ 3 2 1976 SKRGIT RIVER RT MARBLEMOUNT JAN FEB MAR APR MAY JUN JUL AUG SEP OCT TIME IN DAYS Fig. 2.13 Daily range of flow fluctuations in ft and cfs for Skagit River at Marblemount (USGS) for June through December, 1976. The mean daily discharges and mean monthly discharges are also shown. en n :I: :n 15 :;lJ ~ X N ...... 0 10 8 -n ...., en - 5 4 NOV DEC GAGE HEIGHT DRILY RANGE 1977 -SKAGIT RIVER RT MARBLEMOUNT TIME IN DAYS Fig. 2.14 Daily range of flow fluctuations in ft and cfs for Skagit River at Marblemount (USGS) for 1977. The mean daily dis- charges and the mean monthly discharges are also shown. 5 lj 3 2 l t:::1 (/) n = :I> ;;.a Gl fTl >< N 1-' N ... C> C> C) _.... n 11 (/) JAN --~ ---~ 1974 SRUK RIVER FEB t1AR APR MAY JUN JUL AUG SEP TIME IN DAYS Fig. 2.15 Daily range of flow fluctuations in ft and cfs for Sauk River (USGS) for July through November, 1974. The mean daily discharges for this period and the mean monthly discharges for the year are also shown. -·--· _j 0 .... Cl) n ~ ~ ~ X N -w 0 0 0 n ..., Cl) 16 15 1-12 w w l.Lll z ,__, 9 w I ~ 83 7 6 5 4 3 1975 SRUK RIVER 5 4 3 2 L__L ____ J_ __ ~L_--~----~~---L-----L----~----~----~----~----L-----~=1 JAN FEB MAR APR 14AY JUN JUL AUG SEP OCT NOV TIME IN DAYS Fig. 2.16 Daily range of flow fluctuations in ft and cfs for Sauk River (USGS) for 1975. The mean daily discharges and the mean monthly discharges are also shown . . J DEC 1-12 w w LL 11 z 6 5 4 1976 SRUK RIVER 3~~----~----~----~----~----~----~----~----~----~--~~~--L-----~= JAN FEB MAR APR MAY JUN JUL AUG SEP OCT riOV TIME IN DAYS Fig. 2.17 Daily range of flow fluctuations in ft and cfs for Sauk River (USGS) for 1976. The mean daily discharges and mean monthly discharges are also shown. DEC n "'T1 10 ~ " -F t-12 w w u_ 11 :z ,__, w ::r: GRGE HEIGHT DRILY RRNGE 1977 -SRUK RIVER TIME IN DAYS Fig. 2.18 Daily range of flow fluctuations in ft and cfs for Sauk River (USGS) for 1977. The mean daily discharges and the mean monthly discharges are also shown. .J DEC } 65 60 55 50 lJ5 ljQ 35 30 5 lj 3 2 1 t::l (/) n ::::t: )> ::0 N :7'1 0\ rr1 >< I-' -.· 0 0 0 ........ n --n (/) -~ 1-w w lL. z ...... 1- [5 t-1 w I 11 10 1 } 1974 CRSCRDE RIVER TIME IN DAYS Fig. 2.19 Daily range of flow fluctuations in ft and cfs for Cascade River (USGS) for July through December, 1974. The mean daily discharges for this period and mean monthly discharges for the year are also shown. 0 -en ~ 5 :::0 ~ 4 >< N ...... ..... 3 0 8 2 n , en 1-w w LL. z ....... JAN 1975 CRSCRDE RIVER ~. 1 1, I .~ \ 1\ t ,, I"' I~ ~ I ·~ FEB MAR APR MAY JUN JUL AUG SEP OCT NOV TIME IN DAYS Fig. 2.20 Daily range of flow fluctuations in ft and cfs for Cascade River (USGS) for January through November, 1975. The mean daily discharges for this period and the mean monthly discharges for the year are also shown . . J DEC 0 ,_. C/) n I D ;;:o ~ N Q) 13 JAN FEB MAR Fig. 2.21 ) 1976 CRSCRDE RIVER APR MAY JUN JUL AUG SEP OCT NOV TIME IN DAYS Daily range of flow fluctuations in ft and cfs for Cascade River (USGS) for August through December, 1976. The mean daily discharges for this period and the mean monthly discharges for the year ar~ also shown. DEC 10 9 a 7 6 5 CJ 4 U) n :r 3 ~ ~ X 2 -§ n .., 1 U) z ....... ....... w :r: GRGE HEIGHT DRILY RRNGE 1977 -CRSCRDE RIVER \11 1~1 JJ~\ } .. \ . I~ I\ "' I TIME IN DRYS Fig. 2.22 Daily range of flow fluctuations in ft and cfs for Cascade River (USGS) for 1977. The mean daily discharges and the mean monthly discharges are also shown. I ., 't '• '\ ., ·~, 10 9 8 7 6 t::1 5 en Cl 4 = ::t:>o = ::;) 3 rn :>< ...... w 2 ... 0 0 0 0 ...... Cl 11 en 1 ._, . 5 • 4 . 3 . 2 J -J 30.-----~--------------------------------------------------~ 25 -fe20 u ....... 0 0 0 ..... x15 ~ 0::: a: ::I: u ~10 0 .~ .. 1\11 I fl I 1 I I I I I I l • • Skagit River at Newha 1 em 1974 I 'f ' ' • .. II •• If II II II II JAN FEB MAR APR MAY JUN JUL DATE AUG Natura 1 Regulated SEP OCT Fig. 2.21 Natural and regulated streamflows in cfs for Skagit River at Newhalem for 1974 (SCL and USGS). NOV DEC w ....... l - 30.---------------------------------------------------~--~ •• •• 25r-------------------------------------------------------~~·--~ :I Skagit River at Newhalem Natural Regulated 1975 I I • I • ~20 I I I I I I - JAN FEB MAR APR MAY JUN JUL AUG SEP OCT Fig. 2.24 Natural and regulated streamflows in cfs for Skagit River at Newhalem for 1975 (SCL and USGS). J NOV DEC w N l -, } 30.--- 25 --(1)20 ~ § -x15 ~ 0::: a: :t: u ~10 0 ~ I' •' I 'I' I • I till II I 'I II I I J. II I I I 1 I I II JAN FEB MAR APR MAY JUN JUL Skagit River at Newhalem 1976 Natura 1 Regulated AUG SEP OCT NOV DEC Fig. 2.25 Natural and regulated streamflows in cfs for Skagit River at Newhalem for 1976 (SCL and USGS). 30~-------------------------------------------------------. 25~-------------------------------------------------------4 ,...... Ul2Q IJ_ Skagit River at Newhalem 1977 u ........ Natural 0 0 Regulated 0 ....... x15 ~ a::: a: :::r: ~10 ' Cl J ' QL---~----~----~----J_ ____ L_ __ ~L---~L---~-----L-----L----~----~ O JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEc 365 Fig. 7.26 Natural and regulated streamflows in cfs for Skagit River at Newhalem for 1977 (SCL and USGS). J Water year 1970 1971 1972 1973 1974 1975 1976 He an Table 2.1 } Compilation of extreme daily discharges and ratio of maximum to minimum discharge for water years 1970 to 1976. Skagit regulated and Sauk River discharges obtained from USGS records while Skagit natural are from set records. Skagit at Newhalem Skagit at Newhalem Sauk River regulated natural Max. Min. Ratio of Max. Min. Ratio of Max. Min. dis-dis-max. to dis- dis-max. to dis-dis- charge charge min. charge charge min. charge charge (cfs} {cfs} (cfs} (cf s) ·-~ ... ~--... -~-o..-..---(ds} (cfs) 7,000 1,030 7:1 22,500 750 30:1 14,500 1,010 17,900 1,060 17:1 24,250 550 44:1 26,500 1,190 24,700 1,130 22:1 34,575 675 51:1 24,300 1,320 7,560 1,060 7:1 16,625 525 32:1 20,700 1,170 20,500 1,070 19:1 29,550 550 54:1 40,800 1,120 14,600 1,020 14:1 23,250 500 47:1 23,200 860 24,100 1,580 23:1 31,950 850 38:1 50,600 1,330 16,622 1.136 15:1 26,100 629 41:1 28,657 1,143 Ratio of max. to min. 14:1 w \Jl 22:1 18:1 18:1 36:1 27:1 38:1 25:1 36 The mean annual discharges for the 1970-1976 period were 4,751 cfs for the Sauk, 4,683 cfs for Skagit-regulated, and 4,634 cfs for Skagit-natural. The watershed upstream of Newhalem was drier on the average than downstream drainages including the Cascade, Sauk, and Baker rivers. Discharge per square mile of drainage area was calculated from USGS data for sites along the Skagit downstream of Newhalem and for key tributaries (Tables 2.2 and 2.3). Comparison of discharge per square mile of drainage area showed that the drainage upstream of Newhalem had the lowest value, 3.8 cfs/mi2. Because of inflow from generally wetter drainages the discharge per square mile gradually increased to 5.6 cfs/mi2 at Concrete. 2.2 Temperature 2.2.1 General Discussion Long-term temperature regimes for the Skagit (above Alma Creek), Sauk, and .Cascade rivers {Fig. 2.27) were characterized by high temperatures from July through September and low temperatures from December through March. Skagit River temperature was significantly warmer than Sauk and Cascade temperatures beginning in October and September, respectively, and extending to mid-February. During this period the Skagit temperature was influenced by the stored heat in the upstream reservoirs (primarily Ross), and, therefore did not fall as rapidly as it did in the other rivers. From mid-February to mid-May Skagit temperature was cooler than Sauk or Cascade temperatures reflecting the cool and homothermic condition of the reservoirs. In May, as Ross Reservoir began to stratify, Skagit temperatures began to increase more rapidly than before and were intermediate to Sauk and Cascade temperatures through mid-July. All three reach their peaks in August with the Skagit being coolest .• Temperature patterns for the Skagit (above Alma Creek-USGS), Sauk (SCL), and Cascade (SCL) rivers in 1976-mid 1978 (Figs. 2.28-2.30, res- pectively) were generally similar to the long-term temperature regimes (Fig. 2.27) except during summer. During the drought year of 1977 the peak summer temperatures were 3°-5°F higher than average. In addition in both 1976 and 1977 the Cascade River summer temperature was the coolest of the three rivers while for the long-term mean the Skagit was coolest. A longitudinal temperature gradient was present in the Skagit River between Newhalem and Rockport (Fig. 2.31). From mid-January to mid-October, downstream temperature was generally warmer than upstream temperature and from mid-October to mid-January, the opposite was generally the case. These patterns in part reflect the thermal condition of the upstream reservoirs. The cooler upstream temperature from January to April resulted from the cool and generally homothermic reservoirs coupled with the radiational warming that occurs as the Skagit flows through its course from Newhalem to Rockport. Even after May, when the reservoirs (particularly Ross) begin to thermally stratify, solar - i ~I - - - - ~. l 1 Table 2.2 Mean annual Gage location flow (cfs) Newhalem 4,511 Alma Creek 5,688 Harblemount 6,580 Concrete 15,280 Mt. Vernon 16,980 Table 2.3 Tributary Newhalem Creek Cascade River Sauk River Baker River } Mean annual dLc;charge, drainage area, and discharge per square mile of drainage area for selected sites on the mainstem Skagit River. Shows incremental increasE~::> be tween site?. Based on ' USGS records. Additional Flow per mi2 Inflow between Drainage drainage area Flow per mi 2 between sites sites (cfs) area (mi 2 ) -~ (cfs/mi2) (cfs/mi2) 1,175 3.8 1,177 99 11.9 1,274 4.5 892 107 8.3 1,381 4.8 8,700 1,356 6.4 2,737 5.6 1,700 356 4.8 3,093 5.5 Mean annual discharge and drainage area for selected S~?git River tributaries. Mean annual Drainage area Flow per . 2 m~ flow (cfs) (mi 2 ) 2 (cfs/mi ) 181 27.9 6.5 1,040 172 6.0 4,428 714 6.2 2,700 297 9.1 w ......, . J 5 6 LONG-TERM MEAN TEMPERATURES 4 [!] SKAGIT RIVER ABOVE ALMA CREEK lil (USGS, 23-YEAR MEAN) j v-~ 2 (!) SAUK RIVER (SCL AND USGS .... r&. 7-YEAR MEAN) ~ -..., ~~ • CASCADE RIVER (USGS .e-~ 0 18-YEAR MEAN) v \\ ~ / 8 ~ ~~ i'ro 5 5 6 _u/ v ' ~ )& 4 __,-p 1/A ~ \ ~ 2 ;f ~ ~ ( ~ 0 ~ ""-' ~ 91: ~ 1-.::J ,_. ..... 'U ~7 ( 6 -¥!! 3 3 34 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV Fig. 2.27 Long-term mean water temperatures for Skagit River above Alma Creek (USGS, 23-year mean), Sauk River (SCL and USGS, 7-year mean) and Cascade River (USGS, 18-year mean) . \ ~ ~0 ~ r:::1 -... ' (D DEC w (X) 1 --l -, . 1 • 4-r---·----........ ~. 5 2 5 0 8 6 4 2 q 3 8 3 6 34 1976 TEMPERATURES )\ [!] SKAGIT ~ m. n'>. ~ (!) SAUK ,.,.--o ...,/ A CASCADE / IE--A \ "" ? ~~ -1\\~ ..... ~ .(!{' ~ / ' "'" fb.. -.-. I 'J I'm I ~ v 1\\ ..... ~ A ~ ri ~ ~ '\!( JAN FEB MAR APR t·1AY JUN JUL AUG SEP OCT NOV Fig. 2.28 Semi-monthly water temperature (°F) for Skagit (above Alma Creek), Sauk, and Cascade rivers during 1976 (USGS and SCL). \ ~h t:m \ 4:>. DEC 6 0 5 8 5 6 5 ~4 ::! 1- ~4 4 2 0 8 6 4 1977 TEMPERATURES 1977 TEMPERATURES 1!1 SKAGIT (!) SAUK .. CASCADE J ~ ~~ )1\ ~ \ /ur ~~ GY ~/; ~~ ~ , ~/ \~ \m. II \~ ~ VI \ ~ _\ ~ '\... \\ l\, ... ~ w a.... :c W4 I- rlb / ~ ~ "- 4 0 3 ff -~. 3 6 34 ~ $ ~ ~ \~ -I'M b -; j ll ~ -E:r.,_. ~ W/ '-"' ~ JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV Fig. 2.29 Semi-monthly water temperature (°F) for Skagit (above Alma Creek), Sauk, and Cascade rivers during 1977 (rrSGS and SCL). '- ~ m 10 ~ ~ DEC 5 5 5 ;:4 ...... w J: ~4 g§ a: 1.1... '-'4 w 0:: :::J 1--0:4 0::: w 0... I: ~4 3 3 3 4 2 0 8 6 4 2 q 8 ( I. 6 4 ) 1978 HJ1PEPATURE: 1978 TEMPERATURES [!] SKAGIT (!) SAUK A CASCADE flY r v;~ ®.. /r>T' ~ \., rn /rn :1 t.:r }%" ['.,. ............ ....../ W' ~ ~ lA JAN FEB MAR APR ... rn" ~ / MAY n::Y" ~ JUN 1978 ~ ~ l/ ~ JUL AUG SEP OCT NOV Fig. 2.30 Semi-monthly water temperature (°F) for Skagit (above Alma Creek), Sauk, and Cascade rivers during 1978 (USGS and SCL). DEC 5~~--~--------------~-----r----.-~--.----.-----.----.-----.----, 521----------4 SKAGIT RIVER AT: 1!1 NEWHALEM (!) MARBLEMOUNT .t& ROCKPORT MAR APR MAY JUN JUL AUG SEP OCT Fig. 2.31 Semi-monthly mean water temperatures for sites on the Skagit River at Newhalem, Marblemoun~ and Rockport. Values are means of the years 1974-1977 (SCL). NOV DEC - - - - - - - 43 radiation progressively warmed the downstream temperatures until October. From October to early January, stored heat was released from the reservoirs and the temperatures became progressively cooler downstream. These analyses indicate that the general effects of the Skagit Project on the downstream temperature regime have been to elevate the fall and early winter temperatures; reduce the late winter, early spring, and summer temperatures; and change the temperatures only slightly during late spring. This is based on the assumption that Skagit River predam temperature conditions were similar to Sauk and Cascade river temperature conditions. Analyses by Burt (1973) indicated a colder predam regime for the Skagit at all times during the year. The annual temperature patterns for the Skagit River above Alma Creek (USGS) from September 1974 to March 1978, and the 23-year mean temperature pattern are shown in Fig. 2.32. In general, the temperature regimes were at or below average from September 1974 to September 1976, while after mid-September they were consistently above average through October 1977. During this latter period precipitation and the resulting streamflow were below average. Water temperature was particularly high from June to September 1977., attributable in part to the general drought conditions and to the reduced withdrawal of water for generation from Ross Lake during this period. Seattle City Light implemented this program to conserve water in Ross Reservoir. From November 1977 to March 1978, water temperature remained consistently below average. The annual temperature patterns for the Sauk and Cascade rivers compared to their long-term mean temperature are presented in Figs. 2.33 and 2.34, respectively. The relationships between annual ~nd long-term patterns are in general similar t~ those described above for the Skagit River above Alma Creek. 2.2.2 Potential Effect of Copper Creek Dam The effect of the proposed Copper Creek Dam on the temperature regime of the Skagit River will depend mostly on three factors: stratification, depth of intake, and drawdown. Because specific information regarding these factors was not available, it was difficult to quantitatively estimate the impact of the dam on the downstream temperature regime of the Skagit River. However, by establishing the probable range of these factors it became possible to estimate the probable range of the proposed dam's effects. To estimate the probable degree of stratification in the new reservoir it was useful to compare it to Diablo Reservoir. Copper Creek Reservoir would be in the same general class as Diablo in terms of capacity and retention time, but would be shallower and longer (Table 2.4). Diablo Reservoir became stratified to some degree most of the year (Table 2.5). The degree of stratification, however, was minimal except from May through October. Even then the surface and bottom temperatures usually differed by less than 10°F at the maximum. ) 56r----.----------------------------.-----~----~----~----~--~----~ SKAGIT RIVER ABOVE ALMA CREEK (USGS) lU FEB APR 36~~~----~--~-----L----~--~--~-L~--~--~L_ __ _L ____ ~--~ JAN •• MAY JUN JUL AUG SEP OCT Fig. 2.32 Semi-monthly mean water temperature (°F) for Skagit River above Alma Creek from September 1974 to September 1978 (USGS). The 23-year mean temperature is also shown (USGS). j ~ ) ) NOV DEC ' ) J l ) -) SAUK TEMr£RATUkES 6 0 ' ~-- 5 SAUK TEMPERATURES A 8 -7-YEAR t·1EAN -· \ (!) 1975 j 6 I \ A 1976 4 + 1977 lA'rr~_ v .ttl""-~A X 1978 ¥ 2 l = I L~ At.~ ~ v .... [\ 0 }/_ I:L \; \\ 8 ~ ~ ~ / 6 n ..... v _.., ....., ~ 4 ~ ~ t'-Jt,. y -\~ 2 n ..1. ··~ ~ \\~ '"l!r'"~ 0 m4 ~ \~ ~~ d ,, ~ Wf' v ~ I 6 ....., 5 5 - 4 3 3 34 JAN FEB MAR APR ~iA'r JUri JUL AUG SEP OCT rwv DEC Fig. 2.33. Semi-monthly mean water temperature (°F) for Sauk River from January 1975 to May 1978 (SCL). The 7-year mean temperature is also show~ (SCL). 56 54 52 50 ,..... f-....... ~48 z ~ ~46 LL. CASCADE TEMPERATuRES CASCADE TEMPERATURES -18-YEAR MEAN 4. 1976 + 1977 X 1978 I _j .7r ./ A v// ~' ., ..... ./..&-. / "AD vi ~ C-1 A I '\ // v ~ \. r 7 '"" ~ I/ J err \ 1\ V~ / '\.' I ' / ~ \ ~ t--... ... ~ ~ :~7 v IX ~~ 38 36 l). m 34 f JAN FEB t4AR APR MAY JUL AUG SEP OCT i!OV Fig. 2.34. Semi-monthly mean water temperature (°F) for Cascade River from May 1976 to May 1978 (SCL). The 18-mean temperature is also shown (USGS). j.i_ c 1 Reservoir Diahio Copper Creek Year Jan 1971 1972 .4 1973 . 7 1974 0 1975 1976 1977 1.5 Mean 0.7 Table 2.4 Specifications of Copper Creek (to 495-ft elevation) and Diablo reservoirs. Capacity Retention Length Fore bay Intake (Ac-ft) time (mi) depth depth (days) (ft) (ft) 90,000 "' 11 4.2 300 125 123,000 "' 11 10.2 "' 150 "' 110 Table 2.5 Temperature difference between surface and bottom in degrees F. for Diablo Reservoir, MONTH Feb March April May June July Aug Sept Oct Nov . 3 1.8 1.4 7.9 9.0 8.1 1.8 .4 .4 . 7 4.0 2.2 5.2 9.4 3.4 3.6 1.4 0 . 7 4.9 10.1 9.7 3.4 0 • 9 2.8 3.6 1.3 6.0 11.0 8.8 2.0 3.0 0 . 5 . 7 2.2 6.4 11.7 5.1 7.0 2.9 2.2 0 0 . 3 3.7 5.2 5.8 5.8 6.4 4.0 3.1 .1 . 2 1.9 7.6 14.0 17.4 16.4 11.7 7.6 2.4 0.1 0.5 1.7 4.7 5.1 9.0 9.5 7.6 3.6 2.4 ~ ....... Dec 0 . 2 . 9 1.1 . 2 2.0 1.3 1.0 48 For two reasons Copper Creek Reservoir may stratify to a lesser extent than Diablo Reservoir. First, since Copper Creek Reservoir is expected to be shallower, its bottom waters would mix more easily with the surface water. Secondly, the Copper Creek Dam is expected to be used primarily for base load generation and flow reregulation. The level of the reservoir, therefore, would be fluctuating in response to the peaking flows of the dams upstream. This peaking inflow may help to mix the reservoir water and break up stratification. Preliminary information on Copper Creek Dam indicated that the intake would be about 110 ft below full pool elevation (495 ft). At this level the intake would draw water from below the reach of most stratification, where seasonal temperature changes are not as extreme as at the surface. This intake depth is comparable to the intake depth of 125 ft at Diablo Dam. Drawdown is a factor because it has the effect of raising the intake depth. In addition, the heating or cooling of exposed shoreline can significantly affect surface temperatures upon subsequent flooding. However, drawdown in the proposed reservoir is not expected to exceed 15 ft and is expected to average approximately 10 ft. Again, conditions would be similar to Diablo Reservoir, where the average between the minimum and maximum elevations for 1974, 1975, and 1976 was 13.7 ft. If the minimum values for each of the factors discussed above (limited stratification, a deep intake, and limited drawdown) are realized, then the temperature effect of Copper Creek Reservoir would probably be insignificant. The waters should be well mixed and moving through the reservoir fast enough that it would be acting very much like a free-flowing river. However, if the maximum values are realized (a high degree of stratification, shallow intake, and large drawdown) then the temperature changes could be significant. An estimate of the temperature changes was based on the assumption that the temperature effects caused by Copper Creek Reservoir are unlikely to be more extreme than those caused by Diablo Reservoir. Figure 2.35 shows the mean monthly temperature changes from Ross tailrace to Diablo intake based on temperature profiles measured during 1971 to 1977, that is, the temperature changes as water passes through Diablo Reservoir. These were used to estimate the temperature changes that would potentially occur as water passes through Copper Creek Reservoir. Figure 2.36 shows the mean monthly temperatures at Gorge intake which were used to approximate mean monthly temperatures of water flowing into Copper Creek Reservoir. By applying the Diablo Reservoir temperature changes to the Gorge intake temperatures, the mean temperatures for Copper Creek Dam intake were estimated (Fig. 2.36). This analysis indicated the maximum E!xtent that Copper Creek Reservoir could potentially shift the downstream Skagit River temperature regime. The estimates are maximum partly because intake water to Copper Creek Reservoir from Gorge Reservoir would be closer to natural flow temperatures than intake to Diablo Reservoir from Ross Reservoir. Mean .~ -, l MEAN MONTHLY TEMPERATURE CHANGE FROM ROSS TAILRACE TO DIABLO INTAKE ] ) 2~------------------------------------~n----------------------~--~ ~1~--------------------------------~L-------~--------------------~ LL. ~ z cr: :::c u ~~----------~~--------------------~L_ __________________ ~r-------------~ wO 0::: =:! 1-cr: 0::: w a.... :L w ~--1~-----------------------------------------_..).~----+i -2L---~----~----~-----L----~----~----~----L---~~--~----~----~ JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Fig. 2.35 Mean monthly temperature change from Ross tailrace to Diablo intake. Compiled from SCL data 1971-1977. Because Ross power generation was reduced in the summer of 1977, the mean for 1971-1976, i.e., excluding 1977, is indicated with an X. MEAN MONTHLY TEMPERATURE AT GORGE INTAKE AND APPROXIMATED MEAN MONTHLY TEMPERATURE AT COPPER CREEK INTAKE 54,---------------------------------------------~------------------------~ GORGE INTAKE COPPER.CREEK INTAKE 52~--------------------------------------------~----------------------~ --48 I.L ....., UJ a::: 246 a: a::: w 0.. I: ~44 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT Fig. 2.36 Mean monthly temperature at Gorge intake and approximated mean monthly temperature at Copper Creek intake. Compiled from SCL data 1971-1977. X indicates the approximated mean for Copper Creek intake based on 1971-1976 temperature data. This period excludes the summer of 1977 when Ross power generation was reduced. NOV DEC ln 0 - 51 temperatures would be elevated between March and September and depressed between October and February. It is interesting to note that this shift would be toward the Sauk-Cascade temperature regimes (Fig. 2.27) which we have speculated may approximate the predam Skagit River regime. The shift could possibly be beneficial to the system since it may partially reverse temperature effects caused by Ross Reservoir. In conclusion, it can be speculated that Copper Creek Dam will have a maximum potential effect of warming summer temperatures by as much as 2°F and cooling winter temperatures by as much as 1.5°F. This would mean a slight shift in the temperature regime toward predicted predam temperatures. The minimum possible effect is that the dam will not significantly change the temperature regime. 2.3 Profile and Gradient In the 37.7 river miles between Gorge Powerhouse and the mouth of the Baker River, the Skagit River decreased in elevation from about 493 to 162 ft above mean sea level (Fig. 2.37) for a mean drop of R.8 ft/mi. Two breaks occur in the profile of this river section, one at RM 86, just upstream of Copper Creek, and another at RH 69, just upstream of the Sauk River. The mean gradient between RH 86 and Gorge Powerhouse (RM 94.2) was 15.1 ft/mi between RH 86 and Rt-1 69 was 8.8 ft/mi, and between the mouth of the Baker River (RM 56.5) and RM 69 was 4.7 ft/mi. The mean gradient of the Skagit River between the mouth of the Baker (RM 56.5) and Puget Sound (RM 0) was 2.9 ft/mi. 1- ltJ LL. z ..... z 0 -1-a: > ~ SKAGIT RIVER PROFILE 500 450 / 400 ~ / 350 300 250 n / )> n VI n C) )> ::0 ;:oo;: c -rn :z ::0 ~--), 0 )> -CD 0 -r-< r-rn rn )> , r-:;o n "'0 )> n y 0 ~ ~ CD :;o --~ e--rn / o n n -f rn CD ::0 ::0 n ;:oo;: VI rn rn VI ~/ c: ITJ rrl )> 0 ""' ""' c: n ""' ::0 ::0 Y" rn ..... rn CD v ""' )> ""' rn :;o __.... 200 -:;o v 150 55 ..... ~ < rn f~ 59 63 67 71 75 79 83 87 RIVER MILE Fig. 2.37 Skagit River profile illustrating the change in elevation from Gorge Powerhouse to the Baker River. 0 c: z -f -< r--:z rrl 91 /~ , 0 2:: rn ::0 ::z:: 0 ~-,., 95 - - .- - 53 3.0 PERIPHYTON AND BENTHIC INSECTS 3.1 Introduction Flow fluctuations during power generation result in periodic exposure of the benthos and periphyton in shoreline areas of the Skagit River. Studies initiated in 1976 to determine the effect of this exposure on the standing crop of benthic insects and periphyton were continued during 1977. Benthic insects and periphyton in the unregulated Sauk and Cascade rivers were also examined for comparison with the Skagit. Due to unusual drought conditions during 1977, Skagit River flows were maintained at a relatively constant level during much of the year. It was possible to compare benthic insect standing crop at the same station under both fluctuating (1976) and non-fluctuating (1977) flow regimes. In addition to the field studies, the effects of flow fluctuations on aquatic insects were examined in an artificial stream. Reductions in benthic standing crop due to fluctuating flow regimes below dams have been reported by several investigators (Powell 1958, Pearson et al. 1968, Radford and Hartland-Rowe 1971, Fisher and Lavoy 1972, Kroger 1973, Trotzky and Gregory 1974). Powell (1958) reported that insect biomass per unit area was up to 32 times greater above a hydroelectric dam producing a fluctuating flow pattern than below, and insect populations increased farther from the dam. Fisher and Lavoy (1972), as well as MacPhee and Brusven (1973), found that standing crop and diversity of benthos were markedly reduced in areas that were exposed frequently by flow fluctuations. Water level fluctuations can also destroy periphyton through desiccation during exposure and reduce primary production (Neel 1963, Kroger 1973, Brusven et al. 1974). The objectives of the field studies were to compare the standing crop of benthic insects and periphyton in the Skagit River with standing crop in the Sauk and Cascade rivers. In making these comparisons an effort was also made to determine the effects of periodic exposure due to flow fluctuation on the standing crop of benthic insects and periphyton in the Skagit River. The objectives of the experimental studies in an artificial stream were threefold: 1) to test the ability of selected insect species to avoid becoming stranded during flow reductions; 2) to test the ability of selected species to survive desiccation on a dewatered substrate; and 3) to compare density and composition of insect communities subject to conditions of fluctuating and nonfluctuating flow regimes. 3.2 Study Area 3.2.1 Sampling Sites No data were available on benthic and periphyton standing crop in the Skagit prior to regulation of the river by hydroelectric development. Thus, it was necessary to compare standing crop under the present regulated flow regime with standing crop in the unregulated Sauk and Cascade rivers in order to determine effects of flow fluctuations. The Sauk was frequently turbid, while the Skagit and Cascade were relatively 54 clear year-round. The Cascade, althou~h considerably smaller than the other rivers, was selected as a control stream because of its lack of turbidity. Benthic insects were sampled at one station each on the Skagit, Sauk, and Cascade rivers during 1976, and at two stations on both the Skagit and Sauk during. 1977. The upper stations were established on the Skagit and Sauk rivers above the original stations in 1977 to ensure representa- tiveness within and between rivers and to establish a station on the Skagit above the proposed Copper Creek Dam site. Benthic insect sampling was discontinued in the Cascade River during 1977. Additional effort was placed on the Sauk Upper Station, which was not highly turbid and was more comparable in width and discharge to the Skagit River stations. Periphyton was sampled at the Skagit Lower, Sauk Lower, and Cascade stations during 1976 and 1977, and at the Skagit Upper Station in 1977. Sampling station locations are shown in Fig. 3.1. The Skagit Upper Station near river mile (RM) 84 and the Skagit Lower Station, above the town of Marblemount, near RM 79 were 10 and 15 river miles, respectively, below Gorge Powerhouse. The Sauk Upper Station was established at RM 13, 6 mi above the Sauk Lower Station, and the Cascade River Station was at R.M 0.9. Physical characteristics, other than discharge and drainage area, were similar at all stations (Table 3.1). The substrate was composed primarily of cobble, 3 to 10 inches in diameter, mixed with sand and small gravel. Mean current velocity near the bottom in shoreline samplin~ areas ranged from 1.4 to 2.0 ft/sec among stations. Mean annual discharge, shown in Table 3.1, was roughly 1,000-2,000 cfs higher at the Skagit River stations than at the Sauk stations. Mean annual discharge was considerably lower at the Cascade Station than at any of the other stations. The mean, maximum, and minimum discharge figures in Table 3.1 pertain to the entire period of record (hourly recording) of the U.S. Geological Survey (USGS) gaging station nearest the benthic sampling station. The period of record is different for each gaging station due to differences in the year of original installation or intermittent operation. The Sauk and Cascade gages have been operated continuously for 50 years, and the Skagit at Alma Creek gage has operated for 28 years. The USGS gage at Marblemount was operated intermittently from 1943 to 1951, deactivated for 25 years, and reactivated in 1976. The minimum recorded discharge at the Skagit Upper Station is larger than at the Skagit Lower Station because the Skagit at Alma Creek gage, near the upper station, was not operational when the 620 cfs flow occurred at the lower station. 3.2.2 Artificial Stream Site The artificial stream system was located at Ladder Creek, near the town of Newhalem, Washington. A head tank and pipe system, formerly part of the town's water supply system, were available at this site to supply a large volume of water to the artificial stream channels. The site was - - - ~I - i ---<v--- ~ I t 1 Scale \:j in ~ 1 mi 4 I SAUK LOWER SAUK UPPER SKAGIT SKAGIT l 1 Ross UPPER -Sampling Station A USGS Gaging Sta•ion CASCADE * Gorge Po we rho use Fig. 3.1 Map of the Skagit study area showing benthos and periphyton sampling stations. Table 3.1 Physical characteristics at sampling stations. Discharge values for the Sauk Upper Station are estimates based on drainage area. Bottom velocities pertain to shoreline areas only, Discharge (cfs) Drainage Mean bottom Station ~an Maximum Minimum area(mi 2 ) velocity (ft/sec) Substrate nual Recorded Recorded Skagit Upper 5,688 38,500 990 1,274 1.6 Cobble Skagit Lower 6,580 59,300 620 1,381 1.4 Cobble Sauk Upper 4,251 79,104 549 688 1.8 Cobble Sauk Lower 4,428 82,400 572 714 2.0 Cobble Cascade 1,040 18,700 118 172 1.4 Cobble V1 a- - - ,~ 57 also accessible only through a locked ?ate. The area was heavily shaded, allowing little direct sunlight to penetrate, and air temperatures were sometimes 18°F cooler at the artificial stream site than on the shoreline of the Skagit. Insect mortality rates on exposed substrate subject to the cool air temperatures at the stream site were probably lower than would have been the case under the warmer temperature regime typical of open shoreline areas of the Skagit during summer months. The temperature of Ladder Creek water flowing through the artificial stream channels ranged from 45°F to 56°F over the period of operation of the artificial stream during 1977. 3. 3 rtaterials and }let hods 3.3.1 Physical Parameters Hourly gage height records from the USGS streamflow gaging station nearest to each sampling station were used to determine flow patterns. The USGS gage for Skagit River at ~1arblemount was located approximately 0.7 mi below the Skagit Lower Station while th~ USGS gage for Skagit River at Alma Creek was located 1.5 mi above the upper sampling station. The USGS gage on the lower Sauk was used to determine the discharge pattern at both Sauk stations. The gage was 1.6 mi below the lower station and 7.6 mi below the upper station. The USGS gage on the Cascade River near Marblemount was within 300 yards of the Cascade Station. No major tributary streams entered the rivers between a gaging station and a sampling station, and the flow pattern at the gage was considered similar to the actual flow pattern at the sampling site. The percentage exposure time of the substrate at each periphyton and benthic sample location was computed by determining the amount of time that the water's edge was below the sample site, leaving the site exposed to desiccation. First, permanent transects perpendicular to water flow were established at all sampling stations, and samples were collected only along these transects. A stake was located on the transect near the high waterline. Next, plots were constructed with distance (from the stake on the transect to the water's edge) on one axis and gage height (during the hour when distance was measured) on the other. The distance from stake to water's edge was measured periodically over a wide range of flows and plotted against the appropriate gage height values. A curve was drawn through these points, describing the inverse relationship between gage height and distance to the water's edge at a particular transect. Given a gage height, one could estimate the location of the water's edge, in terms of the distance from the stake at the high water line, by using the distance and gage height curve. The gage height, or flow, that would have resulted in a water's edge at a particular point on the transect, e.g., 25ft from the stake, could also be determined using the curve. When samples were collected, the location of each separate sample site was determined by measuring the distance from the stake to the sample site. Separate measurements were made for each location where replicate 58 samples were collected. By consulting the distance versus gage height curve for the transect, the gage height that would result in a water's edge at the sample location was determined. This gage height value was compared with the USGS records of hourly gage readings for the preceding two or six weeks. The number of hours that the actual gage height was below this value was equivalent to the number of hours that the sample location was exposed. Due to infrequent malfunctioning of the streamflow gages, there were some gaps in the USGS gage height records during exposure calculation periods. If data were not available from one of the Skagit River gages, the complete discharge records from the other gage were used to calculate exposure time. When either the Sauk or Cascade gages were inoperative, it was necessary to assume that flow patterns prior to sampling were similar in these two unregulated rivers. During both 1976 and 1977 the flow patterns in the Sauk and Cascade were nearly identical, differing only in magnitude (Fig. 2.5 and 2.6). Fortunately, whenever one of the gages was not functioning, the discharge records from the other operative gage always indicated that the water level at sampling time was lower than it had been during the preceding 2 or 6 weeks. Thus, only unexposed sites were sampled on these occasions. It was assumed that the water level had declined in a similar manner in the other river, and that samples were also collected only in unexposed areas. The estimation of standing crop above and below Copper Creek (Sec. 11.1.1) required calculation of the wetted area between zero and 1.5 ft deep and total wetted area in several sections of the Skagit River. Sample transect depth data collected during spawning studies (Sec. 6.0) were used. The procedure used to calculate wetted area was the same as the procedure to calculate spawnable area (Sec. 6.3.4), except that only the depth data, and not velocity data, were used. The wetted areas were calculated at low, medium, and high flows as defined in Table 6.10. Turbidity was measured at or above benthic sampling stations from June 1976 through the first week of November 1977. Three to five measurements were made at each station in a month, using a Hach portahle engineer's laboratory. All stations were sampled on the same day. 3.3.2 Periphyton Artificial substrates were used to collect samples of stream periphyton from October 1976 through March 1977. The artificial s~bstrate sampler was constructed of two 0.6-x 15-x 5-cm plexiglass plates attached in a horizontal position to a small wood block. The wooden block was bolted to a 15-x 40-x 60-cm concrete block. Four samplers, each with two replicate plexiglass plates, were placed along transects perpendicular to waterflow in eacb of the three rivers. During riverflow fluctuations, the plexiglass plates on the samplers were exposed and submerged periodically. Those samplers in shallow water were exposed more frequently than those in deeper areas. The colonized plexiglass plates were removed every 6 weeks and replaced with clean plates. Colonized - - - ~1 - - 59 plates were frozen and transported to the laboratory where the periphyton was scraped from the upper surface. In spite of the heavy concrete base, the artificial substrate samplers were susceptible to washout during high flows and had to he replaced several times. A technique for direct removal of periphyton from streambed rocks was devised which avoided the problems associated with the artificial substrate samplers. This alternate method was used to collect samples from May to November 1977. The technique involved removal of all periphyton from a 16-cm2 area on the upper surface of natural streambed rocks. A rubber template with a 4-x 4-cm square cut in the center was held against the rock while the area inside the square was thoroughly scrubbed with a small nylon brush. The detached algae was then washed into a collecting bottle. Samples were concentrated on a 0.45-w membrane filter and frozen for transportation to the laboratory. On each sample date, two replicate samples of five rocks each were collected at four different depths (6, 10, 14, and 18 inches) along the sampling transects at the Skagit Upper and Lower, Sauk Lower, and Cascade stations. Samples were dried in a desiccator under refrigeration, and chlorophyll a content was determined using the method for the determinatio; of chlorophyll a in the presence of phaeophytin a (American Public Health Association (APHA) 1971). The percentage of tim~ that each artificial substrate sampler or sample location was exposed to desiccation during the 6 weeks prior to sampling was also determined. 3.3.3 Benthic Insects Benthic insects were sampled bimonthly from May to November 1976, during February 1977, and bimonthly from May to November 1977. Samples were collected along a permanent transect perpendicular to waterflow at each station. It was not possible to sample the river at depths greater than 18 inches and sampling was confined to the shallower shoreline area of the transect on one side of the river. A 0.25-m2 quadrat sampler (351-w mesh), designed by Malick (1977), was used to sample benthos. This. sampler was a larger, heavier version of the standard Surber (1937) sampler. Large rocks were removed from the substrate and individually cleaned, and the remaining substrate was thoroughly stirred three times with a rake to a substrate depth of 6 inches. Samples were preserved in the field with 70 percent ethanol containing rose bengal dye (100 mg/liter). Current velocity was measured as close to the bottom as possible at each sample location with a Gurley No. 625 Pygmy-type current meter. The number of replicates collected and the water depth at sample locations were different in 1976 and 1977. During 1976, two replicates were collected at locations 6, 12, and 18 inches below the surface of the water at the Sauk Lower and Casacade sampling stations and at the Skagit Lower Station in May only. From July through November 1976, two replicates were collected at depths of 6, 10, 14, and 18 inches at the 60 Skagit Lower Station. During 1977, four replicate samples were collected at eac~ of four locations, 6, 10, 14, and 18 inches below the water surface, along the transects at all stations. Benthic insects were handpicked from detritus and inorganic material, identified to order, and counted. Biomass was determined by multiplying the volume of the insects by 1.05, the value for specific gravity of stream invertebrates used by Hynes (1961). The percentage of time that the substrate was exposed during the 2 weeks prior to sampling was calculated for each replicate sample location. The selection of a 2-week exposure calculation period was based on the time necessary for complete recolonization of the stream bottom by benthos. Recolonization rates for barren substrates varied from 2 weeks (Waters 1964) to 4 weeks (Mason et al. 1967) and over 4 weeks (Coleman and Hynes 1970). Potential problems were foreseen under particular flow patterns using an exposure calculation time greater than the recoloni- zation time. For example, if it took only 2 weeks to recolonize the stream bottom, and a 4-week exposure calculation time were used, misleading results would be obtained if the streambed were exposed continuously or frequently during the first 2 weeks, severely reducing insect abundance, and then submerged continuously for the next 2 weeks. In this situation, the benthos would have time to recolonize the affected areas before sampling, resulting in a normal seasonal standing crop but a high exposure level. These results would give the false impression that high exposure had no effect on insect abundance. Using an exposure calculation period less than the recolonization time could also be misleading, e.g., a 2-week exposure calculation period when the recolonization time is 4 weeks. High exposure of the streambed for 2 weeks followed by a 2-week period of no exposure would probably result in a standing crop much lower than the normal seasonal value, since the insects would have had only 2 weeks to recolonize the streambed, and need 4 weeks for complete recolonization. In this case, standing crop at sampling time would be lower than normal, while exposure calculated over the last 2 weeks would also have been low. The investigator would probably assume that some factor other than exposure reduced insect abundance. It was concluded that the period of exposure calculation should be as long as the time necessary for complete recolonization to avoid the problems mentioned above. Since the precise time for recolonization of denuded areas in the Skagit was not known, it was necessary to use a value from the literature. Actual determination of the recolonization time by removal of insects from an area of the streambed and sampling at intervals until insect abundance returned to the original level would have been impractical. Frequent flow fluctuations during 1976 would have periodically removed insects from the area, preventing complete recolonization. Two weeks appeared to be a reasonable estimate of recolonization time, and an equally long 2-week exposure calculation period was used. '~ ~I - - - 61 3.3.~~perimental Studies 3.3.4.1 Artificial Stream. Four artificial stream channels were constructed at the Ladder Creek site in 1976. Each of the channels was 2.4 m long, 46 em wide, and 43 em deep. Up to four 36-x 41-cm trays containing gravel substrate were placed in the bottom of each channel. The trays were filled with a sand and gravel mixture almost to the top. A layer of S-cm gravel was added to the surface of the trays used in the stranding avoidance experiments, while 5-to 15-cm rocks were used in the trays in the flow fluctuation experiments. The trays sloped from one side of the channel to the other (24 percent slope), simulating a sloping river shoreline. A screen (333-w mesh) at the upstream end of the channel prevented insects and debris larger than 333 W from entering, a drift net (333-w mesh) at the downstream end collected drifting insects, and a screen on the top trapped emerging adults. ~ater depth and velocity in each channel were controlled by manipulation of an inflow valve and sluice gate at the end of the channel. Average velocity in the channels remained relatively constant as the depth was changed, and ranged from 0.41 to 0.51 ft/sec at the valve and gate settings used. 3.3.4.2 Flow Fluctuation Experiments. The effects of two different types of flow pattern on density and composition of benthic insects in an artificial stream channel were examined during 1977. Preparation of channels was similar for all experiments. Rocks colonized by algae were collected in the Skagit and placed in the substrate trays in the two channels. Six bottom samples were collected with a 0.25-m2 quadrat sampler at the Skagit Lower Site, and the uncounted insects and detritus from three samples were distributed as evenly as possible over the four substrate trays in each ch3nnel. Water was maintained at a constant level in both channels for 1 week to allow the insect community to stabilize. Prior to initiating experimental flows, the substrate tray from the downstream end of each channel was removed, and the aquatic insects were collected to determine if equal numbers were present in both channels. The trays with substrate material were then returned to their original location in the channel. After the 1-week stabilization period, the experimental channel was either: 1) dewatered for 18 hr a day for 7 days; or 2) dewatered for 48 continuous hours. Two replicate experiments were conducted using the first flow pattern, while only one experiment was conducted with the second pattern. The water level was always raised and lowered at a rate of 0.7 ft/hr. Organisms drifting out of the experimental channel during increasing or decreasing flow were collected in a drift net. During the flow manipulations in the experimental channel, drift was also collected in the control channel for comparison. At the conclusion of the experiments the three undisturbed trays in each channel were removed and the insects were collected for analysis. 3.3.4.3 Stranding Avoidance. Three speciesof aquatic insects were tested to determine their ability to avoid becoming stranded during flow 62 • reductions in an artificial stream channel. At the start of an experi- ment, water level was adjusted so that the entire substrate surface was submerged. After SO insects of a single species were released in the upper half of the upstream tray, the water level was lowered at a rate of 0.7 ft/hr. The upper half of the sloping substrate tray was completely exposed and only the lower half was submerged after 30 min of dewatering. Insect movement during dewatering was observed visually, and the number of insects that remained in or on the exposed substrate after 24 hr was compared with the number that moved to the lower, submerged half of the substrate tray. The number of insects that avoided stranding by drifting was also recorded. Three species of insects commonly found in the Skagit and Sauk rivers were tested during 1977: Ephemerella tibialis (Ephemeroptera), Acroneuria pacifica (Plecoptera), and Dicosmoecus sp. (Trichoptera). Insects were collected in the Skagit River and transported in a cooler to the artificial stream site where they were allowed to acclimate for 24 hr in screened containers in the channels. The range in body length of insect larvae tested was 6-8 mm for !• tibialis, and 10-1S mm for~· pacifica. The case lengths of the Dicosmoecus sp. larvae ranged from 17 to 26 mm. Two replicate stranding avoidance tests were conducted with each of the three species, using SO individuals in each test. 3.3.4.4 Desiccation Survival. The three species of aquatic insect larvae tested for ability to avoid stranding were also examined to determine their ability to survive desiccation in the event of stranding. A total of 40 to SO insect larvae was placed in petri dishes or plastic containers with a 1-cm layer of either dry or damp sand on the bottom. A control was used to estimate mortality caused by handling. Control insects were subjected to the same handling procedure as the others, but were placed in a screened cage in flowing water. Percent mortality of experimental and control insects was determined at 24 hr. 3.4 Results and Discussion 3.4.1 Physical Parameters 3.4.1.1 Flow Pattern. The flow pattern in the Skagit River below Gorge Powerhouse during 1976 was influenced primarily by demand for power in the City of Seattle. Increased release of water through generating facilities as demand increased in the morning usually resulted in rising water levels. Water level generally remained high during the period of peak demand in the day, and then receded at night as demand declined. Weekend flows tended to remain at a low level for 48 hr. The use of the generating facilities on the Skagit River in this manner for hydroelectric peaking resulted in daily fluctuations in water level which alternately exposed and submerged the shoreline areas of the river. There was a pronounced difference between the degree of fluctuation in the regulated Skagit and the naturally fluctuating Sauk and Cascade rivers in 1976. The mean difference between daily maximum and minimum water levels during the period June to December 1976 was 1.01 ft at the ~, - - - - - 63 Marblemount gaging station near the Skagit sampling site, while it was only 0.29 ft at the Sauk gaging station (Table 3.2). Mean daily fluctuation between high and low water levels was always greater in the Skagit at Marblemount than in either the Sauk or Cascade during those months for which discharge data were available. Because of the dampening effect of tributary inflow, variation in water level in the Skagit at Marblemount was considerbly less than at Newhalem, where the mean daily fl~ctuation from June to December 1976 was 1.76 ft. The pattern of flow fluctuations in the Sauk (Fig. 2.17) and Cascade (Fig. 2.21) was the result of natural factors such as precipitation and snowmelt which sometimes caused rapid increases in flow. However, peak flows usually subsided over a period of days or weeks in contrast to the Skagit, where water level fluctuated an average of 1.89 ft at Newhalem and 1.01 ft at Marblemount every 24 hr during 1976. Daily variations in water level of 2 ft or more occurred several times during June through August 1976 in the Skagit at Marblemount (Fig. 2.13), and daily variations of this magnitude occurred frequently in the Skagit at Newhalem during 1976 (Fig. 2.10). During late January 1976, the water level in the Sauk rose 3.4 ft in a single day, the maximum daily variation for the year. However, the water level dropped slowly, and required approximately 10 days to return to its previous level. Except for a 2-week period in late January, daily fluctuations in water level of 2 to 3 ft were recorded frequently from January to late April 1977 at Newhalem as a result of hydroelectric peaking (Fig. 2.11). Flow was nearly stable from late April to mid-November. Due to low water levels in the reservoirs, no daily hydroelectric peaking was occurring durine this time period, and discharge from Gorge Powerhouse was maintained at a nearly constant level. Peaking was restrned in mid-November and continued through the end of 1977. The pattern of flow fluctuations in 1977 at Marblemount (Fig. 2.14) resembled the pattern at Newhalem. Daily ranges of flow fluctuations from late April to mid-November were slightly more variable than at Newhalem. Inflow from tributary streams was responsible for this increased fluctuation downstream from Newhalem, particuarly during the spring runoff in June. The mean daily range in water level at Marblemount from May to October 1977 was 0.20 ft and was only 0.15 ft at Newhalem (Table 3.3). During periods of hydroelectric peaking, tributary inflow generally dampened the fluctuations downstream. Mean daily range in water level was lower at Harblemount than at Newhalem from January to April and in November and December due to tributary inflow. The higher flows due to rainfall or snowmelt during these periods were definitely accentuated at Marblemount by tributary inflow. The pattern of flow fluctuation was almost identical in the Sauk (Fig. 2.18) and Cascade (Fig. 2.22) rivers during 1977. Only the mag- nitude of the fluctuations was different due to the different sizes of the rivers. Flow patterns at the Sauk and Marblemount gaging stations, as well as the magnitude of the mean daily range in gage height (Table 3.3), were also quite similar from late April to mid-November. The variation in 64 Table 3.2 Mean daily range in water level (ft) during each month in 1976 at the Skagit at Newhalem and Marblemount, the Sauk, and the Cascade gaging stations (USGS). Station Skagit at Skagit at Month Newhalem Marblemount Sauk Cascade January 2.86 0.54 February 1. 92 0.17 March 1.19 0.19 April 1. 81 0.18 May 2.64 0.35 June 1. 34 0.91 0.31 July 1. 86 1.40 0.40 August 2.24 1.40 0.28 0.30 September 1. 54 0. 72 0.18 0.09 October 1.41 0.69 0.18 0.14 November 2.00 1. 09 0.36 0.24 December 1. 90 0.84 0.33 0.20 Annual mean 1.89 0.30 May-October mean 1. 84 0.28 ~I ~. - ~· - - ~. ~1 ~ -· ~"""'\ p:~ ,_ ,_ ~ 65 Table 3.3 Mean daily range in water level (ft) during each month in 1977 at the Skagit at Newhalem and Marblemount, the Sauk, and the Cascade gaging stations (USGS). STATION Skagit at Skagit at Month Newhalem Marblemount Sauk Cascade January 1.08 0.75 0.40 0.23 February 2.23 1.14 0.13 0.16 March 1. 79 0.93 0.17 0.07 April 1. 20 0.65 0.31 0.23 May 0.14 0.18 0.24 0.16 June 0.28 0.33 0.46 0.38 July 0.04 0.12 0.16 0.18 August 0.28 0.27 0.16 0.28 September 0.09 0.14 0.27 0.24 October 0.04 0.13 0.20 0.18 November 1.11 0.87 0.93 0.54 December 1.22 0.68 0.75 0.28 Annual Mean 0.79 0.51 0.35 0. 2.4 May-October Mean 0.15 0.20 0.25 0.24 66 water level at both the Sauk and Marblemount stations during the summer was the result of natural factors such as precipitation and snowmelt, resulting in similar patterns. During the periods of hydroelectric peaking in 1977, mean daily range in water level was considerably higher at the Skagit stations than at the Sauk or Cascade stations (Table 3.3). However, from May through October, daily fluctuation was slightly less at the Skagit stations than at the two unregulated sites. These unusual flow conditions made it possible to compare insect standing crop in the Skagit under fluctuating (1976) and relatively stable (late April to mid-November 1977) flow conditions. Flow conditions were nearly the same at Marblemount, near the Skagit Lower Station and at the Sauk sampling stations from May to October. 3.4.1.2 Exposure Time. It is necessary to know the exposure history of the river bottom locations where samples were collected during any type of benthic study to avoid erroneous interpretation of results. This is true for unregulated coastal streams of Pacific Northwest, where water levels may fluctuate widely on a weekly or monthly basis, as well as fo'r regulated streams subject to peaking flows. Sampling a highly exposed zone of the river bottom shortly after it had been submerged during high flow would probably yield samples containing few benthic organisms. An investigator with no knowledge of the flow or exposure history of the area sampled would probably conclude that the river was extremely unproductive, although benthic macroinvertebrate density in unexposed areas in the deeper regions might be high. If samples had been collected before or after the high flow, in the unexposed zone, the observed abundance would have been higher. Calculation of exposure time during a specified period prior to sam- pling is a useful method for summarizing the exposure history of a parti- cular area of the river bottom. Its primary use is in comparing standing crops in zones of the same stream that were subjected to different degrees of exposure, as was done by Fisher and LaVoy (1972) below.a hydroelectric dam on the Connecticut River. The correlation between exposure time and density of benthic organisms is better under conditions of periodic, daily exposure resulting from hydroelectric peaking flows than under a natural flow regime where bottom areas may be exposed for a week and then sub- merged for a week. The exposure history of all sample locations was taken into account when making comparisons among stations and seasons. It would not have been valid to compare a station where most of the samples were collected in highly exposed areas due to high water at sampling time with another station where samples were collected in unexposed areas.· Therefore, only results from unexposed sampling locations were used in computing the mean density for a station on a given sampling date, with a few exceptions. If no unexposed locations were sampled on a sample date, only the data from the location with the lowest degree of exposure were used. If the mean of the replicates at a location with some exposure would not lower the overall mean for the station--i.e., the mean of the exposed replicates was higher than the mean of the other unexposed replicates--they were also - - ,j - ..... ,~ - 67 used to compute the station mean. These exceptions were noted in the tables containing exposure data. Most of the artificial substrate periphyton samples were highly exposed during the winter of 1976-1977 (Table 3.4). Since the locations of the samplers were fixed, some of them were exposed 100 percent of the time. The high level of exposure and lack of data from unexposed samplers at the Skagit Lower and Cascade stations made it difficult to compare rivers in 1976. The flows were relatively stable during the period when the peri- phyton was removed directly from streambed rocks. As a result, there was relatively little exposure of the sampling sites (Table 3.5). None of the sites at the Skagit Upper Station was exposed prior to sampling from May to November 1977. The 6 inch sites in Hay and June 1977 were exposed early in the 6-week exposure calculation period, and the periphyton apparently had enough time to return to a high level hefore sampling. The other sites at the Sauk Lower and Cascade stations marked with an asterisk (*) were also exposed early in the 6-week period, allowing the periphyton to recolonize before sampling. There was no exposure of benthic insect sampling locations during the 2-week exposure calculation period at the Sauk Lower and Cascade stations in 1976 (Table 3.6). The amount of exposure at sites at the Skagit Lower Station was high during May, September, and November 1976, and no samples were collected in unexposed areas in May or November. During 1977, there was little exposure at any of the stations other than at the Skagit Upper Station in February. All 16 replicate samples were used to calculate the station means during 1977, with the exception of the Skagit Upper Station in February. Since periphyton and benthos were always sampled at the same depths and usually on the same dates in 1977, the 6-week exposure figures in Table 3.5 also represent the amount of exposure for benthic insect sample locations during the 6 weeks prior to sampling. The distances from the permanent marker near the high-water line to each periphyton and benthic sample location are shown in Table 3.7. At a particular site, these distances indicate the locations where the two to four replicate samples were collected. 3.4.1.3 Turbidi~. Turbidity levels were much lower at all stations during August and September 1976 (Table 3.8) than during the same months in 1977 (Table 3.9). The Skagit and Cascade were considerably less turbid than the Sauk during July and August 1977. The drainage areas of the three rivers contain numerous glaciers, and the increased turbidity in 1977 was caused primarily by glacial flour in the water. Glacial melting was more extensive in 1977 than in 1976 because of low precipitation during the winter and generally warmer air temperatures during the summer of 1977. The amount of suspended sediment in the Skagit was reduced by settling in the reservoirs. The difference in turbidity levels between the Upper and Lower Sauk stations was caused by suspended sediment of glacial origin contributed by 68 Table 3.4 Percentage of time that the artificial substrate periphyton samplers were exposed to desiccation during the six-week period prior to sampling. Samplers were located on a cross- river transect, and depth increased with the sampler number. SamEler Number Station Date 1 2 3 4 Skagit Lower 10/14/76 72 41 40 20* 11/29/76 87 81 56 26* 1/12/77 24 13 5* 2* 2/24/77 44 25 9 0 Sauk Lower 10/15/76 81 9 0 0 11/30/76 91 72 0 0 1/12/76 92 54 0 0 3/21/77 87 7* 0 0 Cascade 10/15/76 40 22 0 0 11/30/76 95 90 80 39* 1/12/77 93 83 61 14* 3/21/77 100 100 81 38* *Results from these exposed samplers were used in calculating the mean for the sampling station. - ·-, ~l ~-\ filf/P'J'i;, _., - - 69 *Results from these exposed sample locations were used in calculating the mean for the sampling station. 70 Table 3.6 Percentage of time that the streambed at benthic sampling locations was exposed to desiccation during the two-week period prior to sampling. Sampling DeEth of Water at SamEle Site (inches) Station Date 6 10 12 14 18 Skagit Upper 2/24/77 72 64 50 16* 5/11/77 0 0 0 0 7/26/77 0 0 0 0 9/14/77 0 0 0 0 11/9/77 0 0 0 0 Skagit Lower 5/20/76 35 21 16* 7/28/76 1* 1* 0 0 9/14/76 40 33 6 0 11/12/76 96 86 69 22* 2/24/77 0 0 0 0 5/6/77 0 0 0 0 7/26/77 0 0 0 0 9/14/77 0 0 0 0 11/9/77 0 0 0 0 Sauk Upper 2/17/77 0 0 0 0 5/ 5/77 17* 12* 11* 10* 7/27/77 0 0 0 0 9/13/77 0 0 0 0 11/8/77 0 0 0 0 Sauk Lower 5/21/76 0 0 0 7/14/76 0 0 0 9/15/76 0 0 0 11/12/76 0 0 0 2/17/77 16* 0 0 0 5/ 5/77 10* 0 0 0 7/27/77 0 0 0 0 9/13/77 0 0 0 0 11/ 8/77 0 0 0 0 Cascade 5/21/76 0 0 0 7/14/76 0 0 0 9/15/76 0 0 0 11/12/76 0 0 0 *Results from these exposed sample locations were used in calculating the mean for the sampling station. - - - """' -I ~ - ~ ~. ~ - - - I p.~ - ""' .~ - -· - """" - 71 Table 3.7 Distance (ft) from the permanent marker near the high water line to benthic insect and periphyton sample sites along the transects at sampling stations. Sampling Depth of Water at Sample Site (inches) Station Date 6 10 12 14 18 Skagit Upper 2/24/77* 0 18 31 45 5/11/77 57 64 69 75 6/16/77** 58 65 68 73 7/24/77 67 70 76 81 9/14/77 70 76 87 93 11/ 9/77 68 74 80 89 Skagit Lower 5/20/76* 0 23 30 7/28/76* 0 22 66 108 9 /14/76* 23 30 67 96 11/12/76* 30 50 69 89 2/24/77* 81 93 107 127 5/ 6/77 81 93 107 127 6/16/77** 77 101 114 123 7/26/77 111 122 130 140 9/14/77 121 127 140 146 11/ 9/77 117 125 132 143 Sauk Upper 2/17 /77* 52 61 72 81 5/ 5/77* 11 16 21 28 7/27/77* 31 38 51 57 9/13/ 77* 51 56 64 70 11/ 8/77* 44 64 74 90 Sauk Lower 5/21/76* 101 110 121 7/14/76* 97 108 114 9/15/76* 76 84 90 11/12/76* 84 88 96 2/17/77* 95 102 109 114 5/ 5/77 90 96 99 i03 6/17/77** 83 89 95 97 7/26/77 100 103 111 116 9/14/77 103 105 116 127 11/ 8/77 95 101 107 113 Cascade 5/21/76* 75 88 109 7 /14/76* 54 72 86 9/15/76* 30 35 41 11/12/76* 45 50 62 5/10/77** 70 73 77 80 6/17 /77** 60 69 73 75 7/25/77** 74 77 80 82 9/16/77** 83 84 86 89 11/10/77** 74 76 79 82 *Only benthic insects sampled on these dates. **Only periphyton sampled on these dates. 72 Table 3.8 Mean monthly turbidity (J.T.U.) at stations on the Skagit, Cascade, and Sauk rivers during 1976. Station Skagit at Skagit at Sauk Month Newhalem Marblemount Cascade Lower June 1.7 3.3 8.3 7.7 July 4.0 5.6 13.0 31.0 August 4.7 4.3 3.7 13.0 September 0.3 0 0.5 15.0 October 0 0 1.0 5.0 November 2.6 2.8 2.0 8.4 December 6.3 9.3 11.3 ll.5 Mean . 2. 8 3.6 5.4 12.7 June-November mean 2.1 2.5 4.4 14.1 ~ ~""'· ~ ~- ~ 73 - Table 3.9 Mean monthly turbidity (J.T.U.) at stations on the Skagit, f""' Cascade, and Sauk rivers during 1977. p~ STATION MONTH Skagit Skagit Sauk Sauk. at at Cascade Upper Lower Newhalem Marblemount January 4.2 4.4 6.4 5.8 '!""" February 5.0 6.7 10.0 6.7 March 3.8 3.7 4.3 4.3 -April 5.3 6.3 7.6 15.0 -May 3.3 3.4 3.2 5.2 June 6.3 5.3 6.7 19.3 -July 2.0 4.7 2.8 20.0 43.8 August 10.0 7.3 9.0 39.5 197.5 September 5.3 5.3 30.0 8.3 30.5 October 4.8 4.2 4.6 8.8 24.0 November 5.0 2.0 3.0 6.0 9.0 Mean 4.9 4.8 8.1 18.1 34.4 June-November 5.6 4.9 10.1 60.7 Mean 74 the Suiattle River. Water from the Suiattle entered the Sauk immediately above the upper sampling station on the opposite side of the river and did not become mixed with Sauk River water until it had flowed past the sampling transect. As a result, comparatively clear upper Sauk River water flowed over the shoreline area of the transect where samples were collected, while frequently turbid Suiattle River water flowed over the unsampled half of the transect. 3.4.2 Periphyton 3.4.2.1 Flow Fluctuation Effects. Under natural flow conditions, most periphyton production in large streams is probably limited primarily to a zone along the shoreline where environmental conditions are suitable for growth and attachment. The width of the zone depends upon the slope of the shore. This zone moves laterally as the average daily flows change through the year. In the Sauk, maximum flows occurring during the winter and summer were followed by periods of low flow. Periphyton present in shallow areas during the high flow periods was exposed and destroyed by desiccation as the flow decreased. However, the average daily flow decreased gradually and should have allowed periphyton to become established in areas farther from the waterline where water depth or velocity did not permit growth under higher flow, resulting in a net movement of the periphyton zone toward midchannel. As average daily flows rise in the spring and fall, the periphyton zone would be expected to move laterally toward the river margins as previously dry areas become wetted, and velocity becomes too high in midstream. Daily flow fluctuations caused by hydroelectric peaking limit the potential area available for colonization by periphyton by reducing.the width of the periphyton zone. Frequent exposure during low flows prevents the establishment of periphyton near the river margins and only areas that &re permanently submerged or infrequently exposed to desiccation for short periods of time may be suitable for colonization. Scouring of the bottom during high flows due to peaking and spilling may reduce the periphyton standing crop in the midchannel areas where current velocity is usually greatest. Stream profiles at the Skagit River transect are shown in Fig. 3.2 along with periphyton sampler locations and maximum and minimum water levels during the first three 6-week colonization periods. Low flows exposed the deepest sampler, at 125 ft from the high-water mark, to desiccation during all three colonization periods, and precluded the collection of data on chlorophyll ~ values under conditions of zero exposure. Since the plexiglass plates were 7.5 inches above the riverbed, it was possible for the plates to be exposed during a low flow while the concrete base of the sampler remained submerged. The sampler nearest the high-water line was exposed at flows below 5,800 cfs. To determine the effects of exposure on periphyton standing crop, the mean chlorophyll content of the two replicate samples from each periphyton sample was plotted against percent exposure. Results from each coloni- zation period are shown separately in Figs. 3.3-3.6. ...... J } ] ---] 9/1/76 TO 10/15/76 10,245 CFS \.. 1600 CFS I '-------------------~--~~200 X J .. 40 41 X 72 10/15/76 TO 11/30/76 10,515 CFS ~'~;:::::::::::::1::49:5::C:F:S::::::::::::::::::::::::~;;~~~t,X~~f~-:x~-------------'~ """""" ' 56 81 87 26 11/30/76 TO 1/12/77 23,140 C FS ~'~;:::::::::::2::l8:::7C:F:S::::::::::::::::::::::~;;;;~--~x~~x~~~¥~.----------;l~ ' I 5 13 24 2 SCALE HORIZONTAl• 11N=50FT VERTICAl• 1 IN= 10FT Fig. 3.2 Stream profiles at the Skagit Lower station showing maximum and minimum water levels during the six-week colonization periods. The percentage of time that each.peri- phyton sampler was exposed to desiccation during the six weeks prior to sampling is given below the sampler location, which is indicated by an X. ,..... a::: LL.J +- LL.J l: LL.J a::: a: ::J t::2l (/) a::: LL.J fl.. 0 l: ........ a: __J __J >-:I: fl.. 0 a::: 0 __J :I: u 76 9/1/76 Ta 10/15/76 1.10 ·70 .so .so .40 .30 .20 Fig. 3. 3 30 40 50 60 PERCENT EXPOSURE 1!1 SKAGIT LOWER C9 SAUK LO 1-1 ER & CASCRD~ 90 100 Chlorophyll a content of periphyton samples collected at the Skagit Lower~ Sauk LQwer,' and Cascade stations in October 1976. - - - - ~ ,..... 0::::: w -1--w l:: w 0::::: a: ::J C3 (J) 0::::: UJ -a... 0 l:: ........ )~ a: __] __] >-I lL 0 0::::: 0 . __] I u 1 .to t.oo .go .so .70 .so .so .40 .30 .20 .to 77 tO/tS/76 TO tl/30/76 tO 20 30 40 50 60 PERCENT EXPOSURE (!] SKAGIT LOWER (!) SRUK LOWER ~ CASCRDE tOO Fig. 3.4 Chlorophyll ~ content of periphyton samples collected at the Skagit L~wer. Sauk Lower, and Cascade stations in November 1976. 78 ~ ' 11/30/76 TO 1/12/77 1.10 1!1 SKAGIT LOWER 1.oo (!) SAUK LOWER .go .& CASCADE ,...... a::: w 1-w .so L: w a::: a: .70 ~ C1J (jJ 0:: .so w (L. ~ CJ I: .so '-' a: ~ _J .40 _J >-::r:: IL -0 .30 a::: 0 _J :r: /f' u ·1 0 0 10 20 40 50 60 70 80 90 PERCENT EXPOSURE Fig. 3~5 Chlorophyll~ content of periphyton samples collected at the ~ Skagit Lower, Sauk Lo'Wer, and Cascade stations in January 1977. '"""' - .... 79 FEBRUARY 1977 -m ~ .eo I ~ ~ .so -a: ~ .40 I .so. ~ .20 .. 10 40 50 60 90 100 PERCENT EXPOSURE Fig. 3.6 Chlorophyll ~ content of periphyton samples collected at the Skagit Lower Station in February 1977. 80 In general there was a trend of increasing chlorophyll a with decreasing exposure to desiccation. This trend is particularly evident in the results from the Skagit River during November 1976 (Fig. 3.4) and February 1977 (Fig. 3.6). It appears that the daily fluctuations, accompanied by daily exposure, reduced periphyton abundance in these areas of the river margins, and that the amount of periphyton present was related to the degree of exposure. 3.4.2.2 Seasonal Variation. It was difficult to compare stations during the period of October 1976 to March 1977 because of the lack of data from unexposed artificial substrate samples in the Skagit and Cascade rivers. The two deepest samplers at the Sauk Station were unexposed during all sampling periods (Table 3.4) and only data from these samplers were graphed, while data from some exposed samplers at the Skagit and Cascade stations were used in Figs. 3.7 and 3.8. Periphyton standing crop on artificial substrates at the Sauk Station was highest in October and decreased to a lower level during the remaining colonization periods (Fig. 3.7). During October 1976, unexposed substrates at the Cascade Station (Fig. 3.8) had much less periphyton than the Sauk substrates, and chlorophyll~ remained low through March. Chlorophyll ~ on highly exposed Skagit River substrates was low through February. Results in February from unexposed Skagit samplers were similar to results from unexposed Sauk River samplers in March. During the period when the periphyton was removed from streambed rocks, flow patterns were roughly similar, and exposure was low at all sampling stations (Table 3.5). Valid comparisons were possible among stations, but it was not valid to compare standing crop in October or November 1976 with standing crop in these months in 1977 because different sampling methods were used. The pattern of seasonal variation in periphyton standing crop was similar at the Sauk Lower (Fig. 3.7) and Cascade (Fig. 3.8) stations during 1977. Standing crop was almost the same at both stations from January through June; higher at the Cascade Station during the summer, and again similar in November. Maximum standing crop was present during the summer at both stations. Periphyton standing crop at the Skagit Lower Station (Fig. 3.7) rose rapidly from May to June, when it reached the maximum value for the year. Standing crop in May and June was much higher than at the other three sites during this time period, but dropped to the same general level as the Sauk and Cascade during the summer. Unlike the Sauk and Cascade, periphyton standing crop at the Skagit Lower Station remained relatively high into November. Periphyton standing crop at the Skagit Upper Station (Fig. 3.8) increased steadily from Hay to November. During spring and early summer, chlorophyll ~ levels were comparable to levels in the Sauk and Cascade. However, standing crop continued to increase into the fall, as standing crop in the two unregulated streams fell sharply. ~. - - 6 5 - - Fig. 3.7 81 SKAGIT LOHER SAUK LOI•JER ----- \ \ \ ' ' \ \ \ ,, ........ __ I I I I l ~ I ' I ' I '" ' ' ' ' ' \ \ \ \ \ \ ' ' \ \ \ ' \ \ \ M J J A S 0 N D J F M A M J J A S 0 N D 1976 MONTH 1977 Periphyton standing crop, as indicated by chlorophyll~ content, at the Skagit Lower and Sauk Lower stations. Two different sampling methods were employed, and results using each method were plotted separately. 82 6 5 SKAGIT UPPER -~ CASCADE ----.. ~ !4 (f.) , ," ' f5 ," ' ' ~3 ' r ' ~ I ' ' ' -I ' a: I I I ' ...J I ' _, I ' ~2 I ' I ' ~ I ' 0 I ' § I ' I ' l: I ' u I ' 1 I ' I ' I ' • I ' ' I ' ' ' I ' '.! ' • ~~------ 0 ____ ,~ M J J A s 0 N D J F t1 A M J J A s 0 N 1976 MONTH 1977 Fig. 3.8 Periphyton standing crop as indicated by chlorophyll~ content of samples collected at the Skagit Upper and Cascade stations. Two different sampling methods were employed in the Cascade River, and results using each method were plotted separately. - - _, ..,., ~ ~ D - .... - - 83 The relatively stable flow in the Skagit contributed to the high periphyton standing crop at the two Skagit River stations during the Hay through November period. Only minor fluctuations occurred during this time span, and the periphyton was able to grow without being affected by desiccation during flow reductions. The variations in flow consisted of slight increases in water level for a few days, which would not have exposed any periphyton, but may have removed some biomass through scouring and high current velocity. High flows occurring 1 week before sampling were probably responsible for the reduction in standing crop observed at the Skagit Lower and Sauk stations in November 1977. On November 1, the water level rose almost 6ft in the Sauk River. Increases in waterlevel of over 4ft and over I 5 ft were recorded at the Skagit at Marblemount and Alma Creek gages, respectively, on the same date. Water level only varied 2.5 ft at Newhalem on November 1. The observed reduction in periphyton standing crop at the Skagit Lower and Sauk stations was not due to sampling in previously exposed areas during the higher water in November. Although the November samples were collected in areas closer to the high-water line (Table 3.7), there was considerable overlap in the sections of the transects sampled in September and November at all stations except the Cascade. More importantly, most locations sampled in November had been unexposed for extremely long periods. All sampling locations at the Skagit Lower Station had not been exposed during 1977 and all locations at the upper station had been submerged since at least July. At the Sauk Lower Station, the shallowest location had been exposed for several days in September and October, but the other three locations had been submerged continuously during 1977. Since most of the areas sampled in the Sauk and Skagit in November had not been exposed prior to sampling, the reduction was attributed to scouring during the high flows. The reduction in Cascade standing crop may have been due to either exposure or scouring. The standing crop at the Skagit Upper Station was higher in November than in September, and was apparently not reduced during the high water. The amount of suspended sediment in the upper part of the river below Gorge Powerhouse may have been lower, resulting in reduced scouring at the Skagit Upper Station. The large amount of suspended sediment in the Sauk River during the summer undoubtedly limited the amount of light reaching the benthic zone and reduced periphyton growth. Standing crop in the Cascade River was higher than in the Sauk during July and September, probably because of the lower turbidity levels in the Cascade. The ranges of chlorophyll~ values at the Skagit Lower, Sauk Lower, and Cascade stations were compared with the ranges in several other rivers (Table 3.10). Ranges for each type of substrate used in this study are given separately, and values are from unexposed substrates only. The artificial substrates were used during fall and winter, when periphyton Table 3.10 Range of chlorophyll~ values in the Skagit, Sauk, and several other North American streams. Chlorophyll ~ Stream 2 Substrate (mg/m ) Logan River, Utah (McConnell and Sigler, 1959) Streambed rocks 140 -1420 Laboratory Stream, Ore. (Mcintire and Phinney, 1965) Streambed rocks 140 -2010 Valley Creek, Minn. (Waters, 1961) Concrete cylinders 9.2 -21.1 Carnation Creek, B.C. (Stockner and Shortreed, 1976) Plexiglass plates 0.9 -2.1 Skagit River, Wash. (October 1976 -February 1977) Plexiglass plates 0.09 -0.15 Skagit River, Wash. (May 1977 -Novembzr 1977) Streambed rocks 0.41 -8.28 Sauk River, Wash. (October 1976 -March 1977) Plexiglass plates 0.01 -1. 05 Sauk River, Wash. (~fuy 1977 -November 1977) Streambed rocks 0.07 -3. 92 Cascade River, 1:Vash. (October 1976 -March 1977) Plexiglass plates 0.07 -0.25 Cascade River, Wash. (May 1977-November 1977) Streambed rocks 0.20 -4·. 35 00 ~ - -' - - 85 growth is probably at its lowest level, due to reduced light. The natural substrates were used during the seasons of peak periphyton growth. Results using plexiglass artificial substrates in the Skagit, Sauk, and Cascade rivers are comparable to the range of values in Carnation Creek, British Columbia (Stockner and Shortreed 1976). Stockner and Shortreed (1976) considered the level of chlorophyll in Carnation Creek to be extremely low, and attributed this low level to extremely low nutrient concentrations and poor light conditions under the forest canopy. There was no forest canopy at the Skagit, Sauk, or Cascade stations, and turbidity was low during 1976 and early 1977. Therefore, one would expect the chlorophyll levels to be higher at thes.e stations. The low values may have resulted from the use of artificial substrates. The smooth plexiglass plates may not have been suitable for the attachment and growth of some species of algae. Considerable growth of filamentous algae was observed on streambed rocks in the Skagit and Cascade rivers in areas where periphyton samplers were placed, and on the concrete bases of the samplers, but comparable growth did not occur on the plexiglass plates. The length of time that the substrates were available for colonization may not have been long enough. The plexiglass slides were held several inches off the bottom in this study and in the Carnation Creek study (Stockner and Shortreed 1976). The higher velocities above the bottom may have inhibited colonization or may have removed periphyton by scouring. The level of chlorophyll ~ on the streambed rocks was much greater than on the plexiglass plates. This difference may be due to differences in substrate or seasonal effects. The maximum value at the Skagit station, collected from natural substrates, approached the minimum value in Valley Creek, Minnesota (Waters 1961). Values from the three rivers examined, even from streambed rocks, were much lower than the m1n1mum value observed in the Logan River, Utah (McConnell and Sigler 1959). 3.4.3 Benthic Insects 3.4.3.1 Flow Fluctuation Effects. Flow fluctuations can have a detrimental effect on benthic insects by dewatering the substrate and also by altering environmetal conditions in submerged areas of the riverbed. During flow reductions, aquatic insects that are not able to move rapidly enough toward midstream or do not drift downstream are left stranded on the dewatered substrate, where mortality through desiccation or freezing may result. Natural seasonal fluctuations in water level also cause dewatering of shoreline substrate. However, the change in water level occurs gradually, allowing most insects to avoid stranding. Changes in velocity during flow fluctuations can also affect the benthic community. I>fany species of aquatic insects have specific current velocity requirements, and velocity over a particular area of the bottom may exceed the range of tolerance during high daily flows, eliminating some species from affected bottom areas. Deeper areas that are never 86 dewatered can also be affected if velocities during high flows are severe enough to cause shifting of the substrate or scouring. Stream profiles at the Skagit River Lower Station showing maximum and minimum water levels during the 2 weeks prior to benthic sampling in 1976 are presented in Figs. 3.9 and 3.10. During the July 1976 sampling period (Fig. 3.9), a small length of the transect was exposed and submerged, and the duration of the dewatering was very short. This flow pattern resulted in high benthic insect densities near the riverbank. The length of the transect exposed and submerged was much greater in May, September, and November, and the duration of exposure near the bank was higher. Consequently, insect densities were low in shallow areas of the transect. The width of the transect was 374 ft, and between 86 and 112 ft of the sampled side of the transect were exposed at minimum flow during the September and November sampling periods. Only 41 ft were exposed during the 2 weeks prior to the July sample. The relationships between percent exposure and benthic insect density and biomass are shown for May, July, September and November 1976 Skagit River samples in Figs. 3.11-3.14. Benthic insect density and biomass were much lower in areas of the Skagit subject to high exposure than in areas subjected to low exposure. A relationship in which density and biomass increase as exposure decreases, was evident. During May (Fig. 3.11) density and biomass increased sharply as the exposure decreased. This pattern was also observed during September (Fig. 3.13). During July (Fig. 3~12), all sample locations were subject to extremely low exposure (0-1 percent) because minimum flows were high during July. November density and biomass were low at all sample locations at the Skagit Lower Station transect (Fig. 3.14) and were associated with high exposure at all locations. It appears that the benthic insect fauna in shoreline areas of the Skagit was reduced as a result of periodic exposure in 1976, and the degree of reduction was related to exposure time. The pattern of increasing benthic invertebrate density with decreasing exposure was identical to the pattern found below other hydroelectric dams by Fisher and LaVoy (1972) and MacPhee and Brusven (1973). The diurnally fluctuating water levels during hydroelectric peaking in the Skagit have prevented the establishment of the productive shoreline benthic community that is present in unregulated streams. Several investigators have found that the shallow areas of streams_ near the shore are more productive than areas near midstream. Needham and Usinger (1956) found that the density of most aquatic insect genera was several times greater in shallow, slower moving water (0.7-3.0 ft/sec) of an unregulated stream than in the deeper, faster moving water (up to 5.3 ft/sec) at midstream. Kennedy (1967) reported that the majority of benthic organisms in Convict Creek, California, preferred depths between 3 and 6 inches and current velocities between 1.0 and 1.2 ft/sec. As depth increased beyond 6 inches, the number of organisms decreased.· The frequent flow fluctuations in the Skagit during periods of hydroelectric peaking reduced - ~. ) l MAY 1976 16,110 C FS 2718 CFS ·: :.,;;-c 1 l I Jt r JULY 1976 ~ SCALE Fig. 3. 9 4910 CFS 30,975 C FS f t t 0 0 HORIZONTAL• 11N=50 FT VERTICAL: liN= 10FT Stream profiles at the Skagit Lower Station. showing l!lmS::i.Bu:ua . .and ?linimtllll water levels during the two weeks prior to benthic insecL sampiing in May and July 1976. The area between the dashed lines is the area of the riverbed that was periodically exposed and submerged. The locations where replicate benthic samples were collected and percent exposure time are indicated by arrows. ~ 11 00 -...J SEPTEMBER 1976 3030 CFS NOVEMBER 1976 ~ 1656 CFS -- SCALE HORIZONTAL: 11N=50 FT VERTICAL : 1 IN = 10 F T 10,2 45 C F S 6440CFS f: ol I I t 22 f 6 t 69 Fig. 3.10 Stream profiles at the Skagit Lower Station showing maximum and rnrrn1mum Jl 33 f t 86 96 water levels during the two weeks prior to benthic insect sampling in September and November 1976. The area between the dashed lines is the area of the riverbed that was periodically exposed and submerged. The locations where replicate benthic samples were collected and percent exposure time are indicated by arrows. ' 1 (X) OJ , . ... J 1500 8 ,....1200 ...... a::: X~ a:::LLI w:t: 1-w LLia::: I: a: w=> a:::OI a:Cf.J =>a::: ow Cf.Jo... a::: a::: Ww a... co (f) I: x:=> a:Z ~>- 1- (f.J ...... (f.J(f.J a:Z x:W oCl 1-4 co 900 600 300 MAY 1976 I I I I BIOMASS \ . I I I I 1... ..... 89 ..... .......... ..... ..... ..... 0~--~--~----~---L--~----~--~----~--~--~ 0 10 20 30 40 50 60 70 80 90 100 PERCENT EXPOSURE Fig. 3Jl Density and biomass of benthic insects at the Skagit Lower Station in May 1976. 90 JULY 1976 1500 ,..... DENSITY 0 0 ,.....1200 -a::: X~ a::::W wr. t-w Wa:::: :I:cr UJ=:l 900 a::::CI CI:(f) =:la:::: ow (f) a... a:::: a::: Ww C... en (I) I: 600 :I:=:l o:::Z €5'-' >-'-"t- (1)1-4 (1)(1) o:::Z r.LL.I oCI 300 1-4 ? BIOMASS lD 0~--J---~----~--~--~----~--~--~----~--~ 0 1 0 20 30 40 50 60 70 80 90 100 PERCENT EXPOSURE Fig. 3.12 Density and biomass of benthic insects at the Skagit Lower Station in July 1976. ~\ ~; ~' ~ ~ ~ - - 1500 8 .-1200 -a::: X~ a::::LLl w:t: 1-w LLla:::: l::a: w 5 900 a:::: (f) a: ::Ja:::: aw (f) a... a::: w a... U') :t: a: ~ ~ U') U') a: :t: 0 ....... CD a::: w CD ~ 600 z ~ I-..... U') z ~ 300 SEPTEMBER 1976 DENSITY \ \ \ \ \ \ BIOMASS \ \ \ ..... ____________ ...._ .... 91 .... ... 0~---~------~---~------~---~------~---~------~---~------~ 0 10 20 30 40 50 60 PERCENT EXPOSURE 70 80 90 100 Fig. 3.13 Density and biomass of benthic insects at the Skagit Lower Station in September 1976. 92 NOVEMBER 1976 1500 -0 0 -1200 -a:: xW I- a:::W LLJJ:: 1--w LLJo:: J::a: L&J:::l 900 o::O a:CJJ :::lo:: OLLJ (QQ... O::a::: IJ.JLLJ a...~ 600 (l):::l x=z a:~ ~>--~--- (f.)-cnCJJ a:Z J::~ 300 0 -DENSITY CD BIOMASS OL---~--~~~~~~~~~------~==~-~-~-~-~ 0 10 20 30 40 50 60 70 80 90 1 00 PERCENT EXPOSURE Fig.3.14 Density and biomass of benthic insects at the Skagit LQwer Station in November 1976. ~I ....,, -· ~· - - 93 benthic standing crop in these potentially highly productive shoreline zones, leaving only the relatively less productive midstream areas unexposed. Although these areas near midstream remained permanently submerged, detrimental effects were still possible due to fluctuating current velocity. Insect density and biomass in the deeper areas of the Skagit near midstream were relatively high during late spring and early summer of 1976, but these insects may have frequently been unavailable to the fish. During periods of high water in the Skagit, salmonid fry may be forced into the frequently exposed areas that contain fewer food organisms by high current velocities in the deeper, relatively food-rich areas. However, insect drift originating in the unexposed areas of the river may provide sufficient food for these fish if there is sufficient mixing action across the width of the stream and the drift rate is high. 3.4.3.2 Seasonal Variation. The pattern of seasonal abundance of benthic insects is shown in Figs. 3.15 and 3.16. The mean of all replicates at all unexposed sample locations, or at the site with the least exposure, on sampling dates at each station is shown in these figures. The number of replicates used to calculate the station mean was therefore variable, and the exact number can be determined by referring to Table 3.6. During 1976, the pattern of seasonal abundance differed among stations. Insect density generally increased from May ~hrough November at· both the Sauk Lower (Fig. 3.15) and Cascade (Fig. 3.16) stations~ All sample locations at these two stations were unexposed during the 2 weeks prior to sampling. The standing crop at the Skagit Lower Station (Fig. 3.15) was similar to the density at the Sauk and Cascade rivers in May of 1976. Mean density at unexposed locations in the Skagit was similar to density in the Sauk in July •. Both the Sauk and Cascade rivers had higher standing crops than the unexposed sample locations in the Skagit during September. Sauk and Cascade standing crops continued to increase into November while Skagit River standing crop decreased. However, the sample location used to compute the station mean was exposed 22 percent prior to sampling, and a valid comparison cannot be made between the Skagit and the other rivers in November. During 1977, benthic insect standing crop was greater in the Skagit than in the Sauk. At the Skagit Lower Station, density was relatively high during February, declined somewhat in May, and then increased through the summer until in reached a maximum value of 11,330 insects/m2 in September (Fig. 3.15). Insect density declined in November, but was still considerably higher than in the unregulated Sauk River. Density at the Skagit Upper Station increased steadily from February to November (Fig. 3.16). The two Skagit River stations were sampled on different days in February when flow conditions were different. As a result, the samples from the upper station were collected in shoreline areas that had been exposed at least 16 percent of the time during the 2 weeks prior to sampling, while samples were taken only in unexposed 12000 10000 ~0000 I ..... 6000 2000 94 SKAGIT L0\4ER SAUK LOWER ----- ' t\ I \ I \ I \ I \ I \ I \ I \ I \ I \ I \ I \ I \ I \ I I I I I , , M J J A S 0 N D J F M •A M J J A S 0 N D 1976 MONTH 1977 Fig, 3 .• 15 Benthic insect standing crop at the Skagit Lower and Sauk Lower sampling stations. - - - - - ,.-..,. I ! ! ~ ,_ ,.... '""" """" - - - 95 12000 SKAGIT UPPER 10000 SAUK UPPER ------- CASCADE-e-.,. .... 0::: ~ 8000 ~ 1U 0::: ~ 6000 (I) ffi £L ~ 0::: LLJ ~ 1\ Ill s 4000 ~ ' \ I \ z ~ / \ I \ ~ I \ \ ~ \ "' \ ~ ~ \ ~ 2000 I \ .............. , \ , ' ,., , ,., , , ___ , 0 M J J A s 0 N D J F M A ~~ J J A s 0 N D 1976 MONTH 1977 Fig. 3.16 Benthic insect standing crop at the Skagit Upper, Sauk Upper, and Cascade sampling stations. 96 areas at the lower station. The difference in exposure time accounts for the disparity in density at the two Skagit stations in February. If samples could have been collected in unexposed zones at the upper station, the density values would have been more comparable. Density at the Sauk Lower Station varied between a low of 519 insects/m2 in May to a high of 2,149/m2 in July (Fig. 3.15). Density at the Sauk Upper Station increased steadily throu~h September 1977, when it reached a maximum value of 4,406 insects/m2 (Fig. 3.16). Density at both of these stations declined in November. The high water on November 1, 1977, was probably responsible for the reduced benthic insect density observed during the November sampling period. Although samples were taken in areas slightly closer to the high-water line in November than in September, the sampling locations had not been exposed for extremely long periods, as was explained in Section 3.4.2~2. Benthic insect standing crop at the Skagit Upper Station, as well as periphyton standing crop, were not reduced when compared with the other stations in November. The amount of suspended inorganic material may have been lower at the Skagit Upper Station, resulting in lower loss of insects from scouring. Standing crop at the Sauk Lower Station was lower during September and November of 1977 than during the same months in 1976. This difference between years may have been due to increased amounts of settled silt and sand in the riverbed in 1977. The accumulation of inorganic sediment in the interstices of the streambed gravel can reduce benthic macroin- vertebrate abundance (Cordone and Kelley 1961, Nuttal 1972, Brusven and Prather 1974). Turbidity was extremely high at the lower station in August (Table 3.9), and a large amount of the suspended sediment must have settled out, possibly degrading the benthic macroinvertebrate habitat. Turbidity levels were lower at the Sauk Upper Station, and benthic insect abundance was higher at this station than at the lower station during September 1977. In contrast to 1976 observations, insect density in 1977 was highest at stations subjected.to regulated flow rather than unregulated flow. Density at the Skagit Lower Station was always hi~her than at the unregulated Sauk River stations. Density at the Skagit Upper Station was greater than at the Sauk stations during summer and fall months. Benthic insect abundance at the Skagit Lower Station during July and September 1977 was 6 to 9 times greater than at unexposed sample locations in July and September of 1976. Near stable flow conditions in the Skagit were probably responsible for the increased standing crop in the summer of 1977. From late April to mid-November, the benthic community in shoreline areas was subjected to flow fluctuations that were no greater than the fluctuations at the unregulated Sauk Lower Station. The degree of fluctuation was even less at the Skagit Upper Station, since it was closer to the Gorge Powerhouse. Under the relatively stable flow regime, losses of insects from stranding during flow reductions were reduced. Changes in bottom velocity during - - , ..... I - - 97 the flow fluctuations were also reduced, and environmental conditions were nearly constant during this time period. Increased seasonal flow constancy due to regulation has had a beneficial effect on benthic standing crop in other rivers, although species diversity was reduced in some cases (Ward 1976a). Apparently increased flow constancy from late April to mid-November-resulted in enhanced standing crop in the Skagit when compared to 1976 results. Seasonal variation of benthic insects at the Skagit Lower and Sauk Lower stations in 1977 was compared with that in two other North American streams (Fig. 3.17). A Surber sampler with 1.024-mm mesh was used for sampling the Provo (Gaufin 1959) and the Kananaskis (Radford and Hartland-Rowe 1971) rivers, which would not ·have captured the earlier instars of some nymphs and many of the mature chironomids. No information was given on depths sampled, but the Surber sampler cannot be used in water over 12 inches deep, and is probably suitable only for depths of about 8 inches or less. The Skagit, Sauk, and Provo rivers had roughly similar patterns of seasonal abundance. Abundance declined from February to May and then increased during the summer. Abundance declined during the fall in the Skagit and Sauk during 1977, probably due to high water in November. There were no similar periods of extremely high water prior to the November 1976 sampling date, and abundance at the Sauk Station increased through the summer and fall, reaching a peak in November. Density in the Skagit was much higher than in the Provo River during most of the year. Although underestimated, Provo River density was consistently greater than Sauk density. The unregulated Provo River was considered an exceptionally rich stream in terms of food grade (Gaufin 1959). Density in the fluctuating, regulated, Kananaskis RiveT was lower than in any of the other rivers. A rich and varied fauna (no quantitative data) was present in the river prior to operation of the dam. Density in smaller tributary stream sampled for comparison with the Kananaskis was usually higher (Radford and Hartland-Rowe 1971). 3.4.3.3 Composition. The composition of the benthic insect community was influenced by exposure during flow fluctuaton. Composition at each of the Skagit sites and in the Sauk and Cascade rivers is shown for each sampling date in 1976 in Tables 3.11-3.14. In general, Diptera (flies) formed a larger portion of the community in the highly exposed areas of the Skagit, while the percentage of Ephemeroptera (mayflies) was lower in these areas. Mayflies were particularly susceptible to stranding and were intolerant to exposure while chironomids (Diptera) and Trichoptera (caddieflies) appeared to be relatively tolerant (Brusven et al. 1974). It appears that most of the mayflies were eliminated from areas of the Skagit with high exposure, while the more tolerant chironomids were able to remain. The percent composition at the Sauk and Cascade sample locations (all with no exposure) was most similar to composition at Skagit locations that were not exposed. Mayflies were always more abundant than dipterans in 12000 10000 ~ 8000 ~ I .., 6000 2000 Fig. 3.17 98 PROVO R ,-... ------, I SKAGIT R , """ ·I I I I I J I , I , ,.----,_• ........ ...... \ ~~ .... -............ ...... \ ~ ,.,. ......... ......... ' ~~ ,... ... ...... ...... .. ,. ...... ... ,. .. ........... " M 1.J"-·-•. · J s D --. MONTH Seasonal variation in benthic macroinvertebrate density in the Skagit, Sauk, and two other rivers in western North America. The Provo River, Utah (Gaufin, 1959), and the Sauk are unregulated streams. The Skagit River and the Kananaskis River, Alberta (Radford and Hartland- Rowe, 19 71) , are regulated streams. - - ~. .~ - - ~. - - , .... - Table 3.11 Order Ephemeroptera Plecoptera Trichoptera Diptera Coleoptera 99 Percent composition of benthic insects at sampling stations during May 1976. Composition is presented separately for each sample location at the Skagit Lower Station. Percent exposure during the two weeks prior to sampling is also given for each location at the Skagit Station. STATION Ska~~t Lower. Sauk 35% 21% 16% Lower Cascade 43 54 72 53 83 24 22 18 16 11 8 4 1 3 2 25 20 9 28 4 0 0 <1 0 0 Table 3.12 Percent composition of benthic insects at sampling stations during July 1976. Composition is presented separately for each sample location at the Skagit Lower Station. Percent exposure during the two weeks prior to sampling is also given for each location at the Skagit Station. STATION Skagit .Lower Sauk Order I% 0% ·tower Cascade Ephemeroptera 16 32 47 83 Plecoptera 13 11 19 8 Trichoptera 14 9 3 1 Diptera 57 48 31 8 Coleoptera <1 <1 <1 <1 100 Table 3.13 Percent composition of benthic insects at sampling stations during September 1976. Composition is presented separately for each sample location at the Skagit Lower Station. Per- cent exposure during the two weeks prior to sampling is also given for each location at the Skagit Station. STATION Skagit Lower Sauk Order 40% 33% 6% 0'0 '.Lower Cascade Ephemeroptera 0 3 4 37 43 52 Plecoptera 7 18 25 12 8 15 Trichoptera 1 5 3 7 12 7 Diptera 92 74 67 44 37 26 Coleoptera 0 0 1 0 0 0 Table 3.14 Percent composition of benthic insects at sampling stations during November 1976. Composition is presented separately for each sample location at the Skagit Lower Station. Per- cent exposure during the two weeks prior to sampling is also given for each location at the Skagit Station. STATION Skagit .. Lower Sauk Order 96% 86% 69% 22% ·Lower Cascade Ephemeroptera 4 4 14 32 54 55 Plecopt!i!ra 5 1 5 13 24 31 Trichoptera 3 1 4 4 10 6 Diptera 88 94 77 51 12 8 Coleoptera 0 0 0 <1 0 <1 ""'!J111 .-~ -· ~' ""'' ~, 101 the Sauk and Cascade rivers, while dipterans were usually several times more abundant than mayflies at the exposed Skagit River sampling locations. An annual pattern of alternating dominance of Ephemeroptera and Diptera (mainly Chironomidae) was observed at the Skagit Upper and Lower stations, which had almost identical compositions in 1977 (Figs. 3.18 and 3.19). This pattern was evident, but less pronounced at the Sauk Lower Station (Fig. 3.20) and Cascade Station (Fig. 3.21). Ephemeropterans dominated the insect communities at the Skagit and Sauk sites during February and May 1977. During July, the numbers of Diptera collected increased as most of the chironomids became large enough to be retained by the sampling net. Many of the mayfly nymphs that were present in February and May emerged, and the Diptera now comprised the largest proportion of the insect community. The dominance shifted again to the Ephemeroptera in the late summer and fall after many of the dipterans had emerged and the progeny of the mayflies that emerged in the spring were retained by the sampler. Seasonal variation was less obvious at the Sauk Upper Station (Fig. 3.22). The Diptera reached a peak in July at this station, but never formed more than 17 percent of the total insect community. The community was composed primarily of Ephemeroptera (62-78 percent) throughout the year. The proportion of Plecoptera (stoneflies) was greater at the Sauk Upper Station during February and May than at the other stations. 3.4.4 Experimental Studies 3.4.4.1 Flow Fluctuation E~periments. The effects of the experimental flow fluctuations were determined by comparing postfluctuation density and composition in the experimental and control channels (Table 3.15). Since environmental conditions, except for flow pattern, were identical ,in both channels, any differences in postfluctuation density and composition should have been due to the different flow regimes. Density in the control channel at the conclusion of the experiments was always slightly less than prefluctuation density because of normal losses from drift, emergence, natural mortality, and other factors during the experiment. Approximately equal numbers of insects were present in both channels at the start of the experiments. Prefluctuation density in the experimental and control channels was compared using a paired t-test after logarithmic transformation of the data. Density data collected prior to four flow fluctuation experiments conducted in 1976 and 1977 were used. No significant difference between channels was detected. Postfluctuation benthic insect density was lower in the experimental channel than in the control channel in both types of flow fluctuation experiment (Table 3.15). After 7 days of periodic exposure, benthic insect density in the fluctuating experimental channel was only one-third of that in the nonfluctuating control channel. When the number of insects ._ z LL..J u a::: lLJ 0.. 102 11111111 EPHEMEROPTERA D TRICHOPTERA ~ COLEOPTERA 100 90 80 70 60 50 40 30 M J J A S 0 N D J F M A M J J A S 0 N D 1976 MONTH 1977 Fig. 3.18 Percent composition of benthic insects collected at the Skagit Upper Station. - - - - 1-z -LLJ u 0::: LLJ a... - - 100 90 80 70 60 50 40 30 20 10 0 103 11111111 EPHEMEROPTERA D TRICHOPTERA :::::::::::::: mlll~lllllll PLECOP TERA ~ COLEOPTER~ II u M J J A S 0 N D J F M A M J J A S 0 N D 1976 MONTH . 1977 Fig. 3.19 Percent composition of benthic insects collected at the Skagit Lower Station~ I-z LLJ u 0::: LLJ ~ 104 11111111 EPHEMEROPTERR . D TRICHOPTERR ~ COLEOPTERA 100 90 80 70 60 50 40 30 20 10 0 Fig. 3.20 Percent composition of benthic insects collected at the Sauk Lower Station. - - -1-z 100 90 80 70 60 105 11111111 EPHEMEROPTERA D TRICHOPTERA ~ COLEOPTERA llll~lllll~ll1 PLECOPTERA ::!:iiilt~:~~'i 0 I PTERA ~ 50 0::: w a... 40 30 20 10 M J J A S 0 N D J F M A M J J A S 0 N 0 1976 MONTH 1977 Fig. 3.21 Percent composition of benthic insects collected at the Cascade River Station. 1-z lU u 0::: lU ll.. lOOr 90 80 70 60 50 40 30 20 10 ~ 0 M 106 11111111 EPHEMEROPTERA D TRICHOPTERA ll~~ll~~ PLECOPTERA ?f: :: : }} :' J J A s 0 N D J F M A M 1976 MONTH J ~ COLEOPTERA J A S 0 N D 1977 Fig. 3. 22 Percent composition of benthic insects collected at the Sauk Upper Station. - - 107 Table 3.15 M~an number of insects per substrate tray in experimental and control artificial stream channels before and after experimental flow fluctuation. Experimental Flow Pattern Periodic exposure for one week 48-hr continuous exposure Pre-fluctuation 251 536 Post-fluctuation Experimental Control 64 194 378 482 108 per substrate tray was compared between channels in a paired t-test, the difference between channels was statistically significant at the .01 level. Following 48 hr of continuous exposure, the density in the experimental channel was 22 percent lower than in the control channel. However, this difference was not statistically significant. These data indicate that periodic exposure over a 1-week period can significantly reduce benthic insect density. The level of exposure to desiccation in the experimental channel during the 2 weeks prior to sampling was only 30 percent. Flow reductions of similar frequency and duration in the Skagit probably reduced benthic insect density in shaded shoreline areas by a similar amount, either through mortality of stranded insects or drift losses. The 48 hr of continuous exposure did not reduce density as much as 1 week of periodic exposure. In the Skagit, shoreline zones that were continuously submerged or exposed periodically during the week, may have been exposed continously for 48 hr on weekends. This type of experiment was intended to duplicate the weekend flow conditions in the Skagit. A loss of 22 percent of the insects from a particular area of the riverbed would be a sizeable reduction in the amount of food available to the fish. The effect would be even greater if the same area were exposed for 48 hr on several consecutive weekends. The number of surviving insects in the experimental channel may have been overestimated by the inclusion of dead insects. Due to cool and moist conditions on the exposed substrate trays in the experimental chann~l, insects dying from exposure to air would not have been decomposed or desiccated after only 48 hr. After preservation in alcohol, these dead insects would have been indistinguishable from insects that were alive at the end of the experiment and would have been included in the count of inse·cts remaining after 48 hr. Thus, the actual reduction in density was probably greater than 22 percent. The observed 22 percent density reduction was most likely due only to the loss of drifting· insects during initial dewatering. During the periodic exposure experiments, any insects killed during exposure would have been washed out of the channel when the substrate was resubmerged. Both types of experimental flow pattern changed benthic insect community composition. The percentage of Ephemeroptera and Plecoptera was lower in the experimental channel than in the control channel after 1 week of periodic exposure (Table 3.16) and after 48 hr of continuous exposure (Table 3.17). The percentage of Diptera was greater in the experimental channel than in the control under both flow patterns. During both flow reduction and increased flow, Ephemeroptera comprised 56-57 percent of the drift, while Diptera comprised 31-36 percent (Table 3.18). In contrast, the substrate trays contained only 15 percent Ephemeroptera and 73 percent Diptera prior to fluctuation (Table 3.16). The different proportions of Ephemeroptera and Diptera in the drift and on the bottom of the channel indicate that the Ephemeroptera had a greater propensity to drift during flow fluctuations than Diptera. ,...., - - - - -· - - - 109 Table 3.17 Percent composition of benthic insects in experimental and. control artificial stream channels before and after 48 hr of continuous exposure. Post-fluctuation Order Pre-fluctuation Experimental Control Ephemeroptera 11 10 13 Plecoptera 4 5 7 Trichoptera 1 <1 1 Diptera 84 85 79 Coleoptera 0 0 0 110 Table 3.18 Percent composition of drifting aquatic insects in the experimental artificial stream channel during dewatering and rising water and in the control channel during the same time period. Flow Pettern Rising Order Dewatering water Control Ephemeroptera 56 57 49 Plecoptera 8 12 11 Trichoptera <1 <1 1 Diptera 36 31 39 Coleoptera <1 0 0 ~ - - - ·- - - - - 111 Apparently the density of Ephemeroptera was reduced by drift during the fluctuations at a greater rate than dipteran density, resulting in the observed postfluctuation change in community structure. Differences in the ability to survive exposure to air on the dewatered substrate also could have accounted for the observed changes in percent composition. Chironomids were relatively tolerant of desiccation on dewatered streambed substrates under cool temperatures, while mayflies were the most sensitive insect order (Brusven et al. 1974). The density of the Ephemeroptera would be expected to decrease at a higher rate · through desiccation mortality than dipteran density. 3.4.4.2 Stranding Avoidance. Benthic insects that are unable to avoid stranding during flow reductions and are left on the exposed surface of the riverbed may be killed by desiccation or freezing. Insects may avoid stranding by: 1) drifting; 2) migrating with the receding water; 3) migrating from exposed areas to submerged areas; or by 4) burrowing into wet substrate and waiting for the water level to return. The numbers of insects that avoided stranding by the first three methods were recorded during flow reductions in the artificial stream. The interstices in the substrate in the bottom of the t·rays were too small to allow any deep burrowing by the species tested. There were pronounced differences among the three species tested in ability to avoid stranding (Table 3.19). Only 65 percent of the mayfly nymphs (Ephemerella tibialis) were able to escape stranding, primarily by drifting downstream. Almost all of the stonefly nymphs (Acroneuria pacifica) escaped stranding, mainly by moving to the submerged half of the channel. A total of 96 percent of the caddis larvae (Dicosmoecus sp.) avoided stranding, primarily by drifting. Both the stonefly and caddis species tested were able to move several centimeters over dewatered substrated to enter the flowing water. Once exposed, the mayfly nymphs did not move more than a centimeter on the exposed substrate. The results of the stranding avoidance experiments indicate that mayfly nymphs (Ephemeroptera) are much more likely to become stranded d,uring flow reductions than large stonefly (Plecoptera) nymphs and caddis (Trichoptera) larvae. A reduction in water level at a rate of more than 0.7 ft/hr, the rate used in the experiments, would probably result in a higher rate of stranding for all three species. Stranding would probably be more severe on gently sloping shoreline areas than on steep riverbanks. 3.4.4.3 Desiccation Survival. The ability to survive desiccation on dewatered substrates varied among the three species tested (Table 3.20). Dicosmoecus sp., a case-bearing caddis larva, was the most resistant and survived with no mortality on both dry and damp substrates. All Acroneuria pacifica nymphs survi~ed on the damp substrate, but 64 -percent died on the dry substrate. Ephemerella tibialis was the least resistant species and had a high mortality rate on both substrates. 112 Table 3.19 Percentage of aquatic insect larvae stranded and not stranded during experimental flow reductions. The not stranded category includes insects that avoided stranding by moving to the submerged half of the channel or drifting downstream. Not Stranded Species Stranded Total Submerged Drift EphemeroeZZa tibialis 35 65 23 42 Acrooneuria pacifica 1 99 63 36 Dicosmoecus sp. 4 96 22 74 Table 3. 20 Percent mortality of aquatic insect larvae exposed to desiccation for 24 hr on dry and damp substrates. Dry Damp Maximum Air Species Control Temperature Substrate Substrate (OC) EphemeroeZZa tibialis 100 84 2 20 Acrooneuroia pacifica 64 0 0 20 Dicosmoecus sp. 0 0 0 14 - .... - - """ -· - 113 The damp substrate was intended to simulate conditions in shaded areas of the dewatered shoreline areas, or areas dewatered at night or during rain. Conditions on the dry substrate resembled those on areas exposed to sunlight. The caddis species, Dicosmoecus sp., had a sand grain case which probably enabled it to survive desiccation with no mortality. Other species with cases would also be expected to have high survival rates on dewatered substrates. Most stonefly species, including Acroneuria pacifica, crawl out of the water to emerge and can survive short periods out of the water as nymphs. Therefore one would expect them to be more resistant than mayfly nymphs which usually emerge directly from the surface of the water. The desiccation survival experiments, as well as the stranding avoidance experiments, indicate that the mayflies are particularly vulnerable to flow fluctuations. Flow fluctuations in the Skagit probably reduced the mayfly populations at a greater rate than stonefly and caddis populations, causing changes in community structure. 114 - - - - - - 115 4.0 PLA}TKTON DRIFT 4.1 Introduction In 1975 and 1976, examination of salmonid fry'stomachs from the Skagit River showed that salmon and steelhead fry were using zooplankton released from the system of Seattle City Light (SCL) hydropower reservoirs (Sec. 8.0). Contribution of zooplankton to total numbers of food items in 1976 ranged from 26 percent in chinook fry to 0 percent in chum fry. Ross Lake zooplankton had been studied previously (SCL 1973), but little was known about zooplankton abundance in the river. Some sampling of zooplankton abundance and vertical stratification was done in 1973 and 1974 in Gorge and Diablo reservoirs. They generally had lower plankton densities than those of Ross Lake (Burgner 1977). Low plankton standing crop values of some lakes and reservoirs have been attributed to rapid water exchange rates (Brook and Woodward 1956, Tonolli 1955, Axelson 1961, Johnson 1964, Rodhe 1964, and Cowell 1967). Brook and Woodward (1956) found in small Scottish lakes that there was no significant development of zooplankton unless the average water retention time was greater than 18 days. Johnson (1964) found that plankton production was greatly depressed if the mean flushing time of a lake was less than 15 days. Some reservoirs have been observed to receive plankton in discharges from other reservoirs (Tonolli 1955, Cushing 1963, and Johnson 1964), some as far as 80 km upstream (Cowell 1967). Increased abundance of stream benthos immediately below lake outlets releasing zooplankton 'has been reported (Briggs 1948, Cushing 1963, Armitage and Capper 1976). It has been suggested that production of filter feeding macroinvertebrates is enhanced by plankton drift and, even if not fed upon directly, plankton could be strained out by aquatic vegetation and produce nutrient rich detritus (Gibson and Galbraith 1975). Malick (1977) found low drifting detritus densities below a dam on the Cedar River but high densities of filter feeding insects. The reservoir apparently acted as a sink for large particles of detritus but contributed limnoplankton--a higher quality food--to the river downstream. Ward (1975), however, found the hypolimnion releases of hydropower reservoir in Colorado contained so little suspended material that it was actually detrimental to the filter feeding community. Most of these investigators found a rapid decrease in zooplankton density below the lake. Turbulence, abrasion on rocks, and filtering by vegetation and macroinvertebrates are cited as probable causes of this decrease (Chandler 1937). As for effects on fish, Gibson and Galbraith (1975) found that the salmonid biomass was much higher closer to the outlet of a lake. 116 Studies were initiated in April 1977, on the Skagit River and the SCL reservoirs to: I. Discover the fate of crustacean zooplankton passing through the dams and the reservoirs. 2. Determine the availability of plankton to salmonid fry throughout the year and at different distances down the river. 4.2 Study Stations The study stations for the plankton drift samples are shown in Fig. 4.1. The Ross Tailrace Station was upstream from the footbridge below Ross Dam. It was generally flowing and unstratified except for the period June through August 1977 when there was little inflow provided by generation at Ross Powerhouse. The Diablo Forebay Station was at the log boom opposite the intake near the right bank. The reservoir was over 125 ft deep there. The power tunnel intake extends from 105 to 125 ft below the full pool elevation. In 1974, measurements of secchi depths showed that Diablo Reservoir was more turbid than Ross Lake during comparable periods due to seasonal inflows of glacial water from Thunder Creek. The retention time based on long-term average annual discharge was about 11 days (Burgner 1977). In 1977, Diablo Reservoir was thermally stratified from about May to October (Table 2.5) but remained well oxygenated to the bottom. The thermocline was 25 to 40 ft deep. The Diablo Tailrace Station was below Diablo Powerhouse and above Stetattle Creek. The current was generally flowing faster than 2 ft/sec. The Gorge Forebay Station was at the log boom behind Gorge Darn. Depth at this station was about 90 ft. The power tunnel-intakes extend from 60 to 80 ft below the full pool elevation. Turbidity from Thunder Creek caused seasonally high turbidity in this reservoir as well. Retention time for this reservoir based on long-term average annual discharge was about one day (Burgner 1977) and stratification was, at most, slight in 1977. The County Line Station was near the Whatcom-Skagit County line on the Skagit River at about river mile (RM) 89.2, about 4 mi below 'Gorge Powerhouse. This site was selected rather than one closer to Gorge Dam because it was safely accessible and had been used previously for salmonid fry collections for condition and food habits determinations. The Talc Mine Station was on the Skagit River at approximately R}1 84.3, in the neighborhood of the proposed Copper Creek Dam Site. The Marblemount Station was just below the Marblemount Bridge that crosses the Skagit at about RH 78.3. It was above the mouth of the Cascade River. - .... - - 0 I 1 1 2 3 4 I I l I Scale, ~in.~ I mi. 1 l j Ross Diablo Forebay Stat1on Diablo Tailrace County Line Station Talc Mine Station Fig. 4.1 Plankton drift sampling stations, 1977. ] 118 The Concrete Station was just above the community of Concrete and the mouth of the Baker River at about RM 56.7. Turbidity was often extremely high at this station due to inflows from the Sauk River. 4.3 Materials and Methods The sampling apparatus was a Homelite centrifugal water pump, powered by a 5-hp Briggs and Straton engine. The pump was used to draw water from the lake or river, pump it through a brass water meter, and then into a stainless steel cylinder where the water upwelled and then fell of its own weight through a 73-~ aperture plankton net which retained the sample. A volumetric sample could thus be taken at a specified depth in running or standing water. This was used aboard a SCL tug or a Wooldridge river sled boat. At the forebay stations, a 70-ft long, 2-inch I.D. non-collapsible hose was used to obtain a sample near the level of the power tunnel intakes. A dull steel funnel pointed downward on the end of this hose. Some drifting during sampling was encouraged so that new areas would be swept by the plankton pump. At the tailrace stations, samples were taken approximately midway between surface and bottom. At the river stations, a shorter 2-inch diameter hose was used and samples were taken near the surface from a boat holding station in the current. On the end of this hose was a squat 3.5-inch long and 6-inch wide cylinder, with sides made of coarse screening with 0.4-inch apertures. From 100 to 300 gal of water were filtered to obtain a sample, depending on the amount of sediment or organisms present. The net was then thoroughly rinsed down with water and the contents were preserved in 10 percent unbuffered formalin. Two samples were generally taken at the same time and site. In October, a test for differences between the drift sampled in midstream and the drift inshore in rearing areas of juvenile salmonids was conducted. At the stations below Gorge Dam, sample 1 was taken in mid-channel as usual, while sample 2 was taken as far inshore as practical without including much bottom material. Samples were examined-under a binocular microscope and cont~ents enumerated. Some samples were stained with rose bengal <= 100 mg/liter) to make the organic material more visible. The individuals counted as whole organisms could have less than mortal injuries such as two or three appendages missing. "Parts" were defined as more than half an organism damaged more extensively than a couple of appendages missing. It was assumed that by this method an individual organism would be counted only once and an inflated estimate of the density of organisms would be prevented. After counting, the samples were individually retained in 5 percent unbuffered formalin. The average retention period for the reservoirs was calculated by dividing the full pool storage of the reservoirs--89,880 acre-ft for Diablo and 9,758 acre-ft for Gorge--by the daily discharge averaged over a - - - - - - - - 119 month converted to acre-ft. Diablo and Gorge reservoir levels are not drawn down annually like Ross Reservoir (Burgner 1977), so full pool storage of the two smaller reservoirs approximates their volume throughout the year. 4.4 Results and Discussion The results from plankton pump samples from April through December 1977 are presented by month in Tables 4.1 through 4.9, respectively, standardized to numbers of organisms/m3 and rounded to the nearest integer. Since most samples were made by straining 300 gal and there are 264 gal/m3, most sample counts were reduced slightly by multiplying by 264/300. Similarity between replicates was often poor. Larger sample volumes would have been desirable in many cases. In other cases, sediment and drifting algae made it impracticable to pass larger samples through the net. Daphnia appear to be the most fragile of the crustacean zooplankton. Often more than half of the Daphnia in a sample were in parts. Certainly, most of these were broken up by the sampling method. In the reservoir forebay environment, there should be few damaged before sampling. The Clarke-Bumpus net (replicate 3, Table 4.6) damaged much less than the plankton pump. However, as Ward (1975) found in hydropower releases in a Colorado river, the frail carapaces of Daphnia fail to persist for long in the river compared to smaller, more compact zooplankton like Bosmina and Diaptomus nauplii. In September 1977, avoidance of the sampling gear by strongly swimming zooplankters was assessed. A Clarke-Bumpus net, a volumetric plankton sampler, was towed at the same depth that the plankton pump sampled. In both Gorge and Diablo reservoirs, the Clarke-Bumpus net (replicate 3, Table 4.6) sampled higher numbers of organisms/m3 of Daphnia, and lower numbers of organisms/m3 of Diaptomus parts, Daphnia parts, and unbroken Bosmina than the plankton pump. However, the numbers of organisms/m3 yielded by the Clarke-Bumpus net cannot be considered to be without bias. Any type of plankton sampler has some selectivity (Edmondson and Winberg 1971). It may appear from comparing zooplankton densities at Ross Tailrace (Table 4.3) to densities at Diablo Forebay (Table 4.5) that Diaptornus, nauplii, and Daphnia densities decrease during passage through Diablo Lake. However, for the period from June through September, mean daily flow at Ross Darn was only about 400 cfs (Table 4.10). Probably little zooplankton was contributed by Ross Lake during this period because of the low discharge relative to volume of Diablo Lake. Ross Tailrace became a calm and warm arm of Diablo Lake and apparently supported much higher densities of Daphnia and Diaptomus in June, July, and August than the Diablo Forebay Station. Bosmina counts were down at Ross Tailrace during this period, possibly because they thrive better in cooler water. When generation near a normal load was resumed at Ross Darn in October 1977, Table 4.1 Numbers of organisms/m 3 from plankton samples~ April 28-29, 1977. pump Sample Volume Diaptomus Daphnia Bosmina Harpac-Cyclop-Chironomid Plecoptera Ephemeroptera Site replicate (gal.) Diaptomus parts Naup-111 Daphnia parts Bo6mina parts Chydorids ticoida aida larvae nymphs nymphs Ross T.R. 200 30 3 48 15 13 2& 0 0 1 0 0 0 0 6 0 0 88 0 132 220 0 0 0 0 0 0 0 Diahln F.B. 1 200 99 5 41 7 8 79 0 0 1 0 0 0 0 200 100 5 40 0 3 33 0 0 3 3 0 0 0 Diablo T.R. 1 200 53 0 36 12 18 41 0 0 4 0 0 0 2 200 40 4 37 12 18 28 0 0 0 1 0 0 Gorge F.B. 200 22 0 11 9 16 36 3 0 4 0 0 ,_. 2 24 11 0 0 33 0 33 0 0 0 0 11 0 0 tv 0 County Line 200 13 3 33 3 16 25 0 0 0 0 0 0 0 200 13 0 40 3 22 66 3 5 3 3 0 4 0 Talc Mine 1 200 5 0 4 0 1 21 0 1 0 0 5 0 0 2 200 8 0 4 1 0 16 0 0 0 0 0 0 0 Marblemount 1 200 4 0 13 0 0 0 0 0 0 0 0 0 0 2 200 3 26 0 1 11 0 0 5 0 9 0 3 Concrete 200 0 0 0 0 0 0 o" 0 1 0 0 0 1 3 0 0 0 0 0 0 0 0 0 0 0 0 0 ) ) 1 J Table 4.2 Numbers of organisms/m 3 from plankton samples, May 23-24, 1977. pump Sample Vol\lllle Diaptomus Daphnia Bosmina Harpac-Cyclop-Chironomid Plecoptera Ephemeroptera Site replicate (gal.) DiaptoiiTUB part a Nauplii Daphnia parts Bosmina parts Chydorids ticoids oids larvae nymphs nymphs Ross T.R. 1 300 131 1 128 43 43 1903 l 0 0 0 1 0 9 2 300 92 0 236 35 33 1570 0 0 0 0 1 0 0 Diablo F .B. 1 300 782 5 560 206 363 1045 3 0 0 5 0 0 0 2 300 801 0 459 237 331 1117 0 0 0 4 2 0 0 Diablo T. R. 1 300 25 0 33 1 3 108 2 0 1 0 0 0 0 2 300 34 2 53 0 3 107 3 0 1 2 2 0 0 Gorge F.B. 1 300 25 0 48 4 2 182 2 0 3 4 2 3 0 2 300 44 1 64 1 4 171 4 0 3 3 3 1 0 ..... tv County Line 300 83 0 147 28 34 295 0 2 1 0 4 4 0 ..... 300 90 4 158 7 13 319 4 0 2 0 4 2 18 Talc Mine 1 300 21 2 69 3 3 288 4 0 4 0 4 3 9 2 300 12 0 19 1 1 292 0 0 4 0 11 4 0 Marblemount 1 300 4 1 41 0 2 70 0 0 4 0 6 6 9 2 300 4 1 20 1 1 32 3 0 2 0 0 2 0 Concrete 1 300 0 0 2 0 0 7 0 0 0 0 4 1 18 2 300 1 0 0 l 2 7 0 0 1 4 8 4 9 Table 4.3 Numbers of organisms/m 3 from plankton samples, June 23-24, 1977. pump Sample Volume DiaptomuB Daphnia Boamina Harpac-Cyclop-Chironomid Plecoptera Ephemeroptera Site replicate (gal.) l)iaptomus parts Nauplii Daphnia parts Bosmina parts Chydorids ticoids aids larvae nymphs nymphs Ross T.R. 1 300 10966 0 6476 1910 5379 13 0 0 0 0 0 0 0 2 '300 16140 0 7304 1662 4014 2 0 0 0 0 1 0 0 Diablo F.B. 1 300 7& 0 280 49 148 235 0 0 2 0 1 2 0 2 300 86 0 461 74 122 209 0 0 0 2 0 0 0 Diablo T.R. 1 300 47 0 72 5 41 160 0 0 0 0 3 4 0 2 300 30 0 244 2 48 119 0 2 2 2 7 4 0 Gorge F.B. 1 300 26 0 57 3 67 119 0 0 3 0 0 9 1 ....... 2 300 14 1 163 4 12 164 0 0 0 0 1 9 5 N N County Line 1 300 6 0 59 4 4 323 0 0 3 0 32 18 2 2 300 7 0 33 3 14 249 0 1 0 0 25 7 2 Talc Mine 1 300 2 0 9 0 4 158 0 1 2 0 20 4 3 2 300 2 0 21 0 4 198 0 0 0 0 30 4 7 Marblemount 1 300 2 0 26 1 5 67 0 0 5 0 0 0 1 2 300 0 0 6 1 1 91 0 0 1 0 20 4 1 Col)crete 1 300 1 0 6 0 6 5 0 1 3 0 32 3 1 2 300 0 0 0 0 2 10 0 1 0 0 22 0 0 l -l Table 4.4 Numbers of organisms/m 3 from plankton samples, July 27-28, 1977. PUIIIp Sample Volume Diaptormm Daphnia Boomina Harpac-Cyclop-Chir'onomid Plecoptera Ephemeroptara Site replicate (gal.) Diaptormm parts Nauplii Daphnia parts Bosmina parts Chydorids ticoids oids larvae nymphs nymphs Ross T. R. 1 200 2226 0 421 99 28 20 0 0 1 0 0 0 0 2 200 2657 0 821 132 .· 40 11 0 1 0 0 0 0 0 Diablo F. 8. 1 300 27 0 57 18 14 87 0 0 0 0 0 0 0 2 300 40 0 134 19 25 53 0 0 3 1 0 0 0 Diablo T. R. 1 300 16 0 58 0 1 11 0 0 0 1 1 0 0 2 300 18 0 101 5 6 42 0 0 0 0 0 0 0 Gorge F .B. 1 300 21 0 70 4 2 37 0 2 2 0 0 12 0 .. ...... 2 300 27 0 116 5 1 40 0 2 2 0 0 8 0 .. N w County Line 1 300 1 0 2 0 1 9 0 0 0 0 172 37 2 2 300 2 0 0 0 1 4 0 0 0 0 261 38 2 Talc Mine 1 300 4 0 11 2 0 38 0 1 0 1 88 29 1 2 300 4 0 12 1 1 55 0 1 4 1 54 30 3 Marblemount 1 300 1 0 1 0 0 7 0 0 0 0 12 17 1 2 300 3 0 3 0 1 21 0 0 0 2 42 69 6 Concrete 1 300 0 0 2 0 2 4 0 0 0 1 73 11 4 2 300 0 0 0 0 0 0 0 0 1 0 81 26 0 Table 4.5 Numbers of organisms/m 3 from plankton samples, August 23-24, 1977. pump Sample Volume Diaptomus Daphnia BoGmina Harpac-Cyc:lop-Chironomid Plecoptera Ephemeroptua Site replicate (gal.) Diaptomun parts Nauplii Daphnia parts Bosmina parts Chydorids ticoids oida larvae nymphs nymphs Ross T.R. 1 100 2167 42 496 37 24 79 0 3 0 32 0 0 J 2 100 2410 40 950 48 16 53 0 3 0 129 0 0 0 Diablo F.B. 1. 300 92 0 457 22 23 4 0 0 1 0 0 0 2 300 95 0 450 6 25 2 0 0 0 1 1 0 1 Diablo T.R. 1 300 36 0 154 4 12 2 0 1 4 3 4 8 1 2 300 46 0 122 6 10 6 0 1 4 7 7 1 Gorge F.B. 1 300 26 0 176 9 2 3 0 8 3 4 7 6 2 ...... 2 300 23 0 171 2 4 2 0 3 6 5 11 6 1 N 4:- County Line 1 300 6 0 77 0 0 1 0 4 7 2 936 1 125 2 300 3 0 13 0 0 0 0 5 e 0 838 4 99 Talc Mine 1 300 7 0 12 1 0 2 0 7 4 1 314 1 42 2 300 4 0 62 0 1 5 0 2 8 5 327 47 16 Marblemount 1 300 1 0 ·n 0 1 3 0 1 4 0 290 73 7 2 300 1 0 18 0 2 6 0 0 1 0 202 42 4 Concrete 1 100 0 3 3 0 0 0 0 3 18 5 504 0 61 2 100 0 0 3 0 0 3 0 3 21 0 354 0 37 } Table 4.6 Numbers of organisms/m. 3 fro• plankton samples, September 20-21, 1977. pU111p Sample Volume Diaptomus Daphnia Bosmina Harpac-Cyclop-Chironomid Plecoptera l!phemeroptera Site replicate (gal.) Diaptomus parts Nauplii Daphnia parts Bosmina parts Chydorids ticoids aids larvae nymphs nymphs Ross T. R. 1 200 228 17 103 4 7 203 29 0 0 8 0 0 0 2 200 218 11 59 1 11 234 36 1 0 12 3 0 0 Diablo F.B. 1 300 31 9 84 5 21 11 1 0 0 1 0 0 0 2 300 57 1 57 24 22 10 0 1 0 0 0 0 0 3 263 27 0 62 48 1 8 2 0 0 .2 0 0 0 Diablo T.R. 1 300 31 4 13 8 5 3 0 1 0 0 0 0 1 2 300 35 0 27 9 12 4 0 1 1 0 9 0 0 Gorge F.B. 1 350 28 0 21 2 4 2 0 3 0 1 3 0 0 ..... N 2 300 32 2 33 9 5 3 0 5 4 1 2 0 l lJj 3 378 50 1 76 30 1 1 1 13 1 5 8 0 1 Couqty Line 1 345 6 0 6 0 1 2 0 10 10 0 322 0 142 2 300 1 0 0 0 0 0 0 4 2 0 15 0 6 Talc Mine 1 300 2 0 2 1 0 0 0 8 2 0 61 1 14 2 300 1 0 7 1 0 0 0 8 4 0 60 0 18 Marblemount 1 300 0 0 9 0 0 5 0 4 6 4 155 1 76 2 300 2 0 19 0 1 2 0 4 11 0 114 1 52 Concrete 1 230 1 0 2 0 0 0 0 2 11 2 133 0 25 2 200 0 0 5 0 0 0 0 3 17 1 176 0 17 Table 4.7 Nwmers of organisms/m 3 from plankton pump samples, October 22-23, 1977. Sample Volume Diaptomus Daphnia Bosmina Harpac-Cyclop-Chironomid Plecoptera Ephemeropter• Site replicate (gal.) Diaptomus parts Naup11i Daphnia parts Bosmina parts Chydorids ticoids aids larvae nymphs nymphd Ross T.R. 1 300 77 4 10 35 360 90 0 0 0 2 0 0 0 2 300 77 6 8 36 318 170 0 1 0 11 0 0 0 Diablo F.B. 1 300 518 42 35 213 425 73 1 0 1 1 0 0 1 2 300 752 54 70 133 524 108 0 0 1 2 0 0 0 Diablo T.R. 1 300 811 35 64 93 219 83 0 0 0 0 1 0 1 2 300 492 26 74 35 111 70 0 0 0 1 1 0 1 Gorge F.B. 1 300 311 14 30 114 237 11 0 1 0 0 2 0 1 ,_. N 0'1 County Line 1 300 28 4 30 3 2 2 0 1 0 0 10 0 4 2 300 26 2 56 1 2 7 0 3 2 0 28 0 Talc Mine 1 300 26 2 11 0 0 5 0 4 0 1 29 2 1 2 300 19 0 14 0 1 4 0 3 4 0 13 0 4 Marblemount 1 300 8 0 18 0 0 0 0 1 1 0 11 0 2 2 300 3 0 11 1 0 4 0 4 3 2 105 0 3 Concrete 1 300 1 0 6 0 0 1 0 1 1 1 10 0 1 2 300' 1 0 2 0 0 2 0 1 1 0 27 0 2 J Table 4.8 Numbers of organisms/m 3 from plankton samples, November 19-20, 1977. pump Sample Volume Diaptomus Daphnia Bosmina Harpac-Cyclop-Chironomid Plecoptera Ephemeroptera Site replicate (gal.) Diapto111UB parts Nauplii Daphnia parts Bosmina parts Chydorids ticoids oids larvae nymphs nymphs Rosa T. R. 1 300 61 12 1 18 114 50 1 0 0 3 4 0 1 2 300 71 10 2 13 105 25 1 0 0 4 3 0 0 Diablo F.B. 1 300 490 26 48. 31 250 462 0 1 0 1 0 0 1 2 300 467 25 38 36 231 563 0 1 0 0 0 0 2 Diablo T.R. 1 300 452 48 14 7 80 315 4 .4 2 0 0 0 2 2 300 379 48 15 4 75 177 0 4 1 0 2 0 0 Gorge F.B. 1 300 165 11 4 1 49 13 0 3 0 0 2 0 1 ...... 2 300 133 4 8 3 75 49 0 7 1 3 7 0 4 N ....... County Line 1 300 51 4 44 0 4 27 0 3 7 2 60 0 8 2 300 41 5 18 1 2 18 0 3 3 4 30 0 9 Talc Mine 1 300 10 1 12 0 0 36 0 3 2 1 35 0 7 2 300 4 0 4 1 1 7 0 3 0 0 23 0 1 Marblemount 1 300 0 1 6 1 0 13 0 0 4 3 14 1 4 2 300 8 0 6 0 1 7 0 4 6 1 28 0 0 Concrete 1 300 0 2 1 0 7 3 0 10 11 1 6 0 5 2 300 0 0 2 0 0 0 0 3 4 0 0 0 0 Table 4.9 Numbers of organisms/m 3 from plankton samples, December 19-20, 1977. pump Sample Volume Diaptomus Daphnia Bosmina Harpac-Cyclop-Chironomid Plecoptera Ephemeroptera Site replicate (gal.) Diaptomus parts Nauplii Daphnia parts Bosmina parts Chydorids ticoids aids larvae nymphs nymphs Ross T. R. 1 300 24 1 8 16 193 38 0 0 1 0 0 0 0 2 300 29 1 5 10 176 33 0 1 0 2 0 0 0 Diablo F,B. 1 300 27 2 4 27 73 40 0 0 0 1 1 0 0 2 300 32 2 4 18 137 93 0 1 0 1 0 0 0 Diablo T.R. 1 300 26 2 6 6 99 36 0 0 0 0 1 0 0 2 300 26 1 0 12 106 53 0 0 0 0 0 0 0 Gorge F.B. 1 300 30 3 3 14 80 70 0 3 2 0 0 0 0 ....... 2 300 24 2 6 14 84 34 0 0 0 1 0 0 0 N 00 County Line 1 300 17 1 0 4 20 23 0 1 0 0 11 1 2 2 300 12 1 6 0 21 29 0 0 1 2 9 0 Talc Mine 1 300 12 1 2 2 18 53 0 2 5 0 10 1 6 2 300 18 1 0 2 9 7 0 0 0 0 3 0 3 Marblemount 1 300 8 0 1 2 7 18 0 0 10 0 11 0 0 2 300 4 4 0 0 0 3 0 0 0 0 0 0 0 Concrete 1 300 2 0 0 0 1 4 0 3 4 1 19 0 3 2 300 3 0 3 1 0 4 0 1 6 1 20 0 0 .. , l i J J Table 4.10 Seattle City Light flow data for the Skagit plants, 1977. Mean discharge over a month in second-foot days, elevations of Ross Lake in ft above mean sea level, and average retention time in days based on full pool storage. Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Ross Used for power 6467 3452 4409 1970 1479 215 567 lll 730 1063 ll77 4154 Spill 0 0 0 0 0 0 0 0 0 0 0 0 Elevations, max;. 1569 1535 1522 1585 1526 1561 1570 1581 1583 1582 1587 1591 min. 1536 1522 1493 1490 1507 1528 1561 1571 1581 1580 1581 1584 Diablo Used for power 6377 3664 4624 2418 1963 1541 1505 1538 1281 1272 1778 4790 Spill 435 0 0 0 0 0 0 0 0 0 0 0 Avg retention 6.65 12.37 9.80 18.74 23.09 29.41 30.12 29.47 35.38 35.63 25.49 9.46 Gorge Used for power 6632 3841 4779 2730 2195 ...,. 1928 1669 1393 1349 1327 2229 5313 Spill 426 0 12 0 0 0 0 0 0 0 0 0 Avg retention 0. 70 1. 28 1.03 1.80 2.24 2.55 2.95 3.53 3.65 3. 71 2. 21 0.93 ...... ....., \0 130 Diablo Forebay had higher densities of Daphnia and Diaptomus than Ross Tailrace until December when the retention time was shortened to less than 10 days (Table 4.10). Thus, it appears that under certain circumstances, Diablo Reservoir may add substantial numbers of zooplankton to that which it receives from Ross Lake. The retention time of Gorge Lake is very much shorter than that of Diablo (Table 4.10) and also shorter than the 15-day miminum retention time that Johnson (1964) found was needed for plankton development. The plankton densities in Gorge Lake at Diablo Tailrace and Gorge Forebay were similar. Wilcoxon sign rank tests were run on four groups--Daphnia, Bosmina, Diaptomus, and nauplii. The tests failed to show significant differences between the two sites for any of the four groups. It appears that Gorge Reservoir adds little to the plankton coming in from Diablo Reservoir. The higher densities of Bosrnina below Gorge Darn than in Gorge Forebay in April, May, and June (Tables 4.1,4.2, and 4.3, respectively) are difficult to explain. Nauplii densities in April, May, October, and November (Tables 4.1, 4.2, 4.7, and 4.8, respectively) and Diaptomus adult density in May (Table 4.2) were also higher at the County Line Station than at Gorge Forebay. If avoidance of the pump by these zooplankters in the reservoir were the cause, one would expect consistently lower forebay counts through the year. It could be that the plankton pump was not sampling the same stratum of Gorge Forebay that was entering the power intakes, although the short flushing time and lack of thermal strati- fication should make zooplankton stratification unlikely. Plankton sampling in Gorge Reservoir in 1973 and 1974 indicated little vertical stratification (Burgner 1977). Bosmina in Ross Lake in 1973 showed a slight tendency to be more dense than-niaptomus or Daphnia at depths greater than SO ft from April through July (SCL 1974), but this tendency was not apparent in 1972 (SCL 1973). A common phenomenon in zooplankton is a migration toward the surface at night and a downward migration during the day. Perhaps diurnal migrations cause plankton density changes at the stratum entrained by the power intakes and the water that was sampled at the County Line Station left Gorge Lake at a time of high plankton entrainment, e.g., at night when they rise up from the bottom. However, as explained above, zooplankton stratification in Gorge Lake seems unlikely. Also, water travel time between Gorge Powerhouse and the County Line Station was only about 1 hr and the County Line and Gorge Forebay stations were sampled each month in the afternoon on adjacent days. Seasonal fluctuations of plankton abundance are presented in Tables 4.11 to 4.18. At the forebay stations, there were peaks of Diaptornus, Daphnia, and Bosrnina abundance in spring and again in late fall or winter (Tables 4.12 and 4.14). The spring peak of Diaptomus, however, was not distinct at the Diablo Tailrace Station (Table 4.13) or at the Gorge Forebay Station (Table 4.14). In 1972 and 1973, Ross Lake had only one peak of Daphnia and Diaptomus abundance which occurred in August or September. Only Bosmina showed a bimodal abundance curve (SGL 1974). Perhaps in a more typical generation·year, the sites below Ross Lake would ~' ~' ) Table 4.11 Month April May June July August September October November December Seasonal fluctuations in numbers of organisrns/rn 3 at the Ross Tailrace Station. Parts are added to whole organisms. Replicates are averaged and rounded to the nearest integer. Diaptomus Nauplii Daphnia Bosmina 17 68 80 123 112 182 77 1,737 13,553 6,890 6,483 8 2,441 621 149 15 2,330 723 62 66 237 81 11 251 82 9 374 130 77 1 125 38 27 7 197 36 ] ...... w ...... Table 4.12 Month April May June July August September October November December Seasonal fluctuations in numbers of organisms/m3 at the Diablo Forebay Station. Parts are added to whole organisms. Replicates are averaged and rounded to the nearest integer. Diaptormw Nauplii Daphnia Bosmina 105 40 9 56 794 510 569 1,082 81 371 197 222 33 96 38 70 93 453 38 3 41 65 38 10 683 52 648 91 504 43 274 513 31 40 128 66 1-' w N 1 ---1 ---1 Table 4.13 Seasonal fluctuations in numbers of organisms/m3 at the Diablo Tailrace Station. Parts are added to whole organisms. Replicates are averaged and rounded to the nearest integer. Month Diaptomus Nauplii Daphnia Bosmina April 48 36 30 36 May 30 43 3 110 June 38 158 48 140 July 17 80 6 27 August 41 138 16 4 ...... w w September 35 20 17 3 October 682 69 229 76 November 464 15 83 248 December 28 3 112 44 Table 4.14 Seasonal fluctuations in numbers of organisms/m3 at the Gorge Forebay Station. Parts are added to whole organisms. Replicates are averaged and rounded to the nearest integer. ----·-- Month Diaptomus Nauplii Daphnia Bosmina April 17 5 29 36 May 35 56 5 179 June 20 110 43 141 July 24 93 6 38 August 25 173 8 2 September 39 44 17 2 .._.. w .p. October 325 30 350 11 November 156 6 64 31 December 29 4 96 52 J Table 4.15 Month April May June July August Seasonal fluctuations in numbers of organisms/m3 at the County Line Station. Parts are added to whole organisms. Replicates are averaged and rounded to the nearest integer. Diaptomus Nauplii Daphnia Bosmina 15 36 22 47 88 153 41 309 7 46 13 286 1 < 1 < 1 7 4 45 0 < 1 September 4 3 < 1 1 October 30 43 4 4 November 51 31 4 22 December 15 3 22 26 ] -~ 1-' w lJ"' Table 4.16 Month April May June July August September October November December Seasonal fluctuations in numbers of organisms/m3 at the Talc Mine Station. Parts are added to whole organisms. Replicates are averaged and rounded to the nearest integer. Diaptomus Nauplii Daphnia Bosmina 7 4 1 19 18 44 4 292 2 15 4 178 4 12 2 47 6 37 < 1 4 1 4 < 1 0 23 13 <1 4 8 8 < 1 22 16 <1 15 30 J ...... w (j\ l Table 4.17 Month April Hay June July August September October November December ] Seasonal fluctuations in numbers of organisms/m3 at the Marblemount Station. Parts are added to whole organisms. Replicates are averaged and rounded to the nearest integer. Diaptorrrus Nauplii Daphnia Bosmina 7 20 < 1 5 5 31 2 52 < 1 16 4 79 2 2 < 1 14 < 1 23 1 4 < 1 14 < 1 4 5 15 < 1 2 4 6 < 1 10 8 < 1 4 10 I-' w ....... Table 4.18 Month April May June July August September October November December Seasonal fluctuations in numbers of organisms/m3 at the Concrete Station. Parts are added to whole organisms. Replicates are averaged and rounded to the nearest integer. Diaptomus Nauplii Daphnia Bosmina 0 0 0 0 < 1 < 1 1 7 < 1 3 4 8 0 < 1 1 2 1 3 0 1 < 1 4 0 0 < 1 4 0 1 < 1 1 4 1 2 1 1 4 .I f--1 w 00 F"" I I 139 have reflected plankton density fluctuations more similar to those seen in Ross Lake in 1972 and 1973. The bimodal trends in zooplankton abundance seen in the reservoirs were reflected at the County Line Station (Table 4.15) but the trend became.less distinct farther downstream (Tables 4.16-4.18). Zooplankton densities at the downstream stations were low and sporadic. Drifting aquatic insects were found at all sites (Tables 4.2, 4.3, 4.8), but in larger numbers below Gorge Dam. Plecoptera (stonefly) nymphs were most abundant in the river drift below Gorge in July (Table 4.4), while chironomid and Ephemeroptera (mayfly) nymphs were most abundant in August (Table 4.5). Table 4.7 presents the results of a test for differences between the drift sampled in midstream and the drift in juvenile salmonid rearing areas conducted in October 1977. At the stations helow Gorge Dam, sample 1 was taken in mid-channel while sample 2 was taken inshore. Diaptomus densities tended to be higher offshore and chironomid densities tended to be higher closer to the bank. However, the number of observations was so low that Wilcoxon sign rank tests cannot be applied to individual species. The planktonic groups--Diaptomus, nauplii, DaphE~~· Bosmina, and chydorids--tested together, failed to show differences between inshore and offshore samples. A test of the river groups harpacticoids, chironomids, and Ephemeroptera nymphs indicated differences between the sample replicates at a 0.05 significance level, with the inshore samples having higher densities. The implication of these comparisons is that the .juvenile salmonids have available more benthic organisms than the drift samples indicate but not more plankton. Harpacticoids, chydorids, and cyclopoids occurred ubiquitously at low numbers. One species of chydorid, rarely found in the reservoirs, and a desmid, Closterium sp., never found in the reservoirs, was found at the Concrete Station. The desmid is normally found in small acid ponds, suggesting that some of the plankton found at the Concrete Station, well above the mouth of the Baker River, may have come from small ponds nearby. 140 - - - - - - [""' ! - r ! 141 5.0 SALMON AND STEELHEAD 5.1 General Freshwater Life History Waters of the Skagit Basin downstream of Newhalem are utilized for spawning by all five species of Pacific salmon and by steelhead trout. The mainstem Skagit is utilized primarily by summer-fall chinook, pink (in odd years only) and chum salmon, while coho primarily use tributary streams. Sockeye and spring chinook salmon are restricted mainly to the Baker and the Sauk-Cascade systems, respectively. Steelhead trout utilize both mainstem Skagit and tributary spawning sites. Spawning nests or "redds" are prepared in the gravel of the stream bottom by the female primarily, and mating occurs. Eggs are deposited in the redd by the female, fertilized there by a male, and covered with gravel by subsequent digging activities. After fertilization salmon and trout eggs undergo embryonic development within the stream gravels. During this time the developing embryo receives nourishment from the yolk material. About midway through the incubation cycle the eggs hatch. The resulting alevins with their protruding yolk sac continue to absorb the yolk material. The yolk sac gradually recedes and the yolk finally becomes fully absorbed. At this point the juvenile fish becomes dependent on outside material for nourishment. The rate of development and the number of temperature units (TU) required for development between fertilization and yolk absorption are dependent on the temperature regime and differ among the several species. Upon emergence from redds, fry of chinook salmon seek the quieter water along the banks of the larger streams such as the Skagit and Sauk rivers, and tend to distribute along shallow gravel bars and pool areas to feed. This tendency is also shown by juvenile coho and steelhead in their earlier stages after emergence. Pink salmon fry tend to move seaward at once. Chum salmon also are more prone to move seaward soon after emergence. Both pink and chum fry feed to a limited extent during their relatively short residence in freshwater and downstream migration. Juvenile summer-fall chinook generally rear about 3 months (but perhaps up to 5 months) in freshwater prior to their seaward movement. Juvenile coho migrate seaward in the spring of their second year while juvenile steelhead trout probably rear 2 years in freshwater before their migration to saltwater. 5.2 Hatchery Production Salmon and steelhead trout production in the Skagit River is supplemented by the Skagit Salmon Hatchery located near Marblemount (Fig. 1.1) which is maintained and operated by the Washington Department of Fisheries (WDF). Fish production from the Skagit Hatchery and fish plants in the Skagit system between Boyd Creek (river mile [RM] 44.7) and Newhalem are summarized in Table 5.1 for the period 1952 to 1977. Fall -------- ~1" 142 ~. Table 5.1 Fish production of the Skagit Hatchery and fish plants by WDF in the Skagit system from Boyd ~' Creek (river mile 44.7) to Newhalem, 1952-1977. ~' Number of fish Fish plants by WDF Year Brood Skagit Hatchery in the Skagit system from -planted year Species production Boyd Creek to Newhalem 1977 75 Spring chinook (yr) * 178,938 178,938 ~ 76 Spring chinook (fg) 157,121 157,121 75 Fall chinook (yr) 95,978 95,978 76 Fall chinook (yr) 87,860 0 fJJ1!$iP.· 75 Coho (yr) 1,346,647 973,327 76 Coho (fg) 2,828,893 2,828,893 ~, 1976 74 Spring chinook (yr) 45,540 45,540 75 Fall chinook (fg) 668,304 0 74 Coho (yr) 1,169,862 581,562 75 Coho (fr) 0 1,152,000 ~· 75 Chum (fg) 27,946 27,946 75 Pink (fg) 2,576,817 2,576,817 1975 73 Spring chinook· (yr) 90,935 90,935 74 Fall chinook (fg) 2,199,052 0 73 Coho (yr) 2,185,360 1,071,420 -74 Coho (fr) 3,316,920 231,678 74 Chum (fg) 4,586,410 4,586,410 1974 72 Spring chinook (yr) 84,920 84,920 73 Fall chinook (fg) 3,381,221 0 72 Coho (yr) 2,454,154 2,454,154 73 Coho ( fr) 1,000,128 648,960 73 Coho (fg) 485,289 485,289 73 Chum (fg) 3,709,336 3,709,336 73 Pink (fg) 476,216 476,216 72 Steelhead (yr) 30,248 30,248 1973 71 Spring chinook (yr) 14,696 14,696 ~ 71 Fall chinook (yr) 28,624 28,624 72 Fall chinook (fg) 4,228,288 3,399,750 71 Coho (yr) 1,566,949 1,508,426 72 Coho (fr) 805,000 490,000 ~r 72 Coho (fg) 0 76,442 72 Chum (fg) 3,098,166 3,098,166 FDil'- 1972 71 Fall chinook (fg) 3,257,907 3,257,907 71 Fall chinook (yr). 77,337 77' 337 70 Coho (yr) 1,202,491 1,147,391 -·· 71 Coho (fr) 915,600 0 71 Coho (fg) 0 425,000 71 Chum (fg) 463,320 463,320 71 Pink (fg) 38,500 38,500 ~' ' 143 Table 5.1 Fish production of the Skagit Hatchery and fish """' plants by ~IDF in the Skagit system from Boyd ' Creek (river mile 44. 7) to Newhalem, 1952-19 77 - continued. Number of fish Fish plants by WDF ,. ~ Brood Skagit Hatchery in the Skagit system from -~ear planted year Species production Boyd Creek to Newhalem 1971 70 Fall chinook (fg) 5,050,753 5,050,753 69 Coho (yr) 1,872,142 1,314,342 1970 69 Fall chinook (fg) 3,032,222 1,740,934 68 Coho (yr) 1' 711,493 1,870,790 69 Coho (fg) 492,350 492,350 ~ 1969 68 Fall chinook ( fg) 2,813,960 2,813,960 67 Coho (yr) 1,362,207 1,312,207 68 Coho (fr) 890,520 683,880 1968 67 Fall chinook (fg) 2,829,807 2,829,807 66 Coho (yr) 1,682,568 1,682,568 67 Coho (fr) 568,980 568,980 1967 66 Fall chinook (fg) 3,729,377 3,729,377 65 Coho (yr) 1,310,853 1,310,853 1966 65 Fall chino"ok (fg) 2,730,084 1,376,296 64 Coho (yr) 1,250,415 1,049,085 1965 64 Fall chinook (fr) 1,664,950 1 '6.64 '950 64 Fall chinook (fg) 2,560,151 2,037,340 -63 Coho (yr) 546,130 498,530 1964 63 Fall chinook (fr) 1,978,850 0 63 Fall chinook (fg) 2,674,686 1,275,443 -~ 62 Coho (yr) 822,128 635,557 63 Coho (fg) 89,175 89 '175 63 Coho (yr 391,247 158,760 1963 67 Fall chinook (fr) 1,585,292 250,200 62 Fall chinook (fg) 1 '469 '018 991,950 61 Coho (yr) 771 '775 56 7' 100 62 Coho ( fr) 526,500 526,500 1962 60 Spring chinook (yr) 130,400 0 61 Spring chinook (fg) 224,728 224' 728 Gl Fall chinook (fr) 1,888,580 964,444 61 Fall chinook (fg) 2,726,498 1,364,128 r 60 Coho (yr) 754,372 614,750 61 Coho (fr) 1,163,121 0 61 Stee1head (yr) 20,840 4,170 ~ - 144 Table 5.1 Fish production of the Skagit Hatchery and fish plants by WDF in the Skagit system from Boyd Creek (river mile 44.7) to Newhalem, 1952-1977 - continued. Number of fish Fish plants by WDF Year Brood Skagit Hatchery in the Skagit system from ~ planted year Species production Boyd Creek to Newhalem 1961 60 Fall chinook (fg) 2,746,218 1,628,558 ~ 59 Coho (yr) 817,310 608,931 60 Coho (fr) 2,360,364 1,630,964 60 Coho (fg) 230,530 100,264 60 Steelhead (yr) 16,286 4,150 1960 59 Spring chinook (fg) 1,029 1,029 ~ 59 Spring chinook (yr) 35,854 0 59 Fall chinook (fg) 3,626,140 607,136 58 Coho (yr) 550,238 436,538 59 Coho (yr) 88,518 88,518 59. Chum (fg) 196,620 0 59 ·Pink (fg) 80,870 80,870 59 Steelhead (yr) 24,312 0 1959 57 Spring chinook (yr) 149,922 0 58 Spring chinook (fg) 18,480 0 tiPm 58 Fall chinook ( fg) 2,216,846 776,973 57 Coho (yr) 470,297 339,505 58 Coho (fg) 990,198 804,823 57 Steel head (yr) 18,958 0 58 Sockeye 0 38,560 1958 57 Spring chinook (fg) 43,122 0 57 Fall chinook (fg) 3,788,289 1,533,542 56 Coho (yr) 668,957 423,301 57 Coho (fg) ll3 '723 113,723 57 Coho (yr) 135,692 135,692 57 Pink (fg) 21,107 21,107 56 Steelhead (yr) 21,829 0 1957 56 Spring chinook (yr) 27 '885 0 56 Fall chinook (fr) 2,689,249 1,035,827 56 Fall chinook (fg) 2,264,297 806,484 55 Coho (yr) 877,753 586,216 56 Coho (fg) 205,227 204,227 56 Coho (yr) 65,236 65,236 ~ 1956 54 Spring chinook (yr) 74,888 0 55 Spring chinook (yr). 24,918 0 55 Fall chinook (fg) 670,839 239,227 - 54 Coho (yr) 630,441 435,351 55 Coho (fr) 0 20,100 55 Steelhead (yr) 29,862 -0 l - - 145 Table 5.1 Fish production of the Skagit Hatchery and fish plants by WDF in the Skagit system from Boyd Creek (river mile 44.7) to Newhalem, 1952-1977 - continued. Number of fish Fish plants by WDF Year Brood Skagit Hatchery in the Skagit system from planted year Species production Boyd Creek to Newhalem 1955 1954 1953 1952 Ref.: 53 Spring chinook (yr) 36,922 54 Fall chinook (fg) 846,899 53 Coho (yr) 475,950 54 Coho (fr) 233,676 54 Coho ( fg) 40,377 54 Chum ( fr) 61,704 54 Steelhead (yr) 30,280 53 Spring chinook (fg) 100,764 53 Spring chinook (yr) 117,256 52 Coho (yr) 529,559 53 Coho (fr) 0 53 Pink (fg) 285,674 53 Steelhead (yr) 40,859 52 Spring chinook (fg) 438,8 77 52 Fall chinook (fg) 209,736 51 Coho (yr) 322,528 52 Coho (fr) 0 52 Coho (fg) 703,299 51 Steel head (yr) 26,045 50 Coho (yr) 438,029 51 Coho (fg) 208,505 *yr = yearling (270 + days reared). fg = fingerling (14-269 days reared). fr = fry (0-14 days reared). WDF -1977 Annual Report, in press. WDF -1976 Annual Report, Progress Report No. WDF -1975 Annual Report, October, 1976. WDF -Hatchery Statistical Records Report No. WDF -Hatchery Statistical Records Report No. 0 742,992 351,340 167,822 40' 3 77 61,704 0 0 96,574 329,890 23,750 0 0 260,662 209,736 237,474 30,000 457,781 6,297 287,742 143,364 30, July 1977. 1 (2nd Edition). 2. 146 chinook and coho salmon have been the princ~pal species produced, hut in recent years increased emphasis has been placed on producing spring chinook, pink, and chum salmon. Three to five million fall chinook fingerlings were released per year in the early 1970's. Between 1974 and 1976 no fall chinook were released in the Skagit system between Boyd Creek and Newhalem. In 1977 about 96,000 fall chinook yearlings were released. Production of steelhead trout occurred primarily before 1963. A steelhead trout rearing facility is maintained and operated by Washington Department of Game (WDG) in Barnaby Slough, near Rockport (Fig. l.l). Details of the 1974-1977 salmon and trout plants by WDF and WDG for the Skagit system between Concrete and Ross Dam are listed in Table 5.2. 5.3 Escapement Skagit system natural spawning escapements have been estimated for recent years by WDF for chinook (summer-fall and spring), pink, chum, ancl coho salmon (Table 5.3). Summer-fall chinook escapement levels were relatively stable for the 1965 to 1977 period while spring chinook escapements were at low levels from 1974-1976. The lower than average escapement in 1977 may be attributable to the lack of hatchery released fish in 1974 from the 1973 brood. However, the effect and proportion of naturally spawning hatchery produced fish on the wild chinook stocks is not known (Orrell 1976). Escapement estimates for coho, pink, and chum salmon showed greater year-to-year variability than for summer-fall chinook, but neither a general upward nor downward trend was apparent. Chum salmon escapement estimates show a 2-year cyclic pattern with peaks occurring in even years. The low cycle escapements for chums coincide with odd year runs of Skagit pink salmon. This relationship possibly reflects estuarine rearing conditions or capacity since Skagit River chum salmon return predominantly as 4-year-old fish (R. Orrell, personal communication) and pinks, of course, return as 2-year-old fish. Skagit River escapement goals for 1977 were set at 14,850 for summer-fall chinook (Ames and Phinney 1977), and 27,000 for coho salmon (Zillges 1977). Escapement levels to the Skagit Salmon Hatchery from 1949 to 1977 are shown in Table 5.4. 5.4 Relationships Between Skagit River Flows and Chinook Salmon Returns 5.4.1 Introduction Skagit River flow records were analysed in an effort to identify pos- sible correlations between river flows during sensitive stages of chinook salmon life-history and the run size produced from that year. The three life-history periods investigated were: spawning, incubation, and rearing. - - """"' 1974 ' ·- 197S ,... - r - 1976 147 Table S.2 Summary of fish plants in the Skagit River system between Concrete and Ross Darn, 1974-1977 (WDF, WDG). Brood Date Number Location year Species planted planted of plant 72 Spring chinook S/lS 84,920 Clark Creek 72 Coho S/lS 1,187,908 Clark Creek 72 Coho 8/1 1,266,246 Clark Creek 72 Steelhead S/lS 30,248 Clark Creek 73 Coho 4/6 106,900 Bacon Creek 73 Coho 4/6 106,060 County Line 73 Coho 4/6 124,7SO Illabot Creek 73 Coho S/3 2S3,001 Cascade River 73 Churn 6/4 3,118,3S6 Clark Creek 73 Chum 6/17 S90,980 Clark Creek 73 Pink 6/4 476,216 Clark Creek 72 Rainbow 8/14 1,7SO Cascade River 73 Rainbow 4/9 70,000 Diablo Lake 73 Rainbow 6/S l,OS6 County Line Beaver Ponds 73 Spring chinook 3/13 90,93S Clark Creek 73 Coho S/13 1,071,420 Clark Creek 74 Coho 3/21 231,678 Illabot Creek 7!+ Churn S/19 56,800 Clark Creek 74 Churn 6/10 4,529,610 Clark Creek 74 SR steelhead 4/18-4/28 10,968 Lucas Slough 74 SR steelhead S/5-5/16 39,445 Lucas Slough 74 SR steelhead S/7-5/19 26' 77S Cascade River 74 WR steelhead 4/18-4/28 3S,886 Lucas Slough 74 WR steelhead S/2-S/lS 22,892 Lucas Slough 74 l.J'R steelhead 5/2-S/3 20,400 Cascade River 74 WR steelhead S/13 2,737 Rockport 74 WR steelhead S/13 8,383 Goodell Creek 74 Rainbow 6/3 34,4S2 Diablo Lake 74 Rainbow 8/20 3,658 Cascade River 74 Rainbow 8/20 1,000 Bacon Creek 74 Spring chinook 3/1 4S,540 Clark Creek 74 Coho SIS S81,562 Clark Creek 7S)~ Coho 3/22 492,000 Sauk River 75* Coho 4/14 540,000 Sauk River 75 Pink 4/15 1,844,817 Clark Creek 75 Pink 4/23 671 '000 Clark Creek 75 Pink 5/4 61,000 Clark Creek 75 Chum 6/14 2 7. 946 Clark Creek 7S SR steelhead 4/15-5/11 36,470 Lucas Slough 1976 1977 ... 148 Table 5. 2 Summary of fish plants in the Skagit River system between Concrete and Ross Dam, 1974-1977 (WDF, WDG) - continued. Brood year 75 75 75 75 75 75 75 75 75 75 76 Species SR steelhead WR steelhead WR steelhead WR steelhead WR steelhead WR steelhead Rainbow Rainbow Rainbow Rainbow Cutthroat 75 Spring chin. 75 Fall chinook 76 Coho 76 Coho 76 Coho 76 Coho 76 Coho 76 Coho 76 Coho 76 · Chum 76 Chum 76 Spring chin. 76 SR steelhead 76 SR steelhead 76 SR steelhead 76 SR steelhead 76 SR steelhead 76 SR steelhead 76 WR steelhead 76 WR steelhead 76 WR steelhead 76 WR steelhead 76 WR steelhead 76 WR steelhead 76 WR steelhead 76 Rainbow 76 Rainbow 76 Rainbow 76 Rainbow 76 Rainbow 76 Rainbow Date planted 4/29-5/3 4/16-5/13 4/27 4/30 4/26 4/22-4/30 5/21 5/26 6/18 6/29 10/ 7 3/28 3/28 4/ 4 4/ 5 4/ 5 4/ 5 4/ 5 4/ 6 5/ 1 4/22 5/16 6/ 3 4/25 4/25 4/26-4/28 5/ 3-5/ 6 5/ 6-5/10 4/18 4/18-4/20 4/20 4/19-4/21 4/19-5/12 4/21-5/4 4/22-4/25 4/26-4/29 5/18 5/26 5/31 6/ 8 6/28 6/28 Number planted 15,369 88,933 10,980 8,840 10,800 28,457 75,068 53,414 179 1,729 4,000 178,938 95,978 141,990 27,000 69,000 33,000 39,000 6,000 585,337 201,390 2,627,503 157,121 7,920 8,010 16 ,020 12,255 5,687 5,310 19,987 5,017 14,784 201,654 16,901 15,021 19,945 35,175 1,701 65,450 175 1,513 23,100 Location of plant Cascade River Lucas Slough Steelhead Club Park Young's Bar Goodell Creek Cascade River Diablo Lake Gorge Lake Ladder Creek Cascade River Thornton Lakes Clark Creek Clark Creek Cascade River Diobsud Creek Bacon Creek Goodell Creek Illabot Creek Clark Creek Clark Creek Newhalem Ponds Clark Creek Clark Creek Hatchery Cascade River Park Goodell Creek Bacon Creek Lucas Slough Sauk River Sauk River Clear Creek Steelhead Park Lucas Slough Young's Bar Faber's Ferry Baker River Mouth Gorge Lake Cascade River Diablo Lake Ladder Creek Lake Shannon Baker Lake - ~- .... "samish Hatchery Plants Ref. WDF -1974 Annual Report. WDF -1975 Annual Report, October 1976. July 1977 WDF -1976 Annual Report, Progress Report No. 30, WDF -1977 Annual Report, in press. WDG -Hatchery planting records, Seattle office. Year 1959 1961 1963 1965 1966 1967 1968 1969 ~-1970 1971 1972 1973 -1974 1975 1976 -1977 149 Table 5.3 Estimated Skagit River system spawning escapements (Washington Department of Fisheries). Summer-fall Spring Mean chinook1 chinook2 Pink2 200,000 400,000 1,190,000 18,266 3,937 150,000 12 '02 6 2,967 8' 117 1' 4 79 100,000 12,330 1,164 9,613 2,318 100,000 18,872 2,673 18,760 2 '664 300,000 23,234 2,506 17,809 . 2, 349 250,000 12,901 594 11' 555 804 100,000 14,479 804 ') 500,000 3 9,5o:r 14,428 2 '022 329,000 1WDF-Technical Report No. 29, May, 1977. 2wnF-R. Orrell, personal communication. Chum) 47,000 14,900 52,900 24,400 49,100 '12,500 42,800 7,800 85,000 32,130 36,853 lwnF-R. Orrell, personal communication, considered provisional and subject to revision. 4wnF-Technical Report No. 28, April, 1977. Coho 4 24,000 20,000 13 '000 18,000 9,000 18,000 12,000 12,000 13,000 22,000 10,000 5,0002 24,000 15,385 150 Table 5.4 Salmon escapement to the Skagit Hatchery racks, 1949-1977 (WDF).a Coho 1949 190 1950 1951 1,908 4,599b 1952 1,611 1953 841 1954 913 1955 642 1956 1957 27 5 468 1958 1,135 1959 1,680 1960 3,758 1961 "1,479 1962 1963 1,352 1964 1965 1966 . 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1,139 923 2,173 3,530 7,997 16,005 22,204 32,668 15,319 11 '246 32,930 28,090 16,072 12,671 Chinook 159 556 133 259 346 1,995 801 758 924 745 1,107 606 238 Pink 555 1,181 3,135 4,924 Chum 79 72 6,486 a Ref: Department of Fisheries, Annual Report, 1970, pp. 122, 125. ~~F Ptogress Report No. 30, July 1977, pp. 4-7. WDF Annual Report, 1977 in press. blncludes Cascade River fish. cSpawned fish only. .... l - - - 151 5.4.2 Materials and Methods 5.4.2.1 Flow Data. Daily maximum, minimum, and mean gage height data were obtained from U.S. Geological Survey (USGS) for the Skagit River at Newhalem for the period from September 1961 to the present. Analyses of these data included determination of the number of days that flow re- ductions in excess of about 1 ft dropped helow 82 ft (or about 2200 cfs) and the mean daily difference in the maximum. and minimum gage heights. Hean monthly discharge data and maximum daily discharge data for the Skagit River at Alma Creek were obtained from published USGS records. 5.4.2.2 Fisheries Data. As an indicator of run size, the estimated escapement (Table 5.3) w~s added to the Skagit Bay catch (Orrell 1976, and Ames and Phinney 1977). Skagit Bay chinook catches are predominantly Skagit River stock and, therefore, their inclusion better reflects the relative run size than the escapement alone. Specific data were not available for other fisheries known to take Skagit-produced chinook so an estimate of total run size could not be made. Relative run size was paired with flow conditions 4 years earlier. This was based on age ~omposition data from 1965 to 1972 (Orrell 1976) which indicated Skagit chinook salmon were 73.4%, 4-year-old fish, while 3's, 5's, and 6's comprised 9.6%, 16.0%, and 1.1%, respectively. Relative run size (escapement plus Skagit Bay catch) was plotted against the mean September discharge for Skagit near Alma Creek, the maxi- mum daily discharge for Skagit near Alma Creek during September through February, and the number of flow reductions below 82 ft (about 2200 cfs) for Skagit at Newhalem-during January through April. ·, ·5.4.3 Results and Discussion 5.4.3.1 Spawning Flows. The possible influence of stream flow during the chinook spawning period was assessed by comparing mean September discharge near Alma Creek with the relative run size 4 years later (Table 5.5). Skagit near Alma Creek data were used because they would reflect the regulation of discharge by Gorge Dam as w~ll as natural inflow between Newhalem and Alma Creek. Data for the Lewis River indicated that mean flow during spawning was directly related to chinook returns 4 years later (Roy Hamilton, PP&L, personal communication). Skagit River data show considerable scatter and no apparent correlation (Fig. 5.1). 5.4.3.2 Incubation Flow~. Peak flood flows during incubation were shown to be related to sockeye salmon returns in the Cedar River (Miller 1976). No such relationship was apparent from Skagit data (Table 5.5 and Fig. 5.2). As indicated in Sec. 2.0, the Seattle City Light (SCL) dams reduce the magnitude of the peak flood flows in the upper Skagit River which presumably reduces their impact on incubating chinook eggs and alevins. Skagit flows from the Alma Creek gage were used because they reflect the influences of regulation and natural factors. 152 Table 5.5 Compilation of selected streamflow data for Skagit River near Alma Creek and at Newhalem (USGS) and Skagit River escapement and relative run size data (WDF). At Newhalem gage At Alma Creek gage (January-AEril) 4 yrs later Mean Mean Max. daily Drops daily Escapement September flow during below gage ht. plus Brood flow incub. (Sep-Feb) 82 ft change Escape-Skagit Bay year (cfs) (cfs) (No. days) (ft) ment catch 61 3,586 11,300 113 3.65 18,266 45,544 62 2,633 15,900 111 3.57 12,026 31,206 63 3,660 20,200 109 3.36 8,117 17,002 64 3,821 8,900 119 3.63 12,330 23,198 65 2,280 7,650 88 3.25 9,613 17,796 66 2,988 13,400 106 3.49 18,872 26,669 Mean 3,161 12,892 108 3.49 13,204 26,902 67 3,760 22,900 36 1.94. 18,760 23,703 68 4,215 11,200 42 1.86 23,234 31,347 69 3,831 8,180 45 1. 92 17,809 26,333 70 3,384 8,700 26 1. 37 12,901 21,021 71 3,215 11' 500 9 1.51 11,555 22,975 72 4,071 8,960 31 1. 50 14,479 20,878 73 2,115 13,200 7 1. 29 9,602 74 3,098 13,300 Mean 3,461 12,243 28 1.63 15.4 77 24,376 - - - """' ~ """' .-:w, ~\ - ~"" ~- 153 48000~----------------------------------------~ X 61 44000 40000 :I: u ~ a: u + 36000 ...... z w z: w 32000 n... u: X62 X 68 u en w X: 28000~ 0 0 X66 z X69 -::t: u 24000 67XX64 X 71 X70 X72 20000 ~ X 65 X63 16000 I I I • 2000 2400 2800 3200 3600 4000 MEAN SEPT. DISCHARGE-ALMA CK. (CfS) Fig. 5.1 Scattergram of mean September discharge (cfs) at Skagit River near Alma Creek (USGS) versus relative Skagit chinook run size 4 years later. Numbers indicate brood year. 4400 154 40000 ~ 0 1- 5 + 36000 1- ~ 32000 ~ 5 X68 X62 f3 :X: 28000 0 0 X66 z X69 .... 3: u 24000 .. 'X67 X64 X 71 20000 r 70 ~72 X65 X63 16000~--_.----~----._--~~--~----~·-----~·--~----~ 6000 8000 10000 12000 14000 16000 18000 20000 22000 24000 DAILY MAX. DISCHARGE -ALMA CK~ (CfS) Fig. 5.2 Scattergram of daily maximum discharge (cfs} at Skagit River near Alma Creek (USGS) during September through February versus relative Skagit chinook run size 4 years later. Numbers indicate brood year. - - - - - - - 155 5.4.3.3 Rearing Flows. Parameters were developed to reflect the frequency and magnitude of flow fluctuations during the rearing period (January-April) when chinook fry are present and potentially susceptible to stranding. The number of drops below 82 ft and the mean daily change in gage height at the Newhalem gaging station showed a sharp decrease be- ginning in the January-April 1968 period, i.e., influencing fish from the 1967 and later broods (Table 5.5). Prior to this date the numbers of drops below 82 ft were on the average about 4 times more frequent than they were afterward. The mean daily change in gage height was consist- ently between 3 and 4 ft prior to 1968, while afterward they did not exceed 2 ft. These shifts indicate a change in operational policy Gorge Dam releases which in effect reduced the frequency and magnitude of flow fluctuations to downstream areas. Reductions in flow fluctuations should have been beneficial to rearing chinook fry by reducing the potential for fry stranding. Skagit escapement and escapement plus Skagit Bay catch data were examined to determine if they were influenced by the clear-cut and consistent reduction in flow fluctuations. No apparent relationship was discerned by plotting the number of flow reductions below 82 ft (about 2200 cfs) against the relative run size (Fig. 5.3). The mean escapements prior to and after the reductions in flow fluc- tuation were compared using the t-statistic for two means. The result in- dicated no significant (at .05) difference in means. A similar result was obtained when comparing mean escapement plus Skagit Ray catch before and after the reduction in flow fluctuation. These results seem to indicate the presence of a compensatory mecha- nism which may be masking the influence of fry losses due to strandinv,. 5.5 Steelhead Catch While no spawning escapement estimates were available for steelhead trout, WDG has calculated and compi_led catch statistics for the Skagit River system (Tables 5.6-5.8). For the 1961-1977 period, 92~7% of the total sport harvest came from the mainstem Skagit with the remainder distributed between the Sauk (6.6%) and Cascade (0.6%) systems. Winter-run (caught November through April) and sui!ll'ler-run (caught Hay through October) steelhead made up 97.2% and 2.8%, respectively, of the estimated system sport harvest. Skagit system winter-run sport catches for the past 16 cycle years (Table 5.6) have averaged 11,681 fish per cycle year and have shown a sharp decline in recent years (5,743 in 1974-1975; 1,647 in 1975-1976; and 1,220 in 1976-1977). This was due in part to the increased harvest by treaty Indians (Table 5.8) under the "Boldt Decision" that Indians be allowed to catch up to 50% of the harvestable anadromous salmon and steel- head in certain western Washington waters. Treaty Indian catches of winter-run steelhead were 15,968 in 1974-1975; 6,338 in 1975-1976; 1,469 in 1976-1977. 156 48000------------------------------------------- ~ 5 44000. 40000 ~ + 36000 ..... I f3 :.:: 0 0 z -5 X 61 Fig. 5.3 Scattergram of number of days when flows dropped below 82 ft at Skagit River at Newhalem (USGS) versus relative Skagit chinook run size 4 years later. Numbers indicate brood year. - """'' - """" ~ - rrr-- ..... - - ,_ - - 157 Table 5.6 Sport harvest of Skagit system winter-run (Nov-Apr) steelhead trout, 1961-1962 through 1976-1977 (WDG). Figures are corrected for nonresponse bias. Skagit Sauk Suiatt1e Cascade 1961-62 11 '125 656 0 0 1962-63 12,852 832 0 0 1963-64 20 '939 1,301 0 0 1964-65 12,497 850 0 4 1965-66 16,010 700 0 0 1966-67 14,900 1,943 10 2 1967-68 18,914 1,525 0 5 1968-69 13,157 568 0 17 1969-70 6,865 665 13 46 1970-71 10,379 667 12 26 1971-72 13 '678 1,000 13 126 1972-73 8,471 716 28 58 1973-74 6,134 527 17 38 1974-75 5,463 184 15 81 1975-76 1,512 100 2 33 19 76-77 1,029 168 23 Mean 10,870 775 7 29 158 - Table 5.7 Sport harvest of Skagit system summer-run (May-Oct) steelhead trout, 1962 through 1976 (WDG). Figures are corrected for nonresponse bias. - Skagit Sauk Suiattle Cascade ~~ 1962 46 26 0 0 1963 llO 26 0 0 1964 88 14 0 0 1965 94 11 6 0 1966 67 0 0 0 1967 110 16 0 8 1968 199 17 0 7 1969 186 7 0 9 ~ 1970 88 23 0 0 1971 130 43 0 4 1972 343 58 0 59 1973 1,165 28 0 277 ~ 1974 731 22 0 163 -~ 1975 472 16 10 37 1976 269 24 36 Mean 273 22 1 40 ~' - """' - 159 Table 5.8 Skagit system Treaty Indian harvest of winter-run steelhead, 1953-1954 through 1976-1977 (WDG). Gaps in data are for years when no information was available. Steelhead taken 1953-54 41 1956-57 715 1957-58 438 1958-59 7 1959-60 457 1960-61 493 1961-62 1,937 1973-74 3,668 1974-75 15,968+343 1975 cycle .summer-run steelhead 1975-76 6,338 1976-77 1,469+ 19 1976 cycle summer-run steel head 160 5.6 Angler Survey 5.6.1 Introduction One of the effects of the construction of a dam at Copper Creek would be the elimination of any existing recreational river fishery in the main- stem Skagit River upstream from the proposed dam site. Fish species available to the sport angler in that part of the Skagit River include steelhead trout, whitefish, rainbow trout, and Dolly Varden. In an effort to index the angler utilization of the upper Skagit River relative to recreational fishing above and below the Copper Creek site, angler counts were compiled incidentally to other research activities in the study area. 5.6.2 Naterials and Hethods The presence of anglers fishing in the mainstem Skagit was noted whenever an excursion was made into the field. The time, location, whether the observation was made from the truck or from the boat, and the field itinerary were recorded. The only persons considered anglers were those actively fishing or with fishing gear in their possession. Angler observations were made from June 15, 1977, until January 13, 1978. They were terminated January 13 when it was discovered that the Skagit River upstream from the Marblemount Bridge had been closed to all fishing since January 1. Traditionally, the Skagit River has been open to sport fishing from late May when the general stream and river summer season opens until the beginning of the winter steelhead season on December 1. The river then rema~ns open until March or'April, depending on the strength of the fish runs. Observations took place Monday through Friday from approximately 8:00 a~m. until 5:00 p.m. Observations were made over varying distances of the river length between RM 93.3 at Newhalem Creek to RM 67.0 at the mouth of the Sauk River. Since most field activities began at our Newhalem laboratory, the upstream river reaches were surveyed more frequently than downstream reaches. The distance surveyed was traveled either by truck only or by a combination of truck and boat. Most of the time, this distance was traveled by truck but when river travel was necessary to get to work areas, some of the distances were covered by boat. Boat travel was usually from the Newhalem boat launch upstream to the Newhalem Reference Reach and downstream to County Line Bar, from the Talc Mine boat launch to the Talc Mine Reference Reach, from the Marblemount Bridge boat launch up- stream to the Marblemount Reference Reach and occasionally to the Talc Mine boat launch, and from the Rockport steelhead park downstream to the Rockport Bar. The distance from Rockport to Newhalem was driven and the visible sections of river marked on aerial photographs to estimate the number of river miles visible from the road. The sections marked were then measured and converted to river miles according to the aerial photograph scale. This was done in early summer when vegetation partially obscured the view of the river in places. - - - - 161 The study area was divided into three sections: Creek, Copper Creek to Marblemount (mouth of Cascade Marblemount to Rockport (mouth of Sauk River). 5.6.3 Results and Discussion Newhalem to Copper River), and The results of the angler survey are summarized in Table 5.9. For the seven-month observation period, 11 anglers were noted in the Newha1em to Copper Creek section, whereas 46 and 112 anglers were noted in the Cop- per Creek to Marblemount and Harblemount to Rockport sections, respect- ively. This was in spite of the fact that more excursions were made in the upstream section than in the downstream sections. This trend persisted regardless of whether observations were made from the truck only or from the truck and boat in combination. On a per excursion basis there was also a trend of increasing angler utilization for the downstream sec- tions of the Skagit study area. Differential river visibility from the hi~hway for the three sections did not account for this trend. It was estimated that approximately 56% of the river was visible from the highway between Newhalem and Copper Creek, whereas about 63% and 35% were visible between Copper Creek and Harblernount and between Marblemount and Rockport, respectively. Information for recent years obtained from WDG (R.G. Gibbons, WDG, personal communication; Young 1976) contained few data reiative to angler utilization of the Skagit River above Harblemount. Creel censuses were conducted during the winter steelhead season by WDG personnel. During the 1975-1976 ste~lhead season, their "upper Skagit" section extended from 2 mi above the Rockport Bridge to Gorge Powerhouse. However, all angler counts for this section were compiled at two index areas, one extending from the Marblemount Bridge to the mouth of the Cascade River and the other located in the vicinity of an access ramp 2 mi above Rockport. For the 1976-1977 and 1977-1978 winter steelhead seasons, WDG divided the Skagit River into two sections for the purpose of creel surveys. One sec- tion extended from the river mouth to Lyman and the othe.r was from Lyman to Newhalem. However, the Lyman to Newhalem section was usually surveyed by boat to a point about one-half mile upstream of the Rockport Bridge and by car up to the Marblemount Bridge. The results of our angler survey and ~he low emphasis on creel census in the area by WDG indicate the relatively low angler utilization of the Skagit River above Harblemount. Another factor which probably contributes is the poor public access to the upper river. There are no developed public access points to the river above Copper Creek and the section below Copper Creek is accessible from the undeveloped boat launching area underneath the t1arblemount Bridge. Immediately upstream and downstream from this point was the section of river that accounted for the majority of anglers observed in the Copper Creek to Harblemount section. One other access point to that river segment is in the vicinity of the mouth of Bacon Creek which accounted for a lesser portion of anglers. Similarly, most of the anglers observed between Marblemount and Rockport were noted Table 5.9 Survey area* June NH-CC CC-:MM MM-RP July NH-CC CC-:MM MM-RP August NH-CC CC-MM MM-RP SeEtember NH-CC CC-MM MM-RP October NH-CC CC-MM MM-RP November NH-CC CC-MM MM-RP December NH-CC CC-:MM MM-RP January NH-CC CC-:MM MM-RP Total NH-CC CC-MM MM-RP *NH-CC 162 Summary of Skagit River angler survey conducted between Newhalem and Rockport, 15 June 1977 to 13 January 1978. II of excursions II of anglers It of anglers Truck Truck Truck Truck per only & boat only & boat excursion 6 5 1 2 0.27 5 4 5 3 0.89 4 2 2 2 0.67 5 5 0 1 0.10 5 5 1 1 0.20 4 2 4 0 0.67 8 10 1 0 0.06 6 7 4 10 1.08 6 3 2 9 1. 22 6 9 0 3 0.20 6 9 4 8 0.80 5 2 17 11 4.00 6 10 3 0 0.19 6 9 0 7 0.47 6 2 9 2 1. 38 7 5 0 0 0 7 5 3 0 0.25 6 2 0 2 0.25 6 5 0 0 0 6 4 0 0 0 6 2 26 5 3.88 2 1 0 0 0 2 1 0 0 0 2 1 5 16 7.0 46 50 5 6 0.11 43 44 17 29 0.53 39 16 65 47 2.04 = Newhalem to Copper Creek; CC-MM = Copper Creek to Marblemount; MM-RP = Marblemount to Rockport. ~- - ~ - ~ ~'9o _, - ~ - ~ - - - 163 within three-quarters of a mile upstream and downstream of the Rockport Steelhead Park, the main public access point for the upper Skagit. Several factors exist which would bias our angler counts. These include the local anglers from Newhalem who fish for steelhead in the tailrace of Gorge Powerhouse, an area that was not surveyed. Another is the absence of any weekend or early morning and late evening observations. While more total anglers would have been observed if these factors had been accounted for, the proportion of anglers fishing above and helow Copper Creek would probably have remained similar. 164 - - - - - 165 6.0 SPAWNING 6.1 Introduction The focus of these studies was on the adult chinook (Oncorhynchus tshawytscha), pink (0. gorbuscha), churn (0. keta), and coh~salmon-(o~ kisutch), and steelh~ad trout (Salrno gairdneri) which spawn in the "~pper" Skagit River between the conflu~ of the Baker River and Gorge Power- house. The present study was undertaken as part of a larger effort to establish a data base for the upper river upon which possible effects of future modifications or additions to the Skagit Project could be gaged. The principal objectives were: 1) To determine the distribution and timing of the salmon and steelhead trout spawning stocks in the upper Skagit River; 2) to develop the relationship between spawnable area and discharge; and 3) to estimate the amount of potential spawning area for Skagit River salmon above and below the proposed Copper Creek Dam site. Secondary objectives were to determine the depths and velocities "preferred" by spawning Skagit River salmon and to ol;lserve the effects of fluctuating water level on redds and spawning adult fish. These studies were conducted primarily in 1975 and 1976, with followup work in 1977. The area consisted. of 37.7 river miles from the Gorge Power- house at river mile (~) 94.2 downstream to the confluence of the Baker River at RM 56.5 (Fig. 6.1). The discharge of the upper Skagit River was first regulated in 1924 and is presently influenced by Gorge, Diablo, and Ross reservoirs with a combined capacity of 1,535,000 acre-foot (U.S. Geological Survey--USGS--1977). Flows may fluctuate on a diurnal or even hourly basis, depending on the demand for hydroelectric power and the operational constraints exercised. Analysis of discharge data for 1975 and 1976 indicated periods of low flow in late summer and early fall with much higher flows in early summer and late fall (Figs. 6.2 and 6.3). Mean annual discharge varied from 4,511 cfs at Newhalern (1908-1976) to about 12,600 cfs just above the Baker River (1924-1976). Twenty sample transects were established for systematic hydrological investigation with one transect for every 1.9 river miles on the average (Table 6.1 and Fig. 6.1). In addition, four reference reaches were established for biological and detailed hydrological investigations. Two reference reaches were established above the proposed Copper Creek Dam site and two in the river below (Fig. 6.1). Reference Reach 1 was the farthest upstream and was located at RM 91.6, 2.6 rni below the Gorge Powerhouse. Reference Reach 2 was at RM 84.3, 0.3 rni above the proposed Copper Creek Dam site. Reference Reach 3 was established at RM 79.4, near Marblemount, 1.3 mi above the confluence of the Cascade River. Reference B l -->-- 0 2 ~ 4 I I I miles 9 Reference Reach .,,ith sample transect / Somple Transect li USGS Gaging Station • Gorge Powerhouse X Copper Cree~ Dam Srle Fig. 6.1 Skagit River sample transects (1-20, lighter numbers) and reference reaches (1-4, bold numbers) between the Gorge Powerhouse (Newhalem) and the Baker River (Concrete). The Copper Creek Dam ··site and the USGS gaging stations are shown. J J t J -~ ~ ~ J ) 30 25 (J) IJ... u o20 8 X E'5 g§15 J: u (J) ..... Cl >-_j ....... 0: 010 z ~ 5 J l 1975 USGs CONCRETE USGS NEWHALEI1 QL---------~---------~--------L---------~--------~------~ JUL AUG SEP OCT NOV DEC DATE Fig, 6.2 Skagit River hydrographs of mean daily discharge at two gaging sites for the period from July to December 1975 (U.S. Geological Survey 1976). (fJ u.. u 30 25 o20 0 0 X ~ ~15 iS (fJ ...... Cl >-...J ...... a: DlO :z: a: w :c 5 1976 USGS CONCRETE USGS MARBLEMOUNT ~ USGS NEWHALEM QL-------~~---------~--------~--------~L---------~--------~ JUL AUG SEP OCT NOV DEC DATE Fig. 6.3 Skagit River hydrographs of mean daily discharge at three gaging sites for the period from July to December 1976 (U.S. Geological Survey 1977). - - 169 Table 6 .1 Location of Skagit River sample transects by river mile. Sample transect or prominent feature Gorge Powerhouse 1 2 3 4 5 6 7 8 Copper Cr. Darn Site 9 10 11 Cascade River 12 13 14 15 16 Sauk River 17 18 19 20 Baker River River mile 94.2 92.9 91.6 90.5 89.4 88.4 86.6 85.8 84.3 84.0 82.9 80.8 79.4 78.1 77.2 74.6 72.7 70.6 68.1 67.0 65.8 63.8 61.2 59.3 56.5 170 Reach 4 was the farthest downstream at RM 61.2, 5.8 rni below the mouth of the Sauk River and 4.7 rni above the confluence of the Baker River with the Skagit. 6.3 Materials and Methods 6.3.1 Spawning Depths and Velocities Depth and velocity were measured over active chinook, pink, and churn salmon and steelhead trout redds according to techniques established by Heiser (1971). Active redds were those with fish present. A Gurley current meter was placed at the upstream lip of each redd 0.5 ft above the bottom. From these measurements, the 80-percent ranges of depth and velocity for spawning Skagit River chinook, pink, and chum salmon and steelhead trout were established by elimination of the highest and lowest 10 percent of the measurements. 6.3.2 Spawner Observations Timing of spawning for chinook, pink, and chum salmon was investi- gated by the use of boat surveys to observe spawning fish and redds at regular intervals. Chinook salmon redds within the reference reaches were marked with numbered, large rocks when first observed and were then inspected during subsequent surveys to determine the length of time the redds remained visible. Aerial photographs were taken during the peak of the Skagit River chinook runs on September 18-19, 1975, and September 21, 1976, to determine spawner distribution between Newhalem and Sauk River. Redds were counted directly from the photographs. During the 1976 chum salmon run, boat surveys were made along the left bank between Newhalem and Sauk River to determine spawner distribution. An aerial survey was conducted on October 11, 1977, to determine the pink salmon spawning distribution in the mainstem Skagit between Rockport and Newhalem. The portions of the streambed which were utilized for spawning were outlined on aerial photographs. The area of the outlined sections were measured and compiled to determine relative utilization. Aerial surveys were conducted jointly by Washington Department of Game (WDG) and Fisheries Research Institute (FRI) in 1975, 1976, 1977, and 1978 to determine the number and distribution o'f steelhead redds in the Skagit and Sauk rivers (mainstems only) and assess the spawning timing. Observations were conducted during extreme low water periods to determine if chinook redds became exposed and to record the behavior of adult fish over the redds as the water became shallower. The areas chosen for these particular observations were ones in which the active chinook redds lay in unusually shallow water for this species. Spawner surveys were conducted on foot in Goodell Creek to determine the presence of adult salmon and steelhead trout. Three were done in - ~I _,, ~' - - - 171 1975, one in 1976, and six in 1977. The usual area surveyed in 1976 and 1977 extended from the highway bridge, upstream about 3/8 mi to a large pool. The three surveys made in 1975 and one in 1977 extended an additional 1 to. 2 mi upstream of the usual survey area. 6.3.3 Relationships of Spawnable Area to Discharge Four reference reaches were established for intensive studies. Selection of the reference reaches was based on the two following criteria: 1) Observed salmon spawning activity; and 2) river channel stability, to allow sampling over a range of discharges without major streambed shifting. The reference reaches ranged in length from 600- 700 ft and in width from 200-550 ft, depending on location and streamflow. Five transects and a staff gage were located in each reference reach. A systematic study of river depths and velocities was conducted over a variety of discharges. During a 2-year period, each reference reach was surveyed three to seven times. Sampling was conducted using techniques described by Collings (1974). Between 20 and 30 measurements of depth and velocity were made along each one of the five transects in a reach during each survey. Measurements were made from an 18.5-ft boat operated at the speed of the river current to maintain it in a stationary position. The distance between measurements was kept fairly uniform by two-way radio communication with the shore-based mapping crew using a telescopic ali dade. Velocity measur~ments were made with a direct readout Gurley current meter at a depth 0.5 ft above the bottom. The current meter was attached to a 30-pound lead weight which was lowered by a cable to a stationary position on the river bottom. River depth at the same point was measured with a graduated steel rod. The locations of all measurements were mapped by plane table methods. If the river level fluctuated more than 0.2 ft during the time a reference reach was surveyed, the data were discarded. A contour-graphic computer program, SYMAP (Dougenik and Sheehan 1977), was used to map the area of each reference reach over a range of river discharges (Stober and Graybill 1974). Each measurement of depth and velocity along a transect was classified with respect to the 80-percent preferred spawning ranges for each species. The mapped areas that fell within these ranges were designated the estimated spawnable area. 6.3.4 Potential Spawnable Area Twenty sample transects were established for estimation of the potential spawning area available to chinook, pink, and chum salmon and steelhead trout in the upper Skagit River (Fig. 6.1). These transects provided a systematic sample from which an average river width and spawnable width for the river could be obtained (Curtis 1959). Each transect was divided into sections by the 20-30 measurements of depth and velocity taken along its length. The distance in each section between the two measurements was divided into 1-ft intervals. The depth and velocity 172 measurements on either end of a section were averaged and prorated to each of the 1-foot intervals. Each interval was then classified with respect to the 80-percent preferred spawning ranges of depth and velocity for each salmonid species. Computations were then made of the total spawnable width in feet (Thompson 1972) and the percentage of each transect suitable for spawning. An estimate of the potential spawnable area available to each salmonid species in the upper Skagit was obtained by multiplying the mean spawnable width for each species by length of the river section in question. The length of river for any given sample transect was defined as the distance from the point midway between the transect and the adjacent upstream transect to the point midway between the transect and the adjacent downstream transect. An estimate of the total wetted area was obtained by multiplying the mean weighted river width by the river length. The mean river width was weighted by the distance around each transect. Discharge for both sample transect and reference reach surveys was obtained primarily from the three U.S. Geological Survey (USGS) gaging stations at Newhalem, above Alma Creek, and at ~iarblemount (Fig. 6.1). Except for Sample Transect 1 and Reference Reaches 2 and 3, which were very close to the gaging stations, discharge at all other sites was estimated by taking the flow at the nearest gage and adding to it the discharges of the appropriate major tributaries, depending 9n the distance downstream. Discharges for ungaged major tributaries were estimated 'by comparing the size of their drainage basins to the size of similar type drainage basins for gaged streams in the upper Skagit watershed. By multiplying the discharge of the gaged stream by the appropriate drainage basin size ratio, an estimate of the discharge of the ungaged stream was obtained. In 1975 before the installation of the USGS gaging station at Marblemount, discharges for surveys downstream of Marblemount were measured and computed directly using the standard stream method (Corbett 1962). The gaging station at Marblemount was installed in May 1976 and direct discharge measurements were then no longer required. 6.4 Results and Discussion 6.4.1 Spawning Depths and Velocities 6.4.1.1 Chinook Salmon. Depths and velocities were measured over 436 chinook salmon redds. Depths measured over chinook redds ranged from 0.6-7.1 ft (Fig. 6.4) with a mean of 2.89 ft (SD = 0.99). Velocities ranged from 0.5-4.9 ft/sec (Fig. 6.5) with a mean of 2.72 ft/sec (SD = 0.71). The 80-percent intervals were 1.7-4.2 ft for depth and 1.8-3.7 ft/sec for velocity. 6.4.1.2 Pink Salmon. Depths measured over 347 pink salmon redds ranged from 0.3 to 4.2 ft (Fig. 6.6) ~ith a mean of 1.66 ft (~D = 0.68). Velocities ranged from 0.1 to 4.3 ft/sec (Fig. 6.7) with a mean of - - ~' r I I"'"' (f.) ffi a=: ~ I ::J z - - -- CHINOOK SAU10N FREQUENCY 100 90 ~ 80 r---.--- 70 60 50 1- 40 1- r--- 30 1- r--- 20 ~ 10 F-- 173 PERCENT ~ - ,....-- ~21 18 16 14 -12 ~ 9 .--- 1-7 ~ 5 1-- 1-2 r----t---r--o.5 0 1.0 1.5 2.0 2.5 s.o 3.5 4.0 4.5 s.o 5.5 s.o s.s 7.0 7.5 SPAWNING DEPTH C FT l Fig. 6.4 Frequency distribution of chinook salmon spawning depths in the Skagit River measured at 436 redds. CHINOOK SRLttON FREQUENCY 70 so a 50 ~ ~ 20 . P"""- - 10 ~ I I 174 -- ,...__ .....- --~--- i-- .....- P"""- 1-- 1-- - 1-- ........, PERCENT 16 14 ~ 11 9 7 ~ 5 a 2 0 ·4 .a 1.2 1.s 2.0 2.4 2.a s.2 s.s 4.0 4.4 4.a SPAWNING VELOCITY ( FT /SEC l 0 Fig. 6. 5 Frequency distribution of chinook salmon spawning velocities in the Skagit River measured at 436 redds. - - - 17~ PINK SAU1DN FREQUENCY PERCENT 14 50 40 10 - 1- r-- 1- I .s r-- -- r-- 1-- - r-- I 1-- -- --- HI I 1.0 1.4 1.a 2.2 2.s 3.o 3.4 3.8 4.2 SPAWNING DEPTH C FT l 11 8 ~ 6 1- 0 Fig. 6.6 Frequency distribution of pink salmon spawning depths in the Skagit River measured at 347 redds. 176 PINK SAIJ10N f"REQUBCY PERCENT 14 50 1- 1- 10 . --, - 1-11 r-- r--""' 1--1-8 r-- r-- t--1-- r--1-6 1-- r--r-- ....- 1-3 t-- ..r .a ~ 0 1·2 1-6 2-0 2-4 2.8 3.2 s.s 4-0 4-4 SPAWNING VELOCITY CFT/SECl Fig. 6. 7 Frequency distribution of pink salmon spawning velocities in the Skagit River measured at 347 redds. ~. ~' .... , ~ ! tf!Pif':· 'F"' """ 260 234 208 182 t156 Q1 (j) 8130 D .- X a: W1Q4 0::: a: 78 52 26 CHINOOK SALMON REACH 3 213 330 CHINOOK SALMONn:~.-_____ I:....J REACH 4 297 264 231 t198 Q1 (j) D D165 D .- X a: W132 0::: a: 99 66 33 o~~--~~--~~~~--~~ a~~=-~~~~~~~~~ 0 1 2 3 4 5 6 7 8 DISCHARGE X 1000 (CFS) 1!1 TOTAL WETTED AREA C) ESTIMATED SPAI~NABLE AREA 0 2 4 6 8 10 12 14 16 18 20 DISCHARGE X 1000 fCFSJ POLYNOMIAL REGRESSION ON THE ESTif.1ATED SPA~~NABLE AREA Fig. 6.25 Relationship between estimated spawnable area, polynomial regression on the estimated spawnable area, and total wetted area for chinook salmon at Reference Reaches 3-4. 260 234 208 182 tts6 0 (/') §h3o Cl -X a: Wt04 a:: a: 78 52 26 PINK SALMON REACH 1 214 260 234 208 182 tts6 0 (/') -- 8t30 Cl -X a: W1Q4 a:: a: 78 52 26 PINK SALMON REACH 2 o~~--~~--~~--~~~ 0 1 2 3 4 5 6 7 8 DISCHARGE X 1000 CCFS) 0o . 1 2 3 4 s s 7 DISCHARGE X 1000 (CFS) ~ TOTAL WETTED AREA ~ ESTIMATED SPAWNABLE AREA POLYNOMIAL REGRESSION ON THE ESTIMATED SPAWNABLE AREA 8 Fig. 6.26 Relationship between estimated spawnable areat polynomial regression on the estimated spawnable area, arid total vetted area for pink •almcn at Paference Reaches 1-2. _, ""' -) ~. - - t~ ,,.... """ 260 PINK SALMON REACH 3 234 208 182 215 ,..... 330 PINK SALMON REACH 4 297 264 231 t156 t198 0 a (f) (f) ........ eh3o D Btss D --X X a: cr: W104 a::: W132 a::: a: cr: 78 52 26 o~~--~~--~~--~--L-~ 012 3 4 56 7 8 DISCHARGE X 1000 (CFSl [!] TOTAL WETTED AREA (!) ESTIMATED SPA\~NABLE AREA 99 '88 33 a~~~~~~~~~~~~ 0 2 4 8 8 1 0 12 14 16 18 20 DISCHARGE X 1000 (CfSJ POLYNOMIAL REGRESSION ON THE ESTIMATED SPAI~NABLE AREA Fig. 6.27 Relationship between estimated spawnable area, polynomial regression on the estimated spawnable area, and total wetted area for pink salmon at Reference Reaches 3-4. 26° CHUM SALMON REACH 1 234 208 182 216 26° CHUM SALMON REACH 2 234 208 182 t;: 156 t;: 156 C?J C!! (lj (lj B13o 0 eh3o Cl ..... ..... X X a: a: W104 0:::: W1Q4 0:::: a: a: 78 78 52 52 26 oL-~--~~--~~--~~--~ 0 1 2 3 4 5 6 7 8 DISCHARGE X 1000 £CFS) [!] TOTAL WETTED AREA C) ESTIMATED SPAWNABLE AREA 26 o~~--~~--~~--~~--~ 0 1 2 3 4 5 6 7 8 DISCHARGE X 1000 (CFSJ POLYNOMIAL REGRESSION ON THE ESTIMATED SPAWNABLE AREA Fig. 6.28 Relationship between estimated spawnable area, polynomial regression on the estimated spawnable area, and total wetted area for chum salmon at References Reaches 1-2. - - """' - ·- """' r~ ~ l. - - - 260 CHUM SALMON REACH 3 234 208 182 --t1s6 0 en ~ 8130 0 ..... X a: W104 Q:: a: 78 52 26 217 0o 1 2 3 4 5 6 7 8 DISCHARGE X 1000 CCFSl [!] TOTAL WETTED AREA 264 231 -t198 0 cn ~ 0 ol65 0 ..... X ~132 a: 99 66 33 CHUM SALMON REACH 4 o~~~~~~~~~~~-o 2 4 6 8 1 0 12 14 16 18 20 DISCHARGE X 1000 (CFSJ (!) ESTIMATED SPAWNABLE AREA POLYNOMIAL REGRESSION ON THE ESTIMATED SPAWNABLE AREA Fig. 6.29 Relationship between estimated spawnable area, polynomial regression on the estimated spawnable area, and total wetted area for chum salmon at Reference Reaches 3-4. 218 260 STEELHEAD TROUT REACH 1 234 208 182 t156 C3 (/) 8t3o Cl .... X a: W1Q4 0:::: a: 78 52 26 a~~--~~--~~--~~~~ 0 1 2 3 4 5 6 7 8 DISCHARGE X 1000 (CfSl [!] TOTAL WETTED AREA 260 STEELHEAD TROUT REACH 2 234 208 182 tt56 C3 (J) 8t3o 0 .... X a: W104 0:::: a: 78 52 26 o~~~~~--~~--~~~~ 0 '1 2 3 _4 5 6 7 8 DISCHARGE X 1000 [CFSJ (!) ESTIMATED SPA\~NABLE AREA POLYNOMIAL REGRESSION ON THE ESTIMATED SPAWNABLE AREA Fig. 6.30 Relationship between estimated spawnable area, polynomial regression on the estimated spawnable area, and total wetted area for steelhead trout at Reference leaches 1-2. ~. ~ I""', ',\ ,..,. _, - - - - - 260 234 208 182 STEELHEAD TROUT REACH 3 219 330 STEELHEAD TROUT,.,., ----t:.J REACH 4 297 264 231 · ttss 1-t....198- 0 01 en en ._ '-' 8130 0 8165 0 .... .... X X a: a: Wt04 W132 0::: 0::: a: 78 52 26 o~~--~~--~~--~~~ 0 1 2 3 4 5 6 7 8 DISCHARGE X 1000 CCFSl ~ TOTAL WETTED AREA a: (!) ESTH1ATED SPAWNABLE AREA 99 66 33 a~~~~~~~~~~~~ 0 2 4 6 8 1 0 12 14 16 18 20 DISCHARGE X 1000 {CFS) POLYNOMIAL REGRESSION ON THE ESTIMATED SPAWNABLE AREA Fig. 6.31 Relationship between estimated spa~qnable area, polynomial regression on the estimated spawnable area, and total wetted area for steelhead trout at Reference Reaches 3-4. 220 I I Q i j I cp i \ i ·; i, i I I l I I I ! !, \ -----~~----------t I .---- 1 i~ T'l'-----;i-- 3179ch . ....... 1 Cb~ r r ! i ! • I . I I I I . . $ :=_Cl:>_l_· c::;z,~-~~~: I \ I i i ! , \, I ! i ! ! ~ i I I i.' ----.1o1------r ~-----~.i~--~~~r-~· .. 12. Fig. 6.32 Plan views of Reference Reach 1 (Newhalem) showing changes and movement of the estimated spawnable area for pink salmon (shaded) at three discharges. '- ~ - - - - - 221 TALC MINE REACH CHINOOK SALMON 80ft • i • I • I \ \ I ' ' ' f I I I I I • I ' \ \ I I 1 \ ~-~.~------~. 1468 cfs .. I ' I • I i ' I ' I ' I ~ 1 -----------r---~i------1 \ i I • • ' • I I I f ' ' I I I ' ~ "I ~~ I ~ ' l ' I I I ' I I I I I , ~ \ I, ®dill ~~\' ________ db~··· 7690 ch Fig. 6.33 Plan views of Reference Reach 2 (Talc Mine) showing changes and movement of the estimated spawnable area for chinook salmon (shaded) at three discharges. 222 CHUM SALMON 80ft MARBLEMOUNT REACH f T . I . ' I • 4-_ I I 1914 ds I I I I I I 3938 cfs ' I I I I I I I I ' I I I I ' I I I I ' I I I • 7336 cfe Fig. 6.34 Plan views of Reference Reach 3 (Marblemount) showing changes and movement of the estimated spawnable area for chum salmon (shaded) at three discharges. - ~ ~ .. ] l Table 6.9 The peak spawning discharges and associated areas suitable for spawning for chinook, pink, and chum salmon, and steelhead trout, in each of the four reference reaches. The polynomial equations of the estimated spawnable area versus discharge curves are listed. Reference Peak discharge Maximum area Species Reach (cfs) (ft 2 X 10 3 ) Polynomial equation Chinook 1 4,295 69.66 y ~o.0021697x 2 + 18.6365x + 29633.9 2 3,171 66.85 y -0.0012877x2 + 8.166lx + 53901.2 3 2,784 115.08 y -0.0012018x2 -6.3444x + 133621.3 4 11,429 128.48 y -0.0017477x 2 + 42.114lx-124556.9 Pink 1 2,090 68.56 y 0.0008697x 2 17.0057x + 85687.1 2 1,468 59.76 ·Y 0.0023915x 2 26.7632x + 87860.6 3 1,914 55.36 y 0.0027547x 2 -31.2736x + 102860.7 4 11,429 61.36 y -0.0010236x 2 + 22.9018x -66679.0 Chum 1 2,090 90.44 y 0.002104lx 2 -30.4264x + 131387.8 2 1,468 46.05 y 0.0013544x 2 14.0749x + 62741.8 3 1,914 86.92 y = 0.003913lx 2 -46.5865x + 157327.0 4 11,429 145.72 y -0.0021899x2 + 49.638lx -135549.5 Steelhead 1 2,090 66.40 y 0.0010953x2 18.8777x + 86288.0 2 1,468 52.64 y 0.0018760x 2 21. 7496x + 78459.0 3 1,914 60.72 y 0.0027547x 2 31. 2736x + 102860.7 4 11,429 . 77.68 y -0.0013029x 2 + 29.2034x-85901.3 N N w 224 it less susceptible to SCL's regulated discharge influence. The value of Reference Reach 4 stemmed from its indication that whatever the exact peak spawning discharge in this lower section of the river study area was, it would be considerably larger than the 3,417 cfs figure described by Reference Reaches 1-3 further upstream. 6.4.5.2 Pink Salmon. The peak spawning discharges for pink salmon in Reference Reaches 1, 2, and 3 were 2,090, 1,468, and 1,914 cfs, respectively (Table 6.9 and Figs. 6.26 and 6.27). The mean peak spawning discharge for Reference Reaches 1-3 was 1,824 cfs. The peak spawning discharge for Reference Reach 4 was 11,429 cfs. The 80 percen~ ranges of depth and velocity for pink salmon indicated that they preferred slower spawning velocities and much shallower depths than those preferred by spawning chinook salmon. In a large river like the Skagit, both of these conditions were enhanced by relatively low discharges. From the SYMAP analysis, it was apparent that at higher flows the areas within the 80 percent ranges of preferred depth and velocity for pink salmon occurred primarily along the sides of the river. As the discharge decreased to l6wer levels, these areas tended to move into the channel and away from the sides. Once this had occurred,' a much greater area along the river bottom fell within the limits of the preferred range of depth and velocity and was classified as potentially spawnable. Thus, the greatest amount of spawnable area was available at a relatively low flow of 1,824 cfs. 6.4.5.3 Chum Salmon. The peak spawning discharges for chum salmon in Reference Reaches 1, 2, and 3 were 2,090, 1,468, and 1,914 cfs, respectively (Table 6.9 and Figs. 6.28 and 6.29). The mean peak spawning discharge for Reference Reaches 1-3 was 1,824 cfs. The peak spawning discharge at Reference Reach 4 was 11,429 cfs. The 80 percent range of velocity for chum salmon had indicated that chum salmon preferred slower spawning velocities than those preferred by chinook or pink salmon. In the Skagit slower spawning velocities were enhanced by low discharges. Field observations made in November 1975 and 1976 indicated the interacting effects of streamflow and spawning escapement on stream utilization. The mean monthly discharge from the Gorge Powerhouse in November 1975 was 7,081 cfs, while in November 1976, it was 3,692 cfs (USGS 1976 and 1977). The estimated spawning escapement (Table 5.3) for 1975 was 7,800 and for 1976 was 85,000. In November 1975 the chum salmon redds seen in the upper Skagit were mostly either in the side channels or next to the banks. Often these latter seemed to be located behind submerged stumps, boulders, and logs. These areas were apparently "preferred" by spawning chum salmon presumably because bottom velocities in other areas were too high. In November 1976, with the mean daily flows only about half those in November 1975 and with a spawning escapement about 11 times larger in 1976 than in 1975, large areas of chum salmon mass spawning were observed in the mainstem river away from the banks. The differences in the spawning areas utilized from 1 year to the next ~: - - - - - 225 were dramatic and many of the areas ·spawned in November 1976 contained no spawning chums in November 1975. Some of the chum salmon spawning areas selected at the lower discharges during 1976 were the same ones that had been utilized by spawning chinook salmon 1 to 2 months. 6.4.5.4 Steelhead Trout. The peak spawning discharge for steelhead trout in Reference Reaches 1, 2, and 3 were 2,090, 1,468, and 1,914 cfs, respectively (Table 6.9, Figs. 6.30 and 6.31). The mean peak spawning discharge for Reference Reaches 1-3 was 1,824 cfs. The peak spawning discharge at Reference Reach 4 was 11,429 cfs. The 80 percent ranges of depth and velocity for steelhead trout were similar to those for pink salmon. As with pinks the greatest amount of spawnable area was available at the relatively low flow of 1,824 cfs. 6.4.6 Potential Spawnable Area The 20 sample transects that were investigated were spread over 37.7 river miles of the Skagit River and provided a systematic sample from which an 'average river width and spawnable width for the river were obtained. The spawnable width of a sample transect was defined as that part of the total river width that was within the 80 percent ranges of preferred depth and velocity for each species. Spawnable width and river width were dependent on discharge. Discharge in the Skpgit varied greatly so the sample transect investiga- tions were confined ~o three discharge surveys within a subrange of the regulated flows that was most likely to be important to spawning Skagit River salmonids. This subrange of the regulated flows was derived from the mean da.ily natuJal flow of the Skagit at the Gorge Powerhouse for September and October and ranged from 900-6,025 cfs at that location. Natural flow was defined as the river flow if the reservoirs were not present. Natural flows were used because regulation on the Skagit River is a recent phenomenon in. an evolutionary time sense, and therefore Skagit River salmonid stocks have evolved under natural flow conditions except for the past 60 years. Natural flows for the river directly below Gorge Powerhouse were calculated on a daily basis by SCL and on a monthly basis by the USGS. The figures of both agencies agreed closely. Seattle City Light directly calculated natural flows from a combination of changes in water eleva·tion levels of the three upstream reservoirs and known powerhouse and spillway discharges. The September and October flows were used because chinook and pink salmon spawned during those months. The peak spawning discharges for chum and steelhead were contained within this range of flows even though they spawn at different times of the year. Thus, the mean daily natural flows of the Skagit for September and October directly below Gorge Powerhouse from 1961-1974 were ordered in terms of magnitude and the lowest and highest 2.5 percent were discarded to eliminate the extremes. The remaining discharges were then divided equally into three categories which were classified low, medium, and high 226 (Table 6.10). Each of the 20 sample transects was then surveyed on three separate occasions at a low, medium, and high flow. For locations on the Skagit River downstream of Gorge Powerhouse, the inflows of the major tributaries were added to the natural flow at Gorge, thus extending the classification system to any point on the Skagit downstream to the Baker River (Table 6.10). The results of the 60 depth and velocity surveys conducted over the 20 sample transects during a 2-year period are presented and discussed in the following sections (6.4.6.1-6.4.6.4) for chinook, pink, and chum salmon and steelhead trout. The discussion will deal with comparisons of several parameters to describe differences between various river sections. The basic parameters discussed include: 1) mean estimated spawnable width as calculated (in ft) and as percent of mean river width; 2) estimated spawnable area as calculated (in ft2) and as percent of wetted area. In addition the estimated spawnable area for the various river sections are presented as percent of the total estimated spawnable area between Newhalem and Baker River, as well as the estimated spawnable area per acre of wetted area (ft2/acre) and per river mile (ft2/mi). To facilitate the comparisons the sample transects were divided into two main groups: 1) those located above the Copper Creek Dam site; and 2) those below the Copper Creek Dam site. In addition the sample transects in these two main groups were further divided into four subgroups: 1) those located between Newhalem and the Copper Creek Dam site; 2) those between the Copper Creek Dam site and the Cascade River; 3) those between the Cascade River and the Sauk River; and 4) those between the Sauk River and the Baker River. The method precludes making statements about the degree of significance of the numerical differences discussed. 'we observed some areas in our Skagit River reference reaches that were potentially spawnable based on depth and velocity but were not utilized by spawning fish. In an attempt to assign significance to numerical differences presented, these results were compared to available observed distribution data. The relative importance of the various river sections is discussed based on potential and observed distribution data. For chum and steelhead comparisons were made for the sections between Newhalem and Baker River. For chinook and pink salmon comparisons were made for the sections between Newhalem and Sauk River with separate tables provided to facilitate the comparisons. In the sections that follow for the individual species the maximum and minimum values for the parameters are usually discussed. In addition comparisons were made between sections upstream and downstream of Copper Creek Dam site. Comparisons and discussions were usually based on the one discharge classification (either low, medium, or high) that provided the highest overall value even though for a single river section a value may have been higher for a different discharge category. This follows from the idea that a river must be managed as a unit and cannot be managed to - - - - 227 Table 6.10 Discharge classification system and sampling scheme for the 20 sample transects in the upper Skagit Riv.er. ~ River section Discharge ranges (cfs) -below or near: Low Medium High Gorge Powerhouse 900-1700 1700-2400 2400-6025 ~ Mean = 2200 cfs Newhalem Creek 1024-1824 1824-2524 2524-6149 + 124 cfs Goodell Creek 1196-1996 1996-2696 2696-6321 -+ 172 cfs USGS above Alma Creek 1544-2344 2344-3044 3044-6669 + 348 Bacon Creek 1769-2569 2569-3269 3269-6894 + 225 cfs USGS Marblemount 2156-2956 2956-3656 3656-7281 + 387 cfs ~- Cascade River 2911-3711 3711-4411 4411-8036 + 755 cfs -Sauk River 5664-6464 6464-7164 7164-10789 + 2753 cfs """' Baker River 7774-8574 8574-9274 9274-12899 + 2110 cfs - - - 228 optimize conditions in individuals river sections when the sections have differing qualities. 6.4.6.1 Chinook Salmon. The mean spawnable width for chinook salmon was greatest at a medium flow .. for five of the six river sections listed in Table 6.11. The analysis in Reference Reaches 1-3 predicted a peak spawning discharge of 3,417 cfs. The mean natural flow directly below Gorge Powerhouse for September and October was 2,200 cfs which was in the medium category. By prorating 2,200 cfs downstream to include tributary inflow, the discharge increased to 3,456 cfs just above the Cascade River (near Reference Reach 3). The mean of 2,200 cfs and 3,456 cfs was 2,828 cfs (i.e., the mean discharge for the Skagit between Gorge Powerhouse and the Cascade River). This figure was 589 cfs less than the 3,417 cfs predicted by the reference reach analysis. Between Newhalem and the Copper Creek Dam site the mean spawnable width for chinook salmon was 50 ft. This figure was the lowest one in any of the river sections listed in Table 6.11. The mean spawnable width was greatest at 139 ft in the river between the Copper Creek Dam site and the Cascade River. Above the proposed dam site there was an estimated spawnable area for chinook salmon of 2,678 ft2 x 103 at a medium flow, and below the dam there were 15,379 ft2 x 103 (Table 6.12). This difference was due in part to the larger wetted area below the dam site, but in addition there was proportionately more of it that was potentially spawnable for chinook salmon. While approximately 27 percent of the total wetted area below the proposed dam was classified as spawnable, 21 percent of the wetted area above the dam site was considered in this category (Table 6.12). This was partly because of the presence of a set of long, turbulent rapids above the dam site between RM 85.8 and RM 87.2 that provided very little spawnable area for salmon. The Skagit between the dam site and the Cascade River had the largest percentage, or 56 percent of its wetted area available to spawning chinook salmon (Table 6.12). The other three sections had similar percentages, 21-24 percent, of their total wetted area classified as spawnable. Table 6.13 compares the estimated chinook salmon spawnable area in each river section as a percentage of the total estimated spawnable area betwe~n Newhalem and the Baker River. The 10.2 mi of river between Newhalem and the Copper Creek Dam site contained a disproportionately small amount of estimated spawnable area than its length would indicate. This section contained 15 percent of the total chinook spawnable area while it comprised 27 percent of the river section length. Conversely, the sections between the Copper Creek Dam site and the Cascade River and between the Sauk River and Baker River contained a disproportionately large amount of estimated spawnable area than their lengths would indicate, 24 percent versus 16 percent and 34 percent versus 28 percent, respectively. The percentages for the remaining section, Cascade River to Sauk River, were similar. - - - - - ) Table 6.11 Mean spawnable widths for chinook, pink, and churn salmon in the Skagit River between Newhalern and the Baker River. Mean river width and the percentage of the mean river width suitable for spawning are listed. Mean Mean Mean Mean spawnable Percent spawnable Percent spawnable Discharge river width for of mean width for of mean width for classifi-width chinook river pink river churn River section cation (ft) (ft) width (ft) width (ft) Newhalern to Copper Low .209 37 17 34 16 71 • Creek Darn Site Medium 233 50 21 37 16 74 (10.2 rni) High 274 36 13 19 7 41 Copper Creek Darn Low 236 125 53 54 23 151 Site to Cascade R. Medium 249 139 56 45 18 103 (5.9 rni) High 293 62 21 23 8 44 Cascade River to Low 317 57 18 32 10 162 Sauk River Medium 355 83 24 30 9 144 (11.1 rni) High 378 53 14 32 8 69 Sauk River to Low 431 84 20 65 15 150 Baker River Medium 504 111 22 61 12 157 (10. 5 rni) High 527 144 27 73 14 184 Subtotal Copper Creek Darn Low 343 82 24 49 14 155 Site to Baker R. Medium 389 106 27 45 12 140 (27. 5 rni) High 417 90 22 45 11 108 Total Newhalern to Baker Low 307 70 23 45 15 132 River Medium 347 91 26 43 12 122 (37. 7 rni) High 378 75 20 38 10 90 .. J Percent of mean river width 34 32 15 64 41 15 N 51 N 1.0 41 18 35 31 35 45 36 26 43 35 24 Table 6.12 Estimated spawnable area for chinook, pink, and chum salmon in the Skagit River between Newhalem and the Baker River. Estimated wetted area and the percentage of the estimated wetted area spawnable are listed. Estimated Estimated Estimated Estimated chinook pink chum Discharge wetted spawnable % of spawnable % of spawnable % of classifi-area area wetted area wetted area wetted River section cation (ft 2 xl03) (ft 2 x10 3 ) area (ft 2 x103) area (ft2x103) area Newhalem to Copper Low 11,265 1,966 17 1,843 16 3,841 34 Creek Dam Site Medium 12,558 2,678 21 1,985 16 3,991 32 (10. 2 mi) High 14,758 1,940 13 1,005 7 2,182 15 Copper Creek Dam Low 7,339 3,887 53 1, 678 23 4,693 64 Site to Cascade Medium 7,764 4,337 56 1,415 18 3,204 41 River (5.9 mi) High 9,127 1,926 21 722 8. 1,384 15 N w 0 Cascade River to Low 18,580 3,348 18 1,848 10 9,490 51 Sauk River Medium 20,779 4,880 24 1,783 9 8,421 41 (11.1 mi) High 22,176 3,105 14 1,852 8 4,045 18 Sauk River to Low 23,877 4' 64 7 20 3,578 15 8,300 35 Baker River Medium 27,959 6,162 22 3,360 12 8, 718 31 (10.5 mi) High • 29,195 7,961 27 4,020 14 10,225 35 Subtotal Copper Creek Dam Low 49,797 11,883 24 7,104 14 22,483 45 Site to Baker R. Medium 56,502 15,379 27 6, 558 12 20,343 36 (27. 5 mi) High 60,499 12,992 22 6,595 11 15,654 26 Total Newhalem to Low 61,061 13,849 23 8,947 15 26,324 43 Baker River Medium 69,060 18,057 26 8,543 12 24,334 35 (37. 7 mi) High 75,257 14,933 20 7,599 10 17,836 24 J Table 6.13 Percentage of the total estimated spawnable area for chinook salmon in various sections of the Skagit River between Newhalem and the Baker River, compared to the percentage of the total river miles in each section. Spawnable area per acre of wetted area and spawnable area per river mile are also listed. Estimated Estimated % of total chinook Estimated chinook estimated % of spawnable area chinook Discharge spawnable chinook total per acre of spawnable area classifi-area spawnable river wetted area per river mile River section cation (ft 2xl03) area miles (ft2xl03/acre) (ft 2xl0 3/mi) Newhalem to Copper Low 1,966 14 27 7.5 193 Creek Dam Site Medium 2,678 15 27 9.3 263 (10. 2 mi) High 1,940 13 27 5.7 190 Copper Creek Dam Low 3,887 28 16 23.1 659 Site to Cascade Medium 4,337 24 16 24.3 735 River (5.9 mi) High 1,926 13 16 9.2 326 N Cascade River to Low 3,348 24 29 7.8 302 w ...... Sauk River Medium 4,880 27 29 10.2 440 (11.1 mi) High 3,105 . 21 29 6.1 280 Sauk River to Low 4,647 34 28 8.5 443 Baker River Medium 6,162 34 28 9.6 587 (10. 5 mi) High 7,961 53 28 11.9 7 58 Subtotal Copper Creek Dam Low 11,883 86 73 10.4 432 Site to Baker R. Medium 15,379 85 73 11.8 559 (27. 5 mi) High 12,992 87 73 9.4 478 Total Newhalem to Low 13,84 7 100 100 9.9 367 Baker River Medium 18,057 100 100 11.4 479 (37. 7 mi) High 14,933 100 100 8.6 396 232 Based upon the amount of estimated spawnable area per acre of wetted area available, the Skagit above the dam site averaged 9.3 ft2 x 103/acre while below the dam site it averaged 11.8 ft2 x 103/acre (Table 6.13). Based upon the amount of spawnable area per river mile, the Skagit above the dam site averaged 263 ft2 x 103/mi compared to the river below the dam site which averaged 559 ft2 x 103/mi (Table 6.13). The river between the proposed dam site and the Cascade River contained the largest amount of spawnable area per river mile, 735 ft2 x 103/mi, compared to 479 ft2 x 103/mi, the mean value for the Skagit between Newhalem and the Baker River. Another important comparison was between the percentage of the estimated spawnable area in the various river sections and the actual percentage of chinook salmon that spawned there based on the aerial photograph counts. It was previously stated that chinook redd counts were not made below the Sauk River because of the turbidity. If the sample transects below the Sauk River were excluded from the spawnable area analysis, then at a medium flow 23 percent of the total estimated chinook salmon spawnable area was located above the dam site (Table 6.14). In 1975 and 1976, 29.4 percent and 25.5 percent, respectively, of all the chinook salmon redds counted from aerial photographs were in this area (Table 6~5). The river section between the Copper Creek Dam site and the Cascade River contained 36 percent of the total chinook spawnable area above the Sauk; in 1975 and 1976, 35.3 percent and 45.8 percent, respectively, of the total chinook salmon redds were counted in this area. The river between the dam site and the Sauk River contained 77 percent of the chinook salmon spawnable area above the Sauk (Table 6.14) while in 1975 and 1976, respectively, 70.6 percent and 74.4 percent ~f the total chinook salmon redds were counted in this same area (Table 6.5). The order of relative importance for.the potential and observed distribution data for river sections between Newhalem and Sauk River was identical. The magnitudes of the percent distribution were in general agreement for the two sets of data. 6.4.6.2 Pink Salmon. The mean spawnable width for pink salmon was greatest at a low flow for the Skagit River between Newhalem and Baker River, although not strongly so (Table 6.11). The analysis in Reference Reaches 1-3 predicted a peak spawning discharge for pink salmon of 1,824 cfs. This figure was included in the low flow range for most of the river sections between the Gorge Powerhouse and the Cascade River (Table 6.10), which was also the area covered between Reference Reaches 1-3. The mean discharge of the low flow category for the area directly below the Gorge Powerhouse was 1,331 cfs. By prorating 1,331 cfs downstream to include tributary inflow, the discharge increased to 2,587 cfs just above the Cascade River. The mean of 1,331 cfs and 2,587 cfs was 1,959 cfs. This figure was only· 135 cfs more than the },824 cfs predicted by the reference reach analysis. The greatest mean spawnable width was 65 ft, and it occurred between the Sauk River and the Baker River (Table 6.11). The sections with the - - ~' ) l l Table 6.14 Percentage of the total estimated spawnable area for chinook salmon in various sections of the Skagit River between Newhalem and the Sauk River, compared to the percentage of the total river miles in each section. Estimated % of total chinook estimated % of total Discharge spawnable chinook river miles classifi-area spawnable area above River section cation (ft 2 xl03) above Sauk R. Sauk R. Newhalem to Copper Low 1,966 21 38 Creek Dam Site Medium 2,678 23 38 (10. 2 mi) High 1,940 28 38 Copper Creek Dam Low 3,887 42 22 Site to Cascade R. Medium 4,337 36 22 (5. 9 mi) High 1, 926 28 22 Cascade River to Low 3,348 36 41 Sauk River Medium 4,886 41 41 (11.1 mi) High 3,105 45 41 Subtotal Copper Creek Dam Low 7,236 79 63 Site to Sauk R. Medium 9,217 77 63 (17 .1 mi) lfigh 5,031 72 63 Total Newhalem to Low 9,202 100 100 Sauk River Medium 11,895 100 100 (27. 2 mi) High 6,971 100 100 } 1',) w w 234 smaller mean spawnable widths for pink salmon were between the Cascade River and Sauk River and between Newhalem and Copper Creek Dam site with mean spawnable widths of 32 ft and 34ft, respectively. Above the dam site there was an estimated spawnable area of 1,843 ft2 x 103 and below there was 7,104 ft2 x 103 (Table 6.12). The spawnable area above the dam site was 16 percent of the wetted area available while the spawnable area below the dam site comprised 14 percent of the wetted area. Twenty-one percent of the estimated spawnable area was above the dam site, and the 10.2 river miles in question comprised 27 percent of the 37.7 mi of the Skagit studied (Table 6.15). Conversely, the other 79 percent of the estimated spawnable area was below the proposed dam. Based upon the amount of estimated spawnable area per acre of wetted area available, the Skagit above the dam site averaged 7.1 ft2 x 103/acre, while below the proposed dam site it averaged 6.2 ft2 x 103/acre (Table 6.15). However, based upon the amount of spawnable area ~er river mile, Skagit above the Copper Creek Dam site averaged 181 ft x 103/mi while from the Copper Creek site to the Baker River it averaged 258 ft2 x 103/mi (Table 6.15). The.river section with the largest amount of estimated spawnable area per acre of wetted area was between Copper Creek Dam site and Cascade River (10.0 ft 2 x 103/acre) and per river mile was between Sauk and Baker rivers (341 ft2 103/mi). By comparison the Newhalem to Baker River section as a whole had 6.4 ft2 x 10 3 /acre and 273 ft2 103/mi. Comparisons were made between the estimated spawnable area for pink salmon in river sections between_Newhalem and the Sauk River and.the observed spawner distribution in those sections during 1977. Approxi- mately one-third of the total estimated pink spawnable area was_contained in each of the three sections between Newhalem and Sauk River (Table 6.16). The spawner dis.tribution survey conducted in 1977 (Table 6.7) indicated that 39.5 percent of the spawned area was observed above the Copper Creek Dam site, 47.5 percent between Copper Creek Dam site and Cascade River, and 13.0 percent between Cascade and Sauk rivers. The order of rela~ive importance for the sections between Newhalem and Sauk River were identical for both data sets. Agreement between the pairs of values was not good, however, but as indicated in Sec. 6.4.3.2 may relate to flow conditions during the incubation phase of the life cycle. 6.4.6.3 Chum Salmon. The mean spawnable width for chum salmon in the river as a whole was largest for the low discharge classification (Table 6.11). The greatest mean spawnable width of 162 ft occurred in the Skagit between the Cascade and Sauk rivers (Table 6.11). The ~mallest mean spawnable width for chum salmon was 71 ft between Newhalem and the Copper Creek Dam site. Above the dam there was an estimated spawnable area of 3,841 ft2 x 103 and below there was 22,483 ft2 x io3 (Table 6.12). The spawnable area above the dam site was 34 percent of the total wetted area available while the spawnable area below the dam site comprised 45 percent of the total wetted area. ~- - - ~I Table 6.15 Percentage of the total estimated spawnable area for pink salmon in various sections of the Skagit River between Newhalem and the Baker River, compared to the percentage of the total river miles in each section. Spawnable area per acre of wetted area and spawnable area per river mile are also listed. Estimated % of total Estimated pink pink estimated % of spawnable area Estimated pink Discharge spawnable pink total per acre of spawnable area classifi-area spawnable river wetted area per river mile River section cation (ft 2 xl0 3 ) area miles (ft 2 xl0 3/acre) (ft 2 xl03 /mi) Newhalem to Copper Low 1843 21 27 7.1 181 Creek Dam Site Medium 1985 23 27 6.9 195 (10.2 mi) High 1005 13 27 3.0 99 Copper Creek Dam Low 1678 19 16 10.0 284 Site to Cascade Medium 1415 17 16 7.9 240 N w River (5.9 mi) High 722 10 16 3.4 122 lJ1 Cascade River to Low 1848 21 29 4.3 166 Sauk River Medium 1783 21 29 3.7 161 (11.1 mi) High 1852 24 29 3.7 167 Sauk River to Low 3578 40 28 6.5 341 Baker River Medium 3360 39 28 5.2 320 (10.5 mi) High 4020 53 28 6.0 383 Subtotal Copper Creek Dam Low 7104 79 73 6.2 258 Site to Baker R. Medium 6558 77 73 5.1 238 (27.5 mi) High 6595 87 73 4.7 240 Total Newhalem to Low 8947 100 100 6.4 237 Baker River Medium 8543 100 100 5.4 227 (37.7 mi) High 7599 100 100 4.4 202 Table lj.l6 Percentage of the total estimated spawnable area for pink salmon in various sections of the Skagit River between Newhalem and the Sauk River, compared to the percentage of the total river miles in each section. % of total Estimated pink estimated pink % of total Discharge spawnable area spawnable area river miles River section classification (ft 2 xl0 3 ) above Sauk R. above Sauk R. Newhalem to Copper Low 1843 34 38 Creek Dam Site Medium 1985 38 38 (10. 2 mi) High 1005 28 38 Copper Creek Dam Low 1678 31 22 Site to Cascade R. Medium 1415 27 22 (5.9 mi) High 722 20 22 Cascade River to Low 1848 34 41 Sauk River Medium 1783 34 41 (11.1 mi) High 1852 52 41 Subtotal Copper Creek Dam Low 3526 66 63 Site to Sauk R. Medium 3198 62 63 (17.1 mi) High 2574 72 63 Total Newhalem to Low 5369 100 100 Sauk River Medium 5183 100 100 (27. 2 mi) High 3579 100 100 ~---------------- N w 0\ - - - 237 There was 14.8 ft2 x 103 of spawnable area per acre of wetted area above the dam site and 19.6 ft2 x 103 of spawnable area per acre of wetted area below the dam site (Table 6.17). The total amount of chum salmon spawnable area might have been overestimated due to the wide 80 percent preferred spawning depth range mentioned in Sec. 6.4.1.5. However, the relative percentage of spawnable area in different sections of the Skagit would probably not have been affected. Fifteen percent of the estimated spawnable area for chum salmon occurred above the proposed dam site, and the 10.2 mi of the Skagit in question represented 27 percent of the river miles studied (Table 6.17). This percentage was similar to the percentage of the estimated chi- nook salmon spawnable area above the dam site which ranged from 13-15 percent (Table 6.13). The section predicted to be most important for chum salmon spawning was the 11.1 mi between the Cascade and Sauk rivers. In this stretch there were 855 ft2 x 103 of spawnable area per mile compared to 698 ft2 x 103 of spawnable area per mile for the entire Skagit between Newhalem and the Baker River (Table 6.17). From Newhalem to the proposed Copper Creek Dam site, the Skagit averaged 377 ft 2 x 103 of spawnable area per mile for chum salmon, while from the Copper Creek site to the Baker River it averaged 818 ft2 x 103 of spawnable area per mile. The river section with the highest potential and observed utilization (Table 5.17 and Sec. 6.4.3.3, respectively) was between the Cascade and Sauk rivers, but it was more heavily utilized than predicted (36 percent versus 65.6 percent). Overall, the sections upstream of Cascade River were less utilized than predicted but direct comparisons could not be made because the divisions between sections was at Copper Creek Dam site (RN 84.0) for potential and "canyon" (RM 89) for observed. The section between Sauk and Baker rivers was also less utilized than predicted. 6.4.6.4 Steelhead Trout. The mean spawnable width for steelhead trout in the river as a whole was largest for the low discharge classification (Table 6.18). The greatest mean spawnable width of 76 ft occurred in the Skagit between the Copper Creek Dam site and the Cascade River. Above the dam site, there was an estimated spawnable area of 1,224 ft2 x 103 and below there was 8,375 ft2 x 103 (Table 6.18). The spawnable area above the dam site was 11 percent of the total wetted area available while the spawnable area below the dam site was 17 percent of the total wetted area. There were 4.7 ft2 x 103 of spawnable area per acre of wetted area above the darn site and 7.3 ft2 x 103 of spawnable area per acre of wetted area below the dam site (Table 6.19). · Thirteen percent of the estimated spawnable area for steelhead trout occurred above the proposed dam site, and the 10.2 mi of the Skagit in question represented 27 percent of the river miles studied (Table 6.19). Table 6.17 Percentage of the total estimated spawnable area for chum salmon in various sections of the Skagit River between Newha,lem and the Baker River, compared to the percentage of the total river miles in each section. Spawnable area per acre of wetted area and spawnable area per river mile are also listed. Estimated % of total Estimated chum chum estimated % of spawnable area Estimated chum Discharge spawnable chum total per acre of spawnable area classifi-area spawnable river wetted area per river mile River section cation (ft 2xl0 3 ) area miles (f t 2 xl0 3 I acre) (ft 2 xl0 3 /mi) Newhalem to Copper Low 3,841 15 27 14.8 377 Creek Dam Site Medium 3,991 16 27 13.8 391 (10.2 mi) High 2,182 12 27 6.4 214 Copper Creek Dam Low 4,693 18 16 27.9 795 Site to Cascade Medium 3,204 13 16 18.0 543 River (5.9 mi) High 1,384 8 16 6.6 235 Cascade River to Low 9,490 36 29 22.3 855 Sauk River Medium 8,421 35 29 17.6 759 (11.1 mi) High 4,045 23 29 7.9 365 Sauk River to Low 8,300 32 28 15.2 790 Baker River Medium 8, 718 36 28 13.6 830 (10.5 mi) High 10,225 57 28 15.2 974 Subtotal Copper Creek Dam Low 22,483 85 73 19.6 818 Site to Baker R. Medium 20,343 84 73 15.8 740 (27.5 mi) High 15,654 88 73 11.3 569 Total Newhalem to Low 26,324 100 100 18.8 698 Baker P,iver Medium 2~.J34 100 100 15.3 645 (37. 7 mi) High .536 100 100 10. ::_', 6,.73 ••-----·-·---~•oo.--·-'"-~-------·-•--••·• --~·-----~----~-----~---------------~---------.. N !.,.) CD .. ) l Table 6.18 Mean spawnable width and estimated spmmable area for steelhead ttout in the Skagit River between Newhalem and the Baker Rlver. Mean river width, estimated wetted area, and the percentage of the mean river width and estimated wetted area suitable for spawning are listed. Mean Estimated He an spawnable Percent Estimated steelhead Percent Discharge river width for of mean wetted spawnable of classifi-width steelhead river area area wetted River section cation (ft) (ft) width (ft 2 xl0 3) (ft 2 xl0 3) area Newhalem to Copper Low 209 23 11 11,265 17 224 11 Creek Dam Site Medium 233 32 14 12,558 1,715 14 (10.2 mi) High 274 18 7 14,758 973 7 Copper Creek Dam Low 236 76 32 7,339 2,356 32 Site to Cascade R. Medium 249 48 19 7,764 1,478 19 (5. 9 mi) High 293 22 8 9,127 690 8 Cascade River to Low 317 43 14 18,580 2,543 14 N w Sauk River Medium 355 26 7 20' 779 1,542 7 \.() (11.1 mi) High 378 27 7 22,176 1 593 7 Sauk River to Low 431 63 14 23,877 3,475 14 Baker River Medium 504 59 12 27,959 3,244 12 (10.5 mi) High 527 100 19 29,195 5,517 19 Subtotal Copper Creek Dam Low 343 58 17 49,797 8,375 17 Site to Baker R. Medium 389 43 11 56,502 6, 264 11 (27.5 mi) High 417 54 13 60,499 7,S06 13 Total Newhalem to Baker Low 307 48 16 61,061 9,599 16 River Medium 347 40 12 69,060 7,979 12 (37.7 mi) High 378 44 12 75,257 8,773 12 Table 6.19 Percentage of the total estimated spawnable area for steelhead trout in various sections of the Skagit River betwe2n Newhalern and the Baker River, compared to the percentage of the total river miles in each section. Spawnable area per acre of wetted area and spawnable area per river mile are also listed. River section Newhalem to Copper Creek Dam Site (10. 2 mi) Copper Creek Darn Site to Cascade River (5.9 mi) Cascade River to Sauk River (11.1 mi) Sauk River to Baker River (10. 5 mi) Subtotal Copper Creek Dam Site to Baker R. (27. 5 mi) Total Newhalem to Baker River (37. 7 mi) .D Discharge classifi- cation Low Medium High Low Medium High Low Medium High Low Medium High Low Medium High Low Medium High Estimated steelhead spawnable area (ft 2 xl0 3) 1224 1715 973 2356 1478 690 2543 1542 1593 3475 3244 5517 8375 6264 7800 9599 7979 8773 % of total estimated steel head spawnable area 13 22 11 25 19 8 27 19 18 36 41 63 87 79 89 100 100 100 % of total river miles 27 27 27 16 16 16 29 29 29 28 28 28 73 73 73 100 100 100 Estimated steel head spawnable area per acre of wetted area (ft 2 xl0 3 /acre) 4.7 5.9 2.9 14.0 8.3 3.3 6.0 3.2 3.1 6.4 5.1 8.2 7.3 4.8 5.6 6.8 5.1 5.1 Estimated steelhead spawnable area per river mile (ft 2 xl03/rni) 120 168 95 399 251 117 229 139 144 331 309 525 305 228 284 255 212 233 - - - 241 This percentage was similar to the percentage of the estimated chinook spawnable area, 13-15 percent, and chum spawnable area, 12-16 percent, above the dam site (Tables 6.13 and 6.17, respectively). The river section predicted to be most important for steelhead trout spawning was the 5.9 mi between the Copper Creek Dam site and the Cascade River whereas the highest observed utilization was in the Cascade to Sauk section (Sec. 6.4.3.5). Between the project site and the Cascade River there were 399 ft2 x 103 of spawnable area per mile, compared to 255 ft2 x 103 of spawnable area per mile for the entire Skagit between Newhalem and the Baker River (Table 6.19). From Newhalem to the proposed Copper Creek Dam site, the Skagit averaged 120 ft2 x 103 of spawnahle area per mile for steelhead troutA whereas from the Copper Creek site to the Baker River it averaged 305 ftL x 103 of spawnable area per mile (Table 6.19). A comparison was made between the percentage of the estimated spawnable area for steelhead trout in each river section above the Baker River (Table 6.19) and the percentage of steelhead redds observed on the aerial survey counts (Table 6.4). Thirteen percent of the total estimated spawnable area for steelhead was located above the proposed dam site, while between 1975 and 1978, 2 percent of the steelhead redds (peak counts) were located between Newhalem and Bacon Creek (1.1 mi below the dam site). The river section between Copper Creek Dam site and the Cascade River contained 25 percent of the total steelhead spawnable area above the Sauk; between 1975 and 1978, 20 percent of the steelhead trout redds were observed between Bacon Creek and the Cascade River. The river between the dam site and the Baker River contained 87 percent of the steelhead trout spawnable area above the Baker River (Table 6.19), while between 1975 and 1978, 98 percent of the steelhead trout redds were counted between Bacon Creek and the Baker River. The order of relative importance of river sections between Newhalem and Baker River based on potential and observed distribution data was dissimilar. Agreement between the pairs of values was poor except for the section between Copper Creek Dam site and Cascade River. 6.4.6.5 Potential Spawnable Area and Escapement. Over the entire range of discharges occurring during the 1976 chinook, pink, and chum salmon spawning seasons, no more than 6 percent for chinook, 23 percent for pink, and 14 percent for chum salmon of the total estimated spawnable area in the reference reaches was ever actually utilized. A report by the WDF (Ames and Phinney 1977) stated: "Escapement goals for chinook salmon have been based on both historical escapements and the amout of available spawning area. In most cases, the spawning area available to chinook greatly exceeds the amount needed to support rational spawning escape- ments." This statement probably held true for pink and chum salmon as well. That was because all the spawnable areas discussed in this report were potential spawnable areas, and this meant salmon would find these areas suitable for spawning based solely on depth and velocity. Only a portion of these areas was ever actually utilized. Thus, an optimum or even reasonable salmonid escapement estimate could not be obtained by 242 simply taking the amount of potential spawnable area estimated in this study and dividing by the average spawning pair territory or redd size. - - - - - - - 243 7.0 INCUBATION AND EMERGENCE 7.1 Introduction Water temperatures in the Skagit River have been altered by the completion of Ross, Diablo, and Gorge dams. Burt (1973) has estimated that the effect of the three reservoirs has been to elevate the river temperature above predam conditions during all times of the year, hut more so during late fall and winter when salmon eggs are incubating in the gravels of the river bottom (Fig. 7.1). A similar conclusion was reached for the fall and early winter period by assuming that the Sauk and Cascade rivers are models of predam temperature conditions (Fig. 2.27). Since the incubation period of salmon is controlled by the accumulation of temperature units (TU's) (cumulative degree-days above 32 °F)1 to hatch and complete yolk absorption, an increase in water temperature will accelerate embryonic development. The situation for steelhead trout is not so clearcut. Burt (1973) estimated higher temperature throughout the steelhead incubation period, t-1arch-August (Fig. 7.1), while comparisons between Skagit and Sauk-Cascade temperature were mixed during that period (Fig. 2.27). . The change in thermal regime suggested that salmon eggs and alevins incubating in the upper Skagit must be exposed to higher temperatures than under predam conditions. Although yolk absorption was believed to occur earlier at higher temperatures, it has been inferred that chinook fry may spend a longer period of time in the gravel between yolk absorption and emergence. If this latter behavior prevents or inhibits feeding, emerging chinook fry could be in poorer condition than in the natural situation, thus affecting survival. If, as a result of elevated temperature, salmon fry emerged earlier than in the natural situation they may be exposed to less favorable environmental conditions, again, possibly affecting their survival. The objectives of these studies were to assess the effects of the present temperature pattern on salmonid egg incubation and timing of fry emergence and to predict the potential survival effects of different emergence timings resulting from different temperature regimes. Preliminary analysis indicated that river temperature changes predicted for Ross High Dam might have the greatest potential effect on eggs and alevins of chinook salmon. Chinook salmon were the primary focus of our field studies through mid-1977 and so the major portion of this section concerns them. Additional field studies were conducted during the 1977-1978 incubation period for chinook, pink, chum, and coho salmon. 1centrigrade temperature units = Fahrenheit temperature units x 5/9. 52 50 48 w ~42 1--a: 0::: UJ ~40 w I-- 38 36 34 \ ~ I'- JAN / ~ ~ / ' ~ 10-year mean water temperature observed 6 miles below Newhalem / // / """ "' "' ~ / / "\ """ r'\.. / v/ \ // / \ / / Mean temperature prediction with ~ no reservoirs present. Skagit --.- I'-.. River 6 miles below Newhalem. / / _./ FEB MAR MAY JUN AUG SEP OCT NOV Fig. 7.1 Observed and forecast water temperatures for Skagit River (taken from Burt 1971, 1973). .J ""' \ \ [\.. ~ m:r: - - - 245 7.2 Literature Review There is little information in the literature on the temperature requirements of chinook salmon eggs to hatching, and more importantly, to emergence under natural conditions. Some measurements have been taken of TU's required to hatching under hatchery conditions. Host of this work has been done using constant temperatures. A notable exception is Seymour (1956) who exposed Sacramento, Entiat, Skagit, and Gr~en rivers chinook salmon eggs to varying temperature regimes, simulating the natural pattern by beginning exposure on high but decreasing temperature as would be found in a river during the fall, then bottoming out at about 39 °F to represent winter conditions, and finally increasing temperatures to simulate spring conditions. In one lot, Seymour subjected Skagit chinook eggs to a temperature regime averaging 49.4 °F which is close to the 47 °F experienced by Skagit chinook eggs in 1974. Seymour found that 974 TU's were required to 50 percent hatching of Skagit River chinooks under that temperature regime. Seymour concluded that the rate of development of Skagit eggs was intermediate between the faster developing Sacramento River chinook eggs and the slower developing Entiat River eggs. Published literature on TU's to emergence proved difficult to find. Hatchery information was not applicable because most hatchery managers only note the most obvious stages of development, hatching and "swim-up." When alevins are incubated in substrate, "swim-up" coincides with yolk absorption, but under hatchery conditions it usually does not (Brannon 1974). The literature information concerning timing of the early life history of summer-fall chinook salmon is summarized in Table 7.1. Published studies of timing of the early life history of chinook under natural conditions are limited to Johnson (1974), Gebhards (1961), Wales and Coots (1954), Reimers and Loeffel (1967) and the reports of the Washington Department of Fisheries (WDF) on Columbia River spawning channels. Skagit River chinook eggs experimentally incubated at the lfarblernount Salmon Hatchery by WDF were estimated to require 1,700 TU's to yolk absorption (Johnson 1974). Gebhards (1961) sampled a natural redd of a chinook salmon in the Lemhi River, Idaho, to determine development timing. He marked the redd in late August close to the peak spawning time of September 1, 1957. He states, "On December 12, a small section of gravel was dug from the spawning riffle and 34 sac fry (nine of them dead) were collected.'' It was his belief that hatching had occurred in early December. After placing a trap over the redd on January 21, 1958, he captured the first emergents from the redd on February 15 and the greatest number on February 19. The last fry to emerge did so on March 4. Reimers and Loeffel (1967) calculated a mean egg deposition date, incubation period, hatching time and emergence date for fall chinooks in five selected tributaries of the Columbia River. Their calculations were Table 7.1 Summary of literature information on the -:iming of the early life history of summer-fall chinooks under natural conditions. Location Peak spawning Peak hatching Lemhi River, Early September Early December Idaho Klaskanine River, Washington Fall Creek, California McNary Spawning Channel, Columbia River Mid-September Late September- end Octoberl Late September Wells Summer Late October Chinook Spawning Channel, Columbia R. Skagit incubated at Marble- mount Hatche Mid-November lNo peak estimate was available. Peak emergence Mid-February Early February January 1- April 1 1 December Mid-February Temperature units required to emergence 1,800 1,600 Author Gebhards (1961) Reimers and Loeffel (1967) Wales and Coots (1954) Chambers (1963) Allen, Turner an~ Moore (1969-1972) Johnson 3 2 1974 estimate of temperature units required to yolk absorption at Marblemount Salmon Hatchery~ Washington State Department of Fisheries. 3Pers0nal communication. - 247 made with TU information which they received through personal commu- nication and not from data they collected. They mention that the TU requirements they used were for summer chinook, but they do not mention the exact number of TU's or from which stock they were derived. Of the five rivers they examined, the one which came closest (in timing of early life history) to approximating the Skagit was the Klaskanine River. Their estimate of peak spawning in this river was mid-September, peak hatching mid-November and peak emergence in early February. They report using manthly records of U.S. Geological Survey (USGS) data but they fail to give the exact temperatures used. Wales and Coots (1954) studying the efficiency of chinook spawning in Fall Creek, California, found spawning to occur over approximately 1 month from late September to the end of October. No estimate of hatching time or the temperatures to which the eggs were exposed was given. However, trapping of downstream migrants showed emergence to occur from about January 1 to April 1. Reports by WDF on Columbia River chinook salmon spawning channels also provide data on the early life history timing of chinooks. Chambers (1963), in his summary report of the McNary Dam Experimental Spawning Channel, reports that two races of chinook spawned in the channels--an upriver race and a local race. The upriver race could have been a mix of many different populations, and therefore, will not be considered here. The local race of chinooks began spawning in mid-September and peaked in late September-early October. Emergence peaked in December when fry had accumulated approximately 1,800 TU's. Work done in 1968-1969 at ~Jells Summer Chinook Salmon Spawning Channel (Allen, et al. 1969) is of interest. Eggs of summer chinook which had historically spawned in the Wells Dam vicinity were planted on October 22 in the spawning channel. Samples removed periodically showed that between February 13 and February 27, all alevins had absorbed their yolks. Development to this point required approximately 1,600 TU's. Because of the limited amount of published work on development rates of salmon eggs and alevins at different temperature regimes, it was necessary that we conduct further studies specific to the Skagit salmon populations and river temperature conditions to determine the effects of altered temperature regimes on embryonic development, emergence timing, and survival. 7.3 Study Area These studies were conducted in the mainstem Skagit River between Newhalem and Rockport and in the lower Cascade and Sauk rivers (Fig. 7.2). Four study stations were established in the Skagit River: Station 1--1/4 mi below Newhalem Station 2--8 mi below Newhalem j_ 0 l 2 i 4 I I I I Scale: ~in.~l mi. SAUK STATION _/ Fig. 7.2 Study stations on the Skagit, Sauk, and Cascade rivers. - - - - 249 Station 3--1 mi above the confluence of the Cascade Station 4--1/2 mi below the confluence of the Sauk One study station each was established in the Cascade River about 1/2 mile from its mouth and in the Sauk River about 5 mi from its mouth. Because it would be most affected by any dam-related temperature changes, major emphasis was given to the river immediately downstream from the present dam sites between Newhalem and the confluence of the Cascade. This area was characterized by pools and riffles with a predominantly gravel riverbed and was used to varying extents by spawning chinook, pink, and chum salmon and steelhead trout (Sec. 6.4.3). 7.4 Materials and Methods 7.4.1 Embryonic Development Adult salmon were netted out of the upper Skagit River during the 1974, 1975, 1976, and 1977 spawning seasons and transported to the Marblemount Hatchery. With the assistance of personnel from the hatchery, 1,000 to 3,500 eggs were removed from "ripe" females and fertilized with milt from males. The procedure used was as follows: 1. Eggs stripped from female. 2. Hilt added to eggs, mixed throughly and allowed to stand for about 5 min. 3. Eggs rinsed several times to remove excess sperm, blood clots, etc. 4. Let stand for 30-45 min. to water harden. 5. Transferred to appropriate size container and packed in cooler for transporting to incubation site. Eggs from individual female chinook salmon were taken and fertilized on September 16, 1974, and September 3, 1975. Eggs were taken from four females over the course of the spawning season in 1976 and fertilization dates were September 8 and 16, and October 6 and 12. Eggs were taken from two chinook, four pink, four chum, and two coho female salmon during the fall of 1977. Fertilization dates for eggs from the respective species were: September 6 for chinook, October 5 and 13 for pink, December 7 and 16 for chum, and December 16 for coho. Egg diameter and egg weight were determined after water hardening from samples of approximately 35 eggs from each female in 1976 and 1977. Individual egg diameter was determined by measuring the total length of an egg sample as they lay in a groove and dividing by number of eggs. The weight of the total sample, determined using a top-loading Hettler balance (to 0.01 g), was divided by the number of eggs to determine individual egg weight. In 1974 fertilized eggs were held overnight at the Marblemount Hatchery and planted the following day while in 1975, 1976, and 1977 they were transported immediately to the incubation sites for placement. 250 At the Skagit, Sauk, and Cascade river incubation sites 50-80 eggs were placed in each of 6-12 perforated plastic containers (17-ounce capacity) containing gravel substrate. These, in turn, were placed in performated incubation boxes which rested on top of the river bottom and were secured to stable objects on the bank by a cable. In 1974 and 1975, 17-x 25-x 4-inch plywood incubation boxes were used which accommodated 12 plastic containers. Spaces between the containers were filled with rocks to prevent them from shifting, to break up and reduce the flow entering the boxes and flowing through the baffles, and to help hold down the boxes. To improve the sturdiness and durability, boxes of similar dimensions were constructed in 1976, using "expanded metal" for bottom, sides, and baffles, and with a hinged plywood lid to reduce light penetration. Incubation boxes were monitored periodically during the incubation periods. The sampling schedule in 1974 and 1975 was to take samples every 200 TU's after blastopore formation, which requires 250-300 TU's, to monitor embryonic development. However, flow conditions dictated when containers could be removed and the original schedule could not be strictly followed in 1974. Station 1, near Newhalern, proved to be the most successful incubation site because of its close proximity to the darns. Flow regulation by Gorge Powerhouse protected the site from flooding conditions and because much of the silt settles out in the upstream reservoirs, siltation in the egg containers was not a major problem as it had been at the downstream sites. In 1975, after losing one box to vandalism in late October, the others were destroyed by flooding in early December (Fig. 2.4). Based on the experience and information gained in 1974 and 1975, Station 1 was the only Skagit site used in 1976 and 1977, and sampling was commenced just prior to the anticipated time for hatching and yolk asbsorption. Sample size was varied at the individual sites depending on egg and/or alevin mortality to insure that enough organisms would be available for the entire sampling period. Lengths of individual fish were measured and fish were weighed in 5-rnm length groups and condition factor was calculated at a later time. Specimens were preserved in Stockard's Solution in 1974 for later inspection to determine developmental stage. To determine time of hatching in 1976 and 1977, specimens were removed, counted (hatched versus not hatched), and returned to the incubation boxes. Specimens to determine time of yolk absorption were preserved in 10 percent formalin and examined at a later time for the presence or absence of yolk. The USGS recording thermometer, approximately 6 mi below Newhalem near Alma Creek, provided average daily temperature for the Skagit River in addition to Ryan 30-day continuous recording thermographs owned by Seattle City Light (SCL), located in the Sauk and Cascade rivers. ~. ~. - - ,"""" - 251 Chinook eggs were transported to the College of Fisheries Hatchery in Seattle for incubation studies in 1976. These eggs were also placed in perforated plastic containers containing gravel substrate, but were suspended in hatchery incubation troughs. The water temperature was controlled and maintained approximately 5 °F higher than measured in the Skagit near Newhalem. Samples were collected and preserved as indicated above for the 1976 river studies. Temperature data were obtained from a Ryan 30-day continuous recording thermograph placed in the hatchery trough. In 1977, incubation studies were conducted at the College of Fisheries Hatchery in Seattle using approximately 600 eggs from each of four chum and two coho female salmon from the Skagit River. Approximately 200 eggs from each female were incubated in each of three constant temperature water bathes. Cooled and filtered municipal water was mixed with ambient Lake Washington water to maintain constant temperatures of approximately 2.5 oc (36.5 Of), 4.5 °C (40.1 °F), and 6.5 °C (43.7 °F). Eggs were placed in cylindrical containers with screen bottoms and open tops. The cylinders were placed in a plywood flow-through trough where water entered at the base of the trough, flowed upward through the screen bottom of the cylinder through the eggs within the cylinder, then flowed out over the top of th~ cylinder. Gravel substrate was added to the cylinders when hatching began to provide more natural conditions for the developing alevins. Screen fences and tops were added to the cylinders to prevent the escape of alevins as they became more active. The troughs were covered with black plastic so that eggs and alevins were ·incubated in darkness. The experiments were monitored daily and egg and/or alevin mortali- ties were counted and removed. Samples were collected and preserved, as indicated above for the 1976 and 1977 river studies. Temperature was measured daily at several points in each trough using a hand-held analy- tical thermometer. Specimens were examined to determine time to hatching and time to yolk absorption. For hatching it was simply noted whether the eggs were hatched or not hatched. The percentage of hatched fish was calculated for each sample and the date when 50 percent of the eggs had hatched was considered the mean hatching date. The presence or absence of yolk was determined by examining the body cavity of the fish by dissection. Yolk absorption was said to be completed when no yolk could be found. \Vhen 50 percent of the fish had absorbed their yolks, the mean yolk absorption date had been reached. By summing the daily TU's over the period from fertilization to mean hatching and mean yolk absorption the respective TU requirements were obtained. Based on TU requirement and the date of peak spawning determined in these studies for Skagit chinook, the theoretical timing to mean yolk absorption was determined for various temperature regimes. These included temperature regimes for the past several years in the Skagit; the mean, 252 1953-1977, Skagit River regime; recent and long-term temperature regimes for the Cascade and Sauk rivers; and the predicted regime assuming Copper Creek Dam was present. Similar comparisons were made for pink and chum salmon, and steelhead trout based on their spawning times and estimates of their TU requirements. 7.4.2 Timing of Emergence Chinook eggs from the same lot as those planted in the incubation boxes were buried in manmade redds on September 17, 1974. Two hundred eggs were buried at each of four stations in areas where natural spawning was observed. These "artificial" redds were then covered with 5-x 8-ft fry emergent nets, similar to the one described by Phillips and Koski (1969). The purpose of burying these eggs was to determine when fry of a known age would emerge from the gravel and this would provide information on whether chinook fry delay emergence after yolk absorption. To determine when chinook fry from naturally spawned eggs emerged from the gravel a natural redd at each station was marked on September 20, 1974, and it was noted that spawning had ceased on all four redds. Station 4 was subjected to a freshet in November (primarily caused by flooding of the Sauk) which obliterated the marked redd there, thus preventing it from being covered with an emergent net. The other three natural redds were covered with emergent nets like those used on the "artificial" redds, only larger--8 x 10 ft. Portions of the samples of captured fry were measured for length and weight, preserved, and later checked for remaining yolk. Emergent nets were placed over manmade and natural chinook redds in the fall of 1975 and 1976 to obtain further information about timing of emergence. High streamflow during early Decembe·r 1975 and early January 1977 (Fig. 2.4 and 2.6, respectively), rendered them unusable and the studies were terminated. By applying the TU requirement for yolk absorption to a chinook spawning curve, an emergence curve was constructed for the upper river (Newhalem to the Cascade River). "Theoretical emergence" was assumed to occur when 50 percent of the fish in a sample from incubation box studies had absorbed their yolks. The emergence data of fry from redds built on each day were calculated by summing the number of TU's from each day of spawning until eggs deposited on that day had accumulated the theoretical number of TU's required for emergence. In this way a curve showing the emergence period and the relative number of emerging fry was constructed. The information used for timing of chinook spawning in the upper Skagit River was obtained from spawning observations (number of new redds per day) obtained during 1976 (Sec. 6.4.2.1, Fig. 6.14). A portion of the chinook eggs fertilized on October 12, 1976, was incubated in gravel substrate at the College of Fisheries Hatchery to determine the timing of emergence and associated TU's under the warmer hatchery conditions. Two hundred and fifty eggs were buried in gravel substrate in each of two compartments (26 x 12 x 6 inches) in a hatchery ~I ~I - 253 incubation trough. This was the same trough used for embryonic develop- ment studies described earlier and so was under the same temperature regime. The compartments immediately downstream of the ones containing gravel and eggs were without gravel and were separated from the gravel compart- ment by a baffle with a l-inch space at the bottom. The compartments without gravel were covered with black plastic to provide cover for newly emerged fry while the ones with gravel were left uncovered. Fry could, thus, emerge from the gravel at their own volition and move downstream into the nongravel compartment. The experiment was checked approximately daily and the fish in the nongravel compartment were removed, measured for length and weight, preserved, and later checked for remaining yolk. 7.5 Results 7.5.1 Embryonic Development 7.5.1.1 Chinook Salmon. Eggs taken from five female chinook salmon (one from the 1974 run and four from the 1976 run) were incubated in the Skagit River near Newhalem to determine date to mean hatching and to mean yolk absorption. In general, the temperature regime during the 1974-1975 incubation period was similar to that of the 23-year average, while in 1976-1977 it was warmer (Fig. 2.32). The results of these studies are summarized in Table 7.2. Hatching probably began in mid-November 1974 when the eggs had accumulated about 940 °F TU's (Fig. 7.3), although this was not specifically determined because of inadequate sampling frequency. The date to mean yolk absorp- tion was February 28, 1975. By summing TU's for the period September 16, 1974 to February 28, 1975, it was determined that chinook in the incubation boxes required approximately 1,913 °F TU's to yolk absorption (Fig. 7.3). For the 1976-1977 cycle the range of dates to mean hatching was November 5 to December 16, 1976 (Table 7.2). The range of TU's required was 968 to 1,000 TU's and the mean was 981 TU's (SD = 14). On the average it took 61 days from fertilization to hatching. The range of dates to mean yolk absorption for the 1976-1977 cycle was February 6 to March 13, 1977 (Table 7.2). The number of TU's required ranged from 1,769 to 2,153 (Fig. 7.4). The mean number required from both years' data was 1,929 °F TU's (SD = 153). On the average 151 days passed between fertilization and yolk absorption. The range was from 139 to 165 days. The results of incubation studies conducted for the 1977-1978 cycle are summarized in Tables 7.3 and 7.4. For eggs from two female chinook salmon fertilized on September 6 and incubated in the Skagit at Newhalem, the date of mean hatching was October 31 with 958 TU's required. Hean incubation temperature to mean hatching was higher than observed in 1976 (Table 7 .2). tO ..... a::: w m 3000 2500 f52000 t-o... w (I) 2: 0 fl:t5oo (I) ' ;::) t- LLJ > 254 ----YOLK ABSORPTION HATCHING ~1000~------------~ a: ....J ::> z: ;::) u 500 SEPT OCT NOV DEC I I I I I I I I I I I I I I JAN FEB MAR APR Fi 7 3 Cumulative temperature units (Fahrenheit) experienced by Skagit g. • River chinook eggs in the Station 1 incubation box, commencing September 16, 1974. tfl/16'!1!!, Female. 111-74 . #1-76 #2-76 113-76 114-76 Table 7.2 Date fertilized 9-16-74 9-8-76 9-16-76 10-6-76 10-12-76 Mean J Summary of incubation studies for 1974-75 and 1976-77 cycles for eggs from Skagit River chinook salmon incubated near Newhalem. Shows dates, temperature units, number of days and mean temperature to mean hatching and to mean yolk absorption. To mean hatching To mean yolk absorption Date TU's If of Mean Date TU's If of (oF) days temp. (oF) days (oF) Not specifically determined 2-28-75 1913 165 11-5-76 979 58 48.9 2-9-77 2153 154 11-13-76 968 58 48.7 2-6-77 1994 143 12-7-76 975 62 47.7 2-22-77 1769 139 12-16-76 1000 65 47.4 3-13-77 1814 152 981 . 61 1929 151 Standard deviation 14 153 Mean temp. (oF) 43.6 1'-J 46.0 lJ1 lJ1 45.9 44.7 43.9 256 2500 (() 1- :Z200D / "' :::l ,. .. "' LLI ,."' a:: :::l 1-a: a:: LLI ~1500 w 1- 1--w :I: z w ~1000 a: lL.. LLI > -1-.a: _J :::l SOD :c :::l u SEP OCT NOV DEC JAN FEB MAR APR DATE Fig. 7.4 Cumulative temperature units (Fahrenheit) experienced by Skagit River chinook eggs in the Station 1 incubation boxes, commencing September 8 and 16, and October 6 and 12, 1976. Observed dates and associated TU requirements of mean yolk absorption are shown. - ~. -· """' -' ··' ~ ~ 1 -] Table 7.3 Hatching data from 1977-1978 incubation studies for eggs from Skagit River chinook, pink, churn, and coho salmon incubated in the Skagit (near Newhalern), Cascade, and Sauk rivers. Shows dates, temperature units, number of days, and mean temperature to mean hatching. Skagit near Newhalem Cascade Sauk Date TU's II of Mean TU's # of Mean TU's # of Mean S!!ecies Female fertilized Date ("F) days temp("F) Date ("F) dpys temp("F) Date {"F) da:zs tern[)( "F} Chinook 111-77 9/ 6/77 10/31/77 958 55 49.4 11/15/77 954 70 45.6 11/ 8/77 982 63 4 7.6 U2-'77 9/ 6/77 10/31/77 958 55 49.4 11/12/77 922 67 45.8 11/ 6/77 964 61 4 7.8 mean = 958 mean z 938 mean • 973 Pink 111-77 10/ 5/77 12/25/77 971 81 44.0 1/14/78 838 101 40.3 1/14/78 880 101 40.7 112-77 10/ 5/77 12/24/77 962 80 44.0 1/14/78 838 101 40.3 -1/20/78 923 107 40.6 N 113-77 10/13/77 1/ 9/78 946 88 42.8 mean = 838 mean = 902 lJ1 114-77 10/13/77 1/ 7/78 932 86 42.8 ...... mean m 953 Chum 111-77 12/ 7/77 -3/31/78 817 114 39.2 -3/31/78 657 114 37.8 -3/31/78 818 114 39.2 112-77 12/ 7/77 -3/31/78 817 114 39.2 113-77 12/16/77 4/ 5/78 781 110 39.1 114-77 12/16/77 4/12/78 849 117 39.3 mean = 816 Coho 111-77 12/16/77 4/ 5/78 781 110 39.1 112-77 12/16/77 4/ 4/78 772 109 39.1 mean = 777 Table 7.4 Yolk absorption data from 1977-1978 incubation studies for eggs from Skagit River chinook, pink, chum, and coho salmon incubated in the Skagit (near Newhalem), Cascade, and Sauk rivers. Shows dates, temperature units, number of days, and mean temperature to mean yolk absorption. Skagit near Newhal~ Cascade Sauk Date TU's I of Mean TU'a I of Meso TIJ's II of Mean Sf'ecies Female fertilized Date ("F) days temf'( "F) Date ("F) days temE( "F) Date ("F) days temJ2("F) Chinook 111-77 9 I 6/77 3/15/78 2040 190 42.7 4/ 4/78 1801 210 40.6 High mortality 112•77 9/ 6/77 3/19/78 2070 194 42.7 4/ 4/78 1801 210 40.6 High mortality Mean 2055 Mean 1801 Pink 01-77 10/ 5/77 4/ 8/78 1700 185 41.2 4/ 8/78 1374 185 39.4 4/10/78 1602 187 40.6 112-77 10/ 5/77 4/ 8/78 1700 185 41.2 4/11/78 1402 188 39.5 4/12/78 1625 189 40.6 Mean 1388 Mean 1614 113-77 10/13/77 4/18/78 1669 187 40.9 N \.11 114-77 10/13/77 4/21/78 1699 190 40.9 -~ 00 Mean 1692 Chum 111-77 12/ 7/77 6/ 4/78 1597 179 40.9 5/30/78 1244 174 39.1 5/24/78 1486 168 40.8 112-77 12/ 7/77 6/ 2/78 1566 177 40.8 113-77 12/16/77 6/ 4/78 1517 170 '•0.9 114-77 12/16/n 6/ 7/78 1564 173 41.0 Mean 1561 Coho 111-77 12/16/77 5/21/78 1312 156 40.4 112-77 12/16/77 5/19/78 1284 154 40.3 Mean 1298 ) - - - - 259 The dates to mean yolk absorption for the 1977-1978 cycle were March 15 and 19 with an average of 2,055 TU's required. The mean incubation temperature was lower than observed in 1974-1975 and 1976-1977 (Table 7.2). The number of TU's required by chinook salmon to mean yolk absorption in 1977-1978 (2,040 and 2,070 TU's) was within the observed chinook range (1,769-2,153 TU's), but was higher than the mean TU require- ment (1,929 TU's) determined in previous studies. For the 1976-1977 cycle, comparisons were made between number of TU's required and mean incubation temperature and between number of TU's required and egg size to determine the relative influence of these two factors on developmental rate. For eggs from different females (Table 7.2) the correlation coefficient for TU's to hatching versus mean temperature was r = .66 and for TU's to yolk absorption versus mean temperature was r = .71. While not strongly correlated, developmental rate for eggs from different females appeared to be influenced by mean temperature during incubation. However, alevins from Females #1-76 and #2-76 incubated under similar mean temperatures, 46.0 and 45.9 °F, differed markedly in TU's to yolk absorption, 160 TU's. Alevins from Females #1-74 and #4-76 where mean temperature was 43.6 and 43.9 °F, respectively, differed in TU's to yolk absorption by about 100 TU's. In this case the eggs incubated at cooler mean temperature required more TU's than those incubated at warmer mean temperature. Weight and diameter were not measured for eggs from Female #1-74. Individual egg diameter and egg weight were determined for eggs from each of the four female chinook salmon taken in 1976 (Table 7.5). Both diameter and weight were highly correlated to number of TU's required to mean yolk absorption with correlation coefficients (r) of .97 and 1.00, respectively. They were not well correlated, however, with numbers of TU's to mean hatching (r = .28 and .43, respectively). Eggs from chinook Female #3-76 were incubated in the Cascade and Sauk rivers and at the College of Fisheries Hatchery in Seattle, as well as in the Skagit River at Newhalem during the 1976-1977 cycle. The water temperature was lower in the Cascade and Sauk rivers from mid-October 1976 to early February 1977 than it was in the Skagit, while at the University of Washington Hatchery it was maintained at about 5-6 °F higher (Fig. 7.5). It was assumed that egg diameter and weight were not varia- bles in this experiment since the eggs were from an individual female and were presumably of similar size at the various sites. The results of this experiment are presented in Table 7.6. Compared to the Skagit where mean hatching occurred December 7, the effect of the cooler Cascade and Sauk rivers was to retard development by about 40 days so that mean hatching occurred in mid-January 1977. The effect of the warmer conditions at the University of Washington Hatchery was to accel- erate development by 15 days and mean hatching occurred on November 22, 1976. The average number of TU's required to mean hatching was 958 TU's. These same trends were observed to mean yolk absorption also. Overall, the date to mean yolk absorption was delayed from February 22, in Table 7.5 Female No. 1-76 2-76 3-76 4-76 260 Egg weight, egg diameter, number of temperature units required to mean yolk absorption and to mean hatching, and mean incubation temperature to yolk absorption, for eggs taken from four chinook females in 1976. Egg weight (g) 0.441 0.383 0.278 0.287 Egg diameter (nnn) 9.16 8.77 7.43 7.96 TU's to hatching (oF) 979 968 975 1000 TU's to yolk absorption (oF) 2153 1994 1769 1814 Mean incubation temperature to yolk absorption (oF) 46.0 45.9 44.7 43.9 - - :1 ~I ·. -H 60 58 56 54 38 36 34 SAUK ____ ___, l U.W. HATCHERY SKAGIT at NEWHALEM 32~~~----~------~------~------~------~-----J------~~----~ AUG SEP OCT 1976 NOV DEC JAN FEB MAR 1977 Fig. 7.5 Daily temperatures in degrees Fahrenheit for the Skagit (near Newhalem); Sauk, and Cascade rivers and University of Washington Hatchery from August 1976 to April 1977. APR Table 7.6 To Date Location Skagit River 12-7-76 Cascade River 1-18-77 Sauk River 1-15-77 u .w. Hatchery 11-22-76 Mean Standard deviation Summary of incubation studies ·using eggs from chinook female 113-76 fertilized on October 6, 1976 and incubated at four site& Shows location, dates, temperature units, number of days and mean temperature to mean hatching and to mean yolk absorption. mean hatching To mean yolk absorEtion TU's II of Mean Date TU's II of Mean (oF) days temp. (OF) days temp. (OF) (oF) 975 62 47.7 2-22-77 1769 139 44.7 949 104 41.1 4-19-77 1710 195 40.8 888 101 40.8 4-14-77 1662 190 40.7 1019 47 53.7 1-21-77 2069 107 51.3 958 1803 55 183 .t N 0'\ N - - - - 263 the Skagit to April 19 and 14 in the Cascade and Sauk, respectively (Fig. 7.6). This amounted to a delay of 56 days in the Cascade and 51 days in the Sauk. Development at the University of Washington Hatchery was accelerated and date of mean yolk absorption was advanced by 32 days from February 22 to January 21, 1977 (Fig. 7.6). Eggs from Female #3-76 incubated under the cooler temperature regimes of the Cascade and Sauk rivers required less TU's, 1,710 and 1,662 TU's, respectively, than eggs from the same female incubated in the Skagit River with 1,769 TU's (Table 7.6). The converse was true and to a greater t:xtent for eggs from the same female incubated under the warmer tempera- ture regime at the University of Washington Hatchery at 2,069 TU's. This suggests that the developmental rate was altered by a compensating mechanism, probably physico-biochemical, and thus, the effects of the warmer and cooler temperature regimes on eggs from a single Skagit chinook female were dampened. The compensation was only partial, h0\>7ever, but the shift was toward the Skagit condition in all three cases. If eggs at the other sites had required the same number of TU's as at the Skagit site, namely, 1,769 TU's, then yolk absorption would theoretically have occurred on April 25 and 24, in the Cascade and Sauk, ·respectively, and on January 2, at the Univeristy of Washington Hatchery (Fig. 7.6, dashed vertical lines). Thus, the date to mean yolk absorption was shifted 6 days (10 percent) in the Cascade, 10 days (16 percent) in the Sauk, and 19 days (37 percent) at the University of Washington Hatchery from the respective theoretical dates of mean yolk absorption toward the date to mean yolk absorption for the Skagit. The greatest shift occurred for the warmer condition than for the cooler ones. However, the temperature differential was also greater between Skagit and University of Washing- ton Hatchery, at 6.6 °F than between Skagit and cooler regimes; for Cascade River 3.9 °F, and for Sauk River 4.0 °F (Table 7.6). The relationship between the results from the Skagit River and the cooler Cascade River was similar in 1977-1978 to those described above for 1976-1977 -less TU's were required and the date to mean yolk absorption was later in the Cascade than in the Skagit. As in the previous year's studies these data also suggest TU compensation (Fig. 7.7). No data were obtained in the Sauk because of high mortality resulting from heavy siltation in the incubation boxes. The results of incubation studies conducted at the University of Washington Hatchery for the 1976-1977 cycle are presented in Table 7.7. The 6-day difference between fertilization date for eggs from Females #3-76 and #4-76 was maintained to mean hatching which occurred on November 22 and 28, 1976, respectively. Both required about 1,000 TU's. The dates to mean yolk absorption were January 21 and 29, 1977, a difference of 8 days and about 2,050 TU's were required (Table 7.7 and Fig. 7.8). At a higher mean temperature (51.3 °F) eggs from Female #3-76 required about 40 TU's more than eggs from Female #4-76 incubated at a lower temperature (50.6 °F). Contrary to results presented in Table 7.5, more TU's were required to yolk absorption by the smaller eggs from Female #3-76 and less were required by the larger eggs from Female #4-76. (/) I- 2500 :Z2000 =:I LLJ a:: =:I 1-a: a::: LLJ ~1500 LLJ I-._ ..... w ·::c z w g§ 1000 a: LL- LLJ > ..... 1-a: ..J. ~ 500 =:I u 264 / ./ ~------------------------------~/ 1769 TU's I I I I I. OCT I I I I I I NOV 1976 DEC I I / / I 19 days. JAN DATE FEB MAR APR 1977 Fig. 7.6 Cumulative temperature units (Fahrenheit) experienced by chinook eggs from female II 3-76 at selected sites, cormnencing October 6, 1976. Observed dates and associated TU requirements of mean yolk absorption are indicated by vertical and horizontal solid lines. Theoretical dates to mean yolk absorption assuming 1769 TU are indicated by vertical dashed lines. - ~- - - - - (J) l- 2500 z2000 ;::::) w 0:::: ;::::) 1-cr: 0:::: w ~1500 LlJ I- I-...... lLJ ::r: z. LlJ ~1000 cr: LL... w > ...... 1-cr: _J ~ 500 ~ u Fig. 7.7 265 2055 TU 's SEP · OCT NOV DEC 1977 JAN FEB MAR 1978 I I I I I 27 dayS! APR Cumulative Fahrenheit temperature units experienced by chinook eggs incubated in the Skagit and Cascade rivers, commencing September 6, 1977. Observed dates and associated TU requirements to mean yolk absorption are indicated by vertical and horizontal solid lines. Theoretical dates to mean yolk absorption assuming 2,055 TU's are indicated by vertical dashed line. MAY Table 7.7 Date Female fertilized 113-76 10-6-76 114-76 10-12-76 J Summary of incubation studies for eggs from Skagit River chinook salmon incubated at the University of Washington Hatchery for 1976-.77 cycle. Shows dates. temperature units, number of days and mean temperature to mean hatching and to mean yolk absorption. To mean hatching To mean yolk absorption Date TU's II of Mean Date TU's II of (oF) days temp. (OF) days (''F) 11-22-76 1019 47 53.7 1-21-77 2069 107 11-28-76 990 47 53.1 1-29-77 2032 109 N Mean 0\ "' temp. (oF) 51.3 50.6 - - - - - - 267 2500 ~ / ~ r-------------------------------------------~r-~/ zzooo ::::;) LLJ a:: ::::;) ~ a: a:: LLJ ~1500 LLJ ~ ~ ...... LLJ J: z. LLJ g§ 1000 a: LL... LLJ > ...... ~ a: _J ~ 500 ::::;) u / I / I / / / / / I I / / / / / / / / / / / / / / / / / / / / / / • / o~~------~------~--------~------L-~------~ OCT NOV DEC DATE JAN FEB Fig. 7.8 Cumulative temperature units (Fahrenheit) experienced by Skagit River chinook eggs at the U.W. Hatchery, commencing October 6 and 12, 1976. Observed dates and associated TU requirements of mean yolk absorption are shown. 268 In summary, the developmental rate and TU requirements to hatching and yolk absorption for Skagit chinook salmon were shown to be influenced by mean incubation temperature and egg size which when taken together sometimes showed confounding effects. Eggs from a single female, and presuflably of similar size, clearly showed different TU requirements to yolk absorption when incubated at mean temperatures differing by from 4.0 to 10.6 °F (Table 7.6). TU requirements to yolk absorption for eggs from four females which ranged in weight from 0.441-0.287 g and in diameter from 9.16 to 7.96 mm were shown to be highly correlated to egg weight and diameter (Table 7.5). Thus, changes in developmental rate appeared to be controlled by mean incubation temperature when it was sufficiently different and egg size was similar. Conversely, changes in developmental rate appeared to be controlled by egg size when it was sufficiently different and mean incubation temperature was similar. The relative degree of influence for each of these two factors probably depended on the relative amount of difference for each factor. The factor showing the greater difference would probably have the greater influence on changing the developmental rate. If both factors were sufficiently different at the same time then presumably the influences could be additive or in opposition. Contradictory results were more likely when factor dif- ferences were small. Length and weight were determined for alevins (yolk remaining) and fry (yolk absorbed) taken from the incubation boxes. Measurements were usually taken over the period from several weeks prior to mean yolk absorption to several weeks after. From the length and weight measure- ments, condition factor was calculated according to the formula: Condition factor = 5 Weight (g) x 10 3 Length (mm) Yolk, when it wa.s present in the fish, was included in the weight measurement and, therefore, was included.in the calculation of condition factor. See Sec.·8.0 for a more detailed discussion of condition factor. Length, weight, and condition factor data are presented in Table 7.8 for juvenile chinook salmon sampled from the incubation box located near Newhalem during 1975 and in Tables 7.9, 7.10, and 7.11 for juveniles from the four females and sampled during 1976-1977 at the various incubation sites. As a general rule the mean length increased slightly over the first several sampling periods then remained fairly constant through the remainder of the sampling period, but sometimes decreased slightly for the last couple of samples. The mean .weight typically remained fairly con- stant through the first half of the sampling period or increased slightly, while during the latter half, it usually decreased. The general trend for condition factor was to decrease through the sampling period. At or near the time of mean yolk absorption the - - ~- - 269 Table 7. 8 Length, weight, and condition factor, of juvenile chinook salmon from one female and sampled from 1"'-incubation box located in Skagit·River near Newhalem, 1974-75. Sample Mean Mean Condition size length weight factor Date (rnm) (g) 1975 1-8 25 37.4 .4 7 .91 2-4 7 40.0 .58 .91 2-11 18 39.9 .52 . 81 2-18 36 40.9 .54 .78 3-4 29 41.7 .52 .72 3-11 27 40.8 .51 .72 3-18 47 41.0 .51 .73 ,._ 4-1 36 40.8 .50 . 73 4-8 20 41.1 .44 .64 4-22 41 40.3 .41 .63 .. --. Mean 40.5 .49 .74 ,_ - - - I""'• Table 7.9 Length, weight, and condition factor of juvenile chinook salmon from four females and sampled from incubation boxes located in Skagit River near Newhalem, 1976-77. Mean Mean Mean Mean Sample length weight Condition Sample length weight Condition Date size (mm) {g} factor size {mm} {g2 factor 1976 Female /!1-76 Female /12-76 12-17 46 38.8 0.539 0.923 12-23 44 39.4 0.542 0.886 12-29 36 40.2 0.544 0.837 1977 1-4 30 40.9 0.564 0.824 1-10 21 41.5 0.576 0.806 1-14 43 41.7 0. 572 0.789 1-19 31 41.6 0.553 0.768 1-24 43 41.9 0.560 0.761 16 40.1 0.494 0.766 1-28 46 42.2 0.568 0.756 15 40.8 0.507 0.746 2-2 15 41.9 0.542 0.737 40.5 N 15 0.479 o. 721 ...... 0 2-7 20 41.8 0.531 0. 727 15 40.7 0.482 o. 715 2-11 19 40.2 0.451 0.694 Mean 40.9 0.554 0.811 40.4 0.481 0. 727 1977 Female #3-76 Female /14-76 1-28 49 35.1 0. 315 0.728 2-2 14 36.3 0.360 0.753 2-24 49 36.4 0.309 0.641 2-28 25 36.7 0. 311 0.629 25 38.4 0.390 o. 689 3-2 25 36.8 0.310 0.622 25 37.9 0.379 0.696 3-4 40 36.9 0.306 0.609 33 38.2 0.369 0.662 3-7 44 36.4 0.301 0.624 28 38.4 0.373 0.659 3-10 34 36.8 0.306 0.614 21 38.1 0.380 0.687 3-14 25 38.5 0.368 0.645 3-17 26 37.9 0.352 0.647 3-21 25 38.5 0.364 0.638 3-24 25 38.2 0.358 0.642 3-28 25 38.5 0.347 0.608 Mean 36.4 0.308 0.624 38.2 0.367 0.662 l ) ) Table 7.10 Length, weight, and condition factor of juvenile chinook salmon from female #3-76 and sampled from incubation boxes located in Cascade and Sauk rivers, 1976-77. Cascade River Sauk River l1ean Mean Mean Mean Sample length weight Condition Sample length weight Date size (nun) (g) factor size (nun) (g) 1977 3-21 10 35.1 0.277 4-4 10 35.7 0.316 4-7 10 36.0 0. 311 0.667 25 36.3 0. 339 4-11 10 36.2 0.319 0.672 25 36.2 0.318 4-14 10 36.3 0.315 0.659 25 36.1 0.311 4-18 15 36.3 0. 311 0.650 25 36.4 0.309 4-22 15 36.2 0.296 0.624 19 36.5 0. 293 4-26 15 36.2 0.285 0.601 22 36.0 0.288 Mean 36.2 0.304 0.641 36.1 0.309 j Condition factor 0.641 0.&95 0. 709 0.670 0.661 N ....... 0.641 I-' 0. 603 0.617 0.655 Table 7.11 Length, weightt and condition factor .of juvenile chinook salmon from two females and sampled from incubation boxes located at University of Washington Hatchery, 1976-77. . Female /13-76 Female /14-76 Mean Mean Mean Mean Sample length weight Condition Sample length weight Condition Date size (mm) (g) factor size (mm) (g) factor 1976 12-27 49 34.7 0.301 0. 723 12-31 46 35.8 0.310 0.675 1977 1-6 48 36.3 0.318 0.669 36 36.3 0.360 0. 750 1-10 46 36.5 0.322 0.661 50 37.0 0.393 0. 775 1-14 49 36.4 o. 318 0. 662 37 37.2 0. 376 0.733 1-18 47 36.4 0.312 0.646 1-19 47 37.8 0.371 0.690 1-22. 42 36.5 0.302 0.619 1-23 49 37.8 0.376 0.698 1-28 45 36.2 0.305 0.646 49 37.5 0.363 0. 689 2-.2 46 35.8 0.266 0.583 44 37.2 0.360 0.697 2-7 48 37.1 0. 342 0.672 2-11 29 36.9 0.317 0.631 Mean 36.1 0.306 0.654 37.2 0.364 0.706 N "'-1 N - - - - - 273 condition factors for fish from Females #3-76 and #4-76 ranged from about .62 to .69 at the various incubation sites. For fish from Females #1-74, #1-76, and #2-76 condition factors were in the vicinity of .72. Overall mean length, weight, and condition factor of alevins and fry resulting from incubation of eggs from four chinook females appeared to be related to egg diameter and weight (Tables 7.5 and 7.9). The larger (9.16 rnm) and heavier (0.441 g) eggs produced longer (40.9 mm) and heavier (0.554 g) juvenile chinook salmon with higher condition factor (0.811) while the smaller (7.43 rnm) and lighter (0.278 g) eggs produced shorter (36.4 mm) and lighter (0.308 g) juveniles with lower condition factor (0.624). Intermediate sized eggs produced intermediate sized juveniles. Eggs from individual Females, #3-76 and #4-76, produced juveniles of similar overall mean length, weight and condition factor at each of the various incubation sites. These factors are shown in Tables 7.9, 7.10, and 7.11 for juveniles from Female #3-76 and in Tables 7.9 and 7.11 for juveniles from Female #4-76. These results indicated that juvenile size at or near mean yolk absorption was primarily influenced by egg size and little affected by incubation temperature. Presumably the relationship was that the larger eggs contained more yolk material to be converted to body tissue. 7.5.1.2 Pink Salmon. Eggs were taken from four female pink salmon during the 1977 run and incubated in the Skagit River near Newhalem. The dates of fertilization (October 5 and 13) were timed to coincide with the peak of the Skagit pink salmon run (Fig. 6.16). An average of 953 °F TU's were required to mean hatching for eggs from these four females (Table 7.3). The dates to mean yolk absorption ranged from April 8 to April 21, 1978 and an average of 1,692 °F TU's were required by eggs from four pink salmon females (Table 7.4). The dates of mean yolk absorption, which probably approximated emergence time, were consistent with fry availability data and occurred near the middle of the period when pink fry were available to our electroshocking gear (Table 8.38). Female length and weight (eggs removed) and egg weight and diameter data are presented in Table 7.12 along with TU's to mean hatching and mean yolk absorption and mean incubation temperature for pink salmon incubation studies in the Skagit River at Newhalem. Data on egg size and TU's to mean yolk absorption were less variable for pink salmon than those for chinook salmon (Table 7.5). Female length and egg diameter showed an inverse relationship. Eggs from two pink salmon females incubated in the cooler Cascade and Sauk rivers required less TU's to mean yolk absorption (1,388 and 1,614 TU's, respectively) than those incubated in the Skagit (1,700 TU's) and there was a general synchronization in dates to mean yolk absorption at the three sites (Table 7.4). This suggests that the developmental rate was altered by a compensating mechanism so that at lower temperature fewer TU's were required (Fig. 7.9). Table 7.12 Fish Female weight no. (g) 1-77 2150 2-77 1450 3-77 1600 4-77 Lengths and weights of four pink salmon females with respective egg weights and diameters. Also shows temperature units required to mean hatching and to mean yolk absorption, and mean incubation temperature to yolk absorption. Eggs were taken in 1977 and incubated in the Skagit River near Newhalem. TU's to Mean incubation Fish Egg Egg TU's to mean mean yolk temperature to length weight diameter hatching absorption yolk absorption (nun) (g) (mm) (OF) (oF) (oF) 584 0.196 6.93 971 1700 41.2 521 0.229 7.37 962 1700 41.2 584 0.228 6.91 946 1669 40.9 0.210 7.19 932 1699 40.9 N -...J -~=:'- - - P"h-· !iii~ - - - - 275 2500 <r.J 1- ;z2ooo :::::) lLJ 1700 0:::: TU 's :::::) 1-a: 0:::: lLJ ~1500 lLJ 1- 1-....... lLJ I z lLJ g§ 1000 a: IJ... w > ....... '~ 1-I a: __J )-a days :::::) sao 1:: I I :::::) u I 31 da s I 0~----~------~------~----~------~----~~L-~-L~-- Fig. 7.9 ()CT N()V 1977 DEC JAN FEB MAR 1978 APR Cumulative Fahrenheit temperature units experienced by pink eggs incubated in the Skagit, Sauk, and Cascade rivers, commencing October 5, 1977. Observed dates and associated TU requirements to mean yolk absorption are indicated by vertical and horizontal solid lines. Theoretical dates to mean yolk absorption assuming 1,700 TU's are indicated by vertical dashed lines. MAY 276 7.5.1.3 Chum Salmon. Eggs were taken from four female chum salmon during the 1977 run and incubated in the Skagit River near Newhalem. The dates of fertilization (December 7 and 16) were timed to coincide with the peak of Skagit chum salmon spawning observed in 1976 (Fig. 6.17). No spawner observations were made in 1977. An average of 816 °F TO's were required to mean hatching for eggs from these four females (Table 7.3). The dates to mean yolk absorption ranged from June 2 to June 7, 1978 and an average of 1,561 °F TO's were required (Table 7.4). These dates of mean yolk absorption were not consistent with chum fry availability data for 1978 (Table 8.51). By early June fry availability was declining in the Skagit and catches were zero on June 13 at three Skagit sampling sites. Female length and weight (eggs removed) and egg size data are presented in Table 7.13 along with TO and temperature data. Chum data on egg size and TO's to mean yolk absorption was similar to pink data in variability and was less variable than data for chinook salmon. As with pinks there was an inverse relationship between female length and egg size. Eggs from Female #1-77 required less TO's to mean yolk absorption and reached mean yolk absorption in a shorter time when incubated in the Sauk and Cascade rivers than they did when incubated in the Skagit at Newhalem (Table 7.4). These data, like those for chinook and pink salmon, suggest TU compensation occurred for chum salmon (Fig. 7.10). Results of incubation studies conducted at the University of Washing- ton Hatchery are summarized in Table 7.14. Eggs from four chum females were incubated under constant temperature regimes of approximately 45, 41, and 37 °F. The mean numbers of TO's tomean hatching and mean yolk ab- sorption were directly proportional to the incubation temperatures which again suggests TO compensation. The ~41°F constant temperature regime was nearest the mean incubation temperature measured in the Skagit during churn incubation. However, under the ~41 °F regime in the hatchery an average 1,024 TO's were required to mean hatching and 1,757 TO's to mean yolk absorption (Table 7.14) while in the Skagit 816 and 1,561 TO's, respectively, were required (Table 7.3 and 7.4). Dates to mean yolk absorption were later' in the hatchery than they were in the Skagit by about 3-4 weeks. There appeared to be differential egg mortality related to incubation temperature (Fig. 7.11). Egg mortality was extremely high for eggs incubated at ~37 °F. Also note that mean yolk absorption did not occur until late October or early November for eggs incubated at that low temp- erature (Table 7.14). 7.5.1.4 Coho Salmon. Eggs from two coho females fertilized on December 16, 1977 and incubated in the Skagit near Newhalem, required an average 777 TO's to mean hatching (Table 7.3) and 1,298 TO's to mean yolk absorption (Table 7.4). Mean yolk absorption was reached in mid-May. - - Table 7.13 Female no. 1-77 2-77 3-77 4-77 ) ) J ) -J } Lengths and weights of four chum females with respective egg weights and diameters. Also shows temperature units required to mean hatching and to mean yolk absorption, and mean incubation temperature to yolk absorption. Eggs were taken in 1977 and incubated in the Skagit River near Newhalem. TU's to Mean incubation Fish Fish Egg Egg TU's to mean mean yolk temperature to weight length weight diameter hatching absorption yolk absorption (g) (nnn) (g) (mm) (oF) (oF) (oF) 2440 630 0.317 8.34 817 1597 40.9 0.293 7.95 817 1566 40.8 2812 697 0.266 7.64 781 1517 40.9 4128 725 0.259 7.54 849 1564 41.0 N ...... ...... U) l- 2500 z2000 :::) lJ.J 0::: :::) 1-a: a::: w 278 1597 TU's ~1500r-------------------------------------~ IJJ I- I-...... w ::r: z w ~1000 a: lL.. w > ...... 1-a: _J ~ 500 :::) u I I I I I I I I 8 days' I I I I I 28 days 1 I I I o~~--~------~----~------~----~----~-L~--~ Fig. 7.10 DEC 1977 ~IAN FEB MAR APR MAY JUN 1978 Cumulative Fahrenheit temperature units experienced by chum eggs incubated in the Skagit, Sauk, and Cascade rivers, commencing December 7, 1977. Observed dates and associated TU requirements to mean yolk absorption are indicated by vertical and horizontal solid lines. Theoretical dates to mean yolk absorption assuming 1,597 TU's are indicated by vertical dashed lines. - - l l ) ··~ Table 7. 14 Summary of incubation studies using eggs from four chum females incubated under three different constant temperature regimes at the University of Washington Hatchery. Shows dates, temperature units, and number of days to mean hatching and to mean yolk absorption. Incubation To mean hatching To mean yolk absorEtion Female temp. :Date TU's II of TU's II of no. (oF) fertilized Date (oF) days Date (OF) days Chum 111-77 45_ 0 12/ 7/77 3/ 2/78 ll05 85 -5/14/78 2054 158 112-77 45.0 12/ 7/77 3/ 2/78 nos 85 5/ 8/78 1976 152 113-77 44.6 12/16/77 3/10/78 1058 84 5/21/78 1966 156 114-77 45.0 12/16/77 3/15/78 ll57 89 5/22/78 ' 2041 157 mean = ll06 mean = 2009 Chum 111-77 40.6 12/ 7/77 3/31/78 985 ll4 6/22/78 1702 197 112-77 40.6 12/ 7/77 4/ 4/78 1020 ll8 6/28/78 1754 203 113-77 41.0 12/16/77 4/ll/78 1044 116 7/10/78 1854 206 /14-77 40.6 12/16/77 4/16/78 1045 121 7 I 3/78 1719 199 N '-I 1024 1757 \,() mean = mean = Chum 111-77 37.0 12/ 7/77 6/ s/78 907 180 -ll/ 7/78 1688 335 112-77 37.6 12/ 7/77 5/23/78 935 167 10/10/78 1719 307 113-77 37.0 12/16/77 100% mortality 100% mortality /14-77 37.0 12/16/77 6/18/78 927 184 -10/26/78 1583 314 mean = 923 mean = 1663 280 500 400 (fJ w ...... 1--...... _J cr: 300 1-- 0::: 0 :I: g w u.. 0 200 a:: w -41 oF (D :I: ~ z 100 -45° F 0 0 10 20 30 40 50 so 70 80 90 PERCENT OF DAYS TQ MEAN HATCHING Fig. 7.11 Egg mortalities between fertilization and mean hatching for Skagit River chum eggs incubated under three con- stant temperature regimes at the University of Washing- ton Hatchery, 1977-1978. - ~ - ~ """': 100 - ~' - -' ...... - ·- 281 Eggs from two coho females were incubated under constant temperature regimes of approximately 45, 43, and 38 °F at the University of Washington Hatchery (Table 7.15). The TU requirements to mean hatching (1,024 and 1,034 TU's) and mean yolk absorption (1,689 and 1,700 TU's) were similar at 45.3 and 43.0, respectively. These temperatures may be too similar to detect changes in TU requirements. At the lowest incubation temperature (37.6 °F), the TU requirements were also lowest, 933 TU's to mean hatching and 1,470 TU's to mean yolk absorption. Like the other salmon species, TU compensation is indicated for coho salmon. ' 7.5.1.5 Theoretical Timing to Yolk Absorption. The timing to mean yolk absorption under various temperature regimes was calculated for chinook (summer-fall), pink, and chum salmon, and steelhead trout. These calculations do not assume a compensatory shift in developmental rate which if acting might tend to dampen the variation. The timing of spawning, including the peaks, was based on observations by Fisheries Research Institute (FRI) during the 1975, 1976, and 1977 spawning seasons described in Sec. 6.4.2. The TU requirement for Skagit chinook and pink salmon was determined from FRI studies reported in Sees. 7.5.1.1. and 7.5.1.2, respectively. While the TU requirements was determined for Skagit chums (Sec. 7.5.1.3), its validity for predicting dates to mean yolk absorption was questionable (Sec. 7.6.2). The TU requirement for chum salmon was, therefore, based on information from other systems. The TU requirement for steelhead was also based on information from other systems, since specific incubation characteristics were not known for Skagit River steelhead populations. The calculated dates to mean yolk absorption for chinook, pink, and chum salmon are shown Table 7.16 for recent and long-term temperature regimes measured f15T the Skagit River at Alma Creek (USGS) and the predicted predam regime for Skagit River at Alma Creek (Burt i973). In general, the water temperatures during the incubation periods for these species were above average during 1976-1977, below average during 1975-1976, and near average during 1974-1975. For chinook salmon the calculated peak dates of mean yolk absorption showed a 4-week variation (January 18-February 18) between warmer and cooler temperature regimes with the peak expected on February 6, based on the long-term temperature regime. Projections based on the total spawning period for Skagit chinooks (late August through October) indicated that under average temperature conditions, completion of yolk absorption would be expected to occur from early January to late May. Based on Burt's (1973) predicted predam regime, mean yolk absorption would be expected on May 24. Pink and chum salmon showed a 5-and 3-week variation, respectively, for estimated peak yolk absorption over three recent incubation periods. Under average temperature conditions completion of yolk absorption would be expected to occur from mid-February to mid-April with the peak on March 21 for pinks, and from early April through May, with the peak on Hay 16, for chum. Nean yolk absorption would be expected on June 6 and Table 7.15 Summary of incubatiqn studies using eggs from two coho females incubated under three different constant temperature regimes at the University of Washington hatchery. Shows dates, temperature units, and number of days to mean hatching and to mean yolk absorption. Incubation To mean hatching To mean yolk absorption Female temp. Date TU 1 s II of TU's II of no. (oF) fertilized Date (oF) days Date (oF) days Coho 111-77 45.3 12-16-77 3-4-78 1037 78 4-22-78 1689 127 112-77 45.3 12-16-77 3-2-78 1011 76 4-22-78 1689 127 mean 1024 mean = 1689 Coho 111-77 43.0 12-16-77 3-20-78 1034 94 5-17-78 1672 152 112-77 43.0 12-16-77 3-20-78 1034 94 5-22-78 1727 157 mean 1034 mean 1700 N 00 N Coho 111-77 37.6 12-16-77 6-2-78 941 168 9-6-78 1478 264 112-77 37.6 12-16-77 5-30-78 924 165 9-3-78 1462 261 mean 933 mean = 1470 J -J - ~ '~ ,... - - - Table 7 .16 Date of peak spawning Temperature 283 Comparison of calculated dates to mean yolk absorption for chinook, pink, and chum salmon, based on temperature records for Skagit River at Alma Creek (USGS) and Burt's predicted pre~ dam regime for Skagit River at Alma Creek. unit Temperature regime Chinook (summer-fall) Sep 7 Pink Oct 7 requirement 1,930 1,690 1974-75 Feb 4 Mar 16 1975-76 Feb 18 Mar 31 1976-77 Jar: 18 Feb 26 Mean (1953 to 1977) Feb 6 Mar 21 Burt's pre-dam May 24 Jun 6 Chum Dec 7 1,350 May 16 May 22 May 1 May 16 Jun 22 284 June 22 for pink and chum, respectively, under Burt's (1973) predicted predam regime. Timing to mean yolk absorption was calculated for steelhead trout for recent and long-term temperature regimes (Table 7.17) for the Skagit River at Alma Creek (USGS). The water temperature during the expected incubation period for steelhead was, in general, below average in 1975 and 1976, while it was above average in 1977. The spawning period for steelhead trout is not well defined, and as indicated in Sec. 6.4.2.5, the time of peak spawning can vary. Based on the temperature regimes of 3 recent years, the time to mean yolk absorption showed a 2-to 3-week variation between years. Steelhead eggs spawned as early as March 15, and as late as May 15, would be expected to complete yolk absorption on June 22 and July 26, respectively, under average temperature conditions. For steelhead eggs spawned on March 15, April 15, and May 15, mean yolk absorption would be expected on July 3, 17, and August 14, respectively, under Burt's (1973) predicted predam regime. Since salmon eggs usually incubated during a period when te~peratures are falling (Fig. 2.27), the length of the yolk absorption period (i.e., from beginning to end) was usually longer than the length of the spawning period. This resulted from the earlier spawned eggs accumulating TU's faster because of generally higher water temperatures than subsequently spawned eggs. The disparity was greatest for chinook and pink salmon for which the length of the period for the completion of yolk absorption was approxi- mately twice as long as the spawning period. The lengths of the two periods were nearly equal for chum salmon because the first part of their incubation period occurred during a period of decreasing temperatures while the latter part occurred under increasing temperature. These relationships were reversed for steelehad trout because their egg incubation occurred during a period of increasing temperatures. As a result the period of completion of yolk absorption was compressed and was approximately one-half the length of the spawning period. Like salmon, however, steelhead development was accelerated by warmer temperature, and yolk absorption would be expected to occur on an earlier date. The dates to mean yolk absorption were calcualted for chinook, pink, and chum salmon, and steelhead trout, using recent and average temperature regimes from the Cascade and Sauk rivers. The rationale for this was based on the assumption that these systems served as reasonable models of Skagit predam conditions (Sec. 2.2). Therefore, they may reflect the developmental timing of these species in the predam Skagit River. Again, these calculations do not account for a compensatory shift in develop- mental timing. The theoretical dates of mean yolk absorption for the Sauk and Cascade rivers are shown in Tables 7.18 and 7.19, respectively, for chinook, pink, and chum salmon. Based on the average regimes development to yolk absorption would be delayed 43 days for chinooks, 31 days for - - 285 Table 7 .17 Comparison of calculated mean dates of completion of -yolk absorption for steelhead trout based on tempera- ture records for Skagit River at Alma Creek (USGS) and Burt's predicted pre-dam regime for Skagit River at Alma Creek. ,._ -Temperature regime Steelhead trout Date of spawning Mar 15 Apr 15 May 15 Temperature unit -requirement 1,100 1,100 1,100 1975 Jun 29 Jul 13 Jul 31 1976 Jun 29 Jul 17 Aug 2 1977 Jun 13 Jun 28 Jul 17 - Mean ,_ (1953 to 1977) Jun 22 Jul 8 Jul 26 Burt's pre-dam Jul 3 Jul 17 Aug 4 - - 286 Table 7 .18 Comparison of calculated mean dates of completion of yolk absorption for chinook, pink, and chum salmon based on temperature records for Sauk River (USGS and SCL). Temperature Chinook Pink Chum regime (swmner-fall) Date of peak spawning Sep 7 Oct 7 Dec 7 Temperature unit requirement 1,930 1,690 1,350 1974-751 Mar 172 Apr 20 2 May 21 2 1975-761 Mar 21 2 Apr 21 2 May 162 1976-771 Mar 22 Apr 72 May 82 Mean(l970 30 1977) Mar 21 Apr 21 May 17 1sCL temperature data containing some gaps. 2 calculation made using 197Q-77 mean temperature data for gaps. 3 USGS temperature data from Mar 1970 to Apr 1971 and SCL temperature data from Feb 1972 to May 1977. - - - - -~ - - - ·- - - -' Table 7 ~19 · Date of peak spawning 287 Comparison of calculated mean dates of completion of yolk absorption for chinook, pin~ and chum salmon based on temperature records for Cascade River (USGS and SCL). Temperature Chinook Pink Chum regime (summer-fall) Sep 7 Oct 7 Dec 7 Temperature unit requirement 1,930 1,690 1,350 1976-771 Mar 25 Apr 19 May 18 Mean(l952 to 1973)2 Apr 1 Apr 28 May 23 1 SCL temperature data. 2 USGS temperature data. 288 pink, and 1 day for chums, under Sauk River conditions (Table 7.18), compared to Skagit at Alma Creek conditions (Table 7.16). Since Cascade River temperatures were generally lower than Sauk River temperatures, there would be an additional delay of 11 days for chinook, 7 days for pink, and 6 days for chum salmon (Table 7.19). For steelhead trout development to yolk absorption under the average regimes would be advanced 8, 5, and 2 days for those females spawning on March 15, April 15, and May 15, respectively, in the Sauk (Table 7.20) compared to the Skagit at Alma Creek (Table 7.17). The difference in timing was 1 day or less when comparing Cascade River (Table 7.21) to Skagit at Alma Creek (Table 7.17) under average conditions. 7.5.2 Timing of Emergence The fry emergent nets over the ''artificial" chinook redds located at each station were checked twice weekly after they were installed in 1974. By late May 1975, no fry had been observed in the nets and it was assumed that the eggs had either died or fry had emerged without being detected. Consequently, no data were obtained from this experiment. At Stations 1 and 2 the emergent nets placed on natural chinook redds marked on September 20, 1974, caught fry. The net at Station 3 caught no fry and may have been placed on a false redd. It was removed in late May. At Station 1 chinook fry were first observed in the net on January 18, 1975, and 17 of the 24 fish caught had completed yolk absorption (Table 7.22). The net was checked 3 days later and 121 fish were removed. Of the 18 fry examined for yolk, 10 fry had absorbed their yolks. The net at Station 1 was removed on January 21. Between September 20 and January 18, these chinook fry had been exposed to approximately 1,601 TU's. It is not known how much earlier than September 20 the eggs from which the fry developed had been spawned; however, if they required approximately 1,930 TU's to yolk absorption and emergence they would have been placed in the gravel about September 2. At Station 2, 359 chinook fry were removed from the net on January 25, 1975, and all but one of the 22 fry analyzed had absorbed their yolks. By the time these fish had b~come fry, they had been exposed to approximately 1,631 TU's from September 20, and if they required 1,930 TU's to emer-gence, the eggs would have been spawned on September 4. The emergent net was removed on January 25, 1975. The 1976 chinook spawning curve showing number of new redds per day (Fig. 6.14) was assumed to be representative of chinook spawning above the confluence of the Cascade River in 1974. Using the spawning curve (smoothed by threes), an emergence curve was calculated by summing TU's from each day of spawning until the number of TU's required for "theoretical" emergence was accumulated (1,930 TU's). Fig. 7.12 shows the estimated relative number of emerging fry in the upper Skagit. Calculated emergence began in early Janaury and increased gradually until it peaked in early February. Most of the fry emerged from late January to ~:·'' - -~ ~ .. - ''"'" - f~ - - 289 Table 7.20 Comparison of calculated mean dates of completion of yolk absorption for steelhead trout based on temperature records for Sauk River (USGS and SCL). Temperature Steelhead trout regime Date of spawning Mar 15 Apr 15 May 15 Temperature units required 1,100 1,100 1,100 19751 Jun 17 2 Jul 62 Jul 26 2 1976 3 Jun 14 Jul 3 Jul 27 19773 Jun 8 Jun 26 Jul 17 Mean (1970 to 1977) 4 Jun 14 Jul 3 Jul 24 1sc1 temperature data containing some gaps. 2 calculatiori made using 1970-77 mean temperature data for gaps. 3 SCL temperature data. 4 USGS temperature data from Mar 1970 to Apr 1971 and SCL temperature data from Feb 1972 to May 1977. Table 7.21 Date of 290 Comparison of calculated mean dates of completion of yolk absorption for steelhead trout based on temperature records for Cascade River (USGS and SCL). Temperature Steelhead trout regime spawning Mar 15 Apr 15 May 15 Temperature units required 1,100 1,100 1,100 19761 Aug 9 19771 Jun 18 Jul 4 Jul 23 Mean (1952 20 1973) Jun 22 Jul 9 Jul 27 1 SCL temperature data. 2 USGS tempel.".ature data. - ~I - ) l Table 7.22 Data on juvenile chinook salmon captured in emergent nets over natural redds, 1975. Station 1 2 Date of emergence Jan 18 Jan 21 Jan 25 No. of fish 24 121 359 Number for development 24 18 22 Number measured 0 62 19 Average length (mm) 39.9 41.5 Average weight (g) 0.64 0.58 Wet weight condition factor 1.00 0.90 Percent without yolk 71 56 95 292 a 7 6 >-Q:: L&.. i 5 -&:1 ~ "" ~ 4 Q:: ! 3 ~ -t-2 a: ..J ~ 1 0 0 14 28 11 25 11 25 a 22 6 20 JAN FEB MAR APR MAY 1975 Fig. 7.12 Estimated emergence curve of 1974 chinook salmon fry assuming 1930 temperature units to emergence and peak spawning to he Septemher 9th. """" ~' _, -'' ~ ~ ~ ~i """' - - 293 mid-Harch, but emergence continued into mid-t-1ay. Fry availability data obtained by electroshocking (Sec. 8.1.4.1) substantiate early January emergence since fry were captured as early as January 7, 1975, the first sampling date. For the 1976-1977 incubation cycle the timing of expected emergence was calculated from the timing of spawning and the TU requirement for Skagit chinook salmon (Fig. 7.13). The timing of spawning is presented in the form of a histogram with intervals 5 days in width and height shown in percentage. A "histogram" of expected emergence was constructed by summing the TU's for each 5-day interval until 1,930 TU's had been accumu- lated. This "histogram" of expected emergence is not of the usual form and requires special interpretation. Each column in the emergence histogram was derived from a column in the spawning histogram. The height of the column represents the relative proportion emerged given in percentage and is the same height as the corresponding column in the spawning histogram. The width of the column indicates the length of the emergence period resulting from the corresponding 5-day spawning interval. The timing of theoretical emergence for 1976-1977 (Fig. 7.13) was somewhat advanced compared to theoretical emergence for 1974-1975 (Fig. 7.12). Calculated emergence began in mid-December 1976, reached a peak in mid-January 1977, and continued to late April 1977. Electro- shocking data confirmed an earlier emergence date with fry being captured in early December 1976. The emergence pattern for chinook eggs fertilized on October 12, 1976, and incubated in gravel substrate at the University of Washington Hatchery is shown in Fig. 7.14. Emergence extended from about December 17, 1976, to January 14, 1977. Peak emergence for both compartments combined occurred on December 29, 1976, when 1,558 TU's had been accumulated. Individually there was a difference of 2 days to peak emergence between the compartments, December 28 and 30, 1976. Egg to fry survival was excellent for this emergence experim~nt. From the 500 eggs initially planted, 477 live fry were recovered, or 95 percent survival. All emerged fry from this experiment were examined for absence or presence of yolk and none was found to have completed yolk absorption. 7.5.3 Fry Condition at Emergence The physical condition of chinook fry held in the Station 1 incubation box past yolk absorption during early 1975 was compared with the physical condition of Skagit fry. Condition data for fry captured in the Skagit system are presented in detail in Sec. 8.1.4.2. When incubation box fry were compared with fry caught by electroshocking, in all cases natural fry weighed more and their condition factors were larger (Table 7.23). The percent that natural fry were greater in ~eight than incubation box fry rose from 8 percent on March 4 to 71 percent on April 22, when the last sample was removed from the box. The condition I UJ ~ 2250 2000 1750 :ZlSOO ~ IJJ ~1250 1-a: a:: IJJ i:1000 w 1- 750 500 250 I I I ,1' / 1930 TU's I I CUMULATIVE I % SPAWNED: ~I 5 10 15 20 25 31 I I I I I I I I I I I AUG SEP OCT 1976 NOV DEC I I I I CUMULATIVE % EXPECTED 1 ~ EMERGENCE JAN FEB APR MAY Fig. 7.13 Timing and relative magnitude of chinook spawning and expected emergence for 1976-1977 based on the accumulation of 1930 temperature units. Cumulative percent spawning and cumulative percent expected emergence are shown. J 00 90 80 70 so., f'T1 ~oS -t ~ N IC 40 ~ 30 20 10 0 •·,, 1 ) FRY EMERGENCE-HATCHERY so~----------------------------~-------------------------------------------, >-a: a a::: w COMPARTMENT # 1 COMPARTMENT # 2 COMBINED ~30~----~--------------------~B----=--~----------------------------------~ Cl ~ a::: w :C w >-E2o~--------------------~------~--~------~~----------------------------------, a::: w OJ :c :J z 17 19 21 23 25 27 29 DECEMBER 31 2 4 6 8 JANUARY 10 Fig. 7.14 Number of chinook fry emerged per day when incubated in gravel substrate at University of Washington Hatchery during 1976-1977. 12 14 N \0 Ln Date 3-4 3-11 3-18 4-1 4-8 4-22 1-21 Table 7.23 Comparison of juvenile chinook salmon held in incubation box after yolk absorption and natural fry captured by electrofishing, 1975. Percent natural fry are Natural fry captured on same greater than incubation Fry from incubation boxes or com_earable dates box fry Sample Average Average Wet Sample Average Average Wet Average Average Wet size length wet weight size length wet weight length wet weight (mm) weight cond. Date (nnn) weight cond. weight cond. (g) factor (g) factor factor 29 41.7 0.52 0. 72 3-4 30 40.9 .57 . 83 8 14 27 40.7 0.51 0. 72 3-11 30 41.5 . 58 .80 2 18 11 47 40.7 0.51 0.73 3-25 26 40.6 . 64 .95 21 22 36 40.8 0.50 0. 73 4-1 42 40.1 .63 .89 29 24 20 41.0 0.44 0.64 4-8 56 42.6 . 69 .93 4 57 45 41 40.3 0.41 0.63 4-22 66 41.6 .70 .95 3 71 51 Fry from natural redd Station 1 62 39.9 0.64 1.00 J N 1.0 0'1 - -( 297 factor of natural chinook fry also rose from 11 percent ~reater than incubation box fry on March 11 to 51 percent greater on April 22. Very little, if any, food was available to the incubation box fry. This is supported by the fact that five stomachs from each sample were examined and none of them contained food. (See Sec. 8.1.4.3 for results of chinook diet studies.) Also, as the number of weeks from yolk absorption increased, the average weight, length, and condition factor generally decreased (Table 7.23). In contrast, the average weight, length, and condition factor of natural chinook fry generally increased (Table 8.15) and food was found in stomachs taken on all dates during 1975 except March 4, when no stomach samples were taken. The physical condition of chinook fry taken from the emergent net at Station 1 on January 21 is also shown in Table 7.23. Sixty-two fry were 4 percent shorter, 21 percent heavier, and their condition factor was higher than incubation box fry on March 4, the date closest to "theoretical" yolk absorption. The length, weight, and condition factor of chinook fry from Female #4-76 emerging from gravel substrate at University of Washington Hatchery are presented in Table 7.24. These fry, emerging at their own volition, showed a general increase in length from,about 34 to 38 mm, an increase in weight from about 0.33 to 0.41 g, and the resulting decrease in condition factor from about 0.86 to 0.68. This general increase in length and weight was not observed for juvenile chinook from Female #4-76 sampled from incubation boxes located at University of Washington Hatchery (Table 7.11). By comparison the emerging alevins overall were slightly shorter, similar in weight, and had slightly higher condition factor. 7.6 Discussion 7.6.1 Hatching The estimated number of TU's required to hatching for chinook pink, chum, and coho salmon eggs incubated in the Skagit River showed little variation between different females when incubated at similar mean water temperature. Hare variability was encountered when comparing TU requirements to hatching for eggs from the same female incubated under warmer and cooler temperature regimes. Temperature units to hatching did not appear to be related to egg size. The estimated number of TU's that Skagit River chinooks required to hatching as determined by these studies for eggs from four females was quite similar to those that Seymour (1956) found for Skagit chinooks in his experiments (981 at mean temperatures ranging from 47.4 to 48.9 OF compared with 974 at 49.4 °F, mean temperature). Wild summer chinook eggs spawned at the ¥mrblemount Hatchery on September 16, 1974 were estimated by the hatchery manager to have begun hatching on November 20, when they had accumulated 1,070 TU's. They were exposed to an intermediate average temperature (48 °F) compared to eggs from four females incubated in the Skagit River near Newhalem (Table 7.2). 298 ~ Table 7.24 Length, weight, and condition factor of chinook alevins emerging from gravel substrate at University of Hashington Hatchery, 1976-77. Number Mean Mean Condition ..,, emerged length weight factor Date (nun) (g) ~. 1976 12-16 62 33.8 0.334 0.862 •... , 12-20 25 34.5 0.345 0.839 12-22 20 35.1 0.348 0.805 12-24 5 36.2 0.366 0. 772 """ 12-27 69 36.6 0.373 0.761 12-28 39 36.8 0.373 0.745 12-29 42 37.0 0.377 0.741 ~' 12-30 38 37.8 0.376 0. 725 12-31 32 37.7 o. 377 0.702 1977 ~ 1-1 26 37.5 0.374 0.709 1-2 18 37.3 0.370 0.714 1-3 19 37.9 0.380 0.698 1-4 13 37.8 0.383 0. 711 1-5 6 37.8 0.373 0.689 1-6 18 38.3 0.382 0.681 1-7 14 37.1 0.381 0.744 1-8 5 38.2 0.376 0.675 1-9 8 38.3 0.384 0.686 - 1-10 4 38.5 0.385 0.675 1-11 5 38.0 0.412 0. 751 1-12 0 ~ 1-13 6 38.7 0.392 0.678 1-17 3 38.3 0.390 0.693 -· Mean 36. 7 0.368 o. 753 ~~, -299 7.6.2 Yolk Absorption and Emergence Completion of yolk absorption and emergence are not necessarily synonymous. Under hatchery conditions juvenile chinook from Skagit River stock and incubated in trays containing gravel substrate were observed to reach peak emergence approximately 3 weeks before the first juveniles completed yolk absorption in other fish from the same stock. Under natural conditions, however, the timing to yolk absorption and to emergence appeared to be similar. Burgner (1974), in his testimony before the Federal Power Commission in regard to raising Ross Dam, calculated that yolk absorption of summer chinook salmon in the upper Skagit River would, on the average, be completed by mid-December, but was under the impression that fry do not emerge from the gravel for at least 2.5 months beyond mid-December, rather, in early March. Johnson (1974), of WDF, concurred with Burgner's view and added that the emergence time was determined by electrofishing. Both Johnson and Burgner based their statements on a peak spawning date of September 1 and a requirement of 1,700 TU's to yolk absorption. The results of these studies indicated that in 1975, 1976, and 1977, emergence was not delayed. Based on a peak spawning date of September 7, and a requirement of 1,930 TU's to yolk absorption, time of completion of yolk absorption peaked in early February, mid-February, and mid-January, respectively, and not mid-December. It began in January or December depending on temperature. Electroshocking in these years showed some fry had emerged from the gravel as early as January 7, 1975; January 5, 1976; and December 2, 1976. If chinook fry were delaying in the gravel after yolk absorption they would have to rely on body tissues and energy reserves for nourishment. This would be reflected in emerged fry having poor physical condition. As reported in Sec. 7.5.3 fry held in the Station 1 incubation box past yolk absorption simulated this condition and it was found that in every case natural fry weighed more and had a higher condition factor. This suggests that natural fry were not exposed to starvation conditions. Chinook fry were caught in the emergent nets over natural redds at Stations 1 and 2, 1.5 months before Johnson's estimate of peak emergence. A sample of 42 fish from the net at Station 1 showed that about 30 percent still had yolk remaining in their bodies, while 5 percent of a sample of 22 fish from the net at Station 2 still had yolk remaining. Juvenile chinook with yolk remaining at emergence would indicate that they are not delaying in the gravel. The timing of mean yolk absorption for pink salmon as shown by incu- bation studies in 1977-1978 was consistent with the pattern of pink fry availability as determined by electrofishing. These findings suggest that timing to yolk absorption and to emergence were similar under natural con- ditions for pink salmon. The inconsistancy in timing of mean yolk absorption for chum salmon and the pattern of chum fry availability seemed to contraindicate a simi- 300 larity between yolk absorption and emergence. However, this may have resulted from the upstream to downstream temperature gradient in the Skagit River (Fig. 2.31). During the majority of the chum incubation period (December to May or June) water temperature was colder at Newhalem by as much as 2 °F on the average than it was at Marblemount or Rockport. Since the incubation experiment was carried out at Newhalem under these colder conditions, development there was probably delayed. Chum distri- bution was shown to be heaviest in the downstream areas (Sec. 6.4.3.3). Of the mainstream chum spawning between Newhalem and Concrete in 1976, an estimated 65.6 percent occurred between Harblemount and Rockport with 13.6 percent between Newhalem and Marblemount. Therefore, the majority of chum eggs and alevins incubating in the study area were experiencing warmer temperature and advanced development and these should have influenced fry availability more than ones incubating near Newhalem. For this reason the results of the chum incubation experiments at Newhalem were probably not representative of the Skagit chum population in the study area as a whole. And therefore the estimated number of TU's to mean yolk absorption from our chum incubation experiment was not used to predict emergence timing. Similar qualifications do not apply to chinook and pink data. The water temperature during the first part of the chinook incubation period was warmer at Newhalem than it was downstream and during the latter part was cooler (Fig. 2.31). These differences tended to balance each other out. A similar tendency also occurred for pink salmon. In addition, pink salmon were observed to utilize the upstream areas more heavily for spawn- ing than the downstream areas (Sec. 6.4.3.2). Since the timing to yolk absorption and to emergence appeared to be similar under natural conditions for chinook and pink salmon and since a plausible explanation exists for the discrepancy observed for chum salmon, the completion of yolk absorption and calculations made from yolk absorp- tion data are considered to approximate emergence. 7.6.3 Temperature Unit Compensation The estimated number of TU's required to yolk absorption by chinook salmon eggs from different females incubated in the Skagit River showed similar variation to the number of TU's required by eggs from the same female incubated under warmer and cooler temperature regi~es. For the former case, the variation was primarily due to egg size since it was shown that the TU requirement was highly correlated to egg size. Presumably, the larger the eggs, the more yolk material they contained, and more time would be required for that yolk to be absorbed. The results were confounded by differences in mean incubation temperature but the magnitude of the differences did not appear great enough to be the overriding factor. · In the latter case, where egg size was not a factor, the TU requirements were shown to be highly correlated to mean temperature during the chinook incubation period. This suggests that the developmental rate was altered by a compensating mechanism so that at higher temperature more TU's were required and at lower temperature fewer TU's were required. - ~' - '""" - 301 According to E. Brannon (personal communication) sockeye and pink salmon have a physico-biochemical compensating mechanism which in effect compensates their TU requirements under different regimes, i.e., requiring fewer TU's in years of colder water and more TU's in years of warmer water. A similar conclusion was reached for pink, chum, and coho salmon from incubation studies conducted on these species. By this mechanism the fish possess some degree of adaptability to counteract year-to-year variation in environmental conditions. Such a mechanism would presumably improve fish survival by tending to maintain their emergence at a specific time of year when environmental conditions, food resources, etc., are more favorable. For chinook eggs from a single female incubated in warmer and cooler water temperature during 1976-1977, the shift in timing was toward the timing of eggs incubated in the Skagit River in both cases. The amount of compensation was 59 and 107 TU's for temperatures 3.9 and 4.0 °F cooler which resulted in a 10 and 16 percent shift in timing toward the Skagit condition while it was 300 TU's for temperatures 6.6 °F warmer which resulted in a 37 percent shift in timing. 7.6.4 F~y Condition at Emergence According to Brannon (1974), "The trend from hatching to yolk absorption is a consistent reduction in condition factor from approximately 2.65 to 0.76, with some variation because of racial differences among chinook salmon. When condition factor reaches 0.75, weight loss of the alevins will have started from starvation." The condition factors at mean yolk absorption were approximately 0.72 for fry from Skagit chinook females taken during the first half of September and were, therefore, similar to Brannon's minimum value, 0.76. For fry from females taken in October the condition factors at mean yolk absorption were approximately 0.64. This difference may indicate racially different stocks in the Skagit River, the former derived from stocks that Orrell (1976) considered to be the native "summer" chinook and the latter considered to be hatchery-derived "fall" chinook. These possible stocks could not be separated on the basis of spawning timing, however (Sec. 6.4.2.1). The WDF (Allen and Uoser 1963-1969, and Allen et al. 1969-1972) reported the following condition factors for fry egressing from two of their Columbia River spawning channels: 1. Rocky Reach: 1962-1964, 1966-1968. January-June: condition factor ranged from 0.62 to 1.28. 2. Wells: 1967-1968. April-May: condition factor ranged from 0.74 to 0.89. These fry included those captured soon after emerging as well as those which had resided in the spa\ming channel for an unknown period. In comparison, the minimum condition factors observed in Columbia River 302 channels (0.62 and 0.74) were similar to those observed to mean yolk absorption in our incubation studies (0.64 to 0.72). 7.6.5 Effects of Altered Temperature Regimes 7.6.5.1 Chinook Salmon. The Skagit River temperature regime has undergone a change as a result of dam construction, primarily Ross Dam, but the magnitude of the change is not precisely known and can only be estimated. Burt (1973) estimated that predam temperature regime was in general cooler than the present regime. A more conservative estimate was to consider the Sauk and Cascade regimes as models of predam conditions in the Skagit. Upon examination of WDF spawning ground records back to 1952, we found no evidence that the spawning timing for Skagit summer-fall chinook has undergone a change. In comparison with other chinook populations in other systems (Table 7.1), it appears that the timing of spawning and estimated emergence for Skagit River chinook salmon is similar. From the available data, only the peak spawning time described by Wales and Coots (1954) and Allen et al. (1969-1972), differed markedly from that of chinook spawning in the Skagit. The other three estimates fall within or coincide closely with Skagit River chinook spawning. Estimates of emergence by Reimers and Loeffel (1967) and Gebhards (1961) agree closely with the estimate for chinook in the Skagit, as does emergence at Wells Spawning Channel. The estimate by Wales and Coots (1954) spans approximately the same emergence period as the chinook in the Skagit; however, no peak estimate was reported. Only Chambers' (1963) estimate of peak emergence differs significantly and this may be due to spawning channel temperatures being different from predam Columbia River temperatures. The spawning patterns of chinook in the Sauk and Cascade rivers provide additional information for comparison with Skagit River chinook spawning. Spawning time in the Sauk coincided with Skagit River timing for the early portion of the run (Orrell 1976) and Cascade chinook spawn within the same time period as Skagit chinook (R. Orrell, personal communication). Since the spawning times in the upper Skagit, Sauk, and Cascade rivers appear to be similar, it does not appear that chinook spawners in the Skagit River have reacted to increased water temperatures in the r'iver by spawning later. However, there have been only seven or eight generations of chinook which have spawned in the Skagit since 1948 (the estimated initial time of temperature changes in the Skagit). This may or may not have been enough generations to show selection for later spawners. The timing of initiation and peak spawning were observed to be similar for the 1975 and 1976 chinook runs and the postpeak spawning pattern was similar in all 3 years of observation, 1975-1977 (Sec. 6.4.2.1). However, the spawning pattern and timing of Skagit River chinook may be influenced by the releases of "fall" chinook from the Marblemount Hatchery. These releases were quite large, 3-5 million - - r I I I~ - '' !.,.. 303 fingerlings, in the early 1970's. From 1974 (1973 brood) to 1976, no "fall" chinook were released in the upper Skagit system. This termination may affect the future spawning timing, particularly for the later part of the run. Chinook incubation at McNary Dam Spawning Channel required 1,800 TO's to emergence at an average temperature of 52 °F (Chambers 1963) while chinook at Wells Spawning Channel required only 1,600 TO's at an average temperature of 45.5 °F. In both instances the number of TO's required was less than the average 1,930 TO's found in these studies at an average temperature ranging from 44 to 47 °F, even though the McNary population experienced a higher average temperature and the Wells population experienced a similar average temperature. These data appear to be in conflict, insofar as one would expect to see more TO's required with a warmer average temperature. However, the differences between McNary, Wells, and Skagit chinook are probably attributable to the requirements of different racial stocks of salmon, as indicated by Seymour's (1956) study. If Burt's (1973) predam estimated temperatures are correct, then chinook emergence would have occurred in May (Table 7.16). However, it appears that predam temperatures in the Skagit may have approximated those now observed in the Sauk and Cascade because spawning times in the Skagit, Sauk, and Cascade are so similar. Sheridan (1962) showed a correlation between spawning time of pink salmon and stream temperatures. He found that in streams with warmer temperature regimes spawning time began later and that streams with similar temperatures showed similar spawning times. Conversely, similar spawning times could possibly indicate similar temperature regimes and if this were the case, it would appear that Burt's estimate may be low. It does not appear that TO adjustment with higher temperature has been sufficient to shift emergence timing of Skagit River chinook to that under predam conditions since the first appearance of Skagit River chinook fry precedes that of Sauk and Cascade river fry by about 1 month (Sec. 8.1.4.1). It is likely, however, that by TO adjustment the effect of temperature increases resulting from dam construction on the Skagit River has been dampened. 7.6.5.2 Pink, Churn, and Coho Salmon and Steelhead Trout. Pre- dictions were made of the effect of altered temperature regimes for Skagit pink and chum salmon. Based on the calculated timing to mean yolk absorption, the postdam elevated temperature regime has probably shortened the time to emergence by 4-11 weeks for pink salmon depending upon which predam temperature regime (Burt or Sauk-Cascade) is used for comparison. For Skagit chums this comparison ranged from essentially no change (using Cascade) to 5 weeks shorter (using Burt). Similar comparisons for steelhead indicated that the present time to emergence may have been shortened by about 10 days from predam conditions based on Burt's prediction, lengthened by 2-8 days using Sauk River mean regime as a model, and essentially unchanged using Cascade River mean regime. 304 Coho salmon egg incubation and emergence were probably not affected by the altered Skagit River temperature regime since they primarily utilize tributary streams for spawning. Skagit River pink, chum, and coho salmon were shown to possess a compensating mechanism to adjust TU requirements according to water temperature. While the magnitude of this adjustment is not precisely known, it seems likely that the effects of altered temperature regimes would be dampened. 7.6.6 Potential Effects of Copper Creek Dam The range of potential effects of Copper Creek Dam on the downstream temperature regime was predicted and is presented in Sec. 2.2.2. Based on the maximum potential effect the dates to mean yolk absorption were calculated for chinook, pink, and chum salmon, and steelhead trout (Table 7.25). Note the general agreement between dates to mean yolk absorption for Gorge Dam intake from SCL data (Table 7.25) and for Skagit River at Alma Creek from USGS data (Tables 7.16 and 7.17, mean temperature regimes). The predicted change in dates to mean yolk absorption was greatest for summer-fall chinook and pink salmon where the expected delay in timing was 14 and 13 days, respectively. The dates to mean yolk absorption under the two regimes were similar for chum salmon and steelhead trout with a trend to shorten slightly the incubation period. As indicated in Sec. 2.2.2 for temperature the shift in timing was considered the maximum and could range to little or no effect depending on physical and operational factors as yet unknown or undetermined. This maximum shift was in general toward predicted predam conditions. - - - """' - 305 Table 7.25 Comparison of calculated dates to mean yolk absorption for chinook, pin~ and churn salmon, and steelhead trout, based Date of spawning Temperature unit require- ment on temperature records for Gorge intake (SCL, 1971 to 1977), and the estimated temperature at Copper Creek Dam intake. Temperature Chinook regime (Sum/Fall) Pink Chum Steelhead Sep 7 Oct 7 Dec 7 Mar 15 Apr 15 May 1,930 1,690 1,350 1,100 1,100 1,100 Gorge Dam intake Feb 3 Mar 16 May 14 Jun 20 Ju1 7 Jul Copper Cr Dam intake Feb 17 Mar 29 May 13 Jun 18 Ju1 4 Ju1 15 27 24 306 - - - - - - - -i ,..,... t - ~. - 307 8.0 FRY REARING 8.1 Fry Availability, Growth, and Feeding 8.1.1 Introduction Fry of five salmonid species--chinook salmon (Oncorhynchus tshawytscha), pink salmon (Q. gorbuscha), chum salmon (Q. keta), coho salmon (Q. kisutch), and rainbow-steelhead trout (Salmo gairdneri)--reside in the Skagit River system for varying periods after emergence before migrating downstream to saltwater. Electrofishing has been the primary means to detect the presence and relative abundance of salmon and trout fry and to collect fry for diet analysis and for size and condition measurements in the Skagit system. In 1973, Washington Department of Fisheries (WDF) personnel sampled 200-ft sections of Marblemount, Sutter Creek, and Rockport bars on the Skagit River on eight occasions from March 2 through May 21 to assess availa- bility of chinook, chum, and coho fry to potential stranding flows (Phinney 1974a)~ The chinook fry length data indicated a prolonged emergence. iii 1974, \mF collected samples of chinook, coho, chum, and pink fry at the same three locations as well as at additional locations extending downstream to tidal influence and in the Sauk and Suiattle rivers (Orrell 1976). Sampling was conducted at intervals over the period March 4 -May 22, inclusive. Both beach seine and backpack Smith-Root Mark V electrofishing unit were used. Most samples in the upper Skagi.t and Sauk were taken by electrofishing. r1easurement of the growth rate of chinook fry was found impossible because of prolonged emergence from the gravel and continual migration downstream. There was no significant difference found in chinook fry condition factor between sampling locations. Fisheries Research Institute (FRI) began studies of salmon and rainbow-steelhead fry availability·and condition after emergence in 1974. Fry of chinook, pink, chum, and coho salmon, and rainbow-steelhead trout were collected from four.sites on the Skagit River and from five unregulated tributaries to determine the timing of emergence from the gravel and length of residency in the study area, and to monitor changes in abundance, length, weight, and condition factor during the period of their residency. These measurements were used to help determine the effects of temperature regimes and flow patterns modified by hydroelectric operations. Comparative studies of chinook fry diet in the Skagit River and two tributaries were initiated by FRI in 1975. In 1976 and 1977, the other species of salmon and rainbow-steelhead trout were also collected for stomach analysis. Fry diet was studied to determine if there were any differences in fry diet in the dam-regulated Skagit River compared to the unregulated Cascade and Sauk rivers, and, if so, whether these changes could be related to a modified benthic community structure in the Skagit, the 308 presence of zooplankton released from the reservoirs, and changes in fry length, weight, and condition factor. 8.1.2 Fry Electrofishing Sampling Stations The stations for collection of salmonid fry for food habit studies and for size and condition measurements are shown in Fig. 8.1. For the most part, the stations in the mainstem Skagit are the same stations sampled with the plankton pump as described in Sec. 4.2. The County Line Station was on the gently at the Whatcom-Skagit County line at RM 89.2. 2500 cfs, the bar was separated from the right was also sampled for fry. sloping cobble-covered bar At flows above about bank by a back channel that The Talc Mine Station was at the island near the left bank at RM 84.3 near the site of the proposed Copper Creek Dam. This station included areas with rapidly flowing water over cobbles on the river side of the island, quiet sandy habitats below the island, and muddy, brushy areas with overhanging vegetation in the back channel. The Marblemount Station was on the left bank above the mouth of the Cascade River near the Marblemount Bridge at ID1 78.3. This site had strong currents and deep water (about 2ft/sec and 2ft, respectively) fairly close to shore and a cobble and gravel bottom. There was a small quiet pool used as a boat launch and a submerged brush pile under the bridge. The Rockport Station was at a sand and rock bar downstream of the town of Rockport and upstream of the mouth of the Sauk River at RH 67.0. There were some brushy areas in the back channel on the right bank. At flows above 11,000 cfs, the Rockport Bar was inundated so samples were taken in the park at the town of Rockport in fairly slow-flowing water with submerged roots and undercut banks in May 1976 and April 1977. The Concrete Station was added above the mouth of the Baker River at RH 56.7 in April 1977, to sample fry condition and diet in conjunction with plankton drift sampling (Sec. 4.0) as far downstream as possible without the confounding influence of possible limnoplankton releases from reservoirs on the Baker River. This area included shallow sandy riffles, pools with submerged logs, and deeper riffles with cobble and gravel substrate. Fry from two major Skagit tributaries were also sampled for condition and stomach content analysis. The Cascade River was sampled on the left bank near the highway bridge (RM 0.9) upstream from the Harblemount Hatchery. This area included some fast, deep areas with a few stumps. Sometimes the small back channel to the left of the main channel upstream from the bridge was also sampled. The Sauk River was sampled for fry on the right bank at the county road bridge (RH 7.0). There were gravel beaches and submerged stumps and roots here. - - - - JIIJI;'!;;JJ., - ] 0 I J i J ,. g 1 ) ) ) ) j l Ross \ Darn · ----..;- 2 1 4 I I Scale, l~in."l mi. County Line Station Talc Mine Station Sauk River Fig. 8. 1 Electrofishing stations for stomach and condition samples, Skagit Basin, Washington. } w 0 1.0 310 Three minor Skagit tributaries were also sampled for fry. Goodell Creek, which enters the Skagit River at P~1 92.9, was sampled near the highway bridge that crosses the creek 0.1 mi upstream from the Skagit River. Bacon Creek, which enters the Skagit at RM 82.9, was sampled upstream of the campground above the highway bridge 0.2 mi from the Skagit River. Diobsud Creek, which enters the Skagit at approximately Rti 80.7, was sampled near the highway bridge 0.2 mi from the Skagit River. Bacon Creek is the largest of these minor tributaries, with a 7-year average discharge of 429 cfs, and Diobsud Creek is the smallest. Sites of fry collection in the Skagit River were sometimes varied to seek out different fry habitats or because of the occasional unavailabi- lity of the boat for transportation to the usual sampling stations. 8.1.3 Materials and Methods 8.1.3.1 Electroshocking for Fry. A Smith-Root type backpack electrofisher was the primary collection device used for capturing salmon and rainbow-steelhead trout fry for (1) availability assessment, (2) size and condition factor analysis, and (3) diet analysis. Open gravel bars, back channels, and undercut banks were shocked from depths of less than 1 inch to over 3 ft in an effort to sample different rearing habitats. Generally, electrofishing was done by a crew of two: One person carried and operated the electrofisher while the other person helped collect the stunned fry and kept count of the catch. In 1974, chinook, pink, chum, and coho salmon and rainbow-steelhead trout fry were sampled at the upper three Skagit sites, the Sauk River, the Cascade River, Diobsud Creek, Bacon Creek, and Goodell Creek. The Skagit River sites were first sampled on February 14-15, the Cascade River and Sauk River were first sampled on February 21-22, while the creeks were added in Harch or April. Generally, weekly to biweekly samples were taken through June 13, with occasional sampling in July, August, and September 1974. Limited sampling was conducted with fyke nets in Diobsud, Bacon, and Goodell creeks. Samples were collected for assessment of seasonal availability of the fry and for analysis of changes in lengths, weights, and condition factors. In 1975, chinook fry were sampled from the upper three Skagit River sites, the Sauk River, and the Cascade River on a weekly to biweekly basis from early January to late August. From 1 to 55 fry were taken hut an attempt was made to obtain at least ten fish for analysis of lengths, weights, and condition factors at each sampling. Usually five chinook fry were preserved from these collections for diet analysis from January 18 to June 16 in the Skagit River, from March 11 to June 16 in the Cascade River, and from February 11 to June 16 in the Sauk River. Sampling began again in December 1975 at four stations on the Skagit above the Sauk, and at stations on the Sauk and Cascade rivers. Goodell, Diobsud, and Bacon creeks were also sampled. Additional sampling was done on the Skagit River near Concrete beginning in April 1977. Chinook, pink, churn, coho, and rainbow-steelhead fry were collected for assessment of ~- §' - - .... 311 availability and for analysis of length, weight, and condition factor changes. An attempt was made to collect 25 specimens of each available species for each sample from the Skagit, Sauk, and Cascade river sites, while a limit of 10 specimens of each species was usually observed in the three minor tributaries. This sampling was continued year-round through 1976 on a weekly basis for about the first half of the year, and then every two weeks. Weekly electrofishing was resumed in December 1976 and ,continued to May 1977 when sampling was done every two weeks. Sampling in the creeks was terminated in August 1977. Sampling at the remaining stations was monthly from September through December 1977. In 1978, monthly samples continued to be collected at the stations on the Sauk and Cascade rivers, and at the Talc Mine Station on the Skagit River through April while weekly samples were collected into June at the County Line, Marblemount, and Rockport stations on the Skagit River. Monthly samples of five fry from each of the five species (except pink salmon which were scarce) were obtained when available for analysis of stomach contents from the stations on the Skagit, Cascade, and Sauk rivers beginning February 1976. In April 1977, the monthly sample size was increased to ten fish of each available species from each river site and a station at Concret·e upstream from the mouth of the Baker River which was added to coincide with plankton sampling at this site. This sampling was continued through April 1978. In late January 1976, attempts were initiated to make the monitoring of chinook fr~ availability more quantitative by standardizing electro- fishing as to location, distance and area covered, and time expended. Two 50-ft passes with the backpack electrofisher were made parallel to the shore. During the downstream pass, the band from the shore to 10 ft out was covered. During the upstream pass, the band from 10 ft out to 20 ft from shore was covered. One thousand ft2 were covered in the two passes. Fry were captured by the electrofisher operator or a helper and counted at the end of each pass. Fry that escaped capture during the two passes were also counted. In 1976, quantitative sampling of chinook fry was conducted weekly to biweekly from January 26 to May 19 at the County Line Station (RM 89.2) and from January 23 to April 22 at the Rockport Station (RM 67.0). In 1977, the Marblemount Station (RM 78.3) was added as a quantitative sampling site and chum fry availability was also monitored. The transect shocking in 1977 began on January 26 and continued weekly to biweekly through June 6, 1977. 8.1.3.2 Fry Availability. Total fry catches at Skagit Basin sampling sites using electrofishing were tabulated by species and dates. However, these catches were not from standardized effort, but were the total catch of fry for size and condition and for diet studies for each sampling period. To achieve the desired sample size more effort was re- quired early and late in the rearing season for a particular species than during mid-season. Surplus fish in mid-season were often passed over without being counted. While not strictly quantitative, these data can give a general picture of fry abundance during the sampling period. Fry catch tables also indicate the earliest and latest dates fry were available. Fry densities at Skagit River sites were calculated from the 312 standardized electrofishing effort for chinook fry in 1976, 1977, and 1978; for pink fry in 1978; and for chum fry in 1977 and 1978. These data were plotted over time to show seasonal changes in fry density. 8.1.3.3 Fry Size and Condition. Fry for size and condition factor analysis were generally brought alive in jars of water to the laboratory in Newhalem. Fry were anesthetized with MS-222, drained in a wire strainer, measured from tip of snout with jaw closed to fork of tail to the nearest millimeter, and sorted into 5-mm length groups. In 1974 and 1975, wet weights of each length group were measured to the nearest tenth of a gram (0.1 g) on an Ohaus triple beam balance. In 1975, some fry were frozen until they could be transported to Seattle were fry were dried in a Stable Therm laboratory oven at 60°C. Dried fry were weighed by length groups to the nearest ten thousandth of a gram (0.0001 g) on a type H & T Mettler balance. Beginning December 1975, wet weights of each 5-mm length group were obtained to the nearest hundredth of a gram (0.01 g) on a top-loading ~ettler balance (PN 1210). Condition factors were computed using the formula: Condition factor (Average weight in g) x 105 (Average length in mm)3 A condition factor was computed for each 5-mm length ~roup. Then the mean condition factor, weighted by the number of fish in eAch len~th group, was computed for each sample. 8.1.3.4 Fry Diet. Fry for diet analysis were preserved in 10 percent formalin at the time of collection in 197~. For the first l months of 1976, fish for diet analysis were brought alive into the laboratory at Newhalem to he weighed anrl measured nlong with fish llSC'd f,,r condition sampling. This treatment resulted in poor preservation nf some stomach contents. StarU ng in ~1ay 1976, the catch WRS suhs<1mp1Prl in thr field and fry used for stomach Rnnlysis were preservPd in 10 percent formalin. Size and condition of these fish werP assumprl tn hr simi 1:n tn fish sampled for conditio·n Rt the sAme stntinn and time. Lengths l.<'ere recorderl at time of dissection. Year clnsses werr separated hy length frequency. Stomachs were dissected and contents of each were identified, classified, and enumerated. Intestines were not exr~minrd. 8.1.4 Results and Discussion 8.1.4.1 Chinook SAlmon Fry Avni1nhility. In the Initial VPnrs nf samplin~, lt was believed th;:~t summer-fAll chinook fry did not hegin emergence until lAte Fehrunry. OverAll, CRtch~s hv wnr nn thr First thP - r 313 sampling date, March 2, 1973, were much lower than on subsequent sampling dates, and catches were highest from the latter half of March to mid-May (Phinney 1974a). In 1974, cat~hes by WDF in March were lowest on the first of the four sampling dates (Orrell 1976). However, embryonic development studies and electrofishing in 1975 established that chinook fry emergence in the Skagit above the Cascade River began in early January and extended into May, with peak emergence possibly occurring from late January to early February (Sec. 7.0). In 1976, chinook fry from the 1975 brood were first encountered by electrofishing in the Skagit River on January 5, and were present in subsequent weekly samples (Table 8.1). In the standardized sampling beginning January 23, 1976, chinook fry were present at the County Line and Rockport stations and increased in abundance to mid-March (Fig. 8.2 and Table 8.2). At the County Line Station, catches were highest on April 13, then declined to low abundance by ~ay 19. At Rockport Station, fry densities were highest in late Harch and remained rather constant to April 22. The 1976 brood was first encountered by electrofishing on December 2, 1976 (Table 8.3). The chinook fry density reached maximums at the Marblemount Station on February 25, 1977, and at the County Line Station on March 8 (Fig. 8.2 and Table 8.4). Densities were lower at Rockport and reached a less distinct peak on March 4. The earlier emergence timing of the 1976 brood was to a large extent the result of warmer incubation temperatures in 1976-1977 (Sec. 7.0). First appearance of chinook fry was later in the tributaries than in the mainstem Skagit. In 1976, fry apppeared in the mainstem on January 5, in the Sauk River on January 21 (1 fish), in the Cascade River on February 11, in Bacon Creek on February 27, in Goodell Creek on March 25 (one fish), and in Diobsud Creek on March 25 (Table 8.1). The later emergence in tributaries is related primarily to lower mean incubation temperatures. In 1977, first emergence was earlier, but the pattern of later initiation of emergence in tributaries was repeated, except that emergence began as early in the Sauk River as in the mainstem Skagit above the Sauk. The first fry appeared during mid-January in the three creeks except for one precocious fry in Bacon Creek (Table 8.3). In 1976, chinook fry catches in Goodell and Diobsud creeks were small. First appearance was later and last catches were earlier than at any other sampling station (Table 8.1). In 1977, the catches in these two creeks were larger and extended over a longer period. Chinook fry from the 1977 brood were first encountered in mid-Decem- ber, 1977, at the Marblemount Station and at the Sauk River and were pre- sent at all sites monitored except the Cascade River by mid-January, 1978 (Table 8.5). This table, like Tables 8.1 and 8.3, presents total fry catches by electrofishing. Some fry were used for size and condition studies, some were used for diet studies, while some were released. Thus, total effort varied and these 'catches were not quantitative. The Concrete Station was not sampled until late February, 1978, when a low catch of 314 ~ Table 8.1 Chinook fry catches at Skagit Basin sampling sites using electrofisher, 1975 brood. Skagit River at County Talc Marble-Rock-Cascade Sauk Goodell Bacon Diobsud ,._, Date Line Mine mount port River River Creek Creek Creek -1975 12/19-1/3 1976 1/4-:.-1/10 2 13 1/11 -1/17 6 23 1/18 -1/24 17 7 31 10 1 1/25 -1/31 30 1 25 2/1 -2/7 28 28 45 30 11 2/8 -2/14 36 35 39 10 23 2/15 -2/21 28 11 49 42 24 8 2/22 -2/28 41 23 26 46 33 20 3 2/29 -3/6 38 34 37 62 29 28 3/7 -3/13 49 28 113 42 25 26 3/14 -3/20 141 29 36 53 28 26 30 3/21 -3/27 110 30 60 54 25 26 1 23 25 3/28 -4/3 56 25 25 26 26 26 25 4/4 -4/10 44 32 32 27 29 19 2 30 9 4/11 -4/17 152 28 25 43 26 16 2 30 1 4/18 -4/24 25 28 24 46 34 20 27 5 4/25 -5/1 48 25 27 33 35 6 28 1 5/2 -5/8 36 22 42 28 29 3 29 1 ~-~ 5/9 -5/15 25 12 27 24 19 39 5/16 -5/22 15 10 25 27 38 7 25 5 5/23 -5/29 25 25 29 43 17 3 26 s/:.,o -6/5 31 16 38 30 7 9 ~/6 -6/12 16 29 30 32 13 24 6/13 -6/19 35 54 27 11 5 8 30 ~. 6/20 -6/26 42 34 29 32 4 11 14 6/27 -7/3 17 11 19 2 1 17 7/4 -7/10 28 21 11 1 7/11 -7/17 3 2 1 1 1 7/18 -7/24 3 8 7/25 -7/31 1 1 1 8/1 -8/7 Note: dash (-) signifies catch was zero. blank signifies sampling not conducted. - - ',_ - - 315 175--------------------------------------------~ 150 100 • 1- ~ • C3 0 (f) 0 0175 0 ~ a:::: 150 w a....125 >- a:::: 100 l.J._ :::t::: 75 0 0 z 50 -:r: u 0 50 COUNTY LINE MARBLEMOUNT ROCKPORT JAN FEB MAR APR MAY JUN JUL A 1976 l!l 19 77 X 1978 1!1 1977 X 1978 41.1976 C!l 19 77 X 1978 AUG Fig. 8.2 Chinook fry availability at Skagit River sampling sites from standardized electrofishing effort, 1976, 1977, and 1978. Table 8.2 No. Date fish 1976 1/23 1/26 12 2/ 2 26 2/ 3 2/ 9 23 2/20 34 2/24 53 2/25 3/ 1 36 3/ 5 3/ 9 49 3/17 3/19 141 ,, 3/24 3/26 91 3/30 3/31 56 4/ 7 4/ 9 39 4/13 152 4/22 43 4/30 48 5/12 1 5/19 3 316 Summary of chinook fry catch and density data from standardized electrofishing efforts at two Skagit River sampling sites, 1975 brood. County Line Rockport Area No. per No. Area No. per sampled 1000 fish sampled 1000 ( ft2) ft2 ( ft 2) ft2 9 3000 3.0 2100 5. 7 1875 13.9 22 3450 6.4 2050 11.2 3750 9.1 42 5000 8.4 2200 24.1 47 3750 12.5 2250 16.0 19 4000 4.8 2250 21.8 52 4000 13.0 2250 62.7 54 4000 13.5 2250 40.4 17 3000 5.7 2250 24.9 22 3000 7.3 2250 17.3 2250 67.6 43 4000 10.8 2250 19.1 46 < 4000 11.5 2250 21.3 1000 1.0 1000 3.0 lfll:ll!l'•• ~ """ -- ~ ~j - -< ,<,"~ 317 Table 8.3 Chinook fry catches at Skagit Basin sampling sites using electrofisher, 1976 brood, Ska~it River at County Talc Marble-Rock-Cascade Sauk Goodell Bacon Diobsud -Date Line Mine mount port River River Creek Creek Creek 1976 11 ""17"=" 11 I 2 o 11/21-12/4 1 1 5 12/5 -12/11 1 2 4 2 1 -12/12-12/18 4 2 13 14 8 12/19-12/25 9 5 15 15 15 12/26-1/1 19 19 11 18 29 -1977 1/~1/8 35 19 34 29 1 33 1/9 -1/15 27 18 33 32 26 1/16 -1/22 22 26 32 26 31 1 4 9 -1/23 -1/29 9 12 30 28 4 26 5 4 1/30 -2/5 69 23 77 35 11 33 8 30 2/6 -2/12 96 25 27 25 16 27 11 11 2/13 -2/19 33 28 27 22 23 30 2/20 -2/26 111 31 162 70 32 45 12 10 2/27 -3/5 197 144 109 43 38 12 13 -3/6 -3/12 186 28 30 38 25 28 10 10 3/13 -3/19 129 13 105 36 25 26 12 16 3/20 -3/26 73 26 48 51 31 27 6 14 27 3/27 -4/2 31 28 26 79 31 32 10 11 27 4/3 -4/9 62 35 37 69 38 84 9 13 27 4/10 -4/16 63 39 32 33 29 34 5 11 11 4/17 -4/23 51 13 31 18 31 34 12 12 20 ,-4/24 -4/30 139 69 35 36 33 38 12 19 12 5/1 -5/7 55 32 24 30 26 2 10 19 5/8 -5/21 46 32 40 24 37 24 7 13 20 5/22 -6/4 95 38 35 33 33 12 2 30 ~ 6/5 -6/18 69 13 5 1 2 18 1 2 23 6/19 -7/2 27 4 29 2 5 7 11 7/3 -7/16 67 2 32 6 1 2 13 7/17 -7/30 44 1 2 1 7/31 -8/13 16 15 8/14 -8/27 1 10 Note: dash (-) signifies catch was zero. blank signifies sampling not conducted. - Table 8.4 No. Date fish 1977 1/26 5 2/ 1 2/ 2 69 2/ 8 96 2/25 111 3/ 2 197 3/ 4 3/ 8 190 3/15 131 3/22 73 3/23 3/29 3/31 31 4/ 6 4/ 7 62 4/12 4/13 63 4/20 52 4/22 4/26 4/27 142 5/ 2 5/ 6 55 5/12 46 5/24 5/26 109 6/ 6 6/ 7 69 6/21 6/22 30 ' J ! J ~ Summary of chinook fry catch and density data from standardized electrofishing efforts at three Skagit River sampling sites, 19 76 brood. County Line Marblemount RockEort Area No. per No. Area No. per No. Area sampled 1000 fish sampled 1000 fish sampled ( ft 2 ) ft 2 (ft2) ft 2 (ft2) 2150 2.3 33 1000 33.0 29 2500 77 1000 77.0 34 2500 2150 32.1 2150 44.7 13 2000 2500 44.4 162 1000 162.0 70 3500 2500 78.8 144 1000 144.0 12 3500 78 3500 2150 88.4 30 1000 30.0 40 3500 2150 60.9 105 1000 105.0 36 3500 2150 34.0 51 3500 48 1000 48.0 16 1000 16.0 79 3500 2000 15.5 22 1000 22.0 54 3500 2500 24.8 13 2500 32 1000 32.0 33 3500 2150 29.3 2150 24.3 31 1000 31.0 18 3500 35 1000 35.0 2250 63.1 27 1000 27.0 2500 22.0 19 3500 2500 18.4 40 1000 40.0 16 3500 35 1000 35.0 3 3500 2150 50.7 1 1000 1.0 1 3500 2250. 30.7 1 2500 2150 14.0 27 1000 27.0 ~ J t • ' ~ ~ t ! No. per 1000 ft2 11.6 13.6 6.5 20.0 3.4 22.3 11.4 10.3 loU 1-' 14.6 CXl 22.6 15.4 5.2 9.4 5.1 5.4 4.6 0.9 0.3 0.4 J Table 8.4 No. Date fish 1977 7/ 5 7/ 7 67 7/19 46 8/ 2 8/ 3 16 8/16 2 Summary of chinook fry catch and density data from standardized electrofishing efforts at three Skagit River sampling sites, 1976 brood -continued. County Line Marblemount Area No. per No. Area No. per No. Rockeort Area sampled 1000 fish sampled 1000 fish sampled (ft 2) ft 2 (ft2) ft 2 ( ft2) 0 2500 2150 31.2 5 1000 5.0 2150 21.4 0 1000 0.0 0 2500 0 1000 0.0 0 2500 2150 7.4 2150 0.9 0 1000 0.0 0 2500 No. per 1000 ft2 o.o 0.0 o.o o.o LoJ 1-' \0 - 320 e!lil!'-n; Table 8.5 Chinook fry catches at Skagit Basin sampling sites using electrofisher, 1977 brood. Skagit River at County Talc Marble-Rock- ~ Date Line Mine mount port Concrete Cascade Sauk 1977 11/18-11/20 12/15-12/20 6 3 1978 1/11 1 1 1 1/18-1/22 6 6 4 1 2/1 32 10 2 2/10 51 10 16 2/17 48 24 51 2/24-2/26 236 34 63 37 3 37 3 3/3 191 13 10 ~ 3/10 149 20 22 3/17 228 40 3 3/24-3/27 25 27 25 19 15 37 3/31 171 14 10 4/7 169 15 15 4/13 313 10 6 4/21 26 25 25 10 25 -4/24-4/25 354 10 17 5/2 115 19 36 5/9-5/10 136 10 18 5/16-5/17 104 10 21 5/23 75 10 31 6/1 50 10 6/6 22 10 6/13 2 10 16 6/20 60 10 6/27 30 21 - Note: dash (-) signifies catch was zero blank signifies sampling not conducted - - - 321 chinook fry was made. This timing of first emergence was more similar to that of the 1975 brood than the 1976 brood, probably because temperatures during the incubation period of the 1977 brood were lower than those ex- perienced by the 1976 brood (Fig. 2.33). Fry of the 1977 brood were en- countered in the Sauk River in mid-December, but catches in the monthly sampling were low until March. Staqdardized electrofishing was started earlier in 1978 than in pre- vious years, but initial catches were low (Fig. 8.2 and Table 8.6). At the County Line Station, densities became higher than in previous years. Peak density of over 150 fry/1,000 ft2 was reached fairly late compared to previous years in late April. At the Marblemount and Rockport stations, fry densities were generally lower than in previous seasons. Peak densities were in March and February at the ~1arblemount and Rockport sta- tions, respectively. The timing of downriver and seaward migration of summer-fall chinook fry is not well defined. In 1974 sampling conducted by WDF showed that chinook fry had reached the lower river by the first sampling date, April B. By June, the numbers still present in the mainstem upriver areas and the tributaries were greatly reduced. In 1977, the University of Washington Cooperative Fishery Research Unit collected fish samples in the salt marsh at the mouth of the Skagit River. Juvenile chinook salmon were collected as early as March 23, 1977 (J. L. Congleton, Assist. Professor, .u.w., Cooperative Fisheries Research Unit, personal communication). Preliminary results from our 1978 marking study indicated that fry marked upstream of Harblemount before March 18, 1978, were found downstream of Rockport by April and Hay. In 1976, chinook fry catches began to diminish in June and July at the iiver stations and in Bacon Creek. Chinook fry were unavailable by August 1 at all study sites (Table 8.1). In 1977, despite the earlier emergence, there were still chinook fry present ·at most sampling sites as late as or later than in 1976 (Table 8.3). This extra rearing time helped send them to sea at a larger size than in 1976 (Sec. 8.1.4.2) which may favorably influence their return as adults. As in 1976, chinook fry catches at the Skagit sites began declining around early July. The Rockport Station, the farthest downstream of the Skagit River sites, had low catches first. Goodell and Bacon creeks stopped yielding chinook fry somewhat earlier than the upper three Skagit sites, while Diobsud yielded its last chinook fry in the second week of July. The Sauk had a late second peak of large fish that were possibly spring chinook from the Suiattle River. In 1978, fry densities from the standardized sampling had dropped to zero in early to mid-June, then showed a late pulse at the County Line and Marblemount stations (Fig. 8.2 and Table 8.6). However, additional effort on these June sampling dates yielded a different pattern of fry availability at the Marblemount Station (Table 8.5). On the last sampling date, June 27, chinook fry were still present at the County Line and Marblemount stations. Table 8.6 No. Date fish 1978 1/11 1 l/18 6 l/19 2/ 1 33 2/10 53 2/17 54 2/24 249 3/ 3 195 3/10 153 3/17 228 3/31 179 4/ 7 173 4/13 321 4/24 354 4/25 5/ 2 115 5/ 9 5/10 136 5/16 5/17 104 5/23 77 6/ 1 52 6/ 6 25 6/13 2 6/20 65 6/27 33 Summary of chinook fry catch and density data from standardized electrofishing efforts at three Skagit River sampling sites, 1977 brood. County Line Marblemount RockEort Area No. per No. Area No. per No. Area sampled 1000 fish sampled 1000 fish sampled ( ft 2 ) f t 2 (ft2) f t 2 (ft2) 2250 0.4 3 1000 3.0 1 3000 2250 2.7 4 1000 4.0 0 4000 2250 14.7 10 1000 10.0 3 4000 2250 23.6 11 1000 11.0 18 4000 2250 24.0 .2 7 1000 2 7.0 52 4000 2250 110. 7 30 1000 30.0 20 4000 2250 86.7 13 1000 13.0 10 4000 2250 68.0 20 1000 20.0 22 4000 2250 101.3 40 1000 40.0 3 4000 2250 79.6 14 1000 14.0 High water 2250 76.9 15 1000 15.0 15 4000 2250 142.7 2 1000 2.0 6 4000 2250 15 7. 3 10 1000 10.0 17 4000 2000 57.5 19 1000 19.0 36 4000 5 1000 5.0 18 4000 2000 68.0 5 1000 5.0 23 4000 2000 52.0 2000 38.5 2 1000 2.0 33 4000 2000 26.0 1 1000 1.0 0 4000 2000 12.5 0 1000 0.0 High water 2000 1.0 2 1000 2.0 16 4000 2000 32.5 0 1000 0.0 High water 2000 16.5 21 1000 21.0 0 4000 No. per 1000 ft2 0.3 0.0 0.8 IL5 13.0 5.0 2.5 5.5 w N 0.8 N 3.8 1.5 4.3 9.0 4.5 5.8 8.3 0.0 4.0 0.0 ----------- 1 \._,, - - 323 8.1.4.2 Chinook Salmon Fry Size and Condition after Emergence. The changes in length, weight, and condition factor over time are not neces- sarily the result of growth alone because the extent and timing of fry mixing and migration is largely unknown. Confounding factors could include protracted emergence of small fry from the gravel, emigration of larger fry to deeper, faster flowing rearing areas or downstream, and immigration of larger fry from upstream. To some extent in 1976 and 1977, deeper, faster areas were sampled both with the backpack shocker and with the boat shocker without finding larger chinook fry. Results from incubation studies suggested that earlier-emerging fish were smaller than later-emerging fish (Sec. 7.5.3). The mean lengths, weights, and condition factors of the 1973 brood of chinook fry captured by electroshocking in 1974 are presented in Tables 8.7 through 8.14. Sampling was conducted over only part of the period that chinook fry are now known to be present in the area. The trends in the length~ weight, and condition factor changes were similar to those seen in 1974 through 1976 broods. There was an initial period when the mean size and condition parameters in~reased only slightly. Then they increased aburptly, in this case in May, a little later than in 1975, 1976, or 1977, probably because the temperatures over the incubation and rearing periods were cooler than usual in the 1973-1974 incubation and rearing season, according to SCL records. The range of lengths increased through the rearing period. Small fish were present through May and June, indicating a prolonged emergence of small fish from the gravel. Tables 8.15, 8.16, and 8.17 show the mean lengths, mean dry and wet weights, and mean condition factors (wet and dry) from chinook fry of the 1974 brood from the upper three Skagit sites, and the Sauk and Cascade rivers. Dry weights were taken of 1,663 fish--910 from the Skagit, 501 from the Sauk, and 252 from the Cascade. Dry weights were thought to be more accurate because of results in laboratory experiments which reportedly indicated that starving fish would absorb water to maintain body shape. Apparently, chinook fry in our sample area were not often under that degree of stress because wet weights were found to be about six times the dry weights with little variation. Over the sampling period, January through July 1, the average lengths, dry weights, and condition factors for Skagit fry sampled for dry weights were 41.6 mm, 0.1169 g and 0.153, respectively (Table 8.18). Averages were unweighted means for all samples from which dry weights were made. This compares to 43.8 mm, 0.1565 g and 0.165 for the Sauk; and 43.2 mm, o:1396 g, and 0.161 for the Cascade. Skagit fry averaged shorter than the fry from the other two rivers, and their average condition factor was the lowest of the fry from the three rivers. Over the estimated period in which the majority of emergence occurred (January to April 15) (Table 8.18), Skagit fry had an intermediate condition factor, were slightly smaller in average length, and had a slightly lower average dry weight. However, through part of the emergence period (February and March) Skagit fry averaged slightly higher or very close in condition to fry from the other two systems (Fig. 8.3). After mid-April, Cascade and particularly Sauk fry showed a trend toward better condition. The fact ~"'- 324 -- Table 8.7 Mean lengths, weights, and condition factors of Skagit River chinook fry captured by electroshocking """' at sites near County Line, 1973 brood. Number Length (mm) Mean Mean condition Date of fish Range He an weight (g) factors 1974 Feb 14 22 38-44 41.2 o.ss 0.79 ~· 2S 18 37-43 40.3 O.S9 0.91 Mar 11 60 37-4S 40.8 o.S7 0.84 2S 43 39-46 42.S 0.62 0.81 Apr 8 3S 38-44 40.9 0.64 0.94 10 1 41 41 0.7 1.0 17 3 40-41 40.3 o.so 0. 77 24 9 41-43 42.1 O.S9 0.79 May 6 33 36-46 41. s O.S8 0.80 8 28 38-4S 41.4 0.62 0.87 21 26 38-4S 40.9 0.72 1.04 ~ 21 23 37-47 40.7 O.S8 0.84 Jun 13 2S 36-43 39.9 0. 72 1.13 - Jul 3 24 38-S8 44.3 1.08 l.lS 3 18 39-SO 43.2 1.01 1. 24 -Aug lS 1 so so 1.6 1.3 .... ~1 tr><J!r!tJ. 325 Table 8.8 Mean lengths, weights, and condition factors of Skagit River chinook fry captured by electroshocking at sites near Talc Mine, 1973 brood. F"~ Mean Number Length (nnn) Mean condition Date of fish Range Mean weight (g) factor 1974 Feb 15 15 39-43 40.9 0.51 0.75 26 76 39-48 41.7 0.56 0. 77 Mar 12 71 37-44 41.4 0.54 0.75 -26 20 37-45 41.2 0.64 0.91 Apr 9 24 38-47 40.9 0.56 0.82 ,_ 17 23 33-43 40.2 0.59 0.89 23 10 40-45 42.4 0.62 0.81 May 7 43 38-47 41.2 0.64 0.91 20 22 38-48 42.8 0. 71 0.91 Jul 5 1 45 45 0.90 0.99 - - ~ 326 Table 8.9 Mean lengths, weights, and condition factors of Skagit River chinook fry captured by electroshocking at sites near Marblemount, 1973 brood. Mean Number Length (mrn) Mean condition -Date of fish Range Mean weight ~g} factor 1974 Feb 15 46 37-45 41.3 0.54 0. 77 22 78 37-45 40.3 0.57 0.88 26 62 33-45 40.7 0.55 0.80 Mar 12 68 33-45 41.5 0.57 0.80 - 26 45 39-44 41.1 0.61 0.87 Apr 9 44 38-46 41.4 0.70 0.97 17 34 37-46 41.8 0.69 0.94 23 34 38-48 40.6 0.54 0.81 May 7 36 37-46 41.3 0.63 0.88 20 30 41-53 44.1 0.79 0.91 Jun 12 13 37-47 43.5 0.83 1. 00 Jul 2 2 46-47 46.5 1.10 1.09 ~ - ,- 327 ,- Table 8.10 Mean lengths, weights, and condition factors of Cascade River chinook fry captured by electroshocking, --1973 brood. ,..,.. Mean Number Length (mm) Mean condition - Date of fish Range Mean weight (g) factor 1974 ,_ Feb 22 llO 34-46 40.4 0.55 0.82 27 63 34-46 39.3 0.48 0.79 Mar 3 33 37-45 40.8 0.54 0.78 26 51 36-45 40.4 0.56 0.84 Apr 9 37 36-42 38.7 0.51 0.87 17 26 37-42 40.0 0.53 0.82 23 49 38-45 39.9 0.59 0.92 -May 7 34 36-45 40.6 0.61 0.90 21 12 38-45 40.9 0.59 0.85 Jun 12 19 38-51 44.5 1.07 1.17 Jul 2 7 41-54 47.6 1.46 1.35 r- - 328 Table 8.11 Mean lengths, weights, and condition factors of Sauk -· River chinook fry captured by electroshocking, 1973 brood. Mean Number Length Cmrn2 Mean condition Date of fish Range Mean weight (g) factor ..., 1974 Feb 21 30 30-43 34.9 0.53 1.25 27 50 33-43 39.9 0.50 0.79 ~ Mar 13 58 37-44 40.0 0.50 o. 77 26 70 33-46 41.2 0.62 0.88 Apr 9 32 37-45 41.0 0.65 0. 92 23 36 39-50 43.0 0.81 1.01 -May 7 18 38-45 41.0 0.68 0.98 21 13 39-59 47.2 1.16 1. 03 Jun 13 4 46-53 49.8 1.88 1. 50 ~,~, Jul 3 5 40-54 49.0 1.82 1.58 """ " - 329 Table 8.12 Mean lengths, weights, and condition factors of Goodell Creek chinook fry captured by either electroshocking o~ fyke netting, 1973 brood. Mean Number of fish Length (mm) Range Mean Hean condition Date 1974 Mar 13 25 Apr 8 10* 10 17 24 May 6 20 27 21 8 2 2 9 6 2 s. *fyke net sampling 38-44 40.7 39-45 42.1 38-43 39-41 41 41-44 39-45 43-47 38-48 40.1 40.0 41.0 42.2 41.4 45.0 45.4 weight Sg )--'-__ f....:a....:c....:t....:o-'-r ___ _ 0.55 0.64 0.61 0.60 0.70 0.63 0. 77 1.0 0.86 0.82 0.86 0.94 0.94 1.02 0.84 1.09 1.1 0.88 330 Table 8.13 Mean lengths, weights, and condition factors of Bacon Creek chinook fry captured by either electroshocking or fyke netting, 1973 brood. Number Length (nnn) Mean Date of fish Range Mean weight (g) 1974 A---pr-9* 42 37-43 40.9 0.58 10* 30 36-44 41.1 0.60 10 20 37-44 40.0 0.63 17 27 37-45 40.3 0.61 23 26 38-49 41.4 0.62 May 8 21 38-45 40.7 0.58 20 13 38-42 40.3 0.58 21* 2 40-42 41.0 0.45 Jun 13 10 39-47 42.7 Jul 3 4 41-49 44.0 1. 25 *fyke net samples - - Mean condition factor 0.82 0.86 0.97 0.92 .... 0.86 0.85 0.90 0.65 1.44 - - ~. 331 f~ Table 8.14 Mean lengths, weights, and condition factors of Diobsud Creek chinook fry captured by either electroshocking or fyke netting, 1973 brood. Mean Number Length (rnm) Mean condition Date of fish Range Mean weight (g) factor -1974 Mar 12 45 39-45 41.1 0.56 0.80 25 38 39-46 42.0 0.60 0.81 r~ Apr 10 30 34-43 37.3 0.52 1.00 17 32 33-45 38.7 0.48 0.83 -23 37 38-49 42.0 0.61 0.83 May 7* 8 39-44 41.3 0.61 0.87 8 29 38-47 41.7 0.63 0.86 -20 21 39-54 42.9 0.75 0.92 21* 5 39-42 40.2 0.46 0.72 Jun 13 14 36-45 39.0 0.61 1.03 Jul 2 12 37-49 41.5 0.73 0.97 18* 1 46 46 2.0 2.0 *fyke net samples I~ - - - 332 Table 8.15 Mean lengths, weights, and condition factors of chinook fry from the upper three Skagit sites captured by electroshocking, 1974 brood. Average Average Condition Condition dry wet factors factors Number Length (mm) weight weight dry wet Date fish Range Mean (g) (g) weight weight 1975 Jan 7 3 38-40 38.7 0.45 0.78 8 7 36-42 39.6 0.0781 0.49 0.121 0.76 14 17 36-42 39.1 0.0820 0.52 0.137 0.84 18 37 36-42 38.8 0.55 1.01 21 34 34-41 38.6 0.0864 0.50 0.145 0.86 Feb 1 29 36-42 39.4 0.0876 0.57 0.144 0.95 4 47 36-43 39.9 0.0891 0.58 0.141 0.82 11 30 36-44 40.0 0.0894 0.54 0.140 0.84 18 30 37-43 40.4 0.0876 0.53 0.132 0.79 25 15 38-42 40.9 0.53 0.74 Mar 4 30 38-43 40.9 0.0947 0.57 0.138 0.83 11 30 38-44 41.5 0.0967 0.58 0.138 0.80 25 26 38-46 40.6 0.0987 0.64 0.147 0.95 Apr 1 42 38-45 40.1 0.1048 0.63 0.148 0.89 8 56 39-47 42.6 0.1126 0.69 0.152 0.93 15 63 39-47 42.0 0.1180 0.70 0.158 0.94 22 66 37-49 41.6 0.1130 0.70 0.154 0.95 May 2 119 36-51 42.3 0.1276 0.79 0.159 0.99 13 93 38-49 42.1 0.1152 0.75 O.l52 0.99 29 83 38-54 44.9 0.1644 0.99 0.182 1. 09 Jun 16 49 37-51 43.5 0.1426 0.86 0.163 1.03 25 19 39-54 44.9 0.2134 1.12 0.198 1.19 Jul 1 41 40-57 47.9 0.2371 1. 41 0.208 1. 26 14 13 42-56 49.9 1. 55 1.22 Aug 1 68 45-64 55.4 2.11 1. 23 22 3 56-72 66.0 3.80 1. 26 - -- - •• c ~. -, .. _.:• :· .~ ·t;:~ ,-,, ~ '' ''' - - .. ~~ ._ .. -·t;'· ~ - """' ~~ - - ·- - - 333 Table 8.16 Mean lengths, weights, and condition factors of Sauk chinook fry captured by electroshocking, 1974 brood. Average Average Condition Condition dry wet factors factors Number Length (mm) weight weight dry wet Date fish Range Mean (g) (g) weight weight 19 75 Jan 7 8 8 37-42 39.6 0. 0728 0.48 0.117 0.78 14 5 37-41 38.4 0.0866 0.44 0.153 o. 77 18 21 Feb 1 4 14 39-41 40.3 0.0868 0.50 0.132 0.76 11 12 38-42 40.1 0.0853 0.50 0.132 0.78 18 25 l1ar 4 10 37-43 39.6 0. 0811 0.50 0.131 0.80 11 15 37-45 40.9 0.0967 0.57 0.141 0.84 25 22 38-45 41.5 0.1034 0.65 0.144 0.90 Apr 1 38 37-49 41.4 0.1187 0.72 0.165 1. 00 8 35 39-54 44.6 0.1517 0.96 0.167 1.08 15 55 39-50 43.4 0.1392 0.86 0.167 1.05 22 41 39-57 46.0 0.1699 1. 06 0.168 1.05 May 2 67 39-60 44.8 0.1571 0.98 0.168 1.05 13 54 36-53 43.1 0.1510 0.84 0.170 1. 02 29 55 37-65 50.1 0.2558 1. 52 0.195 1.14 Jun 16 25 40-57 50.3 0.2873 1. 60 0.223 1. 21 25 24 39-62 50.8 0.3335 1. 69 0. 213 1.22 Ju1 1 21 41-57 50.0 0.2841 1. 70 0.219 1. 33 14 7 55-63 58.7 3.00 1.49 Aug 4 43 58-83 71.1 4.40 1.19 22 8 70-77 72. 5 5.38 1. 41 334 ~ Table 8.17 Mean lengths, weights, and condition factors of Cascade chinook fry captured by electroshocking, 1974 brood. - Average Average Condition Condition ~~ dry wet factors factors Number Length (mm) weight weight dry wet Date fish Range Mean (g) (g) weight weight ~' 1975 "J"ail 7 8 14 18 21 Feb 1 4 11 18 10 41-43 41.9 0.1050 0.61 0.143 0.83 25 5 38-42 40.6 0.52 0. 77 Mar 4 12 37-43 40.6 0.0879 0.53 0.131 0.79 """'"' 11 10 37-46 40.3 0.0835 0.51 0.129 0. 76 25 10 37-45 40.7 0.1010 0.61 0.146 0.89 """' Apr 1 13 39-45 41.5 0.1039 0.63 0.144 0.88 8 24 39-42 40.4 0.0890 0.57 0.135 0.86 15 23 37-45 41.3 0.1044 0.66 0.146 0.92 22 20 38-46 41.7 0.1125 0. 71 0.154 0.97 May 2 41 39-51 42.6 0.1386 0.86 0.182 1. 09 13 21 39-48 43.6 0.1555 0.90 0.184 1. 07 f'!'!"', 29 23 39-57 47.6 0.2022 1. 23 0.180 1.10 Jun 16 17 39-60 46.6 0.2019 1. 23 0.185 1.16 25 20 37-63 48.3 0.2282 1. 33 0.189 1.12 Jul 1 8 39-59 47.8 0.2409 1.45' 0.208 1. 28 14 11 46-66 54.7 2.14 1. 25 Aug 4 3 56-66 61.0 2.73 1. 20 22 11 56-78 66.6 3.80 1. 25 ~~ ~' - 335 Table 8.18 Mean lengths, dry weights, and condition factors -of chinook fry captured by electroshocking, 1974 brood. Average Condition Average dry factor Number length weight dry River Time period fish (mm) (g) weight 1975 Skagit January-April 15 378 40.2 0.0923 0.140 April 15-July 1 533 43.7 0.1539 0.172 January-July 1 911 41.6 0.1169 0.153 Sauk January-April 15 159 40.7 0.0981 0.142 April 15-July 1 342 47.3 0.2222 0.190 January-July 1 501 43.8 0.1565 0.165 Cascade January-April 15 79 40.9 0.0951 0.138 April 15-July 1 173 44.9 0.1730 0.179 January-July 1 252 43.2 0.1396 0.161 - 336 .24 6 SKAGIT RIVER ~ SAUK RIVER .23 + CASCADE RIVER .22 . 21 .20 0::: 0 f-. 19 u c::( LL. z: . 18 0 ...... f-....... Cl . 17 z: 0 u f-. 16 :I: l!l ...... w . 15 3 >- 0:::: Cl . 14 . 13 . 12 .11 . 10 JAN FEB MAR t~AY t1UL Fig. 8.3 Mean dry weight condition factors of Skagit, Sauk, and Cascade chinook fry taken by electrofishing, 1974 brood. -: ~ ~'I -· """' -· ~ ~ ~- ,·;~ - I~ 337 that the condition of Skagit fry was eventually surpassed by the condition of fry from the Sauk, and Cascade, may be due to racial differences in the stocks, to environmental differences in the rivers affecting the fish after emergence, or to differences in the timing of fry emergence or migration in the Skagit, Sauk, and Cascade. Mean length, weight, and condition factors from samples of more than one fish are presented for the 1975 and 1976 broods in Figs. 8.4 through 8.36. The sizes of samples for this analysis are shown in Figs. 8.37 to 8.42. For each brood, the Skagit River sites were similar in timing of initial emergence, apparent growth, and time of disappearance (Figs. 8.4, 8.5, 8.15, and 8.16). Regionally distinct groups of chinook fry were thus indiscernible. Fry from the Skagit creeks each year showed growth similar to fry from the Skagit, but emerged later and disappeared sooner (Figs. 8.7, 8.8, 8.18, and 8.19). Temperature during the incubation period appears to affect timing of first emergence. In both the 1975-1976 and 1976-1977 fry rearing seasons, the Cascade River and the minor Skagit tributaries yielded their first samples of chinook fry about a month later than the Skagit and Sauk rivers, probably because of the cooler temperatures in the smaller streams (Figs. 8.9, 8.10, 8.13, and 8.14). The 1976 brood of chinook fry started emerging a month or more earlier at all sites in the winter of 1976-1977 than the 1975 brood appeared in the winter of 1975-1976. (Figs. 8.6, 8.9, 8.10, 8.11, and 8.12). The Sauk River was most strongly affected (Fig. 8.12). This earlier emergence can be explained by accelerated egg development due to milder temperatures in the winter of 1976-1977 (Figs. 2.28 and 2.29). Both brood years show an initial period of low apparent growth and close similarity between all river sites, then an accelerated size increase in April (Figs. 8.13, 8.14, 8.24, and 8.25). Exceptions to this initial level period are the first fry from the Sauk and the Skagit rivers for the 1976 brood which not only emerged several weeks earlier in the year than the 1975 brood, but also averaged smaller in length and weight (Figs. 8.6, 8.12, 8.17, anr! 8.23). Sampling with the electrofisher began in both seasons prior to the appearance of emergent fry. Average lengths and weights of the 1976 brood from the Skagit and Sauk rivers became comparable to initial levels of the 1975 brood by January 1977. The initial level period is partly due to continuing emergence of small fish through this period. Due to decreasing temperatures over the spawninp period, emergence is protracted into April (Fig. 7.13). Chinook fry with unabsorbed yolk have been collected as late as May (Sec. 8.1.4.3). The end of this initial level period may indicate the point in time when the number of smaller fry emerging from the gravel began to decrease 338 70.0 ...------------------------~-- ~ ~ COUNTY LINE -e-TALC MINE 60.0 -+-MARBLEMOUNT :I: I: ~ ROCKPORT I: t I- ·0 50.0 z w _J z cr: w I: 40.0 30.0 DEC JAN FEB MAR APR PlAY JUN JUL AUG 1975 1976 Fig. 8.4 Mean lengths of chinook fry from the four sites. 19 75 brood. 70.0 LEGEND -e-courm LINE -a-TALC MINE 60.0 -+-MARBLEMOUNT ~ I I~ I L: ROCKPORT /t/ L: ::r: I- 0 50.0 z w _J z cr: w :I: 40.0 DEC JAN FEB MAR APR MAY J~N JUL AUG 1976 1977 Fig. 8.5 Mean lengths of chinook fry from the four Skagit sites. 1976 brood. Skagit I""'', ~1 .. I' _I - - - 339 40.0 Jf}.tl r r ~)_ !liN .Jill I _j . 8.6 Mean lengths of chinook fry for Skagit sites, combined, 1975 brood compared 'l.vith 1976 brood. 34u 70.0 LEGEND ----BACON CREEK ....... DIOBSUO CREEK 60.0 L: L: I I- D 50.0 z w __J z a: w L: 40.0 30.0 ~----~----~--~----~----~--~~--~----~----~-- DEC JAN FEB MAR .~PR MAY JUN JUL 1975 1976 Fig. 8.7 Mean lengths of chinook fry from Skagit creeks, 1975 brood. L: L: I I- D z w __J z a: w L: 70.1) 60.0 50.0 40.0 LEGEND _.... GOODELL CREEK ..._ BACON CREEK ....... D!OBSUD CREEK AUG 30:0~----~----~--~----~----~--~~--~----~--~L_~ DEC 1976 JAN FEB MAR APR MAY JUL 1977 Fig. 8,8 Mean lengths of chinook fry from Skagit creeks, 1976 brood. AUG ~ - - ~{ - - - - - - ·- -341 .,., ... t ~ """"*-SKAGIT (COtlBI~ED) i -+--CREEKS (COMBINED) 60.0 t I L: + L: I ::r: I I-I l c 50.0 + z I w ' I z I a: r u...; L: 40,J t :.!'· I I .l 30.J ~----~----~--~----~--~-----L--~~--~~--~-- Fig. 8.9 60.0 L: L: ::r: I- 0 50.0 z w _j z <I w L: 40.0 ... I 30.0 Fig. 8.10. DEC 1975 JAN .~PR ~~JI.Y 1976 JU~ .JUL .~UG Mean lengths of chinook fry, Skagit sites, combined, and Skagit creeks, combined, 1975 brood. --*-SKAGIT (C0~1BINED) -+-CREEKS (COMBINED) DEC JAN FEB MAR APP. ~AV 1976 1977 Mean lengths of chinook fry, and Skagit creeks, combined, JUN JUL AUG Skagit sites, combined. 1976 brood. ..342 70.0 LEGEND -e-75 BROOD """*"" 76 BROOD r r 60.0 I I 1- D z w ...J z 50.0 cr: w r ~ 40.0 30.0~----~--~----~--~----~----~--~----~--~--~ DEC JAN FER MAR APP ~~y JUN JUL AUG Fig. 8.11 Mean lengths of chinook fry from the Cascade River, 1975 and 1976 broods. 80.0 LEGENIJ -e-75 BROOD """*"" 76 BROOD 70.0 r r 60.0 I 1- D z w .....) z 50.0 cr: w r 40.0 30.0~----~--~----~--~----~----L---~----~--~--~ DEC JAN FEB MAR APR JUN JUL Fig. 8.12 Mean lengths of chinook fry from the Sauk River, 1975 and 1976 broods. AUG ~, """' -· ' -~ - """" - ""'1 - - --' - - - ::c ::c I: ~ C!l z w _j z a:· w ::c Fig. 8.13 ::c ::c I: ~ d z w _j z a: w ::c .343 j,j. J r---------------------··----· LEGEND -f9-SKAGIT (COMBINED) 60 '! ~ CASCADE R. --6--SAUK R. I I 50.0 40.0 ~o.o~·~--~--~--L--~----~----~--~----~-----L-- 1975 Mean lengths and from the LEGEND FEB MAR APR MAY JUN JUL AUG 1976 of chinook fry from the Skagit sites, Cascade and Sauk rivers, 1975 brood. -f9-SKAGIT ~COMBINED) ~ CASCADE R. 70.0 --6--SAUK R. 50.~ 5~.0 40.0 !8.0 ~----L-----L----~----~--~----~----~---~----~~ nrr MAR ~00 Ill~ .Jill AUG 1976 1977 combined, Fig. 3.14 Mean lengths of chinook fry from the Skagit sites, combined, and from the Cascade and Sauk rivers, 1976 brood. 0 f- 6 w :::;:: z a: w L: Fig. 8.15 0 f- 6 ...... w :::;:: z a: w E 344 5.) 1 LEGEND l-e-CGUNTY Ll N£ 4.0 -er TALC MINE -+-MARBLEI~OUNT ""*""" ROCKPORT 3.0 2.0 1.0 0 nFr JAN FEB MAR APP 'IAV JUN JUL AUG 1975 1976 Mean weights of chinook fry from the four Skagit sites, 1975 brood. 4.U ~ -e-COUNTY LINE 3.0 -er TALC MINE -+-MARBLEt10UNT 2.0 1.0 oLL--~----~--L---~--~--~--_J----~--J--~ 8E~ 1976 JAN FEB MAR APD ~1AY JUN .JUL AIIG 1977 Fig. 8.16 Mean weights of chinook fry from the four Skagit sites, 1976 brood. ~ - - - - _, tiif!W, ~" - - 345 - 5.0 LEGEND ~ 75 BROOD 4.0 -*""" 76 BROOD '""" 0 f- ~ C5 3.0 w :::;::: z a: w :1:: 2.0 -101 """' J. DEC .JAN FEB MAR APR r.~AV JUN JUL AUr. Fig. 8.17 Mean weights of chinook fry for Skagit sites, combined, 1975 brood compared with 1976 brood. .J4b 5.0 . LEGEND ...... BACON CREEK 4.0 ---DIOBSUD CREEK 0 3.0 1- 5 w 3: z 2.0 a: w l: 1.0 0 DEC JAN FEB MAR APR r1AY JUN JUL AUG 1975 1976 Fig. 8.18 Mean weights of chinook fry from Skagit creeks, 1975 brood. 1.0 0~----~--~~--~--~----~----~--~----~--~--_J DEC 1976 JAN FEB MAR APR MAY JUN JUL 1977 Fig. 8.19 Mean weights of chinook fry from Skagit creeks, 1976 brood. AUG ~' - - - - '~ -- !""'- - ~- """" 0 f- ~ C5 w 3: z 0:: w L: 5.0 4.0 3.0 2.0 1.0 LEGEND ~ SKAGIT (COMBINED) i '-+-CREE,~S (COMBINED) 347 J ~----~----~--~----~-----L---~----~----~--~--~ jEC 1975 JAN FEB MAR APR :~AY 1976 JUN JUL ~UG Fig. 8.20 Mean weights of chinook fry, Skagit sites, combined, and Skagit creeks, combined, 1975 brood. :0 .~ ! ----·--------------------------------------- LEGEND ~ SKAGIT (COMBINED) 4.0 -+-CREEKS (COMBINED) 0 3.0 f- l5 w 3: z 2.0 ~ a: /;· w L: 1.0 1976 1977 Fig. 8.k1 Mean weights of chinook fry, Skagit sites, combined, and Skagit creeks, combined, 1976 brood. 348 5.0 LEGEND -6--75 BROOD 4.0 76 BROOD """*- 0 1- 6 3.0 w ::;:: z a: w / :E: 2.0 / 1. 0 J DEC JAN FEB MAR APR :·lAY JlJN JUL -'UG Fig. 8.22 Mean weights of chinook fry from the Cascade River, 1975 and 1976 broods. 6.0 LEGEND -6--75 BROOD 5.1) 76 BROOD 4.0 0 1- 6 3.0 w ::;:: z a: w :E: 2.0 1.0 D _._._ __ _.__ _ __, ___ .......__ _ __, __ _._ __ .__ DEC JAN FER t1AR APR MAV JUN JilL Fig. 8.23 Mean weights of chinook fry from the Sauk River, 1975 and 1976 broods. AUG - - - - ~-. - w 3: z a: w l:: 5.0 4. 3. 2. l. 349 LEGEND ~ SKAGIT (COMBINED) --+-CASCADE R. ..-SAUK R. DEC JAN FEB MAR APR MAY JUN JUL AUG 1975 1976 Fig. 8.24 Mean weights of chinook fry from the Skagit sites, combined, and from the Cascade and Sauk rivers, 1975 brood. Fig.8.25 ------·---- LEGEND 5.0 ~ SKAGIT (COMBINED) -e-CASCADE R. -A-SAUK R. 4.0 3.0 2.0 1.0 0~----~--~----~----~---L----~--~----~----~~ cF•: !A~ FEB MAP AOD 'lAY liJN .lUI AIJG 1976 1977 Mean weights of chinook fry from the Skagit sites, combined, and from the Cascade and Sauk rivers, 1976 brood. ----------------------------- ~50 LEG£ NO -e-courm LINE -e-TALC MINE 0::: 1.2 -+-MARBl Et·lOUNT 0 t-u ""*" a: ROCKPORT l!... z 0 t- D z 0 u 0.8 z a: w 1:: 0.4 DEC JA~I FEG '·1AI\ ~PR ;.1AY Jt"l Jt;L Aur, 1975 1976 Fig. 8.26 Mean condition factors from the four Skagit sites, 1975 brood. Fig. 8.27 0::: 0 t-u a: l!... z 0 t--0 z 0 u z a: w 1:: 1.2 o.a 0.4 Mean 1976 '-----~---------·-··----·-·-·----~~ LEGEND 1-e--COUNTY LIN.E -e-TALC MINE -+-t~ARBlEMOUNT (r ""* ROCKPORT ~EC .IAN FEB ".AR APD ~A!Jy JliN JUL Atlr 1976 1977 condition factors from the four Skagit sites, brood. - - _,. - I - - -- - - cc 0 f-u a: l.J_ z 0 f- 0 z 0 u z a: w L: 351 LEGEND ~ 75 BROOD ~ 76 BROOD 1.2 :).8 0.4 ~----~----~--~----~----~----~--~----~----~-- DEC JAN FEB MAR APR t~AY JUN JUL AUG Fig. 8.28 Mean condition factors of chinook fry for the Skagit sites, combined, 1975 brood compared with 1976 brood. Fig. 8.29 Fig. 8. 30 352 LEGEND __._ GOODELL CREEK ...... BACON CREEK 0::: 1.2 "'"*'" DIOBSUD CREEK CJ 1-u a: 1.1.. z CJ -1-,__. 0 z CJ u 0.8 z a: w 1:: 0.4~----~----L---~----~---L----~--~----~--~--~ DEC JAN FEB t·1AR 1\PR MA' JUN JUL 1975 Mean condition Skagit creeks, 1976 factors of chinook fry from 1975 brood. 0::: a 1-u a: 1.1.. z CJ -1--0 z CJ u z a: w :L LEGEND ...... BACON CREEK ---DIOBSUD CREEK 1.2 0.8 0.~ DEC ,]AN 1976 Mean condition Skagit creeks, FEB MAR ADP l-4A> 1977 factors of chinook 1976 brood. JliN JUL fry from AUG AUG ~""'' ~ -M!t, Jifllr.$. ~ - - - - - - - - .-' - z c 0 z a u z a: w :c 1.2 ,,t I t I I I 353 ---·--- LEGEND -*-SKAGIT (COMBINED) -+-CREEKS (COf1BINED) 0.4 ~·~--~----~----~--~----~----~----~--~----~--- ~[~ JAN FEB 11AR \PR ~AY JUN JUL AUG 1975 1976 Fig. 8.31 Mean condition factors of chinook fry, Skagit sites, combined, and Skagit creeks, combined, 1975 brood. LEGEND -*-SKAGIT (COMB I NED) -+-CREEKS (COMBINED) a::: c LZ >-- '' cr: L.... z c f- 0 z 0 u 0.8 z a: w :L: 0.4~----~----~--~----~----~--~----~----~--~~~ DEC JAN FEB MAR APR MAY JUN JUL AUG 1976 1977 Fig. 8.32 Mean condition factors of chinook fry, Skagit sites, combined, and Skagit creeks, combined, 1976 brood. 354 LEGEND -&-75 BROOD ""* 76 BROOD 0::: 1.2 a f-u a: LL. z a f- 0 z a u 0.8 z a: w I: 0.4 ~----~----~--~----~--~----~--~-----L ____ L_~ DEC JAN FEB MAR APR MAY JUN JUL AUG Fig. 8.33 Mean condition factors of chinook fry from the Cascade River, 1975 and 1976 broods. 0::: a f-u a: LL. z a f-.... 0 z a u z a: w I: Fig. 8.34 ----------~------ LEGEND -&-75 BROOD ""*"-76 BROOD 1.2 0.3 i 0.4 ~--~--~-~--~--~--~-~--~---~ DEC JAN FEB MAR Mean condition factors of Sauk River, 1975 and 1976 APR MAY JUN Jlll AUG chinook fry from the broods. - - . .- ,.- -· - - .. - .-- n:: 0 I-u a: LL.. z 0 I- 0 z 0 u z a: w :L: 355 . LEGEND -6--SKAGIT (COMBINED) --+- 1.2 ~ 0.8 0.4~----~--~~--~--~~---L----~--~----~----~~ DEC 1975 JAN FEB MAR APR I~AY JUN JUL AlJG 1976 Fig. 8,35 Mean condition factors of chinook fry from the Skagit sites, combined, and from the Cascade and Sauk rivers, 1975 brood. :c 0 I-r' a: LL.. z a I- 0 z 0 (_) z a: w !: Fig. 8.36 ! LEGEND -6--SKAGIT (COMBINED) --+-CI>.SCAD E 1. 2 ~ SAUK \ \ 'o\ 0.8 0.4~~~~~~~~~~~~~~~~~~~~~~~~~~~ DEC JAN FEB MAR APR MAY JUII JUL AUG 1976 1977 Mean condition factors of chinook fry from the Skagit sites, combined, and from the Cascade and Sauk rivers, 1976 brood. w N (j) w ....J a... I: a: (/) Fig. 8.37 w N (j) w _J !1... I: a: (j) Fig. 8. 38 -356 --~ 30.01 + LEG£ND Q) [') [') C) C) + EEl + + + C) + ++ Q) (!I [!) ++ C) ~lEI (ll3 00 C)C)+ [!]) +[!] [!] [') C) + + + + [') + 20.0 [!] [') C) + [') C) (9 + C) C) (9 [') (9 + [') [') + 10.0 + [') C) [') [!] C) [!] (9 C) Cl+ if' + CI!J if' 0 r:trr JAN FEB tl!\R OPO "'AY JUN JUL AUG 1975 1976 Sizes of length, weight, and condition factor samples of chinook fry from the 1975 brood from the upper three Skagit River stations. 30.0' -----·-- X ¢ LEG£NO A X COUNTY LINE TALC MINE MARBLEMOUNT X ¢ XX X ROCKPORT • « « X ¢ ¢ o> ¢.<)(<!> X¢ X ¢ CASCADE R. ¢ ¢ X X A¢ ¢ SAUK R. X X X A 20.0 A A A ¢ A ¢ ¢ A X 10.0 X ¢ b. b. X A b. A ¢ A A A ¢ 4> &o> ¢ 0 DFC JAN FEB I~AR ~PR MAY JUN JUL AUG 1975 1976 Sizes of length, weight, and condition factor samples of chinook fry from the 1975 brood from the Rockport station on the Skagit River, the Cascade River, and the Sauk River. - - - ~ .... """"' -~ """' ~ - P'~ ?*" - - - - 357 30.0 I) I LEGEND l!r I) l!r I I) BACON CREEK I) );';Ill 0 0 0 0 0 0 I )!( DJOBSUD CREEK 0 0 w 20.0 N (f) I) w _j l!r n.. :<:::: 0: (./J 10.0 )!( )!( )!( 0 )!( )!(Jl: 0 :E:::: JM: ~~:: ~~AP. AP~ ~.·, JIJ~ Jt~t ~llr. 1975 1976 Fig. 8.39 Sizes of length, weight, and condition factor samples of chinook fry from the 1975 brood from two Skagit creeks. ---~ ---· ·-------~--- + (!) + + (!) (!) +EB Ell+fl~ tB$EBEBI~&!llmq,e+-c:J -f) [!] + [!] (!) (!) 1 LEGEND (!) COUNTY LINE I [!] TALC MINE I + r~ARBLEIIOUNT z:;. ·J C) I.J.J (!] + N [!] [!] 'J) (!) c._: + --' rt] + [!] [!] z: [!] •I + (f) 10.0 (!) (!) J [!] + ~ +[!] [!] + ~ err JAil FEB ~lAP 1\PD ~'1_."1, v 111~1 Jill AIIG 1976 1977 Fig. 8.40 Sizes of length, weight, and condition factor samples of chinook fry from the 1976 brood from the upper three Skagit River stations. 358 ;--- 30.0 LEGEND X .!.. X ROCKPORT .!. ¢>~ .!.¢> ¢>¢>¢> ¢> .!. ::.!>llliiXX)C) <!:.4>( «~<X&.!. <X ¢>¢> ¢> )C) .!. <X )(!)( X ¢> CASCADE R. w .!. .!. .!. SAUK R . w 20.0 N X X (f) w )C) _j X a... L: a: (f) 10.0 "" .!. .t. "" "" "" ¢> ¢> X ¢> "" X ¢> ¢> !Ill; .!. X 0 DEC JAN FEB MAR APR t·lAY LJl.IN' .1111 Allr. 1975 1976 Fig. B.41 Sizes of length, weight, and condition factor samples of chinook fry from the 1976 brood from the Rockport station on the Skagit River, the Cascade River, and the Sauk River. JU.U LEGEND * GOODELL CREEK 0 BACON CREEK )!( DIOBSUD CREEK 20.0 -w N (f) w _j a... L: a: 0)!( )!( (f) 10.0 )!(Ill 1!0!010!1 "*")!( -~~~~~~ )!( )!( )!( )!( * >It)!; * * 0 * >It)!; * * 0 0 0 * * )!( 0 ~EC JAN FEB t1AR APR HAY JUN JUL AUG 1976 1977 Fig. 8.42 Sizes of length, weight, and condition factor samples of chinook fry from the 1976 brood from three Skagit creeks. - - -· ~. - - 359 and older fry that had been growing for some time were more numerous than newly emerged fry. Preliminary length frequency analysis suports this contention. This point should be somewhat after peak emergence. The end of this initial level period was near Harch 20 in 1976 and near Harch 1 in 1977. Estimates derived from observations of peak spawning and temperature unit accumulation placed peak emergence for summer-fall chinook in the Skagit River at February 18 in 1976 and January 18 in 1977 (Table 7.16), five to six weeks before the end of the initial level period. Peak chinook fry abundance at the County Line Station in 1976 occurred in mid-April, several weeks after the end of the initial level period. In 1977, peak abundance at the County Line Station occurred about two weeks after the end of the initial level period, while at the l'larblemount Station, it occurred two weeks before this point (Fig. 8.2). There were several important differences between 1975-1976 and 1976-1977 in the rearing environment of the chinook fry. The 1976 brood of chinook fry experienced warmer temperatures during incubation and rearing, lower precipitation, lower water levels, increased turbidity, and higher solar radiation at all the sites, and less flow fluctutions in the Skagit. Adult returns in 1976 were higher and, for much of the rearing period, fry densities were higher in 1977 than in 1976 (Fig. 8.2). The clearest differences in length and weight between the 1975 and the 1976 broods were seen in the Skagit and Cascade rivers (Figs. 8.6, 8.11, 8.17, and 8.22). Other sites showed increased size of chinook fry in the latter part of the rearing period only. Examination of similarities in environmental contrasts between 1975-1976 and 1976-1977 in· the Cascade River and the Skagit River may help to delineate the factors most important to chinook fry rearing. Warmer temperatures in the winter of 1976-1977 apparently advanced the timing of first emergence of the 1976 brood at all stations (Tables 8.1 and 8.3). This early start and continued warmer temperatures may have, in part, produced fry larger than the 1975 brood in the Cascade and Skagit rivers. The Sauk River exhibited the largest advance in first emergence timing, yet the 1976 brood from the Sauk River did not show the distinct increase in fry size throughout the year as seen in the 1976 brood from the Skagit and Cascade rivers. The Sauk produced sane larger fry toward the end of the rearing period each year, but it is not known how much this was due to spring run chinook fry from the Suiattle River migrating through our study area. Lower precipitation resulted in lower water levels in 1977 at all sites which reduced the size of the fry-rearing environment. The unregulated Cascade was perhaps more affected than the regulated, larger, Skagit yet chin6ok fry from the Cascade and Sauk rivers showed similar between-the-year differences in chinook fry length and weipht. Thus flow apparently did not account for growth differences. Solar radiation can probably safely be assumed to be similar between the major river sites each year. 360 The Cascade and the Skagit experienced about the same increase in turbidity in 1977. This increase was much lower than the increase in turbidity in the Sauk (Tables 3.8 and 3.9). Increased turbidity was strongly indicated as a causative factor in decreased primary and secondary production at the lower Sauk site in 1977 (Sec. 3.4.3.2). Noggle (1978) found in artificial stream experiments that feeding efficiency of salmonid fry was -reduced in turbid water. In 1977, the Skagit River experienced decreased flow fluctuations (Tables 3.2 and 3.3). The Cascade River did not. However, the reduction in flow fluctuations in the Skagit were in effect primarily after May 1977, about 5 months after the 1976 brood of chinook fry began to emerge •. Later emerging species should reveal more about the effect on fry size and condition of reduced fluctuation. In summary, the environmental factor that apparently held chinook fry size and condition in the Sauk at the same level in 1977 as in 1976, but not in the Cascade and Skagit rivers, was the higher turbidity in the Sauk, which counteracted the effects of generally warmer temperatures and increased solar radiation in the 1977 fry growing season. The mean condition factor (Figs. 8.26 to 8.36) shows much more variability than do the length and weight data. This is to be expected since it is the ratio of two variable quantities, one of which is cubed. The condition factor data show less difference between brood years than do the length and weight data. Again, the Sauk River samples have very high points late in the rearing period that appear to be older fish, perhaps spring chinook from the Suiattle. After initial emergence, there is generally a slight decrease in condition factors for the first few months. 8.1.4.3 Chinook Salmon Fry Diet. The results of stomach content analysis of 412 chinook fry collected in 1975 are shown in Tables 8.19, 8.20, and 8.21. Two-hundred ·and fifty Skagit River fry stomachs, 113 Sank River fry stomachs, and 49 Cascade River fry stomachs were examined. In the 1975 study, aquatic insects accounted for the largest number of food items found in stomachs of chinook fry·except in the Skagit where, in some April samples, zooplankton (copepods and cladocerans) originating from the upstream reservoirs were in greater number. A few annelids, terrestrial insects, sand, vegetation, and unknown insect matter were also found in stomachs. The 1975 stomach samples indicated that in the Skagit and Sauk, Diptera were eaten by chinook fry more frequently than any nther drder. Of the Diptera, chironomid 'larvae were most abundant with chironomid adults next in numbers. In the Skagit samples the second most abundant component was copepods, mostly Diaptomus; third was Ephemeroptera nymphs; fourth was cladocerans (Bosmina); and fifth was Plecoptera nymphs. Unlike the Skagit samples, Sauk River fry in 1975 samples had more Plecoptera nymphs than Ephemeroptera nymphs in their stomachs. The primary food found in the 1975 Cascade River samples was Ephemeroptera nymphs, with chironomid larvae and Plecoptera nymphs second and third, respectively. - ' - - - ) ) } } ... <>, ) Table 8,19 Chinook fry stomach contents, Skagit River, 1974 brood. ·---~~~~- Date 1975 tns-~~--2Tt ~-~---zizs-----vfr-·-~zs 4/1 4/8 Sample size 38 ~~2_7~~ ___ 3_0_~ ~-_l_L_ __ _ __12._ __ 10 15 15 ~----------- Total % Total % Total % Total % Total % To["J % Total % To[Al % Foocl items no, occur.., no, occur. no. occur. OC'C'UT no occur occur~ no, occur. no. occur. ------------------ Cullembola 0.14 2. 44 1. 04 0.47 3 0.41 0.52 [•.pht.~me rop te ra nymplls 148 20.73 19 46.63 11 '. 26 50 46.30 31 32.29 31 14.42 78 10.64 17 4.45 adults I'lecnpteca nymphs 0.98 3 7. 32 19 9.09 11 10.19 1.04 3.74 0.55 12 L14 adults 2 4.98 Tr lc:hoptera larvdc 0.14 0.48 0.93 adult::> Diptera Chironomlclae pupae 2 0.28 8 3.83 2 1.85 2 0.93 1.05 larvae 548 76.75 12 29-27 120 57.42 32 29.63 26 27.08 13 6.05 19 2.59 22 5.76 adults 2 0. 28 2 0.52 f,.,.J Simullidae larvae 0.42 2-44 12 5.74 1. 85 0.26 0'\ adults ...... fflsc, Dlpte ra 1 2.44 0.48 2. o. 52 Cladocera 0.48 1.85 71 33.18 191 26.06 48 12.57 D{aptomus 4.88 28 13.40 4.63 37 38.54 88 40.93 4)7 59.62 260 68.06 Misc. aquatic 8 3.83 1.85 0.47 0.14 0.52 Mlsc. terrestrials 0.26 VLil1 eggs Unidentl fled and Inanimate material 0. 93 2.36 ------------------ Table 8,19 Chinook fry stomach contents, Skagit River, 1974 brood--Continued. Dat-e~l975 ___ 4715 ----4722 Sample size __ 1_5_____ ~1~5'--cc_ Food items Collorr.bo1a Ephcmcroptera P lecop te ra Tr lcll('pte ra Olptera Ch:l.ronomidae Slmuliidae Mi.sc. Oiptera Cladocern Diaptom11.q Mlsc. aquatic nymphs ndul ts nvrr:rlls adnl ts larvae adults pupae larvae adults larvae adults Misc. terrestrials Fish egg!'i Un !dent i fied and lnnnimate material Total % no occ11r, 12 6.19 2.06 3.61 0.52 1. OJ 94 48.45 72 37.ll 0.52 0.52 Total % no. occur, 96 4 21 1 31 84 39. 34 1. 64 1.64 8. 61 0.41 0.82 1~.70 34.43 0.41 5/2 18 Total % no. occur. Jl 42 3 9 29 99 14 15 12.45 0.40 16.87 1. 20 3.61 11.65 39.76 1. 61 5.62 6.02 0.08 5/13 17 Total % no. occur. 12 J 3 1. 20 10.98 14.63 3.66 3.66 1. 20 4 4. 88 6 7. 23 23 28.05 1 1. 2 2 9 10.84 2. 44 1. 22 6.01 3.66 5/28 17 Total 23 so 31 10 33 15 16 11.68 25.38 4.06 1. 52 15. 74 5.08 16.75 2.03 7.61 1.02 1. 02 8.12 6/16 3 Total % no: occur. 9.09 9.09 9.09 63.64 9.09 Skagit '75 co;b. 250,_ __ _ Total % no.. occur. 33 0.71 584 13 12 7 12 66 866 16 7 23 4 24 16.82 0.28 3.66 0. )5 0.09 1. 'j(J 24.94 4.81 0.66 0,09 0.69 461 13.27 1030 29.M 21 0. (,J 10 0.2 9 2 9 0. 84 . --) } Table 8,20 Chinook fry stomach contents, Cascade River, 1974 brood. -------~----------------·----· ··------------- Dat(_' 1975 3/ ll 3/25 4/1 4/8 4/15 4/22 Sample size 5 5 5 ) f'OLld i terns Total :{ Total Total Total % Total % Total no. occur. no. occur. no. occur. no. occur. no. nccur. no. occur ·------------------· CLlllL'mhoJa 4.00 3. "!1 nymphs 28.57 27.27 23.53 26.32 12.00 14 46.67 Ephcmernptera adults PLL•coptera nymrhs 42.86 18. 19 4.00 3.n adu 1 ts 4.00 Trichoptera bu·vae pur<~e 9.09 Dlpt~re~ w 5 29.41 12.00 16.6 7 Chlronomidae pupae "' larvae 14.29 6 35.29 9 4 7. 37 36.00 21.33 w adults Slmullidae LHv.Je 9.09 5.26 4.00 adults f.flsc. Diptera 5.26 Cludocera D-io.ptorrrus ~liec. <H}llo1 tiCS 5.26 H[e,·. lE'rrcstrl;tls fish pgg_s Unldenti fled nnd tnanlm.1tc material 14.29 36.36 1!. 76 6 24.00 6.6 7 -------------------------·-·-·-----. Table 8.20 Chinook fry stomach contents, Cascade River, 1974 brood--Continued. Ontc 1975 5/2 5/13 5/28 6/16 C.a.scade R. '75 comb. Snmpl~ size h 5 6 J 49 Food Total i. Total ~ Total % Total 1. Total % Items occur. occur. occur. no. occur. no. occur. no. no. no. CollC"mhola 0. 74 0.80 nymphs JO 50.85 l;5 33.33 5 29.41 37 67.27 148 39.4 7 Ephcmc rop te ra ndults 3 17.65 3. 0.80 nymphs 6 10.17 5.19 5.88 9.09 28 7. 4 7 r lccop te ra adults 5.A8 2 0.27 larvae 1.48 5.88 1. 34 Trlchoptcra pupae 5.88 .53 Olptern pupae 13.56 2 1. 48 2 3.64 25 6.67 Chi ronomidae larvae 12 20.34 62 45.93 3 17.65 4 7.27 1!3 JO.IJ adults 2 ~.39 6 4.44 5.88 ).64 11 2. 93 larvae 2' 1.48 l.JJ w S lnn•llid;>e adults 0.74 0.27 0'\ .!:'- Hlsc. Oiptera 6 4,44 5.45 10 2.6 7 Cladoce ra Diaptomus Hl$C. afluattcs 0. 74 5.88 3.64 1.33 Hl•r. t£"rrestrials Fish eggs Unidentified and lnn11lm~te mat~rial 1.1\9 In 4. 2 7 .c;.;t •.::.. ....... . ~ t ' 1 ' ~ J .~ ' l" J ~ J l ) -l l l Table 8,21 Chinook fry stomach contents, Sauk River, 1974 brood. Date 2/11 3/11 3/25 4/1 4/8 4/15 Sample size 12 5 10 10 10 Food i terns Total r-Total % Total-r-Tota~ to t a r------z--Total % no. occur no. occur no.· occur no. occur no. occur no. occur Co11embola ) 10.71 Epheme rop tera nymphs 6 21.43 9 2.44 8 15.69 5 7.81 2 2.86 adults 2 2.86 l'lecoptera nymphs 3 10. 71 3 20.00 125 33.88 9 14.06 adults Trichoptera larvae 3 20.00 adults 2 .54 2 2.86 Di ptera Chironomidae pupae 3 .81 1 1. 96 8 12.50 44 62.86 larvae 16 57.14 4 26.67 70 18.97 17 33.33 16 25.00 3 4.29 l;J adults 2 .54 0'1 2 2.86 \.J1 Simuliidae Luvae 156 42.28 1 1.51) 14 20.00 adults Mise. Diptera 1 .27 1 1.56 Cladocera Viaptomus Misc. aquatics 5 33.33 1 .27 1 1.56 Nisc. terrestrials 2 3.13 1 1.43 Fish eggs Unidentified and inanimate material 25 49.02 21 32.81 ------------------ Table 8.21 Chinook fry stomach contents, Sauk River, 1974 brood--Continued. Date 1975 4/22 S/2 5/13 5/28 6/16 Sauk R. '75 comb. Sample s lzo 10 10 13 _ ____l!t~-113 Food items folar-r-Total Tot~! % Total /, Total % Total 7, no. occur~ no. occur. no. occur. no, occur. no. occur. no. occur. Collcmbolo. .21 .29 Ephcmeroptcra nymphs 9. 72 21 61.76 49 10.38 19 18.10 59 55.14 185 13.)4 adults 2 .14 Plecoptera nymphs 3 4.17 20.59 19 4.0) 14 lJ.JJ 1) 12.15 196 14.13 adults 2.94 17 16.19 0.93 19 1.37 Trichopte ra larvae 4 .85 11 adults • 79 Dlptcra pupae so 69.44 w Chlronomidn~ 2 5.88 9 1. 91 16 15.24 0 0 133 9.59 0'1 larvae 5 6. 94 2. 94 )67 77.75 24 22.86 0'1 25 23.36 548 39.51 adults 2 2.78 5.88 2 .42 6 5. 71 2 1.87 18 1.30 Slmuliidae larvae 9 1.91 1 0.95 1 adults 0.93 182 13.12 1.06 0.95 6 .43 "lsc. Dlp te ra 5 1.06 4.76 6 5.61 18 1.30 Cladocera Dtnptomu."' Misc. aquatics 2.78 .21 o. 95 11 .79 f!lsc. terrestrials i.J9 .21 1 0.95 6 .43 Fish l\P.f~S l'nlJcntlflcd and i n,m ima tlo! material 2. 78 48 3.46 J ,-. - - - - 367 The results of chinook fry stomach sample analysis from the 1975 and 1976 broods are presented in Tables 8.22 to 8.27. The column "freq. occur." represents the percentage of non-empty stomachs in a sample group that contained a certain prey organism. The next column, "total no.", gives the total number of individuals of the prey counted in the sample group. The next column "%occur.", is the percentage by number of the prey organis~ among all prey types encountered in the sample group. Comparisons of chinook diet in 1976 to chinook diet in 1977 (Table 8.28) is especially interesting because of the environmental contrasts between these years. There was increased solar radiation and warmer temperatures, decreased water fluctuations, and increased benthic production in the Skagit in 1977. Zooplankton utilization by the chinook fry in Skagit samples was light in 1977. Increases in percent occurrence were seen in Ephemeroptera, Plecoptera, and Simuliidae. Utilization of chironomids showed a decrease in 1977. In general, the changes in diet parallelled the changes in benthic insect standing crop (Sec. 3.0), and the Skagit chinook fry diet in 1977 became more similar to the chinook fry diet reflected in Cascade and Sauk river samples. The most important contrast, perhaps, was the decrease in empty stomachs in the 1977 Skagit River samples which may indicate better rearing conditions and may help to explain the increased size of chinook fry in 1977 (Sec. 8.1.4.2). The seasonal pattern of zooplankton utilization by chinook fry has little similarity between years. In contrast, the se-asonal fluctuation in abundance in Ross Lake, the probable source of much of the zooplankton in the river, was similar over several years--1971,1972,and 1973 (SCL 1974). In 1975, zooplankton percent occurrence in stomachs of Skagit chinook fry started low, increased to late April, and then decreased (Table 8.19). In 1976, utilization of zooplankton started high and declined through the year (Table 8.22). It appeared that chinook fry as they grew might be shifting to larger prey items. In 1977, the highest percent occurrence by numbers of zooplankton in the Skagit chinook fry stomach samples was in late May, although the stomach samples from the Skagit River before and after the late May sampling period contained no zooplankton (Table 8.25). In the plankton drift sampling, which started in April 1977, the highest crustacean zooplankton densities in the Skagit River were found in late May, concurrent with the highest occurrence of zooplankton in chinook fry stomach samples in 1977. But moderate plankton densities were found in the plankton samples taken in April and June. Tables 8.29 through 8.34 present the occurrence of incompl~tely absorbed yolk in chinook fry captured for stomach analysis. In 1976 and 1977, yolk absorption did not necessarily precede emergence from the gravel in the Skagit and Sauk (Tables 8.29, 8.31, 8.32, 8.34). Many fry with incompletely absorbed yolk were found with food items in their guts. Although fry hiding in the surface gravel could be pulled out with the electrofisher, it seems unlikely that incubating alevins could be drawn from deep within redds or that incubating alevins would have been feeding. This precocious emergence and feeding was not found in the smaller sample Table 8.22 Chinook fry stomach contents, Skagit River, 1975 brood. Date Feb '76 March '76 A11rU 'Z2 Ma)" 'Zfi June 1 16 IulJI 'Z6 Location and County Line 9 County LinelO County Line 5 County Line 6 County Line 5 County Line 5 sample size Talc Mine 12 Talc Mine 5 Talc Mine 5 Talc Mine 5 Talc Mine 5 Talc 'Mine 3 Marblemount 10 MarblPmount 5 Marblemount 5 Marblemount 5 i. Empty 48 26 6 1 0 0 Freq.Total % Freq.Total % Freq. Total % Freq. Total % Freq,Total % Freq,Total % occur. no. occur occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. Co ZZerrJJo Za Epnemeroptera nymphs 25.0 5 7.14 36.4 12 7.64 57.1 18 8.41 60.0 30 11.63 53.3 36 24.00 62.5 16 11.68 adults Plecoptera nvmphs 9.1 1 .64 21.4 4 1.87 46.7 18 6.98 33.3 7 4.67 50.0 5 3.65 adults 7.1 1 .47 6.7 1 .67 Trichoptera larvae 12.5 2 2.86 9.1 1 .64 14.3 3 1. 40 33.3 7 2. 71 20.0 3 2.00 b.O 2 1.46 (..J adults 6.7 1 .39 6.7 1 .67 0\ JHptera 00 Chironomldae pupae 14.3 6 2.80 13.3 2 .78 larvae 12.5 2 2.86 54.5 38 24.20 92.9 81 37.85 66.7 48 18.60 26.7 59 39.33 62.5 85 62.04 adults 9.1 1 .64 35.7 9 4.21 66.7 133 51.55 33.3 18 12.00 50.0 11 8.03 Simuliidae larvae misc. Diptera 25.0 8 11.43 14.3 2 .93 26.7 7 2. 71 26.7 4 2.67 12.5 1 .73 Daphnia 12.5 10 14.29 45.5 82 52.23 35.7 71 33.18 13.3 3 1.16 6.7 6 4.00 25.0 3 2.19 Bosrrrirza 12.5 17 24.29 IHaptomus adu! ts 25.0 21 30.00 45.5 22 nauplii 14.01 28.6 18 8.41 6.7 1 .39 Misc. Aquatics 7.1 1 .47 20.0 11 7.33 12.5 3 2.19 Nisc. terrestrials 18.7 3 4.29 40.0 8 3.10 26.7 4 2.67 50.0 10 7.30 Fish eggs Unidentified 3~d inanimate material 12.5. 2 2.86 12.5 1 .73 J J Table 8.23 Chinook fry stomach contents, Cascade River, 1975 brood. r'c:?lc:nholl1 D<~te Lnc.1tion nnd sample size % Empty EplH.!meroptera nymphs adults P1Pcopteri1 Trichoptera Dlpl<'ra nym!'hs ndults lnrv.:1c adults ChI rnrHlTni d:~t.~ pup<le I arvae ndults Slrrnlllld;le ]arvne misc. lliptera Dat 11l!lta nJ[jfTiina adults nnupl i1 ~llsc. Aquatics Misc. terrestrials Fish eggs Unldcntlfled nnd Inanimate mnterial reb '76 ------~---- Cascade 1 --___ _Q ___ -- FrPq.Tota1 % occur. no. occur 100 1 100 Horch '76 ----------------- Cascnde 5 _____ _Q___ ___ ·_ Frcq.Tota1 % occur. no. occur. 80.0 7 29.17 fiO.O 9 37.5 20.0 2 8.33 20.0 1 4.17 ?0.0 2 0,33 110.0 3 12.50 __ t'I'!'lL ~~ __ _k1~_y --~-712_ __ Cascade 5 Cascade 5 -_____ Q ___ ~-___ __Q_ ____ l'req.Tota1 % Freq.Total % occur. no. occur. occur. no. occur~ ------------ 20.0 1 2.56 20.0 1 2.17 40.0 5 12.82 80.0 20 43,lf8 40.0 3 7,6g 20.0 1 2.17 40.0 3 7.69 20.0 3 6,52 20.0 1 2.56 110,0 I~ 10.26 r.o.o G 13.04 60.0 15 38 .l~fi 80.0 8 17.3q 20.0 1 2.56 20.0 1 2.17 40.0 12.82 60.0 10.87 20.0 1 2.17 20.0 1 2.56 ----------·--------------------------------- June '75 Cascade 8 ______ Q ____ Freq.Total % occur. n2.5 25.0 50.0 50.0 12.5 12.5 12.5 no. 9 7 35 1 1 1 occur. 15.25 8,47 11.86 59.32 1.69 1.69 1.69 Dec '76 Cascade 1 0 Freq, Total % occur. no. occur. 100 6 100 w ()'\ .0 Table 8.24 Chinook fry stomach contents, Sauk River, 1975 brood. ll11 te Location ill1d sample size % Empty Co llc·1ho la Ephem .. roptera nymphs ndults Plecoplera nymphs adults Trichoptera larvae adults Diptera ChI ron om l d;Je pupae larvae aJults Slmnlll<l<H' } .ill Vcll' mise. Diptera Dapl111ia nl):Jf-7{1-lcl Dia{'to'rlUS adults nauplii Hi'<c. 111uatics Mise. terr<•strials Fish e~gs Unidentified and Inanimate material -------- ___ 1-!,o!'ch ' 76_~ _.T)I[IJ'!_'_7_f) ___ _ ~auk 1 Sauk 5 0 0 Fteq.Total % Frcq.Tntal % occur. no. occur occur. 110. occur. 100.0 2 3.70 80.0 25 75.76 100,0 1 l. 85 40.0 3 9.0'l 20.0 1 3.03 100.0 50 92.59 20.0 3 9.09 20.0 1 3.03 100.0 1 l. 85 w -...! 0 J 1 Date Locnti.on and sample size % Empty ) l J ... ) Table 8.25 Chinook fry stomach contents, Skagit River, 1976 brood. Jan 19 77 ~~r~t~i~!ne Ma rb lemoun t 0 Freq.Total 5 5 3 % __ Feb 197_7 __ f~]'gt~i~!ne Marblemount 0 Freq.Total 5 5 5 % Mar 1977 County Line Talc Mine Marblemount 2 Freq. Total 5 5 5 % Apr 1977 f~]'gt~i~!ne Marblemount ____g_----,--...,.,- Freq. Total % 5 4 5 .tliJYDs t wk) 19 77 County Line 4 Marblemount 5 Freq.Total % May(4th wkll977 . 12 ¥~J'~tki~!ne 11 Marblemount 11 Freq.Total % .Jun 1977 County Lilte 10 Talc Hine 7 Marblemount 10 Freq.Total % ----------occur. no. occur occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur . i'o llembo la Ephemeroptera Plecoptera Trichoptera Diptera nvmphs adults nymphs adults larvae adults Chlronomldae pupne lnrvae adults S I mu Ill d;w larvae misc. Diptera Daphllia Bosmilla Diaptomus adults naupUi ~lise. Aquatics Hisc. terrestrials Fish eggs Unidentified and inanimate material 23.1 84.6 76.9 15.4 92.3 7. 7 69.2 7. 7 7. 7 7.7 23.1 30.8 9 1. 38 243 37.38 48 7.38 2 .31 2 36 36.31 1 .15 58 8.92 1 .15 37 5. 69 1 .15 6 • 92 8 1. 23 13.3 86.7 60.0 6.7 81). 7 6.7 53.3 13.3 6.7 6.7 6.7 6.7 6. 7 4 .44 567 62.38 17 1.87 1 .11 206 22.1\6 12 1. 32 90 9.90 7 1 1 1 1 1 .77 .11 .11 .11 .11 .11 75.0 8.3 8.3 33.3 8.3 8.3 8.3 16.7 18 1 1 4 5 1 1 2 28.6 54.55 71.4 3.03 28.6 3.03 12.12 15.15 3.03 35.7 35.7 7.1 50.0 14.3 3.03 28.6 21.4 6.06 71.4 14.3 12 6.25 51 26.56 9 4. 69 5· 2 .Go 54 28.13 3 1. 56 18 9.38 2 1.04 5 2.60 5 2.60 24 12.50 4 2.08 66.7 44.4 22.2 44.4 22.2 22.2 22.2 6 9.38 12 18.75 2 3.13 32 50.0 4 6.26 3 4.69 5 7.81 17.6 55.9 23.5 41.2 8.8 5.9 29.4 55.9 8.8 50.0 2.9 17.6 17.6 50.0 32.4 8 2.01 30 7. 52 59 14.79 30 7. 52 3 • 75 2 .50 14 3. 51 73 18.3 3 • 75 51 12.78 13 3.26 40 10.03 11 2. 76 39 9. 77 23 5.76 3.7 63.0 3.7 22.2 11.1 7.4 22.2 59.3 7.4 59.3 22.2 48.1 22.2 1 . 40 36 14.46 2 .8 7 2.81 5 2.01 4 1. 61 ll 4.42 90 36.14 2 .80 34 13.65 7 2.81 41 16.47 9 3.61 Table 8.26 Chinook fry stomach contents, Cascade River, 1976 brood. ---------------------------·------- nate feb '77 t1arch '77 April '77 Hay '77 June '77 --------~ Loc;1l ion and Cascade 6 --Cascade--s--Cascade 5 Cascade 8 Cascade 3 s:unp I c s~ze % Empty 16 20 20 0 0 --------- Frcq.Total % Frcq. Tot<tl % Freq. To t<1l % Freq.Total % Freq.Total 7. --------------E.!:Stlr. no~~~ occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. , ·:J lle•·il><J la 50.0 3 2.75 25.0 13 8.18 Ephemt'roptera nymrhs 40.0 7 24.14 50 2 40.0 25.0 3 2.75 87.5 73 45.91 33,1 1 7.69 ndults Plccuptcra n:vmphs 50.0 6 20.69 50 2 40.0 75.0 8 7.34 62.5 7 4.40 33.3 1 7.69 <1dults 12.5 1 .53 larvae 1 2 l. 83 37.5 w Trichoptera 20.0 1 3.45 25 20.0 25.0 4 2.52 ....... adu Its N Dlpt<' 1:-n Chlronomldae pupae 25.0 3 2.75 12.5 1 .53 larv;le 110.0 8 27.59 50.0 5') 54.13 A7.5 20 12.58 33.3 4 30.77 adults 75.0 6 5.50 37.5 16 10.06 100 4 30.77 Slmullldae l~"lrvae mise. Diptera 20.0 6 20.6g 100.0 18 Hi. 51 17.5 l'l 6.3r) Dt'J.1mia ~L~m·tfna Dl:1p{(:"I'L£[; <1dul ts nauplii Ml sc. Aquatics 50.0 2 l. 83 25.0 8 5.03 Hlsc. t<'IT<•strlals 20,0 1 3.45 75.0 5 4.59 12.5 1 ,53 33,3 3 23.08 Fish eggs llnid.,nt!fled and inanim;-ttf' material 37.5 5 3.1'1 ---~-------------- l ) ) ) ) Table 8.27 Chinook fry stomach contents, Sauk River, 1976 brood. ~----------------------- D<tle L~JL.,\ t i L)ll and ::iillilp ll· s i zc j)_e_,c _ _'__]_fj__ __ - S<.1uk 5 Sauk reb '77 Sauk---:5:---- March ''17 -s;_--;.~-- April '77 --sa-• .-J<--s--- 20 0 50 0 0 % Emrty c ·,_,lle.·~lbLJlt1 Eplu~meroptera Plecvptera Trichoptera Dlplcr~ nymphs <1J1dts n \rr1phs .1dults 1:1 rvill' adul [5 Chfro1tomtdne PUila~ 1 ~' r v,1e adults Slmtlllldae l,1rvac flli~c. Diptera fJdJl;Pt i a !ll):_"!r."lina Diaptomtts adults naup l ii Hi sc. A<jUilt ics ~lise. terr~strJals Fish eggs Unldentif1ed and lnn1timnte material ---- Frcq.Total Freq.Tutal % occtlr. no. occur. occur. 110. occur 75.0 15.00 100 317 114. g 25.0 2. 50 100 142 20.11 75.0 10 25.00 100 245 34.7 25.0 22 55.00 20.0 2 .28 25.0 2.50 % Fn"l· Total 20 .03 80.0 8 7.02 60 4 3. 51 50 100 87.72 20 10 83.33 40.0 2 1. 75 20 1 .03 Frcq.Tot"l % 20.0 110.0 60.0 60.0 80.0 5.55 4 22.22 3 16.67 3 16.67 7 38.89 Hay Ost wk.)' 77 ---satik____,-- 0 Frcq.Total % 40.0 20.0 20.0 20.0 60.0 60.0 40.0 60.0 4 8.00 2 2 4.00 4.00 1 2.00 19 38.00 7 14.0 6 12.00 9 18.00 Mily (lith wk.)' 77 June '77 ---saul<~ --s-au;.-.....,---- 0 0 Frcq. Total % Freq.Total 7. 25.0 50.0 25.0 25.0 25.0 75.0 25.0 25.0 75.0 25.0 12 29.27 20.0 3 7.32 80.0 1 2.44 60.0 1 2,114 40.0 1 2.44 12 29.27 100.0 60.0 '2 4.88 1 2.114 60.0 6 14.63 110.0 2 4.88 20.0 1 17 2 li& 22 20 6 1 ,93 14.17 4.17 1.67 39.33 19,33 16.67 5.0 .83 -------------------- w ....... w Table 8.28 Chinook fry stomach contents, summary of 1975 and 1976 broods. Date & location Skae>,it 1976 Skagit 1977 r.ascade 1976 r.ascade 1977 Sauk 1976 Sauk 1977 Sample size --roo ______ 127 25 8 ------:r'l ____ % Empty 21 2 0 11 0 10 --------------~-- Freq. Total % Freq.Total % Freq. Total % Freq. Total % Freq. Total % Freq. Total % Organism occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. CoUembol.a 1Z.9 34 1. 36 8.0 2 1.16 16.7 16 5.08 14.1 18 l.G'l I nymphs 48.1 117 11.87 68.5 951 38.1 60.0 41 23.7 54.2 86 27.3 87.5 44 34.65 62.'J 358 32.52 Ephemeroptera -d 1 7.3 61 2.44 2.9 2 .18 a u ts Plecoptera I nymphs 25.3 35 3.55 38.7 124 4.97 40.0 23 13.29 58.3 24 7.62 b2.5 22 17.32 37.1 15.1 13.')0 adults 2.5 2 .20 4.8 6 0.24 12.0 5 2.89 4.2 1 0. 32 2. 9 1 . ()'' Trichoptera I larvae 19.0 18 1.83 4.8 8 0.32 8.0 4 2.31 25.0 8 2.54 12.0 1 .79 8.5 3 .27 adults 2.5 2 .20 3.2 6 0.24 Diptera w "-J lpupGe 5.1 8 .81 4.0 1 0.58 8.3 4 l. 27 ..r:- Chironomidae larvae 50.6 313 31./4 40.3 476 19.07 40.0 19 10.98 50.0 91 28.89 25.0 ~? 40,'l4 2.'l 1 .0~ adults 31.6 172 17.44 37.1 262 10.5 52.0 61 35.26 37.5 26 8.25 25.0 4 3.15 71.4 1.:35 31.51 Sjmulild~" L1 rvae 19.4 161 6. 45 8.0 2 1.16 12.5 1 . 73 5.7 4 • 35 misc. Diptera 19.0 22 2.23 34.7 108 4.33 24.0 11 6.36 33.3 34 10. 79 28.6 3'' J. ()() Daphnia 21.5 175 17.75 5.6 23 0.92 Bosmina 2. 5 17 1.72 4.8 40 1.60 'adults 19.0 63 6.39 5.6 44 1. 76 Diaptomus. nauplii 1.6 2 0.08 ~lise. aquatics 6.3 15 1. 52 16.9 33 1. 32 4.0 1 0.58 16.7 10 3.17 His c. terrestrials 21.5 25 2.54 39.5 120 4.81 8.0 2 1.16 25.0 10 3.17 25.0 2 1.57 3U,3 34 3.0'1 Fish eggs 4.0 1 0.58 Unidentified and inanimate material 3.8 3 .30 16.1 37 1. 48 12.5 5 1. 59 8.3 1 0.6 8.6 4 .31) J J 376 Table 8.32 Yolk in emerged chinook fry, upper three Skagit sites, 1976 brood. Jan 77 Feb 77 Har 77 Apr 77 Number of stomachs examined 13 15 15 14 Fry with empty gut and yolk 0 0% 0 0% 0 0% 0 0% Fry with non-empty gut and yolk 5 38% 2 13% 0 0% ~ 0% 0 Fry with empty gut and no yolk 0 0% 0 0% 3 20% 0 0% Fry with non-empty gut and no yolk 8 62% 13 87% 12 80% 14 100% """ Table 8.33 Yolk in emerged chinook fry, Cascade River, 1976 brood. Jan 77 Feb 77 Mar 77 Apr 77 Number of stomachs examined 0 6 5 5 Fry with empty gut and yolk 0 0 0% 0 0% 0 0% Fry with non-empty gut and yolk 0 0 0% 0 0% 0 0% Fry with empty gut and no yolk 0 1 17% 1 20% 1 20% Fry with non-empty gut and no yolk 0 s 83% 4 80% 4 80% Table 8.34 Yolk in emerged chinook fry, Sauk River, 1976 brood. Dec 76 Jan 77 Feb 77 Mar 77 Apr 77 Number of stomachs examined 5 5 5 5 5 ....,, Fry with empty gut and yolk 1 20% 0 0% 0 0% 0 0% 0 0% Fry with non-empty gut and yolk 2 40% 0 0% 2 40% 0 0% 0 0% Fry with empty gut and no yolk 0 0% 0 0% 1 20% 0 0% 0 0% Fry with non-empty gut and no yolk 2 40% 5 100% 2 40% 5 100% 5 100% - - ·- - 377 of 31 fry from the Cascade (Tables 8.30 and 8.33). This could imply that warmer temperatures in the Sauk and the Skagit resulted in precocious emergence. 8.1.4.4 Pink. Salmon Fry Availability. Pink salmon fry were available for sampling only in even years. They followed chinook fry in emergence timing in the Skagit Basin. In the 1974 sampling by WDF, pink fry of the 1973 'brood first appeared in electrofishing samples on }1arch 4 and were last captured on April 26. Only 22 were captured, while over 1,800 chinook fry were captured (Orrell 1976). Some sampling of pink fry was also done by FRI in 1974 between February 21 and May 21 (Tables 8.35 and 8.36). In the 1976 sampling by FRI, two fry of the 1975 brood were captured in the mainstem Skagit in the first half of January, and scattered numbers were taken into early Hay (Table 8.37). Highest numbers were taken in April. Pink fry were captured in the Sauk only in April and in Bacon and Diobsud creeks only in March (one fry each creek). No pink fry were taken in the Cascade River or Goodell Creek during the weekly sampling in 1976. Numbers captured overall were low, in part, because of the tendency of the fry to migrate at once following emergence and not to seek. the shoreline waters. Incubation survival was probably reduced by floods in January 1974, and December 1975, especially in unregulated waters. In 1978 pink salmon fry were available from mid-February to mid-May at Skagit River electrofishing stations (Table 8.38). One fry was captured in the Cascade River in late March and none were captured in the Sauk River during monthly sampling. Peak densities found from standard- ized electrofishing effort were reached at the County Line Station on March 31 (Fig. 8.43 and Table 8.39). Farther downstream at the Rockport Station, peak densities were reached on Hay 5. Densities were low and without distinct peaks at the Marblemount Station. However, fry of the 1977 brood were generally more available at the Skagit stations than were fry of the previous two broods (Tables 8.35 and R.37), possibly because of the lack. of flooding during the incubation and early rearing period of the 1977 brood. In addition, the estimated escapement was larger in 1977 than in the two previous cycles (Table 5.3). Numbers of pink fry captured over-all and peak densities were generally lower than for chinook fry, in part because of the tendency of the fry to emigrate nocturnally at once following emergence and to hide in the gravel by day (McPhail and Lindsey 1970). 8.1.4.5 Pink Salmon Fry Size and Condition after Emergence. Size and condition data for Skagit Basin pink fry captured during 1974 are presented in Tables 8.35 and 8.36. In general, pink fry are smaller than chinook fry. Most sites showed little change in mean length, mean weight, or mean condition factor with time. Downstream migration was probably continual. Too few fry were captured in the Cascade and Sauk rivers in 1974 to make meaningful comparisons with the Skagit. Size and condition data for Skagit and Sauk river pink fry captured during 1976 are presented in Table 8.40. The length and weight data 378 """'' - Table 8.35 Mean lengths, weights, and condition factors of pink salmon fry captured by electroshocking in the Skagit River, 1973 brood. - Mean Number Length (mm) condition -Mean Location Date of fish Range Mean weight (g) factor 1974 Skagit River Feb 21 1 27 27 near Newhalem Mar 11 4 33-36 34.5 0.25 0.61 ~' / Apr 8 4 34-38 36.0 0.46 1.00 10 1 35 35 0.35 0.82 17 2 34-37 35.5 0.30 0.68 ~ 24 4 35-38 36.7 0.30 0.61 May 6 1 34 34 0.3 0.8 Skagit River Feb 26 3 34-35 34.3 0.20 0.50 near Talc Mine ~ Mar 12 6 31-35 33.2 0.25 0.69 26 21 33-36 34.4 0.28 0.69 Apr 9 20 32-37 34.5 0.27 0.65 17 4 33-36 34.8 0.23 . 0.53 23 13 33-39 36.5 0.26 0.54 -May 7 3 34-36 35.3 0.30 0.68 Skagit River Feb 22 1 33 33 0.25 0.70 """" near Marblemount 25 1 31 31 ):-· Mar 12 1 35 35 0.25 0.58 ~' ~I ~I 3]9 Table 8.36 Mean lengths, weig~ts, and condition factors of pink salmon fry captured by either electroshocking or fyke netting in Skagit tributaries, 1973 brood. Mean Number Length (mm) Mean co11dition ~· Location Date of fish Range Mean weight (g) factor 1974 Cascade River Feb 27 2 31 31.0 0.15 0.50 ·"""' Sauk River Mar 26 1 37 37 0.4 0.8 Bacon Creek Apr 9* 45 33-39 35.9 0.29 0.64 10* 34 32-37 35.5 0.31 0.69 10 1 35 35 0.3 0.7 24* 6 33-38 35.9 0.29 0.63 Diobsud Creek Apr 9* 14 30-37 34.4 0.30 0.73 10* 9 31-37 34.7 0.31 0.74 24* 19 31-37 34.1 0.24 0.60 May 7* 21 34-39 36.2 0.29 0.60 8 2 34-35 34.5 0.20 0.49 21* 6 33-38 34.2 0.23 0.58 1<fyke net sample Table 8,37 Pink fry catches at Skagit Basin sampling sites using electrofishez, 1975 brood. Skagit River at County Talc Marble-Rock-Cascade Sauk Goodell Bacon Diobsud Date Line Mine mount port River River Creek Creek Creek 1975 12/19-1/3 1976 1/~1/10 , 1 1/11 -1/17 1 1/18 -1/24 1/25 -1/31 5 2/1 -2/7 1 2 2/8 -2/14 2 2/15 -2/21 2 2/22 -2/28 w 2/29 -3/6 1 1 CXI 0 3/7 -3/13 2 3 3/14 ·-3/20 1 2 3/21 -3/27 1 3 1 3/28 -4/3 4/4 -4/10 2 4/11 -4/17 16 1 7 4/18 -4/24 3 8 6 4/25 -5/1 6 2 2 1 5/2 -5/8 1 2 5/9 -5/15 5/16 -5/22 Note: dash (-) signifies catch was zero. blank signifies sampling not conducted. - """' ~' - - 381 Table 8.38 Pink salmon catches at Skagit Basin sampling sites using electrofisher, 1977 brood. Skagit River at County Talc Marble-Rock- Date Line Mine mount port Concrete Cascade 1978 1/18-1/22 2/1 2/10 1 3 2/17 4 35 2/24-2/26 4 5 3/3 15 4 4 3/10 6 1 1 3/17 45 2 3 3/24-3/27 11 19 1 3/31 88 2 4/7 26 8 4/13 29 2 4/21 21 28 16 4/24-4/25 22 3 106 5/2 12 3 120 5/9-5/10 10 6 83 5/16-5/17 4 6 5/23 3 6/1 Note: dash (-) signifies catch was zero blank signifies sampling not conducted Sauk 382 40 .. CMTY LINE • 35 I-l!J 11ARBLEtlOUNT LL X ROCKPORT ....--4 20 0::: w a.... 15 >- 0::: LL 10 :s::: z ~ a.... 0 JAN MAR JUN DATE Fig. 8.43 Pink salmon availability at Skagit River sampling sites from standardized electrofishing effort. 1978. - - ~j - ~ ~ -~ - - Table 8,39 No. Date fish 1978 2/ 1 0 2/10 1 2/17 4 2/24 4 3/ 3 14 3/10 6 3/17 45 3/31 88 4/ 7 26 4/13 29 4/24 22 4/25 5/ 2 12 5/ 9 5/10 5 5/16 5/17 .3 5/23 0 Summary of pink fry catch and density data from standardized electrofishing efforts at three Skagit River sampling sites, 1977 brood. County Line Marblemount Area No. per No. Area No. per No. sampled 1000 fish sampled 1000 fish (ft2) ft2 (ft2) ft 2 2250 0.0 0 1000 0.0 0 2250 0.4 0 1000 0.0 3 2250 1.8 0 1000 0.0 35 2250 1.8 0 1000 0.0 4 2250 6.2 4 1000 4.0 4 2250 2.7 1 1000 1.0 1 2250 20.0 2 1000 2.0 3 2250 39.1 2 1000 2.0 2250 11.6 0 1000 0.0 7 2250 12.9 0 1000 0.0 2 2250 9.8 3 1000 3.0 99 2000 6.0 3 1000 3.0 120 1 1000 1.0 83 2000 2.5 0 1000 0.0 6 2000 1.5 2000 0.0 0 1000 0.0 0 RockEort Area No. per sampled 1000 (ft2) tt2 4000 0.0 4000 0.8 4000 8.8 4000 1.0 4000 1.0 4000 0.3 4000 0.8 High water 4000 1.8 w 00 4000 0.5 w 4000 24.8 4000 30.0 4000 20.8 4000 1.5 4000 0.0 384 Table 8.40 Mean lengths, weights, and condition factors of Skagit and Sauk rivers pink salmon fry captured by electroshocking, 1975 brood. Month SKAGIT RIVER '1976 January February March April May SAUK RIVER 1976 April ------------------------------------------------ Number of fish 7 7 12 45 3 9 Mean length (rnm) 30.3 31.4 33.6 36.5 35.7 36.3 Mean weight (g) 0.24 0.22 0.24 0.27 0.30 0.26 Mean c~ndition factor 0.86 0.71 0.63 0.56 0.66 0.5.4 -- ~ ~ _, - - e'!Wf·; 385 showed a general increase from January through May, while the condition factors decreased slightly. Fry captured fro~ both systems during the peak month, April, were similar in size and condition factor. Hore pink salmon fry were available for size and condition factor analysis from the 1977 brood than from the 1975 brood. Fry were collected from February or March through May at three Skagit River stations and on two dates at the Concrete Station. At all sites, mean lengths generally increased while mean condition factors generally decreased through the season (Tables 8.41-8.44). Trends in mean weight over the season were not significant except at the Rockport Station where there was a slight, but significant (a= 0.05) increase in mean weight (Table 8.43). No signifi- cant differences in size and condition of pink salmon fry were found between stations. However, sample sizes were small. 8.1.4.6 Pink Salmon Fry Diet. Fifty-six pink salmon fry from the SKagit River and one from the Cascade Rjver were collPcte~ rluring 1978 for diet analysis. For fry captured in February, March, and April, at the Skagit sites, 100 percent, 95 percent, and 45 percent, respectively, had empty stomachs (Table 8.45). The single pink fry from the Cascade River also had an empty stomach. Twenty-five out of 26 fry collected in February and March contained yolk, while in April, 17 out of 31 (55 percent) contained yolk (Table 8.45). Out of 26 fry collected in February and March only one fry from the Concrete Station in Harch had food in its stomach, a single Diaptomus nauplius (Table 8.46). Seventeen fry collected in April hao food items in their stomachs (Table 8.46). Non-nutritive items such as Ephemeroptera exuvia (shed insect skins), pebbles, and other inanimate material account- ed for about 48 percent of the contents by number. Of the remaining food items, chironomid and simulid larvae were important by numbers. Zooplank- ton species were found in some stomachs, mainly in those from the C011nty Line Station. 8.1. 4. 7 Churn Salmon Fry Availability. Because chum salmon spawning is late in the fall, emergen~e is later in timing than for summer-fall chinook and pink fry in spite of fewer temperature units required by chum salmon for embryonic development. Chum fry spend little time in freshwater and migrate downstream soon after emerging from the ~ravel, mainly at night. They feed a little if the migration is long (McPhail and Lindsey 1970). These habits made few fry available to our electroshocking effort. In 1973, WDF sampling first encountered chum fry of the 1972 brood in the Parblemount-P.ockport area of the Skagit on Harch 22. Peak numbers were captured in April, but fish were still present on t!ay 21, the last sampling date (Phinney 1974a). In 1974, WDF sampling encountered chum fry of the 1973 brood only in April and nay (Orrell 1976). FRI sampling in 1974 found chum fry from April 9 to Hay 20 in the Skagit, from February 2 to February 27 in the Cascade, from April 23 to May 21 in the Sauk, and on Table 8.41 Mean lengths, weights, and condition factors of pink salmon fry captured by electroshocking at the County Line Station in 1978. 1977 brood Mean Mean Mean Number length weight condition Date of fry (mm) (g) factor February 10 1 32.0 0.240 0.732 17 3 33.7 0.250 0.653 24 4 32.0 0.190 0.580 March 3 15 32.9 0.230 0.646 10 3 34.0 0.240 0.611 17 10 34.5 0.238 0.579 24 1 33.0 0.220 0.612 31 27 34.9 0.223 0.526 l..oJ CXl April 7 10 35.4 0.254 0.572 0'1 21 10 36.4 0.258 0.535 May 10 10 36.7 0.244 0. 492 17 4 36.7 0.240 0.484 23 3 35.7 0.223 0.490 J Table 8.42 Date March 3 10 17 31 April 21 25 May 2 9 Mean lengths, weights, and condition factors of pink salmon fry captured by electroshocking at the Marblemount Station in 1978. 1977 brood Mean He an Mean Number length weight condition of fry (mm2 ~g2 factor 4 33.5 0.230 0.612 1 34.0 0.270 0.687 1 34.0 0. 230 0.585 2 35.5 0.250 0.553 18 37.0 0.268 0.527 3 38.0 0.280 0.510 3 36.7 0.263 0.533 6 37.2 0.260 0.505 w OJ '-I Table 8.43 Date February 10 17 March 3 10 17 April 7 13 25 May 2 9 16 I .. _j -J Mean lengths, weights, and condition factors of pink salmon fry captured by electroshocking at the Rockport Station in 1978. 1977 brood Mean Mean Mean Number length weight condition of fry (mm) (g) factor 3 29.7 0.210 0.802 24 32.0 0. 208 0.635 4 32.5 0.160 0.466 1 33.0 0.230 0.640 3 35.3 0.263 0.595 8 35 0 3 0.245 0.557 2 35 .o 0.240 0.560 10 36.6 • 0.249 0.507 10 36.5 0.241 0.497 11 36.8 0.255 0.509 5 36.8 0.244 0.488 ... r _j w 00 00 Table 8. 44 Mean lengths, weights, and condition factors of pink salmon fry captured by electroshocking at the Concrete Station in 1978. 1977 brood Mean Mean Mean Number length weight condition Date of fry (mm) (g) factor March 24 9 33.8 0.230 0.596 April 21 6 36.3 0.247 0.511 Table 8.45 Yolk in emerged pink salmon fry, 1977 brood. Skagit Skagit Cascade Skagit Feb 78 Mar 78 Mar 78 Apr 78 Number of stomachs examined 5 20 1 31 Fry with empty stomach and yolk 5 100% 19 95% 1 100% 10 32% Fry with non-empty stomach and yolk 0 0% 0 0% 0 0% 7 23% Fry with empty stomach and no yolk 0 0% 0 0% 0 0% 4 13~~ Fry with non-empty stomach and no yolk 0 0% 1 5% 0 0% 10 32% Table 8. 46 Pink salmon fry stomach contents, Skagit River and Cascad2 River, 1977 brood. Date Location and sample size: % empty: Ephemeroptera nymphs adults exuvia Diptera Chironomidae larvae pupae adults Simuliidae larvae Daphnia Bosmina Diaptomus nauplii adults Nematoda Unidentified insects Pebbles, plant material Feb Rockport Freq. occur. and unidentified material 24, 1978 Mar 24, 1978 5 County Line 10 Concrete 10 100 95 Total % Freq. Total % no. occur. occur. no. occur. 100.0 1 100.0 Mar 27, 1978 AJ2r 21, 19 78 Cascade 1 County Line 11 Marblemount 10 Concrete 10 100 45 Freq. Total % Freq. Total % occur. no. occur. occur. no. occur. 5.9 1 1. 79 5.9 1 1. 79 41.2 17 30.36 35.3 8 14.29 17.6 4 7.14 5.9 2 3.57 ~ 0 17.6 5 8.93 5.9 2 3.57 11.8 2 3. 57 11.8 2 3.57 5.9 1 1. 79 5.9 1 1. 79 76.5 10 17.86 •• ,._ - 391 April 17 in Diobsud Creek (Table 8.47). In the 1976 sampling by FRI, chum fry of the 1975 brood were taken from early March to early June in the Skagit and late March to early June in the Sauk (Table 8.48). One chum fry was caught in the Cascade River in early April 1~76. The flood of December 1975 probably caused the abundance of the 1975 brood to be Jow. Chum fry were more available to electrofishing in the upper Skagit River in 1977 (Table 8.49), and were taken from early tlarch until mid-June, with peak densities in April-Hay (Fig. 8.44 and Table 8.50). Chum fry were captured in the Sauk River in small numl,ers from late M.arch until early June. Only three chum fry were captured in the Cascade River in 1977. No chum fry were taken in the weekly sampling in Goodell, Bacon, and Diobsud creeks. In 1978, chum fry were first available at three Skagit stations in small numbers in rnid-February, but were caught in largest numbers in April and May (Table 8.51). Catches were limited to Skagit River stations except for one fry from the Sauk River, probably because most chum spawning was generally in the rna_instern Skagit and its back channels (Sec. 6). Peak fry densities found by standardized electrofishing effort were lower in 1978 than in the previous year (Fig. 8.44 and Table 8.52) reflecting the difference in parental escapement between the two years (Table 5.3). Fry catches at the Skagit River stations dropped to zero in late May or early June. 8.1.4.8 Chum Salmon Fry Size and Condition after Emergence. Table 8.47 presents the mean length, weight, and condition factor data for chum fry of the 1973 brood caught in 1974. The samples were too sroall to detect time and area differences. Mean lengths, weights, and condition factors of the 1976 samples (Table 8.53) showed a tendency to increase over the months of Harch through Hay. Fry from the Sauk River samples averaged slightly longer and heavier than those from Skagit P.iver samples from Harch through Uay~ Chum fry sampled from the 1976 brood showed a slight increase in mean length and weight during the period that they were available (Tables 8.54 -8.58; Figs. 8.45 and 8.46). Mean condition factors, however, were more variable and trends with time were not evident (Fig. 8.47). Figures 8.45 -8.47 include samples of more than one fry. 8.1.4.9 Chum Salmon Fry Diet. Few fish from the 1975 brood were available for stomach analysis and these were all caught from April through June, 1976 (Table 8.59). Eight of the Skagit River chum fry for stomach sample analysis were captured downstream at the Concrete Station. Chironomids were the most important element in the freshwater diet. A few Ephemeroptera nymphs, Plecoptera nymphs, and Trichoptera larvae were also found. No zooplankton were found in these stomachs. Seventy chum fry from the 1976 brood were caught for stomach analyses from April through June, 1977 (Table 8.60). Hore than one-third had empty stomachs. Most of the samples were caught at Skagit River stations. Ephemeroptera nymphs, chironomids, and mites were found to be the most numerous prey organisms in these fry. Zooplankton were also found. 392 ~ Table 8.47 Mean lengths, weights, and condition factors of chum ~ salmon fry captured by electroshocking, 1973 brood. ~ Mean Number Length (mm) Mean condition Location Date of fry Range Mean weight (g) factor -1974 Skagit River Apr 9 2 40-41 40.5 0.48 0. 72 near Talc Mine Apr 17 3 37-38 37.3 0.40 0. 77 """ Skagit River Apr 23 1 40 40 0.5 0.8 near Marblemount May 7 4 37-41 39.0 0.40 0.68 May 20 3 44-45 44.3 0.62 o. 71 Cascade River Feb 2 2 37 37.0 0.40 0.79 Feb 27 1 34 34 0.2 0.5 ~ Sauk River Apr 23 2 36-37 36.5 0.40 0.82 May 7 20 37-40 38.9 0.46 0. 78 ~ Hay 21 6 37-40 38.2 0.38 0.68 Diobsud Creek Apr 17 1 40 40 0.45 0.70 - - Table 8. 48 Chum fry catches at Skagit Basin sampling sites using electrofisher, 1975 brood. Skagit River at County Talc Marble-Rock-Cascade Sauk Goodell Bacon Diobsud Date Line Mine mount port River River Creek Creek Creek 1976 2/22 -2/28 2/29 -3/6 3/7 -3/D 1 3/14 -3/20 2 5 3/21 -3/27 3 3/28 -4/3 4 2 28 1 4/4 --4/10 1 1 5 4/11 -4/17 23 3 7 4/18 -4/24 34 6 9 w 4/25 -5/1 4 9 \0 w 5/2 -5/8 3 2 5/9 -5/15 1 1 5/16 -5/22 2 1 1 5 5/23 -5/29 1 1 5/30 -6/5 2 1 6/6 -6/12 6/13 -6/19 Note: dash (-) signifies catch was zero. blank signifies sampling not conducted. Table 8.49 Chum fry catches at Skagit Basin sampling sites using electrofisher, 1976 brood. Skagit River at County Talc Marble-Rock-Cascade Sauk Goodell Bacon Diobsud Date Line Mine mount port River River Creek Creek Creek 1977 2/20 -2/26 2/27 -3/5 2 3/6 -3/12 3/13 -3/19 1 1 1 3 3/20 -3/26 3 13 1 3/27 -4/2 14 9 54 3 4/3 -4/9 61 14 30 191 w 4/10 -4/16 17 4 19 94 1 '-0 .10- 4/17 -4/23 6 65 6 219 2 6 4/24 -4/30 20 19 6 16 1 5/1 -5/7 40 12 40 1 1 5/8 -5/21 10 36 51 88 8 5/22 -6/4 1 3 1 21 1 6/5 -6/18 2 3 16 1 6/19 -7/2 Note: dash (-) signifies catch was zero. blank signifies sampling not conducted. - - - 395 75 COUNTY LINE X 1978 e:! 1977 0 • 1-- lJ... • C?J (f) 0 75 0 0 MARBLEMOUNT -a::: 50 w X 1978 a... >-25 I!l 1977 a::: LJ.... L: 0 ::::J I u 75 ROCKPORT 50 X 1978 25 ~ 1977 0 JAN Fig. 8.44 Chum salmon availability at Skagit River sampling sites from standardized electrofishing effort, 1977 and 1978. Table 8.50 Summary of chum fry catch and density data from standardized electrofishing efforts at three Skagit River sampling sites, 1976 brood. County Line Marblemount RockEort No. Area No. per No. Area No. per No. Area No. per Date fish sampled 1000 fish sampled 1000 fish sampled 1000 ( ft 2) ft 2 (ft2) ft 2 (ft2) ft 2 1977 3/ 2 0 2500 0.0 0 1000 0.0 0 3500 0.0 3/ 4 2 3500 0.6 3/ 8 0 2150 0.0 0 1000 0.0 0 3500 0.0 3/15 0 2150 0.0 0 1000 0.0 3 3500 0.9 3/22 3 2150 1.4 13 3500 3. 7 3/23 0 1000 0.0 3/29 2 1000 2.0 54 3500 15.4 3/31 14 2000 7.0 w 4/ 6 26 1000 26.0 142 3500 40.6 '0 (j'\ 4/ 7 61 2500 24.4 49 2500 19.6 4/12 4 1000 4.0 94 3500 26.9 4/13 21 2150 9. 8 . 4/20 5 2150 2.3 5 1000 5.0 4/22 229 3500 65.4 4/26 7 1000 7.0 High water 4/27 11 2250 4.9 5/ 2 12 1000 12.0 5/ 6 40 2500 16.0 40 3500 11.4 5/12 10 2500 4.0 51 1000 51.0 88 3500 25.1 5/24 1 1000 1.0 13 3500 3.7 5/26 1 2150 0.5 6/ 6 1 1000 1.0 6 3500 1.7 6/ 7 0 2250 0.0 6/21 0 2500 0.0 6/22 0 2150 0,0 0 1000 0.0 ---- , ..... - """"' F"'": - - - ~ ' 397 Table 8.51 Chum salmon catches at Skagit Basin sampling sites using electrofisher, 1977 brood. Skagit River at County Talc Marble-Rock- Date Line Mine mount port Concrete Cascade 1978 1/18-1/22 2/1 2/10 2/17 1 2/24-2/26 1 1 1 3/3 3/10 3/17 1 3/24-3/27 1 3/31 6 1 4/7 54 4/13 3 4/21 4 10 4/24-4/25 19 10 111 5/2 3 34 5/9-5/10 1 10 61 5/16-5/17 1 5 12 5/23 7 10 21 6/1 7 18 6/6 3 6/13 Note: dash (-) signifies catch was zero blank signifies sampling not conducted Sauk 1 Date 1978 2/10 2/17 2/24 3/ 3 3/10 3/17 3/31 4/ 7 4/13 4/24 4/25 5/ 2 5/ 9 5/10 5/16 5/17 5/23 6/ 1 6/ 6 6/13 Table 8.52 Summary of chum fry catch and density data from standardized electrofishing efforts at three Skagit River sampling sites, 1977 brood. County Line Marblemount RockEort No. Area No. per No. Area No. per No.· Area fish sampled 1000 fish sampled 1000 fish sampled ( f t2) ft2 (ft2) ft 2 (ft2) 0 2250 0.0 0 1000 0.0 0 4000 0 2250 0.0 1 1000 1.0 0 4000 1 2250 0.4 1 1000 1.0 1 4000 0 2250 0.0 0 1000 0.0 0 4000 0 2250 0.0 0 1000 0.0 0 4000 0 2250 0.0 0 1000 0.0 1 4000 0 2250 0.0 1 1000 1.0 High water 0 2250 0.0 0 1000 0.0 55 4000 0 2250 0.0 0 1000 0.0 ') 4000 J 19 2250 8.4 9 1000 9.0 111 4000 0 2000 0.0 3 1000 3.0 34 4000 3 1000 3.0 61 4000 1 2000 0.5 0 1000 0.0 12 4000 1 2000 0.5 0 2000 0.0 5 1000 5.0 24 4000 0 2000 0.0 3 1000 3.0 18 4000 0 2000 0.0 1 1000 1.0 High water 0 2000 0.0 0 1000 0.0 0 4000 .J 1 No. per 1000 ft2 0.0 0.0 0.3 0.0 0.0 0.3 13.8 0.8 w 1,0 00 27.8 8.5 15.3 3.0 6.0 4.5 0.0 - 399 Table 8.53 Mean lengths, weights, and condition factors of Skagit and Sauk rivers chum salmon fry captured by electroshocking, 1975 brood. Number Mean Mean Condition Month of fish length (nnn) weight (g) factor - SKAGIT RIVER '""" 1976 March 45 35.1 0.25 0.58 -April 62 38.5 0.38 0.67 May 6 39.7 0.46 0.74 June 2 38.5 0.36 0.63 SAUK RIVER 1976 March 1 38 0.28 0.51 April 30 39.3 0.41 0.68 May 9 42.4 0.56 0.73 - - -----------------~----- Month 1977 March 15 22 31 April 7 13 20 27 May 6 12 400 Table 8.54 Mean lengths, weights, and condition factors of chum salmon fry captured by electrofishing at the County Line Station, 1976 brood. Mean Number Mean Mean condition of fish length(mm) weight(g) factor 1 31.0 0.310 1.041 3 35.7 0.317 0.697 14 38.8 0.373 0.638 23 38.6 0. 371 0.644 17 39.2 0.369 0.613 6 40.0 0. 398 0.621 20 40.9 0.427 0.616 24 39.7 0.382 0.612 8 39.1 0.376 0. 630 - - """' - ~- - - Table 8.55 Number Month of fish ~~ 1977 f March 15 1 - April 4 9 13 4 22 25 26 19 May 12 24 """' June 7 2 401 Mean lengths, weights, and condition factors of chum salmon fry captured by electrofishing at the Talc Mine Station, 1976 brood. Mean Mean Mean condition length(mm) weight(g) factor 39.0 0.380 0.641 38.3 0.357 0.633 39.0 0.368 0.616 40.3 0.418 0.637 39.8 0.381 0.602 40.9 0.467 0.681 41.0 0.415 0.602 Table 8.56 Number Month of fish 1977 March 15 1 29 9 April 12 19 20 6 26 6 May 2 7 12 24 June 6 3 402 Mean lengths, weights, and condition factors of chum salmon fry captured by electrofishing at the Marblemount Station, 1976 brood. Mean Mean Mean condition length(rnrn) weight (g) factor 34.0 0.290 0. 738 36.2 0.318 0.670 39.0 0.361 0. 606 39.3 0. 360 0.592 39.8 0.442 0. 700 38.9 o. 346 0.588 40.2 0.426 0.654 39.7 0.390 0.625 ~ M"1'C~ ~ ~ - - ~·-Table 8, 57 Number Month of fish ,_ 1977 ~· March 15 3 -22 13 29 24 April 6 25 12 25 22 25 26 16 May 6 25 12 20 24 11 ~,.. June 6 16 - - 403 Mean lengths, weights, and condition factors of chum salmon fry captured by electrofishing at the Rockport Station, 1976 brood. Mean Mean Mean condition length(mm) weight (g) factor 39.0 0.350 0.590 37.8 0.338 0. 631 38.8 0.353 0.605 37.7 0.376 0.699 38.2 0.356 0.640 39.9 0.370 0.580 39.5 0. 365 0. 592 39.2 0.369 0.610 39.3 0.356 0.589 40.7 0.437 0.636 40.0 0.387 0.604 404 - ~ Table 8.58 Mean lengths, weights, and condition factors of Cascade and Sauk River chum salmon fry captured by electrofishing, 1976 brood. Mean ~ Number Mean Mean condition Month of fish length(mm) weight(g) factor CASCADE RIVER 1977 ~· April 18 2 36.5 0.345 o. 710 SAUK RIVER - 1977 March 21 1 40.0 0.380 0.594 -28 3 38.7 0.383 0.662 April 11 1 37.0 0.320 0.632 18 6 41.0 0.430 0.621 -' 25 1 38.0 0.390 0. 711 May 2 1 41.0 0.390 0.566 """" 9 8 39.3 0.363 0.600 June 6 1 45.0 0.800 0.878 - ......... ::E: ::E: ........ I I- C) z w _j z c:c w ~ 405 50 LEGEND -& COUNTY LINE ~ TALC MINE 45 -6-I~ARBLEMOUNT -+-ROCKPORT --+-CONCRETE 40 35 FEB MAR APR 1977 MAY JUN Fig. 8.45 Mean lengths of chum fry taken by electrofishing from five Skagit River stations, 1976 brood. ,...... 0 ._... I-- ~ ~ w ~ z a: w :L 406 t.oo LEGEND -E9-COUNTY LINE .75 "-*" TALC MINE -€9-MARBLEMOUNT --+-ROCKPORT -+-CONCRETE .so .zs 0 ~----~------~------~------~-------L~ FEB Fig. 8.46 MAR APR 1977 MAY JUN Mean weights of chum fry taken by electrofishing from five Skagit River stations, 1976 brood. ~ ~ ~~ ~ ~ ~- - 0:::: 0 1--u c:c LL z 0 1--4 -1-- 1--4 0 z 0 u z c:c w l:: 407 .800~----------------------------------~ .700 .sao .sao LEGEND -e-MARBLEMOWlT --e-COUNTY LINE -+ ROCKPORT *"-TALC MINE -+-CONCRETE .400 FEB MAR APR MAY JUN 1977 Fig. 8.47 Mean condition factors of chum fry taken by electrofishing from five Skagit River stations. Collembola Ephemeroptera Plecoptera Trichoptera Diptera Chironomidae Simuliidae Misc. Diptera Daphnia Bosmina Diaptomus Table 8,59 Location and sample size·: % empty: nymphs adults nymphs adults larvae adults pupae larvae adults larvae adults nauplii Misc. aquatics Misc. terrestrials Fish eggs Unident. and inanimate material Chum fry stomach contents, 1975 brood, April through June, 1976 Skagit R. Cascade R. Sauk R. Marblemount 4 Concrete 8 0 1 33 Freq. Total % Freq. Total % Freq. Total % occur. no. occur. occur. no. occur. occur. no. occur. 37.5 3 1. 28 100.0 4 14.0 12.5 2 .85 25.0 3 1. 28 ~ 0 00 25.0 3 1. 28 100.0 196 83.38 100.0 9 31.0 62.5 22 9.40 100.0 16 55.0 12.5 1 .43 12. 5· 1 .43 25.0 3 1. 28 J 1 Table 8.60 Chum fry stomach contents, 1976 brood, April through June 1977. Skagit R. Cascade R. Sauk R. Location County Line u and Talc Mine 7 sample Marblemount 11 1 6 size: Rockport 23 Cone rete 11 % empty: 37 0 33 Freq. Total % Freq. Total % Freq. Total % occur. no. occur. occur. no. oceur. occur. no. occur. Collembola 10.0 8 2.32 100 14 34.15 25.0 2 12.5 Ephemeroptera nymphs 40.0 42 12.17 100 10 24.39 adu1 ts 2.5 1 .29 Plecoptera nymphs 10.0 5 1.45 100 1 2.44 .p- 0 adults 1.0 Trichoptera larvae 100 1 2.44 adults 7.5 3 .87 Diptera Chironomidae pupae 2.5 3 .87 larvae 42.5 61 17.68 100 5 12.20 75.0 9 56.25 adults 40.0 75 21.74 100 3 7.32 25.0 1 6.25 Simuliidae larvae 10.0 6 1. 74 Mise. Diptera 27.5 24 6.96 100 6 14.63 25.0 1 6.25 Daphnia 5.u 3 .87 Bo~·rnina 5.0 3 .87 Diaptornus adults 10.0 32 9.28 nauplii 5.0 2 .58 Mites 12.8 50 14.84 100 1 2.44 Misc. terrestrials 42.5 21 6.09 75.0 3 18.75 Fish eggs Unident. and inanimate material 12.5 6 1. 74 410 In fry from the Cascade and Sauk rivers, Collembola formed a higher percentage of the diet by numbers than in the fry from the Skagit. Also, chironomids and other flies were a sizable component by numbers in these fry diet samples. Although Ephemeroptera nymphs were numerous in the chum fry sampled from the Cascade River, none were found in stomachs from the six fry from the Sauk River. 8.1.4.10 Coho Salmon Fry Availability. Because coho are late season spawners and spawn primarily in the tributaries, fry tend not to be encountered in the upper Skagit River until April. Fry first appear in the tributaries and the later buildup in the mainstem river is apparently a result of redistribution from the tributaries. In 1973, Skagit River sampling by WDF of coho fry of the 1972-1973 brood were first encountered on April 13. Coho fry broods encompass two years since the spawning starts in December of one year and carries over into the next year. In sampling in 1974 by FRI, coho fry of the 1973-1974 brood were first encountered in the mainstem Skagit near County Line and in Goodell Creek on March 25; they first appeared in catches in Diobsud and Bacon creeks by early April, and by late April at the rest of the sites (Tables 8.61 through 8.68). Early samples tend to be small partly because of initial low effort on coho fry collection. Although coho fry were still present, the sampling was not continued into the fall of 1974. In the 1975-1976 brood the coho fry in the creeks other than Diobsud Creek and in the Cascade River preceded appearance of coho fry in the mainstem Skagit and Sauk (Table 8.69). In the 1976-1977 brood, this pattern suggesting first emergence in the smaller tributaries and redistribution into the Skagit and Sauk rivers was generally repeated although sporatic early catches in the Skagit and Sauk made this trend less distinct (Table 8.70). Tables 8.69 and 8.70 show the extended freshwater rearing stage inherent to the species. Coho fry from broods which emerged in February ·through March of one year were still present at the sampling sites more than a year later. Catches of these older fry with the electrofisher are disporportionately lower than their abundance because the older coho tend to take up feeding stations somewhat beyond the range of the backpack electrofisher. Large fry were observed in January and February 1977, around the Newhalem incubation boxes in 4 to 6 ft of water in the backwater of a submerged log. The timing of downstream migration is difficult to pinpoint because of this decreasing effectiveness of the gear to older fry, but catch data (Tables 8.69 and 8.70) indicated that fry disappeared from the sampling sites during the spring of their second year. As in the preceding two seasons, catches of more than 20 year-0 fry at the Cascade River in 1978 preceded similar sized catches at the County Line Station (Table 8.71). Early catches of coho fry of the 1977-1978 brood at other stations were low and variable. Judging from the pattern of coho fry catches during the previous two seasons, sampling was probably ended before catches of year-0 fry peaked in 1978. - - 411 Table 8.61 Mean lengths, weights, and condition factors of Skagit River coho fry captured by electroshocking """' at sites near County Line, 1973-74 brood. Mean Number Length (rnrn) Mean condition Date of fry Range ~1ean weight (g) factor 1974 -Mar 25 1 35 35 0.3 0.7 Apr 8 8 35-39 36.7 0.46 0.93 -10 2 35 35.0 0.40 0.93 17 1 35 35 0.35 0.82 24 3 34-39 37.1 0·. 43 0.86 ·"""' May 6 5 35-37 35.8 0.38 0.84 8 1 37 37 0.3 0.6 21 1 38 38 0.3 0.5 !'""' 21 3 35-38 36.7 0.43 0.88 Jun 13 3 33-36 35.0 0.57 1.30 Jul 3 7 34-41 37.3 0.73 1. 36 3 1 34 34· 0.8 2.0 Aug 15 22 34-58 43.3 1.16 1.31 ~ 412 Table 8.62 Mean lengths, weights, and condition factors of Skagit River coho fry captured by electroshocking near Talc Mine, 1973-74 brood. Mean Number Length (mm) Mean condition Date of fry Range Mean weight (g) factor 1974 Apr 17 2 34 34.0 0.35 0.89 23 1 39 39 0.4 0.7 May 7 2 35-36 35.5 0.40 0.90 20 1 35 35 0.3 0.7 Jun 13 1 35 35 0.5 1.2 Jul 5 22 31-50 36.9 0.54 0.98 Aug 15 11 35-51 46.8 Sep 4 9 40-63 47.9 1.31 1.07 - ""'" - - ~~ !""" ·- 413 Table 8.63 Mean lengths, weights, and condition factors of Skagit River coho fry captured by electroshocking near Marblemount, 1973-74 brood. Mean Number Length (mm) Mean condition Date of fish Range Mean weight (g) factor 1974 Apr 17 1 33 33 0.3 0.8 May 5 1 37 37 0.4 0.8 Jun 12 12 33-38 35.7 0.40 0.88 Jul 2 18 31-42 36.5 0.52 0.99 Aug 15 10 34-53 39.5 414 ....... Table 8.64 Mean lengths, weights, and condition factors of Cascade River coho fry captured by electroshocking, 1973-74 brood. ~· Mean ~. Number Length ~mm} Mean condition Date of fish Range Mean weight (g) factor 1974 ~. --Apr 23 3 34-35 34.7 0.35 0.84 May 7 5 32-36 34.2 0.37 0.92 21 21 31-40 34.7 0.32 0. 77 ~: Jun 12 9 32-34 33.5 0.41 1.09 Jul 2 16 32-43 37.8 0.62 1.10 Aug 9 15 35-62 45.7 1.21 1.21 ~~ ~. I 415 Table 8.65 Mean lengths, weights, and condition factors of Sauk River coho fry captured by electroshocking, 1973-74 brood. ,-Mean Number Length (mm) Mean condition Date of fish Range Mean weight (g) factor 1974 F" Apr 23 6 33-39 36.2 0.48 1.02 May 21 3 35-36 35.7 0.40 0.88 Jun 13 2 32-33 32.5 0.50 1.46 Jul 3 2 41-42 41.5 1.10 1. 54 Aug 9 7 47-60 54.0 2.06 1. 28 416 Table 8.66 Mean lengths, weights, and condition factors of Goodell Creek coho fry captured by either electroshocking or fyke netting, 1973-74 brood. Mean Number Length (mm) Mean condition Date of fish Range Mean weight (g) factor 1974 Mar 25 26 33-39 36.5 0.39 0.79 Apr 8 28 33-39 35.8 0.38 0.86 ,...., 10* 57 30-38 34.6 0.37 0.89 10 19 33-39 35.9 0.47 1.00 17 28 34-39 36.2 0.41 0.86 24 30 34-40 36.9 0.43 0.87 May 6 38 32-42 35.3 0.38 0.83 20 29 33-41 37.5 0.49 0.92 21* 34 31-38 34.9 0.36 0.84 Jul 2 32 31-52 36.4 0.53 0.98 Aug 9 3 31-40 34.7 0.57 1.33 15 21 36-44 39.4 0.80 1.27 *fyke net samples :~ "'~ 417 Table 8. 67 Mean lengths, weights, and condition factors'of Bacon Creek coho fry captured by either electroshocking or fyke netting, 1973-74 brood. Mean Number Length (mm) Mean condition Date of fish Range Mean weight (g) factor 1974 Apr 9* 59 32-39 35.7 0.32 0.70 10* 33 33-38 35.1 0.31 0. 71 """ 10 10 31-35 33.1 0.36 0.99 17 16 32-37 34.7 0.39 0.94 23 14 33-40 35.7 0.36 0.79 May 8 12 33-38 36.0 0.40 0.84 20 21 32-37 34.9 0.35 0.83 21* 43 34-40 36.4 0.38 0. 78 Jun 13 9 31-41 35.3 Ju1 3 48 31-50 35.4 0.45 0.98 18 11 33-51 37.6 0.60 1.01 25,~ 7 32-36 34.3 0.44 1.09 ' ..... \ Aug 1 3 32-35 34.0 0.37 0.94 9 3 35-36 35.3 0.53 1.20 15 10 37-47 39.8 *fyke net samples - 418 Table 8.68 Mean lengths, weights, and condition factors of Diobsud Creek coho fry captured by either electroshocking or fyke netting, 1973-74 brood. Mean Number Length (mm) Mean condition Date of fish Range Mean weight (g) factor 1974 Apr 10* 2 32-34 33.0 0.40 1.12 10 1 37 37 0.5 1.0 17 4 34-39 36.7 0.39 0.79 23 1 36 36 0.3 0.6 ~! May 8 3 37-39 38.0 0.43 0.78 20 11 33-37 35.8 0.39 0.86 Jun 13 12 33-37 34.2 0.41 1.03 Jul 2 12 33-38 35.0 0.38 0.90 18* 3 34-37 36.0 0.47 1.00 25 11 32-36 34.0 0.38 0.97 ~ Aug 9 17 31-38 34.0 0.37 0.92 - *fyke net samples - 419 Table 8. 69 Coho fry catches at Skagit Basin sampling sites using electrofisher, 1975-76 brood. -Skagit River at County Talc Marble-Rock-Cascade Sauk Goodell Bacon Diobsud Date Line Mine mount port River River Creek Creek Creek ' 1976 -2/22 -2/28 2/29 -3/6 2 3/7 -3/13 11 3 25 3/14 -3/20 27 4 25 3/21 -3/27 25 -8 31 3/28 -4/3 24 19 26 4/4 -4/10 31 1 29 28 4/11 -4/17 1 24 1 40 28 18 4/18 -4/24 2 2 22 1 35 3 22 25 4/25 -5/1 2 4 48 1 31 26 ~ 5/2 -5/8 2 2 so 10 26 38 5/9 -5/15 2 4 29 9 33 5/16 -5/22 16 27 3 25 24 1 5/23 -5/29 2 7 24 4 25 25 5/30 -6/5 40 14 6 67 36 6/6 -6/12 16 3 26 4 29 3 38 25 4 6/13 -6/19 34 5 26 7 33 10 24 26 -~ 6/20 -6/26 45 8 23 10 so 41 25 28 6/27 -7/3 45 3 10 42 31 28 27 3 7/4 -7/10 32 17 8 51 3 25 32 7/11 -7/17 23 1 18 32 7 27 28 27 7/18 -7/24 1 22 25 26 39 29 24 7/25 -7 I 31 14 34 25 35 7 26 29. 29 -8/1 -8/7 33 38 37 36 11 26 28 32 8/8 -8/14 29 4 25 25 25 4 26 29 8/15 -8/28 24 14 25 25 25 9 29 34 30 8/29 -9/11 16 31 28 33 23 7 27 36 9/12 -9/25 25 28 32 26 2 26 12 26 9/26 -10/9 5 5 4 5 10/10-10/23 10 10 24 9 5 3 27 34 10/24-11/6 26 1 30 30 14 5 34 33 11/7 -11/20 13 17 27 9 12 2 11 11 11/21-12/4 15 14 21 11 17 23 14 15 12/5 -12/11 14 6 10 9 11 8 10 12 12/12-12/18 19 5 7 15 9 11 15 12/19-12/25 14 7 2 12 10 1 12 12/26-1/1 10 3 4 7 2 15 2 1977 1/z--.:-1/8 1 10 6 11 13 1/9 -1/15 1 5 5 1/16 -1/22 7 2 7 1 4 1/23 -1/29 1 1 4 1/30 -2/5 8 6 2 - Date 1977 2/r;--::2/ 12 2/13 -2/19 2/20 -2/26 2/27 -3/5 3/6 -3/12 3/13 -3/19 3/20 -3/26 3/27 -4/2 4/3 -4/9 4/10 -4/16 4/17 -4/23 4/24 -4/30 5/1 -5/7 5/8 -5/21 5/22 -6/4 Table 8.69 Coho fry catches at Skagit Basin sampling sites using electrofisher, 1975-76 brood -continued. Skagit River at County Talc Marble-Rock- Line Mine mount port 2 3 1 1 Cascade Sauk Goodell Bacon Diobsud River River Creek Creek Creek 1 3 1 2 2 1 1 1 1 1 1 1 1 1 1 1 Note: dash (-) signifies catch was zero. blank signifies sampling not conducted. ~ N 0 ~ 421 Table 8.70 Coho fry catches at Skagit Basin sampling sites using electrofisher, 197 6-77 brood. .--. Skagit River at County Talc Marble-Rock-Cascade Sauk Goodell Bacon Diobsud Date Line Mine mount port River River Creek Creek Creek 1977 1/25 -1/29 1/30 -2/5 1 2/6 -2/12 1 4 1 6 2/13 -2/19 2/20 -2/26 1 2/27 -3/5 3 3/6 -3/12 3/13 -3/19 8 1 3/20 -3/26 1 2 '""' 3/27 -4/2 2 1 4 1 4/3 -4/9 2 2 35 1 10 4/10 -4/16 2 1 31 15 30 1 4/17 -4/23 1 2 1 28 11 10 4/24 -4/30 6 4 5 7 40 1 29 11 1 5/1 -517 5 2 3 40 15 22 22 2 5/8 -5/21 1 20 1 15 36 3 22 13 7 5/22 -6/4 62 39 1 57 42 37 16 15 11 6/5 -6/18 143 39 10 26 32 46 16 17 13 6/19 -7/2 75 39 29 15 46 34 16 14 9 -7/3 -7/16 67 31 28 31 30 31 12 12 12 7/17 -7/30 117 49 60 27 41 49 12 19 17 7/31 -8/13 90 36 32 25 25 16 12 16 11 8/14 -8/2 7 68 39 28 18 25 9 12 10 16 -8/28 -9/3 79 24 29 25 45 9/20 -9/21 46 37 17 9 38 5 10/19-10/22 83 5 17 3 37 11/18-11/20 24 36 13 24 20 4 12/15-12/20 8 1 21 ~~ 1978 1/11 1/18 -1/22 2/1 .-2/10 2/17 2/24 -2/26 -3/3 3/10 3/17 -3/24 -3/27 5 1 3/31 4/7 1 :"'"" Note: Dash (-) signifies catch was zero. Blank signifies sampling not conducted. ~:~ 422 _, Table 8. 71 Coho salmon catches at Skagit Basin sampling sites using electrofisher, 1977-1978 brood. ..... Skagit River at County Talc Marble-Rock-""" Date Line Mine mount port Concrete Cascade Sauk 19 78 1/18-1/22 2/1 2/10 2/17 2/24-2/26 6 3/3 3/10 3/17 1 3/24-3/27 1 1 1 34 2 3/31 4/7 2 4/13 8 4/21 6 1 4/24-4/25 14 5/2 20 1 4 5/9 -5/10 25 5/16-5717 26 5 3 5/23 35 3 2 6/1 35 3 7 6/6 3 12 6/13 3 1 6 6/20 3 6/27 28 9 21 ,...., -Note: dash (-) signifies catch was zero blank signifies sampling not conducted - _.., - - - - - 423 8.1.4.11 Coho Salmon Fry Size and Condition after Emergence. r~ean lengths, weights, and condition factors of coho fry from the 1973-1974 brood are presented in Tables 8.61 through 8.68. Fry from most sites showed some increase in size and condition with time. Length and weight data for coho fry of the 1975-1976 brood (Figs. 8.48 and 8.49) showed patterns similar to chinook data. From first appearance through June for Cascade and Sauk fry and through July for Skagit (Marblemount) fry, length and weight were fairly constant or increased slightly. After those respective dates, the two parameters increased at all three sites, with the values for the Sauk samples increasing most rapidly, for the Skagit (Marblemount) least rapidly, and at an intermediate rate for the Cascade. The sharp dip in both length and weight for fry from the Cascade and Sauk rivers during late November (November 24) corresponds with a day when natural flows were increasing rapidly because of rain (Fig. 2.5) and resulted in either reduced sampling efficiency or reduced availability of the larger fry, or both. Condition factors (Fig. 8.50) showed more variability than length or weight. For the period from Harch through September, mean condition factor at Cascade and Sauk sites increased and thereafter appeared to level off or decrease slightly to about 1.2. Skagit (Harblemount) coho condition factor was fairly constant from April through July, increased from August to October, and then leveled off at values similar to those for Cascade and Sauk coho fry. Even though condition factors were comparable for this latter period, Cascade and Sauk river fry were longer and heavier. The reduced size and availability of Sauk River coho fry during late November and December indicated that larger fry may have been able to avoid capture or may have moved to faster flowing and deeper rearing habitats outside the range of the backpack electroshocker. The differences in growth patterns of coho fry between the three rivers appear to reflect benthic insect density (Figs. 3.15 and 3.16) in the three rivers for the periods for which data are available. They clo not correlate well with water temperature data for 1976. From ~lc:ly through September, Skagit (at Alma Creek) water temperature was intermediate to Sauk (warmer) and Cascade (cooler) water temperatures, C~no after mid-October was warmer than both (Fig. 2.28). Comparative water quC~lity in the different rivers may also have been a factor. Coho fry of the 1975-1976 hrood continuen to he present At most sites for the first months of 1977, hut showed no distinct increase in size or condition (Tables 8.72-8.80). Like earlier hroons, fry of the 1976-1977 brood showed little change in size nnd condition shortly after the beginning of emergence, followed by a period of increasing size (Figs. 8.51-8.59). These figures include samples thAt contnined more than one fry. The early period of little size and condition change was shorter than in previous years and, at some locntions, it was non-existent, especially in condition factor. The 1976-1977 brood of c0ho from the Skagit sites showed some tendency for coho collected at the downstream Skagit stations (Rockport and Marblemount) to he p,enerally 1ongl'r :tnd to weigh more than fish collected at the upstream Skagit stations (County 424 80 LEGEND (J) -e-SKAGIT (MARBLEMOUNT) 0::: 70 CASCADE w ......_ I-w -+-SAUK l:: .......... _j _j .......... l:: 60 z .......... :c I- CJ z 50 w _j >- 0::: LJ.... z 40 a: w l:: JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 1976 Fig. 8.48 Mean lengths of Skagit, Cascade, and Sauk coho fry taken by electrofishing, 1975-76 brood. ~I ~ ~ """' -.... :: - - - (f) E: <I 0::: 0 z 1----1 I- I 0 1----1 w 3: I I- ·.-. w 3: )- 0::: -LL z <I w :L: - - Fig. 8.49 425 8 LEGEND -er SKAGIT (MARBLEMOUNT) 5 ----A-CASCADE -+-SAUK 4 3 2 1 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 1976 Mean wet weights of Skagit, Cascade, and Sauk coho fry taken by electrofishing, 1975-76 brood. 426 1 .sao r;::::===========~~~,-------------, 0::: 0 1--u cr: lL 1.300 ~ 1.100 1--1 LEGEND -e-SKAGIT (MARBLEMOUNT) ---A-CASCADE -+-SAUK - ~ - 1--1 0 z 0 u >-a:::: lL z cr: w L: .900 .700 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC . 197€ Fig. 8.50 Mean condition factors of Skagit, Cascade, and Sauk coho fry taken by electrofishing, 1975-76 brood. ~' 1 Table 8. 72 Mean lengths, weights, and condition factors of coho salmon fry captured by electroshocking at the County Line Station in 1977 . . -----------------·----197:;-76 brood 1976-77 brood ?'lean !-lean Mean Mean Mean MeaR Number length weight condition Nwnber length weight condition Date of ,-r. (mm) (g) factor of fry (mm) (g) factor January 19 7 73.6 4.650 1.165 0 February 8 0 1 37.0 0.380 0. 750 18 2 71.0 4.615 1.193 0 March 31 0 2 34.5 0.300 0. 723 April 13 0 2 34.5 0.300 0.731 20 0 1 34.0 0.320 0.814 27 0 6 33.7 0. 280 0. 726 .j::-- May 26 0 25 36.5 0.409 0.810 N ........ June 7 0 26 36.0 0. 375 0. 790 22 0 23 40.1 0.639 0.926 July 7 0 24 38.8 0.617 1.015 19 0 27 43.3 0.927 1.064 August 3 0 25 43.4 0.936 1.094 16 0 25 4 7. 5 1. 273 1.173 29 0 26 48.5 1.250 1.076 September 21 0 25 55.4 1.868 1.073 October 22 0 25 64.4 3.259 1.168 November 20 0 14 58.2 2.137 1.026 Date January 6 March 29 April 13 22 26 May 12 26 June 7 22 July 7 19 August 3 16 29 September 21 November 20 _J Table 8.73 Mean lengths, weights, and condition factors of coho salmon fry captured by electroshocking at Talc Mine Station in 1977. 1215-Zf! brood 19Z6-Z7 brood Mean Mean Mean Mean Mean Number length weight condition Number length length of fry (mm2 (g2 factor of fry (mm2 (g) 4 72.5 4. 39 2 1.153 0 3 70.0 3. 420 0.987 1 35 .o 0.310 1 77.0 4.840 1.060 0 0 2 36.0 0.310 1 71.0 3.680 1.028 4 36.5 0.390 0 20 36.2 0.391 0 25 36.0 0.373 0 25 39.1 0,629 0 25 39.4 0.640 0 25 41.9 0.823 0 25 39.1 0.644 0 25 44.9 1.175 0 23 49.6 1.633 0 24 48.0 1.255 0 25 53.8 1.893 0 26 55.7 2.142 Mean condition factor 0. 723 0.664 0.793 0.809 0. 774 .p. N OJ 0.995 0.958 0.987 1.001 1.147 1.195 1.099 1.182 1.098 Table 8,74 Number Date of fry January 4 1 February ')~ _:> 0 April 6 0 12 0 26 0 ~[a\' 12 0 June 6 0 22 0 July 7 0 19 0 August 2 0 16 0 29 0 September 20 0 October 19 0 :iovember 20 0 December 15 0 Nean lengths, weights, and condition factors of coho salmon fry captured by electroshocking at Narblemount Station in 1977. 12Z5-Z6 brood 19Z6-ZZ brood Mean Mean Nean Mean Mean length weight condition Number length weight (mm) (g) factor of fry (mm) (g) 54.0 1.810 1.149 0 1 32.0 0.240 2 32.5 0.240 1 37.0 0.400 5 36.0 0.346 1 35.0 o. 290 10 36.0 0.376 19 35.7 0.443 24 45.4 1. 214 25 47.6 1.537 25 46.8 1.410 25 52.0 1. 827 25 59.9 2.656 7 59.4 2.694 7 67.6 3.297 3 72.3 4.177 1 77.0 4.620 Mean condition factor 0.732 0.699 0.790 0.738 0.676 .J:'- 0. 779 N 1.0 0.932 1.178 1.275 1.334 1. 246 1.145 1.127 1.035 0.998 1.012 Date January 20 April 22 26 May 12 24 June 6 21 July 5 19 August 2 16 September 1 November 18 Table 8.75 Mean lengths, weights, and condition factors of coho salmon fry captured by electroshocking at Rockport Station in 1977. 12Z5-Z6 brood 1976-77 brood Mean Mean Mean Mean Mean Number length weight condition Number length weight of fr:y (mm) (g) factor of fry_ (mm) (g) 2 62.5 2.840 1.163 0 0 1 33.0 0.190 0 7 33.4 0.256 0 15 35.9 0.363 0 22 37.9 0.465 0 26 37.1 0.466 0 15 41.3 0. 791 0 25 46.5 1.270 0 25 49.0 1.465 0 25 51.9 1.847 0 18 58.3 2.459 0 25 59.3 2. 779 0 14 65.6 2.850 Mean condition factor 0.529 0.687 0. 772 0.824 0.871 0.997 .p. w 0 1.180 1.179 1. 286 1.223 1.266 0.995 Date January 5 13 19 February 2 9 March 7 14 21 April 6 11 18 25 May 2 9 24 June 6 22 July 5 20 August 2 15 29 September 20 1 Table 8.76 Hean lengths, weights, and condition factors of coho salmon fry captured by electroshocking at Cascade River in 1977. 12Z5-Z6 brood 1976-77 brood Mean Mean He an Mean Mean Number length weight condition Number length weight of fry (mm) (g) factor of fry (mm) (g) 5 01.2 2.506 1.045 0 1 53.0 1.920 1.290 0 7 64.7 3. 307 1.118 0 0 1 35.0 0.360 4 73. 7 4.880 1.204 0 2 71.0 3.800 1.063 0 1 64.0 3.200 1.221 0 0 1 33.0 0. 250 0 26 33.6 0.368 0 25 34.9 0.325 0 25 34.8 0.309 0 25 36.8 0.411 0 26 36.5 0.405 0 25 38.4 0.509 0 24 36.9 0.481 0 24 37.8 0.572 ·o 20 38.8 0.644 0 25 39.7 0.651 0 25 44.3 1.019 0 25 44.1 0. 989 0 25 4 7. 4 1.344 0 25 46.1 1.103 0 26 47.6 1.165 ) Mean condition factor 0. 840 0.696 .f:'-w 1-' 0.949 0. 760 0. 729 0. 771 0.821 0.878 0. 927 0.941 1.026 0.990 1.112 1.100 1.152 1.067 1.058 Date October 19 November 18 December 15 Table 8.76 Mean lengths, weights, and condition factors of coho salmon fry captured by electroshocking at Cascade River in 1977 -continued. 12Z5-Z6 brood 1976-77 brood Mean Mean Mean Mean· Mean Number length weight condition Number length weight of fry (mm) (g) factor of fry (mm) (g) 0 25 53.9 1.856 0 10 57.6 2.068 0 16 58.3 2.202 Mean condition factor 1.147 1.015 1.052 Date January 25 February 9 March 14 April 18 25 May 2 9 24 June 6 21 July 5 20 August 2 15 l Table 8.77 Mean lengths, weights, and condition factors of coho salmon fry captured by electroshocking at Sauk River in 1977. 12Z5-Z6 brood 1976-77 brood Mean Mean Mean Mean Mean Number length weight condition Number length weight of fry (mm) (g) factor of fry (nun) (g) 1 75.0 4.860 1.152 0 1 63.0 3.160 1. 264 0 1 69.0 3.990 1.215 0 1 76.0 4.340 .989 0 0 1 35.0 0.350 0 9 34.1 0.288 0 3 34.7 0.363 0 25 35.3 0.335 0 25 38.0 0.513 0 30 39.7 0.643 0 25 45.4 1.055 0 25 49.2 1.324 0 16 51.3 1.582 0 9 52.5 1.539 Nean condition factor 0.816 0. 725 ~ w 0.869 w 0.746 0.923 1.002 1.090 1.095 1.141 1.054 Date January 20 25 February 4 23 March 1 14 22 29 April 4 11 20 25 May 2 9 26 June 7 21 July 5 20 August 2 15 Table 8.78 Hean lengths, weights, and condition factors of coho salmon fry captured by electroshocking at GoodellCreek in 1977. 12.15-ZfJ brood 1976-77 brood Mean He an .He an Mean He an Number length weight condition Number length weight of fry (mrn) (g) factor of fry (mm) (g) 1 75.0 4.310 1. 022 0 1 77.0 4.830 1.058 0 3 69.0 4.330 1.210 0 1 65.0 2.480 .903 0 0 3 33.3 0.263 0 8 34.3 0.290 1 61.0 2.790 1.229 2 33.5 0.260 0 4 35.5 0.343 0 10 35·.1 0.378 0 12 35.5 0.351 0 11 37.0 0.481 0 10 37.4 0.441 0 10 35.8 0.363 0 10 37.1 0.448 0 10 39.3 0.732 0 10 40.3 0.654 0 8 38.6 0.553 0 10 45.8 1. 093 0 10 49.1 1.485 0 10 44.1 1. 204 0 10 44.3 0.963 He an condition factor 0.712 0. 720 0.692 0.763 .1':-w ~ 0.819 0. 774 0.887 0.834 o. 775 0.833 1.151 0.912 0.936 o. 977 1.082 1.272 1.102 Table 8,79 Number Date of fry January 5 9 13 5 February 4 5 23 3 March 8 l 14 0 29 0 April 11 0 20 1 25 1 May 2 1 9 0 26 0 June 7 0 21 0 July 5 0 20 0 August 2 0 15 0 l Hean lengths, weights, and condition factors of coho salmon fry captured by electroshocking at Bacon Creek in 1977. 12 Z5-Z6 brood 1976-77 brood Mean Mean Mean Mean Mean length weight condition Number length weight (mm) (g) factor of fry (mm) (g) 62.8 3.013 1.114 0 71.6 4.336 1.152 0 67.4 3.620 1.156 0 59.7 2.507 1.118 0 77.0 4. 790 1.049 0 1 34.0 0.280 1 38.0 0.450 10 37.1 0.441 76.0 4.860 1.107 9 35.2 0.320 59.0 2.270 1.105 9 37.1 0.446 67.0 4.140 1. 376 9 37.8 0.481 10 39.2 0.586 10 36.6 0.414 10 36.2 0.388 10 36.8 0.503 10 39.3 0.603 10 45.8 1.196 10 46.2 1.350 10 49.2 1.452 --J Mean condition factor 0. 712 0.820 0.862 +:-w 0. 729 VI 0.860 0.863 0.940 0.835 o. 805 1.005 0.969 1.107 1.279 1.183 Date January 13 20 25 February 4 9 March 1 8 29 April 25 May 2 9 26 June 7 21 July 5 20 August 2 15 Table 8.80 Mean lengths, weights, and condition factors of coho salmon fry captured by electroshocking at Diobsud Creek in 1977. 12Z5-Z6 brood 19 76-Z7 brood Mean Mean Mean Mean Mean Number length weight condition Number length weight of fry (rnm) (g) factor of fry (rom) (g) 5 54.0 1.754 1.038 0 4 51.8 1.550 1.102 0 3 60.7 2.680 1.111 0 2 67.5 3.745 1. 082 0 5 61.2 2.914 1.137 0 2 57.0 1.915 1.007 0 1 55. o. 2.080 1.250 0 1 68.0 3.700 1.177 0 0 1 36.0 0.390 0 2 34.5 0.245 0 7 34.3 0.283 0 9 35.6 0.348 0 10 35.6 0.386 0 9 35.6 0.355 0 10 35.9 0.394 0 10 38.7 0. 704 0 10 37.2 0.570 0 10 46.2 1.014 J Mean condition factor ~ 0.836 w a- 0.586 0.696 0.752 0.842 0.768 0.832 0.983 1.107 0.985 -_J ~ - .... - r ,..-.. L: ·--L: '--' I I-o z. w _j z a: w L: -~ - 437 80 LEGEND -6-COLNTY LINE 70 "'*" 7ALC MINE -e-W.r3Lct~OUNT -+-ROCKPORT so 50 40 30 clArJ FEB I'~AR APR MAY JU~I JUL AUG SEP OCT NOV DEC 1977 Fig. 8.51 Mean lengths of coho fry taken by electrofishing from four Skagit River stations, 1976-77 brood. t.oo 438 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 1977 Fig. 8.52 Mean weights of coho fry taken by electrofishing from four Skagit River stations, 1976-77 brood. - - - - - - ~ 0 1--u CI lJ..... z 0 .......... I-........ Ct z 0 u z CI w :I: 439 COHO FRY , 1977 1.500~------------------~----------------------~ 1.300 1.100 .goo .700 LEGEND -e9-COUNTY LINE '"'*-TALC r~INE -&-MI~RBLEMOUIH -+ ROCt:PORT .soa._~--~--~--~~--~--~~--~--~--~--~ JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 1977 Fig. 8.53 Mean condition factors of coho fry taken by electrofishing from four Skagit River stations, 1976-77 brood. 40 440 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 1977 Fig. 8.54 Mean lengths of Skagit, Cascade, and Sauk coho fry taken by electrofishing, 1976-77 brood. - """' - ,...-.. D '~ '-J I-:r: D ~ w ~ z cr: w ::L: - 441 s.aa LEGEND -er SKi\GIT (~1arblemount) 4.00 ...... CASCADE -+-SAUK 3.00 z.ao 1.00 0._ __ ~--~--~--~--~--_.--~--~----~--~--~--~ JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 1977 Fig. 8.55 Mean weights of Skagit, Cascade, and Sauk coho fry taken by electrofishing, 1976-77 brood. a::: a 1-u a: LL z a 1--4 1- 1--4 D z a u z a: w L: 442 1.500 LEGEND -e-SKAGIT (r1a rb 1 emount) 1.300 -6--CASCADE -+-SAUK 1.100 .goo .700 JAN FEB MAR APR MAY . JUN JUL AUG SI:::P OCT NOV DEC 1977 Fig. 8.56 Mean condition factors of Skagit, Cascade, and Sauk coho fry taken by electrofishing, 1976-77 brood. ~. -' ~ ~ - ~ ~' - ~- ~' - ~' .,.,. - ;"'~ ~ :L: :L: :r:: I- D z w _j z a: w L: - 443 80 LEGEND --*--GOODELL 70 ~ BACON ----DIOBSuD 60 50 40 3o~~L-~--~--~--~--~--~~~--~--L-~--~~ JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV · DEC 1977 Fig. 8.57 Mean lengths of coho fry taken by electrofishing from three Skagit creeks, 1976-77 brood. ,..-.. a '--' I- I a ......... w ~ z cr: w L: 444 5.00 LEGEND """'*---GOODELL 4.00 .... BACON ""*-DIOESUD 3.00 2.00 1.00 JAN FEB t~AR APR MAY JUN JUL AUG SEP OCT NOV DEC 1977 Fig. 8.58 Mean weights of coho fry taken by electrofishing from three Skagit creeks, 1976-77 brood. - - - m\'1 l!!iilfll"t, ~ ~~· - ~., 0::: 0 I-u a: lL. z 0 .-1----l I- 1----l 0 z 0 u z a: w ::L '""" 445 1 .sao LEGEND --*-GOODELL 1.300 -$-Bf.CON ----DIOBSUC 1.100 .goo .700 JAN FEB MAR APR ~1AY JUN JUL AUG SEP OCT NOV DEC 1977 Fig. 8.59 Mean condition factors of coho fry taken by electrofishing from three Skagit creeks, 1976-77 brood. 446 Line and Talc Mine) from about June 7 to October 22 (Figs. 8.51 and 8.52). There were also lower mean condition factors for fish sampled from the upper two Skagit stations than from the lower two stations from about July 7 to August 21 (Fig. 8.53). Semi-monthly mean temperatures averaged over the years 1974 to 1977 showed that water temperatures at Newhalem, near the County Line Station, were cooler from January to June and again in August and September than at the other Skagit temperature stations farther downstream (Fig. 2.31). The likelihood that this reduced temperature is responsible for the decreased size and condition at the two upstream SKagit sites is reduced by the fact that lower size and condition at upstream stations were not obvious in other species. The size and condition of coho fry of the 1976-1977 brood from the Skagit River at Marblemount and the Cascade and Sauk rivers (Figs. 8.54 - 8.56) are quite different from the 1975-1976 brood (Figs. 8.48-8.50). In the first season of growth at the t1arblemount Station, coho fry of the 1976-1977 brood had much greater mean lengths and weights after the initial level period (Figs. 8.54 and 8.55) compared to fry from the previous brood year (Figs. 8.48 and 8.49). Mean condition factors were higher than in the previous year from the end of the initial level period to about September when condition factors at all sites started leveling off (Fig. 8.56 and 8.50). Water temperatures in the Skagit in 1977 were generally warmer during the coho incubation and early rearinp, period than in 1976 (Fig. 2.32). In addition, the frequency and magnitude of flow fluctuations due to. hydropower operations were greatly reduced in the second half of April, 1977, and continued more stable into November. The overall flow level was also much lower. These conditions would be more favorable for juvenile coho to maintain their feeding stations in the stream. In contrast, in the Cascade River, samples of coho fry showed generally lower lengths ~nd weights after the initial level period in 1977 than in 1976 (Figs. 8.54 and 8.55; Figs. 8.48 and 8.49). Differences be- tween brood years in mean condition factors during the first season of growth were less distinct. The turbidity was somewhat higher in the Cas- cade River from June to November in 1977 than over the same period in 1976 (Table 3.8 and 3.9) and may have reduced benthic insect standing crop, feeding efficiency and growth in coho fry in 1977 despite the warmer temperatures during the incubation and early rearing period in 1977. In addition, river flows were lower in spring-summer of 1977. Despite warmer temperatures in the Sauk River in 1977, the size and condition of year-0 coho fry also appeared lower after the initial level period than those of the previous season, possibly because of the greatly increased turbidity in 1977 (Table 3.9). In addition, spring-summer flows were lower in 1977. Samples of coho fry from the Sauk River were availa- ble only into August in 1977. In the three minor Skagit tributaries -Goodell, Bacon, and Diobsud creeks -mean lengths, weights, and condition factors of 1976-1977 brood coho fry showed increases generally similar to those of fry collected from the mainstem stations (Figs. 8.57-8.59; Tables 8.78-8.80). First .,.. ""'' - 447 emergence and subsequent apparent growth pattern of fry from the smallest tributary, Diobsud Creek lagged behind that of the other two creeks. 8.1.4.12 Coho Salmon Fry Diet_. The stomach contents of 182 coho fry of the 1975-1976 brood were exar1ined, 91 fro!!'. the upper three Skagit River stations, 36 from the lower two Skagit River stations, 46 from the Cascade River, and 9 from the Sauk river. The results of the analysis are presented in Tables 8.81-8.84. Chironomids, of which a high percentage were adults, and Ephemerop- tera nymphs were the most numerous food items in the diet of the 1975-1976 brood of coho (Table 8.85). Planktonic organisms were found in fry samples from the Skagit sites, especially the upper three (Tahle 8.81). They were cost numerous in the July, Aupust, and December, 1976, samples. Although plankton densities in the Skagit River were low in August, 1977, as determined by plankton pump samples (Sec. 4.0), densities in December, 1977, were fairly high. 8.1.4.13 Rainbow-Steelhead Trout Fry Availability. Because of the late winter-spring timing of rainbow-steelhead spawning, fry were not abundant until summer (Tables 8.86-8.88). In 1976 (Table 8.87), fry were found as early as mid-June but were not numerous in the mainstem Skagit River stations above the Sauk until August. Fry were abundant in the Sauk River several weeks before other sites. Yearlings from the 1976 brood were still present at all stations except Diobsud Creek at least to July 1977. In the mainstem Skagit, the juveniles of the 1976 brood were less available during much of 1977 than at many of the other stations. Fry from the 1977 brood emerged much earlier than fry from the 1976 brood (Tables 8.87 ·and 8.88)·. This is the largest observed advancement in ei'lergence timing of any of the salmonid species in the study area. There was even a later observed peak of spawning in 1977 in the Skagit River (Sec. 6.4.2.5). Rainbow-steelhead, being spring spawners, may have a different degree or direction of compensation than do the salmon species in temper?ture units required for emergence under different incubation temperatures. Samplinp was continued at three Skapit sites into June 1978 and rainbow-steelhead fry of the 1977 brood continued to b~ caught at two of them (Table 8.88). 8.1.4.14 Rainbow-Steelhead Trout Fry Size and Condition after Emergenc~. Some rainbow-steelhead fry from the 1974 brood were analysed for size and condition, but not enough samples were taken to exhibit distinct temporal trends or differences between stations (Table 8.86). In the 1976 brood the general pattern seen in other salmonid fry in the Skagit Basin of an initial level period of fairly constant values followed by a period of increasing values was shown for rainbow-steelhead trout growth parameters (Figs. 8.60, 8.61, and 8.62). The divergence between the three sites durinp, the increasing phase was not as pronounced as for coho but it did reflect the pattern of benthic insect density differences between the Skagit, Cascade, and Sauk rivers (Sec. 3.0). All three parameters showed a convergence of values at the three sites in late T~bl,e 8.81 Coho fry stomach contents, 1975-76 brood, upper three Skagit sites. Date May 1976 June 1976 July 1976 August 1976 September 1976 ------------------------- Loca t,ion and 'County Line 1 County Line 't County Line 5 County Line 5 Countv Line 5 sample size Marblemount 5 Talc Nine 1 Marblemount 5 Talc :-line 10 Marblemount 10 % Empty 0 0 ______ Q_---0 0 ----------~ Freq. Total 1: Freq. Total % Freq. Total % freq. Total % Fre<]. Total % occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. C:nllembola 12.0 3 .99 l'st•ptera 20.0 19 6.29 Homnptera 10.0 3 2.11 16.7 1 .57 40.0 27 1!.94 Ephemeroptera nYmphs 100.0 1 25.00 90.0 58 40.85 83.3 20 11.43 80.0 125 53.88 8.0 6 1. 99 adults Pleccptera nvmphs 50.0 11 7.75 16.7 1 .57 70.0 14 6.03 52.0 34 11.25 ndul ts 16.0 20 n.62 Trichoptera lnrvae 30.0 4 1. 72 l~.'J 3 .99 pupae :..o 2 .6n .t--- adults 8.0 2 . 66 ~ .... OJ Diptera Chironomidae larvae 70.0 40 28.17 100.0 124 70.86 70.0 19 8.19 44.0 20 n.62 pup;1e 10.0 1 . 70 16.7 1 0. 57 10.0 .1 . 43 16.0 P . 2.65 adults 100.0 3 75.00 40.0 21 14.79 33. 3 2 1.14 50.0 20 b.62 36.0 32 10.60 Simul i id"" 33.3 '2. 1.14 30.0 4 1.72 4.0 .33 His c. Dlrtera 20.0 4 2.82 16.7 1 .57 48.0 3J 10.93 rwh·-i.'] 10.0 1 . 70 33.3 11 6.29 [i,·,sm1~t>-:l 66.7 5 2.86 30.0 44 18.97 Chvdorids Hi. 7 1 . 17 D l:a p to".tUS i1dults 33.3 5 2.86 nauplii ~~it es 10.0 2 1.41 8.0 12 3.97 ~-lis c. aqn~t:ics t!isc. terrestri'lls 10.0 1 . 70 16.7 1 . 57 80.0 69 22.85 l'n irlent i fied and inanimate mal erial 10.0 1 .43 20.0 11 3.64 375 Table 8,29 Yolk in emerged chinook fry, upper three Skagit sites, 1975 brood. Feb 76 Mar 76 Apr 76 May 76 Number of stomachs examined 31 15 15 16 Fry with empty gut and yolk 15 48% 1 7% 0 0% 1 6% F" Fry with non-empty gut and yolk 9 29% 1 7% 0 0% 0% 0% Fry with empty gut and no yolk 0 0% 3 20% 1 7% 0% 0% Fry with non-empty gut and no yolk 7 23% 10 67% 14 93% 15 94% -Table 8.30 Yolk in emerged chinook fry, Cascade River, 1975 brood. Feb 76 Har 76 Apr 76 May 76 Number of stomachs examined 0 5 5 5 ,,:QII~ Fry with empty gut and yolk 0 0% 0 0% 0 0% Fry with non-empty gut and yolk 0 0% 0 0% 0 0% Fry with empty gut and no yolk 0 0% 0 0% 0 0% Fry with non-empty gut and no yolk 5 100% 5 100% 5 100% ~ Table 8.Jl · Yolk in emerged chinook fry, Sauk River, 1975 brood. Feb 76 Mar 76 Apr 76 May 76 Number of stomachs examined 0 5 5 5 Fry with empty gut and yolk 0 0% 0 0% 0 0% Fry with non-empty gut and yolk 2 40% 0 0% 0 0% Fry with empty gut and no yolk 0 0% 0 0% 0 0% Fry with non-empty gut and no yolk 3 60% 5 100% 5 100% - - "'"' F"" - r- 1 Table 8.81 Coho fry stomach contents, Date October 1976 Location and County Line 5 sample size Talc Mine 1 Marblemount 5 % Empty Freq. Total % occur. no. occur. Collembola 36.4 5 2.45 Psoptera 36.4 5 2.45 Homopte~a 27.3 4 1. 96 Epl1emeroptera nymphs adults Plecoptera nymphs 9.1 1 .49 adults Tr~ch0ptera larvae 9.1 1 .49 pup,qe adults Di.rtera Chironom.idae l,qrvae 18.2 3 1.47 pup.:Je adults Sirn11liidae ~isr:~ Diptera 72.7 55 26.96 ': .·:--:; ~-l1~r1 {3.,,~·--:ir'.O Chvdorids D':.CF tcrnus adults nauplli Nitrs 18.2 2 .98 ~1 L s c • aquatics 9.1 3 1.47 N is c. terrPsLrials 45.5 8 3.92 Unld~rtified and inanimate material 82.2 2 .98 449 1975-76 brood, upper three Skagit sites -continued. December 1976 January 1977 April 1977 County Line 5 County Line 5 Talc ~line 1 Talc Mine 5 Talc Xine 5 Marblemount 1 Marblemount 5 Marblemount 5 -----freq. Total % Freq. Total % Freq. Total % occur. no. occur. occur. no. occur. occur. no. occur. 9.1 1 .07 20.0 4 .62 90.9 625 42.03 5.0 2 13.33 6.7 1 .15 100.0 54 3.63 100.0 48 3.23 33.3 11 1. 70 100.0 519 34.90 13.3 15 2.32 50.0 6 40.00 72.7 zoo 13.45 13.3 2 .31 27.3 10 .67 50.0 2 13.33 40.0 287 44.43 18.2 2 .13 13.3 4 .62 6.7 16 2.47 20.0 238 36.84 18.2 3 .20 20.0 4 .62 36.4 8 .54 50.0 1 6.67 60.0 13 2.01 63.6 14 .94 50.0 3 12.00 53.3 30 4.64 27.3 3 .20 50.0 1 6.67 __ J Colh·mbola l'soptera Hornoptera Date Location :md sample size % Empty Ephemeroptera nvmphs Plecoptera Trichoptera Diptera Chironomidae Simulild;~« Misc. Dintera DarJt~: ;::; licw"i '''" Cioydorids D1:aT' tcmus Nltes adults nymphs adults larvae pupae adults larvae pupae adults adults nauplii Misc. aquatics Misc. terrestrials Unidentified and inanimate material Table 8.82 Coho fry stomach contents, 1975-76 brood, lower two Skagit sites. June 1976 August 1976 September 1976 October 1976 Rockport 5 Concrete 4 ~!ovember 1976 Rockport 5 Rockport 5 20 .. -';0'-------;;;---- Freq. Total % 0 ;oO:=C;oC~U.-:_r o_• __:,n;:_-O:_:•:___:=O..:::C.:::.:C U r • 0 C C U r • no • 25.0 50.0 25.0 25.0 75.0 25.U 25.0 25.0 1 2 2 1 3 2 1 1 7.69 15.38 15.38 7.69 23.08 15.38 7.69 7.69 20.0 20.0 40.0 60.0 20.0 20.0 80.0 60.0 80.0 20.0 60.0 40.0 20.0 2 1 3 3 1 1 32 6 39 1 4 8 1 % Rockport 8 Concrete 1 ______ 0=----=--- Freq. To tal 7, Rockport 1 _______ 0_ -~--- Freq. Total % Freq. Total occur. occur. no. occur. occur. no. occur. occur. n". 1.96 .98 2.94 .98 31.37 5.88 38.24 .98 3. 92 7.84 .98 11.1 33.3 33.3 66.7 11.1 11.1 11.1 55.6 11.1 33.3 66.7 33.3 11.1 66.7 11.1 1 4 3 19 4 1 2 10 6 63 12 2 17 1 .36 2.61 1.96 12.41 2.61 .65 1.31 6.54 3.92 41.18 7.84 4.57 1. 31 11.11 .65 11.1 66.7 33.3 22.2 55.6 11.1 44.4 33.3 44.4 22.2 77.8 77.8 22.2 33.3 44.4 55.6 1 26 5 2 16 2 19 7 18 3 631 43 2 4 22 33 .12 3.11 .60 100.0' .24 1.91 .24 2.27 .84 2.15 .36 75~39 5.14 .24 .48 2.63 100.0 3.94 1 4 occur. 20.0 80.0 451 Table 8,82 Coho fry stomach contents, 1975-76 brood, lower two Skagit sites-continued. Date January 1977 May 1977 Location and Rockport 2 Concrete 5 sample size -% l,':mpty Frcq. Total % Freq. Total % occur. no. occur, occur. no. occur. Collembola 50.0 1 .16 Psoptera Homoptera Ephemeroptera nymphs 100.0 269 43.81 50.0 2 43.81 adults 25.0 19 38.00 Plecoptera nymphs 100.0 16 2.61 25.0 12 24.00 adults -Trichoptera larvae 100,0 4 .65 25.0 1 2.00 pupae adults 25.0 1 2.00 Diptera Chi ronomidae larvae 100.0 148 24.10 75.0 5 10.00 pupae adults 25.0 3 6.00 Simuliidae 100.0 168 27.36 -Misc. Diptel:'a 100.0 6 .98 75.0 3 6.00 Daphnia Bosmina Chydorids Diaptomus adults 50.0 1 .16 nauplii Hites 25.0 2 4.00 ~lise. aquatics """' Mlsc. terrestrials 50.0 l .16 25.0 1 2.00 Unidentified and inanimate material 25.0 1 2.00 - Table 8,83 Coho fry stomach contents, 1975-76 brood, Cascade River. Date March 1 76 April '76 Hay 1 76 June '7o Aug. '7f> Location and Cascade 2 Cascade 5 Cascade 3 Cascade 8 Cascade 3 sample size 0 0 0 () 0 '% Empty Freq. Total % Freq. Total % Freq. Total % Freq. Total % Freq. Total % occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. Collembola 100.0 2 4.65 40.0 3 4.76 Psoptern H1.1moptera 12.5 4 2.86 Ephcmeroptera nymphs 100.0 5 11.63 20.0 2 3.17 adults 33.3 3 8.82 75.0 10 7.14 66.7 4 10.81 Plecoptera nymphs 100.0 6 13.95 20.0 1 1. 59 25.0 2 l. 43 33.3 1 2.70 adults 20.0 1 l.S'l Trichoptera larvae 40.0 2 3.17 33.3 1 2.94 37; 5 3 2.14 """ pupae l.n adults N Dipteril Chironomidae larvae 100.0 26 60.47 40.0 5 7.94 66.7 4 11.76 75.0 23 16.43 66.7 4 10.81 pupae 40.0 2 3.17 adults 100.0 3 6.98 80.0 41 65.0d 100.0 19 55.88 75.0 91 65.00 66.7 28 75.68 ~imuliidae 12.5 1 .71 ftisc. Diptera 100.0 1 2.33 60.0 6 9.52 66.7 2 5.88 12.5 1 .71 l\?.l~;~ ... li·-z Po2mi•7r:r Chydor ids Di'lp tomm ndults nauplii N ites 33.3 1 2.94 12.5 1 .71 tl.lsc. ::trjuat ics 31.3 2 5.88 12.5 2 1. 4 J Nisc. terrestrial;; 11.3 1 2.94 25.0 2 1. 43 Fish eggs 33.3 1 2.94 Unidentified and inanimate material -1 J l Table 8,83 Coho fry stomach contents, 1975-76 brood, Cascade River-continued. Date Sept. '76 Oct. '76 Jan. '77 Anril 'ZZ Location and Cascade 9 Cascade 5 Cascade 5 Cascade 1 sample size % Empty 0 0 0 0 0 Freq. i,.otal % Freq. Total % Freq. Total % occur. no. occur. occur. no. occur. occur. no. occur. Coll ernbola 20.0 1 .87 Psoptera 11.1 1 .46 Homoptera 33.3 5 2.31 Ephemeroptera nymphs 60.0 8 14.04 100.0 29 38.67 100.0 15 46.88 adults Plecoptera nymphs 55.6 8 3.70 80.0 13 22.81 100.0 23 30.67 100.0 5 15.63 adults 11.1 1 ,46 Tri~hoptera larvae 11.1 1 .46 40.0 3 5.26 pupae J';:-. a.dults Ul w Diptera Chironomidae larvae 66.7 48 22.22 80.0 57 49.57 60.0 25 43.86 pupae 44.4 22 10.19 20.0 1 .87 100.0 12 16.00 adults 88.9 64 29.63 80.0 51 44.35 20.0 1 1. 75 100.0 3 9.38 S i mul i'i dae 44.4 5 2.31 20.0 1 1. 75 40.0 6 8.00 Misc. lliptera 77.8 29 13.52 20.0 1 .87 20.0 3 5.26 100.0 3 9.38 T'arhniq Busmina Chydorids Diaptomus adults nauplii Mites 11.1 2 .93 His c. ar1uatics 22.2 2 .93 20.0 2 3.51 20.0 1 1. 33 His c. terrestrials 77 .B 25 11.57 40.0 3 2.61 20,0 1 1. 75 40.0 4 5.33 100.0 6 18.75 Fish eggs Unidentified and 22.2 3 1.39 20.0 1 .87 inanimate material 454 ~ Table 8.84 Coho fry stomach contents, 1975-76 brood, Sauk River. ~ Date June 1976 August 1976 Location and sample size Sauk 4 Sauk 5 % Empty 0 Freq. Total :::: Freq. Total :::: occur. no. occur. occur. no. occur. Collembola 25.0 1 1. 75 20.0 1 0.87 Psoptern Homoptera 25.0 11 19.30 40.0 4 3.48 Ephemeroptera nvmpbs 75.0 20 35.09 20.0 1 0.87 adults Plecoptera nymphs 50.0 2 3.51 20.0 1 0.87 adults -Trichoptera larvae 25.0 1 1. 75 pupae adults Diptera Chironomidae l.~rva" 100.0 13 22.81 80.0 19 16.52 adults 25.0 1 1. 75 40.0 3 2.61 adults 100.0 8 14.04 100.0 66 57.39 Slmul iidae 20.0 2 1. 74 ~ Misc. Diptera 40.0 4 3.48 · Drlrhnia Bosmina Chyd~rids Diaptomus ndults nauplii Nitcs 20.0 7 6.09 Misc. aquatics p:~ Hisc;. terrestrials 40.0 7 6.09 Unidentified and inanimate material """' 455 Table 8,85 Coho fry stomach contents, summary of 1975-76 brood. Location: Upper 3 Skagit sites Lower 2 Skagit sites Cascade Sauk Date: 1976-1977 1976-1977 1976-1977 1976-1977 ·-Sample size: 91 36 46 9 i. Empty: 0 5.56 2.17 0 Freq. Total i. Freq. Total i. Freq. Total % Freq. Total % occur. no. occur. occur. no. occur. occur. no . occur. occur. no. occur. .... Coil el'li>Ola 8.7 9 0.28 11.8 5 0.28 8.9 6 0.74 22.2 2 1.16 Psoptera 9.8 24 o. 75 8.8 4 . 0.23 2.2 1 0.12 Homoptera 16.3 35 1.09 29.4 31 1. 75 8.9 9 1.11 33.3 15 8. 72 Eph emerop tera nymphs 42.4 842 26.25 44.1 285 16.07 44.4 76 9.36 44.4 21 12.21 adults 8.8 21 1.18 Plecoptera nymphs 41.3 115 3.49 50.0 66 3. 72 44.4 59 7.27 33.3 3 1. 74 adults 5.4 21 0.65 8.8 7 0.39 4.4 2 0.25 Trichoptera larvae 19.6 56 1. 75 26.5 26 1. 4 7 20.0 10 1.23 11.1 1 0.58 pupae 1.1 2 0.06 adults 2.2 2 0.06 14.7 10 0.56 Dirt<>ra Chironomidae larvae 53.3 736 22.94 55.9 215 12.12 68.9 204 25.12 88.9 32 18.60 pupae 9.8 26 0.81 17.6 15 0.85 15.6 25 3.08 33.3 4 2.33 adults 40.2 220 6.86 47.1 737 41.54 66.7 301 37.07 100.0 74 43.02 -Sim•1liidae 15.2 207 6.45 8.8 169 9.53 20.0 14 1. 73 ll.l 2 1.16 ~!is r.. Diptera 31.5 107 3.34 70.6 71 4.00 35.5 45 5.54 22.2 4 2.33 ;__ r:r ~~· ~· '1. 12.0 301 9.38 2.9 2 0.11 E'c2·~ina 9.8 53 1.65 -Chydorids 2.2 17 0.53 Diaptomus adults 7.6 246 7.67 2.9 1 0.06 nauplii ~lites 5.4 16 0.50 23.5 19 l. 07 6.7 4 0.49 11.1 7 4.07 -:--lise. aquatics 9.8 16 0.50 14.7 7 0.39 13.3 9 1.11 Mise terrestrials 47.8 109 3.40 44.1 47 2.65 35.6 42 5.17 22.2 7 4.07 Fish eggs 2.2 1 0.12 c'nj den tifi<-d A.nd 21.7 48 1.50 23.5 36 2.03 6.7 4 0.49 inanimate material .... - - 456 Table 8. 86 Mean lengths, weights, and condition factors of rainbow-steelhead fry captured by either """' electroshocking or fyke netting, 1974 brood. Mean ~ Number Length (mrn) Mean condition Location Date of fish Range Mean weight (g) factor 1974 Skagit River Aug 15 5 31-40 34.8 0.40 0.90 near Newhalem 15 6 33-36 34.2 0.32 0.80 Skagit River Jul 5 2 31-33 32.0 0.30 0.92 near Talc Mine Aug 15 11 29-39 33.2 Sep 4 24 29-44 36.0 0.53 1.06 Skagit River Jul 2 3 32 32.0 0. 33 1.01 ~ near Marblemount Aug 15 17 29-35 31.9 _.. Cascade River Jul 2 7 29-31 30.0 0. 26 0.95 Aug 9 20 31-41 32.9 0.30 0.80 Sauk River Jul 3 22 28-37 31.5 0.35 1.12 Aug 9 21 28-52 39.0 0. 72 1.10 Goodell Creek Aug 1 1 31 31 0.3 1.0 9 2 30-32 31.0 0.40 1. 35 15 7 34-44 37.7 0.57 1.03 Diobsud Creek Jul 25 2 32-·34 33.0 0.40 1.11 ~ Aug 9 11 27-33 30.7 0.26 0.92 Bacon Creek Jul 3 2 30-32 31.0 0.70 2.36 ~ 18* 5 35-39 36.8 0.44 0.88 25* 3 30-32 31.3 0.40 1. 31 """' Aug 1 3 29-31 30.3 0. 33 1.22 9 10 29-32 30.9 0.30 1. 02 *Fyke samples 15 5 30-36 32.6 net 457 -Table 8. 87 Rainbow-steelhead fry catches at Skagit Basin sampling sites using electrofisher, 1976 brood. -Skagit River at County Talc Marble-Rock-Cascade Sauk Goodell Bacon Diobsud -Date Line Mine mount port River River Creek Creek Creek 1976 -6/~6/12 6/13 -6/19 5 6/20 -6/26 -6/27 -7/3 8 ! ', 7/4 -7/10 5 1 7/11 -7/17 1 11 2 !""" 7/18 -7/24 1 2 40 5 7/25 -7/31 2 8 16 1 28 5 8/1 -8/7 20 11 27 4 30 3 1 4 8/8 -8/14 23 4 11 26 25 26 5 -8/15 -8/28 20 8 23 25 29 26 29 27 23 8/29 -9/11 33 15 29 47 31 30 25 33 28 9/12 -9/25 25 25 21 25 32 24 35 9/26 -10/9 5 5 8 5 5 10/10-10/23 12 16 38 118 29 24 34 26 10/24-11/6 27 15 25 23 30 30 45 23 27 11/7 -11/20 2 8 15 10 10 10 12 13 11/21-12/4 6 7 15 16 17 47 16 17 20 12/5 -12/11 13 10 15 30 21 63 13 12 25 12/12-12/18 10 6 34 34 19 38 9 10 36 12/19-12/25 10 3 14 16 12 33 12 12 13 12/26-1/1 1 2 3 14 24 22 13 8 11 1977 1/y--:1/8 5 6 8 20 10 11 5 1/9 -1/15 1 2 6 30 12 10 13 10 1/16 -1/22 5 9 16 8 11 10 18 -1/23 -1/29 3 3 2 21 4 6 12 7 1/30 -2/5 4 3 2 5 10 11 5 18 5 2/6 -2/12 1 .1 1 1 18 4 5 8 l 2/13 -2/19 16 2 """' 2/20 -2/26 4 11 8 2 11 1 2/27 -3/5 12 7 18 3 6 3/6 -3/12 1 13 2 6 2 5 -3/13 -3/19 1 1 7 28 1 4 3/20 -3/26 1 2 7 2 '\,; 3/27 -4/2 9 5 1 ..... 4/3 -4/9 3 2 2 4 2 5 5 2 4/10 -4/16 1 11 3 4 11 4/17 -4/23 6 5 16 2 3 3 1 4/24 -4/30 3 1 1 4 27 2 5 4 1 ~ 5/1 -5/7 1 1 10 6 3 4 1 5/8 -5/21 3 1 2 8 21 3 4 5/22 -6/4 6 1 4 14 15 9 4 2 -6/5 -6/18 1 3 4 3 10 2 1 6/19 -7/2 1 1 '· Date 1977 71~7116 7 I 17 -7 I 30 7131 -8113 8114 -8127 8128 -913 9120 -9121 10119-10122 11118-11120 12115-12120 458 Table 8.87 Rainbow-steelhead fry catches at Skagit Basin sampling sites using electrofisher, 1976 brood-- continued. Skagit River at Newhalem-Talc Marble-Rock-Cascade Sauk Goodell Bacon County Mine mount port River River Creek Creek Line 4 1 4 5 2 1 2 1 2 1 1 2 2 1 1 Note: Dash (-) signifies catch was zero. Blank signifies sampling not conducted. - Diobsud Creek ~ ,_, - - ~. ~-~· 459 , ... Table 8.88 Rainbow-steelhead fry catches at Skagit Basin sampling sites using electrofisher. 1977 brood. '""" Skagit River at County Talc Marble-Rock-Cascade Sauk Goodell Bacon Diobsud Date Line. Mine mount port River River Creek Creek Creek 1977 ·-5/22 -6/4 6/5 -6/18 3 1 2 8 7 8 6/19 -7/2 14 3 25 3 10 3 7/3 -7/16 12 5 57 2 24 1 7/17 -7/30 59 40 39 92 35 33 7 9 9 7/31 -8/13 63 25 27 127 27 30 13 13 12 8/14 -8/27 69 30 25 29 28 37 14 14 13 8/28 -9/3 75 30 26 69 41 36 9/20 -9/21 59 38 41 43 35 41 10/19-10/22 64 42 35 24 41 34 -11/18-11/20 34 30 29 29 34 35 12/15-12/20 42 23 11 15 11 16 1978 -1/11 21 2 1/18 -1/22 19 25 4 20 13 2/1 22 1 2/10 6 ; ~ 2/17 2/24 -2/26 7 4 3 22 18 3/3 8 3/10 2 3/17 36 3/24 -3/27 13 2 .~ 3/31 34 4/7 26 2 4/13 24 4/21 4 5. 4/24 -4/25 13 3 5/2 23 1 5/9 -5/10 8 5/16 -5/17 9 5/23 11 6/1 2 1 2 ~ 6/6 25 36 6/13 2 6/20 7 7 6/27 3 5 - Note: Dash (-) signifies catch was zero. Blank signifies sampling not conducted. '""' (f) 0::: w I-w L -_J _J -L z -:c: I- C> z: w _J >- 0::: LJ_ z a: w :L: 460 80 LEGEND -e-SKAGIT (MARBLEMOUNT) 70 -A-CASCADE -+-SAUK so 50 40 30~----~----~~----L-----~----~----~~ JUL AUG SEP 1976 OCT NOV DEC Fig. 8.60 Mean lengths of Skagit, Cascade, and Sauk rainbow-steelhead fry taken by electrofishing, 1976 brood. - - ~~ ~ """ ~ ~ 461 ..... 5 LEGEND -6--SKAGIT (MARBLEMOUNT) CJ) ::L 4 ---A-CASCADE -CI 0::: -+-SAUK CJ z ,_ ~ f-3 ::r:: CJ ~ w ~ l f-w 2 3: >- ~--0:::: LL.. z CI w 1 ::L - 0 JUL AUG SEP OCT NOV DEC 1976 """' Fig, 8. 61 MeAn wet weights of Skagit, Cascade, and Saul< '""" rRinhow-stPP]hPRO f ry trJkPn hy PIP!'! rot ishinv., !9 lh hrood. 0::::: a I-u CI lJ.... z 0 -I--D z 0 u >- 0::::: LL z CI w L: Fig. 8. 62 t.soo 1.300 t.too .900 .700 462 LEGEND -& SKAGIT (MARBLEMOUNT) -A- -+- JUL CASCADE SAUK AUG SEP 1976 OCT NOV Mean condition factors of Skagit, Cascade, and Sauk rainbow-steelhead fry taken by electrofishing, 1976 brood. ~\ ~ - ~- - ~ DEC l: - - 463 November and December, indicating that perhaps with favorable temperature conditions, Skagit fry were able to "catch up" with fry from the Sauk and Cascade rivers. Fry from the 1976 brood continued to be present at all sites into July, 1977, and at some through December, 1977 (Tables 8.89-8.97). Sample sizes of this brood in 1977 were usually low, suggestiPg reduced densities due to emigration and mortality, decreased susceptibility to electrofish- ing, or both. At most sites, there was a general increase in mean' lengths and weights with time, but general increases to mean condition factor were not noticeable. Fry of the 1977 brood began to emerge earlier in the season than the 1976 brood at all sites except the Rockport Station on the Skagit River and Goodell Creek (Tables 8.87 and 8.88), and started increasing in mean length, weight, and condition factor earlier at most sites. Like the 1976 brood, rainbow-steelhead fry of the 1977 hrood showed a brief period of little change in mean size and condition after first emergence except for condition factor at the Harblernount Station (Figs. 8.63-8.68). These figures were constructed for fry samples larger than one. This early period of little change in size may be due in part to a predominance of freshly emerging fry from the gravel over older, frowing fry during this period. The duration and distinctness of this period appeared to be less in 1977 than in previous years. This level period was followed by a period of more rapid increase of mean size and condition until about October after which there was a plateau through the end of the year. Unlike the 1976-1977 brood of coho fry, the 1977 brood of rainbow- steelhead fry from the Skagit River stations showed no consistent difference in size and condition between upstream and downstream stations (Figs. 8.63-8.65). The samples of the 1977 brood from the Skagit River at tlarblemount (Figs. 8.66-8.68) had distinctly larger size and condition after the initial level period compared to year-0 fry from the previous year (Figs. 8.60, 8.61, and 8.62) and in relation to samples of the Cascade and Sauk rivers in 1977. As in the 1976-1977 brood of coho fry, i11creased tem- peratures during incubation, earlier emergence, warmer temperatures during the early rearing period, and decreased flow fluctuations in 1977 compared to 1976 may have improved the rearing qu<'llity of the Harhlemount area in 1977. Despite warmer ~emperatures in the Cascade and Sauk in the 1977 season, samples of year-0 rainbow-steelhead from these two Skapit tributaries _had mean lengths. weights, and conrlition factors similar to those of the previous year. Turbidity levels were higher in these two rivers, especially the Sauk River, durin~ the period June and November in 1977 compared to 1976 (Tables 3.8 and 3,9) and may have decreased the benthic standing crop and feeding efficiency of the fry. Rainbow-steelhead fry of the 1977 brood from Goodell, BReon, and Diobsud c:reeks were sampled for size and condition until mid-Au~ust, 1977 (Tables 3.95-8.97), hut too few sa~ples were availRhle to draw inferences. Table 8.89 Mean lengths, weights, and condition factors of rainbow-steelhead fry captured by electroshocking at the County Line Station in 1977. 1976 brood 1977 brood Mean Mean Mean Mean Mean Number length weight condition Number length weight Date of fry (TIUU) (g) factor of fry (mm) (g) - January 11 1 51.0 1.410 1.063 0 26 3 62.3 2.883 1.145 0 February 8 1 75.0 4.980 1.180 0 25 4 65.5 3.445 1.159 0 March 8 1 70.0 4.230 1. 233 0 15 1 65.0 3.190 1.162 0 April 27 3 68.7 3. 513 1.081 0 May 12 3 78.0 5.393 1.137 0 June 7 1 72.0 4.260 1.141 3 31.7 0.233 22 0 9 35.3 0.376 July 7 6 79.3 7.302 1.139 10 38.0 0.528 19 2 53.0 1.660 1.115 23 35.8 0.376 August 3 ·1 55.0 1.560 0.938 24 37.4 0.484 16 0 23 37.1 0.473 29 0 24 38.1 0.503 September 21 0 25 48.7 1.310 October 22 5 75.6 5.004 1.147 20 59.6 2.537 November 20 0 24 57. 3 . 2.075 December 20 5 75.6 4.268 0.988 20 58.0 2.142 Mean condition factor .j:>- 0\ .j:>- o. 722 0.834 0.925 o. 781 0.862 0.852 0.894 1.103 1.170 1. 066 1.055 J Table 8.90 Mean lengths. weights, and condition factors of rainbow-steeltte<Hl fry captured by electroshocking at ~1e Talc Mine Station in 1977. 1976 brood 1977 brood Mean He an Mean Mean Mean Number length weight condition Number length weight Date of fry (mm) (g) factor of fry (mm) (g) January 11 2 58.5 2.140 1. 069 0 February 9 1 75.0 4. 720 1.119 0 April 13 1 47.0 .930 .896 0 22 6 70.5 4.507 1. 209 0 26 1 73.0 4.540 1.167 0 May 12 1 68.0 3. 700 1.177 (j June 7 3 75.3 5.053 1.148 1· 38.0 0.450 July 7 1 81.0 5.270 . 992 0 19 0 26 34.6 0.350 August 3 0 25 35.9 0.441 16 0 26 38.8 0.631 29 0 25 43.0 0.793 September 21 0 25 44.7 0.998 October 20 0 25 52.0 1.543 November 20 0 20 54.9 1. 667 December 20 0 13 51.7 1.488 i Mean condition factor ~ 0.820 (71 V1 0.811 0.906 1.029 0. 975 1. 053 1.081 0.986 1.044 Date January February March April May June July August September October December 4 19 26 9 15 29 Table 8.91 Mean lengths, weights, and condition factors of rainbow-steelhead fry captured by electroshocking at the Marblemount Station in 1977. 1976 brood 1977 brood Mean Mean Mean Mean Mean Number length weight condition Number length weight of fry (rnm) (g) factor of fry (rnm) (g) 4 55.0 1.673 1.003 0 5 55.2 1.900 1.138 0 3 51.7 1.573 1.134 0 1 47.0 1.030 o. 992 0 1 50.0 1.160 0.928 0 9 63.9 3.439 1.259 0 20 5 73.2 3.944 0.979 0 26 1 63.0 2.420 0.968 0 12 2 62.0 3.390 1.268 0 6 4 66.8 3.638 1.223 1 31.0 0.200 7 4 79 .·3 6.417 1.118 5 32.6 0.270 19 2 84.5 7.440 1.233 23 33.6 0.319 2 3 74.7 5.687 1.259 24 37.7 0.563 16 0 25 41.7 0.881 29 0 25 43.6 0.865 20 0 25 52.7 1. 578 19 1 71.0 4.390 1.227 24 58.3 2.262 15 0 11 52.5 1.539 Mean condition factor .&:-- a- Q'\ o. 671 o. 779 0.810 0. 977 1.143 0.992 1. 051 1.119 1. 028 Date January February April May June July August . ] 1 Table 8.92 Mean lenp,hts, weights, and condition factors of rainhow-stee1head fry captured by electroshocking at the Rockport Station in 1977. 1976 brood 1977 brood Mean Mean Mean Mean Mean Number length weight condition Number length weight of fry (mm) (g) factor of fry (mm) (g) 4 3 54.0 1. 747 1.100 0 11 6' 57.8 2.038 1.046 0 19 6 60.0 2.687 1.217 0 20 3 50.3 1. 387 1.086 0 26 2 50.0 1.625 1.247 0 8 1 54.0 2.050 1.302 0 26 4 64.0 3.233 1.166 0 24 4 75.5 5.220 1.157 0 6 0 8 31.5 0.229 21 1 77.0 6.420 1.406 25 36.7 0.429 5 1 46.0 1.040 1.068 23 36.8 0.447 19 2 65.0 3.690 1.091 24 32.8 0.273 2 0 28 33.1 0.327 16 0 25 37.7 0.496 September 1 0 25 37.8 0.552 20 0 25 47.8 1.198 October 19 0 24 53.5 1.906 November 18 0 19 54.1 1.662 December 15 122.0 19.830 1.092 5 57.0 2.264 Mean condition factor .p. 0\ . -...J 0.717 0.860 0.850 0.754 0.890 0.883 1. 012 1.035 1.214 1.036 1.194 Date January 5 13 19 25 February 2 9 17 23 March 1 7 14 21 29 April 11 18 25 May 2 9 24 June 6 July 5 20 August 2 15 29 Table 8.93 Mean lengths, weights, and condition factors of rainbow-steelhead fry captured by electroshocking at Cascade River in 1977. 12Z6 brood_ ] 9_ zz bi:QQd Mean Mean Mean Mean Mean Number length weight condition Number length weight of fry (mm) (g) factor of fry (mm) (g) 10 49.9 1.350 0.981 0 10 50.0 1.402 1.054 0 10 45.0 1. 097 1.149 0 10 46.7 1.101 1.015 0 5 52.6 1. 598 1.077 0 10 47.3 1. 319 1.165 0 10 48.0 1.301 1.061 0 5 49.4 1. 448 1.146 0 7 47.7 1.213 1.085 0 13 57.7 2.491 1.148 0 7 53.4 1.800 1.114 0 1 53.0 1.600 1.075 0 5 49.2 1.220 0.973 0 5 56.6 2.248 1.178 0 10 51.8 1.559 1.079 0 10 51.8 1.367 0.972 0 5 55.8 2.038 1.157 0 5 58.4 2.572 1. 235 0 11 59.1 2.552 1.174 0 3 55.0 1.883 1.115 7 32.0 0.246 5 69.0 3.760 1.102 2 32.5 0.260 2 85.0 7.995 1. 298 24 33.5 0.308 2 64.5 2.605 0. 971 23 35.2 0.399 2 82.0 5.615 1.013 24 36.0 0.418 0 25 41.0 0.636 Mean condition factor .t:'- 0\ o:> 0.751 0.757 0. 773 0.871 0.873 0.897 Table g.93 Mean lengths, weights, and condition factors of ra1nhow-steelhead fry captured by electroshocking at Cascade River in 1977 -continued 1976 brood 1977 brood Mean Mean Mean Mean Mean Number length weight condition Number length weight Date of fry lr~1m) (g) factor of fry (mm) (g) Septlember 20 1 82 5.670 1.028 24 46.7 1.118 October 19 0 25 48.9 1.193 November 18 0 25 50.6 1. 375 December 15 0 6 51.3 1.487 Mean condition factor ~ 1.059 0\ \0 1.005 1.035 0.981 Table 8.94 Date January 5 13 20 25 February 2 9 17 23 March 1 21 April 11 18 25 May 2 9 24 June 6 21 July 5 20 August 2 15 29 Mean lengths, weights, and condition factors of rainbow-steelhead fry captured by electroshocking at Sauk River in 1977. 1976 brood 1977 brood Mean Mean Mean Mean Mean Number length weight condition Number length weight of fry (mrn) (g) factor of fry (mm) (g) 5 46.6 1.132 1.109 0 10 59.6 2.612 1.185 0 8 51.8 1. 608 1.121 0 4 48.5 1.282 1. 091 0 5 47.2 1.198 1. 069 0 4 49.3 1.433 1.121 0 2 54.5 1. 760 1.087 0 5 54.6 1. 974 1.108 0 2 53.5 1. 885 1.222 0 2. 53.0 1. 700 1. 031 0 3 59.0 2.350 1.141 0 2 56.5 1.860 1. 012 0 2 61.0 2.070 0.886 0 1 69.0 3.220 0.980 0 5 65.6 3.586 1. 234 0 4 63.7 3.037 1.155 0 5 67.2 3.600 1.186 8 31.5 0.250 1 68.0 3.880 1.234 10 33.6 0.308 2 72.5 4.295 1.130 24 37.1 0.469 0 24 35.8 0.417 0 25 38.9 0.659 0 25 42.6 0.766 0 24 37.4 0. 511 1 Mean condition factor ..,... -....J 0 0.793 0.785 0.869 0.822 1. 037 0.906 0.877 Table 8.94 Date September 20 October 19 November 18 December 15 l J l --1 Mean lengths, weights, and cundition factors of rainbow-steelhead fry captured by electroshocking at Sauk River in 1977 -continued. 1976 brood 1977 brood Mean Mean Mean Mean Mean Number length weight condition Number length weight of fry (mm) (g) factor of fry (mm) (g) 0 25 42.7 0.789 1 76.0 4.250 0. 968 23 50.2 1.407 1 92.0 7.100 0.912 25 53.2 1.616 0 11 53.5 1.851 Mean condition factor ~ "-J 1-' 0.945 1.084 1.013 1.126 Table 8.95 Date January 5 13 20 25 February 4 9 23 March 1 8 14 22 April 4 11 20 25 May 2 9 26 June 7 21 July 5 20 August 2 15 J Mean lengths, weights, and c~ndition factors of rainbow-steelhead fry captured by electroshocking at Goodell Creek in 1977. 1976 brood 1977 brood Mean Mean Mean Mean Mean Number length weight condition Number length weight of fry (nun} (g2 factor of fry (mm) {g) 10 46.0 1.028 1. 016 0 10 51.9 1.558 1.072 0 10 43.7 0.852 1. 005 0 6 47.5 1.217 1.082 0 5 53.0 1. 788 1.125 0 5 48.4 1.254 1.011 0 2 48.5 1.240 1. 069 0 10 49.3 "1. 207 0.978 0 6 48.5 1. 308 1.065 0 10 50.2 1. 385 1.071 0 7 54.3 2.171 1.123 0 5 43.8 1. 002 1.138 0 4 45.3 1.083 1.164 0 3 62.0 2.837 1.182 0 5 51.4 1. 366 0.954 0 3 47.3 1.213 1.135 0 3 47.3 1.240 1.129 0 4 79.8 5.950 1.016 0 2 58.5 1. 990 0.994 0 0 3 37.3 0.503 0 1 43.0 0.690 2 75.0 5.100 1.186 6 39.3 0.701 0 10 35.4 0.523 0 10 37.6 0.504 _] Mean condition factor p. ...... N 0.885 0.868 1.077 1. 029 0.863 J ] Table 8.96 Oat~' --- January 5 13 20 25 February 4 9 23 March 1 8 14 29 April 4 11 20 25 Hay 2 9 26 June 7 July 5 20 August 2 15 1 J Mean lengths, weights, and condition factors of r<dnbmv-steelhead fry captured by electroshocking at Bacon Creek in 1977. 1976 brood 1977 brood He an He an Mean Mean Mean Number . length weight condition Number length weight of frv (mm) (g) factor of fry (mm) (g) 5 47.8 1.148 1.033 0 10 5.1.9 1.661 1.016 0 9 50.4 1.399 1.082 0 10 47.7 1.266 1.085 0 5 46.8 1.126 1. 027 0 5 48.6 1. 278 1.100 0 5 52.8 1. 556 1.029 0 3 47.7 1. 310 1.165 0 2 49.0 1.245 L058 0 1 61.0 2.260 0.996 0 1 47.0 1.100 1.059 0 5 49.2 1.268 1.056 0 5 59.6 2.206 1.036 0 3 45.7 0. 913 0.918 0 4 54.0 1.675 1. 041 0 4 57.3 2.240 1.133 0 4 51.5 1.530 1.112 0 2 65.0 2.845 1. 036 0 1 71.0 3.380 0.944 0 1 60.0 2.580 1.194 0 1 78.0 5.370 1.132 9 40.4 0.708 0 10 34.8 0.488 1 56.0 2.090 1.190 9 40.7 o. 716 ., J Mean condition factor ~ ""..! (..J 0.960 0.992 0.996 ~--- Table 8.97 Number Date of fry January 13 10 20 10 25 7 February 4 5 9 4 23 1 March 1 6 8 5 14 4 23 2 April 4 2 20 1 25 1 May 2 1 July 5 1 20 1 August 2 0 15 0 J Mean lengths, weights, and condition factors of rainbow-steelhead fry captured by electroshocking ~t Diobsud Creek in 1977. 1976 brood 1977 brood Mean Mean Mean Mean Mean length weight condition Number length weight (mm) (g) factor of fry (mm) (g) 43.7 0 .. 868 0.983 0 46.9 1. 333 1.034 0 50.4 1.390 1.056 0 48.6 1.282 1.083 0 45.0 1.008 1.085 0 44.0 0.940 1.103 0 47.0 . 1.116 1. 001 0 59.6 2.098 0.917 0 50.3 1.290 0.995 0 67.5 3.794 1.046 0 45.0 1.015 1.027 0 63.0 2. 620 1.048 0 65.0 2.780 -1.012 0 51.0 1.170 .882 0 77.0 5.200 1.139 0 74.0 4.520 1.115 9 33.1 0.271 10 32.5 0.298 10 35.1 0.384 Mean condition factor +:- '-.I +:- 0.747 0.861 0.849 r ,... -! ........ L: L: ~~ '-" J: I-;--o z w _j -z a: w L: - -~ 475 70 LEGEND -5-COUNTY LINE 60 -++--TALC MINE -e-MARBLEMOUNT ....... ROCKPORT 50 40 30 ~------L-----~----~L-----~------L-----~--~ JUN JUL AUG SEP OCT NOV 1977 Fig. 8.63 Mean lengths of rninbow-stcclhcad fry taken hv electrofishing from four Skagit River stations. 1977 hrood. DEC ,......, C) "-' 1- 5 ........ w 3: z a: w l:: 476 4.00 LEGEND ~ COUNTY LINE 3.00 ~ TALC MINE -e-MARBLEMOUNT -+-ROCKPORT 2.00 t.oo JUN JUL AUG SEP OCT NOV 1977 Fig. 8.64 Mean we.ights of rainbow-steelhead fry taken by electrofishing from four Skagit River stations, 1977 brood. - ~ ~- ~ - DEC - - - - a::: 0 ~ u a: LL.. z Cl ~ 1- \--1 0 z 0 u z (I w :L 477 1-300~--------~--------------------------------~ 1.100 .sao LEGEND -e-COUNTY LINE .700 --*"" TALC MHJ E -e-MARBLEMOUNT -$-ROCKPORT .soo~------~----~----~------~----~----~----_j JUN Fig. 8, 65 JUL AUG SEP OCT NOV 1977 Mean condition factors of rainbow-steelhead fry taken by electrofishing. from four Skagit River stations, 1977 brood. DEC 70 60 -~ ~ -...J :I: 1- C> 50 z w _J z a: w E 40 478 LEDENQ -e-SKAGIT (t-1ARBLEMOUNT) ....._ Cl\SCADE 1977 Fig. 8,66 Mean lengths of Skagit, Cascade, and Sauk rainbow- steelhead fry taken by electrofishing, 1977 brood. -· - - - - 1--1 w ::s: z a: w :I: 479 4.00~--------------------------------------------~ LEGEND -6-SKAGIT (MARBLH10UNT) 3.00 ~ CASCADE -+-SAUK JUN JUL AUG 1977 SEP OCT NOV DEC Fig. 8.67 Mean weights of Skagit, Cascade, and Sauk rainbow-· steelhead fry taken by electrofishirig, 1977 brood. cr.: 0 I-u a: IJ... z 0 1-4 1-- 1-4 C) z 0 u z a: w L 480 1.3QOT---------------------------------------------~ 1 .too .sao • '700 LEGEND -e-SKAC-,JT (MARBLEMOUNT ........_ CASCADE -+-SfUK .soo~--J-U-N~--J-UL--~--A-U_G __ ~_S_E_P--~-OC-T--~-N-O-V--~-0-E-C~ 1977 Fig. 8.68 Mean condition factors of Skagit, Cascade, and Sauk - - rainbow-steelhead fry taken by electrofishing, ~ 1977 brood. - - f' ''"" ,·- - - - - 481 8.1.4.15 Rainbow-Steelhead Trout Fry Diet. The stomach contents of 283 rainbow-steelhead fry of the 1976 brood were examined: 101 from the upper three Skagit stations; 72 from the lower two Skagit stations; 56 from the Cascade River; and 54 from the Sauk River. The results of the analysis of these stomach contents are presented in Tables 8.98-8.101. Chironomid larvae were the most numerous item in the diet of the newly emerged rainbow-steelhead fry during August and September. However, larger prey items, especially f.phemeroptera nymphs, became more important as the fry grew larger. Up through ~ay or June, 1977, the percent occurrence of chironomids showed a general decline in all four areas; the upper three Skagit stations, the lower two Skagit stations, the Cascade Station, and the Sauk Station. Ephemeroptera nymphs were the most important component by numbers of the diet in samples from all areas except the Sauk River summed over the whole period that the 1976 brood was available (Table 8.102). Zooplankters were found only in the upper Skagit stations in Septem- ber, December, and January. They contributed by number only 2.31 percent of the diet from samples from the upper three Skagit stations. While one small fish was found in the stomach of a rainbow-steelhead fry caught at the Concrete Station in Septemher, 1976, and one salmonid egg was found in a sample from the Concrete Station in January (Table 8.99), rainbow-steelhead fry of this size appeared to lack piscivorous tendencies. Although the terrestrial insect order, Homoptera, represented in the fry diet by aphids and leaf hoppers, was a noticeable component of stomach contents in fry samples from the Concrete Station in October, 1976, (Table 8.99), the Cascade Station in September, 1976 (Table 8.100), and the Sauk Station in May, 1977 (Table 8.101), the contribution of homopterans by numbers to the over-all diet was slight (Table 8.102). The large number in the "unidentified and inanimate material" category from the December, 1976, sample from the upper three Skagit sites (Table 8.98) were mainly pebbles and algae in fry from the Marblemount and County Line stations. 8.2 Fry Stranding 8.2.1 Introduction The Skagit and Baker rivers differ from other rivers in the watershed because of power-production-related flow fluctuations introduced at Gorge Powerhouse and Baker Dam. Flow fluctuations have resulted in salmonid fry stranding mortalities in previous years. The major concern is over chinook fry, although pink, chum, and coho salmon, and steelhead trout have been affected at times. WDF conducted investigations on salmon fry stranding in the Skagit River in March and April 1970 (Thompson 1970) to determine whether flow changes resulting from power production caused stranding, and if so, what measures were necessary to alleviate the problem. These studies resulted in the recommendation that a minimum flow of 2~800 cfs be maintained in Table 8.98 Rainbow-steelhead fry stomach contents, 1976 brood, upper three Skagit sites. Date Aug. '76 Sept. I 7 Oct. '76 Dpc 1 76 Jan '77 Location and County Line 8 County Line 5 Talc Mine 5 County Line 5 Talc Mine 4 sample size M.arblemount 4 Talc Mine 8 Marblemount 5 Talc Mine 4 Marblemount 4 Marblemount 10 Marblemount 5 % Empty 0 4.4 0 Z.l Freq. Total % Freq. Total % Freq. Total % Freq. Total % Freq. Total % occur. no. occur. occur. no. occur. occur. no. occur. occur, no. occur. occur. no. occur. Collembo1a 10.0 1 .36 28.6 17 6.51 Psoptera 9.1 2 .43 Homoptera 8.3 1 .43 22.7 8 1. 74 20.0 2 .72 Ephemeroptera nymphs 58.3 21 9.09 18.2 5 1.09 10.0 1 .]6 23.1 3 1.52 100.0 94 36.02 adults 4.5 2 .43 Plecoptera nymphs 50.0 8 3. 46 50.0 26 5.65 20.0 2 .72 57.1 15 5.75 adults 18.2 10 2.17 Trichoptera larvae 18.2 9 1. 96 20.0 3 1.08 23.1 6 3.03 100.0 17 6.51 pupae 4.5 1 .22 .,... adults 4.5 1 .22 7.7 1 .51 14.3 1 .38 CXl Diptera N Chironomidae larvae 58.3 169 73.16 68.2 31 6.74 40.0 5 1.80 23.1 5 2.53 85.7 68 26.05 pupae 8.3 1 .43 13.6 12 2.61 10.0 1 . 36 adults 58.3 27 11.69 59.1 242 52.61 60.0 126 45.32 14.3 1 .38 Simuliidae 8.3 1 .43 71.4 16 6.90 Misc. Diptera 45.5 :!8 6.09 70.0 32 11.51 7.7 1 .51 14.3 1 .38 Daphnia Bosmina 23.1 59 29.8 Chydorids 14.3 1 .38 Diaptorrrus adults 9.1 4 .87 15.4 9 4.55 -nauplii Mites 13.6 3 .65 14.3 1 .38 Misc. aquatics 8.3 3 l. 30 4.5 1 .22 10.0 53 19.06 7.7 1 .51 42.9 8 3.07 Misc. terrestrials 59.0 60 13.05 30.0 4 1. 4.4 53.8 12 6.06 18.6 17 6.51 Fish Unidentified and 27.3 8 l. 74 50.0 48 17.27 69.2 100 50.51 28.6 2 .77 inanimate material -------------------------------- ] , ... -~ .... ... } } j ) ) ) l l ) • 1 ... Table 8.98 Rainbow-steelhead. fry stomach contents, 1976 brood, upper three Skagit si tee·-continued. Date Feb. '77 March '77 April '76 May '77 June '77 Location and County Line 3 Talc Mine 1 County Line 4 County Line 6 Talc Mine 2 sample size Talc Mine 3 Talc Mine 2 Talc Mine 1 Marblemount 5 Marblemount 2 Marblemount 5 % Empty 0 0 Freq. Total % Freq. Total % Freq. Total % Freq. Total i. Freq. Total % occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. Collembola 28.6 2 1.64 Psoptera 28.6 2 1.64 Homoptera 16.7 1 .98 16.7 2 .92 14.3 1 .82. Ephemeroptera nymphs 100.0 874 68.5 100.0 1 100.0 100.0 45 44.12 66.7 80 36.70 100.0 46 37.70 aciults 16.7 1 . 98 8.3 3 1.38 Plecoptera nymphs 75.0 116 9.09 83.3 44 43.14 91.7 88 40.37 28.6 5 4.10 a-dults 8.3 1 • 46 Trichoptera larvae 25.0 2 .16 16.7 1 .98 16.7 4 1.83 28.6 2 1.64 pupae ~ adults 00 w Diptera Chironomidae larvae 87.5 86 6.74 33.3 2 1. 96 16.7 2 .92 42.9 3 2.46 pupae adults 25.0 3 1.38 57.1 22 18.03 S imuliidae 62.5 188 14.73 28.6 2 1.64 Misc. Diptera 12.5 1 .08 16.7 1 .98 50.0 15 6.88 57.1 5 4.10 Daphnia Bosmina Chydorids Diaptomu.s adults ·nauplii ~lites 28.6 6 4.92 ~lis c. aquatics 25.0 4 .31 8.3 1 .46 57.1 4 3.28 His c. tPrrestrials 37.5 5 • 39 66.7 5 4.90 33.3 6 2.75 71.4 8 6.56 Fish Unidentified and inanimate material 33.3 2 1. 96 25.0 7 3.21 42.9 14 11.48 Table 8.99 Rainbow-steelhead fry stomach contents, 1976 brood, lower two Skagit sites. Date Aug. '76 sent. 'Z6 Oct. 'Zfi Nov. '76 .Ian. 'ZZ Location and Rockport 4 Rockport 10 Rockport 5 Rockport 4 Rockport 10 sample size Concrete 5 Concrete 8 Concrete 4 % Empty 0 0 0 0 Freq. Total % Freq. Total % Freq. Total % Freq. Total % Freq. Total % occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur~ occur. no. occur. Collembola 11.1 2 2. 70 5.6 1 .28 10,0 5 l. 42 Psoptera 22.2 2 .18 llomoptera 5.6 1 .28 55.6 21 1. 90 Ephemeroptera nymphs 33.3 4 5.41 61.1 28 adults 7. 98 44.4 15 1.36 90.0 lOS 29.83 Plecoptera nymphs 11.1 1 1. 35 11.1 4 1.14 77.8 9 .81 25.0 1 7.69 60.0 16 4.55 adults 11.1 2 .57 22.2 4 .36 20.0 2 .57 Trichoptera larvae 44.4 7 9.46 11.1 4 1.14 55.6 21 1.90 so.o 9 2.56 ~ 00 pupae ~ adults 5.6 1 .28 44.4 31 2.81 10.0 1 .28 Diptera Chironomidae larvae 55.6 11 14.86 66.7 162 46.15 55.6 16 1.45 25.0 1 7.69 90.0 181 51.42 pupae 22.2 4 5.41 16.7 5 1.42 22.2 5 .45 adults 55.6 20 27.03 55.6 83 23.65 88.9 836 75.66 Slmulildae 11.1 1 1. 35 22.2 6 1.71 70.0 28 7.95 Misc. Diptera 33.3 3 4.05 11.1 3 .as 66.7 49 4.43 25.0 1 7.69 30.0 3 .85 Daphnia 11.1 16 Bosmina 21.62 11.1 9 2.56 Chydorids Diaptomus adults nauplii Mites 22.2 4 5.41 22.2 9 2.56 11.1 2 .18 Misc. aquatics 11.1 1 1. 35 11.1 2 .57 22.2 3 .27 25.0 1 7.69 Misc. terrestrials 55.6 27 7.69 66.7 10 .90 50.0 4 30.77 10.0 1 .28 Fish 5.6 1 .28 10.0 1 (egg).28 Unidentified and 16.7 3 .85 88.9 81 7.33 75.0 5 38.46 inanimate material J '~ 485 ~ Table 8.99 Rainbow-steel head fry stomach contents, 1976 brood, lower two Skagit sites-continued. Date Feb. '77 Ma:z: '77 June '77 Oct. '77 Location and Rockport 5 Rockport 4 Rockport 1 Concrete 2 sample size Concrete 10 % Empty 0 14 0 ~ Freq. Total % Freq. Total r. Freq. Total % Freq. Total % occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. Collembola Psoptera 100.0 18 9.42 Homoptera 100.0 86 45.03 Ephemeroptera nymphs 100.0 654 77.95 75.0 38 43.68 100.0 183 91.50 adults 50.0 2 1.05 Plecoptera nymphs 100.0 58 6.91 8.3 1 1.15 100.0 10 5.00 , .. , adults 50.0 7 3.66 Trichoptera larvae 40.0 10 1.19 75.0 24 27.59 50.0 2 1.05 pupae adults 100.0 5 2.62 Diptera Chironomidae larvae 100.0 28 3.34 8.3 1 1.15 100.0 2 1.00 pupae adults 100.0 23 12.04 s j '""'' j J .. ,. 1.00.0 85 lO.J J 100.0 5 2.50 Misc. Diptera 20.0 1 .12 16.7 4 4.60 100.0 32 16.75 [)r;phnia. T?ncmino Clrydorlds Diaptomus adults naup11i ~ Hf t"" Mise. aquatics 40.0 2 .24 16.7 2 2.30 50.0 1 .52 Misc. terrestrl.nls 50.0 11 12.64 100.0 14 7.32 Flo;h 8.3 1 1.15 ~ Unidentified and 20.0 1 .12 33.3 5 5.75 50.0 1 .52 inanimate material """' - Table 8;100 Rainbow-steelhead fry stomach contents, 1976 brood, Cascade River. Date Aug. '76 Sellt• '2!2 Oct. '16 Dec '16 Ian '11 Location and Cascade 2 Cascade 11 Cascade 10 Cascade 5 Cascade 5 sample size 7. Empty 0 ~--D_ Freq, Total i: Freq. Total i: Freq. Total i: Freq. Total % Freq. Total % occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. Co11embola 27.3 7 2.50 Psoptera 18.2 3 '1. 07 Homoptera 54.5 14 5.00 Ephemeroptera nymphs 50.0 1 1.23 '45.5 10 3.57 44.4 5 1.61 100.0 19 40.43 100.0 205 58.24 adults Plecoptera nymphs 11.1 2 • 65 80.0 8 17.02 100.0 70 19.89 adults 9.1 3 1.07 Trichoptera larvae 9.1 1 .36 11.1 1 .32 60.0 3 6.38 40.0 3 .85 .r;- CD pupae 0'1 adults Diptera Chironomidae larvae 100.0 181 64.64 44.4 18 5.81 80.0 11 23.40 60.0 55 15.63 pupae· 100.0 3 3.70 27.3 6 2.14 33.3 11 3.55 adults 100.0 76 93.83 . 90.9 31 11.07 66.7 238 76.77 Simuliidne 9.1 2 .72 20.0 1 2.13 40.0 2 .57 Misc. Diptera 50.0 1 1. 23 45.5 6 2.14 44.4 23 7.42 40.0 2 .57 Daphnia Bosmina Chydorids Diaptomus adults nauplii Mites 11.1 1 .32 20.0 1 2.13 Misc. aquatics 9.1 1 .36 11.1 1 .32 20.0 1 2.13 20.0 1 .28 Misc. terrestrials 45.5 12 4.29 55.6 7 2.26 20.0 1 2.13 80.0 5 1. 42 Fish Unidentified and 18.2 3 1. 07 22.2 3 inanimate material .97 40.0 2 4.26 40.0 9 2.56 J } ·-,~ 487 .... Table 8.100 Rainbow-steelhead fry stomach contents, 1976 brood, Cascade River -continued. Date Feb. '77 March '77 A!:!ril '77 Ma:t 'ZZ Location and Cascade 4 Cascade 5 Cascade 4 Cascade 10 sample size -% Empty 11req. 'fotal % Frcq. l'otal % Frcq. Total % Freq. Total % occur. no. occur. occur, no. occur. occur. no. occur. occur. no. occur. -Collembola 11.1 1 .30 Psoptera r Homoptera Ephemeroptera nymphs 75.0 12 54.55 40.0 2 33.33 25.0 15 26.32 77 .a 275 82.58 ,_ adults Plecoptera nymphs so. 0 3 13.64 40.0 2 33.33 25.0 3 5.26 66.7. 10 3.00 adults Trichoptera larvae 75.0 3 5.26 33.3 7 2.10 pupae adults lliptera -Chironomidae larvae 25.0 1 4.55 75.0 17 29.82 66.7 14 4.20 pupae adults 50.0 8 14.04 11.1 3 .90 Slmuliidae 20.0 1 16.67 25.0 1 1. 75 .''~ Misc. Diptera 25.0 5 8. 77 33.3 4 1.20 Daphnia Bosmina Chydorids !""' Diaptomua adults nauplii Mites 25.0 1 1. 75 11.1 1 .30 Misc. aquatics so.o 2 9.09 Misc. terrestrials 20.0 1 16.67 6q.7 9 2.70 Fish Unidentified and 75.0 4 18.18 25.0 4 7.02 44.4 9 2. 70 inanimate material \. Table. 8.101 Rainbow-steelhead fry stomach contents, 1976 brood, Sauk River. Date Aug 1 16 __se!lL---~16. -~-.~~ Oct 'Z6 Dec '16 Ian '22 Location and Sauk 5 Sauk 10 Sauk 5 Sauk 5 Sauk 5 sample size % Empty Q Freq. Totnl % Freq. Total % Freq. Total % Freq. Total % Freq. Total % occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. occur. no, occur. Co11embola Psoptera Homoptera 10.0 1 .28 20.0 1 • 62 Ephemeroptera ·nymphs 400 4 23.53 50.0 11 3.05 20.0 2 1. 24 60.0 5 10.64 100.0 135 54.88 adults Plecoptera nymphs 20.0 1 5.~8 20.0 4 1.11 40.0 2 1. 24 100.0 24 51.06 100.0 65 26.42 adults Trichoptera larvae 20.0 1 5.88 20.0 5 1.39 80.0 13 8.07 80.0 6 12.77 40.0 3 1. 22 ~ pupae 00 adults 20.0 1 .62 OJ Dlptera Chironomidae larvae 60.0 8 47.06 100.0 310 85.87 100.0 14 8.70 60.0 8 17.02 100.0 27 10.98 pupae 20.0 6 1. 66 60.0 15 9.32 adults 20.0 1 5.88 40.0 13 3.60 80.0 76 47.20 Simuliidae 30.0 3 .83 40.0 4 1.63 Misc. Diptera 30.0 3 .83 80.0 22 13.66 Daphnia Bosmina Chydorids Diaptomus adults nauplii Nites 10.0 1 .28 20.0 1 .62 Misc. aquatics 20.0 1 .62 Misc. terrestrials 20.0 1 5.88 30.0 ) .83 40.0 4 2.48 40.0 3 6. 38 40.0 7 2.85 Fish Unidentified and 20.0 1 5.88 10.0 .28 100.0 inanimate material 9 5.59 20.0 1 2.1) 40.0 5 2.03 ) l 1 1 Table 8.101 Rainbow-steelhead fry stomach contents, 1976 brood, Sauk River-continued. Date Feb. '77 Maq;h •zz Aj!ril '77 May '77 _..J~ne 'ZZ sent· '17 Location and Sauk 5 Sauk 5 Sauk 2 Sauk 10 Sauk 1 Sauk 1 sample size % Empty 0 0 0 0 0 0 Freq. Total % Freq. Total % Freq. Total % Freq. Total % Freq. Total % Freq. Total % occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. Collembola Psoptera Homoptera 20.0 3 5.17 Ephemeroptera nymphs 80.0 31 72.09 25.0 1 7.69 100.0 15 88.24 70.0 27 46.55 100.0 14 58.33 adults Plecoptera nymphs 40.0 2 4.65 50.0 3 23.07 50.0 2 11.76 30.0 3 5.17 adults 10.0 1 1.72 Trichoptera larvae 20.0 2 4.65 25.0 1 7.69 20.0 2 3.45 100.0 1 4.17 pupae ""' adults 00 Diptera \Q Chironomidae larvae 20.0 7 16.28 75.0 7 53.85 30.0 3 5.17 100.0 6 25.00 pupae adults Slmuliidae 10.0 1 1.72 100.0 3 12.50 Mise, Diptera 20.0 5 8.62 PaJ •hnia Bosmina Chydorids Diaptomus adults nauplii ~!Ltes 10.0 1 1.72 Mlsc. aquatics 10.0 1 1.72 Misc. terrestrials 60.0 11 18.97 100.0 4 100.0 Fish Unidentified and 20.0 1 2.33 25.0 1 7.69 inanimate material 490 Table 8,102 Rainbow-steel bead fry stomach contents; summary of 1976 brood. Location: Upper 3 Skagi.t sites Lower 2 Skagit sites Cascade Sauk Date: 1976-1977 1976-1977 1976-1977 llJ7b-llJ77 Sample size: 101 72 56 51, -% Empty: ---.'f....9_7 ___ Z.ZB _____ 3_._.5_7 ___ -·-·-_1~.8.5 ------ Freq. TotHl % Freq. Total % Fr,•q. Total % Frcq. Tot.:ll ., I or. cur. no. occur. OCCUL .. no. OCCUL • occur .. no .. L'CCUL. ocrur. no. occur. Collembola 5.1 20 0.64 4.3 8 0.25 7.4 8 0.5~ ~ Psoptera 4.1 4 0.13 5.7 20 . 0.62 3.7 3 0.20 Homt>ptera 12.2 15 0.48 11.4 108 3.36 11.1 14 0.94 7.5 5 0.50 Ephemeroptera nymphs 52.0 1169 37.15 60.0 1027 31.97 61.1 544 36.56 58.5 2~5 24.72 adults 4.1 7 0.22 1.4 2 0.06 ~ Plecoptera nymphs 48.0 304 9.66 34.3 100 3.11 38.9 98 6.59 45.3 106 10.70 adults 5.1 11 0.35 10.0 15 0.47 1.9 3 0.20 1.9 1 0.10 ~ Trichoptera larvae 23.5 ~4 1.40 ~1.4 78 2.43 24.1 18 1. 21 3~.0 34 3.43 pupite 1.0 1 0.03 adults 3.1 3 0.10 10.0 37 1.15 1.9 1 0.10 Diptcra ~ Chironornidae larvae 50.0 371 11.79 55.7 ~02 12.52 59.3 297 19.% h!.~r ~ 2 390 39. J5 pupae 5.1 J~ 0.~~ 10.0 14 0.44 14.3 20 1. "],. ~-4 2l 2.12 adults 34.7 421 13.38 35.7 962 29.95 38.9 356 2:1.92 17.0 90 9.03 51 mul iidae 14.3 210 6.67 25.7 125 3.39 13.0 0.47 11.2 11 1.11 -Misc. Diptera 31.6 84 2.67 28.6 96 2.99 29.6 41 2.7G 17.0 30 3.03 Dar ·lu; io'! 4.3 25 0.78 llcsmi>w 3.1 59 1. 87 Chydorids 1.0 1 0.03 Diaptomus adults 4.1 13 0.41 nauplii Hit('S 12.2 23 0.73 10.0 15 0.47 7.4 4 0.27 5.7 3 0.30 Nisc. aquatics 1~. 3 75 2.38 15.7 12 0.37 11.1 6 0.40 3.8 2 0.20 ~ :t-1i.sc. terrestrials 40.8 117 3. 72 37.1 67 2.09 40.7 35 2. 35 32. 1 33 3.33 Fish :-~nrl fish eggs ~.3 3 0.09 :;nJ dt'ntlfj ed and 30.6 181 5. 75 28.6 96 2.99 29. (, 34 2.2R 22.6 19 1. 92 i.nanimate material """'" - - - - - - - - 491 the Skagit River at Marblemount (river mile--RM--78.2) during the time when it was felt that salmon fry were abundant. A minimum discharge was then developed for Gorge Powerhouse (RM 94.3) based on fry emergence and migration data and on normal trubutary inflow between Gorge Powerhouse and Marblemount. The minimum discharges and dates recommended were 2,300 cfs from February 1 to April 15; 2,000 cfs from April 15 to ~1ay 1; and 1,700 cfs from May 1 to May 15. The Federal Power Commission (FPC) licensed minimum flow of 1,000 cfs was to remain in effect the rest of the year. In Harch 1973 at the request of Seattle City Light (SCL), personnel from WDF and FRI conducted additional studies on the stranding problem (Phinney 1974~). The 1973 study re-emphasized the earlier findings that substantial salmon fry mortalities could occur under certain conditions. Phinney recommended that a reduction in the minimum flows outlined by Thompson (1970) was not acceptable if flows were fluctuating. In their studies, Thompson (1970) and Phinney (1974~) discussed the probable factors involved in fry stranding as: 1. The seasonal abundance of each of the different species in the shallow water areas. 2. 3. 4. 5. The magnitude and rate of flow fluctuation, particularly the level and duration of the low flow when proportional larger areas of river bar are exposed. The time of day of flow fluctuation, as it may affect fry distribution and behavior. Trubutary inflow, as it contributes to the discharge at Gorge Dam and affects total flow levels. The ~opography of the river channel, including the slope and substrate composition at different locations. Total estimates of fry kill in the Skagit. River between Marblemount and Baker River were made in the ?1arch 1973 experiments. These estimates were based on enumerat~on of dead fry found per unit area in the area exposed by flow fluctuation on four bars in the Skagit River between Rockport and Newhalem. These estimates were extrapolated to kill per linear foot of each of the four bars and further extrapolated to total linear feet of bar in the river area from Newhalem to the Sauk River mouth and from the Sauk River mouth to Baker River, based on measurements from aerial photos. Bars in the latter river stretch were not sampled. Estimates of total kill were as follows: Mortality Date Flow reduction (Newhalem) Newhalem-Sauk Sauk-Baker Harch 17 -5,ooo cfs to 2,304 cfs 17,900 15,600 March 18 -5,ooo cfs to 2,304 cfs 22,400 19,500 March 18 2,304 cfs to 1 '088 cfs 105,300 91,900 492 Some aspects of the estimates could be challenged, and there is certainly question as to whether experiments on other dates would have provided larger or smaller mortality estimates. The 1973 experiment did show, however, that substantial mortality can occur as a result of flow fluctuation, and that schedules such as proposed by WDF need to be applied insofar as feasible to minimize this source of mortality. This, in fact, has been accomplished by informal agreement between WDF and SCL. Phinney (1974~) estimated that roughly 3 percent of the total potential number of chinook fry produced in the Skagit River between Newhalem and the sauk river were killed in the scheduled severe flow reduction of March 18. Obviously, if fluctuations this extreme were repeated periodically, the cumulative mortality could be severe. However, it could be speculated, with some justification, that rearing area is limited and that as a result remaining fry may have a higher survival rate, at least partially compensating for mortality caused by stranding, or that the weaker fry tend to be the ones killed by stranding. However, adequate proof of these possibilities is still lacking. An effort was made to determine success of brood year classes subjected to favorable and unfavorable flow-fluctuation water years by examining escapement-return data. However, it was determined that the accuracy of available escapement data, the difficulties of assigning chinook catches in the various fisheries to river of origin, and the relatively low variation in the estimates of escapement from year to year precluded correlating return per spawner to possible flow fluctuation conditions encountered by the brood year fry. Studies were conducted by FRI per~onnel during the winter and early spring of 1976 and 1977 to determine the extent of losses due to fry stranding in the Skagit Riv~r between Newhalem and the Sauk River under the present operational regime and estimate the probable effects of flow regulations which may be potentially proposed by fisheries agencies for relicensing or which may be potentially provided by Copper Creek Dam. the previously described studies of Thompson (1970) and Phinney (1974~) were conducted during scheduled flow reductions where the rate of reduction (ramping rate) was near or greatly exceeded, in the case of Thompson's studies, the maximum ramping rate of the usual operational policy of SCL. The data on stranded fry was further used to compare the condition factors of stranded and non-stranded fry in an effort to determine if stranding was size selective. Additional investigations were undertaken in 1978 to better understand some of the factors which may influence fry susceptibility to stranding. These investigations were carried out in an experimental channel where the timing and magnitude of the flow reduction and the fry population could be controlled. 8.2.2 Materials and Methods. 8.2.2.1 Mortality Due to Stranding. In 1976, observations for fry stranding were made by FRI personnel along the main channel.of the Skagit River (Fig. 1.1) at County Line Bar (right bank at ID1 89.2), Marblemount Reference Reach (left bank at RM 79.4), and Rockport Rar (right bank at ~- - - f· - - - 493 RM 67.0). In 1977 the same areas were studied except for ~1arblemount which was sampled downriver in the vicinity of the ~1arblemount Bridge (left bank at RM 78.3). The observations were made to obtain data comparable with those obtained by WDF in 1973 (Phinney 1974a). Two additional sites (Bacon Creek Bar, RM 82.8 and Sutter Creek Bar, IDi-70.9) examined by WDF in 1973 were not studied by FRI because of the limited bar exposure under normal operating conditions. It was found in 1976 that effective observations could not be made on days when the exposed substrate was frozen. This restricted the times it'l early season when observations could be taken. Times selected for observations of fry stranding under normal operating conditions were times when flow reduction was sufficient to expose considerable river bar area. In 1977, improved communication with the SCL Power Control Center facilitated the sampling effort by helping predict when such flow reductions were likely to occur. If the flow reduction occurred during daylight hours, the survey team was present at the study site as the flow receded. These measures were taken to minimize scavenging of the stranded fry by birds. Fry stranding surveys were not possible after late-April 1977 because flow control exercised by SCL until late-October 1977 virtually eliminated flow fluctuations and the resulting stranding mortalities for that period. Transecting methods were essentially the same as those described by Phinney (1974~). The upper layer of substrate was removed to maximize the detection of stranded fry~ Fry mortality per unit area and per linear length of exposed bar was calculated for the days when surveys were conducted in 1976 and 1977. The estimate of linear feet where ·stranding might occur between Gorge Powerhouse and the Sauk River (27.7 river miles) was Qbtained by outlining the shorelines and perimeters of bars where conditions approximated those of the study sites on a set of aerial photographs with a scale of one inch equals one hundred feet. The outlined areas were measured with a map measuring instrument and converted to feet by multiplying by 100. This distance was used in the calculations of total mortalites for the days when surveys were conducted. The potential fry mortality from stranding for 1977 was estimated by expanding the mortality esiimates calculated for the days in 1977 when surveys were conducted. The hourly flow records from January 1 to : April 21, 1977 were analyzed. This included the period when fry were available but not necessarily in peak numbers until the non-fluctuating flow regime was implemented by SCL. The flow reductions in excess of approximately one foot were classified according to the minimum elevation reached at the Newhalem gage (U.S. Geological Survey--USGS) and to the number of feet dropped. Based on this classification the proportion of flow fluctuations surveyed to the total number of flow fluctuations for the period was calculated and used to project the potential seasonal fry mortality due to stranding. 8.2.2.2 Stranding Selectivity. Length, weight, and condition factors were calculated for four groups of stranded chinook fry from 1976 and one group from 1977 to compare with length, weight, and condition factors of unstranded fry (electroshocking samples) from the same locations. - 494 In addition, a ?roup of rainbow-steelhead trout fry were captured in August 1977 and treated like a stranded fry sample to determine if stranding ~ and subsequent handling caused changes in lengths, weights, or condition !actors. The stranded fry are different from the electroshocked samples in that they have been dead for several hours before they are brought back to the laboratory for measuring and weighing while the electroshocked samples were normally alive just prior to measuring. The trout fry were hrought back to the laboratory alive, killed, weighed, and measured, just like a normal electroshocked sample. The fry were then placed on a bed of wet gravel for two hours, simulating stranding conditions, and finally placed in a jar of water for one hour, simulating the trip from the field to the laboratory. The fry were remeasured, reweighed, and condition factors were calculated. The changes in lengths and weights were applied to the original samples of stranded chinook fry for another comparison with the unstranded fry. All comparisons were made using the Wilcoxon matched-pairs signed-ranks test. 8.2.2.3 Ramping Fates. Fry stranding data from our 1976 and 1977 studies were combined with that of Phinney (1974~) to describe the relationship between stranding mortality and rampin? rate. Stranding mortality for sites common to both studies (County Line and Harblernou~t b~rs) was plotted against ramping rate. Regression analysis was performed and correlation coefficients were calculated. 8.2.2.4 Experimental Studies. A section of spawning channel at the Big Beef Creek Research Station on Hood Canal was 'altered to simulate flow and substrate conditions on the Skagit River. The channel was formed by two 3-ft high and 6-inch thick concrete walls and was 50 ft long (Fig. 8.69). A river bar was simulated by placing a single layer of large rock (minimum diameter 2 inches) on a substrate of mixed sand and gravel. The 8-ft wide bar was sloped gently (1 to 15) to one side where there was an 18-inch wide channel for minimum flow. The fry were contained within the "bar" area hy two screens made of 1/8-inch nylon net stretched over a wooden frame. The downstream screen had a 6-x 12-inch opening into the minimum flow channel. The opening had a bag net and trap which were used to remove the fish after each trial. The water level in the channel was controlled by a stack of 10 1-x 3-inch boards just below the lower screen. During a trial six boards were removed, one every 10 min, to simulate a river drop of 6 inches per hr (actual rates in the Skagit River vary up to about 18 inches per hr). The water flow rate was controlled just upstream of the upper screen by a 2-x 3-ft gate. As each board was removed the gate was closed a predetermined amount to maintain the flow rate near 1 ft/sec to simulate typical Skagit River flow rates. To divert and dissipate the strong current of water entering the channel, there was a stack of cinder blocks betwPen the gate and upper screen. Prior to use in the experimental channel all fry were held in an adjacent channel in one of two 5-x 5-ft pens made with the same 1/8-inch netting as the screens. The water level and flow rates were constant. The second 5-x 5-ft pen held the "used" fry, which had experienced the channel. - - t ~. '• I I ! I L a'-o" l 1 1 I i I 1 ) l + ,I!L--f-,.~.,.,--:---,-~.,.,--,-~--, ... -.-,-<,...,--".~~IN. _FL()';' .-.A.-... I i [ -'lo" m••h '''ee" ·. ~:: . ~-::&><: I L cinder blocks I L. __ flow gate !'"'"" L_ sand & gravel SECTION TOP VIEW rock max. flow min. flow .___ __ min. flow channel ) ··~ •" cone. wall r..;..;.."lF~~--l--1 1/~' X 3" Steel channel 1x 3" stop block ~-·. _: t"'.' .. · ... It!"·. ·.·.-~· .·.t ..__ ___ {1a) 1X3~ stop blocks _.___ __ ,,_,mesh screen Fig. 8.69 Experimental stranding channel at Big Beef Creek Research Station. 496 Chinook fry were collected at the Skagit River by electroshocker and transported to Big Beef on February 16, March 9, and March 29, 1978, (Groups I, II, and III, respectively). Additional chinook fry were collected at the Lewis River with a stick seine on April 21, 1978, (Group IV). The following routine was used for e~ch ttial in the experimental channel: Gravel on "bar" was raked to distribute it evenly. Trap was disconnected and cover was placed over opening in lower screen. Stop blocks put in position and flow gate opened-level raised to maximum. Sample of 100 fry released at midchannel. Fry were allowed to acclimate for either 16 or 64 hrs. Beginning at 8:00a.m., one stop block was removed every 10 min. As each block was removed the flow gate was closed a predetermined amount. When the flow reduction had uncovered the bar, 6 blocks and 60 min later, the remaining 4 blocks were removed. The trap was positio'ned and the lower screen opening uncovered. The nonstranded .fry were collected in the trap and the stranded fry were recovered by sorting through the gravel. The channe.l was completely drained and those fry which avoided the trap were hand-netted out of the mini~um flow channel. The variables tested were: stability of flow prior to reduction; fry learning; and fry age and/or size. The effect of prior flow was examined by running overnight and weekend trials with 16 and 64 hrs, respectively, of steady flow prior to the reduction. Fry learning was examined by running the same sample of fry twice and comparing the stranding mortality between the first and second trials. Fry age and size were examined by comparing the differences in stranding mortality between the fry sampled on February 16; t1arch 9; Narch 29; and April 21, 1978. The general schedule was to run the weekend trials from Friday afternoon to Monday morning. Following the trial, these fish were put in the "used fry" pen to be returned to the river. The first run fry were put in either Monday or Wednesday afternoon and recovered Tuesday or Thursday morning, respectively. While the channel was prepared for their second run the fry were held in a large bucket. The turnaround time for the channel - - ~. - 497 was about 6 hrs. Following the second run, on Wednesday or Friday Morning, the recovered fry were then put in the "used fry" pen. Because of early difficulties in recovering the first run fish, the sample was often too reduced to mak~ a second run. 8.2.3 Results and Discussion 8.2.3.1 Mortality Due to Stranding. The data for 1976 sampling are given in Table 8.103, including the approximate minimum flow reached and the flow reduction as measured at the Newhalem and Harblemount gaging stations (USGS). The flow lag timeapproximations used downriver from the Newhalem gage were 1 hr to County Line Bar, 2-3 hrs to r1arblemount bars, and 5-6 hrs to Rockport Bar. The hourly flow patterns at Newhalem (USGS) for January through Hay 1976, are shown in Fig. 8.70. The variable nature of the timing, frequency, and magnitude of flow fluctuations can be discerned from this figure. The flow reductions that were sampled for stranded fry are indicated by arrows. A distance of 112,330 linear ft where stranding might occur was calculated from aerial photographs for the river between Gorge Powerhouse and the Sauk River. Extrapolating the fry mortality per linear foot to the estimated bar distance between Gorge Powerhouse and .the mouth of the Sauk River where stranding might occur, we estimate a total mortality of 33,137 fry occurred on the five 1976 observation days.1 This extrapolation includes the assumptions that all dead fry were counted, that those considered freshly dead had been stranded during.the current flow reduction, and that stranding was indeed the cause of mortality of dead fry observed. The 1977 fry stranding observations were more extensive. Results are summarized in Table 8.104. The daily flow patterns at Newhalem (USGS) from January to mid-April are graphed in Fig. 8.71 with stranding observation dates indicated by arrows. The estimated total fry mortality due to stranding between Gorge Powerhouse and the Sauk River was 53,918 for the 11 observations ·in 1977. Several of the minimum flows reached in the 1977 observations were in the vicinity of 2,300 cfs at Newhalem (Table 8.104), similar to the. Harch 1973 test (Phinney 1974a). Mortalities per 1,000 ft2 in all cases were less than encountered at-corresponding bars in the March 17-18, 1973, tests of flow reduction to 2,304 cfs. However, the estimated chinook spawning escapement was also larger in 1972 tharr it was in 1976 (Table 5.3), and the ramping rates were lower for the surveys in 1977 under operational conditions than they were for scheduled tests conducted in 1973. Even so, it was apparent that flow fluctuation did cause mortality at higher discharges. The majority of the fry mortalities estimated for the 1976 and 1977 surveys applied to chinook salmon fry, but included some pink and churn fry as well. One pink fry was found stranded during the 1976 surveys and one chum fry during 1977 surveys. The relatively short freshwater residence time for pink and chum fry following emergence (Sec. 8.1.4.4 and 8.1.4.7, 1 The two mortality values for March 23 were averaged. Table 8.103 Fry stranding observations, 1976. Date Location Time surveyed Area surveyed (sq. ft.) Linear feet surveyed No. of stranded fry Feb sa Rockport 0700 300 6 0 sa Rockport 0600 Mar area surveyed because of County line No Marblemount 0700 frozen substrate. Mar 17 Marblemount 0930 b 173c 8 Mar 23 County line 1200-12SS 3S3 38 11 Mar 23 Marblemount 13S0-1SOO b 173c 36f Apr 22 Marblemount OS1S-OS4S 386 22 0 Apr 29 County line osss 243 18 0 ---------------------------~------------------ aGround too frozen for effective survey. b Area measurements not taken. cShoreline between transects 3 and 4 examined. dFlow dropping during observations, hence corresponding eComplete flow records not available during observation f Includes one pink salmon fry. J Mortality Mortality per 1,000 per sq.ft. linear ft 0 0 '\ 0.046 31.2 0.289 0.208 0 0 0 0 Flow at Newhalem Minimum (cfs) 3,910 3,S3S 4,769d 3,430d 3,S9S 2,490 Decrease (cfs) 2,784 94S 2,01S 3,390 3,317 2,07S minimum at Newhalem difficult to estimate. period. J Flow at Marblemounf Minimum (cfs) S,240 S,300 Decrease (cfs) ,!:-. \0 00 1----w w LL :z: 1----4 I--- I C) 1----4 w I ['•_ . ) l ·~ J . ] l ···. ) ) ) . l SKRGIT RQ RT NEWHRLEM -JRNURRY 1976 SUNDAY MONDAY TUESDAY WEDNESDAY THURSDAY FRIDAY SATURDAY ~I= =I =I =-===lrt=¥==2 4P==3~ ~ ~~~8~ /19 m~4;s1?~3~ ~1=&26 ~~-47:~0 ~~ Fig. 8.70 Hourly gage height data for Skagit River at Newhalem (USGS), January-May, 1976. ] J 1----w w LL :z. 1----l I-- I CJ 1----l w I w CJ ~ SKRGIT Ra RT NEWHRLEM FEBRURRY 1976 SUNDAY MONDAY · TUESDAY WEDNESDAY THURSDAY FRIDAY SATURDAY I 10 I 11 1~=:~ ~ ~~=;~t~4 I 25~1t:r=t-:7 tv 28 ~ 88 86 84 " :~ [29 I I I I I I ~ Fit;. 8.70 Hourly gage height data for Skagit River at Newhalem (USGS), January-May, 1976-continued. Vl 0 0 I--w w LL z f---1 I-- I CJ f---1 w I w (_J a: (_J l SKRGIT Ra RT NEWHRLEM MRRCH 1976 SUNDRY MONDRY TUESDAY WEDNESDAY THURSDAY FRIDAY SATURDAY ~I 60 I 1 ~ 3 lu 4 t ~5~ 6 ~~ ~I' I p I I I I I 1\ / '-" <> 7 8 9 10 11 12 13 80 ~~~~ 15~v-~ 16~ 17 jvo 18 / I 1: 1 I ~0 I ~lv:~*22 I ~= ~ 24 I 25 I 26 aa ~ ~1~'28 r~ I I I 29 30 31 Fig. 8. 70 Hourly gage height data for ·Skagit River at Newhalem (USGS), January-May, 1976-continued. lw 27 I I I VI 0 .... 1-w w LL z: 1--1 1--1 w :r: w 0 a::: 0 SKRGIT RQ RT NEHHRLEM APRIL 1976 SUNDRY MONDRY TUESDAY WEDNESDAY THURSDAY FRIDAY SATURDAY ~1==1 =-I =I ===I =, I =2 ±===:~ ~r.~~~ 1~ 8 1~-' 9 ~~~ ~ILJi$112 8c;; I~ FJ;JF~ /20 lv 21 $ 22 }r 23 I~ Fig. 8.70 Hourly gage height data for Skagit River at Newhalem (USGS), January-May, 1976-continued. J .. ) \.J1 0 N f-w w LL SKRGIT Ra RT NEWHRLEM MRY 1976 SUNDRY MONDRY TUESDAY WEDNESDAY THURSDAY FRIDAY SATURDAY ~=I ===1==1 =-=I =I=~ ~I 80 Fig. 8,70 Hourly gage height data for Skagit River at Newhalem (USGS), January-May, 1976-continued. ·.. J J Table 8.104 Fry stranding observations, 1977. Area Linear No. of Mortality Hortality Flow at Newhalem Flow at Marblemount Time surveyed ft. stranded per 1,000 per Minimum Decrease Minimum Decrease Date Location surveyed (sq. ft.) surveyed fry sq.ft. linear ft (cfs) (cfs) (cfs) (cfs) Feb 3 County line 1600-1700. 480 32 0 0 0 3,550 3,293 Feb 8 Marblemount 0725-0815 a 24 4 0.17 2,260 4,329 2,815 4,150 Feb 23 Marblemount 1600-1715 624 32 1 1.6 0.03 2,550 4,523 3,685 3,865 }1ar 1 County line 1500-1600 1,228 48 5 4.1 0.10 2,730 2,660 Mar 10 Harblemount 0630-0800 1,128 63 1 0.9 0.02 2,394 4,090 3, 710 4,000 Mar 10 County line 1300-1400 748 32 1 1.3 0.03 2,730 2,679 ~1ar 18 County line 1330-1430 688 40 0 0 0 3,475 3,093 Har 19 Rockport 0530-0600 96 8 0 0 0 5,637 1,206 6,650 740 Mar 22 Rockport 0600-0745 448 40 2 4.5 0.05 4,667 2,544 6,195 1,955 Vl 29 lb 0 Har Marblemount 0515-0600 742 34 1.3 0.03 2,382 4,375 3,394 4,036 +:- Mar 30 County line 0515-0700 1,024 40 2 2.0 0.05 2,359 4,377 --------------------------------------------- a Area not recorded on one transect. b Chum salmon fry. J ; J ] 1 ) ., ) j ) J ) . ) ) I-w w LL :z: 1---i I- I c.'J 1---i w :::c w c.'J CI c.'J SKRGIT Ra RT NEWHRLEM -JRNURRY 1977 SUNDRY MONDRY TUESDAY WEDNESDAY THURSDAY FRIDAY SATURDAY ~I 80 I I ~~cl 88 :~d2 I 1~1 7 .. 1\ t~ J~ g 3 5 6 8 80 88 I~ lv-11 ~ J~ I~ B I ~ ~~~ lg 10 ]2 ]3 88 I I I I I I I =I\ 17 18 19 20 21 22 80 1 ~I 80 23 I 24 I 25 I 26 I 27 I 28 I 29 I 88 ~I, ~·~ l I I I I I Fig. 8. 71 Hourly gage height data for Skagit River at Newhalem (USGS), January-April 14, 1977. . 1 Vl 0 Vl f--w w LL z 1--1 !-::r:: 0 1---1 w ::r:: w 0 CI 0 SKRGIT Ra RT NEWHRLEM FEBRURRY 1 97t7 SUNDRY MONDRY TUESDAY WEDNESDAY THURSDAY FRIDAY SATURDAY I Jo17~tfil Ekki -hl~ I t;t+ 24 I ~ El~~~l~¥4~8 ___L_I _ __L__I _______J______I ________l___l _l Fig. 8.71 Hourly gage height data for Skagit River at Newhalem (USGS), January-April 14, 1977-continued. J -) lJl 0 a- j l 1 1-w w LL z ............ 1- 6 1----l w I w D ~ ---l ----------------------- ·---l J -. ll D ) ' , SKRGIT Rn RT NEWHRLEM -MRRCH 1977 SUNDAY MONDAY TUESDAY WEDNESDAY THURSDAY FRIDAY SATURDAY ~1=+:@ / 7 IV 8 P± lh~ I ~1 ~/12 I ;1~-,3 -----+l-,v14 I 15 t= 16 ;=:17 T!~1~ I Fig. 8.71 Hourly gage height data for Skagit River at Newhalem (USGS)~ January-April 14, 1977-continued. ] f-w w LL z ......... w ::r::: w 0 CI 0 SKRGIT RQ RT NEWHRLEM RPR I L -1977 ~I 80 88 86 84 82 80 -- ~[ 80 SUNDRY MONDRY TUESDAY WEDNESDAY THURSDAY FRIDAY SATURDAY I~A 2 ; ~ ~" ~)\ ~ 3 4 5 6 7 8 9 ~I o1 ~\I r-"\ ~ ;:~ TV 10 13 I :3 15 Fig. 8.71 Hourly gage height data for Skagit River at Newhalem (USGS), January-April 14, 1977-continued. .J \.J1 0 (Xl ,..- I""' I -I - 509 respectively makes them mmuch less susceptible to stranding than chinook fry. The later emergence timing of chum fry (Table 7.16 and Sec. 8.1.4.7) probably reduces their susceptibility to stranding also, because of the generally higher streamflow with the commencement of "spring runoff". While stranding observations were not made for rainbow-steelhead trout fry, they are also considered to be less susceptible to stranding than chinook fry for several reasons. First, spawner distribution was very low in upstream areas (Sec. 6.4.3.5) where the effects of flow reductions were greatest. Second, much rearing takes place in tributary streams, outside the influence of flow fluctuations in the mainstem Skagit River. Redistribution of fry into the mainstem Skagit probably does occur, but these fry would presumably be older and larger and may be less susceptible to stranding. Third, a large proportion of the emergence period coincided with the latter part of the high stream flow period in June, July, and early August. Results of the classification of flow reductions according to m1n1mum elevation reached and the number of feet dropped at the Newhalem gage (USGS) for the period from January 1 to April 21, 1977, are presented in Table 8.105. These analyses showed that we had fairly good distribution of sampling for flow reductions to 83-and R2-£t, but none for reductions to 84 ft. In terms of the number of feet dropped, we sampled propor- tionately more of the 3-ft drops than the 2-ft drops and none of the 1-ft . drops. Based on this classification system, we sa~pled approximately 10 percent.(ll/108) of the flow reductions during this period of 1977; and so a gross estimate of total fry killed due to stranding would be 54,000 x 10, or 540,000 for 1977. We consider this to be an overestimate for several reasons. First, this calculation implies comparable mortality during January and April for which we have no strariding observations. Of the 108 flow reductionR, 36 occurred in January and April. Our chinook abundance information (Fig. 8.2) indicated that fry were not as available on the bars in January and April as they were in February and March. This generally agrees with the estimate of emergence timing based on temperature unit requirements. Secondly, results from our stream channel stranding studies indicated that fry may be susceptible to stranding for a fairly short time and that this may he related to age or experience. Substantial increase in average size also occurs in April. Thirdly, we sampled a disproportionately hip.h number of the larger magnitude fluctuations in 1977. For these reasons we consider a kill of 540,000 fry to be a worst case estimate for 1977. However, we do not have a good numerical basis for adjusting the figure downward. 8.2.3.2 Stranding Selectivity. Comparisons of stranded and unstranded chinook fry from 1976 and 1977 surveys indicated that stranded fry had significantly (at a = 0.05) higher condition factors than thP unstranded fry from the same locations and approximately the same date (Table R.l06). 510 Table 8.105 Classification of flow reductions for Skagit River at Newhalem (USGS) between January 1 and April 21, 1977, according to minimum elevation attained and number of feet dropped. Number of flow reductions surveyed for stranded fry are shown in parentheses, Minimum elevation(ft) 84 83 82 81 Magnitude of reduction( ft) 1 2 3 Equivalent streamflow(cfs) -5,000 -3,400 -2,200 -1,200 Total Total Number of occurrences 16 36 (4) 56 ( 7) 0 108 (11) Number of occurrences 47 43 (6) 18 (5) 108 ( 11) ~' - _, ~ > - - - ~ou, - - 511 Table 8.106 Observed and corrected length, weight, and condition factors of stranded and unstranded chinook fry from surveys conducted in 1976 and 1977. Date 3/14/76: 3/17/76 3/17/76c 3/19/76~ 3/23/76 3/23/76c 3/22/76~ 3/23/76 3/23/76c 4/19/76~ 4/19/76 4/19/76c 3/22/77~ 3/22/77 3/22/77c Length groups: 36-40 mm Length Weight Condition Length Location N (mm) (g) factor N (mm) Marblemount 9 39.6 0.466 0.750 17 42.0 II 2 40.0 0.465 o. 727 8 41.8 11 2 40.6 0.451 0.674 8 42.4 County Line 11 39.6 0.455 0.730 14 41.8 II 6 39.7 0.4 75 o. 759 13 41.5 II 6 40.3 0.460 o. 703 13 42.1 Marblemount 11 39.7 0.449 0.718 14. 42.1 II 11 39.4 0.434 o. 710 24 42.0 II 11 40.0 0.421 0.658 24 42.6 Talc Mine 5 39.6 0. 486 0.783 23 42.2 ... 4 38.8 0.542 0.928 2 41.5 II 4 39.4 0.525 0.858 2 42.1 . Rockport 9 39.1 0.454 0.760 16 42.1 II 13 39.2 0.530 0.880 20 41.4 II 13 39.8 0.514 0.815 20 42.0 a = Condition sample from electroshocking samples. b Stranding sample. c = Stranding sample corrected for 1.53% loss in length and 3.09% gain in weight. · .. . ~-~ 41-45 nnn Weight Condition (g) factor 0.542 0.732 0.596 0.816 0.578 0.758 0.535 0.730 0.538 o. 751 0.521 0.698 0.542 0.726 0.526 o. 710 0.510 0.660 0.647 0.861 0.660 o. 923 0.640 0.858 0.522 o. 700 0.534 o. 753 0.518 0.699 512 The experiment simulating stranding resulted in a 1.53 percent loss in length and a 3.09 percent gain in weight of the rainbow-steelhead trout fry (Table 8.107). The loss in length was probably due to rigor mortis and the weight gain from absorption of water. Although the experiment on changes due to stranding (and handling) was conducted with rainbow-steelhead trout, it is reasonable to suggest similar changes in chinook fry. The stranded chinook fry samples were corrected by these percentages and again compared with the electroshocked samples (Table 8.106). The stranded chinook fry, adjusted for handling, were significantly (at a = 0.05) longer than the unstranded fry. The new comparison of condition factors showed no significant (at a = 0.05) difference between stranded and unstranded fry. In view of these results, it is not possible at this time to conclude that there are any significant differences between stranded and unstranded chinook fry. 8.2.3.3 Ramping Rate. Analyses were conducted to determine the relationship between fry stranding mortality and the rate of flow reduction or ramping rate. Stranding mortalities for County Line and Marblemount bars from 1973, 1976, and 1977 surveys when plotted against corresponding ramping rates showed poor correlation. However, when the data were grouped by the minimum elevation attained (Table 8.108), either 82 or 83 ft for Skagit River at Newhalem (USGS), the correlation coefficients indicated that there was at least a 95 percent probability of a linear relationship between stranding mortalities and ramping rates. For flow reductions to 82 ft with n = 11, the correlation coefficient (r) = 0.69 (Fig. 8.72). For flow reductions to 83 ft with n = 7, the correlation coefficient (r) = 0.96 (Fig. 8.73). The slope of the line for flow reductions to 82 ft was significantly steeper than the one for flow reduction to 83 ft (at 0.90 level). This suggests that the stranding mortality increases as the minimum level of flow drops and supports the idea that at lower flow levels the increased proportion of exposed bar area and the increased drying-up of potholes increases the mortality due to stranding. These analyses indicated that for flow reductions to 83 ft or approximately 3,400 cfs, the expected stranding mortality would be zero for ramping rates at about 1,000 cfs/hr and less. For flow reductions to 82 ft or approximately 2,200 cfs, the expected stranding mortality would remain low or go to zero for ramping rates below about 500 cfs/hr. Field observations in 1976 and 1977 had suggested that the duration of the maximum flow prior to flow reduction might be a factor influencing fry stranding mortality. It was observed that when the highest stranding mortality occurred, on March 23, 1976, the longest period of maximum flow prior to reduction (28 hrs) also occurred (Table 8.108). However, observations of other long periods of steady prior flow, such as Narch 30, 1977, showed that stranding mortalities can be relatively low. It can also be observed that on March 23, 1976, the ramping rate was very high, 3,306 cfs/hr. The evidence indicates that the ramping rate and not the duration of maximum flow prior to reduction may be the more important factor in causing stranding mortality. - ~. - ~:· f '""" """' l '"""' ,...,, .F'" '- {""" - ..... ·- Table 8.107 Length group 31-35 36-40 41-45 46-50 51-55 31-35 36-40 41-45 46-50 51-55 31-35 36-40 41-45 46-50 51-55 513 The lengths, weights, and condition factors of 49 rainbow-steelhead trout fry measured fresh, "stranded" for two hours, and then soaked in water for one hour. N Mean length(mm) Mean weight (g) Condition factor Fresh rainbow-steelhead trout 1 34 0.34 . 87 26 38.6 0.5269 .92 15 43.1 0. 7707 .96 6 46.8 1. 0167 .99 1 55 1.61 .97 "Stranded" rainbow-steelhead trout 2 34.5 0.3600 0.88 26 38.3 0.5338 0.95 17 43.2 0.8053 1.00 3 47.7 1.1067 1.02 1 55 1.60 0.96 "Soaked" rainbow-steelhead trout 3 34.6 0.3967 0.95 26 38.4 0.5627 0.99 15 43.0 0.8287 1.04 4 46.8 1.1100 1.08 1 54 1.65 1.05 514 Table 8.108 Calculated ramping rate and time at maximum flow prior to flow reduction for flow reductions to approximately 82 and 83 ft at the Newhalem gaging station (USGS) Date for surveys conducted at County Line and Marblemount bars in 1973, 1976, 1977. Estimated mortality due to stranding is also shown. Ramping rate (cfs/hr) Time at maximum flow prior to reduction (hr) Stranding mortality (fry/lin.ft) County Line Marblemount Reductions to 82 ft 3-17-73 3-18-73 4-29-76 2-8-77 2-23-77 3-1-77 3-10-77 3-29-77 3-30-77 1950 2746 692 2050 1055 665 1630 636 1373 Reductions to 83 ft 3-17-76 3-23-76 4-22-76 2-3-77 3-10-77 3-18-77 1409 3306 1175 1308 1300 618 ND 15 5 2 2 4 1~ 3 14 7 28 3~ 6 4 2 0.92 0.73 0 ND ND 0.10 ND 0.05 ND 0.289 ND 0 0.03 0 0.13 0.50 ND 0.17 0.03 ND 0.02 0.03 ND 0.046 0.202 0 ND ND ND - .... J -· -~ - 515 FLOW REDUCTIONS TO 82 FEET t.ooo f. X I I .800 I I-a a X lL.. I 0:: cr: w I :z 1----4 _j .soo """" 0:: / w Q_ >-I I-X 1--1 _j I cr: ~--~ I- 0:: I a .400 .L.: I C) z / 1--1 0 / /' /' -:z / /' cr: / / 0:: / I-/ / (J) / / -/ .200 / / -9. / X I X I X XI X 0 0 1000.0 2000.0 3000.0 RAMPING RATE (C.F.S.PER HOURJ Fig. 8.72 Relationship between stranding mortality and ramping rate for flow reductions to 82 feet with 95 percent r-confidence intervals shown as dotted lines. ' f-a 0 L1... 0::: a: w z ~ _j 0::: w a.... >- f- ~ _j a: f- 0::: 0 L D z ~ 0 z a: 0::: f- (f) 51'6 FLOW REDUCTIONS TO 83 FEET 1.000~--------------------------------------~ .sao .soo ·400 / / ..... ..... / ..... / / ..... / / / / 0 1000.0 2000-0 3000.0 RAMPING RATE (C.f.S. PER HOUR) Fig. 8.73 Relationship between stranding mortality and ramping rate for flow reductions to 83 feet with 95 percent confidence intervals shown as dotted lines. .... - - """' ! -I - "'"'\ ..... - - ..... - 517 8.2.3.4 Experimental Studies. The results of the chinook fry stranding trials conducted at Big Beef Creek Research Station during 1978 are summarized in Table 8.109. One of the factors studied which may influence fry susceptibility to stranding was the stability of flow prior to a flow reduction. Observations by our field workers during 1976 and 1977 stranding surveys on the Skagit River led them to suggest that longer periods of steady flow may cause higher stranding rates. For example the highest stranding mortalities observed occurred on March 23, f976, when 28 hrs of stable flow preceded the flow reduction (Table 8.108). The rationale was that the fry would have more time to move onto the bars and establish stations. Since they would have been associated with the station for a longer time they may be more reluctant to move offshore as the water drops. Therefore, they would be more likely to become stranded • There was conflicting evidence from the experimental stranding trials that steady flow prior to reduction increases the stranding mortalities. For Group I the percent of fry stranded in the weekend trial with 64 hrs of steady flow prior to reduction was higher than those for the overnight trials with 16 hrs of steady flow, while for the other groups (II, III, and IV), the precent of fry stranded was similar or lower in the weekend trials than they were for overnight trials (Table 8.109). Fry experience, age, and size, were other factors investigated experimentally which may affect fry susceptibility to stranding. Because flow reductions occur relatively frequently in the Skagit River, about once a day, it is possible that after several.successful encounters with receding water levels the fry may "learn" to avoid stranding on subsequent reductions. Group II provided strong evidence supporting this statement. The mean stranding rate for the first and second trials of the sa~e fry, dropped from 4.8 to 1.5 percent (t = 1.15, different at 80 percent confidence). Group III also showed a slight decrease in stranding rate from 0.8 to 0.5 percent between the first and second trials. Adequate data were not available for Groups I and IV to make comparisons between first and second trials. If fry do "learn" to avoid stranding, then we would expect older fry to strand at a lower rate. The stranding rate between the first trials of Groups II and III (Group III fish were collected 20 days later then Group II fish and were significantly larger), dropped from 4.8 to 0.8 percent. This strongly suggested that older fry strand at a lower rate. The stranding rates between the first runs of Groups I and II (Group II fry were collected three weeks later and were significantly larger), however, were not significantly different. Because these two comparisons were inconclusive, chinook fry (Group IV) were collected from the Lewis River where the fish in this particular year had not experienced water level fluctuations (Hugh Fiscus, WDF, personal communication). The rate of stranding of Group IV was expected to be relatively high because the fish had no opportunity to "learn" about flow reductions. The stranding rate, however, was relatively low which suggested that experience was not a factor. Group no. I II III IV Table 8.109 Sununary of chinook fry strnnding trials conduc:ted at Big Beef Creek Resenrc:h Station during 1978, Capture Capture Length(mm) Trial Percent stranded ----·- s2 -s2 date location X N type X N 2/16 Skagit 41.4 2.31 30 Overnight 3 36 4 Overnight 4 1 Weekend 15 1 2/9 Skagit 42.0 5.24 44 Overnight 4.8 4. 71 5 Overnight 1.5 3.69 4 Weekend 0 1 3/29 Skagit 42.9 8.34 30 Overnight .8 1.2 5 Overnight .5 .67 4 Weekend .3 .33 3 4/21 Lewis 42.5 11.95 33 Overnight 0 2 Overnight .5 2 Weekend 1 1 a. Sample size of 50 fry and 6 were stranded. b. Sample was selected from fry used in all previous 1st run trials. Number stranded per trial 0,0,0,12il 4h 15 3,3,6,4,8 0,0,4,2 0 0,2,0,2,0 1.1'1 1-' 0,1,0,1 00 1,0,0 0,0 1,0 1 .;.-£~ .... 519 Lengths of stranded fish from Groups I, II, and III were compared to lengths of fish recovered alive from the channel. If experience is a factor, then the larger, and presumably older, fish would be less likely to become stranded. However, the stranded and recovered fish showed no significant difference in length. Stranded: x Recovered: x 42.2, s2 41.7, g2 5.8, N 4.8, N 20 20 t = 0.15 When FRI personnel compared the condition factors between stranded and nonstranded fish in the 1976 and 1977 studies on the Skagit River they also found no significant difference (Sec. 8.2.3.2). Studies by WDF on the Cowlitz River however, indicated that stranded fry were significantly shorter than unstranded fry (Bauersfeld 1978). There were sane observations of fry behavior in the experimental channel that were notable. The "wfld" Skagit and Lewis river fish, when released in the experimental channel, would swim immediately for the upstream screen. The fry would then, over the next few hours, become evenly distributed throughout the channel. An examination of the location of the stranded fish shows a fairly even distribution, with a sli~ht tendency to . strand near the downstream screen (Fig. 8.74). " "' 10' " X " " " X " " " \x " " " X " " X " X " X X " " " X " X X X X X X X X X " X X X X X X X X X X X xx xx X Fig. 8.74 Locations of stranded fish in experimental channel. During the debugging of the channel, local Big Beef Hatchery fry were placed in the channel. These fish stayed together in a "knot" in the deep water and could not be stranded. A sample of incubation box fry was later obtained from the Skagit River. These fish initially associated more strongly with the gravel than the "wild'' fry, but their stranding rate, 2 percent, was not significantly different from the "wild" fish. While some of the group tests suggested that learning experience or size/age of chinook fry may influence stranding rate, there were contradictory or inconclusive results in other tests. It is clear, however, that as long as fry are within the nearshore areas they run the risk of being stranded. Estimate of residence time in nearshore areas for chinook salmon are presented in Sec. 8.3. 520 8.3 Residence Time of Chinook Salmon Fry 8.3.1 Introduction The following is an attempt to glean an estimate of mean residence time for newly emergent chinook salmon fry in the Skagit River between Newhalem and Harblemount from various data collected by the Skagit River project, Fisheries Research Institute, University of Washington. Principal data include information on timing of egg deposition and emergence as well as a mark recapture experiment that introduced a large number of marked fish in the study area with subsequent recovery effort at two sites, Marblemount and County Line. Two methods of estimating residence time are presented. The first used linear regression and assumed a constant population size (in a steady state). The second method used a simulation model with more reasonable assumptions. The model simulated the proportion of marked fish in the population during the study period based on the temporal pattern of fry emergence and rate of disappearance. The rate of disappearance (outmi- gration and mortality) which gave the highest correlation between predicted proportion of marked fish and observed proportion of marked fish in the population was taken to be estim~ted disappearance rate. 8.3.2 Details of the Fry Marking Study The study area extended from Newhalem to Marblemount (Fig. 8.75), a distance of approximately 15 miles. Host of the sampling was done in areas where chinook fry were abundant. These were usually bars and riverbanks with relatively coarse substrate which provided good cover for the fry. One hundred minnow traps borrowed from Washington Department of Fisheries were used to capture fish; however, the time involved in setting them and the low rate of fish capture eliminated them as usable sampling equipment after the initial trial. The Smith-Root type VII backpack shocker proved to be quite effective in capturing adequate quantities of fish. Whenever large schools of fry were encountered the voltage was reduced from the maximum of 600 volts direct current to 500 or even 400 volts in order to minimize mortalities. The pulse width and rate were usually left at the maximums of 8 ms and 80 hz. The captured fish were taken to the boat for examination under the long wave ultraviolet light. The early observations indicated the marked fish would be recognized better under a more powerful light than was reco~ended for field use. The final light setup consisted of two 15 watt ultraviolet fluorescent tubes and a cold weather ballast to insure easy lighting in the field. Power was provided by a 12-volt battery going to 110 volts a.c. by means of a 300 watt inverter. The lights were mounted in a hinged box which had a viewing port. Further reduction of the ambient light was accomplished by draping a rubberized cloth hood over the box and observer. Sampling for the purpose of marking fish was conducted throughout the study area to obtain uniform proportions of marked fish in the population. - - I I ] 1 liGfHD il) USGS GAGING STATION ~ IIVUMILI 75"' DAM :. _, ST .. TI PISH HATCHIIT $TAT! lfAIING PONDS Fig. 8.75 Study area with the Marblemount and County Line stations. l l11 N I-' 522 Sampling for recaptures was conducted at two stations, Harblemount and County Line (Fig. 8.75). The chinook fry which had previously been marked were counted and released. The unmarked fry and fingerlings were enumerated, marked, and released. The fish were marked with fluorescent pigment granules under 300 ~ in diameter which were embedded in the fish by a portable sandblasting unit. Air ~ressure of 100 p.s.i. during spraying was supplied by a standard SCUBA tank and regulator with an attached pres'Sure gage. Two different colors were used in this experiment during the season - yellow from early February through Harch 17*, and green from April 11 through April 25. Fish marked with the yellow and green pigments were released near the areas where they were captured. Raw data from this study are presented in Table 8.110 and Table 8.111. Samples of 50 fish each were taken four times during the marking season to check for immediate mortalities (caused by marking and handling) and for mark retention. The fish were marked as usual and held in troughs at the State Fish Hatchery at Marblemount. The fish were checked for marks and mortalities within several days of capture. The samples were subsequently checked weely through the mark recovery period for mark retention. 8.3.3 Results 8.3.3.1 ~~rking Mortality and Mark Retention. Sa~ples of 50 marked fish each were held at the Marblemount Hatchery beginning March 1, 15, and 31 and April 25, 1978 to assess marking mortality and mark retention. Mortalities within 5-7 days of capture ranged from 0 to 4 percent (0 to 2 fish) and were assumed to be primarily caused by marking and handling. Mark retention was 100 percent through June 20, 1978, near the end of the mark recovery period. Harking mortality and loss of marks were ignored in the development of the residence time models. 8.3.3.2 Estimation of Pattern Emergence. An estimate of the temporal pattern of emerging chinook salmon fry during the spring of 1978 was derived from the following: 1. Estimated deposition of eggs by adult chinook salmon by weekly intervals during the fall, 1976 (Sec. 6.4.2.1). 2. Estimated days to fry emergence for each week of egg deposition. This was based on mean temperature units to yolk sac absorption (derived from hatchery and in situ experiments) and the *Over 97 percent of the fish marked with yellow pigment were marked from February 28 through March 17. - - ] 1 Table 8.110 Raw data from Skagit River marking study, Marblemount sampling station. Combined Yellow marks Green marks marks Catch Marks Cumul. Recap. r. I Marks Cumul. Recap. r. I r. ril 1 c. 1 C· 1 c. added marks ri added marks r. ci 1 1 1 1 Date M. M. 1 1 21 8 2 2 21 9 1 3 2110 16.4 167 2128 434 601 31 1 870 1471 31 2 60 1531 31 3 191 1722 31 7 247 1969 VI N 31 8 444 703 2672 10 .0225 10 .0225 w 31 9 87 2759 3110 303 3062 3114 355 3417 3115 506 1089 4506 33 .0652 33 .0652 3116 1225 5731 3117 596 6327 3129 1354 15 .0111 15 .0111 41 5 1768 11 .0062 11 .0062 4111 1321 1321 4112 424 2 .0028 1206 2527 2 .0028 4113 952 34 79 4119 1135 10 .0088 2018 5497 39 49 .0432 4124 1220 6717 4125 570 2 .0035 551 7268 61 .1070 63 .1105 5 I 2 511 1 .0020 57 .1115 58 .1135 51 9 769 3 .0039 61 .0793 64 .0832 5/16 350 0 .0000 20 .0571 20 .05 71 5123 205 0 .0000 16 .0780 16 .0780 Date 61 1 61 6 6113 6120 6127 Table 8.110 Raw data from Skagit River marking study, Marblemount sampling station- continued. Combined Yellow marks Green marks marks Catch Marks Cumul. Recap. R. I Marks Cumul. Recap. ril ri r. I c. added marks r. 1 c. added marks r. c. 1 c 1 M. 1 1 M. 1 1 :l :l 1 161 1 .0062 9 .0559 10 .0621 185 0 .0000 7 .0378 7 .0378 79 0 .0000 1 .0127 1 .0127 84 0 .0000 3 . 0357 3 .0357 29 0 .0000 0 .000 0 .0000 1 V1 N ~ --j 1 Table 8.111 Raw data from Skagit River marking studies, County Line sampling station. Combined Yellow marks Green marks marks Catch Marks Cumul. Recap. r. I Me~rks Cumul. Recap. r. I r. r. I c. added marks 1 c added marks 1 c. 1 1 c. r. r. 1 1 1 1 1 1 M. M. Date 1 1 21 8 2 2 21 9 1 3 2110 164 167 2128 434 601 31 1 870 1471 31 2 60 1531 31 3 191 1722 31 7 247 1969 \.11 N 31 8 703 2672 \.11 31 9 87 2759 3110 345 303 3062 29 .0841 29 .0841 3114 355 3417 3115 1089 4506 3116 1225 5731 3117 676 596 6327 89 .1317 89 .1317 3128 505 28 . 0554 28 .0554 . 3131 171 .13 .0760 13 .0760 41 7 694 20 .0288 20 .0288 4111 1321 1321 4112 1206 2527 4113 1014 10 .0099 952 34 79 10 .0099 4119 2018 5497 4124 1160 6 .0052 1220 6717 71 .0612 77 .0664 4125 551 7268 51 2 228 0 .0000 28 .1228 28 .1228 SilO 445 1 .0022 53 .1191 54 .1191 5117 277 22 . 0794 22 .0794 5123 274 8 .0292 8 . 0298 Date 6/ 1 6/ 6 6/13 6/20 6/27 Tabke 8.111 Raw data from Skagit River marking studies, County Line sampling station - continued. Combined Yellow marks Green marks marks Catch Marks Cumul, Recap. r./ Marks Cumul. Recap. ri/ r, r,/ c. added marks l c. added marks l l c. r. r. c. l M. l l M. l l l l l 176 2 .0114 2 .0114 134 4 .0299 4 .0299 2 0 .0000 0 .0000 139 1 1 .0072 1 .0072 64 0 .0000 0 .0000 .... ) .. ~ lJ1 N 0\ 527 ; cumulative TU regime in the Skagit River during incubation of the 1977 chinook year class. 3. The distribution of emergence around the mean in the above ex- periments to estimate TU's to emergence. Estimates of the timing of emergence were based on the assumption that all fry eoerge on the date on which the appropriate TU's are accumulated. Figure 8.76 shows the predicted pattern of emergence based on this method. However, experiments showed that emergence from individual redds occur over a protracted period. These experiments showed that for individual redds, emergence occurred over a period usually in excess of 20 days (Fig. 8.77). Further, the distribution was not normal, but rather uniform. Based on these experiments the distribution of emergence from individual redds was assumed to be uniform over a 24-day period. The period of egg deposition was broken into 10 weekly intervals. The egg deposition was assumed to be uniform within each week (Fig. 8.78A). The predicted distribution of emergent fry spawned in any given week would be the function shown in Fig. 8.78C. The function must be scaled so that the sum of the proportions emerging each day in the interval to-12 to t1+12 is equal to the proportion spawned during the week to to t1• The total distribution of emergence during spring 1978 was estimated by summing the predicted emergence distributions for each of the 10 weekly periods of egg deposition. Relevant parameters are shown in Table 8.112. The derived distribution is shown in Fig. 8.79. 8.3.3.3 Estimated Residence Time-Steady State Model. A rough estimate of mean residence time can be derived by regressing the logarithm of proportion of marked fish against time. If one assurn~s that the · abundance of fish in the study area is constant (i.e., a steady state situration where the number of newly emergent fry in any time interval is equal to the number of fry leaving the study area) then the fraction of marked fish will decline with time. This is due to dilution of the marked population by entering of unmarked emergent fry into the population. In this situation the fraction of marked fish will follow an exponential decline with rate of decline equal to the fraction of the population. disappearing during a unit of time. This argument more formally stated is as follows. Let Number of fish in the study area Mt = Number of marked fish in the population A -Rate of disappearance I Number of emergent fry entering the study area dNt - = I-AN dt t 2500 2250 2000 1750 (f) I- z1soo ::l w ~1250 a: a::: w ~1000 w I- 750 500 250 SPAWNING / / / / / / / / I I I I 1930 TU's I I I I I I J CUMULATIVE f %SPAWNED :~ I I I I I I I I I I / / I I / I I I ,' CUMUlATIVE. % EXPECTED ,y EMERGENCE I 15 20 25 31 - AUG SEP OCT. NOV DEC JAN FEB MAR AP~ MAY 1977 1978 Fig. 8.76 Timing and relative magnitude of chinook spawning and expected emergence J for 1977-1978 based on the accumulation of 1930 temperature units. Cumulative percent spawning and cumulative percent expected emergence are shown. J ,_, 100 90 80 70 60, fTI :::0 n 50~ -t :D VI 40 ~ N 00 30 20 10 0 JUN - ,. - - - """' - 529 Female #1-76, Skagit near Newhalem 100% 5 0 I I I I Female #3-76, Skagit near Newhalem 37% 5 -- 0 I I I I Female 114-76, Skagit near Newhalem 100% a 10 I.LJ -co 0:::: 0 V'l co ct ~ -I 5 0 >- :I: I-....... 3: >-0 I I c:::: Female lll-77, Ll.. Skagit near Newhalem 80% ~ 5 L 0 I 1 I I Female #3-76, Sauk 95% 5 - 0 I I I I 5 10 15 20 25 30 DAYS FROM ONSET OF YOLK ABSORPTION Fig. 8,77 Distribution of emergence (yolk absorption) for various in situ experiments. Numbers in the upper right corner of the figure indicate the total percentage of the yolk absorption observed. "0 Q) t::: ~ p. til >, til C"' 530 / ~ ~ ~----------------------------------------------------------------~ .... Q) ~ p. 0 p. 0 ~ p.. CD t::: ·n or; ~ Q) j;; CLl >, til C"' 0 ·n ~ .... CLl ~ p. 0 p. 0 ~ '""' I Time A -Temporal distribution of egg deposition within each weekly interval. r-r- r-h r-r- hl rh-, I I 1 t*-12 t* -12 t* t* te+l2 tf+l2 0 1 0 1 Time B-Predicted temporal pattern of emergence with inter•.1al of spawning broken into 7 units. I II III t*-12 0 t*-12 1 t*0+12 tf+l2 Time c-Limiting distribution, (i.e., the predicted pattern of emergence with the spawning broken into an infinite number of intervals). Fig. 8.78 A. The assumed time distribution of egg deposition within each week. B. The predicted distribution of emergence generated by breaking the interval of deposition into 7 one-day periods. C. The limiting distribution of emergence generated by breaking the interval of egg deposition into an infinite number of intervals. t 0 and t 1 are the endpoints of the interval of egg deposition. to* is the date on which an egg deposited on t 0 accumulates 1,930 TU's. t1* is the date on which an egg deposited on t 1 accumulated 1,930 TU's. ~-~ ~~ ; - ~ - 1 Table 8.112 Relevant parameters for each week of spawning. Proportion of population spawning Spawning during the to tl t * (Days after t * (Days after Interval period period 0 Nov. 1) 1 Nov. 1) Interval Endpoints weight 1 0.015 8/22 8/29 1/10 (71) 1/30 (91) I 59 79 10 II 79 83 4 III 83 103 10 2 0.095 8/29 9/5 1/30 (91) 2/23 (115) I 79 103 12 II 103 103 0 III 103 127 12 3 0.300 9/5 9/12 2/23 (115) 3/17 (137) I 103 125 11 II 125 127 2 l..n w III 127 149 11 f--1 4 0.230 9/12 9/19 3/17 (137) 4/3 (154) I 125 142 8.5 II 142 149 7 III 149 166 8.5 5 0.190 9/19 9/26 4/3 (154) 4/16 (16 7) I 142 155 6.5 II 155 166 11 III 166 179 6.5 6 0.065 9/26 10/3 4/16 (167) 4/28 (179) I 155 167 6 II 167 179 12 III 179 191 6 7 0.020 10/3 10/10 4/28 (179) 5/7 (188) I 167 176 4.5 II 176 191 15 III 191 200 4.5 Table 8.112 continued. Proportion of population spawning Spawning during the to tl t * (Days after t * (Days after Interval period period 0 Nov. 1) 1 Nov. 1) Interval Endpoints weight 8 0.030 10/10 10/17 5/7 (188) 5/16 (197) I 176 185 4.5 II 185 200 15 III 200 209 4.5 9 0.040 10/17 10/24 5/16 (197) 5/24 (205) I 185 193 4 II 193 209 16 III 209 217 4 10 0.015 10/24 10/31 5/24 (205) 5/31 (212) I 193 200 3.5 II 200 217 17 Ln w III 217 224 3.5 N 533 f ~ 2.0 - - 1.8 p~ 1.6 -1--z w u a:: 1.4 ,----- w -Q.. ........ >-a: 1 .2 Cl 1- a:: w Q.. 0 1 .a z -0 a:: .__ w 1:: .s w F"' z 0 --1--a:: .6 0 F"' Q.. - 0 a=: Q.. ..... .4 ;- ;-- !--1-- r- - 0 r----1 I I I I I I JAN FEB MAR APR MAY JUN Fig. 8.79 Estimated ,timing of chinook emergence, 1977-1978. 534 dM t -AM = dt t Thus: Mt M -At oe Number of recaptures of marked fish Ft =Instantaneous rate fishing mortality (removal) ct Catch of fry rt FtMt = FtMoe-H If I AN, then dN 0 dt ct FtN N is constant ct Ht rt - N rt 1 tA f1oe - ct N r--o At 1n-- N 1n(rt/c ) t To estimate At the instantaneous rate of dissappearance, one regresses the logarithm of t;Ct versus t. The results of these regressions are presented in Tables 8.113 and 8.114. 8. 3. 3.4 Estimated Residence Time -Sinulation f'A:odel. The assumption of constant population size necessary with the steady-state model is unrealistic because .of nonuniform patterns of fry emergence (Fig. P.79). To avoid this a more realistic model was constructed to simulate the results of the tagging experiment. The period of the ta?ging experiment was broken into time intervals. The number of fry in the population (Ni), the number of marked fry in the population (?li), and the proportion of marked fish in the population at the end of any given time interval are given by the following equations: where Number of fry in the population at the end of the ith time interval ..... - ~I ;-:~~~ 535 Table 8.113 Data used in the regressions of ln(Rt/Ct) versus t for the various stations and marks of the study. -Date t c r r/c ln(r/c) Yellow marks Ha:rblemount 3-8 444 10 0.0225 2 0.6794 r = 3-15 0 506 33 0.0652 -2.73 a -3.5277 3-29 14 1354 15 0. 0111 -4.50 i3 = -0.0510 4-5 21 1768 11 0.0062 -5.08 4-12 28 724 2 0.0028 -5.89 4-19 34 1135 10 0.0088 -4.73 4-21 40 570 2 0.0035 -5.65 5-2 47 511 1 0.0020 -6.24 5-9 54 769 3 0.0039 -5.55 5-16 61 350 0 0 5-23 68 205 0 0 6-1 77 161 1 0.0062 6-6 82 185 0 0 6-13 89 79 0 0 Green marks Marblemount { 2 4-19 1135 39 r = 0.6896 4-25 0 570 61 0.1070 -2.2348 a = -2.0899 5-2 7 511 57 0.1115 -2.1933 i3 -0.0292 5-9 14 769 61 0.0793 -2.5342 5-16 21 350 20 0. 05 71 -2.8622 5-23 28 205 16 0.0780 -2.5504 """ 6-1 37 161 9 0.0557 -2.8842 6-6 42 185 7 0.0378 -3.2744 6-13 49 79 1 0.0127 -4.3694 -6-20 56 84 3 0.0357 -3.3322 - - 536 Table 8.113 continued. Date t c r r/c ln(r/c) Countl Line lellow marks ~·1 3-10 345 29 2 0.9547 r = 3-17 0 676 89 0.1317 -2.0276 a. = -1.9413 ,...,., 3-28 11 505 28 0.0554 -2.8924 s = -0.0814 3-31 14 171 13 0.0760 -2.5767 4-7 21 694 20 0.0288 -3.5467 -4-13 27 1014 10 0.0099 -4.6191 4-24 38 1160 6 0.0052 -5.2644 5-2 46 228 0 5-10 54 445 1 0.0022 -6.0981 -' Countl Line green marks 2 ~! 4-24 0 1160 71 0.0612 -2.7935 r = 0. 7144 5-2 8 228 28 0.1228 -2.0971 a. = -1.9898 5-10 16 445 53 0.1191 -2.1278 s = -0.0472 5~17 23 277 22 0.0794 -2.5330 5-23 29 274 8 0.0292 -3.5337 6-1 38 176 2 0. 0114 -4.4 773 6-6 43 134 4 0.0299 -3.5115 ~ 6-13 50 2 0 0 6-20 57 139 1 0. 0072 -4.9345 6-27 64 56 0 0 - - ,-. Table 8.114 537 Mean residence times and rates of disappearance estimated using the steady-state model. Station Rate of disappearance Mean residence and mark (day-1 ) time (days) Marblemount yellow 0.0510 19.6 Marblemount green 0. 0292 34.3 County Line yellow 0.0814 12.3 County Line green 0. 0472 21.2 538 Ii = Number of emergent fry entering the population during the ith time interval A Rate of disappearance Mi = Length of the ith time interval Mi = Number of marked fry in the population U1i Number of fry marked during the ith time interval cR;c)i Proportion of narked fish in the population In this analysis the yellow and green marks were considered to be a single mark. The results of the Marblemount and County Line stations were each simulated. Three parameters, in addition to the marking data (Tables 8.110 and 8.111), and the patterns of emergence (Fig. 8.79) were required for the simulation model. The three parameters were: (1) the initial population size at the beginning of the tagging experiment, (2) the total number of emergent fry, and (3) the rate of disappearance. The initial population size was taken to be the Petersen population estimates at the start of the experiment (Table 8.115). In order to transform the pattern of fry emergence into absolute numbers of fry emerging in any given interval, one must know the total numbers of fry emerging. This value was taken to be that which yielded consistency between the model of outmigration (i.e.~ constant fraction migrating per unit time), and the initial population estimate (No)• That is, if the population size for any day k is -:>.. Nk = Nk-1 e . + Ik we want to find T (the total number of emerging fry) so that Nk on day t 0 is equal to the population size at the onset of the tagging population experiment estimated by tagging. To do so, we guess a value of T and starting at k = 1 we find Nk for each day of emergence until day to by the above equation. Based on a comparison of the derived value of Nto to the actual value we modify T until the two values agree. However, the rate of disappearance (A) was unknown in the simulation. Simulations were performed for a wide range of values for A, Twas estimated then the simulation performed with a correlation coefficient between predicted R/C (proportion of marked fish in the population) and observed R/C. The A which yielded the highest correlation, together with the simulation results, are given in Tables 8.116 and 8.117. These simulations provide estimates of mean residence time of chinook fry of 12.8 days for the County Line location and 22.8 days for the Marblemount location. These are average residence times estimated from the combined marking experiments with yellow and green marks. ..... - ~' ~I """" f ,_, r- ' - 539 Table 8.115 Petersen estimate of initial population size for the tagging experiments at Marblemount and County Line. Date M Marblemount 3/8 1969 County Line 3/10 2959 c 444 345 r 10 29 N 0 87423 36120 A Table 8.116 Results of simulation of the tagging-experiment at Marblemount station (>. = 0.0367, p = 0.7617, T = 476,701). Date on which Predicted Observed interval began I N. I. Ni M. IM. M. R/C R/C 1-1 1 1-1 1 1 3/8 1 87510 34799 102483 1696 1448 2760 0.0269 0.0650 3/15 2 102483 97247 158554 2760 2910 4561 0.0288 0.0110 3/21 3 158554 30032 152665 4561 0 3528 0.0231 0.0062 4/5 4 152665 44333 162412 3528 1321 4049 0.0249 0.0028 4/12 5 1.62412 30986 156602 4049 2158 5290 0.0338 0.0432 4/25 6 156602 19068 144 719 5290 3242 7486 0.0517 0.1105 Vl 5/2 .p.. 7 144719 16208 128140 7486 551 6341 0.0495 0.1135 0 5/9 8 128140 12394 111504 6341 0 4905 0.0440 0.0299 5/16 9 111504 10964 97206 4905 0 3794 0.0390 0.0571 5/23 10 97206 10011 851.94 3794 0 2934 0.0344 0.0780 6/1 11 85194 9057 70287 2934 0 2109 0.0300 0.0621 6/6 12 70287 2860 61364 2109 0 1755 0.0286 0.0378 6/1.3 13 61364 953 48415 1755 0 1358 0.0280 0.0127 6/20 14 48415 0 37446 1358 0 1050 0.0280 0.0357 . ] _J _j 1 1 Table 8.117 Results of the simulation of the tagging experiment at County Line station (\ 0.0661, p = 0.8442, T = 260,721). Date on which Predicted Observed interval began I N. 1 Ii N. M. 1 IM. M. R/C R/C 1.-1. 1.-1. 1. 3/10 1 36120 19033 41773 2759 2972 4709 0.1127 0.1317 3/17 2 41773 43019 63208 4709 596 2872 0.0454 0.0554 3/28 3 63208 9125 60964 2872 0 2355 0.0386 0.0760 3/31 4 60964 19033 57414 2355 0 1483 0.0258 0.0288 4/7 5 57414 20858 59475 1483 2527 3524 0.0593 0.0099 4/13 6 59475 22161 50906 3524 2970 4673 0.0918 0.0664 4/24 7 50906 10429 40428 4673 1771 4525 0.1119 0.1228 5/2 8 40428 7822 31647 4525 0 2667 0.0843 0.1213 5/10 9 31647 5736 25660 2667 0 1679 0.0654 0.0794 5/17 10 25660 4693 21952 1679 0 1129 0.0514 0.0292 5/23 11 21952 4954 17063 1129 0 623 0.0365 0.0114 6/1 12 17063 1564 13825 623 0 448 0.0324 0.0299 6/6 13 13825 521 9225 448 0 282 0.0305 0.0000 6/13 14 9225 0 5808 282 0 177 0. 0305' 0. 0072 6/20 15 5808 0 3657 177 0 112 0.0305 0.0000 V1 ~ ..... 542 Discussion There are two fundamental problems with the analyses of the Skagit River tagging study. First, the estimates of emerging fry are suspect. The pattern of emergence can be estimated, assuming uniform survival of eggs deposited during the spawning season. However, the accuracy of the estimate of absolute numbers of emerging fry cannot be checked. The second difficulty is that the results for the Marblemount and County Line stations differ, indicating that the marked fish are not randomly dispersed throughout the study area. The proportion of marked fi sl1 is higher for the County Line Station than for the ?larblel"lount Station. This may be due to greater population in the lower reaches of the study area or greater marking effort in the upper reaches. Using the lower value for the intial population size at County Line in the application of the simulation model attempts to correct for this discrepancy. Also, the estimated rate of disappearance is higher for the County Line Stat~on than for the Marblemount Station. However, this may simply reflect migration of marked fish into the Harblemount area. This would bias downward the estimate of disappearance rate and account for the lower rate at Harblemount. The actual rate of outmigration may, perhaps, be between these two values. The problem of not knowing the absolute numbers of emerging fry cloes not greatly affect the estimated rate of disappearance. This is because of the manner in which the model was initialized. Popefully, these unknowns were corrected by the estimate of No based on tagging. However, the estimated numbers of fry present throughout the study cannot he used with any degree of confidence, because we do not know with any confidence the number of marked fish in the sampling area. As salmon usually migrate downstream, we cannot assume uniform mixing of fish in the river between ~1arblemount and County Line. Lastly the correlation between the predicted and observed ratio of marked fish in the population was not very sensitive to ;... This suggests a high variance to the estimated value for A. The estimates of mean residence time of chinook fry in the Newhalern to Harblemount area of the Skagit River suggest that individual fry remained in the area about 15 to 30 days on the average. The implications of these results, if we accept them, are of considerable significance. They would indicate, for instance, that at least half the fry emerging on February 10 would have disappeared from the area by March 10. We woulcl expect, then, very few of these fry still present by early April. Our studies of growth of Skagit River fry show that the fry do not exhibit any significant increase in size until April, and seaward migration is assumed to peak so1newhat later in the spring. The seaward migration timing of chinook salmon fry in the Skagit River has not been determined in detail. However, townet sampling in Skagit Bay in 1970 and 1972 indicated that juvenile chinooks were not present in numbers until the latter part of Hay (Stober and Salo 1973). - - ~: ~' - f.·- - .... - 543 From this information we must conclude that few fry emerging in early February would remain in the upstream areas to achieve growth before migrating seaward in mid-to late-spring. Either the early-emerging fry die or gradually move downstream over a period of some three months. The evidence suggests that early-emerging fry have a much lower chance of survival to seaward migration, as might be expected because of the long interval between emergence and beginning of substantial increase in average size of fry. Additional examinations for fluorescent-marked fry was conducted in 1978 downstream of the marking area by Washington Department of Fisheries during their seining program to obtain chinook fry for marking by coded wire tags. Sampling was conducted primarily between Sedro Woolley and Concrete and from Harch 31 through June. Of the fish examined, 70 percent were captured in Nay. A small number of chinooks were sampled in this program in July and early August. Although numbers examined for fluorescent marks during the season are in unknown proportion to the population present, the relative ratios of recaptures of fry marked at different times during the emergence period are consistent with the idea that early emergent fry suffer higher in-stream mortality. In addition to the yellow-and green-pigment marked fish which were released in the same locations were marked in the Harblemount-County Line section, a third, red-pigment marked group was transported a distance from the capture locations and was not used in the retention-time experiments. This group will also be considered below. Downstream (below Concrete) recoveries from these releases were as follows: Color Dates of release Total Number Number recaptured released recaptured per release Yellow Feb 8-Har 17 6325 11 17 X w-4 Red Mar 28-Apr 7 8820 25 2R x 10-4 Green Apr 11-25 7260 33 45 X 10-4 While these data must also be used with caution because of the several sampling assumptions, they do indicate a lower recapture rate of the fry marked during the first period, an intermediate rate for the rlid- period, and the highest recapture rate for the fish marked last. Thus, the estimates of residence time of emerged chinook fry and the relative rates of recapture of fry marked at different times support the conclusion that fry emerging early in the season have a lower freshwater survival potential under present conditions of temperature and flow pattern than later emerging fry. 8.3.4.1 Future Work. In open populations where both emip,ration and mortality are occurring, it is not possible to distinguish between these two processes with tagp,inp, experiments. This is because ernip,ration and mortality both result in a reduction in the abundance of marked fish in the study area. 544 Estimation of abundance, rates of immigration, combined mortality and emigration rates can be obtained using multiple marking procedures (Seber 1974, chapter 5). Here different marks are introduced into the population during successive intervals of time. Based on differential rates of return for the various marks, the number of unmarked fish entering the population, population abundance, and combined rates of mortality and emigration may be estimated. It would be possible to conduct such a study in the Skagit study area. Fry are obtainable in sufficient numbers for reasonable accuracy. Seven different marks are available which would allow estimation of combined mortality-emigration for six time intervals and estimation of numbers of immigrating fry (emergence) during five time intervals. The above marking and interpretation of results would be greatly enhanced by a carefully designed system of downriver sampling to determine the movement of marked and unmarked fry through the river. It would then be possible to develop more precise estimates of the relative survival of fry emerging at different times of the season, and, thus, to determine whether or not the present river temperature regirn~n provides the most favorable development rate for survival. 8.4 Creek Surveys 8.4.1 Introductfon Studies of the fish populations in selected tributaries to the Skagit River above the proposed Copper Creek Dam site were conducted during August 1977. Data gathered included species composition, relative abundance, lengths, weights, and population estimates of the more abundant species. In addition, an informal survey was made in each creek to assess the present and potential accessibility to fish from the river and the proposed reservoir. This information will aid in estimating the impact of the proposed dam. 8.4.2 Study Sites Seven tributaries to the Skagit River above the proposed dam site were studied: Newhalem (RM 93.3), Goodell (RH 92.9), Thornton (RM 90.1), Sky (RH 88.2), Damnation (RM 87.7), Alma (RM 85.2), and Copper (RM 84.1) creeks (Fig. 1.1). 8.4.3 Haterials and Methods A Smith-Root Type VII backpack electroshocker was used to ca.pture fish for the creek surveys during the August 1977 low-flow period. A 100-ft long section in each of the streams (except Copper Creek where a 50-ft long section was sampled and Goodell Creek which was too large to sample by these methods) was blocked off at the upper and lower ends by small-mesh (1/4-inch bar) nets. Three passes were made through the - - - - - ·- 545 section with the electroshocker. All fish captured during each pass were held in separate containers for later identification, enumeration, and length and weight measurements. Fish poplations in the sections were estimated by the "removal method" outlined by Zippen (1958). Stream flows at the time of sampling were calculated following standard procedures except for Newhalem Creek where stream flow was determined from USGS and SCL data. The surveys to assess potential stream accessibility were informal in the sense that distances were generally estimated. The 495-ft elevation (proposed reservoir level) had been clearly marked by SCL survey crews. These marks were useful for evaluating major changes in stream accessibi- lity which might result from reservoir inundation. The length of stream to be inundated was estimated by measuring the distance from the mouth of the creek to the 495-ft level on a topographical map. The slope was esti- mated for that portion of the stream estimated to be inundated. 8.4.4 Results and Discussion The results of the surveys of fish populations (Table 8.118) and physical parameters (Table 8.119) in the tributary streams upstream of Copper Creek Dam site are discussed individually and jointly in the section that follows. 8.4.4.1 Newhalem Creek. Newhalem Creek is unique among the streams studied because of the presence of a power plant which is operated by SCL. A small dam diverts water ~o the powerhouse located approximately 1,500 ft east of the natural streal!lbed. ·.The natural stream was sampled; however, it should be noted that steelhead use the tailrace of the powe~house for spawning (qn June 2, 1977, two live steelhead and six carcasses were observed below the powerhouse). Approximately 800 ft of the natural steam will be covered by the proposed reservoir. The high falls 1,200 ft upstream from this point prevents fish migration at this time and will continue to do so. The estimated rainbow-steelhead trout population in the 100-ft sample section was 129 + 24. The estimated stream flow was 21.3 cfs. 8.4.4.2 Goodell Creek. Goodell Creek flows remained too high to permit effective sampling throughout the summer low-flow period. However, observations made during other investigations showed that rainbow-steel- head trout, Dolly Varden char, and cottids utilize the stream. A salmon spawning survey was made up the creek for a distance of ap- proximately 2 mi past the "group campground" on 12 October, 1977. A po- tential barrier to fish passage was noted near the end of the survey; however, one steelhead was seen above this area which showed that larger fish were able to get over at least during some flows. An estimated 2,000 ft of Goodell Creek would be covered by the proposed reservoir. Table 8.118 Creek Newhalem Thornton Sky Damnation Alma Copper 2 Summary of fish population surveys in 100-ft sections of Skagit River tributaries upstream of Copper Creek Dam site conducted during August, 1977. Rainbow-steelhead trout Number captured Mean Survey 1st 2nd 3rd Population Number length Other date Pass Pass Pass estimate 1 measured (mm) species 8-12-77 58 31 18 129 ± 24 107 48.5 8-11-77 12 4 2 19 ± 3 18 83.3 1 coho 1 dace 8-11-77 2 3 0 6 6 121.5 8-17-77 103 36 26 183 ± 17 163 61.4 3 cottids 8-19-77 63 20 8 96 ± 8 91 67.2 27 dace 36 cottids 1 coho 8-18-77 77 18 4 101 ± 4 97 47.1 1The confidence interval is± 2 standard errors which is approximately a 90% C.I. when the estimated population is between 50 and 200. A percent confidence is not determined for populations under 50 (Zippen 1958). 2 0nly a 50-ft section was sampled in Copper Creek instead of the 100 ft sampled in the rest of the creeks. V1 .so- C1' l ] Table 8.119 Summary of physical data for Skagit River tributaries upstream of Copper Creek Dam site. Creek Stream Dist. to Length length flow Slope migration to be Creek (mi)1 (cfs)2 (rise/run)3 barrier (ft) flooded (ft) Newhalem 8.8 21.3 1/32 2t000 800 Goodell 12.2 15,000 2,000 Thornton 4.2 14.5 1/5.3 1,650 800 Sky 1.1 0.66 1/3 300 Damnation 4.4 6.3 1/12 1,600 1,100 Alma 5.4 28.0 1/8.8 3,500 1,200 Copper 3.0 1.02 1/9.3 2,800 1,500 1williams, et al., 1975. 2Measured at time of fish population survey. 3Estimated for that portion of the stream to be inundated. % of stream to barrier flooded 40 13 48 69 V1 .1:'- 34 "'-l 54 548 8.4.4.3 was 19 + 3. captured. Thornton Creek. The estimated rainbow-steelhead population In addition, one coho salmon fingerling and one dace were This creek has a high falls (over 25 ft) above the 495-ft level within one-third mile of the mouth. This is presently and will continue to be a block to any upstream fish movement. The flow on the sampling date was 14.6 cfs. 8.4.4.4 Sky Creek. Sky Creek was with an estimated flow of 0.66 cfs. It little or no upward migration possible. estimate was six. Approximately 300 ft proposed reservoir. the smallest of the creeks sampled is a very precipitous stream with The rainbow-steelhead population of stream would be covered by the 8.4.4.5 Damnation Creek. The first potential migration block on Damnation Creek was a 6-ft drop approximately 500 ft upstream of the 495-ft elevation. There was a series of falls 8 to 12.ft high, three quarters of a mile farther upstream that probably would stop all but the largest fish. An estimated 1,100 ft of creek would be covered by the reservoir. The rainbow-steelhead population in the 100-ft sample section was 183 + 17. Three cottids were captured in addition to the rainbow-steelhead trout. The discharee was 6.4 cfs when the sanpling was done. 8.4.4.6 Alma Creek. There were several 4-to 6-ft drops above the 495-ft elevation which might prevent upstream migration by smaller fish. Approximately 1,200 ft of the creek will be covered by the reservoir. The rainbow-steelhead trout population in the study section was estimated to be 96 + 8. Fnough dace and cottids were captured in the study section to make population estimates which were 28 + 3 (2 S.E.) and 49 + 21 (2 S.E.), respectively. One coho fingerling was ilso captured. The-estimated flow during the sampling was 28.0 cfs. 8.4.4.7 Copper Creek. Copper Creek was rather low (1.08 cfs) when fish sampling was conducted. In fact, the creek disappeared underground about 400 ft from the mouth and was dry for that distance. There was a major migration block (a 20-ft high waterfall) about one-quarter mile above the 495-ft elevation. An estimated 1,500 ft of stream will be covered by the reservoir. A 50-ft section was sampled instead of the usual 100 ft because of the low flow. The rainbow-steelhead trout population in the 50-ft section was estimated to' be 101 + 4. 8.4.4.8 General Discussion. Length-frequency histograms were constructed for rainbow-steelhead trout captured in six Skagit tributaries (Fig. 8.80). Relatively large numbers of smaller fish (30-60 mm) were captured in Newhalem, Damnation, Alma, and Copper creeks, in contrast to Thornton and Sky creeks where relatively few were captured. The former "t - F"" f' - "'"' -.: """' -! ->< ~· •,.... - - ,.._ .. ~ fREQUENCY 549 PERCENT ~0 46 I 45 41 .1:) NEWHRLEM CREEK 37 ~5 N=to1 32 28 "'" 23 2o 18 15 n:h 14 lQ 9 ~ ~ 5 0 :] :a 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 so 278 45 2:0:0 40 THCRNTCN CREEK 222 35 1SS 30 N=18 167 25 139 20 tM 15 10 56 " ,........, 28 5 a 20 30 . 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 ""., 833 45 75C1 40 SKY CREEK 666 35 553 30~ N=6 500 2""~ 417 zc 333 15 250 tg 167 83 a 0 20 30 40 so 60 70 80 90 100 110 120 130 140 lSO 160 liD 180 190 200 210 31 29 OAMNAT!ON CREEK 2S 22 N•163 19 16 12 9 6 3 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 0 so 56 45 SCI 40 ALMA CREEK 45 -r: 39 ~-30 N=Sl 34 2:0: ~~ 20 ~'- 15 17 10 1~ " '"' 0 0 20 30 40 50 60 70 eo 90 100 110 120 130 140 150 160 170 180 190 200 210 so 43 r---------------------------------------------------------------~"52 40 35 - 30 25 zg L 1~ COPPER CREEK N=97 47 42 ""6 ~~ 21 16 1~ r-fh [ 0 30 40 50 ~~~~~~~~~~~_.~~~~._--~~~~~~._~~~~~~~._~ 0 20 60 70 60 90 100 110 120 130 140 150 160 170 180 190 200 210 LENGTH (MMI Figure 8.80 Length-frequency histograms of rainbow trout ln upper Skagit tributaries. 550 creeks had moderate to shallow slopes while the latter two creeks had steep slopes (Table 8.119). These fish were probably predominately steelhead and may indicate the utilization and spawning success of steelhead trout in these streams. The presence of fish larger than about 80 mm was particularly evident in Newhalem, Damnation, and Alma creeks which along with the presence of fry indicated a better balanced population. The populations in Thornton and Sky creeks were predominately larger fish while in Copper Creek it was made up of smaller fish. - ~. - - - - - 551 9.0 OTHER FISHES 9.1 Introduction Studies were conducted quarterly to survey the fishes other than salmon and adult steelhead trout residing in the mainstem Skagit River between Newhalem and Rockport. The fishes present included ones that were considered resident such as mountain whitefish (Prosopiurn williamsoni) and largescale sucker (Catostomus macrocheilus) and ones that can be either anadromotis or resident, such as Dolly Varden char (Salvelinus malma) and rainbow-steelhead trout (Salmo gairdneri). The objectives of the study were to determine species composition, relative abundance, and distribution of fishes other than salmon and adult steelhead trout in the mainstem Skagit River between Newhalem and Rockport and to assess the possible effects of the proposed Copper Creek Darn on these populations. Other species captured incidentally during sampling described in previous sections are also listed. 9.2 Study Sites Three reaches of similar length were sampled in the mainstem Skagit River: (1) the Newhalem area from river mile (RM) 92.0 to RM 88.6, (2) the r1arblemount area from RM 83.0 to RM 79.5, and (3) the Rockport area from RM 69.0 to RM 65.8 (Fig. 1.1) 9.3 Materials and Methods The fish samples were obtained by electroshocking. The Coffelt designed electrofishing boat equipment using the VVP-15 shocker driven by 3.5 kw, 230 v. gas powered generator was modified to fit the project's 17-ft aluminum boat. Fiberglass booms on each side of the boat were extended 5-ft beyond the bow of the boat. Cables at the end of each boom and electrically connected to the electro-shocker extended several feet into the water and functioned as the anode. Two cables wired to the other pole of the shocker were hung over the sides of the boat near the stern and served as the cathode. The voltage was kept as high as possible (usually around 550 v. D.C.) to overcome the high resistance of the Skagit River water. The direct current was pulsed at a rate of about 120 pulses per second and pulse width of 50-60 pe.rcent was used. The general procedure was to drift through the length of the.study reach moving from side to side in the river to sample a variery of habitat types. The boat operator was responsible for the control of the shocking, while the other member of the team stood in the bow of the boat and dipnetted the fish which were attracted to the anode. The captured fish were identified and counted and part of the catch (up to 40 whitefish, 10 largescale suckers, and any other fish which were caught) was taken to the field station. Fork lengths were measured to the nearest millimeter and weights were measured to the nearest hundredth of a gram (0.01 g) on the Mettler top loading balance for fish less than 552 1200 g. Fish weighing over 1200 g were weighed in a spring scale. Sex and maturity were determined for individual fish and the stomachs were removed and preserved in 10 percent formalin for later examination. The contents of the preserved stomachs were removed in the laboratory and examined with a binocular microscope. All identifiable contents were enumer<>ted and the results compiled. The sampling was conducted quarterly in June, August-September, and December, 1977, and March 1978. 9.4 Results and Discussion 9.4.1 Availabil~ Mountain whitefish (PrEsopi~~ ~~llia~son~) was the most abundant species captured and over-all comprised about 89 percent of the catch (Table 9.1). Largescale sucker (Calostomus macrocheilus) was next in over-all abundance at about six percent-~the catc~~ollowed by Dolly Varden char (Salvelinus malma) and rainbow-steelhead trout (Salmo gairdneri) which comprfsedlabout three and two percent, respectively, of the over-all catch. Mountain whitefish were readily available at the three sampling sites during June, August-September, and December, 1977. The significance of numerical differences in catch is not known since the sampling was not strictly quantitative. Factors such as discharge•(Table 9.1) and conductivity probably affected sampling ability •. ·However, there were no apparent trends to suggest that the distribution of mountain whitefish was other than proportional to river length during the 1977 sampling times. During the March 1978 sampling period no whitefish were captured at the Newhalem and Marblemount areas and only 11 were taken at the Rockport site. Whitefish were observed visually, however, in a deep pool (near RM 87.5) below the Newhalem sampling area. These fish remained beyond the effective range of the shocker. Pettit and Wallace (1975) observed that whitefish moved downstream to overwinter in deep pools at the North Fork Clearwater River in Idaho. It is not known whether or not Skagit River whitefish move downstream after spawning, however, it was apparent that they do move into deeper water. It is also of interest that all of the whitefish taken in the Rockport area came from the confluence of the Sauk and Skagit rivers rather than the usual riffle areas. Dolly Varden and rainbow-steelhead were generally captured at the three sites but in relatively low numbers (Table 9.1). Their distribution appeared to be fairly uniform between the three sites. Largescale suckers were not captured at the upper two sites, but were consistently taken during the four sampling periods at the Rockport sampling site (Table 9.1). - ~' _, -.~ Date 6/9/77 6/15/77 ~ 6/15/77 8/31/77 r-8/31/77 9/1/77 12/1/77 -12/2/77 12/5/77 f'l'lllol\ 3/21/78 3/22/78 3/22/78 - Table 9.1 553 Catch of non-salmon fishes at three sites on the Skagit River during 1977-1978. Catch Discharge Mountain Dolly Varden Rainbow-Largescale Location (cfs) whitefish char steelhead sucker trout Newhalem 2,110 46 1 0 0 Marblemount 3,960 38 1 1 0 Rockport 7.980 20 0 2 6 Newhalem 1,450 40 1 1 0 Marblemount 4,263 75 1 1 0 Rockport 3,845 49 1 2 11 New hal em 4,991 58 2 2 0 Marblemount 16,650 40 1 1 0 Rockport 13,310 48 2 0 5 Newhalem 3,370 0 1 0 0 Marblemount 5,060 0 1 1 0 Rockport 6,670 11 3 0 6 Total 425 15 11 28 554 Len~th and weight data are presented in Table 9.2 for mountain whitefish and in Table 9.3 for rainbow-steelhead trout, Dolly Varden char, and largescale suckers captured at three locations in the mainstem Skagit between Newhalem and Rockport. Whitefish lengths ranged from 100 to 357 mm (mean = 237.5 mm) and weights ranged from 11.21 to 502.81 g (mean 160.58 g). The mean length and weight of whitefish for the individual sampling periods in 1977 declined as the sampling progressed down river (Table 9.1). It is not known whether this was a real representation of the whitefish population or if it was an artifact introduced by sampling gear selectivity. The captured rainbow-steelhead trout ranged in length from 72 to 385 mm (mean length = 150.3 mm) and in weight from 4.04 to 695.32 ~ (mean weight = 92.56 g) (Table 9.3). Dolly Varden ranged in length from 137 to 547 mm (mean length = 416.3 mm) and in weight from 25.0 to 1,9R5 g (mean weight = 925.26 g). It seemed probable that both anadromous and resident froms of these two species were present in the samples but no attempt was made to differentiate them. Largescale suckers were, in general, more consistent in size than the two previously discussed species (Table 9.3) and ranged from 355 to 492 mm (mean length = 412.4 mm) in length and from 529.0 to 1,133.1 g (mean weight = 886.2 g) in weight. 9.4.3 Sexual Hatur_!!.l The sexual maturity data for mountain whitefish (Table 9.4) indicated that spawning took place in December. Information on the spawning times of the other species was sketchy due to the limited number of specimens captured in these studies. These fish probably spawn at times normal for their species: Dolly Varden char in the fall (September-November); rainbow-steelhead trout in the spring (April-June); and largescale suckers in the spring (April-June). S:eelhead trout (anadromous form) have been observed to spawn in the mainstem Skagit between March and June (Sec. 6. 4. 2. 5). 9.4.4 Diet The results of stomach content analysis for 345 mountain whitefish collected in 1977 and 1978 at three sites on the mainstem Skagit River are presented in Tables 9.5, 9.6, and 9.7. The column labeled "Freq. occur." represents the percentage of non-empty stomachs in a sample group that contained a certain prey organism. The column, "Total no.", gives the total number of individuals of the prey counted in the sample group. The column, "Range", indicates the minimum and maximum numbers of a prey organism in individual stomachs for a sample group. The next column, "%occur.", is the' percentage by numbers of the prey organism among all prey types encountered in the sample group. - - - Table 9.3 Length and weight data for fishes captured at three locations in the mainstem Skagit River during quarterly sampling in 1977 and 1978. Number Fork length(nun) Weight(g) Date Location Species sampled min. mean max. min. mean max, 6/ 9/77 Newhalem DV 1 428 950 6/16/77 Marblemount Rb-SH 1 82 6.42 DV 1 471 1372.11 6/15/77 Rockport Rb-SH 2 88 14 7 206 7.96 53.71 99.46 LSS 6 412 428 440 843.32 971.42 1081.72 8/31/77 Newhalem Rb-SH 1 145 33.17 DV 1 380 5U2. 86 8/31/77 Marblemount Rb-SH 1 99 10.11 DV 1 137 25.0 9/ 1/77 Rockport Rb-SH 2 111 112 113 14.25 15.36 16.47 DV 1 390 744.75 LSS 10 355 404.4 455 529.0 816.21 1115.98 \,.11 \,.11 12/1/77 Newhalem Rb-SH 2 72 228.5 a-385 4.04 349.68 695.32 DV 2 356 406.5 457 59 3. 9 7 795.34 996.70 12/2/77 Marblemount Rb-SH 1 218 106.43 DV· 1 235 148.49 12/5/77 Rockport DV 2 488 517.5 54 7 1220 1602.5 1985 LSS 5 377 417.2 492 716. 76 89 2. 9 3 1009.0 3/21/78 Newhalem DV 1 505 1130 3/22/78 Marblemount Rb-SH 1 134 24.56 - DV 1 411 770.69 3/22/78 Rockport DV 3 437 480 515 844.32 1146.44 1445 LSS 6 387 406 419 768.17 912.02 1133.1 Total Rb-SH 11 72 150.3 385 4.04 92.56 694.32 DV 15 137 416.3 54 7 25.0 9 25. 26 1985.0 LSS 27 355 412.4 492 529.0 886.20 1133.1 Rb-SH = Rainbow-steelhead trout. DV Dolly Varden char. LSS = Largescale sucker. 557 Table 9.4 Sexual maturity of Skagit River whitefish, 1977-78. DeveloEment stages Number 1 2 3 4 5 Date sampled sampled N % N % N % N % N % 6/9,15 M 30 30 100 1977 F 60 60 100 Unident. 4 8/31,9/1 M 58 8 14 50 86 1977 F 62 15 24 47 76 12/1,2,5 M 60 5 8 40 67 15 25 1977 F 60 14 23 3 5 37 62 2 3 1 2 ~ 3/21,22 M 6 2 33 2 33 2 33 1978 F 5 2 40 3 60 '""" Development stages: 1. Innnature -Gonads very small, individual eggs not distinguishable. 2. Maturing -Gonads increasing in size, will proba~ly spawn that season, individual eggs easily distinguished. 3. Mature -Gonads near maximum size, spawning imminent. -· 4. Ripe -Sexual products easily extruded. 5. Spent -Gonads deflated in appearance, residual eggs and milt may be present. - Table 9.5 Newhalem whitefish stomach contents. Date 6-9-77 8-31-77 12-1-77 3-21-78 Combined Freq. Totai Range % Freq. Total Range % Freq. Total Range % Freq. Total Range % Freq. Total % occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. Sample si::e 35 40 39 0 114 Ephemeroptera 97.1 1264 2-244 58.30 85.0 1693 1-443 44.41 53.8 141 1-70 21.73 78.0 3098 46.73 Plecoptera 51.4 62 1-14 2.86 77.5 712 . 1-129 18.68 74.4 102 1-'·7 15.72 68.4 876 13.21 Trichoptera 80.0 277 1-33 12.7.8 80.0 634 1-192 16.63 97.4 252 1-20 38.83 86.0 1163 17.54 Misc. Diptera 37.1 21 1-4 .97 17.5 27 1-17 .71 12.8 7 1-3 1.08 21.9 55 .83 Chironomidae 45.7 265 1-217 12.22 82.5 670 1-110 17.58 2.6 1 1 .15 43.9 936 14.12 Tipulidae 34.3 66 1-52 3.04 5.1 3 1-2 .46 12.3 69 1.04 Simuliid;:te 8.6 5 1-3 .23 2.5 4 4 .10 3.5 9 .14 Diaptomus 2.5 1 1 ·.03 .83 1 .02 IJ1 Sphaeriidae IJ1 Mise. Aquatics 20.0 9 1-3 .42 30.0 33 1-11 .87 2.6 1 1 .15 17.6 43 .65 00 Misc. Terrestrials 40.0 70 1-23 3.23 12.8 6 1-2 .92 16.7 76 1.15 Salmon eggs 15.0 33 1-11 .87. 48.7 67 1-19 10.32 21.9 100 1.51 Whitefish eggs 2.5 1 1 .03 35.9 20 1-4 3.08 13.2 21 .32 Unidentified eggs 17.1 124 1-74 5. 72 5.7 124 1. 87 Inanimate material 5.7 5 1-4 .23 2.5 4 4-4 .10 12.8 49 1-29 7.55 7.0 58 .87 J ] l l J --~ ' Table 9.6 Marblemount whitefish stomach contents. Date 6-15-77 8-31-77 12-2-77 3-21-78 Combined Freq. Total Range % Freq. Total Range % Freq. Total Range r. Freq, Total Range % Freq. Total % occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. Sample size 39 40 39 0 118 Ephemerop teri?, 84.6 1950 1-251 52.85 97.5 2369 1-760 60.81 51.3 1048 1-399 51.83 78.0 5367 55.86 Plecoptera 43.6 82 1-27 2.22 75.0 284 1-45 7.29 41.0 22 1-3 1.09 53.4 388 4.04 Trichoptera 92.3 270 1-37 7.32 87.5 378 1-112 9.70 71.8 270 1-104 13.35 83.9 918 9.55 Hiac. Diptera 10.3 7 1-4 .19 17.5 10 1-2 .26 17.9 9 1-2 .45 15.3 26 ,27 Chi ronomidae 64.1 812 1-629 22.01 75.0 366 1-79 9.39 30.8 41 1-13 2.03 56.8 H19 12.69 Tipulidae 46.2 291 1-163 7.89 2.5 1 1 .03 15.4 10 1-3 .49 21.2 '302 3.14 Simuliidae 20.5 17 1-5 .46 37.5 422 1-343 10.83 10.3 5 1-2 .25 22.9 444 4.62 Diaptomus 5.1 2 1 .10 1.7 2 .02 lJ1 lJ1 Sphaeriidae 5.1 19 1-18 .51 1.7 19 .20 \0 Misc. Aquatics 23.1 13 1-5 .35 35.0 34 1-8 .87 12.8 8 l-2 .40 23.7 55 .57 Misc. Terrestrials 25.6 18 1-8 .49 7.5 4 1-2 .10 12.8 15 1-7 .74 15.2 37 .39 Salmon eggs 10.0 28 2-17 .72 84.7 490 1-32 24.23 31.4 518 5.39 Whitefish eggs 43.6 64 1-12 3.17 14.53 64 .67 Unidentified eggs 15.4 106 1-75 2.87 5.13 106 1.'10 Inanimate material 43.6 105 1-21 2.85 20.5 38 2-7 1.88 21.2 143 1.49 Table 9. 7 Rockport whitefish stomach contents. Date 6-16-77 9-1-77 12-5-77 3-22-78 Combined Freq. Total Range % Freq. Total Range % Freq. Total Range % Freq. Total Range % Freq. Total % occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. Sample size 20 40 42 11 113 Ephemeroptera 100.0 1145 4-319 43.57 85.0 1853 1-315 42.19 52.4 162 1-89 13.15 100.0 70 1-12 1.71 77 .o 3230 26.14 Plecoptera 45.0 17 1-5 .65 32.5 73 1-39 1.66 59.5 187 1-64 15.18 45.5 9 1-3 .22 46.0 286 2.31 Trichoptera 95.0 329 1-86 12.52 95.0 658 1-58 14.98 81.0 207 1-53 16.80 63.6 13 1-3 .32 86.7 1207 9. 77 Misc. Diptera 15.0 3 1 .11 20.0 13 1-5 .30 31.0 25 1-3 2.03 21.3 41 .33 Chironomidae 80.0 421 1-145 16.02 90,0 1344 1-289 30.60 14.3 11 1-4 .89 100.0 3771 5-1119 91.89 61.1 554 7 44.89 Tipulidae 65.0 120 1-76 4.57 12.5 8 1-2 .18 11.9 12 1-6 .97 18.2 3 1-2 .07 22.1 143 1.16 Simuliidae 65.0 546 1-507 20.78 32.5 405 1-248 9.22 2.4 1 1 .08 90.9 202 1-129 4.92 32.7 1154 9.34 Diaptomus Sphaeriidae 9.1 1 1 .02 .9 1 .01 I.J1 0\ Misc. Aquatics 25.0 10 1-5 .38 22.5 16 1-4 .36 2.4 1 1 .08 45.5 22 1-15 .54 17.7 49 .40 0 Misc. Terrestrials 20.0 14 1-11 .53 10.0 5 1-2 .11 73.8 160 1-21 12.99 9.1 1 1 .02 35.4 180 1.46 Salmon eggs 17.5 17 1-4 . 39 6.2 17 .14 Whitefish eggs 57.1 56 1-7 4.55 21.2 56 .45 Unidentified eggs 15.0 12 3-5 .46 76.2 407 1-33 33.04 27.3 7 1-4 .17 33.6 426 3.45 Inanimate material 20.0 11 1-8 .42 4.8 3 2-2 .24 18.2 5 2-3 .12 7.1 19 .15 :f~ - - ~- .~ 561 Aquatic insects accounted for about 90 percent or more of the total number of food items in the stomachs of mountain whitefish captured at three sites on the Skagit River. The remainder of the stomach contents were composites such as watermites and calanoid copepods, terrestrial insects, fish eggs, and particles of inanimate material such as wood and rocks. In general the most frequently occurring food items (Freq. occur.) were Trichoptera, Ephemeroptera, Chironomidae, and Plecoptera. Members of the order Ephermeroptera accounted for the largest combined number of food items found in stomachs of whitefish captured in the Newhalem and Marblemount reaches followed by Trichoptera and Chironomidae at Newhalem and by Chironomidae and Trichoptera at Marblemount. For fish captured in the Rockport Reach, Chironomids were found in the largest numbers followed by Ephemeroptera, Trichoptera, and Simuliidae. The predominance of Chironomidae in the combined data for Rockport resulted from the heavy utilization of this insect group shown by fish collected in March 1978, (91.89 percent). This shift was probably related to the observation that whitefish were captrued in pools near the mouth of the Sauk River in March 1978, and not in the usual riffles as during other sampling times. Pool conditions with sandy bottoms and slower currents should favor chironomid production hence, their availability for whitefish residing in the pools. Another seasonal difference was observed during the salmon sapwning season when fish eggs made up a sizable proportion of the whitefish diets. This was particularly noticeable during the December 1977 sampling period. Dolly Varden showed a general preference for aquatic insects except during the salmon spawning season, when salmon eggs made up the majority of their diet (Table 9.8). This was evidenced at all three locations. Other items recovered from Dolly Varden stomachs included frogs, salamanders, and juvenile salmonids, and a sucker. 9.4.5 Incidental Species Other fish species captured incidentally during other fisheries investigations we were conducting in the study area are listed below: (a) brook trout (Salvelinus fontinalis) (b) threespine stickleback (Gasterosteus aculeatus) (c) sculpins (Cottus sp.)-confirmed Cottus aspe£, but may be others (d) longnose dace (Rhinichthys cataractae) (e) brook lamprey (Lampetra richardson!) There was a noted absence of cutthroat trout (Salmo clarki) in the study area. This included smaller tributaries to the Skagit River upstream of the Cascade River (RM 78.1) where sampling was conducted such as Newhalem, Goodell, Thornton, Sky, Damnation, Alma, Copper, and Diobsud creeks. Sampling conducted by Washington Department of Game (WDG) extending to lower Skagit tributaries found cutthroat trout only as far upstream as Miller Creek (RM 64.7) (WDG 1977, 1978). Table 9.8 Dolly Varden stomach contents. Samples from Newhalem, Marblemount and Rockport combined. Date: June 1977 SeEtember, 1977 December, 1977 March 1978 Combined Freq. Total Range % Freq. Total Range % Freq. Total Range % Freq. Total Range % Freq. Total Range 7. occur. no. occur. occur .. no. occur. occur. no. occur. occur. no. occur. occur. no. occur. Sal'lele sfze 2 3 5 5 15 Ephemeroptera 50.0 2 2 10.53 33.3 1 1 4.0 40.0 20 2-18 10.81 26.67 23 1-18 4.44 Plecoptera 50.0 1 1 5.26 20.0 85 85 45.95 13.33 86 1-85 16.60 Trichoptera 100.0 12 1-11 63.16 40.0 6 1-5 3.24 26.67 18 1-11 3.4 7 Diptera 20.0 1 1 .35 20.0 1 1 .54 13.33 2 1 . 39 Annelida 40.0 16 5-11 5.54 20.0 2 2 1.08 20.0 18 2-11 3.47 Anura 40.0 4 1-3 1.38 13.33 4 1-3 .77 Caudata 20.0 3 3 1.04 20.0 1 1 .54 13.33 4 1-3 .77 Misc. Terrestrials 100.0 2 1 10.53 20.0 1 1 .54 20.0 3 1 .58 Sucker 20.0 1 1 .54 6.67 1 1 .19 Ln Salmonid 0'\ N juveniles 50.0 1 1 5.26 33.3 1 1 4.0 60.0 19 1-10 6.5 7 33.33 21 1-10 4.05 Salmon eggs 33.3 23 23 92.0 100.0 246 1-121 85.12 40.0 269 1-121 51.93 Unidentified fish eggs 20.0 62 62 33.51 6.67 62 62 11.97 Organic material 50.0 1 1 5.26 40.0 2 1 1.04 20.0 3 1 .58 Inorganic material 20.0 4 4 2.16 6.67 4 4 .77 ~ j .) ! ] J -1 - - - ,.. .. I~ 563 10.0 SUMMARY AND CONCLUSIONS 10.1 Periphyton and Benthic Insects 10.1.1 Periphyton Periphyton in the Skagit, Sauk, and Cascade rivers was sampled along transects perpendicular to water flow at six-week intervals from October 1976 to November 1977. Two different sampling methods were employed. Artificial substrates were used through March 1977, and periphyton was collected directly from streambed rocks on subsequent dates. Samples were analyzed to determine chlorophyll~ content, and the percent exposure time during the six weeks prior to sampling was calculated for each sampler or sampling location. Results indicated that exposure to desiccation during flow fluctua- tions reduced the periphyton standing crop in the Skagit along the stream margins. The amount of periphyton, as indicated by chlorophyll~ content, on the artificial substrates during periods of hydroelectric peaking was related to the amount of time the substrates were exposed during dewatering, with a greater amount of periphyton on deepe~, less frequently exposed substrates. During the period of nearly stable flow in 1977, periphyton standing crop was usually greater in the Skagit than in the Sauk or Cascade rivers. The degree of water level fluctuation was similar in all three rivers and the higher standing crop in the Skagit was due to lower turbidity and possibly higher nutrient levels. Enhancement of periphyton growth below reservoirs due to turbidity reduction, discharge of nutrients from the hypolimnion, and stabilization of discharge has been noted frequently (Neel 1963). The stable flow regime during much of 1977, combined with the effects of turbidity reduction and any release of nutrients, resulted in optimal conditions for periphyton growth in the stream margins. Reduced fluctuation under the stable flow regime was beneficial to the periphyton in shoreline areas of the Skagit. A controlled flow regime in the future would most likely result in a similarly high level of periphyton standing crop. 10.1.2 Benthic Insects During 1976, benthic insects were sampled bimonthly in the Skagit, Sauk, and Cascade rivers from May through November. In 1977, samples were collected in the Skagit and Sauk in February and bimonthly from May to November. Samples were collected at three to four depths along permanent transects at the sampling stations using a modified Surber sampler. Insect density and community composition, as well as percent exposure time during the two weeks prior to sampling, were determined for each location on the transect. As a result of exposure during flow fluctuation, the density of benthic insects in exposed shoreline areas of the Skagit was reduced, and 564 the degree of reduction was related to exposure time. During the fluctuating flow regime of 1976, density at unexposed locations in the Skagit was similar to density in Sauk and Cascade in July. However, density at unexposed locations was lower in the Skagit in September. Community composition in shoreline areas of the Skagit was also affected by flow fluctuation. Species susceptible to stranding or intolerant to exposure to desiccation were eliminated or reduced in the marginal areas of the river. The resulting community composition was dissimilar to composition in deeper, unexposed areas of the Skagit and to composition in the Sauk and Cascade rivers. During the period of nearly stable flow from late April to mid- November 1977, density at the Skagit River stations was always greater than at the Sauk River stations. Benthic insect abundance at the Skagit Lower Station during July and September 1977 was six to nine times greater than at unexposed sample locations in July and September 1976, indicating that the reduction in flow fluctuation was extremely beneficial to the benthic insect community. During the stable flow period, stranding mortality and drift losses were reduced, and the beuthic insect community in the shoreline areas was unexposed for long periods. The enhanced periphyton standing crop may have also contributed to increased insect abundance. A reduction in water level fluctuation, either by manipulation of flow with existing hydroelectric facilities or by the proposed Copper Creek Dam, would be likely to have the same beneficial effect on benthic insect standing crop. 10.1.3 Experimental Studies Three species of aquatic insects from the Skagit River, representing the orders Ephemeroptera, Plecoptera, and Trichoptera, were tested in a series of experiments design~d to determine their ability to avoid becoming stranded during flow reduction and to survive desiccation on dewatered substrate. The density and composition of aquatic insect communities subjected to fluctuating and non-fluctuating flow regimes in an artificial stream were also compared. Results from the stranding experiments indicated that substantial numbers of insects, particularly mayflies (Ephemeroptera), may be stranded during flow reductions in the Skagit. The mayfly species tested was also more susceptible to desiccation on exposed substrate, indicating that mayflies are highly vulnerable to the effects of flow fluctuation. 10.2 Plankton Drift Because of the large number of unbroken, viable specimens collected in the tailrace stations and in the Skagit River below Gorge Dam, it was evident that crustacean zooplankton survived passage through the hydropower dams on the Skagit. - - ~' ·~ - ..... '· 565 There was zooplankton production in Diablo Reservoir in addition to zooplankton received from Ross Reservoir. However, because of the rapid flush time, Gorge Lake apparently added little to the plankton it received from Diablo Lake. Diablo Lake was probably the source of most of the zooplankton in the Skagit River below Gorge Powerhouse in 1977. Seasonal plankton abundance fluctuations at the Gorge Forebay Station and the stations downstream reflected the bimodal seasonal fluctuations of Diaptomus, Bosmina, and Daphnia densities in Diablo Lake more than they reflected the unimodal fluctuation of total crustacea observed in Ross Lake in 1972 and 1973 (SCL 1974.). However, discharge from Ross Lake was low most of the year and especially low from June through September. In a typical generation year, Ross Lake is probably the primary source of zooplankton at the river stations. The Diaptomus, Bosmina, and Daphnia densities at the upper river sites had peaks in May or June and another in the fall or winter. At the lower stations, this bimodal trend was damped out. In 1977, the timing of the peak utilization of zooplankton by Skagit chinook fry corresponded with the timing of peak plankton densities observed in 1976 while in 1975 and 1976 they did not. The peak occurrence of zooplankton in coho stomach samples occurred in August in 1976. Feeding on zooplankton by salmonid fry appeared sporadic and opportunistic. Zooplankton was available to salmonid fry as far downriver as the Concrete Station, about 37 river miles downstream of Gorge Powerhouse. 10.3 Relationships Between Skagit Flows and Chinook Salmon Returns The relationships between Skagit River flow during spawning, incuba- tion, and rearing of chinook salmon and the subsequent escapement and relative run size were investigated for the 1961 through 1972 brood years. No apparent correlations were observed. A clear-cut reduction in the frequency and magnitude of flow fluctua- tions was observed beginning in 1968. This reduction was not reflected, however, in the chinook escapement and relative run size data. Further analyses could be conducted to assess the possible interac- tions between flow conditions during spawning, incubation, and rearing and to test their influence in various combinations on relative run size. 10.4 Angler Survey Angler counts were compiled incidentally to other research activities in the study area between Newhalem and Rockport from June 1977 to January 1978. Angler utilization was relatively low in the Skagit River upstream of Marblemount compared to downstream areas. Utilization was highest in the vicinity of Rockport Steelhead Park. 566 10.5 Spawning_ 10.5.1 Spawning Depths and Velocities Depth and velocity were measured over active salmon and steelhead trout redds to determine the preferred spawning ranges. The SO-percent ranges of preferred spawning depths ann velocities for Skaf!it Piver salmon and steelhead trout were: chinook between 1.7-4.2 ft for depth and 1.8-3.7 ft/sec for velocity; pink between 0.9~2.5 ft for depth and 1.2-3.2 ft/sec for velocity; chum between 1.4~4.4 ft for depth and 0.2-3.0 ft/sec for velocity; steelhead between 0.9-2.9 ft for depth and 1.5-3.0 ft./sec for velocity. By comparison to literature values Skagit River chinook and pink salmon appeared to spawn in both deeper and faster water than the same species in most smaller streams. Depth seemed to be the less critical of the two criteria. The velocity range for Skagit River chum salmon compared favorably with that reported by another researcher while the depth range was higher and wider. For Skagit River steelhead trout the depth and velocity ranges were similar to those reported in the literature. 10.5.2 Timing of Spawning Boat and aerial surveys were conducted to determine the timing of spawning for Skagit River chinook, pink, and chum salmon, and steelhead trout. Summer-fall chinook salmon spawned from the last week of August through the end of October with peak spawning between September 4 and September 10. In comparison to other chinook populations in other systems, it appears that the timing of spawning for Skagit River chinook salmon was similar. Upon reviewing historical spawning records, no evidence was found that the spawning timing has undergone a change. Pink salmon spawned from the last week of September until the last week of October with peak spawning in the first two weeks of October. Chum salmon spawned from early November until late December with peak spawning during the first two weeks of December. Steelhead trout spawned from Harch to June, but peak spawning was not well defined. Skagit system coho salmon spawned from mid-October to mid-January (Williams et al., 197 5). Boat surveys of chinook spawning areas indicated that redds remained visible after construction for approximately 26 days on the average. 10.5.3 Spawner Distribution Aerial surveys were conducted over various river sections to determine the spawner distribution of Skagit River chinook (summer-fall) and pink salmon and steelhead trout. For the mainstem Skagit upstream of the Sauk River, the most heavily utilized section on a per-mile-basis was between Copper Creek Dam site and Cascade River for summer-fall chinook and pink salmon. The most heavily utilized section for steelhead upstream of the Sauk River was the section between the Cascade and Sauk rivers. - ~ I """" i ...., i - ..... ~. 567 These patterns, particularly for chinook and steelhead, were probably due in part to the influence of nearby fish hatchery and rearing facilities. Based on Washington Department of Fisheries (WDF) carcass recoveries, the most heavily utilized section for chum salmon spawning was between the Cascade and Sauk rivers. About 27.5 and 39.5 percent of chinook and pink salmon spawning, respectively, above the Sauk River took place above the Copper Creek Dam site. The 10.2 river miles above the dam site comprised 37.5 percent of the"river miles. Approximately 11 and 2 percent of chum salmon and steelhead trout spawning, respectively, above the Baker River, took place above Copper Creek dam site which comprised 27 percent of the river miles. The relatively high pink salmon utilization of the river section immediately downstream of Newhalem may be attributable to the presence of the Skagit dams. Through their operation, the peak flood flows were reduced which presumably increased the survival of incubating eggs and alevins. The spawner distribution upstream of Copper Creek Dam site as a proportion of that for the Skagit system was estimated using the above data for chinook, pink, and chum salmon and using other distribution data provided ·by WDF. An estimated 14, 30, and 7 percent of chinook, pink, and chum salmon spawning in the Skagit system took place above the Copper Creek Dam site. Based on accessible length of Skagit system tributaries and mainstem areas, a maximum utilization above the project site of 2.4 percent was estimated for coho salmon. Based on peak redd counts from four years, less than 1 percent of the steelhead redds in the mainstem Skagit and Sauk rivers were observed above Copper Creek Dam site. 10.5.4 Low Flow Observations Fluctuating low flows were observed to drive adult chinook salmon off their redds. The exposed chinook redds that were examined always had residual water in them beneath their surfaces. 10.5.5 Relationship of Spawnable Area to Discharge Detailed surveys of depth and velocity were conducted in four reference reaches over a range of stream flows. Each measurement of depth and velocity was classified with respect to the SO-percent preferred spawning ranges for each species. The areas that fell within these ranges were designated the estimated spawnable area. The calculated peak spawning flow was defined as the flow that provided the maximum amount of estimated spawnable area. The peak spawning discharge in the Skagit River upstream of Sauk River was 3,417 cfs for chinook salmon. The peak spawning discharge for pink and chum salmon and steelhead trout was 1,824 cfs. Theoretically these peak flows describe maximized conditions for spawning fish particularly if spawning area was limiting. However, we observed some 568 areas in our Skagit River reference reaches that were potentially spawnable based on depth and velocity, but were not utilized by spawning fish. The estimates made in this study of spawnable area were based on the two hydraulic parameters of depth and velocity. They did not include other such possibly influential and recognized factors as substrate size, light intensity, intragravel flow, upwelling, dissolved oxygen, and temperature (Bell 1973). Nevertheless, as key criteria, depth and velocity have been among the most widely used determinants of preferred spawning areas (Stalnaker and Arnette 1976) and have often been thought of as two of the most important (Chambers et al. 1955; Sams and Pearson 1963). 10.5.6 Potential Spawnable Area Detailed surveys of depth and velocity were conducted at 20 sample transects for estimation of potential spawning area available to chinook, pink, and chum salmon, and steelhead trout in the upper Skagit. It was estimated that there were 2,678 ft2 x 10J of potential spawnable area for chinook salmon at a medium flow, 1,843 ft2 x 103 of potential spawnable area for pink salmon at a low flow, 3,841 ft2 x 103 of potential spawnable area for chum salmon at a low flow, and 1,224 ft2 x 103 of potential spawnable area for steelhead trout at a low flow above the Copper Creek Dam site. Between the dam site and the Baker River it was estimated that there were 15,379 ft2 x 103 of potential spawnable area for chinook salmon at a medium flow, 7,104 ft2 x 103 of potential spawnable area for pink salmon at a low flow, 22,483 ft2 x 103 of potential spawnable area for chum salmon at a low flow, and 8,375 ft2 x 103 of potential spawnable area for steelhead trout ai a low flow. Fifteen percent at a medium flow, 21 percent at a low flow, 15 percent at a low flow, and 13 percent at a low flow, of the potential estimated spawnable area on the mainstem Skagit above the Baker River for chinook, pink, and chum salmon, and steelhead trout, respectively, occurred above the Copper Creek Dam site. The Skagit above the proposed darn site contained 9.3 ft2 x 103, 7.1 ft2 x 103, 14.8 ft2 x 103, and 4.7 ft2 x 103 of spawnable area per acre of wetted area for chinook, pink, and chum salmon, and steelhead trout, respectively. The Skagit between the dam site and the Baker River contained 11.8 ft2 x 103, 6.2 ft2 x 103, and 19.6 ft2 x 103, and 7.3 ft2 x 103, of spawnable area per acre of wetted area for chinook, pink, and chum salmon, and steelhead trout, respectively. The Skagit River above the Copper Creek Dam site was estimated to contain 263 ft2 x 103/mi of potential chinook salmon spawnable area at a medium flow, 181 ft2 x 103/mi of potential pink salmon spawnable area at a low flow, 377 ft2 x 103/mi of potential chum salmon spawnable area at a low flow and 120 ft2 x 103/mi of potential steehead trout spawnable area at a low flow. Between the dam site and the Baker River, it was estimated - - - - - ~. -~ ~· l, - - ,569 that there were 559 ft2 x 103/mi of potential chinook salmon spawnable area at a medium flow, 258 ft2 x 103/mi of potential pink salmon spawnable area at a low flow, 818 ft2 x 103/mi of potential chum salmon spawnable area at a low flow, and 305 ft2 x 103/mi of potential steelhead trout spawnable area at a low flow. Based upon the amount of potential spawnable area involved, it was concluded that the section of the Skagit River above the proposed Copper Creek Dam site was an important spawning area for the four species discussed. However, for its relative length, the Skagit River above the project site usually contained less potential spawnable area for chinook, pink, and chum salmon, and steelhead trout per river mile than did the other sections of the Skagit between the Copper Creek site and the Baker River. This uneven distribution was most pronounced for chinook and chum salmon, and steelhead trout, with 15, 15, and 13 percent, respectively, of their total estimated spawnable area above the Baker River occurring upstream of the proposed dam. It was less pronounced, though still apparent, with the distribution of the pink salmon spawnable area of which 23 percent of the estimated total occurred above the dam_ site. This was in spite of the fact that the river above the project site contained 27 percent of the total river miles studied. The method precludes making statements about the degree of significance of the numerical differences discussed. For chinook and pink salmon; however, the comparisons between potential and observed distribu- tion data were generally good. Comparisons were not made for chum salmon because dissimilar river sections were used for the two sets of data and agreement of these data was poor for steelhead trout. -. The findings of this investigation did not preclude the possibility that the 10.2 mi of river above the Copper Creek Dam site might provide a relatively superior quality and quantity of preferred spawnable area when compared to other sections of the Skagit River not examined in this study. Nor did the study findings preclude the possibility that fry production could be reduced in the Skagit below the Sauk River because of the excessive turbidity, even though the amount of potential spawnable area available to the adult salmon was large. 10.6 Incubation and Emergence The Skagit River temperature regime has undergone a change as a result of dam construction, but the magnitude of the change is not precisely known. The present temperature regime is warmer than the estimated pre-dam regime, during the fall and early winter when salmon eggs and alevins are incubating in the river gravels. 10.6.1 Chinook Salmon Under present temperature conditions embryonic development of chinook salmon in the Skagit River occurred from late August to May. An estimated 570 981 temperature units (TU) were required to mean hatching and about 1,930 TU's were required to mean yolk absorption. While completion of yolk absorption and emergence are not necessarily synonymous, their timing appeared to be similar under natural conditions. · Emergence was calculated to have occurred from mid-December or early January to late April or mid-May depending on temperature with peak emergence occurring from late January to early February. It appears that chinook fry do not delay in the gravel after yolk absorption because: 1) emergent fry were caught by electroshocking in early January; 2) fry held in incubation boxes past yolk absorption had.lower condition factors than natural f~y; and 3) a portion of the fry caught in emergent nets over natural redds still contained egg yolk. The developmental rate and TU requirments to hatching and yolk absorption were shown to be influenced by mean incubation temperature and egg size. The relationship with egg size was that the larger and heavier eggs required more TU's to yolk absorption than did the smaller and lighter eggs. Egg size and fry size were shown to be related; the larger the egg the larger the resulting fry. For eggs of similar size from a single female chinook the TU requirements were shown to be highly correlated to mean temperature during the incubation period. Confounding effects are pos·sible when. both factors vary simultaneously. The observed effects of mean incubation. temperature suggests that the developmental rate was altered ·by a compensating mechanism so that at higher temperature more TU's were required and at a-lower temperature less TU's were required. Such a mechanism would presumably improve fish survival by tending to maintain their emergence at a specific time of year when environmental conditions, food resources, etc., are more favorable. It does not appear that TU adjustment with higher temperature has been sufficient to shift emergence timing of Skagit River chinooks to that under pre-dam conditions since the first appearance of Skagit River chinook fry precedes that of Sauk and Cascade river fry by about one month. It is likely, however, that by TU adjustment the effect of temperature increases resulting from dam construction on the Skagit River has been dampened. Condition factor of chinook fry at or near mean yolk absorption ranged from 0.64 to 0.72 and compared favorably with the_minimum of those egressing from two Columbia River spawning channels. During the evolutionary development of these organisms the timing of emergence was presumably set to coincide with conditions favorable to their survival subsequent to emergence. Two of these factors, water temperature and food resource, are related to growth (Baldwin 1956, Brett et al. 1969, Brocksen and Bugge 1974), and presumably to survival. The apparent early emergence of Skagit chinook fry under the present regime appeared to present less favorable conditions, at least in terms of water temperature. Water temperature was still dropping when fry began to emerge in December 1976, and reached its minimum'in early March 1977, when an estimated 80-90 percent of fry had already emerged. - - - - - - 571 The relationship between emergence timing and food resource was not clear. Abundance of aquatic insects was at or near its minimum during the beginning of emergence in December 1976, then increased in February 1977. However, under natural flow conditions, such as in the Sauk River, emergence occurred during a period of generally declining aquatic insect density. Considering the generally low water temperature through this period food resource levels represented by aquatic insects may be of minor importance. Later emergence would seem to better coincide with improving temperature conditions and presumably would improve survival. A later emergence time than presently observed for Skagit chinook salmon could potentially reduce the losses due to fry stranding. Improved rearing conditions for later emerging fry may shorten the freshwater residence time or at least may allow the onset of growth at an eaFlier time. Either or both of these would probably reduce stranding losses. A more detailed discussion of factors influencing growth and fry stranding are presented in Sec. 8.0. 10.6.2 Pink, Chum, and Coho Salmon and Steelhead Trout The mean number of TU's required to mean yolk absorption was 1,692 for pink salmon incubated in the Skagit. Less TU's were required in the Cascade (1,388 TU's) and Sauk (1,614 TU's) rivers than in the Skagit, but there was a general synchronization in dates to mean yolk absorption at the three sites. This suggests that the developmental rate was altered by a compensating mechanism so that at lower temperature fewer TU's were required. Chum salmon required on the average 1,561 TU's in the Skagit while eggs from a single female required 1,244 TU's in the Cascade, and 1,486 TV's in the Sauk. Along with less TU's chum salmon eggs reached mean yolk absorption in a shorter time in the Cascade and Sauk rivers than in the Skagit which again suggests TU compensation. Coho salmon required 1,298 TU's to reach mean yolk absorption in the Skagit River. Eggs from Skagit churn and coho salmon were incubated at the Universi- ty of Washington Hatchery under constant temperature conditions. For chum salmon the mean number of TU's to mean hatching and mean yolk absorption was directly proportional to the mean incubation temperature. The pattern for coho was similar except that the TU requirements were nearly equal for eggs incubated at 45.3 and 43.0°F. There may have been too little dif- ference between these temperatures to cause changes in the TU require- ments. The incubation period under the post-dam elevated temperature regime was predicted to be from 4 to 11 weeks shorter for pink salmon, no change to 5 weeks shorter for chum salmon and 10 days shorter to 8· days longer for steelhead trout depending on which model (Burt 1973, or Sauk-Cascade) was used for pre-dam conditions. Coho salmon were not considered since 572 spawning and incubation occurs primarily in tributary streams, out of the influence of the Skagit Project. 10.6.3 Temperature Effects of Copper Creek Dam The maximum potential temperature effects on incubation period caused by Copper Creek Dam would be to lengthen the incubation period by about two weeks for chinook and pink salmon, and to effect little change for chum salmon and steelhead trout. 10.7 Fry Rearing 10.7.1 Fry Availability Except for preliminary estimates based on mark and recapture of chinook fry in 1978, no fry population estimates were made because of the difficulties of working with an open population. The interacting factors of emergence timing, immigration from tributaries and upstream mortality, and downriver migration, determine fry abundance at the study site. The temperature regime during incubation strongly affects the timing of first emergence. Warmer temperatures like those of the 1976-1977 in- cubation period advance emergence. Fry of summer-fall chinook in the Skagit, Cascade, and Sauk rivers begin emergence in December or January. Peak emergence is in January or February and emergence continues into May. Peak abundance along the river bars is normally in Harch or April. Emigration begins as early as March and upriver a~~ndance declines in Hay and June. Chinook fry are nearly absent from the study area by August. Mark-recapture studies suggest a mean residence time after emergence of less than one month. It appears that early emerging fry have much reduced probability of survival to the normal period of seaward migration. Fry of pink salmon begin emergence as early as January. Highest abundance is usually between mid-11arch and early Hay. Pink fry are more abundant in the mainstem Skagit than the tributaries~ They were absent from the sampling sites by late May. Fry of chum salmon are present at the sampling sites from mid-Febru- ary to early June. They were most abundant in April and May. Nearly all were caught in the mainstem Skagit River. Coho fry are present at the sampling sites all year. They first emerge from February to early April in the tributaries and appear at the Skagit River sites by April. They reside in the study area for 12 months or more. Fry of rainbow-steelhead trout first emerge from June to July. The fry remain in the study area for perhaps two years before emigrating. Some remain as residents, especially in the tributaries. - ~I .~ - - - 573 10.7.2 Fry Size and Condition after Emergence_ For chinook, rainbow-steelhead, and coho fry in our study area, there generally was an initial period after first emergence with little increase or even a decline in mean lengths, weights, and condition factors. Within each species, the size and condition at all sites were more similar during this period than during later periods. Because of the higher variability of condition factors, these data showed these trends less distinctly than lengths and weights. This initial level period is thought to be partially due to continual emergence of fry from the gravel through this period. By end of the initial level period, when mean lengths, weights, and condition factors started to increase, most of the fry population have probably emerged from the gravel. This point would be somewhat after peak emergence. This would place peak emergence of chinook, coho, and rainbow-steelhead before March, June, and August, respectively. In the winter-spiing of 1976-1977, warmer temperatures during incubation and early rearing, however, can advance the timing of first emergence and peak emergence, as seen in the 1976 brood of chinook fry and the 1977 brood of rainbow-steelhead fry. After the initial period of no size increase, there was a tendency for the Sauk River chinook, coho, and rainbow-steelhead fry in the broods monitored before 1977 to be larger and have higher condition factors than the fry from the Cascade or Skagit River except for rainbow-steelhead and coho fry in the fall. Fry from the Skagit River tended to be smallest and have the lowest condition factor. However, in 1977, chinook, coho, and rainbow-steelhead fry from the Skagit showed distinctly better size and condition cornpar~d to fry samples of previous-years and compared to fry from the Sauk River in 1977. Envi- ronmental factors associated with the unusually dry and mild 1976-1977 winter and spring contributed to this difference in fry size and condition. 1. In 1976 the Skagit River was cooler than the Sauk River from about March through September, through the chinook fry rearing period and the early part of the coho and rainbow-steelhead rearing period. For the rest of the year, the Skagit was warmer than the Sauk. Chinook, coho, and rainbow-steelhead fry from Skagit River samples at the Marblemount Station generally had lower size and condition than fry from the Sauk River. During the period late in the year when the Skagit River was warmer, rainbow-steelhead fry from th~ Skagit River caught-up in size and condition with fry from the Sauk River, while coho fry from the Skagit converged in condition factor only. In the Cascade River in 1976, chinook, coho, and rainbow-steelhead fry were generally larger after the initial level period than fry from the Skagit River despite generally lower temperatures in the Cascade River ex- cept for February, March, and April. In the fall, when Cascade River temperatures were much lower than Skagit temperatures, coho and rainbow- steelhead fry from the Skagit River tended to catch up in size and 574 condition to the fry from the Cascade Rivert but other factors besides temperatures appeared to keep fry size and condition low in the Skagit compared to fry from the Cascade River. In 1977 there was less difference in te~perature between the Sauk and Skagit rivers and less difference in size and condition of chinook fry in the two rivers than in 1976, except for the last three samples of very large fry from the Sauk River in 1977. The year-0 coho and rainbow-steel- head fry from the Skagit River in 1977 had distinctly better size than those from the Sauk River for much of the rearing period before the last months of the year. In 1977 temperatures in the Cascade River were generally cooler than those in the Skagit Rive.r and much cooler than those in the Sauk River with minor exceptions. Mean lengths and weights of year-0 coho and rainbow-steelhead from the Cascade River after the initial level period were generally less than for samples from the Skagit River at the Marblemount Station, but not clearly less than those from the Sauk River. It is apparent that temperature only partially accounted for the between-year and within-season differences between rivers in size and con- dition of juvenile salmonids. 2. The food supply in the Skagit River may be reduced due·to fluctu- ations and the resulting increased substrate exposure. Dam-related fluc- tuations clearly reduced periphyton and benthic insect standing crop in the Skagit River (Sec. 3.4.2.1 and 3.4.3.1). Although reduced flow fluctuations in 1977 were not in effect until late April (several months into the chinook fry rearing period), the reduced fluctuations may have resulted, in partt in the improved size and condition of chinook, coho, and rainbow-steel.head fry from the Skagit River in relation to Sank and Cascade river fry samples in 1977 compared to 1976. A lower percentage of empty stomachs in chinook fry stomach samples from the Skagit in 1977 than in 1976, suggests that more food was available in 1977. 3. The reduction in flow and flow fluctuation in the Skagit River from late April until Novembert 1977, also presumably allowed coho and rainbow-steelhead fry to establish and maintain feeding territories for longer periods of time than in 1976, which also would contribute to the better apparent growth conditions experienced in 1977. 4. Higher turbidity in the Sauk in 1977 appeared to play a role in decreased size and condition of chinook, coho, and rainbow-steelhead fry by reducing benthic production and probably by reducing feeding effici- ency. 5. There was probably movement of spring chinook fry from tributaries of the Sauk into or through the mainstem Sauk River sampling areas. The initiation of growth may be earlier for spring chinook fry since they emerge earlier than summer-fall chinook fry. The extent and timing of migration and the growth pattern for spring chinook fry are not well defined. 6. The interaction of several of the above factors, notably, temper- ature, turbidity, flow level, and flow fluctuations, may be responsible - - ;~ - 575 for the divergence in fry size and condition between the river sites. Pink and chum salmon fry were also sampled for size and condition, but the small sizes of the catches prevent the development of strong inferences about peak emergence timing and differences in size and condi- tion between sites. 10.7.3 Fry Diet Aquatic insects are the rr.ost important component by number in chinook, chum, pink, coho, and rainbow-steelhead fry diets in the Skagit River below Gorge Dam, the Sauk River, and the Cascade River. Chironomids and Ephemeroptera nymphs are the two most important groups of aquatic insects. Zooplankton utilization by chinook fry in the Skagit River was lower in 1977 when. increased solar radiation and decreased flow fluctuations stimulated higher benthic insect production than in 1976. A higher per- centage of the chinook fry diet in samples from the Skagit River in 1977 compared to 1976 consisted of Simuliidae larvae, Ephemeroptera nymphs, and Plecoptera nymphs. Despite higher fry densities in the Skagit in 1977, a smaller percentage of empty chinook fry stomachs were found in 1977 than in 1976. The apparently better feeding conditions, as well as warmer temperatures during incubation and rearing, may have caused improved size and condition factors of Skagit chinook fry in 1977. However, despite im- proved size and condition factor through the rearing period of chinook fry captured in the Cascade River in 1977, there was a larger percentage of empty stomachs in 1977 in the small sample examined. 10.7.4 Fry Stranding Water level fluctuations caused by fluctuations in power generation at Gorge Dam can result in the stranding of salmon fry in the upper Skagit River. The estimated total fry mortality due to stranding between Gorge Powerhouse and The Sauk River for 1977 was 540,000.· For several reasons, we consider this an overestimate. Comparisons of stranded fry and unstranded fry from 1976 and 1977 surveys indicated that stranding was selective for fry with higher condition factor. However, when the data were adjusted for changes in the fry due to stranding and handling, no significant differences in condition factor between stranded and unstranded fry were found. Of the many factors involved in stranding, the rate of flow reduction (ramping rate) and the level of minimum flow were suspected as being most important. Analyses of these factors indicated a correlation between stranding mortality and both ramping rate and the level of minimum flow. Experiments in a controlled flow channel suggested that learning experience, or the age of fry, may influence the stranding rate. The experiments failed to find evidence linking the duration of steady flow 576 prior to flow reduction to stranding rate or to find evidence that stranding is size selective. 10.7.5 Residence Time of Chinook Salmon Fry Estimates of mean residence time for newly emergent chinook salmon fry in the Skagit River between Newhalem and Marblemount were developed from data on timing of egg deposition and emergence as well as a mark recapture experiment that introduced a large number of marked fish in the study area with subsequent recovery effort at two sites, Marblemount and County Line. Two methods of estimating residence time were developed. The first used linear regression and assumed a constant population size (in a steady state). The second method used a simulation model with more reasonable assumptions. The model simulated the proportion of marked fish in the population during the study period based on the temporal pattern of fry emergence and rate of disappearance. The rate of disappearance (outmi- gration and mortality) which gave the highest correlation between predicted proportion of marked fish and observed proportion of marked fish in the population was taken to be estimated disappearance rate. The estimates of mean residence time of chinook fry in the Newhalem to Marblemount area of the Skagit River suggest that individual'fry remained in the area about 15 to 30 days on the average. The implications of these results, if we accept them, are of considerable significance. They would indicate, for instance, that at least half the fry emerging on February 10 would.pave disappeared from the area by March 10. We would expect, then, very few of these fry still present by early April. Our studies of growth of Skagit River fry show that the fry do not exhibit any significant increase in size until April, and seaward migration is assumed to peak somewhat later in the spring. From this information we must conclude that few fry emerging in early February would remain in the upstream areas to achieve growth before mi- grating seaward in mid-to late-spring. Either the early-emerging fry die or gradually move downstream over a period of some three months. The evidence suggests that early-emerging fry have a much lower chance of survival to seaward migration, as might be expected because of the lone interval ·between emergence and beginning of substantial increase in average size of fry. 10.7.6 Creek Surveys Rainbow-steelhead trout were the predominant species captured in six Skagit tributaries upstream of Copper Creek Dam site. Hhile no attempt was made to differentiate resident from anadromous fish, both forms were presumably present. The major impact of the Copper Creek Dam on the resident game fish populations in the.tributaries would be the loss of lower portions of the accessible flowing stream habitats. These losses would range from 300 ft - - - - - ~' - ·- - - 577 in Sky Creek to 2,000 ft in Goodell Creek. There will be no changes in the accessibility within the streams; that is, resident populations presently isolated from fish in the river will continue to be isolated from fish in the proposed reservoir. The slopes of these streams are steeper above the inundation level than below except for Goodell Creek where the slope remains relatively low for some distance upstream. The precipitous nature of the creeks, the presence of probable migration blocks near the mouths, and the very limited amount of suitable substrate will eliminate all of the creeks but Goodell Creek as potentially important spawning and rearing areas for fish from the reservoir. Goodell Creek is presently utilized by salmon and steelhead for spawning and rearing and it could be expected that it would be suitable for trout living in a reservoir. Upstream migration of anadromous fishes will be blocked by Copper Creek Dam. These losses are discussed in Sec. 11.0. 10.8 Other Fishes Quarterly sampling was conducted in the mainstem Skagit for fishes other than salmon and adult steelhead trout. Mountain whitefish was the most abundant species captured comprising about 89 percent of the catch followed by largescale sucker ·(6 percent), Dolly Varden char (3 percent), and rainbow-steelhead trout (2 percent). The distribution of mountain whitefish appeared to be proportional to river length except during winter when they were captured only at the Rockport site. However, they were observed visually in upstream areas during winter but were outside the effective range of our sampling gear. They may exhibit a downstream migration pattern in winter or at least a movement to deeper areas in the river. Distribution of Dolly Varden char and rainbow-steelhead trout appeared fairly uniform while largescale suckers were captured at the Rockport site only. The sexual maturity data indicated that whitefish spawning occurred in December. Spawning times were not determined for the other species but they probably spawn at times normal for their species. Aquatic ins~cts accounted for the majority of food items in the stomachs of mountain whitefish. They showed a tendency to consume proportionately more chironomids during the winter probably related to a change in habitat at that time. Fish eggs were consumed by whitefish particularly during the fall salmon spawning season. Dolly Varden char primarily utilized aquatic insects except during the fall when salmon eggs dominated their diets. Juvenile salmonids and a sucker also appeared in the stomach contents of Dolly Varden. Other species captured incidentally to other sampling were (1) brook trout, (2) threespine stickleback, (3) sculpin, (4) brook lamprey, and (5) longnose dace. There was a noted absence of cutthroat trout in Skagit tributaries within the study area. 578 -, - ~. - - - - - - - 579 ll.O IMPACT 11.1 Copper Creek Project 11.1.1 Periphyton and Benthic Insects The Skagit Lower Station was representative of the river between the prpposed Copper Creek Dam site and the mouth of the Sauk River. Environmental conditions were different below the Sauk, due to increased turbidity and smaller substrate size. The Skagit Upper Station, located about 1 mi above the Copper Creek Dam site, was representative of the river above the proposed dam, except for the river immediately below Gorge Powerhouse. Based on data from these two Skagit stations, mean annual standing crop· per-unit-area was equal above and below the dam site in 1977. Mean chlorophyll a content of sam~les collected during May through November 1977, was 3.12 mg/m at the upper station and 3.17 mg/m2 at the lower station. Standing crop per-unit-area was higher at the lower station during May and June, but higher at the upper station during July, September,. and November. Hean annual standing crop above and below Copper Creek was estimated by two methods, resulting in minimum and maximum estimates (Table 11.1). Areas of the river deeper than 1.5 ft could not be sampled. It was assumed that standing crop in these areas could be as low as zero grams chlorophyll ~ per-unit-area, but no greater than standing crop in areas 1.5-ft deep. The minimum estimates (method 1) were derive~ by multiplying wetted area between 0.0-and 1.5-ft deep by the appropriate standing crop per-unit-area value, 3.12 mg/m2 for river sections above Copper Creek, and 3.17 mg/m2 for sections below. Standing crop in areas deeper than 1.5 ft was assumed to be zero. The maximum standing crop value for a particular section of the river was the sum of the minimum value and an estimate of standing crop in areas deeper than 1.5 ft (method 2). This estimate was derived by multiplying wetted area deeper than 1.5 ft by the mean annual chlorophyll~ content of samples collected at locations 1.5-ft deep. The amount of periphyton that would be lost varied with the discharge level and method of calculation. It ranged from a minimum of 0.63-0.98 kg chlorophyll ~ to a maximum of 3.26-4.27 kg. Standing crop calculated by the second method was mainly a function of total wetted area, or discharge. However, standing crop calculated by the first method was a function of the wetted area between 0.0-and 1.5-ft deep, which depended on the shape of the riverbed and did not necessarily increase with increasing discharge. When calculated by the first method, maximum chlorophyll a was available at low discharge above Copper Creek and at medium discharge below Copper Creek. Table 11.1 Mean annual (1977) periphyton standing crop, as indicated by amount of chlorophyll a, in the Skagit River between Gorge Powerhouse and the Sauk River at low-(L), medium (M), and high (H) discharge. The percentage of Estimate Minimum Maximum the total standing crop above and below Copper Creek is also shown for each discharge level. Two methods were used to calculate standing crop and results are shown separately as minimum and maximum estimates. River section Gorge Powerhouse -Copper Creek Copper Creek -Cascade River Copper Creek -Sauk River TOTAL (Gorge Powerhouse -Sauk River) Gorge Powerhouse -Copper Creek Copper Creek -Cascade River Copper Creek -Sauk River TOTAL (Gorge Powerhouse -Sauk River) Chlorophyll g (kg) L M H 0.98 0.83 0.63 0.45 0.37 0. 35 1.38 1.57 1.18 2.36 2.40 1.81 3.26 3.63 4.27 1. 75 1.83 2.13 6.13 6. 77 7.29 9.39 10.40 11.56 J Percent of total standing crop L M H 42 35 35 58 65 65 35 35 37 65 65 63 U1 CXl 0 - - - - - - - - 581 The percentage of total standing crop above and below Copper Creek indicated the changes in relative productivity at different flows. Of the total river mileage between'Gorge Powerhouse and the Sauk River, 37.5 percent lies above Copper Creek and 62.5 percent below. The first method indicates that the section above Copper Creek is more productive per river mile than the section below at low discharge, since it contains 42 percent of the standing crop, but only 37.5 percent of the length. At other discharges, and at all discharges using the second calculation method, the section below Copper Creek is relatively more proquctive. Benthic insect standing crop per-unit-area was slightly higher in the river below Copper Creek than above during 1977. Mean density during May through November was 4,951 insects/m2 at the upper station and 6,252 insects/m2 at the lower station. Mean annual benthic insect standing crops (Table 11.2) were estimated using the same procedure used for calculation of the periphyton standing crops. Benthic insect density values were simply substituted for the chlorophyll per-unit-area valu~s. There is evidence that benthic macroinvertebrate density decreases with increasing water depth and velocity. Needham and Usinger (1956) found that the abundance of most aquatic insect genera was several times greater in shallow, slower moving water of an unregulated stream than in the deeper, faster moving water at midstream. Kennedy (1967) reported that benthic macroinvertebrate density in Convict Creek, California, was highest at depths of 4-5 inches (686 organisms/ft2) and decreased steadily as depth increased. Density was lowest at 11-12 inches (114 organisms/ft2), the deepest location sampled. During July and September 1977, when discharge was relatively stable, benthic insect density was always highest at the 6-inch deep locations at both Skagit River stations. Density decreased with increasing depth, and was usually lowest at 1.5 ft. This trend of declining density probably continued beyond depths of 1.5 ft, resulting in much lower density in midstream areas than in the shoreline areas that were 1.5 ft deep. Therefore, the actual standing crop is probably closer to the minimum estimate in Table 11.2 than to the maximum. The estimated standing crop of benthic insects that would be lost due to construction of the proposed Copper Creek Dam is shown in Table 11.2. Predicted losses ranged from a minimum of 1.57 x 109 -1.00 x 109 to a maximum of 4.28 x 10 9 -5.35 x 109 insects. When calculated by the first method, standing crop above Copper Creek and between Copper Creek and the Cascade River was highest at low flow. In the section below Copper Creek, standing crop was greatest at medium flow. The section of river below Copper Creek was as productive, or more productive per ~iver mile than the section above Copper Creek, regardless of the method of estimation. The capacity for benthic i~sect production below Copper Creek is related to the type of £low pattern. Benthic insect standing crop was reduced under the fluctuating flow regime in 1976 and enhanced during the relatively stable flow period in 1977. Benthic insect density in areas Table 11.2 Mean annual (1977) benthic insect standing crop in the Skagit River between Gorge Powerhouse and the Sauk River at low (L), medium (M), and high (H) discharge. The percentage of the total standing crop above and below Copper Creek is also shown for each discharge level. Two methods were used to estimate standing crop, and results are shown separately as minimum and maximum estimates. Estimate Minimum Maximum River section Gorge Powe~house -Copper Creek Copper Creek -Cascade River Copper, Greek -Sauk River TOTAL (Gorge Powerhouse -Sauk River) Gorge Powerhouse -Copper Creek Copper Creek -Cascade River Copper Creek -Sauk River TOTAL (Gorge Powerhouse -Sauk River) Standing crop (Individuals x 109 ) L M H 1.57 1. 33 1.00 0.89 0.73 0.69 2.73 3.10 2.32 4.30 4.43 3.32 4.28 4.67 5.35 3.03 3.13 3.62 10.56 11.66 12.40 14.84 16.33 17.45 Percent of total standing crop L M . H 37 30 30 63 70 70 29 29 30 71 71 70 J lJ1 co N r ill:lilU'.\ - ,~ - - 583 unexposed during th two week period prior to sampling was as high as 1236 insects/m2 during 1976. Density in exposed areas was always lower than in the unexposed areas. When this maximum density value for fluctuating flow conditions was multiplied by the wetted area 0-1.5 ft deep between Copper Creek and the mouth of the Sauk River~ total standing crop estimates of 0.54 x 109, 0.61 x 109, and 0.46 x 10~ insects were obtained for low, medium, and high flows, respectively. These estimates are considerably lower than the minimum estimates for stable flow conditions of 2.32 x 10 9 to 3.10 x 109 insects shown in Table 11.2. The benefits of flow control in the Skagit were evident during the period of relatively stable flow from late April to mid-November. Both periphyton and benthic standing crops were high when compared with standing crops in the Sauk and Cascade. Benthic insect standing crop in unexposed areas of the river was higher under stable flow conditions in 1977 than under fluctuating flow in 1976. Controlled flows in the future would most likely have the same effect. 11.1.2 Plankton Drift Copper Creek Reservoir will be similar in volume and retention time to Diablo Reservoir (Table 2.4). The extent of stratification could be as high as that found in Diablo Reservoir •. During moderate to low flows in August, September, and October (Table 11.3), fairly long retention times were predicted and would allow plankton production in addition to the biomass received from upstream as in Diablo Reservoir. Preliminary dr~ings of Copper Creek Dam indicate power tunnel intakes 110 ft below the full pool elevation, compared to 125 ft in Diablo Dam. If Copper Creek Reservoir stratifies, it is likely that zooplankton will be concentrated in the epilimnion, and avoid entrainment to some degree, extending the plankton retention time longer than the average water retention time and allowing more plankton development. Like the other reservoirs, some zooplankton will probably be released from Copper Creek Reservoir which could augment the diet of salmonid fry downstream. The amount and seasonal timing is difficult to predict from the data collected in the atypical, low-flow year of 1977. 11.1.3 Spawning Area Construction of Copper Creek Dam will remove the 10.2 mi of the mainstem Skagit and associated tributaries upstream of the site from access to adult anadromous salmonids. Based on recent escapement levels and observed spawner distribution data, the estimated loss of that portion ... of the spawning population from the Skagit Basin would amount to 14 percent for chinook salmon, 30 percent for pink salmon, 7 percent for chum salmon, and less than 1 percent for steelhead trout. A maximum estimate of loss for coho salmon was 2.4 percent based on accessible length data. Based on average escapement this would translate to approximately 2,000 adult chinook, 100,000 adult pinks, 2,600 adult chum, Table 11.3 Predicted average monthly discharge from proposed Copper Creek Reservoir in acre-ft based on USGS records of Skagit River discharge at Alma Creek, 1951-1976, and average retention time in days calculated from full pool storage capacity of 123,000 acre-ft. Month Jan Feb Mar Apr May Jun Jul A up; Sep Oct Nov Dec discharge 357,738 307,862 303,515 298,996 356,754 504,004 508,673 291,307 211,123 279,750 334,715 366,954 (acre-ft) retention 10.66 11.29 12.56 12.34 10.69 7.32 7.50 13.09 17.48 13.63 11.02 10.39 time (days) -~ - - i~ - ,_ 585 and 370 adult coho. Escapement estimates are not available for steelhead trout. Chinook, coho, and steelhead production is probably not limited by spawning area in the Skagit River. This is based on the observed densities in our reference reaches and in the Skagit River as a whole and upon the early life history of the juveniles which rear in the Skagit for a period of time before migrating to salt water. For summer-fall chinook salmon it is unlikely that a racially distinct stock was present above the Copper Creek site, but we have no evidence either way. The river sections downstream of the project site could probably accommodate those chinook, coho, and steelhead adults which weuld have spawned above the project site. Because pink and chum juveniles do not rear for an extended period in fresh water, spawning area may be limiting for the adults. This is especially true in the upstream areas for pink salmon which utilized it so heavily. Because of the partial protection provided by the present dams., the area i-mmediately downstream of Newhalem acts as a buffer against flood. flows. As natural inflow is added progressively downstream, this protection is reduced. A significant portion of this would be lost with construction of Copper Creek Dam. 11.1.4 Incubation and Emergence It was predicted that the downstream temperature regime resulting from construction of Copper Creek Dam and Reservoir would either change very little or shift slightly toward predicted pre-dam condition. The maximum potential effects would be to lengthen the incubation period by about two weeks for chinook and pink salmon and to effect little change for chum salmon and steelhead trout. 11.1. 5 Fry Rearing. Copper Creek Dam would inundate potential rearing areas along 10.2 mi of the mainstem Skagit River, in the mouths of tributaries between Newhalem and Copper Creek Dam site, in the Newhalem Ponds, and in the County Line Ponds. Freshwater rearing area is not an important consideration in the production of pink and chum salmon fry. These two species spend little time in upstream areas after emergence. However, chinook, coho, and rainbow-steelhead spend a considerable portion of their early life feeding in freshwater. Zill~es (1977) used several methods to estimate production of coho smolts in different types of freshwater environments. In streams less than 6 yd wide, the number of potential smolts was calculated by multiplying the available rearing area in yd2 by 0.42 smolts/yd2, the 586 highest density found by Chapman ( 1965) in small Oregon streams. In larger streams, the smolt production was calculated by multiplying the accessible length in yards by 2.5 smolts/linear yd, the figure found by Lister and Walker (1966) for the Big Qualicum River. For lakes and reservoirs accessible to coho, the smolt production was calculated by multiplying the yards of shoreline by 1.25, the number of smolts per linear yard on one river bank. Using Zillges' (1977) methodology, we estimated the coho smolt production potential for the area above river mile (RM) 84 to be 58,887 smolts (Table 11.4). This is 4.0 percent of the potential smolt production we estimated by this methodology for the whole Skagit Basin, including production from the Baker River a~d its tributaries that were appended in an errata sheet to Zillges (1977). The lower fry rearing value of the lower Skagit, due to turbidity and siltation, and of the Skagit near Gorge Dam, which is more exposed to dam-related flow fluctuations, is not considered in this simplistic analysis, but the two biases may tend to cancel. However, the 4.0 percent figure may be conside.red a minimum figure because of the large extent of areas of lower fry rearing value in the lower Skagit. From standardized electrofishing effort in 1978, coho fry densities at the County Line Station on the mainstem Skagit River reached 1.80 fry/yd of one•river bank in June, but were usually much lower. Although standardized electrofishing was discontinued in June 1978, catches of age~O coho fry remained high in 1976 and 1977 in the mainstem Skagit sites into August, suggesting peak densities may occur later than June. Most coho spawning occurs in the tributaries and coho fry densities may be higher there than in the mainstem Skagit. However, because of considerable mortality of the young salmon from many sources, eventual smolt production should be considerably lower than fry densities. It appears that the smolt production of at least some areas fell short of the maximum production potential estimated by Zillges' (1977) method. Coho adult escapements in recent years may have been too low to saturate the fry rearing environment. Zillges (1977) calculated the number of females necessary to produce the potential smolts by dividing the number of smolts by 100, found from the average fry rearing potential and optimum escapement at tlinter Creek (Salo and Bayliff 1978). Total desired escapement was then roughly calculated as 2 to 2.5 times the number of females. By these calculations, the estimated smolt production potential of the Skagit drainage, 1,455,191, would require the parentage of 14,552 female spawners, or at the least, 29,104 total spawners. Estimated coho escapements other than hatchery returns from 1965 to 1977 averaged only 15,385 and never reached 29,104 (Table 5.3). Lister and Walker (1966) found that chinook srnolt production in the Big Qualicum River tended to be 0.31 smolts/yd2 or 4.67 smolts/accessible yd, despite more variable adult escapements. These figures were applied in analysis similar to the one above used for estimating coho smolt potential from Zillges (1977) to streams in the Skagit Basin known to be used by chinook for rearing, spawning, or migration (Williams et al., 1975). The results (Tables 11.5 and 11.6) indicated that - ··~ - - ~' ~' -· ..... - - - - - 587 Table 11.4 Estimated coho smelt production potential above the proposed Copper Creek Dam site at RM 84.0. Adapted from Zillges (1977), Table 4 and Errata sheet. Location Computation Smelt potential Newhalem Creek 1, 760 2 .42 739 yds X Goodell Creek 3,168 yds accessible X 2.5 7,920 Martin Creek 1,056 yds 2 X .42 443 Newhalem Ponds, two 2,300 yds perimeter X 1.25 2,875 Thornton Creek 704 2 .42 296 yds X County Line Ponds, three 1,033 yds perimeter X 1.25 1,291 Damnation Creek 1,056 2 .42 443 yds X 10.2 miles of Skagit R. 17,952 yds accessible X 2.5 44;880 58,887 Estimated smelt production potential above RM 84.0 Estimated smelt production potential for Skagit Basin = = 58,887 = 4.0% 1,455,191 smelt prod. pot. lost 588 TabJe 11.5 Estimated chinook smolt ~roduction potential below the proposed Copper Creek Dam site at RM 84.0. Adapted from Zillges (1977) ~ and Williams et al. (1975). Stream no. 176 177 178 213 215 275 278 298 299 359 377 392 667 673 677 710 723 761 797 8l3 897 919 973 1022 1078 1079 1092 1174 1176 1204 1346 1411 1412 1750 1774 1774 1780 Name Skagit, below Copper Cr. Tom Moore Slough Unnamed Freshwater Slough N .. Fork Skagit Unnamed Shiyou Slough Day Creek Slough Day Alder Grandy. Finney McCleod Slough Sauk Unnamed Suiattle Big Tenas Straight Buck Lime Downey Sulpher Milk Unnamed Dan Unnamed Unnamed Unname.d · S. Fork Sauk Illabot Cascade Jordan Diobsud Bacon Upper Bacon Falls Acceuible length (mi) 84.0 2.8 1.0 3.0 7.3 .9 2.2 1.5 5.0 4.4 4.0 11.7 2.4 35.0 0.9 45.0 0.6 1.6 1.9 1.5 1.0 L2 1.2 5.8 2.2 3.4 1.0 .2 .7 12.0 2.5 18.5 .5 1.7 6.0 2.3 0.3 Averaa;e width (yds) ·- 1.0 2.5 LO 4.0 2.0 4.0 4.0 1.0 1.0 3.0 4.0 3.0 3.0 Total Chinook smolt potential x 1000 690.4 23.0 8.2 24.7 60.0 .5 18.1 12.3 4Li 6.0 32.9 96.2 19.7 287.7 .5 36.9. 9 4.9 3.5 2 .l 12.3 2.2 9 •. 9' 9.9 47.7 18.1 7.4 .6 1.6 .4 98.6 20.6 152.1 .8 3.7 49.3 3.8 .5 2141.2 - ~I - -t - - Table 11.6 Stream 589 Estimated chinook smelt production potential above the proposed Copper Creek Dam site at RM 84.0 and its comparison with the estimated production potential of the total accessible Skagit drainage. Adapted from Zillges (1977), and Williams et al. (1975). Name Accessible Average width Chinook smelt no. length (mi) (yds) potential X 1000 176 Skagit, above Copper Cr. 10.2 83.8 1827 Alma 0.3 2 .3 1867 Goodell 1.8 14.8 Tc,tal 98.9 Estimated chinook smelt production potential above RM 84.0 = 98.9 X 10 3 4.4% Estimated chinook smelt production potential for Skagit Basin = 2240 x 10 3 590 4.4 percent of the potential chinook smolt production would be lost after construction of Copper Creek Dam at RM 84.0. The upstream areas of the Skagit River are probably more important for fry rearing than this analysis indicated and, as with coho, this estimate of lost smolt production may be a minimum figure. Washington Department of Fisheries (WDF) data for 1973 to 1976 indicated that 66.4 percent of the mainstem Skagit adult chinook escapement was attributed to the river section upstream of the Sauk River (Sec. 6.4.3.1). In 1978, WDF had difficulty capturing chinook fry for wire tagging at stations on the Skagit River below the mouth of the Sauk until May and fry captured at the downstream stations were larger than those captured above the mouth of the Sauk River (Don Hendricks, WDF, personal communication). These findings suggest that the lower reaches are more important for fry migration than for fry rearing. Chinook returns in some years were probably large enough ~o produce fry densities near the carrying capacity. For example, using an egg to smolt survival for chinook salmon of 5 percent from findings of Lister and Walker (1966), a fecundity of 6,400 eggs/fe~ale found from spawners captured near Marblemount in 1973, and a sex ratio of 1.5:1 males to females (Russ Orrell, WDF, personal communication), we calculate that an adult return of 17,391 could fill the estimated production potential for the Skagit Basin of 2,24 million chinook smelts. The average return to. natural spawning areas from 1965 to 1977 of summer-fall chinook spawners and spring chinook was 14,428 and 2,022, respectively. Slight improvements of the egg to smolt survival figure due to decreased density dependent mortality or environmental factors would allow even average adult returns to fill the fry rearing environment by this estimate. It appears that rearing area is more of a limiting factor than spawning area for chinook in the Skagit Basin, especially since a disproportionate amount of fry production appears to be packed into the mainstem Skagit above the Sauk. Redistribution of overcrowded fry downstream as observed in chinook fry by Lister and Walker (1966) and improved rearing environment below Copper Creek Dam due to reduced flow fluctuations could help mitigate the effects of the loss of rearing area. Because rainbow-steelhead fry rearing areas are similar to chinook and coho rearing areas, there would probably be about a 4 percent reduction in rainbow-steelhead rearing potential also. It is ~ore difficult to esti~ate the extent of fry crowding based on adult returns for rainbow-steelhead fry than for chinook or coho fry because the escapement sizes are not known for rainbow-steelhead adults. Sport catches of winter-run steelhead from the Skagit system averaged 12,378 from 1961-1962 to 1975-1976, but from 1973-1974 to 1975-1976 averaged 6,494. Lucas Slough releases contributed between 30 and 39 percent of the 1963-1964 and 1964-1965 catch (Gary Engman, Washington Department of Game (WDG), personal communication). Total rainbow-steelhead redd counts from WDG aerial surveys of the Skagit and Sauk rivers averaged 705 from 1975 to 1978. These redd counts are considerably lower than one would expect if rainbow-steelhead - :~. ·:f. - 591 escapements were of the size of the' coho and chinook returns to the Skagit system in recent years. Bjornn (1978) found that migrant rainbow-steelhead production from Big Springs Creek in Idaho was limited to 0.56 subyearlings and 0.52 yearling per yd2 and that the number of migrants were reduced when chinook salmon were added to the stream. This is comparable to the production figures used for coho and chinook smolts. It appears that with recent escapement sizes the steehead fry may be less limited by rearing area than chinook and coho fry. 11.1.6 Creeks in Project Area The major impact of the Copper Creek Dam on the resident game fish populations in the tributaries would be the loss of lower portions of the accessible flowing stream habitats. These losses would range from 300 ft in Sky Creek to 2,000 ft in Goodell Creek. There will be no changes in the accessibility within the streams; that is, resident populations presently isolated from fish in the river will continue to be isolated from fish in the proposed reservoir. The slopes of these streams are steeper above the inundation level than below except for Goodell Creek where the slope remains relatively low for some distance upstream. The precipitous nature of the creeks, the presence of probable migration blocks near the mouths, and the very limited amount of suitable substrate will eliminate all of the creeks but Goodell Creek as potentially impor- tant spawning and rearing areas for fish from the reservoir. Goodell Creek is presently utilized by salmon and steelhead for spawning and rearing and it could be expected that it would be suitable for trout living in a reservoir. 11.1.7 Other Fishes Skagit River fishes other than salmon and adult steelhead trout will be affected by the alteration of 10 mi of upriver habitat if Copper Creek Dam is installed. Hountain whitefish are known to reside in lakes and reservoirs and probably could survive in the proposed Copper Creek Reservoir. However, if the Skagit whitefish population exhibits a migration pattern similar to that discussed by Pettit and Wallace (1975) then Copper Creek Dam would block access to upstream spawning grounds. However, no data are available for migration behavior of the Skagit whitefish. Largescale suckers were not observed upstream of the proposed dam site. The species composition of the new reservoir can reasonably be expected to match that of the upstream reservoirs. These reservoirs have fish populations composed predominantly of rainbow trout, but also in- cludes: cutthroat trout, Dolly Varden char, and brook trout. Downstream of the dam site these fishes will probably not be greatly affected by modified flow fluctuation except as it might affect benthic insect production. Whitefish and Dolly Varden rely heavily on aquatic insects. We have not observed these species stranded from flow fluctuation. 592 12.0 REFERENCES 12.1 Physical Environment Burt, W. V. River. 1973. Natural flow water temperatures in the upper Skagit Water Res. Assoc., Corvallis, Oregon. 4 pp. United States Geological Survey. 1955. Compilation of records of surface waters of the United States through September 1950. Water-supply paper 1316. United States Geological Survey. 1964. Compilation of records of surface waters of the United States, October 1950 to September 1960. Water-supply paper 1736. United States Geological Survey. 1971. 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The effects of river fluctuations hydroelectric peaking on selected aquatic Idaho Water Resour. Res. Inst., Moscow, Idaho. Malick, J. G. 1977. Ecology of benthic insects of the Cedar River, Washington. Ph.D. Thesis, Univ. Washington. 188 pp. Mason, W. T., J. B. Anderson, and G. E. Morrison. 1967. A limestone- filled artificial substrate sampler-float unit for collecting macroinvertebrates in large streams. Prog. Fish-Cult. 29:74. McConnell, W. J., and W. F. Sigler. 1959. Chlorophyll and productivity in a mountain river. Limnol. Oceanogr. 4:335-351. Mcintire, C. D., and H. K. Phinney. 1965. Laboratory studies of periphy- ton production and community metabolism in lotic environments. Ecol. Monogr. 5:237-258. Mcintire, C. D. 1966. Some effects of current velocity on periphyton• communities in laboratory streams. Hydrobiologia 27:559-570. Needham, P.R., ~nd R. L. Usiuger. 1956. 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Pupl., Oxford and Edinburgh. 358 pp. Gibson, R. J., and D. Galbraith. 1975. The relationships between invertebrate drift and salrnonid populations in the Matarnek River, Quebec, below a lake. Trans. Amer. Fish. Soc. 104:529-535. Johnson, W. E. 1964. Quantitative aspects of the pelagic, entromostracon zooplankton of a multibasis lake system over a 6-year period. Verh. Intern. Verein. Lirnnol. 15:727-734. King, I. P., and G. T. Orlob. 1973. Final report on the temperature effects of Ross Dam, Skagit River, Washington. Prepared for the Dept. Lighting, City of Seattle, by Water Resources Engineers, Walnut Creek, CA. Halick, J. G. 1977. Ecology of benthic insects of the Cedar River, Washington. Ph.D. Dissertation, Univ. Washington, Seattle. 188 pp. Rodhe, W. 1964. Effects of impoundment on water chemistry and plankton in Lake Ransaren (Swedish Lappland). Verb. Intern. Verein. Limnol. 15:437-443. Seattle City Light. 1973. 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Foster, R., v. Fletcher, and B. Kiser. 1977. 1976 hatcheries statistical report of production and plantings. Wash. Dept. Fish., Prog. Rep. 30. Foster, R., R. Kolb, and v. Fletcher. 1975. 1974 hatcheries statistical report of production and plantings. Wash. Dept. Fish. Foster, R., R. Rogers, B. Kiser, and V. Fletcher. 1976. 1975 hatcheries statistical re?ort of production and plantings. Wash. Dept. Fish. Gibbons, R. G., Biologist, Wash. Dept. Game, personal communication. ~amilton, R.,.Biologist, Pacific Power and Light, personal communication. 1 Kolb, R., R. Hager, and V. Fletcher. 1976. Hatchery stream plantings, 1952-1974. 2nd ed. Hatchery Statistical Records Rep. 1, Wash. Dept. Fish. Kolb, R., R. Hager, B. HcMillan, and V. Fletcher. plantings, production by hatchery, 1952-1974. Records Rep. 2, Wash. Dept. Fish. 1975. Hatchery Hatchery Statistical Miller, J. W. 1976. An analysis of the relationship between sockeye fish production and streamflow levels on the Cedar River. M.S. Thesis, Univ. Washington, Seattle, WA. Oppermann, A., Biologist, Wash. Dept. Game, personal commun.fcation. Orrell, R. F. 1976. Skagit chinook race differentiation study. Wash. Dept. Fish., Proj. Gompl. Rep. 53 pp. -. .·~ - - - 597 Orrell, R. F., Biologist. Personal communication, Wash. Dept. Fish. Reed, D., ed. 1971. 1970 Annual report. Wash. Dept. Fish. Washington Department of Game. Hatcheries fish planting records. Seattle Reg. Off. [Unpublished] Young, B. 1976. Steelhead sport catch estimates for Washington rivers during 1975-76 winter season. Treaty Indian Program, August 10, 1976. several western Wash. Dept. Game, Zillges, G. 1977. Methodology for determining Puget Sound coho escape- ment goals, escapement estimates, pre-season run size prediction, and in-season run assessment. Wash. Dept. Fish., Tech. Rep. 28. 60 PP• 12.5 Spawning Ames, J., and D. E. Phinney. 1977. 1977 Puget Sound summer-fall chinook methodology: Escapement estimates and goals, run size forecasts, and in-season run size updates. Wash. Dept. Fish., Tech. Rep. 29. 70 pp 0 Bell, M. C. 1973. Fisheries handbook of engineering requirements and biological criteria. Fish. Eng. Res. Prog. U.S. Army Corps Eng., N. Pac. Div., Portland, Oregon. Chambers, J. S., G. H. Allen, and R. T. Pressey. 1955. Research relating to study of spawning grounds in natural areas. Annu. Rep. 1955. Rep. to U.S. Army Corps Eng. by Wash. Dept. Fish. 175 pp. Collings, ~1. R. 1974. Generalization of spawning and rearing for several Pacific salmon species in western Washington. Surv. Open-File Rep. 39 PP• discharges u.s. Geol. Corbett, D. H. 1962. Stream-gaging procedure. p. 245. U.S. Geol. Surv. Water- Suppl. Paper 888. Curtis, B. 1959. Changes in a river's physical character~~tics under substantial reductions in flow due to hydroelectric diversion. California Fish Game 45:181-188. Dougenik, J. A. , and D. E. Sheehan. 1977. 5th ed. Lab. Computer Graphics Spatial September 1975, revised February 1977. SYMAP user's reference Anal., Harvard Univ. 187 PP• manual. Engman, R. G., personal communication. Fish. Biol., Wash. Dept. Game. Graybill, J. P. 1974. Effects of discharge in the Cedar River on sockeye salmon spawning area. M.S. Thesis, Univ. Washington, Seattle, Washington. 60 PP• 598 Heiser, D. W. 1971. Spawning depths and velocities of chu~ and pink salmon in western Washington. Pages 42-50 in Pink and chum salmon investigations, 1969. Puget Sound Stream Studies, Suppl. Prog. Rep., Wash. Dept. Fish. Hooper, D. R. ecology. 1973. Evaluation of the effects of flows on trout stream Pacific Gas Elec. Co., Emeryville, California. 97 pp. Hunter, J. W. 1973. A discussion of game fish in the State of Washington as related to water requirements. Wash. Dept. Game, Olympia, Washington. [Unpublished Manuscript.] 66 pp. Meekin, T. K. 1967. Observations of exposed fall chinook redds below Chief Joseph Dam during periods of low flow, October 1966 through January 1967. Wash. Dept. Fish., Res. Div. 23 pp. Miller, J. W. 1976. An analysis of the relationship between sockeye fish production and streamflow levels on the Cedar River. H.S. Thesis, Univ. Washington, Seattle, Washington. 45 pp. Oppermann, A. Fish. Bioi., Wash. Dept. Game. Personal communication. Orrell, R. F. Fish. Biol., Wash. Dept. Fish. Personal 'communication. .Sams, R, E., and L. S. Pearson. 1963. A study to develop methods for determining spawning flows for anadromous salmonids. Oregon Fish Comm. [Unpublished manuscript.] 56 pp. Smith, A. K. 1973. Development and application of spawnin? velocity and depth criteria for Oregon salmonids. Trans. Amer. Fish. Soc. 102(2): 312-316. Stalnaker, C. B., and J. L. Arnette. 1976. Methodologies for the determination of stream resource flow requirements: An assessment. Prepared for U.S. Fish Wild!. Serv., Off. Biol. Serv., Western Water Allocation by Utah State Univ., Logan, Utah. 199 p. Stober, Q. J., and J. P. Graybill. 1974. Effects of discharge in the Cedar River on sockeye salmon spawning area. Univ. Washington, Fish. Res. Inst., Final Rep. FRI-UW-7407. 39 pp. Thompson, K. E. 19z~· Determining stream flows for fish life. Pages 31- 46 and 85-103 in lnstrearn flow requirement workshop. Pac. N.W. River Basins Comm. United· States Geological Survey. 1943-1960. Water supply papers. Yearly volumes. United States.Geological Survey. 1961-1977. Water resources data for Washington. Yearly volumes. Williams, R. v!., F .• }1. Laramie, and J. J. Ames. 1975. A catalog of Washington streams and salmon utilization, Vol. 1, Puget Sound - - - - - - - - 599 region. Wash. Dept. Fish. Zillges, G. 1977. Methodology for determining Puget Sound coho escape- ment goals, escapement estimates, 1977 pre-season run size prediction and in-season run assessment. Wash. Dept. Fish., Tech. Rep. 28. 65 PP• 12.6 Incubation and Emergence Allen, R. L., and A. C. Moser. 1963-1965, 1967-1969. Rocky Reach chinook salmon spawning channel. Wash. Dept. Fish., Res. Div. Annu. Reps. 61-62, 62-63, 63-64, 65-66, 66-67, 67-68. Allen, R. L., B. D. Turner, and J. E. Moore. 1969-1972. Wells summer chinook salmon spawning channel. Wash. Dept. Fish., Res. Div. Douglas County Pub!. Uti!. Dist. Contract 022-4204, Annu. Reps. 68-69. Baldwin, N. S. 1956. Food consumption and growth of brook trout at different temperatures. Trans. Amer. Fish. Soc. 86:323-328. Brannon, E. 1974. General husbandry and growth. College of Fisheries, Univ. Washington. [Unpublished manuscript.] Brett, J. R., J. E. Shelbourn, and C. T. Shoop. 1969. Growth rate and body composition of fingerling sockeye salmon, Oncorhynchus nerka, in .relation to temperature and ration size. J. Fish. Res. Board Can. 26(9) :2363-2393 •. Brocksen, R. W., and J.P. Bugge. 1974. Preliminary investigations on the influence of temperature on food assimilation by rainbow trout, Salmo gairdneri Richardson. J. Fish. Biol. 6:93-97. Burgner, R. L. 1974. Testimony before the Federal Power Commission. pubject: In the Matter of City of Seattle Project No. 553. Held in Washington, D. C. Official Stenographer's Report 28:4403. Burt, W. V. 1971. Water temperature forecasts for the Skagit River below proposed High Ross Dam with maximum surface elevation of 1,725 feet above sea level. Water Res. Assoc., Corvallis, Oregon. 30 pp. Burt, W. V. River. 1973. Natural flow water temperatures in the upper Skagit Water Res. Assoc., Corvallis, Oregon. 30 pp. Chambers, J. S. 1963. Propagation of fall chinook salmon in McNary Dam experimental spawning channel. Summary Rep. 1957-1963, Wash. Dept. Fish., Res. Div. 38 PP• Gebhards, S. V. 1961. Emergence and mortality of chinook salmon fry in a natural redd. The Progr. Fish-Cult. 23:91. Johnson, R. C. 1974. Testimony before the Federal Power Commisssion. Subject: In the Matter of City of Seattle Project No. 553. Held at 600 Washington, D.C. Official Stenographer's Report 28:5067, 5080. Orrell, R. F. 1976. Skagit chinook race differentiation study. Wash. Dept. Fish., Proj. Compl. Rep. 53 pp. Phillips, R. w., and K V. Koski. 1969. A fry trap method for estimating salmonid survival from egg deposition to fry emergence. J. Fish. Res. Board Can. 26(1):133-141. Reimers, P. E., and R. E. Loeffel. 1967. The length of residence of juvenile fall chinook salmon in selected Columbia River tributaries. Oregon Fish. Comm. Res. Briefs 13(1):5-19. Seymour, A. H. 1956. Effects of temperature upon young chinook salmon. Ph.D. Thesis, Univ. Washington, Seattle. 127 pp. Sheridan, W. L. 1962. Relation of stream temperatures to timing of pink salmon escapements in.southeast Alaska. Pages 87-102 in Symposium on pink saln,10n. H. R. MacMillan Lectures in Fish., Univ.British Columbia, Vancouver, Canada. Wales, J. H., and M. Coots. 1954. Efficiency of chinook salmon spawning in Fall Creek, California. Trans. Amer. Fish. Soc. 84:137-149. 12.7 Fry Rearing Bauersfeld, K. 1978. Stranding of juvenile salmon by flow reductions at t1ayfield Dam on tl:te Cowlitz River, 1976. Wash. Dept. Fish., Tech. Rep. No. 36. 36 PP• Bjornn, T. C. 1978. Survival, production, and yield of trout and chinook salmon in the Lemhi River, Idaho. Final Report, Federal Aid to Fish Restoration, Project F-49-R, Salmon and Steelhead Invest. Bull. No. 27, Univ. Idaho. Idaho Dept. of Fish and Game, 57 pp. Burt, W. V. 1973. Natural flow water temperatures in the upper Skagit River. Water Res. Assoc., Corvallis, Oregon. 4 pp. Chapman, D. W. 1965. Oregon streams. Net production of juvenile coho salmon in three Trans. Amer. Fish. Soc. 94(1):40-52. Congleton, J. L., Assist. Professor, U. W., Cooperative Fisheries Research Unit, personal communication. Engman, G., Fish. Biol., Wash. Dept. Game, personal communication. Fiscus, H., Fish. Biol., Wash. Dept. Fish., personal communication. Hendricks, D., Fish. Biol., Wash. Dept. Fish, personal communication. Lister, D. B., and C. E. Walker. 1966. The effect of flow control on freshwater survival of chum, coho, and chinook salmon in the Big Qualicum River. Canad. Fish. Cult. 37:3-25. - - - - - - 601 McPhail, J. D., and c. C. Lindsey. 1970. Freshwater fishes of North- western Canada and Alaska. Fish. Res. Board Can. Bull. 173. 381 pp. Noggle, c. C. 1978. Behavioral, physiological and lethal effects of suspended sediment on juvenile salmonids. M.S. thesis, Univ. Washington, Seattle. 87 PP• Orrell, R. F. 1976. Skagit chinook race differentiation study. Wash. Dept~ Fish., Proj. Compl. Rep. 53 pp. Orrell, R. F., Fish. Bioi., Wash. Dept. Fish., personal communication. Phinney, L. A. 1974a. Further observations of juvenile salmon strandings in the Skagit River, March 1973. Wash. Dept. Fish. 34 pp. Phinney, L. A. 1974b. Direct examination testimony, Official Stenographers Rep. FPC/City of Seattle, Project No. 553, at Washington, D.C., pp. 4892. Salo, E. and W. H. Bayliff. 1958. Artificial and natural production of silver salmon (Oncorhynchus kisutch), at Minter Creek, Washington. Wash. Dept. Fish., Res. Bull. No. 4, 76 pp. Seattle City Light. 1974. The aquatic environment, fishes and fishery, Ross Lake and the Canadian Skagit River. Int. Rep. No. 3. City of Seattle, Dept. of Lighting. Thompson J. S. 1970. The effect of water flow regulation at Gorge Dam on stranding of salmon fry in the Skagit River, 1969-1970. Wash. Dept. Fish., Suppl. Prog. Rep., Power Dam Studies, Management and Research Div. 46 PP• Williams, R. W., R. M. Laramie, and J. J. Ames. 1975. A catalog of Vol. 1. Puget Sound Washington streams and salmon utilization. region. Wash. Dept. Fish. Zillges, G. 1977. Hethodology escapement estimates, 1977 in-season run assessment. 65 PP• for determining Puget Sound coho preseason run size prediction and Wash. Dept. Fish., Tech. Rep. No. 28, Zippin, c. 1958. The removal method of population estimation. Journal of Wild!. Management 22(1):82-91. 12.8 Other Fishes Pettit, S. W. and R. L. Wallace. 1975. Age, growth, and movement of mountain whitefish, Prosopium williamson! (Girard), in the North Fork Clearwater River, Idaho. Trans. Amer. Fish. Soc. 104(1):68-76. 602 Hashington Department of Game. 1977. Skagit River studies. Progress Rep.-December 31, 1977, Cooperative aggreement 14-16-0001-5776 FS and 14-16-0001-6345 IFC. Pp. 48-84. Washington Department of Game. 1978. Skagit River studies. Progress Rep.-March 31, 1978, Cooperative agreement 14-16-0001-6345 IFC. Pp. 31-60. - -. T I I -r .. I I