Jolyonwalkley Thesis Final 12

SEASONAL ECOLOGY OF FISH AND MACROINVERTEBRATES INHABITING

FOURMILE CREEK, UPPER KLAMATH LAKE, OREGON

Jolyon E. Walkley

A Thesis

Presented to

The Faculty of Humboldt State University

In Partial Fulfillment

Of the Requirements for the Degree

Masters of Science

In Natural Resources: Fisheries

December, 2010

ABSTRACT

SEASONAL ECOLOGY OF FISH AND MACROINVERTEBRATES INHABITING FOURMILE CREEK, UPPER KLAMATH LAKE, OREGON

Jolyon E. Walkley

I investigated the species assemblage and abundances of fish and macroinvertebrates inhabiting the lower three km of Fourmile Creek, an altered and largely unstudied intermittent tributary to Upper Klamath Lake, Oregon. Seasonal reproductive state, body condition and diet of the four most abundant fish (speckled dace,

Rhinichthys osculus , fathead minnow, Pimephales promelas , slender sculpin, Cottus tenuis , and yellow perch, Perca flavescens ) were also examined. Nine native and seven non-native fish species from eight families were captured March – October, 2005 and

2006. Native species, including speckled dace and slender sculpin, tended to dominate the fish catch from March – August; non-native species, including fathead minnow and yellow perch, increased in abundance during fall. Both abundance and species richness were greatest at sites situated within the lower one km of Fourmile Creek where surface flow persisted longer and water quality (temperature, dissolved oxygen and pH) tended to be more stable than at more ephemeral upper creek sites. Gonadosomatic indices and the presence of larvae and juveniles show Fourmile Creek to be an important breeding habitat for speckled dace, slender sculpin and other native fish. Speckled dace and yellow perch spawn in spring, fathead minnow spawn in summer, and slender sculpin spawn during late summer/fall. Condition factors of sexually mature fish tended to decrease both during their reproductive season, and as surface waters disappeared.

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Especially poor body condition in slender sculpin likely resulted from the temporal overlap of reproduction with stream drying, followed by growth-limiting winter habitat conditions. Benthic insects and crustaceans were the most important foods for speckled dace and slender sculpin; detritus and crustaceans were the most important foods for fathead minnow; insects, crustaceans and fish were the most important foods for yellow perch. Dietary overlap between speckled dace and fathead minnow was not significant across seasons, even as the creek dried, suggesting minimal dietary competition between these two abundant cyprinid species. Crustaceans, insects and annelids were the dominant macroinvertebrates inhabiting Fourmile Creek. Cladocerans and copepods, the dominant crustacean taxa, peaked in abundance during spring/early summer and during the fall. Dipterans (principally chironimid larvae) dominated the insect community during most months, while hemipteran and coleopteran taxa increased in abundance as the creek dried. Other insects, including simuliid larvae, were only abundant until early summer, when water flow decreased.

ACKNOWLEDGEMENTS

This thesis is dedicated to my family, whose generosity and support made it possible. To my wife, Shannon and our two sons, Alden and Dylan, I thank you for your unwavering love, support and patience over the last six years. I also must thank my parents, Barrie and Annabelle, and my sister, Brett, for a lifetime of support and encouragement. Thanks for taking me fishing Dad!

Special thanks also go to my advisor, Tim Mulligan, and my committee members,

Helen Mulligan and Terry Roelofs. Both Tim and Helen provided valuable guidance and encouragement across all stages of this long, and at times daunting, project. Their assistance during field data collection (especially during Alden’s birth), in sorting through massive amounts of data and their feedback on my many drafts was invaluable.

Terry Roelofs also provided valuable guidance during the course of the study and feedback on this manuscript. I also want to thank Mark Lomeli for his assistance in the laboratory, and Rebecca Quinones and Susan Tharratt for their assistance in the field. A special thank you also goes to the staff at both the Humboldt State University Marine Lab and the HSU Children’s Center. This project was generously funded through a grant from the USFS Hatfield Restoration Program and the Marin Rod and Gun Club.

TABLE OF CONTENTS

Page

ABSTRACT ...... iii

ACKNOWLEDGEMENTS ...... v

TABLE OF CONTENTS ...... vi

LIST OF TABLES ...... vii

LIST OF FIGURES ...... xiv

LIST OF APPENDICIES ...... xxiv

INTRODUCTION ...... 1

STUDY SITE ...... 6

MATERIALS AND METHODS ...... 15

Field Collection ...... 15

Sample Processing and Analysis ...... 18

RESULTS ...... 26

Water Quality ...... 26

Potential Macroinvertebrate Prey ...... 39

Fish Abundance, Condition, Reproduction and Diet ...... 80

DISCUSSION ...... 161

LITERATURE CITED ...... 189

PERSONAL COMMUNICATIONS ...... 194

APPENDICIES ...... 195

LIST OF TABLES

Table Page

1. Coordinates for the Fourmile and Westside transect boundaries and sampling sites within the lower 2.4 kilometers of Fourmile Creek, Upper Klamath Lake, Oregon. Fish and invertebrates were collected March – October 2005 and March – October 2006. Coordinates are projected in World Geodetic System (WGS 84)...... 8

2. Mean morning, afternoon and overall mean water temperature, dissolved oxygen, pH and specific conductivity values recorded at the lower and upper sites of the Fourmile transect, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – October 2006. Channel values represent readings taken 0.3m above the bottom in the middle of the channel. Margin values represent readings taken 0.3m below the water surface, immediately adjacent to the trap net mouth...... 27

3. Mean morning, afternoon and overall mean water temperature, dissolved oxygen, pH and specific conductivity values recorded at the lower, upper, and pasture sites of the Westside transect, Fourmile Creek, Upper Klamath Lake, Oregon, April – August 2005 and March – July 2006. Channel values represent readings taken 0.3m above the bottom in the middle of the channel. Margin values represent readings taken 0.3m below the water surface, immediately adjacent to the trap net mouth. The pasture site was only sampled in May 2006...... 28

4. Invertebrate taxa collected in light traps, plankton tows and benthic cores at the Fourmile and Westside transects in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – October 2006...... 40

5. Number of organisms and frequency of occurrence (number of samples) of major invertebrate taxa caught in light traps at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. The % of total = % of total number of invertebrates collected in light traps. The % of samples = % of total number of light trap samples in which the taxon was collected...... 44

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Table Page

6. Number of organisms and frequency of occurrence (number of samples) of major invertebrate taxa caught in plankton tows at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. The % of total = % of total number of invertebrates collected in plankton tows. The % of samples = % of total number of plankton tows in which the taxon was collected...... 45

7. Number of organisms and frequency of occurrence (number of samples) of major Crustacean and Arachnid taxa caught in light traps at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. The % of total = % of total number of Arachnida and % of total number of Crustacea collected in light traps. The % of samples = % of total number of light trap samples in which the taxon was collected...... 48

8. Number of organisms and frequency of occurrence (number of samples) of major Crustacean and Arachnid taxa caught in plankton tows at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. The % of total = % of total number of Arachnida and % of total number of Crustacea collected in plankton tows. The % samples = % of total number of plankton tows in which the taxon was collected...... 49

9. Number of organisms and frequency of occurrence (number of samples) of major Insecta taxa caught in light traps at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. The % of total = % of total number of Insecta collected in light traps. The % of samples = % of total number of light traps in which the taxon was collected...... 50

10. Number of organisms and frequency of occurrence (number of samples) of major Insecta taxa caught in plankton tows at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. The % of total = % of total number of Insecta collected in plankton tows. The % of samples = % of total number of plankton tows in which the taxon was collected...... 51

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Table Page

11. Number of organisms and frequency of occurrence (number of samples) of selected Insecta life history stages caught in light traps at two sampling transects Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. The % of total = % of total number of Insecta collected in light traps. The % of samples = % of total number of light traps in which the taxon was collected...... 52

12. Number of organisms and frequency of occurrence (number of samples) of selected Insecta life history stages caught in plankton tows at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. The % of total = % of total number of Insecta collected in plankton tows. The % of samples = % of total number of plankton tows in which the taxon was collected...... 53

13. Number of organisms and frequency of occurrence (number of samples) of selected Diptera life history stages caught in light traps at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. The % of total = % of total number of Insecta collected in light traps. The % of samples = % of total number of light traps in which the taxon was collected...... 54

14. Number of organisms and frequency of occurrence (number of samples) of selected Diptera life history stages caught in plankton tows at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. The % of total = % of total number of Insecta collected in plankton tows. The % of samples = % of total number of plankton tows in which the taxon was collected...... 55

15. Number of organisms and frequency of occurrence (number of samples) of Hemiptera caught in light traps at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. The % of total = % of total number of Insecta collected in light traps. The % of samples = % of total number of light traps in which the taxon was collected...... 56

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16. Number of organisms and frequency of occurrence (number of samples) of Hemiptera caught in plankton tows at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. The % of total = % of total number of Insecta collected in plankton tows. The % of samples = % of total number of plankton tows in which the taxon was collected...... 57

17. Mean CPUE for major invertebrate taxa caught in light traps at two sampling transects, Fourmile (FM) and Westside (WS), in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each location, mean CPUE (number of organisms sampled per 12 hours) = [(total number of organisms sampled / total (hours darkness + 2)) x 12]...... 60

18. Mean CPUE for major invertebrate taxa caught in plankton tows at two sampling transects, Fourmile (FM) and Westside (WS) in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each location, mean CPUE (number of organisms sampled per m3) = (total number of organisms sampled / total volume sampled)]...... 61

19. Mean CPUE for major Crustacean and Arachnid taxa caught in light traps at two sampling transects, Fourmile (FM) and Westside (WS), in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each location, mean CPUE (number of organisms sampled per 12 hours) = [(total number of organisms sampled / total (hours darkness + 2)) x 12]...... 62

20. Mean CPUE for major Crustacean and Arachnid taxa caught in plankton tows at two sampling transects, Fourmile (FM) and Westside (WS) in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each location, mean CPUE (number of organisms sampled per m3) = (total number of organisms sampled / total volume sampled)]...... 63

21. Mean CPUE for orders of Insecta caught in light traps at two sampling transects, Fourmile (FM) and Westside (WS), in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each location, mean CPUE (number of organisms sampled per 12 hours) = [(total number of organisms sampled / total (hours darkness + 2)) x 12]...... 65

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22. Mean CPUE for orders of Insecta caught in plankton tows at two sampling transects, Fourmile (FM) and Westside (WS) in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each location, mean CPUE (number of organisms sampled per m3) = (total number of organisms sampled / total volume sampled)]...... 66

23. Mean CPUE for Hemiptera caught in light traps at two sampling transects, Fourmile (FM) and Westside (WS), in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each location, mean CPUE (number of organisms sampled per 12 hours) = [(total number of organisms sampled / total (hours darkness + 2)) x 12]...... 67

24. Mean CPUE for major Hemiptera caught in plankton tows at two sampling transects, Fourmile (FM) and Westside (WS), in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each location, mean CPUE (number of organisms sampled per m3) = (total number of organisms sampled / total volume sampled)]...... 68

25. Mean CPUE for Diptera caught in light traps at two sampling transects, Fourmile (FM) and Westside (WS), in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each location, mean CPUE (number of organisms sampled per 12 hours) = [(total number of organisms sampled / total (hours darkness + 2)) x 12]...... 69

26. Mean CPUE for Diptera caught in plankton tows at two sampling transects, Fourmile (FM) and Westside (WS) in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each location, mean CPUE (number of organisms sampled per m3) = (total number of organisms sampled / total volume sampled)]...... 70

27. Number of organisms and frequency of occurrence (number of samples) of major invertebrate taxa collected in benthic samples at two sampling transects, Fourmile (FM) and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – October 2006. The % of total = % of total number of invertebrates collected in benthic samples. The % of samples = % of total number of benthic samples in which the taxon was collected...... 79

28. Total numbers of fish taken in trap nets at two transects, Fourmile (FM) and Westside (WS), in Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 81

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29. Total numbers of native and non-native fish taken in trap nets at two transects, Fourmile (FM) and Westside (WS), in Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 82

30. Total numbers of native and non-native fish taken in trap nets at the Fourmile (FM) sampling transect of Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 83

31. Total numbers of native and non-native fish taken in trap nets at the Westside (WS) sampling transect of Fourmile Creek, Upper Klamath Lake, Oregon, April – July 2005 and March – July 2006...... 85

32. Overall Mean CPUE values for each fish species collected at two transects, Fourmile (FM) and Westside (WS), in Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 86

33. Overall Mean CPUE values for each fish species collected in trap nets at the Fourmile transect (FM) in Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 89

34. Overall Mean CPUE values for each fish species collected in trap nets at the Westside transect (WS) in Fourmile Creek, Upper Klamath Lake, Oregon, April – July 2005 and March – July 2006...... 90

35. Overall mean CPUE values of all fish species taken in trap nets at the Fourmile (FM) and Westside (WS) transects in Fourmile Creek, Upper Klamath Lake, Oregon, during April – July 2005 and April – July 2006. These are the months during which both transects were sampled in both the 2005 and 2006 sampling seasons...... 94

36. Transect specific overall and annual mean CPUE values of selected fish at the Fourmile (FM) and Westside (WS) transects, in Fourmile Creek, Upper Klamath Lake, Oregon, April – July 2005 and April – July 2006. These are the months during which both transects were sampled in both the 2005 and 2006 sampling seasons...... 95

37. Percent number, percent weight and percent frequency of occurrence of major dietary groups consumed by speckled dace, Rhinichthys osculus , collected at two sampling transects, Fourmile (FM) and Westside (WS) in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Size class values are midpoints of 10mm standard length size classes. *indicates minor taxa and/or unidentifiable parts...... 129

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38. Percent number, percent weight and percent frequency of occurrence of major dietary groups consumed by fathead minnow, Pimephales promelas , collected at two sampling transects, Fourmile (FM) and Westside (WS) in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Size class values are midpoints of 3mm standard length size classes. * indicates minor taxa and/or unidentifiable parts...... 130

39. Percent number, percent weight and percent frequency of occurrence of major dietary groups consumed by slender sculpin, Cottus tenuis , collected at two sampling transects, Fourmile (FM) and Westside (WS) in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Size class values are midpoints of 10mm standard length size classes. * indicates minor taxa and/or unidentifiable parts...... 131

40. Percent number, percent weight and percent frequency of occurrence of major dietary groups consumed by yellow perch, Perca flavescens , collected at two sampling transects, Fourmile (FM) and Westside (WS) in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Size class values are midpoints of 20mm standard length size classes. *indicates minor taxa and/or unidentifiable parts...... 132

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LIST OF FIGURES

Figure Page

1. Aerial photograph depicting the lower four kilometers of Fourmile Creek and the Fourmile and Westside transects, Upper Klamath Lake, Oregon. Fish and invertebrates were sampled March – October 2005 and March – October 2006. Data available from the Oregon Imagery Explorer...... 7

2. Aerial photograph depicting the location of the Fourmile transect sites in Fourmile Creek, Upper Klamath Lake, Oregon. Sampling for fish and invertebrates at this transect occurred March – October 2005 and March – October 2006. Data available from the Oregon Imagery Explorer...... 10

3. Photographs showing seasonal water level changes in the Fourmile upper site, Fourmile Creek, Upper Klamath Lake, Oregon. Both photographs look upstream at the Fourmile upper trap net site. The one on the left was taken in May 2006, while the photograph on the right was taken in September 2006...... 11

4. Aerial photograph showing the location of the Westside transect sites, Fourmile Creek, Upper Klamath Lake, Oregon. Sampling for fish and invertebrates at this transect occurred April – August 2005 and March – July 2006. Data available from the Oregon Imagery Explorer...... 13

5. Photographs showing seasonal water level changes at the Westside lower site, Fourmile Creek, Upper Klamath Lake, Oregon. The upper photograph was taken at the commencement of sampling at the site in April 2005, the middle photograph was taken in June 2005, and the bottom photograph was taken in August 2005, when sampling at this site was suspended for the season...... 14

6. Mean monthly morning and afternoon temperature readings recorded at the lower and upper Fourmile transect sites in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – October 2006. Mid channel values represent readings taken 0.3m above the bottom. Channel margin values represent readings taken 0.3m below the water surface...... 30

7. Mean monthly morning and afternoon temperature readings recorded at the lower and upper Westside transect sites in lower Fourmile Creek, Upper Klamath Lake, Oregon, April – August 2005 and March – July 2006. Mid channel values represent readings taken 0.3m above the bottom. Channel margin values represent readings taken 0.3m below the water surface...... 31

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Figure Page

8. Mean monthly morning and afternoon dissolved oxygen readings at the lower and upper Fourmile transect sites in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – October 2006. Mid channel values represent readings taken 0.3m above the bottom. Channel margin values represent readings taken 0.3m below the water surface...... 32

9. Mean monthly morning and afternoon dissolved oxygen readings recorded at the lower and upper Westside transect sites in lower Fourmile Creek, Upper Klamath Lake, Oregon, April – August 2005 and March – July 2006. Mid channel values represent readings taken 0.3m above the bottom. Channel margin values represent readings taken 0.3m below the water surface...... 33

10. Mean monthly morning and afternoon pH readings at the lower and upper Fourmile transect sites in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – October 2006. Mid channel values represent readings taken 0.3m above the bottom. Channel margin values represent readings taken 0.3m below the water surface...... 34

11. Mean monthly morning and afternoon pH readings recorded at the lower and upper Westside transect sites in lower Fourmile Creek, Upper Klamath Lake, Oregon, April – August 2005 and March – July 2006. Mid channel values represent readings taken 0.3m above the bottom. Channel margin values represent readings taken 0.3m below the water surface...... 35

12. Mean monthly morning and afternoon specific conductivity readings recorded at the lower and upper Fourmile transect sites in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – October 2006. Mid channel values represent readings taken 0.3m above the bottom. Channel margin values represent readings taken 0.3m below the water surface...... 37

13. Mean monthly morning and afternoon specific conductivity readings recorded at the lower and upper Westside transect sites in lower Fourmile Creek, Upper Klamath Lake, Oregon, April – August 2005 and March – July 2006. Mid channel values represent readings taken 0.3m above the bottom. Channel margin values represent readings taken 0.3m below the water surface...... 38

14. Overall mean monthly CPUE for snails sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 72

Figure Page

15. Overall mean monthly CPUE for Oligochaeta sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 73

16. Overall mean monthly CPUE for Arachnida sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 74

17. Overall mean monthly CPUE for Crustacea sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 75

18. Overall mean monthly CPUE for Insecta sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 76

19. Mean monthly CPUE of introduced and native fish captured in trap nets at two transects in Fourmile (FM) and Westside (WS), in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 87

20. Mean site-specific CPUE for the five overall most abundant fish at the lower (LW) and upper (UP) sites of the Fourmile (FM) transect, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 91

21. Mean site-specific CPUE for the five overall most abundant fish at the lower (LW), upper (UP) and pasture (PS) sites at the Westside (WS) transect, Fourmile Creek, Upper Klamath Lake, Oregon, April – July 2005 and March – July 2006...... 92

22. Monthly species diversity (H), species evenness (J), and species richness (S) of fish captured in trap nets at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Monthly H values are represented by grey bars; J values by black squares (possible range from zero to one); and S by open circles. Note that during April 2005 and March 2006, only one species of fish (Rhinichthys osculus ) was captured at the Westside transect...... 96

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Figure Page

23. Gonadosomatic Index for female and male speckled dace, Rhinichthys osculus, collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005. Size class midpoints represent 10mm standard length size classes...... 100

24. Gonadosomatic Index for female and male speckled dace, Rhinichthys osculus, collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – September 2006. Size class midpoints represent 10mm standard length size classes...... 101

25. Gonadosomatic Index for female and male fathead minnow, Pimephales promelas , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005. Size class midpoints represent 3mm standard length size classes...... 103

26. Gonadosomatic Index for female and male fathead minnow, Pimephales promelas , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – September 2006. Size class midpoints represent 3mm standard length size classes...... 104

27. Gonadosomatic Index for female and male slender sculpin, Cottus tenuis, collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – September 2006. Size class midpoints represent 10mm standard length size classes...... 106

28. Gonadosomatic Index for female and male slender sculpin, Cottus tenuis , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – September 2006. Size class midpoints represent 10mm standard length size classes...... 107

29. Gonadosomatic Index for female and male yellow perch, Perca flavescens , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005. Size class midpoints represent 20mm standard length size classes...... 108

30. Gonadosomatic Index for female and male yellow perch, Perca flavescens , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – September 2006. Size class midpoints represent 20mm standard length size classes...... 109

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Figure Page

31. Fulton–type condition factors for speckled dace, Rhinichthys osculus , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Condition factor 1 is based on total body weight; Condition factor 3 is based on gonad-free, gut-free body weight. Horizontal line represents mean value for each condition factor. Size class midpoints represent 10mm standard length size classes...... 111

32. Fulton-type condition factors for fathead minnow, Pimephales promelas , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Condition factor 1 is based on total body weight; Condition factor 3 is based on gonad-free, gut-free body weight. Horizontal line represents mean value for each condition factor. Size class midpoints represent 3mm standard length size classes...... 112

33. Fulton-type condition factors for slender sculpin, Cottus tenuis , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Condition factor 1 is based on total body weight; Condition factor 3 is based on gonad-free, gut-free body weight. Horizontal line represents mean value for each condition factor. Size class midpoints represent 10mm standard length size classes...... 113

34. Fulton-type condition factors for yellow perch, Perca flavescens , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Condition factor 1 is based on total body weight; Condition factor 3 is based on gonad-free, gut-free body weight. Horizontal line represents mean value for each condition factor. Size class midpoints represent 20mm standard length size classes...... 114

35. Fulton-type condition factors for female and male speckled dace, Rhinichthys osculus , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Condition factor 1 is based on total body weight. Horizontal line represents mean value for each condition factor. Size class midpoints represent 10mm standard length size classes...... 116

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36. Fulton-type condition factors for female and male speckled dace, Rhinichthys osculus , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Condition factor 3 is based on gonad-free, gut-free body weight. Horizontal line represents mean value for each condition factor. Size class midpoints represent 10mm standard length size classes...... 117

37. Fulton-type condition factors for female and male fathead minnow, Pimephales promelas , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Condition factor 1 is based on total body weight. Horizontal line represents mean value for each condition factor. Size class midpoints represent 3mm standard length size classes...... 119

38. Fulton-type condition factors for female and male fathead minnow, Pimephales promelas , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Condition factor 3 is based on gonad-free, gut-free body weight. Horizontal line represents mean value for each condition factor. Size class midpoints represent 3mm standard length size classes...... 120

39. Fulton-type condition factors for female and male slender sculpin, Cottus tenuis , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Condition factor 1 is based on total body weight. Horizontal line represents mean value for each condition factor. Size class midpoints represent 10mm standard length size classes...... 121

40. Fulton-type condition factors for female and male slender sculpin, Cottus tenuis , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Condition factor 3 is based on gonad-free, gut-free body weight. Horizontal line represents mean value for each condition factor. Size class midpoints represent 10mm standard length size classes...... 122

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Figure Page

41. Fulton-type condition factors for female and male yellow perch, Perca flavescens , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Condition factor 1 is based on total body weight. Horizontal line represents mean value for each condition factor. Size class midpoints represent 20mm standard length size classes...... 123

42. Fulton-type condition factors for female and male yellow perch, Perca flavescens , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Condition factor 3 is based on gonad-free, gut-free body weight. Horizontal line represents mean value for each condition factor. Size class midpoints represent 20mm standard length size classes...... 124

43. Hepatosomatic index for female and male slender sculpin, Cottus tenuis , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Horizontal line represents mean value for both sexes. Size class midpoints represent 10mm standard length size classes...... 126

44. Hepatosomatic index for female and male yellow perch, Perca flavescens , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Horizontal line represents mean value for both sexes. Size class midpoints represent 20mm standard length size classes...... 127

45. Index of relative importance (IRI) values of major dietary groups consumed by speckled dace, Rhinichthys osculus , collected in trap nets at two sampling transects, Fourmile (FM) and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. IRI values normalized to 100% for each size class-season category. Size class values are midpoints of 10mm standard length classes. Numbers at tops of bars indicate total number of gastrointestinal tracts examined...... 134

46. Index of relative importance (IRI) values of insect orders consumed by speckled dace, Rhinichthys osculus , collected in trap nets at two sampling transects, Fourmile (FM) and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. IRI values normalized to 100% for each size class-season category. Size class values are midpoints of 10mm standard length classes. Numbers at tops of bars indicate total number of gastrointestinal tracts containing insects...... 135 xx

Figure Page

47. Index of relative importance (IRI) values of major dietary groups consumed by fathead minnow, Pimephales promelas , collected in trap nets at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. IRI values normalized to 100% for each size class-season category. Size class values are midpoints of 3mm standard length classes. Numbers at tops of bars indicate total number of gastrointestinal tracts examined...... 136

48. Index of relative importance (IRI) values of major dietary groups consumed by slender sculpin, Cottus tenuis , collected in trap nets at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. IRI values normalized to 100% for each size class-season category. Size class values are midpoints of 10mm standard length classes. Numbers at tops of bars indicate total number of gastrointestinal tracts examined...... 137

49. Index of relative importance (IRI) values of insect orders consumed by slender sculpin, Cottus tenuis , collected in trap nets at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. IRI values normalized to 100% for each size class-season category. Size class values are midpoints of 10mm standard length classes. Numbers at tops of bars indicate total number of gastrointestinal tracts containing insects...... 138

50. Index of relative importance (IRI) values of major dietary groups consumed by yellow perch, Perca flavescens , collected in trap nets at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. IRI values normalized to 100% for each size class-season category. Size class values are midpoints of 20mm standard length classes. Numbers at tops of bars indicate total number of gastrointestinal tracts examined...... 139

51. Index of relative importance (IRI) values of major dietary groups consumed by speckled dace, Rhinichthys osculus , collected in short duration/mixed gear samples at two sampling transects, Fourmile (FM) and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. IRI values normalized to 100% for each size class- season category. Size class values are midpoints of 10mm standard length classes. Numbers at tops of bars indicate total number of gastrointestinal tracts examined...... 144

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52. Index of relative importance (IRI) values of insect orders consumed by speckled dace, Rhinichthys osculus , collected in short duration/mixed gear samples at two sampling transects, Fourmile (FM) and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. IRI values normalized to 100% for each size class- season category. Size class values are midpoints of 10mm standard length classes. Numbers at tops of bars indicate total number of gastrointestinal tracts containing insects...... 145

53. Index of relative importance (IRI) values of major dietary groups consumed by fathead minnow, Pimephales promelas , collected in short duration/mixed gear samples at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. IRI values normalized to 100% for each size class- season category. Size class values are midpoints of 3mm standard length classes. Numbers at tops of bars indicate total number of gastrointestinal tracts examined...... 146

54. Index of relative importance (IRI) values of major dietary groups consumed by slender sculpin, Cottus tenuis , collected in short duration/mixed gear samples at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. IRI values normalized to 100% for each size class-season category. Size class values are midpoints of 10mm standard length classes. Numbers at tops of bars indicate total number of gastrointestinal tracts examined...... 147

55. Index of relative importance (IRI) values of insect orders consumed by slender sculpin, Cottus tenuis , collected in short duration/mixed gear samples at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. IRI values normalized to 100% for each size class-season category. Size class values are midpoints of 10mm standard length classes. Numbers at tops of bars indicate total number of gastrointestinal tracts containing insects...... 148

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Figure Page

56. Index of relative importance (IRI) values of major dietary groups consumed by yellow perch, Perca flavescens , collected in short duration/mixed gear samples at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. IRI values normalized to 100% for each size class-season category. Size class values are midpoints of 20mm standard length classes. Numbers at tops of bars indicate total number of gastrointestinal tracts examined...... 149

57. Seasonal size specific dietary overlap values (S 10 ) between speckled dace and fathead minnow captured in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. This analysis uses low taxonomic resolution (%IRI values of the five major dietary groups). S10 values ≥ 0.6 show significant dietary overlap between the two fish species...... 155

58. Seasonal size specific dietary overlap values (S 10 ) between speckled dace and fathead minnow captured in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. This analysis uses a high level of taxon resolution (%IRI values of 27 prey groups). S 10 values ≥ 0.6 show significant dietary overlap between the two fish species...... 156

59. Seasonal %IRI of major dietary groups consumed by small (< 50mm SL) and large ( ≥ 50mm SL) speckled dace and fathead minnow. Fish were captured in overnight trap nets set in lower Fourmile Creek, Upper Klamath Lake, Oregon, duringMarch – October 2005 and March – September 2006...... 158

60. Seasonal %IRI of 27 prey groups consumed by small (< 50mm SL) and large (≥ 50mm SL) speckled dace and fathead minnow. Fish were captured in overnight trap nets set in lower Fourmile Creek, Upper Klamath Lake, Oregon, during March – October 2005 and March – September 2006...... 159

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LIST OF APPENDICIES

Appendix Page

A. Light trap sampling effort (total (hours of darkness + 2) fished) and total number of samples taken at two sampling transects, Fourmile (FM) and Westside (WS), in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Sites are: lower (LW), upper (UP), pasture (PS). Hours fished for each sample = hours of darkness + two hours...... 196

B. Plankton tow sampling effort (m 3 water filtered ) and total number of samples collected at two sampling transects, Fourmile (FM) and Westside (WS), in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 197

C. Overall mean monthly CPUE for Hydrachnida sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 198

D. Overall mean monthly CPUE for Cladocera sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 199

E. Overall mean monthly CPUE for Copepoda sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 200

F. Overall mean monthly CPUE for Ostracoda sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 201

G. Overall mean monthly CPUE for Collembola sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 202

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Appendix Page

H. Overall mean monthly CPUE for Ephemeroptera sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 203

I. Overall mean monthly CPUE for Hemiptera sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 204

J. Overall mean monthly CPUE for Corixidae sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 205

K. Overall mean monthly CPUE for Aphidoidea sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 206

L. Overall mean monthly CPUE for Gerridae sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 207

M. Overall mean monthly CPUE for Coleoptera sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 208

N. Overall mean monthly CPUE for Dytiscidae sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 209

O. Overall mean monthly CPUE for Hydrophilidae sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 210

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Appendix Page

P. Overall mean monthly CPUE for Diptera sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 211

Q. Overall mean monthly CPUE for Chironomidae sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 212

R. Overall mean monthly CPUE for Diptera (misc) sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006...... 213

S. Mean CPUE for snails sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 214

T. Mean CPUE for snails sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 215

U. Mean CPUE for Oligochaeta sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 216

V. Mean CPUE for Oligochaeta sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 217

W. Mean CPUE for Arachnida sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 218

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Appendix Page

X. Mean CPUE for Arachnida sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 219

Y. Mean CPUE for Hydrachnida sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 220

Z. Mean CPUE for Hydrachnida sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 221

AA. Mean CPUE for Crustacea sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 222

AB. Mean CPUE for Crustacea sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 223

AC. Mean CPUE for Cladocera sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 224

AD. Mean CPUE for Cladocera sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 225

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Appendix Page

AE. Mean CPUE for Copepoda sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 226

AF. Mean CPUE for Copepoda sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 227

AG. Mean CPUE for Ostracoda sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 228

AH. Mean CPUE for Ostracoda sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 229

AI. Mean CPUE for Insecta sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 230

AJ. Mean CPUE for Insecta sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 231

AK. Mean CPUE for Collembola sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 232

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Appendix Page

AL. Mean CPUE for Ephemeroptera sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 233

AM. Mean CPUE for Ephemeroptera sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 234

AN. Mean CPUE for Hemiptera sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 235

AO. Mean CPUE for Hemiptera sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 236

AP. Mean CPUE for Corixidae sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 237

AQ. Mean CPUE for Aphidoidea sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 238

AR. Mean CPUE for Gerridae sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 239

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Appendix Page

AS. Mean CPUE for Coleoptera sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 240

AT. Mean CPUE for Coleoptera sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 241

AU. Mean CPUE for Dytiscidae caught in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 242

AV. Mean CPUE for Hydrophilidae caught in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 243

AW. Mean CPUE for Diptera sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 244

AX. Mean CPUE for Diptera sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 245

AY. Mean CPUE for Chironomidae sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 246

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Appendix Page

AZ. Mean CPUE for Chironomidae larvae sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites...... 247

BA. Number of organisms and frequency of occurrence (number of samples) of major Crustacean and Arachnid taxa caught in benthic samples at two sampling transects, Fourmile (FM), and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – October 2006. The % of total = % of total number of Arachnida and % of total number of Crustacea collected in benthic samples. The % samples = % of total number of benthic samples in which the taxon was collected...... 248

BB. Number of organisms and frequency of occurrence (number of samples) of major Insect taxa collected in benthic samples at two sampling transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – October 2006. The % of total = % of total number of Insecta collected in benthic samples. The % samples = % of total number of benthic samples in which the taxon was collected...... 249

BC. Total monthly counts of each species captured in trap nets set at the Fourmile (FM) and Westside (WS) transects in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each month, trap net catches at sites within each transect were combined. X indicates no trap netting at a transect during a given month...... 250

BD. Length frequencies of speckled dace, Rhinichthys osculus , collected in trap nets at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Midpoints represent 2mm total length size classes. N = 11,548 speckled dace...... 254

BE. Length frequencies of speckled dace, Rhinichthys osculus , collected in trap nets at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005. Midpoints represent 2mm total length size classes...... 255

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Appendix Page

BF. Length frequencies of speckled dace, Rhinichthys osculus collected in trap nets at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – September 2006. Midpoints represent 2mm total length size classes...... 256

BG. Overall length frequencies of fathead minnow, Pimephales promelas , collected in trap nets at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Midpoints represent 2mm total length size classes. N = 5,996 fathead minnow...... 257

BH. Length frequencies of fathead minnow, Pimephales promelas , collected in trap nets at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005. Midpoints represent 2mm total length size classes...... 258

BI. Length frequencies of fathead minnow, Pimephales promelas , collected in trap nets at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – September 2006. Midpoints represent 2mm total length size classes...... 259

BJ. Overall length frequencies of slender sculpin, Cottus tenuis , collected in trap nets at two sampling transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Midpoints represent 2mm total length size classes. N = 610 slender sculpin...... 260

BK. Length frequencies of slender sculpin, Cottus tenuis , collected in trap nets at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005. Midpoints represent 2mm total length size classes...... 261

BL. Length frequencies of slender sculpin, Cottus tenuis , collected in trap nets at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – September 2006. Midpoints represent 2mm total length size classes...... 262

BM. Length frequencies of yellow perch, Perca flavescens , collected in trap nets at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Midpoints represent 10mm total length size classes. . N = 1,239 yellow perch...... 263

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Appendix Page

BN. Length frequencies of yellow perch, Perca flavescens , collected in trap nets at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005. Midpoints represent 10mm total length size classes...... 264

BO. Length frequencies of yellow perch, Perca flavescens , collected in trap nets at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – September 2006. Midpoints represent 10mm total length size classes...... 265

BP. Overall length frequencies of Cyprinidae collected in light traps at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Midpoints represent 2mm total length size classes. N = 1,939 Cyprinidae...... 266

BQ. Overall length frequencies of Cyprinidae collected in light traps at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005. Midpoints represent 2mm total length size classes...... 267

BR. Overall length frequencies of Cyprinidae collected in light traps at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – September 2006. Midpoints represent 2mm total length size classes...... 268

BS. Overall length frequencies of sculpin, Cottus sp. , collected in light traps at two sampling transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Midpoints represent 2mm total length size classes. N = 2,482 Cottidae...... 269

BT. Overall length frequencies of sculpin, Cottus sp. , collected in light traps at two sampling transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005. Midpoints represent 2mm total length size classes...... 270

BU. Overall length frequencies of sculpin, Cottus sp. , collected in light traps at two sampling transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – September 2006. Midpoints represent 2mm total length size classes...... 271

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INTRODUCTION

In their unaltered state, streams in the western United States typically have higher flows during winter and spring, when rain or snowmelt occurs, and lower flows during late summer and early fall, when precipitation is infrequent. At peak flows, streams may escape their banks, whereas during periods of low flow, surface water may be available only in intermittent pools or may disappear completely. Consequently the abundance and quality of habitat available to aquatic organisms in these streams fluctuates seasonally.

Native fish and invertebrate assemblages have adapted to the natural seasonal habitat fluctuations. For example, in California native fish tend to spawn during March, April and May, before streams become intermittent (Moyle 2002). Henning et al. (2007) documented the temporal and spatial importance of large river flood plains as seasonal habitat for both native and non-native fish in the Chehalis River, Washington. The importance of intermittent tributaries as rearing habitat for both anadromous and non- anadromous salmonids is increasingly well documented (Erman and Hawthorne 1976,

Ebersole et al. 2006).

Increasing human demand for water in arid landscapes has led to the damming and diversion of many rivers and creeks. Diversion of water from streams typically results in lower peak flows and longer periods of intermittency during the summer

(Mount 1995). All too often, these physical alterations of streams are accompanied by introductions of non-native fish, placing further ecological strain on native fish.

Numerous studies have shown that such shifts away from natural flow regimes tend to

2 benefit non-native fish over native fish. Marchetti and Moyle (2001) concluded that abundances of non-native fish decreased with increased stream flow in the lower 37 km of Putah Creek. In this California stream, higher flows flushed non-native fish from the system and created favorable reproductive conditions for native fish. Restoration of more natural flow regimes has thus been proposed as a tool to restore and maintain native fish assemblages adversely affected by flow alteration and non-native introductions (Poff et al. 1997, Bunn and Arthington 2002).

The Upper Klamath Basin has received much attention due to the predictably poor habitat conditions affecting its fish populations. Upper Klamath Lake is naturally eutrophic and undergoes seasonal depth fluctuations. Snowmelt contributes much of the water to the tributaries of the lake in pulses, beginning in early spring. This runoff is stored in the lake and released downriver as needed later in the year. During periods of water storage, vast areas of wetlands are covered. After drawdown, wetlands are left dry.

Consequently, much of the habitat available to fish, especially along lake and tributary margins, is seasonal.

One such seasonal habitat is Fourmile Creek. Fourmile Creek historically flowed into Pelican Bay via Harriman Springs and Harriman Creek. Pelican Bay is located in the northwest corner of Upper Klamath Lake. However, since 1922 virtually the entire creek has been diverted at its source, Fourmile Lake, into the neighboring Rogue River drainage for use by the Medford Water District. The original creek bed, which flows only at high water, drops almost 500m in elevation as it flows down the southeast slope of Mt. McLoughlin. Its channel consists of high gradient boulder strewn runs and rapids

interspersed by small pools and backwater eddies. Pieces of large woody debris are

common. Before reaching Pelican Bay the creek crosses about six km of low gradient

valley floor. Reaches in the upper creek have been impacted by water diversion, while its

lower reaches have been severely altered by agriculture and ranching. As the lower creek

approaches Harriman Springs it consists of a series of straight channelized sections

interspersed with meandering flows through grassy pasture land. Upstream of Harriman

Springs, continuous surface flow exists only during late winter to early summer when

rain or snow melt flood the pasture land. As the water table drops, much of the lower

creek becomes intermittent. Only those areas below the water table or below lake level

remain submerged. Harriman Springs and Harriman Creek are continually connected to

Pelican Bay.

The alteration in the hydrodynamics of Fourmile Creek, along with the

introduction of non-native fish species, has undoubtedly had profound effects on the

native fish in this creek. Formal study of the creek’s fish and invertebrates is lacking.

No intensive studies were carried out prior to the commencement of fish stocking in

1925. Brown trout, Salmo trutta , were stocked in 1925; brook trout, Salvelinus fontinalis , were stocked from 1925 through 1956; and rainbow trout, Oncorhynchus mykiss , were stocked in 1950, 1957 and 1961 (United States Department of Agriculture 1998).

Mulligan et al. (2009) conducted an inventory of fish and invertebrates at a number of sites within the Upper Klamath National Wildlife Refuge Marsh near Fourmile Creek. In

July 2004, they expanded their effort to include Fourmile Creek, concentrating on two sites 500m upstream of Harriman Springs. Their preliminary data suggested that

although non-native fish are present in Fourmile Creek, fish native to the Klamath Basin

do not appear to have been significantly displaced by them. Native fish observed in

Fourmile Creek included slender sculpin, Cottus tenuis , marbled sculpin, Cottus

klamathensis , speckled dace, Rhinichthys osculus , tui chub, Gila bicolor , blue chub, Gila

coerulea , and rainbow trout. Introduced fish include the brown bullhead, Ameiurus nebulous , fathead minnow, Pimephales promelas , yellow perch , Perca flavescens , brown trout and brook trout. This preliminary study indicated that lower Fourmile Creek may be an important breeding and nursery area for slender sculpin and speckled dace, native fish that are of increasing concern to the Oregon Department of Fish and Wildlife and

U.S. Fish and Wildlife Service (Mulligan et al. 2009).

Harriman Springs once supported significant spawning runs of short nose suckers,

Chasmistes brevirostris , and Lost River suckers, Deltistes luxatus , both of which are now listed as endangered species and are of interest and concern in the Klamath Basin. The last published documentation of catostomid spawning occurring at Harriman Springs was in 1974 (Andreasen 1975). However, local landowners report seeing adult suckers in

Fourmile Creek as recently as 1988 (Edward Sloan, personal communication, 2005). To help with the recovery of these two species, as well as to increase the overall water quality in Klamath Lake, the diversion of water into the Rogue drainage may be curtailed

(Stubbs and White 1993). If the Fourmile Lake - Fourmile Creek connection is reestablished, base line documentation of existing conditions will be critical in evaluating the effectiveness of any recovery action.

This study was undertaken to further document the seasonal ecology of fish and macroinvertebrates inhabiting lower Fourmile Creek during its peak spring flows and subsequent surface water loss from midsummer through mid fall. The abundance of fish species was examined at different spatial and temporal scales. Monthly species diversity, richness and evenness of fish at each transect was also examined. An analysis of the size distribution, body condition, reproductive state and diet of the four most abundant fish

(two native and two non-native) encountered in the study was also conducted. In addition, the overall and seasonal abundance of the major groups of potential macroinvertebrate prey inhabiting this section of intermittently flowing stream was investigated.

STUDY SITE

Two study transects, designated Fourmile and Westside, were selected because they are characteristic of the habitats found within the low gradient and intermittently flowing section of lower Fourmile Creek. Fish and invertebrates were collected monthly at two representative sites within each transect until it became dry. Whenever possible the position of the sites within a transect remained constant over the course of the study.

However, site locations were adjusted when flows were too high for effective sampling or when a site had dried up. Sample transects and auxiliary sample sites are shown in

Figure 1. World Geodetic System (WGS84) coordinates for the transect boundaries and sampling sites within the study section of Fourmile Creek are shown in Table 1.

The Fourmile transect extends from the low-water confluence of Fourmile Creek with Harriman Springs upstream one km to the Rocky Point Road Bridge. A dike runs along the entire southern bank of this portion of Fourmile Creek, separating it from adjacent cattle pastures. The upstream section of the northern bank is also diked. During spring and early summer Pelican Bay inundates the lower 150m of creek channel and its surrounding meadows and pastures. The mouth and channel become more defined as the water level subsides. Eventually, during late summer an alluvial bar first severely limits and then finally blocks fish passage into and out of the creek. Once confined to the channel, the wetted width of the creek is fairly constant due to diking. The channel is U- shaped over much of its length, with minimal pool and riffle development. Maximum water depths range from 0 to 1.6m depending upon season. Substrate in this transect is

0 m 500 m

Figure 1. Aerial photograph depicting the lower four kilometers of Fourmile Creek and the Fourmile and Westside transects, Upper Klamath Lake, Oregon. Fish and invertebrates were sampled March – October 2005 and March – October 2006. Data available from the Oregon Imagery Explorer.

Table 1. Coordinates for the Fourmile and Westside transect boundaries and sampling sites within the lower 2.4 kilometers of Fourmile Creek, Upper Klamath Lake, Oregon. Fish and invertebrates were collected March – October 2005 and March – October 2006. Coordinates are projected in World Geodetic System (WGS 84).

Site North West Fourmile lower transect downstream boundary (mouth) 42.467267 -122.099126

Fourmile lower transect trap net site 42.466213 -122.099899

Fourmile lower transect upper boundary 42.464900 -122.101034

Fourmile upper transect trap net site 42.464091 -122.102003

Fourmile upper transect upstream boundary (Rocky Pt. Rd. Bridge) 42.462503 -122.106011

Westside lower transect downstream boundary (Westside Rd. Bridge) 42.456000 -122.116000

Westside lower transect trap net site 42.456024 -122.117447

Westside lower transect upper boundary 42.459427 -122.118559

Westside upper transect trap net site 42.455859 -122.119794

Westside pasture and upper boundary 42.456168 -122.720418

8 9

dominated by hard clay deposits with scattered gravel and sparse cobbles. Submerged

aquatic vegetation in the creek channel is not abundant during most of the year; however,

at high water a bordering meadow to the west of the creek, sparsely wooded with

willows, Salix, and aspen, Populus tremuloides , is flooded. Grasses, both submerged and emergent are the dominant aquatic vegetative cover along the channel margin. Mid- channel vegetation consists primarily of submerged pondweed, Potamogeton spp., and spineless hornwort, Ceratophyllum echinatum . The mid-channel plant biomass increases during midsummer, but dies back in September and October.

The same two Fourmile sites utilized by Mulligan et al. (2009) were selected as sampling locations in this study: Fourmile lower and Fourmile upper (Figures 2, 3). The

Fourmile lower site was located 100m upstream of the low-water confluence with

Harriman Springs. The Fourmile upper site was located 500m upstream of Harriman

Springs. Low water levels in September of 2005 and August of 2006 required the upper site to be moved downstream 150m.

The Westside transect extends 700m upstream from the Westside Road Bridge

(Figure 1). Its upstream boundary is a large pasture. Both banks are diked throughout the lower 600m of this transect; however, channelization ceases at the pasture, which is inundated during high water levels. Maximum water depths range from 0 to 1.75m. The dikes are largely free of rip-rap, except for large (greater than one meter in largest dimension) boulders placed along the boundary between the northern dike and the pasture. The boulders extend to the bottom of the channel; other large rocks are sparsely

0 m 225 m

Figure 2. Aerial photograph depicting the location of the Fourmile transect sites in Fourmile Creek, Upper Klamath Lake, Oregon. Sampling for fish and invertebrates at this transect occurred March – October 2005 and March – October 2006. Data available from the Oregon Imagery Explorer.

Figure 3. Photographs showing seasonal water level changes in the Fourmile upper site, Fourmile Creek, Upper Klamath Lake, Oregon. Both photographs look upstream at the Fourmile upper trap net site. The one on the left was taken in May 2006, while the photograph on the right was taken in September 2006.

12 distributed across this transect. Substrate in the Westside transect is comprised of fine and coarse sands, gravels, small cobbles, and both allochthonus and autochthonous organic debris. The stream is lined with aspen and pine, Pinus spp., along its course.

The bottom of the channel is densely covered with grasses, rushes, Scirpus spp., and sedges, Carex spp. With the onset of spring, when peak flow occurs, these plants are

largely dormant and their blades are forced to the bottom by the stream flow. As the flow

drops and the plants start to grow, their blades reach to the surface of the water. During

mid-summer, the intermittent puddles that remain are almost completely hidden by thick

emergent vegetation. Small and large woody debris are common in the stream channel.

Sampling within the Westside transect occurred at three sites, all on U.S. Forest

Service land: Westside lower, Westside upper and Westside pasture (Figures 4, 5). The

Westside lower site was located 2.25km upstream of the confluence of Fourmile Creek

with Harriman Springs. The Westside upper site was located 2.5km upstream of

Harriman Springs. During May 2006, the velocity of water flowing through the Westside

lower site prevented secure anchoring and fishing of the trap net and light traps. Soon

after being set, the gears quickly clogged with drifting vegetation and were pushed

downstream. After repeated failed attempts to securely place the gears at the proposed

Westside lower site, it was decided to conduct sampling that month inside the flooded

pasture, 100m upstream of the Westside upper site. During both study years, monthly

sampling ceased at the Westside transect when it became dry. Final annual Westside

samples were taken in August 2005 and July 2006.

0 m 150 m

Figure 4. Aerial photograph showing the location of the Westside transect sites, Fourmile Creek, Upper Klamath Lake, Oregon. Sampling for fish and invertebrates at this transect occurred April – August 2005 and March – July 2006. Data available from the Oregon Imagery Explorer.

Figure 5. Photographs showing seasonal water level changes at the Westside lower site, Fourmile Creek, Upper Klamath Lake, Oregon. The upper photograph was taken at the commencement of sampling at the site in April 2005, the middle photograph was taken in June 2005, and the bottom photograph was taken in August 2005, when sampling at this site was suspended for the season.

MATERIALS AND METHODS

Field Collection

Monthly collections occurred at each transect. Sampling was done from March through October 2005 and 2006. Both sites within a transect were sampled on the same day. The Fourmile and Westside transects were sampled on subsequent days. Up to five sampling methods were utilized to collect fish and invertebrates: trap net, pole seine, light trap, plankton tow and benthic core. Adult and juvenile fish were sampled with trap nets and by pole seining. Juvenile and larval fish and potential invertebrate prey were sampled with both quatre-foil light traps and with plankton net tows. Benthic cores were also taken to sample potential prey items. This project was approved by Humboldt State

University’s Institutional Animal Care and Use Committee (IACUC approval number

03/04.F.02-A). A Yellow Springs Instrument Multiprobe 6600 Data Logger was used to record water temperature, dissolved oxygen, pH, and conductivity prior to any fish sampling at a site. These water parameter readings were taken at the channel margin and at the bottom of the deepest part of the channel when gear was set in the afternoon (PM readings) and fished the next morning (AM readings).

When water depths at the Fourmile and Westside sites were greater than 0.25 m, a trap net (6.4 mm mesh with 0.7 X 10.6 m wings and lead and 0.7 X 1.0 m frame and two internal fykes) was set to collect fish. The trap net was deployed with the wings parallel to the north bank and the lead perpendicular to the shore. The trap net was set in the afternoon and fished until the next morning. Captured fish were held in live wells during 15

16 processing. Fish were identified to species. A representative sample of up to 12 fish of each species caught in each trap net collection was retained for later measurement, determination of reproductive status and condition factor, and diet analysis at Humboldt

State University’s Telonicher Marine Laboratory. Subsamples of unidentifiable fish were also retained for laboratory identification. All retained fish were sacrificed in 250 ppm

MS-222 before being fixed in 10 percent formalin. Whenever possible all remaining fish in the trap net sample were measured to the nearest mm (TL), and counted before being released back into the creek at the sampling site. When large catches prevented prompt handling, representative subsamples from each live well were measured and counted.

The use of traps may influence results of a diet study for several reasons.

Prolonged holding times usually associated with traps increase the level of post-capture digestion of stomach contents (Bowen 1996). In addition, as fish are retained in a relatively small area and in unnatural densities, they may consume foods they would not normally eat. To determine if utilizing overnight trap net captured fish biased the diet analysis in this study, monthly qualitative samples of fish at each transect were obtained by pole seining. The pole seine measured 3.7 X 1.8m and had 3mm stretch mesh. When pole seining was unsuccessful, a trap net, set for one hour, was used. To minimize any influence that previous trap-net sampling might have had upon the natural feeding habits of the fish at a site, every attempt was made to collect the short duration/mixed gear gut samples twenty-four hours before or after overnight trap netting occurred at a site. These short duration/mixed gear gut samples were collected between 1600 and 2100 hrs, overlapping with the overnight trap net fishing times. Representative subsamples of each

17 fish species caught were sacrificed in 250 ppm MS-222 before being fixed in 10% formalin.

Larval and juvenile fish, as well as potential neustonic prey items, were sampled with both light traps and plankton net tows. Light traps were the same custom made, quatre-foil type used by Mulligan et al. (2009). Two light traps were set at each site in the evening and retrieved the next morning prior to fishing the trap net. One light trap was placed in aquatic vegetation, while the other was placed in open water. Replicate two minute plankton tows using a 12cm diameter 333 µm mesh plankton net were taken prior to setting trap nets and light traps at each site. Plankton samples were always conducted on foot at the Westside sites. However, when water levels permitted, sampling was done by boat at the Fourmile sites. Due to seasonally fluctuating surface water and vegetation levels, light traps and plankton nets were not always used concurrently. Light traps worked efficiently in both vegetated and non-vegetated water, so long as there was sufficient light diffusion to attract positively phototactic specimens. Plankton nets on the other hand, worked best in areas free of vegetation, where water flow into the plankton net was not interrupted by accumulated debris. Thus, light trap samples were taken in both vegetated and open water while plankton samples were taken only in areas free of aquatic vegetation. When taking a plankton sample, large pieces and (/or) clumps of aquatic vegetation were intentionally excluded from the net. Because of this protocol, more light trap sets were made than plankton tows. Samples were rinsed over a 250 µm

mesh sieve. If fish were present in the sample, the entire sieve containing the sample was

18 suspended in a 250 ppm solution of MS-222 for five minutes. Samples were fixed in 10% formalin.

Two replicate samples of potential benthic prey items were also taken at each site.

A 10cm diameter corer was driven into the substrate to a depth of 5cm to obtain a benthic sample, which was then washed with filtered water over a 500 µm mesh sieve before being fixed in 10% formalin.

Sample Processing and Analysis

In the laboratory, all samples were transferred into 40% isopropyl alcohol.

Identification of all fish retained from each overnight trap net sample was verified. Fish were measured (total length (TL)) to the nearest mm. Light trap and plankton samples were rinsed through a 180 µm mesh sieve before being processed under a dissection

microscope. Benthic samples were rinsed through a 333 µm mesh sieve with tap water to

remove excess clay and fine debris. Invertebrates were then picked and counted under a

dissection microscope. Juvenile and larval fish taken in plankton tows and light traps

were enumerated, measured to the nearest mm (TL) and identified to the lowest possible

taxonomic level.

Aquatic insects were classified to at least order and categorized by life history

stage following Pennak (1989). Representative individuals from the following insect

orders were further identified to family and (or) genus: Coleoptera, Diptera,

Ephemeroptera, Hemiptera, Homoptera and Odonata. The number of individuals of each

life history stage within a specific taxonomic group was counted. For enumeration,

Annelids were grouped into Oligochaeta and Euhirudinea. Crustaceans were grouped into Cladocera, Copepoda, Isopoda or Amphipoda. Mollusks were grouped into snails and clams. Annelids, crustaceans and mollusks were not divided into life history stages.

R 2.8.0 was utilized for all data analysis (R Development Core Team 2008).

Total numbers and frequency of occurrence of specific invertebrate taxa were used to describe the overall macroinvertebrate community. Total numbers of each fish species were used to describe the overall fish community. Overall, monthly and site- specific comparisons of both fish and invertebrate taxa were carried out using catch-per- unit-effort (CPUE). For a given taxon level t, CPUEs of trap nets (TR), light traps (LT),

and plankton tows (PL) were calculated. Trap net CPUE was calculated as

number individuals CPUETR # ind 16 hr = *16 (fishing hours / where 16 is the average number of hours trap nets were fished. Light trap CPUE was

calculated as

number individuals CPUELT # ind 12 hr = *12. (hours darkness +2) / Light traps were fished over a range of photic conditions: afternoon, dusk, night and dawn. The hours of darkness (hours between sunset and sunrise) varied seasonally from

12 hours during March, to 8.6 hours during June and 13 hours during October. During this study, both riparian vegetation and the surrounding terrain provided sufficient shade for the light traps to begin attracting taxa about an hour before sunset and to remain fishing for about an hour after sunrise. Thus, when calculating the time a specific light

20 trap was fished, two hours were added to the hours of darkness to account for catches made during these transitional periods. To standardize catches across seasons, sample

CPUE was first calculated for a single hour and then multiplied by 12 hours, the average total hours of darkness across all months.

Plankton tow CPUE was calculated as

number individuals CPUEPL # ind m3 = volume of water (m3) / where the estimated effort (volume of water sampled) for each plankton sample taken either by boat or on foot was 1.4m3 and 1.1m3 respectively.

Overall mean catch-per-unit-effort was calculated for each fish species by dividing the total number of each species taken during the two years of the study by the total trap net fishing time. In addition, overall and transect-specific annual mean CPUEs of fish during the months of concurrent trap netting at the Fourmile and Westside transects in both 2005 and 2006 were calculated. Trap netting was carried out at the

Fourmile transect March – October 2005 and March – September 2006. At the Westside transect, trap nets were set April – July 2005 and March – July 2006.

Total monthly catches of both fish and potential invertebrate prey were calculated for each gear type at each site and transect. The composition of the fish population was assessed at the species and size class levels. In addition, the composition of native versus non-native fish was calculated. The CPUE of the potential invertebrate prey available to fish was calculated at the order and family levels. These CPUE values were calculated separately for light trap and plankton samples and plotted for interpretation.

Total numbers of fish in overnight trap net catches were used to calculate monthly species richness, monthly species diversity, and monthly species evenness at each transect. Monthly species richness (S) was calculated as the total number of species caught at a given transect in a given month. Monthly species diversity (H) was assessed using the Shannon index (Krebs 1989). Shannon Diversity was calculated as

= − ∗ where is the relative abundance ( of each species (i) at a given transect in a given month. Higher H values indicate higher diversity. Monthly species evenness (J) is a

measure of each species’ numerical contribution to the total monthly catch and was

calculated at each transect using Pielou’s index (Pielou 1966). Species evenness was

calculated as

J = . Species evenness values range from zero (most variation) to one (least variation). The

Vegan Community Ecology Package in R (Oksanen et al. 2008) was used to calculate fish community characteristics.

Fish retained from each overnight trap net sample were used to assess reproductive state and condition factor for speckled dace, fathead minnow, slender sculpin and yellow perch. For each month, catches at the two sites within each of the

Fourmile or Westside transects were combined for analytical purposes. For each transect, subsamples of 12 individuals of each of these four fish species caught in the overnight

22 trap net were randomly selected. All fish in a sample were assigned a number and individuals were selected using random number tables. When possible, fish from both the lower and upper sites within a transect were selected as per Mulligan et al. (2009). If fewer than 12 individuals were captured for that month, all were processed.

Prior to examination for selected external parasites and overall condition, total length (1.0mm), standard length (0.025mm) and total fish wet weight (0.01g) were taken for each of the subsampled individuals of a given species. Subsequently, the gastrointestinal tract and gonads were removed from each fish and cleaned of tissues and fats. The liver in non-cyprinid fish was also removed. Sex of the fish (female, male or indeterminate) was recorded. The removed organs were then blotted and individually wet weighed to the nearest 0.0001g. Gonads and gastrointestinal tracts were saved.

Gonadosomatic index (GSI), Fulton-type condition factor (CF1 and CF3) and hepatosomatic index (HSI) were calculated using the morphometrics taken in the above steps. Gonadosomatic index was calculated as

gonad wt G I = * 100. gut-free, gonad-free fish wt S The two Fulton-type condition factors and hepatosomatic index were calculated as

fish wt CF1 gm cm 3 = * 100 standard length 3 / gut-free, gonad-free fish wt CF3 gm cm 3 = * 100 standard length 3 / liver wt H I = * 100. gut-free, gonad-free fish wt S

The first condition index (CF1) was based upon total body weight, while the second

(CF3) relied upon the gonad-free, gut-free body weight. For each species, both CF1 and

CF3 were calculated by size class, first for all individuals, and then separately for each sex. Samples from the 2005 and the 2006 sampling years were combined in this analysis.

Gastrointestinal tracts from the same individuals used for condition factor analysis were used for diet analysis. Because morphology differed across the species being examined, family specific protocols were used. In cyprinids (speckled dace and fathead minnow), which lack a well-defined stomach, the anterior 50 percent of the intestinal tract was utilized for diet analysis. For slender sculpin and yellow perch, only the well- defined stomach and portion of the intestine immediately anterior to the pyloric caecae were used. Contents of the respective digestive tract segments were removed under a dissection microscope, examined, sorted, and classified into prey items of the appropriate taxonomic level. All prey taxa were enumerated. Blotted wet weights of each taxonomic or food classification were taken to the nearest 0.0001g. For diet analysis of fish from overnight trap net samples, digestive tract contents were grouped first by fish size class and then by season and size class. Within each grouping, percent number, percent weight, and percent frequency of occurrence (Hyslop 1980) of each prey type was calculated. Percent number of each prey group was calculated as

# of items of a particular classification % number = *100. total # of items Percent weight of each prey grouping was calculated as

weight of items of a particular classification % weight = *100 total weight of items .

Percent frequency of occurrence of each prey grouping was calculated as

# of stomachs containing a particular classification % freq occur = *100 total # of stomachs . For each seasonal size grouping, an Index of Relative Importance (IRI) was calculated using these three percentages as per Cailliet et al. (1986). Index of Relative Importance was calculated as

IRI = % number + % weight) * (% frequency of occurrence . Within each seasonal size group, the IRI for all prey types were summed and the relative

importance of each prey type within the grouping was expressed as a percentage of this

total IRI (%IRI). The above procedure also was followed for fish captured by seine and

short trap net sets (short duration/mixed gear samples); however, these fish were grouped

only by season and size class for analysis because of the seasonal patchiness of samples.

Seasonal, size specific (small vs. large) dietary overlap between the two most

abundant fish, native speckled dace and non-native fathead minnow, was calculated using

Schoener’s (1970) index of overlap (S 10 ). Following Armstrong et al. (1995), %IRI values were used to represent proportions of prey in diets. Dietary overlap was calculated as

= 1−0.5 −

where Pxi = the proportion of prey i (%IRI) in the diet of small (or large) speckled dace;

Pyi = the proportion of prey i (%IRI) in the diet of small (or large) fathead minnow; and j

= the number of prey types. For both cyprinids, small fish were those individuals <

50mm SL and large fish were those individuals ≥ 50mm SL. Because the grouping of prey items may influence the overlap value between two species (Greene and Jaksic

1983), seasonal dietary overlap was calculated using two levels of prey taxon resolution.

First, prey taxa were consolidated into five major taxa (Annelida, Crustacea, Insecta,

“gorp” and “other”). “Gorp” is a complex mix of organic and inorganic debris (Mulligan et al. 2009). Secondly, diet overlap was calculated using higher taxa resolution (j=27 prey types). S10 values range from 0.00 (no foods shared) to 1.00 (all foods consumed in

the same proportions). For this analysis, S 10 ≥ 0.6 (Schoener 1970) indicated significant

dietary overlap between small (or large) speckled dace and fathead minnow.

RESULTS

Water Quality

Environmental conditions observed at the Fourmile and Westside transects over the entire course of the study are summarized in Tables 2 and 3. In both transects, the overall mean water temperature was lower at the lower channel sites. Of the two transects, Fourmile was the coolest on average, but the greatest temperature extremes occurred at Westside, where individual temperature readings ranged from 1.5˚C to

27.7˚C. Within the Fourmile transect, the lowest overall average temperature occurred at the lower site’s channel bottom while the highest overall average temperature occurred along the margins of the upper site. In the Westside transect, the highest mean overall,

AM and PM temperatures were associated with the margins of the upper site, while the lowest occurred in the upper channel. Water quality parameters were measured at the pasture site only during May 2006 when high creek flow prevented trap netting at the

Westside lower site.

Overall mean dissolved oxygen values were generally high at both Fourmile and

Westside. The upper sites of both transects had the highest overall mean concentration of oxygen. Westside average pH values were slightly more acidic than average Fourmile values. Within each transect, overall average pH values were similar across sites. Total mean specific conductivity was lower at the Westside sites than at the Fourmile sites.

Plots of average monthly AM and PM temperature, dissolved oxygen, pH and specific conductivity values measured at the Fourmile and Westside transects are 26

Table 2. Mean morning, afternoon and overall mean water temperature, dissolved oxygen, pH and specific conductivity values recorded at the lower and upper sites of the Fourmile transect, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – October 2006. Channel values represent readings taken 0.3m above the bottom in the middle of the channel. Margin values represent readings taken 0.3m below the water surface, immediately adjacent to the trap net mouth. Lower Lower Upper Upper Channel Margin Channel Margin Temperature Mean 10.3 11.5 11.6 12.7

AM 8.8 9.7 9.8 10.4

PM 12.0 13.5 13.3 15.0

Dissolved Oxygen (% sat)

Mean 97.8 97.1 99.2 98.4

AM 88.0 87.7 87.8 86.0

PM 106.9 106.9 110.5 108.5

Dissolved Oxygen (mg/L)

Mean 9.5 9.1 9.3 9.0

AM 8.9 8.6 8.6 8.3

PM 9.9 9.6 10.0 9.4

Mean 7.1 7.1 7.1 7.1

AM 6.9 6.9 7.0 7.0

PM 7.3 7.3 7.3 7.2

Specific conductivity (mS/cm)

Mean 67.7 65.7 69.0 67.2

AM 68.1 65.9 65.8 62.1

PM 67.3 65.3 68.5 67.2

Table 3. Mean morning, afternoon and overall mean water temperature, dissolved oxygen, pH and specific conductivity values recorded at the lower, upper, and pasture sites of the Westside transect, Fourmile Creek, Upper Klamath Lake, Oregon, April – August 2005 and March – July 2006. Channel values represent readings taken 0.3m above the bottom in the middle of the channel. Margin values represent readings taken 0.3m below the water surface, immediately adjacent to the trap net mouth. The pasture site was only sampled in May 2006. Lower Lower Upper Upper Pasture Pasture Channel Margin Channel Margin Channel Margin Temperature Mean 12.7 12.8 12.2 13.8 10.5 11.0 AM 10.7 10.9 10.0 11.2 9.0 9.5 PM 14.7 15.0 14.4 16.9 12.0 12.6 Dissolved Oxygen (% sat) Mean 83.3 83.8 84.9 90.7 90.5 90.2 AM 67.1 69.5 68.4 78.3 83.8 84.2 PM 98.0 101.2 101.0 109.3 97.7 97.5 Dissolved Oxygen (mg/L) Mean 7.8 7.9 8.0 8.2 8.7 8.5 AM 6.8 7.0 7.0 7.7 8.3 8.2 PM 8.7 8.9 9.0 9.2 9.0 8.9 PH Mean 6.7 6.7 6.7 6.8 6.4 6.2 AM 6.5 6.6 6.5 6.6 6.1 6.2 PM 6.8 6.9 6.9 7.0 6.7 6.2 Specific conductivity (mS/cm) Mean 50.2 50.2 46.5 47.6 90.5 90.2 AM 50.4 50.5 47.1 46.2 83.8 84.2 PM 50.2 50.0 46.0 47.8 97.7 97.5

29 provided in Figures 6 to 13. Distinct seasonal and diel patterns were present in water quality readings. Individual monthly average temperature, at both transects, followed a similar annual pattern (Figures 6, 7). Temperatures generally increased until late summer and then decreased. During May, AM and PM water temperatures were lower, coinciding with snowmelt runoff. This decrease was most noticeable in the Fourmile upper site and in the Westside sites. Diel variation in temperature at the Fourmile sites was more constant in the lower channel than in the upper channel. The margins of both

Fourmile sites showed increasing differences in diel temperature during later months. At

Westside, the greatest variation in diel temperatures occurred in the upper margin.

Dissolved oxygen at all Fourmile sites followed a similar seasonal trend: a decrease in April and subsequent increase in July (Figures 8, 9). Diel variation in mean monthly dissolved oxygen was similar across Fourmile sites during most months. From

March through June of 2005 and in March, May and June of 2006, AM and PM readings showed little diel variation. During later months diel variation in AM and PM readings were greater. Westside sites showed a decrease in dissolved oxygen, especially in morning readings, during later months.

Monthly mean morning and afternoon pH values tended to increase from May through September at the Fourmile sites (Figure 10). Diel pH variation was greater in later months than in early months. This variation was especially apparent in 2005 margin readings. pH readings at the Westside sites generally showed a general decrease during a sampling season (Figure 11). Low pH values are usually correlated with low dissolved oxygen and high levels of carbon dioxide. Carbon dioxide levels were not specifically

FM Lower - Mid Channel 30 Morning 25 Afternoon

10 Temperature (C) Temperature 5

MAMJJASOMAMJJASO

FM Lower - Channel Margin 30

10 Temperature (C) Temperature 5

MAMJJASOMAMJJASO

FM Upper - Mid Channel 30

10 Temperature (C) Temperature 5

MAMJJASOMAMJJASO

FM Upper - Channel Margin 30

25 20

15 10 Temperature (C) Temperature 5

MAMJJASOMAMJJASO 2005 2006

Figure 6. Mean monthly morning and afternoon temperature readings recorded at the lower and upper Fourmile transect sites in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – October 2006. Mid channel values represent readings taken 0.3m above the bottom. Channel margin values represent readings taken 0.3m below the water surface.

WS Lower - Mid Channel 30 Morning 25 Afternoon 20 15 10 5 Temperature (C) Temperature 0

MAMJJASOMAMJJASO

WS Lower - Channel Margin 30 25 20 15 10 5 Temperature (C) Temperature 0

MAMJJASOMAMJJASO

WS Upper - Mid Channel 30 25 20 15 10 5 Temperature (C) Temperature 0

MAMJJASOMAMJJASO

WS Upper - Channel Margin 30 25 20 15 10 5 Temperature (C) Temperature 0

MAMJJASOMAMJJASO 2005 2006

Figure 7. Mean monthly morning and afternoon temperature readings recorded at the lower and upper Westside transect sites in lower Fourmile Creek, Upper Klamath Lake, Oregon, April – August 2005 and March – July 2006. Mid channel values represent readings taken 0.3m above the bottom. Channel margin values represent readings taken 0.3m below the water surface.

FM Lower - Mid Channel 18 Morning 16 Afternoon 14 12 10

D D O (mg/L) 8 6 4

MAMJJASOMAMJJASO

FM Lower - Channel Margin 18 16 14 12 10

D O D (mg/L) 8 6 4

MAMJJASOMAMJJASO

FM Upper - Mid Channel 18 16 14 12 10

D D O (mg/L) 8 6 4

MAMJJASOMAMJJASO

FM Upper - Channel Margin 18 16 14 12 10

D D O (mg/L) 8 6 4

MAMJJASOMAMJJASO 2005 2006

Figure 8. Mean monthly morning and afternoon dissolved oxygen readings at the lower and upper Fourmile transect sites in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – October 2006. Mid channel values represent readings taken 0.3m above the bottom. Channel margin values represent readings taken 0.3m below the water surface.

WS Lower - Mid Channel Morning 15 Afternoon 10

5 D D O (mg/L)

MAMJJASOMAMJJASO

WS Lower - Channel Margin

5 D D O (mg/L)

MAMJJASOMAMJJASO

WS Upper - Mid Channel

5 D O D (mg/L)

MAMJJASOMAMJJASO

WS Upper - Channel Margin

5 D O D (mg/L)

MAMJJASOMAMJJASO 2005 2006

Figure 9. Mean monthly morning and afternoon dissolved oxygen readings recorded at the lower and upper Westside transect sites in lower Fourmile Creek, Upper Klamath Lake, Oregon, April – August 2005 and March – July 2006. Mid channel values represent readings taken 0.3m above the bottom. Channel margin values represent readings taken 0.3m below the water surface.

FM Lower - Mid Channel 9 Morning 8 Afternoon

7 pH

MAMJJASOMAMJJASO

FM Lower - Channel Margin 9

7 pH

MAMJJASOMAMJJASO

FM Upper - Mid Channel 9

7 pH

MAMJJASOMAMJJASO

FM Upper - Channel Margin 9

pH 7

MAMJJASOMAMJJASO 2005 2006

Figure 10. Mean monthly morning and afternoon pH readings at the lower and upper Fourmile transect sites in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – October 2006. Mid channel values represent readings taken 0.3m above the bottom. Channel margin values represent readings taken 0.3m below the water surface.

WS Lower - Mid Channel 9 Morning 8 Afternoon

pH 7

MAMJJASOMAMJJASO

WS Lower - Channel Margin 9

pH 7

MAMJJASOMAMJJASO

WS Upper - Mid Channel 9

pH 7

MAMJJASOMAMJJASO

WS Upper - Channel Margin 9

pH 7

MAMJJASOMAMJJASO 2005 2006

Figure 11. Mean monthly morning and afternoon pH readings recorded at the lower and upper Westside transect sites in lower Fourmile Creek, Upper Klamath Lake, Oregon, April – August 2005 and March – July 2006. Mid channel values represent readings taken 0.3m above the bottom. Channel margin values represent readings taken 0.3m below the water surface.

36 measured; however, the combined plant and animal respiration and lack of flow experienced during June through August likely resulted in elevated levels of dissolved carbon dioxide, which drove down the pH during the night.

Unlike pH and other water parameters, mean specific conductivity readings showed little diel variation (Figures 12, 13). In both the Fourmile and Westside transects, mean specific conductivity levels were similar across sites within a given month. With the exception of steep declines during May, when snow runoff provided water with a lower ionic concentration, mean conductivity remained constant at the Fourmile transect.

At the Fourmile transect, the highest mean conductivity values occurred during fall; at the

Westside transect (where surface water disappeared in August) high mean conductivity values occurred during spring. During other parts of the year, input from springs and slow moving surface water resulted in relatively constant specific conductivity readings at both transects.

FM Lower - Mid Channel 125 Morning 105 Afternoon 85

Conductivity (mS/cm) 25

MAMJJASOMAMJJASO

FM Lower - Channel Margin 125

105

Conductivity (mS/cm) 25

MAMJJASOMAMJJASO

FM Upper - Mid Channel 125

105

Conductivity (mS/cm) 25

MAMJJASOMAMJJASO

FM Upper - Channel Margin 125

105

Conductivity (mS/cm) 25

MAMJJASOMAMJJASO 2005 2006

Figure 12. Mean monthly morning and afternoon specific conductivity readings recorded at the lower and upper Fourmile transect sites in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – October 2006. Mid channel values represent readings taken 0.3m above the bottom. Channel margin values represent readings taken 0.3m below the water surface.

WS Lower - Mid Channel 125 Morning 105 Afternoon 85 65 45 25 Conductivity (mS/cm) MAMJJASOMAMJJASO

WS Lower - Channel Margin 125 105 85 65 45 25 Conductivity (mS/cm) MAMJJASOMAMJJASO

WS Upper - Mid Channel 125 105 85 65 45 25 Conductivity (mS/cm) MAMJJASOMAMJJASO

WS Upper - Channel Margin 125 105 85 65 45 25 Conductivity (mS/cm) MAMJJASOMAMJJASO 2005 2006

Figure 13. Mean monthly morning and afternoon specific conductivity readings recorded at the lower and upper Westside transect sites in lower Fourmile Creek, Upper Klamath Lake, Oregon, April – August 2005 and March – July 2006. Mid channel values represent readings taken 0.3m above the bottom. Channel margin values represent readings taken 0.3m below the water surface.

Potential Macroinvertebrate Prey

Table 4 lists all identified macroinvertebrate taxa caught in light trap, plankton and benthic samples. A total of 71,777 invertebrates were captured in the 98 light trap sets; 7,961 invertebrates were captured in the 92 plankton tows and 3,562 were captured in the 100 benthic samples taken. Light trap and plankton results will be discussed first because samples from the two gears were similar in composition.

Sampling effort for light trap and plankton samples taken at each of the Fourmile and Westside transects is summarized in Appendices A and B. A total of 98 light trap sets were made between March 2005 and September 2006. The total fishing effort for all light trap samples was 1,160 hours. During this same period 92 plankton tows were taken, sampling a total volume of 117.1m3 of water.

At the Fourmile transect, light traps were set March through October 2005 and

March through September 2006. Plankton tows were taken March through October 2005,

and March through September 2006. No plankton or light trap samples were taken in

October of 2006, as the Fourmile transect had become a series of narrow, shallow,

intermittent pools. During September and October 2005 and September 2006, plankton

samples were taken on foot at the Fourmile transects because water levels prevented boat

access into the creek. During other months plankton samples at the Fourmile transect

were collected by boat.

At the Westside transect, light trap samples were collected April – August 2005

and March – July 2006. Plankton samples were taken April – June 2005 and March –

Table 4. Invertebrate taxa collected in light traps, plankton tows and benthic cores at the Fourmile and Westside transects in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – October 2006.

Taxon Common Name Cnidaria hydroids Platyhelminthes flatworms Nematoda roundworms Mollusca Bivalvia clams, fingernail clams Gastropoda ------limpets ------snails Annelida Hirudinea leeches Oligochaeta oligochaetes Arthropoda Arachnida Hydrachnida water mites Oribatida oribatid mites Araneae spiders Crustacea Amphipoda scuds Conchostraca clam shrimps Cladocera Daphnia, water fleas Copepoda copepods Ostracoda ostracods Insecta Diplura two-pronged bristletails Collembola springtails Ephemeroptera mayflies Baetidae ------

Taxon Common Name Odonata Anisoptera dragonflies Zygoptera damselflies Hemiptera Aphidoidea aphids Cicadellidae leafhoppers Corixidae water boatmen Delphacidae plant hoppers Gerridae water striders Macrovelidae macrovelid shore bugs Nepidae water scorpions Notonectidae backswimmers Belostomatidae giant water bugs Hymenoptera ants, bees & wasps Trichoptera caddis flies Lepidoptera moths & butterflies Megaloptera * alderflies Coleoptera beetles Cantharidae soldier beetles Carbaidae ground beetles Chrysomelidae leaf beetles Curculionidae snout beetles Dytiscidae predacious diving beetles Elmidae riffle beetles Haliplidae crawling water beetles Gyrinidae whirling beetles Hydrophilidae water scavenger beetles

Taxon Common Name Coleoptera (continued) Hydraenidae minute moss beetles Microsporidae Minute bog beetles Salpingidae narrow-waisted bark beetles Scirtidae marsh beetles Staphylinidae rove beetles Diptera Cecidomyidae thrips Ceratopogonidae biting midges, no-see-ums Chaoboridae phantom midges Chironomidae midges Culicidae mosquitoes Dolichopodidae long-legged flies Empididae aquatic dance flies Muscidae aquatic muscids Ephydridae brine/shore flies Sciomyzidae marsh flies Simuliidae black flies Stratiomyidae soldier flies Tabanidae horse and deer flies Tipulidae crane flies * Indicates taxon only captured in benthic cores.

July 2006. The upper Westside site was completely dry by August of both 2005 and

2006. Light trap samples were taken only at the Westside lower site in August 2005 due to low water levels at the upper site. During July and August 2005, no plankton samples were taken at the Westside transect because virtually all available water was densely covered by both submerged and emergent vegetation. However, plankton tows were possible at both Westside sites during July 2006, because pockets of water remained free of thick aquatic vegetation.

Overall summaries of taxa caught in light traps and plankton tows, including total numbers captured and frequency of occurrence, can be found in Tables 5 and 6.

Invertebrates from six phyla were caught. Mollusca, Annelida and Arthropoda were the most numerous and frequently encountered phyla in light trap and plankton samples.

Cnidaria, Platyhelminthes and Nematoda comprised less than two percent of the total number of invertebrates captured in both light trap and plankton samples. Of these three relatively sparse phyla, Cnidaria were both the most frequently encountered and had the highest overall number of individuals recorded. All Cnidaria encountered were hydroids and were primarily captured in plankton tows.

Three groups of Mollusca were captured during the study. Bivalves were extremely sparse in both light trap samples (one individual captured) and plankton samples (three individuals captured). Pre-settlement limpets were only found in two percent of the plankton samples and were entirely absent in the light trap samples. Snails dominated both the overall number and the percent frequency of occurrence of Mollusca

Table 5. Number of organisms and frequency of occurrence (number of samples) of major invertebrate taxa caught in light traps at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. The % of total = % of total number of invertebrates collected in light traps. The % of samples = % of total number of light trap samples in which the taxon was collected. Taxon Number % of Total a # of Samples % of Samples b Cnidaria 1 <0.01 1 1.02 Platyhelminthes 5 0.01 4 4.08 Mollusca Bivalvia 1 <0.01 1 1.02 Gastropoda Snails 347 0.48 39 39.80 Annelida Hirudinea 3 <0.01 2 2.04 Oligochaeta 18 0.03 9 9.18 Arthropoda Arachnida 1,181 1.65 66 67.35 Crustacea 40,399 56.28 90 91.84 Insecta 29,822 41.55 97 98.98 a Total number of organisms sampled = 71,777 b Total number of light trap samples = 98

Table 6. Number of organisms and frequency of occurrence (number of samples) of major invertebrate taxa caught in plankton tows at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. The % of total = % of total number of invertebrates collected in plankton tows. The % of samples = % of total number of plankton tows in which the taxon was collected.

Taxon Number % of Total a # of Samples % of Samples b Cnidaria 80 1.00 24 26.09 Platyhelminthes 2 0.03 2 2.17 Nematoda 8 0.10 7 7.61 Mollusca Bivalvia 3 0.04 2 2.17 Gastropoda Limpets 11 0.14 2 2.17 Snails 454 5.70 40 43.48 Annelida Hirudinea 1 0.01 1 1.09 Oligochaeta 374 4.70 54 58.70 Arthropoda Arachnida 116 1.46 50 54.35 Crustacea 3,133 39.35 83 90.22 Insecta 3,779 47.47 92 100.00 a Total number of organisms sampled = 7,961 b Total number of plankton samples = 92

46 captured. The percent frequency of snails in both light trap and plankton samples was similar. Large snails were observed floating in the water column at both transects, suggesting that their presence in plankton samples was not due to contamination by unintended vegetative debris. More large snails were captured in light traps than in plankton tows. Many snails in the plankton tows appeared to be newly hatched individuals.

Oligochaetes were the most common annelid captured in both light trap and plankton tows. Most of the 347 oligochaetes counted in plankton samples appeared to be reproductive buds, with relatively few large, whole worms collected. Frequency of occurrence was low (nine percent) in light trap samples, but was greater than 50% in plankton samples. Leeches were sparse, only occurring in two percent of light trap and one percent of plankton tows.

The most abundant phylum overall for both gear types was the Arthropoda, which accounted for 99.5 and 88.3% of all invertebrates collected in light trap and plankton samples, respectively. Three major Arthropod taxa were present in samples: Crustacea,

Insecta, and Arachnida. In light trap samples crustaceans were the most numerous, comprising 56.3% of the overall invertebrate and 56.6% of the overall catch of

Arthropoda. Insects ranked second, comprising 41.6% of the overall and 41.8% of the arthropod light trap catch. In plankton samples, by comparison, insects outnumbered crustaceans, making up 47.5 and 53.7% of the overall invertebrate and arthropod catches, respectively. Arachnida comprised less than two percent of overall invertebrates and

1.7% of all Arthropoda in both light trap and plankton samples. Not only did arthropods

47 account for the highest numbers, but overall they also had the highest frequency of occurrence. Insects were found in 99 and 100% of the light trap and plankton samples respectively.

In addition to these invertebrate taxa, algae and diatoms were regularly collected in plankton tow samples. With the exception of the readily identifiable Volvox , algae were not identified. Volvox colonies, like pre-settlement limpets, were only collected in plankton samples, probably because they are generally too small to be retained in the mesh collecting well of the light traps. In plankton samples, Volvox colonies were more numerous and had a higher frequency of occurrence than Cnidaria, Platyhelminthes and

Nematoda.

Overall numbers and frequency of occurrence of the arthropod taxa captured in light trap and plankton samples can be found in Tables 7 – 16. Arachnids were the least dominant of the captured arthropods, and were proportionally more numerous in light traps than in plankton samples (Tables 7, 8). Overall Hydrachnida were more numerous and occurred in more samples than either Oribatidea or Araneae. Hydrachnida composed

98.56% of the total Arachnida caught in light trap samples, but in plankton tows these mites accounted for only 27.6% of all Arachnida. Oribatid mites instead dominated the

Arachnid component of the plankton samples.

Four classes of crustaceans were present in invertebrate samples: Branchiopoda,

Copepoda, Ostracoda and Malacostraca. By far, the most dominant class in overall numbers was Branchiopoda. Two orders of Branchiopoda, Cladocera and Conchostraca, were found in invertebrate samples (Tables 7, 8). Conchostraca had the lowest frequency

Table 7. Number of organisms and frequency of occurrence (number of samples) of major Crustacean and Arachnid taxa caught in light traps at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. % of total = % of total number of Arachnida and % of total number of Crustacea collected in light traps. The % of samples = % of total number of light trap samples in which the taxon was collected.

Taxon Number % of Total a # of Samples % of Samples b Arachnida Hydrachnida 1,164 98.56 59 60.20 Oribatida 5 0.42 5 5.10 Araneae 12 1.02 12 12.24 Crustacea Amphipoda 175 0.43 37 37.76 Conchostraca 35 0.09 9 9.18 Cladocera 33,092 81.91 77 78.57 Copepoda 6,533 16.17 81 82.65 Ostracoda 564 1.40 48 48.98

a Total number of Arachnida sampled = 1181; total number of Crustacea sampled = 40,399 b Total number of light trap samples = 98

Table 8. Number of organisms and frequency of occurrence (number of samples) of major Crustacean and Arachnid taxa caught in plankton tows at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. The % of total = % of total number of Arachnida and % of total number of Crustacea collected in plankton tows. The % samples = % of total number of plankton tows in which the taxon was collected.

Taxon Number % of Total a # of Samples % of Samples b Arachnida Hydrachnida 32 27.59 19 20.65 Oribatida 51 43.97 30 32.61 Araneae 33 28.45 21 22.83 Crustacea Amphipoda 2 0.06 2 2.17 Conchostraca 6 0.19 1 1.09 Cladocera 1,750 55.86 60 65.22 Copepoda 903 28.82 60 65.22 Ostracoda 472 15.07 53 57.61

a Total number of Arachnida sampled = 116; total number of Crustacea sampled = 3,133 b Total number of plankton tow samples = 92

Table 9. Number of organisms and frequency of occurrence (number of samples) of major Insecta taxa caught in light traps at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. The % of total = % of total number of Insecta collected in light traps. The % of samples = % of total number of light traps in which the taxon was collected.

Taxon Number % of Total a # of Samples % of Samples b Insecta (misc) 1 <0.01 1 1.02 Collembola 4 0.01 3 3.06 Ephemeroptera 1,368 4.59 33 33.67 Odonata 264 0.89 19 19.39 Hemiptera 4,802 16.10 90 91.84 Hymenoptera 7 0.02 6 6.12 Trichoptera 28 0.09 15 15.31 Coleoptera 2,421 8.12 89 90.82 Diptera 20,927 70.17 80 81.63

a Total number of Insecta sampled = 29,822 b Total number of light trap samples = 98

Table 10. Number of organisms and frequency of occurrence (number of samples) of major Insecta taxa caught in plankton tows at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. The % of total = % of total number of Insecta collected in plankton tows. The % of samples = % of total number of plankton tows in which the taxon was collected.

Taxon Number % of Total a # of Samples % of Samples b Insecta (misc) 7 0.19 4 4.35 Diplura 2 0.05 2 2.17 Collembola 546 14.45 24 26.09 Ephemeroptera 69 1.83 18 19.57 Odonata 42 1.11 13 14.13 Hemiptera 362 9.58 47 51.09 Hymenoptera 53 1.40 17 18.48 Trichoptera 21 0.56 13 14.13 Lepidoptera 1 0.03 1 1.09 Coleoptera 129 3.41 41 44.57 Diptera 2,547 67.40 88 95.65

a Total number of Insecta sampled = 3,779 b Total number of plankton tow samples = 92

Table 11. Number of organisms and frequency of occurrence (number of samples) of selected Insecta life history stages caught in light traps at two sampling transects Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. The % of total = % of total number of Insecta collected in light traps. The % of samples = % of total number of light traps in which the taxon was collected.

Taxon Stage Number % of Total a # of Samples % of Samples b Ephemeroptera adult 0 0.00 0 0.00 nymph 1,368 4.59 33 33.67 Anisoptera adult 0 0.00 0 0.00 nymph 47 0.16 10 10.20 Zygoptera adult 0 0.00 0 0.00 nymph 217 0.73 18 18.37 Trichoptera adult 0 0.00 0 0.00 pupae 20 0.07 10 10.20 larvae 8 0.03 5 5.10 Coleoptera adult 2,182 7.32 88 89.80 larvae 239 0.80 27 27.55 Hemiptera adult 3,551 11.91 90 91.84 nymph 1,246 4.18 45 45.92

a Total number of Insecta sampled = 29,822 b Total number of light trap samples = 98

Table 12. Number of organisms and frequency of occurrence (number of samples) of selected Insecta life history stages caught in plankton tows at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. The % of total = % of total number of Insecta collected in plankton tows. The % of samples = % of total number of plankton tows in which the taxon was collected.

Taxon Stage Number % of Total a # of Samples % of Samples b Ephemeroptera adult 0 0.00 0 0.00 nymph 69 1.83 18 19.57 Anisoptera adult 0 0.00 0 0.00 nymph 2 <0.01 2 2.17 Zygoptera adult 0 0.00 0 0.00 nymph 40 1.06 11 11.96 Trichoptera adult 1 0.03 1 1.09 pupae 0 0.00 0 0.00 larvae 19 0.50 11 11.96 Coleoptera adult 90 2.38 36 39.13 larvae 38 1.01 14 15.22 Hemiptera adult 168 4.45 14 15.22 nymph 130 3.44 25 27.17

a Total number of Insecta sampled = 3,779 b Total number of plankton tow samples = 92

Table 13. Number of organisms and frequency of occurrence (number of samples) of selected Diptera life history stages caught in light traps at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. The % of total = % of total number of Insecta collected in light traps. The % of samples = % of total number of light traps in which the taxon was collected.

Taxon Stage Number % of Total a # of Samples % of Samples b Diptera (misc) adult 44 0.15 28 28.57 Cecidomyidae adult 1 <0.01 1 1.02 Diptera (misc) pupae 68 0.23 21 21.43 Ceratopogonidae larvae 7 0.02 5 5.10 Chaoboridae larvae 31 0.10 8 8.16 Chironomidae larvae 20,731 69.52 74 75.51 Culicidae larvae 19 0.06 7 7.14 Ephydridae larvae 1 <0.01 1 1.02 Simuliidae larvae 25 0.08 5 5.10

a Total number of Insecta sampled = 29,822 b Total number of light trap samples = 98

Table 14. Number of organisms and frequency of occurrence (number of samples) of selected Diptera life history stages caught in plankton tows at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. The % of total = % of total number of Insecta collected in plankton tows. The % of samples = % of total number of plankton tows in which the taxon was collected.

Taxon Stage Number % of Total a # of Samples % of Samples b Diptera (misc) adult 191 5.05 44 47.83 Cecidomyidae adult 39 1.03 11 11.96 Diptera (misc) pupae 36 0.95 22 23.91 Diptera (misc) larvae 1 0.03 1 1.09 Ceratopogonidae larvae 8 0.21 6 6.52 Chironomidae larvae 2,097 55.49 83 90.22 Culicidae larvae 65 1.72 22 23.91 Muscidae larvae 1 0.03 1 1.09 Ephydridae larvae 2 0.05 2 2.17 Sciomyzidae larvae 4 0.11 4 4.35 Simuliidae larvae 95 2.51 13 14.13 Tipulidae larvae 2 0.05 2 2.17

a Total number of Insecta sampled = 3,779 b Total number of plankton tow samples = 92

Table 15. Number of organisms and frequency of occurrence (number of samples) of Hemiptera caught in light traps at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. The % of total = % of total number of Insecta collected in light traps. The % of samples = % of total number of light traps in which the taxon was collected.

Taxon Number % of Total a # of Samples % of Samples b Homoptera (misc) 1 <0.01 1 1.02

Aphidoidea 6 0.02 4 4.08

Cicadellidae 1 <0.01 1 1.02

Corixidae 4,442 14.90 89 90.82

Delphacidae 4 0.01 4 4.08

Nepidae 8 0.03 7 7.14

Notonectidae 339 1.14 32 32.65

Belostomatidae 1 <0.01 1 1.02

a Total number of Insecta sampled = 29,822 b Total number of light trap samples = 98

Table 16. Number of organisms and frequency of occurrence (number of samples) of Hemiptera caught in plankton tows at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. The % of total = % of total number of Insecta collected in plankton tows. The % of samples = % of total number of plankton tows in which the taxon was collected.

Taxon Number % of Total a # of Samples % of Samples b Hemiptera (misc) 9 0.24 6 6.52

Homoptera (misc) 3 0.08 3 3.26

Aphidoidea 206 5.42 30 32.61

Cicadellidae 8 0.21 6 6.52

Corixidae 25 0.66 12 13.04

Delphacidae 3 0.08 3 3.26

Gerridae 104 0.24 14 15.22

Notonectidae 4 0.11 3 3.26

a Total number of Insecta sampled = 3,779 b Total number of plankton tow samples = 92

57 58 of occurrence of all Crustacean taxa, while that of Cladocera was among the highest, equaling and almost equaling that of Copepoda in plankton and light traps respectively.

Cladocera were the most numerically dominant taxa overall, and accounted for 43.7% of all invertebrates captured by both gears. Copepoda and Ostracoda were the second and third most numerous Crustacean taxa. The only Malacostraca taxa found in invertebrate samples were amphipods. Amphipods were not encountered in large numbers or in a significant proportion of plankton samples. They were, however, found in 37.8% of light trap samples.

The most diverse of the identified taxa were the insects, with a total of ten insect orders captured in plankton and light trap samples (Table 4). Summaries of the number and frequency of occurrence of insect orders in light trap and plankton samples can be found in Tables 9 and 10. Diptera were by far the most numerous, accounting for 29 and

32% of all individual invertebrates captured by the two sampling gears in lower Fourmile

Creek. Hemiptera, the next most numerous insect order in light samples, had the highest frequency of occurrence. Trichoptera were not caught frequently by either light traps or plankton nets. However, they were regularly observed in trap nets. Diversity of insect orders was greater in plankton tows than in light traps.

A breakdown of number of individuals of each insect order by life history stage is presented in Tables 11 – 16. Excluding Diptera, light samples contained a larger proportion of adult than larval insects (Table 11). Plankton tows contained similar numbers of adults and immature stages, as can be seen in Table 12. Overall, 10,081 non- dipteran individuals were captured by both gear types. Over 59 percent of these

59 individuals were adults. Hemiptera and Coleoptera tended to be adults. No adult

Ephemeroptera or Odonata were captured. Chironomid larvae were by far the most numerous and frequently encountered dipteran taxon in both light and plankton samples

(Tables 13, 14). Few adult Diptera were captured. Of the identified Hemiptera,

Corixidae (water boatmen) and Notonectidae (backswimmers) dominated light trap samples. Aphidoidea (aphids) and Gerridae (water striders) dominated plankton samples

(Tables 15, 16). Larger Nepidae and Belostomatidae were relatively rare.

Overall CPUE of major invertebrate taxa, at each transect, is summarized in

Tables 17 and 18. CPUE for non-arthropods was generally low in both light trap and plankton samples. The highest overall CPUE of major invertebrate taxa caught in both light traps and plankton samples occurred at the Westside transect. Of the major taxa captured in light traps, crustaceans yielded the maximum overall CPUE, followed by insects. Abundances of these two major taxa were nearly equal in plankton samples.

Within light trap samples, only Cnidarian and Arachnida were more abundant at the

Fourmile transect than at the Westside transect.

There were marked differences in overall abundances of specific arachnid and crustacean taxa in plankton and light samples at the Fourmile and Westside transects

(Tables 19, 20). Hydrachnida were by far the most abundant arachnid taxa overall at both transects in light traps. CPUEs for each of the arachnid taxa captured in plankton samples were similar at both transects.

Overall abundances of specific crustacean taxa varied widely. Within the major crustacean taxa, Cladocera and Copepoda had the highest CPUE by both gears. In fact,

Table 17. Mean CPUE for major invertebrate taxa caught in light traps at two sampling transects, Fourmile (FM) and Westside (WS), in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each location, mean CPUE (number of organisms sampled per 12 hours) = [(total number of organisms sampled / total (hours darkness + 2)) x 12].

Taxon FM WS Cnidaria 0.02 0.00 Platyhelminthes 0.00 0.15 Mollusca Bivalvia 0.00 0.03 Gastropoda Snails 1.40 7.25 Annelida Hirudinea 0.02 0.06 Oligochaeta 0.00 0.11 Arthropoda Arachnida 16.03 5.81 Crustacea 122.43 912.58 Insecta 88.24 677.22

Table 18. Mean CPUE for major invertebrate taxa caught in plankton tows at two sampling transects, Fourmile (FM) and Westside (WS) in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each location, mean CPUE (number of organisms sampled per m 3) = (total number of organisms sampled / total volume sampled)] .

Taxon FM WS Cnidaria 0.88 0.25 Platyhelminthes 0.06 0.05 Nematoda 0.00 0.08 Mollusca Bivalvia 0.04 0.00 Gastropoda Limpets 0.12 0.03 Snails 3.30 5.16 Annelida Hirudinea 0.01 0.00 Oligochaeta 3.36 2.83 Arthropoda Arachnida 0.98 1.02 Crustacea 23.37 34.33 Insecta 30.93 35.35

Table 19. Mean CPUE for major Crustacean and Arachnid taxa caught in light traps at two sampling transects, Fourmile (FM) and Westside (WS), in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each location, mean CPUE (number of organisms sampled per 12 hours) = [(total number of organisms sampled / total (hours darkness + 2)) x 12].

Taxon FM WS Arachnida

Hydrachnida 15.86 5.62

Oribatida 0.05 0.06

Araneae 0.12 0.14

Crustacea

Amphipoda 2.13 1.27

Conchostraca 0.00 0.97

Cladocera 55.99 821.77

Copepoda 61.27 78.05

Ostracoda 3.04 10.51

Table 20. Mean CPUE for major Crustacean and Arachnid taxa caught in plankton tows at two sampling transects, Fourmile (FM) and Westside (WS) in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each location, mean CPUE (number of organisms sampled per m3) = (total number of organisms sampled / total volume sampled)].

Taxon FM WS Arachnida

Hydrachnida 0.22 0.38

Oribatida 0.37 0.58

Araneae 0.38 0.05

Crustacea

Amphipoda 0.02 0.00

Conchostraca 0.00 0.16

Cladocera 12.17 21.13

Copepoda 6.83 9.69

Ostracoda 4.35 3.35

64 the CPUE of Cladocera at the Westside transect was the highest of any major invertebrate taxon collected in lower Fourmile Creek. Ostracoda were the third most abundant crustacean taxa. Amphipods and Conchostraca were not abundant in either light or plankton samples.

Overall CPUE of major Insecta orders and other selected insect taxa at the

Fourmile and Westside transects are summarized in Tables 21 – 26. Overall CPUEs of insect orders were generally higher at the Westside transect, with differences most marked in Westside light trap samples. Diptera were the most abundant insect order at the two transects in both light traps and plankton tows. Hemiptera, for the most part, had the next highest CPUE. The CPUE of Collembola (springtails) surpassed that of

Hemiptera only in the plankton samples from the Westside transect. Coleoptera, followed by Ephemeroptera, were the third and fourth most abundant insect orders in light traps.

At both transects Corixidae (water boatmen) were the dominant hemipteran taxon sampled in light traps (Tables 23, 24); this was especially true at the Westside transect.

Notonectidae were the second most frequently captured hemipteran in light traps.

Plankton samples displayed different proportions of hemipteran taxa, with aphids dominating the hemipteran catch at the Fourmile transect. CPUEs of gerrids (water striders) and aphids were nearly equal at the Westside transect.

Diptera possessed the highest overall CPUE of any insect order. Chironomid larvae had by far the highest CPUE of any dipteran taxon at all transects and in both gear types. In light traps, larval chironomid CPUE was more than an order of magnitude

Table 21. Mean CPUE for orders of Insecta caught in light traps at two sampling transects, Fourmile (FM) and Westside (WS), in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each location, mean CPUE (number of organisms sampled per 12 hours) = [(total number of organisms sampled / total (hours darkness + 2)) x 12].

Taxon FM WS Collembola 0.05 0.03

Ephemeroptera 0.97 36.22

Odonata 0.23 6.92

Hemiptera 35.59 73.21

Hymenoptera 0.05 0.11

Trichoptera 0.25 0.36

Coleoptera 9.38 51.27

Diptera 41.73 509.08

Table 22. Mean CPUE for orders of Insecta caught in plankton tows at two sampling transects, Fourmile (FM) and Westside (WS) in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each location, mean CPUE (number of organisms sampled per m3) = (total number of organisms sampled / total volume sampled)].

Taxon FM WS Insecta (misc) 0.05 0.08

Diplura 0.01 0.03

Collembola 2.16 10.21

Ephemeroptera 0.12 1.62

Odonata 0.14 0.85

Hemiptera 3.39 2.44

Hymenoptera 0.63 0.05

Trichoptera 0.22 0.08

Lepidoptera 0.01 0.00

Coleoptera 0.89 1.56

Diptera 23.29 18.42

Table 23. Mean CPUE for Hemiptera caught in light traps at two sampling transects, Fourmile (FM) and Westside (WS), in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each location, mean CPUE (number of organisms sampled per 12 hours) = [(total number of organisms sampled / total (hours darkness + 2)) x 12].

Taxon FM WS Homoptera (misc) 0.00 0.03

Aphidoidea 0.07 0.06

Cicadellidae 0.00 0.03

Corixidae 34.80 64.58

Delphacidae 0.05 0.03

Nepidae 0.12 0.03

Notonectidae 0.56 8.44

Belostomatidae 0.00 0.03

Table 24. Mean CPUE for major Hemiptera caught in plankton tows at two sampling transects, Fourmile (FM) and Westside (WS), in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each location, mean CPUE (number of organisms sampled per m3) = (total number of organisms sampled / total volume sampled)].

Taxon FM WS Hemiptera (misc) 0.07 0.08

Homoptera (misc) 0.01 0.05

Aphidoidea 2.22 0.74

Cicadellidae 0.01 0.19

Corixidae 0.07 0.52

Delphacidae 0.04 0.00

Gerridae 0.94 0.77

Notonectidae 0.01 0.08

Table 25. Mean CPUE for Diptera caught in light traps at two sampling transects, Fourmile (FM) and Westside (WS), in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each location, mean CPUE (number of organisms sampled per 12 hours) = [(total number of organisms sampled / total (hours darkness + 2)) x 12].

Taxon Stage FM WS Diptera (misc) adult 0.54 0.33 Cecidomyidae adult 0.02 0.00 Diptera (misc) pupae 0.40 1.22 Ceratopogonidae larvae 0.02 0.17 Chaoboridae larvae 0.07 0.75 Chironomidae larvae 40.64 505.48 Culicidae larvae 0.03 0.47 Ephydridae larvae 0.02 0.00 Simuliidae larvae 0.00 0.69

Table 26. Mean CPUE for Diptera caught in plankton tows at two sampling transects, Fourmile (FM) and Westside (WS) in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each location, mean CPUE (number of organisms sampled per m3) = (total number of organisms sampled / total volume sampled)].

Taxon Stage FM WS Diptera (misc) adult 2.11 0.58 Cecidomyidae adult 0.42 0.14 Diptera (misc) pupae 0.27 0.38 Ceratopogonidae larvae 0.09 0.03 Chironomidae larvae 19.52 14.41 Culicidae larvae 0.62 0.41 Diptera (misc) larvae 0.00 0.03 Muscidae larvae 0.01 0.00 Ephydridae larvae 0.02 0.00 Sciomyzidae larvae 0.04 0.03 Simuliidae larvae 0.12 2.33 Tipulidae larvae 0.02 0.00

71 greater at Westside than at Fourmile (Table 25). The abundance of larval chironomids was similar in plankton tows at both transects (Table 26). Other Diptera had relatively low abundances in both samples. Adult and pupal dipterans were not identified to family.

CPUE for these two life history stages was higher at the Fourmile transect for both gear types. The only larval non-chironomid dipteran taxon with a CPUE greater than one was the Simuliidae, or black flies, and these occurred primarily at the Westside transect.

Mean monthly abundances of invertebrate taxa sampled in light traps and plankton tows were higher in 2005 than in 2006 (Figures 14 – 18, Appendices C – H).

Seasonal trends for many invertebrate taxa were present. Snails and Oligochaeta increased in abundance during the late summer (Figures 14, 15). Arachnida abundance

(Figure 16) was largely dominated by Hydrachnida (see Appendix C). The monthly trend in water mite CPUE was similar in both light and plankton samples, remaining low during April through May and increasing in subsequent months.

Crustacean CPUE in light traps was considerably higher in June 2005 and May

2006, when levels greater than 1,000 individuals per 12 hour period were encountered

(Figure 17). CPUE of Crustaceans was drastically lower in plankton tows than in light traps during all months. Peaks in Crustacean abundance occurred during late spring and early fall. As seen in the overall CPUE, Cladocera, Copepoda, and Ostracoda dominated the monthly abundance of Crustacea (Appendices D – F).

Monthly combined CPUE of all insects is presented in Figure 18. Insect abundance was low during March – May in both light trap and plankton samples, but increased in June. The highest light trap monthly CPUE for insects was 6,009 individuals

40 Light Trap

10 mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Plankton Tow + 30

25 +

20 + + 15 + 10

5 mean CPUEmean (number/m*3) + + + + 0 + + + + + +

MAMJJASOMAMJJAS 2005 2006

Figure 14. Overall mean monthly CPUE for snails sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

6 Light Trap

1 mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Plankton Tow + 25 +

15 + 10

+ 5 + + mean CPUEmean (number/m*3) + + + + + 0 + + + +

MAMJJASOMAMJJAS 2005 2006

Figure 15. Overall mean monthly CPUE for Oligochaeta sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

Light Trap 100

20 mean CPUEhr) mean (number/12

MAMJJASOMAMJJAS 2005 2006

+ Plankton Tow 4 + +

3 + + 2 +

1 + + + + + mean CPUEmean (number/m*3) + + + 0 +

MAMJJASOMAMJJAS 2005 2006

Figure 16. Overall mean monthly CPUE for Arachnida sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

8000 Light Trap

6000

4000

2000 mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Plankton Tow +

150

+ + + 100 +

50 + mean CPUEmean (number/m*3) + + + + + 0 + + + +

MAMJJASOMAMJJAS 2005 2006

Figure 17. Overall mean monthly CPUE for Crustacea sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

6000 Light Trap

5000

4000

3000

2000

1000 mean CPUEhr) mean (number/12

MAMJJASOMAMJJAS 2005 2006

200 + Plankton Tow

150 + + + 100

50 + + +

mean CPUEmean (number/m*3) + + + + + + 0 +

MAMJJASOMAMJJAS 2005 2006

Figure 18. Overall mean monthly CPUE for Insecta sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

77 per 12 hour period, which occurred in June 2005. Within the insects, CPUEs for most individual taxa were also higher during this month (Appendices G – R). Collembola were predominantly captured during spring, when surface water was more available

(Appendix G). Ephemeroptera (Baetidae nymphs) were more abundant June – August

2005 and April – June 2006 (Appendix H).

Together Hemiptera, Coleoptera and Diptera comprised the largest component of monthly insect CPUE values (Appendices I – R). Each of these three orders was disproportionally more abundant in light trap samples taken in June 2005. Corixidae were the most abundant hemipteran family in monthly samples, but had relatively low

CPUE values from March through May. After June, abundances generally increased.

Corixid nymphs were more abundant than adults in light trap samples during all months except June, July and October of 2005 and June of 2006. Corixid adults were more abundant than Corixidae nymphs in plankton samples. Aphids and water striders tended to be more numerous in plankton tows than in light traps, when present at all in monthly samples. Abundances of both aphids and water striders increased in the summer and fall months, during warmer, lower water conditions. Monthly CPUE for beetles was higher in light traps than in plankton tows. The abundance of Coleoptera increased during mid to late summer in both years. Beetles tended to be less abundant during March.

Dytiscidae and Hydrophilidae beetles were the two most abundant Coleoptera families in monthly samples. Their CPUEs in both gear types followed similar monthly patterns.

Diptera were the most abundant insect order in monthly samples. Monthly CPUEs for all

Diptera tended to be lowest during the period of March through May. Chironomidae

78 larvae dominated monthly Diptera abundances. Diptera pupae and adults, which were not identified to family and were combined for analysis, peaked during July and August.

Monthly site-specific CPUE of selected invertebrate taxa were complex and did not always follow the same seasonal patterns during 2005 and 2006. In addition, taxa were not consistently abundant at specific sites. Site-specific CPUE values for each major taxa and important specific taxa captured in light traps and plankton tows are presented in Appendices S through AZ.

Benthic cores were taken at the Fourmile transect March – October in both 2005 and 2006. At the Westside transect, benthic cores were taken April – August 2005 and

March – July 2006. Benthic samples originating in the Fourmile transect tended to consist of a layer of clay covered by a 1 to 3cm layer of organic and inorganic material.

The clay was hard, extremely dense and typically devoid of invertebrates. Organisms were usually found in the upper detritus layer. Benthic cores taken at the Westside transect were comprised primarily of gravel, soil and dense roots. Cores from the

Westside lower site consisted primarily of gravel, while those from the upper site included a greater proportion of soil and roots.

A summary of overall numbers and frequency of occurrence of benthic invertebrates is presented in Table 27. These samples yielded fewer invertebrates overall than either the plankton or light samples. Notably, these samples were dominated by oligochaetes, insects and bivalves which comprised 65.3%, 17.8% and 9.46% of the total invertebrates in benthic samples, respectively. Frequency of occurrence of each of these three taxa was 91%, 90% and 50%.

Table 27. Number of organisms and frequency of occurrence (number of samples) of major invertebrate taxa collected in benthic samples at two sampling transects, Fourmile (FM) and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – October 2006. The % of total = % of total number of invertebrates collected in benthic samples. The % of samples = % of total number of benthic samples in which the taxon was collected.

TAXON Number % of Total a # of Samples % of Samples b Cnidaria 0 0.00 0 0.00 Platyhelminthes 4 0.11 3 2.97 Nematoda 47 1.36 26 25.74 Mollusca Bivalvia 337 9.46 50 50.00 Gastropoda Snails 117 3.28 37 37.00 Annelida Hirudinea 0 0.00 0 0.00 Oligochaeta 2,327 65.33 91 91.00 Arthropoda Arachnida 10 0.28 10 10.00 Crustacea 86 2.41 39 39.00 Insecta 634 17.80 90 90.00 a Total number of organisms sampled = 3,562 b Total number of benthic samples = 100

Crustacea and Arachnida were not captured in large numbers in benthic samples

(Table 27, Appendix BA). However, insects were common, and included 11 orders, including Diplura and Collembola (Appendix BB). Diptera, predominantly chironomid larvae, accounted for 87.5% of all insects and were found in 85% of samples. Other insect orders were low in both overall numbers and in frequency of occurrence.

Fish Abundance, Condition, Reproduction and Diet

A total of 20,210 fish, from eight families and 14 species, were captured in lower

Fourmile Creek (Table 28). Monthly totals of each species captured in trap nets at each

transect during 2005 and 2006 are in Appendix BC. Speckled dace, Rhinichthys osculus ,

and fathead minnow, Pimephales promelas , were the two most numerous species,

accounting for 87% of all fish captured in trap nets. Yellow perch, Perca flavescens ,

represented the third most abundant species overall. Native fish comprised 63% of the

total fish sampled (Table 29). The dominance of native fish was primarily due to the

abundant speckled dace.

Native fish dominated the overall trap net catches at both the Fourmile and

Westside transects. At the Fourmile transect eight families and 14 species of fish were

captured (Table 30). The total number of native fish was greater than non-native fish.

Speckled dace and slender sculpin, Cottus tenuis , together accounted for 95% of native

fish captured and 60% percent of the overall Fourmile catch. Fathead minnow and

Table 28. Total numbers of fish taken in trap nets at two transects, Fourmile (FM) and Westside (WS), in Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

Family Species Common Name Number Petromyzontidae Lampetra (ammocoete) * 1

Cyprinidae Gila bicolor tui chub 152 Gila coerulea blue chub 156 Pimephales promelas fathead minnow 5,996 Rhinichthys osculus speckled dace 11,548 17,854

Catostomidae Catostomidae (juvenile) ** 1

Ictaluridae Ameiurus nebulosus brown bullhead 237

Salmonidae Oncorhynchus mykiss rainbow (red band) trout 7 Oncorhynchus nerka kokanee 21 Salmo trutta brown trout 5 Salvelinus fontinalis brook trout 1 34

Cottidae Cottus klamathensis marbled sculpin 56 Cottus princeps Klamath Lake sculpin 163 Cottus tenuis slender sculpin 610 829

Centrarchidae Lepomis gibbosus pumpkinseed 17

Percidae Perca flavescens yellow perch 1,239

Total 20,210

* Ammocoete not identified to species. ** Juvenile Catostomidae not identified to species.

Table 29. Total numbers of native and non-native fish taken in trap nets at two transects, Fourmile (FM) and Westside (WS), in Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

Fourmile Westside Total # %

Non-native 6,847 669 7,516 37.19%

Native * 11,584 1,110 12,694 62.81%

Total # ** 18,431 1,779 20,210 100.00%

* One ammocoete and one juvenile Catostomidae included in Native fish grouping.

Table 30. Total numbers of native and non-native fish taken in trap nets at the Fourmile (FM) sampling transect of Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

Origin Species Number Non-native Pimephales promelas 5,644 Ameiurus nebulosus 116 Oncorhynchus nerka 19 Salmo trutta 4 Salvelinus fontinalis 1 Lepomis gibbosus 15 Perca flavescens 1,048 6,847

Native Lampetra (ammocoete) * 1 Gila bicolor 149 Gila coerulea 152 Rhinichthys osculus 10,501 Catostomidae (juvenile) ** 1 Oncorhynchus mykiss 6 Cottus klamathensis 56 Cottus princeps 159 Cottus tenuis 559 11,584

Total 18,431

* Ammocoete not identified to species. ** Juvenile Catostomidae not identified to species.

84 yellow perch made up 97% of the non-native fish and 36% of the total fish caught at this transect.

In addition to slender sculpin, Klamath lake sculpin, Cottus princeps , and marbled sculpin, Cottus klamathensis , were captured at the Fourmile transect. Overall, salmonids were relatively rare. The most abundant salmonids were sockeye salmon or kokanee,

Oncorhynchus nerka , followed by rainbow trout. Most of the captured salmonids were juveniles, and all were captured in June, July and August, when water level was falling.

Six families and 12 species of fish were recorded from the Westside transect

(Table 31). As in the Fourmile transect, speckled dace and slender sculpin dominated the native fish catch, accounting for 99% of native fish and 62% of the overall Westside trap net catch. Fathead minnow and yellow perch accounted for 81% of the non-native fish and 38% of the total fish catch at this transect. Six native and six non-native fish species were captured in trap nets at the Westside transect. No Catostomidae, Lampetra ammocoetes, marbled sculpin or brook trout were captured at the Westside transect.

Trap nets were fished for a total of 858.1 hours during the course of the study.

Overall mean CPUEs for all captured species are shown in Table 32. Speckled dace, fathead minnow and yellow perch had the highest overall CPUE values. Slender sculpin were encountered more frequently, but in lower numbers, than yellow perch and thus rank lower in overall CPUE.

Overall monthly CPUEs of both native and non-native fish captured in trap nets over the two sampling years are shown in Figure 19. CPUE of both native and non- native fish was highest during August – October of 2005 and July – September of 2006.

Table 31. Total numbers of native and non-native fish taken in trap nets at the Westside (WS) sampling transect of Fourmile Creek, Upper Klamath Lake, Oregon, April – July 2005 and March – July 2006.

Origin Species Number Non-native Pimephales promelas 352 Ameiurus nebulosus 121 Oncorhynchus nerka 2 Salmo trutta 1 Salvelinus fontinalis 0 Lepomis gibbosus 2 Perca flavescens 191 669

Native Lampetra (ammocoete) * 0 Gila bicolor 3 Gila coerulea 4 Rhinichthys osculus 1,047 Catostomidae (juvenile) ** 0 Oncorhynchus mykiss 1 Cottus klamathensis 0 Cottus princeps 4 Cottus tenuis 51 1,110

Total 1,779

* Ammocoete not identified to species. ** Juvenile Catostomidae not identified to species.

Table 32. Overall Mean CPUE values for each fish species collected at two transects, Fourmile (FM) and Westside (WS), in Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

Species Samples Mean CPUE Rhinichthys osculus 48 215.144 Pimephales promelas 48 111.708 Perca flavescens 48 23.083 Cottus tenuis 48 11.365 Ameiurus nebulosus 48 4.415 Cottus princeps 48 3.037 Gila coerulea 48 2.906 Gila bicolor 48 2.832 Cottus klamathensis 48 1.043 Oncorhynchus nerka 48 0.391 Lepomis gibbosus 48 0.317 Oncorhynchus mykiss 48 0.130 Salmo trutta 48 0.093 Catostomidae (juvenile) 48 0.019 Lampetra (ammocoete) 48 0.019 Salvelinus fontinalis 48 0.019

1200 Introduced Native 1000

800

600 MEANCPUE 400

200

0 July July May May April April June June March March August August October January February November December September 2005 2006 September MONTH

Figure 19. Mean monthly CPUE of introduced and native fish captured in trap nets at two transects in Fourmile (FM) and Westside (WS), in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

Non-native fish were caught at lower rates than were native fish over much of the year.

In trap net samples, introduced fish were more abundant than native fish only during

September and October in 2005 and September in 2006.

The overall CPUE of each fish species at the Fourmile and Westside transects is presented in Tables 33 and 34 respectively. At both the Fourmile and Westside transects the same three fish species were most abundant: speckled dace, fathead minnow and yellow perch. At the Fourmile transect, CPUE for speckled dace was highest, followed by fathead minnow, yellow perch and slender sculpin. The CPUEs of the most abundant fish at the Westside transect followed a similar pattern, except that the CPUE for brown bullhead was higher than that of slender sculpin.

Calculation of site-specific mean CPUE for the five overall most abundant species at the Fourmile lower and upper sites shows that the relative abundances are similar between sites (Figure 20). The abundance of slender sculpin was roughly equal at both sites. Speckled dace and yellow perch were more abundant at the upper site, while fathead minnow and brown bullhead were more abundant at the lower site.

Speckled dace dominated the overall catch at all Westside sites (Figure 21). The relatively high abundance of brown bullhead and yellow perch can be attributed to large catches in July 2006. In 2005, only two brown bullhead and no yellow perch were captured at the Westside transect. Conversely, in a single 2006 July trap net set in the lower site, 114 brown bullhead and 187 yellow perch were captured.

Overall mean CPUE for fish captured in trap nets during months of concurrent sampling at the Fourmile and Westside transects (April – July of both 2005 and 2006) is

Table 33. Overall Mean CPUE values for each fish species collected in trap nets at the Fourmile transect (FM) in Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

Species Samples Mean CPUE Rhinichthys osculus 30 308.649 Pimephales promelas 30 165.890 Perca flavescens 30 30.803 Cottus tenuis 30 16.430 Cottus princeps 30 4.673 Gila coerulea 30 4.468 Gila bicolor 30 4.379 Ameiurus nebulosus 30 3.410 Cottus klamathensis 30 1.646 Lepomis gibbosus 30 0.441 Oncorhynchus nerka 30 0.558 Oncorhynchus mykiss 30 0.176 Salmo trutta 30 0.118 Catostomidae (juvenile) 30 0.029 Lampetra (ammocoete) 30 0.029 Salvelinus fontinalis 30 0.029

Table 34. Overall Mean CPUE values for each fish species collected in trap nets at the Westside transect (WS) in Fourmile Creek, Upper Klamath Lake, Oregon, April – July 2005 and March – July 2006.

Species Samples Mean CPUE Rhinichthys osculus 18 53.274 Pimephales promelas 18 17.911 Perca flavescens 18 9.719 Ameiurus nebulosus 18 6.157 Cottus tenuis 18 2.595 Cottus princeps 18 0.204 Gila coerulea 18 0.204 Gila bicolor 18 0.153 Lepomis gibbosus 18 0.102 Oncorhynchus nerka 18 0.102 Oncorhynchus mykiss 18 0.051 Salmo trutta 18 0.051 Catostomidae (juvenile) 18 0.000 Cottus klamathensis 18 0.000 Lampetra (ammocoete) 18 0.000 Salvelinus fontinalis 18 0.000

Ameiurus nebulosus Pimephales promelas Cottus tenuis Rhinichthys osculus Perca flavescens

300

250

200 MEANCPUE 150

100

0 LW UP SITE

Figure 20. Mean site-specific CPUE for the five overall most abundant fish at the lower (LW) and upper (UP) sites of the Fourmile (FM) transect, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

Ameiurus nebulosus Pimephales promelas Cottus tenuis Rhinichthys osculus Perca flavescens

40 MEANCPUE

0 LW UP PS SITE

Figure 21. Mean site-specific CPUE for the five overall most abundant fish at the lower (LW), upper (UP) and pasture (PS) sites at the Westside (WS) transect, Fourmile Creek, Upper Klamath Lake, Oregon, April – July 2005 and March – July 2006.

93 presented in Table 35. Again, speckled dace was by far the most abundant fish species.

Fathead minnow and yellow perch were the two next most abundant species and were captured at similar rates during months of concurrent sampling.

Transect-specific overall and annual mean CPUEs of the eight most abundant fish in trap nets during the months of concurrent trap-net sampling are given in Table 36.

Values for fish not included in the table were small, due largely to single occurrences in trap net samples. During April – July of both 2005 and 2006, the overall CPUEs for all but one species were higher at the Fourmile transect than at the Westside transect.

CPUEs for all eight species, except blue chub and tui chub at the Fourmile transect and

Klamath Lake sculpin at the Westside transect, were highest in 2006.

Patterns of monthly fish diversity (Shannon index (H)) and richness (S) differed between the Fourmile and Westside transects (Figure 22). At the Fourmile transect both species diversity and evenness peaked in May of 2005 and June – September of 2006.

Fourmile fish diversity was lowest in July of both years, and subsequently increased.

Species evenness (Pielou’s index (J)) peaked at 0.9 in May 2005. In 2006, evenness remained around 0.7 during March – June. It then dropped to 0.3 in July when speckled dace made up 80% of the Fourmile catch. The greatest number of species was captured in trap nets set in August of 2005 and June – September of 2006. Species richness was generally higher during mid summer and fall than during spring. Species diversity of fish captured in trap nets at the Westside transect was lowest in April 2005 and March 2006, when only speckled dace were captured. Species diversity subsequently increased to approximately one after May 2005 and April 2006. Unlike Fourmile transect samples,

Table 35. Overall mean CPUE values of all fish species taken in trap nets at the Fourmile (FM) and Westside (WS) transects in Fourmile Creek, Upper Klamath Lake, Oregon, during April – July 2005 and April – July 2006. These are the months during which both transects were sampled in both the 2005 and 2006 sampling seasons.

Species Samples Mean CPUE Rhinichthys osculus 32 148.15 Pimephales promelas 32 30.07 Perca flavescens 32 20.39 Cottus tenuis 32 8.52 Ameiurus nebulosus 32 3.61 Gila coerulea 32 3.31 Gila bicolor 32 2.89 Cottus princeps 32 1.65 Oncorhynchus nerka 32 0.36 Cottus klamathensis 32 0.14 Lepomis gibbosus 32 0.11 Oncorhynchus mykiss 32 0.06 Catostomidae (juvenile) 32 0.03 Salmo trutta 32 0.03 Salvelinus fontinalis 32 0.03 Lampetra (ammocoete) 32 0.00

Table 36. Transect specific overall and annual mean CPUE values of selected fish at the Fourmile (FM) and Westside (WS) transects, in Fourmile Creek, Upper Klamath Lake, Oregon, April – July 2005 and April – July 2006. These are the months during which both transects were sampled in both the 2005 and 2006 sampling seasons.

CPUE for April through July Species FM WS Overall 2005 2006 Overall 2005 2006 Rhinichthys osculus 231.8 135.5 328.5 58.1 15.7 104.6 Pimephales promelas 39.3 17.0 61.7 20.2 15.1 25.7 Perca flavescens 29.2 0.2 58.3 10.9 0.0 23.0 Cottus tenuis 13.7 9.8 17.7 2.9 3.0 2.9 Ameiurus nebulosus 0.5 0.1 1.0 6.9 0.2 14.3 Gila coerulea 6.2 6.4 6.0 0.2 0.1 0.4 Gila bicolor 5.4 7.3 3.5 0.2 0.0 0.4 Cottus princeps 3.0 2.8 3.2 0.2 0.4 0.0

3.0 13 Fourmile 12 2.5 11 10 2.0 9 8 7 1.5 6 5 1.0 4 3 0.5 2 1 0.0 0 3.0 13 Westside 12 2.5 11 10 2.0 9 SPECIESDIVERSITY (H) NUMBERSPECIES OF (S)

SPECIESEVENNESS 1) - (0 8 7 1.5 6 5 1.0 4 3 0.5 2 1 0.0 0 July July May May April April June June March March August August October January February November December September September 2005 2006 MONTH Figure 22. Monthly species diversity (H), species evenness (J), and species richness (S) of fish captured in trap nets at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Monthly H values are represented by grey bars; J values by black squares (possible range from zero to one); and S by open circles. Note that during April 2005 and March 2006, only one species of fish (Rhinichthys osculus ) was captured at the Westside transect.

97 species evenness at the Westside transect increased from the second month through the completion of trap netting. Fish species richness peaked in June in both sampling years.

Overall and annual percent length frequency distributions of speckled dace, fathead minnow, yellow perch and slender sculpin captured in trap nets are shown in

Appendices BD – BO. Larger size classes tended to dominate trap net catches of speckled dace and fathead minnow in March and April. In May and June smaller sizes of both species, that were previously excluded from the trap net samples because they easily slipped through the trap net mesh, began to be retained. Because speckled dace and fathead minnow reach maturity at, or just after, a size where they can be retained by the trap nets, these size classes for the most part represent adult fish. Both the smallest and largest slender sculpin were captured from May – August. Of the yellow perch captured, over 90 percent were less than 100mm TL. Most of the larger yellow perch were captured in March; however, a few large yellow perch (over 90 mm TL) were again encountered in the fall.

Light trap fish catches were dominated by cyprinids and cottids (Appendices BP –

BU). Species identification of cyprinids under 25mm and cottids under 15mm TL was problematic, so fish captured in light trap samples are represented at the family level for length frequency analysis. Catches of both families were higher in 2005 than in 2006.

The smallest cyprinid larvae appeared in light trap samples during June and July. The smallest cottids appeared from April – May. No cyprinids under 24mm TL were found in light trap samples during March – May and August – October. Of 902 cyprinids identified to species, 898 were identified as speckled dace, two as fathead minnow and

98 two as tui chub. Of 684 cottids identified to species, 682 were identified as slender sculpin and two were identified as Klamath Lake sculpin. Fourteen juvenile yellow perch

(31 to 45mm TL) were captured in light traps between June and August in 2006. Two juvenile sockeye salmon (30 and 46mm TL) were captured in April and May in 2006.

The temporal patterns in abundance and size classes of other fish (in addition to speckled dace, fathead minnow, yellow perch and slender sculpin) were also investigated.

As a whole, Klamath Lake sculpin were less abundant during spring 2005, absent in spring 2006, but increased in abundance over summer months. Individuals within the smallest size classes were retained by trap nets during August – October. Both adult and juvenile brown bullhead were captured, with the greatest size class diversity occurring during September and October at the Fourmile transect, which coincided with the lowest water levels observed at this transect during the study. At the Westside transect brown bullhead were only captured in July of 2005 and June and July of 2006. Blue chub, less than 90mm, were present during all sampling months, except September 2005 and dominated the overall blue chub catch. Blue chub greater than 90mm were captured May

– August 2005 and May – July 2006, primarily at the Fourmile transect. Adult blue chub were captured at the Westside lower site during June 2005 and at the Westside upper and pasture sites during May 2006. Tui chub less than 90mm TL were not captured during early summer, while larger tui chub were present March – September 2005 and March –

June 2006, almost exclusively at the Fourmile transect. Adult tui chub were only captured at the upper Westside site during May 2006.

Up to 12 individuals of each species from each transect, each month were used to examine time of reproduction in speckled dace, fathead minnow, slender sculpin, and yellow perch. This goal of 12 individuals was not always met because catches of some species were sporadic. Subsamples of 254 speckled dace, 238 fathead minnow, 164 slender sculpin and 124 yellow perch were used to calculate mean, monthly size-class- specific gonadosomatic indices (GSIs) for both males and females. Samples from both transects were combined in this analysis.

Of the speckled dace examined, 68% were female, 31% were male and 1% had undifferentiated gonads. Standard length of the speckled dace subsample ranged from

34.8 to 86mm. All males in the subsample were less than 70mm SL. The largest female speckled dace were captured before May. In both years gonadosomatic index levels followed a distinct seasonal pattern (Figures 23, 24). GSI levels of all female speckled dace greater than 40mm SL peaked in April. Virtually all of these females possessed GSI levels over eight from March through May. Males also showed elevated GSI levels during the period from March through May. However, their GSI levels were less than

5.5. Field observations of robust speckled dace with red coloration both along their fin bases and around their mouths also indicated fish were in spawning condition during this time. Starting in May, female speckled dace GSI decreased, suggesting that speckled dace complete spawning by June. In September, GSI levels increased as the speckled dace began to prepare for the next reproductive season. All speckled dace whose gonads were classified as undifferentiated were caught in May and June, the same months

100

30 Female-2005 25

GSI 10

30 Male-2005 25

GSI 10

Figure 23. Gonadosomatic Index for female and male speckled dace, Rhinichthys osculus, collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005. Size class midpoints represent 10mm standard length size classes.

101

30 Female-2006 25

GSI 10

30 Male-2006 25

GSI 10

Figure 24. Gonadosomatic Index for female and male speckled dace, Rhinichthys osculus, collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – September 2006. Size class midpoints represent 10mm standard length size classes.

102 smaller individuals became vulnerable to the trap net gear. Female GSIs were consistently higher than male GSIs in all months.

Of the fathead minnow examined, 40% were females, 49% were males, and 11% had undifferentiated gonads. Standard lengths ranged from 29 to 59mm. All females were less than 53.1mm SL. Females within the fathead minnow subsample tended to fall within smaller size classes and had a smaller mean SL than did males. Female and male fathead minnow had marked differences in GSIs (Figures 25, 26). In all months GSI levels of males remained below three, while those of virtually all females were above three. Fathead minnow reproduce later in the year than speckled dace. A distinct spike in female fathead minnow GSI values occurred from May into August. During this period most females had GSIs ranging between 10 and 25. Females in all sampled size classes collected from the Fourmile site appear to spawn during a protracted reproductive season. Ovaries of many females contained eggs in various stages of development, suggesting that individuals spawn multiple times. The increase in GSI levels in males was less pronounced, with most values between one and two. As in females, this increase in reproductive condition occurred in virtually all size classes. Secondary sexual characteristics such as nuptial tubercles, dark anterior coloration and a blunt head were observed in males throughout the spawning season. Most GSIs during August – October were less than one, which suggests most spawning is completed prior to August.

The slender sculpin subsample was comprised of 55% females and 41% males.

Four percent possessed undifferentiated gonads. The standard length of all slender sculpin with undifferentiated gonads was less than 40mm. During the period March

103

30 Female-2005 25

GSI 10

0 42 45 48 51 42 45 48 51 42 45 48 51 42 45 48 51 42 45 48 51 42 45 48 51 42 45 48 51 42 45 48 51 < 40 < 52 > 40 < 52 > 40 < 52 > 40 < 52 > 40 < 52 > 40 < 52 > 40 < 52 > 40 < 52 > March April May June July August September October Size Class Midpoints (mm)

30 Male-2005 25

GSI 10

Figure 25. Gonadosomatic Index for female and male fathead minnow, Pimephales promelas , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005. Size class midpoints represent 3mm standard length size classes.

104

30 Female-2006 25

GSI 10

30 Male-2006 25

GSI 10

Figure 26. Gonadosomatic Index for female and male fathead minnow, Pimephales promelas , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – September 2006. Size class midpoints represent 3mm standard length size classes.

105 through June, GSI values were similar for males and females. The maximum gonadosomatic index value for both sexes in these months was 1.7 (Figures 27, 28).

GSIs were slightly higher for female slender sculpin than for male slender sculpin. In

July, GSIs started to increase and peaked in August. In Fourmile Creek slender sculpin prepare for spawning in the late summer/fall, by which time the Westside transect was dry. Consequently, slender sculpin with fully developed gonads were captured only at the

Fourmile transect. Relatively few fish were captured during the fall, so a precise representation of the GSIs for all size classes during the reproductive season is not possible. Increases in reproductive readiness were observed in slender sculpin over

50mm and were highest in the 70 to 80mm SL size class.

The yellow perch subsample was composed of 43% females, 52% males.

Standard lengths of the 5% of yellow perch whose gonads were classified as undifferentiated ranged from 36 to 52mm. All yellow perch possessing undifferentiated gonads were captured during March and June. Both males and females had significantly increased GSI values in March, when yellow perch egg strands and ripe females were observed at the Fourmile site (Figures 29, 30). During April through August, both males and females possessed low GSI values of less than two. With the onset of fall, yellow perch started readying for the subsequent spawning season. No females over 80mm SL were captured in Fourmile Creek during fall, so GSI values for females that would potentially be reproducing the following spring are not available. Female GSIs during the fall remained less than one for the smaller females that were captured. However, males between 40 and 70mm SL possessed higher GSIs, indicating males reach sexual

106

15 Female-2005

GSI 5

15 Male-2005

GSI 5

Figure 27. Gonadosomatic Index for female and male slender sculpin, Cottus tenuis , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – September 2006. Size class midpoints represent 10mm standard length size classes.

107

15 Female-2006

GSI 5

15 Male-2006

GSI 5

Figure 28. Gonadosomatic Index for female and male slender sculpin, Cottus tenuis , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – September 2006. Size class midpoints represent 10mm standard length size classes.

108

20 Female-2005

GSI 10

0 50 70 90 50 70 90 50 70 90 50 70 90 50 70 90 50 70 90 50 70 90 50 70 90 <40 110 <40 110 <40 110 <40 110 <40 110 <40 110 <40 110 <40 110 March >120 April >120 May >120 June >120 July >120 August >120 September >120 October >120 Size Class Midpoints (mm)

20 Male-2005

GSI 10

Figure 29. Gonadosomatic Index for female and male yellow perch, Perca flavescens , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005. Size class midpoints represent 20mm standard length size classes.

109

20 Female-2006

GSI 10

20 Male-2006

GSI 10

Figure 30. Gonadosomatic Index for female and male yellow perch, Perca flavescens , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – September 2006. Size class midpoints represent 20mm standard length size classes.

110 maturity at a smaller size than do females and are undergoing gonadal recrudescence in the fall.

Two Fulton type condition factors (CF1 and CF3) were used to investigate overall condition of speckled dace, fathead minnow, slender sculpin and yellow perch during each sampling month. CF1 takes into account both somatic and gonad condition and is an indicator of overall condition, while CF3 reflects somatic condition only. For each species, both CF1 and CF3 were calculated by size class, first for all individuals, and then separately for each sex. The same specimens used to examine reproduction were used to analyze condition factor. Samples from the 2005 and the 2006 sampling years and from both transects were combined in this analysis. CF1 and CF3 values of all individuals examined by species are compared in Figures 31 – 34. Means of both condition factors were highest in fathead minnow. Mean CF1 was lowest in yellow perch, while mean of

CF3 was lowest in slender sculpin. Speckled dace and fathead minnow possessed very similar mean values for each condition factor. Each condition factor differed by less than

5% between speckled dace and fathead minnow. Both species have similar round body morphologies. The mean condition factor values of slender sculpin and yellow perch also were similar to each other. Differences in the mean values of the two condition indices of these two species were also less than 5%. These two species tended to have a more oval cross sections and robust fore bodies. This similarity in condition indices between slender sculpin and yellow perch may also be influenced by the skewed size class distribution of yellow perch in samples. The majority of the yellow perch captured in trap nets were less than 70mm TL, while most slender sculpin were less than 85mm TL.

111

1 Condition Factor 1 Condition

1 Condition Factor 3 Condition

Figure 31. Fulton-type condition factors for speckled dace, Rhinichthys osculus , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Condition factor 1 is based on total body weight; Condition factor 3 is based on gonad-free, gut-free body weight. Horizontal line represents mean value for each condition factor. Size class midpoints represent 10mm standard length size classes.

112

1 Condition Factor 1 Condition

1 Condition Factor 3 Condition

Figure 32. Fulton-type condition factors for fathead minnow, Pimephales promelas , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Condition factor 1 is based on total body weight; Condition factor 3 is based on gonad-free, gut-free body weight. Horizontal line represents mean value for each condition factor. Size class midpoints represent 3mm standard length size classes.

113

1 Condition Factor 1 Condition

1 Condition Factor 3 Condition

Figure 33. Fulton-type condition factors for slender sculpin, Cottus tenuis , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Condition factor 1 is based on total body weight; Condition factor 3 is based on gonad-free, gut-free body weight. Horizontal line represents mean value for each condition factor. Size class midpoints represent 10mm standard length size classes.

114

1 Condition Factor 1 Condition

1 Condition Factor 3 Condition

Figure 34. Fulton-type condition factors for yellow perch, Perca flavescens , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Condition factor 1 is based on total body weight; Condition factor 3 is based on gonad-free, gut-free body weight. Horizontal line represents mean value for each condition factor. Size class midpoints represent 20mm standard length size classes.

115

Each of the four species possessed a seasonal peak in condition factor. In speckled dace this peak was more pronounced in the CF1 values, and occurred during early to mid spring. Fathead minnow condition factors, on the other hand, peaked during late spring and early summer, especially in minnow over 46mm SL. Condition factors of non-sexually mature fathead minnow were relatively constant during March through

October. Slender sculpin condition factors, especially those of larger size classes, increased during late spring and early summer and decreased in the fall. Interpretation of yellow perch condition factors is hampered by missing size classes during several months. CF1 values were highest in larger yellow perch and appeared to peak during

July.

In order to see how sex-specific condition varied seasonally, condition factors were calculated for both male and female fish. Male speckled dace were dominated by smaller size classes, preventing comparison of condition factors for both sexes across all size classes (Figures 35, 36). Larger reproductive females possessed high CF1 levels in

April and May. However, male CF1 values were not greatly elevated during these reproductive months (Figure 35). Females were investing more heavily than males in gonad development during these months (Figure 36). CF3 values for females dropped slightly during August and September. The high CF1 value for female speckled dace less than 40mm SL, captured in September, represents a single individual. Except for this individual, both the CF1 and the CF3 values for all size classes of female speckled dace increased in October.

116

3 Female

1 Condition Factor 1 Condition

3 Male

1 Condition Factor 1 Condition

Figure 35. Fulton-type condition factors for female and male speckled dace, Rhinichthys osculus , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Condition factor 1 is based on total body weight. Horizontal line represents mean value for each condition factor. Size class midpoints represent 10mm standard length size classes.

117

3 Female

1 Condition Factor 3 Condition

3 Male

1 Condition Factor 3 Condition

Figure 36. Fulton-type condition factors for female and male speckled dace, Rhinichthys osculus , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Condition factor 3 is based on gonad-free, gut-free body weight. Horizontal line represents mean value for each condition factor. Size class midpoints represent 10mm standard length size classes.

118

Calculating the condition factors for male and female fathead minnow separately revealed interesting trends (Figures 37, 38). Fathead minnow CF1 showed a definite seasonal increase in the condition of females, and, less obviously, in males. Male fathead minnow CF3 values increased during the protracted spawning season from May to

August. This increase is likely linked to development of secondary sexual characteristics in males. In addition to overall darkening in skin coloration, male fathead minnows develop thick tubercles and dorsal pads, which likely cause significant increases in body weight. Within size classes, CF3 values for female fathead minnows were lower than

CF1 values, while in males the two condition indices were almost identical. While females invested energy in egg development, males invested energy mainly in somatic growth, secondary sexual characteristics and parental care of eggs.

Condition factor of both male and female slender sculpin was lowest during

March and April (Figures 39, 40). Larger male slender sculpin possessed the lowest CF1 and CF3 values during March and April. The low condition factor of slender sculpin during these months was obvious, even during trap netting and sample processing.

Slender sculpin taken during March and April appeared emaciated, while those taken in later months were obviously more robust. After May, larger males had the highest ranking CF1 and CF3 values. Both male and female condition factors peaked in July. As

CF3 tended to be higher in males than females, somatic allocation appears to be highest in male slender sculpin.

In yellow perch, condition factor of the smallest size classes remained relatively constant during March through October (Figures 41, 42). This was true for both sexes,

119

3 Female

1 Condition Factor 1 Condition

3 Male

1 Condition Factor 1 Condition

Figure 37. Fulton-type condition factors for female and male fathead minnow, Pimephales promelas , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Condition factor 1 is based on total body weight. Horizontal line represents mean value for each condition factor. Size class midpoints represent 3mm standard length size classes.

120

3 Female

1 Condition Factor 3 Condition

3 Male

1 Condition Factor 3 Condition

Figure 38. Fulton-type condition factors for female and male fathead minnow, Pimephales promelas , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Condition factor 3 is based on gonad-free, gut-free body weight. Horizontal line represents mean value for each condition factor. Size class midpoints represent 3mm standard length size classes.

121

3 Female

1 Condition Factor 1 Condition

3 Male

1 Condition Factor 1 Condition

Figure 39. Fulton-type condition factors for female and male slender sculpin, Cottus tenuis , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Condition factor 1 is based on total body weight. Horizontal line represents mean value for each condition factor. Size class midpoints represent 10mm standard length size classes.

122

3 Female

1 Condition Factor 3 Condition

3 Male

1 Condition Factor 3 Condition

Figure 40. Fulton-type condition factors for female and male slender sculpin, Cottus tenuis , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Condition factor 3 is based on gonad-free, gut-free body weight. Horizontal line represents mean value for each condition factor. Size class midpoints represent 10mm standard length size classes.

123

3 Female

1 Condition Factor 1 Condition

3 Male

1 Condition Factor 1 Condition

Figure 41. Fulton-type condition factors for female and male yellow perch, Perca flavescens , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Condition factor 1 is based on total body weight. Horizontal line represents mean value for each condition factor. Size class midpoints represent 20mm standard length size classes.

124

3 Female

1 Condition Factor 3 Condition

3 Male

1 Condition Factor 3 Condition

Figure 42. Fulton-type condition factors for female and male yellow perch, Perca flavescens , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Condition factor 3 is based on gonad-free, gut-free body weight. Horizontal line represents mean value for each condition factor. Size class midpoints represent 20mm standard length size classes.

125 even though males appeared to reach sexual maturity at a smaller size and younger age than did females. In the spring, the CF3 values of large female yellow perch with mature ovaries were lower than those of males in the same size classes.

Hepatosomatic index values (HSIs) appeared strongly correlated to season, sex and size class in slender sculpin (Figure 43). Those female slender sculpin that likely did not spawn in the previous year (sculpin less than 50mm SL) possessed similar HSI values from March to September. During spring, HSIs of all slender sculpin of post- reproductive size were at their lowest levels. These sculpin had mobilized their liver reserves for both gonad growth and metabolism during the fall and winter. Both male and female slender sculpin HSIs peaked around May (coinciding with peak CF values).

However, the duration of the peak differed between the sexes. HSIs of female slender sculpin, especially those of reproductive age, remained elevated through August, when gonadal recrudescence commenced. The HSIs of male slender sculpin, even in sexually mature fish, decreased more rapidly in late summer. Yellow perch HSIs for pre- reproductive age classes were highest in March and October (Figure 44). Few sexually mature yellow perch were captured after March. However, it appears that liver reserves in male individuals that would potentially reproduce during the following spring

(individuals between 40 and 70 mm SL) increased during October.

The same specimens used to examine reproduction and condition factor were used for diet analysis. Samples from the 2005 and 2006 sampling years and from both transects were combined in this analysis. A total of 254 speckled dace, 238 fathead minnow, 164 slender sculpin and 124 yellow perch made up the subsample of overnight

126

5 Female

1 Hepatosomatic index Hepatosomatic

5 Male

1 Hepatosomatic index Hepatosomatic

0 45 55 65 75 45 55 65 75 45 55 65 75 45 55 65 75 45 55 65 75 45 55 65 75 45 55 65 75 45 55 65 75 < 40 < 80 > 40 < 80 > 40 < 80 > 40 < 80 > 40 < 80 > 40 < 80 > 40 < 80 > 40 < 80 > March April May June July August September October Size Class Midpoints (mm) Figure 43. Hepatosomatic index for female and male slender sculpin, Cottus tenuis , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Horizontal line represents mean value for both sexes. Size class midpoints represent 10mm standard length size classes.

127

5 Female

1 Hepatosomatic index Hepatosomatic

5 Male

1 Hepatosomatic index Hepatosomatic

Figure 44. Hepatosomatic index for female and male yellow perch, Perca flavescens , collected in trap nets at the Fourmile (FM) and Westside (WS) sampling transects, Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Horizontal line represents mean value for both sexes. Size class midpoints represent 20mm standard length size classes.

128 trap-net caught fish used for the primary diet analysis. In addition, 131 speckled dace,

105 fathead minnow, 10 slender sculpin and 68 yellow perch captured by seine and short trap net sets (short duration/mixed gear samples) were used separately in the diet analysis. The short duration/mixed gear samples were used to identify any biases due to factors such as post-capture digestion and(or) ingestion of prey by fish in overnight trap net sets. In the overnight trap net samples a total of 100 (39.4%) speckled dace, 84

(35.6%) fathead minnow, 33 (20.1%) slender sculpin and 47 (37.9%) yellow perch had empty foreguts. In the short duration/mixed gear samples, 12 (9.2%) speckled dace, 21

(20%) fathead minnow, no slender sculpin and four (5.9%) yellow perch had empty foreguts.

Overall numerical abundance (% num), weight importance (% wt), and percent frequency occurrence (% freq) of major prey of each fish species in overnight trap nets can be found in Tables 37 – 40. Important food items for all four species included microcrustaceans (especially Cladocera) and insect larvae (especially Chironomidae,

Trichoptera and Hemiptera). Another food item was “gorp”, a complex mix of organic and inorganic debris (Mulligan et al. 2009). The inorganic debris consisted of fine silt and sand. The organic debris consisted of a complex mixture of diatoms, plant fibers and broken arthropod exoskeletons. Diatoms (in great abundance) are the definitive organic ingredient of “gorp”. The organic and inorganic materials comprising the tubes of tube- dwelling Chironomidae are very similar in composition to “gorp”. In this analysis, the importance of “gorp” in cyprinid diets was probably understated because it was always assigned a numeric abundance of one.

Table 37. Percent number, percent weight and percent frequency of occurrence of major dietary groups consumed by speckled dace, Rhinichthys osculus , collected at two sampling transects, Fourmile (FM) and Westside (WS) in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Size class values are midpoints of 10mm standard length size classes. *indicates minor taxa and/or unidentifiable parts.

< 40 mm 45 mm 55 mm 65 mm >70 mm SIZE CLASS % % % % % % % % % % % % % % % MIDPOINTS # wt freq # wt freq # wt freq # wt freq # wt freq Oligochaeta 11.7 48.1 8.3 2.9 22.6 10.9 1.2 19.0 4.7 1.8 45.2 9.4 0.0 0.0 0.0 Mollusca

Gastropoda 0.0 0.0 0.0 0.0 0.0 0.0 0.4 2.5 4.7 0.0 0.0 0.0 0.2 5.5 6.7 Bivalvia 0.0 0.0 0.0 0.1 0.4 0.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Crustacea

Cladocera 4.9 0.0 16.7 20.4 5.2 21.8 6.5 3.0 11.8 5.4 3.7 3.1 0.4 0.0 13.3 Copepoda 0.0 0.0 0.0 6.5 3.7 5.5 3.3 1.8 4.7 4.0 1.4 6.3 0.0 0.0 0.0 Other Crustacea* 0.0 0.0 0.0 0.2 0.4 1.8 0.3 0.1 2.4 1.3 1.3 6.3 0.0 0.0 0.0 Insecta

Chironomidae (larvae) 80.6 32.1 41.7 63.5 35.0 29.1 77.7 40.5 25.9 63.2 11.3 28.1 5.9 13.4 26.7 Coleoptera 0.0 0.0 0.0 0.3 0.2 4.5 0.5 1.3 5.9 0.9 4.1 6.3 0.4 1.8 6.7 Diptera (other) 0.0 0.0 0.0 0.7 4.9 3.6 5.2 4.8 11.8 1.3 0.7 9.4 0.4 0.5 13.3 Ephemeroptera 0.0 0.0 0.0 0.7 2.2 1.8 0.2 0.8 2.4 0.0 0.0 0.0 0.4 15.8 6.7 Hemiptera 0.0 0.0 0.0 0.1 0.2 0.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Odonata 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.0 1.2 0.0 0.0 0.0 0.0 0.0 0.0 Simuliidae (larvae) 0.0 0.0 0.0 2.4 3.7 7.3 2.0 1.0 2.4 17.0 6.1 12.5 90.9 47.5 13.3 Trichoptera 0.0 0.0 0.0 0.4 7.1 4.5 1.2 13.2 10.6 1.3 20.7 9.4 0.6 9.9 13.3 Other Insecta* 0.0 0.0 0.0 0.8 7.0 7.3 0.5 3.2 1.2 0.9 1.5 6.3 0.0 0.0 0.0 Gorp 1.9 18.9 16.7 0.8 7.0 10.0 0.5 1.0 5.9 1.3 2.1 9.4 0.4 4.7 13.3 Other* 1.0 1.0 8.3 0.3 0.5 3.6 0.5 7.8 5.9 1.3 2.0 9.4 0.2 0.8 6.7

129

Table 38. Percent number, percent weight and percent frequency of occurrence of major dietary groups consumed by fathead minnow, Pimephales promelas , collected at two sampling transects, Fourmile (FM) and Westside (WS) in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Size class values are midpoints of 3mm standard length size classes. * indicates minor taxa and/or unidentifiable parts.

SIZE CLASS < 40 mm 42 mm 45 mm 48 mm >49 mm MIDPOINTS % % % % % % % % % % % % % % % # wt freq # wt freq # wt freq # wt freq # wt freq Oligochaeta 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.2 0.5 2.0 Gastropoda 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.2 5.3 2.0 Crustacea Cladocera 79.2 38.3 17.6 38.5 14.9 17.9 66.2 55.3 30.2 58.4 31.1 21.9 74.8 30.8 23.5 Ostracoda 1.8 0.3 3.9 0.0 0.0 0.0 6.0 2.8 3.2 0.8 0.0 3.1 2.6 8.0 3.9 Copepoda 6.6 2.1 3.9 24.8 23.1 7.7 13.6 5.8 7.9 0.0 0.0 0.0 4.3 0.6 3.9 Other Crustacea* 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.1 2.3 3.9 Insecta Chironomidae (larvae) 5.1 5.6 15.7 23.9 6.8 23.1 9.0 7.7 25.4 17.6 7.0 18.8 4.8 5.8 17.6 Coleoptera 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.2 0.5 2.0 Diptera (other) 0.0 0.0 0.0 0.0 0.0 0.0 0.2 3.0 1.6 0.0 0.0 0.0 0.0 0.0 0.0 Simuliidae (larvae) 1.2 5.0 3.9 1.7 4.1 2.6 1.0 0.0 4.8 0.0 0.0 0.0 0.3 0.0 2.0 Other Insecta* 0.3 0.0 2.0 0.0 0.0 0.0 0.5 3.4 3.2 0.8 0.3 3.1 0.3 5.4 3.9 Gorp 3.9 33.6 25.5 8.5 51.1 25.6 3.3 22.0 22.2 11.2 56.6 43.8 3.3 32.1 41.2 Other* 1.8 15.0 5.9 2.6 0.0 7.7 0.2 0.0 1.6 11.2 5.0 15.6 7.9 8.9 15.7

130

Table 39. Percent number, percent weight and percent frequency of occurrence of major dietary groups consumed by slender sculpin, Cottus tenuis , collected at two sampling transects, Fourmile (FM) and Westside (WS) in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Size class values are midpoints of 10mm standard length size classes. * indicates minor taxa and/or unidentifiable parts.

SIZE CLASS < 40 mm 45 mm 55 mm 65 mm >70 mm MIDPOINTS % % % % % % % % % % % % % % % # wt freq # wt freq # wt freq # wt freq # wt freq Hirudinea 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.1 4.2 2.8 0.0 0.0 0.0 Gastropoda 0.0 0.0 0.0 0.0 0.0 0.0 1.7 0.2 2.9 2.2 0.6 2.8 0.0 0.0 0.0

Crustacea Cladocera 2.3 1.0 7.7 2.8 0.4 10.0 2.9 0.3 5.9 2.2 0.0 5.6 0.7 0.0 5.6 Copepoda 23.3 1.8 19.2 21.6 6.4 14.0 2.3 0.0 8.8 1.1 0.0 2.8 4.2 0.0 22.2 Ostracoda 0.0 0.0 0.0 1.7 1.6 2.0 0.0 0.0 0.0 1.1 0.0 2.8 0.7 6.3 5.6 Other Crustacea* 0.0 0.0 0.0 1.4 2.8 6.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Insecta Chironomidae (larvae) 60.5 33.6 38.5 54.8 34.3 46.0 58.7 8.1 41.2 37.8 3.0 36.1 61.3 4.0 38.9 Coleoptera 3.9 8.0 11.5 0.6 1.1 4.0 9.3 13.3 35.3 5.6 3.8 11.1 4.9 3.4 22.2 Diptera (other) 0.8 0.9 3.8 9.3 1.8 6.0 0.6 0.1 2.9 2.2 0.4 5.6 1.4 0.3 11.1 Ephemeroptera 0.0 0.0 0.0 1.7 27.9 10.0 4.7 23.9 11.8 4.4 13.2 5.6 4.2 11.9 5.6 Hemiptera 0.0 0.0 0.0 0.0 0.0 0.0 2.3 5.5 11.8 2.2 0.4 5.6 2.8 1.3 22.2 Odonata 0.0 0.0 0.0 0.8 1.9 6.0 0.0 0.0 0.0 10.0 23.1 16.7 2.1 2.7 11.1 Simuliidae (larvae) 0.8 0.0 3.8 0.3 0.0 2.0 1.7 0.1 2.9 1.1 0.3 2.8 0.0 0.0 0.0 Trichoptera 4.7 28.5 15.4 1.1 9.9 8.0 9.3 21.5 23.5 14.4 24.4 22.2 9.2 9.7 33.3 Other Insecta* 1.6 2.8 7.7 2.2 8.9 14.0 2.3 6.6 11.8 4.4 2.7 11.1 0.7 1.0 5.6 Fish 0.8 15.0 3.8 0.0 0.0 0.0 0.0 0.0 0.0 3.3 23.4 8.3 1.4 54.0 11.1 Gorp 0.8 5.0 3.8 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Other* 0.8 3.4 3.8 1.7 2.9 12.0 4.1 20.3 20.6 6.7 0.7 16.7 6.3 5.3 44.4

131

Table 40. Percent number, percent weight and percent frequency of occurrence of major dietary groups consumed by yellow perch, Perca flavescens , collected at two sampling transects, Fourmile (FM) and Westside (WS) in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Size class values are midpoints of 20mm standard length size classes. *indicates minor taxa and/or unidentifiable parts.

SIZE CLASS < 40 mm 50 mm 70 mm 90 mm >100 mm MIDPOINTS % % % % % % % % % % % % % % % # # wt freq # wt freq # wt freq # wt freq wt freq Oligochaeta 0.4 10.3 3.6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Gastropoda 0.4 0.0 3.6 0.6 8.6 4.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Crustacea Cladocera 34.2 8.0 35.7 18.7 1.9 23.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Copepoda 43.7 11.2 35.7 49.9 2.5 25.4 54.5 0.1 18.8 0.0 0.0 0.0 0.0 0.0 0.0 Ostracoda 0.0 0.0 0.0 0.2 0.0 1.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Hydrachnida 0.9 0.0 3.6 0.2 0.0 1.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Insecta Chironomidae (larvae) 11.3 3.1 46.4 10.8 2.7 25.4 18.2 0.9 12.5 0.0 0.0 0.0 0.0 0.0 0.0 Coleoptera 0.0 0.0 0.0 1.2 0.4 3.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Diptera (other) 3.5 15.5 17.9 2.3 1.5 7.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Ephemeroptera 1.3 0.7 10.7 11.6 6.8 16.4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Hemiptera 0.4 0.0 3.6 1.2 1.3 6.0 0.0 0.0 0.0 0.0 0.0 0.0 16.7 0.3 12.5 Odonata 1.3 17.3 10.7 1.5 26.9 10.4 9.1 1.3 6.3 0.0 0.0 0.0 0.0 0.0 0.0 Simuliidae (larvae) 0.9 4.6 3.6 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Trichoptera 0.4 16.6 3.6 0.4 2.9 3.0 18.2 97.7 6.3 0.0 0.0 0.0 0.0 0.0 0.0 Fish 0.0 0.0 0.0 0.8 42.9 6.0 0.0 0.0 0.0 100.0 100.0 60.0 50.0 97.8 37.5 Other * 1.3 12.7 10.7 0.4 1.6 3.0 0.0 0.0 0.0 0.0 0.0 0.0 33.3 1.9 12.5

132

133

One similarity across all species was at least one size class’s dependence upon either or both chironomid larvae and Cladocera. Speckled dace of all sizes relied upon chironomid larvae as a dominant food item (Table 37). The next most important food group was annelids, specifically Oligochaeta. Cladocera and copepods were other major foods. Fathead minnow fed principally upon Cladocera, “gorp” and chironomid larvae

(Table 38). “Gorp” seemed to be the more important food group for larger size classes.

The importance of invertebrates and “gorp” in the diet of smaller fathead minnow was similar. Slender sculpin utilized a broad range of foods (Table 39). Again,

Chironomidae were among the most frequent and abundant foods. In smaller slender sculpin, they accounted for the highest percentage of the prey weight. In larger slender sculpin, larger insects such as Ephemeroptera, Odonata and Coleoptera were more important prey items. Yellow perch showed a definite shift in diet with increasing size(Table 40). Younger individuals (less than 60mm SL) fed primarily upon crustaceans, especially Cladocera and Copepods. Larger yellow perch shifted their dietary focus toward bigger prey items, including Trichoptera and fish.

Seasonal trends were present in the diet of the four fish species examined from overnight trap net samples. Species specific plots of percent index of relative importance

(% IRI) values for each size class by season can be found in Figures 45 – 50. Insects, particularly chironomids, simuliids and trichopterans, were the dominant food for all size classes of speckled dace from March – June (Figures 45, 46). Crustaceans and annelids were other important foods for most size classes of speckled dace during this period. The composition and relative importance of food items in the speckled dace diet changed after

0 33 34 11 6 9 37 25 10 4 1 22 14 7 5 2 18 12 4 0 100

40 IRI Percent IRI

0 < 40 45 55 65 > 70 < 40 45 55 65 > 70 < 40 45 55 65 > 70 < 40 45 55 65 > 70 Mar/Apr May/Jun Jul/Aug Sep/Oct

Annelida Crustacea Insecta Gorp Other

Figure 45. Index of relative importance (IRI) values of major dietary groups consumed by speckled dace, Rhinichthys osculus , collected in trap nets at two sampling transects, Fourmile (FM) and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. IRI values normalized to 100% for each size class- season category. Size class values are midpoints of 10mm standard length classes. Numbers at tops of bars indicate total number of gastrointestinal tracts examined.

134

0 13 18 7 4 3 21 8 5 1 1 9 7 2 1 1 8 3 1 0 100

40 IRI Percent IRI

0 < 40 45 55 65 > 70 < 40 45 55 65 > 70 < 40 45 55 65 > 70 < 40 45 55 65 > 70 Mar/Apr May/Jun Jul/Aug Sep/Oct Chironomidae (larvae) Coleoptera Other Insecta Simulidae (larvae) Ephemeroptera Diptera (other) Trichoptera Figure 46. Index of relative importance (IRI) values of insect orders consumed by speckled dace, Rhinichthys osculus , collected in trap nets at two sampling transects, Fourmile (FM) and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. IRI values normalized to 100% for each size class-season category. Size class values are midpoints of 10mm standard length classes. Numbers at tops of bars indicate total number of gastrointestinal tracts containing insects.

135

13 13 12 3 8 15 14 22 15 18 14 6 21 9 17 9 6 8 5 8 100

40 IRI Percent IRI

0 <40 42 45 48 >49 <40 42 45 48 >49 <40 42 45 48 >49 <40 42 45 48 >49 Mar/Apr May/Jun Jul/Aug Sep/Oct

Annelida Crustacea Insecta Gorp Other Figure 47. Index of relative importance (IRI) values of major dietary groups consumed by fathead minnow, Pimephales promelas , collected in trap nets at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. IRI values normalized to 100% for each size class-season category. Size class values are midpoints of 3mm standard length classes. Numbers at tops of bars indicate total number of gastrointestinal tracts examined.

136

14 16 8 7 3 0 15 15 10 6 8 12 6 17 8 4 7 5 2 1 100

40 IRI Percent IRI

0 < 40 45 55 65 > 70 < 40 45 55 65 > 70 < 40 45 55 65 > 70 < 40 45 55 65 > 70 Mar/Apr May/Jun Jul/Aug Sep/Oct

Annelida Crustacea Insecta Fish Other

Figure 48. Index of relative importance (IRI) values of major dietary groups consumed by slender sculpin, Cottus tenuis , collected in trap nets at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. IRI values normalized to 100% for each size class- season category. Size class values are midpoints of 10mm standard length classes. Numbers at tops of bars indicate total number of gastrointestinal tracts examined.

137

9 6 6 4 3 0 14 14 8 6 5 9 3 13 6 4 3 5 1 1 100

40 IRI Percent IRI

0 < 40 45 55 65 > 70 < 40 45 55 65 > 70 < 40 45 55 65 > 70 < 40 45 55 65 > 70 Mar/Apr May/Jun Jul/Aug Sep/Oct Chironomidae (larvae) Ephemeroptera Trichoptera Coleoptera Hemiptera Other Insecta Diptera (other) Odonata Figure 49. Index of relative importance (IRI) values of insect orders consumed by slender sculpin, Cottus tenuis , collected in trap nets at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. IRI values normalized to 100% for each size class-season category. Size class values are midpoints of 10mm standard length classes. Numbers at tops of bars indicate total number of gastrointestinal tracts containing insects.

138

0 12 9 1 6 15 0 1 1 0 9 29 1 2 2 4 26 5 1 0 100

40 IRI Percent IRI

0 <40 50 70 90 >100 <40 50 70 90 >100 <40 50 70 90 >100 <40 50 70 90 >100 Mar/Apr May/Jun Jul/Aug Sep/Oct

Mollusca Crustacea Insecta Fish Other Figure 50. Index of relative importance (IRI) values of major dietary groups consumed by yellow perch, Perca flavescens , collected in trap nets at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. IRI values normalized to 100% for each size class- season category. Size class values are midpoints of 20mm standard length classes. Numbers at tops of bars indicate total number of gastrointestinal tracts examined.

139

140

June. While insects remained the most important food for speckled dace over 40mm SL,

“gorp” became the most important component in the diet of speckled dace less than

40mm SL during July – October. Crustaceans were utilized only by speckled dace between 40 and 50mm SL during July – October. Annelids and simuliids disappeared entirely from the speckled dace diet after June. The food group “other” was important during July/August when it was utilized by virtually all size classes of speckled dace. In speckled dace, this food group consisted of large pieces of vegetation and the unidentifiable digested remains of what were most likely snails. These foods were not included under “gorp” because they remained in large, intact pieces.

“Gorp” and Crustacea were the most important components in the diet of most size classes of fathead minnow from March – October (Figure 47). Fathead minnows greater than 43mm SL relied less upon “gorp” during September/October than during

March – August. The composition of the crustacean component in the fathead minnow diet varied seasonally. During March/April, copepods were more abundant than cladocerans in fathead minnow gut samples. Cladocerans were both the most abundant and most frequently encountered crustacean during May/June, July/August and

September, but were entirely absent in October gut samples. Ostracoda was the most important crustacean taxon in the fathead minnow diet in October, but were only observed in two stomachs.

Seasonally, the percent IRI of insects was lower than that of crustaceans for most size classes of fathead minnow. All size classes of fathead minnow consumed insects

141 from March through August; however, during September/October insects were only consumed by fathead minnow between 43 and 49 mm SL. Virtually all identifiable insects in fathead minnow gastrointestinal tracts were chironomid larvae. Other dipterans, including dipteran pupae and simuliid larvae, were more important than coleopterans (the only other identifiable insect order found in overnight trap-net fathead minnow gut samples). During April, both the percent number and percent frequency of occurrence of chironomid and simuliid larvae in fathead minnow gastrointestinal tracts were similar; during other months chironomids were by far the most important insect in the fathead minnow diet. Simuliids were found in only one size class of fathead minnow

(43 to 46mm SL) during May/June and were not found in samples taken in subsequent months. Vegetation, annelids, and fish scales (included in the “other” category) were observed both infrequently and in low numbers.

Insects were by far the most important food group throughout the year for slender sculpin (Figure 48). The percent IRI of insect orders consumed by slender sculpin is presented in Figure 49. During March – October, chironomid larvae were the most important insects in the diet of slender sculpin less than 50mm SL. From July – October, chironomids were the single most important insect food group for most size classes of slender sculpin. Larger insect larvae, including Coleoptera, Trichoptera and

Ephemeroptera were seasonally important dietary components. Coleoptera were present in slender sculpin gastrointestinal tracts primarily during March/April. Trichoptera larvae were important dietary components of all size classes of slender sculpin during

142

March – June. Ephemeroptera nymphs were preyed upon during May/June and

September/October.

Crustaceans and fish were seasonally important, non-insect components of the slender sculpin diet (Figure 48). Copepods were the most important crustacean in the slender sculpin diet during March/April and September/October, but were observed in stomachs during all months. Cladocera were the dominant crustacean prey during

May/June. Conchostracans and ostracods were found only during May. Single occurrences of amphipods were noted in slender sculpin gastrointestinal tracts collected in April and August. While the importance of crustaceans in the slender sculpin diet was greatest during March/April, fish increased in importance from March – October in slender sculpin over 60mm SL. Identifiable fish found in slender sculpin gastrointestinal tracts included juvenile Cottus spp. and juvenile/adult fathead minnow. Annelids were

not an important food for slender sculpin, as only one specimen was noted during July

2006, at the Westside lower site. Interestingly, this was the only leech found during gut

analysis of all four species.

All yellow perch greater than 80mm SL relied upon fish as their primary prey

item during March – October (Figure 50). At least two of the ingested fish found in

yellow perch caught at the Fourmile transect in July 2006 were speckled dace.

Identification of other ingested fish to the family or species level was impossible due to

digestion. Yellow perch less than 80mm SL did not prey heavily upon fish, but instead

ate mainly crustaceans and insects. Cladocera and copepods were consumed during all

143 months; however, both the abundance and frequency of occurrence of these two crustacean taxa were highest during July/August and September/October. Copepods were the most important crustacean in the yellow perch diet during all months except

May/June. Chironomid larvae and mayfly nymphs were also consumed during most months. Both Anisoptera and Zygoptera were consumed by yellow perch during June and July. Corixid adults were found in yellow perch foreguts between June and

September. Infrequently consumed insect taxa included dytiscid beetles, trichopterans and simuliids. Mollusks were a minor component of the diet of yellow perch in lower

Fourmile Creek. Snails were identified in a few yellow perch gastrointestinal tracts, but only during July and October.

The percent IRI of major dietary groups consumed by speckled dace, fathead minnow, slender sculpin and yellow perch collected in short duration/mixed gear samples are presented in Figures 51 – 56. The percent IRI of major food groups consumed by speckled dace captured in short duration/mixed gear samples (Figures 51, 52) were similar to those captured in overnight trap net sets (Figures 45, 46). In both sample types, insects were the most important food category consumed by most size classes of speckled dace through June. Crustaceans were least important during July/August; and the importance of “gorp” increased after July. In both sample types, the proportional importance of specific prey (i.e. simuliids and copepods) versus more general prey (i.e.

“gorp” and unidentified animal parts) decreased after June. For most size classes of speckled dace, crustaceans and annelids were proportionally more important foods for

3 10 5 3 0 12 26 3 3 0 11 28 6 1 0 16 4 0 0 0 100

90 Annelida 80 Crustacea 70 Insecta Gorp 60 Other

40 IRI Percent IRI

0 < 40 45 55 65 > 70 < 40 45 55 65 > 70 < 40 45 55 65 > 70 < 40 45 55 65 > 70 Mar/Apr May/Jun Jul/Aug Sep/Oct

Figure 51. Index of relative importance (IRI) values of major dietary groups consumed by speckled dace, Rhinichthys osculus , collected in short duration/mixed gear samples at two sampling transects, Fourmile (FM) and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. IRI values normalized to 100% for each size class-season category. Size class values are midpoints of 10mm standard length classes. Numbers at tops of bars indicate total number of gastrointestinal tracts examined.

144

2 9 4 3 0 7 21 2 2 0 7 17 3 1 0 14 2 0 0 0 100

90 ChironomidaeChironomidae (larvae) (larvae) 80 SimulidaeSimulidae (larvae) (larvae) 70 DipteraDiptera (other) (other) Coleoptera 60 Coleoptera EphemeropteraEphemeroptera 50 TrichopteraTrichoptera OtherOther Insecta Insecta 40 IRI Percent IRI

0 < 40 45 55 65 > 70 < 40 45 55 65 > 70 < 40 45 55 65 > 70 < 40 45 55 65 > 70 Mar/Apr May/Jun Jul/Aug Sep/Oct

Figure 52. Index of relative importance (IRI) values of insect orders consumed by speckled dace, Rhinichthys osculus , collected in short duration/mixed gear samples at two sampling transects, Fourmile (FM) and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. IRI values normalized to 100% for each size class-season category. Size class values are midpoints of 10mm standard length classes. Numbers at tops of bars indicate total number of gastrointestinal tracts containing insects.

145

5 0 0 0 0 22 8 5 1 7 6 7 5 6 12 13 3 4 1 0 100

90 Annelida 80 Crustacea 70 Insecta Gorp 60 Other

40 IRI Percent IRI

0 <40 42 45 48 >49 <40 42 45 48 >49 <40 42 45 48 >49 <40 42 45 48 >49 Mar/Apr May/Jun Jul/Aug Sep/Oct

Figure 53. Index of relative importance (IRI) values of major dietary groups consumed by fathead minnow, Pimephales promelas , collected in short duration/mixed gear samples at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. IRI values normalized to 100% for each size class-season category. Size class values are midpoints of 3mm standard length classes. Numbers at tops of bars indicate total number of gastrointestinal tracts examined.

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1 0 0 1 0 2 0 1 0 0 5 0 0 0 0 0 0 0 0 0 100

90 Annelida 80 Crustacea 70 Insecta Fish 60 Other

40 IRI Percent IRI

0 < 40 45 55 65 > 70 < 40 45 55 65 > 70 < 40 45 55 65 > 70 < 40 45 55 65 > 70 Mar/Apr May/Jun Jul/Aug Sep/Oct

Figure 54. Index of relative importance (IRI) values of major dietary groups consumed by slender sculpin, Cottus tenuis , collected in short duration/mixed gear samples at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. IRI values normalized to 100% for each size class-season category. Size class values are midpoints of 10mm standard length classes. Numbers at tops of bars indicate total number of gastrointestinal tracts examined.

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1 0 0 1 0 2 0 1 0 0 5 0 0 0 0 0 0 0 0 0 100

90 Chironomidae (larvae) 80 Coleoptera 70 Diptera (other)

60 Ephemeroptera Hemiptera 50 Odonata

40 Trichoptera IRI Percent IRI Other Insecta 30

0 < 40 45 55 65 > 70 < 40 45 55 65 > 70 < 40 45 55 65 > 70 < 40 45 55 65 > 70 Mar/Apr May/Jun Jul/Aug Sep/Oct

Figure 55. Index of relative importance (IRI) values of insect orders consumed by slender sculpin, Cottus tenuis , collected in short duration/mixed gear samples at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. IRI values normalized to 100% for each size class-season category. Size class values are midpoints of 10mm standard length classes. Numbers at tops of bars indicate total number of gastrointestinal tracts containing insects.

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0 0 0 0 0 12 0 0 0 0 6 21 4 0 1 18 4 2 0 0 100

90 Mollusca 80 Crustacea 70 Insecta Fish 60 Other

40 IRI Percent IRI

0 <40 50 70 90 >100 <40 50 70 90 >100 <40 50 70 90 >100 <40 50 70 90 >100 Mar/Apr May/Jun Jul/Aug Sep/Oct

Figure 56. Index of relative importance (IRI) values of major dietary groups consumed by yellow perch, Perca flavescens , collected in short duration/mixed gear samples at two sampling transects, Fourmile (FM), and Westside (WS), Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. IRI values normalized to 100% for each size class-season category. Size class values are midpoints of 20mm standard length classes. Numbers at tops of bars indicate total number of gastrointestinal tracts examined.

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150 fish from short duration/mixed gear samples than for fish from overnight trap net sets.

During Jul/Aug the proportional importance of the “other” category (in speckled dace,

“other” is comprised of mollusks, arachnids, rocks and vegetation) was greater across speckled dace size classes in overnight trap net samples than in short duration/mixed gear samples.

Across seasons, diptera larvae (specifically chironomid and simuliid larvae) were the most important seasonal insect prey for nearly all size classes of speckled dace in both overnight trap net and short duration/mixed gear samples (Figures 46, 52). In both gear types, simuliid larvae were consumed only during March – June, while chironomid larvae were consumed during all months. The relative importance of these two dipteran taxa in the speckled dace diet did differ, however. Simuliid larvae were proportionally more important in the diets of speckled dace captured in short duration/mixed gear samples (Figure 52). In both gear types, the diversity of insect prey was greatest during

March – June, and decreased during subsequent months. The relative importances of other insect taxa in the speckled dace diet (Coleoptera, Ephemeroptera and Trichoptera) were generally low in both gear types. Trichoptera and Ephemeroptera were, for the most part, slightly more important foods for speckled dace captured in overnight trap net samples. Coleoptera were slightly more important foods for speckled dace in short duration/mixed gear samples.

The seasonal diets of fathead minnow from short duration/mixed gear samples

(Figure 53) versus overnight trap net samples (Figure 47) were very different. Only five

151 fathead minnows (all under 40mm SL) were captured in short duration/mixed gear samples during March and April 2005 and 2006. All gastrointestinal tracts from these fathead minnows contained cladocerans. One fathead minnow had also ingested two small chironomid larvae. During March/April, the “gorp” and “other” categories (in fathead minnow, “other” is comprised of unidentifiable matter) were absent from the gastrointestinal tracts of short duration/mixed gear fathead minnow samples. In contrast,

“gorp” was the single most important food category consumed by fathead minnow less than 40mm SL captured in overnight trap nets during March/April.

During May/June, insects were the most important food category consumed by four of the five size classes of fathead minnow in short duration/mixed gear samples.

Only one fathead minnow between 46 and 49mm SL was available for diet analysis during May/June and it contained only “gorp”. Of the insect prey consumed by fathead minnow during May/June, chironomid larvae were the most important prey for fish between 40 and 46mm SL. Simuliid larvae were the most important food item for fathead minnow over 49mm SL. Crustaceans (cladocerans and copepods) were not important foods for fathead minnow greater than 43mm SL. The most important crustacean prey found in fathead minnow less than 43mm SL was unidentifiable crushed crustaceans, followed by cladocerans. Copepods and ostracods were the least important crustacean prey consumed by fathead minnow during May/June. By contrast, crustaceans and (or) “gorp” were the most important food items in the diet of all size classes of fathead minnow captured in overnight trap net samples during May/June.

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Although insects were consumed by all size classes of fathead minnow in overnight trap net samples, they ranked low in importance.

During July – October, “gorp” replaced insects as the most important food category consumed by fathead minnow over 47mm SL in the short duration/mixed gear samples. Crustaceans (cladocerans) were more important than “gorp” in the diet of fathead minnow between 40 and 43mm SL during July/August. “Gorp” was the most important food item for fathead minnow under 40mm SL during September/October; crustaceans (copepods) were the next most important. In fathead minnow over 40mm SL

“gorp” was the only food category observed during September/October. In contrast, in overnight trap net samples taken during July – October, crustaceans were the single most important food category (especially during September/October) for all but three seasonal size classes of fathead minnow. In overnight trap net samples, insects were the most important food for fathead minnow between 40 and 43mm SL. “Gorp” was the most important food for fathead minnow over 49 mm SL during July/August and individuals between 40 and 43mm SL during September/October.

Overall, both slender sculpin and yellow perch were seasonally patchy and low in abundance in short duration/mixed gear samples (Figures 54, 56). All ten slender sculpin captured in short duration/mixed gear samples were less than 70mm SL. The diets of slender sculpin, less than 70mm SL, in both overnight and short duration trap net samples taken between March and August were similar (Figures 48, 54). In both trap net and short duration/mixed gear samples, insects were the most important major dietary group

153 consumed by slender sculpin, less than 70mm SL. However, the relative importance of specific insect orders differed somewhat between the two sample types. Chironomidae,

Coleoptera, Trichoptera and Ephemeroptera were important foods for slender sculpin, less than 60mm SL, captured in overnight trap nets (Figure 49). In short duration/mixed gear samples, Chironomidae, Coleoptera and Trichoptera were the only insect orders consumed (Figure 56). All slender sculpin gastrointestinal tracts from short duration/mixed gear samples contained chironomid larvae (Figure 55). During most months, chironomid larvae were the single most important food item consumed. During

March/April, trichopteran larvae were the most important food for the only slender sculpin over 40mm SL examined. During May/June, both size classes of slender sculpin examined fed upon coleopteran larvae. Crustaceans (cladocerans and copepods) were seasonally important foods for slender sculpin, less than 40mm SL, captured in both sampling gears. Slender sculpin gastrointestinal tracts from short duration/mixed gear samples did not contain fish which, in overnight trap net samples, were moderately important foods for larger slender sculpin.

The yellow perch diet appeared similar in both the overnight trap net and short duration/mixed gear samples. One yellow perch, greater than 80mm SL was captured in the short duration/mixed gear samples and its stomach contained only fish. This yellow perch was captured during July/August, during which fish were at least marginally important prey for all four size classes of yellow perch examined from short duration/mixed gear samples. Fish were not found in short duration/mixed gear yellow

154 perch stomachs during September/October. Yellow perch, less than 60mm SL, fed primarily upon crustaceans and insects. During May/June and September/October crustaceans (primarily copepods) were the most important food category for yellow perch under 40mm SL. During July/August, however, insects (primarily chironomid larvae) were more important. Odonata, Ephemeroptera and Hemiptera were the most important insect orders consumed by yellow perch between 40 and 60mm SL during July/August.

During September/October, trichopteran larvae were the most important food for yellow perch between 40 and 60mm SL. Hemipterans, followed by snails, were the most important foods for yellow perch between 60 and 80mm SL.

Dietary overlap (S 10 ) between speckled dace and fathead minnow captured in overnight trap net sets was not significant at either low or high taxonomic resolutions

(Figures 57, 58). Using major dietary categories (Figure 57), seasonal S10 values between small speckled dace and fathead minnow ranged from 0.23 to 0.35. S10 values between large fish ranged from 0.05 to 0.19. Using higher taxonomic resolution (Figure 58), S 10 values between small speckled dace and fathead minnow ranged from 0.23 to 0.38. S10 values between large fish ranged from 0.00 to 0.27. At both taxa resolutions, dietary overlap between small fish followed slightly different seasonal trends. Using major dietary categories, dietary overlap between small fish was highest during March/April, decreased during May/June and July/August, and increased slightly during

September/October (Figure 57). When prey taxa were not lumped, dietary overlap between small fish changed little during March – August, but increased during

155

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0.9

0.8

0.7

0.6 SL Size Class (mm) Small <50 0.5 Large >=50

0.4 Diet Overlap (S10) DietOverlap

0.3

0.2

0.1

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Mar/Apr May/Jun Jul/Aug Sep/Oct

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Figure 57. Seasonal size specific dietary overlap values (S 10 ) between speckled dace and fathead minnow captured in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. This analysis uses low taxonomic resolution (%IRI values of the five major dietary groups). S10 values ≥ 0.6 show significant dietary overlap between the two fish species.

156

1.0

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Figure 58. Seasonal size specific dietary overlap values (S 10 ) between speckled dace and fathead minnow captured in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. This analysis uses a high level of taxon resolution (%IRI values of 27 prey groups). S 10 values ≥ 0.6 show significant dietary overlap between the two fish species.

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September/October (Figure58). The seasonal trend in dietary overlap between large speckled dace and fathead minnow was similar at both taxonomic resolutions. It was low in March/April, increased during May/June and decreased again during July – October at both taxon resolutions.

Seasonal %IRI of prey consumed by small and large speckled dace and fathead minnow provide insight into the seasonal dietary overlap trends and are provided in

Figures 59 and 60. One important overall pattern is that, for both large and small speckled dace, the seasonal %IRIof insects always remaines high, while %IRI of the most important foods for fathead minnow (crustaceans and “gorp”) vary both with season and sizeclass. This pattern was obvious at both taxonomic resolutions. When %IRI is calculated using major prey categories, the %IRI of crustacean and insect categories in the diet of small speckled dace and fathead minnow were more similar during

March/April than during other months (Figure 59). At the lowest taxonomic resolution, dietary overlap was most elevated during March/April. Conversley, when %IRI was calculated using specific prey taxa, differences in the %IRI of specific crustacean and insect taxa in the diet of the two fish became evident (Figure 60). Small speckled dace were principally feeding upon chironomid larvae and oligochaetes, and consuming few cladocerans and copepods. During the same period the most important foods for small fathead minnow were copepods, cladocerans and “gorp” (Figure 60). At high resolution, diet overlap between small individuals of these two species was highest during

September/October, when cladocerans and “gorp” were consumed by both species. Diet

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March/April July/August 100 dace LARGE 100 dace LARGE 90 fathead 90 fathead 80 80 70 70 60 60 50 50 40 40 30 30 20 20 10 10 0 0 100 SMALL 100 SMALL 90 90 % IRI % IRI % 80 80 70 70 60 60 50 50 40 40 30 30 20 20 10 10 0 0

Annelida Crustacea Insecta Gorp Other Annelida Crustacea Insecta Gorp Other Prey Prey

May/June September/October 100 dace LARGE 100 dace LARGE 90 fathead 90 fathead 80 80 70 70 60 60 50 50 40 40 30 30 20 20 10 10 0 0 100 SMALL 100 SMALL 90 90 % IRI % IRI % 80 80 70 70 60 60 50 50 40 40 30 30 20 20 10 10 0 0

Annelida Crustacea Insecta Gorp Other Annelida Crustacea Insecta Gorp Other Prey Prey

Figure 59. Seasonal %IRI of major dietary groups consumed by small (< 50mm SL) and large ( ≥ 50mm SL) speckled dace and fathead minnow. Fish were captured in overnight trap nets set in lower Fourmile Creek, Upper Klamath Lake, Oregon, during March – October 2005 and March – September 2006.

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March/April July/August 90 dace LARGE 90 dace LARGE 80 fathead 80 fathead 70 70 60 60 50 50 40 40 30 30 20 20 10 10 0 0 90 SMALL 90 SMALL 80 80 % IRI % 70 IRI % 70 60 60 50 50 40 40 30 30 20 20 10 10 0 0 Gorp Gorp Rocks Rocks Bivalvia Bivalvia Odonata Odonata Mollusca Mollusca Copepoda Copepoda Ostracoda Crustacea Ostracoda Crustacea Cladocera Cladocera Nematoda Vegetation Nematoda Vegetation Hemiptera Hemiptera Trematoda Trematoda Coleoptera Coleoptera Amphipoda Amphipoda Gastropoda Gastropoda Lepidoptera Trichoptera Lepidoptera Trichoptera Unidentified Unidentified Hydrachnida Hydrachnida Oligochaetae Oligochaetae Conchostraca Conchostraca Insecta (misc) Insecta (misc) Insecta Diptera (other) Diptera (other) Diptera Ephemeroptera Ephemeroptera Simuliidae (larvae) Simuliidae (larvae) Simuliidae Chironomidae (larvae) Chironomidae (larvae) Chironomidae May/June September/October 90 90 dace LARGE dace LARGE 80 fathead 80 fathead 70 70 60 60 50 50 40 40 30 30 20 20 10 10 0 0 90 SMALL 90 SMALL 80 80 % IRI % 70 IRI % 70 60 60 50 50 40 40 30 30 20 20 10 10 0 0 Gorp Gorp Rocks Rocks Bivalvia Bivalvia Odonata Odonata Mollusca Mollusca Copepoda Copepoda Ostracoda Crustacea Ostracoda Crustacea Nematoda Vegetation Nematoda Vegetation Cladocera Cladocera Hemiptera Hemiptera Trematoda Trematoda Coleoptera Coleoptera Amphipoda Amphipoda Lepidoptera Trichoptera Lepidoptera Trichoptera Gastropoda Gastropoda Unidentified Unidentified Hydrachnida Hydrachnida Oligochaetae Oligochaetae Conchostraca Conchostraca Insecta (misc) Insecta (misc) Insecta Diptera (other) Diptera (other) Diptera Ephemeroptera Ephemeroptera Simuliidae (larvae) Simuliidae (larvae) Simuliidae Chironomidae (larvae) Chironomidae (larvae) Chironomidae Prey Prey Figure 60. Seasonal %IRI of 27 prey groups consumed by small (< 50mm SL) and large (≥ 50mm SL) speckled dace and fathead minnow. Fish were captured in overnight trap nets set in lower Fourmile Creek, Upper Klamath Lake, Oregon, during March – October 2005 and March – September 2006.

160 overlap between large fish was highest during May/June. ”Gorp” and annelids were not important food items for large fish during these months. In May/June cladocerans were the most important food for large fathead minnow, while chironomid larvae were the most important food for large speckled dace.

DISCUSSION

Changes in environmental characteristics between each monthly sampling were drastic at both the Fourmile and Westside transects during both sampling seasons. The

Fourmile transect was continuously wetted across its length during March through

August in both 2005 and 2006. Shallow intermittent pools remained from September through October. The Westside transect was wetted from March through July, but it quickly dried up and reverted to a meadow after surface flow became intermittent. The close proximity of the Fourmile transect to Harriman Springs and the Klamath Lake flood plain result in its being wetted during more months and having more stable water temperature, dissolved oxygen, and pH values than the Westside transect (Figures 6 –

13). Small springs located immediately upstream of the Rocky Point Road Bridge contributed visible flow to Fourmile Creek from March through May (Figure 2). Visible flow from these springs was not observed during subsequent months; however, the flow of the springs may have been reduced to imperceptible levels as ground water pressure dropped. In contrast, water coverage at the Westside transect was more ephemeral and dependent upon precipitation and snowmelt, as most outflow from Fourmile Lake is diverted or delayed. Underground springs may contribute water upstream of the

Westside transect. However, none was observed within that transect.

The timing of seasonal peak flows observed during both 2005 and 2006 are typical of this drainage, at least under its current hydrologic management. During both study years surface discharge (and wetted habitat) increased during March and April,

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162 peaked during May and quickly dropped during June and July. This pattern closely follows the Fourmile Creek hydrograph published by the United States Department of

Agriculture (1996). Before the damming of the outflow of Fourmile Lake in 1922, the magnitude and duration of flows resulting from snowmelt were undoubtedly greater

(United States Department of Agriculture 1996). Much of the upper drainage area above

Fourmile Lake consists of exposed bedrock and impervious material. Precipitation and snowmelt, instead of infiltrating these surfaces and flowing into subsurface aquifers, remains on the surface and flows into Fourmile Lake. Before the dam was constructed

(which effectively added 9m to the lake’s elevation) recharge of the lake by surface runoff was probably rapid and occurred during early winter rain storms, while snowmelt contributed water from spring into the fall (United States Department of Agriculture

1996). Spillover from Fourmile Lake into Fourmile Creek was thus probably perennial, with high flow pulses during snowmelt. Currently, rains and snowmelt must fill an additional 9m of Fourmile Lake. Spillover from winter rains and late snowmelt, which historically would have flowed into Fourmile Creek, are instead captured and diverted.

This has resulted in intermittent flow in upper Fourmile Creek. As a result, before and after peak spring snowmelt, discharge in lower Fourmile Creek is currently dependent upon secondary tributary and spring input instead of the historic outflow from Fourmile

Lake. Surface flow in lower Fourmile Creek was probably historically intermittent because its channel is both flat and contains porous substrates (United States Department of Agriculture 1996). However, outflow from Fourmile Lake would likely have caused earlier resumption of flow in winter, higher flow magnitude and greater flow persistence

163 into late summer than currently occurs. Data from this study confirm that these stream conditions and resultant aquatic habitat would have been important to native fish such as speckled dace, slender sculpin, blue chub and red band trout, as well as their macroinvertebrate prey.

The results of this two-year study show that lower Fourmile Creek is home to a diverse and abundant invertebrate fauna when it is wetted. Crustaceans and aquatic insects dominated the overall pleustonic, planktonic and nektonic macroinvertebrate community in lower Fourmile Creek. These two major taxa had the highest percent composition and frequency of occurrence in both light trap and plankton tow samples

(Tables 5, 6). Using the same two measures, annelids dominated the sub-surface benthic macroinvertebrate community (Table 27). Cladocerans, copepods and ostracods were the dominant crustaceans at both the Fourmile and Westside transects. Of these three taxa, cladocerans and copepods were the most abundant and thus most influenced monthly crustacean CPUE values (Tables 17 – 20; Figure 17; Appendices D – F, AA – AH).

These two crustacean taxa appeared to possess two seasonal peaks in abundance: one in late spring/early summer and one during the fall. Cladocerans and most copepods possess physiological and life history traits that enable them to survive and flourish in the highly variable habitats that exist in lower Fourmile Creek. For example, most genera within these orders are eurythermal, many are capable of rapid population increases through parthenogenetic reproduction, and many genera produce resting eggs which may withstand both desiccation and freezing (Pennak 1989). Such characteristics allow these taxa to persist and thrive even in the Westside pasture site, which is flooded for only a

164 few months during spring and early summer but then quickly dries up. Other crustaceans, including conchostracans, and amphipods were less abundant in samples.

The aquatic habitat in lower Fourmile Creek may be too variable to support large amphipod and conchostracan populations. Amphipods, for example, typically thrive in consistently cool and permanent water (Covich and Thorp 1991). Such habitats do not exist in the low-gradient portion of lower Fourmile Creek upstream of Harriman Springs.

Once flow became intermittent, some shallow pools remained. However, they experience large diel fluctuations in water temperatures. Mulligan et al. (2009) found that cladocerans and copepods were the dominant crustaceans in the Upper Klamath Marsh

Creeks.

Like the crustacean community, the insect community in lower Fourmile Creek was both abundant and diverse. In general, insect abundance (in terms of CPUE) was lower during spring and increased during summer and fall as water levels decreased.

Dipterans, particularly chironomids, dominated the overall and monthly insect catch and persisted in samples across all months. The abundance of chironomids in lower Fourmile

Creek is not surprising because they are often abundant in freshwater environments that experience daily or seasonal fluctuations of temperature, dissolved oxygen and water coverage. In a Californian intermittent stream, for example, chironomid larvae accounted for 43% of individual invertebrates captured and were found in all samples from June through November (Rosario and Resh 2000). Chironimid larvae also tended to dominate the aquatic insect community in habitats adjacent to Fourmile Creek, including Upper

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Klamath Lake and the Upper Klamath Marsh Creeks (Bonnell and Mote 1942, Mulligan at al. 2009).

In general, the CPUE of hemipteran and coleopteran taxa also tended to be lower during spring and increased as water levels decreased during the summer, especially at the Westside transect (Appendices AN – AV). Individuals within transects undoubtedly became concentrated as water became scarce. In addition, because most taxa within these orders are predators, the decreasing water levels in lower Fourmile Creek provide desirable habitat that might actually have recruited adult individuals from surrounding waters. Mobile prey (including insects, crustaceans, fish and amphibians) were concentrated and thus potentially easier to catch as water levels decreased and intermittent pools formed. In addition to abundant food, juvenile hemipterans and coleopterans potentially benefited from the higher water temperatures during summer because of faster growth rates. Furthermore, since adult stages of these insects utilize atmospheric air and most can fly, individuals were able to withstand drying and could disperse to other wetted habitats when water disappeared. Refuge habitats might include intermittent pools downstream of the Westside transect and, especially during late fall,

Harriman Springs and Pelican Bay. Stanley et al. (1994) found that winged hemipterans and coleopterans dominated the insect community in an Arizona stream reach as it dried.

They attributed this dominance both to concentration of individuals within sites as the stream dried, and to colonization by individuals from other nearby habitats.

Some insects were most abundant during spring and early summer when transect margins were flooded and visible surface flow was high. These include collembolans and

166 simuliids. Collembolans probably are ubiquitous in the benthos of lower Fourmile Creek valley and in all of its surrounding moist habitats. They may have been present in soils and debris and subsequently washed into the water column as these moist habitats were inundated during spring snowmelt. While true aquatic springtail genera exist, for the most part they inhabit moist riparian areas (Merritt and Cummins 1996). During May,

2005, for example, I observed dense aggregations comprised of thousands of individual collembolans were observed floating in shallow puddles located alongside a road bordering the Westside transect. Collembolans possess an extremely hydrophobic exoskeleton and thus tend to float on the surface film when present in the water column.

Because they tend to float, they are less likely to enter light traps, whose entrances are subsurface. Consequently most were captured in plankton tows.

A total of 25 and 95 simuliids (black flies) were captured in light trap and plankton samples, respectively. Black flies were routinely observed in large numbers while setting trap nets at the Westside transect, usually while attached to submerged vegetation, but were largely absent from the Fourmile transect (Tables 25, 26). When dislodged from the vegetation, they affixed themselves to the next available surface, including the trap net or the sampler. This affinity for structure limits the time simuliid larvae drift in the water column and potentially reduced their exposure to light traps and plankton tows used in this study. It probably explains why few black flies were captured or observed in the Fourmile transect. The channel within the Fourmile transect was dominated by smaller-sized substrates (ranging from clays to gravel) which are unsuitable attachment sites for black flies. The vegetation that did occur in this transect

167 was predominantly situated along the channel margin, and was not exposed to the laminar flow preferred by black fly larvae. At the Westside transect, however, midchannel vegetation was abundant, and ideally positioned for simuliid feeding until flows decreased after May. Merritt et al. (1982) suggested that the availability of suitable substrate was a major factor limiting abundance of black fly larvae in Mud Creek,

Michigan. In Mud creek, attachment sites for simuliid larvae were restricted to submerged vegetation because soft sediments dominated its benthos.

Both overall and monthly mean CPUE’s of most crustacean and insect taxa sampled in light traps were higher at the more heavily vegetated, but more ephemeral

Westside transect than at the Fourmile transect (Tables 17 – 26, Appendices AA – AZ).

From March through August, vegetative cover in the channel of the Fourmile transect increased from very low to moderate levels. The channel margin at the Westside transect possessed moderate to high vegetative cover during all sampling months. Vegetation is often associated with higher abundances and species richness of invertebrate taxa. Light traps set adjacent to heavy levels of vegetation had higher invertebrate CPUEs than those set in sparsely vegetated or bare areas in the Upper Klamath National Wildlife Refuge

Marsh (Mulligan et al. 2009).

When overall numbers and abundance (expressed as CPUE) of fish from both transects were considered, native species dominated the fish assemblage in lower

Fourmile Creek. Not only did they account for the greatest proportion of the total and transect-specific catches (Table 29), but they also had the greatest species richness

(Tables 30, 31). These patterns did not persist across months, however. Seasonally, the

168 fish assemblage inhabiting lower Fourmile Creek transitioned from one dominated by native fish to one dominated by non-native fish (Figure 19, Appendix BA). This shift coincided with, and was likely highly influenced by, the predictable seasonal change in wetted habitat. Although overall fish abundance remained low from March through June, the abundance of native fish was usually higher than that of non-native fish. During this period fish were presumably dispersed in flooded channel and marginal habitats up to at least the flooded Westside pasture. The subsequent increase in abundance of both native and non-native fish during August resulted from both the concentration of fish as habitat dried and to the recruitment of YOY and older cohorts into the trap net catch, primarily speckled dace and fathead minnow, which are discussed below. By September, the abundance of non-native species exceeded that of native species.

This transition toward a non-native fish assemblage occurred at both transects but species richness and abundance were lower at the Westside transect than at the Fourmile transect (Tables 33 – 36, Figures 20 – 22). Trends in species diversity and richness also differed between the two transects. Fish diversity and evenness peaked during May of

2005 and June of 2006 at the Fourmile transect. Both were lowest during July, when speckled dace made up 80% of the trap net catch. Diversity and evenness at the Westside transect were initially low because only speckled dace were captured during April 2005 and March 2006. During subsequent months, fish diversity and evenness increased as other species became more abundant in trap net samples. These trends were likely influenced by the close proximity of the Fourmile transect to (and its longer connectivity with) permanent water. This allowed fish access to more refugia during stream drying

169 and provided a source of colonists. The persistence of a fish assemblage in intermittently wetted habitats depends upon a number of factors, including both the ability of fish to find suitable refuge as wetted habitats shrink and to colonize habitats as they are rewetted (Magoulick and Kobza 2003, Moyle et al. 2007). Seasonal loss of surface water prohibits permanent year-round utilization of the Westside transect by fish. Once

Fourmile Creek reaches the valley floor, it flows across relatively flat alluvial till and has little pool development. Consequently, its channel drains quickly and offers little refugia during and after drying. During my study, fish that had not yet moved downstream of the

Westside Road bridge between July and August would have succumbed to desiccation, poor water conditions or predation. Reestablishment of the fish community in the

Westside transect after it is rewetted thus depends primarily upon upstream immigration of fish from downstream habitats. Only salmonids (all non-native with the exception of stocked redband/rainbow trout) are known to persist in Fourmile Lake and the upper reaches of Fourmile Lake.

As the water receded in the Fourmile transect, fish may have taken refuge in the permanent water downstream of Harriman Springs or in the few remaining shallow intermittent pools located downstream of the Rocky Point Road bridge. Pole seining at one such pool in October 2006 yielded hundreds of speckled dace, fathead minnow and juvenile yellow perch and two juvenile slender sculpin. The downstream-most extent of this pool was located midway between the upper and lower Fourmile sites. The pool extended about 40m upstream to the upper site. Other possible refuge habitat exists in the form of deeper permanent pools located immediately upstream of the Rocky Point

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Road Bridge, between the Fourmile and Westside transects. Pole seining in a deep permanent pool located just upstream this bridge during August, September and October, of both sampling years, yielded hundreds of cyprinids, yellow perch and brown bullhead.

While native cyprinids, including tui chub, blue chub and speckled dace, were captured in this pool, non-native fathead minnow were by far the most abundant cyprinid. Adult and juvenile brown bullhead and juvenile yellow perch were also abundant.

The high numbers of non-native fathead minnow, yellow perch and brown bullhead in these intermittent pools suggest that, once surface flows diminish, these habitats might benefit non-native fish over native fish. Non-native piscivorous yellow perch and brown bullhead were probably preying upon native fish, or at the least, competing for space, food and oxygen. By the following spring, however, native fish again dominated the fish assemblage. Restoration of stream flow in late fall, in conjunction with cold and inhospitable conditions during the winter, probably contributed to this resurgence of the native fish community. Water quality parameters were not measured during the winter, so their effect on year-round resident fish is not known.

From late December to late February, however, the creek freezes over and flows remain low. According to Geiger et al. (2000), water temperatures just downstream of the

Westside Road crossing ranged from 0.08˚C to 2.75˚C and dissolved oxygen ranged from

1.0 mg/l to 8.9 mg/l during winter. If these values are representative of typical conditions, temperature and dissolved oxygen may inhibit survival of fish overwintering in pools. Even those fish utilizing pools with high underwater spring input, and thus

171 relatively constant temperature, may succumb to low oxygen levels if ice prevents atmospheric exchange.

The presence of large blue chub and tui chub in the Westside upper and flooded pasture sites during May is notable as it shows the potential importance of this transect for larger native fish. These fish most likely swam upstream from the Fourmile transect because neither chub species is present in Fourmile Lake. The occurrence of these fish at the Fourmile transect is not surprising considering this transect’s proximity to and interconnectivity with flooded habitats around Pelican Bay. To reach the flooded pasture adjacent to the Westside transect, however, fish must navigate at least one km of intermittently braided stream channel and pass under two road crossings. This suggests that these fish may be making a directed upstream movement to this seasonally available habitat. Tui chub and blue chub could undertake this upstream migration to take advantage of the abundant food resources available in the Westside transect. Cladocerans and dipteran larvae are important foods for both tui chub and blue chub (Bird 1975,

Mulligan et al. 2009). Cladocerans and dipteran larvae, as well as other potential prey taxa, were abundant during and after June at the Westside transect (Appendices S – AZ).

Additionally, tui chub may also spawn in the Westside transect. Two YOY tui chub were captured in light traps at the upper Westside site during June 2006, which suggest that tui chub are spawning either there or in an adjacent area. Tui chub spawn over heavy vegetation during June and July in East Lake, Oregon, and the larvae remain in the vegetation (Bird 1975). Both blue and tui chub occur in warm, low gradient rivers and streams (Contreras 1973, Moyle 2002). In April 1973, for example, Contreras (1973)

172 found that these two chub species made up almost 75 percent of the total fish catch in the

Lost River. The ecology of these two native cyprinids has not been well studied in Upper

Klamath Lake, or its tributaries and floodplains. Further investigation into the extent to which these two species utilize this vast, but temporarily flooded, habitat should be conducted.

While reproduction of speckled dace, fathead minnow, and slender sculpin in

Fourmile Creek was not directly observed, reproductive timing can be inferred from the presence of fish with mature gonads (high GSI values), individuals with pronounced secondary sexual characteristics and by the temporal pattern of juvenile fish size and abundance in trap net and light trap samples. Spawning of yellow perch sin lower

Fourmile Creek was further confirmed by the presence of their distinct egg strands.

Speckled dace spawning appears to be mildly protracted in Fourmile Creek, but it coincides with, and is likely correlated with peak spring flows. In Fourmile Creek, GSI values for female speckled dace peaked in April and were low after May (Figures 23, 24).

These GSI values, together with the red spawning coloration observed on speckled dace of both sexes from both transects, indicate that speckled dace spawn between March

(perhaps earlier) and May at the Fourmile and Westside transects. Other populations of speckled dace have similar reproductive timing. John (1963) observed speckled dace spawning in May and hatching in June in an Arizona stream. Using egg diameter,

Jhingran (1948) determined that speckled dace in the upper Trinity River, California had a protracted spawning season which peaked around late June. Egg diameters ranged from

0.90 to 1.82mm from May into July, but were 0.18 to 0.90mm for the remainder of the

173 year. Jhingran (1948) concluded that since ovaries ripened from the posterior end, females probably spawn repeatedly, resulting in an extended reproductive period. In

Fourmile Creek, as well as in both the Arizona and the California studies, speckled dace spawning also coincided with high stream flows.

In other drainages, speckled dace have been observed nesting in gravel and rocks free of silt, both with and without algae and plant cover (John 1963). Soft mud and peat dominate most of the benthos of Pelican Bay and the Upper Klamath Marsh. Mulligan et al. (2009) captured few speckled dace over these substrates despite significant sampling effort. In contrast, Fourmile Creek has a larger proportion of hard substrates. The fine sand, gravel and cobbles comprising much of the channel bottom in the Fourmile transect offer abundant spawning substrate for speckled dace and other fish that require hard spawning substrate. Although vegetation covers most of the channel area at the Westside transect throughout the year, the bottom is largely sand and gravel. Thus, bare areas among submerged plants and along the flooded margin offer suitable spawning habitat for speckled dace from March through May at the Westside transect.

The timing of fathead minnow reproduction in Fourmile Creek is more protracted and occurs later than that of speckled dace, as inferred from GSI values. Female GSI values ranged from 10 to 25 from May into August (Figures 25, 26). Males possessed tubercles, enlarged dorsal pads and other secondary sexual characteristics typically associated with spawning in this species from May through August. Fathead minnow in

Ohio also have a protracted spawning season and were observed to hatch from May through August (Trautman 1981). This highly fecund fish appears to reproduce first at

174 the Westside transect and the upper Fourmile site and then at the Fourmile lower site.

Fathead minnow initiate spawning as water temperatures approach 18˚C (Dobie et al.

1956). The threshold spawning temperature of 18˚C was reached first at the warmer

Westside sites and the margin of the upper Fourmile site between May and June (Figures

6, 7). Water in and adjacent to these sites tended to be both shallow and heavily vegetated which facilitated quicker warming and also provided abundant spawning substrates. Fathead minnow have been known to lay eggs on the undersides of objects, including woody debris, fence posts, rocks and submerged plants, which are then guarded by the males (Markus 1934). Consequently, fathead minnow might utilize the rocks, woody debris and submerged vegetation in both the Fourmile and Westside transects.

Using only length frequency, differentiation between YOY speckled dace and fathead minnow emergence timing proved to be challenging (Appendices BP – BR).

When combined with GSI data, however, temporal patterns became more clear. In

Fourmile Creek, speckled dace captured in light traps during March through May in 2005 were between 30 and 50mm SL (Appendices BP – BR). Presumably these represented one year old and older speckled dace. YOY cyprinids first appeared in light trap samples during June. This June recruitment occurred after speckled dace GSIs had decreased, and as fathead minnow GSIs were increasing. This indicated that fathead minnow were initiating spawning. Thus the early cyprinids were presumed to be speckled dace. The smaller YOY cyprinids captured in monthly samples after June include an increasing proportion of fathead minnow. Based upon length frequency data, Jhingran (1948) calculated that one year after hatching, speckled dace grew to about 37mm in California’s

175

Trinity River. He also noted that the abundance of YOY speckled dace in the Trinity

River was highest during July, a month after peak egg maturation. Fathead minnow grow rapidly, tend to be short lived and may even spawn during their first year. In Ohio YOY fathead minnow ranged from 13 to 64 mm TL in August (Trautman 1981).

Slender sculpin in lower Fourmile Creek probably spawn in late summer and fall.

In this study GSI values peaked during August and September; during other sample months GSI values remained low (Figures 27, 28). Slender sculpin are thought to initiate spawning in the fall (Robins and Miller 1957). However, Bentivoglio (1998) reported capturing slender sculpin with ripe ovaries during both April and September at the

Klamath Fish Hatchery on Crooked Creek, Oregon, where water temperature is consistently 8˚C. Bentivoglio hypothesized that the constant temperature allowed this population of slender sculpin to spawn continuously. Such is the case with Cottus pygmaeus , which inhabits small spring habitats in Alabama (Williams 1968). In contrast, temperatures in Fourmile Creek are not constant (Figures 6, 7). The reproductive habits of slender sculpin are not well documented. However, its closest relative, the rough sculpin, Cottus asperrimus , nests over substrates ranging from sand to cobble (Daniels

1987). The fine sand, gravel and small cobbles comprising much of the channel bottom in the Fourmile transect potentially offer abundant spawning substrate for slender sculpin.

Fourmile Creek appears to be an important spawning and nursery area for cottids.

The presence of large numbers of advanced cottid larvae in March, followed by a cohort of smaller, newly hatched cottid larvae in April, is evidence that these fish spawn at different times in Fourmile Creek (Appendices BS – BU). Cottid larvae captured during

176

March (7 – 13mm SL) were slender sculpin. Characteristics such as pigment and fin ray development were more developed in these larvae than in the newly hatched cottid larvae. Water temperatures between October and March would have been cold and larval development and growth correspondingly slow. Early larvae captured after April (7 –

9mm SL) were either Klamath Lake sculpin, or marbled sculpin, which spawn in the late winter or spring (Robins and Miller 1957, Daniels 1987). Cottid reproduction and early life history is not well documented in other Upper Klamath Lake habitats and deserves further study. In Upper Klamath Marsh creeks, juvenile and larval sculpin were infrequently captured in light traps (Dr. Helen Mulligan, personal communication, 2009).

GSI values and by the presence of eggs in submerged vegetation suggest that yellow perch spawn in early spring (March) in Fourmile Creek. GSIs in large male and female yellow perch were high during March, and (in males) during September and

October (Figures 29, 30). From April to August, GSI values of all sampled size classes were low. The patterns of yellow perch gonad development observed in Fourmile Creek resemble the patterns found by Mulligan et al. (2009) in the Upper Klamath Marsh. Here they found that large, reproductive yellow perch utilized Upper Klamath Marsh habitats early in the spring. In Upper Klamath Marsh, GSIs of the largest size classes of yellow perch were highest in March and April. GSIs of virtually all size classes, regardless of sex, were below one from May through August. In September and October, GSIs of larger size classes of female and most size classes of male Upper Klamath Marsh yellow perch increased. Yellow perch release sheets of adhesive eggs over submerged vegetation (Becker 1983). These very distinct sheets of eggs were found entangled in

177 submerged vegetation bordering the channel at the Fourmile transect during March. The submerged vegetation, situated along the flooded channel margin of the Fourmile transect and most of the Westside transect, affords yellow perch with abundant spawning substrate.

Overall (CF1) and somatic (CF3) condition factors of male speckled dace remained similar across seasons, while those of female speckled dace fluctuated (Figures

35, 36). It is possible that males, because they have smaller maximum sizes and have lower reproductive investments in terms of gonad mass than females, were able to maintain more stable body weights across seasons. Mature male speckled dace could invest time and energy into somatic growth, metabolism and predator avoidance, but did not have to make the significant investments in gonad maturation that females did.

Overall condition of most size classes of female speckled dace were highest during

March through May, lower during July through September and increased again in

October. The peak in overall female condition during spring can be attributed mainly to gonad maturation and recrudescence because somatic condition values remained low during these peak spawning months. Female speckled dace were mobilizing their lipid and protein reserves to satisfy both basic metabolic and reproductive needs. This mobilization lowered muscle mass in mature individuals. Declining somatic condition and energy reserves around spawning time is common and well documented in small temperate fish, including the three-spined stickleback, Gasterosteus aculeatus , and

blacknose dace, Rhinichthys atratulus (Love 1970, Cunjak and Power 1986).

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After May, reproduction ceased, yet body condition of both sexes appeared to decrease between July and September. This was especially true for females. During these months, available water decreased rapidly in lower Fourmile Creek, subjecting speckled dace to fluctuating environmental conditions as well as to increased competition for food and space. One or all of these factors could have resulted in the lower body condition observed during these months. By October overall and somatic conditions values had increased, suggesting that speckled dace were able to meet basic metabolic needs and to store energy and nutrients. These reserves might be utilized both during winter, when food might be limited, and for gonad maturation in the spring.

Female and male fathead minnow were in best condition immediately prior to their reproductive season (Figures 37, 38). Female fathead minnow invested primarily in gonad maturation, at the expense of somatic condition during May through August.

During these months mean female GSI (Figures 25, 26) and overall condition values were elevated, yet female somatic condition values decreased. Males invested less in gonad growth and instead maintained higher levels of somatic condition. However, toward the end of the breeding season many males appeared to possess diminished trunk musculature and were generally thin in profile. Thus, the elevated somatic condition of sexually mature male fathead minnow in Fourmile Creek does not necessarily mean that these fish were experiencing optimal growth conditions. Instead, male fathead minnow were probably investing significant resources and energies into secondary sexual characteristics and behaviors. Secondary sexual characteristics (enlarged dorsal pads, nuptial tubercles and increased anterior robustness) were regularly observed on male

179 fathead minnow in Fourmile Creek during May – August. Males use these features to herd females into and out of their nests, to nudge females into the correct egg-laying position and to chase all small fish from the nest (Wynne-Edwards 1932). Because the development of these features increases the mass of an individual while its standard length remains virtually unchanged, the somatic condition factor increases. Given that fathead minnow reproduction is protracted in Fourmile Creek and that fathead minnow are generally fractional spawners (Herwig and Zimmer 2007), reproductive energy expenditure in both males and females would have been elevated over a prolonged period. This continued reproductive output, in conjunction with increasing levels of intraspecific and interspecific competition for space and food as habitat decreased, may account for the general decrease in male fathead minnow condition towards the conclusion of their spawning season.

Overall and somatic condition factors and hepatosomatic indices (HSI) for slender sculpin suggest that winter may be a critical time for slender sculpin, particularly reproductively mature individuals (Figures 39, 40, 43). Slender sculpin greater than

50mm SL captured during March – April were laterally compressed and generally emaciated and snake-like in appearance. Their low condition probably resulted from a combination of energy expenditure during spawning, lower feeding opportunities after spawning and unfavorable habitat conditions during late fall and winter. Unlike speckled dace, which also experienced a decrease in somatic condition as they prepared to spawn, slender sculpin probably did not have favorable forage and growth conditions as they completed spawning. During September and October the water level decreased and the

180 creek’s channel was dry over much of its length. At the same time, the invertebrate assemblage in lower Fourmile Creek was transitioning from a diverse one which included abundant benthic ephemeropteran, trichopteran and dipteran larvae to one that was increasingly dominated by hemipteran and coleopteran adults (Appendices C – R).

Larger slender sculpin feed primarily upon ephemeropteran, trichopteran and dipteran larvae (Figures 48, 49). Slender sculpin stranded in pools would have had limited foraging opportunities as benthic prey became less available. In addition, shrinking habitat probably resulted in greater competition for space and food, further reducing body condition.

The seasonal pattern of overall, somatic and Hepatosomatic condition indicate that yellow perch were in best condition during June and July (Figures 41, 42, 44).

Decreased condition during spring suggests that, like female speckled dace, sexually mature yellow perch were rebuilding energy reserves that had been expended during spawning and overwintering. During the period of intermediate water coverage (June and July) condition appeared to be greatest, suggesting habitat conditions were optimal.

These individuals may have had greater feeding success during early summer as habitat began to shrink and food became concentrated. After July, condition decreased as habitat was further constricted.

The diets of speckled dace, fathead minnow, slender sculpin and yellow perch were assessed from specimens obtained in two ways: overnight trap nets (Figures 45 –

50) and short duration/mixed gear samples (Figures 51 – 56). The latter was done to investigate whether factors such as in-trap predation and retention time affected the diet

181 of each species as determined from overnight trap net samples. Intraspecific diets of speckled dace, slender sculpin and yellow perch in overnight trap net samples and in short duration/mixed gear samples were similar. This suggests that for these three species, either in-trap feeding was not significant or foods such as insects and crustaceans were available to, and consumed by, fish in overnight trap nets. Overnight trap net samples contained greater percentages of empty gastrointestinal tracts than did short duration/mixed gear samples. This supports the former conclusion. If frequent in-trap feeding was occurring, one would expect the percentages of empty gastrointestinal tracts to be more similar between the two gear types. Fathead minnow was the one species for which the diets of individuals captured in overnight trap nets versus short duration/mixed gear samples differed. This variation in diet of fathead minnow is discussed after the discussion of the speckled dace diet.

Speckled dace in Fourmile Creek were highly insectivorous during March –

October, (Figures 45, 46). In most seasonal size class groupings, benthic insects possessed the highest %IRI values of any food group. For example in overnight trap net gastrointestinal tract samples, the %IRI values for insects were greater than 60% in all but three seasonal size classes. Individuals within each of the three seasonal size classes of speckled dace for which insects were not the most important food (fish < 40 mm and >

70 mm SL during July/August and fish < 40 mm SL during September/October) had consumed insects. However, the %IRI values of the “gorp” and/or “other” categories were higher. The diversity of benthic insects consumed by speckled dace was greater during March – June than during subsequent months. This was likely due to changes in

182 habitat and prey availability resulting from water loss. While some insects like chironomid larvae were available and consumed during all months, certain seasonal prey

(i.e. simuliid larvae) were only available during periods of higher water. During later months, fast swimming prey such as hemipterans and coleopterans increased in abundance in light trap samples, but were not important foods for speckled dace. Benthic insects have been shown to be a major component in the diets of other speckled dace populations, with detritus a seasonally important component (Jhingran 1948, Schreiber and Minckley 1981). Jhingran (1948) found that chironomids were frequently consumed by speckled dace in California’s Trinity River during December – March, but not during other months. Mayfly and stonefly nymphs were important foods during spring. Winged insects were important during summer. Filamentous algae and insect parts were important foods in the fall. Interestingly, in Fourmile Creek “gorp” (ingested detritus often dominated by diatoms) was not an especially important food for speckled dace, even as the creek dried in the fall, yet it was consumed during most months. Because

“gorp” was not generally an important food for large speckled dace, its presence in most instances may be attributed to incidental consumption and(or) to prey digestion. The presence of ingested detritus in fish diet samples does not necessarily indicate fish are deriving nutrition from it, or that fish are purposefully eating it (Gerking 1994). Dense layers of diatomaceous, fine particulate matter were observed covering aquatic vegetation and other surfaces at both the Fourmile and Westside transects. Speckled dace may have inadvertently consumed some detritus and periphyton while ingesting chironomids or other benthic prey. Additionally, “gorp” in speckled dace gastrointestinal tracts could be

183 a product of digestion. The material comprising the tubes of tube-dwelling chironomids, which were an important prey of speckled dace, appeared similar in composition to

“gorp”. Partially digested and intact chironomid larvae still inside their tubes were frequently present in speckled dace gut gastrointestinal tracts. Their presence indicates speckled dace regularly plucked sheathed individuals from substrates. According to

Merritt and Cummins (1996), chironomids consume a wide range of substances, including detritus, algae, vegetation and animals. Larval simuliids and oligochaetes also consume particulate organic matter. Digestion of such prey and their external tubes could release organic matter into the speckled dace gastrointestinal tracts.

The diet of the fathead minnow was unique among the four species examined because it contained a significant amount of “gorp”. This was also the one species for which the seasonal diets of individuals captured in overnight trap nets versus those captured in short duration/mixed gear samples obviously differed (Figure 47, 53).

“Gorp” was an important food for fathead minnow captured in both gear types. Because

“gorp” possessed high %IRI values, it is doubtful that “gorp” in fathead minnow gastrointestinal tracts was derived solely from incidental ingestion or from mastication and digestion of invertebrate prey. Across seasons, “gorp” was generally encountered in a greater percentage of gastrointestinal tracts and in greater masses than were chironomids and other insects. The key difference in diet between the two gear types was that in overnight trap net samples, the %IRI of crustaceans was also high, while in short duration/mixed gear samples the %IRI of insects was high until June, after which “gorp” became the dominant food. The reason for this diet difference is not clear. However, it is

184 likely that this species does naturally utilize all of these foods in Fourmile Creek.

Fathead minnow are primarily benthic feeders and have been shown to eat a wide range of foods including algae, insect larvae, crustaceans and silt (Coyle 1930, Held and

Peterka 1974). It is possible that “gorp” was under-represented in overnight fathead minnow gastrointestinal tract samples because it was digested and evacuated more quickly than invertebrate prey. Consequently, its %IRI in fathead minnow gastrointestinal tract samples from overnight trap nets would have been artificially depressed. One possible explanation for the high %IRI of crustaceans in overnight trap net samples versus the high %IRI of insects in short duration/mixed gear samples is diel prey behavior. Crustaceans, because they may be more vulnerable to predation at night, may have been more important foods for fathead minnow captured in overnight trap net sets. During the afternoon/evening, fathead minnow would instead have preyed upon

“gorp” and benthic insect larvae, as is evident from short duration/mixed gear samples.

As water levels dropped after June, insects may have been less available during daylight hours so “gorp” was instead consumed until crustaceans and other zooplankton once again became vulnerable to predation during the night. Schram et al. (1990) found that diel drift of crustaceans and other zooplankton in the headwaters of the Illinois River, including intermittent tributaries, was highest during the night and lowest during daylight hours.

Dietary overlap between speckled dace and fathead minnow from overnight trap net samples was not significant (Figures 57, 58). Of the four most abundant fish in this study, speckled dace are the most ecologically similar to fathead minnow. Both species

185 are locally abundant, small bodied cyprinids that are known to consume a broad spectrum of predominantly benthic foods. Because “gorp” and crustaceans were typically the most important food for fathead minnow, while insects were the most important food for speckled dace, these species remain largely trophically segregated. The fathead minnow’s diet is probably one of the factors contributing to its successful persistence in

Fourmile Creek, where both the loss of available wetted habitat and the recruitment of larval and juvenile fish after June contribute to increased fish densities. Under such conditions, fish utilizing one primary food group (i.e. insects) would potentially face greater intra-specific and inter-specific competition for food resources. In other wetland ecosystems that undergo seasonal fluctuations in habitat availability, prey density and intra-specific competition have been found to influence the consumption of detritus by fathead minnow. Herwig and Zimmer (2007) found that the consumption of detritus by adult fathead minnow in Minnesotan prairie potholes was negatively related to invertebrate abundance and positively related to adult fish density.

Slender sculpin over 40mm SL are highly insectivorous in Fourmile Creek. Their diet was high in insects and comparatively low in crustaceans during all months. Larger insects (coleopterans, ephemeropterans and trichopterans) were more important from

March – June; smaller insects including chironomids were more important from July –

October. As was the case for speckled dace, this dietary shift probably resulted from a change in available prey as water disappeared in Fourmile Creek. As water disappeared, the insect community was increasingly comprised of smaller benthic insects (e.g. chironimid larvae) and highly mobile, swimming coleopterans and hemipterans.

186

Bentivoglio (1998) conducted a dietary analysis of slender sculpin captured at the

Klamath Fish Hatchery on Crooked Creek, Oregon. Fifteen individuals of unspecified length were pooled for analysis and numbers of individuals of each prey taxa were reported. Unfortunately, no sample date is given. Insects were the most diverse dietary component consumed by slender sculpin in Crooked Creek, with Trichoptera, Diptera,

Coleoptera and Plecoptera together comprising 30% of individual prey. The most abundant individual taxon in stomach samples was amphipods ( Gammarus sp .) which, in

combination with isopods, comprised 32% of individual prey. Mollusks accounted for

10% of prey while nematodes reportedly comprised 28% of stomach contents. Slender

sculpin in Fourmile Creek consumed fewer crustaceans and more insects than did slender

sculpin in Crooked Creek. This difference in diet between the two populations probably

reflects different prey availability at the two sites. Bentivoglio (1998) described Crooked

Creek as having a constant temperature of 8˚C. This is indicative of markedly different

habitat conditions than those at Fourmile Creek. Fourmile Creek is characterized by

large seasonal and diel temperature variations. One would expect that the invertebrate

assemblage inhabiting constantly wetted, cold Crooked Creek would consequently be

different from Fourmile Creek. Amphipods and other large crustaceans, for example,

should be abundant in Crooked Creek (see macroinvertebrate discussion subsection), but

few large crustaceans (i.e. amphipods) were captured in invertebrate samples taken at the

Westside and Fourmile transects.

Yellow perch showed distinct ontogenetic and seasonal dietary patterns (Figures

50, 56). Fish were the most important prey for all yellow perch > 80 mm SL, while

187 insects and crustaceans were important prey for smaller yellow perch. Seasonal constriction of wetted habitat may offer larger yellow perch increased feeding opportunities because prey fish were concentrated into smaller habitats. Thus, the %IRI of small prey fish in the diet of large yellow perch was high through fall. Likewise, small yellow perch consumed seasonally abundant foods including chironomid larvae and copepods.

This study demonstrates that even though the lower three km of Fourmile Creek loses most of its surface water, it is an important habitat for both fish and macroinvertebrates during March – October. Native fish dominate the Fourmile Creek fish assemblage from March – August. Non-native fish then became dominant.

Spatially, both the abundance and richness of fish were greatest at sites situated within the lower one km of Fourmile Creek where surface flow persisted for more months and water quality (temperature, dissolved oxygen and pH) tended to be more stable than at sites situated within the more ephemeral third km of the creek. The fish assemblage in the lower three kilometers of Fourmile Creek was dominated by two native and two non- native fish. Both gonadosomatic index values and the presence of larval and juvenile fish show that Fourmile Creek is an important breeding habitat for these and other fish.

Speckled dace and yellow perch spawn in spring, fathead minnow spawn in summer, and slender sculpin spawn during late summer/fall. Condition factors of sexually mature fish tended to decrease both during their reproductive season and as surface waters disappeared. Especially poor body condition of slender sculpin captured during the spring was due to their reproductive timing, and was likely exacerbated by poor growth

188 conditions during winter. Across seasons, benthic insects and crustaceans were the most important foods for speckled dace and slender sculpin. Detritus and crustaceans were the most important foods for fathead minnow. Insects, crustaceans and fish were the most important foods for yellow perch. Dietary overlap between speckled dace and fathead minnow was not significant across seasons, even as the creek dried, suggesting minimal dietary competition between these two abundant cyprinid species. Despite the lack of significant dietary overlap, these two species may face competition in other arenas, including competition over habitat as the stream dries. Potential macroinvertebrate prey was both overall and seasonally abundant. Crustaceans, insects and annelids were the dominant macroinvertebrates inhabiting Fourmile Creek. Cladocerans and copepods, the dominant crustacean taxa, peaked in abundance during spring/early summer and during fall. Dipterans, principally chironimid larvae, dominated the insect community during most months, while hemipteran and coleopteran taxa increased in abundance as the creek dried. Other insects, including simuliid larvae, were only abundant until early summer, when water flow decreased.

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PERSONAL COMMUNICATIONS

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APPENDICIES

195

Appendix A. Light trap sampling effort (total (hours of darkness + 2) fished) and total number of samples taken at two sampling transects, Fourmile (FM) and Westside (WS), in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Sites are: lower (LW), upper (UP), pasture (PS). Hours fished for each sample = hours of darkness + two hours.

Fishing effort (# samples) Site Total Sampling Location LW UP PS

Fourmile 363.5 (30) 363.5 (30) 727.0 (60)

Westside 206.1 (18) 205.3 (18) 22.3 (2) 433.7 (38)

1160.7 (98)

196

Appendix B. Plankton tow sampling effort (m 3 water filtered ) and total number of samples collected at two sampling transects, Fourmile (FM) and Westside (WS), in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

Fishing effort (# samples) Site Total Sampling Location LW UP PS

Fourmile 40.3 (30) 40.3 (30) 80.6 (60) Westside 16.0 (16) 18.2 (14) 2.3 (2) 36.5 (32)

117.1 (92)

197

Light Trap 100

20 mean CPUEhr) mean (number/12

MAMJJASOMAMJJAS 2005 2006

3.0 Plankton Tow + 2.5

2.0 + + 1.5

1.0 + + 0.5 mean CPUEmean (number/m*3) + + + 0.0 + + + + + + +

MAMJJASOMAMJJAS 2005 2006

Appendix C. Overall mean monthly CPUE for Hydrachnida sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

198

Light Trap 6000

5000

4000

3000

2000

1000 mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Plankton Tow + 80 +

60 +

40 + + + 20 + mean CPUEmean (number/m*3) + + + + 0 + + + +

MAMJJASOMAMJJAS 2005 2006

Appendix D. Overall mean monthly CPUE for Cladocera sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

199

800 Light Trap

600

400

200 mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

+ Plankton Tow 50 +

40 +

20 + 10 + mean CPUEmean (number/m*3) + + + + + + 0 + + + +

MAMJJASOMAMJJAS 2005 2006

Appendix E. Overall mean monthly CPUE for Copepoda sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

200

140 Light Trap 120

100

20 mean CPUEhr) mean (number/12

MAMJJASOMAMJJAS 2005 2006

80 Plankton Tow +

40 +

20 + +

mean CPUEmean (number/m*3) + + + + 0 + + + + + + +

MAMJJASOMAMJJAS 2005 2006

Appendix F. Overall mean monthly CPUE for Ostracoda sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

201

Light Trap 1.0

0.8

0.6

0.4

0.2 mean CPUEhr) mean (number/12 0.0

MAMJJASOMAMJJAS 2005 2006

+ Plankton Tow 30

20 +

5 mean CPUEmean (number/m*3) + + + + 0 + + + + + + + + +

MAMJJASOMAMJJAS 2005 2006

Appendix G. Overall mean monthly CPUE for Collembola sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

202

300 Light Trap

250

200

150

100

50 mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

6 Plankton Tow + 5

4 +

2 + 1 + mean CPUEmean (number/m*3) + + 0 + + + + + + + + +

MAMJJASOMAMJJAS 2005 2006

Appendix H. Overall mean monthly CPUE for Ephemeroptera sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

203

Light Trap

300

200

100 mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

+ Plankton Tow 60

30 + 20

10 mean CPUEmean (number/m*3) + + + + 0 + + + + + + + + +

MAMJJASOMAMJJAS 2005 2006

Appendix I. Overall mean monthly CPUE for Hemiptera sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

204

350 Light Trap

300

250

200

150

100

mean CPUEhr) mean (number/12 50

MAMJJASOMAMJJAS 2005 2006

Plankton Tow 4 + + 3

+ 1 + + mean CPUEmean (number/m*3) + 0 + + + + + + + + +

MAMJJASOMAMJJAS 2005 2006

Appendix J. Overall mean monthly CPUE for Corixidae sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

205

Light Trap 1.0

0.8

0.6

0.4

0.2 mean CPUEhr) mean (number/12 0.0

MAMJJASOMAMJJAS 2005 2006

Plankton Tow 4 +

3 +

+ + 2

+ + + 1 + mean CPUEmean (number/m*3) + + 0 + + + +

MAMJJASOMAMJJAS 2005 2006

Appendix K. Overall mean monthly CPUE for Aphidoidea sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

206

4 Light Trap

1 mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

4 Plankton Tow

+ + 3 +

+ 1 mean CPUEmean (number/m*3)

0 + + + + + + + + + +

MAMJJASOMAMJJAS 2005 2006

Appendix L. Overall mean monthly CPUE for Gerridae sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

207

Light Trap 250

200

150

100

50 mean CPUEhr) mean (number/12

MAMJJASOMAMJJAS 2005 2006

+ Plankton Tow 6

5 + +

4 + 3

2 + + + + 1 + mean CPUEmean (number/m*3) + + + + 0 + +

MAMJJASOMAMJJAS 2005 2006

Appendix M. Overall mean monthly CPUE for Coleoptera sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

208

140 Light Trap 120

100

mean CPUEhr) mean (number/12 20

MAMJJASOMAMJJAS 2005 2006

Plankton Tow 4 +

2 +

+ 1 + + + +

mean CPUEmean (number/m*3) + + + 0 + + + + +

MAMJJASOMAMJJAS 2005 2006

Appendix N. Overall mean monthly CPUE for Dytiscidae sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

209

Light Trap 120

100

20 mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

3.5 + Plankton Tow

3.0 +

2.5

2.0

1.5 +

1.0 +

mean CPUEmean (number/m*3) 0.5 + + + + + 0.0 + + + + + +

MAMJJASOMAMJJAS 2005 2006

Appendix O. Overall mean monthly CPUE for Hydrophilidae sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

210

5000 Light Trap

4000

3000

2000

1000 mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

+ Plankton Tow 150 +

+ 100

50 + + + +

mean CPUEmean (number/m*3) + + + + + + + 0 +

MAMJJASOMAMJJAS 2005 2006

Appendix P. Overall mean monthly CPUE for Diptera sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

211

5000 Light Trap

4000

3000

2000

1000 mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

150 + + Plankton Tow

100 +

50 + + +

mean CPUEmean (number/m*3) + + + + + + 0 + + +

MAMJJASOMAMJJAS 2005 2006

Appendix Q. Overall mean monthly CPUE for Chironomidae sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

212

Light Trap 8

2 mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

+ Plankton Tow 25

15 +

10 + + 5 mean CPUEmean (number/m*3) + + + + + + + 0 + + + +

MAMJJASOMAMJJAS 2005 2006

Appendix R. Overall mean monthly CPUE for Diptera (misc) sampled in light traps and plankton tows at Fourmile (FM) and Westside (WS) sampling transects, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006.

213

80 Upper Site FM Low er Site 60

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

80 Upper Site WS Low er Site Pasture Site 60

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Appendix S. Mean CPUE for snails sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

214

100 Upper Site FM Low er Site 80

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

100 Upper Site WS Low er Site 80 Pasture Site

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

Appendix T. Mean CPUE for snails sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

215

6 Upper Site FM Low er Site 5

4 3

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

6 Upper Site WS Low er Site 5 Pasture Site 4

2 1

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Appendix U. Mean CPUE for Oligochaeta sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

216

20 Upper Site FM Low er Site

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

20 Upper Site WS Low er Site Pasture Site 15

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

Appendix V. Mean CPUE for Oligochaeta sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

217

100 Upper Site FM Low er Site 80

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

100 Upper Site WS Low er Site Pasture Site 80

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Appendix W. Mean CPUE for Arachnida sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

218

4 Upper Site FM Low er Site

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

4 Upper Site WS Low er Site Pasture Site 3

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

Appendix X. Mean CPUE for Arachnida sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

219

100 Upper Site FM Low er Site 80

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

100 Upper Site WS Low er Site Pasture Site 80

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Appendix Y. Mean CPUE for Hydrachnida sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

220

5 Upper Site FM Low er Site 4

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

5 Upper Site WS Low er Site 4 Pasture Site

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

Appendix Z. Mean CPUE for Hydrachnida sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

221

Upper Site FM Low er Site 6000

4000

2000

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Upper Site WS Low er Site 6000 Pasture Site

4000

2000

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Appendix AA. Mean CPUE for Crustacea sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

222

200 Upper Site FM Low er Site

150

100

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

200 Upper Site WS Low er Site Pasture Site 150

100

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

Appendix AB. Mean CPUE for Crustacea sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

223

7000 Upper Site FM Low er Site 6000 5000 4000 3000 2000 1000

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

7000 Upper Site WS Low er Site 6000 Pasture Site 5000 4000 3000 2000 1000

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Appendix AC. Mean CPUE for Cladocera sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

224

120 Upper Site FM Low er Site 100

80 60

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

120 Upper Site WS Low er Site 100 Pasture Site 80

40 20

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

Appendix AD. Mean CPUE for Cladocera sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

225

1000 Upper Site FM Low er Site 800

600

400

200

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

1000 Upper Site WS Low er Site 800 Pasture Site

600

400

200

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Appendix AE. Mean CPUE for Copepoda sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

226

120 Upper Site FM Low er Site 100

80 60

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

120 Upper Site WS Low er Site 100 Pasture Site 80

40 20

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

Appendix AF. Mean CPUE for Copepoda sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

227

80 Upper Site FM Low er Site

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

80 Upper Site WS Low er Site Pasture Site 60

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Appendix AG. Mean CPUE for Ostracoda sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

228

60 Upper Site FM Low er Site 50

40 30

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

60 Upper Site WS Low er Site 50 Pasture Site 40

20 10

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

Appendix AH. Mean CPUE for Ostracoda sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

229

7000 Upper Site FM Low er Site 6000 5000 4000 3000 2000 1000

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

7000 Upper Site WS Low er Site 6000 Pasture Site 5000 4000 3000 2000 1000

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Appendix AI. Mean CPUE for Insecta sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

230

120 Upper Site FM Low er Site 100

80 60

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

120 Upper Site WS Low er Site 100 Pasture Site 80

40 20

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

Appendix AJ. Mean CPUE for Insecta sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

231

Upper Site FM 100 Low er Site

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

Upper Site WS Low er Site 100 Pasture Site 80

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

Appendix AK. Mean CPUE for Collembola sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

232

500 Upper Site FM Low er Site 400

300

200

100

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

500 Upper Site WS Low er Site 400 Pasture Site

300

200

100

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Appendix AL. Mean CPUE for Ephemeroptera sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

233

15 Upper Site FM Low er Site

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

15 Upper Site WS Low er Site Pasture Site

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

Appendix AM. Mean CPUE for Ephemeroptera sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

234

600 Upper Site FM Low er Site 500

400 300

200

100

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

600 Upper Site WS Low er Site 500 Pasture Site 400

300

200 100

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Appendix AN. Mean CPUE for Hemiptera sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

235

80 Upper Site FM Low er Site

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

80 Upper Site WS Low er Site Pasture Site 60

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

Appendix AO. Mean CPUE for Hemiptera sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

236

Upper Site FM 500 Low er Site

400

300

200

100

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Upper Site WS 500 Low er Site Pasture Site 400

300

200

100

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Appendix AP. Mean CPUE for Corixidae sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

237

50 Upper Site Aphidoidea FM Low er Site 40

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

50 Upper Site Aphidoidea WS Low er Site 40 Pasture Site

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Appendix AQ. Mean CPUE for Aphidoidea sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

238

25 Upper Site FM Low er Site 20

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

25 Upper Site WS Low er Site 20 Pasture Site

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Appendix AR. Mean CPUE for Gerridae sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

239

400 Upper Site FM Low er Site

300

200

100

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

400 Upper Site WS Low er Site Pasture Site 300

200

100

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Appendix AS. Mean CPUE for Coleoptera sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

240

25 Upper Site FM Low er Site 20

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

25 Upper Site WS Low er Site 20 Pasture Site

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

Appendix AT. Mean CPUE for Coleoptera sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

241

200 Upper Site FM Low er Site

150

100

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

200 Upper Site WS Low er Site Pasture Site 150

100

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Appendix AU. Mean CPUE for Dytiscidae caught in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

242

200 Upper Site FM Low er Site

150

100

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

200 Upper Site WS Low er Site Pasture Site 150

100

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Appendix AV. Mean CPUE for Hydrophilidae caught in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

243

Upper Site FM 5000 Low er Site

4000

3000

2000

1000

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Upper Site WS 5000 Low er Site Pasture Site 4000

3000

2000

1000

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Appendix AW. Mean CPUE for Diptera sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

244

100 Upper Site FM Low er Site 80

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

100 Upper Site WS Low er Site 80 Pasture Site

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

Appendix AX. Mean CPUE for Diptera sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

245

Upper Site FM 5000 Low er Site

4000

3000

2000

1000

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Upper Site WS 5000 Low er Site Pasture Site 4000

3000

2000

1000

mean CPUEhr) mean (number/12 0

MAMJJASOMAMJJAS 2005 2006

Appendix AY. Mean CPUE for Chironomidae sampled in light traps at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

246

120 Upper Site FM Low er Site 100

80 60

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

120 Upper Site WS Low er Site 100 Pasture Site 80

40 20

mean CPUEmean (number/m*3) 0

MAMJJASOMAMJJAS 2005 2006

Appendix AZ. Mean CPUE for Chironomidae larvae sampled in plankton tows at the Fourmile (FM) and Westside (WS) sites, lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each sampling period, mean CPUE = mean CPUE for duplicate samples taken at sites.

247

Appendix BA. Number of organisms and frequency of occurrence (number of samples) of major Crustacean and Arachnid taxa caught in benthic samples at two sampling transects, Fourmile (FM), and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – October 2006. The % of total = % of total number of Arachnida and % of total number of Crustacea collected in benthic samples. The % samples = % of total number of benthic samples in which the taxon was collected.

Taxon Number % of Total a # of Samples % of Samples b Arachnida Hydrachnida 7 70.00 7 7.00 Oribatida 1 10.00 1 1.00 Araneae 2 20.00 2 2.00

248 Crustacea Amphipoda 3 3.49 2 2.00 Cladocera 18 20.93 9 9.00 Copepoda 34 39.53 19 19.00 Ostracoda 31 36.05 18 18.00

a Total number of Arachnida sampled= 10; total number of Crustacea sampled = 86 b Total number of benthic samples = 100

Appendix BB. Number of organisms and frequency of occurrence (number of samples) of major Insect taxa collected in benthic samples at two sampling transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – October 2006. The % of total = % of total number of Insecta collected in benthic samples. The % samples = % of total number of benthic samples in which the taxon was collected.

Taxon Number % of Total a # of Samples % of Samples b Insecta (misc) 1 0.16 1 1.00 Diplura 1 0.16 1 1.00 Collembola 27 4.26 18 18.00 Ephemeroptera 1 0.16 1 1.00 Odonata 1 0.16 1 1.00 249 Hemiptera 5 0.79 4 4.00 Hymenoptera 2 0.32 2 2.00 Megaloptera 2 0.32 2 2.00 Trichoptera 12 1.89 9 9.00 Lepidoptera 3 0.47 3 3.00 Coleoptera 24 3.79 19 19.00 Diptera 555 87.54 85 85.00

a Total number of Insecta sampled = 634 b Total number of benthic samples = 100

Appendix BC. Total monthly counts of each species captured in trap nets set at the Fourmile (FM) and Westside (WS) transects in lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. For each month, trap net catches at sites within each transect were combined. X indicates no trap netting at a transect during a given month. Transect Year Species Mar Apr May Jun Jul Aug Sep Oct Total FM 2005 Lampetra (ammocoete) 0 0 0 0 0 0 0 0 0 Gila bicolor 9 11 50 7 1 5 6 18 107 Gila coerulea 17 10 44 4 2 5 0 1 83 Pimephales promelas 60 67 67 16 10 521 1,796 1,298 3,835 Rhinichthys osculus 602 645 32 251 350 1,097 1,179 542 4,698

250 Catostomidae (juvenile) 0 0 0 0 0 0 0 0 0 Ameiurus nebulosus 1 1 0 0 0 1 16 21 40 Oncorhynchus mykiss 0 0 0 0 0 1 0 0 1 Oncorhynchus nerka 0 0 0 0 0 0 0 0 0 Salmo trutta 0 0 0 0 0 0 0 0 0 Salvelinus fontinalis 0 0 0 0 1 0 0 0 1 Cottus klamathensis 0 0 0 0 2 14 11 22 49 Cottus princeps 5 5 7 1 13 17 40 19 107 Cottus tenuis 51 33 27 21 11 59 33 1 236 Lepomis gibbosus 2 0 0 0 0 0 1 0 3 Perca flavescens 14 2 0 0 0 9 12 132 169

Total 761 774 227 300 390 1,729 3,094 2,054 9,329

Transect Year Species Mar Apr May Jun Jul Aug Sep Oct Total FM 2006 Lampetra (ammocoete) 0 0 0 0 0 0 1 X 1 Gila bicolor 6 4 1 27 1 1 2 X 42 Gila coerulea 4 10 2 23 21 8 1 X 69 Pimephales promelas 9 58 10 251 260 809 412 X 1,809 Rhinichthys osculus 86 128 1 241 2,714 2,236 397 X 5,803 Catostomidae (juvenile) 0 0 0 1 0 0 0 X 1 Ameiurus nebulosus 1 6 1 1 1 2 64 X 76 Oncorhynchus mykiss 0 0 0 0 1 4 0 X 5 Oncorhynchus nerka 0 0 0 8 4 4 3 X 19 Salmo trutta 0 0 0 0 0 4 0 X 4 Salvelinus fontinalis 0 0 0 0 0 0 0 X 0 Cottus klamathensis 0 0 0 1 2 0 4 X 7 Cottus princeps 0 0 7 15 8 15 7 X 52 Cottus tenuis 127 24 38 94 10 24 6 X 323 Lepomis gibbosus 0 1 0 1 0 0 10 X 12 Perca flavescens 7 7 1 181 358 196 129 X 879

Total 240 238 61 844 3,380 3,303 1,036 X 9,102

251

Transect Year Species Mar Apr May Jun Jul Aug Sep Oct Total WS 2005 Lampetra (ammocoete) X 0 0 0 0 X X X 0 Gila bicolor X 0 0 0 0 X X X 0 Gila coerulea X 0 0 1 0 X X X 1 Pimephales promelas X 0 3 116 19 X X X 138 Rhinichthys osculus X 15 35 78 16 X X X 144 Catostomidae (juvenile) X 0 0 0 0 X X X 0 Ameiurus nebulosus X 0 0 0 2 X X X 2 Oncorhynchus mykiss X 0 0 0 0 X X X 0 Oncorhynchus nerka X 0 0 0 0 X X X 0 Salmo trutta X 0 0 1 0 X X X 1 Salvelinus fontinalis X 0 0 0 0 X X X 0 Cottus klamathensis X 0 0 0 0 X X X 0 Cottus princeps X 0 0 4 0 X X X 4 Cottus tenuis X 0 0 25 2 X X X 27 Lepomis gibbosus X 0 0 0 0 X X X 0 Perca flavescens X 0 0 0 0 X X X 0

Total X 15 38 225 39 X X X 317

252

Transect Year Species Mar Apr May Jun Jul Aug Sep Oct Total WS 2006 Lampetra(ammocoete) 0 0 0 0 0 X X X 0 Gila bicolor 0 0 3 0 0 X X X 3 Gila coerulea 0 0 3 0 0 X X X 3 Pimephales promelas 0 4 86 77 47 X X X 214 Rhinichthys osculus 33 342 253 275 0 X X X 903 Catostomidae(juvenile) 0 0 0 0 0 X X X 0 Ameiurus nebulosus 0 0 0 5 114 X X X 119 Oncorhynchus mykiss 0 0 0 1 0 X X X 1 Oncorhynchus nerka 0 0 0 2 0 X X X 2 Salmo trutta 0 0 0 0 0 X X X 0 Salvelinus fontinalis 0 0 0 0 0 X X X 0 Cottus klamathensis 0 0 0 0 0 X X X 0 Cottus princeps 0 0 0 0 0 X X X 0 Cottus tenuis 0 0 5 3 16 X X X 24 Lepomis gibbosus 0 0 0 0 2 X X X 2 Perca flavescens 0 0 0 4 187 X X X 191

Total 33 346 350 367 366 X X X 1,462

253

6 254 PERCENTFREQUENCY 4

0 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 <36 100 102

SIZE CLASS MIDPOINTS (mm)

Appendix BD. Length frequencies of speckled dace, Rhinichthys osculus , collected in trap nets at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Midpoints represent 2mm total length size classes. N = 11,548 speckled dace.

25 20 MAR 15 N= 67 10 5 0 25 20 APR 15 N= 675 10 5 0 25 20 MAY 15 N= 67 10 5 0 25 20 JUN 15 N= 329 10 5 0 25 20 JUL 15 N= 351 10 5 PERCENT PERCENT FREQUENCY 0 25 20 AUG 15 N= 1097 10 5 0 25 20 SEP 15 N= 1179 10 5 0 25 20 OCT 15 N= 542 10 5 0 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 <36 100 102 SIZE CLASS MIDPOINTS

Appendix BE. Length frequencies of speckled dace, Rhinichthys osculus , collected in trap nets at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005. Midpoints represent 2mm total length size classes.

255

25 20 MAR 15 N= 119 10 5 0 25 20 APR 15 N= 470 10 5 0 25 20 MAY 15 N= 254 10 5 0 25 20 JUN 15 N= 516 10 5 0 25 20 JUL 15 N= 2714 PERCENT FREQUENCY 10 5 0 25 20 AUG 15 N= 2236 10 5 0 25 20 SEP 15 N= 397 10 5 0 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 <36 100 102 SIZE CLASS MIDPOINTS

Appendix BF. Length frequencies of speckled dace, Rhinichthys osculus collected in trap nets at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – September 2006. Midpoints represent 2mm total length size classes.

256

10 257 PERCENTFREQUENCY

<34 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 71 SIZE CLASS MIDPOINTS (mm)

Appendix BG. Overall length frequencies of fathead minnow, Pimephales promelas , collected in trap nets at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Midpoints represent 2mm total length size classes. N = 5,996 fathead minnow.

30 25 MAR 20 N= 70 15 10 5 0 35 30 25 APR 20 N= 67 15 10 5 0 35 30 25 MAY 20 N= 70 15 10 5 0 35 30 25 JUN 20 N= 132 15 10 5 0 35 30 25 JUL 20 N= 29 15 10

PERCENT PERCENT FREQUENCY 5 0 35 30 25 AUG 20 N= 521 15 10 5 0 35 30 25 SEP 20 N= 1796 15 10 5 0 35 30 25 OCT 20 N= 1298 15 10 5 0 <34 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 71 SIZE CLASS MIDPOINTS

Appendix BH. Length frequencies of fathead minnow, Pimephales promelas , collected in trap nets at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005. Midpoints represent 2mm total length size classes.

258

35 30 25 MAR 20 N= 9 15 10 5 0 35 30 25 APR 20 N= 62 15 10 5 0 35 30 25 MAY 20 N= 96 15 10 5 0 35 30 25 JUN 20 N= 328 15 10 5 0 35 30 25 JUL 20 N= 307 PERCENT PERCENT FREQUENCY 15 10 5 0 35 30 25 AUG 20 N= 809 15 10 5 0 35 30 25 SEP 20 N= 412 15 10 5 0 <34 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 71 SIZE CLASS MIDPOINTS

Appendix BI. Length frequencies of fathead minnow, Pimephales promelas , collected in trap nets at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – September 2006. Midpoints represent 2mm total length size classes.

259

4 260 PERCENTFREQUENCY 2

0 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 71 73 75 77 79 81 83 85 87 89 91 93 95 97 99 101 103 105 107 <40 SIZE CLASS MIDPOINTS (mm)

Appendix BJ. Overall length frequencies of slender sculpin, Cottus tenuis , collected in trap nets at two sampling transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Midpoints represent 2mm total length size classes. N = 610 slender sculpin.

30 25 MAR 20 N= 51 15 10 5 0 30 25 APR 20 N= 33 15 10 5 0 30 25 MAY 20 N= 27 15 10 5 0 30 25 JUN 20 N= 46 15 10 5 0 30 25 JUL 20 N= 13 15 10 5 PERCENT PERCENT FREQUENCY 0 30 25 AUG 20 N= 59 15 10 5 0 30 25 SEP 20 N= 33 15 10 5 0 30 25 OCT 20 N= 1 15 10 5 0 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 71 73 75 77 79 81 83 85 87 89 91 93 95 97 99 <40 101 103 105 107 SIZE CLASS MIDPOINTS (mm)

Appendix BK. Length frequencies of slender sculpin, Cottus tenuis , collected in trap nets at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005. Midpoints represent 2mm total length size classes.

261

30 25 MAR 20 N= 127 15 10 5 0 30 25 APR 20 N= 24 15 10 5 0 30 25 MAY 20 N= 43 15 10 5 0 30 25 JUN 20 N= 97 15 10 5 0 30 25 JUL 20 N= 26

PERCENT FREQUENCY 15 10 5 0 30 25 AUG 20 N= 24 15 10 5 0 30 25 SEP 20 N= 6 15 10 5 0 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 71 73 75 77 79 81 83 85 87 89 91 93 95 97 99 <40 101 103 105 107 SIZE CLASS MIDPOINTS (mm)

Appendix BL. Length frequencies of slender sculpin, Cottus tenuis , collected in trap nets at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – September 2006. Midpoints represent 2mm total length size classes.

262

20 263 PERCENTFREQUENCY

0 35 45 55 65 75 85 95 105 115 125 135 145 155 165 175 185 195 205 <30 SIZE CLASS MIDPOINTS (mm)

Appendix BM. Length frequencies of yellow perch, Perca flavescens , collected in trap nets at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Midpoints represent 10mm total length size classes. N = 1,239 yellow perch.

80 MAR 60 N= 14 40 20 0 80 APR 60 N= 2 40 20 0 80 MAY 60 N = 0 40 20 0 80 JUN 60 N = 0 40 20 0 80 JUL 60 N = 0 40 20 PERCENT PERCENT FREQUENCY 0

80 AUG 60 N= 9 40 20 0 80 SEP 60 N= 12 40 20 0 80 OCT 60 N= 132 40 20 0 35 45 55 65 75 85 95 105 115 125 135 145 155 165 175 185 195 205 <30 SIZE CLASS MIDPOINTS

Appendix BN. Length frequencies of yellow perch, Perca flavescens , collected in trap nets at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005. Midpoints represent 10mm total length size classes.

264

80 MAR 60 N= 7 40 20 0 80 APR 60 N= 7 40 20 0 80 MAY 60 N= 1 40 20 0 80 JUN 60 N= 185 40 20 0 80 JUL 60 N= 545

PERCENT FREQUENCY 40 20 0 80 AUG 60 N= 196 40 20 0 80 SEP 60 N= 129 40 20 0 35 45 55 65 75 85 95 105 115 125 135 145 155 165 175 185 195 205 <30 SIZE CLASS MIDPOINTS

Appendix BO. Length frequencies of yellow perch, Perca flavescens , collected in trap nets at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – September 2006. Midpoints represent 10mm total length size classes.

265

10 PERCENTFREQUENCY 5

0 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 <4

SIZE CLASS MIDPOINTS (mm)

Appendix BP. Overall length frequencies of Cyprinidae collected in light traps at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Midpoints represent 2mm total length size classes. N = 1,939 Cyprinidae.

266

60 MAR 40 N = 78 20 0 60 APR 40 N = 5 20 0 60 MAY 40 N = 3 20 0 60 JUN 40 N = 719 20 0 60 JUL 40 N = 189 20 0 PERCENT FREQUENCY 60 AUG 40 N = 99 20 0 60 SEP 40 N = 226 20 0 60 OCT 40 N = 12 20 0 5 7 9 <4 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 SIZE CLASS MIDPOINTS (mm)

Appendix BQ. Overall length frequencies of Cyprinidae collected in light traps at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005. Midpoints represent 2mm total length size classes.

267

60 MAR 40 N = 0 20 0 60 APR 40 N = 7 20 0 60 MAY 40 N = 0 20 0 60 JUN 40 N = 41 20 0 60 JUL 40 N = 400

PERCENT FREQUENCY 20 0 60 AUG 40 N = 104 20 0 60 SEP 40 N = 56 20 0 5 7 9 <4 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 SIZE CLASS MIDPOINTS (mm)

Appendix BR. Overall length frequencies of Cyprinidae collected in light traps at two transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – September 2006. Midpoints represent 2mm total length size classes.

268

20 PERCENTFREQUENCY

0 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 <4

SIZE CLASS MIDPOINTS (mm)

Appendix BS. Overall length frequencies of sculpin, Cottus sp. , collected in light traps at two sampling transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005 and March – September 2006. Midpoints represent 2mm total length size classes. N = 2,482 Cottidae.

269

MAR 60 N = 1709 40

0 APR 60 N = 278 40

0 MAY 60 N = 65 40

60 JUN N = 81 40

0 JUL 60 N = 153 40

PERCENT PERCENT FREQUENCY 20

0 AUG 60 N = 97 40

60 SEP N = 32 40

60 OCT N = 1 40

0 5 7 9 <4 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 SIZE CLASS MIDPOINTS (mm)

Appendix BT. Overall length frequencies of sculpin, Cottus sp. , collected in light traps at two sampling transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – October 2005. Midpoints represent 2mm total length size classes.

270

MAR 60 N = 0 40

0 APR 60 N = 8 40

0 MAY 60 N = 0 40

20 0

60 JUN N = 18 40

0 JUL PERCENT FREQUENCY 60 N = 16 40

0 AUG 60 N = 2 40

20 0

60 SEP N = 19 40

0 5 7 9 <4 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 SIZE CLASS MIDPOINTS (mm)

Appendix BU. Overall length frequencies of sculpin, Cottus sp. , collected in light traps at two sampling transects, Fourmile (FM) and Westside (WS), lower Fourmile Creek, Upper Klamath Lake, Oregon, March – September 2006. Midpoints represent 2mm total length size classes.

271