Idaho Department of Fish and Game Fisheries Management Annual Report

Home , Boulder Chain Lakes, Chamberlain Basin, Chinese Wall (Idaho), Cove Lake, East Fork Salmon River, Fourth of July Lake

IDAHO DEPARTMENT OF FISH AND GAME FISHERIES MANAGEMENT ANNUAL REPORT

Virgil Moore, Director

SALMON REGION 2016

Jordan Messner, Regional Fisheries Biologist Jon Hansen, Regional Fisheries Biologist Brent Beller, Senior Fisheries Technician Greg Schoby, Regional Fisheries Manager

November 2018 IDFG 17-104

TABLE OF CONTENTS HIGH MOUNTAIN LAKES:...... 1 STOCKING AND SURVEYS - 2016 ...... 1 ABSTRACT ...... 1 INTRODUCTION ...... 2 OBJECTIVES ...... 2 Mountain Lake Stocking ...... 2 Mountain Lake Surveys ...... 2 STUDY AREA ...... 2 METHODS ...... 3 Mountain Lake Stocking ...... 3 Mountain Lake Surveys ...... 3 RESULTS AND DISCUSSION ...... 4 Mountain Lake Stocking ...... 4 Mountain Lake Surveys ...... 4 Challis Area ...... 4 Slate Creek Area ...... 6 Boulder-White Clouds - Little Boulder Creek ...... 9 Boulder-White Clouds - Big Boulder Creek ...... 14 Boulder-White Clouds - Chamberlain Basin ...... 18 Boulder-White Clouds – Fourth of July Drainage ...... 20 MANAGEMENT RECOMMENDATIONS ...... 22 LOWLAND LAKES AND RESERVOIRS: ...... 49 TROUT EXPLOITATION STUDIES ...... 49 ABSTRACT ...... 49 INTRODUCTION ...... 50 OBJECTIVES ...... 50 STUDY SITES ...... 50 METHODS ...... 52 Return-to-Creel ...... 52 Angler Effort ...... 52 RESULTS AND DISCUSSION ...... 53 Little Bayhorse Lake ...... 53 Perkins Lake ...... 53 Squaw Creek Pond ...... 54 Valley Creek ...... 54 Yankee Fork Dredge Ponds ...... 55 MANAGEMENT RECOMMENDATIONS ...... 55 WALLACE LAKE REDSIDE SHINER AND TIGER TROUT SAMPLING ...... 63 ABSTRACT ...... 63 INTRODUCTION ...... 64 OBJECTIVES ...... 64 STUDY SITE ...... 64 METHODS ...... 65

Biological Sampling ...... 65 Tiger Trout ...... 65 Redside Shiners ...... 65 Zooplankton ...... 66 Angler Effort and Return-to-Creel ...... 66 RESULTS AND DISCUSSION ...... 67 Biological Sampling ...... 67 Angler Effort and Return-to-Creel ...... 68 MANAGEMENT RECOMMENDATIONS ...... 69 REGIONAL LAKE INVENTORIES ...... 77 ABSTRACT ...... 77 INTRODUCTION ...... 78 OBJECTIVES ...... 78 STUDY SITES AND METHODS ...... 78 Buster Lake ...... 78 Stanley Lake ...... 79 Stone Reservoir ...... 80 RESULTS AND DISCUSSION ...... 80 Buster Lake ...... 80 Stanley Lake ...... 81 Stone Reservoir ...... 82 MANAGEMENT RECOMMENDATIONS ...... 82 JIMMY SMITH LAKE RAINBOW TROUT FISHERY ...... 89 ABSTRACT ...... 89 HISTORY AND INTRODUCTION ...... 90 OBJECTIVES ...... 90 STUDY SITE ...... 90 METHODS ...... 91 RESULTS AND DISCUSSION ...... 92 MANAGEMENT RECOMMENDATIONS ...... 93 CARLSON LAKE FISHERY EVALUATION ...... 97 ABSTRACT ...... 97 INTRODUCTION ...... 98 OBJECTIVES ...... 98 STUDY SITE AND METHODS ...... 98 RESULTS ...... 99 DISCUSSION...... 100 MANAGEMENT RECOMMENDATIONS ...... 100 HERD LAKE FISHERY EVALUATION ...... 105 ABSTRACT ...... 105 INTRODUCTION ...... 106 OBJECTIVES ...... 106 STUDY SITE AND METHODS ...... 106

RESULTS ...... 107 DISCUSSION...... 107 MANAGEMENT RECOMMENDATIONS ...... 108 RIVERS AND STREAMS: ...... 113 SALMON RIVER ELECTROFISHING SURVEYS ...... 113 ABSTRACT ...... 113 INTRODUCTION ...... 114 OBJECTIVES ...... 114 STUDY SITES AND METHODS ...... 115 RESULTS ...... 116 DISCUSSION...... 118 MANAGEMENT RECOMMENDATIONS ...... 118 WILD TROUT REDD COUNTS ...... 132 ABSTRACT ...... 132 INTRODUCTION ...... 133 OBJECTIVES ...... 133 STUDY SITES AND METHODS ...... 133 Rainbow Trout Redd Count Monitoring ...... 133 Big Springs Creek ...... 133 Lemhi River ...... 134 Bull Trout Redd Count Monitoring ...... 134 Alpine Creek ...... 134 Fishhook Creek ...... 134 Fourth of July Creek ...... 134 Hayden Creek ...... 135 Bear Valley Creek ...... 135 East Fork Hayden Creek ...... 135 RESULTS AND DISCUSSION ...... 136 Rainbow Trout Redd Count Monitoring ...... 136 Big Springs Creek and Lemhi River ...... 136 Bull Trout Redd Count Monitoring ...... 136 Alpine Creek ...... 136 Fishhook Creek ...... 136 Fourth of July Creek ...... 137 Hayden Creek ...... 137 Bear Valley Creek ...... 137 East Fork Hayden Creek ...... 137 MANAGEMENT RECOMMENDATIONS ...... 137 MIDDLE FORK SALMON RIVER TREND MONITORING ...... 145 ABSTRACT ...... 145 INTRODUCTION ...... 146 OBJECTIVES ...... 146 STUDY SITES AND METHODS ...... 146 Mainstem and Tributary Snorkeling Transects ...... 147 Project Angling ...... 147

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RESULTS AND DISCUSSION ...... 147 Mainstem and Tributary Snorkeling Transects ...... 147 Project Angling ...... 148 MANAGEMENT RECOMMENDATIONS ...... 149 LITERATURE CITED ...... 159

LIST OF TABLES Table 1. Salmon Region high mountain lake stocking rotations A, B, and C by year, 2016 through 2022...... 23 Table 2 High Mountain Lakes stocked in the Salmon Region in 2016 (Rotation C)...... 23 Table 3. Rotation A high mountain lakes surveyed in 2016 (n = 34), including location (LLID), elevation, estimated maximum depth, hiking distances, estimated level of human use, and amphibian species observed...... 25 Table 4. High mountain lakes surveyed in 2016 that are not stocked on rotation A (n = 18). Includes location (LLID), elevation, estimated maximum depth, hiking distances, estimated level of human use, and amphibian species observed...... 27 Table 5. Fish population structure and abundance in high mountain lakes, surveyed in 2016, where fish were found (n = 47). Includes current stocking information, fish species, size structure, and relative abundances observed during surveys, mean length at age 2 when available, and whether or not natural reproduction is suspected...... 28 Table 7. Estimated angler exploitation (fish harvested) and total use (fish caught) of catchable Rainbow Trout stocked in 2016 in selected Salmon Region waterbodies, up to March 1, 2017. HRBT is hatchery Rainbow Trout...... 57 Table 8. Estimated mean exploitation (Expl.) (fish harvested) and total use (fish caught) for all stocked catchable Rainbow Trout in a given year, in Salmon Region water bodies 2011 through 2016 ...... 58 Table 9. Angler use at Squaw Creek Pond from May 5 to August 8, 2016. Values were estimated using three remote trail cameras positioned around the lake, which captured hourly photos of anglers fishing...... 59 Table 10. Minnow trap cluster locations (WGS84) (±3m) used for Wallace Lake Redside Shiner monitoring...... 70 Table 11. Summary statistics from Wallace Lake Redside Shiner sampling, 2005- 2016, including Redside Shiner sub-sample size (n), relative abundance (CPUE), total length statistics (mm), and condition factor (K)...... 70 Table 12. Zooplankton total biomass, ZPR, and ZQI average values obtained from mid-august sampling, 2013-2016...... 71 Table 13. Angler use at Wallace Lake from June 8 to October 26, 2015, and June 8 to October 12, 2016. Camera one did not function from June 22 to September 14, and Camera three did not function from July 21 to September 14, in 2016. Values were estimated using three remote trail cameras positioned around the lake, which captured hourly photos of anglers fishing...... 71

Table 14. Catch compositions and catch-per-unit-effort (CPUE, fish/hr) for Buster Lake on three sampling occasions, 1993, 2002, and 2016. EBT = Eastern Brook Trout, RBT = Rainbow Trout...... 83 Table 15. Summary statistics for kokanee salmon and Lake Trout captured during gill netting surveys at Stanley Lake, 2007 to 2016, including relative abundance (CPUE, fish/hr), total length, and relative weight (Wr)...... 83 Table 16. Summary of gill netting surveys at Jimmy Smith Lake 1996 to 2016, including mark/recapture population estimate and size structure information. (TL = total length, Wr = relative weight) ...... 94 Table 17. Summary of zooplankton sampling at Jimmy Smith Lake 2002 to 2016. (ZPR = zooplankton ratio, ZQI = zooplankton quality index) ...... 95 Table 18. Summary of relative abundance (catch per unit effort, CPUE) and size structure values from survey results at Carlson Lake, 1997 to 2016...... 101

Table 19. Total lengths (mm), weights (kg), and relative weights (Wr) of tiger muskellunge captured during gill netting at Carlson Lake in 2016...... 102 Table 20. Summary of Herd Lake surveys 1967 to 2016, showing Rainbow Trout relative abundance and size structure information. (TL = total length, Wr = relative weight) ...... 109

Table 21. Total lengths (mm), weights (kg), and relative weights (Wr) of tiger muskellunge captured during gill netting at Herd Lake in 2016...... 109 Table 22. Zooplankton total biomass, ZPR, and ZQI average values obtained from mid-summer sampling, 2002-2016...... 110 Table 23. Values (x) used to calculate confidence limits for a Poisson frequency distribution with total number of recaptures (R) equaling 0 through 4...... 119 Table 24. Catch rates (fish/hr) by day for all target fish captured during main stem Salmon River electrofishing in 2016. WCT = Westslope Cutthroat Trout, RBT = Rainbow Trout, BUT = Bull Trout, CHN = Chinook Salmon, BRK = Brook Trout, SMB = Smallmouth Bass...... 120 Table 25. Numbers of O. mykiss parr and Westslope Cutthroat Trout marked (M), captured (C), and recaptured (R) during three passes of electrofishing surveys on each transect in September and October, 2016 on the main stem Salmon River. Numbers were used to estimate abundance (fish/km) in each transect, if recaptures allowed...... 121 Table 26. Size structure summary for target species collected during Salmon River electrofishing in 2016...... 121 Table 27. Recapture information for fish PIT tagged prior to capture during our 2016 Salmon River e-fishing surveys...... 122 Table 28. Summary of Rainbow Trout redds counted in the upper Lemhi River and Big Springs Creek (BSC) transects, 1994 - 2016...... 138 Table 29. Bull trout redds counted in tributaries of the upper Salmon River in the Sawtooth National Recreation Area, 1998 - 2016...... 139 Table 30. Bull trout redds counted in the Hayden Creek drainage in the Lemhi River basin, 2002 - 2016...... 141 Table 31. Densities of salmonids observed during snorkel surveys in the MFSR drainage in 2016 (fish/100m2)...... 150

Table 32. Summary of fish caught during angling surveys on the mainstem MFSR, 1959 to 2016...... 152 Table 33. Percentage of each salmonid species represented in total catch during angling surveys on the mainstem MFSR, 1959 to 2016. 1969 was omitted due to only enumerating WCT that year...... 153

LIST OF FIGURES Figure 1. Length-frequency histograms and relative weights (Wr) of all fish captured by lake in the Challis Creek area during gill netting. All species are combined for relative weights (dashed line represents Wr = 100). Refer to Table 5 for sample sizes...... 32 Figure 2. Length-at-age of all fish captured and aged by lake in the Challis Creek area during gill netting...... 33

Figure 3. Length-frequency histograms of total lengths and relative weight (Wr)of all fish captured by lake in the Slate Creek area during gill netting. Note that x-axis for East Basin Creek Lake exceeds 460 mm, but fish larger than 460 mm TL exceeded 1kg and were not able to be weighed. All species are combined for relative weights (dashed line represents Wr = 100). Refer to Table 5 for sample sizes...... 34 Figure 4. Length-at-age of all fish captured and aged by lake in the Slate Creek area during gill netting...... 35 Figure 5. Length-frequency histograms of total lengths of all fish captured at lakes within the Little Boulder Creek drainage during gill netting and angling sampling events. All species are combined for relative weights (dashed line represents Wr = 100). Refer to Table 5 for sample sizes...... 36 Figure 6. Length-at-age of all fish captured and aged from lakes within the Little Boulder Creek drainage during gill netting and angling sampling events...... 39 Figure 7. Length-frequency histogram of total lengths of all fish captured at lakes within the Big Boulder Creek drainage during gill netting and angling sampling events. All species are combined for relative weights (dashed line represents Wr = 100). Refer to Table 5 for sample sizes...... 41 Figure 8. Lengths at ages of all fish captured and aged from lakes within the Big Boulder Creek drainage during gill netting and angling sampling events...... 43 Figure 9. Length-frequency histograms of total lengths of all fish captured at lakes in the Chamberlain Basin area during gill netting. All species are combined for relative weights (dashed line represents Wr = 100). Refer to Table 5 for sample sizes...... 45 Figure 10. Length-at-age of all fish captured and aged from lakes in the Chamberlain Basin area during gill netting...... 46 Figure 11. Length-frequency histograms of total lengths of all fish captured at lakes in the Fourth of July Creek area during gill netting. All species are combined for relative weights (dashed line represents Wr value of 100). Refer to Table 5 for sample sizes...... 47 Figure 12. Length-at-age of all fish captured and aged from lakes in the Fourth of July Creek area during gill netting...... 48

Figure 13. Overall estimated total use (catch) and exploitation (harvest) of catchable Rainbow Trout in seven selected waterbodies in the Salmon Region in 2016...... 60 Figure 14. Estimated total use (fish caught) and exploitation (fish harvested) (± 95% CI) based on angler tag returns for catchable-sized hatchery Rainbow Trout stocked in the Salmon Region in 2016. Overall averages for 2015 are also shown for lakes that were evaluated in both years...... 61 Figure 15. Estimated angler effort by month for Squaw Creek Pond in 2016, based on data gathered from remote trail cameras...... 62 Figure 16. Locations (± 3.0m) of minnow trap clusters and boat ramp shore access used for Wallace Lake Redside Shiner trapping. Specific coordinates are displayed in Table 10...... 72 Figure 17. Camera locations and directions of view for estimating angler effort in 2015 and 2016 at Wallace Lake...... 72 Figure 18. Relative frequencies and relative weights of tiger trout stocked and gill netted in Wallace Lake in 2015 and 2016...... 73 Figure 19. Size structure of the Redside Shiner population in Wallace Lake during sampling efforts from June, 2014 to September, 2016. June 2014 is the only sampling date where only four minnow traps were used, versus the nine clusters of three traps used for all other periods...... 74 Figure 20. Catch-per-unit-effort (fish/min ± SE) of Redside Shiners captured during minnow trapping in Wallace Lake in June, July, and September 2014- 2016...... 75 Figure 21. Zooplankton quality and abundance values from Wallace Lake in mid- August, 2013-2016...... 75 Figure 22. Monthly angler effort at Wallace Lake, June 8 through October 26, 2015 and June 8 through October 12, 2016. Camera one did not function from June 22 to September 14, and Camera three did not function from July 21 to September 14, in 2016...... 76 Figure 23. Angler effort by time of day at Wallace Lake June 8 through October 26, 2015 and June 8 through October 12, 2016. Camera one did not function from June 22 to September 14, and Camera three did not function from July 21 to September 14, in 2016...... 76 Figure 24. Relative frequency and relative weight of Brook Trout caught during gill netting surveys at Buster Lake, 1993, 2002, and 2016. No weights were taken in 1993, so relative weights could not be calculated...... 84 Figure 25. Temperature (°C) profile measured at mid-lake in Stanley Lake on May 21, 2016...... 85 Figure 26. Length-frequency histogram (total length TL) of Lake Trout sampled in Stanley Lake, by year using...... 86 Figure 27. Relative weight by total length (TL) of Lake Trout caught in Stanley Lake during gill netting in 2012 and 2016...... 87 Figure 28. Approximate locations of Lake Trout (each point is n = 1) caught during sampling at Stanley Lake in 2012 and 2016...... 88 Figure 29. Length=frequency histogram of total length (TL), and relative weights, of Rainbow Trout collected in gill nets at Jimmy Smith Lake in 2015 and 2016...... 96

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Figure 30. Length-frequency histogram and relative weights of Brook Trout captured at Carlson Lake during gill netting sampling by year. For length frequencies from other years (back to 1999) see the Salmon Region 2015 annual report (Messner et al. 2017). Tiger muskellunge were stocked in 2002, 2006, and 2013...... 103 Figure 31. Relative abundance and mean size of Brook Trout sampled at Carlson Lake, 1998 to 2016. All CPUE values were derived from gill netting surveys, with the exception of 2004* (hoop nets and angling). Error bars on mean TL estimates are standard error...... 104 Figure 32. Length-frequency histogram (TL) of Rainbow Trout captured at Herd Lake during gill netting surveys from 1967 to 2016. Tiger muskellunge were stocked in 2006 and 2013, and bag limits were increased from 6 fish per day to 25 fish per day in 2011...... 111 Figure 33. Relative weights for all Rainbow Trout captured in gill nets at Herd Lake in 2016 (n = 97)...... 112 Figure 34. Approximate locations of sites surveyed along the main stem Salmon River in 2016. See Figure 35 for survey location names...... 124 Figure 35. Mean catch rates (fish/hr) (± SE) for top five target species captured in each of the main stem Salmon River electrofishing transects in September and October, 2016...... 125 Figure 36. Peterson abundance estimates (± 95% confidence intervals) for Westslope Cutthroat Trout and natural origin O. mykiss parr obtained via mark/recapture electrofishing surveys conducted in September and October 2016 on the main stem Salmon River. Density (fish/km) calculated by dividing abundance estimate by transect length (km)...... 126 Figure 37. Westslope Cutthroat Trout length frequency in all main stem Salmon River transects surveyed in September and October, 2016...... 127 Figure 38. Mean relative weights for Westslope Cutthroat Trout, Rainbow Trout, and Bull Trout caught in the main stem Salmon River during electrofishing surveys in September and October, 2016. Box represents Q1 to Q3 and mean, and whiskers show minimum and maximum observed values for each transect. Single dots are for sample size of n = 1. Dashed line at Wr = 100 represents species average based on standard weight for a given length...... 128 Figure 39. Bull Trout length frequency in all main stem Salmon River transects surveyed in September and October, 2016...... 129 Figure 40. O. mykiss length frequency in all main stem Salmon River transects surveyed in September and October, 2016...... 130 Figure 41. Non-target fish length-frequency in 3.2km sub-section of the Deadwater to Indianola transect, Salmon River, September 2016...... 131 Figure 42. Resident Rainbow Trout redds counted during ground surveys in the upper Lemhi River (Beyeler Ranch) and Big Springs Creek (BSC) (Neibaur and Tyler ranches), 1997 - 2016...... 142 Figure 43. Number of Bull Trout redds counted in both survey transects on Alpine Creek, 1998 - 2016...... 142 Figure 44. Number of Bull Trout redds counted in both transects on Fishhook Creek, 1998 - 2016...... 143

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Figure 45. Number of Bull Trout redds counted on Fourth of July Creek, 2003 - 2016...... 143 Figure 46. Number of Bull Trout redds observed in upper Hayden Creek redd count trend transect, 2005 - 2016...... 144 Figure 47. Number of Bull Trout redds observed in the Bear Valley Creek transects, 2002 - 2016...... 144 Figure 48. Map of the Middle Fork Salmon River and its major tributaries, Idaho...... 154 Figure 49. Salmonid densities observed in mainstem MFSR snorkel transects in 2015 and 2016...... 155 Figure 50. Percentage of Westslope Cutthroat Trout greater than 300 mm TL observed during snorkel surveys in the mainstem MFSR, 1971 to 2016...... 156 Figure 51. Percentage of Rainbow Trout/Steelhead (RBT/STHD), Westslope Cutthroat Trout (WCT), and other species (Other) represented in total angler catch during angling surveys on the mainstem MFSR, 1959 to 2016...... 156 Figure 52. Catch per unit effort (CPUE) (# of fish caught per angler hour) estimated from hook and line sampling on the Middle Fork of the Salmon River between 2008 and 2016. The gray dotted line represents the mean (3.9 fish per angler hour) CPUE estimated over this time period...... 157 Figure 53. Percentage of Westslope Cutthroat Trout greater than 300 mm TL caught during angling surveys on the Middle Fork Salmon River, 1959 to 2016...... 157 Figure 54. Length frequency histogram of Westslope Cutthroat Trout caught during angling surveys in 2016 on the Middle Fork Salmon River...... 158

LIST OF APPENDICES Appendix A. Intercept (a) and slope (b) parameters for standard weight (Ws) equations, taken from Blackwell et al. (2000). 10 = + 10(total length (mm)) ...... 163 Appendix B. Bathymetric maps for select high mountain lakes surveyed in 2016...... 164 퐿퐿퐿 푊푊 푎′ 푏 ∗ 퐿퐿퐿 Appendix C. Bathymetric map of Wallace Lake, 2016...... 176 Appendix D. Bathymetric map of Buster Lake, 2016...... 177 Appendix E. Bathymetric map of Jimmy Smith Lake, 2016...... 178 Appendix F. Wild trout redd count trend transect coordinates and lengths...... 179

ix HIGH MOUNTAIN LAKES:

STOCKING AND SURVEYS - 2016

ABSTRACT

Regional fisheries staff coordinated with Mackay Fish Hatchery and Sawtooth Flying Service to stock 38,516 fish in 57 high mountain lakes in the Salmon Region in 2016. A total of 39 lakes were stocked with 27,030 Westslope Cutthroat Trout Oncorhynchus clarkii lewisi, seven lakes with 7,044 triploid Rainbow Trout O. mykiss, six lakes with 3,124 Golden Trout O. mykiss aguabonita, four lakes with 1,019 Arctic Grayling Thymallus arcticus, and one lake with 299 catchable-sized (~250 mm to 300 mm TL) tiger trout Salmo trutta x Salvelinus fontinalis. Aerial stocking in 54 lakes took place between August 17 and September 13, 2016, and backpack stocking for Nez Perce Lake, UP Lake, and Hindman Lake #1 took place on July 6, August 26, and September 20, respectively. Flight costs totaled $5,750 for 2016.

In 2016, fisheries staff attempted to survey 53 high mountain lakes (stocked in 2014) to evaluate growth, survival, and relative abundance of stocked fish (targeted lakes). We surveyed 52 total waterbodies, including 34 targeted and 18 opportunistic. We found fish present in 47 (90%) of the 52 waterbodies sampled. Westslope Cutthroat Trout were found in 39 lakes, Rainbow Trout were found in 13 lakes, apparent Cutthroat x Rainbow Trout hybrids were found in six lakes, Arctic Grayling were found in three lakes, Golden Trout were found in two lakes, Eastern Brook Trout Salvelinus fontinalis were found in one lake, and Bull Trout Salvelinus confluentus were found in one lake.

Amphibians were found in 13 (25%) of the 51 waterbodies where they were surveyed in 2016. Amphibians were found in 26% of lakes that contained fish, and 20% of fishless lakes.

Author:

Jordan Messner, Regional Fisheries Biologist

INTRODUCTION

Anglers fishing high mountain lakes in Idaho have consistently expressed high satisfaction with their experience (IDFG Fisheries Management Plan 2013-2018). High mountain lakes offer diverse angling opportunities in highly scenic areas and are an important contributor to the state’s recreational economy.

Stocking hatchery trout plays a vital role in managing angling opportunities in mountain lakes. Of over 1,000 Salmon Region high mountain lakes, 189 are currently being stocked on a three-year rotation, and four are stocked annually. Idaho Department of Fish and Game (IDFG) primarily stocks four species of trout fry (TL <76 mm) in high mountain lakes: Arctic Grayling Thymallus arcticus (GRA), Golden Trout Oncorhynchus aguabonita (GN), triploid Rainbow Trout O. mykiss (RBT), or Westslope Cutthroat Trout O. clarkii (WCT) fry. In rare circumstances, IDFG also periodically stocks predator species (i.e. tiger muskellunge Esox masquinongy x Esox Lucius [TM] or tiger trout Salmo trutta x Salvelinus fontinalis [BB]) in some high mountain lakes to reduce abundance of other fish species (i.e. Eastern Brook Trout Salvelinus fontinalis [EBT]). The three-year stocking rotation maintains a diverse size structure of fish and ensures fish populations persist in mountain lakes where natural reproduction is not sufficient. The stocking rotation is adjusted annually using the most recent survey information and current management goals.

In 2015, we began an intensive three-year evaluation of the effectiveness of our current high mountain lake stocking program. Over a three year period, we plan to survey the majority of our stocked high mountain lakes to assess fish growth, species composition, and relative abundance (catch per unit effort [CPUE]), similar to what has been done previously in the Panhandle region (Fredericks et al. 2002, Fredericks et al. 2009). Study results will be used to influence stocking decisions (i.e. density, species, or frequency) to improve fishing quality in these high mountain lakes.

OBJECTIVES

Mountain Lake Stocking

1. Provide diverse high mountain lake fisheries throughout the Salmon Region (i.e. diverse species and size structure), with emphasis placed on high-use areas where natural reproduction does not occur.

Mountain Lake Surveys

1. Collect current fish community data (species, growth, relative abundance) from high mountain lakes to inform fisheries management and provide accurate fish population information to anglers.

2. Identify high mountain lakes that currently support naturally reproducing fish populations, and determine whether natural reproduction is adequate for maintaining quality fisheries

STUDY AREA

The Salmon Region contains more than 1,000 high mountain lakes. These range from small ponds that are less than one hectare in size to 70 ha Sawtooth Lake #1 in the Stanley Basin. Regional high mountain lake elevations range from 1,970 m to over 3,000 m. Further

2 information on each specific lake that was surveyed in 2016 can be found in the results section of this chapter. METHODS

Mountain Lake Stocking

As of September, 2016, 189 high mountain lakes throughout the Salmon Region are currently stocked on a three-year rotation. The stocking program helps maintain fish in high mountain lakes that could not otherwise support a fishery (i.e. lack of natural reproduction).

High mountain lake stocking densities and species requests are coordinated between regional staff and Mackay Fish Hatchery staff each spring. Fish are hatched and reared at Mackay Fish Hatchery, who coordinates with the contracting aviation company (Sawtooth Flying Service, McCall, ID) to stock the lakes with the correct species and numbers of fish. As of September 2016, 58 lakes are requested to be stocked on rotation A, 76 lakes on rotation B, and 55 lakes on rotation C. Actually stocking can vary from the request in some years, due to a surplus or deficit in fish, or to accomplish specific management objectives. Rotation C lakes were requested to be stocked in 2016 (Table 1). Each stocking rotation usually requires multiple flights and/or days to complete all stocking for one rotation. Flight routes for each rotation were refined in recent years to keep flight time and fuel costs efficient. Further details of regional aerial stocking methodology were reported in Flinders et al. (2013).

Aerial stocking in 54 lakes took place between August 17 and September 13, 2016, and backpack stocking for Nez Perce Lake, UP Lake, and Hindman Lake #1 took place on July 6, August 26, and September 20, respectively. Total flight costs for 2016 stocking were approximately $5,750, for an average flight cost of $100.88 per lake.

Mountain Lake Surveys

All rotation A lakes that were actually stocked in 2014 (n = 53) were scheduled for surveys in 2016, while rotation B lakes will be sampled in 2017, and rotation C lakes were already sampled in 2015. Salmon Region fisheries staff surveyed 52 high mountain lakes and ponds in the Upper Salmon River drainage in 2016. Thirty-four of 53 (64%) rotation A lakes (target lakes) were successfully surveyed, and 18 other waterbodies were surveyed opportunistically. We sampled the fish community at 32 of the 34 target lakes using one sinking experimental mountain lake gill net fished overnight. Fish and amphibian presence was estimated at the other 20 lakes we surveyed by a combination of angling and visual surveys (n = 11) or by gill netting (n = 9). Monofilament gill nets were 36 m long by 1.8 m deep, and composed of six panels of 10.0, 12.5, 18.5, 25.0, 33.0, and 38.0 mm mesh. Captured fish were measured to the nearest mm total length (TL) and weighed in grams (g). Relative weights (Wr) were calculated using the standard weight (Ws) equation:

( ) = + (total length (mm)) where a = the intercept value퐿퐿퐿10 and푊푠 b =푎 slope푏 ∗ derived퐿퐿퐿10 from Blackwell et al. (2000) (Appendix A). We used Rainbow Trout slope and intercept values for Arctic Grayling also, since Blackwell et al. (2000) did not offer any for Arctic Grayling. The log value is then converted back to base 10, and relative weight is then calculated using the equation:

weight (g) = 100

푊푟 � � ∗ Sagittal otoliths were collected from three푊푠 to five fish in each 10 mm size class for age- structure analysis. Otoliths were prepared for sectioning at the Salmon regional office, and sectioned and digitized at the Idaho Falls (Region 6) Fish and Game office. Cross-sectioned otoliths were photographed at 40x magnification and read by two independent readers. Discrepancies in age estimates between readers were settled by a third reader.

Survey crews visually and subjectively assessed fish spawning potential and the presence of natural reproduction at each lake, based on estimated total spawning area (m2) and the presence of redds, fry, and/or fingerlings. Potential natural reproduction was also determined based on findings derived from fish age distribution data using otoliths. Physical characteristics of each lake, weather conditions at the time of survey, access information and the amount of human use were also recorded. Human use was subjectively classified as none, low, moderate, or high based on the abundance of fire rings, user trails, and litter around the lakes. Bathymetric depth data of the lake was also collected when time allowed, by traversing the lake in a floating packraft and recording GPS waypoints and depths, taken using a handheld depth finder (Hondex PS-7).

At each lake, we assessed presence and relative abundance of amphibians using a modification of the timed visual encounter survey (VES) (Crump and Scott 1994). The main deviation from the VES methodology was that the survey crew performed a full perimeter search without accounting for various habitat types. Survey data was entered into the statewide ‘Lakes and Reservoirs’ database.

RESULTS AND DISCUSSION

Mountain Lake Stocking

Fifty-four rotation C lakes were stocked by fixed-wing aircraft in 2016, and three lakes were stocked by backpacking/horseback crews. In total, 39 lakes were stocked with 27,030 Westslope Cutthroat Trout (WCT), seven lakes with 7,044 triploid Rainbow Trout (RBT), six lakes with 3,124 Golden Trout (GN), four lakes with 1,019 Arctic Grayling (GRA), and one lake with 299 catchable-sized (~250 mm to 300 mm TL) tiger trout (BB) (Table 2).

Mountain Lake Surveys

We surveyed 32 of 53 (60%) rotation A lakes by gill netting, and two by angling in 2016 (Table 3). Eighteen other water bodies were surveyed by a combination of angling and visual surveys (n = 9), or gill netting (n = 9) (Table 4).

Challis Area

Challis Creek Lakes – There are three lakes in the Challis Creek Lakes basin, and two are currently stocked on rotation A (Challis Creek Lakes #2 and #3). Challis Creek Lakes #1, #2, and #3 were first stocked with Cutthroat Trout in 1937, 1959, and 1954, respectively. All three lakes have been stocked with several strains of Cutthroat Trout, including Henry’s Lake strain Yellowstone Cutthroat Trout O. clarkii bouvieri and Westslope Cutthroat Trout, and Rainbow Trout x Cutthroat Trout hybrids over the years.

Challis Creek #1 was also stocked with Brook Trout from 1945 to 1951, and Challis Creek #2 was stocked with adult anadromous steelhead in 2005. Challis Creek Lake #1 was last stocked in 2002 with WCT, and Challis Creek Lake #2 and #3 are currently stocked once every three years with ~750 WCT, and ~950 WCT, respectively. Human use is relatively moderate to high in the Challis Creek Lakes basin, due to easy access via jeep or 4-wheeler, and close proximity to the town of Challis (Tables 3 and 4). Challis Creek Lakes #1, #2, and #3 were surveyed on the evening of June 29, 2016. We constructed bathymetric maps for all three Challis Creek Lakes (Appendix B).

Challis Creek Lake #1 – One gill net was set at Challis Creek Lake #1 for 14.0 hours and caught five WCT and eight WCTxRBT hybrids (combined CPUE 0.93 fish/hr) (Table 5). Total length of WCT ranged from 312 mm to 377 mm, with an average (± standard error) of 349 (± 15.2, n = 5) (Table 5, Figure 1). Total length of WCTxRBT hybrid trout ranged 310 mm to 358 mm TL, with an average of 334 mm (± 5.5, n = 8) (Table 5, Figure 1). Relative weights (with range) were average for both species alike (WCT mean Wr 89.7 (72.8 – 112.8), hybrid mean Wr 94.5 (89.5 – 104.7) (Figure 1). Natural reproduction is definitely occurring, as indicated by the presence of hybrid trout (Figure 1) and multiple age classes of fish that do not coincide with stocking history (Figure 2). Since this basin gets a relatively high level of use (Table 4), providing relatively moderate catch rates and a diversity of sizes and species without stocking is excellent, so no change in stocking is recommended (Table 6). Two anglers fished the lake for a combined 1.66 hours but no fish were caught. No amphibians were observed in 2016 (Table 3).

Challis Creek Lake #2 – One gill net was set in Challis Creek #2 for 14.2 hours and caught 42 WCT (CPUE 2.96 fish/hr) (Table 5). Three anglers also caught another eight fish, during a combined three hours of angling (CPUE 2.67 fish/hr) (Table 5). Total Length of WCT ranged from 112 mm to 316 mm TL, with an average of 207 mm (± 7.4, n = 42) (Table 5, Figure 1). Relative weights were below average for all size classes of fish (mean Wr 85.2, [range 40.8 – 99.3) (Figure 1). Natural reproduction is likely, as indicated by the presence of age classes of trout that do not reflect stocking history (Figure 2). Catch rates at this lake are relatively high, and fish size may improve from reduced stocking. Stocking density is currently very high (368 fish/ha) (Table 5). We recommend reducing stocking density to see if fish size improves (Table 6). No amphibians were observed in 2016 (Table 3).

Challis Creek Lake #3 – One gill net was set in Challis Creek #3 for 15.3 hours and yielded no fish. This is the second consecutive sampling event in 15 years that has yielded no fish. This lake likely experiences winter kill on occasion. We recommend halting stocking and leaving this lake as fishless (Table 6). No amphibians were observed in 2016 (Table 3).

Twin Creek Lakes There are two larger and relatively deeper lakes, and four shallower ponds in the Twin Creek Lakes basin. Twin Creek Lake #2 is the only lake currently stocked (on a three-year rotation with ~150 RBT). Twin Creek #2 is also the only lake that IDFG has record of ever being stocked. It was first stocked in 1949 and 1951 with Brook Trout (EBT), and has been stocked several times with Cutthroat Trout and Rainbow Trout since 1959. Twin Creek Lake #6 (the uppermost lake in the basin),

despite no stocking record, contains naturally reproducing trout. Although the lake was not officially surveyed in 2016, trout appeared to be abundant. Human use is relatively moderate at the Twin Creek Lakes, due to easy hiking access from Twin Peak Lookout (Tables 3 and 4). Twin Creek #2 was surveyed on the evening of August 6, 2016.

Twin Creek Lake #2 – One gill net was set in Twin Creek Lake #2 for 15.8 hours and caught 17 trout that were apparent WCTxRBT hybrids (CPUE 1.08 fish/hr) (Table 5). Trout ranged in length from 136 mm to 368 mm TL and averaged 270 mm (± 13.9, n = 17) (Table 5). Relative weights were generally above average (mean Wr = 109.5, range 96.2 – 130.3) (Figure 1). It seems likely that natural reproduction is occurring here since trout were apparent hybrids (which have not been stocked), and we estimated all age classes were present from age-3 to 7 (Figure 2). Despite the combination of stocking and apparent natural reproduction, fish are not overabundant and stunted, and this lake functions well as a fishery that provides moderate catch rates (Table 5) with relatively large fish (Figure 1). With nearby Twin Creek Lake #6 likely offering higher catch rates of smaller fish solely through natural reproduction, the two complement each other well. No change is recommended (Table 6).

West Fork Bear Creek Lakes – There are two lakes (#1 and #2) and one small pond in the West Fork Bear Creek Lakes basin. WF Bear Creek Lake #1 (the only one currently stocked) was first stocked in 1990 with WCT, and since 1996 has been stocked with ~200 WCT on a three-year rotation. WF Bear Creek Lake #2 does not have any stocking history, but fish movement is possible between #1 and #2. Human use in the West Fork Bear Creek Lakes basin appears to be relatively low, due to requiring over two miles of cross country travel through heavy downfall to access the basin (Table 3). WF Bear Creek Lake #1 was surveyed the evening of August 7, 2016.

W F Bear Creek Lake #1 – One gill net was set for 13.2 hours and captured 23 WCT (CPUE 1.74 fish/hr) (Table 5). An additional six WCT were caught during one hour of angling (CPUE 6.00 fish/hr). WCT ranged in size from 156 mm to 327 mm TL and averaged 238 mm (± 9.5, n = 23) (Table 5, Figure 1). Relative weights were generally average (mean Wr = 92.2, range 81.2 – 105.4) (Figure 1). Otolith analysis suggests that, in addition to stocking, WCT are naturally reproducing in the lake (Figure 2). Age data also showed that fish are fairly long- lived (up to age 10), with slow growth after age 6 (Figure 2). As angling effort is relatively low here and gill net catch rate was relatively high, a halt in stocking may help decrease abundance and increase growth for naturally reproducing WCT in the lake (Table 6). We recommend to re-evaluate this lake in 2019 to see if natural reproduction is adequate for sustaining the fishery, and whether trout size has improved. Four Western Toad adults were also observed at the lake in 2016 (Table 3).

Slate Creek Area

Slate Creek Drainage – The Slate Creek drainage contains four large lakes. According to IDFG historical stocking records, Crater Lake was first stocked in 1950, Hoodoo Lake was first stocked in 1959, and Ocalkens Lakes #1 and #2 were first stocked in 1967, all with Cutthroat Trout. With the exception of Ocalkens Lake #2 receiving Rainbow Trout in 1987, none of these lakes have ever been stocked with anything other than Cutthroat Trout (although several strains of Cutthroat Trout were stocked). Currently, Hoodoo Lake

6 is stocked once every three years with ~250 WCT, Crater Lake with ~875 WCT, and Ocalkens #1 and #2 with ~500 and ~750 WCT, respectively. The lakes in the Slate Creek drainage were classified as receiving a relatively low to moderate level of human use in 2016 (Table 3). Even though access is good to these lakes, their remoteness likely affects angler visitation. These lakes were surveyed between July 11th and July 13th, 2016. We constructed bathymetric maps for all four of these lakes in 2016 (Appendix B).

Hoodoo Lake –One gill net was set for 13.5 hours and did not capture any fish in Hoodoo Lake in 2016. This is the second sampling event in the last five years that has yielded no fish in Hoodoo Lake. The lake appears deep enough to support fish, but they do not seem to persist long-term. In 2007, gill netting found several size classes of WCT in the lake, so they may persist in some years (perhaps even naturally reproduce), but experience winterkill in others. Recommend continuing with stocking and re-evaluate in the near future to determine whether this lake should be removed from the stocking rotation (Table 6). Three amphibian egg masses were found in the lake in 2016, and were believed to be Columbia Spotted Frogs (Table 3).

Crater Lake– One gill net was set for 12.4 hours in 2016, and captured 27 WCT (CPUE 2.18 fish/hr). WCT ranged in length from 210 mm to 347 mm TL and averaged 308 mm (± 5.7, n = 27) (Figure 3, Table 5). Although fish were relatively long (TL), relative weights were below average (mean Wr 77.4, range 65.5 – 91.3] (Figure 3). Some natural reproduction does appear to be occurring (Figure 4), and in addition to stocking, is producing a relatively high abundance of fish. This may contribute to the observed slow growth after age 5 (Figure 4) and below average relative weights. Since use is moderately high in this area however, no change is recommended (Table 6). No amphibians were documented in 2016 (Table 3).

Ocalkens Lake #1 – We captured 14 WCT during 11.8 hours of gill netting (CPUE 1.19 fish/hr) in 2016 (Table 5). WCT ranged in length from 154 mm to 354 mm TL, and averaged 257 mm (± 17.2, n = 14) (Table 5, Figure 3). Relative weights were average (mean Wr 96.4, range 82.3 – 110.5) (Figure 3). Some level of natural reproduction appears to be occurring in the lake, as evidenced by the presence of all age classes from age-3 to age-7 (Figure 4). This lake currently offers a moderate abundance of fish with good size, growth, and relative weights (Figure 4) to provide a fishery, so no change is recommended (Table 6). No amphibians were found in 2016 (Table 3).

Ocalkens Lake #2 – Ocalkens Lake #2 was not gill netted in 2016 because the survey crew felt they could see the entire bottom of the lake, and no fish were observed. This is the second time we have surveyed Ocalkens #2 (first time was 1984) and determined it to be fishless. The survey crew in 2016 also noted that lake depth was largely less than 1.75 meters, and was deeper only in a very small area near the inlet. The lake did not appear suitable to overwinter fish, therefore we recommend removing from the stocking rotation (Table 6). No amphibians were observed in 2016 (Table 3).

Elk Lake – According to our records Elk Lake was first stocked in 1950 with Cutthroat Trout, and has been stocked at least 34 times since then. All recorded stocking events

7 were with Cutthroat Trout, except once in 1951 when Rainbow Trout were stocked. Despite no record of being stocked, Brook Trout were the only species documented in the lake in 1988. Elk Lake is now stocked on a three year rotation with ~675 WCT. In 2016, the survey crew estimated that human use was very low to none, since access is solely cross-country and is approximately 4 miles through heavily timbered, steep terrain (Table 3).

We captured 30 WCT during 13.2 hours of gill netting (CPUE 2.27 fish/hr) in 2016, and another 12 WCT in one hour of angling (CPUE 12.00 fish/hr) (Table 5). WCT ranged in length from 160 mm to 268 mm TL, and averaged 217 mm (± 6.7, n = 30) (Table 5, Figure 3). Relative weights varied with size, but overall were slightly below average (mean Wr 86.7, range 69.2 – 112.8) (Figure 3). Natural reproduction appears to be occurring in the lake at a fairly high rate, and small, slow growing fish are highly abundant (Figure 4, Table 5). Recommend halting stocking to see if natural reproduction can solely support this low use fishery (Table 6). Two Western Toad adults were found in 2016 (Table 3).

Swimm Lake – According to IDFG records, Swimm Lake was first stocked in 1949 with Cutthroat Trout, and has never been stocked with any other species. Swimm Lake is now stocked with ~870 WCT, once every three years. In 2016, the survey crew estimated that human use was low due to access difficulty, as it is roughly a 12 mile hike to get to the lake, with four of that being difficult cross-country (Table 3). The last time Swimm Lake was surveyed, in 2001, it was classified as fishless, despite having been stocked in 1996 and 1999.

We captured 16 WCT during 13.0 hours of gill netting (CPUE 1.23 fish/hr) in 2016 (Table 5). Fish ranged in length from 276 mm to 366 mm TL, and averaged 334 mm (± 6.0, n = 16) (Table 5, Figure 3), with excellent, above average relative weights (mean Wr = 116.6, range 101.8 – 132.8) (Figure 3). Some level of natural reproduction may be occurring in the lake, but all captured fish were very close in size (Figure 3) and age (Figure 4), not exceeding 6 years. This, in combination with the fact that the lake was found to be fishless in 2001, suggests fish kills may occur (perhaps infrequently). At the current stocking density (131 fish/ha), relative abundance is moderately high and fish size is adequate for providing a quality fishery (Table 5). Recommend continuing current stocking program to ensure long-term fish persistence (Table 6). No amphibians were found in 2016 (Table 3).

East Basin Creek Lakes– The first recorded stocking event for East Basin Creek Lake #1 was in 1977 with Cutthroat Trout, and it is now stocked on a three year rotation with ~480 WCT. East Basin Creek Lake #2 was also stocked with Cutthroat Trout from 1977 to 1987, but was discontinued after being deemed unsuitable for fish persistence. In 2016, the survey crew estimated that human use was low at the East Basin Creek Lakes (Table 3). Access requires a long 4-wheeler, motorcycle, or horseback ride (Table 3). The last time East Basin Creek Lake #1 was surveyed, in 1976, WCT were caught.

We captured 12 WCT during 13.5 hours of gill netting (CPUE 0.89 fish/hr) in 2016 (Table 5). No fish were caught during 0.5 hours of angling. Fish caught in the gill net ranged in length from 313 mm to 496 mm TL, and averaged 374 mm (± 18.1, n = 12), and relative weights were well above average (mean Wr 130.4, range 113.2 – 143.7) (Table 5, Figure 3). The largest two fish we caught weighed well over 1kg, thus exceeding our scale capacity. We were not able to determine relative weights for those

two fish. Based on ageing data, it appears that no natural reproduction is occurring in the lake (Figure 4). We detected age-5 fish (stocked in 2011) and age-8 fish (stocked in 2008), and nothing else. Consequently, with low fish density the lake currently grows very large, heavy fish (Figure 3). Since this lake is infrequently fished, the current stocking density should continue (254 fish/ha) (Table 5 and 6) to maintain a rare trophy fishing option. Both, Columbia Spotted Frogs and Western Toads, were found in 2016 (Table 3).

Boulder-White Clouds - Little Boulder Creek

Spring Basin – Little and Big Frog lakes are the only two named lakes in Spring Basin, and the only two that have ever been stocked. There are also eight smaller ponds in the basin. The first stocking records in Spring Basin were Cutthroat Trout in Big Frog Lake in 1977 and in Little Frog in 1987. However, stocking likely occurred before then, as fish presence was documented prior to those stocking records in both Big Frog Lake in 1956 and Little Frog Lake in 1968. Little Frog Lake is no longer stocked, but Big Frog Lake is currently stocked once every three years with approximately 1,000 WCT. Big and Little Frog lakes were gill netted on July 20th, 2016. Human use at Big Frog Lake appears to be very high (Table 3), as this is one of the first lakes visitors arrive at in the very popular Little Boulder Creek Basin in the Boulder-White Cloud Mountains.

Big Frog Lake – We caught 32 WCT in 15.5 hours of gill netting in Big Frog Lake (CPUE 2.06 fish/hr) (Table 5). Fish length ranged from 103 mm to 425 mm TL and averaged 256 mm (± 19.9, n = 32), with average relative weights calculated for all size classes (mean Wr 92.4, range 80.2 – 109.2) (Table 5, Figure 5). Otolith analysis suggests natural reproduction does occur in Big Frog Lake (Figure 6), and surveyors noted that even though there is not a lot of spawning habitat around the lake, abundant shoreline cover may contribute to increased productivity. This lake currently supports a relatively high abundance and wide range of size classes of trout in good condition. Fish size may be improved even further if stocking were discontinued, but due to its relatively high level of use, we suggest no change for Big Frog Lake (Table 6). Columbia Spotted Frogs and Western Toads were observed in 2016 (Table 3).

Little Frog Lake– We captured seven WCT in 14.5 hours of gill netting in Little Frog Lake in 2016 (CPUE 0.48 fish/hr) (Table 5). Fish lengths ranged from 115 mm to 336 mm TL and averaged 282 mm (± 31.0, n = 6), and relative weights overall were average (mean Wr 93.2, range 87.1 – 108.8) (Table 5, Figure 5). Otolith analysis suggests either some very low level of natural reproduction is present in the lake, or young fish are immigrating to the lake from Big Frog Lake when the inlet is functional (Figure 6). We believe the latter to be true, as there is very poor spawning habitat at Little Frog Lake. Length-at-age information also suggests fish that colonize Little Frog Lake experience excellent growth, probably due to decreased competition for forage, compared to nearby Big Frog Lake. Estimated age 4 fish in Little Frog Lake were slightly larger than age 4 fish in Big Frog Lake (Figure 6). However, the low level of angler-use at this lake does not justify adding this lake back to the stocking rotation. With our current stocking strategy, Little Frog Lake offers an opportunity to catch slightly larger trout nearby to Big Frog Lake, so no change is recommended (Table 6). Both, Columbia

Spotted Frog and Western Toad adults were observed at Little Frog Lake in 2016 (Table 4).

(Little) Boulder Chain Lakes – There are 13 lakes and three ephemeral pools within the Boulder Chain Lakes, and none are currently stocked. IDFGs earliest records of stocking the Little Boulder Chain Lakes date back to the 1970s when Cutthroat Trout were stocked in Lodgepole Lake, Lonesome Lake, Headwall Lake, and Hourglass Lake. Since then, Hidden Lake and Sliderock Lake have also been stocked, but no lakes in the Boulder Chain series have been stocked since 1999. Both WCT and RBT have been stocked in this series of lakes at one time or another and the availability stream spawning habitat and connectivity in the Little Boulder Chain Lakes is believed to aid in the success of natural reproduction and distribution of fish throughout the basin. Even though Cutthroat Trout have been stocked more often than Rainbow Trout, it appears that Rainbow Trout are the dominant species in the lower lakes of this series. Human use is generally high in the Little Boulder Chain Lakes, but seems to decrease as elevation and distance from the trailhead increases (Table 4). The Little Boulder Chain Lakes were angled and gill netted between July 21st and July 23rd, 2016. The lakes are listed below in order of occurrence from the trailhead.

Willow Lake – 161 RBT and one Bull Trout (BUT) were caught during 12.0 hours of gill netting (CPUE 13.42 fish/hr) in Willow Lake (Table 5). RBT ranged from 80 mm to 339 mm TL and averaged 144 mm (± 5.0, n = 161) and the BUT measured 315 mm TL (Figure 5). The majority of RBT caught in Willow Lake showed poor relative weight values (mean Wr = 75.2, range 39.0 – 97.1), but relative weight of the BUT we caught was above average for the species across its range (Wr = 112.2) (Figure 5). Willow Lake has been surveyed three times previously (1968, 2000, and 2001), and this is the first time Bull Trout have been observed. As the lowest lake in the Boulder Chain Lakes series, the Bull Trout may move in and out of this lake seasonally from the creek/outlet, draining to the East Fork Salmon River. Good spawning habitat in both the inlet and outlet to Willow Lake likely support a relatively high level of RBT natural reproduction. We observed all age classes of RBT from age 2 to age 7, with the majority of fish caught being age 2 and 3 (Figures 5 and 6). Willow Lake seemingly receives high angler visitation (Table 4), being the first in the “Chain Lakes”, and thus appropriately provides very high catch rates, even though RBT growth may be somewhat stunted. No management changes are recommended at this time (Table 6). Both, Columbia Spotted Frog and Western Toad adults were observed at Willow Lake in 2016 (Table 4).

Hatchet Lake – 136 RBT were caught during 18.1 hours of gill netting (CPUE 7.51 fish/hr) in Hatchet Lake (Table 5). RBT ranged from 80 mm to 211 mm TL and averaged 160 mm (± 3.2, n = 136), and all relative weight values were generally below average (mean Wr = 72.7, range 27.8 – 96.8) (Figure 5). As one of the lowest lakes in the Boulder Chain Lakes series, Hatchet Lake receives a very high level of angler visitation, like Willow Lake (Table 4). Also similar to Willow Lake, natural reproduction appears to be high in Hatchet Lake (Table 5) with high CPUE and very slow growth of RBT (Figure 6). Although fish size could use improvement, this lake currently offers much higher catch rates than many other lakes in the Boulder Chains, and thus is serving an important role in the basin as a whole. No management changes are recommended at this time

(Table 6). Western Toad adults were observed at Hatchet Lake in 2016 (Table 4).

Shelf Lake – 78 RBT were caught during 16.0 hours of gill netting (CPUE 4.88 fish/hr) in Shelf Lake (Table 5). Similar to Willow and Hatchet, RBT ranged from 94 mm to 244 mm TL and averaged 184 mm (± 2.6, n = 78), and relative weights were generally below average (mean Wr 74.6, range 57.9 – 96.1) (Figure 5). Shelf Lake also receives a high level of angler visitation due to being one of the lower lakes in the Boulder Chains, and having trailed access all the way to the lake (Table 4). Shelf Lake supports a relatively high level of natural reproduction as well, resulting in high catch rates of relatively small size trout (Figure 5). We observed RBT from age-5 to age-8 in Shelf Lake, none of which grew larger than 244 mm TL (Figure 6). The only recommended action would possibly be to reduce RBT abundance in the Boulder Chains to improve fish growth, but that would likely prove very difficult given the suspected degree of natural reproduction, and high level of connectivity between lakes. Therefore, no management changes are recommended at this time (Table 6). We did not observe any amphibians at Shelf Lake in 2016 (Table 4).

Sliderock Lake – 90 RBT were caught during 11.7 hours of gill netting (CPUE 7.69 fish/hr) in Sliderock Lake (Table 5). RBT ranged from 92 mm to 275 mm TL and averaged 182 mm (± 5.3, n = 90) (Figure 5). Relative weights were generally below average for all size classes (mean Wr = 74.3, range 46.7 – 117.8) (Figure 5). Shelf Lake receives a relatively high level of angler visitation due to being one of the lower lakes in the Boulder Chains, and having trailed access all the way to the lake (Table 4). Good spawning habitat in both the inlet, outlet, and around the shoreline at Sliderock Lake seem to support a relatively high level of natural reproduction, similar to Willow, Hatchet, and Shelf Lake, resulting in high catch rates of relatively small RBT (Figure 5). We observed all age classes of RBT from age-2 to age-8, none of which reached a larger size than 275 mm TL (Figure 6). It would be beneficial to improve size of RBT in at least one of the lower Boulder Chain Lakes, but this would likely be very difficult considering the high level of natural reproduction taking place in these lakes. Other than potentially improving size, no management changes are recommended at Sliderock Lake (Table 6). We did not observe any amphibians at Sliderock Lake in 2016 (Table 4).

Hourglass Lake – 33 RBT were caught during 14.5 hours of gill netting (CPUE 2.28 fish/hr) and 10 RBT were caught during one hour of angling (CPUE 10.00 fish/hr) in Hourglass Lake (Table 5). Gill netted RBT ranged from 147 mm to 238 mm TL and averaged 192 mm (± 4.3, n = 33), and their relative weights were mostly below average (mean Wr = 79.4, range 66.7 – 98.3) (Figure 5). Again, being one of the lower lakes in the Boulder Chain Lakes series, Hourglass Lake receives a very high level of angler visitation, similar to the others previously mentioned (Table 4), even though it is 3 miles further in the drainage than Willow. Natural reproduction also appears to be high in Hourglass Lake, as evidenced by high catch rates (Table 5) and very slow growth (Figure 6). It may be beneficial to improve size of RBT in some of the Boulder Chain Lakes, including this one, but this would be very difficult considering the high level of natural reproduction taking place in these lakes. No management changes are recommended at this

11 time (Table 6). We did not observe any amphibians at Hourglass Lake in 2016 (Table 4).

Hummock Lake – 57 RBT were caught during 15.5 hours of gill netting (CPUE 3.68 fish/hr) and 51 were caught during two hours of angling (CPUE 25.50 fish/hr) in Hummock Lake (Table 5). Gill netted RBT ranged from 81 mm to 232 mm TL and averaged 159 mm (± 7.4, n = 45), and relative weights were once again mostly below average (mean Wr = 87.3, range 37.5 – 139.4) (Figure 5). Hummock Lake also receives a very high level of angler visitation (Table 4), so high catch rates likely lend themselves well to angler satisfaction. Similar to those lakes previously mentioned, natural reproduction appears to be very high in Hummock Lake, as evidenced by high catch rates (Table 5) and slow growth (Figure 6). Improving fish size would be difficult given the high level of natural reproduction taking place here, but would be beneficial. No management changes are recommended (Table 6). Both Columbia Spotted Frog and Western Toad adults were observed at Hummock Lake in 2016 (Table 4).

Hidden Lake – 26 RBT were caught during two hours of angling (CPUE 13.00 fish/hr) in Hidden Lake (Table 5). The lake was not gill netted in 2016, so RBT were not measured, but all fish caught were estimated to be no larger than 250 mm TL. Human use and size and age structure of RBT in Hidden Lake is likely very similar to that which was observed in Hummock, considering they are connected by approximately 15 meters of flowing water. If there are any lakes in the “Chain Series” that may be easier to reduce RBT abundance to improve size, it is Hourglass, Hidden, and Hummock, based on their location in the series. If this management option is pursued, start at these three lakes. At this time however, we recommend no change (Table 6). No amphibians were observed in 2016 (Table 4).

Scoop Lake – Scoop Lake was not gill netted in 2016, but three RBT and one WCT were caught during two hours of angling (CPUE 1.50 fish/hr) (Table 5). Several other WCT were visually observed, but not caught. The survey crew noted that all RBT in the lake appeared to be between 150 mm to 250 mm TL, similar to the other lakes previously mentioned, but WCT in the lake were larger (approximately 350 mm to 500 mm TL) (Figure 5). Fish were not weighed, so relative weights are not known. Scoop Lake likely receives a relatively moderate level of angler visitation (Table 4), as it is in a very popular area and has trailed access, but is high in the basin. Similar to those lakes previously mentioned, RBT natural reproduction appears to be relatively high in Scoop Lake as evidenced by high catch rates of small RBT. However, this is the first lake in the Boulder Chain series where we observed WCT, which seem to experience better growth than RBT. Recommend re-establishing WCT stocking at Scoop, at low density, to provide more species diversity in the basin (Table 6). Columbia Spotted Frog were observed at Scoop Lake in 2016 (Table 4).

Headwall Lake – One WCT was caught during two hours of angling (CPUE 0.50 fish/hr) in Headwall Lake (Table 5). The lake was not gill netted, but surveyors noted catching one WCT that measured approximately 460 mm TL (no weight taken). Surveyors also noted that no fish were observed from shore at Headwall Lake in 2016, so abundance is probably extremely low. Human-use was estimated as moderate in 2016 (Table 4), but it is likely relatively much lower

than for most other lakes in the Boulder Chains, due to requiring cross country navigation for access. No fish were aged from Headwall Lake in 2016, but if WCT natural reproduction is occurring, it is at an extremely low rate. Recommend re- establishing WCT stocking in Headwall Lake at a relatively low density (~150 fish/ha), to increase catch rates, but continue to manage for quality size (Table 6). No amphibians were observed at Headwall Lake in 2016 (Table 4).

Lonesome Lake – Two anglers fished Lonesome Lake for 1.5 hours and caught no fish. Lonesome Lake is the highest lake in the Boulder Chain series, and receives relatively low use (Table 4). Surveyors observed several large WCT in the lake, but were unable to catch any. The lake was last stocked in 1999, so some very low level of natural reproduction must be present for WCT to still persist. This is the highest and one of the least used lakes in the Boulder Chain series, so no change is recommended (continue to manage for larger size WCT) (Table 6). No amphibians were observed at Lonesome Lake in 2016 (Table 4).

Little Boulder Creek Lakes – There are 10 lakes in the upper portion of Little Boulder Creek, past the trail split up to the Boulder Chain Lakes. Only two lakes (Castle Lake and Shallow Lake) are currently stocked. According to IDFG historical stocking records, Castle Lake and Shallow Lake have both been stocked primarily with WCT since the 1970s, and are currently stocked with ~650 and ~380 WCT, respectively, once every three years. Both lakes have also been stocked with RBT and WCTxRBT hybrids on a few occassions. Rock Lake and Glacier Lake are two other lakes that have been stocked in this area, but have not been stocked since 1984 and 1999, respectively. Human use is lower here compared to the Boulder Chain Lakes area, and generally decreases further up the drainage (Tables 3 and 4). Five lakes in the Upper Little Boulder Creek basin were surveyed between July 22nd and July 24th, 2016. The lakes surveyed are listed below in order of increasing elevation.

Castle Lake – We captured 12 RBT, five WCT, and two WCTxRBT hybrids in 12.1 hours of gill netting at Castle Lake in 2016 (CPUE 1.16 fish/hr) (Table 5). RBT ranged in length from 90 mm to 270 mm TL, and averaged 164 mm (± 19.7, n = 12), WCT ranged in length from 304 mm to 330 mm TL, and averaged 318 mm (± 6.4, n = 5), and hybrids ranged from 252 to 272 mm TL, and averaged 262 (n = 2) (Table 5, Figure 5). Relative weights for all species in all size classes were below average (RBT mean Wr = 77.2; range 67.1 – 87.8; WCT mean Wr = 79.7; range 62.7 – 93.2; hybrid mean Wr = 81.2; range 68.8 – 93.7) (Figure 5). Natural reproduction is occurring in or near Castle Lake, as evidenced by the presence of multiple year classes outside the historic stocking regime and the presence of hybrids (Figure 6). Although RBT could likely persist in the lake without stocking, stocked WCT (and their hybrids) appear to grow better than RBT in the lake (Figure 6), so stocking should continue (Table 6), perhaps at an even higher density to boost the WCT population. No amphibians were observed in 2016 (Table 3).

Noisy Lake – Noisy Lake was not gill netted in 2016, but we caught 15 WCTxRBT hybrids in one hour of angling (CPUE 15.00 fish/hr) (Table 5). Surveyors noted that fish lengths ranged from approximately 150 mm to 400 mm, but no fish were actually measured or weighed. Likely a combination of high rates of natural reproduction, as well as dispersion of fish from other lakes, adds to this lake offering high catch rates of relatively smaller fish (though fish can

reach at least ~400 mm TL). Noisy Lake shows very little sign of human use (Table 4), so does not call for any changes in management (Table 6), especially since it currently provides a fishery without stocking. No evidence of amphibian presence was observed at Noisy Lake, but unidentified egg masses were observed in a nearby ephemeral pool.

Quiet Lake – Five RBT were captured during one hour of angling at Quiet Lake in 2016 (CPUE 5.00 fish/hr) (Table 5). The lake was not gill netted, but fish caught during angling ranged in length from 152 to 432 mm TL, and averaged 279 mm (± 56.0, n = 5) (Table 5, Figure 5). No weights were taken. Whether some low level of natural reproduction is taking place to sustain RBT in Quiet Lake, or fish colonize the lake from other nearby lakes, catch rates are good and fish size is above average for the area. Despite being classified as having a high level of human-use (Table 4), no management changes are suggested (Table 6). Continue managing for above average catch rates and moderate sizes of fish. No amphibians were observed in 2016 (Table 4).

Scree Lake – 54 WCT were caught during 1.5 hours of angling (CPUE 36.00 fish/hr) (Table 5). Fish lengths ranged 176 mm to 292 mm TL and averaged 234 mm (± 7.3, n = 20) (Table 5, Figure 5). Relative weights were generally below average (mean Wr 81.5 [range 69.4 – 103.7]) (Figure 5). Based on otolith analysis, natural reproduction is certainly occurring (Figure 6), likely at a relatively high rate. However, WCT size variation is fairly wide and fish appear to be in good condition, so maintenance of high catch rates with moderate fish size works well in this lake, without stocking. Human-use is relatively low (Table 4). No management changes are recommended (Table 6). We did not observe any sign of amphibians in 2016 (Table 4).

Shallow Lake - 16 WCT were caught during 13.5 hours of gill netting (CPUE 1.20 fish/hr) and one was caught during one hour of angling (CPUE 1.00 fish/hr) in Shallow Lake (Table 5). Gill netted WCT ranged from 147 mm to 298 mm TL and averaged 189 mm (± 12.0, n= 16), and relative weights were slightly below average (mean Wr = 89.9, range 68.7 – 103.1) (Figure 5). Angler visitation is very low at Shallow Lake (Table 4), due to its remoteness, and although WCT size structure is similar to in Scree Lake (Figure 5), catch rates are lower, and growth rates appear higher as a result (Figure 6). All of the lakes in the Upper Little Boulder Creek Drainage appear to currently offer diverse catch rates, species, and size structure, so no management changes are recommended (Table 6). We did not observe any sign of amphibians in 2016 (Table 4).

Boulder-White Clouds - Big Boulder Creek

Big Boulder Lakes – There are 19 named lakes and over a dozen small ponds in the Big Boulder Creek drainage. According to IDFG historical stocking records, Boulder Lake was the first lake stocked in this basin, in 1935, and Sheep Lake was the first lake in the Salmon Region to be stocked with GRA, in 1971. Overall, 13 lakes in the basin have been stocked since the 1970s, and 11 lakes are currently stocked on a three year rotation (Table 3). Once every three years, Goat Lake receives ~1,150 WCT, Feldspar Lake receives ~500 GRA, Cove Lake receives ~1,100 WCT, Gentian Lake receives ~325 RBT, Snow Lake receives ~370 WCT, Sapphire Lake receives ~1,250 WCT,

Cirque Lake receives ~1,150 WCT, Sheep Lake receives ~500 WCT, Slide Lake receives ~270 WCT, Tin Cup Lake receives ~1,000 GRA, and Gunsight Lake receives ~450 WCT. Stocking was discontinued at Boulder Lake in 1984 and at Island Lake in 1999, both due to suspected natural reproduction sufficient for maintaining fish populations. Human-use is generally moderate to high in this popular lake basin, but can be fairly low at some of the more remote and less accessible lakes (Table 3). Twelve lakes in the Big Boulder Creek Drainage were surveyed between July 25th and July 27th, 2016.

Goat Lake - 19 WCT and seven RBT were caught during 13.5 hours of gill netting (CPUE 1.93 fish/hr) in Goat Lake (Table 5). WCT lengths ranged from 84 mm to 372 mm TL, and averaged 256 mm (± 19.0, n = 19), and RBT ranged from 162 mm to 353 mm TL and averaged 288 mm (± 27.2, n = 7) (Figure 7). Relative weights were generally average or slightly below average (WCT mean Wr = 94.8, range 71.7 – 122.7; RBT mean Wr = 81.7, range 69.0 – 88.8) (Figure 7). Even though Goat Lake is one of the lowest lakes in the Big Boulder Lakes area, angler visitation does not appear to be high (Table 3), perhaps because most visitors to the area are setting out for the higher lakes in the basin. Natural reproduction appears to be occurring (Figure 8), but catch rates remain relatively moderate and fish size is relatively good, so no management changes are recommended (Table 6). No amphibians were observed at Goat Lake in 2016 (Table 3).

Feldspar Lake – 26 RBT and three GRA were caught during 14.9 hours of gill netting (CPUE 1.95 fish/hr) in Feldspar Lake (Table 5). RBT lengths ranged from 153 mm to 306 mm TL, and averaged 233 mm (± 8.1, n = 26), and GRA ranged from 230 mm to 308 mm TL and averaged 257 mm (± 31.4, n = 3) (Figure 7). Relative weights for all species and all size classes were below average (mean GRA Wr = 71.7, range 63.3 – 76.2; mean RBT Wr = 78.5, range 66.2 – 92.7) (Figure 7). Feldspar Lake sits approximately one mile further up the inlet to Goat Lake, and as such likely receives low angler use (Table 3). Natural reproduction by Rainbow Trout in the lake appears to be occurring at a fairly high rate, which is contributing to overabundance and slow growth. The Grayling growth rate seems to be higher than for Rainbow Trout in the lake (Figure 8), but could probably be improved further if Rainbow Trout abundance was reduced. At this time however, no management changes are recommended, due to the difficulties associated with reducing abundance of a naturally reproducing population (Table 6). No amphibians were observed at Feldspar Lake in 2016 (Table 3).

Cove Lake – 18 RBT and three WCT were caught during 17.0 hours of gill netting (CPUE 1.24 fish/hr), and three more RBT were caught during one hour of angling (CPUE 3.00 fish/hr) in Cove Lake (Table 5). RBT lengths ranged from 183 mm to 404 mm TL, and averaged 293 mm (± 15.6, n = 18), and WCT ranged from 283 mm to 416 mm TL and averaged 340 mm (± 48.3, n = 3) (Figure 7). Not all fish were weighed, but for the fish that were, relative weights were below average and seemed to be lower as total length increased (mean RBT Wr = 74.2, range 52.3 – 83.3; mean WCT Wr = 91.8, range 88.7 – 94.9) (Figure 7). Cove Lake is the first lake in the upper series of Big Boulder Lakes, so human use is relatively high (Table 3). Natural reproduction appears to be occurring in or near the lake, at least by Rainbow Trout (Figure 8), but catch rates remain moderate

15 and fish size is decent. No management changes are recommended (Table 6). No amphibians were observed at Cove Lake in 2016 (Table 3).

Gentian Lake – One WCT was caught during 14.8 hours of gill netting (CPUE 0.07 fish/hr), measuring 180 mm TL (Table 5, Figure 7). No fish were caught during 0.3 hours of angling. Relative weight was average (Figure 7). Gentian Lake sits in a flat above Cove Lake, with Snow and Boulder lakes. There is likely seasonal connectivity between the three lakes. Human-use is relatively low at Gentian Lake (Table 3). Gentian Lake is very small, but seems to have adequate depth and spawning opportunity to support stocked fish. However, RBT are currently stocked, and only WCT are found in this lake as well as in Snow and Boulder lakes. As Snow Lake is the only one currently stocked with WCT, it may be the source for WCT colonization into the other two lakes. Considering their relatively low catch rates, the lakes in this basin do not promote very high fish growth. Recommend halting stocking to see if natural reproduction in the basin is enough to sustain a fishery, and perhaps improve overall fish size (Table 6). No amphibians were observed at Gentian Lake in 2016 (Table 3).

Boulder Lake – Boulder Lake was not gill netted in 2016, but one WCT was caught during two hours of angling (CPUE 0.50 fish/hr), measuring approximately 250 mm TL (Table 5, Figure 7). Boulder Lake sits in a flat above Cove Lake, with Snow and Gentian Lakes. Human-use is relatively low (Table 4). Although Boulder Lake is not stocked, surveyors noted seeing many WCT in the 150 mm to 250 mm range in the lake, but could not get them to take flies. Nearby Snow Lake is stocked with WCT, and also seems to support natural reproduction, so it seems likely that fish are colonizing Boulder Lake from there. No management changes are recommended (Table 6). No amphibians were observed at Boulder Lake in 2016 (Table 4).

Snow Lake – We caught 25 WCT in 12.6 hours of gill netting (CPUE 1.98 fish/hr), and two WCT during two hours of angling (CPUE 1.00 fish/hr) in Snow Lake in 2016 (Table 5). Fish lengths ranged from 133 mm to 373 mm TL and averaged 308 mm (± 10.6, n = 25), and relative weights were generally slightly below average (mean Wr = 88.4, range 59.4 – 125.9) (Table 5, Figure 7). Otolith analysis suggests natural reproduction does occur in Snow Lake (Figure 8), but not at an extremely high rate. WCT size may be improved if stocking were discontinued in this basin, so we suggest halting stocking to determine if presumed low level of natural reproduction is enough to maintain a fishery, and possibly improve fish growth (Table 6). Re-evaluate and re-stock if fishery is not maintained solely through natural reproduction. No amphibians were observed in 2016 (Table 3).

Sapphire Lake – We caught 18 WCT in 15.3 hours of gill netting (CPUE 1.18 fish/hr), and three WCT during one hour of angling (CPUE 3.00 fish/hr) in Sapphire Lake (Table 5). Fish lengths ranged from 223 mm to 353 mm TL and averaged 283 mm (± 8.6, n = 18), and relative weights were generally average (mean Wr = 92.9; range 74.6 – 111.7) (Table 5, Figure 7). Otolith analysis suggests some natural reproduction does occur in Sapphire Lake (Figure 8), but probably not at an extremely high rate, as catch rates were only moderate. Human-use was estimated as moderate as well (Table 3), as this is the middle lake in the set of three main Big Boulder Lakes (Cove, Sapphire, and Cirque).

Current catch rates seem appropriate for level of human-use, and fish size is adequate for sustaining a quality fishery, so no change is recommended (Table 6). No amphibians were observed in 2016 (Table 3).

Cirque Lake – We caught 14 WCT in 13.8 hours of gill netting (CPUE 1.01 fish/hr), and did not catch any fish during one hour of angling (CPUE 0.00 fish/hr) in Cirque Lake (Table 5). Fish lengths ranged from 199 mm to 415 mm TL and averaged 319 mm (± 20.7, n = 14), and relative weights were largely average (mean Wr = 97.4; range 88.6 – 116.0) (Table 5, Figure 7). Otolith analysis suggests there is no natural reproduction taking place in Cirque Lake, as all age classes correspond to stocking events (Figure 8). Human-use is low as well, as this lake sits high in the basin (Table 3). With the level of human-use this lake sees, it seems appropriate to manage this lake for relatively lower catch rates and large fish size, so no change is recommended (Table 6). No amphibians were observed in 2016 (Table 3).

Sheep Lake – We caught 15 WCT and two WCTxRBT hybrids in 18.0 hours of gill netting (CPUE 0.94 fish/hr), and four WCT during one hour of angling (CPUE 4.00 fish/hr) in Sheep Lake (Table 5). WCT lengths ranged from 93 mm to 375 mm TL and averaged 232 mm (± 21.5, n = 15), and WCTxRBT hybrid lengths were 292 mm and 314 mm TL (Table 5, Figure 7). Relative weights for both species and all size classes were largely on or slightly above average (mean WCT Wr = 99.6; range 78.1 – 121.4; mean hybrid Wr = 100.6; range 94.0 – 107.3) (Figure 7). Although our catch rate was relatively low, fish in Sheep Lake seem to grow well (Figure 8). Otolith analysis suggests natural reproduction does occur (Figure 8), but not at an extremely high rate. Higher catch rates would be preferred, but not at the risk of decreasing fish size/growth, so no changes are recommended (Table 6). No amphibians were observed in 2016 (Table 3).

Slide Lake – We caught 18 WCT in 18.0 hours of gill netting (CPUE 1.00 fish/hr), in Slide Lake (Table 5). No fish were caught during 1.7 hours of angling. Fish lengths ranged from 143 mm to 465 mm TL and averaged 253 mm (± 28.7, n = 18) (Table 5, Figure 7), and relative weights were above average, especially as total length increased (mean Wr = 106.4; range 81.9 – 132.9) (Figure 7). The largest four fish we caught weighed well over 1kg and our scale was not able to weigh them, but they were extremely fat. Otolith analysis suggests no natural reproduction takes place in Slide Lake, so fish experience excellent growth (Figure 8). Human-use is low (Table 3), so it seems appropriate to manage this lake for relatively lower catch rates and very large fish. No change is recommended (Table 6). No amphibians were observed in 2016 (Table 3).

Tin Cup Lake – We caught 13 WCT, five GRA, and five WCTxRBT hybrids in 15.9 hours of gill netting (CPUE 1.45 fish/hr) in Tin Cup Lake (Table 5). WCT lengths ranged from 224 mm to 446 mm TL and averaged 303 mm (± 15.1, n = 13), GRA lengths ranged from 173 mm to 205 mm TL and averaged 186 mm (± 6.4, n = 5) and WCTxRBT hybrid lengths ranged from 179 mm to 337 mm TL and averaged 259 mm (± 32.8, n = 5) (Table 5, Figure 7). Relative weights were well below average for all size ranges of all species (mean WCT Wr = 77.6; range 65.7 – 91.6, mean GRA Wr = 70.9; range 61.2 – 77.4; mean WCTxRBT hybrid Wr = 79.0; range 69.4 – 86.0) (Figure 7). Natural reproduction is undoubtedly occurring, at least for WCT and WCTxRBT hybrids, which has likely affected fish

growth (Figure 7). Although growth rate is not extremely high (Figure 8), fish can grow to large size (total length) because they are relatively long-lived (Table 3). GRA (the only species currently stocked) are not very large in the lake, but still offer diversity and enhance the lure of the fishery. The lake is difficult to access, but offers great fishing and exceptional views. No management change is recommended (Table 6). No amphibians were observed in 2016 (Table 3).

Gunsight Lake – Gunsight Lake was not gill netted in 2016, but eight WCT were caught during one hour of angling (CPUE 8.00 fish/hr), ranging from an estimated 150 mm to 460 mm TL. No weights were taken. Surveyors noted that they visually observed fish in the lake ranging from an estimated 75 mm to 500 mm TL (Table 5). Gunsight Lake is one of the highest lakes in the Big Boulder Lakes area, nestled up against the “Chinese Wall”, which offers a spectacular view. Natural reproduction appears to be occurring along the shoreline of the lake, and despite relatively high catch rates, fish size is excellent. With very little human use (Table 3), it may be beneficial to improve fish size even more with a halt in stocking, without being concerned with affecting catch rates. Recommend halting stocking and re-visit to ensure natural reproduction is sufficient for maintaining the fishery (Table 6). No amphibians were observed at Gentian Lake in 2016 (Table 3).

Boulder-White Clouds - Chamberlain Basin

Chamberlain Basin Lakes – There are five larger lakes and several small ponds in Chamberlain Basin. All five of the larger lakes and one of the ponds (Chamberlain Lake #9) have been stocked several times. According to IDFG historical stocking records, the lowest lake in the series, Chamberlain Lake #7, was first stocked with Golden Trout in 1939. We do not have stocking records for any of the other lakes until around 1970 (1987 in Hope). Four lakes are still currently stocked on our three year rotation (Table 3). Once every three years, Chamberlain Lake #7 receives ~500 WCT, Castleview Lake receives ~250 WCT, Honey Lake receives ~200 WCT, and Hope Lake receives ~650 GRA. Stocking was discontinued at Chamberlain Lake #9 in 1987 due to inadequate depth (this is a small pond) and at Heart Lake in 2008 because natural reproduction seemed sufficient for sustaining the fishery there. Human-use is generally moderate to high in this popular lake basin, but can be fairly low at some of the more remote and less accessible lakes (Table 3). Six water bodies in Chamberlain Basin were surveyed between July 5th and July 7th, 2016. We constructed bathymetric maps for Chamberlain Lake #7, Castleview Lake, Heart Lake, Honey Lake, and Hope Lake (Appendix B).

Chamberlain Lake #9 – Two anglers fished the lake for one hour and did not catch any fish. This is the lowest lake/pond in the Chamberlain Basin series, and was stocked with fish on four occasions from 1970 to 1987. However, it has been deemed fishless on every sampling occasion since 1969, as it is a very shallow pond, so stocking was discontinued in 1987 (Table 4). Although it seems to provide great summer foraging or breeding amphibian habitat, no amphibians were observed in 2016 (Table 4).

Chamberlain Lake #7– Five WCT were caught during 13.1 hours of gill netting (CPUE 0.38 fish/hr), ranging from 186 mm to 323 mm TL and averaging 217 mm (± 29.7, n = 5) (Table 5, Figure 9). Relative weights varied by size class, but were

generally near average (mean Wr = 99.5; range 78.7 – 112.9) (Figure 9). We only caught two apparent age classes of WCT in our gill net (Figure 10), and relative abundance was much lower than we would like it to be, given that human-use appears to be relatively high at this lake (Table 3). This lake has been surveyed since 1964, and records indicate our findings in 2016 are representative of previous years as well. We recommend increasing the stocking density (or even stocking frequency) to increase catch rates (Table 6). This lake is the first, and probably most popular, stop for visitors to the Chamberlain Lakes Basin, so higher catch rates would be appropriate with use. Western Toad adults were observed in 2016 (Table 3).

Castleview Lake – We set a gill net for 13.0 hours and did not catch any fish. This is the second consecutive survey that has yielded no fish (other was 1999), but surveys in 1969 and 1970 found WCT present. Surveyors noted in 2016 that the water level was down from its high mark. It is possible that this lake can sustain a fishery during favorable water years, but is susceptible to occasional fish kills as well. Human use is moderate in the area, and this lake would likely see higher use in years when fishing is good. Recommend continuing stocking and re-evaluate (Table 6), especially since 2017 is shaping up to be a good water year. No amphibians were observed in 2016 (Table 3).

Heart Lake - We caught 31 WCT in 17.3 hours of gill netting (CPUE 1.80 fish/hr), in Heart Lake (Table 5). Fish lengths ranged from 120 mm to 327 mm TL and averaged 227 mm (± 12.1, n = 31) (Table 5, Figure 9). Relative weight varied by size class, but was generally near average (mean Wr = 94.3; range 69.9 – 134.6) (Figure 9). This fishery is maintained solely through natural reproduction and perhaps some emigration from nearby stocked lakes, as it hasn’t been stocked since 2008. All age classes were present from age 3 to age 7 (Figure 10). Human-use is relatively moderate (Table 4), and catch rates and fish size appear to be sufficient for providing a quality fishery as is, so no change is recommended (Table 6). No amphibians were observed in 2016 (Table 3).

Honey Lake - We caught 21 WCT in 14.3 hours of gill netting (CPUE 1.47 fish/hr), and seven WCT in two hours of angling (CPUE 3.50 fish/hr) in Honey Lake (Table 5). Fish lengths ranged from 128 mm to 355 mm TL and averaged 269 mm (± 15.7, n = 21), and relative weight was generally average or slightly below (mean Wr = 90.2; range 71.9 – 103.3) (Table 5, Figure 9). Natural reproduction appears to be occurring based on age distribution (Figure 10). With fairly low use (Table 3), halting stocking to reduce abundance and improve fish size may be an option. Honey Lake is connected to Heart Lake via a short ~20m stream, and there appears to be enough spawning habitat in the stream and along the shoreline of both lakes to support enough natural reproduction to sustain the fishery. Fish growth may improve as a result. Recommend removing from the stocking rotation and re-evaluate to ensure the fishery is maintained (Table 6). No amphibians were observed in 2016 (Table 3).

Hope Lake - We caught 16 GRA and 11 GN in 16.2 hours of gill netting (CPUE 1.67 fish/hr), and did not catch any fish in one hour of angling (CPUE 0.00 fish/hr) in Hope Lake (Table 5). GRA lengths ranged from 222 mm to 261 mm TL and averaged 239 mm (± 3.1, n = 16) and GN lengths ranged from 93 mm to 220 mm TL and averaged 142 mm (± 16.1, n = 11) (Table 5, Figure 9). Relative

weights were generally below average for both species (mean GRA Wr = 82.1; range 78.7 – 85.8; mean GN Wr = 85.1; range 59.4 – 124.8) (Figure 9). Spawning of GN was observed in the inlet to the lake in 2016, so natural reproduction does occur. Additionally, GN have not been stocked anywhere in the Chamberlain Lakes Basin since 1977. GRA however, do not appear to be naturally reproducing based on age data (Figure 10). Overall abundance is relatively moderate, but GN growth is slow (Figure 10). GRA growth appears better, but we didn’t catch any GRA older than age 3 (Figure 10), so we do not know how large they can get. With low use, being the highest lake in the Chamberlain Basin series, we would typically try to manage this fishery for larger fish size. However, in this case Honey and Heart Lake offer quality size WCT fisheries and Hope adds unique species diversity by providing a GN and GRA fishery. Keep stocking GRA to sustain their persistence (Table 6). No amphibians were observed in 2016 (Table 3).

Boulder-White Clouds – Fourth of July Drainage

Six Lakes – There are six “lakes” in the Six Lakes basin, four of which are very shallow most years, and we would consider them to be ponds. Six Lake #1 and Fourth of July Lake were the first two high mountain lakes IDFG has on record for being stocked in the Salmon Region, in 1920 by horseback. Since then, both WCT and RBT have been stocked dozens of times in the basin. All of the lakes and ponds in the Six Lakes basin have been stocked at least once, but Six Lakes #2, #4, #5, and #6 have been deemed too shallow to support overwintering fish, thus are no longer stocked. Six Lake #1 is the only lake in the basin still currently stocked on our three year rotation (Table 3). Once every three years, it receives ~500 WCT. Stocking was discontinued at Six Lake #3 in 1999, after two consecutive surveys found it to be fishless. Human-use is moderate in this fairly popular lake basin (Table 3). Six Lake #1 was surveyed August 6th, 2016.

Six Lake #1- We caught two WCT in 14.2 hours of gill netting (CPUE 0.14 fish/hr), in Six Lake #1 (Table 5). The two fish we caught were very large (382 mm and 450 mm TL) and relative weights were 73 and 100, respectively (Table 5, Figure 11). The fish were 4 and 5 years old, respectively (Figure 12), and no evidence of natural reproduction was observed. The lake showed signs of heavy use in 2016 (Table 3), with trampled trails and abundant litter. With such high use, recommend increasing stocking density or stocking frequency to improve catch rates (Table 6). No amphibians were observed in 2016 (Table 3).

Thunder and Lightning Lakes – Thunder and Lightning Lakes sit in the same sub- drainage as Phyllis Lake, all of which are currently stocked on a three-year rotation (Table 3). According to IDFG stocking records, these lakes were stocked as early as 1946, and have been stocked with WCT, RBT, and WCTxRBT hybrids over the years. Currently Phyllis Lake is stocked with ~375 WCT, Thunder Lake is stocked with ~225 WCT, and Lightning Lake is stocked with ~275 WCT, once every three years. Human- use is relatively moderate (Table 3), as a high clearance vehicle road climbs high into the basin. Thunder and Lightning lakes were surveyed on the evening of August 5th, 2016. Phyllis Lake was not surveyed in 2016.

Thunder Lake- We caught 16 WCT in 16.1 hours of gill netting (CPUE 0.99 fish/hr), in Thunder Lake (Table 5). Fish lengths ranged from 250 mm to 341 mm

TL and averaged 276 mm (± 6.6, n = 16), and relative weights were excellent (mean Wr = 124.5; range 101.0 – 135.4) (Table 5, Figure 11). All fish caught in Thunder Lake in 2016 were very healthy and girthy. Ages ranged from 3 to 7 (Figure 12), suggesting some natural reproduction is present, but probably at a low rate. Human use was classified as moderate (Table 3). Considering the current high quality of the fish in Thunder Lake, no change is recommended (Table 6). The fishery offers relatively moderate catch rates and excellent quality WCT. Three adult Columbia Spotted Frogs were observed in 2016 (Table 3).

Lightning Lake- We caught 27 WCT in 15.3 hours of gill netting (CPUE 1.77 fish/hr), in Lightning Lake (Table 5). Fish lengths ranged from 90 mm to 390 mm TL and averaged 257 mm (± 20.2, n = 27) (Table 5, Figure 11). Relative weights varied by size class, and decreased steadily with an increase in total length (mean Wr = 91.1; range 46.3 – 133.7) (Figure 11). We aged fish caught in Lightning Lake in 2016 from age 2 to age 7 (Figure 12), suggesting some natural reproduction is present. Human use was classified as relatively moderate (Table 3), but this is likely the least visited lake in the drainage, considering it is the highest in elevation. While nearby Thunder Lake offers slightly lower catch rates but very large heavy fish, we recommend managing Lightning Lake to provide higher catch rates, as it currently does, so no change is recommended (Table 6). No amphibians were observed in 2016 (Table 3).

Fourth of July and Washington Lake #2 – Fourth of July Lake and Washington Lake #2 are not actually in the same drainage, but are in very close proximity to one another. Both are located along a well-used trail that crosses through the top of Fourth of July Creek (Upper Salmon River drainage) and over into Washington Creek (East Fork Salmon River drainage), and both are currently stocked on a three-year rotation (Table 3). As mentioned previously, Fourth of July Lake was one of the first high mountain lakes IDFG has on record as being stocked in the Salmon Region, back in 1920. The earliest stocking we have on record for Washington Lake #2 is in 1937. Currently, Fourth of July Lake is stocked with ~725 WCT, and Washington Lake #2 is stocked with ~750 WCT, once every three years. Human-use is high at these lakes (Table 3). The lakes were surveyed on the evening of August 4th, 2016.

Fourth of July Lake- We caught 35 WCT in 13.8 hours of gill netting (CPUE 2.55 fish/hr), in Fourth of July Lake (Table 5). Fish lengths ranged from 84 mm to 329 mm TL and averaged 172 mm (± 13.6, n = 34), and relative weights were average (mean Wr = 98.5; range 85.9 – 120.2) (Table 5, Figure 11). All age classes from 2 to 7 appeared to be present (Figure 12), suggesting natural reproduction occurs. Human use was classified as moderate (Table 3). Although natural reproduction is present, the currently observed high catch rates may not be sustained if stocking were halted. Since this lake is very popular and easily accessible, we recommend continuing with the current stocking density and frequency (Table 6) to maintain high catch rates, especially since fish condition is good. Four adult Columbia Spotted Frogs and six adult Long-toed Salamanders were observed in 2016 (Table 3).

Washington Lake #2- We caught 85 EBT in 14.6 hours of gill netting (CPUE 5.82 fish/hr), in Washington Lake #2 (Table 5). EBT lengths ranged from 89 mm to 308 mm TL and averaged 172 mm (± 6.3, n = 77) (Table 5, Figure 11). Relative weight values varied by size class, decreasing with an increase in total

length (mean Wr = 91.3; range 52.5 – 160.0) (Figure 11). Despite not having record of Brook Trout ever being stocked in the lake, and numerous stocking events for other species over the past several decades, naturally reproducing Brook Trout are very abundant in Washington Lake #2. We estimated otolith ages from age 2 to age 7, but the majority of fish we caught were likely between ages 2 and 4 (Figures 11 and 12). Human use was classified as high (Table 3), so maintaining high catch rates should be a priority. However, naturally reproducing Brook Trout are prone to overpopulating and stunting, so it may be more desirable to remove them and stock the lake with a different species like WCT. Until Brook Trout are removed however, stocking should be halted (Table 6), as WCT stocked over the last 40+ years have been unable to persist. Two adult Columbia Spotted Frogs and hundreds of Western Toad tadpoles were observed in 2016 (Table 3).

MANAGEMENT RECOMMENDATIONS

1. Maintain project goals of sampling a stocking panel each year.

2. Review and implement annual changes in stocking recommendations for each lake.

3. Use information gathered in these surveys to construct a high mountain lake angling guide for public use.

Table 1. Salmon Region high mountain lake stocking rotations A, B, and C by year, 2016 through 2022.

Stocking rotation sequence A B C Year 2023 2024 2016 of 2017 2018 2019 stocking 2020 2021 2022

Table 2 High Mountain Lakes stocked in the Salmon Region in 2016 (Rotation C).

Date stocked Lake IDFG cat.# Species # Stocked 8/17 M.F. Hat Ck. #3 07-1289 RBT 1992 8/17 M.F. Hat Ck. #4 07-1290 RBT 1033 9/10 Puddin Mtn. #1 07-0764 RBT 502 9/10 Puddin Mtn. #2 07-0766 RBT 502 9/10 Puddin Mtn. #6 07-0773 RBT 1005 9/10 Puddin Mtn. #5 07-0770 RBT 1005 9/10 Lost Packer 07-0564 RBT 1005 9/13 Rocky 07-1135 WCT 442 9/13 Tango #6 07-0895 WCT 884 9/13 Lola #2 07-1148 WCT 493 9/13 Lola #3 07-1149 WCT 493 9/10 Cabin Ck. Peak #1 07-1487 WCT 254 9/10 Cabin Ck. #7 07-1494 WCT 304 9/10 Cabin Ck. #3 07-1503 WCT 152 9/10 Cabin Ck. #4 07-1504 WCT 101 9/10 Knapp #7 07-1169 WCT 203 9/10 Loon Ck. #3 07-0904 WCT 152 9/10 Tango #4 07-0893 WCT 659 9/10 Loon Ck. #11 07-0917 WCT 372 9/10 Loon Ck. #13 07-0919 WCT 237 9/10 Paragon 07-0756 WCT 271 9/10 Ramshorn 07-0755 WCT 355 9/10 Puddin Mtn. #10 07-0778 WCT 271 9/10 Puddin Mtn. #15 07-0787 WCT 676 9/10 Heart 07-0793 WCT 1674 9/10 Hidden 06-0616 WCT 1133 9/10 Broncho 07-0566 WCT 727 9/10 N.F.E.F. Reynolds #2 07-0575 WCT 1302 9/10 N.F.E.F. Reynolds #4 07-578 WCT 998 9/10 Line 06-0603 WCT 355

23 Table 2 (continued) Date stocked Lake IDFG cat.# Species # Stocked 9/20 Hindman #1 07-1495 WCT 505 8/17 Pass 07-1307 WCT 299 8/17 Devils 07-1260 WCT 355 8/17 Patterson #1 07-1258 WCT 150 8/17 Patterson #3 07-1258.5 WCT 131 8/17 Bear Valley #1 07-1243 WCT 1495 8/17 Basin Ck. #4 (McNutt) 07-1236 WCT 411 8/17 Basin Ck. #5 07-1237 WCT 1121 8/17 Ship Island #5 07-0616 WCT 1009 8/17 Ship Island #7 07-0620 WCT 318 8/17 Birdbill 07-1197 WCT 505 8/17 Wilson 07-0794 WCT 1009 8/17 Harbor 07-0796 WCT 2990 8/17 Welcome 07-0790 WCT 1215 8/17 Spruce Gulch 07-1316 WCT 1495 8/26 U.P. 07-1220 WCT 1514 8/17 Bear Valley #1 07-1243 GR 325 8/17 M.F. Hat Ck. #1 07-1287 GR 162 8/17 M.F. Hat Ck. #2 07-1288 GR 357 9/10 Knapp #14 07-1179 GR 175 8/17 Pass 07-1307 GN 391 8/17 Glacier 07-1189 GN 271 8/17 Gooseneck 07-1187 GN 211 8/17 Crater 07-1185 GN 693 8/17 Golden Trout 07-1201 GN 964 9/13 Alpine Ck. #11 07-1797 GN 594 7/6 Nez Perce 07-1273 BB 299 WCT=Westslope Cutthroat Trout, RBT=Triploid Rainbow Trout, GR=Arctic Grayling, GN=Golden Trout, and BB=Tiger Trout.

Table 3. Rotation A high mountain lakes surveyed in 2016 (n = 34), including location (LLID), elevation, estimated maximum depth, hiking distances, estimated level of human use, and amphibian species observed. Cross- Trail country Amphibian Elevation Maximum distance distance # Human species Drainage/ lake name LLID a (m) depth (m) (mi) (mi) campsites use present b Challis Creek drainage Challis Creek Lake #2 1145181445498 2738 -- 7.0 0.2 0 Mod none Challis Creek Lake #3 1145208445520 2738 -- 7.0 0.5 3 Mod none Twin Creek Lake #2 1144768445832 2715 5.0 0.0 0.3 1 Mod none W F Bear Creek Lake #1 1144874445667 2725 4.1 0.0 2.5 0 Low WT Slate Creek area Hoodoo Lake 1146076441271 2641 5.0 2.0 0.0 1 Mod CSF Crater Lake 1146082441415 2719 16.8 5.0 0.0 4 Mod none Elk Lake 1147476442291 2555 7.5 0.0 4.0 0 none WT Swimm Lake 1146675441491 2703 -- 8.0 4.0 0 Low none Ocalkens Lake #1 1146360441277 2703 9.1 3.5 1.3 1 Low none Ocalkens Lake #2 1146412441245 2755 4.6 3.5 1.3 4 Mod none East Basin Cr Lake #1 1147924443262 2482 4.0 6.0 0.8 0 Low CSF, WT Little Boulder Cr drainage Big Frog Lake 1145459440792 2700 -- 8.0 0.0 4 High CSF, WT Castle Lake 1145764440463 2872 -- 9.5 0.0 1 Mod none Shallow Lake 1145991440632 2938 3.1 10.5 0.5 1 Low none Big Boulder Cr drainage Cirque Lake 1146208441064 3067 23.8 5.0 2.5 1 Low none Cove Lake 1146086441013 3001 9.4 5.0 1.8 4 High none Feldspar Lake 1145904440905 2932 -- 4.0 1.0 0 Low none Gentian Lake 1146122440972 3059 4.6 5.0 2.5 0 Low none Goat Lake 1145813440983 2725 5.5 5.0 0.2 1 Mod none Gunsight Lake 1146076441271 3067 9.4 6.5 1.5 0 Mod none Sapphire Lake 1146152441033 3015 10.6 5.0 2.0 1 Mod none Sheep Lake 1146111441133 3011 9.4 5.0 3.0 2 Mod none Slide Lake 1146198441124 3104 6.1 5.0 3.5 0 Low none Snow Lake 1146138440957 3053 9.7 5.0 2.6 0 Low none Tin Cup Lake 1146095441228 3043 -- 6.5 2.0 0 Low none Chamberlain Basin area Castleview Lake 1145949440206 2823 7.0 10.1 0.5 2 Mod none Chamberlain Lake #7 1145928440269 2804 6.1 10.1 0.0 6 High WT Honey Lake 1146054440368 2897 -- 10.1 1.2 3 Mod none

25 Table 3 (continued)

Cross- Trail country Amphibian Elevation Maximum distance distance # Human species Drainage/ lake name LLID a (m) depth (m) (mi) (mi) campsites use present b Fourth of July Cr area Fourth of July Lake 1146313440433 2856 2.2 1.2 0.0 5 High CSF,LTS Lightning Lake 1146643440160 2918 -- 3.0 0.5 0 Mod none Six Lake #1 1146776440290 2701 9.4 3.0 2.0 3 Mod none Thunder Lake 1146605440221 2797 -- 3.0 0.0 0 Mod CSF Washington Lake #2 1146211440319 2855 -- 2.5 0.0 7 High CSF, WT Hope Lake 1146102440386 3003 4.6 10.1 1.5 0 Low none a LLID = Latitude and Longitude Identification b CSF = Columbia Spotted Frog, LTS = Long-toed Salamander, WT = Western Toad

Table 4. High mountain lakes surveyed in 2016 that are not stocked on rotation A (n = 18). Includes location (LLID), elevation, estimated maximum depth, hiking distances, estimated level of human use, and amphibian species observed.

Cross- Trail country Amphibian Elevation Maximum distance distance Human species Drainage/ lake name LLID (m) depth (m) (mi) (mi) # campsites use present Challis Creek drainage Challis Creek Lake #1 1145139445528 2736 -- 7.0 0.0 3 High none Little Boulder Cr drainage Hatchet Lake 1145626440690 2709 -- 8.5 0.0 4 High WT Headwall Lake 1145983440743 2974 -- 12.3 0.8 0 Mod none Hidden Lake 1145955440788 2901 4.6 10.0 0.0 1 High none Hourglass Lake 1145883440776 2899 4.6 10.0 0.0 2 High none Hummock Lake 1145920440775 2901 6.4 10.0 0.0 3 High CSF, WT Little Frog Lake 1145420440799 2704 8.6 8.8 0.0 2 Mod CSF, WT Lonesome Lake 1146070440743 3182 -- 10.8 0.4 0 Low none Noisy Lake 1145834440581 2743 -- 10.0 3.0 1 Low none Quiet Lake 1145934440539 2818 9.4 10.0 4.0 4 High none Scoop Lake 1145945440729 2940 6.4 10.0 0.0 1 Mod CSF Scree Lake 1145956440618 2907 6.1 11.0 1.0 0 Low none Shelf Lake 1145674440704 2726 10.1 8.5 0.0 1 High none Sliderock Lake 1145715440706 2738 9.5 8.8 0.0 2 High none Willow Lake 1145600440736 2662 3.8 8.0 0.0 2 High CSF, WT Big Boulder Cr drainage Boulder Lake 1146142440982 3059 -- 5.0 2.6 0 Low none Chamberlain Basin area Chamberlain Lake #9 1145886440243 2801 -- 10.1 0.1 0 Low none Heart Lake 1146040440340 2890 9.1 10.1 0.9 1 Mod none a LLID = Latitude and Longitude Identification b CSF = Columbia Spotted Frog, LTS = Long-toed Salamander, WT = Western Toad

Table 5. Fish population structure and abundance in high mountain lakes, surveyed in 2016, where fish were found (n = 47). Includes current stocking information, fish species, size structure, and relative abundances observed during surveys, mean length at age 2 when available, and whether or not natural reproduction is suspected.

Current Current fish stocking species density Fish species CPUE (fish/hr) Mean TL (range) Drainage/ lake name stocked (fish/ha) present # caught angling/gill netting (mm) Challis Creek drainage Challis Creek Lake #1 none na WCT 5 0.00/0.35 349 (312 -377) WCTxRBT 8 0.00/0.57 334 (310-358) Challis Creek Lake #2 WCT 368 WCT 50 2.67/2.96 207 (112-316) Twin Creek Lake #2 RBT 119 WCTxRBT 17 --/1.08 270 (136-368) W F Bear Creek Lake #1 WCT 143 WCT 29 6.00/1.74 238 (156-327) Slate Creek area Crater Lake WCT 136 WCT 27 --/2.18 308 (210-347) Elk Lake WCT 125 WCT 42 12.00/2.27 217 (160-268) Swimm Lake WCT 131 WCT 16 --/1.23 334 (276-366) Ocalkens Lake #1 WCT 268 WCT 14 --/1.19 257 (154-354) East Basin Cr Lake #1 WCT 254 WCT 12 0.00/0.89 374 (313-496) Little Boulder Cr drainage Big Frog Lake WCT 192 WCT 32 --/2.06 256 (103-425) Castle Lake WCT 127 WCT 5 --/0.41 318 (304-330) RBT 12 --/0.99 164 (90-270) WCTxRBT 2 --/0.17 262 (252-272) Hatchet Lake none na RBT 136 --/7.51 160 (80-211) Headwall Lake none na WCT 1 0.50/-- 457 Hidden Lake none na RBT 26 13.00/-- >250 Hourglass Lake none na RBT 43 10.00/2.28 192 (147-238) Hummock Lake none na RBT 108 25.50/3.68 159 (81-232) Little Frog Lake none na WCT 7 --/0.48 282 (115-336) Noisy Lake none na WCTxRBT 15 15.00/-- -- (150-410) Quiet Lake none na RBT 5 5.00/-- 279 (152-432) Scoop Lake none na RBT 3 1.50/-- -- (152-250) WCT 1 0.33/-- 356 Scree Lake none na WCT 54 36.00/-- 234 (176-292) Shallow Lake WCT 159 WCT 17 1.00/1.20 189 (147-298) Shelf Lake none na RBT 78 --/4.88 184 (94-244) Sliderock Lake none na RBT 90 --/7.69 182 (92-275)

Current Current fish stocking species density Fish species CPUE (fish/hr) Mean TL (range) Drainage/ lake name stocked (fish/ha) present # caught Angling/Gill netting (mm) Willow Lake none na RBT 161 --/13.42 144 (80-339) BUT 1 --/0.08 315 Big Boulder Cr drainage Boulder Lake none na WCT 1 0.50/-- 250 Cirque Lake WCT 140 WCT 14 0.00/1.01 319 (199-415) Cove Lake WCT 143 WCT 3 0.00/0.18 340 (283-416) RBT 21 3.00/1.06 293 (183-404) Feldspar Lake GRA 173 GRA 3 --/0.20 257 (230-308) RBT 26 --/1.74 233 (153-306) Gentian Lake RBT 711 WCT 1 0.00/0.07 180 Goat Lake WCT 326 WCT 19 --/1.41 256 (84-372) RBT 7 --/0.52 288 (162-353) Gunsight Lake WCT 142 WCT 8 8.00/-- -- (76-500)a Sapphire Lake WCT 138 WCT 21 3.00/1.18 283 (223-353) Sheep Lake WCT 147 WCT 19 4.00/0.83 232 (93-375) WCTxRBT 2 0.00/0.11 303 (292-314) Slide Lake WCT 153 WCT 18 0.00/1.00 253 (143-465) Snow Lake WCT 134 WCT 27 1.00/1.98 308 (133-373) Tin Cup Lake GRA 169 GRA 5 --/0.31 186 (173-205) WCT 13 --/0.82 303 (224-446) WCTxRBT 5 --/0.31 259 (179-337) Chamberlain Basin area Castleview Lake WCT 124 UNK 0 --/0.00 -- Chamberlain Lake #7 WCT 114 WCT 5 --/0.38 217 (186-323) Heart Lake none na WCT 31 --/1.80 227 (120-327) Honey Lake WCT 128 WCT 28 3.50/1.47 269 (128-355) Hope Lake GRA 173 GRA 16 0.00/0.99 239 (222-261) GN 11 0.00/0.68 142 (93-220) Fourth of July Cr area Fourth of July Lake WCT 273 WCT 35 --/2.55 172 (84-329) Lightning Lake WCT 124 WCT 27 --/1.77 257 (90-390) Six Lake #1 WCT 122 WCT 2 --/0.14 416 (382-450) Thunder Lake WCT 267 WCT 16 --/0.99 276 (250-341) Washington Lake #2 WCT 105 EBT 85 --/5.82 172 (89-308) a Estimate based on visual observation

Table 6. List of stocking recommendations for high mountain lakes in 2017 as a result of 2016 surveys.

Current Current fish stocking Recommended # to be species density Recommended Recommended stocking density stocked in Drainage/ lake name stocked (fish/ha) # stocked change species (fish/ha) 2017 Challis Creek drainage

Challis Creek Lake #1 none n/a none none none none 0 Challis Creek Lake #2 WCT 368 750 reduce density WCT 184 375 Challis Creek Lake #3 WCT 374 950 halt stocking none 0 0 Twin Creek Lake #2 RBT 119 150 none RBT 119 150 W F Bear Creek Lake #1 WCT 143 200 halt stocking none 0 0 Slate Creek area

Hoodoo Lake WCT 134 250 none WCT 134 250 Crater Lake WCT 136 875 none WCT 136 875 Elk Lake WCT 125 675 halt stocking none 0 0 Swimm Lake WCT 131 870 none WCT 131 870 Ocalkens Lake #1 WCT 268 500 none WCT 268 500 Ocalkens Lake #2 WCT 174 750 halt stocking none 0 0 East Basin Creek Lake #1 WCT 254 480 none WCT 254 480 Little Boulder Cr. - BWC

Big Frog Lake WCT 192 1,000 none WCT 192 1,000 Little Frog Lake none n/a 0 none none 0 0 Willow Lake none n/a 0 none none 0 0 Hatchet Lake none n/a 0 none none 0 0 Shelf Lake none n/a 0 none none 0 0 Sliderock Lake none n/a 0 none none 0 0 Hourglass Lake none n/a 0 none none 0 0 Hummock Lake none n/a 0 none none 0 0 Scoop Lake none n/a 0 re-establish stocking WCT 150 450 Hidden Lake none n/a 0 none none 0 0 Headwall Lake none n/a 0 re-establish stocking WCT 150 390 Lonesome Lake none n/a 0 none none 0 0 Castle Lake WCT 127 650 increase density WCT 200 1,010 Noisy Lake none n/a 0 none none 0 0 Quiet Lake none n/a 0 none none 0 0 Scree Lake none n/a 0 none none 0 0 Shallow Lake WCT 159 380 none WCT 159 380

30 Table 6 (continued)

Goat Lake WCT 326 1,150 none WCT 326 1,150 Feldspar Lake GRA 173 500 none GRA 173 500 Cove Lake WCT 143 1,100 none WCT 143 1,100 Gentian Lake RBT 711 325 halt stocking none 0 0 Boulder Lake none n/a 0 none none 0 0 Snow Lake WCT 134 370 halt stocking none 0 0 Sapphire Lake WCT 138 1,250 none WCT 138 1,250 Cirque Lake WCT 140 1,150 none WCT 140 1,150 Sheep Lake WCT 147 500 none WCT 147 500 Slide Lake WCT 153 270 none WCT 153 270 Tin Cup Lake GRA 169 1,000 none GRA 169 1,000 Gunsight Lake WCT 142 450 halt stocking none 0 0 Chamberlain Basin - BWC

Chamberlain Lake #9 none n/a 0 none none 0 0 Chamberlain Lake #7 WCT 114 500 increase density WCT 200 875 Castleview Lake WCT 124 250 none WCT 124 250 Heart Lake none n/a 0 none none 0 0 Honey Lake WCT 128 200 halt stocking none 0 0 Hope Lake GRA 173 650 none GRA 173 650 Fourth of July Cr. area Six Lake #1 WCT 122 500 increase density WCT 200 800 Thunder Lake WCT 267 225 none WCT 267 225 Lightning Lake WCT 124 275 none WCT 124 275 Fourth of July Lake WCT 273 725 none WCT 273 725 Washington Lake #2 WCT 105 750 halt stocking none 0 0

1.0 Challis Cr L #1 Challis Cr L #2 WCT 0.5 RBTxWCT

0.0 160

120

40 / relative weight / relative

1.0

requency Twin Cr L #2 WF Bear Cr L 0.5

0.0

Relative f 160 120 80 40

TL (mm)

Figure 1. Length-frequency histograms and relative weights (Wr) of all fish captured by lake in the Challis Creek area during gill netting. All species are combined for relative weights (dashed line represents Wr = 100). Refer to Table 5 for sample sizes.

450 Challis Cr L #1 Challis Cr L #2 400 WCT 350 RBTxWCT 300 250 200

150 100 50 0

450 Twin Cr L #2 WF Bear Cr L 400 Total length (mm) 350 300 250 200 150 100 50 0 0 2 4 6 8 10 12 14 0 2 4 6 8 10 12 14

Estimated age

Figure 2. Length-at-age of all fish captured and aged by lake in the Challis Creek area during gill netting.

1.0 WCT Crater L Elk L 0.5

0.0 160

120

1.0 Swimm L Ocalkens L #1 0.5

/ relative weight / relative 0.0

160 120 requency 80 40

Relative f

1.0 E Basin Cr L 0.5

0.0

160 120 80 40

TL (mm)

450 Crater L Elk L 400 WCT

350 300 250 200 150 100 50 0

450 Swimm L Ocalkens L #1 400

350 300 250 200 150 100 Total length (mm) 50 0 0 2 4 6 8 10 12 14

450 E Basin Cr L 400 350 300 250 200 150 100 50 0 0 2 4 6 8 10 12 14

Estimated age

Figure 4. Length-at-age of all fish captured and aged by lake in the Slate Creek area during gill netting.

1.0 WCT Big Frog L Castle L RBT 0.5 RBTxWCT BUT

0.0 160 120 80 40

1.0 Hatchet L Headwall L 0.5

relative weight relative 0.0

/ 160

120 No weight taken requency 80

40 Relativef 1.0 Hourglass L Hummock L 0.5

0.0

160

120

TL (mm)

Figure 5. Length-frequency histograms of total lengths of all fish captured at lakes within the Little Boulder Creek drainage during gill netting and angling sampling events. All species are combined for relative weights (dashed line represents Wr = 100). Refer to Table 5 for sample sizes.

36 Figure 5(continued)

1.0 Little Frog L Quiet L 0.5

0.0 160

120

80 No weight taken

1.0 Scoop L Scree L 0.5 / relative weight / relative 0.0 160

requency 120 No weight taken 80

Relative f 40

1.0 Shallow L Shelf L 0.5

0.0 160

120

TL (mm)

37 Figure 5(continued)

1.0 Sliderock L Willow L

0.5

0.0 160

120

40 Relative frequency/ relative weight frequency/Relative relative

TL (mm)

Big Frog L Castle L 450 WCT 400 RBT 350 RBTxWCT 300 250 200 150 100 50 0

450 Hatchet L Hourglass L 400 350 300

250 200 150 100 50 0

Total length (mm) 450 Hummock L Little Frog L 400 350 300 250 200 150 100 50 0 0 2 4 6 8 10 12 14

450 Scree L 400 350 300 250 200 150 100 50 0 0 2 4 6 8 10 12 14

Estimated age

Figure 6. Length-at-age of all fish captured and aged from lakes within the Little Boulder Creek drainage during gill netting and angling sampling events.

39 Figure 6 (continued)

450 Shallow L Shelf L 400 350 300 250

200 150 100 50 0

450 Sliderock L Willow L Total length (mm) 400 350 300 250 200 150 100 50 0 0 2 4 6 8 10 12 14 0 2 4 6 8 10 12 14 Estimated age

WCT 1.0 RBT Boulder L Cirque L RBTxWCT GRA 0.5

0.0 160

120 No weight taken 80

1.0 Cove L Gentian L 0.5

0.0 / relative weight / relative 160

120 requency 80

40 Relative f 1.0 Goat L Sapphire L 0.5

0.0 160

120

TL (mm)

Figure 7. Length-frequency histogram of total lengths of all fish captured at lakes within the Big Boulder Creek drainage during gill netting and angling sampling events. All species are combined for relative weights (dashed line represents Wr = 100). Refer to Table 5 for sample sizes.

41 Figure 7 (continued)

1.0 Sheep L Slide L 0.5

0.0 160

120

1.0 Snow L Tin Cup L 0.5

0.0 / relative weight / relative 160

120

requency 80

40 Relative f

1.0 Feldspar L 0.5

0.0

160 120 80 40

TL (mm)

450 Cirque L Cove L 400 350 300 250 200 WCT 150 RBT 100 RBTxWCT 50 GRA 0 450 Goat L Sapphire L 400 350 300 250

200 150 100 50 0

450 Sheep L Slide L 400 Total length (mm) 350 300 250 200 150 100 50 0

450 400 Snow L Tin Cup L 350 300 250 200 150 100 50 0 0 2 4 6 8 10 12 14 0 2 4 6 8 10 12 14

Estimated age

Figure 8. Lengths at ages of all fish captured and aged from lakes within the Big Boulder Creek drainage during gill netting and angling sampling events.

43 Figure 8 (continued)

450 400 Feldspar L 350 300 250 200 150 100 Total length (mm) 50 0 0 2 4 6 8 10 12 14

Estimated age

1.0 Chamberlain L #7 Heart L WCT GRA 0.5 GN

0.0

160

120

40 / relative weight / relative

1.0

requency Honey L Hope L 0.5 Relative f 0.0 160

120

TL (mm)

Figure 9. Length-frequency histograms of total lengths of all fish captured at lakes in the Chamberlain Basin area during gill netting. All species are combined for relative weights (dashed line represents Wr = 100). Refer to Table 5 for sample sizes.

450 Chamberlain L #7 Heart L 400 WCT 350 GRA 300 GN 250 200 150 100 50 0

450 Honey L Hope L 400

Total length (mm) 350 300 250 200 150 100 50 0 0 2 4 6 8 10 12 14 0 2 4 6 8 10 12 14

Estimated age

Figure 10. Length-at-age of all fish captured and aged from lakes in the Chamberlain Basin area during gill netting.

1.0 Fourth of July L Lightning L WCT 0.5 EBT

0.0 160

120

1.0 Six L #1 Thunder L 0.5

0.0 / relative weight / relative 160

120

requency 80

40 Relative f

1.0 Washington L #2 0.5

0.0

160 120 80 40

TL (mm)

Figure 11. Length-frequency histograms of total lengths of all fish captured at lakes in the Fourth of July Creek area during gill netting. All species are combined for relative weights (dashed line represents Wr value of 100). Refer to Table 5 for sample sizes.

450 Fourth of July L Lightning L 400 WCT 350 EBT 300 250 200 150 100 50 0

450 400 Six L #1 Thunder L

350 300 250 200 150 100 50

Total length (mm) 0 0 2 4 6 8 10 12 14

450 Washington L #2 400 350 300 250 200 150 100 50 0 0 2 4 6 8 10 12 14

Estimated age

Figure 12. Length-at-age of all fish captured and aged from lakes in the Fourth of July Creek area during gill netting.

LOWLAND LAKES AND RESERVOIRS:

TROUT EXPLOITATION STUDIES

ABSTRACT

We estimated return-to-creel rates for stocked catchable-sized Rainbow Trout Oncorhynchus mykiss (mean 250 mm TL) in seven put-and-take fisheries in the Salmon Region in 2016, using the Tag-You’re-It program (Meyer et al. 2012, Cassinelli 2014). Both total use (fish caught) and total exploitation (fish harvested) were estimated for each waterbody. As of March 1, 2017, estimated rates for hatchery-stocked catchable Rainbow Trout were highest in Perkins Lake (32.7% for use and 25.5% for exploitation), and lowest in Little Bayhorse Lake (16.9% use and 12.0% exploitation). Since 2011 when we began using these methods to estimate return-to-creel rates, 49.2% is the highest estimated total use we have observed in the region (Meadow Creek Lake in 2014).

In 2016 we also estimated angler effort at Squaw Creek Pond using trail cameras. Total fishing effort was 401 hours between May 5 and August 8, 2016, with the highest effort during June and July. These results will help guide our put-and-take stocking program for Squaw Creek Pond in future years.

Author:

Jordan Messner, Regional Fisheries Biologist

INTRODUCTION

Hatchery production of catchable-size Rainbow Trout (averaging ~250 mm TL) typically accounts for over 50% of IDFG’s annual Resident Hatchery budget (Cassinelli 2014). Therefore, there is a need to quantify catch and exploitation patterns to better inform management decisions and help guide stocking programs to maximize efficiency. IDFG research staff developed a tag reporting program in 2006, called “Tag-You’re-It”, to evaluate return-to-creel rates for catchable Rainbow Trout Oncorhynchus mykiss stocked in “put-and-take” waters (Meyer et al. 2012, Cassinelli 2014). The tagging program allows us to estimate total use (fish caught) and exploitation (fish harvested) of stocked groups, based on angler reporting of caught tags.

We have been using the Tag-You’re-It program to estimate return-to-creel rates for stocked lakes in the Upper Salmon River Basin since 2011. Over the past five years, 14 regional lakes and ponds have been evaluated, and some have been evaluated in multiple years. We evaluated two lakes in 2011, two in 2012, three in 2013, nine in 2014, and eight in 2015 in the Salmon Region. We also estimated return-to-creel for catchable Rainbow Trout stocked in the Salmon River in 2011, 2012, and 2013. Overall use estimates in our region have ranged as low as 0.0% and 1.4% in Hyde Pond (2014) and Alturas Lake (2014), respectively, and as high as 49.2% in Meadow Lake in 2014.

We used the Tag-You’re-It program in 2016 to evaluate return-to-creel rates for stocked catchable Rainbow Trout at seven put-and-take fisheries, as well as for stocked tiger trout Salvelinus fontinalis x Salmo trutta in Wallace Lake. Results for Wallace Lake are presented in chapter three of this report (Chapter Three: Wallace Lake).

OBJECTIVES

1. Improve understanding of how anglers use regional fisheries by conducting return-to- creel evaluations.

2. Estimate return-to-creel rates of hatchery trout to determine whether stocking timing, frequency, and/or densities could be adjusted to maximize angler use and satisfaction.

STUDY SITES

Little Bayhorse Lake (WGS84 datum: 44.41222ºN, 114.38805ºW) is a 6.2 ha lake located ~30 km from the city of Challis, at ~2,550 m elevation. Drive-in access to the lake is available during snow-free months, as there is a maintained road that climbs the 11.5 km up Bayhorse Creek, past the historic “ghost town” of Bayhorse, to Big and Little Bayhorse Lakes. Little Bayhorse Lake was first stocked in 1957, and IDFG currently stocks ~1,000 to ~3,000 catchable Rainbow Trout annually. In 2015, we stocked ~500 catchables during each of four events (two in June and two in July), for a total of ~2,000 stocked fish, and 30 fish (~10%) were tagged during each event to estimate return-to-creel on the stocked groups. Average total use across all stocked groups was 9.8% for 2015. In 2016, we stocked 3,344 Rainbow Trout during three events (1,061 on June 23, 939 on June 28, and 1,344 on September 20), and tagged 74 from the first event only.

Perkins Lake (WGS84 datum: 43.92811ºN, 114.83856ºW) is an approximately 20.0 ha lake located in the Sawtooth Basin, approximately 37 km south of Stanley, ID, at an elevation of 2,143 m. The inlet to Perkins Lake (Alturas Lake Creek) comes from Alturas Lake, and the

outlet flows into the upper Salmon River. There is a Lutheran Church camp located on the east side of the lake (Camp Perkins) which maintains and operates a boat ramp and several docks. However, these services are open only to camp attendees. There are two public access areas to the lake (one at the north end and one at the south end), but no public boat ramp. IDFG began stocking Perkins Lake in 1927 with Rainbow Trout. Brook Trout S. fontinalis were stocked from 1949 to 1952, but the lake has been primarily stocked with Rainbow Trout since 1959 (IDFG stocking records). We currently stock ~1,000 to 2,000 catchable Rainbow Trout in Perkins Lake each year, but catch and harvest has not yet been evaluated using Tag-You’re-It methodology. Northern Pikeminnow Ptychocheilus oregonensis, suckers Catostomus spp., and Mountain Whitefish Prosopium williamsoni are also present in the lake, and made up the majority of angler and gill net catch composition in the 1980s, when the lake was last surveyed.

Squaw Creek Pond (WGS84 datum: 44.25806ºN, 114.45701ºW) is a 0.6 ha pond located ~6 km from the town of Clayton, and ~32 km from the city of Challis. IDFG constructed the pond in 1997 on land owned by the Thompson Creek Mining Company. The pond was first used as an anadromous steelhead acclimation pond, where hatchery-reared steelhead were stocked prior to smolting. After steelhead left the pond, non-migratory fish would remain and supported a local Rainbow Trout fishery. Currently, the pond is managed as a put-and-take fishery, and we stock 600 to 800 catchable Rainbow Trout per year. The pond receives water from Squaw Creek via a diversion ditch and the outflow is diverted back into Squaw Creek. The pond is dewatered during winter months, and is re-watered in the spring to offer recreational fishing opportunity for the surrounding communities (i.e. Clayton and Thompson Creek) during summer months. In 2015 we used Tag-You’re-It methodology to assess return-to-creel rates at Squaw Creek Pond, but no tags were returned.

Valley Creek (WGS84 datum: 44.22142ºN, 114.94633ºW) is a major tributary to the upper Salmon River, with the confluence located in the town of Stanley, ID at an elevation of 1,896 m. The Stanley area (Sawtooth Basin) is a very popular tourist destination from approximately May through September, and Valley Creek likely receives relatively high angling pressure due to conveniently located sportsman’s access points (e.g. Sheep Bridge, Stanley Creek, and M-M). Brook Trout were stocked in Valley Creek as early as 1940 and quickly established a naturally reproducing population. In the early 1990’s, Brook Trout densities in Valley Creek were extremely high, and they were not providing a quality fishery. IDFG staff attempted a large scale Brook Trout removal effort from 1995 to 2001, in combination with Westslope Cutthroat Trout O. clarkii and Bull Trout S. confluentus re-introduction (Larkin et al. 2001). Over 26,000 Brook Trout were removed from Valley Creek using electrofishing during those years, and over 100,000 native fish were stocked throughout the drainage. However, the re-introduction efforts were largely considered a failure. Currently, we treat Valley Creek as a put-and-take fishery, by stocking 3,000 to 4,000 catchable Rainbow Trout annually. We have not yet evaluated angler use and harvest for Valley Creek using Tag-You’re-It methodology.

The Yankee Fork Dredge Ponds are located approximately 6 km up the Yankee Fork Salmon River drainage. There are several ponds in the area, but the only ponds currently stocked are Yankee Fork Lower Dredge Pond (WGS84 datum: 44.30566ºN, 114.71974ºW), Yankee Fork Dredge Pond 1 (WGS84 datum: 44.31152ºN, 114.71614ºW), and Yankee Fork Dredge Pond 4 (WGS84 datum: 44.34673ºN, 114.72555ºW). There are very few “community fish ponds” in the Stanley, ID area, so the Yankee Fork Dredge Ponds effectively serve as such. In 2016, we stocked 150 catchable Rainbow Trout in Yankee Fork Lower Dredge Pond, 3,425 catchable Rainbow Trout in Yankee Fork Dredge Pond 1, and 425 catchable Rainbow Trout in Yankee Fork Dredge Pond 4. This is the first time we are evaluating angler use and harvest at the Yankee Fork Dredge Ponds using Tag-You’re-It methodology.

METHODS

Return-to-Creel

Return-to-creel rates were assessed for select catchable Rainbow Trout stocking events at Little Bayhorse Lake, Perkins Lake, Squaw Creek Pond, Valley Creek, and the Yankee Fork Dredge Ponds in 2016, and were also assessed for the first of two stocking events for catchable tiger trout stocked in Wallace Lake (summarized in Chapter Three: Wallace Lake). Total use (fish caught) and exploitation (fish harvested) were evaluated for hatchery- produced catchable Rainbow Trout in five water bodies, and tiger trout in one water body (discussed in Chapter Three of this report) in the Salmon Region in 2016. Little Bayhorse Lake, Perkins Lake, Squaw Creek Pond, Valley Creek, and the Yankee Fork Dredge Ponds are stocked with catchable Rainbow Trout several times each year, and Wallace Lake was stocked with catchable tiger trout in 2016. A proportion of stocked fish during each stocking event are tagged, and use and exploitation estimates for each stocked group of fish, based on tags reported, are adjusted by factoring in estimated tag reporting rates, estimated tag-loss rates, and estimated tagging mortality rates (Cassinelli 2014). For selected stocking events in 2016, 10% of stocked fish were marked with FLOY™ T-bar anchor tags for exploitation analysis. Tags used for this study were printed with a unique numerical code and information for anglers to report caught and harvested fish (Cassinelli 2014). IDFG contact information on the tags directed anglers to report tags to the Nampa Fish Research office where the data is stored. Estimated total use and exploitation for each stocking event were calculated based on methods reported in Meyer et al. (2010). We used the same statewide angler reporting rate estimate (58.0% in 2014) and statewide estimated tag-loss rate (2.5% for first year at large) used in the 2015 report (Messner et al. 2017) to calculate adjusted harvest and catch estimates in 2016. The estimated tagging mortality rate is a constant (0.8%, from Cassinelli 2014). In this report, we only generated estimates for each stocking group’s first year at large. Estimates for adjusted use and exploitation ( ) were calculated using the formula: ′ 푢 = (1 )(1 ) ′ Where: 푢 푢 푙 푚 = unadjusted harvest/catch rate휆 − 푇𝑇 − 푇𝑇 = angler tag reporting rate 푢 = first year tag-loss rate 휆 = tagging mortality rate 푙 푇𝑇 Ninety percent푇𝑇푚 (90%) confidence intervals were calculated for all harvest and catch estimates. For more information and details regarding these methods and associated formulas, see Meyer et al. (2010).

Angler Effort

From May 5 to August 8, 2016 we conducted a remote creel survey at Squaw Creek Pond using trail cameras. We also attempted to do the same at the Yankee Fork Dredge Pond 1, but cameras did not function properly so that data will not be used. We positioned one trail camera to photograph Squaw Creek Pond every hour, on the hour each day, from 0700 to 2100 hours. We downloaded photos once a month and stored them at the regional office. To estimate daily angler effort, we enumerated anglers in each photo, and then summed the total number of unique anglers, and total number of angler hours observed each day. We grouped estimates

into three categories (minimum effort, inferred effort, and maximum effort). Minimum effort was based on counts of individuals who were positively identified as anglers, inferred effort was based on minimum effort as well as individuals who were likely angling, and maximum effort was a sum of all individuals. We used inferred effort for our reported estimates. Daily counts were summed for each month to arrive at monthly angler effort estimates.

RESULTS AND DISCUSSION

Little Bayhorse Lake

Mackay Hatchery staff stocked 3,344 catchable Rainbow Trout in Little Bayhorse Lake in 2016; stocking occurred on June 23 (n = 1,061), June 28 (n = 939), and September 20 (n = 1,344). In 2016, we tagged 74 fish from the first stocking event (June 23) to estimate return-to- creel. As of March 1, 2017, five of the tagged fish were reported as harvested and two were reported caught and released (Table 7). Total use estimate (± 95% CI) for the June 23 group was 16.9% (± 13.0%) and harvest was 12.0% (± 11.0%) (Figures 13 and 14). By comparison, use and harvest estimates of stocked Rainbow Trout in 2015 at Little Bayhorse Lake were only 9.8% (± 6.3%) and 7.1% (± 5.3%), respectively (Figures 13 and 14; Table 8).

Our estimated return-to-creel rates for Rainbow Trout stocked in Little Bayhorse Lake on June 23, 2016 are very similar to what we found for the June 22, 2015 stocked group (Messner et al. 2017). Due to their remoteness and elevation, the Bayhorse Lakes only receive angling pressure from approximately mid-June through October each year. With such relatively low effort (compared to lakes that are open year round) estimated use values in the 10% - 20% range are acceptable. However, if possible, improving the quality of fishing at the lake may increase angler effort and return-to-creel. Little Bayhorse Lake was last gill netted in 1994, and four of the six Rainbow Trout caught in gill nets (CPUE = 0.35 fish/hr) measured greater than 350 mm TL (maximum 400 mm TL). With more current fish and forage data, we may be able to adjust stocking densities to better balance fish size and abundance, to improve the overall quality of the fishery.

Perkins Lake

Nampa/Sawtooth Fish Hatchery staff stocked 1,218 catchable Rainbow Trout in Perkins Lake in 2016, on June 21 (n = 448), July 25 (n = 473), and August 18 (n = 297). Forty-nine fish (~10%) were tagged during the first event only (June 21) to estimate return-to-creel rates. As of March 1, 2017, seven tagged fish were reported as harvested and two were reported as caught and released (Table 7). Use and harvest estimates (± 95%CI), based on tag returns, were 32.7% (± 21.5%) and 25.5% (± 19.1%), respectively (Figure 13; Table 7).

These estimated total use and exploitation values at Perkins Lake in 2016 are relatively high. Confidence intervals are wide due to small sample size, but our results suggest fish return to creel well in Perkins Lake. Even if Camp Perkins attendees account for a large portion of angling effort on the lake currently, stocking catchable Rainbow Trout should continue. In addition, the fact that catchable Rainbow Trout return to creel well in the lake suggests improved public access may increase the overall value and quality of the fishery. In the mid- 1980’s discussions were held between IDFG staff and Sawtooth National Recreation Area (SNRA) staff on improving public access to the lake. It was decided that a small public access point would be developed on the south side of the lake, with parking for 6 to 8 vehicles, and a

trail to 6 or so lakeside picnic tables. It was also decided that barriers would be placed to prevent anyone but the IDFG fish stocking truck from driving up to the lake on a spur road that took off from the proposed development area. Recently, SNRA staff have expressed interest in decommissioning this spur road, which would prevent the IDFG stocking truck from accessing the lake at the south end. Alternatively, the stocking truck can use the Camp Perkins boat ramp area, but currently only with permission from Camp Perkins staff. It is in our best interest to ensure the spur road remains intact until other permanent stocking arrangements can be made, and work with the SNRA to promote access to the lake for anglers

Squaw Creek Pond

Mackay Fish Hatchery staff stocked 1,032 catchable Rainbow Trout in Squaw Creek Pond in 2016, on May 6 (n = 270), May 24 (n = 364), June 14 (n = 199), and July 8 (n = 199). Twenty-seven fish were tagged during the May 6 event and 25 fish were tagged during the June 14 event to estimate return-to-creel. As of March 1, 2017, two fish were reported harvested from the May 6 event (one of which was harvested specifically because it was tagged) and one was reported as caught and released, and five fish were reported as harvested from the June 14 event (two of which were harvested specifically because they were tagged) and none were reported as caught and released (Table 7). Adjusted estimated use and harvest (± 95% CI) for the stocked groups (combined) in 2016 was estimated at 27.4% (± 12.5%) and 13.7% (± 10.3%), respectively (Figures 13 and 14; Table 7).

Compared to return-to-creel estimates at Squaw Creek Pond in 2015 (0.0%), 2016 results suggest excellent returns of stocked catchable Rainbow Trout. Although Squaw Creek Pond is very rural in terms of community ponds in the region, it seems that the fishery is relatively highly utilized. We estimated a total of 401 hours were spent fishing at Squaw Creek Pond between May 5 and August 8, 2016, based on our remote creel study (Table 9; Figure 15). Angler effort tended to be higher on weekends versus weekdays in May and June (Table 9), and overall was highest in June and July, over the duration of the study period (Figure 15). The inflow water at Squaw Creek Pond is typically turned off in late August for two reasons; 1) when irrigation demand is high (IDFG holds a junior water right for Squaw Creek), and 2) to prevent the water in Squaw Creek from becoming too warm. When water was shut off in August 2016, there were still an abundance of catchable Rainbow Trout left in the lake that had not been harvested. These fish are not likely to overwinter, as the lake depth draws down to <1 m when the inflow is turned off. Based on estimated angler effort and return-to-creel for catchable Rainbow Trout in 2016, we will consider reducing the stocking density slightly to reduce the number of fish leftover in the pond in the fall.

Valley Creek

We stocked 3,250 catchable Rainbow Trout in Valley Creek in 2016; stocking events occurred on: June 17 (n = 750), July 5 (n = 500), July 11 (n = 500), July 18 (n = 500), July 27 (n = 500), August 2 (n = 250), and August 17 (n = 250). We tagged 75 fish on June 17, 99 fish on July 5, and 50 fish on August 2 to estimate return-to-creel. As of March 1, 2017, 11 of the tagged fish were reported as harvested and three were reported caught and released from both the June 17 and July 5 stocking events, and two fish were reported as harvested and one as caught and released from the August 2 stocking event (Table 7). Total use estimates (± 95% CI) were 33.3% (± 18.0%), 25.2% (± 13.9%), and 10.7% (± 12.5%) for the June, July, and August groups, respectively, and harvest estimates were 26.1% (± 16.0%), 19.8% (± 12.3%), and 7.1% (± 10.3%), respectively (Figures 13 and 14). Total use and harvest for all fish tagged in 2016 (as a whole) was estimated at 24.7% (± 10.0) and 19.1% (± 8.6%), respectively.

Valley Creek has numerous sportsman’s access points, and it seems that stocked catchable Rainbow Trout are returning well (similar to the Salmon River in 2011 through 2013) (Table 8). Recommend continuing with the current stocking program.

Yankee Fork Dredge Ponds

Nampa/Sawtooth Fish Hatchery staff stocked 3,425 catchable Rainbow Trout in Yankee Fork Dredge Pond 1, 150 catchable Rainbow Trout in Yankee Fork Lower Dredge Pond, and 425 catchable Rainbow Trout in Yankee Fork Dredge Pond 4, in 2016. We tagged 50 fish stocked in Yankee Fork Dredge Pond 1 in June, 75 fish stocked in Pond 1 in July, and 20 fish stocked in Pond 1 in August. We also tagged 20 fish stocked in the Lower Dredge Pond and 21 fish stocked in Yankee Fork Dredge Pond 4, in August, 2106. For Pond 1, as of March 1, 2017, one tag was reported as harvested and one as released in June, 11 tags were reported as harvested and two as released in July, and four tags were reported as harvested and none as released in August (Table 7). Three tags were reported as harvested and none as released for both the Lower Dredge Pond and Pond 4 in August (Table 7). Based on tag returns, we estimated use and exploitation (± 95% CI) at Pond 1 was 7.1% (± 10.3%) and 3.6% (± 7.3%), respectively in June, 30.9% (± 17.4%) and 26.1% (± 16.0%), respectively in July, and 35.7% (± 33.7%) for both variables in August, for a combined mean of 23.4% (± 11.4%) and 19.7% (± 10.4%), respectively (Table 7 and Figures 13 and 14). Total use and exploitation (± 95% CI) for the Lower Yankee Fork Dredge Pond was estimated at 26.7% (± 29.9%) and 26.7% (± 29.9%), respectively in 2016, and for Pond 4 was 25.5% (± 28.6%) and 25.5% (± 28.6%), respectively in 2016 (Table 7 and Figures 13 and 14).

These results suggest catchable Rainbow Trout in the Yankee Fork Dredge Ponds are highly utilized by anglers, especially during July and August, during peak tourism season. Even though the Yankee Fork Dredge Ponds are closed to angling from December 1 until Memorial Day each year, they provide one of the more important put-and-take fisheries in the Stanley area. Other lakes in the Stanley area are more utilized as recreational waters (boating, water skiing, wind surfing) than as fisheries, and the Yankee Fork Dredge Ponds have become known for providing excellent catch rates and harvest opportunity. With such high estimated use and exploitation, we may consider increased stocking during the summer months in the Yankee Fork Dredge Ponds.

MANAGEMENT RECOMMENDATIONS

1. Survey Little Bayhorse Lake fish and zooplankton communities to determine if adjusting stocking practices could improve the quality of the fishery.

2. Continue current stocking program at Perkins Lake and work with SNRA staff to ensure public access and put-and-take stocking program remain intact.

3. Consider reducing catchable stocking slightly in Squaw Creek Pond, in late summer, to reduce the number of fish leftover in the pond when the inlet water is shut off in the fall.

4. Continue current stocking program in Valley Creek.

5. Evaluate angling effort at the Yankee Fork Dredge Ponds in 2017 to determine if changes in stocking practices can help improve the quality of these put-and-take fisheries.

Table 7. Estimated angler exploitation (fish harvested) and total use (fish caught) of catchable Rainbow Trout stocked in 2016 in selected Salmon Region waterbodies, up to March 1, 2017. HRBT is hatchery Rainbow Trout.

Disposition Adjusted exploitation Adjusted total use Tagging Tags Harvested Water body Species Harvested Released Estimate 90% C.I. Estimate 90% C.I. date released b/c tagged

6/23/2016 HRBT 74 5 0 2 12.0% 11.0% 16.9% 13.0% Little Bayhorse Lake

2015 overall 200 8 1 2 7.1% 5.3% 9.8% 6.3% Perkins Lake 6/21/2016 HRBT 49 7 0 2 25.5% 19.1% 32.7% 21.5% 5/6/2016 HRBT 27 1 1 1 6.6% 13.4% 19.8% 22.6% 6/14/2016 HRBT 25 3 2 0 21.4% 24.3% 35.7% 30.3% Squaw Creek Pond 2016 overall 52 4 3 1 13.7% 10.3% 27.4% 12.5% 2015 overall 40 0 0 0 0.0% n/a 0.0% n/a 6/17/2016 HRBT 75 11 0 3 26.1% 16.0% 33.3% 18.0% 7/5/2016 HRBT 99 11 0 3 19.8% 12.3% 25.2% 13.9% Valley Creek 8/2/2016 HRBT 50 2 0 1 7.1% 10.3% 10.7% 12.5% 2016 overall 224 24 0 7 19.1% 8.6% 24.7% 10.0% 6/8/2016 HRBT 50 1 0 1 3.6% 7.3% 7.1% 10.3%

Yankee Fork (YF) 7/7/2016 HRBT 75 11 0 2 26.1% 16.0% 30.9% 17.4% Dredge Pond 1 8/3/2016 HRBT 20 4 0 0 35.7% 33.7% 35.7% 33.7% 2016 overall 145 16 0 3 19.7% 10.4% 23.4% 11.4% YF Lower Dredge Pond 8/3/2016 HRBT 20 3 0 0 26.7% 29.9% 26.7% 29.9% YF Dredge Pond 4 8/3/2016 HRBT 21 3 0 0 25.5% 28.6% 25.5% 28.6%

Table 8. Estimated mean exploitation (Expl.) (fish harvested) and total use (fish caught) for all stocked catchable Rainbow Trout in a given year, in Salmon Region water bodies 2011 through 2016

2011 2012 2013 2014 2015 2016 Water body Expl. Use Expl. Use Expl. Use Expl. Use Expl. Use Expl. Use Alturas Lake ------1.4% 1.4% - - - - Big Bayhorse Lake ------25.6% 31.8% - - - - Blue Mountain Pond ------47.6% 47.6% - - Cape Horn Lake #1 ------4.5% 4.5% - - Hayden Pond ------20.1% 23.4% - - - - Hyde Pond - - 16.9% 46.1% - - 0.0% 0.0% - - - - Iron Lake #1 ------8.3% 11.1% - - - - Iron Lake #2 ------8.2% 11.0% - - - - Kids Creek Pond 25.5% 47.4% - - 19.5% 19.5% 17.2% 17.2% - - - - Little Bayhorse Lake ------16.1% 21.4% 12.0% 16.9% Meadow Lake ------38.0% 49.2% - - - - Mosquito Flats Reservoir - - - - 33.6% 36.4% - - 6.9% 9.2% - - Perkins Lake ------25.5% 32.7% Salmon River 10.9% 24.3% 15.3% 19.8% 11.5% 15.2% ------Stanley Lake 15.8% 26.2% 14.1% 26.2% 12.0% 15.1% 11.9% 18.9% - - - - Squaw Creek Pond ------0.0% 0.0% 13.7% 27.4% Valley Creek ------19.1% 24.7% Wallace Lake ------15.4% 22.3% - - - - YF Dredge Pond 1 ------19.7% 23.4% YF Dredge Pond 4 ------25.5% 25.5% YF Lower Dredge Pond ------26.7% 26.7%

Table 9. Angler use at Squaw Creek Pond from May 5 to August 8, 2016. Values were estimated using three remote trail cameras positioned around the lake, which captured hourly photos of anglers fishing. May June July August Week Weekend Week Weekend Week Weekend Week Weekend Angler hours 24 45 47 100 90 64 40 3 Mean hours/day 1.26 5.63 2.14 12.50 4.29 6.40 6.67 1.50

60% 2016 total use (catch) exploitation (harvest) 50%

40%

30%

20%

10%

0% Adjusted use and exploitation (± 95%CI) Little Perkins Squaw Valley YF Dredge YF Lower YF Dredge Bayhorse Lake Creek Creek Pond 1 Dredge Pond 4 Lake Pond Pond

Figure 13. Overall estimated total use (catch) and exploitation (harvest) of catchable Rainbow Trout in seven selected waterbodies in the Salmon Region in 2016.

70% total use (catch) 60% exploitation (harvest) 95%CI)

± ( 50%

40%

30%

20%

10% Adjusted use and exploitation 0% 5/6/2016 7/5/2016 8/2/2016 6/8/2016 7/7/2016 8/3/2016 8/3/2016 8/3/2016 6/23/2016 6/21/2016 6/14/2016 6/17/2016 2015 overall 2016 overall 2015 overall 2016 overall 2016 overall

Little Squaw Creek Pond Valley Creek YF Dredge Pond 1 Bayhorse YF Lower Lower YF

Lake YF 4 Pond Perkins Lake

Figure 14. Estimated total use (fish caught) and exploitation (fish harvested) (± 95% CI) based on angler tag returns for catchable- sized hatchery Rainbow Trout stocked in the Salmon Region in 2016. Overall averages for 2015 are also shown for lakes that were evaluated in both years.

180 160

140 120 100 80 60 Total angler hours 40 20 0 May 5-31 June 1 - 30 July 1 - 31 Aug 1 - 8 Time period surveyed

Figure 15. Estimated angler effort by month for Squaw Creek Pond in 2016, based on data gathered from remote trail cameras.

WALLACE LAKE REDSIDE SHINER AND TIGER TROUT SAMPLING

ABSTRACT

On June 8, 2016 we set two gill nets (one sinking and one floating) in Wallace Lake to determine fish size and condition after overwintering in the lake. We caught six tiger trout Salmo trutta x Salvelinus fontinalis in 6.2 hours of gill netting (CPUE 1.29 fish/hr) ranging in length from 305 mm to 345 mm TL, and averaging 327 mm. Although lengths were at the upper end of what was stocked in 2015, relative weights of fish that survived over winter were poor (47.9 to 72.3, mean 61.2). In June and July, 2016, another 1,200 tiger trout were stocked in the lake, ranging from 184 mm to 358 mm TL (mean 274.5 mm). Relative weights for the stocked group were much better (range 67.5 to 99.5, mean 84.8) than for tiger trout that overwintered. Similar to 2015, tiger trout were very healthy and active upon stocking, and we observed them chasing and feeding on groups of Redside Shiners Richardsonius balteatus.

The ultimate goals of stocking tiger trout were to reduce Redside Shiner density to increase forage available for stocked Rainbow Trout Oncorhynchus mykiss and Cutthroat Trout O. clarkii, and to provide a unique fishery for anglers, as tiger trout are rare in Idaho. Relative abundance of Redside Shiners caught in minnow traps was lower in 2016 than in 2015 for all three months sampled. Additionally, angler effort has increased 1.7 times from 2015 to 2016 (608 hours and 1,045 hours, respectively). Based on exploitation tagging, tiger trout harvest and use was relatively low in 2016 (estimated use 3.6%). However, with an estimated 20.5% use (fish caught) and 13.3% exploitation (fish harvested) in 2015, and nearly double the angler effort occurring in 2016, we believe exploitation and use were underestimated in 2016, and are likely higher than what was found in 2015.

Availability of large-bodied zooplankton in 2016 remained low and was very similar to what we found in 2014 and 2015. Forage competition is very likely for planktivorous fish.

Authors:

Jordan Messner, Regional Fisheries Biologist

Brent Beller, Regional Fisheries Technician II

Jon Hansen, Regional Fisheries Biologist

INTRODUCTION

Wallace Lake is a popular put-and-take trout fishery in the Salmon Region that was first stocked with Rainbow Trout Oncorhynchus mykiss in 1968. In 1978, Wallace Lake was classified as having low natural spawning potential for trout (Jeppson and Ball 1979), and has since been stocked with approximately 1,000 to 2,000 Rainbow Trout or Cutthroat Trout O. clarkii, annually, to sustain the fishery.

In the early 2000’s, Redside Shiners Richardsonius balteatus were first detected in Wallace Lake (Esselman et al. 2007). The source of Redside Shiner colonization is unknown (i.e. introduction or immigration), but over the last 15 years Redside Shiners have become the dominant fish species in the lake, and made up 92% of the catch composition during gill net sampling in June, 2005. Redside Shiners in the lake presumably compete with stocked Rainbow Trout for forage resources (Messner et al. 2015). Zooplankton abundance was so low by 2013 that biologists introduced tiger trout Salmo trutta x Salvelinus fontinalis to reduce Redside Shiner abundance in the spring of 2015. Mackay Fish Hatchery staff stocked 1,795 tiger trout in Wallace Lake during two stocking events in June, 2015.

We began monitoring the effects of tiger trout introduction on the Redside Shiner and zooplankton population in Wallace Lake in 2013. Redside Shiner abundance declined after tiger trout were introduced in 2015, but the abundance and quality of zooplankton did not increase (Messner et al. 2017). Continual sampling of both communities will help determine when the lake is again suitable for resuming stocking of catchable Rainbow Trout.

Prior to 2014, tiger trout had not been stocked in Idaho. However, tiger trout have been stocked in lakes in Western Washington (Miller 2010) and Utah (Winters 2014) since the early 2000s, in some cases as a means to reduce abundance of undesirable fish species (Budy et al. 2014) similar to our objectives in Wallace Lake. The tiger trout introduction at Wallace Lake was only the second in the state, and tiger trout were stocked as “catchables” (200 to 370 mm TL), which presented a unique opportunity for anglers. In 2015 we estimated 608 hours were spent fishing Wallace Lake, and stocked tiger trout were caught at a rate of 20.5%, and harvested at a rate of 13.3% (Messner et al. 2017). We are continually monitoring angler effort and catch/ harvest at Wallace Lake to see how this changes as tiger trout stocking continues.

OBJECTIVES

1. Monitor Redside Shiner abundance and zooplankton quality and abundance to determine how stocking tiger trout has affected prey and forage dynamics.

2. Monitor angler effort, catch, and harvest at Wallace Lake to determine how stocking tiger trout has affected the quality of the fishery.

STUDY SITE

Wallace Lake (WGS84 datum: 45.24625ºN, 114.00730ºW) is a 3.0 ha lake located approximately 32 km from the town of Salmon. The lake sits at an elevation of approximately 2,470 meters, and has a maximum depth of approximately 10 meters. This lake has been managed as a put-and-take Rainbow Trout fishery since 1968, and has also received periodic stocking of Cutthroat Trout fry and fingerlings since the mid-1990’s. In 2014, we assessed return-to-creel rates on approximately 2,150 stocked catchable Rainbow Trout in the lake,

Harvest and catch were 15.4% and 22.3%, respectively (Messner et al. 2016). Although angler use has been fair, we have observed an overall decrease in body condition of stocked Rainbow Trout at the lake since the early 2000’s when Redside Shiners were first documented. It is likely that an increasing Redside Shiner population has led to a reduction in forage resources, thereby resulting in the poor condition of stocked Rainbow Trout over the last several years (Messner et al. 2015). In June, 2015, we stocked 1,795 catchable-size (200 to 370 mm TL) tiger trout to try to reduce abundance of Redside Shiners and increase available forage for stocked catchable Rainbow Trout. Another 1,200 catchable tiger trout were stocked in 2016.

METHODS

While surveying the lake in June 2016, we conducted a depth profile with handheld depth sonar and handheld GPS unit to collect data points that would be used to construct a bathymetric map of the lake bed. GPS referenced depth points were uploaded to ArcMap 10.1 and used to create a triangulated irregular network (TIN) to create a series of polygons showing the contours of the lake bottom (Appendix C).

Biological Sampling

Tiger Trout

On June 8, 2016, prior to stocking for the year, the existing tiger trout in Wallace Lake were sampled by deploying one sinking and one floating monofilament gill net (36 m long by 1.8 m deep, and composed of six panels of 10.0, 12.5, 18.5, 25.0, 33.0, and 38.0 mm mesh) for three hours each, to determine relative abundance and condition of fish that survived over winter. Then, on June 16 and July 13, 2016, Mackay Fish Hatchery staff stocked 1,200 catchable size (200 to 370 mm TL) tiger trout in Wallace Lake during two stocking events (749 and 451, respectively). A subsample (~10%, n = 75) of tiger trout from the first stocking event were weighed (g), measured (mm TL), and tagged with FLOY t-bar anchor tags to estimate return-to-creel rates, using the Tag-You’re-It program methodology (Cassinelli 2015).

We compared body condition for tiger trout at the time of stocking in 2016 to tiger trout that were stocked in 2015 and overwintered using relative weight (Wr). We first calculated standard weight (Ws) using the equation:

( ) = + (total length (mm))

where a and b were derived퐿퐿퐿 10from푊푠 the 푎length푏 ∗-weight퐿퐿퐿10 relationship for Brown Trout in Blackwell et al. (2000) (a = -4.867 and b = 2.96, Appendix A). This relationship most closely resembled the length-weight relationship we observed from the tiger trout we stocked in Wallace Lake in 2015 (r2 = 0.91, a = -4.738 and b = 2.90). Relative weight was then calculated using the equation:

weight (g) = 100

푊푟 � � ∗ 푊푠 Redside Shiners

Minnow trapping methods for Redside Shiners in 2016 followed the same methods outlined in the 2014 IDFG Salmon Region Annual Report (Messner et al. 2016). Redside Shiners were trapped using Promar collapsible minnow traps (38 cm L x 24 cm W x 26 cm H,

with a 3 cm opening and 2 mm x 4mm mesh size) baited with canned tuna in oil. Traps were deployed on June 8, July 22, and September 15, 2016 to track relative abundance using catch- per-unit-effort (CPUE) and determine the seasonal size structure of the Redside Shiner community.

Nine trap clusters, consisting of three minnow traps each, were uniformly deployed around the lake perimeter and fished for one hour during each of three capture events (Figure 16, Table 10). Trap clusters were set 2-3 meters away from shore at an average depth of 1 m. Redside Shiners were then enumerated by trap for each cluster. Weight (g) and total length (mm) measurements were taken from a subsample of approximately 50 shiners randomly collected from each trap cluster, during each capture event. If fewer than 50 Redside Shiners were captured in a cluster, then all individuals were sampled. Exact fishing start and stop times were recorded to calculate catch-per-unit-effort (fish per minute). This information was then used to compute Redside Shiner relative abundance and size structure for comparison to past and future trapping events. We used paired t-tests (α = 0.05) to test for differences in trap cluster catch-per-unit-effort from 2015 to 2016, for June, July, and September.

Zooplankton

Zooplankton sampling was conducted at Wallace Lake at two locations on August 17, 2016. The lake is only 2.7 ha in size and does not have a well-defined inlet, so we only sampled near the outlet and at mid-lake (no sampling near the inlet). We performed three vertical tows, using Wisconsin-style plankton nets with mesh sizes 153µm, 500µm, and 750µm, at each location following methods outlined in Teuscher (1999). Samples were stored in 100% ethyl alcohol for thirteen days, at which time contents were weighed and zooplankton ratio index (ZPR) and zooplankton quality index (ZQI) were calculated using the methods outlined in Teuscher (1999).

Angler Effort and Return-to-Creel

We conducted a remote creel survey at Wallace Lake using trail cameras from June 8 to October 12, 2016. We positioned three trail cameras to photograph the entire lake (Figure 17). All three cameras were set to take photos at the same time (every hour, on the hour) each day, from 0700 to 2100 hours. We downloaded photos once a month and stored them at the regional office. To estimate daily angler effort, we enumerated anglers in each photo and referenced between cameras to make sure no anglers were enumerated twice during any given hour. We then summed the total number of unique anglers, and total number of angler hours observed each day from the three cameras. We grouped estimates into three categories (minimum effort, inferred effort, and maximum effort). Minimum effort was based on counts of individuals who were positively identified as anglers, inferred effort was based on minimum effort as well as individuals who were likely angling, and maximum effort was a sum of all individuals. We used inferred effort for our reported estimates. Daily counts were summed for each month to arrive at monthly angler effort estimates.

Return-to-creel rates (exploitation and use) were estimated using the methods outlined in chapter two of this report (Chapter Two: Exploitation Studies) (Cassinelli et al. 2015). Mackay Fish Hatchery staff stocked 1,200 catchable tiger trout in Wallace Lake during two stocking events in June (June 16, n = 750; July 13, n = 450). Approximately 10% of the stocked fish from the first event only (n = 75) were tagged to estimate return-to-creel. Detailed methods and calculations can be found in Meyer et al. (2010).

RESULTS AND DISCUSSION

Biological Sampling

Prior to stocking in 2016, we caught six tiger trout in 6.2 hours of gill netting (CPUE 0.97 fish/hr) ranging from 305 mm to 345 mm TL, and averaging 327 mm (Figure 18). Although tiger trout lengths were at the upper end of what was stocked in 2015 (Figure 18), relative weights of fish that survived over winter were poor (mean Wr = 61.2; range 47.9 - 72.3) (Figure 18). Subsampled tiger trout stocked on June 16, 2016 (n = 75) ranged from 184 mm to 358 mm TL (mean 274.5 mm), and relative weights were much better (mean Wr = 84.8; range 67.5 to 99.5) (Figure 18). Similar to in 2015 (Messner et al. 2017), tiger trout were very healthy and active upon stocking, and we observed them chasing and feeding on groups of Redside Shiners. However, we are not sure why we are observing decreasing body condition (Wr) of tiger trout throughout the year after they are stocked. From September 2014 to September 2015, we observed a significant decrease in Redside Shiner abundance (Messner et al. 2017), suggesting they were either being consumed by stocked tiger trout, or had altered their behavior to avoid tiger trout predation. This should have promoted excellent growth of tiger trout that overwintered in the lake, but our results don’t support this. Anglers do report catching tiger trout with good body condition at the lake, but we have yet to see such tiger trout during sampling. Perhaps the most aggressive tiger trout are being caught and harvested by anglers, therefore preventing them from being captured in our gill nets.

Redside Shiners were trapped on three occasions in 2016, similar to 2015. We caught 1,568 Redside Shiners in June, 1,739 Redside Shiners in July, and 327 Redside Shiners in September, 2016 (Figure 19). Overall CPUE was 2.67 fish/minute in June, 3.27 fish/minute in July, and 0.57 fish/minute in September, 2016 (Table 11). Mean CPUE for the trap clusters decreased significantly from July 2015 to July 2016 (df = 8, p < 0.001), and from September 2014 to September 2016 (df = 8, p = 0.001), and although it decreased from September 2015 to September 2016, the difference was not significant (df = 8, p = 0.13) (Figure 20). Mean CPUE was lower in 2016 than in 2015 for all three months (Figure 20). During each capture event in 2016, a subsample of Redside Shiners was measured and weighed (June = 450, July = 450, September = 148). Mean total length and condition factor of subsampled Redside Shiners was similar for all three months sampled, and was also similar to values obtained in 2015 (Figure 19 and Table 11). Mean TL (± SE) was 92 mm (± 0.65) in June, 93 mm (± 0.71) in July, and 92 mm (± 0.87) in September (Table 11, Figure 19), and condition factor (K) was 0.82 (± 0.00) in June, 0.84 (± 0.00) in July, and 0.92 (± 0.01) in September (Table 11).

Similar to what we observed from September 2014 to September 2015 (Messner et al. 2017), Redside Shiner abundance continued to decrease in 2016 (Figure 20). Redside Shiner condition factor was also the highest we’ve observed in all sampling periods in September 2016 (Table 11), and it appears the smallest size range of Redside Shiners we saw during previous sampling events was not captured in September 2016 (Figure 19). These findings suggest a change may be occurring in Redside Shiner population structure. However, we suspect the observed decrease in CPUE is partially due to a change in behavior to avoid predation, rather than solely a reduction in abundance. We observed a change in Redside Shiner behavior in the lake, where prior to tiger trout introduction they were visible throughout the lake’s littoral areas, and after tiger trout introduction they seemed to prefer hiding in covered habitat. Predator avoidance behavior by Redside Shiners would also explain the poor growth and condition of stocked tiger trout if they are unable to effectively prey upon Shiners. Further sampling will hopefully provide more insight.

Zooplankton sampling on August 17, 2016 found mean ZPR = 0.04, mean ZQI = 0.01, and mean total biomass = 1.24 g/m3 (Table 12). Values are nearly identical to what was found in 2015 (Figure 21). Although total zooplankton biomass remains at 1.24 g/m3, abundance of large zooplankton (those needed to sustain quality growth for planktivorous trout) has not increased at all, therefore we are not yet ready to resume stocking of catchable Rainbow Trout in the lake, until ZPR and ZQI values show an increase.

Angler Effort and Return-to-Creel

Camera one malfunctioned and did not capture photos from June 22 to September 14, and Camera three malfunctioned from July 21 to September 14 (Figure 17). Due to camera malfunctions, we may have missed some angler effort during those periods. The estimates should therefore be considered a ‘minumum’ amount of effort. Estimated angler effort at Wallace Lake from June 8 to October 12, 2016 was 1,045 hours (Table 13). Angling effort followed a similar trend as was found in 2015, with a peak in July and August (Table 13, Figure 22). Estimated angler effort was over 1.7 times greater than was estimated using the same methods in 2015 (Messner et al. 2017). The last creel survey conducted at Wallace Lake prior to 2015 was in 1988, between June 1 and September 5, and estimated 2,805 hours fished. However, comparing 2015 and 2016 results to the 1988 estimate is likely not viable. The 1988 survey was an expanded estimate, generated from only four or five days of sampling per month, and favored weekend sampling which likely overestimated angling effort for the entire period. In 2015, we found angler effort was, on average, 41% higher on weekend days versus weekdays (6.1 hours per day versus 3.6 hours per day, respectively) (Messner et al in press). Angler effort was proportionally higher in the afternoon in 2015, compared to 2016 when it seemed to be proportionally higher from around 1000 to 1400 (Figure 23). The increase in angler effort from 2015 to 2016 is likely due to the fact that Wallace Lake is one of the few lakes in Idaho where tiger trout were stocked in spring 2015, so the fishery has presented a unique opportunity which is being increasingly utilized.

Of 75 tagged tiger trout, only one was reported as harvested, so use was only estimated at 3.6%, with 4.9% confidence intervals. Additionally, three tiger trout tagged in 2015 were reported as harvested in 2016. Even though the bag limit for tiger trout at Wallace Lake was decreased in 2016, to 2 per day, we believe there is substantially more harvest on tiger trout in the lake than what our data suggest. In 2015, total use for each stocked group was 14.1% and 25.5%, respectively, for an overall average of 20.5% total use across both groups (Messner et al. 2017). Perhaps many anglers are practicing catch-and-release to allow the tiger trout to get larger, since relative weights are relatively poor. Alternatively, many anglers simply do not report catching tagged fish, knowing there is no monetary value on these tags. In either case, angler effort nearly doubled from 2015 to 2016, despite the decrease in bag limits. Overall, anglers that catch tiger trout at Wallace Lake are pleased with the opportunity to catch a new and different species of fish (information obtained from angler comments, J. Cassinelli, IDFG, personal communication). Return-to-creel rates suggest these fish are readily available to anglers, but that anglers are not inclined to keep all tiger trout caught. This is especially important considering tiger trout were introduced in the lake in order to reduce Redside Shiner abundance through predation, and harvest may have inhibited our ability to detect any biological response to the introduction. Tag returns for fish that were stocked in the lake the previous year are promising, suggesting decent overwinter survival. Although fish condition (relative weight) is relatively low for fish that overwinter, we are hopeful that as fish grow larger in size they will utilize Redside Shiners more as a prey source.

MANAGEMENT RECOMMENDATIONS

1. Continue monitoring Redside Shiner abundance, size structure, and condition as they relate to the effects of tiger trout introduction.

2. Continue annual monitoring of zooplankton quality and abundance to determine the primary forage-base response to tiger trout introduction.

3. Stock additional tiger trout in 2017 to supplement the growing fishery, and evaluate exploitation and use of these fish to guide future stocking needs.

4. Evaluate angler effort in 2017 to determine the influence of establishing this unique fishery on angler dynamics at the lake.

Table 10. Minnow trap cluster locations (WGS84) (±3m) used for Wallace Lake Redside Shiner monitoring. Location (WGS84) Cluster No. Latitude °N Longitude °W 1 45.24627498 -114.00484100 2 45.24596804 -114.00467399 3 45.24570501 -114.00516098 4 45.24545900 -114.00614603 5 45.24542397 -114.00746903 6 45.24593703 -114.00725797 7 45.24650901 -114.00701104 8 45.24698996 -114.00608903 9 45.24695601 -114.00522301

Table 11. Summary statistics from Wallace Lake Redside Shiner sampling, 2005-2016, including Redside Shiner sub-sample size (n), relative abundance (CPUE), total length statistics (mm), and condition factor (K). Total length (mm) Condition factor (K) Total # CPUE Mean caught (fish/min) n Min Max (SE) Min Max Mean (SE) Aug 20 13 101 1.12 101 57 141 86 (1.21) 0.50 1.08 0.77 (0.01) Jun 2014 647 2.70 480 73 156 93 (0.48)a 0.41 1.59 0.88 (0.01) Aug 2014 178 0.74 178 41 140 83 (1.10)a 0.35 1.46 0.82 (0.01) Sep 2014 1,818 3.30 457 45 149 89 (0.75)a 0.44 1.32 0.86 (0.00) Jun 2015 1,670 3.01 455 57 147 95 (0.75) 0.40 1.16 0.82 (0.00) Jul 2015 3,107 5.74 450 53 156 94 (0.84) 0.45 2.10 0.82 (0.01) Sep 2015 666 1.22 371 42 156 91 (1.09) 0.26 1.47 0.82 (0.01) Jun 2016 1,568 2.67 450 64 149 92 (0.65) 0.39 1.23 0.82 (0.00) Jul 2016 1,739 3.27 450 55 159 93 (0.71) 0.57 1.20 0.84 (0.00) Sep 2016 327 0.57 148 49 129 92 (0.87) 0.53 1.31 0.92 (0.01) a Standard errors (SE) were reported incorrectly in 2014 management report (Messner et al., 2016)

Table 12. Zooplankton total biomass, ZPR, and ZQI average values obtained from mid-august sampling, 2013-2016. Survey Year 2013 2014 2015 2016 Mean total biomass (g/l) 0.48 0.70 1.23 1.24 Mean zooplankton Ratio (ZPR) 0.33 0.00 0.00 0.04 Mean zooplankton quality index (ZQI) 0.01 0.00 0.00 0.01

Table 13. Angler use at Wallace Lake from June 8 to October 26, 2015, and June 8 to October 12, 2016. Camera one did not function from June 22 to September 14, and Camera three did not function from July 21 to September 14, in 2016. Values were estimated using three remote trail cameras positioned around the lake, which captured hourly photos of anglers fishing. June July August September October Total 2015 2016 2015 2016 2015 2016 2015 2016 2015 2016 2015 2016 Anglers (#) 64 147 137 238 90 126 67 43 52 8 410 562 Angler hours 87 278 195 418 122 243 126 92 78 14 608 1045

Figure 16. Locations (± 3.0m) of minnow trap clusters and boat ramp shore access used for Wallace Lake Redside Shiner trapping. Specific coordinates are displayed in Table 10.

Figure 17. Camera locations and directions of view for estimating angler effort in 2015 and 2016 at Wallace Lake.

40% June 2015 (stocked) (n=178) 30% (mean = 285.6 mm TL)

20%

10%

40% September 2015 (gill netted) (n=30) 160 (mean = 310.7 mm TL) Spring 2015 30% Fall 2015 120 20%

10% 80

0% 40

40% 160 June 2016 (overwintered) Overwintered 2016 (n=6) Stocked 2016 Relative Frequency Relative (mean = 327.5 mm TL) Weight Relative 30% 120

20% 80

10% 40 0%

40% June 2016 (stocked) TL (mm) (n=75) 30% (mean = 274.5 mm TL)

20%

10%

TL (mm)

Figure 18. Relative frequencies and relative weights of tiger trout stocked and gill netted in Wallace Lake in 2015 and 2016.

0.20 June 2014 September 2014 0.15

0.10

0.05

0.00

0.20

June 2015 July 2015 September 2015 0.15

0.10

0.05 Relative Frequency Relative 0.00

0.20 June 2016 July 2016 September 2016 0.15

0.10

0.05

0.00 40 60 80 100 120 140 160 40 60 80 100 120 140 160 40 60 80 100 120 140 160

TL (mm)

Figure 19. Size structure of the Redside Shiner population in Wallace Lake during sampling efforts from June, 2014 to September, 2016. June 2014 is the only sampling date where only four minnow traps were used, versus the nine clusters of three traps used for all other periods.

7.0 2014 SE)

6.0

± 2015 ( 5.0 2016 4.0 3.0 2.0 1.0 CPUE (fish/min) 0.0 June July September

Figure 20. Catch-per-unit-effort (fish/min ± SE) of Redside Shiners captured during minnow trapping in Wallace Lake in June, July, and September 2014-2016.

1.40

1.20 Mean Total biomass (g/l) 1.00 Mean Zooplankton Ratio 0.80 (ZPR) 0.60 Mean Zooplankton Quality

Mean total Mean total Index (ZQI) 0.40 biomass/ZPR/ZQI 0.20 0.00 2013 2014 2015 2016

Figure 21. Zooplankton quality and abundance values from Wallace Lake in mid-August, 2013-2016.

500

400 2015 2016 300

200

100 Angler effort (hours) 0 June July August September October

Figure 22. Monthly angler effort at Wallace Lake, June 8 through October 26, 2015 and June 8 through October 12, 2016. Camera one did not function from June 22 to September 14, and Camera three did not function from July 21 to September 14, in 2016.

160

140 2015 120 100 2016 80 60 40 Angler effort (hours) 20 0

Time of day (24 hr) Figure 23. Angler effort by time of day at Wallace Lake June 8 through October 26, 2015 and June 8 through October 12, 2016. Camera one did not function from June 22 to September 14, and Camera three did not function from July 21 to September 14, in 2016.

REGIONAL LAKE INVENTORIES

ABSTRACT

In Buster Lake in 2016, we caught 60 Brook Trout Salvelinus fontinalis in 27.5 gill net hours (CPUE 2.18 fish/hr), ranging in size from 157 to 389 mm TL. PSD-Q for Brook Trout in the lake was 45% in 2016, compared to only 12% in 2002. In Stanley Lake, we caught 38 Lake Trout S. namaycush in 472.4 gill net hours (CPUE 0.08 fish/hr). Similar to all years except 2012, we were unable to effectively sample juvenile Lake Trout in the 200 mm to 450 mm TL size range. However, we were able to determine areas of the lake where Lake Trout seemed to aggregate prior to stratification. We also gill netted Stone Reservoir for 3.0 hours in 2016, and caught one Westslope Cutthroat Trout Oncorhynchus clarkii and one Bull Trout S. confluentus. Stone Reservoir is very shallow, and probably does not support overwintering trout. However, trout from Little Timber Creek likely use the reservoir during open water seasons.

Author:

Jordan Messner, Regional Fisheries Biologist

INTRODUCTION

The Salmon Region defines lowland lakes as being generally accessible by road and able to be stocked with fish by truck. There are 23 lowland lakes, two reservoirs, and 11 public ponds in the Salmon Region (Curet et al. 2011). Fisheries management objectives for lowland lakes in the Salmon Region focus on providing diverse angling opportunities (i.e. species diversity), with angling catch rates above 1 fish/hr, and diverse size structure, including opportunity for trophy-size fish when possible. Understanding fish species composition, relative abundance, and size structure is an important part of managing these fisheries, and helps us prioritize management efforts where they are most likely to provide benefit to anglers.

OBJECTIVES

1. Determine the species composition, relative abundance, size structure, and condition of fish in Buster Lake.

2. Determine gill netting locations and depths most effective for targeting Lake Trout Salvelinus namaycush in the spring at Stanley Lake.

3. Gather baseline fish population information, including abundance and size structure, for Stone Reservoir to evaluate its potential as a fishery.

STUDY SITES AND METHODS

Buster Lake

Buster Lake (WGS84 datum: 44.43980o N, -114.415529o W) is located at the head of Garden Creek, approximately 20 km from the town of Challis, in the Salmon-Challis National Forest. It is a natural lake that has a surface area of 3.1 ha and sits at 2,610 m in elevation. In 1908, the Forest Service issued William Buster a special use permit to turn Buster Lake into a water storage reservoir, by completing a tunnel through the rock below and installing a gate to control flow. A new owner took over the permit in 1931 and signed into an agreement with the Forest Service to share maintenance responsibility. From then until around 1979, the Forest service maintained majority ownership of the water in the lake. In 1961, Buster Lake was last estimated to hold approximately 139 acre feet of water when full (Salmon Region IDFG records - Buster Lake Dam Meeting transcripts, 1982). The Forest Service gave their share of the water to the City of Challis in 1979.

According to our stocking records, IDFG began stocking the lake in 1937 with 2,000 Brook Trout S. fontinalis from Ashton Hatchery. It was stocked once with Rainbow Trout Oncorhynchus mykiss in 1938, then was stocked solely with Brook Trout several times until 1998, and was last stocked in 2001 with Rainbow Trout. In 2002 it was determined that Brook Trout were outcompeting Rainbow Trout, and stocking was halted. The lake is accessible by full size vehicle, and there are several camping areas present.

We set one pair of standard lowland lake gill nets (one sinking and one floating, per pair) (46 m x 2 m, with six panels consisting of 19, 25, 32, 38, 51, and 64 mm bar mesh) overnight in Buster Lake on the evening of June 23, 2016 to determine the species composition, relative

abundance, and size structure of fish in the lake. Fish caught in the gill nets were identified to species, enumerated, measured (mm TL), and weighed (g). We built length-frequency histograms to describe overall size structure, and we calculated proportional stock density for Brook Trout using minimum stock and quality lengths proposed in Willis et al. (1993) (200 mm TL and 330 mm TL, respectively). Relative abundance (catch-per-unit-effort, CPUE) was calculated as the total number of fish caught, divided by the total number of gill net hours. Relative weight (Wr) was calculated using the standard weight formula (Ws):

( ) = + (total length (mm))

where a = the intercept value퐿퐿퐿10 and푊푠 b =푎 slope푏 ∗ derived퐿퐿퐿10 from Blackwell et al. (2000) (Appendix A), and then converting back to base 10 to solve for Wr:

weight (g) = 100

푊푟 � � ∗ While surveying the lake in June 2016,푊푠 we conducted a depth profile with handheld depth sonar and handheld GPS unit to collect data points that would be used to construct a bathymetric map of the lake bed. GPS referenced depth points were uploaded to ArcMap 10.1 and used to create a triangulated irregular network (TIN) to create a series of polygons showing the contours of the lake bottom (Appendix D).

Stanley Lake

Stanley Lake (WGS84 datum: 44.24371ºN, 115.05653ºW) is located in the Sawtooth Basin, near Stanley, Idaho. Stanley Lake is 71.3 ha in size and sits at 1,990 m in elevation. IDFG first stocked the lake in the 1940’s, and has been stocking hatchery catchable Rainbow Trout since 1956 (IDFG stocking website). We stocked ~14,000 catchable Rainbow Trout in Stanley Lake in 2014, ~7,000 in 2015, and ~9,500 in 2016. The Sawtooth Basin is a popular destination for tourists during summer months, so the lake is managed as a put-and-take opportunity for visiting anglers. In addition to stocked Rainbow Trout, there are naturally reproducing Kokanee Salmon O. nerka, Brook Trout, Westslope Cutthroat Trout O. clarkii, Bull Trout S. confluentus, Lake Trout and Redside Shiners Richardsonius balteatus in Stanley Lake. Trout limit is six per person per day, with the exception of Brook Trout (25 per day) and Bull Trout (0 per day, catch-and-release only).

We conducted a temperature profile on May 21, 2016 at Stanley Lake to determine if the lake had stratified yet. Profiles were conducted in the middle of the lake using a YSI 556MPS multi-meter probe with a 20m sensor cord.

Increased interest has developed over the last few years in the region to understand the dynamics of the Lake Trout population in Stanley Lake, and ensure this unique fishery does not have negative impacts on native fish restoration efforts in the area (i.e. Sockeye Salmon O. nerka recovery). Our objective was to determine Lake Trout population relative abundance and size structure, and continue exploring where and how they can effectively be sampled in the spring in Stanley Lake. We set a combination of standard lowland lake floating gill nets and sinking gill nets (46 m x 2 m, with six panels consisting of 19, 25, 32, 38, 51, and 64 mm bar mesh) for a total of 472.4 gill net hours at Stanley Lake between May 20-25, 2016. We also set five trap nets for a total of 368.1 hours. While trap nets were left in the water constantly and

checked once per day, gill nets were checked every one to three hours to reduce lake trout mortality. Both gill nets and trap nets were fished at varying depths, and approximate depths and locations for all Lake Trout caught were recorded. All Lake Trout caught in the gill nets were enumerated, measured (mm TL), and weighed (g), and sex was determined based on external examination of the urogenital region (Mohr 1982). Relative abundance (catch-per-unit-effort: CPUE) was calculated as the total number of fish caught divided by the total number of gill net hours. Relative weight (Wr) was calculated using the same formulas outlined above, with slope and intercept values obtained from Blackwell et al. (2000).

Stone Reservoir

Stone Reservoir (WGS84 datum: 44.579356ºN, 113.468532ºW) is located in the Lemhi Range, approximately 15 km southwest of Leadore, ID. The reservoir is on Timber Creek, a tributary to the Lemhi River, and currently has a surface area of 7.0 ha, and sits at an elevation of 2,320 m. The original dam was constructed in 1909 and gave the reservoir a water storage capacity of approximately 300 acre feet, with a surface area of approximately 12.5 ha. The Forest Service declared the old dam a hazard in 1963, and the reservoir was drained. In the late 1960s and early 1970s, ranchers in the area attempted to rebuild the dam to hold some 700 acre feet of irrigation water, and sought a partnership with IDFG on the project in exchange for a minimum pool of 100 acre feet (~4 m max depth at draw down). Due to financial constraints, the project did not come to fruition. Although IDFG records do not show a stocking history for Stone Reservoir, an interdepartmental memo from Don Corley to Stacy Gebharts in 1967 (Salmon Region IDFG records) suggests catchable Rainbow Trout were stocked in years prior to the reservoir being drained, and few fish carried over the winter. Corley also writes that resident fish (from Timber Creek) inhabit the reservoir throughout the year. We have no survey history for the reservoir, but are anecdotally aware of Westslope Cutthroat Trout and Bull Trout from Timber Creek using the reservoir throughout the year.

When we visited the lake on July 12, 2016, we conducted a depth profile with handheld depth sonar and handheld GPS unit to collect data points that would be used to construct a bathymetric map of the lake bed. However, the GPS malfunctioned, so depth points could not be accurately spatially referenced. While conducting the depth profile we found that the lake was primarily less than 1.0 m deep, so we found the only deeper portion of the lake (~2 m deep) for setting our gill net. We set one sinking and one floating standard lowland lake gill net (46 m x 2 m, with six panels consisting of 19, 25, 32, 38, 51, and 64 mm bar mesh) to determine the composition, relative abundance, and size structure of the fish community. Fish caught in the gill nets were identified to species, enumerated, measured (mm TL), and weighed (g). Relative abundance (catch-per-unit-effort: CPUE) was calculated as the total number of fish caught, divided by the total number of gill net hours. Relative weight (Wr) was calculated using the same methods outlined above.

RESULTS AND DISCUSSION

Buster Lake

We caught 60 Brook Trout in 27.5 hours of gill netting on June 23, 2016 (CPUE 2.18 fish/hr) (Table 14, Figure 24). Mean TL of Brook Trout TL was 292 mm TL (± 7.7) and ranged from 157 mm to 389 mm. Mean Wr was 93 (range: 74 – 121) (Figure 24) and PSD-Q was 45%, compared to 12% in 2002.

The Brook Trout in Buster Lake are some of the largest in the Salmon Region. Perhaps spawning opportunity in Buster Lake is scarce enough that Brook Trout reproduction occurs only at a very low rate, so fish abundance is limited and quality forage is readily available. However, proportion of quality size fish in the stock range (PSD-Q) increased from 12% in 2002 to 45% in 2016 (Figure 24), and fish abundance in 2016 was higher than was found in both 1993 and 2002 (Table 14), This lake offers a unique opportunity to catch relatively large Brook Trout.

Stanley Lake

A temperature profile conducted on May 19, 2016 determined Stanley Lake had not yet stratified (Figure 25). We captured 38 Lake Trout in 472.4 total hours of gill netting over the next five days, from May 20 to 25, 2016 (CPUE = 0.08 fish/hr) (Table 15). All Lake Trout were caught in sinking gill nets, between a depth of 6 to 18 m (mean = 11 m), and usually along steep lake contours. No Lake Trout were caught during 54.0 hours using floating gill nets, or during 368.1 hours using trap nets. We also obtained length and weight measurements from one other Lake Trout that was harvested by an angler while we were sampling, for a total of n = 39. Additionally, we caught one Bull Trout, one Westslope Cutthroat Trout, 28 Brook Trout, and more than 15 kokanee salmon during gill netting (only 15 were enumerated and measured). We did not catch any Rainbow Trout in the lake in 2016, as we have in most other years. The 15 kokanee salmon we measured ranged in size from 141 to 234 mm TL (mean: 212 mm TL) (Table 15). Lake Trout ranged in size from 216 to 1083 mm TL (mean: 606 mm TL) (Table 15, Figure 26), and relative weights ranged from 59 to 112 (mean: 88), similar to in 2012 (Table 15, Figure 27).

Relative abundance for Lake Trout captured in gill nets has remained relatively steady over the past four sampling periods, despite that effort has varied widely (Table 15). Likely the best sample we’ve obtained to describe Lake Trout population size structure over the past decade was in 2012 (n = 203) (Figure 26). We’ve learned over the past few years that our standard lowland lake gill nets appear to be very size biased when sampling for Lake Trout, and it can be difficult to collect younger fish in the 200 mm to 450 mm size range (Figure 26). Although sampling all size classes has not been effective in most years (except 2012), we have narrowed down locations of aggregations of Lake Trout during early spring prior to stratification, as well as in late fall for spawning (Flinders et al. 2013). Summer telemetry work done by regional staff in 2012 showed that Lake Trout in Stanley Lake were dispersed in deep water throughout the lake during mid-summer months, but aggregated at the northeast end of the lake near the outlet in October and November for spawning. In spring 2015 and 2016, we found that Lake Trout tended to group along steep lake bottom contours, between 6 to 18 m deep, and major aggregations were located in the west, southwest, and northeast ends of the lake, as well as along the southeastern shoreline. However, we were not effective at sampling juvenile Lake Trout during either of those years.

In order to more effectively sample younger Lake Trout in Stanley Lake, we may need to have gill nets made specifically for this purpose (Nick Wahl, IDFG, personal communication). To capture juvenile Lake Trout in Lake Pend Oreille (LPO), IDFG researchers use nets consisting of only 50 mm and 75 mm stretched mesh, 6 mm diameter twine, with floats tied “on the half” meaning the mesh is loose so fish get tangled and “bag” themselves easier. Additionally, nets used in LPO are set in 800 m long strings, in a serpentine pattern, which has proven most effective for catching Lake Trout. Although we do not have the capability to set such large strings of nets (LPO is gill netted by commercial fishermen), designing longer nets with selective mesh sizes and smaller twine diameter, and setting those nets in a serpentine pattern as

suggested by LPO research staff, may help us obtain a better sample of younger Lake Trout in Stanley Lake.

The Lake Trout fishery in Stanley Lake has come under scrutiny in recent years, due to the amount of effort being spent on Sockeye Salmon recovery in the Sawtooth Basin, and the perceived threat of Lake Trout on accomplishing these objectives. Currently, regional staff are developing a management plan for Stanley Lake to alleviate concerns over the possibility of Lake Trout expansion into other lakes in the drainage, which may pose possible threats to established Bull Trout and Sockeye Salmon populations through competition and/or predation. Another consideration in formulating the management plan is whether we can preserve this trophy Lake Trout fishery that is highly regarded by anglers. Options to consider, if Lake Trout removal is deemed justified or necessary, include using sterile Lake Trout to control population abundance, rotenone treatment, and/or mechanical removal via gill netting. Maintaining the current management of the lake may also be a viable option (i.e. a do nothing approach). In preparation for conducting a comprehensive study on the Lake Trout community in Stanley Lake, we wanted to determine where Lake Trout could be effectively sampled with gill nets during the spring months. Results from gill netting efforts over the last several years show Lake Trout can be effectively sampled with gill nets in nearshore areas of the lake in early spring, especially along the east shoreline (Figure 28). However, sampling techniques need to be further refined to become effective at capturing the entire size range, especially juveniles. This information will help us form a study design to assess Lake Trout abundance, size/age structure, and population dynamics over the next few years.

Stone Reservoir

We caught one Westslope Cutthroat Trout and one suspected Brook Trout x Bull Trout hybrid in a combined three hours of gill netting in 2016 (CPUE = 0.67 fish/hr). Both fish were caught in the sinking gill net. The Westslope Cutthroat Trout fell from the net upon retrieval, but was estimated to be approximately 300 mm TL. The suspected Brook x Bull hybrid measured 300 mm TL and weighed 265 g. We classified the Brook x Bull hybrid as a hybrid based on slight vermiculation on the dorsum, and light brown (not black) markings on the dorsal fin.

Stone Reservoir is very shallow (mean depth = 1.0 m; max depth = 2.1 m) and likely would not support fish overwinter. However, Little Timber Creek must provide overwinter habitat for trout that can then utilize the reservoir in the spring, summer, and fall. There appears to be heavy human use in the area, with several camping sites and user trails. Stone Reservoir may be able to provide a quality recreational fishery in the area if fish densities were higher.

MANAGEMENT RECOMMENDATIONS

1. Have custom gill nets made for Stanley Lake, to target Lake Trout in the 200 mm to 450 mm size range. Continue sampling to document population trends.

2. Try stocking WCT fry/fingerlings in Stone Reservoir to boost population abundance.

Table 14. Catch compositions and catch-per-unit-effort (CPUE, fish/hr) for Buster Lake on three sampling occasions, 1993, 2002, and 2016. EBT = Eastern Brook Trout, RBT = Rainbow Trout.

# caught CPUE (fish/hr)

Year # nets Net hours EBT RBT Total EBT RBT Total

1993 2 6.0 4 0 4 0.67 0.00 0.67

2002 4 66.3 79 12 91 1.19 0.18 1.37

2016 2 27.5 60 0 60 2.18 0.00 2.18

Table 15. Summary statistics for kokanee salmon and Lake Trout captured during gill netting surveys at Stanley Lake, 2007 to 2016, including relative abundance (CPUE, fish/hr), total length, and relative weight (Wr).

Kokanee Salmon Lake Trout Mean Mean Gill TL SE Max TL SE Max Mean Year net hrs n CPUE (mm) TL TL n CPUE (mm) TL TL Wr SE Wr

2007 164.5 20 0.12 234.2 5.8 276 44 0.27 651.2 21.3 930 97.5 4.7

2010 111.5 46 0.41 214.7 2.5 271 18 0.16 689.0 42.2 915 94.1 3.6 a 2011 428.2 40 -- 214.6 2.8 252 37 0.09 679.5 35.5 1017 95.8 2.6 a 2012 4069.5 343 -- 204.7 1.4 336 203 0.05 551.1 14.5 1005 93.7 2.6

2015 107.6 46 0.43 234.7 3.0 270 5 0.05 657.0 114.4 902 95.0 3.9 a 2016 472.4 15 -- 212.1 7.4 234 38 0.08 606.4 29.2 1083 87.7 1.7 a gill netting during these years was aimed at capturing only Lake Trout, so we will not report kokanee salmon CPUE.

0.20 1993 (n = 4) 0.16 0.12 0.08 0.04 0.00

160 2002

0.20 2016 2002 (n = 79) 0.16 120 0.12 0.08 80 0.04 Relative weight

Relative frequency 40 0.00

0.20 2016 (n = 60) TL (mm) 0.16 0.12 0.08 0.04 0.00

TL (mm)

Figure 24. Relative frequency and relative weight of Brook Trout caught during gill netting surveys at Buster Lake, 1993, 2002, and 2016. No weights were taken in 1993, so relative weights could not be calculated.

Temperature (°C) 3 5 7 9 0 2 4 6

8 10

Depth (m) 12 14 16 18 20

Figure 25. Temperature (°C) profile measured at mid-lake in Stanley Lake on May 21, 2016.

0.10 2007 (n=44) 0.08

0.06

0.04

0.02

0.00 0.10 2010 (n=18) 0.08 0.06 0.04 0.02 0.00

0.10 2011 (n=39) 0.08

0.06

0.04

0.02 Relative frequency 0.00

0.10 2012 (n=203) 0.08 0.06 0.04 0.02 0.00

0.10 2016 (n=39) 0.08

0.06

0.04

0.02

0.00

TL (mm)

Figure 26. Length-frequency histogram (total length TL) of Lake Trout sampled in Stanley Lake, by year using. .

2012 160 2016

120

80 Relative weight

TL (mm)

Figure 27. Relative weight by total length (TL) of Lake Trout caught in Stanley Lake during gill netting in 2012 and 2016.

2012 (n = 172)

2016 (n = 38)

Figure 28. Approximate locations of Lake Trout (each point is n = 1) caught during sampling at Stanley Lake in 2012 and 2016.

JIMMY SMITH LAKE RAINBOW TROUT FISHERY

ABSTRACT

Jimmy Smith Lake is a popular lowland lake fishery in the Salmon Region. It is open to angling year-round and supports a self-sustaining population of Rainbow Trout Oncorhynchus mykiss that originated from stocking events in the early 1930s. According to historic creel records, angler catch rates have always been relatively high at Jimmy Smith Lake (>3.0 fish/hr), but fish size has typically been very low. The quality of Rainbow Trout at Jimmy Smith Lake has improved substantially over the past few years, at least partially due to access improvements and increased bag limits, encouraging increased harvest. Increases in mean and maximum total length have been correlated with decreases in population abundance, resulting in reduced competition and increased forage quality and abundance. From 2012 to 2015, gill net catch rates suggested fish abundance decreased by as much as half (~8.0 fish/hr in 2010/2011 to ~4.0 fish/hr in 2014/2015), abundance of large-bodied zooplankton more than quadrupled, and the proportion of quality length Rainbow Trout (PSD-Q)increased from 0% in 2012 to 22% in 2015. In 2016, we observed the lowest gill net catch rates ever recorded at Jimmy Smith Lake, on two sampling occasions (August CPUE = 0.30 fish/hr, November CPUE = 1.30 fish/hr).Abundance of large-bodied zooplankton was also very low, and Rainbow Trout PSD-Q decreased to 4% in November. Jimmy Smith Lake is known to experience occasional fish kills in late summer, and we believe this may have occurred in 2016. Even though zooplankton quality was low in 2016, reduced competition for forage into 2017 should further improve the quality of fish in Jimmy Smith Lake.

Author:

Jordan Messner, Regional Fisheries Biologist

HISTORY AND INTRODUCTION

Jimmy Smith Lake was the first Idaho Department of Fish and Game owned access property in the state, purchased with license funds for $240.00 in 1929. Rainbow Trout Oncorhynchus mykiss from Williams Lake and Mackay Hatchery were stocked in the late 1920s to 1930’s to provide a resource for miners in the Clayton area. Today, the lake continues to support a naturally reproducing Rainbow Trout population that originated from those stocking events (Flinders et al. 2013). Rainbow Trout in the lake exhibit density dependent growth, and overall fish size has been improved in years when population abundance has been reduced (Brimmer et al. 2003, Flinders et al. 2013). Historically, mean total length rarely ever exceeded 200 to 250 mm in Jimmy Smith Lake, but a large fish kill in August, 2000 reduced fish abundance enough to cause a substantial increase in mean length from 2001 to 2003 (from 203 mm to 278 mm TL). As trout abundance increased again following the fish kill, TL decreased, and the density dependent growth relationship became clearer. In order to reduce trout abundance and improve size quality once again, we made major access improvements at the lake in 2011, and increased the daily bag limit from 6 trout per day to 25 (Flinders et al. 2013). From 2011 to 2015, relative trout abundance decreased from 7.49 fish/hr to 4.32 fish/hr, and mean total length increased from 183 mm to 289 mm (Messner et al. 2017). Proportion of quality length (>300 mm TL) to stock length (>200 mm TL) (PSD-Q) had increased from 0% in 2012, to 12% in 2014, and up to 22% by 2015.

OBJECTIVES

1. Monitor relative abundance and size structure of the Rainbow Trout population.

2. Continue monitoring forage quality and abundance to better understand how they affect fish growth.

STUDY SITE

Jimmy Smith Lake (WGS84 datum: 44.16907oN, -114.40249oW) is a landslide lake, located in north central Custer County, near Clayton, Idaho, at 1,948 meters elevation with a surface area of 26 hectares. The lake has one outlet and three inlet streams. The outlet stream, Big Lake Creek, is located at the southeast end of the lake and drains to the East Fork Salmon River. Two small inlet streams, Corral Creek and Jimmy Smith Creek, are located at the north end and east end of the lake, respectively, and the major inlet and primary spawning tributary, Big Lake Creek, enters from the northwest end of the lake.

Jimmy Smith Lake supports a self-sustaining Rainbow Trout fishery that originated from stocking events in the 1930s. Natural reproduction is so successful in the lake that it has been identified as a potential cause for low size attainment due to competition for forage, resulting in stunting (Brimmer et al. 2003). In May 1930, IDFG and USFS staff attempted to increase forage abundance by stocking 710,000 Eastern Smelt eggs in the lake. The attempt was unsuccessful, and no other fish species have ever been documented in the lake besides Rainbow Trout. The lake is highly productive, and is dominated by an abundance of aquatic macrophytes, large zooplankton, and amphipod scuds. Ice fishing is popular during winter months, with an estimated 796 hours of fishing from December 4, 2014 to March 20, 2015 (Messner et al. 2017). However, the lake can also offer excellent catch rates during ice-free months; typically from around mid-March to late-July. In late summer, water temperatures typically increase to 18°C or more, which can result in thick algae blooms, low dissolved oxygen concentrations, and occasional fish kills (Brimmer et al. 2003).

METHODS

While surveying the lake in August 2016, we conducted a depth profile with handheld depth sonar and handheld GPS unit to collect data points that would be used to construct a bathymetric map of the lake bed. GPS referenced depth points were uploaded to ArcMap 10.1 and used to create a triangulated irregular network (TIN) to create a series of polygons showing the contours of the lake bottom (Appendix E).

In August 2016, we set six gill nets (three sinking and three floating) for a combined total of 90.1 hours, overnight, to estimate relative Rainbow Trout abundance (CPUE) and collect size structure information. An additional four gill nets (two sinking and two floating) were set in November 2016, due to the extremely low catch rates observed in August. Fish captured in gill nets were enumerated, measured (mm TL) and weighed (g), and relative weights (Wr) were calculated by computing the standard weight (Ws) using the equation:

( ) = + (total length (mm))

where a = the intercept value퐿퐿퐿10 and푊푠 b =푎 slope푏 ∗ derived퐿퐿퐿10 from Blackwell et al. (2000) (Appendix A). The log value is then converted back to base 10, and relative weight is then calculated using the equation:

weight (g) = 100

푊푟 � � ∗ Fish captured in the gill nets were sacrificed푊푠 for stomach content analysis. Stomachs were opened and the entire contents were examined and identified. The components of each stomach were estimated and recorded as percent total stomach content biomass for each fish (ex. 75% amphipod scuds, 20% terrestrial invertebrates, 5% zooplankton). In the results section, we report only the primary component of the stomach contents for each fish.

We built length-frequency histograms for each sampling event at Jimmy Smith Lake to describe trends in overall size structure, and we calculated proportional stock density to describe the relative proportion of “quality” size Rainbow Trout present each year (PSD-Q), using criteria suggested in Willis et al. (1993) (200 mm for stock size and 330 mm for quality length).

Zooplankton sampling was conducted at Jimmy Smith Lake on August 19, 2016. Samples were collected near the inlet, mid-lake, and at the outlet following a modified version of methods outlined by Teuscher (1999). We sampled the outlet and mid-lake locations at 5.0 m depth, and the inlet location at 3.0 m, as maximum depth in the lake is not more than 6.0 m. Total zooplankton biomass (grams/liter) at each site is quantified by weighing the dried contents of the 153 µm net and dividing by tow depth. The zooplankton ratio index (ZPR) is the ratio of preferred to useable zooplankton, and is calculated by dividing the dried weight of the 750 µm sample (preferred) by the dried weight of the 500 µm sample (useable). The zooplankton quality index (ZQI) is the index of overall abundance and size ratios, and is calculated by dividing the sum of weights for the 500 µm and 750 µm samples by ZPR. Samples were stored in 100% ethyl alcohol for ten days, at which time ZPR/ZQI values were quantified (Teuscher 1999). Average total biomass, ZPR, and ZQI are calculated for each lake by averaging across the three sampling locations at each lake.

RESULTS AND DISCUSSION

During a combined 90.1 hours of gill netting on the evening of August 18, 2016, we captured 27 Rainbow Trout (CPUE 0.30 fish/hr) (Table 16). This is the lowest catch rate we have ever found over 13 sampling periods, since 1996 (Table 16). We caught 26 fish in floating nets and only one in sinking nets. Fish ranged in size from 146 mm to 362 mm TL, and averaged 250 mm TL (SE ± 13.4), and relative weights ranged from 64 to 88 (mean = 77) (Figure 29, Table 16). PSD-Q remained relatively high in August 2016 (32%), compared to 22% in 2015 (Table 16). Stomach contents of gill netted fish were primarily zooplankton in 48% (n = 13) of the fish captured, amphipod scuds in 41% (n = 11) of the fish captured, and terrestrial macroinvertebrates in 11% (n = 3).

On November 9, 2016, we resampled the lake to investigate whether the low catch rate observed in August was indicative of a dramatic reduction in fish abundance, or simply a function of sampling at a different time of year than normal. We typically sample in July rather than August, when water temperatures tend to be cooler. In 73.9 hours of gill netting in November, we captured 96 Rainbow Trout (CPUE 1.30 fish/hr) (Table 16) (six in floating nets and 90 in sinking nets). Fish size structure was very similar to what was observed in August (range: 150 mm - 353 mm TL; mean TL = 225 mm; SE ± 4.7), and although relative weights were higher (Figure 29), PSD-Q dropped to 4% (Table 16). Relative frequency of larger fish was much lower in November 2016 than was observed in August 2016 and June 2015 (Figure 29, Table 16). Analysis of fish stomachs found that the primary diet composition in subsampled fish in November (n = 27) was zooplankton for 40% (n = 11), terrestrial macroinvertebrates in 34% (n = 9), mussels/snails in 19% (n = 5), and amphipod scuds in 7% (n = 2).

Although total zooplankton biomass (contents of the 153µm net) increased in Jimmy Smith Lake in 2016 (9.59 g/m3), average ZQI and ZPR values are the lowest we have observed since 2011 (0.06 and 0.03, respectively) (Table 17). ZQI values lower than 0.60 indicate that competition for food is likely (Teuscher 1999).

Both August and November 2016 catch rates were the lowest we have observed in 20 years of sampling. Although our August catch rate may have been affected by unfavorable hypolimnetic conditions during the warm summer months, the relative proportion of fish caught in sinking to floating gill nets in November (94%) suggests hypolimnetic conditions were more favorable by that time. However, catch rates were still relatively very low. We suspect that at least a partial fish kill occurred at the lake in 2016, which has occurred in other years (Brimmer et al. 2003). The last reported fish kill in 2000 was considered very large, and approximately 1,000 dead fish were observed around the lake shore (Brimmer et al. 2003). In August 2016, we did observe mortalities around the lake, but not to that degree (n<100). During periods of poor lake conditions in late summer, fish may also seek cooler tributaries as refugia, which could also explain poor catch rates in August. However, it doesn’t seem likely that Rainbow Trout would have been utilizing tributaries in November when we revisited the lake. More likely, Rainbow Trout abundance was reduced in 2016 as a result of a late summer fish kill.

Abundance of large zooplankton was also very low in August, 2016. In fact, it was the lowest we have observed since fish abundance was very high in 2011. Typically with a large reduction in Rainbow Trout abundance, we would have expected to see an increase in abundance of large zooplankton (Messner et al. 2017), but perhaps the effect will be delayed a year. Most cladoceran and copepod zooplankton are very tolerant of low levels of dissolved oxygen (Pennak 1953), so anoxia (perhaps causing a fish kill) would likely not result in a large reduction in zooplankton.

Although quality zooplankton abundance was low in 2016, this may not necessarily result in poor fish growth into 2017. Analysis of fish stomach contents in 2016 suggests other food sources (i.e. terrestrial invertebrates, mussels/snails, and amphipod scuds) are also highly utilized by the Rainbow Trout population, and may be sufficient for maintaining quality growth during years of low zooplankton production. Overall, fish quality remained relatively high in 2016, with PSD-Q at 32% in August and 4% in November, and relative weights increased in November, compared to June 2015 and August 2016. Perhaps the observed decrease in PSD- Q was due to the relatively higher effects of poor lake conditions on larger fish, due to increased metabolic demands. If the correlation we have previously observed between fish abundance and fish size holds true, we may expect to see increased growth in 2017 as a result of low trout abundance in 2016.

MANAGEMENT RECOMMENDATIONS

1. Monitor relative abundance, size, and condition of Rainbow Trout in Jimmy Smith Lake in 2017 to determine how the suspected fish kill in 2016 has affected the trout population.

2. Work to develop a standardized monitoring program for Jimmy Smith Lake that involves surveying the lake every 3 to 5 years, with the objective being to document significant changes in Rainbow Trout population structure.

Table 16. Summary of gill netting surveys at Jimmy Smith Lake 1996 to 2016, including mark/recapture population estimate and size structure information. (TL = total length, Wr = relative weight)

Abundance Size structure

Relative Gill net # Fish Mean TL (mm) Maximum a Year abundance Population Est (95% CI) Mean Wr (± SE) PSD-Q hours caught (± SE) TL (mm) (CPUE)

1996 15.0 157 10.47 -- 213 (--) 332 -- 1%

2001 16.5 113 6.85 -- 203 (--) 370 -- 25%

2003 62.2 144 2.32 -- 278 (--) 368 -- 4%

2005 65.2 351 5.38 -- 251 (3.0) 427 -- 11%

2006 181.5 779 4.29 -- 222 (1.9) 419 106.8 (0.5) 6%

2008 90.3 914 10.13 -- 202 (1.1) 320 80.4 (0.3) 0%

2009 69.8 914 9.88 -- 203 (1.2) 325 77.8 (1.5) 0%

2010 71.7 591 8.24 -- 205 (1.2) 295 75.6 (1.1) 0%

2011 90.3 676 7.49 18,955 (10,540-36,970) 183 (0.9) 250 89.2 (0.4) 0%

2012 121.7 419 3.44 33,109 (15,796-75,589) 229 (1.8) 295 84.8 (0.6) 0%

2014 110.3 539 4.89 11,856 (8,030-18,324) 241 (2.4) 425 85.2 (0.3) 12%

2015 58.1 251 4.32 -- 289 (2.6) 368 79.4 (0.6) 22% 8/2016 90.1 27 0.30 -- 250 (13.4) 362 76.6 (1.1) 32% 11/2016 73.9 96 1.30 -- 226 (4.7) 353 83.3 (1.3) 4% a PSD-Q values were calculated using 300 mm TL as the “quality” length cutoff for previous reports. PSD-Q values reported here have been re-calculated using 330 mm TL as the “quality” cutoff, as recommended in Willis et al. (1993).

Table 17. Summary of zooplankton sampling at Jimmy Smith Lake 2002 to 2016. (ZPR = zooplankton ratio, ZQI = zooplankton quality index) 8/19 8/1 8/9 8/24 8/24 8/29 8/31 8/26 8/17 8/15 8/20 8/19 8/19 Sampling date 2002 2003 2004 2006 2007 2008 2009 2011 2012 2013 2014 2015 2016 Mean total biomass (g/L) 2.84 2.24 -- 0.95 3.15 1.41 2.53 1.43 6.24 5.08 6.07 5.88 9.59 Mean ZPR 0.00 0.11 0.03 0.23 0.16 0.25 0.05 0.07 0.24 0.30 0.57 0.26 0.03 Mean ZQI 0.00 0.17 0.03 0.15 0.02 0.02 0.01 0.05 2.02 1.97 4.59 1.05 0.06

0.2 June 2015 0.1

0.0 160 120 80 40

0.2 August 2016

0.1

0.0 160 120 80 40

November 2016 0.2 Relative frequency/ relative weight 0.1

0.0

160 120 80 40

TL (mm)

Figure 29. Length=frequency histogram of total length (TL), and relative weights, of Rainbow Trout collected in gill nets at Jimmy Smith Lake in 2015 and 2016.

CARLSON LAKE FISHERY EVALUATION

ABSTRACT

Idaho Department of Fish and Game staff set six gill nets (three sinking and three floating) overnight at Carlson Lake in June 2016 to monitor relative abundance and size structure of the Brook Trout Salvelinus fontinalis population. Since the third introduction of tiger muskellunge Esox masquinongy x Esox lucius in 2013, Brook Trout quality has improved substantially at Carlson Lake. Both mean and maximum observed total length in 2016 (272 mm and 351 mm, respectively) were greater than previously documented values and PSD-Q increased from 0% over the past 10 years, to 5% in 2016. Overall fish condition was also excellent, with relative weights ranging from 80 to 120 (mean Wr = 95). Six tiger muskellunge were captured during gill netting in 2016, ranging in size from 647 mm to 910 mm TL (mean 741.8 mm TL). One of the tiger muskellunge captured in 2016 was aged at 11 years (stocked in 2006) and all others were stocked in 2013. All exhibited excellent overall body condition (mean Wr = 110).

Author:

Jordan Messner, Regional Fisheries Biologist

INTRODUCTION

Carlson Lake contains a naturally reproducing Brook Trout Salvelinus fontinalis population originating from stocking events in the 1940’s and 1950’s. An interdepartmental memo written by Kent Ball in 1975 suggests Brook Trout weighed up to 1.4 kg during the early years of the fishery, just after they were initially stocked (Salmon Region IDFG records). Rainbow Trout Oncorhynchus mykiss were also stocked in the lake in 1975 and 1993, but those introductions failed. Since 1975, surveys have indicated poor size and body condition of Brook Trout in the lake, presumably as a result of overabundance and related stunting (Messner et al. 2015). In the mid 1990’s, fisheries staff attempted to reduce Brook Trout abundance via several different means (intensive gill netting, electrofishing, explosives, and increased bag limits) but all proved unsuccessful in obtaining long-term improvements to Brook Trout size structure (Brimmer et al. 2006). In 2002, 41 tiger muskellunge Esox masquinongy x Esox lucius were introduced as a biological means to reduce Brook Trout abundance and improve their size structure.

In 2002, when tiger muskellunge were first introduced, Brook Trout abundance was estimated (95% CI) at 9,024 (7,474-11,064), with a mean TL of 201 mm. In 2005, three years after tiger muskellunge introduction, Brook Trout abundance had decreased to 6,103 fish (95% C.I. 4,196-9,262), and mean TL increased to 231 mm. Tiger muskellunge were seemingly successful at reducing Brook Trout abundance and improving size structure for the first few years after introduction, and another 32 tiger muskellunge were stocked in the lake in 2006. However, mean length and condition of Brook Trout decreased from 2006 to 2009 (Curet et al. 2010), and continued to decrease into 2013, when the population was estimated at 10,867 (95% C.I. 9,182-13,008); the highest estimated abundance since monitoring began (Messner et al. 2015). To attempt a larger decrease in Brook Trout abundance and larger response in size structure, tiger muskellunge were stocked again in 2013, but at twice the number of the other two events (n = 70). Another population estimate conducted in 2015 found that abundance was reduced to an estimated 2,682 Brook Trout (95% C.I. 1,653-4,748), and mean TL had increased to 251 mm, the highest observed mean TL to date (Messner et al. 2017).

OBJECTIVES

1. Monitor Brook Trout abundance and size structure to determine if introduced tiger muskellunge have been effective at improving the quality of the Brook Trout fishery.

STUDY SITE AND METHODS

Carlson Lake (WGS84 datum: 44.28153oN, 113.75283oW) is a sub-alpine lake approximately 3.5 hectares in size located in the Pahsimeroi River drainage at 2,438 m elevation. Subterranean flow from the lake drains into Double Springs Creek, a tributary of the Pahsimeroi River, but there is essentially no outlet and the inlet flow is seasonally intermittent. Carlson Lake has a highly vegetated littoral zone that extends for an average of approximately 12 meters from shore, and averages around 1 meter deep around the entire perimeter of the lake. There is a primitive campsite with picnic bench and pit toilet located on the southwest end, by the inlet. The lake can be accessed from two different routes. From the northeast route, full size vehicles can drive to within approximately 2 km of the lake before alternative transportation is recommended. From the southwest route, full size vehicles can access the top of the ridge above the lake, but are not permitted to descend the remaining 1 km of road. Motorized vehicle access to the lake and camping area is limited to ATVs, UTV’s, and motorbikes only.

The fish community was sampled using gill nets on June 9, 2016 to determine relative abundance and size structure of the Brook Trout population. Six gill nets (three floating and three sinking) (46 m x 2 m, with six panels consisting of 19, 25, 32, 38, 51, and 64 mm bar mesh) were deployed overnight and retrieved the following morning. Fish captured in gill nets were enumerated, measured (mm TL) and weighed (g), and relative weights (Wr) were calculated by computing the standard weight (Ws) using the equation:

( ) = + (total length (mm)) where a = the intercept value퐿퐿퐿10 and푊푠 b =푎 slope푏 ∗ derived퐿퐿퐿10 from Blackwell et al. (2000) (Appendix A). The log value is then converted back to base 10, and relative weight is then calculated using the equation:

weight (g) = 100

푊푟 � � ∗ We built length-frequency histograms푊 for푠 each sampling event at Carlson Lake to describe trends in overall size structure, and we calculated proportional stock density to describe the relative proportion of “quality” size Brook Trout present each year (PSD-Q), using criteria suggested in Willis et al. (1993) (200 mm for stock size and 330 mm for quality length).

In addition to collecting lengths and weights, tiger muskellunge caught in gill nets were examined for PIT tags (all tiger muskellunge stocked in 2013 were PIT tagged), and otoliths were extracted and stomach contents examined from any mortalities. Otoliths were cleaned of debris and mucus, and stored in dry vials. Otoliths were then mounted in epoxy and cross- sectioned using an isometric saw (Beamish 1979, Casselman 1983). Sections were mounted on microscope slides and digitized under 40x magnification. Digital images were read by two independent technicians and if independent readers were not in agreement on an age, a third reader was used to assign an age to the otolith.

RESULTS

During a combined 82.7 hours of gill netting Carlson Lake on the evening of June 9, 2016, we captured 67 Brook Trout (CPUE 0.81 fish/hr) and six tiger muskellunge (CPUE 0.07 fish/hr) (Table 18). Brook Trout ranged in size from 169 mm to 351 mm TL, and averaged 272 mm TL (SE ± 5.8) (Figure 30, Table 18). Brook Trout body condition (Wr) in 2016 was excellent, averaging 95 (Wr range 80 to 120) (Figure 30, Table 18). PSD-Q for Brook Trout was 5% in 2016 compared to 0% over the past 10 years.

Five of the six tiger muskellunge captured in 2016 had been PIT-tagged when they were stocked in 2013, and ranged in size from 647 mm to 770 mm TL (mean 708 mm TL ± 23.9 SE) (Table 19). One tiger muskellunge (910 mm TL) did not have a PIT tag, and otolith analysis revealed it was 11 years old (stocked in 2006). All tiger muskellunge captured in 2016 exhibited excellent body condition (mean Wr = 110; range = 100 - 122) (Table 19). Two mortalities were examined for stomach contents, and both stomachs contained ~300 mm Brook Trout.

DISCUSSION

Brook Trout size improved substantially at Carlson Lake in 2016, with PSD-Q reaching 5%, and larger mean and maximum TL values than have been observed in several decades (Figure 31). It appears that the much lower Brook Trout abundance observed in 2015 (Messner et al. 2017) continued into 2016. This reduction has led to improved Brook Trout size structure over the past three years (Figures 30 and 31), likely as a result of improved growth rates since tiger muskellunge stocking density was increased (Messner et al. 2017).

Although tiger muskellunge were first stocked in Carlson Lake in 2002 and 2006, the effect of predation on Brook Trout was not markedly pronounced until after 2013, when tiger muskellunge stocking density was doubled. Koenig et al. (2015) found that high mountain lake Brook Trout populations could be significantly reduced or even completely eliminated, in some cases, by stocking tiger muskellunge at a density of 40 fish/ha. The first two stocking events in Carlson Lake were at half the recommended density (20 fish/ha and 16 fish/ha, respectively), but stocking density was nearly doubled in 2013 (35 fish/ha). With a relative reduction in younger age classes of Brook Trout and increased growth rates for those younger age classes as a result, we have observed an overall increase in both mean and maximum size of Brook Trout in Carlson Lake. Without continued predation pressure, Brook Trout densities and poor size structure are likely to return to historic levels. Intermittent sampling over the next several years should indicate if and when additional tiger muskellunge stocking is needed to achieve PSD-Q > 25%, providing a high quality mixed species (Brook Trout and tiger muskellunge) fishery.

MANAGEMENT RECOMMENDATIONS

1. Continue to monitor relative abundance, size, and condition of Brook Trout in Carlson Lake in 2017.

2. Consider stocking additional tiger muskellunge in 2018 or 2019 to continue suppressing Brook Trout abundance and maintain PSD-Q > 5%.

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Table 18. Summary of relative abundance (catch per unit effort, CPUE) and size structure values from survey results at Carlson Lake, 1997 to 2016.

Abundance Size structure

Relative Gill net # fish Mean TL (mm) Maximum TL Mean Wr Year abundance Estimated abundance (mark/recapture) hours caught (± SE) (mm) (± SE) (CPUE)

1997 466.4 999 2.14 -- 192.0 (--) 245.0 --

1998 483.3 818 1.69 -- 196.0 (--) 295.0 --

1999 386.1 1,151 2.98 -- 198.0 (--) 305.0 --

2000 270.9 665 2.45 -- 191.2 (1.4) 270.0 --

2002 147.8 546 3.69 9,024 (95% CI = 7,474-11,064) 200.6 (1.4) 276.1 84.2 (3.1)

2003 416.9 562 1.35 9,063 (95% CI = 6,987-12,039) 209.3 (1.4) 270.0 64.9 (3.3) a 2004 40.5 47 1.16 -- 225.4 (2.4) 255.0 83.2 (2.1)

2005 369.5 607 1.62 6,103 (95% CI = 4,196-9,262) 230.7 (2.2) 290.0 89.2 (0.9)

2006 64.8 154 2.32 -- 215.7 (4.0) 301.0 104.1 (1.3) b 2008 20.5 67 3.27 -- 224.5 (3.6) 270.0 88.1 (1.5)

2009 151.7 251 1.62 -- 233.8 (1.9) 312.0 87.2 (1.0)

2011 132.7 287 2.16 -- 218.4 (2.0) 291.0 89.1 (5.1) 2013 172.5 825 4.78 10,867 (95% CI = 9,182-13,008) 220.3 (1.1) 292.0 74.8 (0.3) 2014b 3.5 35 10.00 -- 226.0 (0.9) 287.0 79.7 (0.4) 2015 75.0 108 1.44 2,682 (95% CI = 1,653-4,748) 251.7 (2.4) 289.0 86.0 (0.8) 2016 82.7 67 0.81 -- 272.2 (5.8) 351.0 95.4 (1.1) a hoop net/angling survey b angling surveys

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Table 19. Total lengths (mm), weights (kg), and relative weights (Wr) of tiger muskellunge captured during gill netting at Carlson Lake in 2016.

TL (mm) Wt (kg) Wr Age

910 5.62 100.3 11 675 2.52 121.9 4 Tiger muskellunge 647 1.87 104.2 4 (n = 6) 770 3.90 121.6 4 725 2.62 99.9 4 724 2.92 111.9 4 Mean 741.8 3.24 110.0 --

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0.3 2013 0.2 0.1 0.0 160 120 80 40

0.3 2015 0.2

0.1

0.0 160 120 80 40 Relative frequency/ relative weight

0.3 2016 0.2

0.1

0.0 160 120 80 40

TL (mm)

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5.0 290 relative abundance 4.5 280 mean TL 4.0 270

3.5 260 3.0 250 2.5 240 2.0 230 CPUE (fish/hr) 1.5 220 mean TL (mm) 1.0 * 210 0.5 200 0.0 190

Year

Figure 31. Relative abundance and mean size of Brook Trout sampled at Carlson Lake, 1998 to 2016. All CPUE values were derived from gill netting surveys, with the exception of 2004* (hoop nets and angling). Error bars on mean TL estimates are standard error.

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HERD LAKE FISHERY EVALUATION

ABSTRACT

We set four gill nets (two sinking and two floating) overnight at Herd Lake in mid-June 2016 to assess relative abundance and size structure of the Rainbow Trout Oncorhynchus mykiss population. We are monitoring the Rainbow Trout population in Herd Lake to determine whether fish size has improved as a result several management strategies (increased bag limit, predator introductions) implemented over the last decade to decrease fish abundance. We found that relative abundance of Rainbow Trout (1.80 fish/hr) was much lower in 2016 than was observed during the last two sampling events (2010 and 2011), but size structure had not improved. Mean total length and relative weight in 2016 was 207 mm and 76, respectively. We did not capture any Rainbow Trout considered “quality length” (larger than 300 mm TL) in 2016.

Zooplankton surveys were also conducted at Herd Lake in 2016 to determine how changes in fish abundance affect the quality and availability of forage in the lake. Zooplankton quality and abundance increased slightly after tiger muskellunge were first introduced in 2006, and again when daily bag limits were increased in 2011. However, results of our 2016 surveys suggest forage quality and abundance is currently as low as we have ever seen in the lake (ZQI = 0.02, ZPR = 0.04). Even though relative fish abundance has decreased over the last several years, it appears that forage is currently inadequate for promoting high growth potential.

Author:

Jordan Messner, Regional Fisheries Biologist

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INTRODUCTION

Herd Lake is one of 23 lowland lakes in the Salmon Region that are easily accessible to anglers by road. Fisheries management objectives for lowland lakes in the Salmon Region focus on providing diverse angling opportunities (i.e. species diversity) with catch rates above 1 fish/hr and diverse size structure of fish available to anglers. Herd Lake supports a self- sustaining population of Rainbow Trout Oncorhynchus mykiss that spawn in Lake Creek, the sole inlet to the lake. While catch rates for Rainbow Trout at the lake can be very high (2008 and 2013 angling survey catch rates were 10.0 fish/hr and 3.8 fish/hr, respectively), fish size leaves much to be desired. Gill netting efforts between 2001 and 2011 showed that average Rainbow Trout length in Herd Lake rarely exceeded 250 mm TL (Curet et al. 2013), which is considered a result of an overabundance of fish resulting in competition for forage (Brimmer et al. 2003). In the mid-1990s, a fish migration barrier was installed on the spawning inlet to Herd Lake (Lake Creek) to reduce the number of fish contributing to spawning, but later evaluation showed fish could ascend the inlet above the barrier, so the effort was negated. In a similar attempt to reduce Rainbow Trout abundance, improve size structure, and increase species diversity, 72 tiger muskellunge Esox masquinongy x Esox lucius were stocked in 2006 and the bag limit on Rainbow Trout was increased from six to 25 trout per day in 2011. In 2013, an additional 75 tiger muskellunge were stocked (Messner et al. 2015). We have been monitoring zooplankton quality and abundance since 2002 in Herd Lake to determine whether the aforementioned management actions have improved forage conditions, and we have also been regularly monitoring Rainbow Trout size structure to determine how forage conditions affect subsequent fish growth.

OBJECTIVES

1. Monitor Rainbow Trout abundance and size structure to determine whether tiger muskellunge introduction has been effective at improving the quality of the fishery.

STUDY SITE AND METHODS

Herd Lake (WGS84 datum: 44.08921°N, 114.17364°W) is located in the East Fork Salmon River drainage in Custer County at 2,187 m elevation and was formed by a prehistoric landslide which blocked Lake Creek. The lake has a surface area of 6.7 ha and maximum depth of 14 meters.

We set two pairs of standard lowland lake gill nets (one sinking and one floating, per pair) (46 m x 2 m, with six panels consisting of 19, 25, 32, 38, 51, and 64 mm bar mesh) overnight in Herd Lake on the evening of June 22, 2016 to determine relative abundance, size structure, and condition (relative weight – Wr) of the Rainbow Trout population, and to determine whether tiger muskellunge remained in the lake from previous stocking events in 2006 and 2013. Fish caught in the gill nets were identified to species, enumerated, measured (mm TL), and weighed (g). Relative abundance (catch-per-unit-effort, CPUE) was calculated as the total number of fish caught, divided by the total number of gill net hours. Relative weight (Wr) was calculated by first calculating standard weight (Ws) using the equation:

( ) = + (total length (mm))

퐿퐿퐿10 푊푠 푎 푏 ∗ 퐿퐿퐿10

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where a = the intercept value and b = slope derived from Blackwell et al. (2000) (Appendix A). The log value is then converted back to base 10, and relative weight is then calculated using the equation:

weight (g) = 100

푊푟 � � ∗ Zooplankton samples were collected at푊푠 Herd Lake on August 18, 2016. Tows were conducted near the inlet, mid-lake, and at the outlet following methods outlined by Teuscher (1999). Tows were conducted from a depth of 7.0 m near the inlet, and 9.1 m at mid lake and near the outlet. Samples were stored in 100% ethyl alcohol for eleven days, at which time they were analyzed using methodology presented in Teuscher (1999). Total zooplankton biomass (grams/liter) at each site is quantified by weighing the dried contents of the 153 µm net and dividing by tow depth. The zooplankton ratio index (ZPR) is the ratio of preferred to useable zooplankton, and is calculated by dividing the dried weight of the 750 µm sample (preferred) by the dried weight of the 500 µm sample (useable). The zooplankton quality index (ZQI) is the index of overall abundance and size ratios, and is calculated by dividing the sum of weights for the 500 µm and 750 µm samples by ZPR. Average total biomass, ZPR, and ZQI are calculated for each lake by averaging across the three sampling locations at each lake.

RESULTS

Gill nets were fished for a combined total of 55.3 hours overnight on the evening of June 22, 2016 and caught 97 Rainbow Trout (Table 20) and four tiger muskellunge. Rainbow Trout catch-per-unit-effort (CPUE) was 1.75 fish/hour, and tiger muskellunge CPUE was 0.07 fish/hr. Rainbow Trout caught during gill netting in 2016 ranged in size from 159 mm TL to 290 mm TL, and averaged 207.6 mm TL (SE ± 1.9) (Figure 32, Table 20). Relative weight values showed poor condition of Rainbow Trout in the lake in 2016, with a maximum observed value of 98, but an average of 76 (Figure 33). We did not catch any Rainbow Trout in Herd Lake in 2016 that would qualify as “quality length” (greater than 300 mm TL). Sixty-one of the 97 Rainbow Trout we caught, and all four tiger muskellunge, were captured in floating gill nets. The four tiger muskellunge caught during gill netting in 2016 ranged in size from 670 mm TL to 755 mm TL, and averaged 711.3 mm TL (SE ± 20.1) (Table 21). Tiger muskellunge captured from the lake in 2016 were in excellent condition, with relative weight values averaging 96.8 (SE ± 2.3) (Table 21).

Zooplankton sampling was conducted at three locations (near inlet, mid lake, near outlet) on August 18, 2016. Average total zooplankton biomass, as measured in the 153µm net, was very similar to values obtained from previous years of sampling (2.1 grams/meter in 2016) (Table 22). ZPR and ZQI values in 2016 were the lowest we have observed in the lake over the past decade. ZPR and ZQI values below 0.60 suggest competition for food is likely (Teuscher 1999). The index values calculated for 2016 suggest forage quality is currently very poor in Herd Lake.

DISCUSSION

Rainbow Trout size has not improved in Herd Lake, despite several attempts to do so over the past decade. We have not observed any strong density dependent growth relationship over the past 20 years of monitoring the fishery, suggesting fish density is not what is limiting

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growth. Although catch rates are currently meeting regional objectives (angling catch rates greater than 1.0 fish/hr), we would still like to increase fish size to achieve a PSD-Q (330 mm TL) of 25% or greater. However, if reductions in fish abundance do not result in improved growth rates, the lake may be nutrient/forage limited. We recommend continuing to suppress abundance while examining other factors that may help improve fish growth in the lake.

MANAGEMENT RECOMMENDATIONS

1. Develop a management plan to improve the quality of the fishery at Herd Lake.

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Table 20. Summary of Herd Lake surveys 1967 to 2016, showing Rainbow Trout relative abundance and size structure information. (TL = total length, Wr = relative weight)

Total Relative # effort # RBT abundance Size range Mean TL (mm) Mean Wr Year Nets (hours) caught (CPUE) (mm TL) (± SE) (± SE) 1967 unk unk 77 -- 178-279 220.0 (± 3.1) -- 1994 2 15.0 113 7.5 130-260 199.4 (± 2.5) -- 1996 1 16.3 15 0.9 160-292 258.1 (± 10.8) -- 2001 2 32.6 30 0.9 95-280 178.5 (± 13.1) 106.6 (± 2.9) 2002 4 51.2 81 1.6 97-350 200.0 (± 5.6) -- 2003 2 49.3 93 1.9 107-309 212.2 (± 5.7) 90.7 (± 0.7) 2005 4 65.23 272 4.2 163-292 207.2 (± 1.7) 80.5 (± 0.9) 2006 4 165.8 682 4.1 141-268 191.8 (± 1.2) 87.4 (± 0.8) 2008a 1b 10.0 100 10.0 135-312 226.7 (± 5.0) 80.0 (± 1.0) 2009 4 98.3 129 1.3 157-306 229.8 (± 3.4) 76.7 (± 2.0) 2010 4 79.5 420 5.3 113-315 223.8 (± 1.9) 77.1 (± 2.1) 2011 4 64.6 282 4.4 118-292 184.4 (± 1.5) 94.5 (± 1.7) 2013a 4b 44.0 169 3.8 75-285 192.7 (± 4.4) 96.8 (± 4.6) 2016 4 55.3 97 1.8 159-290 207.6 (± 3.2) 76.0 (± 0.6) a 2008 and 2013 surveys were angling surveys, not gill netting surveys. b # of anglers (not gill nets) for angling surveys in 2008 and 2013.

Table 21. Total lengths (mm), weights (kg), and relative weights (Wr) of tiger muskellunge captured during gill netting at Herd Lake in 2016.

TL (mm) Wt (kg) Wr

755 3.11 103.5 Tiger muskellunge 670 1.89 93.7 (n = 4) 685 2.04 94.0 735 2.64 96.1 Mean 711.3 2.42 96.8

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Table 22. Zooplankton total biomass, ZPR, and ZQI average values obtained from mid-summer sampling, 2002-2016.

8/27 7/31 8/9 8/24 8/24 8/29 8/31 8/26 8/17 8/15 8/20 8/19 8/18 Sample date 2002 2003 2004 2006 2007 2008 2009 2011 2012 2013 2014 2015 2016 Mean total biomass (g/l) 1.34 1.34 -- 0.95 3.21 0.86 1.36 1.02 4.23 1.94 2.82 2.38 2.10 Mean zooplankton ratio (ZPR) 0.05 0.05 0.02 0.14 0.50 1.02 0.36 0.16 0.44 0.94 0.49 0.26 0.04 Mean zooplankton quality Index (ZQI) 0.01 0.01 0.04 0.02 1.28 0.98 0.22 0.05 1.63 2.42 0.87 0.31 0.02

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0.40 1967 1994 0.30

0.20

0.10

0.00

0.40 1996 2001 0.30

0.20

0.10

0.00

0.40 2002 2003 0.30 0.20

0.10

0.00

frequency 0.40 2005 2006 0.30

0.20 Relative 0.10

0.00

0.40 2009 2010 0.30 0.20 0.10

0.00

0.40 2011 2016 0.30 0.20 0.10 0.00

TL (mm)

Figure 32. Length-frequency histogram (TL) of Rainbow Trout captured at Herd Lake during gill netting surveys from 1967 to 2016. Tiger muskellunge were stocked in 2006 and 2013, and bag limits were increased from 6 fish per day to 25 fish per day in 2011.

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Relative weight Relative

TL (mm)

Figure 33. Relative weights for all Rainbow Trout captured in gill nets at Herd Lake in 2016 (n = 97).

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RIVERS AND STREAMS:

SALMON RIVER ELECTROFISHING SURVEYS

ABSTRACT

Raft mounted electrofishing equipment was used to determine fish composition, abundance, distribution, and size structure in six sections of the mainstem Salmon River in fall, 2016. Non-target species (mainly Mountain Whitefish, various Sucker spp., and Northern Pikeminnow) outnumbered target species in all transects we surveyed in 2016. However, non- target species were not netted in most transects. Overall target species composition (n = 1,826) was 49.1% O. mykiss parr (n = 896, 93% natural origin and 7% hatchery origin), 26.2% Chinook Salmon parr (n = 478, 99% natural origin and <1% hatchery origin), 16.0% Westslope Cutthroat Trout (n = 293), 4.5% adult Rainbow Trout (> 300 mm TL)(n = 82), 2.3% Bull Trout (n = 42), 1.6% trout hybrids (Cutthroat x Rainbow n = 28, Brook x Bull n = 1), and <0.1 % Smallmouth Bass (n = 6). Target species catch rates showed that, in general, Chinook Salmon parr, steelhead parr, and adult Rainbow Trout were relatively more abundant in the middle transects (Deer Gulch to Colston, Rattlesnake to Elevenmile, and Kilpatrick to Elk Bend), while Westslope Cutthroat Trout and Bull Trout were relatively more abundant in the upper transects (Pennal Gulch to Watt’s Bridge, and East Fork to Deadman’s Hole). Mark/recapture point estimates for both O. mykiss parr and Westslope Cutthroat Trout corroborated with catch rate findings. To quantify abundance of non-target species for reference, we conducted a two-pass mark/recapture estimate for a 3.2 km section of the Deadwater to Indianola transect in September, 2016. Overall CPUE for non-target fish in the transect sub-section was 241.9 fish/hr over both passes, and overall non-target fish abundance (± 95% CI) was estimated at 7,506 fish (4,402 – 13,808) in the 3.2 km sub-section, or 2,346 non-target fish/km. Non-target species composition was, in descending order, Largescale Sucker (31.5%, n = 192), Mountain Whitefish (29.1%, n = 177), Northern Pikeminnow (13.3%, n = 81), Bridgelip Sucker (11.5%, n = 70), Mountain Sucker (10.5%, n = 64), Chiselmouth Chub (3.6%, n = 22), and Redside Shiner (<1%, n = 3). The information gathered from these surveys in 2015 and 2016 will serve as baseline information for further studies on the upper mainstem Salmon River.

Author:

Jordan Messner, Regional Fisheries Biologist

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INTRODUCTION

The upper Salmon River already serves as a popular fishery for targeting anadromous Chinook Salmon Oncorhychus tshawytscha and steelhead O. mykiss, but is under-utilized as a trout fishery. IDFG’s current fisheries management plan lists “Improv[ing] the quality of resident trout fishing in the mainstem Salmon River during the summer months” as an objective (IDFG 2014). Our ability to improve trout fishing on the upper Salmon River is hindered by the fact that we currently know little about composition, abundance, distribution, and size structure of trout in the river.

The Salmon River supports a wide range of fish species, including anadromous salmon and steelhead, and several resident species including Rainbow Trout O. mykiss, Cutthroat Trout O. clarkii, Bull Trout Salvelinus confluentus, Brook Trout S. fontinalis, Mountain Whitefish Prosopium williamsoni, Northern Pikeminnow Ptycheilus oregonensis, various sucker species Catastomus spp., dace Rhinichthys spp., sculpin Cottus spp., Chiselmouth Chub Acrocheilus alutaceus, and Redside Shiners Richardsonius balteatus. Electrofishing surveys conducted on the upper mainstem Salmon River in 1998 found that suckers (var. spp.) and Mountain Whitefish (combined) made up 67% to 89% of the catch, while trout made up only 1% to 4% (Curet et al. 2000a).

Trout fishing in the upper Salmon River can be good during certain times of the year. Spatial distribution of resident trout throughout the upper mainstem Salmon River varies seasonally, and is likely related to seasonal habits and requirements for each species (i.e. spawning, foraging, and overwintering) (Schoby 2006). Rainbow Trout and Westslope Cutthroat Trout mainly spawn in smaller tributaries in the spring, but occupy various parts of the mainstem river at other times of the year. Bull Trout use the mainstem river for overwintering and foraging during fall, winter, and spring, but aggregate in the upper reaches of smaller tributaries for spawning from mid-summer to early fall (Schoby 2006).

With little information regarding the abundance and size structure of resident trout in the upper mainstem Salmon River, it is difficult to make informed management decisions to improve the quality of resident trout fishing. Baseline information that includes fish densities, species composition, and size structure information will help us identify reaches within the Salmon River that currently offer quality resident trout angling opportunities, and those in need of improvement. Establishing trend reaches and annual sampling will allow us to monitor long-term trends of resident salmonid populations, and evaluate the effectiveness of future management decisions aimed at improving fishing in the basin.

OBJECTIVES

1. Establish trend monitoring sites on the upper mainstem Salmon River and collect baseline information relating to trout abundance, movement, and size structure.

2. Locate overwintering Chinook Salmon and steelhead parr, deploy PIT tags in ~150-200 of each species in each transect, and evaluate outmigrant survival through the hydrosystem in 2017.

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STUDY SITES AND METHODS

We electrofished seven transects on the main stem Salmon River in the fall, 2016; five were newly established transects and two had been previously established in 2015 (East Fork to Deadman’s Hole and Pennal Gulch to Watt’s Bridge). Transect descriptions for the two earlier transects can be found in the 2015 Salmon Region Annual Report (Messner et al. 2017). The newly established transects were (in descending/downstream order) Deer Gulch (44.7034°N, - 114.0427°W) to Colston Corner (44.7526°N, -113.9964°W) (8.7 km), Kilpatrick (44.8301°N, - 113.9872°W) to Elk Bend (44.9043°N, -113.9689°W) (10.8 km), Rattlesnake bridge (44.9370°N, -113.9639°W) to Elevenmile (45.0262°N, -113.9183°W) (14.4 km), Morgan Bar (45.2539°N, - 113.90724°W) to Red Rock (45.3481°N, -113.9201°W) (13.1 km), and Deadwater (45.3869°N, - 114.0525°W) to Indianola (45.3983°N, -114.1694°W) (11.2 km).

All transects (with the exception of Rattlesnake to Elevenmile) were electrofished over three days, approximately one week apart, with the first and second passes serving as marking events, and the third pass used to recapture marked fish. The Rattlesnake to Elevenmile transect was only electrofished one day, because we felt trout densities were so low we would not recapture enough marked trout for a population estimate. Electrofishing surveys were conducted on the Deadwater to Indianola, Morgan Bar to Red Rock, and Deer Gulch to Colston transects in the first, second, and third weeks of September, and surveys were conducted on the other transects in the first, second, and third weeks of October (Rattlesnake to Elevenmile was surveyed the first week only).

Each of the transect reaches were sampled using two rafts operating in tandem, mounted with Midwest Electrofishing Systems Infinity control boxes powered by Honda 5000 W generators. Pulsed DC current was applied to the water using two booms with Wisconsin ring anodes on each boat. Control box settings were between 200-350 volts, at a frequency of 60 Hz and 25% duty cycle, and typically between 4 – 8 Amps and 1500 to 1800 watts. One fisheries technician on the front of each boat attempted to net all trout spp., Chinook Salmon parr, steelhead parr, and any rare species encountered (e.g. Smallmouth Bass). Non-target species (Mountain Whitefish, Northern Pikeminnow, various sucker species, and Redside Shiners) were not netted in most transects because they were so abundant it would have complicated our objective of collecting information on target species. However, in a 3.2 km sub-section of the Deadwater to Indianola transect, all non-target fish were also captured to estimate abundance and gather size structure information. Non-target fish were marked on one pass in the sub- section and examined for marks/recaptures on the next pass. Anadromous adults (Chinook Salmon and steelhead) were not netted during any of our surveys. If anadromous adults were encountered, shocking was temporarily halted, and resumed approximately 50 m downstream.

All netted fish were anaesthetized using Aqui-S 20E fish anaesthetic. All reporting requirements for using Aqui-S 20E as a trial anaesthetic were followed (i.e. careful tracking of amounts used, fish handling times, and fish recovery times). Fish were identified, scanned for PIT tags and other tags/marks, measured (mm TL), and weighed (g), and all target species (with the exception of Chinook Salmon parr) were given a fin clip on the first and second passes of each transect. All O. mykiss smaller than 300 mm TL (both steelhead and Rainbow Trout parr) were grouped together as O. mykiss parr, and those larger than 300 mm TL were examined further to subjectively determine whether they were resident Rainbow Trout or juvenile steelhead. Adipose-clipped O. mykiss that were slightly larger than 300 mm TL were considered hatchery steelhead based on morphological characteristics. All trout that did not already contain a PIT tag were given one, and we also attempted to PIT tag ~150 to 200

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Chinook Salmon and steelhead parr in each transect. All PIT tag information (marked or recaptured) was entered into ptagis.org.

Trout abundance was summarized in two ways; catch per unit effort and mark/recapture abundance. Mark/recapture abundance estimates were only calculated for Westslope Cutthroat Trout and steelhead parr, due to insufficient number of recaptures for all other species. We used the Peterson estimator (Chapman modification) to estimate trout abundance in each section using the formula:

( ) = + 1 ∑ 퐶푡푀푡 � 푁 푡 where Ct = number of fish captured during pass∑ t,푅 Mt = number of fish marked during pass t, and Rt = number of fish recaptured during pass t. Confidence intervals (95%) were calculated using confidence limits for a Poisson distribution because the total number of recaptures was <50 in each section (Krebs, 1989):

( )( ) 95% confidence limits on = 1 + 1 푀 퐶 푁� − where M = total number of fish marked, C = total number푥 of fish captured during recapture events, and x = value obtained from Table 23.

We built length-frequency histograms for each species of trout in each section to describe overall size structure, using all fish captured (including those <150 mm TL), and we calculated proportional stock density for each species of trout using minimum stock and quality lengths suggested in Willis et al. (1993) (200 mm TL and 330 mm TL, respectively for all trout).

RESULTS

We electrofished 17 days in September and October 2016, on seven main stem Salmon River transects (Figure 34), for a total of 82.8 hours, and caught 1,885 target fish (trout spp., Chinook Salmon and steelhead parr, and Smallmouth Bass), 59 of which were recaptures. Overall target species catch composition (n = 1,826) was 49.1% O. mykiss parr (n = 896, 93% natural origin and 7% hatchery origin), 26.2% Chinook Salmon parr (n = 478, 99% natural origin and <1% hatchery origin), 16.0% Westslope Cutthroat Trout (n = 293), 4.5% adult Rainbow Trout (> 300 mm TL)(n = 82), 2.3% Bull Trout (n = 42), 1.6% trout hybrids (Cutthroat x Rainbow n = 28, Brook x Bull n = 1), and <0.1 % Smallmouth Bass (n = 6). Catch rates showed that, in general, Chinook Salmon parr, steelhead parr, and adult Rainbow Trout were relatively more abundant in the middle transects (Deer Gulch to Colston, Rattlesnake to Elevenmile, and Kilpatrick to Elk Bend), while Westslope Cutthroat Trout and Bull Trout were relatively more abundant in the upper transects (Pennal Gulch to Watt’s Bridge, and East Fork to Deadman’s Hole) (Table 24, Figure 35). Mark/recapture point estimates for both O. mykiss parr and Westslope Cutthroat Trout corroborated with catch rate findings (Table 25, Figure 36).

Westslope Cutthroat Trout PSD-Q was highest in the East Fork to Deadman’s (45%, n = 47) and Rattlesnake to Elevenmile transects (33%, n = 4), and was above 20% in all transects but one (Pennal to Watt’s, 10%, n = 113) (Table 26). We generally caught larger Westslope Cutthroat Trout (> 400 mm TL) in the upper transects (East Fork to Deadman’s, Pennal to Watt’s, and Kilpatrick to Elk Bend), but quality size Westslope Cutthroat Trout were found in all transects (Figure 37). Westslope Cutthroat Trout relative weights were slightly higher in the

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upper transects, but the difference was not significant (Figure 38). Bull Trout PSD-Q exceeded 30% in five of the six transects where they were captured (Table 26), but the largest Bull Trout were captured in the upper transects (East Fork to Deadman’s and Pennal to Watt’s) (Figure 39). Mean relative weight was near 100 for Bull Trout in all transects where they were observed (Figure 38). O. mykiss PSD-Q was very low (< 20%) in all transects (Table 25), but this is misleading due to the relatively large numbers of O. mykiss parr we captured, of which the majority are likely steelhead. When we look only at O. mykiss greater than 300 mm TL (which we considered adult Rainbow Trout), mean total length exceeded 350 mm in four of the six transects where they were captured (Table 26). O. mykiss were found in every transect, but Rainbow Trout adults were primarily found only in the middle transects during our surveys (Figure 40). The largest Rainbow Trout we caught were 585 mm TL and 440 mm TL in the Kilpatrick to Elk Bend and Deer Gulch to Colston transects, respectively. Rainbow Trout relative weights were similar between transects, and mean values for the seven transects ranged from 86 to 98 (Figure 38).

We recaptured 27 fish during our surveys that had been previously PIT tagged by other projects in the basin. All previously PIT tagged anadromous parr (Chinook Salmon, n = 3 and steelhead, n = 13) that we recaptured were tagged in either the Lemhi River or the Pahsimeroi River as outmigrants in 2016, with the exception of one hatchery steelhead parr we captured in the Pennal to Watt’s transect, which was reared at Hagerman Fish Hatchery and tagged prior to release at Sawtooth Hatchery in April, 2016 (Table 27). All previously PIT tagged Westslope Cutthroat Trout we recaptured (n = 5) were tagged in the North Fork Salmon River in the fall of 2016, and all were recaptured in the transects immediately above and below the mouth of the North Fork Salmon River (Table 27). Both previously PIT tagged Rainbow Trout adults we caught (n = 2) were tagged in the Pahsimeroi River as “steelhead”; one in 2013 and one in 2014 (Table 27). Both fish residualized and never outmigrated to the ocean. Finally, we recaptured one previously PIT tagged Bull Trout in the lower transects (Morgan Bar to Red Rock) that was tagged at the Hayden Creek screw trap in the fall of 2015, and three previously PIT tagged Bull Trout in the upper transects (Pennal to Watt’s and East Fork to Deadman’s) that had all been tagged at the East Fork Salmon River fish trap in 2012, 2013, and 2014, respectively.

Although we did not enumerate non-target species in most transects, visual estimation determined they (mainly Mountain Whitefish, various Sucker spp., and Northern Pikeminnow) outnumbered target species in all transects we surveyed in 2016. To quantify abundance of non-target species for reference, we conducted a two-pass mark/recapture estimate for a 3.2 km section of the Deadwater to Indianola transect in September, 2016. We caught 233 non- target fish during 1.2 hours of electrofishing on the first pass (CPUE = 187.9 fish/hr), 232 of which were marked with a fin clip, and we caught 387 non-target fish during 1.3 hours of electrofishing on the second pass (CPUE = 292.5 fish/hr), 11 of which were recaptures. Overall CPUE for non-target fish in the transect sub-section was 241.9 fish/hr over both passes. Non- target species composition was, in descending order, Largescale Sucker (31.5%, n = 192), Mountain Whitefish (29.1%, n = 177), Northern Pikeminnow (13.3%, n = 81), Bridgelip Sucker (11.5%, n = 70), Mountain Sucker (10.5%, n = 64), Chiselmouth Chub (3.6%, n = 22), and Redside Shiner (<1%, n = 3). On the second pass, we recaptured seven Mountain Whitefish, three Largescale Suckers, and one Northern Pikeminnow. All non-target fish were pooled to gather a rough estimate of their overall abundance in the subsection. Using the Chapman (single mark/recapture event) estimator, overall non-target fish abundance (± 95% CI) was estimated at 7,506 fish (4,402 – 13,808) in the 3.2 km sub-section, or 2,346 non-target fish/km. Size distributions for all non-target fish captured are shown in Figure 41.

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DISCUSSION

Catch rates of target species were likely affected somewhat by survey timing and water temperature in 2016. For example, 36 of 44 (82%) Westslope Cutthroat Trout caught in the Deadwater to Indianola transect, and 22 of 49 (45%) Westslope Cutthroat Trout caught in the Morgan Bar to Red Rock transect were caught on the third passes of those surveys, when water temperatures had decreased substantially (Table 24). All previously PIT tagged Westslope Cutthroat Trout we caught in those transects were tagged in the North Fork Salmon River, and hadn’t emigrated from the North Fork Salmon River until the end of August/beginning of September, based on their last detection in the North Fork. Additionally, Bull Trout were not encountered until the third pass of the first round of surveys in late September, which is likely when they began moving into the main stem river after returning from spawning tributaries. Based on these findings, we suggest optimal timing for conducting these surveys in the fall should be after river temperature cools to 14° or 15°C, in late September or early October, but before temperature reaches below 6°C.

Very few anadromous adults were encountered during electrofishing in 2016. As per our permit guidelines, when an adult Chinook Salmon or steelhead is encountered, shocking is suspended to allow the fish to move upstream past the shocking boats. We briefly encountered one adult Chinook Salmon on each of our first two passes in the Deadwater to Indianola transect and our first pass in the Morgan Bar to Red Rock transect in 2016. No more anadromous adults were encountered until our last passes on the Pennal to Watt’s Bridge section and the Kilpatrick to Elk Bend section, when we briefly saw one and two adult steelhead, respectively.

On September 4th and September 21st in the Deer Gulch to Colston section, we briefly encountered White Sturgeon Acipenser transmontanus. On both occasions, at the bottom end of Cronks Canyon, we had a White Sturgeon breach the surface of the water and swim upstream of our shocking boats. We believe that they were two different individuals, and estimate they were four and six feet in length, respectively.

MANAGEMENT RECOMMENDATIONS

1. Monitor survival and migration timing of PIT tagged juvenile steelhead and Chinook Salmon (presumably overwintering in the main stem Salmon River), and compare with survival estimates from spring emigrating juveniles tagged at screw traps in the Lemhi and Pahsimeroi Rivers.

2. Design and conduct radio telemetry studies throughout the basin to locate spawning tributary strongholds for large fluvial Rainbow and Cutthroat trout, using future main stem electrofishing surveys in the fall as potential tagging events.

3. Initiate studies to determine the current status and distribution of White Sturgeon in the upper Salmon River basin.

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Table 23. Values (x) used to calculate confidence limits for a Poisson frequency distribution with total number of recaptures (R) equaling 0 through 4.

95 % R Lower Upper 0 0 3.285 1 0.051 5.323 2 0.355 6.686 3 0.818 8.102 4 1.366 9.598

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Table 24. Catch rates (fish/hr) by day for all target fish captured during main stem Salmon River electrofishing in 2016. WCT = Westslope Cutthroat Trout, RBT = Rainbow Trout, BUT = Bull Trout, CHN = Chinook Salmon, BRK = Brook Trout, SMB = Smallmouth Bass. Water RBT >300 mm TL CHN parr O. mykiss parr temp Effort natural hatchery BU hatchery natural hatchery natural RBT x BRK x SM Tota (°C) (hours) WCT origin origin T origin origin origin origin WCT BUT B l East Fork to Deadman's 5-Oct 6.5 4.70 2.8 0.0 0.0 1.7 0.0 5.5 0.0 4.0 0.4 0.0 0.0 14.5 13-Oct 4.0 4.74 2.3 0.0 0.0 1.7 0.0 3.4 0.0 1.7 0.2 0.2 0.0 9.5 19-Oct 4.5 4.05 5.7 0.0 0.0 2.0 0.0 12.9 0.5 4.2 0.2 0.0 0.0 25.4 Pennal to Watt's 4-Oct 8.5 4.40 6.6 0.5 0.5 0.5 0.0 5.9 1.1 13.2 0.2 0.0 0.0 28.4 12-Oct 6.5 4.75 11.2 1.1 0.4 0.8 0.0 6.9 1.5 11.4 0.2 0.0 0.0 33.5 18-Oct 6.5 4.43 7.0 0.7 0.2 1.4 0.0 4.5 0.9 11.3 0.2 0.0 0.0 26.2 Deer Gulch to Colston 4-Sep 11.5 4.76 1.7 2.5 0.0 0.0 0.0 2.5 4.8 12.6 0.6 0.0 0.0 24.8 11- 12.0 3.46 0.3 2.6 0.0 0.0 0.0 3.8 4.0 9.5 0.3 0.0 0.0 20.5 Sep 21- 12.5 4.10 1.5 1.5 0.0 0.0 0.0 4.9 2.4 21.2 1.7 0.0 0.0 33.2 Sep Kilpatrick to Elk Bend 11-Oct 9.0 4.67 4.9 1.1 0.0 0.2 0.2 15.4 1.7 18.0 0.6 0.0 0.0 42.2 17-Oct 8.5 3.12 1.9 2.2 0.0 0.3 0.0 8.3 1.3 9.0 0.3 0.0 0.0 23.4 24-Oct 7.5 3.87 1.3 1.0 0.3 0.0 0.3 17.6 1.8 10.3 0.3 0.0 0.0 32.8 Rattlesnake to Elevenmile 3-Oct 9.5 4.53 0.9 1.1 0.0 0.2 0.0 13.9 0.7 21.7 0.7 0.0 0.0 39.1 Morgan Bar to Red Rock 3-Sep 14.0 5.88 1.4 1.4 0.0 0.0 0.0 0.7 0.5 5.8 0.0 0.0 0.0 9.7 10- 13.0 5.32 3.6 1.1 0.0 0.0 0.0 0.8 0.6 9.2 0.2 0.0 0.6 16.0 Sep 20- 14.0 5.49 4.0 0.9 0.2 0.4 0.0 3.8 0.7 16.4 0.4 0.0 0.0 26.8 Sep Deadwater to Indianola 2-Sep 17.0 5.35 0.7 0.2 0.0 0.0 0.0 0.2 0.0 0.9 0.0 0.0 0.4 2.4 9-Sep 14.0 1.24 3.2 0.0 0.0 0.0 0.0 0.0 0.0 4.8 0.0 0.0 0.8 8.9 19- 14.0 3.94 9.1 0.0 0.0 0.5 0.0 0.5 0.0 4.3 0.0 0.0 0.0 14.5 Sep

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Table 25. Numbers of O. mykiss parr and Westslope Cutthroat Trout marked (M), captured (C), and recaptured (R) during three passes of electrofishing surveys on each transect in September and October, 2016 on the main stem Salmon River. Numbers were used to estimate abundance (fish/km) in each transect, if recaptures allowed.

O. mykiss parr Westslope Cutthroat Trout

Transect Est. length M C R 95% CI M C R Est. fish/km 95% CI fish/km (km) Transect name East Fork to Deadman's Hole 12.2 27 17 0 -- -- 24 22 1 23.4 (7.1 - 42.9)

Pennal Gulch to Watt's Bridge 12.7 121 54 4 105.7 (47.2 - 264.2) 29 54 3 32.4 (13.2 - 81.2)

Deer Gulch to Colston 8.7 126 97 10 130.0 (73.8 - 251.0) 9 6 1 3.9 (1.3 - 7.4)

Kilpatrick to Elk Bend 10.8 121 47 3 135.6 (55.4 - 338.9) 27 7 3 5.1 (2.1 - 13.0)

Morgan Bar to Red Rock 13.1 83 94 11 50.8 (29.5 - 95.2) 26 22 4 9.4 (4.2 - 23.7)

Deadwater to Indianola 11.2 11 17 2 6.4 (2.3 - 16.1) 8 36 0 -- --

Table 26. Size structure summary for target species collected during Salmon River electrofishing in 2016.

Rainbow Trout Westslope Cutthroat Rainbow X Brook X Bull Smallmouth Bull Trout > 300 mm TL Trout Cutthroat Trout Trout Bass

Mean TL PSD- Mean TL Mean TL PSD-Q PSD-Q Mean TL (mm) (± SE) (mm) (± SE) Q (mm) (± SE) (mm) (± SE) Transect name East Fork to Deadman's -- -- 319.9 (± 9.6) 45% 392.8 (± 33.5) 74% 394.3 (± 40.5) 315.0 (± 0.0) -- 347.5 (± Pennal to Watt's 12.2) 7% 259.1 (± 4.1) 10% 384.2 (± 44.7) 33% 301.0 (± 73.5) -- -- Deer Gulch to Colston 367.6 (± 8.4) 17% 264.6 (± 11.8) 29% -- -- 269.9 (± 19.7) -- -- 382.4 (± Kilpatrick to Elk Bend 18.5) 11% 282.3 (± 10.8) 28% 287.0 (± 65.1) 50% 315.0 (± 25.6) -- -- Rattlesnake to 354.8 (± Elevenmile 22.9) 8% 281.5 (± 42.5) 33% 257.0 (± 0.0) 0% 268.0 (± 19.9) -- -- Morgan Bar to Red Rock 356.5 (± 8.8) 16% 289.8 (± 7.0) 29% 450.0 (± 89.1) 100% 269.0 (± 8.7) -- 214.0 (± 8.2) Deadwater to Indianola 301.0 (± 0.0) 0% 283.5 (± 7.1) 21% 312.5 (± 14.8) 50% -- -- 280.7 (± 71.2)

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Table 27. Recapture information for fish PIT tagged prior to capture during our 2016 Salmon River e-fishing surveys.

Recap Recap Recapture Recapture Tagging Tagging Tagging Species length weight PIT tag number Tagging location transect date date length (mm) weight (g) (mm) (g) Deadwater 9/19/2016 WCT 195 54 3D9.1BF1A1C25F 9/9/2016 North Fork SR 184 56

Deadwater 9/19/2016 WCT 235 110 3D9.1BF2329B8D 8/10/2016 North Fork SR 212 92

Deadwater 9/19/2016 WCT 286 200 3D9.1BF2331743 8/10/2016 North Fork SR 227 194

Deadwater 9/19/2016 CHN 108 10 3DD.0077814B2D 9/14/2016 Lemhi River 107 16

Morgan Bar 9/20/2016 BUT 387 535 3D9.1C2D57764E 9/22/2015 Hayden Creek 239 157

Morgan Bar 9/20/2016 CHN 110 14 3DD.0077816C2E 9/14/2016 Lemhi River 109 17

Morgan Bar 9/20/2016 CHN 102 17 3DD.00778188D0 9/12/2016 Lemhi River 102 13

Morgan Bar 9/3/2016 RBT 420 800 3D9.1C2C94F801 10/13/2013 Pahsimeroi River 208 100

Morgan Bar 9/20/2016 STHD 215 109 3DD.00775D2B36 6/17/2016 Lemhi River 136 32

Morgan Bar 9/10/2016 STHD 197 70 3DD.00775D7FA7 5/28/2016 Lemhi River 98 10

Morgan Bar 9/20/2016 STHD 196 71 3DD.00775DF4BF 5/26/2016 Lemhi River 102 11

Morgan Bar 9/20/2016 STHD 206 85 3DD.00775E1C8C 5/9/2016 Lemhi River 95 9

Morgan Bar 9/3/2016 STHD 187 62 3DD.00778069A6 5/5/2016 Lemhi River 95 10

Morgan Bar 9/10/2016 STHD 194 62 3DD.00778DAB7F 9/4/2016 Lemhi River 181 62

Morgan Bar 9/20/2016 WCT 360 380 3D9.1BF1A8D750 9/4/2016 North Fork SR 355 414

Morgan Bar 9/10/2016 WCT 235 115 3D9.1BF1CE9244 8/14/2016 North Fork SR 212 98

Kilpatrick 10/24/2016 STHD 225 124 3DD.00778C3D9B 10/13/2016 Pahsimeroi River 210 119

122 Table 27 (continued)

Recap Recap Recapture Recapture Tagging Tagging Tagging Species length weight PIT tag number Tagging location transect date date length (mm) weight (g) (mm) (g) Deer Gulch 9/4/2016 RBT 403 684 3D9.1C2E04DB86 11/13/2014 Pahsimeroi River 205 91

Deer Gulch 9/11/2016 STHD 292 226 3DD.007751A285 11/23/2015 Pahsimeroi River 161 43

Deer Gulch 9/4/2016 STHD 200 84 3DD.00778041C4 5/30/2016 Pahsimeroi River 113 17

Deer Gulch 9/11/2016 STHD 195 84 3DD.00778C2E67 8/1/2016 Pahsimeroi River 171 53

Deer Gulch 9/21/2016 STHD 265 164 3DD.00778C64B7 6/3/2016 Pahsimeroi River 122 21

Pennal 10/12/2016 BUT 651 2334 3D9.1BF258D3AB 7/7/2014 East Fork SR 499 --

Pennal 10/12/2016 STHD 265 192 3DD.0077810595 6/3/2016 Pahsimeroi River 126 24

Pennal 10/18/2016 STHD-H 274 158 3DD.003BE06CAD 11/3/2015 Hagerman FH -- --

East Fork 10/13/2016 BUT 670 3002 3D9.1BF24313BD 6/15/2012 East Fork SR 515 --

East Fork 10/5/2016 BUT 673 2404 3D9.1BF27E6AC2 6/26/2013 East Fork SR 535 --

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Figure 34. Approximate locations of sites surveyed along the main stem Salmon River in 2016. See Figure 35 for survey location names.

124

25 natural origin Chinook Salmon parr natural origin O. mykiss parr 20 adult Rainbow Trout (> 300 mm TL)

Bull Trout SE)

± Westslope Cutthroat Trout 15

10 Mean catch rate (fish/hr) ( 5

0 East Fork to Pennal to Watt's Deer Gulch to Kilpatrick to Elk Rattlesnake to Morgan Bar to Deadwater to Deadman's Colston Bend Elevenmile Red Rock Indianola Downstream

Figure 35. Mean catch rates (fish/hr) (± SE) for top five target species captured in each of the main stem Salmon River electrofishing transects in September and October, 2016.

125

350400 Natural origin O. mykiss parr 300350 300 250 Westslope Cutthroat Trout 250 200 200 150 150 100 100 No 95% CI) 50 50

± recaptures 0

100

60 Estimated fish/km ( fish/km Estimated

20 No recaptures 0 East Fork to Pennal Gulch Deer Gulch Kilpatrick to Morgan Bar Deadwater to Deadman's to Watt's to Colston Elk Bend to Red Rock Indianola Hole Bridge Downstream

Figure 36. Peterson abundance estimates (± 95% confidence intervals) for Westslope Cutthroat Trout and natural origin O. mykiss parr obtained via mark/recapture electrofishing surveys conducted in September and October 2016 on the main stem Salmon River. Density (fish/km) calculated by dividing abundance estimate by transect length (km).

126

0.50 East Fork to Deadman's

0.25

0.00

0.50 Pennal to Watt's

0.25

0.00

0.50 Deer Gulch to Colston

0.25

0.00

0.50 Kilpatrick to Elk Bend

0.25 Downstream

Relative frequency 0.00

0.50 Rattlesnake to Elevenmile

0.25

0.00

0.50 Morgan Bar to Red Rock

0.25

0.00

0.50 Deadwater to Indianola

0.25

0.00

Total length (mm)

Figure 37. Westslope Cutthroat Trout length frequency in all main stem Salmon River transects surveyed in September and October, 2016.

127

150 Westslope Cutthroat Trout 130

110

150 Adult Rainbow Trout (>300 mm TL) 130 ) r 110

70 Relative weight (W weight Relative 50

150 Bull Trout 130

110

30 East Fork to Pennal to Deer Gulch Kilpatrick to Rattlesnake Morgan Bar Deadwater Deadman's Watt's to Colston Elk Bend to to Red Rock to Indianola Elevenmile Downstream

Figure 38. Mean relative weights for Westslope Cutthroat Trout, Rainbow Trout, and Bull Trout caught in the main stem Salmon River during electrofishing surveys in September and October, 2016. Box represents Q1 to Q3 and mean, and whiskers show minimum and maximum observed values for each transect. Single dots are for sample size of n = 1. Dashed line at Wr = 100 represents species average based on standard weight for a given length.

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0.50 East Fork to Deadman's

0.25

0.00

0.50 Pennal to Watt's

0.25

0.00

0.50 Deer Gulch to Colston

0.25

0.00

0.50 Kilpatrick to Elk Bend

0.25

Relative frequency 0.00 Downstream 0.50 Rattlesnake to Elevenmile

0.25

0.00

0.50 Morgan Bar to Red Rock

0.25

0.00

0.50 Deadwater to Indianola

0.25

0.00

Total length (mm)

Figure 39. Bull Trout length frequency in all main stem Salmon River transects surveyed in September and October, 2016.

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0.30 East Fork to Deadman's 0.20

0.10

0.00 0.30 Pennal to Watt's 0.20

0.10

0.00 0.30 Deer Gulch to Colston 0.20

0.10

0.00 0.30 Kilpatrick to Elk Bend

0.20

0.10

0.00 Relative frequency 0.30 Downstream Rattlesnake to Elevenmile 0.20

0.10

0.00 0.30 Morgan Bar to Red Rock 0.20

0.10

0.00 0.30 Deadwater to Indianola 0.20

0.10

0.00

Total length (mm)

Figure 40. O. mykiss length frequency in all main stem Salmon River transects surveyed in September and October, 2016.

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0.20 Bridgelip Sucker 0.15

0.10

0.05

0.00 0.20 Chiselmouth Chub 0.15

0.10

0.05

0.00 0.20 Largescale Sucker 0.15

0.10

0.05

0.00 0.20 Mountain Sucker 0.15 Relative frequency 0.10

0.05

0.00 0.20 Mountain Whitefish 0.15

0.10

0.05

0.00

0.20 Northern Pikeminnow 0.15

0.10

0.05

0.00

Total length (mm)

Figure 41. Non-target fish length-frequency in 3.2km sub-section of the Deadwater to Indianola transect, Salmon River, September 2016.

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WILD TROUT REDD COUNTS

ABSTRACT

Regional fisheries staff conducted redd count surveys for resident Rainbow Trout Oncorhynchus mykiss and Bull Trout Salvelinus confluentus populations in 2016, as part of an annual trend monitoring program. In spring, we counted 190 Rainbow Trout redds in Big Springs Creek and 46 in the Lemhi River. During Bull Trout redd count surveys in fall 2016, we counted 13 redds in Alpine Creek, 60 in Fishhook Creek, eight in Fourth of July Creek, 89 in Bear Valley Creek, and 41 redds in the main stem of Hayden Creek. Bull Trout redds were not enumerated in the East Fork Hayden Creek in 2016. Compared to surveys in 2015, the number of Rainbow Trout redds counted in the Lemhi River and Big Springs Creek in 2016 increased slightly, and the number of Bull Trout redds counted in 2016 increased in Alpine and Hayden Creek, but decreased in all other transects.

Author:

Jordan Messner, Regional Fisheries Biologist

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INTRODUCTION

Salmon Region IDFG staff conduct annual redd counts for resident and fluvial Rainbow Trout Oncorhynchus mykiss and Bull Trout Salvelinus confluentus in nine streams in the region, to monitor trends in spawner abundance. In 1994, the we began counting Rainbow Trout redds in Big Springs Creek, a tributary to the upper Lemhi River near Leadore, and in 1997 another transect was established for Rainbow Trout on the upper Lemhi River, just above the confluence with Big Springs Creek. Redd count monitoring for Rainbow Trout on these transects provides a general indication of population abundance trends over time. Numerous habitat improvement projects, changes in water-use practices, alterations in land management practices, and fisheries regulation changes have occurred in the upper Lemhi River basin in the last decade, all of which have likely benefited resident fish populations.

Bull Trout were listed as threatened under the Endangered Species Act (ESA) on June 10, 1998. That fall, we established the Salmon Region’s first trend transects for enumerating Bull Trout redds. Trend transects were established on Alpine and Fishhook Creeks in the Sawtooth Basin, near Stanley in 1998, on Bear Valley Creek and East Fork Hayden Creek in the Lemhi River drainage in 2002, on Fourth of July Creek in the Stanley basin in 2003, and on Upper Hayden Creek in the Lemhi River drainage in 2006.

Over the years, as additional redd production areas have been located (outside of established transect boundaries), new trend transects have been added to encompass as much spawning production as possible. New transects were added to account for additional productivity on Bear Valley Creek in 2007, on Fishhook Creek in 2008, and on Alpine Creek in 2011. In upper Hayden Creek, the trend transect was moved altogether in 2010, when staff determined the existing transect was too low in the drainage and most Bull Trout spawning occurred much higher.

OBJECTIVES

1. Maintain trend monitoring datasets for spawning resident and fluvial trout in the region by continuing annual redd counts and operating fish weirs in priority tributaries.

STUDY SITES AND METHODS

Rainbow Trout Redd Count Monitoring

Big Springs Creek

Big Springs Creek is a tributary to the Lemhi River, located approximately 8 km north of Leadore, Idaho. Two trend transects (Tyler transect and Neibaur transect) are walked on Big Springs Creek annually (Messner et al, 2016) (Appendix F). The Big Springs transects were the first resident/fluvial Rainbow Trout redd count trend transects established in the region, in 1994.

Redd counts are usually conducted during the last week of April or the first week of May on Big Springs Creek. The counts are “single pass” counts, where redds are counted on a single occasion and are not flagged. Redd counts on Big Springs Creek were conducted on May 5 in 2016.

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Lemhi River

The Lemhi River flows approximately 100 km from its headwaters near Leadore, Idaho to its confluence with the Salmon River at Salmon, Idaho. The upper Lemhi River redd count trend transect was established in 1997 and includes a 3 km section of Lemhi River flowing through the property known as the Merrill Beyeler Ranch from the fence line 100 meters upstream of the upper water gap to the lower fenced boundary (Messner et al, 2016) (Appendix F).

Redd counts are usually conducted during the last week of April or the first week of May, at the same time and using the same methods as for Big Springs Creek (single pass). Redd counts were also conducted on May 5, 2016.

Bull Trout Redd Count Monitoring

Alpine Creek

Alpine Creek is a tributary to Alturas Lake Creek, which flows into Alturas Lake in the Sawtooth basin, approximately 35 km south of Stanley, Idaho. Two trend transects are walked annually on Alpine Creek (Messner et al, 2016) (Appendix F).

Historically, two visual ground counts are conducted annually, about two weeks apart, on both transects in Alpine Creek. However, only one count was conducted in 2016 due to insufficient time for completing both counts. The survey in 2016 was conducted on September 12 to account for as much spawning as possible. For each transect, all redds in progress or completed redds were counted during the survey.

Fishhook Creek

Fishhook Creek is a tributary of Redfish Lake in the Sawtooth basin, approximately 10 km south of Stanley, Idaho. Two trend transects are walked on Fishhook Creek annually (Messner et al, 2016) (Appendix F).

Historically, two visual ground counts are conducted annually, about two weeks apart, on each of the two Fishhook Creek transects. Only one count was conducted in 2016 due to insufficient time for completing both counts. The survey on Fishhook Creek was conducted on September 12, 2016. For each transect, all redds in progress or completed redds were counted during the survey.

Fourth of July Creek

Fourth of July Creek is a tributary of the upper Salmon River in the Sawtooth basin, located approximately 28 km south of Stanley, Idaho. One single visual ground count is conducted on Fourth of July Creek annually (Messner et al, 2016) (Appendix F).

Fisheries staff conducted a redd count survey for Bull Trout in Fourth of July Creek on September 4, 2016. Redd counts on Fourth of July Creek are “single pass” counts, meaning redds are enumerated on a single occasion and are not flagged.

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Hayden Creek

Hayden Creek is the largest tributary to the Lemhi River. The trend transect currently surveyed on upper Hayden Creek (Appendix F) is not the same that was established in 2006. The older transect produced single digit Bull Trout redd counts each year between 2006 and 2009. In 2010, the transect boundaries were moved upstream to the current location (Messner et al, 2016) to encompass the bulk of spawning activity (M. Biggs, IDFG, personal communication).

Both fluvial and resident forms of Bull Trout are found in upper Hayden Creek. The upper Hayden Creek trend transect is walked twice annually, approximately one week apart, to visually count fluvial and resident Bull Trout redds. In 2016, four passes were conducted. Redd counts in 2016 were conducted on August 29, and September 12, 20, and 27. Since fluvial Bull Trout are larger in size than residents, fluvial Bull Trout redds were classified as redds equal to or greater than 0.4 m by 0.6 m in diameter while redds smaller in size were considered those of resident Bull Trout. For each transect, all redds in progress or completed redds were counted during the first survey and flagged. On the second survey in each transect, additional completed redds were counted and included with the number of flagged redds to provide a total number of redds

Bear Valley Creek

Bear Valley Creek is a tributary of Hayden Creek in the Lemhi River drainage, located approximately 60 km south of Salmon, Idaho. Two trend transects are walked annually on Bear Valley Creek to enumerate Bull Trout redds (Messner et al, 2016) (Appendix F).

Two to three visual ground counts are conducted annually about one week apart on the Bear Valley Creek transects. A third pass is typically only conducted when the ratio of live fish to redds is greater than one on the second pass. In 2016, six counts were conducted on August 23 and 29, and September 6, 12, 20, and 26. Both fluvial and resident Bull Trout life histories are found in Bear Valley Creek. Since fluvial Bull Trout are larger in size than residents, fluvial Bull Trout redds were classified as redds equal to or greater than 0.4 m by 0.6 m in diameter while redds that were smaller in size were considered those of resident Bull Trout. For each transect, all redds in progress or completed redds were counted during the first survey and flagged. On the second and third passes in each transect, additional completed redds were counted and included with the number of flagged redds to provide a total number of redds.

East Fork Hayden Creek

Bull Trout redd counts on East Fork Hayden Creek were not conducted in 2016 due to time constraints.

135

RESULTS AND DISCUSSION

Rainbow Trout Redd Count Monitoring

Big Springs Creek and Lemhi River

Fisheries staff observed 190 Rainbow Trout redds in Big Springs Creek and 46 Rainbow Trout redds in the upper Lemhi River in 2016, for a total of 236 redds (Table 28, Figure 42). On Big Springs Creek, 124 redds were counted in the historic Neibaur Ranch transect while 66 redds were observed in the Tyler Ranch transect (Table 28). The total number of redds counted in 2016 falls on the average trend count line (Figure 42). The 2012 to 2014 trend counts were three of the four highest counts on record, but spawner abundance decreased in 2015 and remained relatively lower in 2016. Numerous habitat improvement projects, tributary reconnections, and changes in land-use practices over the last several decades in the upper Lemhi River seem to have benefitted the resident Rainbow Trout population, and trend redd counts may provide insight to those benefits. These transects will continue to be monitored annually.

Bull Trout Redd Count Monitoring

Alpine Creek

In the upper Alpine Creek trend transect, we counted six Bull Trout redds in 2016 (Table 29, Figure 43). Prior to 2013, no Bull Trout redds, or live fish, had been observed in the upper trend area in five years. Only one redd was counted in the upper transect in 2013, four redds in 2014, and three in 2015. In the lower trend transect (established in 2010), no Bull Trout redds were observed in 2014 or 2015, but we counted seven Bull Trout redds in 2016. This is the first time we have counted more than two Bull Trout redds in that reach since the transect was established (Figure 43).

This year’s Alpine Creek redd abundance is one of the highest on record. The cause for low numbers of Bull Trout redds observed from 2008 to 2015 is unknown. From 2000 to 2007, mean redd abundance was 14.4 (± 1.8) in the upper trend transect. In 2014, we questioned whether we were missing spawning activity (geographically or temporally) since we had not observed more than four redds in a given year in Alpine Creek since 2007. In 2015, we walked the entire stream from approximately 2 km above the upper transect, to Alturas Lake, and did not find any evidence that there was a great deal of spawning activity occurring outside of these transects.

Fishhook Creek

Forty-seven Bull Trout redds were observed in the upper trend transect in Fishhook Creek in 2016, and 13 redds were counted in the lower transect (Table 29, Figure 44). Redd abundances in the upper transect in 2015 and 2016 are the highest documented to date. Prior to 2015, Bull Trout redd numbers in Fishhook Creek have remained relatively consistent over the years, indicating a stable population. However, the increase in spawner abundance in 2015 and 2016 suggest an increase in overall population abundance.

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Fourth of July Creek

Staff counted only eight completed Bull Trout redds in the Fourth of July Creek trend transect in 2016 (Table 29, Figure 45). Based on a pattern that emerged in the data since we began monitoring redd abundance, we expected to see relatively high abundance in 2016, but this was not the case (Figure 45). This is the lowest count we have observed since we began monitoring in 2003.

Hayden Creek

Forty-one Bull Trout redds were counted in the upper Hayden Creek trend site in 2016 (Table 30, Figure 46). Twenty-three redds were estimated to be fluvial size (56%) and 18 were resident size (44%).

Bear Valley Creek

Regional fisheries staff counted 30 Bull Trout redds in the older Bear Valley Creek trend transect in 2016 and 59 redds in the newer trend transect, for a total of 89 redds (Table 30, Figure 47). Sixty redds were estimated as fluvial size (67%) and 29 as resident size (33%). In general, Bull Trout redd abundance has been relatively high in Bear Valley Creek over the past seven years.

East Fork Hayden Creek

Bull Trout redds were not counted in the East Fork of Hayden Creek in 2016.

MANAGEMENT RECOMMENDATIONS

1. Continue monitoring trends in spawner abundance for resident trout populations in designated trend transects.

2. Collect fluvial Bull Trout (either pre- or post-spawn) to implant PIT tags for further movement and growth study throughout the upper Salmon River basin.

3. Consider collecting fluvial Bull Trout fin rays to determine age structure of spawning groups.

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Table 28. Summary of Rainbow Trout redds counted in the upper Lemhi River and Big Springs Creek (BSC) transects, 1994 - 2016.

Big Springs Big Springs Creek Neibaur Creek Lemhi River Year Ranch Tyler Ranch Beyeler Ranch Total 1994 ------40 1995 57 -- -- 57 1996 32 -- 7 39 1997 44 45 8 97 1998 93 124 18 235 1999 39 71 29 139 2000 160 123 23 306 2001 95 186 2 283 2002 360 193 3 556 2003 128 103 56 287 2004 174 45 15 234 2005 75 43 3 121 2006 63 143 9 215 2007 163 62 8 233 2008 82 108 9 199 2009 100 54 10 164 2010 132 57 18 207 2011 103 49 20 172 2012 130 224 14 368 2013 159 122 49 330 2014 185 280 93 558 2015 65 60 75 200 2016 124 66 46 236

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Table 29. Bull trout redds counted in tributaries of the upper Salmon River in the Sawtooth National Recreation Area, 1998 - 2016.

Older Newer transect Stream Year transect Total redds redds redds Alpine Creek 1998 1 -- 1 1999 3 -- 3

2000 9 -- 9

2001 15 -- 15

2002 14 -- 14

2003 14 -- 14

2004 9 -- 9

2005 13 -- 13

2006 13 -- 13

2007 18 -- 18

2008 0 -- 0

2009 0 -- 0

2010 0 1 1

2011 0 2 2

2012 0 0 0

2013 1 2 3

2014 4 0 4 2015 3 0 3 2016 6 7 13 Fishhook Creek 1998 11 -- 11 1999 15 -- 15

2000 18 -- 18

2001 26 -- 26

2002 17 -- 17

2003 17 -- 17

2004 11 -- 11

2005 23 -- 23

2006 25 -- 25

2007 22 -- 22

2008 13 14 27

2009 21 12 33

2010 17 10 27

2011 11 7 18

2012 21 9 30

2013 15 13 28

2014 6 8 14

2015 61 2 63

139 Table 29 (continued)

Older Newer transect Stream Year transect Total redds redds redds Fishhook Creek 2016 47 13 60 Fourth of July Creek 2003 16 -- 16 2004 33 -- 33

2005 41 -- 41

2006 71 -- 71

2007 49 -- 49

2008 25a -- 25a

2009 50 -- 50

2010 56 -- 56

2011 51 -- 51

2012 50a -- 50a

2013 21 -- 21

2014 85 -- 85

2015 48a -- 48a 2016 8 8

a Numbers reported incorrectly in 2015 annual report

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Table 30. Bull trout redds counted in the Hayden Creek drainage in the Lemhi River basin, 2002 - 2016.

Older transect Newer transect Stream Year redds redds Total redds Bear Valley Creek 2002 26 -- 26 2003 42 -- 42 2004 44 -- 44 2005 34 -- 34 2006 26 60 86 2007 25 115 140 2008 27 21 48 2009 42 24 66 2010 37 22 59 2011 36 103 139 2012 33 91 124 2013 41 78 119 2014 66 134 200 2015 39 98 137 2016 30 59 89 Hayden Creek 2005 22 -- 22 2006 74 -- 74 2007 115 -- 115 2008 28 -- 28 2009 22 -- 22 2010 -- 29 29 2011 -- 49 49 2012 -- 39 39 2013 -- 14 14 2014 -- 29 29 2015 -- 18 18 2016 -- 41 41 a No count conducted

141

600 Lemhi BSC 500 Average

400

300

# of redds 200

100

Figure 42. Resident Rainbow Trout redds counted during ground surveys in the upper Lemhi River (Beyeler Ranch) and Big Springs Creek (BSC) (Neibaur and Tyler ranches), 1997 - 2016.

30 Lower transect redds 25 Upper transect redds

# of redds 10

Figure 43. Number of Bull Trout redds counted in both survey transects on Alpine Creek, 1998 - 2016.

142

60 Lower transect redds Upper transect redds 50

30 # of redds 20

Figure 44. Number of Bull Trout redds counted in both transects on Fishhook Creek, 1998 - 2016.

90 80 70

60 50 40 # of redds 30 20 10 0

Figure 45. Number of Bull Trout redds counted on Fourth of July Creek, 2003 - 2016.

143

140

120

100

60 # of redds 40

Figure 46. Number of Bull Trout redds observed in upper Hayden Creek redd count trend transect, 2005 - 2016.

250 Newer transect redds 200 Older transect redds

150

100 # of redds

Figure 47. Number of Bull Trout redds observed in the Bear Valley Creek transects, 2002 - 2016.

144

MIDDLE FORK SALMON RIVER TREND MONITORING

ABSTRACT

During July 2016, IDFG personnel snorkeled 43 trend transects in the Middle Fork Salmon River (MFSR) drainage to determine fish species composition, size, abundance, and density. Thirty-four mainstem Middle Fork Salmon River (MFSR) transects and nine tributary transects were snorkeled. For main stem transects surveyed in 2016 (both Corley and Traditional, combined) (n = 34), Westslope Cutthroat Trout Oncorhynchus clarkii lewisi had an overall mean density (± SE) of 1.91 fish/100 m2 (± 0.33), Rainbow Trout /steelhead O. mykiss mean density was 1.51 fish/100 m2 (± 0.66), and juvenile Chinook Salmon O. tshawytscha mean density was 1.69 fish/100 m2 (± 0.71). In tributary transects surveyed in 2016 (n = 9), Westslope Cutthroat Trout had an overall mean density of 0.65 fish/100 m2 (± 0.28), Rainbow Trout /steelhead mean density was 2.47 fish/100 m2 (± 0.66), and juvenile Chinook Salmon mean density was 2.13 fish/100 m2 (± 1.22).

In 2016, 46% (n = 147) of the 319 Westslope Cutthroat Trout observed during main stem snorkel surveys were greater than 300 mm TL, compared to 13% in 1971 (prior to catch-and- release regulations implemented in 1972). Forty-seven percent (47%) of Westslope Cutthroat Trout caught during angling surveys in 2016 were greater than 300 mm TL. That number has fluctuated from a low of 25% in 2007 to 53% in 1987, but has remained higher in the years since catch-and-release regulations began (1972) than during the four years of data we have prior. Average angler catch rate during surveys has remained relatively stable over the last seven years (2.8 to 5.8 fish/hr) and was 3.1 fish/hr in 2016. Westslope Cutthroat Trout accounted for 56% of the total angler catch and Rainbow Trout/Steelhead accounted for 40% in 2016.

Authors:

Jordan Messner, Regional Fisheries Biologist

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INTRODUCTION

The earliest fishery study conducted on the Middle Fork Salmon River (MFSR) was a tagging study that took place in 1959 and 1960. That study evaluated seasonal movement, age and growth structure, and mortality of Westslope Cutthroat Trout Oncorhynchus clarkii lewisi, to determine the impacts of a rapidly increasing recreational fishery (Mallet 1961, 1963). The study concluded that Westslope Cutthroat Trout in the MFSR could experience major declines due to year-round fishing pressure, and recommended to decrease the daily bag limit. Eventually catch-and-release regulations were adopted in 1972, and IDFG began monitoring abundance and size structure of MFSR Westslope Cutthroat Trout to evaluate the effectiveness of the new rules.

A 1971 study established snorkeling transects to be surveyed periodically in the MFSR drainage for monitoring fish population trends (Corley 1972; Jeppson and Ball 1977, 1979). In the 1971 report, these transects are described as main stem historical (Corley) transects (n = 6). In 1981, additional main stem transects were established in order to monitor steelhead O. mykiss populations on the MFSR (Thurow 1982, 1983, 1985). In 1985, the Department added additional snorkel sites to monitor trends in abundance of steelhead, juvenile Chinook Salmon O. tshawytscha, and Westslope Cutthroat Trout densities throughout the main stem and its tributaries (Reingold and Davis 1987a, 1987b, 1988; Lukens and Davis 1989; Davis et al. 1992; Schrader and Lukens 1992; Liter and Lukens 1994). The snorkel sites established in 1981 are known in this report as traditional main stem (n = 28) or traditional tributary (n = 10) transects. The Salmon Region has been snorkeling trend sites since 1971 and has been periodically monitoring trends in fish species composition and size structure caught during angling surveys in the MFSR since 1959. In 2008 we began recording fishing effort during angling surveys to monitor trends in catch rates.

OBJECTIVES

1. Monitor Rainbow Trout/Steelhead, juvenile Chinook Salmon, and Westslope Cutthroat Trout densities within the MFSR and its tributaries to evaluate long-term trends in population status.

2. Monitor angling catch rates, particularly for Westslope Cutthroat Trout, to evaluate long- term trends relating to angler satisfaction.

STUDY SITES AND METHODS

The Middle Fork Salmon River (MFSR) (Figure 48) is part of the Wild and Scenic Rivers System and flows through the Frank Church River of No Return Wilderness in central Idaho. The MFSR originates at the confluence of Bear Valley and Marsh creeks near Cape Horn Mountain. It flows 171 km to its confluence with the Salmon River, 92 km downstream from Salmon, Idaho. The MFSR is a major recreational river offering a wide variety of outdoor and back-country experiences. The number of people floating the river has increased substantially in the past 50 years, from 625 in 1962 to 10,601 in 2014. The U.S. Forest Service estimated total use days during the 2014 permit season on the MFSR (May 28-Sept. 3) to be 58,537 days (USFS website).

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Mainstem and Tributary Snorkeling Transects

MFSR snorkeling transects were sampled using techniques described by Thurow (1982). Snorkeling was conducted by two snorkelers floating downstream with the current, remaining as motionless as possible, along both sides of the river margin. All species observed were documented, and length and abundance were estimated for all salmonids. The area surveyed was estimated by multiplying the length snorkeled by the visible corridor (i.e. visibility). Visibility was measured at each site by suspending a sighting object in the water column and allowing the snorkeler to drift downriver until the object was unidentifiable. The snorkeler then moved upriver until the object reappeared clearly. The measured distance (m) between the object and the observer’s facemask was the visibility. Fish densities were calculated by dividing estimated abundance by the area of the transect.

Historical transects on the mainstem MFSR were established prior to 1985 while traditional transects were established after 1985. All six MFSR historical (Corley) transects, all 28 traditional main stem transects, and nine of 10 traditional tributary transects were snorkeled during July 19 to 26, 2016.

Project Angling

The main objective of ‘project angling’ is to evaluate current trends in angler catch rates and sizes of fish in angler creels. Project anglers used conventional fly-fishing and spinning tackle to gather catch rate and creel size information on 152.5 km of the mainstem MFSR from Boundary Creek to the confluence with the Salmon River in 2016. Anglers recorded data including the exact amount of time fished, gear type used, total length and species of their catch. These data were added to an existing trend dataset that has been sporadically maintained since 1959, and consistently maintained since 2008.

RESULTS AND DISCUSSION

Mainstem and Tributary Snorkeling Transects

Average densities (± SE) for Westslope Cutthroat Trout, Rainbow Trout, and Chinook Salmon parr in traditional mainstem MFSR transects were 2.06 fish/100 m2 (± 0.38), 1.75 fish/100 m2 (± 0.79), and 2.05 fish/100 m2 (± 0.85), respectively (Table 31). Average Mountain Whitefish density was 2.23 fish/100 m2 (± 0.39) in traditional main stem transects (Table 31). No Brook Trout S. fontinalis were observed in traditional main stem transects in 2016, but one Bull Trout Salvelinus confluentus was observed in the Marble Pool site. Average fish densities at the five historical main stem (Corley) sites snorkeled in 2016 were 1.23 fish/100 m2 (± 0.65) for Cutthroat Trout, 0.38 fish/100 m2 (± 0.24) for Rainbow Trout/Steelhead, 0.04 fish/100 m2 (± 0.03) for Chinook Salmon parr, and 2.69 fish/100 m2 (± 1.9) for Mountain Whitefish (Table 31). No Bull Trout or Brook Trout were observed at the Corley sites in 2016. The trend in average densities for Cutthroat, Rainbow/Steelhead, Chinook Salmon parr, and Mountain Whitefish across all main stem sites has tracked very similarly for the last several years, but densities were higher for all species across the board (at almost all sites) in 2016 compared to 2015 (Figure 49).

147

In the nine traditional tributary transects we snorkeled in 2016, fish densities averaged 0.65 fish/100 m2 (± 0.28) for Westslope Cutthroat Trout, 2.47 fish/100 m2 (± 0.66) for Rainbow Trout/Steelhead, 2.13 fish/100 m2 (± 1.22) for Chinook Salmon parr, 0.02 fish/100 m2 (± 0.02) for Bull Trout, and 1.93 fish/100 m2 (± 0.90) for Mountain Whitefish (Table 31). No Brook Trout were observed in traditional tributary transects in 2016.

Catch-and-release regulations on the main stem MFSR have been in effect since 1972. Prior to catch-and-release regulations, in 1971, the percent of Cutthroat Trout greater than 300 mm TL observed during snorkel surveys was 13%. That figure has ranged from 13% to 60% since that time. In 2016, 46% (n = 147) of the 319 Cutthroat Trout observed during snorkeling were estimated to be greater than 300 mm TL in main stem MFSR transects (Figure 50).

Snorkeling transects in the mainstem MFSR were established in 1971 and 1981 (Corley 1972; Thurow 1982) and likely represent one of the longest term trend data sets on Westslope Cutthroat Trout throughout their range. However, little has been done to evaluate what transects provide accurate trends in mimicking population abundance (High et al. 2008). Also, some transects are difficult and dangerous to snorkel during flow conditions over a river stage of 2.5 ft on the Middle Fork Lodge gauge (USFS gauge # 13309220). Survey counts conducted during high flows may represent inherent snorkeler bias since a snorkeler may not be able to accurately observe fish when challenged by difficult waters.

Project Angling

IDFG anglers caught 486 fish from the mainstem MFSR during 2016 angling surveys (Table 32). Westslope Cutthroat Trout accounted for 56% of our total catch (n = 270) while Rainbow Trout/steelhead accounted for 40% (n = 192) (Table 33, Figure 51). Mountain Whitefish, Northern Pikeminnow Ptychochelius oregonensis, suckers (various spp), Redside Shiners Richardsonius balteatus, Bull Trout, and trout hybrids accounted for the remaining 4% (Table 33, Figure 51). Angler catch per unit effort (CPUE) was 3.1 fish/hr in 2016 (Table 32, Figure 52). CPUE has fluctuated between 2.8 fish/hour and 5.8 fish/hour since 2009 when we began recording angling effort times (mean 3.9 fish/hr). Our ability to detect dramatic shifts in species composition in the MFSR will increase as we continue to collect this data.

Prior to catch-and-release regulations going into effect in 1972, proportion of Westslope Cutthroat Trout caught by project anglers greater than 300 mm TL averaged approximately 20%. Since the regulation change, this proportion has fluctuated annually, ranging from a low of 25% in 2007 to a high of 53% in 1987 (mean 38.5%) (Figure 53). In 2016, the proportion of Westslope Cutthroat Trout larger than 300 mm TL caught by project anglers was 47% (n = 127) (Figure 54). Annual fluctuation of this value could be partially attributed to differences in angler skill level, gear type, sample timing, river discharge, and water clarity. However, in relative terms, this value has remained stable since 2010 (Figure 53).

The relative increase in proportion of larger Westslope Cutthroat caught since catch- and-release regulations went in place can be attributed mainly to reduced total annual mortality and higher abundance for Westslope Cutthroat Trout. Growth rates for WCT have actually decreased since the period prior to catch-and-release regulations (Messner et al. 2017). However, more WCT are living to maximum age (~7 years) than prior to the regulation change. Prior to the change, mean annual survival was estimated at 32% (1959-1960) (Mallet 1963), and in 2015 we estimated mean annual survival at 60% (Messner et al. 2017).

148

Although Westslope Cutthroat Trout growth is slower in recent years than it was 50 years ago (Mallet 1963), catch rates are currently very high, and nearly half of WCT caught are greater than 300 mm, compared to only 20% before catch-and-release regulations were imposed. This has produced one of the highest quality trout fisheries in the Salmon Region at present time. Hopefully with maintaining this dataset, we can detect any major community shifts that would affect the quality of the fishery and address them early.

It is important to ensure project anglers are diligent with keeping accurate angling times logged for CPUE calculations. In 2016, it is likely that the reason we calculated one of our lowest CPUE values is because, although instructed to, some project anglers did not record angling times accurately. For example, if an anglers starts floating and fishing at 10 am, fishes sporadically for 20 minute periods at a time with 10 minutes breaks in between, and stops for lunch at noon, they did not fish for two hours. They only fished for an hour and 20 minutes, because of the breaks they took.

MANAGEMENT RECOMMENDATIONS

1. Continue annual monitoring of Westslope Cutthroat Trout, Rainbow Trout/Steelhead, and juvenile Chinook Salmon in all 28 main stem sites, 10 tributary sites, and 6 historical mainstem MFSR sites by snorkeling between the second week of July and the third week of August.

2. Continue monitoring angling catch rates (fish/hour) every year on the Middle Fork Salmon River to assess trends to provide up-to-date information for anglers, guides, and outfitters.

149

Table 31. Densities of salmonids observed during snorkel surveys in the MFSR drainage in 2016 (fish/100m2).

Rainbow Chinook Trout Cutthroat Brook Site Trout/ Salmon Bull Trout Whitefish Fry Trout Trout steelhead Parr Historical main stem sites (Corley) Little Creek GS 0.00 1.41 0.00 2.82 0.00 0.00 11.29 Mahoney 0.00 0.37 0.00 3.33 0.00 0.00 0.74 White Creek PB 0.00 0.00 0.00 0.17 0.00 0.00 1.08 Bernard Airstrip 0.00 0.45 0.15 0.76 0.00 0.00 0.91 Hancock Pool 0.00 0.00 0.00 0.00 0.00 0.00 1.81 Cliffside Pool 0.00 0.07 0.07 0.28 0.00 0.00 0.28 Mean 0.00 0.38 0.04 1.23 0.00 0.00 2.69 SE 0.00 0.24 0.03 0.65 0.00 0.00 1.90 Minimum 0.00 0.00 0.00 0.00 0.00 0.00 0.28 Maximum 0.00 1.41 0.15 3.33 0.00 0.00 11.29 Traditional main stem sites Boundary 7.93 2.76 18.61 7.24 0.00 0.00 3.79 Gardell’s 0.00 0.46 3.05 1.22 0.00 0.00 1.53 Velvet 0.00 20.79 11.95 3.12 0.00 0.00 1.56 Elkhorn 0.00 4.14 7.81 0.00 0.00 0.00 1.84 Sheepeater 0.00 1.88 0.00 0.00 0.00 0.00 2.50 Greyhound 0.00 0.21 0.00 1.93 0.00 0.00 5.37 Rapid R 0.00 7.94 0.00 6.52 0.00 0.00 7.66 Indian 0.00 0.00 0.24 4.87 0.00 0.00 4.26 Pungo 0.00 0.00 7.79 3.64 0.00 0.00 2.34 Marble Pool 0.00 0.47 2.11 3.64 0.12 0.00 6.34 Ski Jump 0.00 0.00 0.00 0.52 0.00 0.00 2.58 Lower Jackass 0.00 0.00 0.00 1.93 0.00 0.00 1.45 Cougar 0.00 0.00 0.37 0.37 0.00 0.00 0.00 Whitey Cox 0.00 0.73 0.00 3.99 0.00 0.00 5.99 Rock Island 0.00 2.66 0.00 2.66 0.00 0.00 0.61 Hospital Pool 0.00 0.00 0.00 2.69 0.00 0.00 0.99 Hospital Run 0.00 0.00 0.00 2.79 0.00 0.00 3.19 Tappan Pool 0.00 0.32 3.81 2.38 0.00 0.00 1.90 Flying B 0.00 0.22 0.22 1.33 0.00 0.00 0.89 Airstrip 0.00 0.45 0.00 0.91 0.00 0.00 0.91 Survey 0.00 0.00 0.00 0.61 0.00 0.00 1.21 Big Cr PB 0.00 2.87 1.06 0.57 0.00 0.00 0.33 Love Bar 0.00 0.00 0.00 0.37 0.00 0.00 0.56 Ship Island 0.00 0.17 0.00 3.14 0.00 0.00 1.49 Little Ouzel 0.00 0.96 0.24 0.00 0.00 0.00 0.48

150 Table 31 (continued)

Rainbow Chinook Trout Cutthroat Brook Site Trout/ Salmon Bull Trout Whitefish Fry Trout Trout steelhead Parr Otter Bar 0.00 1.60 0.00 1.17 0.00 0.00 1.02 Goat Pool 0.00 0.12 0.00 0.12 0.00 0.00 0.50 Goat Run 0.00 0.14 0.00 0.00 0.00 0.00 1.23 Mean 0.28 1.75 2.05 2.06 0.00 0.00 2.23 SE 0.29 0.79 0.85 0.38 0.00 0.00 0.39 Minimum 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Maximum 7.93 20.79 18.61 7.24 0.12 0.00 7.66 Traditional tributary sites Indian LOWER 0.00 4.20 0.42 0.42 0.00 0.00 0.14 Indian UPPER 0.00 1.05 0.84 0.00 0.00 0.00 0.00 Loon L1-Bridge 0.00 1.28 0.80 0.96 0.00 0.00 1.28 Loon L-2 Run 0.00 2.43 0.17 0.69 0.00 0.00 0.87 Camas L1 0.00 0.81 0.37 0.44 0.15 0.00 2.07 Camas UPPER 0.00 2.88 0.72 0.36 0.00 0.00 2.88 Marble Lower 0.48 0.12 2.76 0.12 0.00 0.00 0.00 Pistol L1 0.00 3.57 11.04 2.60 0.00 0.00 8.12 Pistol L2 0.00 5.91 2.05 0.23 0.00 0.00 2.05 Mean 0.05 2.47 2.13 0.65 0.02 0.00 1.93 SE 0.06 0.66 1.22 0.28 0.02 0.00 0.90 Minimum 0.00 0.12 0.17 0.00 0.00 0.00 0.00 Maximum 0.48 5.91 11.04 2.60 0.15 0.00 8.12

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Table 32. Summary of fish caught during angling surveys on the mainstem MFSR, 1959 to 2016.

RBT/ RS Total # of Total hours Year WCT STHD BLT MWF WCTxRBT BUTxEBT CHN EBT NPM SUC S fish of effort CPUE 1959 143 112 11 0 0 0 0 0 0 0 0 266 UNK n/a 1960 484 103 94 0 0 0 0 0 0 0 0 681 UNK n/a 1969a 166 0 0 0 0 0 0 0 0 0 0 166 UNK n/a 1975 158 109 11 4 0 0 0 0 0 0 0 282 57.5 4.9 1976 75 14 2 2 0 0 0 0 0 0 0 93 UNK n/a 1978 160 91 0 13 0 0 0 0 0 0 0 264 86.0 3.1 1979 139 112 0 0 0 0 0 0 0 0 0 251 UNK n/a 1990 735 339 2 0 0 0 0 0 0 0 0 1076 UNK n/a 1991 42 54 0 0 3 0 0 0 0 0 0 99 UNK n/a 1992 42 53 0 1 0 0 0 0 0 2 0 98 UNK n/a 1993 242 66 0 0 6 0 0 0 0 0 0 314 UNK n/a 1999 182 132 0 0 8 0 0 0 0 0 0 322 UNK n/a 2003 167 91 0 0 0 0 1 0 0 0 1 260 UNK n/a 2004 243 184 1 0 0 0 1 0 1 0 0 430 UNK n/a 2005 226 157 7 2 4 0 0 0 5 0 0 401 UNK n/a 2007 264 253 2 6 1 0 0 0 16 0 0 542 UNK n/a 2008 64 90 0 0 1 0 0 0 0 0 0 155 26.9 5.8 2009 340 230 2 4 8 0 0 1 14 0 2 601 166.0 3.6 2010 174 115 8 21 3 0 2 2 0 0 0 325 116.2 2.8 2011 109 47 0 6 0 0 0 0 0 0 0 162 42.0 3.9 2012 299 206 11 14 4 0 0 0 5 1 1 541 145.9 3.7 2013 200 195 1 6 1 1 3 0 9 0 0 416 102.0 4.1 2014 167 137 3 7 1 1 0 0 6 3 2 327 98.7 3.3 2015 214 179 3 12 10 0 29 0 8 0 0 455 104.9 4.3 2016 270 192 0 2 11 0 0 0 9 0 2 486 156.5 3.1 a Only WCT enumerated WCT=Westslope Cutthroat Trout, RBT/STHD=Rainbow Trout/Steelhead, BUT=Bull Trout, MWF=Mountain Whitefish, CHN=Chinook Salmon, EBT=Eastern Brook Trout, NPM=Northern Pikeminnow, SUC = Sucker spp., RSS=Redside Shiner. CPUE = fish/hr

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Table 33. Percentage of each salmonid species represented in total catch during angling surveys on the mainstem MFSR, 1959 to 2016. 1969 was omitted due to only enumerating WCT that year.

Year WCT RBT/STHD BUT EBT MWF CTxRBT BUTxEBT 1959 54% 42% 4% 0% 0% 0% 0% 1960 71% 15% 14% 0% 0% 0% 0% 1975 56% 39% 4% 1% 0% 0% 0% 1976 81% 15% 2% 2% 0% 0% 0% 1978 61% 34% 0% 5% 0% 0% 0% 1979 55% 45% 0% 0% 0% 0% 0% 1990 68% 32% 0% 0% 0% 0% 0% 1991 42% 55% 0% 0% 3% 0% 0% 1992 43% 54% 0% 1% 0% 0% 0% 1993 77% 21% 0% 0% 2% 0% 0% 1999 57% 41% 0% 0% 2% 0% 0% 2003 64% 35% 0% 0% 0% 0% 0% 2004 57% 43% 0% 0% 0% 0% 0% 2005 56% 39% 2% 0% 1% 0% 0% 2007 49% 47% 0% 1% 0% 0% 0% 2008 41% 58% 0% 0% 1% 0% 0% 2009 57% 38% 0% 1% 1% 0% 0% 2010 54% 35% 2% 6% 1% 0% 1% 2011 67% 29% 0% 4% 0% 0% 0% 2012 55% 38% 2% 3% 1% 0% 0% 2013 48% 47% 0% 1% 0% 0% 1% 2014 51% 42% 1% 2% 0% 0% 0% 2015 47% 39% 1% 3% 2% 0% 6% 2016 56% 40% 0% 0% 2% 0% 0% mean 57% 38% 1% 1% 1% 0% 0% WCT=Westslope Cutthroat Trout, RBT/STHD=Rainbow Trout/Steelhead, BUT=Bull Trout, MWF=Mountain Whitefish, CHN=Chinook Salmon, EBT=Eastern Brook Trout

153

Salmon River

Big Creek

Camas Creek

Marble Creek Indian Creek

Loon Creek

Pistol Creek

Middle Fork Salmon River

^^^^ Dagger Falls

Figure 48. Map of the Middle Fork Salmon River and its major tributaries, Idaho.

154

10.0 Westslope Cutthroat Trout 2015 8.0 2016

6.0

4.0

2.0

0.0 10.0 O. mykiss 8.0

6.0

4.0 ) 2 2.0

0.0

(fish/100m 10.0 Chinook Salmon parr 8.0

6.0 Fish density 4.0

2.0

0.0 10.0 Mountain Whitefish 8.0

6.0

4.0

2.0

0.0 Indian Velvet Pungo Airstrip Survey Cougar Elkhorn Rapid R Rapid Flying B Gardell’s Love Bar Love Otter Bar Ski Jump Mahoney Boundary Goat Run Big Cr PB Goat Pool Greyhound Ship Island Little Ouzel Whitey Cox Sheepeater Rock Island Rock Marble Pool White Creek… Tappan Pool Hospital Run Hospital Cliffside Pool Hospital Pool Hospital Hancock Pool Lower Jackass Little Creek GS Bernard Airstrip Downstream

Figure 49. Salmonid densities observed in mainstem MFSR snorkel transects in 2015 and 2016.

155

70%

60%

50%

40%

30%

20% % WCT > 300 mm TL 10%

Figure 50. Percentage of Westslope Cutthroat Trout greater than 300 mm TL observed during snorkel surveys in the mainstem MFSR, 1971 to 2016.

Other RBT/STHD WCT 100% 90% 80% 70% 60% 50% 40% 30% 20% Angler catch composition 10% 0%

Figure 51. Percentage of Rainbow Trout/Steelhead (RBT/STHD), Westslope Cutthroat Trout (WCT), and other species (Other) represented in total angler catch during angling surveys on the mainstem MFSR, 1959 to 2016.

156

7.0 6.0

5.0 4.0 3.0 2.0 CPUE (fish/hr) 1.0 0.0

Figure 52. Catch per unit effort (CPUE) (# of fish caught per angler hour) estimated from hook and line sampling on the Middle Fork of the Salmon River between 2008 and 2016. The gray dotted line represents the mean (3.9 fish per angler hour) CPUE estimated over this time period.

60%

50%

40%

30%

20%

% WCT > 300 mm TL 10%

Figure 53. Percentage of Westslope Cutthroat Trout greater than 300 mm TL caught during angling surveys on the Middle Fork Salmon River, 1959 to 2016.

157

40 35 30

25 20

# caught 15 10 5 0

TL (mm)

Figure 54. Length frequency histogram of Westslope Cutthroat Trout caught during angling surveys in 2016 on the Middle Fork Salmon River.

158

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Appendix A. Intercept (a) and slope (b) parameters for standard weight (Ws) equations, taken from Blackwell et al. (2000). ( ) = + (total length (mm)) ′ 퐿퐿퐿10 푊푠 푎 푏 ∗ 퐿퐿퐿10 Minimum Species Intercept (a) Slope (b) TL (mm) Source Brown Trout (lentic) -4.867 2.96 140 Milewski and Brown, 1994 Cutthroat Trout (lotic) -5.192 3.086 130 Kruse and Hubert, 1997 Cutthroat Trout (lentic) -5.189 3.099 130 Kruse and Hubert, 1997 Lake Trout -5.681 3.246 280 Piccolo et al., 1993 Mountain Whitefish -5.086 3.036 140 Rogers et al., 1996 Tiger Muskellunge -6.126 3.337 240 Rogers and Koupal, 1997 Northern Pikeminnow -4.886 2.986 250 Parker et al., 1995 Rainbow Trout (lentic) -4.898 2.99 120 Simpkins and Hubert, 1996 Rainbow Trout (lotic) -5.023 3.024 120 Simpkins and Hubert, 1996 Smallmouth Bass -5.329 3.2 150 Kolander et al., 1993 White Sturgeon -5.795 3.232 700 Beamesderfer, 1993

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Appendix B. Bathymetric maps for select high mountain lakes surveyed in 2016. Challis Creek Lake #1.

164

Appendix B. (continued) Challis Creek Lake #2.

165

Appendix B. (continued) Challis Creek Lake #3.

166

Appendix B. (continued) Hoodoo Lake.

167

Appendix B. (continued) Crater Lake.

168

Appendix B. (continued) Ocalkens Lake #1.

169

Appendix B. (continued) Ocalkens Lake #2.

170

Appendix B. (continued) Chamberlain Lake #7.

171

Appendix B. (continued) Castle View Lake.

172

Appendix B. (continued) Heart Lake.

173

Appendix B. (continued) Honey Lake.

174

Appendix B. (continued) Hope Lake.

175

Appendix C. Bathymetric map of Wallace Lake, 2016.

176

Appendix D. Bathymetric map of Buster Lake, 2016.

177

Appendix E. Bathymetric map of Jimmy Smith Lake, 2016.

178

Appendix F. Wild trout redd count trend transect coordinates and lengths.

Start End

Year Latitude Longitude Latitude Longitude Length Species/ Transect established (°N) (°W) (°N) (°W) (km) Rainbow Trout

Big Springs Creek - Tyler 1994 44.70896 113.39917 44.72855 113.43430 3.4 Big Springs Creek - Neibaur 1994 44.70047 113.38436 44.70896 113.39917 4.5 Upper Lemhi River 1994 44.68689 113.36273 44.69945 113.37074 3.0 Bull Trout

Alpine Creek - upper 1998 43.90705 114.93078 43.90357 114.94457 1.5 Alpine Creek - lower 2010 43.89707 114.91327 43.90245 114.92246 1.5 Fishhook Creek - upper 1998 44.13706 114.96703 44.13472 114.97622 1.0 Fishhook Creek -lower 2008 44.14882 114.93716 44.13992 114.96205 3.5 Fourth of July Creek 2003 44.04112 114.75831 44.05039 114.69165 5.0 Hayden Creek 2010 44.70624 113.73430 44.37053 113.75771 2.5 Bear Valley Creek - upper 2007 44.78332 113.75496 44.79685 113.80820 4.7 Bear Valley Creek - lower 2002 44.77624 113.74259 44.78332 113.75496 1.7 East Fork Hayden Creek 2002 44.72984 113.67145 44.72438 113.66671 1.5

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Prepared By: Approved By: IDAHO DEPARTMENT OF FISH AND GAME

Jordan Messner Jeff Dillon Regional Fisheries Biologist State Fishery Manager

Jon Hansen James P. Fredericks Regional Fisheries Biologist Chief of Fisheries

Brent Beller Senior Fisheries Technician

Greg Schoby Regional Fisheries Manager

180