s 639.3755 F2fsu 2001 Fish Surveys of the Upper South Fork Judith River and its Tributaries Conducted during 2000 Bradley B. Shepard Montana Fish, Wildlife and Parks and Montana Cooperative Fishery Research Unit 1400 South 19'^ Bozeman, Montana 59718 y October 2001 Soulli Kork.fiidilli 2000 Table of Contents Table of Contents ii List of Tables ii List of Figures iii Executive Summary v Introduction 1 Study Area 1 Methods 1 Results 5 Big Hill Creek 5 Bluff Mountain Creek 15 Cabin Creek 18 Cross Creek 21 Deadhorse Creek 22 Russian Creek 24 South Fork Judith River 28 Smith Creek 31 Discussion 33 Fish Distribution and Abundance 33 Recommendations for Conservation of Westslope Cutthroat Trout 34 Acknowledgements 34 References 34 List of Tables Table 1. Catch of westslope cutthroat trout (WCT) and rainbow trout (RB) per electrofishing pass, estimated number per section (standard error; S.E.), and section length (m) by stream, stream kilometer (Km) and date during 2000 in the upper South Fork Judith River 6 Table 2. Average length and weight (ranges) of fish captured during fish sampling in the upper South Fork Judith River and its tributaries by stream and stream kilometer 7 Table 3. Streambed composition, frequency of small (< 150 mm) and large (>= 150 mm) in- channel and cross-channel woody debris per km, and square meters of spawning habitat per km by stream, section, and date 1 1 Table 4. Total length (m), average length (m), average width (m), average depth (cm), and average volume (cubic meters) of each habitat type and average thalweg depth (cm) and residual pool volume (cubic meters) by stream and section 12 Table 5. Rankings (0 = none or lowest; to 9 = highest) of instream cover, bank cover, bank stability, and pool quality by stream, section, and date 15 Page ' ii Su'jjh Kork.ludith 2000 Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure List of Figures 1 . Map of upper South Fork Judith River drainage showing locations of thermographs, sites of fish abundance sampling (coded by fish species observed or captured), and stream kilometers (upstream from mouth) during 2000 2 2. Map of streams sampled in upper South Fork Judith River drainage showing stream names and sample sites, by type of population abundance information collected 3 3. Average, minimum, and maximum water temperatures in Big Hill Creek immediately below the unnamed tributary during the summer of 2000 5 4. Length frequencies of westslope cutthroat trout captured in Big Hill Creek during 2000 6 5. Average, minimum, and maximum water temperatures in Bluff Mountain Creek just above its mouth during the summer of 2000 16 6. Relative abundance (number of fish 75 mm and longer captured on the first electrofishing pass per 100 m of stream length) for westslope cutthroat (WCT), brook (EBT), and rainbow and rainbow/cutthroat trout hybrids (RB + HB) in four sections of Bluff Mountain Creek and three sections of an unnamed tributary by stream kilometer. 17 7. Length frequencies for westslope cutthroat trout in Bluff Mountain Creek (by stream kilometer up from mouth) and in three sections in a major unnamed tributary (TRIB) during July 2000 18 8. Average, minimum, and maximum water temperatures in Cabin Creek just above its mouth during the summer of 2000 19 9. Relative abundance (number of fish 75 mm and longer captured on the first electrofishing pass per 100 m of stream length) for westslope cutthroat (WCT) and rainbow and cutthroat/rainbow trout hybrids (RB + HB) in eight sections of Cabin Creek by stream kilometer 20 1 0. Length frequencies for westslope cutthroat trout in Cabin Creek (by stream kilometer up from mouth) during late June (km 1.6 and 3.2) and late July (km 0.8, 2.4, and 4.0 to 6.4) 2000 20 1 1 . Length frequencies for westslope cutthroat trout in Cross Creek at stream kilometer 0.8 during late July 2000 21 12. Average, minimum, and maximum water temperatures in Deadhorse Creek just above its mouth during the summer of 2000 22 13. Relative abundance (number of fish 75 mm and longer captured on the first electrofishing pass per 1 00 m of stream length) for westslope cutthroat trout in six sections of Deadhorse Creek by stream kilometer..... 23 14. Length frequencies for westslope cutthroat trout in six sections of Deadhorse Creek (by stream kilometer) during late July 2000 24 15. Average, minimum, and maximum water temperatures in Russian Creek just below the South Fork Road crossing (top) and just above its mouth (bottom) during the summer of 2000 26 16. Relative abundance (number of fish 75 mm and longer captured on the first electrofishing pass per 100 m of stream length) for westslope cutthroat trout during 2000 in two sections of Russian Creek (left) and an unnamed tributary to Russian Creek (right) by stream kilometer. Page iii 27 South Fork Judith 2000 Figure 17. Length frequencies for westslope cut throat trout in two sections of Russian Creek (by stream kilometer) and its major unnamed tributary (Trib) during late June 2000. 27 Figure 18. Average, minimum, and maximum water temperatures in the South Fork Judith River below the mouths of Bluff Mountain Creek (top), Big Hill Creek (middle), and Corral Creek (bottom) during the summer of 2000 29 Figure 19. Relative abundance (number of fish 75 mm and longer captured on the first electrofishing pass per 100 m of stream length) for westslope cutthroat trout (WCT) and rainbow trout (RB + HB) during 2000 in nine sections of the South Fork Judith River by stream kilometer 30 Figure 20. Length frequencies for westslope cut throat trout in nine sections of the South Fork Judith River (by stream kilometer) during late June 2000 31 Figure 21. Average, minimum, and maximum water temperatures in Smith Creek just above its mouth during the summer of 2000 32 Figure 22. Frequencies of relative abundance (number of fish 75 mm and longer per 100 m of stream length) for westslope cutthroat trout in allopatry in 489 sample sections that were a minimum of 50 m long within the streams of the upper Missouri River basin and a few streams in the upper Clark Fork basin of Montana 33 Pai'c IV South Fork Judith 2000 Executive Summary This report summarizes fish survey information collected in the upper South Fork Judith River drainage in 2000. The purpose of the survey was to document the status of westslope cutthroat trout, Oncorhynchus clarki lewisi (WCT), within the upper South Fork drainage to help direct conservation efforts for WCT in this drainage. WCT were widely distributed in the upper South Fork Judith River basin and they were generally abundant where they occurred. Relative abundance for WCT generally ranged from 20 to 50 fish 75 mm and longer per 100 m of stream length and was as high as nearly 70 WCT per 100 m of stream. WCT in the South Fork Judith basin were found as far up into headwaters as stream size would support fish. Normative rainbow trout or fish identified as hybrids occupied the lower portions of Bluff Mountain and Cabin creeks, most of Smith Creek, and were also found in the South Fork Judith as far upstream as river km 19.3, just above Smith Creek. I am unsure how numerous rainbow trout are in the South Fork or how long they have been present in the upper portions of the basin, but their presence so far up the basin is a major concern for WCT conservation and restoration. The upper South Fork Judith River basin above Bluff Mountain Creek represents a good opportunity to restore a moderately large connected stream and river system for WCT. This area contains approximately 60 km of stream with approximately 40 km now inhabited by fish. Any attempt to conserve WCT in the upper South Fork will require construction of a fish barrier to eliminate the continuing invasion of brook and rainbow trout into the upper basin. Unfortunately, rainbow trout have already made their way up into the basin at least as far as Smith Creek. It also appears that WCT populations in several tributaries, including Russian and Cabin creeks, have already been slightly hybridized with either rainbow trout or Yellowstone cutthroat trout based on earlier genetic sampling. Fin clips taken for PfNE genetic analyses during this study will provide more conclusive evidence for the genetic status of all WCT populations. Lastly, fish identified as either rainbow or hybrids between rainbow and WCT were captured in Bluff Mountain, Cabin, and Smith creeks, as well as the South Fork Judith. Thus, several decisions will have to be made regarding barrier location(s) and either management of existing slightly hybridized populations as conservation populations that could not be used as donors for other waters, or removal of existing hybridized populations and replacing these existing hybrid populations using genetically pure sources from other streams in the basin, either by natural dispersal or by active human intervention. P;)uc V Soiitli 1‘orlv .Midilh 2000 Introduction The Montana Cooperative Fishery Research Unit and Montana Fish, Wildlife and Parks (FWP) was asked by Region 4 of FWP and the Lewis and Clark National Forest to conduct fish surveys in waters of the upper South Fork Judith River, Montana to document the presence and status of westslope cutthroat trout {Oncorhynchus clarki lewisi; WCT). These surveys were done during 2000 in cooperation with Region 4 of FWP and the Lewis and Clark National Forest to develop a conservation plan for westslope cutthroat trout in the upper South Fork. Study Area The streams surveyed included Corral, Big Hill, Russian, Deadhorse, Cross, Cabin, Smith and Bluff Mountain creeks, as well as the main South Fork Judith River down to the mouth of Bluff Mountain Creek (Figure 1). Streams in the upper South Fork supported WCT, brook trout (Salvelinus fontinalis), and rainbow trout {Oncorhynchus mykiss), while the South Fork also supported mountain whitefish {Prosopium williamsoni) and mottled sculpin (Coitus hairdi). Methods A systematic sampling scheme was employed to estimate both the relative abundance and distribution of fishes and to quantify stream habitat characteristics. Sample sections ranging from 45 to 135 m were surveyed at a frequency of approximately every 0.8 km (0.5 mile) of stream length by single-pass electrofishing with backpack Smith-Root electrofishers (Models SR-12BP, SR-15B). At approximately 3.2 km (2 mile) intervals we conducted two-pass depletion population estimates (Van Deventer and Platts 1985; Figure 2). Population estimates were not made when few or no fish were captured during the first electrofishing pass. Sample section lengths were usually at least 20 times, with most at least 30 times, the average wetted stream width. Lyons (1992) found that when stream lengths of 35 times the mean wetted width were sampled with a towed electrofishing unit, all species of fish in fish communities in warm water streams of Wisconsin were generally captured. Sample sites were referenced by mile above the stream’s mouth, and later converted to kilometers above the mouth, and by latitude and longitude obtained from a global positions system (GPS; Garmin 12XL). Field GPS locations were input into an ARCVIEW (Version 3.2; 1999; Environmental Systems Research Institute, Inc.) event theme and projected on I ; 100,000 stream hydrography layers. The field GPS locations were corrected to overlay the hydrography layer and stream kilometer locations when discrepancies existed between field GPS and mapped locations (Figures 1 and 2). Length (total length in mm) and weight (gm) were recorded for all captured salmonids. For two- pass estimates to provide reasonable results, we assumed that field calculated probabilities of capture (calculated as 1- (C2/C1); where Ci= number captured on the first pass, and C2 = number captured on second pass) had to be 0.80 or higher (c.f , White et al. 1982; Riley and Fausch 1992). If field calculated probabilities of capture were less than 0.80 after two passes, additional electrofishing passes were usually made. Population estimates were calculated using a maximum likelihood estimator within the MICROFISH program (Van Deventer and Platts 1985) Pagf - 1 Digitized by the Internet Archive in 2017 with funding from Montana State Library https://archive.org/details/fishsurveysofupp2001shep 13.0 Figure 1 . Map of upper South Fork Judith River drainage showing locations of themiographs, sites of fish abundance sampling (coded by fish species observed or captured), and stream kilometers (upstream from mouth) during 2000. / South Fork .ludith 2000 by species for fish 75 mm and longer. Population estimates of fish 75 mm and longer were also standardized per 100 m of stream length. Relative fish abundance was calculated as the number of fish 75 mm and longer per 100 m of stream length captured in the first electro fishing pass. Due to its large size, the South Fork Judith River below Deadhorse Creek could not be efficiently sampled using backpack electrofishers. Consequently, no sampling was conducted in the South Fork from Deadhorse Creek down river. Fin samples from westslope cutthroat trout were taken for genetic analysis. Where possible, a sub-sample of westslope cutthroat trout captured at each sample site within a stream was represented in the genetic samples. The University of Montana Wild Salmon and Trout Genetics Laboratory, using Paired Interspersed Nuclear DNA Element-PCR (PINE) tests, will determine genetic status from these fin clips; however, results were not available at the time this report was completed. A listing of all tissue samples taken for genetic analyses and submitted to the Wild Salmon and Trout Genetics Laboratory are included in Appendix A. Site level habitat surveys were conducted at 3.2 km (2 mile) intervals in sample sections where fish population estimates were made. The following information was collected for each macrohabitat type (pool, riffle or run) within a sample section: length of the macrohabitat type; wetted and channel width (width of normal bank-full channel), measured at a single location which represented an average width and depth of a habitat type; average depth, estimated by taking three depth measurements at equal distances across the single cross section where width was measured and dividing by 4; average maximum pool depth using 4 maximum (thalweg) depths were measured longitudinally down the channel and averaged; residual pool depth and volume were estimated using the average maximum depth of the pool minus the maximum depth of the adjacent downstream habitat unit, along with surface area of the pool for volume (Lisle 1987). Over the entire sample section the following information was collected: surface area of suitable spawning habitat (defined as patches of substrate dominated by material 10 to 30 mm which cover at least 0.5 m ); number of large (>15 cm in diameter) and small (£ 15 cm in diameter) woody debris within the stream channel; number of large and small woody debris which span the stream channel; qualitative assessment of stream bank condition that ranked relative stability from low to high (and described the composition of the stream bank and the source of instability); qualitative assessment of instream cover which ranked the relative amount of instream cover from a low to high proportion of water volume with cover; qualitative assessment of bank overhead cover which ranked the amount of the water’s surface which is covered or shaded; estimate of surficial streambed composition by size class in percentage by class; qualitative assessment of relative use of riparian areas by livestock or wildlife. Continuously recording digital thermographs (models WTA08, Onset Computer Corporation, Pocasset, Massachusetts) were used to record water temperatures in Big Hill, Bluff Mountain, Cabin, Deadhorse, and Russian creeks and the South Fork (Figure 1). Model WTA08 thermographs were set to record temperatures every half hour. During mid-July thermographs were placed in well-mixed pools, shielded from direct solar radiation, from late June to mid- July and left to record stream temperatures until late September. Daily stream temperatures were summarized into daily average, maximum, and minimum recorded temperatures and graphed for each thermograph site by year. Page - 4 South J orit .liulilli 21)0(1 Results Big Hill Creek Big Hill Creek is a small tributary to the South Fork Judith River, entering the South Fork at about stream kilometer (km) 27.6. Fish population and habitat surveys were conducted in Big Hill Creek just downstream from the South Fork Road, at the confluence with a small tributary to Big Hill Creek. This small tributary did not support fish and was dry at the end of the summer 2000 sampling period. Conifers dominate the riparian vegetation in this reach and stream habitat was generally excellent. No dispersal barriers were observed, although the culvert at the South Fork Road may cause passage problems during high flows. Average water temperatures in Big Hill Creek remained below 12 C, while maximum temperatures remained below 16 C, during the summer of 2000 (Figure 3). O o 3 *-• (0 k. o Q. 0) Date Figure 3. Average, minimum, and maximum water temperatures in Big Hill Creek immediately below the unnamed tributary during the summer of 2000. Big Hill Creek supported only WCT. A genetics sample of 10 WCT taken by Mike Enk of the Lewis and Clark National Forest in August 1995 was 100% pure WCT based on allozymes analysis (Tews et al. 2000). We collected fins from 25 WCT in June 2000 for genetic testing using the PINE test (Appendix A). No sculpins were observed. A 100 m sample section located at stream kilometer (km) 0.8 supported an estimated 1 1 (SE not calculated due to all fish captured on pass 1), 32 (SE: 0.6), and 1 1 (SE not calculated due to all fish captured on pass 1) westslope cutthroat trout <75 mm, 75-149 mm, and 150 mm and longer, respectively (Table 1 and Appendix B). Captured westslope cutthroat trout averaged 109 mm (range: 46-217; Table 2; Figure 4). Page - - South Fork .hidith 2000 Table 1 . Catch of westslope cutthroat trout (WCT) and rainbow trout (RB) per electrofishing pass, estimated number per section (standard error; S.E.), and section length (m) by stream, stream kilometer (Km) and date during 2000 in the upper South Fork Judith River. Stream Km Section Date length (m) Species Catch per pass 1 2 Estimate S.E. BIG HILL CR 0.8 6/12/00 100 WCT 40 3 43 0.5 BLUFF MOUNTAIN CR 1.6 7/21/00 100 WCT 29 5 34 1.0 CABIN CR 3.2 6/25/00 75 WCT 40 3 43 0.5 CROSS CR 0.8 7/25/00 90 WCT 31 3 34 0.6 DEADHORSE CR 3.2 7/25/00 75 WCT 20 7 29 3.0 RUSSIAN CR-W FK TRIB 0.4 6/14/00 100 WCT 23 5 28 1.1 S FK JUDITH R 19.3 6/15/00 135 WCT 71 6 77 0.7 RB 2 0 2 0.0 S FK JUDITH R 22.5 6/15/00 100 WCT 57 8 64 1.0 S FK JUDITH R 25.7 6/13/00 105 WCT 50 4 54 0.6 1 £ Ll. 0 50 100 150 200 Length Class (mm) 250 Figure 4. Length frequencies of westslope cutthroat trout captured in Big Hill Creek during 2000. A habitat survey conducted at km 0.8 found that the streambed in Big Hill Creek at this location was comprised primarily of sand and gravels with sand and silt making up about 35% of the streambed’s surface (Table 3). Small and large woody debris was relatively abundant in the stream channel with over 25% of the large debris crossing the entire wetted channel (Table 3). Spawning habitat appeared to be relatively abundant and was likely not limiting fish recruitment (Table 3). Pool habitats made up slightly over 40% by number and 30% by length of all habitat types (Table 4). Wetted width averaged 1.4 m and depth averaged 14. 7 cm (Table 4). Pool volumes averaged about 0.7 m^. Pools had an average maximum depth of 18.5 cm and residual volume of 0.3 m^. Instream and bank cover, bank stability, and pool quality were all ranked l-‘age - 6 South Fork .luditli 2()()U Table 2. Average length and weight (ranges) of fish captured during fish sampling in the upper South Fork Judith River and its tributaries by stream and stream kilometer. STREAM Length Weight Km Date Species n (range) (range) BIG HILL CR 0.80 06/12/2000 WCT 54 108.8 24.9 (46-217) (1-314) BLUFF MOUNTAIN CR 0.80 07/24/2000 WCT 26 121.0 27.0 (72-212) ( 3- 99) 1.61 07/21/2000 RB 3 161.7 38.0 ( 147- 182) ( 34- 42) 07/21/2000 EBT 3 205.0 ( 197-212) - 07/21/2000 WCT 38 145.1 30.7 ( 66- 235) ( 2- 72) 2.41 07/24/2000 WCT 15 131.3 26.0 ( 70- 178) ( 4- 62) 4.02 07/26/2000 WCT 10 136.6 (91- 174) - BLUFF MOUNTAIN CR 0.80 07/24/2000 EBT 1 185.0 ( 185- 185) - 07/24/2000 WCT 12 162.8 ( 90- 223) - 1.61 07/24/2000 WCT 9 141.2 ( 85- 203) - 2.41 07/24/2000 WCT 2 148.5 ( 138- 159) - South Fork Judith 20011 Table 2. (continued). STREAM Length Weight Km Date Species n (range) (range) CABIN CR 0.80 07/26/2000 WCT 18 128.3 30.8 ( 54- 223) (3- 110) 07/26/2000 HB 1 192.0 75.0 ( 192- 192) ( 75- 75) 1.61 06/25/2000 WCT 10 133.2 29.5 (64- 191) ( 5- 66) 2.41 07/25/2000 WCT 19 125.2 23.3 ( 51- 187) (5-61) 3.22 06/25/2000 WCT 43 138.1 27.3 (90-215) ( 7- 120) 4.02 07/26/2000 WCT 24 143.8 33.4 ( 118- 206) ( 19- 79) 4.83 07/26/2000 WCT 41 124.1 23.0 (66- 190) ( 5- 67) 5.63 07/26/2000 WCT 35 135.5 29.8 ( 59- 202) (3-68) 6.44 07/26/2000 WCT 2 173.5 59.0 ( 147- 200) ( 38- 80) CROSS CR 0.80 07/25/2000 WCT 35 133.6 25.9 ( 59- 188) ( 4- 53) DEADHORSE CR 0.80 07/25/2000 WCT 8 159.9 48.5 ( 65- 205) (3-81) 1.61 07/25/2000 WCT 15 159.9 43.3 ( 113-226) ( 12- 82) Page K S(-uil! lork ,)n(iini 2000 Table 2. (continued). STREAM Length Weight Km Date Species n (range) (range) 2.41 07/25/2000 WCT 23 130.8 30.2 ( 66- 186) (5- 68) 3.22 07/25/2000 WCT 28 139.2 ( 61-208) - 4.02 07/25/2000 WCT 18 124.3 ( 60- 195) - 4.83 07/25/2000 WCT 7 83.0 ( 56- 136) RUSSIAN CR 0.80 06/14/2000 WCT 6 129.3 22.0 ( 104- 180) ( 10-53) 2.41 06/14/2000 WCT 22 126.9 27.2 ( 65- 245) (3- 180) RUSSIAN CR-W FK TRIB 0.40 06/14/2000 WCT 33 116.7 19.9 ( 57- 199) ( 3- 66) 1.20 06/14/2000 WCT 9 147.4 33.1 ( 93- 197) ( V- 63) S FK JUDITH R 19.31 06/15/2000 WCT 77 165.4 84.5 ( 81-292) ( 2- 475) 06/15/2000 RB 2 230.0 230.0 (214- 246) ( 200- 26 22.53 06/15/2000 WCT 69 138.8 36.7 ( 55- 229) (2- 106) P<\ge - 0 South Fork Jiuiith 2000 Table 2. (continued). STREAM Length Weight Kni Date Species n (range) (range) 23.33 06/13/2000 WCT 34 162.8 45.4 ( 93- 227) ( 9- 99) 24.14 06/13/2000 WCT 17 152.1 49.1 (98-211) ( 11- 118) 24.94 06/13/2000 WCT 34 153.4 42.5 (64-214) ( 6- 84) 25.74 06/13/2000 WCT 55 157.1 61.1 ( 62- 227) (4- 170) 26.55 06/13/2000 WCT 45 124.1 49.3 ( 50- 246) ( 5- 192) 27.35 06/13/2000 WCT 49 133.7 31.6 (53-217) ( 2- 97) 28.32 06/12/2000 WCT 6 156.0 44.5 ( 121- 177) ( 28- 57) SMITH CR 0.80 07/25/2000 WCT 13 132.3 26.2 (67-215) ( 2- 86) 07/25/2000 HB 4 153.0 43.5 ( 118- 205) ( 14- 97) V-dv.c 10 Table 3. Streambed composition, frequency of small (< 150 mm) and large (>= 150 mm) in-channel and cross-channel woody debris per km, and square meters of spawning habitat per km by stream, section, and date. ■S ' C OJ ? & o. iS 5. cr o 00 (U s: o; o SO K3 o O o rn o o r--* e o^ fN oo r-- (N c/^ o i* o u 'O e- M South iork .liidilh 2000 Table 5. Rankings (0 = none or lowest; to 9 = highest) of instream cover, bank cover, bank stability, and pool quality by stream, section, and date. STREAM Km Date Instream cover Bank cover Bank stabilitv Pool aualitv Riparian use BIG HILL CR 0.8 06/12/2000 8 BLUFF MOUNTAIN CR 9 9 7 1 1.6 07/21/2000 4 7 6 3 1 CABIN CR 3.2 06/25/2000 7 8 8 7 3 CROSS CR 0.8 07/25/2000 5 6 7 7 3 DEADHORSE CR 3.2 07/25/2000 8 RUSSIAN CR-W FK TRIB 6 7 6 2 0.4 06/14/2000 6 7 5 4 3 S FK JUDITH R 19.3 06/15/2000 4 - - - - 22.5 06/15/2000 7 7 7 5 2 25.7 06/13/2000 7 8 9 6 1 high, while riparian use was rated as low (Table 5). Instream cover was primarily provided by woody debris. Bluff Mountain Creek Bluff Mountain Creek is a 6.5 km-long tributary to the South Fork Judith. The upper 2 km of stream has a low to moderate gradient and flows through dense lodge pole pine forest. Fish habitat is marginal and no fish were captured above stream km 4.8. Below km 4.8, the valley bottom is much more confined, the channel gradient increases, and the quality of pool habitats improves. Many high quality pools are formed at the base of bedrock outcroppings. The headwaters of Bluff Mountain Creek had previously been logged, but the riparian zone was not harvested. No barriers to fish dispersal were observed in Bluff Mountain Creek; however. Tews et al. (2000) identified that a series of cascades may be a barrier to upstream fish movement. Due to its confined valley bottom and numerous bedrock outcroppings, there are many potential barrier construction sites. Bluff Mountain Creek has one unnamed tributary that enters between stream km 2.5 and 3.0. Fish distribution and relative abundance was assessed at stream kilometers 0.8, 1.6, 2.4, and 4.0 and fish population estimate and habitat surveys were conducted at km 1 .6. Average water temperatures in lower Bluff Mountain Creek remained below 13 C, while maximum water temperatures remained below 15 C (Figure 5). Pase - 15 South Fork Judith 2000 O (D k. 3 4-> ra k. 0) Q. E (D n E 3 0 South Fork Judith ^19.3 □22.5 ^23.3 024.1 ^24.9 025.7 026.5 027.4 ■ 28.3 50 100 150 200 Length Class (mm) 250 300 Figure 20. Length frequencies for westslope cut throat trout in nine sections of the South Fork Judith River (by stream kilometer) during late June 2000. 25% by number and 18% by length at km 22.5; and 38% by number and 31% by length at km 25.7 (Table 4). Wetted width averaged 5.6, 4.0, 2.6 m and depths averaged 35, 26, and 24 cm in sample sections at km 19.3, 22.5, and 25.7 illustrating how the South Fork became much smaller near its headwaters (Table 4). Pools were relatively large, with averaged volumes of from 6.9 to 22.7 m^, in a downstream direction. Residual pool volumes at km 22.5 and 25.7 were 5.9 and 2.5 m^, respectively. Average depths of pools ranged from 33 to 44 cm. Ranks were not assigned to bank cover, bank stability, pool quality, or riparian use at km 19.3. Instream cover was ranked as moderately low at km 19.3, but was moderately high at both km 22.5 and 25.7 (Table 5). Bank cover and stability were high at km 22.5 and 25.7. Pool quality was moderate and riparian use low at both km 22.5 and 25.7. Smith Creek Smith Creek is about 4.7 km long and enters the South Fork from the north near river km 18.8 (Figures 1 and 2). A large unnamed tributary enters Smith Creek from the west at about km 1 .5 or 0.7 km below the South Fork Road. Two old beaver ponds just above the South Fork Road impound the creek. Above these ponds the channel gradient is moderate and the valley is comprised primarily of a lodgepole pine forest and is relatively unconfmed. The channel above the ponds was believed too small to support fish and improper livestock grazing had led to poor channel conditions. From these ponds downstream the channel gradient increases and the valley Pane - 3 ! South Fork Judith 2000 becomes much more confined. The streambed contained a high proportion of fine sediments both above and below the South Fork Road. Vegetation along the lower portion of the stream was also dominated by lodgepole pine forest. During the summer of 2000 Smith Creek’s channel was nearly dry from the beaver ponds down to about stream kilometer 0.5. Riffle habitats were dry, but some water remained in pool habitats. Fish were observed at high densities in those pools that had water. The field crew believed that some pools that retained water might retain enough water through the summer to provide a refuge and allow some of these fish to survive. Below stream kilometer 0.5 Smith Creek progressively regained surface water flow and aquatic habitat condition improved. A thermograph placed near the mouth of Smith Creek recorded relatively cool water temperatures throughout the summer of 2000 with average daily temperatures seldom exceeding 14 C and maximum temperatures seldom exceeding 17 C (Figure 21). Figure 21 . Average, minimum, and maximum water temperatures in Smith Creek just above its mouth during the summer of 2000. Smith Creek supports WCT and fish that appeared to be hybrids. A total of 13 WCT and 4 fish identified as hybrids were captured in a single 50 m section located at km 0.8. As mentioned above, this section was within the portion of stream that was nearly dry. Consequently, all fish were captured in the few pool habitats that had retained water within the section. Captured WCT averaged 132 mm while hybrids averaged 153 mm (Table 2). A cursory sample of the stream in 1 999 near the South Fork Road found a few fish in this location that also appeared to be hybrids (personal communication, Anne Tews, Montana, Fish, Wildlife and Parks, Lewistown, Montana). Huge - 32 South I (trk JiuJidi 200(t Discussion Fish Distribution and Abundance WCT were widely distributed in the upper South Fork Judith River basin and they were generally abundant where they occurred. Relative abundance for WCT generally ranged from 20 to 50 fish 75 mm and longer per 100 m of stream length and was as high as nearly 70 WCT per 100 m of stream. Median relative abundance for WCT 75 mm and longer was 16.9 per 100 m in 489 sample sections in the upper Missouri River basin where WCT existed in allopatry and where at least 50 m of stream length was sampled (Figure 22). WCT in the South Fork Judith basin were generally distributed as far up into headwaters as stream size would support fish. Normative rainbow trout occupied the lower portions of Bluff Mountain and Cabin creeks, most of Smith Creek, and were also found in the South Fork Judith as far upstream as river km 19.3, just above Smith Creek. I am unsure how numerous rainbow trout are in the South Fork or how long they have been present in the upper portions of the basin, but their presence so far up the basin is a major concern for WCT conservation and restoration. There was no obvious reason for the presence of brook trout in Bluff Mountain Creek and their absence elsewhere in the upper drainage. Figure 22. Frequencies of relative abundance (number of fish 75 mm and longer per 100 m of stream length) for westslope cutthroat trout in allopatry in 489 sample sections that were a minimum of 50 m long within the streams of the upper Missouri River basin and a few streams in the upper Clark Fork basin of Montana. South Fork Judith 2000 Recommendations for Conservation of Westslope Cutthroat Trout The upper South Fork Judith River basin above Bluff Mountain Creek represents a good opportunity to restore a moderately large connected stream and river system for WCT. The upper South Fork basin from Bluff Mountain Creek upstream contains approximately 60 km of stream with approximately 40 km now inhabited by fish. Any attempt to conserve WCT in the upper South Fork will require construction of a fish barrier to eliminate the continuing invasion of brook and rainbow trout into the upper basin. Unfortunately, rainbow trout have already made their way up into the basin at least as far as Smith Creek. It also appears that WCT populations in several tributaries, including Russian and Cabin creeks, have already been slightly hybridized with either rainbow trout or Yellowstone cutthroat trout based on earlier genetic sampling. Fin clips taken for PfNE genetic analyses during this study will provide more conclusive evidence for the genetic status of all WCT populations. Lastly, fish identified as either rainbow or hybrids between rainbow and WCT were captured in Bluff Mountain, Cabin, and Smith creeks, as well as the South Fork Judith. Thus, several decisions will have to be made regarding barrier location(s) and either management of existing slightly hybridized populations as conservation populations that could not be used as donors for other waters, or removal of existing hybridized populations and replacing these existing hybrid populations using genetically pure sources from other streams in the basin, either by natural dispersal or by active human intervention. Acknowledgements Matt Sloat and David Barnes collected most of the field data and entered that data into computer data files. Mike Enk of the Lewis and Clark National Forest and Anne Tews of Montana Fish, Wildlife and Parks and their field crews assisted with data collection, logistics, background information, and valuable suggestions. Dr. Robert White and Dee Topp of the Montana Cooperative Fishery Research Unit at Montana State University provided administrative and logistical support. References Environmental Systems Research Institute, Inc. 1999. Arcview GIS program. Version 3.2. Lisle, T.E. 1987. Using residual depths to monitor pool depths independently of discharge. Research Note PSW-394, USDA Forest Service, Pacific Southwest Forest and Range Experiment Station, Berkley, California. Lyons, J. 1992. The length of stream to sample with a towed electrofishing unit when fish species richness is estimated. North American Journal of Fisheries Management 12:198- 203. Riley, S. C. and K. D. Fausch. 1992. Underestimation of trout population size by maximum- likelihood removal estimates in small streams. North American Journal of Fisheries Management 12:768-776. {’age - 31 Soiidi 1 ork .liniilli 2000 Tews, A., M. Enk, S. Leathe, W. Hill, S.Dalbey, and G. Liknes. 2000. Westslope cutthroat trout (Oncorhynchus clarki lewisi) in northcentral Montana; status and restoration strategies. Montana, Fish, Wildlife and Parks, Great Falls, Montana. White, G. C., D. R. Anderson, K. P. Burnham, and D. L. Otis. 1982. Capture-Recapture and Removal Methods for Sampling Closed Populations. LA-8787-NERP. UC-1 1. U.S. Department of Energy, Los Alamos National Laboratory, Los Alamos, New Mexico. Van Deventer, J. S. and W. S. Platts. 1985. A Computer Software System for Entering, Managing, and Analyzing Fish Capture Data From Streams. Research Note rNT-352. U.S. Department of Agriculture, Forest Service, Intermountain Research Station, Ogden, Utah. 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