G.G.Oliver and Associates Environmental Science Watershed Restoration Aquatic Science Fisheries Research Kootenay Region Small Lakes Stocking Assessment: 2003 Prepared for Ministry of Water, Land and Air Protection 205 Industrial Rd. G Cranbrook, B.C. V1C 7G5 Prepared by G. G. Oliver, M.Sc., R.P.Bio. GG Oliver and Associates Environmental Science 2291 1 st Ave S. Cranbrook, B.C. V1C 6Y3 February 2004
EXECUTIVE SUMMARY Twelve small lakes in the Kootenay Region were investigated September through October 2003 to assess the performance of rainbow trout stocks outplanted in monoculture systems or lakes having a coarsefish presence. Gillnet surveys were completed at Box, Cameron and Rosebud lakes in the West Kootenay and Aid, Alces, Comfort, Halfway, Help, Rockbluff, Rocky Point, Solar and Three Island lakes in the East Kootenay. Length-at-age and length-weight relationships were determined and evaluated against current stocking rates and management regimes. Measurements of total dissolved solids (TDS) and ph were also collected to update current water chemistry conditions. Isometric growth coefficients ranged from a low of 2.62 to a high of 3.00. The lowest value was determined for rainbow trout in Comfort Lake where coarsefish numbers have dramatically increased since the mid- 1980 s; the highest values were obtained at Alces Lake and may be coincidental with present levels of angling effort that maintain an appropriate population structure relative to lake productivity. Of the rainbow trout stocks monitored across the 12 study lakes, Tunkwa and Pennask-Premier stocks were most characteristic of early maturation at a smaller size, particularly among males. The size and age structure of individual populations was variable among study lakes and survival of rainbow trout to adulthood was believed to be affected by early maturation or competitive interactions between rainbow and other species, where present. At Rosebud Lake, survival may have been influenced by prevailing environmental conditions leading to physiological stress associated with high ph. Recommendations are provided relative to changes in stock selection, stocking density and fisheries management alternatives. February 2004 ii
ACKNOWLEDGEMENTS The following people are gratefully acknowledged for contributions of information and assistance during this study: Ministry of Water, Land and Air Protection W.T. Westover, Fisheries Biologist, Cranbrook, B.C. Jeff Burrows, Sr. Fisheries Biologist, Nelson, B.C. J. Bell, Fisheries Fisheries Biologist, Nelson, B.C. Herb Tepper, Fisheries Biologist, Cranbrook, B.C. Kevin Heidt, Fisheries Technician, Cranbrook, B.C. Peter Brown, Fish Culturist, Wardner, B.C. Doug Crowley, Fish Culturist, Wardner, B.C. Kevin Franck and Associates Kevin Franck, Draftsman, Cranbrook, B.C. Kevin Heidt, Herb Tepper, Jeff Burrows and John Bell assisted with netting surveys and provided sources of information necessary in the completion of the report. Bill Westover and Kevin Heidt provided information on angler use in the East Kootenay. Peter Brown and Doug Crowley provided background on rearing practices for individual stocks at Kootenay Trout Hatchery and information on fish size at time of release. Kevin Franck provided drafting services during report preparation. My sincere thanks to all participants. February 2004 iii
TABLE OF CONTENTS EXECUTIVE SUMMARY...II ACKNOWLEDGEMENTS...III TABLE OF CONTENTS...IV LIST OF TABLES...VI LIST OF FIGURES...VII 1.0 INTRODUCTION...1 1.1 BACKGROUND...1 2.0 METHODS...2 2.1 WATER CHEMISTRY...2 2.2 FISH SAMPLING...4 2.3 ANALYTICAL PROCEDURES...4 3.0 RESULTS...5 3.1 PHYSICAL AND CHEMICAL CHARACTERISTICS...5 3.2 BIOLOGICAL CHARACTERISTICS...5 3.2.1 Aid Lake...5 3.2.2 Alces Lake...10 3.2.3 Box Lake...13 3.2.4 Cameron Lake...17 3.2.5 Comfort Lake...23 3.2.6 Halfway Lake...29 3.2.7 Help Lake...32 3.2.8 Rockbluff Lake...38 3.2.9 Rocky Point Lake...41 3.2.10 Rosebud Lake...45 3.2.11 Solar Lake...48 3.2.12 Three Island Lake...53 3.3 GROWTH, STOCKING DENSITY AND ANGLER USE...56 February 2004 iv
4.0 DISCUSSION...58 5.0 LITERATURE CITED...62 APPENDIX 1...63 BATHYMETRIC MAPS FOR SELECTED LAKES...63 APPENDIX 2...74 BIOLOGICAL DATA...74 APPENDIX 3...92 PHOTOGRAPHIC PLATES...92 February 2004 v
LIST OF TABLES TABLE 1. PHYSICAL AND CHEMICAL CHARACTERISTICS OF SMALL LAKES IN THE STUDY AREA.6 TABLE 2. BACK-CALCULATED LENGTHS AT SUCCESSIVE ANNULI FOR RAINBOW TROUT IN AID LAKE. 95% CONFIDENCE LIMITS ARE SHOWN IN BRACKETS....7 TABLE 3. BACK-CALCULATED LENGTHS AT SUCCESSIVE ANNULI FOR RAINBOW TROUT IN ALCES LAKE. 95% CONFIDENCE LIMITS ARE SHOWN IN BRACKETS....12 TABLE 4. BACK-CALCULATED LENGTHS AT SUCCESSIVE ANNULI FOR RAINBOW TROUT IN BOX LAKE. 95% CONFIDENCE LIMITS ARE SHOWN IN BRACKETS....15 TABLE 5. BACK-CALCULATED LENGTHS AT SUCCESSIVE ANNULI FOR RAINBOW TROUT IN CAMERON LAKE. 95% CONFIDENCE LIMITS ARE SHOWN IN BRACKETS...20 TABLE 6. BACK-CALCULATED LENGTHS AT SUCCESSIVE ANNULI FOR RAINBOW TROUT IN CAMERON LAKE. 95% CONFIDENCE LIMITS ARE SHOWN IN BRACKETS...24 TABLE 7. BACK-CALCULATED LENGTHS AT SUCCESSIVE ANNULI FOR RAINBOW TROUT IN HALFWAY LAKE. 95% CONFIDENCE LIMITS ARE SHOWN IN BRACKETS...30 TABLE 8. BACK-CALCULATED LENGTHS AT SUCCESSIVE ANNULI FOR RAINBOW TROUT IN HELP LAKE. 95% CONFIDENCE LIMITS ARE SHOWN IN BRACKETS....33 TABLE 9. BACK-CALCULATED LENGTHS AT SUCCESSIVE ANNULI FOR RAINBOW TROUT IN ROCKBLUFF LAKE. 95% CONFIDENCE LIMITS ARE SHOWN IN BRACKETS....39 TABLE 10. BACK-CALCULATED LENGTHS AT SUCCESSIVE ANNULI FOR RAINBOW TROUT IN ROCKY POINT LAKE. 95% CONFIDENCE LIMITS ARE SHOWN IN BRACKETS....44 TABLE 11. BACK-CALCULATED LENGTHS AT SUCCESSIVE ANNULI FOR DOMESTIC RAINBOW TROUT IN ROSEBUD LAKE. 95% CONFIDENCE LIMITS ARE SHOWN IN BRACKETS...47 TABLE 12. BACK-CALCULATED LENGTHS AT SUCCESSIVE ANNULI FOR RAINBOW TROUT IN SOLAR LAKE. 95% CONFIDENCE LIMITS ARE SHOWN IN BRACKETS....50 TABLE 13. BACK-CALCULATED LENGTHS AT SUCCESSIVE ANNULI FOR RAINBOW TROUT IN THREE ISLAND LAKE. 95% CONFIDENCE LIMITS ARE SHOWN IN BRACKETS....55 February 2004 vi
LIST OF FIGURES FIGURE 1. LOCATION OF STUDY AREA....3 FIGURE 2. RAINBOW TROUT STOCK SELECTION AND STOCKING RATE AT AID LAKE FROM 1998 TO 2003....8 FIGURE 3. LENGTH FREQUENCY DISTRIBUTION OF RAINBOW TROUT SAMPLED IN AID LAKE ON SEPTEMBER, 2003....8 FIGURE 4. BODY:SCALE RELATIONSHIP FOR RAINBOW TROUT IN AID LAKE...9 FIGURE 5. LENGTH FREQUENCY DISTRIBUTION OF FINESCALE SUCKER SAMPLED IN AID LAKE ON SEPTEMBER, 2003....9 FIGURE 6. LENGTH-WEIGHT RELATIONSHIP FOR RAINBOW TROUT SAMPLED IN AID LAKE ON SEPTEMBER 30, 2003...10 FIGURE 7. RAINBOW TROUT STOCK SELECTION AND STOCKING RATE IN ALCES LAKE FROM 1999 TO 2003....11 FIGURE 8. LENGTH FREQUENCY DISTRIBUTION OF RAINBOW TROUT SAMPLED IN ALCES LAKE ON OCTOBER 17, 2003....11 FIGURE 9. BODY:SCALE RELATIONSHIP FOR RAINBOW TROUT IN ALCES LAKE....12 FIGURE 10. LENGTH-WEIGHT RELATIONSHIP FOR RAINBOW TROUT SAMPLED IN ALCES LAKE ON OCTOBER 17, 2003....13 FIGURE 11. LENGTH FREQUENCY DISTRIBUTION OF RAINBOW TROUT SAMPLED IN BOX LAKE ON OCTOBER 7, 2003....14 FIGURE 12. BODY:SCALE RELATIONSHIP FOR RAINBOW TROUT IN BOX LAKE....15 FIGURE 13. RAINBOW TROUT STOCK SELECTION AND STOCKING RATE AT BOX LAKE FROM 1993 TO 2003....16 FIGURE 14. LENGTH-WEIGHT RELATIONSHIP FOR RAINBOW TROUT SAMPLED IN BOX LAKE ON OCTOBER 7, 2003....16 FIGURE 15. LENGTH FREQUENCY DISTRIBUTION OF EASTERN BROOK TROUT SAMPLED IN BOX LAKE ON OCTOBER 7, 2003....17 FIGURE 16. LENGTH-WEIGHT RELATIONSHIP FOR EASTERN BROOK TROUT SAMPLED IN BOX LAKE ON OCTOBER 7, 2003....18 FIGURE 17. RAINBOW TROUT AND EASTERN BROOK TROUT STOCK SELECTION AND STOCKING RATE AT CAMERON LAKE FROM 1998 TO 2003....18 FIGURE 18. LENGTH FREQUENCY DISTRIBUTION OF RAINBOW TROUT SAMPLED IN CAMERON LAKE ON OCTOBER 7, 2003....19 February 2004 vii
FIGURE 19. BODY:SCALE RELATIONSHIP FOR RAINBOW TROUT IN CAMERON LAKE...20 FIGURE 20. LENGTH-WEIGHT RELATIONSHIP FOR RAINBOW TROUT SAMPLED IN CAMERON LAKE ON OCTOBER 7, 2003....21 FIGURE 21. LENGTH FREQUENCY DISTRIBUTION OF EASTERN BROOK TROUT SAMPLED IN CAMERON LAKE ON OCTOBER 7, 2003...21 FIGURE 22. LENGTH-WEIGHT RELATIONSHIP FOR EASTERN BROOK TROUT IN CAMERON LAKE ON OCTOBER 7, 2003....22 FIGURE 23. LENGTH FREQUENCY DISTRIBUTION OF RAINBOW TROUT SAMPLED IN COMFORT LAKE ON SEPTEMBER 30, 2003...23 FIGURE 24. RAINBOW TROUT STOCK SELECTION AND STOCKING RATE AT COMFORT LAKE FROM 1998 TO 2003...24 FIGURE 25. BODY:SCALE RELATIONSHIP FOR RAINBOW TROUT IN COMFORT LAKE...25 FIGURE 26. LENGTH-WEIGHT RELATIONSHIP FOR RAINBOW TROUT SAMPLED IN COMFORT LAKE ON SEPTEMBER 30, 2003...26 FIGURE 27. LENGTH FREQUENCY DISTRIBUTION OF FINESCALE SUCKER SAMPLED IN COMFORT LAKE ON SEPTEMBER 30, 2003...27 FIGURE 28. LENGTH-WEIGHT RELATIONSHIP FOR FINESCALE SUCKER SAMPLED IN COMFORT LAKE ON SEPTEMBER 30, 2003...28 FIGURE 29. RAINBOW TROUT STOCK SELECTION AND STOCKING RATE AT HALFWAY LAKE FROM 1998 TO 2003...29 FIGURE 30. LENGTH FREQUENCY DISTRIBUTION OF RAINBOW TROUT SAMPLED IN HALFWAY LAKE ON OCTOBER 1, 2003....30 FIGURE 31. BODY:SCALE RELATIONSHIP FOR RAINBOW TROUT IN HALFWAY LAKE....31 FIGURE 32. LENGTH-WEIGHT RELATIONSHIP FOR RAINBOW TROUT SAMPLED IN HALFWAY LAKE ON OCTOBER 1, 2003....32 FIGURE 33. RAINBOW TROUT STOCK SELECTION AND STOCKING RATE AT HELP LAKE FROM 1998 TO 2003....33 FIGURE 34. LENGTH FREQUENCY DISTRIBUTION OF RAINBOW TROUT SAMPLED IN HELP LAKE ON SEPTEMBER 30, 2003....33 FIGURE 35. BODY:SCALE RELATIONSHIP FOR RAINBOW TROUT IN HELP LAKE....34 FIGURE 36. LENGTH-WEIGHT RELATIONSHIP FOR RAINBOW TROUT SAMPLED IN HELP LAKE ON OCTOBER 1, 2003....35 FIGURE 37. LENGTH FREQUENCY DISTRIBUTION OF FINESCALE SUCKER SAMPLED IN HELP LAKE ON OCTOBER 1, 2003....36 February 2004 viii
FIGURE 38. LENGTH-WEIGHT RELATIONSHIP FOR FINESCALE SUCKER SAMPLED IN HELP LAKE ON OCTOBER 1, 2003....36 FIGURE 39. LENGTH FREQUENCY DISTRIBUTION OF EASTERN BROOK TROUT SAMPLED IN HELP LAKE ON OCTOBER 1, 2003....37 FIGURE 40. LENGTH-WEIGHT RELATIONSHIP FOR EASTERN BROOK TROUT SAMPLED IN HELP LAKE ON OCTOBER 1, 2003....37 FIGURE 41. RAINBOW TROUT STOCK SELECTION AND STOCKING RATE AT ROCKBLUFF LAKE FROM 1998 TO 2003...38 FIGURE 42. LENGTH FREQUENCY DISTRIBUTION OF RAINBOW TROUT SAMPLED IN ROCKBLUFF LAKE ON OCTOBER 17, 2003....39 FIGURE 43. BODY:SCALE RELATIONSHIP FOR RAINBOW TROUT IN ROCKBLUFF LAKE...40 FIGURE 44. LENGTH-WEIGHT RELATIONSHIP FOR RAINBOW TROUT SAMPLED IN ROCKBLUFF LAKE ON OCTOBER 17, 2003....41 FIGURE 45. RAINBOW TROUT STOCK SELECTION AND STOCKING RATE AT ROCKY POINT LAKE FROM 1999 TO 2003...42 FIGURE 46. LENGTH FREQUENCY DISTRIBUTION OF RAINBOW TROUT SAMPLED IN ROCKY POINT LAKE ON OCTOBER 2, 2003....43 FIGURE 47. BODY:SCALE RELATIONSHIP FOR RAINBOW TROUT IN ROCKY POINT LAKE...43 FIGURE 48. LENGTH-WEIGHT RELATIONSHIP FOR RAINBOW TROUT SAMPLED IN ROCKY POINT LAKE ON OCTOBER 2, 2003....45 FIGURE 49. RAINBOW TROUT STOCK SELECTION AND STOCKING RATE AT ROSEBUD LAKE FROM 1996 TO 2002...46 FIGURE 50. LENGTH FREQUENCY DISTRIBUTION OF RAINBOW TROUT SAMPLED IN ROSEBUD LAKE ON OCTOBER 8, 2003....46 FIGURE 51. BODY:SCALE RELATIONSHIP FOR RAINBOW TROUT IN ROSEBUD LAKE....48 FIGURE 52. LENGTH-WEIGHT RELATIONSHIP FOR RAINBOW TROUT SAMPLED IN ROSEBUD LAKE ON OCTOBER 8, 2003....49 FIGURE 53. RAINBOW TROUT STOCK SELECTION AND STOCKING RATE AT SOLAR LAKE FROM 1998 TO 2003....49 FIGURE 55. BODY:SCALE RELATIONSHIP FOR RAINBOW TROUT IN SOLAR LAKE...52 FIGURE 56. LENGTH-WEIGHT RELATIONSHIP FOR RAINBOW TROUT SAMPLED IN SOLAR LAKE ON OCTOBER16, 2003...53 FIGURE 57. RAINBOW TROUT STOCK SELECTION AND STOCKING RATE AT THREE ISLAND LAKE FROM 1999 TO 2003...54 February 2004 ix
FIGURE 58. LENGTH FREQUENCY DISTRIBUTION OF RAINBOW TROUT SAMPLED IN THREE ISLAND LAKE ON OCTOBER 2, 2003...54 FIGURE 59. BODY:SCALE RELATIONSHIP FOR RAINBOW TROUT IN THREE ISLAND LAKE....55 FIGURE 60. LENGTH-WEIGHT RELATIONSHIP FOR RAINBOW TROUT SAMPLED IN THREE ISLAND LAKE ON OCTOBER 2, 2003....56 FIGURE 61. A COMPARISON OF RAINBOW TROUT LENGTH-WEIGHT RELATIONSHIPS AMONG REPRESENTATIVE STUDY LAKES....57 FIGURE 62. A COMPARISON OF ANGLER USE AT SELECTED LAKES BASED ON AVAILABLE SLIM DATA. DATA SUMMARIZED FOR INDIVIDUAL YEARS....58 February 2004 x
1.0 Introduction Over the past twenty years, the small lakes management program in the Kootenay Region has included a variety of activities to improve the size and survival of hatchery-maintained rainbow trout fisheries and to expand the quality of local angling opportunities. Earlier management activities focused on special regulations, chemical rehabilitation and lake aeration at several small lakes in the East and West Kootenay. More recently, however, management activities have centered on special stock introductions into selected small lakes to off-set growth impairment due to early maturity issues or coarsefish interactions. To this end, the most appropriate stocks that best maximize rainbow trout production have been considered to improve angling quality within small lakes in the Kootenay Region. The present report outlines rainbow trout age and growth characteristics as part of an ongoing program in its second year. The small lakes assessment program is designed to evaluate the performance of individual stocks in selected lakes and provide recommendations for future management options. 1.1 Background Special stocks employed in the present evaluation include rainbow trout of either Premier, Pennask, Tunkwa, Tunkwa/Badger, Gerrard or Fraser Valley origin. Pennask stock was introduced into Premier Lake (Kootenay Trout Hatchery s egg collection station) in the mid-1980 s owing to a chronic problem of early maturity in the original Premier stock that plagued growth and survival of out-planted yearlings in stocking-dependent small lakes throughout the region. Selection for early maturity was artificially hastened by earlier hatchery operations that utilized two year old males as a donor source for fertilization purposes. Introduction of Pennask stock, known for its later maturity, into Premier Lake has helped to correct the problem and shifted the average age of first maturity to 3 and 4 years for male and female fish, respectively. For present purposes, Premier and Pennask stocks obtained from Premier Lake are distinguished by previous marks (clips) applied to Pennask stock; unmarked fish are assumed to represent Premier stock. In a single stocking example, Fraser Valley rainbow trout eggs were manipulated by heat shock treatment to enhance sterility (i.e., triploidy). As a consequence of their sterile February 2004 1
condition, growth efficiencies are directed at somatic development allowing individual fish to achieve a larger overall size. With the exception of the Gerrard stock, raised at Selkirk College (as part of an embryology program in the present curriculum), all other stocks were cultured at Kootenay Trout Hatchery (Wardner, B.C.). All fish were released as either yearlings or fingerlings. The present evaluation includes 3 lakes in the West Kootenay (Rosebud, Box and Cameron lakes) and 9 lakes in the East Kootenay (Aid, Comfort, Help, Rocky Point, Three Island, Halfway, Alces, Rockbluff, and Solar lakes; Fig. 1). Rocky Point, Three Island, Halfway, Alces, Rockbluff lakes are managed as rainbow trout monoculture systems. Historically, Cameron and Box lakes have been managed for both rainbow and eastern brook trout. Aid, Comfort and Help lakes support multiple fish species that also include coarsefish. The purpose of the present study is to evaluate rainbow trout stocks across variable stocking densities and assess rainbow trout growth relative to physical, chemical and biological (single/multiple species) conditions. Stock evaluations examine age and growth and length-weight relationships across lake environments and management regimes. Updates in chemical lake conditions are also assessed through measurements of ph and total dissolved solids (TDS). Recommendations to changes in current management strategies are included where current stocks or stocking densities have not met expectations. 2.0 Methods 2.1 Water chemistry Total dissolved solids (TDS) and ph were measured at each selected lake during the period of assessment from late September through mid-october 2003. A 500 ml water sample was collected from the surface near the lake margin where depths exceeded 0.5 m and analyzed. TDS was measured with an Oakton TDS Testr 1 while ph was measured with an Oakton ph Testr 2; individual meters were calibrated with reference samples prior to use at each lake to assess precision and maintain accuracy. Further adjustments to the TDS meter beyond factory settings were not required over the duration of the study. February 2004 2
Figure 1. Location of study area. February 2004 3
2.2 Fish sampling Fish collections were completed by gillnet surveys employing floating and sinking nets; use of a floating net was restricted to Aid Lake whereas all other study lakes were sampled by sinking net only. Ninety-two meter standard experimental gangs consisting of 6, 15 X 2.5 m variable mesh panels (ordered as 25, 76, 51, 89, 38 and 64 mm mesh sizes shoreward to lakeward) were deployed in littoral habitats and each set was placed perpendicular to the shoreline. Individual nets were anchored shoreward and lakeward; the lakeward end of the each net was supported with a buoy to mark the endpoint and assist with retrieval. Overnight sets were completed from 14:30 to 12:00 hours with an average soak time of 19.4 hours. All sets were made from a 4 m aluminum boat. Individual fish were collected as a composite sample from all panels and catch per unit effort (CPUE) was reported as fish per hour by species. Fork lengths were obtained with a measuring board to the nearest millimeter and weights were measured to the nearest gram with an Ohaus Model CS 5000 (0-5 kg) electronic balance; each fish was supported in a plastic cradle that required taring prior to each measurement. A representative number of scales across the size range of the rainbow trout sample were removed within 3-5 rows of the lateral line immediately posterior to the dorsal fin and stored in individual scale envelopes. 2.3 Analytical procedures Rainbow trout scales were cleaned, mounted on a glass slide and read with a 3M TM 800 Microfiche reader at 60X magnification. Measurements of scale radius and distance from nucleus to each annulus were marked on a paper strip, body:scale relationship (mm) determined by regression analysis and lengths at successive annuli back-calculated using Lea s formula (Bagenal 1978). Ages were then assigned to length frequency distributions assembled for each rainbow trout sample. Length-weight data were transformed by natural logarithm; coefficients for each fish sample were generated by regression analysis to explain the length-weight relationship. Proportionality was used to compare deviations from isometric growth among sample populations from each lake relative to present stocking densities and corresponding lake productivity. For each regression calculated, a plot of residuals was inspected for equality of variance among individual samples. Theoretical February 2004 4
stocking rate was calculated using the formula: Number of yearlings = TDS * ((2.47 shoal area) + (0.247 surface area)); for fall fry determinations: two fall fry were considered equivalent to one yearling. 3.0 Results 3.1 Physical and chemical characteristics A summary of the physical and chemical characteristics of selected lakes in the study area are provided in Table 1. Four of the lakes are considered high elevation lakes and lie above 1000m while the remainder are considered low elevation lakes lying below 1000 m. The majority of candidate lakes have inlets and/or outlets while remaining waterbodies are considered small kettle lakes; water level fluctuation occurs primarily through direct surface run-off during snowmelt or natural upwelling springs. The extent of natural recruitment to lakes with a surface supply is unknown but considered marginal. The mean surface area of the study lakes is ~22 ha; Box Lake has the largest surface area at 71 ha. The majority of lakes are also considered shallow with maximum depths ranging from 2.5 to 34 m and mean depths ranging from 1-10 m. Accordingly, the amount of shoal area is considered moderate with an average of 63% littoral area estimated across all lakes. ph ranges from 8.1 to 9 yet the majority of lakes lie within an acceptable limit for fish production. Total dissolved solids are highly variable ranging from 40 to 430 ppm. Across the range of candidate lakes, a comparison of MEI (Ryder et al. 1974), an index of lake productivity, suggests a production capability that ranges from low to moderate. A summary of lake bathymetry, for candidate lakes with completed physical surveys, is provided in Appendix 1; all biological data is in Appendix 2. 3.2 Biological characteristics 3.2.1 Aid Lake Previous gillnet surveys conducted in 1984 identified rainbow trout and largescale sucker as local species (FISS database, Victoria, B.C.); closer inspection of suckers February 2004 5
Table 1. Physical and chemical characteristics of small lakes in the study area. Lake Watershed Latitude Longitude Elevation Surface Maximum Mean Shoal area ph TDS MEI 1 code (m) area (ha) depth (m) depth (m) (ha) (ppm) Aid 300-871400 51:39:38 117:27:05 985 13.18 5 2.4 13.18 8.1 150 7.91 Alces 349-666200-32000 50:07:14 115:32:21 1210 30.1 14.8 6.7 14.50 8.3 180 5.18 Box 300-706100 50:12:32 117:42:57 593 70.82 7.3 4.5 8.9 90 4.47 Cameron 300-697000-74600 50:18:51 117:59:59 930 35.37 12.5 4.2 23.80 8.6 40 3.09 Comfort 300-871400 51:38:49 117:25:48 997 9.11 5.5 3.3 9.11 8.5 150 6.74 Halfway 300-968400-25600 50:45:57 116:22:08 1103 5.5 13.4 3.8 1.20 8.9 270 8.43 42200-5960 Help 300-871400 51:39:09 117:26:15 994 11.97 2.4 1.2 11.97 8.5 150 11.18 Rockbluff 349-491000-78400 49:53:32 115:38:34 940 19.83 25.6 9.1 7.00 8.8 350 6.20 Rocky Point 390-359600 51:00:55 116:46:12 1426 27.64 14.6 4.6 18.50 8.5 90 4.42 Rosebud 330-092600-11000 49:02:52 117:16:03 808 13.36 14.9 7 8.9 130 4.31 Solar 349-434900-13700 49:45:39 115:49:18 930 3.26 10 8.9 430 77200-7880 Three Island 390-137600-40800 51:00:43 116:47:04 1518 23.7 34.3 10.7 6.97 9 70 2.56 1 MEI = morpho-edaphic index February 2004 6
in the present survey suggests that these fish are likely finescale owing to the nature of their extended bulbous snout, a ventral mouth that protrudes behind the tip of the snout and small cycloid scales. The catch composition on September 30, 2003 consisted of 84% rainbow trout (CPUE=2.09) and 16% finescale sucker (longnose; CPUE=0.39). Rainbow trout have been planted consistently at a 1500 yearlings per annum over the last several years utilizing either Premier and Pennask stock or their crosses (Fig. 2). The rainbow trout sample ranged from 122 260 mm (mean = 190.3 Fig. 3) and included individuals up to age-group 3+. Size-at-age from scale interpretations are provided in Table 2; back-calculated lengths for each age class were estimated from the body:scale relationship depicted in Figure 4. Low incremental growth during their second and third years may be related to a condition of early maturity in combination with low lake productivity (TDS=150); all fish >200 mm FL were developing gonads and would have spawned during the spring of 2004. Finescale sucker ranged in size from 103 210 mm (mean = 144.6; Fig. 5) with corresponding weights from 14-110 g. The length-weight relationship for rainbow trout indicates that growth is less than proportional (Fig. 6). Accordingly, the lack of proportionality over the range of fish size sampled suggests that individuals are in slightly poorer condition than expected if growth was isometric (Plate 1 (Appendix 3)). Their present condition may be related to competitive interactions with coarsefish for a limited food supply. The slightly lower slope coefficient is not believed to be related to stocking density since the lake is currently managed at ~28% of theoretical stocking capacity. Table 2. Back-calculated lengths at successive annuli for rainbow trout in Aid Lake. 95% confidence limits are shown in brackets. Age-group n Age Class I II III 1+ 4 67.7 (11.67) 2+ 7 64.1 136.1 (6.89) (13.53) 3+ 7 73.8 138.3 200.7 (8.10) (12.36) (11.55) Grand Average 68.5 137.2 200.7 February 2004 7
1600 Pennask Pennask Premier Premier Pennask-Premier Pennask-Premier 1400 1200 Number of fish released 1000 800 600 400 200 0 1998 1999 2000 2001 2002 2003 Figure 2. Rainbow trout stock selection and stocking rate at Aid Lake from 1998 to 2003. 18 16 2+ n=48 14 3+ 12 Percent occurrence 10 8 6 1+ 4 2 0 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 Size category (mm) Figure 3. Length frequency distribution of rainbow trout sampled in Aid Lake on September, 2003. February 2004 8
300 Fork length (mm) = 20.1793 + 3.1590 (Scale radius); r 2 = 0.78; n = 18 250 200 Fork length (mm) 150 100 50 0 0 10 20 30 40 50 60 70 80 90 Scale radius ( X60 mm) Figure 4. Body:scale relationship for rainbow trout in Aid Lake. 35 30 n=9 25 Percent occurrence 20 15 10 5 0 100 110 120 130 140 150 160 170 180 190 200 210 Size category (mm) Figure 5. Length frequency distribution of finescale sucker sampled in Aid Lake on September, 2003. February 2004 9
5.5 5 Ln (W) = -10.7639 + 2.8736 Ln (FL); r 2 = 0.98; n=48 Ln Weight (g) 4.5 4 3.5 3 4.7 4.8 4.9 5 5.1 5.2 5.3 5.4 5.5 5.6 Ln Fork length (mm) Figure 6. Length-weight relationship for rainbow trout sampled in Aid Lake on September 30, 2003. 3.2.2 Alces Lake Composition of the catch from a single sinking gillnet retrieved on October 17, 2003 consisted entirely of rainbow trout (CPUE=2.51; Premier or Premier-Pennask stock; Fig. 7). A review of the stocking records indicates a consistent outplanting of 2000 fish per year over the last five years. The size distribution (n=49) of trout ranged from 140 400 mm (mean = 333.6) with age-groups ranging from 1+ - 5+ (Fig. 8). Of this total, 4 fish were immature, 2 were in kelted condition, 1 female was egg-bound and the remainder were maturing. Size-at-age information is provided in Table 3 based on the body-scale relation shown in Figure 9; considerable scatter was observed about the regression line for the given scale subsample size. Incremental growth begins to slow after the 3 rd year and may be related to maturity and low to moderate lake productivity. Weight is proportional to body length in this sample and an average slope coefficient is apparent (Fig. 10; Plate 2). Present stocking levels occur at ~26% of theoretical stocking capacity in consideration of February 2004 10
2500 2000 Pennask Premier Premier Pennask-Premier Pennask-Premier Number of fish released 1500 1000 500 0 1999 2000 2001 2002 2003 Figure 7. Rainbow trout stock selection and stocking rate in Alces Lake from 1999 to 2003. 16 14 n=49 3+ 5+ 12 4+ Percent occurrence 10 8 6 4 2 0 1+ 140 150 160 170 180 190 200 210 220 230 240 250 Size category (mm) 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400 Figure 8. Length frequency distribution of rainbow trout sampled in Alces Lake on October 17, 2003. February 2004 11 2+
Table 3. Back-calculated lengths at successive annuli for rainbow trout in Alces Lake. 95% confidence limits are shown in brackets. Age-group n Age Class I II III IV V 1+ 1 121.5 2+ 5 132.7 192.2 (3.81) (13.00) 3+ 6 137.2 202.3 269.9 (4.76) (18.15) (25.73) 4+ 2 132.6 181.5 251.7 316.9 (0.95) (2.87) (30.81) (11.53) 5+ 5 135.0 179.6 236.9 296.9 343.7 (2.30) (6.03) (21.92) (10.13) (10.32) Grand Average 131.0 192.0 260.8 316.9 343.7 450 400 Fork length (mm) = 99.0354 + 1.9614 (Scale radius); r 2 =0.77; n=19 350 300 Fork length (mm) 250 200 150 100 50 0 0 20 40 60 80 100 120 140 160 180 Scale radius (mm X60) Figure 9. Body:scale relationship for rainbow trout in Alces Lake. February 2004 12
ambient lake productivity. 7 6.5 6 Ln (W) = -11.4846 + 3.0081 Ln (FL); r 2 =0.95; n=49 5.5 Ln Weight (g) 5 4.5 4 3.5 3 4 4.5 5 5.5 6 6.5 Ln Fork length (mm) Figure 10. Length-weight relationship for rainbow trout sampled in Alces Lake on October 17, 2003. 3.2.3 Box Lake Rainbow trout (10%; CPUE=1.38) and eastern brook trout (90%; CPUE=12.19) were captured in an overnight sinking gillnet set on October 7, 2003. Rainbow trout size distribution varied from 114 391 mm (mean = 205.1) and ages were assigned from 1+ - 4+ (Fig. 11). The frequency distribution was highly skewed to younger fish suggesting low survival of adults and all fish >190 mm were maturing. Size-at-age from scale interpretations are provided in Table 4; lengths were estimated from the body:scale relationship shown in Figure 12. On average, the largest incremental growth was observed during the second and third year (refer to Table 2). Pennask and Premier rainbow stocks have been used in Box Lake since 1999 while the Pennask-Premier cross has been utilized over the last two years (Fig. 13; the stocking rate was reduced by 50% in 2003 and remains at 2500 fish per year. A review of the length-weight relationship indicates isometric growth (Fig. 14); overall, the fish are in average condition (Plate 3). A mild infestation of black spot on February 2004 13
rainbow trout was also evident. 20 18 1+ n=29 16 14 Percent occurrence 12 10 8 6 4 2+ 3+ 4+ 2 0 120 140 160 180 200 220 240 260 280 300 320 340 360 380 Size category (mm) Figure 11. Length frequency distribution of rainbow trout sampled in Box Lake on October 7, 2003. February 2004 14
Eastern brook trout grossly outnumbered rainbow trout (~9 fold) in the catch; a more balanced frequency distribution, but without specific age confirmation, suggests up Table 4. Back-calculated lengths at successive annuli for rainbow trout in Box Lake. 95% confidence limits are shown in brackets. Age-group n Age Class I II III IV 1+ 9 86.86 (7.00) 2+ 5 81.1 162 (5.87) (16.1) 3+ 1 105.6 266.9 309.7 4+ 2 72.5 118.3 253.7 321.8 (11.47) (20.4) (80.6) (55.0) Grand Average 86.5 182.4 281.7 321.8 450 400 Fork length (mm) = 36.4341 + 2.7877 (Scale radius); r 2 =0.92; n=17 350 300 Fork length (mm) 250 200 150 100 50 0 0 20 40 60 80 100 120 140 Scale radius (mm X60) Figure 12. Body:scale relationship for rainbow trout in Box Lake. February 2004 15
6000 5000 Pennask Premier Premier Number of fish released 4000 3000 2000 Pennask-Premier Pennask-Premier 1000 0 1999 2000 2001 2002 2003 Figure 13. Rainbow trout stock selection and stocking rate at Box Lake from 1993 to 2003. 7 6.5 Ln (W) = -11.1867 + 2.9663 Ln (FL); r 2 =0.99; n=29 6 Ln Weight (g) 5.5 5 4.5 4 3.5 4.5 5 5.5 6 6.5 Ln Fork length (mm) Figure 14. Length-weight relationship for rainbow trout sampled in Box Lake on February 2004 16
October 7, 2003. to 5 age classes of this species were present in the sample (Fig. 15). The size distribution for brook trout varied from 102 to 383 mm (mean = 236.8) and corresponding fish weight varied from 14 to 620 g, respectively. Fish > 180 mm were sexually mature and all specimens in the sample were heavily plagued by black spot disease. As indicated in the regression equation in Figure 16, a coefficient of 3.06 indicates proportional growth for the population (i.e., average condition). A review of the stocking information dating back to the early 1920 s shows no record of Eastern brook trout introduction; it is assumed that the presence of brook trout is the result of an unauthorized introduction. 3.2.4 Cameron Lake The catch composition from a single sinking gillnet set on October 7, 2003 consisted of near equal proportions of rainbow trout and Eastern brook trout (CPUE=3.2). Two thousand sterile brook trout were planted in 1998 and 1999 whereas 2000 Pennask stock rainbow have been introduced over the last four years (Fig. 17). 12 n=253 10 8 Percent occurrence 6 4 2 0 110 130 150 170 190 210 230 250 270 290 310 330 350 370 Size category (mm) Figure 15. Length frequency distribution of Eastern brook trout sampled in Box Lake on October 7, 2003. February 2004 17
7 6.5 6 Ln (W) = -11.6195 + 3.0605 Ln (FL); r 2 =0.99; n=198 5.5 Ln Weight (g) 5 4.5 4 3.5 3 2.5 4 4.5 5 5.5 6 6.5 Ln Fork length (mm) Figure 16. Length-weight relationship for Eastern brook trout sampled in Box Lake on October 7, 2003. 2500 2000 Aylmer 3N Aylmer AF3N Pennask Pennask Pennask Pennask Number of fish released 1500 1000 Ebt Rbt 500 0 1998 1999 2000 2001 2002 2003 Figure 17. Rainbow trout and Eastern brook trout stock selection and stocking rate at Cameron Lake from 1998 to 2003. February 2004 18
The stocking rate currently remains at 74% of theoretical capacity. Notwithstanding, there was a definite contrast in length frequency between species. The size distribution of rainbow trout ranged from 164 358 mm (mean = 222.9) and included age-groups 1+ - 3+ but the sample was largely dominated by over-yearling fish (Fig. 18). Size-at-age information for rainbow trout is provided in Table 5; incremental growth during their second and third years was highly comparable. The body:scale relationship, illustrated in Figure 19, was again used to back-calculate length at successive ages. A review of the length-weight relationship suggests proportional growth with an average condition factor expressed by the rainbow trout population (Fig. 20; Plate 4). Early maturity was again evident but size-related differences were noted between sexes; rainbow trout males were maturing as small as 180 mm whereas females were maturing >240 mm. The size distribution of Eastern brook trout was more evenly balanced; the sample ranged from 188 445 mm (mean = 312.0) and corresponding weights ranged from 102 1480 g (Fig. 21). The frequency distribution suggests that individuals up to 6 25 1+ 20 Percent occurrence 15 10 2+ 3+ 5 0 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 Size category (mm) Figure 18. Length frequency distribution of rainbow trout sampled in Cameron Lake on October 7, 2003. February 2004 19
Table 5. Back-calculated lengths at successive annuli for rainbow trout in Cameron Lake. 95% confidence limits are shown in brackets. Age-group n Age Class I II III 1+ 16 107.2 (6.23) 2+ 8 114.3 217.9 (7.83) (15.22) 3+ 2 100.9 161.6 271.6 (1.22) (18.08) (38.34) Grand Average 107.5 189.8 271.6 years of age were present but this remains unconfirmed since aging structures were not collected. Brook trout displayed an average condition (Fig. 22; refer to Plate 4) and all fish were mature. There was no evidence of any all-female triploids, from the 1999 planting, in the sample. 400 350 Fork length (mm) = 59.6580 + 2.4142 (Scale radius); r 2 =0.84; n=26 300 Fork length (mm) 250 200 150 100 50 0 0 20 40 60 80 100 120 140 Scale radius (mm X60) Figure 19. Body:scale relationship for rainbow trout in Cameron Lake. February 2004 20
6.5 6 Ln (W) = -11.2531 + 2.9801 Ln (FL); r 2 =0.99; n=57 5.5 Ln Weight (g) 5 4.5 4 3.5 5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 6 Ln Fork length (mm) Figure 20. Length-weight relationship for rainbow trout sampled in Cameron Lake on October 7, 2003. 14 12 10 Percent occurrence 8 6 4 2 0 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 390 400 410 420 430 440 Size category (mm) Figure 21. Length frequency distribution of Eastern brook trout sampled in Cameron Lake on October 7, 2003. February 2004 21
7.5 7 Ln (W) = -11.4567 + 3.0427 Ln (FL); r 2 =0.99; n=56 6.5 Ln weight (g) 6 5.5 5 4.5 4 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 6 6.1 6.2 Ln Fork length (mm) Figure 22. Length-weight relationship for Eastern brook trout in Cameron Lake on October 7, 2003. February 2004 22
3.2.5 Comfort Lake Rainbow trout (38%; CPUE=4.83), Eastern brook trout (2%; CPUE=0.22) and finescale sucker (60%; CPUE=7.56) were collected during an overnight, sinking gillnet set at Comfort Lake on September 30, 2003. The size distribution of rainbow ranged from 20 264 mm (mean = 195.9) and included age-groups 1+ and 2+ (Fig. 23). The absence of older age-groups in the sample suggests poor adult survival. Multiple stocks of rainbow trout have been utilized over the past 6 years; 2000 Pennask yearlings were planted from 1998-99, 2000 Premier yearlings were planted from 2000-01 and 2000 Pennask-Premier yearlings were planted from 2002-03 (Fig. 24). Current stocking levels are managed at ~54% of theoretical stocking capacity. Back-calculated ages are provided in Table 6 based on the body:scale relationship illustrated in Figure 25. The low correlation coefficient (r 2 =0.35) is attributed to the high degree of scatter about the trend line owing to large differences in observed scale growth among individuals in the sample. Low incremental growth during the 30 n=87 2+ 25 Percent occurrence 20 15 10 5 1+ 0 130 140 150 160 170 180 190 200 210 220 230 240 250 260 Size category (mm) Figure 23. Length frequency distribution of rainbow trout sampled in Comfort Lake on September 30, 2003. February 2004 23
2500 2000 Pennask Pennask Premier Premier Pennask-Premier Pennask-Premier Number of fish released 1500 1000 500 0 1998 1999 2000 2001 2002 2003 Figure 24. Rainbow trout stock selection and stocking rate at Comfort Lake from 1998 to 2003. Table 6. Back-calculated lengths at successive annuli for rainbow trout in Cameron Lake. 95% confidence limits are shown in brackets. Age-group n Age Class I II 1+ 1 116.3 (5.39) 2+ 5 139.8 189.2 (3.55) (7.74) Grand Average 128.1 189.2 February 2004 24
second year may be attributed to early maturity (the majority of fish >165 mm were maturing); low lake productivity (TDS=150) and/or coarsefish interactions. Consequently, rainbow trout growth was not proportional based on the length-weight determinations and a low slope coefficient was observed among the sample (Fig. 26; Plate 5). 300 250 Fork length (mm) = 107.58 + 1.70 Scale radius; r 2 =0.35; n=20 200 Fork length (mm) 150 100 50 0 0 10 20 30 40 50 60 70 80 90 Scale radius (mm x60) Figure 25. Body:scale relationship for rainbow trout in Comfort Lake. February 2004 25
5.5 5 Ln (W) = -9.4038 + 2.6141 Ln (FL); r 2 =0.92; n=85 Ln Weight (g) 4.5 4 3.5 3 4.8 4.9 5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 Ln Fork length (mm) Figure 26. Length-weight relationship for rainbow trout sampled in Comfort Lake on September 30, 2003. February 2004 26
The four Eastern brook trout collected in the gillnet set ranged from 142 446 mm (mean = 250.8) with corresponding weights ranging from 34 1180 g. The largest individual (a female) was mature. Further analysis has not been attempted due to the low sample size. Finescale sucker displayed an even size structure; the frequency distribution ranged from 110 to 295 mm (mean = 185.8; Fig. 27) and body weight ranged from 16 to 310 g. The high slope coefficient for finescale sucker (Fig. 28) suggests that this species is likely out-competing rainbow trout for the available food supply. This same aspect may explain the apparent poor survival of the selected rainbow trout stock owing to the truncated size distribution that was observed. Although exact aging of the sample was unconfirmed, the frequency distribution for finescale indicates that individuals may be represented up to five years of age. 18 16 14 n=58 Percent occurrence 12 10 8 6 4 2 0 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 Size category (mm) Figure 27. Length frequency distribution of finescale sucker sampled in Comfort Lake on September 30, 2003. February 2004 27
6 5.5 5 Ln (W) = -11.5092 + 3.0333 Ln (FL); r 2 = 0.99; n=58 Ln Weight (g) 4.5 4 3.5 3 2.5 4 4.5 5 5.5 6 Ln Fork length (mm) Figure 28. Length-weight relationship for finescale sucker sampled in Comfort Lake on September 30, 2003. February 2004 28
3.2.6 Halfway Lake Rainbow trout (n=64; CPUE=3.05 fish/hr) was the only species captured in a sinking gillnet set on October 1, 2003. Pennask stock was introduced in 1998 and 1999, changed to Premier stock in 2000 and 2001 and presently includes the Pennask- Premier cross; all plantings have remained at a stocking rate of 1500 fish per year (Fig. 29) or ~58% of theoretical stocking. Rainbow trout ranged from 156 370 mm (mean = 234.5) and included age-groups 1+ - 3+ (Fig. 30). Back-calculated ages for the Halfway sample is provided in Table 7; incremental growth increased from ~80 to 100 mm from age 2 to age 3, respectively. The body:scale relationship displayed a reasonable fit resulting in a high correlation coefficient (Fig. 31). Similarly, the length-weight relationship was well-correlated, although growth was slightly less than proportional (Fig. 32). Accordingly, the slope coefficient is slightly below average, yet the fish visually appear healthy (Plate 6). Consistent with other observations that include this stock, individuals were maturing but maturation was generally observed 1600 Pennask Pennask Premier Premier Pennask-Premier Pennask-Premier 1400 1200 Number of fish released 1000 800 600 400 200 0 1998 1999 2000 2001 2002 2003 Figure 29. Rainbow trout stock selection and stocking rate at Halfway Lake from 1998 to 2003. February 2004 29
20 18 1+ n=64 16 14 Percent occurrence 12 10 8 6 2+ 3+ 4 2 0 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 Size category (mm) Figure 30. Length frequency distribution of rainbow trout sampled in Halfway Lake on October 1, 2003. among fish >250 mm. Table 7. Back-calculated lengths at successive annuli for rainbow trout in Halfway Lake. 95% confidence limits are shown in brackets. Age-group n Age Class I II III 1+ 5 96 (7.71) 2+ 9 96.1 174.2 (2.48) (10.88) 3+ 5 95.1 181.3 279.6 (5.36) (18.56) (23.42) Grand Average 95.7 177.8 279.6 February 2004 30
450 400 Fork length (mm) = 51.4679 + 2.5457 (Scale radius); r 2 =0.90; n=19 350 300 Fork length (mm) 250 200 150 100 50 0 0 20 40 60 80 100 120 140 Scale radius (mm X60) Figure 31. Body:scale relationship for rainbow trout in Halfway Lake. 6.5 Ln (W) = -10.5296 + 2.8428 Ln (FL); r 2 =0.99; n=64 6 5.5 Ln Weight (g) 5 4.5 4 3.5 5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 6 Ln Fork length (mm) February 2004 31
Figure 32. Length-weight relationship for rainbow trout sampled in Halfway Lake on October 1, 2003. 3.2.7 Help Lake The catch composition (n=223) from a single sinking gillnet set on September 30, 2003 consisted of 50% rainbow trout (CPUE=5.29), 41% finescale sucker (CPUE=4.38), 7% Eastern brook trout (CPUE=0.76) and 2% burbot (CPUE=0.19). The same choice of rainbow trout stocks selected for Aid and Comfort lakes have been planted in Help Lake at a stocking rate of 2000 fish per year (Fig. 33) or ~41% of theoretical stocking capacity. Similarly, the timing of stock introductions has followed the same pattern recorded for the other local lakes from 1998 to 2003. There is no record of previous brook trout or burbot release to Help Lake; their occurrence may be natural owing to the lakes connectivity to Succour Creek and hence the Columbia River, or, an unauthorized introduction. The size distribution of rainbow trout ranged from 112 286 mm (mean = 188.4) and includes age-groups 1+ to 3+ (Fig. 34). Back-calculated size-at-age determinations appear in Table 8, based on the body:scale relationship provided in Figure 35. The lower correlation coefficient is again attributed to the high degree of 2500 2000 Pennask Pennask Premier Premier Pennask-Premier Pennask-Premier Number of fish released 1500 1000 500 0 1998 1999 2000 2001 2002 2003 February 2004 32
Figure 33. Rainbow trout stock selection and stocking rate at Help Lake from 1998 to 2003. 18 16 1+ 2+ n=111 Percent occurrence 14 12 10 8 6 3+ 4 4+ 2 0 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 Size category (mm) Figure 34. Length frequency distribution of rainbow trout sampled in Help Lake on September 30, 2003. scatter about the regression line due to considerable variation in growth among Table 8. Back-calculated lengths at successive annuli for rainbow trout in Help Lake. 95% confidence limits are shown in brackets. Age-group n Age Class I II III IV 1+ 5 68 (8.61) 2+ 13 65.9 143.2 (4.75) (7.28) 3+ 10 64.5 131.9 190.8 (7.67) (13.92) (12.08) 4+ 1 66.9 120.8 207 257.3 Grand Average 66.1 132.0 198.9 257.3 February 2004 33
350 Fork length (mm) = 36.6099 + 2.8328 Scale radius; r 2 = 0.68; n = 29 300 250 Fork length (mm) 200 150 100 50 0 0 10 20 30 40 50 60 70 80 90 Scale radius (x 60 mm) Figure 35. Body:scale relationship for rainbow trout in Help Lake. individual fish. Low lake productivity (TDS=150), early maturity (generally, for fish >185 mm), and coarsefish interactions are again suspected as causative factors governing the growth characteristics of this population. Near-equal incremental rainbow growth from age 2 to age 4 and the greater size distribution of the catch suggest that competitive interactions may not be as intense as that observed in Comfort Lake given the apparent lower density of coarsefish (i.e., based on a lower CPUE in the sample). The length-weight relationship for rainbow trout provides further evidence where a slightly improved coefficient (e.g., 2.84 in Help vs 2.62 in Comfort) was evident, albeit that growth remained less than proportional (Fig. 36). Finescale sucker frequency distribution ranged from 117 225 mm (mean = 170.2; Fig. 37) and corresponding weights ranged from 20 148 g. The length-weight relationship for this population is provided in Figure 38 which suggests a slightly above-average slope coefficient. Eastern brook trout ranged in length from 124 335 mm (mean = 228.2) and corresponding weights varied from 18 444 g (Fig. 39). Above average condition February 2004 34
was again evident for the sample (Fig. 40). Growth characteristics favouring the 6 5.5 5 Ln (W) = -10.6184 + 2.8449 Ln (FL); r 2 =0.99; n=111 Ln Weight (g) 4.5 4 3.5 3 2.5 4.6 4.8 5 5.2 5.4 5.6 5.8 Ln Fork length (mm) Figure 36. Length-weight relationship for rainbow trout sampled in Help Lake on October 1, 2003. 20 18 16 n=34 14 Percent occurrence 12 10 8 6 4 2 0 120 130 140 150 160 170 180 190 200 210 220 Size category (mm) February 2004 35
Figure 37. Length frequency distribution of finescale sucker sampled in Help Lake on October 1, 2003. 5.5 5 Ln (W) = -11.9648 + 3.1324 Ln (FL); r 2 =0.99; n=32 4.5 Ln Weight (g) 4 3.5 3 2.5 4.7 4.8 4.9 5 5.1 5.2 5.3 5.4 5.5 Ln Fork length (mm) Figure 38. Length-weight relationship for finescale sucker sampled in Help Lake on October 1, 2003. February 2004 36
20 18 n=16 16 14 Percent occurrence 12 10 8 6 4 2 0 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 Size category (mm) Figure 39. Length frequency distribution of Eastern brook trout sampled in Help Lake on October 1, 2003. 6.5 6 Ln (W) = -12.7921 + 3.2625 Ln (FL); r 2 =0.99; n=16 5.5 5 Ln Weight (g) 4.5 4 3.5 3 2.5 4 4.5 5 5.5 6 6.5 Ln Fork length (mm) Figure 40. Length-weight relationship for Eastern brook trout sampled in Help Lake on October 1, 2003. February 2004 37
highest slope coefficient among representative species may in part be due to a low brook trout population density displaying a competitive advantage over the other species. Burbot ranged in length from 158 304 mm (mean = 230.3) and corresponding weights varied from 24 150 g. Low sample size restricted further analysis. Representative photos of the species complex are shown in Plate 7. 3.2.8 Rockbluff Lake Rainbow trout (n=49; CPUE=2.58) were the only species encountered in a single sinking gillnet set on October 17, 2003. Multiple stocks have been planted over the past six years: Badger-Tunkwa stock was introduced from 1998 to 2000, Premier stock was released in 2001 and switched to Tunkwa stock over the last two years (Fig. 41). The stocking rate for Rockbluff (Quartz) Lake has remained at 3000 yearlings per year over the same duration and is currently held at 39% of theoretical stocking capacity. The size distribution of rainbow trout ranged from 144 445 mm 3500 3000 Badger-Tunkwa Badger-Tunkwa Badger-Tunkwa Premier Tunkwa Tunkwa 2500 Number of fish released 2000 1500 1000 500 0 1998 1999 2000 2001 2002 2003 Figure 41. Rainbow trout stock selection and stocking rate at Rockbluff Lake from 1998 to 2003. February 2004 38
(mean = 270.1) and included age-groups 1+ - 4+ (Fig. 42). Back-calculated size-atage determinations are provided in Table 9 based on the body:scale relationship in Figure 43. The latter relationship is highly significant (r 2 =0.93) in consideration of 12 2+ n=49 10 1+ 3+ Percent occurrence 8 6 4 4+ 2 0 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 Size category (mm) Figure 42. Length frequency distribution of rainbow trout sampled in Rockbluff Lake on October 17, 2003. Table 9. Back-calculated lengths at successive annuli for rainbow trout in Rockbluff Lake. 95% confidence limits are shown in brackets. Age-group n Age Class I II III IV 1+ 5 121.6 (4.19) 2+ 12 123.4 195.4 (5.35) (18.35) 3+ 5 124.9 197.2 291.9 (4.30) (10.08) (21.87) 4+ 2 127.5 207.3 278.3 367.7 (7.74) (4.47) (42.94) (8.75) Grand Average 124.4 200.0 285.1 367.7 February 2004 39
500 450 Fork length (mm) = 78.5516 + 2.2815 (Scale radius); r 2 =0.93; n=24 400 350 Fork length (mm) 300 250 200 150 100 50 0 0 20 40 60 80 100 120 140 160 180 Scale radius (mm X60) Figure 43. Body:scale relationship for rainbow trout in Rockbluff Lake. February 2004 40
limited scatter about the trend line. Incremental growth was constant from ages 2 through 4 (refer to Table 9) and the majority of fish >240 mm were maturing. Despite the lakes moderate to high productivity (TDS=350), growth is slightly less than proportional; early maturation may contribute to the lower coefficient observed (Fig. 44). This growth characteristic may also account for the larger overlap between agegroups 2+ and 3+ where non-maturing individuals (generally females) were able to achieve a larger size during their third summer (refer to Fig. 42). The size distribution and average condition of representative individuals are shown in Plate 8. 3.2.9 Rocky Point Lake Eighty-eight rainbow trout (CPUE=4.89) were captured in a single sinking gillnet set on October 2, 2003. With the exception of Premier stock planted in 1999, Tunkwa stock has since been planted in Rocky Point Lake at a stocking rate of 8000 fall fry per year (Fig. 45). The size distribution ranged from 160 430 mm (mean = 281.2) 7 6.5 6 Ln (W) = -10.8296 + 2.8985 Ln (FL); r 2 =0.99; n=49 Ln Weight (g) 5.5 5 4.5 4 3.5 4.5 4.7 4.9 5.1 5.3 5.5 5.7 5.9 6.1 6.3 6.5 Ln Fork length (mm) Figure 44. Length-weight relationship for rainbow trout sampled in Rockbluff Lake on October 17, 2003. February 2004 41
9000 8000 Premier Tunkwa Tunkwa Tunkwa Tunkwa 7000 Number of fish released 6000 5000 4000 3000 2000 1000 0 1999 2000 2001 2002 2003 Figure 45. Rainbow trout stock selection and stocking rate at Rocky Point Lake from 1999 to 2003. and included age-groups 1+ - 5+ (Fig. 46). Notwithstanding, the length frequency distribution was skewed to the younger age-groups. Back-calculated ages are based on a body:scale relationship that displays a high degree of scatter and hence, a lower correlation value (r 2 =0.72; Fig. 47); average annual increments in growth steadily decline beyond their second year (Table 10) and may be related to early maturation in this stock (i.e., majority of fish maturing >250 mm) or low lake productivity (TDS=90). The rather large increment in their first year suggests that fish released in the fall, continue to feed actively until ice-up. Growth was again less than proportional (b=2.75; Fig. 48) and fish were generally in fair condition (Plate 9); two of the larger individuals captured in the sample had not recovered from their kelted condition following spawning (i.e., despite rearing another summer in the lake). February 2004 42
16 14 3+ n=68 12 4+ Percent occurrence 10 8 6 1+ 2+ 4 2 5+ 0 160 180 200 220 240 260 280 300 320 340 360 380 400 420 Size category (mm) Figure 46. Length frequency distribution of rainbow trout sampled in Rocky Point Lake on October 2, 2003. 450 400 Fork length (mm) = 92.6737 + 2.0092 (Scale radius); r 2 = 0.72; n = 19 350 300 Fork length (mm) 250 200 150 100 50 0 0 20 40 60 80 100 120 140 160 Scale radius ( X60 mm) Figure 47. Body:scale relationship for rainbow trout in Rocky Point Lake. February 2004 43
Table 10. Back-calculated lengths at successive annuli for rainbow trout in Rocky Point Lake. 95% confidence limits are shown in brackets. Age-group Age Class I II III IV V 1+ 111.1 2+ 123.1 176.2 (6.40) (34.63) 3+ 124.3 198.6 261.2 (1.95) (14.80) (15.82) 4+ 121.3 192 265 323 (4.72) (19.15) (26.24) (11.75) 5+ 117.2 176.1 252.1 318.3 374.8 Grand Average 119.4 185.7 259.4 320.7 374.8 February 2004 44
7 6.5 6 Ln (W) = -10.0424 + 2.7516 Ln (FL); r 2 =0.98; n=68 Ln Weight (g) 5.5 5 4.5 4 3.5 5 5.2 5.4 5.6 5.8 6 6.2 Ln Fork length (mm) Figure 48. Length-weight relationship for rainbow trout sampled in Rocky Point Lake on October 2, 2003. 3.2.10 Rosebud Lake Seventy rainbow trout (CPUE=4.24 fish/hr) were captured in a single sinking gillnetset on October 8, 2003. Fraser Valley Trout Hatchery domestic stock has been introduced since 1999 at a stocking rate of 3000 fingerlings per year; additional stocks planted in 2003 include Gerrard rainbow (1000 yearlings) raised at Selkirk College as part of their educational program (Fig. 49). The size distribution of rainbow trout ranged from 153 433 mm (mean = 253.7) and includes age-groups 1+ - 4+ (Fig. 50). The length frequency distribution is highly skewed to yearling fish that are largely represented by Gerrard stock judging by the even pattern of circuli spacing on scales and recorded size at release (22.7 g). The missing age-group (2+) and low representation of older age classes in the population suggests extremely low survival of domestic rainbow in Rosebud Lake. Poor survival may be related to seasonal metabolic processes that provide environmental extremes within this shallow, hardwater basin. Back-calculated ages based on the body: scale February 2004 45
3500 3000 Fraser Valley 3N Fraser Valley Fraser Valley Fraser Valley Fraser Valley Number of fish released 2500 2000 1500 1000 Gerrard 500 0 1999 2000 2001 2002 2003 2003 Figure 49. Rainbow trout stock selection and stocking rate at Rosebud Lake from 1996 to 2002. 30 1+ n=70 25 20 Weight (g) 15 10 3+ 4+ 5 0 150 170 190 210 230 250 270 290 310 330 350 370 390 410 430 Size category (mm) Figure 50. Length frequency distribution of rainbow trout sampled in Rosebud Lake on October 8, 2003. February 2004 46
relationship (Fig. 51) are provided in Table 11 but caution is advised due to the limited number of domestic age-groups in the data set; size-at-age determinations for the Gerrard stock have not been included to avoid confusion in growth rates Table 11. Back-calculated lengths at successive annuli for domestic rainbow trout in Rosebud Lake. 95% confidence limits are shown in brackets. Age-group n Age Class I II III IV 1+ 3 55.3 (20.52) 2+ 3+ 6 73.3 167.9 265.6 (14.5) (15.93) (12.82) 4+ 2 53.6 95.8 226 351.7 (2.09) (49.0) (1.78) Grand Average 60.7 131.9 245.8 351.7 February 2004 47
500 450 Fork length (mm) = 22.6030 + 2.5705 (Scale radius); r 2 =0.92; n=11 400 350 Fork length (mm) 300 250 200 150 100 50 0 0 20 40 60 80 100 120 140 160 Scale radius (mm X60) Figure 51. Body:scale relationship for rainbow trout in Rosebud Lake. between stocks. A review of the length-weight relationship indicates proportional growth among individuals in the sample and an average condition prevails (Fig. 52; Plate 10). For the purpose of this investigation, both stocks of rainbow trout have been included to evaluate overall condition. From the available data for Fraser Valley rainbow trout, a maturing condition was observed for fish >240 mm. 3.2.11 Solar Lake Rainbow trout (n=33; CPUE=1.61 fish/hr) was the only species recorded in the catch during a single sinking gillnet set on October 16, 2003. Solar Lake was a candidate lake for winter aeration during the mid-1980 s since it was known to partially winterkill; the presence of relatively mild winters over the last decade has minimized the extent of oxygen depletion under ice cover and stocking has continued in the absence of further management intervention (i.e., aeration). Tunkwa stock was planted into Solar Lake from 1998-99, changed to Premier stock in 2000-01 and returned to Tunkwa stock over the last two years (Fig. 53). The size distribution of the catch (Fig. 54) varied from 225 560 mm (mean = 292.6), included age-groups February 2004 48
7 6.5 6 Ln (W) = -11.1415 + 2.9633 Ln (FL); r 2 =0.98; n=70 Ln Weight (g) 5.5 5 4.5 4 3.5 4.5 5 5.5 6 6.5 Ln Fork length (mm) Figure 52. Length-weight relationship for rainbow trout sampled in Rosebud Lake on October 8, 2003. 1200 1000 Tunkwa Tunkwa Premier Premier Tunkwa Tunkwa Number of fish released 800 600 400 200 0 1998 1999 2000 2001 2002 2003 Figure 53. Rainbow trout stock selection and stocking rate at Solar Lake from 1998 to 2003. February 2004 49
16 14 2+ n=33 12 3+ Percent occurrence 10 8 6 4 4+ 5+ 2 0 220 240 260 280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 Size category (mm) Figure 54. Length frequency distribution of rainbow trout sampled in Solar Lake on October 16, 2003. (2+ - 5+ and was highly skewed to fish <300 mm. The lower percentage of large fish in the sample would suggest poor survival to adulthood that may be linked to poor over-winter survival due to ongoing low oxygen concentrations under ice cover. Size-at-age determinations appear in Table 12 based on the body:scale relationship (r 2 =0.96) provided in Figure 55. Owing to inherent high lake productivity, individuals, on average, demonstrated sustained incremental growth up to year 4 (refer to Table 12) yet fish weight was not proportional to fish length (Fig. 56) suggesting that body condition is below expected growth. Representative samples of the catch are shown in Plate 11. Early maturation (for males >250 mm) was again characteristic of the sample; this condition was more frequent in smaller males that dominated the catch, whereas females displayed early maturation at a larger size (generally > 270 mm). Table 12. Back-calculated lengths at successive annuli for rainbow trout in Solar Lake. 95% February 2004 50
confidence limits are shown in brackets. Age-group 1+ n Age Class I II III IV V 2+ 13 84.5 166.9 (3.57) (19.18) 3+ 1 81 128.5 252.5 4+ 1 94.5 171.6 309.9 377.6 0 0 0 0 5+ 2 87.4 176.1 271.6 411.9 456.8 (9.10) (43.70) (38.86) (40.10) (51.20) Grand Average 86.7 160.8 278.0 394.8 456.8 February 2004 51
600 500 Fork length (mm)= 36.1974 + 2.5705 (Scale radius); r 2 =0.96; n=17 400 Fork length (mm) 300 200 100 0 0 50 100 150 200 250 Scale radius (mm X60) Figure 55. Body:scale relationship for rainbow trout in Solar Lake. February 2004 52
8 7.5 7 Ln (W) = -10.0218 + 2.7712 Ln (FL); r 2 =0.98; n=33 Ln Weight (g) 6.5 6 5.5 5 4.5 5.2 5.4 5.6 5.8 6 6.2 6.4 Ln Fork length (mm) Figure 56. Length-weight relationship for rainbow trout sampled in Solar Lake on October16, 2003. 3.2.12 Three Island Lake Rainbow trout (n=39; CPUE=2.17 fish/hr) was the only species sampled in a single sinking gillnet set on October 2, 2003. Three Island Lake has been consistently planted with Tunkwa stock over the last five years at a rate of 5000 fall fry per year (Fig. 57) or ~77% of theoretical stocking. Prior stocking with Premier stock was undertaken in 1999. The size distribution of the catch ranged from 158 350 mm (mean = 235.9) and included age-groups 1+ - 4+ (Fig. 58); a more even size distribution was evident for the sample. The body: scale relation demonstrated limited scatter (r 2 =0.92; Fig. 59) and annual increments displayed continued growth up to 4 years of age (Table 13). Consistent with low lake productivity (TDS=70), however, body weight of individual fish was not proportional to body length and the majority of fish were observed in fair condition (Fig. 60; Plate 12). Further examination of the body cavity indicated early maturity among smaller males (for individuals >230 mm) and larger females (for individuals > 280 mm). February 2004 53
6000 5000 Premier Tunkwa Tunkwa Tunkwa Tunkwa Number of fish released 4000 3000 2000 1000 0 1999 2000 2001 2002 2003 Figure 57. Rainbow trout stock selection and stocking rate at Three Island Lake from 1999 to 2003. 20 18 1+ n=39 16 14 Percent occurrence 12 10 8 2+ 3+ 4+ 6 4 2 0 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 Size category (mm) Figure 58. Length frequency distribution of rainbow trout sampled in Three Island Lake on October 2, 2003. February 2004 54
400 350 Fork length (mm) = 83.3990 + 1.9512 (Scale radius); r 2 = 0.93; n = 21 300 250 Fork length (mm) 200 150 100 50 0 0 20 40 60 80 100 120 140 160 Scale radius (x60 mm) Figure 59. Body:scale relationship for rainbow trout in Three Island Lake. Table 13. Back-calculated lengths at successive annuli for rainbow trout in Three Island Lake. 95% confidence limits are shown in brackets. Age-group n Age Class I II III IV 1+ 4 104.5 (3.78) 2+ 5 105.9 170.4 (4.51) (9.02) 3+ 7 109.8 167.9 246.7 (2.34) (7.49) (20.09) 4+ 5 109.3 154.1 208.1 314.4 (2.33) (9.17) (13.00) (15.21) Grand Average 107.4 164.1 227.4 314.4 February 2004 55
6.5 6 Ln (W) = -10.4104 + 2.8191 Ln (FL); r 2 =0.99; n=39 5.5 Ln Weight (g) 5 4.5 4 3.5 5 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 Ln Fork length (mm) Figure 60. Length-weight relationship for rainbow trout sampled in Three Island Lake on October 2, 2003. 3.3 Growth, stocking density and angler use A comparison of rainbow trout growth characteristics across the 12 study lakes suggests a wide range of deviation from proportionality (i.e., from 2.62 3.00 (mean = 2.85); the highest value was determined for Alces and the lowest value was observed at Comfort Lake (Fig. 61). The higher coefficients approaching isometric growth were generally associated with monoculture fisheries with low stocking density while the lower values were generally associated with lakes characteristic of high stocking density and/or coarsefish populations. An absence of theoretical stocking calculations exist for those lakes where shoal area has not yet been completed. With respect to the length-weight relationship of individual rainbow trout populations, the importance of stocking density cannot be over-stated in consideration of densitydependent growth coupled with lake productivity. Moreover, stocking densities in February 2004 56
combination with the appropriate management regime are generally intended to meet a specific management objective. The array of management regimes can vary from high turnover put and take fisheries to low turnover quality fisheries; the latter 3.1 3 Slope coefficient % Theoretical 0.9 0.8 Deviation from isometric growth 2.9 2.8 2.7 2.6 2.5 0.7 0.6 0.5 0.4 0.3 0.2 0.1 Percentage of theoretical capacity 2.4 0 Comfort Halfway Rocky Point Solar Three Island Help Aid Rockbluff Rosebud Box Cameron Alces Figure 61. A comparison of rainbow trout length-weight relationships among representative study lakes. option is generally associated with more restrictive regulations to meet quality angling objectives. In the present context, the 12 study lakes are more representative of put and take fisheries where minimum restriction is emphasized. Stocking densities are purposely set below the theoretical stocking rates of individual lakes to ensure that proportional growth is achieved. Further fine-tuning of stocking rate is dependent upon the amount of angler use and corresponding returns to the creel. In this instance, angler use at a few of the selected lakes, monitored from aerial counts, is considered low and without any apparent increasing trend; SLIM counts for 2003 have been purposely avoided due to lower than expected numbers associated with forest closure/ fire hazard rating during the summer of 2003. The higher coefficient observed for Alces Lake, may in part be due to both a higher catch (Fig. 62) and lower stocking rate that reduces intra-specific competition. Low angler use and high corresponding CPUE s from gillnet surveys may explain the lower coefficient of fish in lakes with a more balanced size structure (e.g., Three Island, February 2004 57
Rocky Point, Rockbluff and to a lesser extent Halfway) and assumed higher 1800 1600 1996 2002 1400 Number of angler days per year 1200 1000 800 600 400 200 0 Rocky Point Three Island Halfway Rockbluff Alces Solar Figure 62. A comparison of angler use at selected lakes based on available SLIM data. Data summarized for individual years. density of fish. There are no angler use statistics available for West Kootenay lakes other than anecdotal information pertaining to relative use in which case Rosebud likely receives the greatest amount of annual pressure from Trail and Castlegar residents (J. Bell, Fisheries Technician, Nelson, B.C.; pers. comm.). 4.0 Discussion The results of the 2003 small lakes assessment program are particularly interesting in light of the nature of candidate lakes that are generally of low biological productivity and characteristic of rainbow trout stocks of a non-special designation. Only two water bodies are considered under special management status in regard to special angling regulations (Alces Lake; no bait, artificial fly, winter closure) or reduced harvest (Rosebud; 2 fish daily limit). Moreover, none of the selected lakes are considered to support exceptional angler use due to an inherent, above-average February 2004 58
quality of the fishery. Earlier stock assessments have been conducted on seven of the selected lakes during the mid to late 1980 s (Rockbluff, Comfort, Help, Aid and Solar; Ministry of Water, Land and Air Protection; file data) or early 1990 s (Three Island and Halfway; RL&L Environmental Services Ltd.; 1991 and 1993, respectively) and provide some insight on future management direction. As a preface to further discussion on fisheries management goals, interpretations consider the representativeness of each fish sample at selected lakes recognizing 1) the size selectivity of the sampling gear and 2) end of season growth rates that are likely typical of the slower growing individuals in the population, since the faster growing members are often removed by the fishery. A general trend of poor to fair isometric growth exists for most of the representative samples among the lakes surveyed. This condition was particularly evident for those lakes with coarsefish populations; a comparison of coarsefish catch rates between years (Ministry of Water, Land and Air Protection; Cranbrook, B.C.; file data) suggests a burgeoning increase in coarsefish numbers in Comfort Lake that is likely responsible for the poorest growth among study lakes. A negative correlation seems apparent between coarsefish density and proportionality for the three lakes in the Succour Creek drainage; the highest coarsefish catch per unit was observed in Comfort Lake (7.56 fish per hour) while the lowest CPUE was observed in Aid Lake (0.39 fish per hour). In contrast, the highest isometric growth coefficient was determined for Aid Lake while the lowest value was afforded to Comfort Lake rainbow trout. Owing to the nature of surface water interconnectivity between these lake basins and coarsefish dynamics, growth of rainbow trout populations in Help and Aid lakes is expected to decline into the future. Moreover, the recent occurrence of two other species in the lake chain (i.e., brook trout and burbot; whether natural or unauthorized introduction) suggests that competitive interactions between species and/or predation will likely exert certain pressures on future rainbow trout survival. Annual releases at present stocking levels should continue for Help and Aid Lake in the interest of diversifying angling opportunity in the area, however, future monitoring will be required to determine when further stocking is unwarranted. Alternatively, if suitable rainbow trout stocks compatible with coarsefish populations, become available in the future, continued stocking of all three lakes is recommended. Outplanting of Blackwater stock in Help and Aid lakes is not recommended at this time owing to inherent behaviour that would likely result in their downstream migration as evidenced in other small lakes, with outlet channels, in the Kootenay February 2004 59
Region and B.C. southern interior (Oliver 2003). For monoculture lakes with apparent low angling pressure (e.g., Halfway, Rockbluff, Rocky Point, Three Island and Solar), early maturation in both males and females may be problematic towards improved trout growth among selected lakes. Early maturation seems more apparent for Tunkwa and Pennask-Premier stocks and may require a shift towards the use of Pennask stock in combination with sterilization techniques presently employed at Kootenay Trout Hatchery. In recognition of the low isometric growth coefficient for fish at Halfway Lake, a shift to triploid Pennask stock and a reduction in stocking rate to 1000 yearlings per year may help resolve the present situation. Despite the highest coefficient among study lakes in 2003, Alces Lake should also be considered as a candidate for triploid introduction due to its connectivity to the Lussier drainage and the provincial fisheries mandate to protect native wildstock in natural waters. The use of heat shock to Pennask eggs may be a cost-effective means of achieving management objectives without the increased expense of AF3N introduction. The condition of rainbow trout under multiple stock fisheries (i.e., Box and Cameron lakes) is particularly interesting. Despite appearances, both rainbow stocks have achieved acceptable growth in the presence of a successful competitor but rainbow populations are highly skewed to younger fish. Despite large differences in Eastern brook trout numbers between lakes (based on large differences in CPUE between lakes), the size structure of each population is more evenly balanced than that observed for rainbow trout at either lake. The fewer number of rainbow trout display a lower deviation from proportional growth, but survival to adulthood would appear somewhat compromised as a consequence of competition or predation. Continued stocking of rainbow trout at current levels is recommended to diversify angling opportunities in the area, but, encouragement of a differential harvest limit for brook trout at Box and Cameron lakes (i.e., a higher daily catch limit) may be beneficial in controlling very large brook trout populations. Alternatively, it would be beneficial to block spawning migrations to the outlet channel at Box Lake to reduce overall recruitment to the system. The introduction of catchable rainbow trout at Box Lake is currently being considered by fisheries management staff; the provision of catchable trout may be an important measure to alter public perception towards black spot disease that currently appears to restrict angler use at this lake. The response of catchables within a mixed stocked fishery will require further monitoring to evaluate February 2004 60
their performance, however, since the results of catchable introductions at Rosen Lake, in the East Kootenay, were not particularly favourable (Oliver 2003). Rosebud Lake provides an interesting contrast in survival between rainbow trout stocks. The results of the 2003 survey demonstrated proportional growth among individuals yet poor survival to adulthood. It is important to recognize that the contribution of Gerrard stock largely overshadows the contribution of Fraser Valley rainbow in the analysis, as well, a missing year class (two year olds) was evident for the latter stock. Although further investigation into Fraser Valley trout survival is warranted, ambient water quality over the last few years may provide some insight. Rosebud Lake supports an abundant macrophyte community and local water chemistry likely supports moderate phytoplankton populations. The high demand for carbon to meet the photosynthetic requirements of both macrophyte and phytoplankton communities may cause a shift in CO 2 equilibrium during the summer growing season that elevates ph to levels in excess of 9.0; this occurrence seems plausible given the late season ph value of 8.9 at time of survey (i.e., end of the growing season). Supporting lines of evidence were apparent by the high amount of calcium carbonate precipitate on plants or submerged woody debris within the littoral zone that normally occurs in calcareous hardwater lakes with high ph values (Wetzel 1975). Given the differences in the genetic make-up between Fraser Valley and Gerrard stock, domestics may have a lower ph tolerance than interior stocks of rainbow trout. A higher summer ph would explain the missing year class and overall low survival during hot, dry summers that have been experienced in the recent past. The cumulative effect of high ph and elevated surface temperature could place undue physiological stress on Fraser Valley stocks (i.e., stress that hasn t been observed among other interior stocks evolving under naturally high ph regimes). Notwithstanding these concerns, partial winter-kill cannot be ruled out owing to the high macrophyte community present and previous anoxic conditions below 4.5 m, measured in late spring (J. Bell, Fisheries Technician; pers. comm.). Further examination of summer ph is warranted and investigations could extend to caged experiments with Fraser Valley stock in surface waters to corroborate potential mortality. Similarly, continued monitoring of late winter oxygen profiles would be useful to confirm the effects of lake metabolism under ice cover relative to overwinter rainbow trout survival. In the absence of further study, it may be desirable to introduce alternative interior rainbow stocks at present stocking levels or consider catchable introductions. February 2004 61
As a final note, the introduction of Eastern brook trout into Comfort, Help and Box lakes suggest the need for heightened public awareness to avoid both the ecological and legal consequences of unauthorized introductions into provincial waterbodies. Disregard for the importance of maintaining current management strategies can severely compromise both management objectives and the long-term maintenance of the native species complex. Future efforts/actions are warranted to dissuade the public from further inter-basin transfers. 5.0 Literature Cited Bagenal, T.B. and F.W. Tesch. Age and growth. Pages101-136 in T.B. Bagenal (ed.) Methods for assessment of fish production in fresh waters. Blackwell Scientific Publications Ltd., Oxford, England. Ministry of Water, Land and Air Protection, Cranbrook, B.C. Oliver, G.G. 2003. Kootenay Region small lakes stocking assessment: 2002. Prepared for Ministry of Water, Land and Air Protection, Cranbrook, B.C. Prepared by GG Oliver and Associates Environmental Science, Cranbrook, B.C. 51 p + appnds. RL&L Environmental Services Ltd. 1991. A Fisheries Investigation of Three Island Lake. Prepared for Mica Fisheries, Technical Committee, Nelson, B.C. Prepared by RL&L Environmental Services Ltd, Edmonton, AB. 31 p + appnds. RL&L Environmental Services Ltd. 1991. A Fisheries Investigation of Halfway Lake. Prepared for Mica Fisheries, Technical Committee, Nelson, B.C. Prepared by RL&L Environmental Services Ltd, Vancouver, B.C.. 26 p + appnds. Ryder, R.A., S.R., Kerr, K.H. Loftus, and H.A. Regier. 1974. The morphoedaphic index, a fish yield estimator a review and evaluation. Journal of the Fisheries Research Board of Canada 31:663-688. Wetzel, R.G. 1975. Limnology. W.B.Saunders Co., Philadelphia. February 2004 62
APPENDIX 1 Bathymetric maps for selected lakes Gillnet locations are indicated with an arrow February 2004 63
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APPENDIX 2 Biological data Maturity Classifications: IM = Immature M = Mature MT = Maturing K = Kelt February 2004 74
Lake: Aid Date: 29-Sep-03 TDS (ppm): 150 ph: 8.1 Species: Gillnet Deployment Time (hrs): 23 Weight Length Sex Maturity Stomach Weight Length Sex Maturity Stomach (g) (mm) contents (g) (mm) contents Rainbow trout 202 260 F MT 72 192 24 129 104 208 F MT 138 242 M MT 90 195 F MT 150 242 F MT 70 185 M MT 146 252 F MT 36 149 30 138 22 122 62 180 F IM 70 186 80 200 66 189 40 151 94 202 F MT 108 208 F MT 68 185 F MT 58 169 F IM 90 214 M MT 100 205 M MT 96 201 M MT 118 211 F MT 78 190 M MT 178 251 F MT 34 150 108 212 M MT 52 172 F IM 52 164 86 192 M MT 114 226 F MT 118 223 F MT 114 223 F MT 84 200 F IM 50 166 24 130 72 188 F IM 64 184 86 204 F IM 62 178 F IM 30 138 88 202 F IM 68 184 F MT 64 176 46 159 86 205 M MT Finescale sucker 110 210 96 193 80 184 16 103 58 170 20 115 14 103 16 112 16 111 February 2004 75
Lake: Alces Date: 16-Oct-03 TDS (ppm): 180 ph: 8.3 Species: Gillnet Deployment Time (hrs): 19.5 Weight Length Sex Maturity Stomach (g) (mm) contents Rainbow trout 704 382 F M 538 370 F M 770 390 M M 420 340 F M 504 350 388 345 M M 532 360 F IM 592 387 M M 388 330 M M 374 328 M M 472 345 M M 192 243 508 361 F M 376 350 M M 282 300 M M 394 341 F M 486 352 F M 390 338 M 560 364 F MT 332 324 F MT 242 280 350 317 M MT 304 303 F IM 280 302 F IM 464 359 M MT 496 346 F MT 348 328 M MT 200 262 M MT 354 313 M MT 532 355 F MT 434 335 F MT 318 311 M MT 408 332 F MT 472 370 M K 660 400 F MT 578 380 F MT 572 364 F EGG BOUND 710 394 M MT 358 320 M MT 364 314 F MT 608 364 F MT 298 297 F IM 318 311 F IM 418 340 M MT 342 328 M MT 458 354 F MT 314 355 M K 222 269 M MT 30 145 IM February 2004 76
Lake: Box Date: 6-Oct-03 TDS (ppm) 90 ph: 8.9 Species: Gillnet Deployment Time (hrs): 21 Weight Length Sex Maturity Stomach Weight Length Sex Maturity Stomach (g) (mm) contents (g) (mm) contents Rainbow trout 674 391 F MT 496 358 M MT 442 336 F MT 244 273 F MT 182 250 F IM 146 232 M MT 256 284 F IM 166 237 M MT 78 193 IM 82 193 M IM 98 210 M IM 86 190 M MT 58 170 F IM 22 128 IM 48 161 28 133 18 114 28 136 38 148 72 183 64 172 90 193 M MT 76 191 M MT 72 178 M MT 82 200 M MT 58 175 M MT 60 163 M MT 64 183 IM 66 174 M MT Black spot disease not as apparent on Rb as Ebt February 2004 77
Eastern brook trout Weight Length Sex Maturity Stomach Weight Length Sex Maturity Stomach (g) (mm) contents (g) (mm) contents 398 316 F M E 436 324 F IM 480 322 M M snails 306 302 F M 260 262 F M E 158 240 F M 456 340 F M E 24 126 F M 228 265 M M E 236 265 M M 202 255 M M E 236 274 M M 420 316 F M E 278 265 M M 446 319 F M E 376 314 F M 358 300 F M E 228 255 M M 398 314 F M E 386 315 F M 192 246 F M E 192 246 F M 300 290 M M snails 310 290 F M 392 296 M M E 122 214 IM 206 255 M M E 380 310 F M 220 260 M M E 242 273 F M 220 267 M M E 184 242 F M 282 274 F M E 184 246 F M 394 324 F M 78 192 F M 486 322 F M 104 208 F 22 123 78 186 M M 20 121 232 259 F M 36 143 260 262 M M 20 118 198 249 M M 20 124 230 266 F M 34 140 80 182 M M 16 118 250 264 M M 22 124 280 283 16 114 152 224 M M 20 117 184 249 34 148 354 307 F M 14 108 246 258 M M 16 110 128 222 M M 20 119 376 316 M M 388 307 202 250 F M 244 272 M M 238 258 M M 206 256 M M 78 189 F M 500 336 M M 80 194 M M 362 307 F M 62 169 M M 220 265 F M 176 235 M M 312 296 F M 126 228 M M 246 277 F M 150 220 M M 254 276 M M 54 168 F M 196 257 M M 362 295 F M 296 308 M M 156 226 M M 322 300 F M 228 254 F M 388 319 F M 304 275 F M 20 118 F M 162 239 F M 18 112 IM 56 160 F M 148 228 IM 224 260 IM 178 243 IM 320 309 M M 132 216 IM 410 331 IM 326 303 M M 198 254 M M 328 298 M M 194 245 M M 276 290 M M 620 366 M M 172 242 M M 366 302 M M 122 212 F M 194 254 M M 156 221 M M 482 335 M M 224 257 M M 504 356 M M 360 311 M M 148 222 F M 36 140 F M 164 233 F M February 2004 78
Eastern brook trout Weight Length Sex Maturity Stomach Weight Length Sex Maturity Stomach (g) (mm) contents (g) (mm) contents 80 188 F M 210 265 F M 82 184 M M 152 230 F M 160 243 162 236 M IM chironomid 32 139 M M 110 198 M M 20 118 M M 104 203 F M 28 132 M M 100 201 M M 14 102 M M 59 163 M IM chironomid 24 125 44 159 M M 22 116 220 253 M M 20 116 382 322 M M 20 119 274 278 F M 20 117 82 202 M M 292 274 282 278 M M 196 236 234 262 M M 242 260 394 320 M M 306 280 404 325 M M 330 317 M M 92 211 IM 244 264 M M 394 309 M M 176 236 M M 250 252 M M 26 133 M M 330 309 M M 18 112 F M 238 275 IM 266 262 M M 194 246 M M 18 116 M M 292 269 F M 22 123 572 354 F M 18 117 138 214 M M 16 119 M M 78 184 IM 302 267 82 185 M M 268 268 100 204 M M 328 302 172 235 F M 462 327 102 199 F M 302 296 214 240 F M 610 383 102 199 M M 364 300 56 170 F M 334 292 366 302 M M 384 308 430 316 F M 190 250 M M 380 306 M M 174 245 F M 318 302 M M 232 266 F M 376 328 M M 402 315 M M 466 322 M M plus 3 unmeasured; all fish heavy with black spot disease February 2004 79
Lake: Cameron Date: 6-Oct-03 TDS (ppm) 40 ph: 8.6 Species: Gillnet Deployment Time (hrs): 17.5 Weight Length Sex Maturity Stomach Weight Length Sex Maturity Stomach (g) (mm) contents (g) (mm) contents Rainbow trout 520 358 F MT chironomids 78 187 356 310 F IM 114 218 IM 400 326 M MT 72 186 IM 122 222 90 197 IM 136 230 IM 86 198 IM 120 216 M MT 98 207 IM 54 170 118 219 IM 54 169 IM 90 193 IM 322 303 M MT 76 194 IM 318 306 F MT 106 213 176 260 F IM 62 169 IM 110 204 M MT 64 182 IM 52 164 68 180 IM 446 344 F MT 76 187 IM 298 287 M MT 184 242 M MT 132 225 M IM 96 203 IM 172 244 F MT 556 358 F MT 132 218 M MT 448 332 F IM 158 244 F IM 98 208 IM 114 215 M MT 72 188 IM 100 200 Im 74 179 IM 86 195 108 200 M MT 88 199 IM 70 181 M MT 104 204 88 194 IM 78 193 IM 350 310 M MT 80 189 IM 116 219 IM 108 208 IM 62 171 IM 92 200 IM 84 191 98 196 M MT plus 2 more unsampled February 2004 80
Eastern brook trout Weight Length Sex Maturity Stomach Weight Length Sex Maturity Stomach (g) (mm) contents (g) (mm) contents 1480 445 F M 394 310 M M 1026 426 F M 210 254 M M 668 349 M M 582 349 F M 404 306 M M 476 327 F M 372 310 F M 290 268 M M 664 362 F M 158 228 M M 668 362 F M 238 280 M M 878 397 M M 258 268 F M 234 257 F M 222 266 F M 870 420 M M 118 218 M M 598 349 M M 176 237 M M 758 385 F M 128 215 M M 912 404 M M 142 220 M M 808 395 M M 172 239 M M 704 365 M M 102 188 M M 242 262 M M 144 221 M M 250 248 F M 110 197 M M 948 403 F M 240 260 M M 714 378 F M 504 327 M M 428 314 M M 806 370 M M 502 344 M M 780 395 M M 972 408 M M 966 419 F M 474 340 F M 778 398 F M 462 328 M M 286 280 M M 292 275 M M 278 273 F M 272 267 M M 272 279 F M 286 275 M M 138 220 F M 526 334 F M 210 258 M M February 2004 81
Lake: Comfort Date: Sept 29 2003 TDS (ppm) 150 ph: 8.5 Species: Gillnet Deployment Time (hrs): 18 Weight Length Sex Maturity Stomach Weight Length Sex Maturity Stomach (g) (mm) contents (g) (mm) contents Rainbow trout 86 205 60 175 94 201 86 200 74 186 88 211 F MT leech 78 187 74 193 M MT empty 110 210 66 196 82 187 84 195 M MT empty 96 206 84 194 F MT 98 210 94 215 F MT insects 70 194 62 176 72 180 84 195 F MT insects 62 182 86 194 36 137 122 225 M MT caddis 110 221 76 185 F MT 78 200 94 206 F MT 134 233 F MT empty 60 174 F IM 126 234 90 200 F MT 86 198 74 194 F MT insects 122 20 70 185 116 225 F MT zooplank 118 232 M MT 198 264 F MT fry 84 207 F IM 94 205 88 215 F MT 80 194 94 195 F MT 86 201 86 195 F MT 56 176 122 219 F MT 86 200 66 186 F IM 60 180 50 168 F MT 116 227 F MT empty 52 164 F IM 110 224 F MT snails 90 209 M MT 82 195 106 215 F MT 132 235 M MT 88 200 60 173 60 180 122 225 F MT 84 193 78 200 86 206 50 168 52 169 64 184 66 183 120 227 F IM 98 211 70 193 84 200 74 195 66 176 106 222 72 188 100 206 76 185 74 191 90 205 104 210 78 182 66 191 64 180 50 168 February 2004 82
Weight Length Sex Maturity Stomach Weight Length Sex Maturity Stomach (g) (mm) contents (g) (mm) contents Eastern brook trout 1180 446 F M 98 206 34 142 100 209 Finescale sucker 152 235 62 172 144 233 70 181 296 281 198 255 310 295 152 225 120 209 46 160 128 225 62 172 284 290 120 216 60 171 56 167 64 172 22 120 142 227 24 131 116 210 46 157 52 160 16 110 174 243 20 120 130 219 34 143 82 191 60 174 74 183 20 121 188 253 56 165 206 260 32 142 62 168 116 212 154 237 46 160 160 234 20 118 118 213 20 120 82 189 18 116 102 199 22 124 160 246 26 129 136 230 22 123 42 155 28 136 64 170 20 119 132 224 plus 78 LNS unsampled, but similar size range 52 165 February 2004 83
Lake: Halfway Date: 1-Oct-03 TDS (ppm) 270 ph: 8.9 Species: Gillnet Deployment Time (hrs): 21 Weight Length Sex Maturity Stomach Weight Length Sex Maturity Stomach (g) (mm) contents (g) (mm) contents Rainbow trout 256 295 M MT 68 178 424 335 M MT 70 178 300 308 F MT 90 202 434 350 F MT 250 281 M MT 518 370 M MT 138 229 M MT 166 254 F IM 66 171 390 324 F MT 66 176 358 317 F MT 56 174 420 329 F MT 128 213 M MT 360 315 F M 70 183 274 289 F MT 62 179 342 310 F MT 150 237 282 292 F MT 76 191 266 294 F MT 82 193 248 275 F M 68 173 264 291 M MT 56 163 228 284 M MT 70 180 282 285 M M 60 165 244 280 M MT 68 185 238 261 M M 72 187 284 293 F MT 74 189 248 285 F MT 70 182 172 248 M MT 50 156 192 270 F IM 60 172 184 245 M MT 88 193 192 266 F MT 60 175 206 268 M MT 66 184 64 176 184 264 F IM 54 162 70 183 170 253 M MT 118 220 F IM 116 214 50 163 70 181 58 167 February 2004 84
Lake: Help Date: 29-Sep-03 TDS (ppm) 150 ph: 8.5 Species: Gillnet Deployment Time (hrs): 21 Weight Length Sex Maturity Stomach Weight Length Sex Maturity Stomach (g) (mm) contents (g) (mm) contents Rainbow trout 128 222 F MT 118 223 F MT 80 205 F IM 120 228 F MT 70 186 F MT 132 235 64 176 64 185 F IM 86 205 136 229 F MT 80 193 F MT 138 240 F MT 78 192 M MT 76 186 M MT 120 222 108 217 F MT 94 205 F MT 82 196 F MT 82 200 F IM 76 195 F IM 62 183 F IM 216 260 F MT 106 217 110 220 F MT 80 192 M MT 100 205 F MT 114 223 F MT 20 122 80 195 F MT 22 124 68 183 152 240 F MT 90 202 F MT 126 230 F MT 80 192 F MT 140 237 M MT 102 216 M MT 46 164 74 193 30 147 90 208 52 167 104 214 F MT 24 130 66 186 F MT 126 229 M MT 80 195 126 230 F MT 66 183 74 194 102 203 F MT 104 210 M MT 66 185 82 199 F MT 60 176 110 232 M MT 60 180 82 197 F IM 70 190 F IM 96 205 F MT 74 194 F IM 104 210 F MT 102 220 F IM 60 172 M MT 122 226 F MT 24 134 126 227 F MT 28 136 82 191 F MT 20 120 118 224 F MT 16 112 74 188 20 119 120 232 F MT 20 118 72 187 F MT 28 137 140 230 F MT 20 126 60 174 F MT 68 188 104 214 F MT 22 126 112 214 F MT 18 117 106 217 F MT 72 183 F MT 92 205 M MT 32 136 82 196 F MT 96 210 96 208 20 122 98 206 M MT 30 140 54 171 32 144 110 218 F MT 22 125 56 177 F IM 26 123 64 177 F IM 22 115 122 224 F MT 20 114 86 195 F MT 20 115 110 213 F MT 48 159 252 286 M MT February 2004 85
Weight Length Sex Maturity Stomach Weight Length Sex Maturity Stomach (g) (mm) contents (g) (mm) contents Eastern brook Trout 242 267 F M 62 181 F IM 224 264 M M 444 335 F M 160 240 F MT 122 223 F MT 18 124 60 178 F IM 252 270 F M 240 271 M M 172 250 F M 76 185 F MT 92 203 F MT 58 173 F IM 190 249 F M 166 238 M M Burbot 24 158 150 304 74 238 62 221 Finescale sucker 74 179 142 212 148 224 132 216 142 225 134 215 94 189 70 176 106 202 20 123 92 190 30 135 60 170 32 139 58 165 66 176 76 180 92 198 70 182 24 123 20 120 56 170 22 120 60 170 34 142 118 209 56 165 58 170 26 125 66 172 20 117 66 174 64 176 plus 58 unsampled, similar size range February 2004 86
Lake: Quartz Date: 16-Oct-03 TDS (ppm) 350 ph: 8.8 Species: Gillnet Deployment Time (hrs): 19 Weight Length Sex Maturity Weight Length Sex Maturity (g) (mm) (g) (mm) Rainbow trout 900 445 78 193 608 382 F MT 82 192 298 294 M MT 110 213 450 358 M MT 54 167 F IM 460 361 M MT 92 200 716 401 F MT 78 185 F IM 380 316 F MT 64 182 F IM 238 283 M MT 94 203 M MT 642 400 M MT 76 190 F 490 353 F MT 66 180 F IM 334 324 M MT 42 144 M IM 474 352 F MT 52 165 M MT 426 331 M MT 296 289 M MT 220 261 274 291 M MT 136 229 F IM 378 323 F MT 164 245 F MT 750 395 F MT 68 174 360 311 F MT 148 236 330 310 F MT 166 242 F IM 470 349 F MT 110 223 M MT 342 315 F MT 186 246 F MT 358 315 M MT 74 192 408 333 M MT 82 196 252 293 M MT 100 200 308 295 F MT 46 158 February 2004 87
Lake: Rocky Point Date: 1-Oct-03 TDS (ppm): 90 ph: 8.5 Species: Gillnet Deployment Time (hrs): 18 Weight Length Sex Maturity Stomach Weight Length Sex Maturity Stomach (g) (mm) contents (g) (mm) contents Rainbow trout 228 273 M 184 255 M MT 54 165 390 343 F MT 132 236 F IM 174 250 F MT 436 336 334 308 F MT 60 167 F MT 54 165 214 269 M MT 50 160 252 292 M MT 252 278 294 308 F MT 314 310 M MT 314 310 M MT 256 272 F MT 454 376 M K 324 304 M MT 360 336 M K 306 299 F M 384 320 250 273 F MT 384 319 M MT 184 264 M MT 78 190 272 298 F IM 294 296 F MT 312 304 M MT 258 284 M M 70 185 F MT 320 305 F MT 458 353 M M 242 280 F IM 118 220 420 345 F MT 332 320 F MT 246 298 F MT 48 163 358 323 F MT 332 310 F MT 174 250 510 358 M M 266 298 F MT 264 283 M MT 156 256 M MT 216 270 196 265 M MT 178 254 F IM 154 252 M MT 210 273 F IM 118 219 282 300 F MT 126 223 M MT 324 320 F MT 348 316 F MT 662 430 F K 324 310 F MT 322 305 F MT 182 255 M MT 388 325 M MT 204 270 M MT 164 246 F IM 240 275 M MT 160 240 186 254 F MT plus 20 (160-270 mm range) 478 414 M K February 2004 88
Lake: Rosebud Date: 8-Oct-03 TDS (ppm): 130 ph: 8.9 Species: Gillnet Deployment Time (hrs): 16.5 Weight Length Sex Maturity Stomach Weight Length Sex Maturity Stomach (g) (mm) contents (g) (mm) contents Rainbow trout 958 428 M M snails 148 230 M IM 984 433 F M E 144 232 M IM 650 386 M IM E 178 248 M IM 528 349 F IM dragonfly larvae, snails 164 237 M IM 216 256 M M chironomids 182 247 M IM 160 238 M IM E 162 238 M IM 90 190 M M 210 260 78 183 F IM E 172 240 F MT 648 388 M IM 168 234 M IM chironomid 600 367 M IM algae, bugs 114 216 646 380 M IM E 166 245 M IM chironomid 138 231 M IM E 218 262 M IM 180 248 M IM E 150 234 M IM 188 247 M IM 120 222 M IM 158 231 M IM 156 234 M IM chironomid 212 262 M IM E 174 246 M IM 136 223 M IM snails, chironomids 140 227 M IM 118 239 M IM snails 202 250 M IM 132 225 M IM 170 242 M 174 246 M IM 112 207 M IM 170 244 M IM 148 234 M IM 166 243 M IM 140 231 M IM 166 242 M IM 130 225 M IM 172 241 M IM 42 153 IM 158 247 M IM 180 231 M IM 174 246 M IM 154 228 M IM 554 370 M IM E 138 230 M IM chironomid 554 364 M IM 142 224 M IM 156 239 M IM 144 238 M IM 166 236 M IM 132 231 M IM 164 240 M IM 162 244 M MT 178 245 M IM 156 227 M IM 154 237 M MT 144 234 M IM 138 230 F IM 146 236 M IM 188 248 M IM 132 223 M IM February 2004 89
Lake: Solar Date: 16-Oct-03 TDS (ppm): 430 ph: 8.9 Species: Gillnet Deployment Time (hrs): 20.5 Weight Length Sex Maturity Stomach (g) (mm) contents Rainbow trout 2016 560 F MT 970 437 M MT 340 297 M MT 1146 487 F MT 742 403 F MT 324 300 F IM 312 325 M MT 268 277 M MT 314 291 M MT 278 274 M MT 230 258 M MT 308 290 M MT 298 298 F IM 252 273 F IM 184 259 F IM 286 288 F IM 340 296 M MT 240 261 M MT 224 270 F IM 196 251 164 237 M MT 178 239 F IM 230 266 F IM 234 273 F IM 232 262 M MT 198 243 F IM 266 285 F IM 140 225 M MT 174 240 M MT 186 245 F IM 158 230 M MT 218 250 M MT 224 265 M MT February 2004 90
Lake: Three Island Date: 1-Oct-03 TDS (ppm): 70 ph: 9 Species: Gillnet Deployment Time (hrs): 18 Weight Length Sex Maturity Stomach (g) (mm) contents Rainbow trout 322 306 378 319 F MT 98 204 382 340 M MT 72 183 58 176 146 230 474 348 M MT 122 218 F MT 422 343 338 320 M M 264 307 M MT 72 188 F MT 60 173 64 176 64 175 74 188 56 169 128 228 F IM 52 170 94 197 60 176 132 228 M M 52 160 416 345 M M 294 284 F M 288 304 F MT 256 285 M M 56 170 374 331 M MT 64 173 176 249 M MT 96 200 440 350 F MT 54 160 52 158 66 175 96 203 264 290 M MT February 2004 91
APPENDIX 3 Photographic plates February 2004 92
Plate 1. Representative catch at Aid Lake. February 2004 93
Plate 2. Representative catch at Alces Lake. February 2004 94
Plate 3. Representative catch at Box Lake. February 2004 95
Plate 4. Representative catch at Cameron Lake. February 2004 96
Plate 5. Representative catch at Comfort Lake. Plate 5. Representative catch at Comfort Lake. February 2004 97
Plate 6. Representative catch at Halfway Lake. February 2004 98
Plate 7. Representative catch at Help Lake. February 2004 99
Plate 7. Representative catch at Help Lake. Plate 8. Representative catch at Rockbluff Lake. February 2004 100
Plate 9. Representative catch at Rocky Point Lake. Plate 10. Representative catch at Rosebud Lake. February 2004 101
Plate 11. Representative catch at Solar Lake. Plate 12. Representative catch at Three Island Lake. February 2004 102