Aerated Lakes Angler Survey: Swan and Spring Lakes, Alberta, 2015

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1 Aerated Lakes Angler Survey: Swan and Spring Lakes, Alberta, 2015

2 The Alberta Conservation Association is a Delegated Administrative Organization under Alberta s Wildlife Act.

3 Aerated Lakes Angler Survey: Swan and Spring Lakes, Alberta, 2015 Nikita Lebedynski Alberta Conservation Association Chippewa Road Sherwood Park, Alberta, Canada T8A 6J7

4 Report Editors PETER AKU KELLEY KISSNER Alberta Conservation Association 50 Tuscany Meadows Cres. NW Chippewa Rd. Calgary, AB T3L 2T9 Sherwood Park, AB T8A 6J7 Conservation Report Series Type Data ISBN: Disclaimer: This document is an independent report prepared by Alberta Conservation Association. The authors are solely responsible for the interpretations of data and statements made within this report. Reproduction and Availability: This report and its contents may be reproduced in whole, or in part, provided that this title page is included with such reproduction and/or appropriate acknowledgements are provided to the authors and sponsors of this project. Suggested Citation: Lebedynski, N Aerated lakes angler survey: Swan and Spring Lakes, Alberta, Data Report, D , produced by Alberta Conservation Association, Peace River, Alberta, Canada. 10 pp + App. Cover photo credit: David Fairless Digital copies of conservation reports can be obtained from: Alberta Conservation Association Chippewa Rd. Sherwood Park, AB T8A 6J7 Toll Free: Tel: (780) Fax: (780) info@ab-conservation.com Website: i

5 EXECUTIVE SUMMARY In Alberta, stocking waterbodies that lack sport fish provides additional angling opportunities in a province with few fish-bearing lakes and high numbers of anglers. Alberta Environment and Parks and Alberta Conservation Association (ACA) stock, aerate and maintain user facilities at many waterbodies throughout Alberta. To prevent winterkill of stocked trout, ACA uses various aeration techniques to enhance winter dissolved oxygen levels at 16 waterbodies across the province. The increased dissolved oxygen levels result in year-round survival of stocked fish and the creation of sport fisheries capable of producing large trout. In the summer of 2015, we conducted angler surveys to assess angling pressure, catch and harvest at two popular aerated lakes in northwest Alberta: Swan and Spring lakes. Both lakes are stocked annually, have a daily bag limit of five fish of any size and are open for angling year round. At Swan Lake, 341 anglers were interviewed, and fishing pressure was estimated to be 31.5 h/ha (95% CI = ) during the survey period. Catch-per-unit-effort (CPUE) was rainbow trout per hour. Total yield of rainbow trout was kg (95% CI = ) or 1.98 kg/ha (95% CI = ). Fish ranged in size from 205 to 585 mm total length (TL) (n = 38). At Spring Lake, 592 anglers were interviewed, and fishing pressure was estimated to be h/ha (95% CI = ) during the survey period. Total CPUE was fish/h and was 0.47 fish/h and 0.03 fish/h for rainbow and brook trout, respectively. Total yield of rainbow trout was kg (95% CI = ) or 16.2 kg/ha (95% CI = ). Total yield of brook trout was 54.7 kg (95% CI = ) or 1.36 kg/ha (95% CI = ). Rainbow trout ranged in size from 208 to 536 mm TL (n = 141). Brook trout ranged in size from 314 to 428 mm TL (n = 15). Key words: aeration, stocking, rainbow trout, brook trout, creel survey, Swan Lake, Spring Lake. ii

6 ACKNOWLEDGEMENTS Funding for this project was provided by Alberta Conservation Association (ACA) and Canada Summer Jobs. Thank you to seasonal staff member Vanessa Ushenko for delivering creel surveys and representing ACA in a professional manner. Thank you to the Municipal District of Greenview No. 16 and Spring Lake Campground for their in-kind support. iii

7 TABLE OF CONTENTS EXECUTIVE SUMMARY... ii ACKNOWLEDGEMENTS... iii TABLE OF CONTENTS... iv LIST OF FIGURES... v LIST OF TABLES... vi LIST OF APPENDICES... vii 1.0 INTRODUCTION STUDY AREA Swan Lake Spring Lake MATERIALS AND METHODS Angler survey Camera-based parameter estimates Data management and analysis RESULTS Swan Lake Spring Lake LITERATURE CITED APPENDICES iv

8 LIST OF FIGURES Figure 1. Map of Swan Lake showing the location of the creel site Figure 2. Map of Spring Lake showing the location of the creel site Figure 3. Figure 4. Figure 5. Length frequency distribution of rainbow trout captured by anglers at Swan Lake, Length frequency distribution of rainbow trout captured by anglers at Spring Lake, Length frequency distribution of brook trout captured by anglers at Spring Lake, v

9 LIST OF TABLES Table 1. Number of available survey units and number of units surveyed during the angler survey at Swan and Spring lakes, vi

10 LIST OF APPENDICES Appendix 1. Angler survey form, Appendix 2. Appendix 3. Appendix 4. Appendix 5. Appendix 6. Flow chart outlining the process used to calculate a whole lake estimate for single-access creel surveys at Swan and Spring lakes during the summer of Summary of information collected during the angler survey at Swan Lake in the summer of Biological information collected from sampled fish during the angler survey at Swan Lake in the summer of Summary of information collected during the angler survey at Spring Lake in the summer of Biological information collected from sampled fish during the angler survey at Spring Lake in the summer of vii

11 1.0 INTRODUCTION In Alberta, stocking waterbodies that lack sport fish provides additional angling opportunities in a province with few fish-bearing lakes and high numbers of anglers. Alberta Environment and Parks (AEP) and Alberta Conservation Association (ACA) stock approximately 300 lakes across the province annually to supplement the roughly 800 lakes with natural sport fish populations (Zwickel 2012). To prevent winterkill of stocked trout, ACA uses various aeration techniques to enhance winter dissolved oxygen levels at 16 waterbodies across the province. The increased dissolved oxygen levels result in year-round survival of stocked fish and the creation of sport fisheries capable of producing large trout. In the summer of 2015, we conducted angler surveys to assess angling pressure, catch and harvest at two popular aerated stocked lakes in northwest Alberta: Swan and Spring lakes. Both lakes are stocked annually, have a daily bag limit of five fish of any size and are open for angling year round. 2.0 STUDY AREA 2.1 Swan Lake Swan Lake (55 3ʹN, ʹW) has a surface area of ha, a maximum depth of 5.6 m and a mean depth of 3.2 m (Brian Lucko, AEP senior fisheries technician, personal communication). It is located in the Peace River drainage, approximately 65 km southeast of Grande Prairie, Alberta (Figure 1). Road access, located on the north side of the lake, is maintained by the Municipal District of Greenview No. 16 and includes a boat launch, two docks, day-use area and free-to-use camping area. Swan Lake is stocked with rainbow trout annually, with 30,000 fish stocked in 2015 (Government of Alberta 2015). 1

12 Figure 1. Map of Swan Lake showing the location of the creel site. Inset map shows the location of the lake within Alberta. 2

2.2 Spring Lake Spring Lake (55 30ʹN, 119 35ʹW) has a surface area of 40.1 ha, a maximum depth of 20.3 m and a mean depth of 8.

Access to the lake, located on the southeast shore, includes a boat launch, one dock and day-use area. Spring Lake Campground is located nearby.

13 2.2 Spring Lake Spring Lake (55 30ʹN, ʹW) has a surface area of 40.1 ha, a maximum depth of 20.3 m and a mean depth of 8.6 m (Brian Lucko, AEP senior fisheries technician, personal communication). It is located in the Peace River drainage, approximately 60 km northwest of Grande Prairie, Alberta (Figure 2). Access to the lake, located on the southeast shore, includes a boat launch, one dock and day-use area. Spring Lake Campground is located nearby. Spring Lake is stocked with rainbow and brook trout in alternating years. In 2015, the lake was stocked with 6,400 rainbow trout, and in 2014, it was stocked with 4,000 brook trout (Government of Alberta 2015). Figure 2. Map of Spring Lake showing the location of the creel site. Inset map shows the location of the lake within Alberta. 3

14 3.0 MATERIALS AND METHODS 3.1 Angler survey We conducted low-effort, single-access-point angler surveys at each lake following methods outlined in Pollock et al. (1994). The lakes were surveyed from May 16 to August 31, Both lakes were surveyed from the boat launch where docks for shore angling were also located. The survey was divided into four strata: weekday mornings ( ), weekday evenings ( ), weekend/holiday mornings ( ) and weekend/holiday evenings ( ). Sunday evenings were considered weekday evenings, and Friday evenings were considered weekend/holiday evenings. Of the 216 possible survey units, 27 (12.5%) and 33 (15.3%) were surveyed at Swan and Spring lakes, respectively (Table 1). Table 1. Number of available survey units and number of units surveyed during the angler survey at Swan and Spring lakes, Lake Strata Available Surveyed % Coverage Swan Weekday a.m Weekday p.m Weekend a.m Weekend p.m Spring Weekday a.m Weekday p.m Weekend a.m Weekend p.m Anglers were interviewed upon completion of their trip. They were asked a series of questions, including number of hours fished; number of fish caught, harvested and released; fishing method used; and travel time (Appendix 1). When permitted, creel staff sampled harvested fish and recorded fork length (FL, mm), total length (TL, mm) and weight (g). 4

15 3.2 Camera-based parameter estimates To increase sampling effort and reduce survey costs, we used trail cameras to estimate hourly angler count data from 0500 to 2200 hours daily. Two cameras were deployed at Swan Lake. One camera was located at the boat launch facing southeast and was positioned to include both docks. The second camera was located on the south side of the lake across from the boat launch facing northwest. At Spring Lake, we used one camera that was located near the boat launch facing north to capture the dock and as much of the lake as possible. Data were downloaded from cameras and battery life was assessed every two weeks. We used the Timelapse2 software (Greenburg 2015) to identify and count the number of anglers in each photograph, providing an instantaneous count of anglers on the lake, within the camera field of view (FOV) (Greenberg 2015). Photos that did not allow anglers to be counted (e.g., due to fog, glare or insufficient light) were excluded from the analysis. Camera counts were then bootstrapped to produce a distribution of mean counts, which when multiplied by the total number of hours in the survey period gave a distribution of mean effort (h) in the camera FOV during the survey period. Because each camera only captured a portion of the lake, the camera-based estimates were spatially corrected to account for the portion of the lake outside the FOV. To determine the spatial correction, creel staff performed instantaneous angler counts at the top of each hour during their shifts at each lake. During these counts, the number of anglers on the lake and the number of anglers inside the camera FOV were recorded. We used the ratio of the number of anglers within the camera FOV to the number of all anglers on the lake to extrapolate angler effort estimates for the whole lake. 3.3 Data management and analysis Before analysis, length-weight plots were used to identify and omit outliers if measurement or recording error was suspected. Angler survey data were submitted to the provincial Fisheries and Wildlife Management Information System maintained by AEP. Bootstrapping was used to derive estimates and associated 95% confidence intervals for the number of anglers and for fish catch, harvest and release (Sullivan 2004). Yield was 5

16 calculated as a product of the average weight of sampled fish and the sum of estimated harvest and release mortality. Angler catch rates were calculated as total ratio estimators following Malvestuto (1983). We estimated release mortality by multiplying the estimated number of each species released by a mortality rate based on previous studies (Schill 1996; Schisler and Bergersen 1996). For rainbow and brook trout, we used release mortality rates of 3.9% for fish caught on a fly, 5.0% for fish caught using hardware without bait, and 32.1% for fish caught using passive bait fishing (Schill 1996; Schisler and Bergersen 1996). Flow charts describing the steps used to calculate estimates are provided in Appendix RESULTS 4.1 Swan Lake Angler survey We interviewed a total of 341 anglers during the survey. These anglers fished for a total of h, catching 119 rainbow trout and harvesting 41 fish (Appendix 3). Based on camera data and angler interviews, an estimated 2,149 anglers (95% CI = 1,882 2,442) fished for 5,130.7 h (95% CI = 4, ,707.3) between May 16 and August 31, Total estimated angling effort between these dates was 31.5 h/ha (95% CI = ) Rainbow trout harvest and yield Anglers harvested an estimated 280 rainbow trout (95% CI = ) at a rate of 0.06 fish/h and released rainbow trout (95% CI = ) at a rate of fish/h. Total catch rate was fish/h. Of the released fish, 44.6 (95% CI = ) perished as a result of hooking mortality. Total yield (harvest + release mortality) was kg (95% CI = ) or 1.98 kg/ha (95% CI = ). Biological data collected from sampled fish are listed in Appendix 4. 6

4.1.3 Rainbow trout population structure Rainbow trout captured by anglers ranged in TL from 205 to 585 mm, with a mean TL of 393.1 ± 17.1 mm (n = 38) (Figure 3). Six (15.

17 4.1.3 Rainbow trout population structure Rainbow trout captured by anglers ranged in TL from 205 to 585 mm, with a mean TL of ± 17.1 mm (n = 38) (Figure 3). Six (15.8%) of the sampled fish were longer than 50 cm. Figure 3. Length frequency distribution of rainbow trout captured by anglers at Swan Lake, 2015 (n = 38). 4.2 Spring Lake Angler survey We interviewed a total of 592 anglers during the survey. These anglers fished for a total of 1,258 h and caught 592 rainbow trout and 38 brook trout, of which 136 rainbow trout and 14 brook trout were harvested (Appendix 5). Based on camera data and angler interviews, an estimated 4,236 anglers (95% CI = 3,815 4,692) fished for 8,996.8 h (95% CI = 8, ,800.4) between May 16 and August 31, Total estimated angling effort between these dates was h/ha (95% CI = ). 7

4.2.2 Rainbow trout harvest and yield Anglers harvested an estimated 973 rainbow trout (95% CI = 893 1,060) at a rate of 0.11 fish/h and released 3,261 fish (95% CI = 2,994 3,553) at a rate of 0.

18 4.2.2 Rainbow trout harvest and yield Anglers harvested an estimated 973 rainbow trout (95% CI = 893 1,060) at a rate of 0.11 fish/h and released 3,261 fish (95% CI = 2,994 3,553) at a rate of 0.36 fish/h. Total catch rate was 0.47 fish/h. Of the released fish, we estimated that (95% CI = ) likely perished as a result of hooking mortality. Total yield (harvest + release mortality) was kg (95% CI = ) or 16.2 kg/ha (95% CI = ). Biological data collected from sampled fish are listed in Appendix Rainbow trout population structure Rainbow trout ranged in TL from 208 to 536 mm (n = 141), with a mean TL of ± 6.7 mm (Figure 4). Four (2.8%) of the sampled fish were longer than 50 cm. Figure 4. Length frequency distribution of rainbow trout captured by anglers at Spring Lake, 2015 (n = 141) Brook trout harvest and yield Anglers harvested an estimated brook trout (95% CI = ) at a rate of fish/h and released fish (95% CI = ) at a rate of fish/h. Total catch rate was 0.03 fish/h. Of the released fish, we estimated that 13.2 (95% CI = ) likely perished as a result of hooking mortality. Total yield (harvest + release 8

19 mortality) was 54.7 kg (95% CI = ) or 1.36 kg/ha (95% CI = ). Biological data collected from sampled fish are listed in Appendix Brook trout population structure Brook trout ranged in TL from 314 to 428 mm (n = 15), with a mean TL of ± 7.3 mm (Figure 5). Percentage Total Length (mm) Figure 5. Length frequency distribution of brook trout captured by anglers at Spring Lake, 2015 (n = 15). 9

20 5.0 LITERATURE CITED Government of Alberta Alberta Environment and Parks fish stocking list Available online at documents/albertafishstockingreport-oct pdf [Accessed January 28, 2016]. Greenberg, S Timelapse2: An image analyser for camera traps. Includes software and manuals. Available online at [Accessed October 15, 2015]. Malvestuto, S.P Sampling the recreational fishery. Pages In: L.A. Nielsen and D.L. Johnson, editors. Fisheries techniques. American Fisheries Society, Bethesda, Maryland, USA. 468 pp. Pollock, K.H., C.M. Jones, and T.L. Brown Angler survey methods and their applications in fisheries management. American Fisheries Society Special Publication pp. Schill, D.J Hooking mortality of bait-caught rainbow trout in an Idaho trout stream and a hatchery: Implications for special-regulation management. North American Journal of Fisheries Management 16: Schisler, G.J., and E.P. Bergersen Post release hooking mortality of rainbow trout caught on scented artificial baits. North American Journal of Fisheries Management 16: Sullivan, M.G Computer simulation of sport fishery parameters. Alberta Fish and Wildlife Division, Unpublished Memorandum, Edmonton, Alberta, Canada. 16 pp. Zwickel, H Sport fishing in Alberta 2010: Summary report from the eighth survey of recreational fishing in Canada. Alberta Sustainable Resource Development, Fisheries Management Branch, Edmonton, Alberta, Canada. 46 pp. 10

21 6.0 APPENDICES Appendix 1. Angler survey form,

22 Appendix 2. Flow chart outlining the process used to calculate a whole lake estimate for single-access creel surveys at Swan and Spring lakes during the summer of Solid lines represent values with no variance, and dashed lines represent data with variance. 12

23 Appendix 3. Summary of information collected during the angler survey at Swan Lake in the summer of RNTR = rainbow trout. Date (d/m/y) Number of anglers Fishing effort (h) RNTR harvested RNTR released 16/05/ /05/ /05/ /05/ /06/ /06/ /06/ /06/ /06/ /06/ /06/ /06/ /07/ /07/ /07/ /07/ /07/ /07/ /07/ /07/ /07/ /07/ /07/ /08/ /08/ /08/ /08/ /08/

24 Appendix 4. Biological information collected from sampled fish during the angler survey at Swan Lake in the summer of RNTR = rainbow trout; test-angled fish denoted by an asterisk (*). Species Fork length (mm) Total length (mm) Weight (g) RNTR RNTR RNTR ,240 RNTR RNTR RNTR ,510 RNTR ,600 RNTR ,005 RNTR ,900 RNTR ,910 RNTR ,600 RNTR ,900 RNTR* RNTR RNTR ,100 RNTR RNTR* ,100 RNTR RNTR ,095 RNTR RNTR RNTR RNTR RNTR RNTR ,950 RNTR RNTR RNTR RNTR

25 Appendix 4. Continued. Species Fork length (mm) Total length (mm) Weight (g) RNTR RNTR* RNTR RNTR RNTR ,565 RNTR RNTR ,055 RNTR RNTR ,245 15

26 Appendix 5. Summary of information collected during the angler survey at Spring Lake in the summer of BKTR = brook trout; RNTR = rainbow trout. Date (d/m/y) Number of anglers Fishing effort (h) BKTR harvested BKTR released RNTR harvested RNTR released 20/05/ /05/ /05/ /05/ /05/ /05/ /06/ /06/ /06/ /06/ /06/ /06/ /06/ /06/ /06/ /06/ /07/ /07/ /07/ /07/ /07/ /07/ /07/ /07/ /08/ /08/ /08/ /08/

27 Appendix 5. Continued. Date (d/m/y) Number of anglers Fishing effort (h) BKTR harvested BKTR released RNTR harvested RNTR released 22/08/ /08/ /08/ /08/

28 Appendix 6. Biological information collected from sampled fish during the angler survey at Spring Lake in the summer of BKTR = brook trout; RNTR = rainbow trout; test-angled fish denoted by an asterisk (*). Species Fork length (mm) Total length (mm) Weight (g) RNTR RNTR RNTR RNTR* ,065 RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR ,120 18

29 Appendix 6. Continued. Species Fork length (mm) Total length (mm) Weight (g) RNTR RNTR RNTR* RNTR* ,040 RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR

30 Appendix 6. Continued. Species Fork length (mm) Total length (mm) Weight (g) RNTR RNTR* RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR ,065 RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR ,610 20

31 Appendix 6. Continued. Species Fork length (mm) Total length (mm) Weight (g) RNTR* RNTR* RNTR RNTR RNTR ,205 RNTR RNTR RNTR RNTR RNTR RNTR RNTR ,050 RNTR RNTR RNTR RNTR RNTR RNTR RNTR ,275 RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR ,270 RNTR RNTR RNTR RNTR

32 Appendix 6. Continued. Species Fork length (mm) Total length (mm) Weight (g) RNTR ,275 RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR RNTR BKTR BKTR BKTR BKTR BKTR BKTR BKTR BKTR BKTR BKTR BKTR ,025 22

33 Appendix 6. Continued. Species Fork length (mm) Total length (mm) Weight (g) BKTR BKTR BKTR BKTR

34 Alberta Conservation Association acknowledges the following partners for their generous support of this project:

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