Status of Northern Pike and Yellow Perch at Goosegrass Lake, Alberta, 2006

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Status of Northern Pike and Yellow Perch at Goosegrass Lake, Alberta, 2006

Nathan Carruthers, Tyler Johns and Greg Fortier Alberta Conservation Association Bag 900‐26 Peace River, Alberta, Canada T8S 1T4

Report Series Editor PETER AKU KELLEY KISSNER Alberta Conservation Association 50 Tuscany Meadows Cres NW #101, 9 Chippewa Rd Calgary, AB T3L 2T9 Sherwood Park AB T8A 6J7

Conservation Report Series Type Data

ISBN printed: 978‐0‐7785‐7064‐6 ISBN online: 978‐0‐7785‐7065‐3 Publication No.: T/185

Disclaimer: This document is an independent report prepared by the 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: Carruthers, N., T. Johns, and G. Fortier. 2007. Status of northern pike and yellow perch at Goosegrass Lake, Alberta, 2006. Data Report, D‐2007‐002, produced by the Alberta Conservation Association, Peace River, Alberta, Canada. 16 pp + App.

Cover photo credit: David Fairless

Digital copies of conservation reports can be obtained from: Alberta Conservation Association #101, 9 Chippewa Rd Sherwood Park AB T8A 6J7 Toll Free: 1‐877‐969‐9091 Tel: (780) 410‐1998 Fax: (780) 464‐0990 Email: info@ab‐conservation.com Website: www.ab‐conservation.com

i EXECUTIVE SUMMARY

Increased access in the Red Earth region of northwestern Alberta has raised concerns about impacts of potential increases in angling pressure on sportfish populations of lakes in the region, including Goosegrass Lake. The present study was conducted at Goosegrass Lake to generate quantitative data on abundance, population structure and growth of two major species, northern pike (Esox lucius) and yellow perch (Perca flavescens), that can be used to assess impacts of increased fishing pressure.

A total of 225 sportfish were captured during the survey. Northern pike was the most abundant species captured, accounting for 74.6% of the catch, and yellow perch was least abundant, accounting for 25.4% of the catch.

Mean catch‐per‐unit‐effort (CPUE) for northern pike ranged from 16.18 to 21.29 fish/100 m2/24 h with a total CPUE of 18.00 fish/100 m2/24 h. Of the 168 northern pike sampled, 46% were females and 54% were males resulting in a female to male sex ratio of 0.87:1. Total length (TL) of females ranged from 430.3 to 828.0 mm with a mean (± SD) of 695.5 ± 78.0 mm. Males ranged in length from 496.6 to 747.2 mm with a mean of 640.6 ± 55.9 mm (n = 89). Male northern pike ranged in age from 4 to 11 y (mean = 7.33 ± 1.62 y; n = 89), whereas females ranged from 3 to 13 y (mean = 7.66 ± 2.10 y; n = 77); overall mean age of the catch was 7.45 y ± 1.90 y (n = 167). Age‐8 males and age‐6 females with mean TLs of 668.7 ± 17.80 mm (n = 27) and 652.9 ± 24.74 mm (n = 18), respectively, were the most abundant year‐classes representing 26.8% of the total catch.

Mean CPUE for yellow perch ranged from 5.83 to 6.56 fish/100 m2/24 h with a total CPUE of 6.11 fish/100 m2/24 h. Of the 56 yellow perch caught, 60.7% (n = 34) were females and 5.4% (n = 3) were males resulting in a female to male sex ratio of 11.33:1. Predicted TL of females ranged from 92.8 to 245.0 mm with a mean of 193.2 ± 8.69 mm (n = 34), whereas length of males ranged from 161.6 to 218.9 mm with a mean of 192.7 ± 28.84 mm (n = 3). Male yellow perch ranged in age from 8 to 9 y (mean = 8.5 y, n = 2), whereas females ranged in age from 2 to 9 y with a mean of 5.79 + 2.00 y (n = 33); overall mean age of the catch was 5.72 ± 2.10 y (n = 39). The age‐6 cohort with a mean TL of 198.9 mm ± 6.09 mm (n = 8) was the most abundant year‐class, representing 20.5% of the total catch.

ii The results of the present study provide important baseline information that can be used by resource managers to quantify the effects of anticipated increases in angling pressure on sportfish population in Goosegrass Lake.

Key words: Goosegrass Lake, northern pike, yellow perch, benthic gill nets, growth, maturity, catch‐per‐unit‐effort.

iii ACKNOWLEDGEMENTS

This work was funded by the Alberta Conservation Association. We thank Dave Jackson for assisting with the delivery of this project and Paul Hvenegaard for reviewing earlier drafts of this report.

iv

TABLE OF CONTENTS

EXECUTIVE SUMMARY...... ii ACKNOWLEDGEMENTS...... iv TABLE OF CONTENTS ...... v LIST OF FIGURES...... vi LIST OF TABLES...... vii LIST OF APPENDICES ...... viii 1.0 INTRODUCTION ...... 1 2.0 STUDY AREA...... 1 3.0 MATERIALS AND METHODS ...... 3 3.1 Sampling design ...... 3 3.2 Data collection...... 3 3.3 Data analysis ...... 4 4.0. RESULTS ...... 5 4.1 Northern pike...... 5 4.2 Yellow perch...... 10 4.3 Summary...... 15 5.0 LITERATURE CITED ...... 16 6.0 APPENDICES...... 17

v LIST OF FIGURES

Figure 1. Map of Goosegrass Lake showing gill net locations for 2006...... 2 Figure 2. Length distributions of male and female northern pike captured at Goosegrass Lake, Alberta during the 2006 stock assessment...... 8 Figure 3. Age distributions of male and female northern pike captured at Goosegrass Lake during the 2006 stock assessment...... 9 Figure 4. von Bertalanffy plots for male and female northern pike captured at Goosegrass Lake, Alberta, 2006...... 10 Figure 5. Length distribution of yellow perch captured at Goosegrass Lake during the 2006 stock assessment...... 13 Figure 6. Age distribution of yellow perch captured at Goosegrass Lake, Alberta, 2006...... 14 Figure 7. von Bertalanffy growth function for yellow perch captured at Goosegrass Lake, Alberta, 2006 ...... 15

vi LIST OF TABLES

Table 1. Distribution of fish sampling effort by depth strata at Goosegrass Lake, Alberta, 2006...... 3 Table 2. Mean catch‐per‐unit‐effort of northern pike from the 2006 stock assessment at Goosegrass Lake, Alberta...... 5 Table 3. Proportion of mature northern pike in each age class from the 2006 stock assessment at Goosegrass Lake, Alberta...... 6 Table 4. Proportion of mature northern pike in each length class from the 2006 stock assessment at Goosegrass Lake, Alberta...... 7 Table 5. Mean catch‐per‐unit‐effort of yellow perch from the 2006 stock assessment at Goosegrass Lake, Alberta...... 11 Table 6. Proportion of mature yellow perch in each age class from the 2006 stock assessment at Goosegrass Lake, Alberta...... 11 Table 7. Proportion of mature yellow perch in each length class from the 2006 stock assessment at Goosegrass Lake, Alberta...... 12

vii LIST OF APPENDICES

Appendix 1. Universal transverse mercator coordinates of gill net locations at Goosegrass Lake, Alberta, 2006...... 17

viii 1.0 INTRODUCTION

Increased access (new road development) to lakes in the Red Earth area in northern Alberta, including Goosegrass Lake, has raised concerns about the potential impacts of increasing angling pressure on sportfish populations. Strategies implemented by Alberta Sustainable Resource Development (ASRD) to maintain or recover fish populations include changes in angling regulations that are designed to reduce fish mortality and increase recruitment (Berry 1999). Regular evaluation of the abundance and structure of sportfish populations is necessary to assess the effectiveness of management strategies.

To assess impacts of increased accessibility on sportfish populations in Goosegrass Lake, we conducted a stock assessment survey on the lake to quantify the abundance, age and growth of the two major sportfish species, northern pike (Esox lucius) and yellow perch (Perca flavescens).

2.0 STUDY AREA

Goosegrass Lake is located approximately 68 km northeast of Red Earth Creek, Alberta (Figure 1) at 658426 Easting, 6306250 Northing, UTM zone 11. It has a surface area of 238.7 ha, an average depth of 3.8 m and a maximum depth of 6.5 m. Access to the lake is via a gravel road followed by an ATV trail. The lake supports natural populations of northern pike, yellow perch and white sucker (Catostomus catostomus) (Wilcox 1999).

1 (! ´

(! (!

(!

(!

(!

(!

(!

(!

Legend

(! Sampling Locations [_ 0 - 5 m depth interval Red Earth Creek 5 - 15 m depth interval

00.1 0.2 0.4 0.6 0.8

Kilometers

Figure 1. Map of Goosegrass Lake showing gill net locations for 2006. Inset is a map of Alberta indicating the location of the lake within the province.

2 3.0 MATERIALS AND METHODS

3.1 Sampling design

This study was conducted between 19 and 21 June 2006. Nine multi‐mesh benthic gill nets were used to capture fish. Each net measured 1.8 m deep by 61.0 m long and was comprised of eight 7.6 m panels of different mesh sizes (stretched mesh) including 25, 38, 51, 64, 76, 102, 127, and 152 mm sewn together in sequential order.

Sampling sites were selected in a stratified random sampling design, with two depth strata (2 to 5 m and 5 to 15 m); water deeper than 15 m was not sampled. Table 1 shows the stratification and the proportion of the lake’s surface area represented by each stratum. Sampling effort was allocated proportionately to surface area of the two depth strata (Table 1). A total of nine gill nets were deployed and their locations are provided in Appendix 1. Sample sites were randomly selected with a minimum distance of 500 m between all sites. Nets were set at depths ≥ 2 m and ≤ 15 m for approximately 24 h. Nets were set perpendicular to the shoreline; if the net extended beyond its depth stratum then the net was reset at an angle. The orientation of the largest or smallest mesh in relation to the shore was random.

Table 1. Distribution of fish sampling effort by depth strata at Goosegrass Lake, Alberta, 2006.

Depth interval (m) Proportion of lake surface area (%) Number of sites 2 to 5 46 3 5 to 15 54 6

3.2 Data collection

Biological data collected from all captured fish included: fork length (FL), total length (TL) and weight. Sex, maturity and stomach contents were determined through internal examination of deceased fish. Stomach contents were collected as requested by ASRD. Ageing structures were also removed from deceased fish and were aged following methods in Mackay et al. (1990). Cleithra were collected to age northern pike

3 and opercular bones and dorsal fin rays were collected to age yellow perch. All data (number caught, FL, age, weight and stomach contents) were entered into the Alberta government Fisheries Management Information System (FMIS), Project Location ID 7309.

3.3 Data analysis

The abundance of each species, expressed as catch‐per‐unit‐effort (CPUE, fish/100 m2 of net/24 h), was calculated at each sampling site and used to calculate the mean CPUE (+ 95% confidence interval). CPUE values were reported for each depth stratum as well as a grand mean for all depth strata combined. Total catch‐per‐unit‐effort (TCUE) is the total catch of each fish species divided by the total effort applied. In order to evaluate current management strategies at a particular lake, fisheries managers of ASRD compare catch rates (CPUE and TCUE) at the lake to those on other similar lakes, and monitor changes in catch rates over time.

Length‐frequency and age‐frequency‐distributions were used to examine the population structure of each species. Distributions of length and age were shown in relation to CPUE for each 20 mm class or age interval. Total length distributions were displayed in 20 mm length classes.

We established relations between FL and TL for northern pike and yellow perch from fish captured in this study. In order to reduce sampling time, TL was not measured for all fish. To estimate the TL of all fish captured in this study, we plotted FL and TL measurements of individual northern pike and yellow perch, where both were recorded, and fit the data to the following linear regression models.

Northern :pike TL = 1.0356(FL) + 15.07; 2 0.996,(R == 59)n Yellow :perch TL = 1.0428(FL) + 2 == 18)n0.999,(R0.99;

Fish maturity was described as the age at which 50% of the fish were mature. The length at which 50% of fish were mature was also reported. Fish growth rate was described using the von Bertalanffy (1938) growth model:

4 k ‐ (t‐ )t = 0 Lt ∞ (1L ‐ )e where,

Lt = length at age t,

L∞ = the asymptote or final maximum size, K = the rate at which the growth curve approaches the asymptote, and

t0 = a time scaler, the hypothetical time when the fish was size zero

To account for sexual variation in growth rate, the von Bertalanffy model was fitted separately for male and female fish. The parameter used to estimate growth in the von Bertalanffy model is K, i.e., the rate at which the fish approaches maximum size (L∞). Higher values of K represent faster growth and are usually associated with a lower L∞.

Due to small sample sizes of small fish, t0 was fixed at zero to reduce bias in the growth function.

4.0. RESULTS

4.1 Northern pike

Northern pike accounted for 74.6% of the total catch (168 of 225 fish captured). TCUE was 18.00 fish/100 m2/24 h. Mean CPUE ranged from 16.18 fish/100 m2/24 h in the 5 to 15 m depth interval to 21.29 fish/100 m2/24 h in the 2 to 5 m interval, with a grand mean of 17.89 fish/100 m2/24 h (Table 2).

Table 2. Mean catch‐per‐unit‐effort (CPUE) of northern pike from the 2006 stock assessment at Goosegrass Lake, Alberta.

Depth (m) Mean CPUE 95% confidence interval (+/‐) Number of nets

2 to 5 21.29 10.03 3 5 to 15 16.18 3.75 6 Combined 17.89 3.31 9

5 The proportion of mature northern pike in each age and length class is shown in Tables 3 and 4. While sample sizes of each age class were insufficient to determine the point of 50% maturity, the data show this occurs earlier than age‐6 for both males and females. The data also show that 50% of male northern pike are mature before they reach 630 mm TL. Small sample sizes of females in each length category were insufficient to determine the point of 50% maturity.

Table 3. Proportion of mature northern pike in each age class from the 2006 stock assessment at Goosegrass Lake, Alberta.

Age Males Females (y) % mature n % mature n 3 ‐ ‐ 0 1 4 80 5 0 1 5 88 8 33 6 6 100 10 78 18 7 100 23 93 15 8 100 27 100 9 9 100 8 100 14 10 100 5 75 4 11 100 3 100 5 12 ‐ ‐ 100 3 13 ‐ ‐ 100 1

6 Table 4. Proportion of mature northern pike in each length class from the 2006 stock assessment at Goosegrass Lake, Alberta.

Total length Males Females (mm) % mature n % mature n 400 ‐ ‐ ‐ ‐ 420 ‐ ‐ 0 1 440 ‐ ‐ ‐ ‐ 460 ‐ ‐ ‐ ‐ 480 50 2 ‐ ‐ 500 100 3 ‐ ‐ 520 100 2 0 4 540 80 5 50 2 560 100 1 50 2 580 100 4 ‐ ‐ 600 100 8 0 1 620 100 8 83 6 640 100 19 67 6 660 100 19 100 7 680 100 9 100 7 700 100 5 100 1 720 100 3 100 14 740 100 1 100 11 760 ‐ ‐ 89 9 780 ‐ ‐ 100 4 800 ‐ ‐ 100 1 820 ‐ ‐ 100 1 840 ‐ ‐ ‐ ‐

Of the 166 northern pike sampled where sex could be determined, 46% (n = 77) were females and 54% (n = 89) were males, resulting in a female to male sex ratio of 0.87:1. Total length of females ranged from 430.3 to 828.0 mm with a mean of 695.5 ± 78.0 mm (n = 77; Figure 2), whereas total length of males ranged from 496.6 to 747.2 mm with a mean of 640.6 mm ± 55.9 mm (n = 89; Figure 2).

7 2.0

1.8 Females (n = 77) Males (n = 89) 1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0 400 500 600 700 800 900 Predicted Total Length (mm)

Figure 2. Length distributions of male and female northern pike captured at Goosegrass Lake, Alberta during the 2006 stock assessment.

Males ranged in age from 4 to 11 y (mean = 7.33 ± 1.62 y; n = 89), whereas females ranged in age from 3 to 13 y (mean = 7.66 ± 2.10 y; n = 77); overall mean age of the catch was 7.45 ± 1.90 y (n = 167; Figure 3). The age‐6 cohort was the most abundant year‐class for female northern pike, representing 23% of all females (n = 18). Age‐8 males were most abundant, representing 30% of all males (n = 27). Age‐6 females had a mean TL of 652.9 ± 24.7 mm ( n = 18). Age‐8 males had a mean TL of 668.7 ± 17.8 mm (n = 27). Average TL of the age‐6 female and age‐8 male cohorts exceeded the legal harvest size of 63 cm, making both cohorts susceptible to angler harvest.

8 3.0

Females (n = 77) 2.5 Males (n = 89) ) 2 2.0

1.5 (fish/24h/100m

1.0 CPUE

0.5

0.0 02468101214 Age

Figure 3. Age distributions of male and female northern pike captured at Goosegrass Lake during the 2006 stock assessment.

When fitted to the von Bertalanffy growth function, male northern pike had an L∞ of

757 mm TL and a growth coefficient K of 0.267 (Figure 4). Females had an L∞ of 855 mm TL and a growth coefficient K of 0.233 (Figure 4).

9 1000

k ‐ (t ‐ 0 )t L t = L∞ (1 ‐ )e

800

(mm) 600

Length 400 Total

200

0 0 2 4 6 8 10 12 14 Age

Figure 4. von Bertalanffy plots for male and female northern pike captured at Goosegrass Lake, Alberta, 2006. Males: L∞ = 757, K = 0.267, n = 89; Females: L∞ = 855, K = 0.233, n = 77.

4.2 Yellow perch

Yellow perch accounted for 25.4% of the total catch (57 of 225 fish captured). TCUE was 6.11 fish/100 m2/24 h. Mean CPUE ranged from 5.83 fish/100 m2/24 h in the 5 to 15 m depth to 6.56 fish/100 m2/24 h in the 2 to 5 m interval, with a grand mean of 6.07 fish/100 m2/24 h (Table 5). However, the combination of a very small sample size and large variance in catch rates in the 2 to 5 m interval suggests that this estimate may be unreliable (Table 5).

10 Table 5. Mean catch‐per‐unit‐effort (CPUE) of yellow perch from the 2006 stock assessment at Goosegrass Lake, Alberta.

Depth (m) Mean CPUE 95% confidence interval (+/‐) Number of nets 2 to 5 6.56 8.84 3 5 to 15 5.83 1.61 6 Combined 6.07 1.68 9

Analyses of female maturity data were inconclusive due to an insufficient sample size of female yellow perch (Tables 6 and 7). All male yellow perch captured were deemed to be mature (Table 6 and 7).

Table 6. Proportion of mature yellow perch in each age class from the 2006 stock assessment at Goosegrass Lake, Alberta.

Age Males Females (y) % mature n % mature n 2 ‐ ‐ 0 2 3 ‐ ‐ 67 3 4 ‐ ‐ 20 5 5 ‐ ‐ 100 3 6 ‐ ‐ 100 7 7 ‐ ‐ 80 5 8 100 1 100 6 9 100 1 100 2

11 Table 7. Proportion of mature yellow perch in each length class from the 2006 stock assessment at Goosegrass Lake, Alberta.

Total length Males Females (mm) % mature n % mature n 80 ‐ ‐ ‐ ‐ 90 ‐ ‐ 0 1 100 ‐ ‐ 0 1 110 ‐ ‐ ‐ ‐ 120 ‐ ‐ 0 1 130 ‐ ‐ 50 2 140 ‐ ‐ 67 3 150 ‐ ‐ 33 3 160 100 1 100 1 170 ‐ ‐ ‐ ‐ 180 ‐ ‐ 100 2 190 100 1 100 3 200 ‐ ‐ 100 5 210 ‐ ‐ 75 4 220 100 1 100 1 230 ‐ ‐ 100 3 240 ‐ ‐ 100 4

Of the 37 yellow perch sampled where sex could be determined, 91.9% (n = 34) were females and 8.1% (n = 3) were males, resulting in a female to male sex ratio of 11.33:1. Predicted TLs of males ranged from 161.6 to 218.9 mm with a mean of 192.7 ± 28.84 mm (n = 3), whereas TLs of females ranged from 92.8 to 245.0 mm with a mean of 193.2 mm ± 8.69 mm (n = 34; Figure 5).

12 1.4

n = 50 1.2

1.0 ) 2

0.8

0.6 (fish/24h/100m

0.4 CPUE

0.2

0.0 50 100 150 200 250 300

Total Length (mm) Figure 5. Length distribution of yellow perch captured at Goosegrass Lake during the 2006 stock assessment.

Of the 39 yellow perch where age could be determined, 84.6% (n = 33) were females, 5.1% (n = 2) were males and 10.3% (n = 4) were of unknown gender. Female yellow perch ranged in age from 2 to 9 y with a mean age of 5.79 ± 2.00 y (n = 33). Males ranged in age from 8 to 9 y with a mean age of 8.5 y (n = 2). The mean age of yellow perch was 5.72 ± 2.10 y (n = 39; Figure 6).

13 1.0

n = 39

0.8 ) 2

0.6

0.4 (fish/24h/100m CPUE 0.2

0.0 024681012 Age

Figure 6. Age distribution of yellow perch captured at Goosegrass Lake, Alberta, 2006.

When fitted to the von Bertalanffy growth function yellow perch had an L∞ of 283 mm TL and a growth coefficient K of 0.204 (Figure 7).

14 300

k ‐ (t ‐ 0 )t L t = L∞ (1 ‐ )e 250

200 (mm)

150 Length

100 Total

50

0 0246810 Age

Figure 7. von Bertalanffy growth function for yellow perch captured at Goosegrass Lake, Alberta, 2006 (L∞ = 283, K = 0.204, n = 39).

4.3 Summary

Improved access (upgraded and new roads) into lakes in the Red Earth area in recent years, including Goosegrass Lake, has raised concern about the potential for increased angling pressure. The results of this study provide important baseline information that can be used by resource managers to quantify the effects of increases in angling effort due to increased access to Goosegrass Lake that are forecasted to occur over the next decade. Increased monitoring of fish populations at Goosegrass Lake and other lakes in the Red Earth area will become increasingly important with the development of a proposed highway extending from Red Earth to Fort McMurray.

15 5.0 LITERATURE CITED

Berry D.K. 1999. Alberta’s northern pike management and recovery plan. Alberta Environmental Protection, Natural Resources Service, Number T/459, Edmonton, Alberta. 22 pp.

Mackay, W.C., G.R. Ash, and H.J. Norris. 1990. Fish ageing methods for Alberta. R.L. & L. Environmental Services Ltd. in association with Alberta Fish and Wildlife Division and University of Alberta, Edmonton, Alberta. 113 pp.

Wilcox, K. 1999. Lake monitoring program results, Goosegrass Lake. Data report produced by the Alberta Conservation Association, Peace River, Alberta, Canada. 17 pp.

von Bertalanffy, L. 1938. A quantitative theory of organic growth. Human Biology 10: 181‐213.

16 6.0 APPENDICES

Appendix 1. Universal transverse mercator (UTM) coordinates (NAD 83, UTM zone 11) of gill net locations at Goosegrass Lake, Alberta, 2006.

Depth Interval (m) Site Id UTM Easting UTM Northing A20 656912 6306559 2 to 5 18 657903 6307069 19 658522 6304939

D03 657971 6305863 D01 657863 6306707 A03 658228 6305420 5 to 15 A10 657465 6306362 A02 658386 6306662 A01 658555 6305745

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CCONSERVATIONONSERVATION RREPORTEPORT SSERIESERIES The Alberta Conservation Association acknowledges the following partner for their generous support of this project