Status of sport Fish in Lesser Slave Lake, Alberta, 2005
Author(s)
Greg Fortier, Tyler Johns and Nathan Carruthers
Summary
Lesser Slave Lake, one of the premier sport fishery lakes in Alberta, has experienced increases in angling pressure since 1985. Strategies used by Alberta Sustainable Resource Development (ASRD) to maintain or recover sport fisheries throughout the province include changes to fish size limit, daily bag limits, catch and harvest rates, and fishery closures. To evaluate the effectiveness of such management strategies for Lesser Slave Lake, we conducted gill netting (index netting) surveys on the lake from 12 to 18 September 2005 to quantify population metrics for four major sport fishes, walleye (Sander vitreus), northern pike (Esox lucius), lake whitefish (Corregonus clupeaformis) and yellow perch (Perca flavescens). This information is intended for use by fisheries managers to support management of the fishery at Lesser Slave Lake.
Overall, walleye and lake whitefish were the predominant sport fishes in the lake, constituting 43.0% and 32.7% of the total catch, respectively; northern pike (6.5%) and yellow perch (4.2%) occurred in low numbers. Total catch-per-unit-effort (TCUE) for walleye and lake whitefish was 13.67 and 10.39 fish/100 m2/24 h, respectively, and was 2.06 and 1.33 fish/100 m2/24 h for northern pike and yellow perch, respectively.
Of 761 walleye sampled, 44.7% were females and 55.3% were males resulting in a female to male sex ratio of 0.81:1. Total lengths of males ranged from 127 to 655 mm with a mean (± SD) of 412.7 ± 52.70 mm (n = 421), whereas lengths of females ranged from 184 to 732 mm with a mean of 441.9 ± 76.04 mm (n = 340). Males ranged in age from 1 to 12 y with a mean of 7.5 ± 1.70 y (n = 152), whereas females ranged in age from 1 to 14 y with a mean of 7.5 ± 2.19 y (n = 147). Females reached maturity by age-6 at 450 mm. In contrast, males reached maturity by age-5 or by 400 mm. Based on von Bertalanffy growth estimates, walleye in Lesser Slave Lake should reach 43 cm TL in 8.3 years for males and 6.5 years for females.
Of 116 northern pike sampled, 68.1% were females and 31.9% were males resulting in a female to male sex ratio of 2.14:1. Total lengths of males ranged from 233 to 773 mm with a mean of 467.8 ± 101.79 mm (n = 37), whereas lengths of females ranged from 321 to 1,077 mm with a mean of 667.0 ± 175.87 mm (n = 79). Males ranged in age from 1 to 9 y with a mean of 3.4 ± 1.51 y (n = 37), whereas females ranged in age from 2 to 11 y with a mean of 5.7 ± 2.47 y (n = 78). Females reach maturity by age-3 or by 500 mm. In contrast, males reach maturity by age-2 or by 350 mm. Based on von Bertalanffy growth estimates, northern pike in Lesser Slave Lake should reach 43 cm TL in 4.0 years.
Of the 466 lake whitefish sampled, 60.7% were females and 39.3% were males resulting in a female to male sex ratio of 1.55:1. Total lengths of males ranged from 243 to 642 mm with a mean of 515.7 ± 67.06 mm (n = 183), whereas lengths of females ranged from 131 to 630 mm with a mean of 513.8 ± 76.30 mm (n = 283). Males ranged in age from 2 to 13 y with a mean of 8.1 ± 2.19 y (n = 111), whereas females ranged in age from 2 to 13 y with a mean of 7.8 ± 2.29 y (n = 112). Both females and males reached maturity by age-6 or by 500 mm.
Of the 65 yellow perch sampled, 83.1% were females and 16.9% were males resulting in a female to male sex ratio of 4.91:1. Total lengths of males ranged from 94 to 168 mm with a mean of 108.7 ± 20.56 mm (n = 11), whereas females ranged from 100 to 347 mm with a mean of 245.3 ± 77.59 mm (n = 54). Males ranged in age from 1 to 2 y with a mean of 1.1 ± 0.32 (n = 10), whereas females ranged from 1 to 10 y with a mean of 5.3 ± 2.74 y(n = 51). Females reached maturity by age-3 or by 250 mm. All males were mature at age-1 and 100 mm.
The results of this study provide important information that can be used by resource managers to quantify the effects of anticipated increases in angling pressure on sport fish population in Lesser Slave Lake, as well as to evaluate the effects of regulation changes.