Status of Walleye and Northern Pike Sport Fisheries at Graham Lake, Alberta, 2004
Greg Fortier and John Tchir
Improved access to lakes in the Red Earth area in northern Alberta has raised concerns about impacts of potential increases in angling pressure on the relatively unexploited sport fish populations of these lakes. However, very little quantitative data exist on angling pressure and sport fish harvest on most of these lakes, including Graham Lake. To generate such data on Graham Lake, a creel survey was conducted on the lake during the summer of 2004.
An estimated 2240 (95% CI = 1520 - 3640) anglers fished at Graham Lake from 13 May to 23 August 2004, resulting in an angling pressure of 1.19 angler-h/ha (95% CI = 0.91 - 1.57). The overall catch rate (expressed as total catch-per-unit-effort, TCUE) of walleye (Sander vitreus) was 0.80 fish/h and the total harvest-per-unit-effort (THUE) was 0.130 fish/h. The total estimated walleye harvest was 0.291 kg/ha (95% CI = 0.203 - 0.384). In contrast, the overall TCUE of northern pike (Esox lucius) was 0.31 fish/h, with a THUE of 0.027 fish/h. The total estimated harvest of northern pike was 0.087 kg/ha (95% CI = 0.056 - 0.132).
Length of walleye harvested by anglers ranged from 490 to 707 mm with a mean (± SD) of 580.5 ± 43.21 mm (n = 218) and ages ranged from 9 to 21 y with a mean of 13.3 ± 1.67 y (n = 224). Length of fish caught by test anglers ranged from 314 to 665 mm with a mean of 520.9 ± 75.01 mm (n = 63) and ages ranged from 4 to 18 y with a mean of 11.0 ± 3.16 y (n = 57).
Length of northern pike harvested by anglers ranged from 640 to 1020 mm with a mean of 744.8 ± 80.55 mm (n = 60) and ages ranged from 6 to 14 y with a mean of 9.3 ± 1.80 y (n = 56). Length of fish caught by test anglers ranged from 580 to 1033 mm with a mean of 675.6 ± 104.35 mm (n = 18) and ages ranged from 3 to 13 y with a mean of 7.6 ± 2.43 y (n = 19).
Based on von Bertalanffy growth estimates, walleye in Graham Lake should reach harvestable size (> 50 cm TL) in 9 years and northern pike should reach harvestable size (> 63 cm TL) in 6 years.
Results of our study will aid fisheries managers in formulating management guidelines for walleye and northern pike sport fisheries of priority lakes in the Red Earth area. Although our estimated angling pressures at Graham Lake may be considered low, improved access and upgrading of facilities at the lake may result in increased fishing pressure in the future. Our data will serve as the baseline for assessing future impacts.