A Creel-based Assessment of Sport Fisheries in Sturgeon Lake, Alberta, 2007
Nathan Carruthers, Greg Fortier, Tyler Johns, and John Tchir
Recent population growth in northwestern Alberta has raised concerns about the potential impacts of increases in angling pressure on regional populations of sport fish. To guide fisheries management at Sturgeon Lake, the Alberta Conservation Association (ACA) conducted shoreline creel surveys between 11 May and 26 August 2007. We used observations collected from two locations, and computer modeling and bootstrapping procedures, to provide whole lake estimates of angling parameters. We also conducted test angling to verify catch rates reported by sport anglers.
We interviewed a total of 2,514 anglers at Sturgeon Lake. Anglers reported a total effort of 7,187 angler-h or 1.77 angler-h/ha. We estimated that (over the entire angling season and lake) 11,400 anglers fished at Sturgeon Lake in 2007 (95% CI = 9,300 – 14,400). In addition, we estimated that angling effort was 36,000 angler-h (95% CI = 27,500 – 47,000) or 9.00 angler-h/ha (95% CI = 6.75 – 11.50).
Anglers reported catching 2,774 walleye during the survey, of which 528 were harvested. Total catch-per-unit-effort (CPUE) of walleye by sport anglers was 0.386 fish/h, whereas total CPUE by test anglers was 0.436 fish/h. Total harvest-per-uniteffort (HPUE) of walleye by anglers was 0.073 fish/h. We estimated that the total angler catch of walleye in the lake was 14,500 fish (95% CI = 10,500 – 19,300) and total angler harvest of walleye was 2,800 fish (95% CI = 2,500 – 3,500).
The mean weight of harvested walleye was 0.86 kg/fish (95% CI = 0.82 – 0.90). Using the mean weight and number of harvested walleye, we estimated that the total weight of the harvest was 2,405 kg (95% CI = 2,127 – 3,007) or 0.59 kg/ha (95% CI = 0.53 – 0.74). Walleye harvested by anglers ranged in size from 319 to 540 mm total length (TL), with a mean (± SD) TL of 452 ± 41 mm (n = 121). Age of angler-harvested walleye ranged from 3 to 16 y, with a mean age of 8.9 ± 3.6 y (n = 116). Based on von Bertalanffy growth estimates, it would take approximately five years to produce a harvestable walleye (> 43 cm TL).
Anglers reported a total catch of 2,905 northern pike and a harvest of 276 northern pike during the survey. Total CPUE of northern pike by sport anglers was 0.404 fish/h, whereas total CPUE of northern pike by test anglers was 0.410 fish/h. Total HPUE of northern pike was 0.038 fish/h. We estimated that the total angler catch of northern pike in Sturgeon Lake was 13,500 fish (95% CI = 10,000 – 18,000) and that the total angler harvest in the lake was 1,650 fish (95% CI = 1,250 – 2,100).
The mean weight of harvested northern pike was 1.66 kg/fish (95% CI = 1.46 – 1.87) and that the weight of the total harvest was 2,747 kg (95% CI = 2,081 – 3,497) or 0.678 kg/ha (95% CI = 0.514 – 0.864). Northern pike harvested by anglers ranged in size from 553 to 903 mm TL, with a mean of 653 ± 76 mm (n = 51). Age of harvested northern pike ranged from 4 to 14 y, with a mean age of 6.8 ± 2.0 y (n = 51). Based on von Bertalanffy growth estimates, it would take four to five years to produce a harvestable northern pike (> 55 cm TL).