Assessment of Summer Sport Fishery for Lake Trout at Lake Minnewanka, Banff National Park, Alberta, 2005
Fiona Johnston, Bill Patterson and Michael Sullivan
This creel survey is part of a larger monitoring program that was designed to provide information required to manage the lake trout fishery in Lake Minnewanka. A catch and possession limit of two lake trout was applicable during the angling season (21 May – 5 September).
This survey was designed as an access point survey, stratified by weekdays, weekends, and holidays, and by time of day (am and pm). Three angling groups were surveyed independently during the 108-day fishing season from 21 May to 5 September 2005. The first survey was comprised of recreational anglers that accessed the lake via the boat launch area. This group was interviewed by two creel clerks at a creel booth in the vicinity. A second group survey documented recreational angling pressure that took place on the dam and at nearby shoreline areas of the lake. This was a visual instantaneous count survey and was done hourly during a creel shift. In addition, creel clerks corrected for the number of anglers that were not visible from the creel booth area by carrying out a survey of non-visible areas for a sub-sample of the instantaneous counts. Third, information on anglers was obtained from the two guiding companies on the lake, Banff Fishing Unlimited and Lake Minnewanka Tours. These operators were expected to provide censuses of their angling clientele including information on their guiding activities and angling effort.
Based on surveys of these different angler groups, total estimated angler effort was 7.69 h/ha (95% CI = 6.27 – 10.21) during the 2005 fishing season. Of this total effort, recreational anglers using the boat launch contributed an estimated 71% (5.42 h/ha), and guided anglers contributed 29% (2.23 h/ha); contribution of anglers on the dam and shoreline was negligible (i.e. 0% of total effort).
An estimated 1,806 lake trout (95% CI = 1,448 – 2,316) were harvested from Lake Minnewanka during the 2005 fishing season. Of this total, 60% (1,089 fish) was harvested by anglers using the boat launch, <1.0% (6 fish) by dam-based anglers, and 39% (711 fish) by guided anglers. Mean weight of individual lake trout harvested by recreational and guided anglers were 1.2 kg/fish (95% CI = 1.18 - 1.23 kg, n = 266) and 1.13 kg/fish (95% CI = 1.09 - 1.19 kg, n = 362), respectively. The estimated yield of lake trout was 0.96 kg/ha (95% CI = 0.75 – 1.26) during the angling season. Estimates using five mortality scenarios (low, moderate, high, very high, and decompression), suggest that an additional mortality of 60 to 905 fish (estimated yield of 0.03 to 0.29 kg/ha) could result from incidental mortality.
Approximately 3,002 lake trout (95% CI = 2,441 – 4,024) were released by anglers from Lake Minnewanka during the 2005 fishing season. Of this total, anglers from the boat launch (i.e., access point) released 52% (1,551 fish), anglers based at the dam <1% (9 fish), and guided anglers 48% (1,443 fish). Lake trout released by guided anglers had a mean weight of 1.05 kg/fish (95% CI = 0.97 - 1.14 kg, n = 563). The estimate for total yield for released lake trout was 1.42 kg/ha (95% CI = 1.13 – 1.92) over the angling season.