Winter Sports Fishery at Gull Lake, Alberta, 2009
Gull Lake is known for its winter sport fisheries of Lake Whitefish, Northern Pike and Yellow Perch. Motivated by the concerns of Alberta Sustainable Resource Development (ASRD) regarding overharvest, the Alberta Conservation Association conducted a creel survey during the winter of 2009. The survey generated data on angler effort, yield and biological descriptors of the Lake Whitefish, Northern Pike and Yellow Perch populations for comparison with similar data from angler surveys conducted during the winters of 1992 and 2003 by ASRD.
Approximately, 28,796 anglers fished the lake in 2009 for 111,032 h which resulted in an angling pressure of 13.5 angling‐h/ha. Angling pressure has declined substantially since the 1992 and 2003 surveys.
Overall, the Gull Lake winter sport fishery in 2009 was dominated by Lake Whitefish. During the 2009 survey, anglers harvested approximately 20,974 Lake Whitefish corresponding to a yield of 2.5 kg/ha. The total catch for Lake Whitefish has declined by 49% and 72%, respectively, since 1992 and 2003. This change is primarily seen in the harvest rates, as the release rates from all three surveys were consistently very low.
The lengths of Lake Whitefish harvested during the 2003 and 2009 surveys were similar and fish condition did not differ between these two years. However, Lake Whitefish harvest and yield has declined since the 1992 and 2003 surveys by 2.7 and 9.3 times, respectively. The decrease in catch rates and the absence of both small and large fish in the harvest may indicate decreased recruitment and a recruitment‐overfished state.
The catch rates for Northern Pike increased in 2009, however, the rates remain very low according to ranges of catch rate and associated population classifications listed in Alberta’s Northern Pike Management and Recovery Plan. The harvest and yield of Northern Pike has declined significantly since 1992, possibly caused by the imposition of minimum size limits, however, large fish (>600 mm fork length) were not common in the 2009 harvest. These data indicate the Northern Pike sport fishery may also be in a recruitment‐overfished state.
The harvest rate for Yellow Perch was similar in the 2003 and 2009 surveys, however, the release rate increased by six times. The yield associated with caught and released fish decreased substantially. Anglers harvested larger numbers of smaller fish in 2009 than during the 2003 survey. This demographic change may be indicative of a growthoverfished Yellow Perch population where overexploitation of large mature fish adults is compensated for by successful recruitment of younger fish.