Abstract

Lake Wabamun, located approximately 64 km west of Edmonton, Alberta, has two thermal electric generating stations situated upon it which utilize lake water for cooling purposes. The fishery for lake whitefish (Coregonus clupeaformis [Mitchill]) in the lake is important due to its high commercial and sport value. Since lake whitefish eggs require low temperatures throughout the winter for successful incubation, and since the major spawning area in the lake is located across a small bay from one of the power plants, it was feared that the heated water discharge would reduce lake whitefish egg survival on the spawning grounds. Since the whitefish are subject to heavy fishing pressure in the lake, it was thought that such a reduction in egg survival might cause a gradual reduction in the whitefish population.

During preliminary fishery investigation in the lake it was discovered that large numbers of lake whitefish were spawning on an organic ooze substrate in the heated area.

To determine the survival of eggs spawned on the ooze substrate in one of the heated areas , and also on the major spawning grounds (a rock and sand shoal), fertilized lake whitefish eggs were incubated in situ in enclosed trays in these areas and at control sites located in the portion of the lake not influenced by the power plants. The effects of substrate type, water temperature, and siltation on egg survival and their relation to the heated water discharge areas are discussed.

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