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Abstract
Decreases in biodiversity are occurring worldwide because of the spread of invasive species, and by some standards, invasive species are the largest threat to maintenance of biodiversity. This research examined a potential pathway for control of an invasive species, lake trout Salvelinus namaycush, in Yellowstone Lake, Wyoming. Lake trout were first verified in Yellowstone Lake in 1994 and lake trout were known to be an effective piscivore. Native Yellowstone cutthroat trout Oncorhynchus clarki bouvieri were expected to be the main prey for larger lake trout. Most lake trout spawning in Yellowstone Lake was believed to occur in the West Thumb portion of the lake. As the population increases, new spawning areas may be pioneered, expanding recruitment to the population. By applying spatial and temporal habitat concepts of macro-, meso-, and microhabitat developed primarily for lotic environments to a lentic system, and combining these with lake trout spawning habitat requirements, a conceptual model defining lake trout spawning habitat was developed. This conceptual model was used in combination with wave energy theory and information about the geomorphology of Yellowstone Lake to create a habitat suitability model capable of predicting appropriate mesohabitat for lake trout spawning to occur. Published values for water depth, fetch length, slope, sedimentation information, and distance to areas of depth and from thermal vents were used to define suitable spawning habitat. The model classified 87% of the lake as having unsuitable conditions for lake trout spawning habitat. Another 4% of the lake was predicted to have high potential to develop suitable spawning habitat for lake trout if appropriate substrate was present. Predicted patches of suitable spawning habitat occurred almost exclusively leeward to land masses. Known information concerning lake trout spawning within Yellowstone Lake corresponded well with model predictions. These modeling results indicate an ability to predict areas that may be colonized by spawning lake trout based on knowledge of climatic, geomorphologic, and substrate features.
