Westslope Cutthroat Trout Conservation Project: Research, Monitoring and Assessment $40,800

This will be the second year of an ongoing project to collect the base line genetic and ecological data required to assess hybridization of the native westslope cutthroat trout (Oncorhynchus clarki lewisi) with introduced rainbow trout (Oncorhynchus mykiss) in the upper Kootenay River basin. Results from our work completed in 1999 indicate that hybridization is wide spread. We collected 354 tissue samples, which were then analyzed at Eric Taylor's lab at UBC by examining the species-specific variation in intron sequences. Hybrids were found at 7 of the 11 sites investigated across 6 different streams (Taylor and Stamford, 2000). A similar study was completed in 1986 (Leary, 1987). These sites were re-assessed in our study. Only the population in the North Fork of the White River was hybridized in 1986. Hybridization has now been found in Gold Creek (14%), Skookumchuck Creek (3%), the headwaters of the upper Kootenay River (21%), the lower St. Mary's River (10%), and the lower Elk River (3%). These figures should be viewed as conservative because the majority of the samples looked at F1 generation hybrids only and not at introgression (Taylor and Stamford, 2000). If these results mirror the experiences in the U.S. across most of the westslope cutthroat trout's home range, it is likely that many of these populations of pure westslope cutthroat trout will be extirpated (Allendorf and Leary, 1988). In Montana the westslope cutthroat trout is thought to occupy less than 28% of its historic range, of which less than 3% of the remaining population is considered genetically pure (Liknes and Graham, 1988). The upper Kootenay River was the last large refuge area for the species in North America.

It is our long-term goal to collect the data required to effectively contribute to the development of a strategic management plan, which will address conservation of the westslope cutthroat trout.

Our goals and objectives for this field season are to:

1) Complete the cursory genetic assessments started last year in order to fill in the information gaps, especially for the Elk, Wigwam and Skookumchuck Rivers.
2) Initiate a comprehensive genetic assessment to determine rate, extent, and mechanisms of hybridization. This will be completed for the St. Mary's River.
3) Initiate habitat and ecological assessments of the study area to determine environmental factors that may influence hybridization.

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