Abundance, Distribution, Spawning, and Thermal Habitat of Westslope Cutthroat Trout and Bull Trout in the Stimson Creek Watershed
Brad Hurkett, Jason Blackburn, and Logan Redman
Westslope cutthroat trout and bull trout populations continue to persist in the Stimson Creek watershed but in low numbers. Westslope cutthroat trout were identified in the upper reaches of Pekisko Creek, upstream and immediately downstream of McConnell Falls, in Miller Creek, Sheppard Creek, and Hay Creek. Sample sites upstream of McConnell Falls had the greatest catch rates and distribution of Westslope cutthroat trout in the study area which is likely attributed to higher quality fish habitat, colder water temperatures and the absence of rainbow trout populations; McConnell and Upper Pekisko Creek falls were both classified as upstream fish barriers.
Bull trout were only identified in the Pekisko Creek basin and absent elsewhere in the watershed. We observed a resident bull trout population in upper Pekisko Creek, downstream of McConnell Falls and Miller Creek. Low fish abundance and redd counts suggests bull trout abundance and distribution is limited to the upper reach of Pekisko Creek.
Rainbow trout were the most abundant trout species in the watershed as they were detected at most sites in the Pekisko Creek watershed, downstream of McConnell Falls, as well as in the upper half of Sheppard Creek watershed. Rainbow trout was the only salmonid captured in Stimson Creek albeit in low numbers. Cutthroat x rainbow trout hybrids were captured in two streams in the watershed, Hay Creek and Bear Creek. These sites are transition zones where rainbow trout and Westslope cutthroat trout ranges overlap. We anticipate that more hybridized fish will be identified by AEP in 2018 following analysis of genetic samples taken in 2017.