Westslope Cutthroat Trout Range Expansion Feasibility
Westslope cutthroat trout (WSCT) currently occupy only 5% of their historic range in Alberta, and recovery of the species requires expanding their distribution. It is therefore imperative to identify additional suitable habitats and determine feasibility for WSCT recovery outside of the current range. Invasive species are potentially the greatest threat to westslope cutthroat trout in Alberta, through hybridization, competition, and displacement. The presence of natural waterfall barriers partially mediates this threat by impeding invasion by non-native species into headwater streams and lakes. Several sub-populations of WSCT remain genetically pure because of waterfall barriers. The habitats upstream of these barriers represent opportunities for expanding the range of WSCT and total critical habitat area of the species through introduction or re-introduction of pure stocks. Before re-introductions can begin, a thorough examination of upstream habitats must be undertaken to catalogue and rank range expansion potential and identify those areas most suitable for WSCT re-establishment. Our objective is to assess the feasibility of WSCT range expansion into streams and lakes above barriers currently unoccupied by pure WSCT populations. We are customizing an existing framework recently developed by bull trout researchers, to score and rank habitats above waterfall barriers based on WSCT life history requirements. We will determine range expansion feasibility for each habitat based on the sum of scores that rate habitat quality, habitat quantity, habitat complexity, threats to existing WSCT populations, and future invasion risk. We will rank both stream and lake habitats by range expansion suitability score, which government agencies require to plan WSCT re-establishment and recovery.
Alberta Environment and Parks
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|Westslope Cutthroat Trout Range Expansion Feasibility||2018-2019||1|