Research Document 2020/046
Recovery Potential Modelling of Westslope Cutthroat Trout (Oncorhynchus clarkii lewisi) in Canada (Saskatchewan-Nelson River populations)
By van der Lee, A.S. and Koops, M.A.
Abstract
The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assessed the Westslope Cutthroat Trout (WCT, Oncorhynchus clarkii lewisi) as Threatened for Saskatchewan-Nelson River populations (DU 1) in Canada. Here population modelling is presented to assess the impacts of harm, determine abundance and habitat recovery targets, and conduct long-term projections of population recovery in support of a recovery potential assessment (RPA). The analysis demonstrated that WCT populations were most sensitive to perturbations to the juvenile stage (e.g. survival, growth, and habitat) under most circumstances. Harm to these aspects of WCT life-history should be avoided. Population viability analysis was used to identify potential recovery targets. Demographic sustainability, (i.e. a self-sustaining population over the long term) can be achieved with population sizes of 1,600 to 4,200 adults (> 138 mm). A population of this size would require between 21 and 37 km of stream habitat. Population projections predicted that recovery could occur in 27–33 years with an initial density of 10% of the abundance targets.
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