Assessment and recommendations: Spray River restoration

Abstract

This Master's Degree project focuses on the assessment of the ecological integrity of the Spray River in Banff National Park, and provides recommendations for the future study and management of the aquatic resources in the Spray River. The purpose of this project was to assess the current state of the fish population and its related ecosystem in the Spray River below Canyon Dam and to recommend management actions to improve fish habitat, within the context of ecological integrity. To assess the native fish habitat restoration potential in the Spray River, a comprehensive study approach was employed, including measurements of stream discharge, stream temperature, topographic and bathymetric survey, substrate, fish community, instream cover, riparian vegetation, conductivity and pH, benthic invertebrates, and total suspended solids (TSS). Data were compared to habitat suitability indices to determine the quality of cutthroat trout and bull trout habitat in the Spray River. Low stream flows have reduced and homogenized available fish habitat in the Spray River. The habitat assessment indicated that the low number of pools, lack of deep pools, and lack of instream cover limit habitat suitability for cutthroat trout and bull trout. Non-indigenous brook trout dominated the fish community. Stream flows and water depths in the Spray River have been significantly reduced from their historic levels. Reduced water depths and stream flows are the primary limiting factors for the re-establishment of native fish species. Removal of brook trout from the Spray River may never be successful due to the difficulty to completely remove small brook trout and several open fish migration pathways into the stream. Direct habitat modification would have to be extensive and would require a long-term monitoring and maintenance program. Keywords: Environmental science, ecological integrity, Spray River, habitat assessment, restoration, cutthroat trout, bull trout, brook trout.