North Saskatchewan River Drainage, Fish Sustainability Index Data Gaps Project, 2018
Chad Judd, Mike Rodtka, and Zachary Spence
Fishery inventories provide resource managers with information on fish species abundance, distribution, and habitat. This information is a key component of responsible land use planning. Alberta Environment and Park’s (AEP) Fish Sustainability Index (FSI), is a standardized process of assessment that provides the framework within which fishery inventories must occur for greatest relevance to government managers and planners. Our objective was to describe bull trout (Salvelinus confluentus) distribution and abundance in the headwaters of the North Saskatchewan River watershed to address data deficiencies for this FSI priority species. Bull trout are particularly sensitive to habitat change and are classed as Threatened in Alberta (Saskatchewan and Nelson rivers populations). Priority areas for fishery inventories in 2018 were identified in consultation with project partners and included the Cardinal River and its tributaries. From July 17 to August 17, we sampled 30 sites randomly distributed throughout three watersheds classed as hydrologic unit code (HUC) 10, Ruby Creek, Upper Cardinal River, and Lower Cardinal River. Sites were sampled using backpack and tote-barge electrofishing gear. We captured 98 bull trout, ranging in size from 31 to 273 mm fork length (FL). Bull trout were detected at seven sites in the Ruby Creek HUC 10 watershed and at six sites in the Upper Cardinal River HUC 10 watershed. Bull trout were not detected at any sites in the Lower Cardinal River HUC 10 watershed and overall thirteen of the 30 sites had zero fish captures. The Ruby Creek HUC 10 watershed had the highest median relative abundance of bull trout at 0.96 (CI = 0.00 – 4.33) bull trout per 100 m. We also sampled 6.5 kilometers of the Cardinal River mainstem using float electrofishing and angling gear and captured two bull trout and eleven cutthroat trout (Onchorynchus clarki). We measured stream temperature (hourly) at four stations in the HUC 10 watersheds and results indicated that highly suitable thermal habitat for bull trout existed in each of the watersheds in the summer months of 2018. Cobble substrate was dominant throughout the watersheds, a habitat quality preferred by bull trout. Our study provides current information on stream habitats, and the abundance and distribution of FSI priority species within the Cardinal River and its tributaries. This information is useful to land managers when attempting to balance the diverse values of the landbase upon which they operate and critical for the conservation of native fish species particularly sensitive to habitat degradation including bull trout.