Temperature and Dissolved Oxygen Conditions of Callum Creek, Alberta, 2021–2022
Logan Redman and Jason Blackburn
With genetically pure populations currently occupying only 5% of their historical range in Alberta and the species listed as Threatened under the Species at Risk Act, restoring and expanding pure westslope cutthroat trout (Oncorhynchus clarkii lewisi) (WSCT) populations is critical to safeguard against extirpation. Based on the current and historical presence of WSCT, the Callum Creek watershed in southwestern Alberta was identified as suitable for potential WSCT restoration and expansion. From spring 2021 until spring 2022, we monitored temperature and dissolved oxygen (DO) levels at ten locations in the Callum Creek watershed to determine if DO and stream temperature levels were limiting factors for WSCT distribution and survival.
Summer temperatures in the Callum Creek mainstem in 2021 were unsuitably high for WSCT for periods ranging from one to three consecutive weeks. Mean daily stream temperatures at all sampling locations in the Callum Creek mainstem exceeded WSCT thermal tolerance levels. However, tributaries to Callum Creek may provide summer thermal refuge for WSCT, as temperatures within tributary sampling sites remained largely within their tolerance range. In contrast, winter DO measurements in the mainstem and one tributary remained above the minimum threshold level for WSCT, suggesting that overwintering oxygen conditions may not be a limiting factor for WSCT survival and distribution within the Callum Creek watershed.