Clearwater River Core Area Bull Trout Status

ACA has a long history of documenting sport fish distributions at a watershed scale to support species status assessments. When describing species distribution based on presence-absence surveys, identification of presence based on species detection is straightforward, but it becomes much more difficult to assert absence based on a failure to detect the species at a site. In these cases, the question remains: Is the species truly absent from the site or did we just fail to detect it? Bull trout, a Threatened species in Alberta, may be particularly hard to detect because it is secretive, patchily distributed across watersheds, and often occurs in low numbers. During the Clearwater River study, we assessed our ability to detect bull trout and the stream habitat factors that impact detection. We found the current sampling standard under typical environmental conditions gave us a very high probability (>90%) of detecting bull trout and that, depending on the goals of the study, sampling effort could be reduced substantially (by at least 30%) without jeopardizing our results. These findings have important implications for the efficient design and delivery of future watershed-scale fish distribution assessments. We chose to publish the Clearwater River Core Area Bull Trout Status study results in a scientific journal because peer review and communication of study results are crucial components of the scientific process. Our paper, “Estimating occupancy and detection probability of juvenile bull trout using backpack electrofishing gear in a west central Alberta watershed” was published in the Canadian Journal of Fisheries and Aquatic Sciences in spring 2015.

Annual Summaries

We are working hard to upload all past summaries. If there is a report you would like to see that isn't presently here, please email

Title Year Category
Clearwater River Core Area Bull Trout Status 2014-2015 1