The Effect of Thermal Stress on the Physiology of Juvenile Bull Trout

To accurately model bull trout habitat, we need to know what temperatures they need to thrive. Research from the United States found that temperatures should be below 15 degrees to be optimal for bull trout; this project will determine if that is accurate for Alberta populations.

Dr. Analisa Lazaro-Côté at the University of Manitoba had previously determined thermal stress levels of fish kept at different temperatures in the lab. They did this by swabbing the fish’s mucous layer and measuring the levels of molecules that are produced in response to thermal stress. Lazaro-Côté and our team used the same methods on fish from our Kakwa survey, which has a gradient of disturbance, and the Nahanni River in the NWT, which serves as a relatively undisturbed, reference watershed. The lab work and analysis are in progress.

This information will help determine in which areas bull trout are experiencing the most stress and may be integrated in stream temperature models being developed in other Water and Fish projects. This can lead to better predictions of suitable bull trout habitat considering our changing climate and increases in human-induced disturbances.