ANALYSIS OF BROOK TROUT SPATIAL BEHAVIOUR DURING PASSAGE ATTEMPTS OF CORRUGATED CULVERTS USING NEAR-INFRARED ILLUMINATION VIDEO IMAGERY (#64)
In a recent field study of brook trout passage performance in culverts, Goerig et al. showed better passage success in corrugated pipes than in smooth pipes, particularly among smaller fish. They suggested this result could be related to a better ability of smaller fish to exploit near-wall low velocity areas associated with corrugated culvert undulations. In order to test this suggestion, we used light-sensitive surveillance video cameras and near-infrared illumination to document the spatial behaviour of brook trout of various sizes in a corrugated culvert at different hydraulic conditions. Semi-automated image analysis was used to digitize fish position at high temporal resolution inside the culvert, which allowed calculating various spatial behaviour metrics, including instantaneous ground and swimming speed, path complexity, distance from side walls, velocity preference ratio (velocity at fish position/mean cross-sectional velocity) as well as number and duration of stops in forward progression. The presentation will summarize the main results of the study and discuss how they could be used to improve fish passage performance in roads and forest culverts.