Evaluation of a portable underwater video camera to study fish communities in two Lake Ontario tributaries

We evaluated the suitability of a portable underwater camera to characterize fish communities and streambed particle sizes in two Lake Ontario tributaries. Two video sampling methods were used-quadrat (a stationary camera with a fixed viewing area) and line sampling (camera walked through the stream). Compared to electrofishing surveys, underwater camera data suggested simpler fish communities (biased towards salmonids) and smaller sized fish. Shallow water depths, turbulence, and obstructions (eg., woody debris) limited our ability to identify fish during some of the video samples. Video sampling-was able to detect a decreasing trend of fish abundance as water temperatures declined over the course of the study. There was also a strong agreement between measurements of streambed particle sizes done manually in the field and those done with both video sampling methods. The results suggest that a portable underwater camera system could be used to measure seasonal changes in habitat use by salmonid fish species and certain habitat features in streams and rivers.