We are studying fishes associated with a tidal-stream energy project in Cobscook Bay, the north eastern-most bay of the United States, at the entrance to the Bay of Fundy. Tidal energy devices under consideration are Ocean Renewable Power Company’s (ORPC) TidGen® and OCGen® systems. Our research was initiated in 2009 to determine the ‘natural’ vertical distribution and density of fishes. Baseline data enabled the detection of turbine effects, and will be used to estimate the likelihood that fish encounter a tidal turbine once installed at a fixed height in the water column. Since then, we have built on this research, adding studies of fish behaviour in response to a tidal energy device in the near-field (within 3m) and mid-field (up to 200m away). Approaches at multiple spatial and temporal scales are proving useful in deciphering the previously unknown behaviours of fish in response to marine hydrokinetic (MHK) devices and enabling more focused methods for future monitoring.