Assessing occupancy of freshwater fishes in urban boat slips of Toronto Harbour

Hardening of natural shorelines in urban aquatic ecosystems can result in a loss of fish habitat and productivity. The north shore of Toronto Harbour (Lake Ontario) has been converted to hardened boat slips for commercial, industrial and recreational purposes, but its potential utility as fish habitat has not been evaluated. The objective of this study was to determine whether fish frequented and utilized four slips in the Inner Harbour of Toronto. Two western boat slips are adjacent to some natural features and have undergone some rehabilitation to increase the complexity of aquatic habitat (i.e. addition of large substrate, overhead cover, and in-water structure). In contrast, the two eastern slips are deeper and more influenced by the turbid Don River. We assessed the timing and duration of occupancy within all four slips for seven fish species using acoustic telemetry. In just under a year, tagged fishes spent