Tidal currents help shape coastal marine environments and are essential in life cycles of many fish species.  The effects of tidal energy devices on fish are of high concern to regulators, industry, fishers, and other stakeholders, but are difficult to predict because fish behavior within fast tidal currents is largely unstudied.  My PhD work at UMaine took place at a tidal energy site in Cobscook Bay, Maine.  I used hydroacoustics to describe fish reactions to a tidal energy device, to better understand the natural presence of fish at the site, and to provide guidance for future monitoring of device effects in these difficult environments.  I found that fish moved with the current, but those approaching the device showed signs of avoiding it by adjusting their direction slightly.  A two-year record of hourly fish passage rate at the depth of the turbine, after it had been removed, showed that fish passage rate (and therefore potential encounter rate with the turbine) changed dramatically over time with the dominant environmental patterns (tidal, daily, lunar, and seasonal cycles).  By timing surveys of fish abundance at tidal energy sites with these cycles, the quality of long-term monitoring results can be improved.  Using this approach at tidal energy sites could therefore increase our ability to detect device effects without requiring expensive continuous sampling over a long time.  These findings are likely to be applicable to other tidal energy sites, but study designs and results need to be considered in the context of species and life stages of fish present.  I am now beginning a post-doc at Acadia University, where I will be applying and building on these methods in a much higher-energy tidal environment.