Altered Fish Behavior Near a Static Hydrokinetic Turbine

Hydrokinetic (HK) tidal power devices use energy from tidal currents to generate electricity.  HK turbines have an open design and are expected to be more environmentally friendly than conventional hydropower (dams).  However, a major concern is the effects of HK turbines on fishes.  These effects will largely be determined by how fish respond to a device (e.g., avoidance) and the distance at which the response occurs.  We investigated the responses of fish 10-20 m from an HK device in Cobscook Bay, Maine, when the turbine was static (brake applied, not rotating).  Fish behavior (movement direction) was observed continuously from April to May, 2013, using a split beam echosounder aimed across the turbine’s face, sampling in front of the turbine and beside it (a control area).  Fish were tracked in three dimensions as they approached the device (flood tide) or departed from it (ebb tide).  Preliminary results from flood tide data indicate that some fish responded to the turbine at the ranges sampled: most fish moved with the current, but movement was more variable in front of the turbine than in the control area.  Effects of environmental factors (diel stage and current speed) and fish size on behavior will be presented.