Behavioral Responses of Paddlefish, Lake Sturgeon, and Fathead Minnows to Electromagnetic Fields

Hydrokinetic devices and cables used to transmit electrical current to shore will both create electromagnetic fields (EMF) that may be strong near the source but dissipate rapidly with distance.  The most likely potential for adverse effects is among bottom-oriented organisms that occupy habitats near transmission cables laid on the river bed.  Although a chronic response to long-term exposure is possible, we believe that a more likely impact could be from a rapid response to an immediate or short-term exposure. For example, disorientation caused by a network of underwater electrical transmission cables could affect normal movement patterns, feeding, or predator avoidance. We exposed paddlefish Polyodon spathula, lake sturgeon Acipenser fulvescens, and fathead minnows Pimephales promelas to DC ferrite bar magnets and AC electromagnets and evaluated immediate and short-term (1-2 days) behavioral responses. During 24-48 hrs exposure of individual adult minnows and juvenile sturgeon to ferrite and electromagnets we saw no evidence of avoidance or attraction and only a possible indication that level of activity was affected. Rapid responses to an immediate exposure were tested in a round tank with an electromagnet that could be turned on as a fish swam in close proximity. Fish behavior was recorded with a high speed camera and videos were analyzed for a variety of possible responses, such as change in swimming speed or direction, gill flaring, shaking, and other startle responses. No responses to variable magnetic fields were observed among paddlefish, but lake sturgeon exhibited a startle response after nearly every exposure. Magnetic field strength was subsequently varied to identify the lowest level that induced detectable responses in lake sturgeon.