Behaviour and Space Use of Sea Lamprey Near Traps at a Hydroelectric Generating Station

Invasive species are the focus of management concern in many ecosystems. Trapping is a potentially valuable form of control. I used telemetry to track sea lamprey immediately downstream of traps at a hydro-generating station. I tested if manipulations of discharge influenced the behaviour of lamprey in a manner that increased their susceptibility to trapping. Encounter rates with traps increased when discharge was high, but rates of departure without entering traps simultaneously increased. I further tested whether lower trapping success is a consequence of space use by lamprey immediately downstream of traps. Lamprey aggregated away from where traps were located. Differences in vertical space use with respect to discharge suggest that flows exiting the generating station attract sea lamprey to the station wall, but also away from the traps. To improve trap success, managers must make traps more attractive or place traps in locations where lamprey are most likely to aggregate.