Effects of vertical electric barrier on the behaviour of common carp

When managing invasive fishes, permanent barriers may be best in preventing spread; however, they may not be feasible due to costs and logistical constraints. Alternatively, non-permanent barriers using electricity, light, sound, pressure, bubbles, CO2, and other stimuli are being developed and deployed in efforts to limit the spread of aquatic invasive species or to achieve fish guidance and conservation. However, the effectiveness of these barriers is quite variable and testing is often lacking for both target and non-target species. We conducted a series of laboratory trials to examine the effects of a vertical electric barrier on behaviour of common carp Cyprinus carpio (Linnaeus, 1758). In response to the electric field, common carp reduced passing the electric barrier significantly, exhibiting different behaviours when interacting with the electric barrier, and spent more time away from the electric barrier when it was turned on during the stimulus period compared to pre- and post-stimulus periods. Our results suggest that a relatively weak electric gradient (i.e., voltage gradient: 0.2-0.4 V.cm(-1), power density: 3-42 mu W.cm(-3)) can inhibit the movement of common carp. Our results also highlight the importance of detailed examination of behavioural responses of target species when evaluating and considering fish-deterrent technologies.