LAUSR

Providing safe downstream passage for outmigrating freshwater eels around hydroelectric facilities, especially on large river systems, is a daunting challenge. With engineering limitations on the installation of physical barriers, behavioural guidance research is needed to steer outmigrating eels towards safe passage or collection facilities. We exposed late, yellow-stage American eel Anguilla rostrata to different colours and strobing frequency of light-emitting diode (LED) light, or to unlit control trials, in y-maze dichotomous choice tests. Eels demonstrated initial attraction towards the y-maze structure and entered the dark (control) side more often and for a longer duration compared to the illuminated side. Blue light strobing at 30 Hz elicited the greatest initial avoidance response and eels spent less time on the light side with this treatment, and we recommend that this setting be tested further under field conditions. Although the initial avoidance of all light settings attenuated over the 5 min observations, this attenuation may be less relevant when eels are engaged in active migration, and thus may provide a viable means of guiding eels to safe outmigration paths.