Preliminary assessment of sensory deterrents for reducing threatened elasmobranch bycatch in northern Australian gillnet fisheries

The study evaluated if green LED lights and pulsed electrical deterrents (SharkGuard) could reduce bycatch of threatened elasmobranchs in Northern Australia gillnet fisheries. 23 paired deployments of LED lights (Fishtek Marine) and 7 electric deterrent trials were analyzed. Nets with green LED lights caught 35% fewer elasmobranchs, while also resulting in a significant increase (76%) of bony fish catch (however, commercially-targeted species of bony fish were not caught significantly more in the LED nets). Electric deterrents did not significantly reduce bycatch or fish catch, however, the small sample size limits the ability to detect meaningful effects. Both green LEDs and electric deterrents showed moderate effects related to reduced sawfish (Pristis clavata, P. zijsron, Anoxypristis cuspidata) catch per unit effort (CPUE), particularly for the electrical deterrents, which could be explored in a larger study.