Acoustic playback is better than food to trap one of the worst invasive fishes.

With the number of invasive alien species increasing globally, the management of invaded areas is constantly seeking innovative and effective solutions. Thanks to recent technological advances, acoustic signals are increasingly used in species management, either as an indicator of the presence of species or as a stimulus to repel species from risky areas or attract species for monitoring or eradication purposes. However, acoustic-based solutions are still rarely used by freshwater managers. In the present study, we explored the potential of acoustic playback to trap the round goby Neogobius melanostomus, a highly invasive aquatic species. We equipped traps with specifically-designed cost-effective, easy-to-deploy underwater speakers to broadcast resynthesized reproductive calls and tested four conditions by crossing the presence or absence of acoustic and food. The traps were deployed in Lake Sainte-Croix and Lake Brunet: two French lakes where round goby invasion is ongoing. Consistent with a previous test of acoustic trapping conducted on round gobies from the Great Lakes, broadcasting reproductive calls overall improved trapping success. Acoustic alone was the best trap configuration with a tendency to have more round gobies in the traps. By contrast, food increased the proportion of bycatch and was particularly attractive to crayfish, which reduced the probability of finding round gobies in the traps. Contrary to our expectation, the proportion of reproductive gobies in the traps was not increased by acoustic signals. Our results provide support for the inclusion of acoustic approaches in the toolbox of freshwater managers.