Potential of creating seal-free fishing areas with seal deterrents

Damages to fisheries caused by growing seal populations have markedly increased in recent decades in many coastal regions around the world. In the Baltic Sea, solutions to reduce these damages have largely focused on modifying fishing gear but this has been insufficient for solving the problem. We tested whether straits to shallow inshore areas could be “closed” from seals by seabed-mounted acoustic seal deterrent devices (ADDs) and thereby create seal-free fishing areas. So far, we have tested such “sound-fences” only on relatively narrow straits, up to 200 m in width. Our experiments suggest that seabed-mounting would be a technically feasible method to discourage seals from entering through straits into inshore bay areas. Additional methodological development is needed to close wider straits and to make the method both easy to use and reliable. We discuss the challenges and potential of this new method.