The battle between boats and killer whales off Portugal may soon find a solution as authorities plan to test new sonic devices to scare off marine mammals.

The Portuguese National Association of Passenger Ships aims to protect sailing ships from killer whales that have deliberately begun to damage and sink ships, and even to teach their offspring this. While the reason behind the killer whales’ behavior remains a mystery, scientists have put forward various theories, ranging from revenge to playful behavior or irritation.

Acoustic deterrents that can minimize interaction between killer whales and sailboats will reportedly be tested this summer to keep ships safe. These devices are similar to shark deterrent devices that make sounds that mimic the calls of killer whales and are currently used to deter marine predators.