Baleen whales often get entangled in fishing gear, which is potentially very dangerous for these animals. Scientists have been trying to come up with solutions for these unwanted entanglements for decades. One measure is to include acoustic alarms that function to alert whales to the presence of fishing gear. This is a great idea, but has sometimes proven to be tricky to put into practice. The whales need to notice the sound, and also associate it with nets or lines. Also, the right sound is different for each whale, and for many species we do not know yet how we can effectively use these alarms. For example, great successes have been booked to reduce the entanglement of harbour porpoises, common dolphins and beaked whales. For other species, like humpback whales and other baleen whales, whales do not seem to respond to the alarms yet. It is an ongoing topic of research, with hopefully big breakthroughs in the future, to guarantee that all cetaceans can swim freely and securely in our oceans.
by Judith Kok