When rare North Atlantic right whales (Eubalaena glacialis) swim through noisy water, they make louder calls to each other, presumably to try make sure they can be heard over the din.
Susan Parks from Penn State University led a team who tagged 14 North Atlantic right whales in the Bay of Fundy, in Canada, with acoustic tags that recorded their calls as well as background noises.
At times when background noise was louder – probably because of commercial shipping activity nearby – individual, lone whales called louder. Birds and Primates are known to do the same thing when things get noisy around them.
Shouting louder isn’t necessarily a great idea for whales – it takes more energy, it makes them more likely to be heard by predators, and the important messages they are trying to communicate could get mixed up. Ultimately, whales may not be able to hear each other, at least not over such long distances.
This study has important implications for conservation efforts because the calls studied by Parks and the team - so-called “up-calls” – are picked up by automated sound recorders set up in the sea to give an estimate of how many of these rare whales there are in the area – providing crucial data for population monitoring.
If whales are changing their calls in noisy waters it could make these automated whale detectors inaccurate.
So this study not only provides yet more evidence that marine mammals could fair badly as the oceans get noisier, but because we may have to look again at the ways we use to work out how many of them are left.