Pulsing sounds made by technology used to monitor fish stocks may affect how baleen whales communicate, even at great distances.
Marine biologists working in Massachusetts waters noticed that humpback whales sang less during the fall of 2006, when a low frequency signal showed up in their recordings. They eventually traced the signal to some acoustic sensing equipment that was part of a scientific study off Maine’s coast, about 120 miles from where they were studying seasonal changes in whale songs in Georges Bank.
The scientists recorded more frequent whale vocalizations (listen below) during the same time of year in 2008 and 2009, when the study’s Ocean Acoustic Waveguide Remote Sensing equipment was not being used. This suggests the whales reacted to the low-level sounds by silencing their songs.“It’s fascinating that we saw this behavioral response over such a large distance,” said Denise Risch, a marine biologist at the National Oceanic and Atmospheric Association and lead author of research published Jan. 11 in PLoS One.