A recent study reveals that this one threat endangers orcas more than any other.
Killer whales have few natural predators, but man may prove to be the species that finally does the majestic beast in. According to a report from the Vancouver Sun, a new study has shown the noise caused by shipping traffic throughout the Salish Sea is wreaking havoc on orcas’ ability to hunt and communicate with each other.
Scientists studying the noise pollution in the Strait of Juan de Fuca and the Puget Sound have shown that the low-frequency rumbles caused by massive containerships has an effect on baleen whales, the orcas’ larger cousins. The recent study, however, takes a closer look at the high-frequency noise emitted by ships, which was found to travel much further than anyone believed possible.
Killer whales rely on echolocation to find food and other individuals. They emit a high-frequency whine or click and use sensors to calculate the distance between their head and another object. The study’s lead author, Scott Veirs of Seattle’s Beam Reach Marine Science and Sustainability School, says that shipping activities in these waters could be seriously disrupting the activities of the orcas.
“If you listen, you quickly learn that whales are wonderfully vocal, but also that their environment is filled with ship noise,” Viers said.
Researchers have long believed that ships and orcas operate on different “channels,” so to speak – that is, that the frequencies emitted by ships and the ones used by orcas to communicate didn’t overlap whatsoever. The recent study, however, reveals that scientists were searching in the wrong place for high-frequency noises coming from massive ships.
Researchers believed that the noise generated by ships that was likely to bother killer whales is likely to dissipate after it travels for about 5 kilometers. As scientists decided to listen closer for the type of noise they imagined was affecting orca populations, they were stunned to find that nearly all of the vessels they observed were making high-frequency noise.
Orcas are also known to congregate around established shipping routes, so their level of exposure to this ship noise remains unknown. New vessels are being designed to address the issue of submarine noise pollution, and listening devices are being installed in harbors to determine when the potential for disturbance is the highest.
A press release describing the details of the recent study can be found here.