Underwater noise from ships is making it tough for killer whales, or orcas, to find and catch their favorite fish, a recent study has found. Orcas (Orcinus orca) rely heavily on sound to hunt. They emit ultrasonic echolocation clicks that bounce off objects. By listening for the echoes of these clicks, the orcas can identify objects that are around, including prey like salmon. Since orcas “see” with sound, researchers wanted to understand how ship noise in the Salish Sea, off the west coast of the U.S. and Canada, affects their hunting. So they tagged 25 orcas from two threatened populations: the northern resident killer whales and the southern resident ones. The tags, deployed between 2009 and 2014, tracked the orcas’ movements and recorded underwater sounds, including noise from ships that can get louder than a rock concert. The study found that the louder the ship noise, the longer orcas spent searching for fish, and with less success. This is likely because vessel noise interferes with orcas’ abilities to receive the returning echoes of their echolocation clicks, causing them to miss important information, Jennifer Tennessen, the study’s lead author from the University of Washington, U.S., told Mongabay. “The noise is analogous to foggy conditions where the whales are unable to see as far using echolocation,” Dimitri Ponirakis, a noise analyst at Cornell University, U.S., who wasn’t involved in the study, told Mongabay in an email. “This means that they must expend more energy to find the same amount of prey as…This article was originally published on Mongabay
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