UNIVERSITY PARK, Pa., July 7 (UPI) — North American right whales can crank it up when they need to be heard over an environmental din, U.S. scientists found.
And just like their human counterparts in noisy locations, the whales may reach a point when it become too costly to shout, a Pennsylvania State University researcher said Tuesday in a release.
“The impacts of increases in ocean noise from human activities are a concern for the conservation of marine animals like right whales,” said Susan Parks, an assistant professor of acoustics and research associate with Penn State’s Applied Research Laboratory. “The ability to change vocalizations to compensate for environmental noise is critical for successful communication in an increasingly noisy ocean.”
The upcall of right whales — believed to be so-named because they were the “right whales” to hunt because they’re rich in blubber, slow swimming and remain afloat after death — are used for passive acoustic monitoring in conservation efforts to protect this endangered species, Parks said.
Researchers listened to acoustic recordings of tagged whales, discovering the whales increased the amplitude, or energy, of their upcalls without changing the frequency as background ocean noise increased. The finding suggests right whales can maintain the signal-to-noise ratio of their upcalls in moderate levels of ocean noise, Park said.
“To our knowledge, this is the first evidence for noise-dependent amplitude modification of calls produced by a (right) whale,” Parks said.
Whether the whales can maintain their communication range in noisier environments still must be tested, she said.
“Ocean sound levels will probably continue to increase due to human activities and there is a physical limit to the maximum source level that an animal can produce,” she said.
Parks, Mark Johnson and Peter Tyack of the Woods Hole Oceanographic Institution; and Douglas Nowacek of Duke University published their findings Tuesday in Biology Letters.
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