Just like people in a bar or other noisy location, North American right whales increase the volume of their calls as environmental noise increases; and just like humans, at a certain point, it may become too costly to continue to shout, according to marine and acoustic scientists.
"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, assistant professor of acoustics and research associate, Applied Research Laboratory, Penn State. "The ability to change vocalizations to compensate for environmental noise is critical for successful communication in an increasingly noisy ocean."
Right whales are large baleen whales that often approach close to shore. They may have been given the name because they were the right whales to hunt as they are rich in blubber, slow swimming and remain afloat after death. Consequently, whalers nearly hunted these whales to extinction. Currently right whales are monitored to determine the health and size of the population. The northern and southern right whales are on the endangered species list.
"Right whale upcalls are used extensively for passive acoustic monitoring in conservation efforts to protect this endangered species," said Parks.
Whales produce upcalls, sometimes called contact calls, when they are alone or in the process of joining with other whales. An upcall begins low and rises in pitch. It is the most frequent call produced by right whales.
Parks and her colleagues, Mark Johnson and Peter L. Tyack, Woods Hole Oceanographic Institution and Douglas Nowacek, Duke University, looked at short-term modifications of calling behavior of individual North Atlantic right whales in varying environmental noise situations. They report their results in today's (July 6) issue of Biology Letters.
The researchers' data came from right whales tagged with acoustic suction cup tags. They listened to tag r
|Contact: A'ndrea Elyse Messer|