A pristine area of the Bering Sea is one baseline for comparisons. In the course of a typical week, one ship might pass by. At the other extreme is Haro Strait, an area just north of Puget Sound that's between British Columbia and the San Juan Islands, where there are so many ships they are difficult to count.
Sixty percent of the time, Haro Strait's sound budget is dominated by shipping noise, Nystuen has found. It's also heavily used by killer whales.
"If the food is there, do the orcas care?" he asks. "That's one for the biologists to determine."
Contact: Sandra Hines
University of Washington