A disproportion in bowhead whale call counts around an acoustic array during the fall 2012 migration in the Chukchi Sea, Alaska: An investigation into the potential of acoustic masking

A long-term passive acoustic study in the Chukchi Sea monitors the bowhead whale (Balaena mysticetus) migration between their summering and wintering grounds in the Beaufort and Bering Seas, respectively. A hexagonal array offshore from Point Lay, AK was located near the center of their migratory corridor in the falls of 2009 through 2011. In 2012 however, there was a large difference in the number of acoustic detections across the array, with call counts close to three times higher in its northwest section compared to its southeast. An increase in vessel traffic in the area resulted in higher ambient noise conditions for much of the summer. This paper investigates the possibility of acoustic masking of calls due to this increase in background noise levels.