1. Applied Ocean Physics and Engineering Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543,
USA
2. Marine Physical Laboratory, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California
92093, USA
3. University of Washington and National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Alaska Fisheries
Science Center Marine Mammal Lab, Seattle, Washington 98105, USA
4. School of Earth and Ocean Sciences, University of Victoria, Victoria, Canada