[MARMAM] New Publication: Migratory behavior of gray whales tracked using a hydrophone array
rguazzo at ucsd.edu
Mon Oct 30 11:04:19 PDT 2017
My co-authors and I are pleased to announce the following open-access
Guazzo RA, Helble TA, D’Spain GL, Weller DW, Wiggins SM, Hildebrand JA
(2017) Migratory behavior of eastern North Pacific gray whales tracked
using a hydrophone array. PLoS ONE12(10): e0185585.
Eastern North Pacific gray whales make one of the longest annual migrations
of any mammal, traveling from their summer feeding areas in the Bering and
Chukchi Seas to their wintering areas in the lagoons of Baja California,
Mexico. Although a significant body of knowledge on gray whale biology and
behavior exists, little is known about their vocal behavior while
migrating. In this study, we used a sparse hydrophone array deployed
offshore of central California to investigate how gray whales behave and
use sound while migrating. We detected, localized, and tracked whales for
one full migration season, a first for gray whales. We verified and
localized 10,644 gray whale M3 calls and grouped them into 280 tracks.
Results confirm that gray whales are acoustically active while migrating
and their swimming and acoustic behavior changes on daily and seasonal time
scales. The seasonal timing of the calls verifies the gray whale migration
timing determined using other methods such as counts conducted by visual
observers. The total number of calls and the percentage of calls that were
part of a track changed significantly over both seasonal and daily time
scales. An average calling rate of 5.7 calls/whale/day was observed, which
is significantly greater than previously reported migration calling rates.
We measured a mean speed of 1.6 m/s and quantified heading, direction, and
water depth where tracks were located. Mean speed and water depth remained
constant between night and day, but these quantities had greater variation
at night. Gray whales produce M3 calls with a root mean square source level
of 156.9 dB re 1 µPa at 1 m. Quantities describing call characteristics
were variable and dependent on site-specific propagation characteristics.
Regina A. Guazzo
Scripps Institution of Oceanography
University of California, San Diego
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