[MARMAM] New Publication: Gray whale call and blow rates

Regina Guazzo rguazzo at ucsd.edu
Fri Aug 30 11:43:49 PDT 2019


Dear colleagues,

My co-authors and I are pleased to announce the publication of the
following open-access publication:

Guazzo RA, Weller DW, Europe HM, Durban JW, D'Spain GL, Hildebrand JA
(2019) Migrating eastern North Pacific gray whale call and blow rates
estimated from acoustic recordings, infrared camera video, and visual
sightings. Scientific Reports 9:12617.

DOI: https://doi.org/10.1038/s41598-019-49115-y

Abstract:  During the eastern North Pacific gray whale 2014–2015 southbound
migration, acoustic call recordings, infrared blow detections, and visual
sightings were combined to estimate cue rates, needed to convert detections
into abundance. The gray whale acoustic call rate ranged from 2.3–24
calls/whale/day during the peak of the southbound migration with an average
of 7.5 calls/whale/day over both the southbound and northbound migrations.
The average daily calling rate increased between 30 December–13 February.
With a call rate model, we estimated that 4,340 gray whales migrated south
before visual observations began on 30 December, which is 2,829 more gray
whales than used in the visual estimate, and would add approximately 10% to
the abundance estimate. We suggest that visual observers increase their
survey effort to all of December to document gray whale presence. The
infrared camera blow rate averaged 49 blows/whale/hour over 5–8 January.
Probability of detection of a whale blow by the infrared camera was the
same at night as during the day. However, probability of detection
decreased beyond 2.1 km offshore, whereas visual sightings revealed
consistent whale densities up to 3 km offshore. We suggest that future
infrared camera surveys use multiple cameras optimised for different ranges
offshore.

I am happy to respond to any questions about this work at rguazzo at ucsd.edu

Thank you,

Regina

Regina A. Guazzo, PhD
Environmental Readiness Branch
Naval Information Warfare Center Pacific
(c) 908.507.1421
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