[MARMAM] New publications on Rice's whales

Melissa Soldevilla - NOAA Federal melissa.soldevilla at noaa.gov
Mon Aug 1 19:28:51 PDT 2022

Dear colleagues,

On behalf of my co-authors, I'm happy to share our two new publications on
Rice's whales from the Gulf of Mexico.

1. Melissa S. Soldevilla, Katrina Ternus, Ashley Cook, John A. Hildebrand,
Kaitlin E. Frasier, Anthony Martinez, and Lance P. Garrison , "Acoustic
localization, validation, and characterization of Rice's whale calls", The
Journal of the Acoustical Society of America 151, 4264-4278 (2022)

ABSTRACT: The recently named Rice's whale in the Gulf of Mexico is one of
the most endangered whales in the world, and improved knowledge of
spatiotemporal occurrence patterns is needed to support their recovery and
conservation. Passive acoustic monitoring methods for determining
spatiotemporal occurrence patterns require identifying the species' call
repertoire. Rice's whale call repertoire remains unvalidated though several
potential call types have been identified. This study uses sonobuoys and
passive acoustic tagging to validate the source of potential call types and
to characterize Rice's whale calls. During concurrent visual and acoustic
surveys, acoustic-directed approaches were conducted to obtain visual
verifications of sources of localized sounds. Of 28 acoustic-directed
approaches, 79% led to sightings of balaenopterid whales, of which 10 could
be positively identified to species as Rice's whales. Long-moan calls,
downsweep sequences, and tonal-sequences are attributed to Rice's whales
based on these matches, while anthropogenic sources are ruled out. A
potential new call type, the low-frequency downsweep sequence, is
characterized from tagged Rice's whale recordings. The validation and
characterization of the Rice's whale call repertoire provides foundational
information needed to use passive acoustic monitoring for better
understanding and conservation of these critically endangered whales.

2.  Soldevilla, M.S., Debich, A.J., Garrison, L.P., Hildebrand, J.A., &
Wiggins, S.M. (2022). Rice’s whales in the northwestern Gulf of Mexico:
Call variation and occurrence beyond the known core habitat. Endangered
Species Research, 48:155-174. https://doi.org/10.3354/esr01196

ABSTRACT: The endangered Rice’s whale *Balaenoptera ricei*, with fewer than
100 individuals remaining, is the only year-round resident baleen whale
found in the Gulf of Mexico (GOM) and occurs primarily along the
northeastern shelf break near De Soto Canyon. Historical whaling records
and predictive density modeling suggest that these whales potentially could
occur more broadly throughout the GOM. High levels of anthropogenic
activities in the GOM, including oil and gas exploration and extraction,
fisheries, shipping, and the unprecedented *Deepwater Horizon* oil spill,
highlight the need to better understand the distribution, ecology, and
threats to this small population to improve protection of these endangered
whales. We used long-term passive acoustic recordings from the northwestern
GOM shelf break to explore the extent of Rice’s whale distribution in the
northern GOM and to evaluate whether they exhibit seasonal movements
throughout this range. We describe 6 new stereotyped variants of Rice’s
whale long-moan calls, found predominantly in the western GOM, that share
distinctive features with typical eastern long-moans, including a 150 Hz
starting tone, an approximately 100 Hz tail with amplitude modulation, and
a long call duration ranging from 10 to 35 s. Western long-moan variants
were detected at 3 northwestern sites, occurring sporadically throughout
the year on as many as 16% of days at the westernmost site, and
infrequently at an eastern core-habitat site. These results indicate that
some whales persistently occur over a broader range in the GOM than
previously understood, which is important to consider when designating
critical habitat and assessing threats to this Critically Endangered

Please feel free to contact me with any questions.

Best wishes,

Melissa Soldevilla, PhD
Research Fishery Biologist
Marine Mammal & Turtle Division
NOAA Southeast Fisheries Science Center
75 Virginia Beach Drive
Miami, FL 33149
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