[MARMAM] New publication on noise levels received by endangered killer whales

Marla Holt - NOAA Federal marla.holt at noaa.gov
Thu Aug 3 10:58:39 PDT 2017

Dear Colleagues,

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

Holt, M.M
*., Hanson, Giles, D.A., M.B., Emmons, and Hogan, J.T. 2017. Noise levels
received by endangered killer whales (Orcinus orca) before and after the
implementation of vessel regulations. Endangered Species Research 34:
15-26.  *
DOI: *https://doi.org/10.3354/esr00841* <https://doi.org/10.3354/esr00841>

Whale watching is often conducted from motorized vessels, which contribute
to underwater noise pollution and can disturb marine mammals. Protective
measures can ameliorate some effects of disturbance, but it is crucial to
empirically assess the effectiveness of such measures, particularly for
endangered species. We quantitatively compared noise exposure to endangered
southern resident killer whales before and after US federal vessel
regulations were established to protect this population from disturbance by
vessels and sound. We expected to see a reduction in noise exposure to this
population from vessel sound propagation loss due to a doubling of the
minimum viewing distance relative to a prior state law. Noise levels were
empirically measured from digital acoustic recording tags (DTAGs)
suction-cup attached to killer whales in transboundary critical habitat. We
collected concurrent vessel data during DTAG deployments to relate to
received noise levels at the animal. Results of a linear mixed model
analysis that included 10 explanatory variables in candidate models
revealed that noise was best predicted by animal ID, vessel count, vessel
speed category, and year. Vessel count and speed category were positive
predictors of noise levels. Vessel regulations (before vs. after
implementation), country, and average vessel distance were not significant
predictors of noise levels, although only 1 yr of baseline data limited
assessment. These findings inform managers about the effectiveness of
current regulations for viewing killer whales and are applicable to other
cetacean species that are exposed to vessel noise from whale-watching



Marla M. Holt, Ph.D.
Research Wildlife Biologist
Marine Mammal & Seabird Ecology Team, Conservation Biology Division
NOAA/NMFS Northwest Fisheries Science Center
2725 Montlake Blvd East
Seattle, WA 98112
Phone: 206.860.3261, Fax: 206.860.3475
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