[MARMAM] new publication on Cook Inlet beluga & noise

Manuel Castellote - NOAA Affiliate manuel.castellote at noaa.gov
Tue May 28 08:39:40 PDT 2019

Dear MARMAM recipients,
We are happy to announce our new publication:

Castellote, Thayre, Mahoney, Mondragon, Lammers & Small. 2018.
Anthropogenic Noise and the Endangered Cook Inlet Beluga Whale,
*Delphinapterus leucas*: Acoustic Considerations for Management. Marine
Fisheries Review 80(3): 63-88.

Anthropogenic noise has been identified as a major threat for the recovery
of the endangered Cook Inlet beluga, *Delphinapterus leucas*, population,
but little is known about its occurrence in critical habitat. We analyzed
8,756 h of acoustic recordings from different locations and months in Cook
Inlet, Alaska, to describe anthropogenic noise, evaluate the potential for
acoustic impact to Cook Inlet belugas, and provide management
recommendations. Nine total sources of noise were identified: commercial
ship, dredging, helicopter, jet aircraft (commercial or military
non-fighter), fighter jet, propeller aircraft, outboard motor, pile
driving, sub-bottom profiler, as well as four repetitive unidentified noise
sources. Several noise metrics were compared across noise sources, months,
and locations. A total of 6,263 anthropogenic acoustic events were detected
and classified, for a total duration of 1,025 h representing 11.7% of the
sound recordings analyzed. Anthropogenic noise was present in every day
sampled. The natural background noise (i.e., ambient noise without
anthropogenic contribution), in areas where currents and vegetative debris
did cause minimal self-noise, was below 120 dBrms re. 1μPa for 94% to 100%
of the time; much lower than previously reported and unsupportive of the
current application of the elevated behavioral harassment threshold for
non-impulsive noise of 125 dBrms. Based on spectral received levels and
spatial and temporal prevalence, several anthropogenic noise sources in
Cook Inlet have the potential to chronically mask beluga communication and
hearing in most of the locations and periods sampled for this study.
Current activities (e.g., shipping, dredging) exceed behavioral harassment
levels on a daily basis in a significant portion of the critical habitat.
Ship noise was identified as the top priority focus for noise mitigation
management actions. A high concentration of noise sources was identified in
the lower region of Knik Arm. This area is recommended for further research
to evaluate the potential for beluga displacement and the basis to start
considering cumulative impact effects in the permitting process. The amount
of detected unidentified machinery noise or unclassifiable noises
highlights the need for further research in coordination with industry, in
particular in areas of oil and gas production (i.e., Trading Bay) or
intense shipping related activities (i.e., facilities). Finally,
unpermitted activities were also detected suggesting the need for further
enforcement and outreach to increase the awareness towards this endangered
population of belugas and the negative consequences of underwater noise in
their protected habitat.

The article can be downloaded at no cost in the following link:

Manuel Castellote

Manuel Castellote, PhD
Joint Institute for the Study of the Atmosphere and Ocean, University of
Cetacean Assessment and Ecology Program, Marine Mammal Laboratory
Alaska Fisheries Science Center, NOAA Fisheries
7600 Sand Point Way N.E. F/AKC3
Seattle, WA 98115-6349
(206) 526-6866 (voice)
(206) 526-6615 (fax)
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