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NOAA's Marine Mammal Acoustic Guidance

Status of NOAA's Guidance for Assessing the Effects of Anthropogenic Sound on Marine Mammals

The National Oceanic and Atmospheric Administration (NOAA) is holding a second public comment period on our draft acoustic guidance for assessing the effects of anthropogenic sound on marine mammal species [pdf] under our jurisdiction.

This revised draft includes changes made due to comments received during the initial public comment period and new science we have received and put through peer review. Changes made include:

The second public comment period will last 45-days and begin on July 31. Comment now  (Note: Please be sure to be commenting on the most recent version of the Guidance, which is the dated July 2015).

NOAA will review and incorporate public comments from the first and second public comment periods into our final Guidance document, which we expect to finalize late 2015.

Purpose of the Acoustic Guidance

The Guidance provides acoustic threshold levels for onset of permanent threshold shift (PTS) and temporary threshold shifts (TTS) for all sound sources. It is intended to be used by NOAA analysts/managers and other relevant user groups/stakeholders, including other federal agencies to better predict a marine mammal’s response to sound exposure. The manner of response has the potential to trigger certain requirements under one or more of NOAA’s statutes (MMPA, ESA, and National Marine Sanctuaries Act).

To develop these acoustic threshold levels, NOAA has compiled, interpreted, and synthesized best available information currently available on the effects of anthropogenic sound on marine mammals, as well as developed a method for updating these levels through a systematic, transparent process. The document outlines NOAA's updated acoustic threshold levels and describes in detail how the thresholds were developed and how they will be updated in the future.

Due to the complexity and variability of marine mammal behavioral responses, NOAA will continue to work over the next year on developing guidance regarding the effects of anthropogenic sound on marine mammal behavior.

Process to Develop Acoustic Guidance

The process to finalize the guidelines includes the following steps:

  1. NOAA internal review
  2. External peer review
    » Initial Peer Review Report
  3. Public comment
  4. Finalize and release guidance

NOAA's draft acoustic Guidance [pdf] has undergone an internal review, 3 external peer reviews, and received informal input from key federal partners. 

External Peer Reviews

The first external peer review, which was completed September 2013, focused on the scientific and technical studies used in the analysis for the development of proposed onset PTS and TTS acoustic threshold levels. (Report link)

The second external peer review evaluates a U.S. Navy Technical paper provided to NOAA in January 2015 as part of the Navy's Phase 3 Acoustic Effects Analysis. The paper describes the Navy's proposed methodology for updating auditory weighting functions and subsequent numeric thresholds for predicting auditory effects (TTS/PTS thresholds) on marine animals exposed to active sonars and other active acoustic sources utilized during Navy training and testing activities. (Report link)

The third external peer review evaluates NOAA's proposed methodology for defining threshold usage for sources characterized as impulsive or non-impulsive. This methodology was modified using comments from the initial public comment period. (Report link)

More information about these additional peer reviews

First Public Comment Period

The comment period on the initial draft guidance opened in December 2013 (78 FR 78822) and closed on March 13, 2014 (79 FR 4672). Comments received are available on

During this time NOAA Fisheries held a public meeting to inform interested parties and solicit comments on the proposed acoustic guidance. The meeting was held on January 14, 2014, in the NOAA Science Center in Silver Spring, MD. A transcript from the meeting is available as well as the Public Meeting One-Pager [pdf] and Presentation [pdf].

Second Public Comment Period

The second public comment period ends on September 14, 2015. Comment now

Once the comments from the public comment periods are addressed, NOAA will finalize and release the acoustic guidelines for onset PTS and TTS.

Frequently Asked Questions Regarding NOAA's Acoustic Guidance are also available (updated July 2015).

For more information, please contact:

Amy R. Scholik-Schlomer
NMFS Protected Resources Acoustic Coordinator
1315 East West Highway
Silver Spring, MD 20910

Updated: July 30, 2015