AcousticEcology.org Special Report

NOAA Ocean Noise Criteria EIS

In early January 2004, the US National Oceanic and Atmospheric Administration (NOAA) initiated public involvement in the creation of new criteria to be used for issuing permits involving ocean noise.

Specifically, they are preparing the EIS to analyze the environmental impacts of several approaches to creating new "guidelines to determine what constitutes a ‘take' of a marine mammal under the Marine Mammal Protection Act (MMPA) and Endangered Species Act (ESA) as a result of exposure to anthropogenic noise in the marine environment."

The development of new noise criteria could be the most significant opportunity on the current horizon for public involvement and institutional re-thinking of the effects of human noise in the sea. Whether this opportunity is seized will depend on the breadth of substantive public participation, and on the willingness of agency planners to genuinely consider a full range of approaches to regulating ocean noise.

The first phase, scheduled to last until March 14, is the "scoping period." During this time, the public is invited to comment on NOAA's initial framing of the issue, and to suggest ways that their approach could be improved. Six to twelve months later, NOAA will issue a Draft Environmental Impact Statement, which will also be open for comments. Eventually, a final EIS will be issued, and new rules on acceptable noise exposures will be made.

The National Marine Fisheries Service (NMFS) is the sub-office of NOAA managing this process. NMFS hosted public meetings in four cities during January, to gather public input. The new standards will apply to industrial, military, and academic activities, and will govern the issuance of "small take" permits and "Incidental Harassment Authorizations".

Current Standards
The MMPA and ESA require permits to be issued when any marine mammal or endangered species will be affected by human activities. Permits allow "takes" of animals; this does not necessarily mean killing them (in fact, it rarely does); "takes" also include harassment. There are two statutory "levels" of harassment: Level A harassment covers activities with the potential to cause physical injury, while Level B harassment involves the potential for behavioral disruption. (In 2003, the definition of Level B harassment was loosened for military and academic research activities, so that these activities need permits only if they have a "significant potential" to injure an animal or are "likely to" disturb behavior "to a point where such behavioral patterns are abandoned or significantly altered.")

Since 1997, NMFS has used generic exposure level criteria in issuing permits. Working with results from a limited number of field studies, 180dB was set as the Level A harassment level (because noise louder than this can cause temporary or permanent hearing loss), and 160dB was set as the Level B harassment level (because noise louder than this can cause behavioral disruption, most commonly avoidance [i.e., changing course or moving away from the noise source]). (Notes: exposure levels for pinnipeds (seals and sea lions), have been slightly higher. Also, the Level B threshold is for pulsed noise, such as sonar and airguns; the Level B harassment threshold for continuous noise is 120dB.)

This approach, while having the virtue of being concrete and specific, has several shortcomings. Most important is the fact that ocean species vary widely in their sensitivity to sound, and especially to the frequency range which they hear. Thus this "one size fits all" noise standard likely misses the mark in most specific instances. The core of NMFS's new approach attempts to rectify this. Secondly, many environmentalists and some researchers feel that these levels are too high, across the board; 145dB is considered the highest safe level for human exposure to naval sonars, for instance, and some studies suggest that whale breathing and singing patterns are affected by noise levels as low as 95-110dB.

NOTE: The measurement of sound in water is rife with complexities. This special report assumes all units to be "re: one micro pascal", the standard water-borne sound reference point. Further confusion is caused by whether we are measuring "sound pressure level" or "energy flux density level", which incorporates energy over time. Frankly, I'm still not completely clear on the distinctions here (indeed, even acousticians who can decode these mysteries have differing opinions on how the various measurements may or may not relate to the acoustic experiences and physical sensitivities of marine creatures). In any case, to avoid the likelihood of making improper assumptions based on our experiences of sound in air, I suggest you take a look at the ocean acoustics section, linked in the box at the top of this page, and at other acoustics primers linked to from there.

New Criteria Alternatives
The approach being proposed by NOAA/NMFS represents their attempt to create a more nuanced scientific foundation for making permitting decisions. Four of the six proposed alternatives utilize a new matrix of categories which divides the current single set of standards into five "functional hearing groups" of marine creatures, and four types of sound sources. Thus the new approach would set different exposure levels for, say, dolphins (who hear mid-frequency sounds well) and blue whales (who hear low-frequency sounds well), when each is exposed to a given sound source (presumably a lower safety threshold would be set for the whales than the dolphins, if the source sound was low frequency, the assumption being that the whale would be more sensitive to the low frequency source).

While having the virtue of at least attempting to address species-specific sensitivities, the weak point of this approach is that we lack solid knowledge of the hearing sensitivities of many (actually, most) marine species. Thus, there will be many assumptions and extrapolations based on the best information we do have (with the stated goal of using conservative figures). Some of these are small jumps, such as using solid dolphin data to set standards for other species of dolphins. Others may be rather large leaps, such as using terrestrial animal sensitivity levels as basis for setting standards on ocean species lacking data.

The five initial alternatives proposed by NMFS are:
Alternative 1
No action alternative: use current standards.
Alternative 2
Level A Harassment: any noise louder than average ambient noise.
Level B Harassment: any noise louder than lowest possible ambient noise.
(BOTH WILL VARY WITH LOCATION, DEPENDING ON CURRENT AMBIENT NOISE LEVELS, INCLUDING BOTH NATURAL AND HUMAN NOISE)
Alternative 3
Level A Harassment: noise level that can trigger TTS (Temporary Threshold Shift, or short-term reduction of hearing sensitivity)
Level B Harassment: noise level at which 50% of the population exhibits behavioral avoidance of the noise.
Alternative 4
Level A: noise level that triggers PTS (Permanent Threshold Shift, or long-term hearing damage), less 6dB as a safety buffer (6dB is a doubling of noise intensity)
Level B: noise level that triggers TTS, less 6dB as a safety buffer
Alternative 5
Level A: noise level that triggers PTS
Level B: noise level that triggers TTS
Alternative 6
Level A: noise level that triggers PTS, plus 6dB (this alternative is designed to require a higher probability of exposed animals experiencing a meaningful change in hearing sensitivity)
Level B: noise level that triggers PTS, less 6dB

To read the Federal Register notice that contains the NOAA/NMFS proposals, including sections explaining the rationale behind their choices, see:
Federal Register notice, html: [READ NOTICE]
Federal Register notice, pdf: [DOWNLOAD NOTICE(pdf)]

Brief Comments on the Criteria
In the one example given in the notice, the proposed Alternatives 3 through 6 will all result in an increase in the allowable noise exposure (the example is for the best knowledge of grey whales' hearing sensitivities; all harassment levels increase except for Level B harassment in Alternative 3, which stays the same as it is now). This may reflect the opinion among some researchers that current standards are unnecessarily low (i.e., the limited studies we do have may suggest that the 180/160 dB standards are more conservative than necessary). This increase in apparent noise thresholds is also caused by a change in the way that sound exposure is calculated: the new approach (SEL, sound energy level) factors in cumulative and repeated exposures, resulting in a dB measurement that is higher than the current approach (SPL, sound pressure level). For example, a received sound that measures 180dB (SPL, current standard, regardless of duration of the sound) would, if it continued for 2 seconds, be measured as 183dB (SEL). More dramatically, a 179dB (SPL; below current Level A standards) that continued for 16 minutes, would measure 209dB (SEL, triggering Level A in two of the four alternatives using this approach). The acoustical physics, as well as the biological significance, of the new approach is, like everything else in this field, subject to debate among acousticians and biologists; however, the addition of some consideration of cumulative effects reflects an important expansion of regulatory consideration.

It appears that NMFS is content to continue to rely on an underlying assumption that animals will move away from extreme noise sources far enough to reliably keep them out of the Level A harassment zone, and that most Level B behavioral disruption is biologically insignificant. (This question will be clarified as we see how NMFS uses the new criteria when issuing bioloical opinions or Incidental Harassment Authorizations.)

The reliance on biological parameters (TTS, PTS) that are as yet still unknown for many species, and the proposed grid of varying thresholds based on differing hearing sensitivities, while a noble attempt to be more scientific, seems to create the possibility for both overly complex regulatory standards, and for countless legal challenges based on differing readings of the current science. (As noted above, some research can be read to suggest much lower thresholds of at least behavioral response; also, there are indications that the distinction between pulsed and steady noise sources, especially at great distances, is less clear than the standards seem to imply.)

Alternative 2 looks like an attempt to explore a very different approach: it sets acceptable noise standards based not on biological sensitivity (which is largely unknown for many species, and often nearly impossible to measure), but on current ocean noise levels (which is also not widely measured, but could be). It is also the only alternative that would address concerns about animal communication being acoustically masked by human noise. This approach holds much promise, as it proceeds from the assumption that animals are well-adapted to natural ambient noise levels, and that any significant change in the overall noise level introduced by human noise is likely to be detrimental. (Note: current human noise, primarily shipping and recreational boating, is included in the "current ambient noise" criteria to be used by this alternative; while there are likely areas where these human sources are having biological impacts, the purpose of the current criteria is largely to regulate louder, short-term human activities.) However, the standards suggested will need to be adapted in order to provide a viable model for effective regulation. First, since we cannot practically measure ambient noise in each area where permitted projects are proposed, it would be difficult to set reliable standards; it may make more sense to measure current ambient noise levels in a range of environments/habitats (e.g., harbor, continental shelf, reef, etc., perhaps with consideration of relative distance from shipping lanes) and to then use these dB standards as the ground for the approach suggested in Alternative 2. (This would surely involve some extrapolations that would not be precise, but such extrapolation is likely to be less problematic than the cross-species assumptions suggested in Alternatives 1 and 3-6). Second, the standards suggested may be unrealistically low; virtually any human activity involving motors or intense pulsed sound will trigger at least Level B harassment and probably also Level A as defined. For this to be a useful alternative, it must not be an overly extreme "straw man," easily discarded. Perhaps the use of 6dB or 12dB envelopes around the current ambient noise levels, and defining a distance at which these envelopes will be allowed and measured, would allow this approach to be more practical, as well as providing a level of protection to the acoustic integrity of ocean habitats that better reflects a sensitive and precautionary approach. (NOTE: Despite the enthusiasm for this Alternative implied by this narrative, it's important to note that there is little data to provide a scientific basis for either long-term biological (ie population-level) effects caused by acoustic masking, or what levels of noise above the background ambient cause short term behavioral changes. Thus, it's a difficult approach to hang regulations on; of course, the same could be said--and likely will be said--about whatever they come up with. This ambient noise Alternative still deserves to be given due consideration)

Comments Submitted to NMFS:

Acoustic Ecology Institute (special focus on ambient noise alternative) [DOWNLOAD COMMENTS(Word Doc)]
National Resources Defense Council [DOWNLOAD COMMENTS(pdf)]
Seaflow (much detail on bioacoustics, how animals use sound) [DOWNLOAD COMMENTS (pdf)] [PUBLIC MEETING COMMENTS(pdf)]
Center for Regulatory Responsibility (calls for criteria to be population level effects, and claims no evidence of this; also suggests use of Potential Biological Removal, an approach used successfully in fisheries) [DOWNLOAD COMMENTS(pdf)]
National Marine Manufacters Association (NMMA) - (Calls for status quo to be continued due to lack of clear science on acoustic effects Also detailed critiques of each alternative other than status quo) [DOWNLOAD COMMENTS(pdf)]
Animal Welfare Institute [DOWNLOAD COMMENTS(pdf)]

Submitting Comments
During the scoping phase, the most useful comments are ones that suggest specific, quantifiable alternatives or techniques that might inform the continued development of concrete regulatory mechanisms, which will be formally proposed as Alternatives in the Draft Environmental Impact Statement. This is not to discount the value of more general comments and input from the public, but just to clarify the sorts of comments that will be most useful to planners at this stage. General comments and statements of your feelings or ethical beliefs about ocean noise, while not directly "useful" to NOAA/NMFS planners, may help to influence the tone or scope of the range of alternatives presented in the DEIS.

The public comment period has ended, but NMFS will always accept comments.

Written comments on the scope of the EIS should be submitted to:
P. Michael Payne, Chief, Marine Mammal Conservation Division
Office of Protected Resources, NMFS (F/PR2)
1315 East-West Highway
Silver Spring, MD 20910.

Written comments may also be submitted by or by facsimile (fax) to (301) 427–2581.

Include in the subject line the following identifier: I.D. 060804F.

FOR FURTHER INFORMATION CONTACT: Brandon Southall, Office of Protected Resources, NMFS, 1315 East-West Highway, Silver Spring, MD 20910; Telephone (301) 713–2322. Additional information is available at (www.nmfs.noaa.gov/protlres/PR2/ AcousticslProgram). For information regarding the EIS process, contact Michael Payne at the above referenced contact information.