Whales, Dolphins, and Ocean Noise: ‘Absence of Evidence is not Evidence of Absence’

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Whales and dolphins are known to strand due to sonar and seismic exploration.
Whales and dolphins are known to strand due to sonar and seismic exploration.

Your input is needed to balance that of the oil industry and special interests on the issue of ocean noise – March 13, 2014 is the deadline to make comments on the government’s proposed guidelines on ocean acoustics and marine mammals.
Because this is a complex issue involving a lot of science and technical language, reading all of the documents can be off-putting and discouraging but it is worth the effort to skim through them.  However, if you are short on time the information below will give you a great start and can be checked back through the links provided.


Your input is vital! The oil industry would like a proposed 24 hour time period for measuring the sound levels their activities generate reduced significantly to as little as three hours – which means they would only have to measure a portion of the recommended time.
NOAA has repeatedly requested more input on this point (please scroll to the bottom to the section on the public meeting), and it is important to share your thoughts as counter-point to industry input such as this statement by a researcher contracted by the oil industry. (See full remark below).

This leads me to ask “what problem is NOAA trying to solve by this aggressive  approach?” Is there any evidence at all that the present guidelines leave whales with hearing loss from shipping, low-frequency active sonar, seismic arrays, and others? Have whale populations declined in areas where these sources are used? Unless there is evidence of either effect, then it is best to discard this graph and continue to use the present guidelines until empirical data become available on hearing in low-frequency cetaceans. (Gentry)

Fortunately, when dealing with wildlife the government has taken the stance that the benefit of doubt should go to the animals, particularly if there are threatened or endangered species involved (which sadly is true in all the oceans). You can use this point as an argument in your comment to the government.
Background on the Endangered Species Act:

5. Assess species responses to exposure.
Actions potentially resulting in habitat modification or destruction are indirect effects – as these effects may ultimately cause demographic effects on individuals or populations of a listed species. In this case the assessment must determine if a species habitat is likely to change in response to action-related changes in the quantity, quality, or availability of one or more of the resources that comprise its habitat.
To meet the statutory requirement to insure a proposed action is not likely to cause JAM, the agency conducts its analysis to avoid concluding that the action had no effect on listed species or its habitat when, in fact, there was an effect. This approach minimizes the likelihood of making a false negative conclusion (absence of evidence is not evidence of absence). In doing so, the agency must use the “best scientific and commercial data available,” and in cases where information is incomplete, clearly articulate the rationale for reaching a conclusion (thus avoiding being found to have made an arbitrary or capricious conclusion). At times, this approach to error may lead to different conclusions than would a more traditional scientific approach to hypothesis testing, but it is in compliance with direction from the ESA and the courts to provide the benefit of the doubt to the species.
6. Assess risk: to individuals, populations, and to species.
a. Would the response of the individuals exposed to the action be sufficient to reduce the fitness of those individuals?
b. Would changes in the fitness of these individuals be sufficient to increase the extinction risk (or reduce the probability of persistence and recovery) of the populations, given what is known about the species?
c. Would changes in the extinction risk (or persistence) of those populations be sufficient to increase the extinction risk of the species, given its status?

Below are excerpts from the relevant documents, but you can stop reading here and just use the information on endangered species above since it is applicable.

One additional point – walruses, polar bears, otters, and manatees are NOT included in NOAA’s document and so your comments on these species will not be included for consideration.  They will only consider arguments that address points covered in the document.

Please go here to enter your comment, the full draft can be found here. Reference comments from the documents are below, you might them helpful in writing your comments.


 NOAA’s remarks taken from the Peer Review Report:
(“Thresholds” refers to the sound levels that cause temporary hearing impairment (‘TTS  is Temporary Threshold Shift’) or permanent hearing loss (PTS is ‘Permanent Threshold Shift’)).

  • There will not be implementing regulations in association with this document.
  • These thresholds are to be used more before the activity occurs. So when applicants come and they have to estimate how many marine mammals are going to be harassed…this more of a tool to be used beforehand rather than out in the field.
  • So whatever process applicants are undergoing now in order to estimate the distribution or presence of marine mammals when they come in for authorizations under the MMPA would be the same using these thresholds. It is just that the science used in calculating these  thresholds is different.
  • So on a case-by-case basis, I would assume that applicants are doing the best  they can to estimate the distribution and presence of marine mammals, but there is no guidance additional within this document for that kind of estimation.

NOAA is continuing our examination of the effects of noise on marine mammal behavior and will focus our work over the next year on developing guidance regarding the effects of anthropogenic sound on marine mammal behavior. Behavioral response is a complex question, and additional time is needed to research and appropriately address the issue.
This guidance on behavior, when available, will also be subject to future peer review.

Input  was made by these four peer reviewers:

Klaus Lucke, Ph.D., Wageningen University and Research (The Netherlands)  “Results of masking modelling indicate that airgun sounds can lead to a reduction in communication range for blue and fin whales 2000 km from the source depending strongly on the frequency content of the vocalization.” Conference abstract, page 180
Paul Nachtigall, Ph.D., University of Hawaii Loud anthropogenic sounds have been associated with whale strandings. Loud impulsive sounds may contribute to behavioral disruption and hearing deficits.” Conference abstract, page 113  {This preliminary study showed that some cetaceans may be able to mute the effects of noise when given a warning noise.}
Doug Nowacek, Ph.D., Duke University “The critical elements of a robust mitigation and monitoring plan for responsibly conducting marine seismic surveys include obtaining baseline ecological data; substantial advance planning, communication, and critical review; integrated acoustic and visual monitoring during operations; and systematic analysis of results to inform future planning and mitigation.” Abstract
Aaron Thode, Ph.D., Scripps Institution of Oceanography  “Call localization rates (CLRs) were compared before, during, and after periods of airgun use between sites near seismic activities (median distance 41-45km) and sites relatively distant from seismic activities (median distance >104km). At the onset of airgun use, CLRs dropped significantly at sites near the airguns, where median received levels from airgun pulses (SPL) were 116-129 dB re 1 Pa (10-450 Hz). Abstract   {This study was done on bowhead whales.}

The bulleted points below were taken from the Peer Review document – they are not in order since the remarks were not identified by reviewer (but are by one of the individuals above, or by a NOAA representative, so are somewhat anonymous).
These remarks were selected to represent the issue that seems to be most important for the public to comment upon, the 24 hour recovery period. (cSEL is ‘cumulative Sound Exposure Level’). NOAA repeatedly requested that this issue be addressed during the comment period.

  • I feel the report has so many caveats on this subject as to render this definition worthless:
    “The 24-h baseline accumulation period is generally considered a conservative baseline for accumulation time under most situations. However, flexibility may be required. For example, if specific information on residence time of individuals, likely swim speeds for transient species, more specific details on the sound-producing activity (e.g., specific times when activity temporarily ceases),”
  • Just about every oil and gas industry survey is going to try to reduce this period of time to the time it takes for a migrating animal to swim past a spatially compact activity.
  • I think a sentence should be added that if the primary behavior of marine mammals in the area is migration, the cSEL duration can be restricted to three hours. Areas that cover feeding and mating should remain at 24 hours. This is much simpler than requiring an applicant to estimate swimming speed, swimming depth, whether animals is assumed to deviate or avoid course, etc. Restricting duration to 3 hours also makes the behavioral and TTS criteria more consistent.
  • → Response: NOAA appreciates your input on this particular topic and anticipate there will be additional comments provided during the public comment period. The proposed 24-h accumulation period may not be appropriate for certain sound sources or species. We are planning to call particular attention to this topic during the public comment period.
  • Additionally, your comments seem to focus strictly on seismic activities. However, the proposed accumulation period is for all PTS onset acoustic threshold levels for various sources (e.g., sonar, pile driving, drilling, etc.). Thus, there are multiple considerations needed based on whether a source is stationary or mobile and based on the species and specific context of exposure.
  • Proposed solution: Provide specific guidelines whether cSEL covers only proposed activities or whether it covers all independent activities (including shipping) during that time. State whether NOAA will reduce the cSEL threshold if multiple permits working in the same area are received.
  • Another issue with defining cSEL duration to be 24 hours is what to do when multiple uncoordinated activities are present. For example, multiple seismic surveys? Shipping vessel transits? NOAA should also state intentions what it plans to do if multiple organizations submit requests to operate in the same region, with each showing individual cSELs below TTS, but cumulative cSEL from all operations exceed TTS.
  • Response: Currently, the PTS onset acoustic threshold levels are being proposed for discrete activities and not multiple activities occurring in a single area. This will be clarified in the text (footnote #15).


Input from those attending the public meeting:
JESSICA LEFEVRE [Jessica S. Lefevre is an attorney in private practice specializing in natural resource issues, including the mitigation of local impacts resulting from resource development. She has served ascounsel to the Alaska Eskimo Whaling Commission since 1985]:

I think we might encourage you to do that, if it is possible, and we also will  put in a request for an extension. This is pretty important and a lot of information to get on top of. Those are procedural questions. My substantive question is: Could you talk a little bit how the cumulative SEL can be used to account for multiple, repeated exposures, where you’ve got an animal going past one site and then moving along encountering a second site? It just we have not had a lot of time to spend with this and that is one of the questions we’re trying to wrap our heads around. Thanks.
[MODERATOR]: I think terms of the nature of that comment, what I would suggest is that you provide information that you think it is not clear how we are proceeding in accumulating sound from multiple exposures, and we will make sure we clarify that in the final document. Thank you.

SCOTT SLAUGHTER: I am Scott Slaughter, and I am commenting today on behalf of The Center for Regulatory Effectiveness  [“CRE was formed by former career officials of the White House Office of Management and Budget. The head of the firm is Jim Tozzi.It has been criticised as a front organisation for industries which seek to undermine the regulatory process, notably by Chris C. Mooney in his book The Republican War on Science.[1]  Wikipedia].

…Given this absence of harm in the real world, the government should carefully consider the benefits and costs of regulating oil and gas  seismic. In particular, the government should consider the requirements of Executive Orders 12866 and 13563 when regulating oil and gas seismic. Under Executive Order 12866, the Guidance should go to OMB to review standards that require a benefit-cost analysis be performed. Suggest that the government solicit public input performing cost-benefit analysis. We thank you for the opportunity to present these comments, and we look forward to the government’s response.

ROGER GENTRY: I’m Roger Gentry..G-E-N-T-R-Y. I’m with ProScience Consulting and the Joint Industry Program. [“The JIP is a cooperative effort, established in 1991, by a number of petroleum and chemical companies to consolidate independent construction cost surveys soliciting similar information from contractors”.]

I’m going to read my statement.
My written comments covers three pages, but I’ll just here discuss the guidelines for low-frequency cetaceans. The frequency weighting function shown in Figure 2 [page 16 of NOAA’s draft acoustic Guidance ] are basically invented because there are no empirical data to support them.
It is probably invalid to use mid-frequency cetacean equal loudness contours to set points “a” and “b” on that graph. The overall effect of this weighting function is much more  aggressive than the approach presently in place, especially in the Arctic guidelines. It implies that low-frequency cetaceans are much more sensitive to acoustic exposure than is formally believed, and it does so with supporting data.
This leads me to ask “what problem is NOAA trying to solve by this aggressive  approach?” Is there any evidence at all that the present guidelines leave whales with hearing loss from shipping, low-frequency active sonar, seismic arrays, and others? Have whale populations declined in areas where these sources are used? Unless there is evidence of either effect, then it is best to discard this graph and continue to use the present guidelines until empirical data become available on hearing in low-frequency cetaceans.
Several funding groups are interested in obtaining these data, and current development suggests they will be available in five to six years when the next version of these guidelines should appear. NOAA wisely declined to set guidelines for behavioral effects due to poor data and should make an equally wise decision to not to set guidelines for low-frequency cetaceans in total absence of data. Thank you.

DAVID ZEDDIES: Hi. David Zeddies. Last name Z-E-D-D-I-E-S. I’m at JASCO Applied Sciences. [JASCO Research is an international company with over 25 years experience providing consulting services to the Marine Industrial, Oceanographic, Oil & Gas, Fisheries, Defense and IT sectors.] 

I want to make a quick technical comment on the 24-hour integration period, and it starts with..we have a pretty good idea why you want to do that. There are natural breaks in the operations or you want to give some sort of method for allowing recovery to occur, but 24 hours is an arbitrary number that is really not based in any type of biology that I am aware of. There is some scant studies on that, but basically thereare better ways of doing it. Agent-based models we have will give you a natural indication of how long the animals..you expect the animals to be in that area. So instead of setting a guideline that strictly writes down the number ..in a 24-hour period, you could ask people to estimate the time the animals would be in that area, and there are also better ways of allowing for recovery periods. That would be as part of the cumulative SEL measurement. You could integrate..you could use a function that would allow for some recovery period.

ROBERT SUYDAM  [Senior Wildlife Biologist, Department of Wildlife Management, North Slope Borough] :

Thank you. My name is Robert Suydam. My last name is spelled S-U-Y-D-A- M. First, I would like to kinda re-emphasize what Dr. Ketten and Dr. Gentry mentioned about a section on needed research I think would be helpful in the document and then a couple of other points. One that Jessica LeFevre mentioned, the cumulative impacts issue of multiple operations that I know that frequently in the past NOAA has not ..dealt with each operation separately and not really addressed cumulative impacts from multiple operations on individual animals. So adopting new guidance criteria, I think needs to figure out how to address that issue of multiple operations that are occurring in one location. So, I think additional guidance is needed there. I would also like to comment on the guy from JASCO, sorry I didn’t catch his name that the 24 hour integration period for cumulative SEL seems a bit arbitrary and some additional support is needed for..in the document for why the 24 hour integration period is the appropriate one and not either a greater period or shorter period. So that would be helpful.
Another issue that really wasn’t addressed in the Guidance is the issue of impulsive sound versus non- impulsive sound. Of course with seismic sound, they are impulsive when they are close, when an animal is close to the seismic source, but they become more non-impulsive the farther you are away from an airgun. Of course, the loudness of the sounds changes, as well, but maybe trying to figure out if having  this dichotomy of impulsive vs. non-impulsive is really the best way to go or whether there needs to be some other category in between there? And then, I guess a question that I had: I understand that the  Guidance is really about assessing what the effects are on the marine mammals prior to the operations that I am at a loss to figure out at least how cumulative SEL is going to be actually monitored for what animals are actually taken. So I think the Guidance, the new Guidance would really benefit by having a section on how monitoring would occur to actually figure out if the projections of exposures to marine mammals are realistic.
[MODERATOR]: Thank you very much. I would just like to reiterate that any input that anyone may have on the accumulation duration, we would much appreciate that. Thank you.


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