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OCR for page 73
~ Findings and Recommendations Or
The Committee discussed a wide range of topics related to its charge. This
chapter presents the results of the Committee's review of the Marine Mammal
Research Program (MMRP), identification of important future research and obser-
vations, specification of desirable regulatory reforms, and ideas for comprehen-
sive monitoring and regulation of sound in the ocean.
RESULTS OF THE MMRP
Findings: Tests of the Acoustic Thermometry of Ocean Climate (ATOC) source
were authorized under permits for the MMRP experiment. Although the MMRP
was allowed some control over the specific days that the California transmissions
took place, MMRP was retrofitted to an operational use of the ATOC source and
was not designed to investigate the effects of the source most effectively. This
situation illustrates problems that can be encountered in studies designed to
monitor animals in the area where a noise source has been placed and is operated
for other reasons, rather than optimizing transmissions to accomplish a specific
research objective. As a consequence, the results of the MMRP do not conclu-
sively demonstrate that the ATOC signal either has an effect or has no effect on
marine mammals in the short- or long-term. In view of the lack of data for marine
mammals exposed to the ATOC signal at received levels above 137 dB, and the
incomplete analyses of much of the data collected off the Kauai source, the
Committee could reach no conclusions about the effects of the ATOC source at
the level of 195 dB. Data from tests of oil industry noises (Malme et al., 1983)
and the low-frequency active (LFA) sonar tests (Tyack and Clark, 1998) indicate
that these kinds of signals can alter the normal behavior of migrating gray whales,
73
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74
MARINE MAMMALS AND LOW-FREQUENCY SOUND
and data from MMRP are suggestive of a behavioral change in humpback whales
and sperm whales exposed to 130 dB or greater from the ATOC signal. Thus,
there is a potential for altering the normal behavior of marine mammals capable
of hearing low-frequency sounds, such as those produced by the ATOC source,
LEA sonar, and commercial shipping. The biological significance of short- and
long-term exposure cannot be extrapolated from the limited data acquired during
the short-term MMRP studies. Redistribution of marine mammals from tradi-
tional feeding or breeding areas was not observed, but cannot be ruled out.
Recommendations: If ATOC does continue, a marine mammal monitoring and
research component should be required, but the marine mammal research program
should have the flexibility to design and perform playback experiments opti-
mized to yield information about biologically significant effects of the source on
marine mammals. In general, any long-term experiment involving high source
level ensonification of large areas of the ocean should take precautions to mini-
mize exposure of marine mammals to dangerous levels of sound. Such precau-
tions could include one or more of the following:
· Design the physical structure of the source to minimize the potential
exposure of marine organisms, if this is technically feasible. For example, a
physical barrier could be erected around the source, like a radome on a radar
facility.
· Install sensors to shut down the source automatically when marine mam-
mals are too close.
· Make the source level and duty cycle as low as possible, given the objec-
tives of the research.
· Install the source away from large concentrations of marine mammals.
· Design the ramp-up period to make it possible for marine mammals to
avoid received levels that would cause temporary threshold shift (TTS).
If the Kauai ATOC transmissions are continued, it will be important to
continue ship- and air-based measurements of marine mammals within the 130-
dB zone around the source. The Committee was told that ATOC investigators
plan to continue aerial observations. Observations of marine mammals near the
Kauai source should include humpback whales as well as other species. Vessel-
based observations and aerial surveys are complementary and both methods
should be used. The inability of shore-based observers on Kauai to observe
humpback whales near enough to the ATOC source to be exposed to sound levels
that would be likely to produce biologically significant behavioral responses
indicates that shore-based observations should not be continued for studying the
effects of the Kauai source. Shore-based methods are useful, however, when
animals exposed to the sound levels of interest can be viewed easily from shore
(e.g., Malme et al., 1983, 1984; Frankel and Clark, 1998a).
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FINDINGS AND RECOMMENDATIONS
75
Long-term observations should be conducted near the Kauai source. Priority
should be given to specific studies targeted to resolve areas of critical uncer-
tainty. Since the source may be deployed for at least 5 more years to meet the
ATOC objectives, long-term studies of animals near the source are a priority. If
the source is to be operated for decades as part of an operational ocean-observing
system, it is important to determine whether there are some animals that are
resident in the area, because in such a case small effects might accumulate over
time to have a larger impact. A study should be designed specifically to deter-
mine whether there are resident animals in the source area and to study whether
the ATOC source changes the pattern of residency for identified individual
animals on day-to-day and interannual timescales. Such observations would be
more sensitive indicators of habitat usage for resident populations than the more
general comparisons of the distributions of sightings of each species conducted
by the MMRP.
A vessel-based study to photo-identify marine mammals sighted near the
source could be used to test whether there are any resident individuals or popula-
tions. If carried out over the years ATOC hopes to operate, such an observation
program could provide more information on the status of the population (as did
similar data for baleen whales off California; Calambokidis, 1996, 1999~. The
vessel conducting this photo-identification work could also combine visual and
acoustic monitoring of marine mammals and monitor for any unexpected effects
of ATOC transmissions with a statistically designed sampling program. In addi-
tion, ATOC has a responsibility to design a well-controlled study on the effects of
ATOC transmissions on humpback whales within the 130-dB zone around the
source. This would probably need to be vessel-based in order to follow animals
near the source. It could use the same vessel involved with the photo-identifica-
tion work.
2. Conduct aerial surveys around the ATOC source. If aerial surveys are
conducted early enough in the season to document the migration of humpback
whales into the area, there will be some evidence as to whether individual ani-
mals enter the area around the receiver and later are repelled by the source.
Individual animals are impossible to track for long from an airplane, but a broader
coverage can usually be accomplished using aircraft rather than shore- or ship-
based methods. Aerial surveys also allow documentation of the distributions of
sperm whales and other species that are more difficult to observe from vessels to
determine whether there is cause for concern about long-term exposure of these
species.
3. Use radio-tagging and tracking, and recoverable data recorders. The use
of such tags to study the effect of the California source on elephant seals provided
a wealth of data on diving behavior and received levels of sound. Although tags
and data recorders are harder to place on whales than on elephant seals and harder
to retrieve later, they could be useful in providing the same kind of information
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MARINE MAMMALS AND LOW-FREQUENCY SOUND
on received level and diving behavior, with a potential for recording whale
vocalizations.
4. Conduct studies on the effects of ramped-up signals. Ramped-up signals
are used worldwide in high-energy seismic surveys as a common-sense measure,
but their effectiveness has not been tested scientifically. Funding should be
designated from the ATOC program or other sources for competitive grants to
study the responses of seals and whales to a ramp-up of a noxious sound. Since
baleen whales and sperm whales cannot be tested in controlled studies in captivity
with the ATOC signal, and since most other species probably cannot hear it, a
higher-frequency ATOC-like sound could be used. For example, responses of
captive dolphins or white whales could be used to document the kinds of responses
or lack thereof to a ramped-up signal. Do they ignore it or do they approach to
investigate the new sound? How many exposures does it take (if ever) for them
to leave the area as the ramp-up begins? Do they habituate to the ramped-up
signal? At what level should the ramp-up start, in order to avoid startling the
animals but still be heard above background noise (e.g., should the ramp-up
phase start with a lower source level than 165 dB)? This would not be a perfect
experiment because it could be argued that baleen whales might not respond the
same way as small toothed whales, nor wild animals like captives, but such an
experiment should provide insight into the potential behavior of other marine
mammals. The Minerals Management Service (MMS) is funding a study in the
Gulf of Mexico region of signal ramp-up that is designed to repel small toothed
whales and seals before seismic surveys using airguns are started. Data from this
study should be reviewed by ATOC investigators.
FUTURE RESEARCH AND OBSERVATIONS
The Committee reiterates the research recommendations made in NRC (1994,
1996~. Although progress has been made on many of these topics (e.g., TTS), all
remain valid and were discussed in detail in Chapter 3. In addition to these
research topics, research priorities are identified below and suggestions made for
the appropriate institutional structure for selecting, funding, and overseeing re-
search. The federal agencies and Congress should determine whether these ac-
tivities are of high enough priority to merit reprogramming of existing funds or
appropriating new funds. The speed with which these research and observation
activities are implemented will depend on the urgency felt by the public, Con-
gress, and federal agencies for gaining the knowledge necessary to address the
goals of both protecting marine mammals and carrying out desirable human
activities that add sound to the ocean.
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FINDINGS AND RECOMMENDATIONS
77
Priority Studies
Findings: The typical pattern for funding research on the effects of noise on
marine mammals is for a group responsible for producing noise to be required to
provide data on the effects of its operations. This leads the group to fund projects
closely tied to the specific signals, areas, times of planned operations, and species
of special concern to that project. For example, the primary approach of the
MMRP has been to study one anticipated sound stimulus at three anticipated
source sites. A problem with this approach is that results cannot be extrapolated
readily to other stimuli or sometimes to other sites. There are hundreds of
sources of potential concern, and it may be more efficient to develop a more
comprehensive research program using a set of representative stimuli to more
easily allow any users to model the predicted response to their own stimulus.
Sound is multidimensional and cannot be characterized fully by a single
measure, for example, peak intensity or frequency. Thus, in considering (1) the
auditory capability of a species, (2) its response to a particular sound, and (3) regu-
latory guidelines for exposure of animals to sound, the full dimensionality of
sound should be taken into consideration. In this regard, factors that must be
considered include the temporal and spectral characteristics of the sound, includ-
ing the intensity, duration, duty cycle, frequency, bandwidth, rise time, temporal
structure and similarity of any of these dimensions to biologically relevant sounds,
as well as sensitivity of the relevant species to sounds with those characteristics.
Decisions based on such parameters should be made more objective by
combining parameter values in mathematical decision models. Such risk assess-
ment models have yet to be developed and tested for marine mammals and sound
because of a lack of basic information about how sound characteristics are related
to species-specific hearing sensitivity. An additional complication of modeling
the effects of sound on marine mammals arises in predicting the received levels at
the animals, particularly in shallow water, because of reflection off the sea sur-
face and seafloor and unexpected areas of anomalous temperatures, salinities,
and densities. Such factors can cause differences between predicted and actual
received levels as great as 30 dB (J. Lynch, Woods Hole Oceanographic Institution,
personal communication, 1999~. This potential problem with acoustic propaga-
tion models creates a responsibility for major noise generators to calibrate their
model-predicted sound levels against measured levels.
Recommendations: With regard to future research to study the effects of human-
generated sound on marine mammals, the Committee supports the recommenda-
tion of NRC (1994) that there is a need for planned experiments designed to relate
the behavior of specific animals to the received level of sound to which they are
being exposed. Very few studies have succeeded in this aim. Because studies of
ocean acoustics and marine mammal behavior are very challenging, successful
experiments will require a closer collaboration between biologists and acousti-
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MARINE MAMMALS AND LOW-FREQUENCY SOUND
clans than has been the case in the past for many field studies. Success will also
require continued refinement of techniques for making acoustic and visual obser-
vations, such as methods for locating vocalizing marine mammals and develop-
ment of tags that can monitor received levels at the tagged animal.
To move beyond requiring extensive study of each sound source and each
area in which it may be operated, a coordinated plan should be developed to
explore how sound characteristics affect the responses of a representative set of
marine mammal species in several biological contexts (e.g., feeding, migrating,
and breeding). Research should be focused on studies of representative species
using standard signal types, measuring a standard set of biological parameters,
based on hearing type (Ketten, 1994), taxonomic group, and behavioral ecology
(at least one species per group; Box 5.1~. This could allow the development of
mathematical models that predict the levels and types of noise that pose a risk of
injury to marine mammals. Such models could be used to predict in multi-
dimensional space where TTS is likely (a "TTS potential region") as a threshold
of potential risk and to determine measures of behavioral disruption for different
species groups. Observations should include both trained and wild animals. The
results of such research could provide the necessary background for future envi-
ronmental impact statements, regulations, and permitting processes.
The uncertainty in predictions of received sound levels hinders the applica-
tion of models of marine mammal responses to sound and will require three
complementary approaches: (1) development of better acoustic propagation
models; (2) development of better observing systems to gather the data needed in
models; and when the first two are not feasible, (3) development of better systems
to observe ambient sound and transient noise pollution events in the ocean. Any
research that includes relatively loud sound sources should monitor sound levels
around the source site to gather data to calibrate its acoustic propagation models.
The locations of ATOC sites were dictated by requirements for the ATOC
sound to reach many preplaced receivers and thus were not ideal for observing
marine mammals. Pioneer Seamount is 88 km offshore, and observations on the
north shore of Kauai were complicated by frequent high winds, waves, and bad
weather. In general, studies designed to observe the effects of sound on marine
mammals should be conducted in areas of high animal density for easy and less
costly observation. Potential investigators should not transmit the noise until
preexposure control data on individual subjects are obtained, and great care should
be taken to ensure that ensonified marine mammals are not significantly damaged
physiologically.
Acoustic studies focused on topics other than marine mammals should try to
keep sound sources away from marine mammal "hotshots," even if this compli-
cates logistics, increases costs, and/or decreases the efficiency of the experi-
ments. In the case of the MMRP, acoustic and marine mammal studies with
different goals were linked, leading to the proposal to place the sources in areas
with high concentrations of marine mammals. Continuation of the oceanographic
OCR for page 79
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MARINE MAMMALS AND LOW-FREQUENCY SOUND
component of ATOC would involve less risk to marine mammals if the source
were moved, but this could be prohibitively expensive and would alter the data
series. Even if scientists use sound responsibly, however, this does not guarantee
the protection of essential marine mammal habitat, because commercial users are
not subject to the same permitting requirements.
Studies of wild marine mammals should include careful determination of
their locations, coupled with improved sampling and modeling of acoustic propa-
gation to estimate received sound levels accurately. Alternatively, acoustic data
loggers could be mounted on individual animals to record (1) the sounds (and
their levels) to which the animals are exposed; (2) their vertical and horizontal
movements; and (3) the sounds produced by the animals, including physiological
sounds such as breathing and heartbeats. Preliminary analysis of MMRP data
from tagged elephant seals demonstrated the usefulness of this approach in assess-
ing behavioral response to ATOC sounds at Pioneer Seamount (Costa et al.,
1999) and showed potential for use in other comparable studies. Acoustic data
loggers will be particularly important for research on deep-diving mammals,
whose behavior and exposure cannot be monitored systematically at depth in any
other way.
A central theme of this report is that the task of developing predictive models
of acoustic conditions that would harm marine mammals could be simplified by
partitioning research among a small number of species that are representative in
their hearing capabilities and sensitivities of larger groups of marine mammals.
Box 5.1 describes the priority species groups, signal characteristics, and biological
response parameters that should be investigated.
Richardson et al. (1995) summarized studies of marine mammal responses to
human-generated sounds, particularly those associated with oil exploration and
shipping. Some of these studies reported a significant difference between levels
of pulsed versus more continuous sounds required to evoke a response in whales.
To evoke the same level of response in migrating gray whales, a pulsed air gun
sound required levels 50 dB higher than a diverse array of low-frequency con-
tinuous sources. This result is unexpected based on human hearing capabilities.
How do marine mammals respond to signals with durations between the pulsed
air gun noise (pulses separated by 7 to 15 seconds) and more continuous sounds?
Another important question is: How do marine mammals respond when the
received level is the same from two sources at different distances? This would
help to discriminate whether marine mammals generally respond to received
level (as was the case in the Phase II LEA study), estimated range to source, the
gradient of acoustic energy over distance, and/or other sound characteristics.
Response to Stranded Marine Mammals
Findings: Observed behavioral responses of baleen whales to human-generated
sound have all been reactions to sounds that are near or above the noise back-
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FINDINGS AND RECOMMENDATIONS
81
ground (Richardson et al., 1995~. Behavioral response thresholds in the range of
100 to 110 dB (Dahlheim and Ljungblad, 1990; Frankel et al., 1995) are consid-
erably greater than human underwater threshold hearing levels. As has been
suggested by Frankel et al. (1995) and Richardson et al. (1995), field observations
of acoustic response thresholds probably have been limited by background noise
rather than being indicative of true hearing thresholds.
The NRC (1994, p. 57) recommended the organization of a Stranded Whale
Auditory Test (SWAT) team to obtain audiometric data from stranded or ensnared
whales using recently developed electrophysiological techniques and instrumen-
tation (e.g., Dolphin, 1997) for evoked potential studies (Hall, 1992~. Some
thresholds for killer whales and dolphins have been obtained using evoked poten-
tial methods (Popov and Supin, 1998; Popov and Klishin, 1998; Popov et al.,
1998; Szymanski et al., 1995, 1998), but further research on methods of evoked
potential audiometry are required for the application of the SWAT team approach
to large whales.
Evoked potential audiograms, even on a few animals (e.g., using the SWAT
team approach), would resolve the issue of whether baleen whale thresholds are
below the observed behavioral response. Levels producing TTS often are stated
as decibels above absolute sensitivity, so knowing the audiogram would be
important for regulatory decisions and policy making if noise levels are being
controlled based on TTS. Determining the hearing capabilities of the marine
mammals in the categories listed in Box 5.1 is an exceptionally high priority for
future research, and plans for such studies should be developed and implemented
as soon as possible. The ultimate goal of such studies should be to provide
information on hearing sensitivity, TTS, nonauditory effects, and other biological
parameters listed in Box 5.1 to help in the determination of sound levels that
might affect marine mammal hearing or significantly alter their behavior.
Physiological methods such as the auditory brainstem response (ABR) pro-
vide baseline data for use in evaluating promising behavioral techniques such as
playbacks like those employed by Dahlheim and Ljungblad (1990) and others
and thus are an important complement to behavioral techniques. So far these
playback methods have produced thresholds that are on the order of 50 dB less
sensitive than thresholds at the most sensitive frequencies obtained in the labora-
tory setting using ABR techniques with smaller species.
Recommendations: The concept of SWAT teams recommended in NRC (1994)
and NRDC (1999) should be implemented by funding trained scientists and asso-
ciating them with stranding networks. The Office of Naval Research (ONR)
partially funded a small effort to support the activities of a SWAT team, but the
hardware and field methods are not yet adequate for wide testing. The ONR
program manager (R. Gisiner) estimates that a considerable, but not unreason-
able, amount of hardware and software design and testing will be needed (about
1 to 2 years of effort) before a system capable of regular operation under the
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MARINE MAMMALS AND LOW-FREQUENCY SOUND
SWAT team approach is feasible. However, this activity should be expanded to
at least two teams, one on the east coast and one on the west coast of the United
States. The teams should be responsible for (1) necropsy of suspected/possible
marine mammal victims of sound injury (to be able to show whether sound
caused the injuries or deaths) and (2) testing of hearing on stranded or entangled
live animals. There is a need to expand the pool of individuals capable of doing
this kind of work and capable of relating ear anatomy to function. An immediate
need is for funding a specialist in evoked potential audiometry to develop
improved methods applicable to large whales. A postdoctoral fellowship might
be the most economical way to achieve this goal. NMFS and/or ONR should
include funding for such work in the next budget cycle. Alternative possibilities
for studying hearing in animals that are not kept in captivity also should be
explored, such as placing a tag with electrodes on the head of a free-swimming
whale and playing sound to the animal in a quiet environment.
Multiagency Research Support
Findings: Most marine mammal studies are funded from mission-oriented
sources. At this time the greatest source of funding for marine mammal research
is ONR. However, by its nature, ONR-funded research tends to be focused on
questions of practical importance to the Navy and is not necessarily responsive to
the broad interests of scientists seeking to learn more about the basic biology of
marine mammals. Scientist-driven fundamental research could significantly
improve our understanding of hearing and the effects of low-frequency sound on
marine mammals, as well as our overall understanding of the acoustic behavior of
these animals.
Recommendations: If government funding shortages and priorities continue to
constrain budgets for marine mammal research in the foreseeable future, manage-
ment of sound in the ocean should remain conservative (and should incorporate
management of all sources of human-generated noise in the sea, including indus-
trial sources), in the absence of required knowledge. If government regulators
need better information on which to base decisions, they should take such steps as
necessary to provide increased funding for marine mammal research and to
improve the ways that needed research is identified, funded, and conducted.
Acquiring better information is often complicated because the regulatory parts of
agencies like NMFS and FWS are separated from research, and funded research
may not necessarily match research needed by regulators. It is imperative that the
research and regulatory arms of NMFS and FWS maintain good linkages within
these two agencies, and that priority is given to research needed by regulators in
each agency. Government agencies with basic science missions (e.g., National
Science Foundation [NSF] and National Institutes of Health [NIH]) should fund
marine mammal research at the levels needed to answer fundamental questions
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FINDINGS AND RECOMMENDATIONS
83
about hearing anatomy and physiology. Mission agencies with responsibilities
related to marine mammals (e.g., ONR, National Oceanic and Atmospheric
Administration [NOAA], MMS, U.S. Geological Survey [USGS]) should also
fund basic research (notwithstanding ONR's limitations under the Mansfield
Amendment), in the spirit of the recommendation of NRC (1992) that "federal
agencies with marine-related missions find mechanisms to guarantee the continu-
ing vitality of the underlying basic science on which they depend" (p. 28~. Such
research should receive the same level of peer review as other basic research and
be competitive with such programs for funding. Because marine mammal
research is quite expensive, multiagency funding may be necessary to spread the
costs. Alternatively, multiple parts of the same agency may need to cooperate in
order to provide sufficient funds.
Multidisciplinary Research Teams and Peer Review
Findings: The MMRP suffered from the lack of an interdisciplinary group for
planning its research. Further, the MMRP was added to an existing research
program, rather than being designed to fulfill its own objectives. The agenda for
the acoustic oceanographic component of ATOC required different transmission
schedules from those that would have been optimal for marine mammal research.
For example, the geographic location, depth, and duty cycle (in part) of the
source were determined by the needs of ATOC, not the needs of the MMRP. As
a consequence, the biological data that resulted were not optimal for answering
the fundamental biological questions raised by the ATOC transmissions.
Recommendation: Consideration should be given to establishing a multi-
investigator program to study the effects of sound on marine mammals, funded
by consortia of government agencies, non-governmental organizations, shipping,
and hydrocarbon exploration and production industries. These consortia should
include individuals, organizations, and companies in nations that share marine
mammal stocks and sound-producing activities with the United States (e.g.,
Canada, Mexico, nations of the North Atlantic Treaty Organization). Such
consortia could be initiated through a workshop to bring together the interested
communities. The design and implementation of auditory research on marine
mammals ideally should be an interdisciplinary enterprise. Valuable contribu-
tions can be made by physical acousticians on the choice of sound stimuli to be
used, by electronics experts on the choice and calibration of transducers for
presenting the stimuli, by marine biologists on the choice of species and/or the
best season and location for testing, by psychoacousticians on the testing proce-
dures, and by statisticians on initial design and eventual data analysis and presen-
tation. Without collaboration among specialists within these various disciplines,
there is a greater probability that expensive and time-consuming projects will
contain errors that preclude an unambiguous interpretation of the results. These
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projects are sufficiently complex that one or two individuals cannot reasonably
be expected to have the full range of knowledge necessary for success. The
logistical difficulties, permitting issues, and expense of such research demand
advanced planning in all these areas.
If such a research program is established, it should use a public Request for
Proposal (RFP) process that results in proposals from more than one research
team and is modeled after the peer-review processes used by NSF and NIH.
Conversely, some research should continue to be funded through the less conser-
vative ONR model, which provides program managers with greater latitude to
fund more innovative science. A spectrum of funding styles is useful. The REP
should be well advertised to encourage ideas and proposals from a wide range of
researchers and institutions (including foreign participants), rather than relying
on a set of traditional investigators. The goal of the process should be to optimize
the selection of hypotheses, methods, and design and to identify the best
performers) (e.g., best track record in previous work) for the proposed work. It
is to the advantage of the sponsors to implement programs of broad-based peer
review for such proposals. Future research on marine mammals unquestionably
would profit from a broad-based review of the plans developed by multi-
disciplinary teams and evaluated by a peer-review process that is objective and
independent. Such a review should determine whether the proposing investiga-
tive teams did the following adequately:
· identified basic problems);
· established specific hypotheses to be tested, with appropriate methods for
data reduction, data presentation, and statistical analysis;
· identified optimal experimental methods and test conditions (including
geographic location of study); and
· evaluated the power of the proposed experimental design.
Because long research projects often need to adjust to experience gained in
field programs and learning about what kinds of observations are practical and
achievable, it is important to provide advice from an outside review team later in
the life of a project.
Sponsors of research need to be aware that studies funded and led by one
special interest are vulnerable to concerns about conflict of interest. For example,
research on the effects of smoking funded by NIH is likely to be perceived to be
more objective than research conducted by the tobacco industry. Concern for
peer review, efficiency, and independence argues for having an agency such as
NSF take the lead in managing an interagency research program on the effects of
. .
noise on manne mamma s.
Agencies that fund such applied research should ensure that adequate fund-
ing for analysis and plans for peer review are in place before a research award is
made. Analysis might be speeded by employing a larger team for analysis and
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FINDINGS AND RECOMMENDATIONS
85
involving this team in planning the observations to make them as easy as possible
to analyze later. Although publication in peer-reviewed journals is the standard
by which most research is judged, applied research output from projects like the
MMRP is not necessarily suitable for publication in available academic journals
and the results may need to be used for regulatory decisions within a shorter
amount of time than the normal journal paper cycle. Timely peer review of such
studies might be better accomplished by conducting a mail and/or panel review of
results by an independent group established specifically for this purpose.
Population-Level Audiograms
Findings: Ridgway and Carder (1997) published the first evidence that auditory
capabilities in bottlenose dolphins may vary with sex and may change with age,
similar to observations in humans (Ward, 1997~. These data reinforce the recom-
mendation of NRC (1994) that audiograms should be obtained for many indi-
viduals in a population to determine the normal range of hearing capability and
the effects of aging. Because of the difficulty and expense of training and main-
taining large numbers of animals, most studies collect data from one or two
individuals of a particular species. Although individual differences have been
noted (e.g., Terhune and Turnbull, 1995; Schlundt et al., 2000), no single study
has used the same methods for multiple individuals of both sexes and varied ages.
In addition, Ridgway and Carder (1997) reported that a young dolphin apparently
had been deafened due to disease and had survived in the wild although deaf and
mute. Clearly, there is a range of normal hearing among individuals, and even
deficits may not prove fatal for individuals of social species. The major barrier to
large-scale testing of the hearing of many individuals of the same species has
been the need to train each individual to respond to sounds in measurable ways.
The further development of audiometric procedures based on auditory evoked
potentials (Hall, 1992; Szymanski et al., 1999) would eliminate that problem.
Recommendations: Federal agencies should sponsor studies on the hearing
abilities of both free-swimming and stranded animals. Population-level audio-
grams of many individuals (such as are performed for humans; see Yost and
Killion, 1997) are necessary for establishing the baseline of hearing capabilities
and normal hearing loss in marine mammals, as also recommended in NRC
(1994~. Stranded animals should be assessed to determine if their hearing is
"normal." Data are needed to provide comparisons that would allow an evalua-
tion of how common hearing deficits may be among stranded animals. The
development of population-level audiograms will require the perfection and wide
use of auditory evoked potential techniques, to eliminate the need to train all
tested animals. However, if the cost and techniques limit widespread auditory
evoked potential measurements of captive animals, a good sample of multiple
animals (different ages and both genders) of the same species should be tested.
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National Captive Marine Mammal Research Facility
Findings: There are few sources of trained marine mammals and few facilities
available to academic (or even government) scientists for closely controlled
research on the hearing capabilities of captive marine mammals and on sick or
injured marine mammals being rehabilitated for release back into the wild. The
costs of capturing, training, and maintaining marine mammals are great, meaning
that anyone working with a marine mammal must make a long-term commitment
to its care and well-being. Unlike work with small lab mammals or farm animals,
marine mammal research requires decades of obligation to the animals, including
experienced trainers and veterinarians and long-term care of trained and retired
animals. Some rare marine mammals will only become available for study at
such facilities that have received them after rescues. Lack of specialized research
facilities hinders the priority studies described earlier. For example, a rare oppor-
tunity to obtain evoked potential audiometric data from a stranded baleen whale
(a juvenile gray whale) was lost when competing demands for access made it
impossible to get sufficient time with the animal to test its hearing. This experi-
ence emphasizes the need for not only better methods of obtaining auditory
information, but also for gaining access to species for which few or no auditory
data exist.
Currently, there is only one site in the United States (and perhaps the world)
that has the facilities and animals that could be used in such studies. This site is
operated by the U.S. Navy in San Diego, California.1 Even this site has its
limitations, however, in that investigators must be U.S. citizens to work with the
trained animals. Although some research on the hearing abilities of marine
mammals could possibly be conducted at public aquariums, research commit-
ments at aquariums usually are secondary to public display requirements. In
addition, they are not able to do research with animals in the open sea, as is
possible with the highly trained animals maintained by the Navy. Such training
takes years and is beyond the capabilities or interests of public aquariums. The
ocean science community has a variety of different centers and shared-used
facilities, for example, the Ocean Drilling Program, that could provide a model
for a national captive marine mammal research facility.
Recommendations: If the studies described in Chapter 3 and Box 5.1 are of
sufficient priority to reduce uncertainties in the regulation of human-generated
sound in the ocean, federal agencies should establish a national facility for the
study of marine mammal hearing and behavior. The Committee believes that
such a facility might be established at relatively little incremental cost by enhance-
ment of the existing Navy facility.
1The one committee member associated with this facility did not take a position on whether the
facility could or should be expanded and made available beyond Navy scientists.
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The facility for captive marine mammal research would have animals for
"hire" by investigators funded for peer-reviewed research. Offset funds would
come from individual grants and researchers, but the funding base for such a
facility should not be provided solely by such offsets. Allocation of space,
animals, and facility resources should be determined by a broad-based review
board on the basis of the quality and significance of the proposed research. An
additional virtue of establishing a national captive marine mammal research
facility is that the total number of marine mammals removed from the wild would
be minimized. Investigators could apply for support for short- or long-term study
of the animals at this facility, from the range of agencies funding marine mammal
research, at costs that would not have to include long-term maintenance of the
animals. Such a facility should include the capability to work with trained ani-
mals in the open ocean. The Navy's Marine Mammal Program facility in San
Diego keeps marine mammals and already has trained animals and expertise in
maintaining them. Its role potentially could be expanded to provide a more
widely accessible national facility, including unclassified research. If such a
facility is operated by the Navy, it will be necessary to ensure that research data
are not restricted from publication. Establishment of a facility to promote field
studies could also enable research recommended in this report, but such a facility
would be more expensive and a lower priority than a national facility for research
on trained, captive animals.
REGULATORY REFORM
Findings: The existing permit system for acoustic research is unnecessarily
restrictive in some aspects and not comprehensive enough in other regards. It is
not scientifically defensible to apply general source standards for permit require-
ments (120 dB for continuous sound, 160 dB for intermittent sound, and 180 dB
for sounds of all frequencies and durations) for all species and all sound charac-
teristics under all possible conditions. Until NMFS publishes new acoustic guide-
lines, current NMFS policy recommends applying for a small-take authorization
for sound-producing research activities that have the potential to harass, injure, or
kill a marine mammal (K. Hollingshead, NMFS, personal communication, 1999~.
Different species have different sensitivities and susceptibilities, and sound effects
may accumulate as new sources are added. In the absence of information,
managers rightly have chosen to be cautious, at least in regard to permitting
ocean science research. However, as noted in NRDC (1999), there is virtually no
regulation of sound produced by large commercial ocean-going vessels: "The
worst polluter, shipping, is also the least regulated, while a comparative light-
weight [in terms of the amount of sound put into the ocean], scientific research, is
far more strictly scrutinized" (p. 13~. This combination of cautious regulation of
minor activities, coupled with lack of regulation of major noise sources, will not,
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in the long run, adequately protect marine mammals from potentially deleterious
effects of noise and could unnecessarily impede important acoustic research.
Recommendations: Congress should change the Marine Mammal Protection
Act (MMPA) and/or NOAA should change the implementing legislation of the
MMPA to allow incidental take authorization based solely on negligible impact
on the population. Research should be undertaken to allow the definition of
Level A harassment to be related to the TTS produced in a species, when known.
Level B harassment should be limited to meaningful disruption of biologically
significant activities that could affect demographically important variables such
as reproduction and longevity.
COMPREHENSIVE MONITORING AND REGULATION
OF SOUND IN THE OCEAN
Findings: Protecting marine mammals from significant adverse impacts clearly
requires a broader application of regulations. There is a global increase of sound
levels in the sea resulting from shipping, recreation, aircraft, and naval operations
as well as research (Urick, 1986~. It is important to characterize the existing
ambient sound field in terms of the levels, frequencies, and locations of sources,
especially in terms of areas particularly important for marine mammals (i.e., the
"hotshots" of NRDC, 1999~. Such a characterization of the ambient noise field
will provide a context for determining when, where, and with what characteristics
new sources could be added.
Recommendations: Noise monitoring is important and acoustic hotspots should
be identified. Fortunately, ambient noise data exist for a variety of locations,
which could provide time series and baselines for additional monitoring. Exist-
ing data should be identified and made accessible through a single easy-to-access
source. Like marine mammal research programs, funding for noise monitoring
should be awarded based on responses to a request for proposals and careful
evaluation of the costs and benefits of the proposed systems. The opening of the
existing IUSS for whale research was important for demonstrating the power of
bottom-mounted hydrophore arrays, but the IUSS may or may not provide the
best system for the acoustic monitoring tasks envisioned here, given that it was
designed for an entirely different purpose.
The first step in comprehensive monitoring and regulation of sound in the
ocean should be to attempt to characterize the existing ambient sound field in the
ocean and to characterize the sources that contribute to it. Monitoring of baseline
sound levels should be carried out, particularly in critical habitats of acoustically
sensitive or vulnerable species or in habitats critical to specific life stages, such as
breeding and calving areas. Protection of marine mammals from subtle or long-
term effects of harassment cannot be achieved through regulation of individual
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FINDINGS AND RECOMMENDATIONS
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"takes." An alternative habitat-oriented approach is required to protect marine
mammals from the cumulative impacts of noise pollution, chemical pollution,
physical habitat loss, and fishing. Such an approach requires monitoring of the
status of marine mammal populations along with the quality of critical habitats,
including the acoustic quality. Account should be taken of the populations in-
volved; it is sensible to protect more rigorously species that are more endangered
(e.g., northern right whales) than those that are less at risk. Basic research
regarding what is significant about critical habitats and what factors have
population-level effects for example, food supply, water quality, and noise
levels and characteristics will prove much more effective for protecting marine
mammals than merely attempting to regulate individual human activities that
may potentially cause changes in the behavior of an individual marine mammal.
NMFS regulations should encompass the entirety of noise pollution and other
threats to marine mammals.
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Representative terms from entire chapter:
marine mammal
