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4
Regulatory Issues
ACOUSTIC HARASSMENT
The intent of the Marine Mammal Protection Act (MMPA) is the manage-
ment and regulation of human activities that affect distinct populations of marine
mammals and the protection of essential marine mammal habitats. Conservation
of whales and seals and their environments must be continuous, and the National
Marine Fisheries Service (NMFS)1 should develop long-term strategies to fulfill
the MMPA's mandates. For example, NMFS has an obligation to collect the
necessary data to monitor the long-term health of whale and seal populations,
including population trends, distribution and abundance, and definition and status
of critical habitats.2 Conserving populations and habitats should be the guiding
principles for regulation of activities impacting whales and seals. The acoustic
parameters of the habitat are just as important as other habitat characteristics,
although much less is known about the acoustic features of critical habitats. The
National Research Council (NRC, 1994) devoted one of its three chapters to
marine mammal regulatory issues. This chapter discusses the existing regulatory
procedures affecting acoustic harassment, recommends changes to those proce-
1The U.S. Fish and Wildlife Service is responsible for conservation for some marine mammal
species, including manatees, dugongs, polar bears, walruses, and marine and sea otters. The Com-
mittee does not consider such species in this report because most are less likely to be affected
specifically by low-frequency sound than are whales and seals, although the vocalization and hearing
capabilities of these species have not been well characterized. NMFS has the responsibility for
whales and seals (except walruses).
2The Endangered Species Act requires the designation of critical habitats for endangered and
threatened species.
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MARINE MAMMALS AND LOW-FREQUENCY SOUND
cures, and discusses the permitting process. Here, the Committee considers how
the MMPA could be changed in its next reauthorization to improve the definition
of harassment from acoustic sources.
The NRC (1994) suggested that the regulations governing the taking of
marine mammals by fishing activities should be broadened to include other user
groups that might take marine mammals. This concept was incorporated into the
1994 MMPA amendments. The MMPA now requires calculation for each species
of a conservative number of animals that might be taken by humans from marine
mammal stocks, while "allowing that stock to reach or maintain optimum sus-
tainable population," called the potential biological removal (PBR) level (MMPA,
Sec. 1362[t]; see Appendix C). NMFS is required to tally all human-induced
mortality for its stock assessments (MMPA Sec.1386[aj) and uses this number to
estimate PBR. The PBR regime seems to be working, although additional effort
may be required to quantify marine mammal takes from all human activities so
that they can be incorporated into the PBR, even though this might reduce the
takes allowed to fishermen. However, it would be virtually impossible in the near
future to sum all sources of lethal takes to compare with the PBR for any species
and lethal takes by sound would be particularly problematic because it is so
difficult to prove that they resulted as a consequence of human-generated sound.
Takes are not allocated officially, but many fisheries operate under prohibited
species quotas and thus automatically received part or all of the PBR level of
takes, whereas research scientists must apply for takes through a small-take
exemption. If the takes counted against the PBR of a marine mammal stock are
known to not include all human takes, the PBR should be adjusted downward
accordingly.
The core of the MMPA is a "moratorium on the taking or importation of
marine mammals" (Sec. 1371~. "Taking" is defined in the MMPA as "to harass,
hunt, capture, or kill or attempt to harass, hunt, capture, or kill any marine mam-
mal" (Sec.1362[m]~. The 1994 amendments to the MMPA included a definition
of harassment (Sec.1362[rj) as "any act of pursuit, torment, or annoyance which:
Level A has the potential to injure a marine mammal or marine mammal
stock in the wild; or
Level B has the potential to disturb a marine mammal or marine mammal
stock in the wild by causing disruption of behavioral patterns, including, but not
limited to, migration, breathing, nursing, breeding, feeding, or sheltering."
In its 1994 report the NRC identified drawbacks to these definitions. Swartz
and Hofman (1991) reviewed the issue of taking by harassment in the context of
small-take authorizations before the enactment of the 1994 MMPA amendments.
They noted (pp. 2-3) that "the term 'harass' has been interpreted through practice
to include any action that results in an observable change in the behavior of a
marine mammal for example, abrupt termination of breeding or feeding, avoid-
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REGULATORY ISSUES
67
ance behavior, and changes in swimming speed, dive frequency, dive duration, or
direction of movement." The NRC noted that, as techniques for observing marine
mammals improve, it may become possible to observe responses as soon as an
animal can detect an acoustic signal, even though such responses may not consti-
tute evidence of a significant negative effect. This has, in fact, occurred. For
example, Burgess et al. (1998) were able to track the heart rates of free-ranging
elephant seals, and time-depth recorders recorded subtle meter-by-meter patterns
of dive behavior. Such data can be combined with data on received sound levels
to determine behavioral thresholds of sound, levels that animals react to with
some physiological or behavioral response, but which are not necessarily danger-
ous to the animals. Conversely, for long sound exposures (hours to days), TTS
can occur without any behavioral response. It cannot be assumed that avoidance
responses to continuous noise will prevent injury in the wild. For example,
animals might be motivated to approach a loud source that produced a TTS if the
source was near food that the animal sought. This reinforces the need to focus on
predicted TTS rather than behavior, although this is not now possible for most
species. The NRC (1994, 1996) has advocated a regulatory definition of harass-
ment that focuses on adverse effects to marine mammals.
The Committee supports this effort to distinguish between injury and disrup-
tion of behavior and proposes a refinement of the above definitions to incorporate
and differentiate between immediate injury and longer-term, significant physi-
ological and behavioral effects that may affect the growth, reproduction, or
mortality of animals. Moreover, regulatory efforts directed at minimizing and
mitigating the effects of anthropogenic sounds on marine mammals and other
marine organisms should have the goal of minimizing the risk of injury and
meaningful disruption of biologically significant activities, where biological sig-
nificance is defined as having potential demographic effects on reproduction or
longevity.
Definition of Level A Acoustic Harassment
The definition of Level A acoustic harassment should be related to the like-
lihood that a sound will produce a temporary threshold shift (TTS), as well as to
the magnitude of the TTS. However, relatively little is known about TTS in
marine mammals, and this would be a difficult standard to implement, at least
with existing knowledge. The problem of using TTS as an absolute standard of
injury is illustrated by terrestrial mammals, for which it is possible for an animal
to exhibit small amounts of TTS on numerous occasions without TTS developing
into a PTS. Animals that experience only low levels of TTS are not going to be
injured, suggesting TTS as a conservative standard for prevention of injury. In
humans the best predictions about the relationship between TTS and PTS come
from datasets involving noise exposures in the workplace. For those situations
the standard rule of thumb is that the amount of TTS exhibited at the end of a
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MARINE MAMMALS AND LOW-FREQUENCY SOUND
single workday will become a PTS of that same magnitude after approximately
10 years in the workplace (e.g., Nixon and Glorig, 1961~. However, that predic-
tion is based on the assumption of daily exposures to that same sound for 5 days
per week and 50 weeks per year during that 10-year period. That is, this predic-
tion presumes regular long-duration exposures. With less frequent exposures the
time required to cause equivalent PTS would be extended. Clearly relevant here
for the question of Level A harassment is the amount of TTS produced because
large amounts of TTS will lead to measurable amounts of PTS sooner than will
small amounts. That is, there might be a negative effect on the ability of a marine
mammal to hear and communicate after only a few exposures to sounds strong
enough to produce large amounts of TTS in that species. (As noted elsewhere in
this report, maximal TTS and PTS often occur at frequencies above the exposure
frequency by as much as an octave or more.)
For certain animal models it appears that TTS of 10 dB and less within 15
minutes after the exposure is fully reversible and without obvious cochlear
damage (Liberman and Dodds, 1987; Ahroon et al., 1996) as long as the expo-
sures are not continued for long periods of time. In both these studies, cochlear
damage was evident only after TTS exceeded 40 to 60 dB within 15 minutes after
the exposure. However, species differences are relevant here, too, because there
is some evidence in primates that even in the absence of a measurable PTS or a
functional change in hearing, there can be anatomical evidence of damage to the
cochlea following repeated episodes of TTS over the course of months (Lonsbury-
Martin et al., 1987~.
These facts, coupled with the general ignorance that exists about TTS in
marine mammals, make it impossible to identify an exposure level that would be
unequivocally safe for all the members of a species. However, as a preliminary
criterion, it seems reasonable to presume that any sound that produces a TTS of
10 dB or less in exposure episodes that are separated by nonexposure intervals
that are ample to allow full recovery (at least 24 hours) does not constitute a
major risk to the auditory system of a marine mammal. As knowledge of the
auditory systems of marine mammals increases, this preliminary criterion should
be reexamined.
Definition of Level B Acoustic Harassment
It does not make sense to regulate minor changes in behavior having no
adverse impact; rather, regulations must focus on significant disruption of behav-
iors critical to survival and reproduction, which is the clear intent of the definition
of harassment in the MMPA. For example, Malme et al. (1983) documented that
migrating gray whales show a statistically significant avoidance of an area a few
hundred meters around a source playing back the sounds of oil industry activities.
It is difficult to assess the impact of this avoidance on gray whale survival and
reproduction because the adaptive value of migrating close to shore is unknown.
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69
From one perspective, this avoidance is an adaptive response because it would
protect the whales from approaching industrial activities too closely and would,
at worst, delay their migration from Alaska to Mexico by a few minutes. From
another perspective, even a small avoidance could result in unanticipated conse-
quences. If the avoidance response makes the whales more vulnerable to preda-
tion by killer whales, or the sound producing the avoidance response masks killer
whale sounds or other environmental cues, the avoidance could have effects
beyond delaying migration.
Activities that produce statistically significant but biologically insignificant
responses are subject to take authorizations under the MMPA and ESA as the
regulations are currently implemented; responsible agencies must provide autho-
rization unless there is good justification for concluding that the effects will not
be negligible. Such review would be a reasonable approach if "negligible effects"
were defined more appropriately. For example, current research suggests that
thousands of ships each day are likely to cause short-term avoidance responses,
and many of these responses may help reduce the risk of vessel collision. If the
current interpretation of the law for Level B harassment (detectable changes in
behavior) were applied to shipping as strenuously as it is applied to scientific and
naval activities, the result would be crippling regulation of nearly every motorized
vessel operating in U.S. waters. NMFS should promulgate uniform regulations
based on their potential for a biologically significant impact on marine mammals.
Thus, Level B harassment should be redefined as follows:
Level B has the potential to disturb a marine mammal or marine mammal
stock in the wild by causing meaningful disruption of biologically significant
activities, including but not limited to, migration, breeding, care of young,
predator avoidance or defense, and feeding.
The Committee suggests limiting the definition to functional categories of
activity likely to influence survival or reproduction. Thus, the term "sheltering"
that is included in the existing definition is both too vague and unmeasurable to
be considered with these other functional categories.
There are several exemptions to the moratorium on taking marine mammals
provided in the MMPA and its implementing regulations. They include
(1) permits for scientific research on marine mammals (Sec. 1374[cl[3l);
(2) authorization by rule making to take small numbers of marine mammals
incidental to activities other than commercial fishing (Sec. 1371[aj[51[Aj); and
(3) authorization by a more streamlined process for the unintentional take of
small numbers of marine mammals by harassment incidental to activities other
than marine fishing (Sec. 1371 (a)~5~(D)~. Each exemption has implications for
uses of sound for scientific research in the ocean. Although Congress intended to
provide less stringent means for marine scientists to obtain permission to uninten-
tionally harass marine mammals to an insignificant degree, NMFS has applied its
regulations most stringently to science.
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MARINE MAMMALS AND LOW-FREQUENCY SOUND
The criterion of negligible impact on a population from all human activities
should consider the number of individuals (or percent of population) potentially
impacted and the risk of impact to each individual. Decisions should consider
critical habitat issues and the status of a population, as well as sensitivity of
different marine mammals to the type of activity proposed. For activities that
include introduction of sound to the ocean, frequency, duration, temporal charac-
teristics of the sound, and the relevance of these sound qualities to characteristic
species should be considered. Also, the total duration and spatial extent of the
sound field must be taken into consideration (Reeves et al., 1996~. The ultimate
long-term goal should be a risk function involving intensity and duration of
exposure (see Miller, 1974) for each species, but our current lack of knowledge
impedes this goal.
Scientific Research Permits
When Congress reauthorized the MMPA in 1994 it allowed the issuance of
general authorizations for research on marine mammals. NMFS has excluded
acoustic studies not focused on marine mammals (like the Acoustic Thermometry
of Ocean Climate experiment) from this harassment authorization category. The
rationale for this exclusion is that permits are for research on marine mammals;
research that incidentally affects marine mammals was not meant to be covered.
The Committee believes that all forms of scientific research permits, relating
to both Level A and Level B harassment, should be judged by compatible stan-
dards. The existing regulatory regime does not consistently regulate research that
could affect either directly or indirectly marine mammals. For example, a
biologist proposing to study how a whale responds to vessel noise would have to
apply for a scientific research permit, whereas an oceanographer planning to
transit the same habitat in a large research vessel would not be subject to any
regulation, and an acoustician using a similar level of sound for studies unrelated
to marine mammals might need to obtain an incidental harassment authorization.
It seems illogical to regulate the artificially induced acoustic stimuli more
intensely than the vessel-induced sound, which adds the risk of actually striking
the whale. For example, the MMPA and NMFS regulations should include
acoustic studies in the regulatory procedures related to approvals for harassment
during scientific research.
Incidental Harassment Authorization
NMFS has proposed regulations for implementing Section 1371(a)~5~(D) of
the MMPA, which provides a streamlined process for obtaining incidental take
authorization when the taking would be by harassment only (DOC, 1995~. These
regulations appear to address some of the concerns of NRC (1994), which stated
that regulation of acoustic harassment posed significant barriers to scientific
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71
research. An interim final rule was published in 1996 to expedite the processing
of incidental harassment authorization (IHA) requests for oil- and gas-related
activities (DOC, 1996~. NMFS expects to publish new criteria in the near future
and will develop new regulations and guidelines after review and comment on the
criteria. The delay in issuing final regulations occurred because NMFS, the
Navy, and other groups wanted to discuss the effects of noise on marine mam-
mals in workshop settings to gather a broad base of information (e.g., Reeves et
al., 1996; Gisiner, 1998~.
Persons requesting an IHA must provide information demonstrating that any
taking is likely to be by harassment only, will be unintentional, will involve small
numbers of marine mammals, and will have a negligible impact on the affected
species and stocks. NMFS has defined "small numbers" as a portion of a marine
mammal species or population stock whose taking would have negligible impact
on the viability of that species or stock. The Committee supports incorporating
population status into regulations on harassment. The duration and expected
severity of the proposed harassment also should be factored into these authoriza-
tions, recognizing that the environmental impacts of acoustic pollution, like other
environmental impacts, can have cumulative effects.
In addition to making the suggested change in the Level B harassment defi-
nition, it would be desirable to remove the phrase "of small number" from MMPA
Section 1371(a)~5~(D)(i). If such a change is not made, it is conceivable under
the current MMPA language there would be two tests for determining takes by
harassment, small numbers first, and if that test were met, negligible impact from
that take of small numbers. The suggested change would prevent the denial of
research permits that might insignificantly harass large numbers of animals and
would leave the "negligible impact" test intact.
CUMULATIVE IMPACTS
Even if marine mammals are protected on a case-by-case basis from indi-
vidual acts of harassment extreme enough to have an adverse impact, they may
require additional protection from milder harassment that is repeated so often that
impact accumulates. One way to address this issue is to study how animals
respond to repeated exposure. Most animals habituates to repeated exposure to
the same stimulus. This reduced probability and reduced intensity of response
suggest that applying a response model based on single exposures may be overly
conservative, but there are few data on habituation in marine mammals.
Alternatively, animals can be sensitized to stimuli, in that their later responses
may be greater than earlier responses. The Committee is not aware of any
Behavioral habituation is ``a desensitization to a specific stimulus situation (Lorenz, 1981).
Habituation to a loud noise is not necessarily adaptive and could actually make ITS or PTS more
likely.
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MARINE MAMMALS AND LOW-FREQUENCY SOUND
definitive experiments conducted since 1994 on habituation of marine mammals
to a noise stimulus, although the National Oceanic and Atmospheric Administra-
tion and the Marine Mammal Commission are extremely interested in this issue
because of its relevance to using higher-frequency sound (e.g., 10 kHz) as an
acoustic deterrence to reduce interactions between marine mammals and the
fishing industry (Reeves et al., 1996~. Kastak and Schusterman (1996) showed in
unpublished research that one individual harbor seal and two California sea lions
eventually habituated to clicks and frequency-modulated tone stimuli, but an
elephant seal appeared to become sensitized. Clearly, these data are limited by
our ignorance of differences among these species, but the Kastak and Schusterman
study does underscore the importance of investigating species differences in
sensitivity to acoustic stimuli (see Chapter 5) because there may be species-
specific responses to representative anthropogenic sounds.
The Committee also suggests that activities that are presently unregulated,
but which are major sources of sound to the ocean (e.g., commercial shipping) be
brought into the regulatory framework of the MMPA. Such a change should
increase protection of marine mammals by providing a comprehensive regulatory
regime for acoustic impacts on marine mammals, eliminating what amounts to an
exemption on regulation of commercial sound producers and the current and
historic focus on marine mammal science, oceanography, and Navy activities.
Representative terms from entire chapter:
marine mammal
