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Small Takes of Marine Mammals Incidental to Specified Activities; Oceanographic Surveys in the Mid-Atlantic Ocean
Note: EPA no longer updates this information, but it may be useful as a reference or resource.
[Federal Register: September 17, 2003 (Volume 68, Number 180)]
[Notices]
[Page 54421-54429]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr17se03-41]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[I.D. 080803C]
Small Takes of Marine Mammals Incidental to Specified Activities;
Oceanographic Surveys in the Mid-Atlantic Ocean
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice of receipt of application and proposed incidental take
authorization; request for comments.
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SUMMARY: NMFS has received an application from the Lamont-Doherty
Earth Observatory (LDEO), a part of Columbia University, for an
Incidental Harassment Authorization (IHA) to take small numbers of
marine mammals, by
[[Page 54422]]
harassment, incidental to conducting oceanographic surveys in the Mid-
Atlantic Ocean. Under the Marine Mammal Protection Act (MMPA), NMFS is
requesting comments on its proposal to issue an authorization to LDEO
to incidentally take, by harassment, small numbers of several species
of cetaceans and pinnipeds for a limited period of time within the next
year.
DATES: Comments and information must be received no later than October
17, 2003.
ADDRESSES: Comments on the application should be addressed to the
Acting Chief, Marine Mammal Conservation Division, Office of Protected
Resources, National Marine Fisheries Service, 1315 East-West Highway,
Silver Spring, MD 20910-3225, or by telephoning the contact listed
here. A copy of the application containing a list of the references
used in this document may be obtained by writing to this address or by
telephoning the contact listed here. Comments cannot be accepted if
submitted via e-mail or the Internet.
FOR FURTHER INFORMATION CONTACT: Sarah C. Hagedorn, Office of Protected
Resources, NMFS, (301) 713-2322, ext 117.
SUPPLEMENTARY INFORMATION:
Background
Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.)
direct the Secretary of Commerce to allow, upon request, the
incidental, but not intentional, taking of marine mammals by U.S.
citizens who engage in a specified activity (other than commercial
fishing) within a specified geographical region if certain findings are
made and either regulations are issued or, if the taking is limited to
harassment, a notice of a proposed authorization is provided to the
public for review.
Permission may be granted if NMFS finds that the taking will have a
negligible impact on the species or stock(s) and will not have an
unmitigable adverse impact on the availability of the species or
stock(s) for subsistence uses and that the permissible methods of
taking and requirements pertaining to the monitoring and reporting of
such takings are set forth. NMFS has defined ``negligible impact'' in
50 CFR 216.103 as ``...an impact resulting from the specified activity
that cannot be reasonably expected to, and is not reasonably likely to,
adversely affect the species or stock through effects on annual rates
of recruitment or survival.''
Subsection 101(a)(5)(D) of the MMPA established an expedited
process by which citizens of the United States can apply for an
authorization to incidentally take small numbers of marine mammals by
harassment. Under Section 3(18)(A), the MMPA defines ``harassment'' as:
any act of pursuit, torment, or annoyance which (i) has the
potential to injure a marine mammal or marine mammal stock in the
wild; or (ii) 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.
The term ``Level A harassment'' means harassment described in
subparagraph (A)(i). The term ``Level B harassment'' means harassment
described in subparagraph (A)(ii).
Subsection 101(a)(5)(D) establishes a 45-day time limit for NMFS
review of an application followed by a 30-day public notice and comment
period on any proposed authorizations for the incidental harassment of
marine mammals. Within 45 days of the close of the comment period, NMFS
must either issue or deny issuance of the authorization.
Summary of Request
On July 21, 2003, NMFS received an application from LDEO for the
taking, by harassment, of several species of marine mammals incidental
to conducting a seismic survey program. As presently scheduled, two
seismic surveys will be conducted in the Mid-Atlantic Ocean. The Trans-
Atlantic Geotransect (TAG) cruise will be centered at 26oN and 45oW in
the Mid-Atlantic Ocean during mid- to late-October 2003, for a total of
six days of seismic surveying. The Atlantic Deep Western Boundary
Current (ADWBC) cruise will occur between 39o and 42oN and between 45o
and 52.5oW, and will take place at an, as of yet, unscheduled date
(likely in July, 2004) for a total of approximately 20 days of
surveying. These operations will take place in international waters.
The seismic survey work conducted during the TAG cruise is part of
a multi-disciplinary experiment, taking place in the TAG Active Mound
area over a period of nine months. The TAG active mound (26oN on the
Mid-Atlantic Ridge), which is one of the largest hydrothermal deposits
found to date on the seafloor, is a large, focused mineral deposit on a
slow-spreading ridge. The purpose of the TAG cruise is to delineate the
nature, position, and size of any heat sources (low-velocity zones)
that might drive convection at the TAG active mound, and more
generally, to provide an understanding of crustal architecture in the
TAG region. More specifically, the TAG experiment will address key
issues at the TAG site: (1) the nature of the heat source driving
circulation, (2) the relationship between faulting on the eastern flank
and fluid flow at the mound, (3) the possible existence of a low-
velocity zone beneath the rise axis, and (4) the hydraulic connectivity
of the shallow TAG mound.
The ADWBC cruise will determine the configuration, age, and
paleoceanographic significance of the sedimentary sequences on J
Anomaly Ridge and Southeast Newfoundland Ridge, which may show evidence
for strong boundary currents dating to the early Paleocene. Proposed
tracklines for the seismic survey were chosen with four primary
objectives in mind: (1) to map the main reflection sequences across the
full extent of the ridges and onto the edges of adjacent abyssal
plains, (2) to obtain continuity in tracing sequences by profiling
around major interruptions (seamounts) and optimizing track crossings,
(3) to provide abundant crossing lines in areas where existing seismic
and bathymetric data suggest that there are outcrops of pre-Neogene
strata, and (4) to take advantage of good-quality seismic data, where
they exist (e.g., Conrad 2510 MCS), in order to make loop correlations
between tracks.
Description of the Activity
The TAG seismic survey will involve a single vessel which will
conduct the seismic work, the R/V Maurice Ewing, operated by LDEO under
a cooperative agreement with the U.S. National Science Foundation
(NSF), owner of the vessel. The Maurice Ewing will deploy an array of
20 airguns as an energy source, and will deploy and retrieve Ocean
Bottom Hydrophones (OBHs). A hydrophone streamer will not be towed
during the TAG cruise. The energy to the airgun array is compressed air
supplied by compressors on board the source vessel. As the airgun array
is towed along the survey lines, the OBHs and Ocean Bottom Seismometers
(OBSs) will receive the reflected signals and transfer the data to the
onboard processing system. All planned geophysical data acquisition
activities will be conducted by LDEO scientists with onboard assistance
by the scientists who proposed the study. The TAG program will consist
of 185 km (100 n.mi.) of survey lines. There will be a total of three
seismic lines, two along- and one across-axis of the TAG. Water depths
in the area will vary from 1500 to 4500 m (4921-14,764 ft).
[[Page 54423]]
The ADWBC cruise will likely involve the oceanographic research
vessel R/V Knorr, a U.S. Navy-owned ship operated by the Woods Hole
Oceanographic Institution (WHOI). However, another vessel may
ultimately be chosen for the survey. Other possible vessels include,
but are not limited to, the R/V Maurice Ewing or a vessel from the
University-National Oceanographic Laboratory System (UNOLS). The vessel
would be using a portable LDEO seismic system to conduct the seismic
survey. The vessel will deploy 2 General Injector guns as an energy
source, plus a towed streamer containing hydrophones to receive the
returning acoustic signals. The hydrophone array will consist of a 600-
m (1969 ft) solid state streamer with a 200-m (656 ft) tow leader. The
energy to the airgun array is compressed air supplied by compressors on
board the source vessel. As the 2 GI guns are towed along the survey
line, the hydrophone array will receive the returning signals and
transfer the data to the onboard processing system. All planned
geophysical activities will be conducted by the scientists who have
proposed the study, while LDEO will provide the portable high-
resolution seismic system that will support the seismic surveys for the
proposed study. The ADWBC program will consist of 4334 km (2340 n.mi.)
of seismic profiles that will be shot over a period of 20 days. The
most detailed grids of seismic lines are proposed for the southern end
of J Anomaly Ridge and for moats around seamounts on the crest of the
Southeast Newfoundland Ridge - both are areas where there appear to be
extensive pre-Neogene outcrops. Water depths in the area will vary from
4000 to 5000 m (13,124-16,405 ft).
The procedures to be used for the two seismic studies will be
similar to those used during previous seismic surveys by LDEO, e.g., in
the equatorial Pacific Ocean (Carbotte et al., 1998, 2000). The
proposed seismic surveys will use conventional seismic methodology with
a towed airgun array as the energy source, and either a towed
hydrophone streamer or OBH and OBS receivers placed on the bottom to
receive the reflected signals. For the TAG survey, eighteen OBHs will
be deployed (and recovered) by the Maurice Ewing - eight along each of
the long axis lines and two on the across axis line. After the seismic
lines are shot, the data will be downloaded and the OBSs will be
retrieved during an, as of yet, unscheduled cruise in the summer of
2004 (during which no seismic sound sources will be used). Along three
selected seismic lines, 13 OBS receivers will be placed in the proposed
study area by the R/V Alvin from 7-24 June 2003, before the arrival of
the Maurice Ewing. In addition, a multi-beam bathymetric sonar will be
operated from the source vessel continuously throughout both cruises,
and a lower-energy sub-bottom profiler will also be operated during
most of both surveys. During the ADWBC study, coring of numerous
sedimentary outcrops known to exist on the ridges will also take place.
During both cruises, there will be additional operations associated
with equipment testing, startup, line changes, and repeat coverage of
any areas where initial data quality is sub-standard.
The R/V Maurice Ewing will be used as the source vessel during the
TAG cruise, and the R/V Knorr will likely be used as the source vessel
during the ADWBC cruise. Both vessels will tow airgun arrays along
predetermined lines, and will also serve as platforms from which
vessel-based marine mammal observers will watch for marine mammals
before and during airgun operations.
During TAG-study airgun operations, the vessel will travel at 7.4-
9.3 km/hr (4-5 knots), and seismic pulses will be emitted at intervals
of 60-90 seconds (OBS lines during the TAG cruise). The 60-90 sec.
spacing along OBS lines is to minimize reverberation from previous shot
noise during OBS data acquisition, and the exact spacing will depend on
water depth. The airgun array to be used will consist of 20 2000 psi
Bolt airguns, towed at a depth of 7.5 m (24.5 ft). The 20-gun array
will include airguns ranging in chamber volume from 80 to 850 in\3\,
with a total volume of 8,575 in\3\. These airguns will be spaced in an
approximate rectangle with dimensions of 35 m (115 ft) (across track)
by 9 m (30 ft) (along track).
The ADWBC seismic survey will be high-resolution, consisting of two
105 in\3\ GI airguns with a total volume of approximately 210 in\3\,
spaced 7.8 m (26 ft) apart, and towed 37 m (121 ft) behind the vessel
at a depth of 2-3 m (7-10 ft). Towing airguns at this shallow depth is
accomplished by suspending the guns from floats, and the resulting
short-period free surface ``ghosting'' keeps the spectral content broad
with usable signals up to 300-350 Hz. These airguns produce an
unusually clean impulse with sufficient energy to penetrate many
hundreds of meters of sediment. Airgun firing, timing, and
synchronizing is handled by a LDEO-built controller, which is
integrated with a SUN workstation-based DGPS navigation, data logging,
and fire control system. The air is produced by a standalone Price Co.
2000 psi compressor, and the seismic signals are detected by a solid
state ITI hydrophone ``Stealtharray'', with 48 12.5-m (41 ft) long
channels, and a total length of 600 m (1969 ft).
The dominant frequency components for both airgun arrays is 0 - 188
Hz. The 2-airgun array will have a peak sound source output level of
237 dB re 1 microPa or 243 dB peak-to-peak (P-P). The 20-airgun array
will have a peak sound source output level of 255 dB re 1 microPa or
262 dB P-P. Because the actual source is a distributed sound source (2
or 20 airguns) rather than a single point source, the highest sound
levels measurable at any location in the water will be less than the
nominal source level. Also, because of the downward directional nature
of the sound from these airgun arrays, the effective source level for
sound propagating in near-horizontal directions will be substantially
lower.
Along with the airgun operations, several additional acoustical
data acquisition systems will be operated during most or all of the
cruises. The ocean floor will be mapped with an Atlas Hydrosweep DS-2
multi-beam 15.5-kHz bathymetric sonar, and/or a 3.5-kHz sub-bottom
profiler. These mid-frequency sound sources are commonly operated from
research vessels simultaneous with airgun arrays as well as in the
absence of airgun activity.
The Atlas Hydrosweep sonar will be used during cruises by the R/V
Maurice Ewing, is mounted in the hull of the vessel, and operates in
three modes depending on the water depth. The first is a shallow-water
mode when water depth is <400 m (1312.3 ft); source output is 210 dB re
1 microPa-m rms and a single 1-millisec (ms) pulse or ``ping'' per
second is transmitted, with a beamwidth of 2.67 degrees fore-aft and 90
degrees in athwartship. The beamwidth is measured to the -3 dB point,
as is usually quoted for sonars. The other two modes are deep-water
modes: The Omni mode is identical to the shallow-water mode except that
the source output is 220 dB rms (normally used only during start up).
The Rotational Directional Transmission (RDT) mode is normally used
during deep-water operation and has a 237 dB rms source output. In the
RDT mode, each ``ping'' consists of five successive transmissions, each
ensonifying a beam that extends 2.67 degrees fore-aft and approximately
30 degrees in the cross-track direction. The five successive
transmissions (segments) sweep from port to starboard with minor
overlap, spanning an overall cross-track angular extent of about 140
degrees, with tiny (<1 millisec) gaps between the pulses for successive
30-degree segments. The
[[Page 54424]]
total duration of the ``ping'', including all 5 successive segments,
varies with water depth but is 1 ms in water depths <500 m (1640.4 ft)
and 10 ms in the deepest water. For each segment, ping duration is 1/
5th of these values or 2/5th for a receiver in the overlap area
ensonified by two beam segments. The ``ping'' interval during RDT
operations depends on water depth and varies from once per second in
<500 m (1640.5 ft) water depth to once per 15 seconds in the deepest
water.
If the R/V Knorr is used for the ADWBC cruise, the SeaBeam 2100/12
multibeam 12 kHz bathymetric sonar system will be used, with a source
output of 237 dB re 1 microPa-m. Operation of this system is similar to
that of the Atlas Hydrosweep (described above). The SeaBeam 2100/12
system has a swath width of about 3 times the water depth, so it will
provide data over swaths 10-15 km (5-8 n.mi.) wide during most of the
survey.
The sub-bottom profiler is normally operated to provide information
about the sedimentary features and bottom topography that is
simultaneously being mapped by the Hydrosweep. The energy from the sub-
bottom profiler is directed downward by a 3.5-kHz transducer mounted in
the hull of the vessel. The output varies with water depth from 50
watts in shallow water to 800 watts in deep water. Pulse interval is 1
sec. but a common mode of operation is to broadcast five pulses at 1-
sec. intervals followed by a 5-sec. pause. The beamwidth is
approximately 30[deg]
and is directed downward. Maximum source output
is 204 dB re 1 microPa, 800 watts, while nominal source output is 200
dB re 1 microPa, 500 watts. Pulse duration will be 4, 2, or 1 ms, and
the bandwith of pulses will be 1.0 kHz, 0.5 kHz, or 0.25 kHz,
respectively.
For the ADWBC cruise, the multibeam bathymetry and sub-bottom
profiling will be used to define windows where erosion or non-
deposition has exposed deeper sequences suitable for piston coring.
Coring transects across these windows will provide biostratigraphic age
determinations that can be used to constrain the age of reflections
throughout the study area. There will be five days of piston coring
following completion of the ADWBC seismic survey.
Additional information on the airgun arrays, bathymetric sonars,
and sub-bottom profiler specifications is contained in the application,
which is available upon request (see ADDRESSES).
Description of Habitat and Marine Mammals Affected by the Activity
A detailed description of the Mid-Atlantic Ocean and its associated
marine mammals can be found in a number of documents referenced in the
LDEO application as well as in the LDEO application itself, and is not
repeated here. There will be differences in species composition between
the two study sites in the Mid-Atlantic, since the ADWBC cruise will
take place at a more northern latitude than the TAG cruise. Therefore,
species with more northerly distributions are only likely to be sighted
during the ADWBC cruise, and species with more southerly/tropical
distributions will only be encountered during the TAG cruise, if at
all. The two proposed cruises are also scheduled to occur in different
seasons, and that could have an effect on the species and numbers
present in the area. Approximately 34 species of cetaceans are known to
occur within the proposed study areas in the Mid-Atlantic Ocean, six of
which only rarely occur in the areas. These species are the sperm whale
(Physeter macrocephalus), pygmy sperm whale (Kogia breviceps), dwarf
sperm whale (Kogia sima), Cuvier's beaked whale (Ziphius cavirostris),
northern bottlenose whale (Hyperoodon ampullatus), True's beaked whale
(Mesoplodon mirus), Gervais' beaked whale (Mesoplodon europaeus),
Sowerby's beaked whale (Mesoplodon bidens), Blainville's beaked whale
(Mesoplodon densirostris), rough-toothed dolphin (Steno bredanensis),
bottlenose dolphin (Tursiops truncatus), Pantropical spotted dolphin
(Stenella attenuata), Atlantic spotted dolphin (Stenella frontalis),
spinner dolphin (Stenella longirostris), clymene dolphin (Stenella
clymene), striped dolphin (Stenella coeruleoalba), short-beaked common
dolphin (Delphinus delphis), Fraser's dolphin (Lagenodelphis hosei),
white-beaked dolphin (Lagenorhynchus albirostris), Atlantic white-sided
dolphin (Lagenorhynchus acutus), Risso's dolphin (Grampus griseus),
melon-headed whale (Peponocephala electra), pygmy killer whale (Feresa
attenuata), false killer whale (Pseudorca crassidens), killer whale
(Orcinus orca), long-finned pilot whale (Globicephala melas), short-
finned pilot whale (Globicephala macrorhynchus), North Atlantic right
whale (Eubalaena glacialis), humpback whale (Megaptera novaeangliae),
minke whale (Balaenoptera acutorostrata), Bryde's whale (Balaenoptera
edeni), sei whale (Balaenoptera borealis), fin whale (Balaenoptera
physalus), and blue whale (Balaenoptera musculus). Also, six species of
pinnipeds could potentially be encountered during the proposed seismic
surveys, although their occurrence in the study area is unlikely. These
include the bearded seal (Erignathus barbatus), hooded seal (Cystophora
cristata), harbor seal (Phoca vitulina), ringed seal (Pusa hispida),
grey seal (Halichoerus grypus), and the harp seal (Pagophilus
groenlandicus). Additional information on most of these species is
contained in Caretta et al. (2001, 2002) which is available at:
http://www.nmfs.noaa.gov/prot_res/PR2/Stock_Assessment_Program/sars.html.
Potential Effects on Marine Mammals
The sound pressure fields for the 2-GI and 20-gun arrays have been
modeled by LDEO, in relation to distance and direction from the
airguns. Table 1 in the application (LDEO Mid-Atlantic 2003) shows the
maximum distances from the arrays where sound levels of [gteqt]190,
180, 170, and 160 dB re 1 microPa (rms) are predicted to be received:
------------------------------------------------------------------------
Predicted RMS Radii in meters/ft
Airgun Array --------------------------------------------------
190 dB 180 dB 170 dB 160 dB
------------------------------------------------------------------------
2 GI guns...... 17/56 54/177 175/574 510/1673
20 airguns..... 275/902 900/2953 2600/8531 9000/29,529
------------------------------------------------------------------------
Notice of a previous (LDEO) application and proposed IHA was
published in the Federal Register on April 14, 2003 (68 FR 17909). That
notice described, in detail, the characteristics of the Ewing's
acoustic sources and, in general, the anticipated effects on marine
mammals including masking, disturbance, and potential hearing
impairment and other physical effects. That information is not repeated
here. However, possible effects of the sub-bottom profiler, which was
not used in the project described in that notice, are described below.
Details on acoustic sources from the 2-GI gun array, which will be
installed on the R/V Knorr for the ADWBC cruise as part of an LDEO
[[Page 54425]]
portable high-resolution seismic system, were described in an earlier
Federal Register notice on April 11, 2003 (68 FR 17773). The current
LDEO Mid-Atlantic application also provides information on what is
known about the effects on marine mammals of the types of seismic
operations planned by LDEO.
Possible Effects of the Sub-bottom Profiler Signals
Sound levels have not been measured for the sub-bottom profiler
used by the Maurice Ewing, but Burgess and Lawson (2000) measured the
sounds propagating more or less horizontally from a similar unit with
similar source output (205 dB re 1 microPa-m). The 160 and 180 dB re 1
microPa (rms) radii, in the horizontal direction, were estimated to be
near 20 m (66 ft) and 8 m (26 ft), respectively, from the source, as
measured in 13 m (43 ft) water depth. The corresponding distances for
an animal in the beam below the transducer would be greater, on the
order of 180 m (591 ft) and 18 m (59 ft), assuming spherical spreading.
The sub-bottom profiler on the Maurice Ewing has a maximum source
level of 204 dB re 1 microPa-m. Thus the received level would be
expected to decrease to 160 and 180 dB at about 160 m (525 ft) and 16 m
(52 ft) below the transducer, respectively (assuming spherical
spreading). Corresponding distances in the horizontal plane would be
lower, given the directionality of this source (30[deg]
beamwidth) and
the measurements of Burgess and Lawson (2000).
Masking by Sub-bottom Profiler Signals
There is little chance that marine mammal communications will be
masked appreciably by the sub-bottom profiler signals given its
relatively low power output, the low duty cycle, directionality, and
the brief period when an individual mammal is likely to be within its
beam. Furthermore, in the case of baleen whales, the sonar signals do
not overlap with the predominant frequencies in the animals' calls,
which would avoid significant masking.
Behavioral Responses Resulting from Sub-bottom Profiler Signals
Marine mammal behavioral reactions to pulsed sound sources and
responses to the sub-bottom profiler are likely to be similar to those
of other pulsed sources at the same received levels. However, the
pulsed signals from the sub-bottom profiler are much weaker than those
from the airgun array and the multi-beam sonar. Therefore behavioral
responses rising to Level B harassment are not expected unless marine
mammals are very close to the source, e.g. within about 160 m (525 ft)
below the vessel, or a lesser distance to the side. Because simple
momentary behavioral reactions that are within normal behavioral
patterns for that species are not considered to be a taking, the very
brief exposure of cetaceans to signals from the sub-bottom profiler is
unlikely to result in a ``take'' by harassment.
Hearing Impairment and Other Physical Effects
Source levels of the sub-bottom profiler are much lower than those
of the airguns and the multi-beam sonar that will be used during the
planned project. Furthermore, received levels of pulsed sounds that are
necessary to cause temporary or permanent hearing impairment in marine
mammals appear to be higher than 180 dB. Thus, it is unlikely that the
sub-bottom profiler produces pulse levels strong enough to cause
hearing impairment or other physical injuries even in an animal that is
briefly in a position immediately adjacent to the source.
Furthermore, the sub-bottom profiler is usually operated
simultaneously with other higher-power acoustic sources. Many marine
mammals will move away in response to the approaching higher-power
sources before the mammals would be close enough to be affected by the
less intense sounds from the sub-bottom profiler. In the event that
mammals do not avoid the approaching vessel and its various sound
sources, mitigation measures that would be applied to minimize effects
of the higher-power sources (discussed later in this document) would
further reduce or eliminate any minor effects of the sub-bottom
profiler.
Estimates of Take by Harassment for the two Mid-Atlantic Cruises
As described previously (68 FR 17909, April 14 2003), animals
subjected to sound levels £160 dB may alter their behavior or
distribution, and therefore might be considered to be taken by Level B
harassment. However, the 160-dB criterion is based on studies of baleen
whales (mysticetes), which are low frequency hearing specialists. In
contrast, odontocete hearing at low frequencies is relatively
insensitive, and dolphins and pilot whales generally appear to be more
tolerant of strong sounds than are most baleen whales. Delphinidae have
their best hearing in the higher frequencies and are unlikely to be as
sensitive as the mysticete whales to the low frequency of the airgun
array. Therefore, LDEO believes they are less likely to experience
Level B harassment at 160 dB, and a more likely threshold for onset of
Level B harassment in response to seismic sounds is at about 170 dB.
The estimates of takes by harassment are based on the number of
marine mammals that may be exposed to seismic sounds [gteqt]160 dB re 1
microPa (rms) by operations with the 20-airgun array and the 2 GI guns,
during the TAG and ADWBC cruises, respectively. Based on marine mammal
density sightings and effort data collected during a survey of offshore
waters northeast of the Azores by Lens (1991), LDEO used their
estimates of marine mammal density to compute the best (and maximum)
estimates of the number of marine mammals that may be exposed to
received levels [gteqt]160-dB re 1 microPa (rms) (NMFS' current
criterion for onset of Level B harassment). The best estimates of
densities were then multiplied by the linear extent of the proposed
survey effort and by twice the 160 dB radius around the applicable
airgun array. The proposed survey effort is 185 km (100 n.mi.) for the
TAG cruise, and 4329 km (2340 n.mi.) for the ADWBC cruise. The 160-dB
radius for the TAG cruise (20-gun array) is 9000 m (29,529 ft), whereas
that for the ADWBC cruise (2 GI guns) is 510 m (1673 ft). For large
cetaceans, LDEO used 0.5x the densities seen during the Lens (1991)
survey to calculate the numbers that might be exposed to seismic
sounds, but even this reduced number is likely a high estimate, because
the proposed survey areas are likely less productive, so feeding
aggregations similar to those seen by Lens (1991) are not likely to be
seen. In particular, the two areas where the proposed surveys will be
conducted are farther offshore and likely in less productive waters
than the area surveys northeast of the Azores (Lens 1991). Thus,
densities are likely to be much lower in the two proposed survey areas
than in the Lens (1991) survey area.
Based on this method, tables 3 and 4 of LDEO's application give the
best estimates, as well as maximum estimates, of densities for each
species or species group of cetacean in the proposed seismic survey
areas during the TAG and ADWBC cruises, respectively, that might be
exposed to received levels [gteqt]160 dB re 1 microPa (rms), and thus
potentially taken by Level B harassment, during seismic surveys in the
proposed study areas of the Mid-Atlantic Ocean. During the TAG cruise,
38 of the marine mammals exposed to sounds [gteqt]160 dB re 1 microPa
(rms) would be endangered species, primarily fin (18) and sperm whales
(15). During the ADWBC cruise, 49 of the marine mammals exposed to
sounds [gteqt]160 dB re 1 microPa (rms) would be endangered
[[Page 54426]]
species, primarily fin (24) and sperm whales (20). During both research
cruises, Delphinidae would account for 92 percent of the overall
estimate for potential taking by harassment during each of the proposed
seismic surveys (i.e., 709 of 772 (TAG) and 943 of 1028 (ADWBC)). While
there is no agreement regarding any alternative ``take'' criterion for
dolphins exposed to airgun pulses, if only those dolphins exposed to
[gteqt]170 dB re 1 microPa (rms) were to be affected sufficiently to be
considered taken by Level B harassment, then the best estimate for
common dolphins (the most abundant dolphin in the area) would be 91
rather than 316 during the TAG cruise, and 144 rather than 419 during
the ADWBC cruise. These are based on the predicted 170-dB radius around
the 20- and 2-airgun arrays (2600 and 175 m (8530 and 574 ft),
respectively), and are considered to be more realistic estimates of the
number of each species of delphinid that may be disturbed. Therefore,
the total number of animals likely to react behaviorally is
considerably lower than the 772 (TAG cruise) or 1028 (ADWBC cruise)
animals that LDEO has estimated in Table 3 and 4 (LDEO Mid-Atlantic,
2003).
Conclusions-Effects on Cetaceans
Strong avoidance reactions by several species of mysticetes to
seismic vessels have been observed at ranges up to 6 to 8 km (3.2 to
4.3 nm) and occasionally as far as 20-30 km (10.8-16.2 nm) from the
source vessel. Some bowhead whales avoided waters within 30 km (16.2
nm) of the seismic operation. However, reactions at such long distances
appear to be atypical of other species of mysticetes, and even for
bowheads may only apply during migration.
Odontocete reactions to seismic pulses, or at least those of
dolphins, are expected to extend to lesser distances than are those of
mysticetes. Odontocete low-frequency hearing is less sensitive than
that of mysticetes, and dolphins are often seen from seismic vessels.
In fact, there are documented instances of dolphins approaching active
seismic vessels. However, dolphins as well as some other types of
odontocetes sometimes show avoidance responses and/or other changes in
behavior when near operating seismic vessels.
Taking account of the mitigation measures that are planned, effects
on cetaceans are generally expected to be limited to avoidance of the
area around the seismic operation and short-term changes in behavior,
falling within the MMPA definition of ``Level B harassment.'' In the
cases of mysticetes, these reactions are expected to involve small
numbers of individual cetaceans because few mysticetes occur in the
area where seismic surveys are proposed. For Bryde's whales, LDEO's
best estimate is that 1 animal during each of the cruises, which
translates to 3 percent of the North Atlantic population for this
species in the area of the TAG survey, and 1.5 percent of the North
Atlantic population for this species in the area of the ADWBC survey,
has the potential to be exposed to sound levels [gteqt]160 dB re 1
microPa (rms) and potentially affected. LDEO's best estimate is that 18
(TAG) and 24 (ADWBC) fin whales, both of which are <0.1 percent of the
estimated North Atlantic fin whale population (IWC 2003), will be
exposed to sound levels <160 dB re 1 microPa (rms) and potentially
affected. Similarly, only 15 (TAG) and 20 (ADWBC) sperm whales, or
approximately 0.1 and 0.2 percent of the estimated North Atlantic sperm
whale population would receive seismic sounds [gteqt]160 dB. Therefore,
based on the relatively low numbers of marine mammals that will be
exposed at levels [gteqt]160 dB and the expected impacts at these
levels, NMFS has preliminarily determined that this action will have a
negligible impact on the affected species or stocks.
Larger numbers of odontocetes may be affected by the proposed
activities, but the populations sizes of the main species are large and
the numbers potentially affected are small relative to the population
sizes. The best estimate of the total number of odontocetes that might
be exposed to [gteqt]160 dB re 1 microPa (rms) in the proposed survey
areas in the Mid-Atlantic Ocean is 746 for the TAG cruise, and 991 for
the ADWBC cruise. Of these, 709 (TAG cruise) and 943 (ADWBC cruise) are
Delphinidae, and of these about 204 (TAG cruise) and 322 (ADWBC cruise)
might be exposed to [gteqt]170 dB. Only 316 and 419 common dolphins
(the most abundant delphinid in the proposed survey areas) are expected
to be exposed to seismic sounds [gteqt]160 dB in the proposed TAG and
ADWBC seismic survey areas, respectively. This represents considerably
less than 0.2 and 0.3 percent of the North Atlantic population of
common dolphins. Of these, 91 and 144, respectively, might be exposed
to [gteqt]170 dB. These figures are much less than 0.1 percent of the
North Atlantic population and the 170-dB values (91 and 144) are
believed to be a more accurate estimate of the number potentially
affected. Smaller numbers of other species of dolphins will be exposed
to seismic sounds [gteqt]160 dB during the proposed surveys, and the
numbers for each species represent considerably less than 0.1 to 0.7
percent of each population. The numbers that might be exposed to
[gteqt]170 dB are even smaller and represent considerably less than 0.1
to 0.2 percent of each population; these latter percentages are
believed to be a more accurate estimate of the numbers potentially
affected. Based on the relatively low numbers of marine mammals that
will be exposed at levels [gteqt]160 dB and the expected impacts at
these levels, NMFS has preliminarily determined that this action will
have a negligible impact on the affected species or stocks.
Altogether, proposed mitigation measures such as controlled speed,
course alteration, look-outs, non-pursuit, ramp-ups, and power-downs
when marine mammals are seen within defined ranges (See Mitigation)
will reduce short-term reactions to disturbance, and minimize any
effects on hearing sensitivity.
Conclusions-Effects on Pinnipeds
Very few if any pinnipeds are expected to be encountered during the
proposed seismic surveys in the Mid-Atlantic Ocean. Most have a coastal
distribution or are distributed along the pack-ice edge. Therefore, it
is unlikely that pinnipeds will be encountered in either study area.
However, if pinnipeds are encountered, they are more likely to be seen
during the ADWBC cruise in the northern Mid-Atlantic than during the
TAG cruise. A few gray seals, which are normally found in coastal areas
might be seen during the ADWBC cruise. In addition, a few vagrant
harbor seals, harp seals, or hooded seals might be encountered. None of
the pinniped species is considered endangered or vulnerable.
Because no seismic surveys will take place in coastal and nearshore
areas, the best estimate of the numbers of each of the more common (but
unlikely) species that might be taken by Level B harassment is no more
than 2 and is most likely 0. For the other less-common species the best
estimate is zero. If pinnipeds are encountered, the proposed seismic
activities would have, at most, a short-term effect on their behavior
and no long-term impacts on individual seals or their populations.
Responses of pinnipeds to acoustic disturbance are variable, but
usually quite limited. Effects are expected to be limited to short-term
and localized behavioral changes falling within the MMPA definition of
Level B harassment. Therefore, based on the relatively low numbers of
marine mammals that will be exposed, NMFS has preliminarily determined
that this
[[Page 54427]]
action will have a negligible impact on the affected species or stocks.
Mitigation
For the proposed TAG seismic survey, LDEO will use a 20-gun array
with a total volume of 8575 in\3\. Individual airguns will range in
size from 80 to 850 in3. For the ADWBC cruise, LDEO will use 2 GI guns
with a total volume of 210 in\3\. The airguns comprising these arrays
will be spread out horizontally, so that the energy from the arrays
will be directed mostly downward.
The sound pressure fields were modeled by LDEO in relation to
distance and direction from the 2 GI guns and the 20-gun array, as
shown in Figures 5 and 6 (LDEO Mid-Atlantic, 2003). The radii around
the arrays where the received level would be 180-dB re 1 microPa (rms)
(NMFS' threshold level for onset of Level A harassment applicable to
cetaceans) were estimated as 54 m (177 ft) and 900 m (2953 ft),
respectively, for the 2-GI and 20-gun array. The radii around the 2 GI
guns and the 20-gun array where the received level would be 190 dB re 1
microPa (rms), (NMFS' threshold level for onset of Level A harassment
applicable to pinnipeds), were estimated as 17 m (56 ft) and 275 m (902
ft), respectively. A calibration study was conducted prior to these
surveys to determine the actual radii corresponding to each sound
level. These actual radii will be used to define the safety radii to be
used for this study. Until then, or if those measurements appear
defective, LDEO will use a precautionary 1.5 times the modeled 180-
(cetaceans) and 190- (pinnipeds) dB radii as the safety radii.
Vessel-based observers will monitor marine mammals in the vicinity
of the arrays. LDEO proposes to power-down the airguns if marine
mammals are observed within the proposed safety radii. Also, LDEO
proposes to use a ramp-up procedure when commencing operations using
the 20-gun array. Ramp-up will begin with the smallest gun in the array
(80 in3), and guns will be added in a sequence such that the source
level of the array will increase at a rate no greater than 6 dB per 5-
minute period over a total duration of about 25 minutes. Ramp-up will
not occur for the 2-GI gun array because the total air discharge volume
is small (210 in3). Please refer to LDEO's application for more
detailed information about the mitigation measures that are an integral
part of the planned activity.
The directional nature of the 6-airgun array to be used in this
project is an important mitigating factor, resulting in lower sound
levels at any given horizontal distance than would be expected at that
distance if the source were omnidirectional with the stated nominal
source level. Because the actual seismic source is a distributed sound
source (2 or 20 guns) rather than a single point source, the highest
sound levels measurable at any location in the water will be less than
the nominal source level.
Marine Mammal Monitoring
At least two vessel-based observers will be stationed aboard LDEO's
seismic survey vessel during seismic operations in the Mid-Atlantic
Ocean. It is proposed that one or two marine mammal observers aboard
the seismic vessel will search for and observe marine mammals whenever
seismic operations are in progress during daylight hours, and if
feasible, during periods without seismic activity. Vessel-based
observers will monitor for marine mammals near the seismic source
vessel for at least 30 minutes prior to and during all daylight ramp-up
and airgun operations, and during any nighttime startups of the
airguns. Airgun operations will be suspended when marine mammals are
observed within, or about to enter, the designated safety radii.
Observers will not be on duty during ongoing seismic operations at
night; bridge personnel will watch for marine mammals during this
period and will call for the airguns to be powered down if marine
mammals are observed in or about to enter the safety radii. At least
one marine mammal observer will be on ``standby'' at night, in case
bridge personnel see a marine mammal. An image-intensifier night-vision
device (NVD) will be available for use at night. If the airguns are
started up at night, two marine mammal observers will monitor for
marine mammals near the source vessel for 30 minutes prior to start up
using NVDs. The 30-minute observation period is only required prior to
commencing seismic operations following an extended shut down period.
After 30 minutes of observation, the ramp-up procedure will be
followed.
The observers will watch for marine mammals from the highest
practical vantage point on the vessel, which is either the flying
bridge or the bridge. On the R/V Maurice Ewing, the observer's eye
level will be approximately 11 m (36 ft) above sea level when stationed
on the bridge, allowing for good visibility within a 210[deg]
arc. If
observers are stationed on the flying bridge, the eye level will be
14.4 m (47.2 ft) above sea level. The proposed monitoring plan is
summarized later in this document.
Mitigation During Operations
The following mitigation measures, as well as marine mammal
monitoring, will be adopted during the proposed Mid-Atlantic seismic
surveys, provided that doing so will not compromise operational safety
requirements: (1) Speed or course alteration; (2) Power-down
procedures; (3) Shut-down procedures; and (4) Ramp-up procedures.
Course Alteration
If a marine mammal is detected outside the safety radius and, based
on its position and the relative motion, is likely to enter the safety
radius, the vessel's speed and/or direct course will be changed in a
manner that also minimizes the effect to the planned science
objectives. The marine mammal activities and movements relative to the
seismic vessel will be closely monitored to ensure that the marine
mammal does not approach within the safety radius. If the mammal
appears likely to enter the safety radius, further mitigative actions
will be taken, i.e., either further course alterations or shutdown of
the airguns.
Power-down and Shut-down Procedures
Received sound levels have been modeled for the 2-GI and 20-gun
arrays. Based on the modeling, estimates of the 190-, 180-, 170-, and
160-dB re 1 microPa (rms) distances (safety radii) for these arrays
have been provided previously in this document.
Airgun operations will be powered-down (or shut-down) immediately
when cetaceans or pinnipeds are seen within or about to enter the
appropriate 180-dB (rms) or 190-dB (rms) radius, respectively. These
180- and 190-dB criteria are consistent with guidelines listed for
cetaceans and pinnipeds by NMFS (2000) and other guidance by NMFS. If a
marine mammal is detected outside the safety radius but is likely to
enter the safety radius, and if the vessel's course and/or speed cannot
be changed to avoid having the marine mammal enter the safety radius,
the airguns will be powered-down before the mammal is within the safety
radius. Likewise, if a mammal is already within the safety radius when
first detected, the airguns will be powered-down immediately. If a
marine mammal is seen within the appropriate safety radius of the array
while the guns are powered-down, airgun operations will be shut-down.
For the power-down procedure for the 20-gun array, one 80 in\3\ airgun
will be operated during the interruption of seismic survey. When the 2
GI guns are in use, a shut-down
[[Page 54428]]
rather than a power-down will likely be necessary. Airgun activity
(after both power-down and shut-down procedures) will not resume until
the marine mammal has cleared the safety radius. The animal has cleared
the safety radius if it is visually observed to have left the safety
radius, or if it has not been seen within the zone for 15 min (small
odontocetes and pinnipeds) or 30 min (mysticetes and large odontocetes,
including sperm, pygmy sperm, dwarf sperm, beaked, and bottlenose
whales).
Ramp-up Procedure
A ``ramp-up'' procedure will be followed when the airgun arrays
begin operating after a specified duration without airgun operations.
Under normal operational conditions (vessel speed 4 knots, or 7.4 km/
hr), a ramp-up would be required after a power-down or shut-down period
lasting about 8 minutes or longer if the Ewing was towing the 20-gun
array. At 4 knots, the source vessel would travel 900 m (2953 ft)
during an 8-minute period. If the towing speed is reduced to 3 knots or
less, as sometimes required when maneuvering in shallow water, it is
proposed that a ramp-up would be required after a ``no shooting''
period lasting 10 minutes or longer. At towing speeds not exceeding 3
knots, the source vessel would travel no more than 900 m (3117 ft) in
10 minutes. Based on the same calculation, a ramp-up procedure would be
required after a 6 minute period if the speed of the source vessel was
5 knots. During the ramp-up procedures, the safety radii for the full
gun array will be maintained.
Ramp-up will not occur if the safety radius has not been visible
for at least 30 min prior to the start of operations in either daylight
or nighttime. If the safety radius has not been visible for that 30
minute period (e.g., during darkness or fog), ramp-up will not commence
unless one airgun with a sound pressure level (SPL) of at least 180 dB
has been maintained during the interruption of seismic activity.
Therefore, it is likely that the 20-gun array will not be ramped up
from a shut-down at night or in thick fog, since the safety radii for
this array will not be visible during those conditions.
Monitoring and Reporting
LDEO proposes to conduct marine mammal monitoring of its 2003 Mid-
Atlantic seismic programs in order to satisfy the anticipated
requirements of the IHA.
Vessel-based Visual Monitoring
The observer(s) will systematically scan the area around the vessel
with reticle binoculars (e.g., 7 X 50 Fujinon) and with the naked eye
during the daytime. At night, NVDs will be available (ITT F500 Series
Generation 3 binocular image intensifier or equivalent). Laser
rangefinding binoculars (Leica LRF 1200 laser rangefinder or
equivalent) will be available to assist with distance estimation.
At least two observers will be based aboard the vessel, and at
least one will be an experienced marine mammal observer. Observers will
be appointed by LDEO with NMFS concurrence. Observers will be on duty
in shifts of duration no longer than 4 hours. The second observer will
also be on watch part of the time, including the 30 minute periods
preceding startup of the airguns and during ramp-ups. Use of two
simultaneous observers will increase the proportion of the marine
mammals present near the source vessel that are detected. LDEO bridge
personnel additional to the dedicated marine mammal observers will also
assist in detecting marine mammals and implementing mitigation
requirements whenever possible (they will be given instruction on how
to do so), especially during ongoing operations at night, when
designated observers will not be on duty. If ramp-up procedures must be
performed at night, two observers will be on duty 30 minutes prior to
the start of airgun operations and during the subsequent ramp-up
procedures. Ramp-up is not required for the 2 GI gun array, but
observers must watch for 30 minutes prior to operation of the 2 GI guns
and the safety radii must be visible.
Reporting
The vessel-based monitoring will provide data required to estimate
the numbers of marine mammals exposed to various received sound levels,
to document any apparent disturbance reactions, and thus to estimate
the numbers of mammals potentially taken by Level B harassment. It will
also provide the information needed in order to shut down the airguns
at times when mammals are present in or near the safety zones. When a
mammal sighting is made, the following information about the sighting
will be recorded: (1) Species, group size, age/size/sex categories (if
determinable), behavior when first sighted and after initial sighting,
heading (if consistent), bearing and distance from seismic vessel,
sighting cue, apparent reaction to seismic vessel (e.g., none,
avoidance, approach, paralleling, etc.), and behavioral pace; and (2)
time, location, heading, speed, activity of the vessel (shooting or
not), sea state, visibility, cloud cover, and sun glare. The data
listed under (2) will also be recorded at the start and end of each
observation watch and during a watch, whenever there is a change in one
or more of the variables.
All mammal observations and airgun power- and shut-downs will be
recorded in a standardized format. Data will be entered into a custom
database using a laptop computer when observers are off-duty. The
accuracy of the data entry will be verified by computerized validity
data checks as the data are entered and by subsequent manual checking
of the database. These procedures will allow initial summaries of data
to be prepared during and shortly after the field program, and will
facilitate transfer of the data to statistical, graphical or other
programs for further processing and archiving.
Results from the vessel-based observations will provide (1) the
basis for real-time mitigation (airgun power-down or shut-down); (2)
information needed to estimate the number of marine mammals potentially
taken by harassment, which must be reported to NMFS; (3) data on the
occurrence, distribution, and activities of marine mammals in the area
where the seismic study is conducted; (4) information to compare the
distance and distribution of marine mammals relative to the source
vessel at times with and without seismic activity; and (5) data on the
behavior and movement patterns of marine mammals seen at times with and
without seismic activity.
A report will be submitted to NMFS within 90 days after the end of
each cruise in the Mid-Atlantic Ocean. The end of the TAG cruise is
predicted to occur on or about October 30, 2003. The end of the ADWBC
cruise is unknown at this time. The report will describe the operations
that were conducted and the marine mammals that were detected. The
report will be submitted to NMFS, providing full documentation of
methods, results, and interpretation pertaining to all monitoring
tasks. The 90-day report will summarize the dates and locations of
seismic operations, marine mammal sightings (dates, times, locations,
activities, associated seismic survey activities), and estimates of the
amount and nature of potential take of marine mammals by harassment or
in other ways. The draft report will be considered the final report
unless comments and suggestions are provided by NMFS within 60 days of
its receipt of the draft report.
[[Page 54429]]
Endangered Species Act (ESA)
Under section 7 of the ESA, NMFS has begun consultation on the
proposed issuance of an IHA under section 101(a)(5)(D) of the MMPA for
this activity. Consultation will be concluded prior to the issuance of
an IHA.
National Environmental Policy Act (NEPA)
The NSF has prepared an Environmental Assessment (EA) for the two
Mid-Atlantic surveys. NMFS is reviewing this EA and will either adopt
it or prepare its own NEPA document before making a determination on
the issuance of an IHA. A copy of the NSF EA for this activity is
available upon request (see ADDRESSES).
Preliminary Conclusions
NMFS has preliminarily determined that the impact of conducting two
seismic surveys in the Mid-Atlantic Ocean will result, at worst, in a
temporary modification in behavior by certain species of marine
mammals. This activity is expected to result in no more than a
negligible impact on the affected species.
While the number of potential incidental harassment takes will
depend on the distribution and abundance of marine mammals in the
vicinity of the survey activity, the number of potential harassment
takings is estimated to be small. In addition, no take by injury and/or
death is anticipated, and the potential for temporary or permanent
hearing impairment is low and will be avoided through the incorporation
of the mitigation measures mentioned in this document. In addition, the
proposed seismic program is not expected to interfere with any
subsistence hunts, since operations in the whaling and sealing areas
will be limited.
Proposed Authorization
NMFS proposes to issue an IHA to LDEO for conducting two seismic
surveys in the Mid-Atlantic Ocean, provided the previously mentioned
mitigation, monitoring, and reporting requirements are incorporated.
NMFS has preliminarily determined that the proposed activity would
result in the harassment of small numbers of marine mammals; would have
no more than a negligible impact on the affected marine mammal stocks;
and would not have an unmitigable adverse impact on the availability of
stocks for subsistence uses.
Information Solicited
NMFS requests interested persons to submit comments and information
concerning this request (see ADDRESSES).
Dated: September 11, 2003.
Laurie K. Allen,
Acting Director, Office of Protected Resources, National Marine
Fisheries Service.
[FR Doc. 03-23766 Filed 9-16-03; 8:45 am]
BILLING CODE 3510-22-S