[Federal Register Volume 78, Number 55 (Thursday, March 21, 2013)]
[Notices]
[Pages 17359-17383]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2013-06504]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
RIN 0648-XC461
Takes of Marine Mammals Incidental to Specified Activities;
Marine Geophysical Survey in the Northeast Atlantic Ocean, June to
July, 2013
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice; proposed Incidental Harassment Authorization; request
for comments.
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SUMMARY: NMFS has received an application from the Lamont-Doherty Earth
Observatory of Columbia University (L-DEO) for an Incidental Harassment
Authorization (IHA) to take marine mammals, by harassment, incidental
to conducting a marine geophysical (seismic) survey in the northeast
Atlantic Ocean, June to July, 2013. Pursuant to the Marine Mammal
Protection Act (MMPA), NMFS is requesting comments on its proposal to
issue an IHA to L-DEO to incidentally harass, by Level B harassment
only, 20 species of marine mammals during the specified activity.
DATES: Comments and information must be received no later than April
22, 2013.
ADDRESSES: Comments on the application should be addressed to P.
Michael Payne, Chief, Permits and Conservation Division, Office of
Protected Resources, National Marine Fisheries Service, 1315 East-West
Highway, Silver Spring, MD 20910. The mailbox address for providing
email comments is [email protected]. Please include 0648-XC461 in
the subject line. NMFS is not responsible for email comments sent to
addresses other than the one provided here. Comments sent via email,
including all attachments, must not exceed a 10-megabyte file size.
All comments received are a part of the public record and will
generally be posted to http://www.nmfs.noaa.gov/pr/permits/incidental.htm#applications without change. All Personal Identifying
Information (for example, name, address, etc.) voluntarily submitted by
the commenter may be publicly accessible. Do not submit confidential
business information or otherwise sensitive or protected information.
A copy of the application containing a list of the references used
in this document may be obtained by writing to the above address,
telephoning the
[[Page 17360]]
contact listed here (see FOR FURTHER INFORMATION CONTACT) or visiting
the Internet at: http://www.nmfs.noaa.gov/pr/permits/incidental.htm#applications.
The National Science Foundation (NSF), which owns the R/V Marcus G.
Langseth, has prepared a draft ``Environmental Analysis of a Marine
Geophysical Survey by the R/V Marcus G. Langseth for the Northeast
Atlantic Ocean, June-July 2013,'' prepared by LGL Ltd., Environmental
Research Associates, on behalf of NSF and L-DEO, which is also
available at the same Internet address. Documents cited in this notice
may be viewed, by appointment, during regular business hours, at the
aforementioned address.
FOR FURTHER INFORMATION CONTACT: Howard Goldstein or Jolie Harrison,
Office of Protected Resources, NMFS, 301-427-8401.
SUPPLEMENTARY INFORMATION:
Background
Section 101(a)(5)(D) of the MMPA, as amended (16 U.S.C. 1371
(a)(5)(D)), directs the Secretary of Commerce (Secretary) to authorize,
upon request, the incidental, but not intentional, taking of small
numbers of marine mammals of a species or population stock, by United
States citizens who engage in a specified activity (other than
commercial fishing) within a specified geographical region if certain
findings are made and, if the taking is limited to harassment, a notice
of a proposed authorization is provided to the public for review.
Authorization for the incidental taking of small numbers of marine
mammals shall 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 (where relevant). The authorization must
set forth the permissible methods of taking, other means of effecting
the least practicable adverse impact on the species or stock and its
habitat, and requirements pertaining to the mitigation, monitoring and
reporting of such takings. NMFS has defined ``negligible impact'' in 50
CFR 216.103 as ``[hellip]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.''
Section 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.
Section 101(a)(5)(D) of the MMPA establishes a 45-day time limit for
NMFS's review of an application followed by a 30-day public notice and
comment period on any proposed authorizations for the incidental
harassment of small numbers of marine mammals. Within 45 days of the
close of the public comment period, NMFS must either issue or deny the
authorization.
Except with respect to certain activities not pertinent here, 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 [Level A harassment]; 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 [Level B harassment].
Summary of Request
On January 8, 2013, NMFS received an application from the L-DEO
requesting that NMFS issue an IHA for the take, by Level B harassment
only, of small numbers of marine mammals incidental to conducting a
marine seismic survey on the high seas (i.e., International Waters) and
within the Exclusive Economic Zone of Spain during June to July, 2013.
L-DEO plan to use one source vessel, the R/V Marcus G. Langseth
(Langseth) and a seismic airgun array to collect seismic data as part
of the proposed seismic survey in the northeast Atlantic Ocean.
In addition to the proposed operations of the seismic airgun array
and hydrophone streamer, L-DEO intends to operate a multibeam
echosounder and a sub-bottom profiler continuously throughout the
survey.
Acoustic stimuli (i.e., increased underwater sound) generated
during the operation of the seismic airgun array may have the potential
to cause a behavioral disturbance for marine mammals in the survey
area. This is the principal means of marine mammal taking associated
with these activities and L-DEO has requested an authorization to take
20 species of marine mammals by Level B harassment. Take is not
expected to result from the use of the multibeam echosounder or sub-
bottom profiler, for reasons discussed in this notice; nor is take
expected to result from collision with the source vessel because it is
a single vessel moving at a relatively slow speed (4.6 knots [kts]; 8.5
kilometers per hour [km/hr]; 5.3 miles per hour [mph]) during seismic
acquisition within the survey, for a relatively short period of time
(approximately 39 days). It is likely that any marine mammal would be
able to avoid the vessel.
Description of the Proposed Specified Activity
L-DEO proposes to conduct a high energy, two-dimensional (2D) and
three-dimensional (3D) seismic survey in the northeast Atlantic Ocean,
west of Spain (see Figure 1 of the IHA application). Water depths in
the survey area range from approximately 3,500 to greater than 5,000
meters (m) (11,482.9 to 16,404.2 feet [ft]). The proposed seismic
survey would be scheduled to occur for approximately 39 days during
June 1 to July 14, 2013. Some minor deviation from these dates would be
possible, depending on logistics and weather.
L-DEO plans to use conventional seismic methodology in the Deep
Galicia Basin of the northeast Atlantic Ocean. The goal of the proposed
research is to collect data necessary to study rifted continental to
oceanic crust transition in the Deep Galicia Basin west of Spain. This
margin and its conjugate are among the best studied magma-poor, rifted
margins in the world, and the focus of studies has been the faulting
mechanics and modification of the upper mantle associated with such
margins. Over the years, a combination of 2D reflection profiling,
general marine geophysics, and ocean drilling have identified a number
of interesting features of the margin. Among these are the S reflector,
which has been interpreted to be detachment fault overlain with fault
bounded, rotated, continental crustal blocks and underlain by
serpentinized peridotite, and the Peridotite Ridge, composed of
serpentized peridotite and thought to be upper mantle exhumed to the
seafloor during rifting.
To achieve the project's goals, the Principal Investigators (PIs),
Drs. D. S. Sawyer (Rice University, J. K. Morgan (Rice University), and
D. J. Shillington (L-DEO) propose to use a 3D seismic reflection
survey, 2D survey, and a long-offset seismic program extending through
the crust and S detachment into the upper mantle to characterize the
last stage of continental breakup and the initiation of seafloor
spreading, relate post-rifting subsidence to syn-rifting lithosphere
deformation, and inform the nature of detachment faults. Ocean Bottom
Seismometers (OBSs) and Ocean Bottom Hydrophones (OBHs) would also be
deployed during the program. It is a cooperative program with
scientists from the United Kingdom, Germany, Spain, and Portugal.
[[Page 17361]]
The proposed survey would involve one source vessel, the R/V Marcus
G. Langseth (Langseth). The Langseth would deploy an array of 18
airguns as an energy source with a total volume of approximately 3,300
in\3\. The receiving system would consist of four 6,000 m (19,685 ft)
hydrophone streamers at 200 m (656.2 ft) spacing and up to 78 OBS and
OBH instruments. The OBSs and OBHs would be deployed and retrieved by a
second vessel, the R/V Poseidon (Poseidon), provided by the German
Science Foundation. As the airgun array is towed along the survey
lines, the hydrophone streamers would receive the returning acoustic
signals and transfer the data to the on-board processing system. The
OBS and OBHs record the returning acoustic signals internally for later
analysis.
A total of approximately 5,834 km (3150.1 nmi) of survey lines,
including turns, will be shot in a grid pattern with a single line
extending to the west (see Figure 1). There will be additional seismic
operations in the survey area associated with equipment testing, ramp-
up, and possible line changes or repeat coverage of any areas where
initial data quality is sub-standard. In L-DEO's estimated take
calculations, 25% has been added for those additional operations.
In addition to the operations of the airgun array, a Kongsberg EM
122 multibeam echosounder and a Knudsen Chirp 3260 sub-bottom profiler
will also be operated from the Langseth continuously throughout the
survey. All planned geophysical data acquisition activities would be
conducted by L-DEO with on-board assistance by the scientists who have
proposed the study. The vessel will be self-contained, and the crew
will live aboard the vessel for the entire cruise.
Vessel Specifications
The Langseth, a seismic research vessel owned by the NSF, will tow
the 36 airgun array, as well as the hydrophone streamer(s), along
predetermined lines (see Figure 1 of the IHA application). When the
Langseth is towing the airgun array and the hydrophone streamer(s), the
turning rate of the vessel is limited to three degrees per minute (2.5
km [1.5 mi]). Thus, the maneuverability of the vessel is limited during
operations with the streamer. The vessel would ``fly'' the appropriate
U.S. Coast Guard-approved day shapes (mast head signals used to
communicate with other vessels) and display the appropriate lighting to
designate the vessel has limited maneuverability.
The vessel has a length of 71.5 m (235 ft); a beam of 17.0 m (56
ft); a maximum draft of 5.9 m (19 ft); and a gross tonnage of 3,834.
The Langseth was designed as a seismic research vessel with a
propulsion system designed to be as quiet as possible to avoid
interference with the seismic signals emanating from the airgun array.
The ship is powered by two 3,550 horsepower (hp) Bergen BRG-6 diesel
engines which drive two propellers directly. Each propeller has four
blades and the shaft typically rotates at 750 revolutions per minute.
The vessel also has an 800 hp bowthruster, which is not used during
seismic acquisition. The Langseth's operation speed during seismic
acquisition is typically 7.4 to 9.3 km per hour (hr) (km/hr) (4 to 5
knots [kts]). When not towing seismic survey gear, the Langseth
typically cruises at 18.5 km/hr (10 kts). The Langseth has a range of
25,000 km (13,499 nmi) (the distance the vessel can travel without
refueling).
The vessel also has an observation tower from which Protected
Species Visual Observers (PSVO) will watch for marine mammals before
and during the proposed airgun operations. When stationed on the
observation platform, the PSVO's eye level will be approximately 21.5 m
(71 ft) above sea level providing the PSVO an unobstructed view around
the entire vessel. More details of the Langseth can be found in the IHA
application and NSF/USGS PEIS.
The Poseidon is a German-flagged vessel, owned by the Federal State
of Schleswig-Holstein and operated by Briese Schiffahrts GmbH &Co. KG.
The Poseidon has a length of 60.8 m (199.5 ft), a beam of 11.4 m (37.4
ft), and a maximum draft of 4.7 m (15.4 ft). The ship is powered by
diesel-electric propulsion. The traction motor produces 930 kW and
drives one propeller directly. The propeller has five blades, and the
shaft typically rotates at 220 revolutions per minute (rpm). The vessel
also has a 394 hp bowthruster, which would not be used during OBS/OBH
deployment and retrieval. The Poseidon typically cruises at 8.5 kt
(11.5 km/hr) and has a range of 7,408 km (4,000 nmi).
Acoustic Source Specifications
Seismic Airguns
The Langseth will deploy a 36-airgun array, consisting of two 18
airgun (plus 2 spares) sub-arrays. Each sub-array will have a volume of
approximately 3,300 cubic inches (in\3\). The airgun array will consist
of a mixture of Bolt 1500LL and Bolt 1900LLX airguns ranging in size
from 40 to 360 in\3\, with a firing pressure of 1,900 pounds per square
inch (psi). The 18 airgun sub-arrays will be configured as two
identical linear arrays or ``strings'' (see Figure 2.11 of the NSF/USGS
PEIS). Each string will have 10 airguns, the first and last airguns in
the strings are spaced 16 m (52.5 ft) apart. Of the 10 airguns, nine
airguns in each string will be fired simultaneously (1,650 in\3\),
whereas the tenth is kept in reserve as a spare, to be turned on in
case of failure of another airgun. The sub-arrays would be fired
alternately during the survey. The two airgun sub-arrays will be
distributed across an area of approximately 12 x 16 m (40 x 52.5 ft)
behind the Langseth and will be towed approximately 140 m (459.3 ft)
behind the vessel. Discharge intervals depend on both the ship's speed
and Two Way Travel Time recording intervals. The shot interval will be
37.5 m (123 ft) during the study. The shot interval will be relatively
short, approximately 15 to 20 seconds (s) based on an assumed boat
speed of 4.5 knots. During firing, a brief (approximately 0.1 s) pulse
sound is emitted; the airguns will be silent during the intervening
periods. The dominant frequency components range from two to 188 Hertz
(Hz).
The tow depth of the airgun array will be 9 m (29.5 ft) during the
surveys. Because the actual source is a distributed sound source (18
airguns) rather than a single point source, the highest sound
measurable at any location in the water will be less than the nominal
source level. In addition, the effective source level for sound
propagating in near-horizontal directions will be substantially lower
than the nominal omni-directional source level applicable to downward
propagation because of the directional nature of the sound from the
airgun array (i.e., sound is directed downward).
Hydrophone Streamer
Acoustic signals will be recorded using a system array of four
hydrophone streamers, which would be towed behind the Langseth. Each
streamer would consist of Sentry Solid Streamer Sercel cable
approximately 6 km (3.2 nmi) long. The streamers are attached by floats
to a diverter cable, which keeps the streamer spacing at approximately
100 to 150 m (328 to 492 ft) apart.
Seven hydrophones will be present along each streamer for acoustic
measurement. The hydrophones will consist of a mixture of Sonardyne
Transceivers. Each streamer will contain three groups of paired
hydrophones, with each group approximately 2,375 m (7,800 ft) apart.
The hydrophones within each group will be approximately 300 m (984 ft)
apart. One additional hydrophone will be located
[[Page 17362]]
on the tail buoy attached to the end of the streamer cable. In
addition, one Sonardyne Transducer will be attached to the airgun
array. Compass birds will be used to keep the streamer cables and
hydrophones at a depth of approximately 10 m (32.8 ft). One compass
bird will be placed at the front end of each streamer as well as
periodically along the streamer.
Metrics Used in This Document
This section includes a brief explanation of the sound measurements
frequently used in the discussions of acoustic effects in this
document. Sound pressure is the sound force per unit area, and is
usually measured in micropascals ([mu]Pa), where 1 pascal (Pa) is the
pressure resulting from a force of one newton exerted over an area of
one square meter. Sound pressure level (SPL) is expressed as the ratio
of a measured sound pressure and a reference level. The commonly used
reference pressure level in underwater acoustics is 1 [mu]Pa, and the
units for SPLs are dB re: 1 [mu]Pa. SPL (in decibels [dB]) = 20 log
(pressure/reference pressure).
SPL is an instantaneous measurement and can be expressed as the
peak, the peak-to-peak (p-p), or the root mean square (rms). Root mean
square (rms), which is the square root of the arithmetic average of the
squared instantaneous pressure values, is typically used in discussions
of the effects of sounds on vertebrates and all references to SPL in
this document refer to the root mean square unless otherwise noted. SPL
does not take the duration of a sound into account.
Characteristics of the Airgun Pulses
Airguns function by venting high-pressure air into the water which
creates an air bubble. The pressure signature of an individual airgun
consists of a sharp rise and then fall in pressure, followed by several
positive and negative pressure excursions caused by the oscillation of
the resulting air bubble. The oscillation of the air bubble transmits
sounds downward through the seafloor and the amount of sound
transmitted in the near horizontal directions is reduced. However, the
airgun array also emits sounds that travel horizontally toward non-
target areas.
The nominal source levels of the airgun arrays used by L-DEO on the
Langseth are 236 to 265 dB re 1 [mu]Pa (p-p) and the rms value for a
given airgun pulse is typically 16 dB re 1 [mu]Pa lower than the peak-
to-peak value (Greene, 1997; McCauley et al., 1998, 2000a). The
specific source output for the 18 airgun array is 252 dB (peak) and 259
dB (p-p). However, the difference between rms and peak or peak-to-peak
values for a given pulse depends on the frequency content and duration
of the pulse, among other factors.
Accordingly, L-DEO have predicted the received sound levels in
relation to distance and direction from the 18 airgun array and the
single Bolt 1900LL 40 in\3\ airgun, which will be used during power-
downs. A detailed description of L-DEO modeling for this survey's
marine seismic source arrays for protected species mitigation is
provided in the NSF/USGS PEIS (see Appendix H). NMFS refers the
reviewers to the IHA application and NSF/USGS PEIS documents for
additional information.
Predicted Sound Levels for the Airguns
Tolstoy et al. (2009) reported results for propagation measurements
of pulses from the Langseth's 36 airgun, 6,600 in\3\ array in shallow-
water (approximately 50 m [164 ft]) and deep water depths
(approximately 1,600 m [5,249 ft]) in the Gulf of Mexico in 2007 and
2008. Results of the Gulf of Mexico calibration study (Tolstoy et al.,
2009) showed that radii around the airguns for various received levels
varied with water depth and that sound propagation varied with array
tow depth.
The L-DEO used the results from the Gulf of Mexico study to
determine the algorithm for its model that calculates the mitigation
exclusion zones for the 36-airgun array and the single airgun. L-DEO
has used these calculated values to determine buffer (i.e., 160 dB) and
exclusion zones for the 18 airgun array and previously modeled
measurements by L-DEO for the single airgun, to designate exclusion
zones for purposes of mitigation, and to estimate take for marine
mammals in the northeast Atlantic Ocean. A detailed description of the
modeling effort is provided in the NSF/USGS PEIS.
Comparison of the Tolstoy et al. (2009) calibration study with the
L-DEO's model for the Langseth's 36-airgun array indicated that the
model represents the actual received levels, within the first few
kilometers and the locations of the predicted exclusion zones. However,
the model for deep water (greater than 1,000 m; 3,280 ft) overestimated
the received sound levels at a given distance but is still valid for
defining exclusion zones at various tow depths. Because the tow depth
of the array in the calibration study is less shallow (6 m [19.7 ft])
than the tow depths in the proposed survey (9 m [29.5 ft), L-DEO used
the following correction factors for estimating the received levels
during the proposed surveys (see Table 1). The correction factors are
the ratios of the 160, 180, and 190 dB distances from the modeled
results for the 6,600 in\3\ airgun arrays towed at 6 m (19.7 ft) versus
9, 12, or 15 m (29.5, 39.4, or 49.2 ft) (LGL, 2008).
For a single airgun, the tow depth has minimal effect on the
maximum near-field output and the shape of the frequency spectrum for
the single airgun; thus, the predicted exclusion zones are essentially
the same at different tow depths. The L-DEO's model does not allow for
bottom interactions, and thus is most directly applicable to deep
water.
Using the model (airgun array and single airgun), Table 1 (below)
shows the distances at which three rms sound levels are expected to be
received from the 18 airgun array and a single airgun. To avoid the
potential for injury or permanent physiological damage (Level A
harassment), NMFS's (1995, 2000) current practice is that cetaceans and
pinnipeds should not be exposed to pulsed underwater noise at received
levels exceeding 180 dB re: 1 [micro]Pa and 190 dB re: 1 [micro]Pa,
respectively. L-DEO used these levels to establish the proposed
exclusion zones. If marine mammals are detected within or about to
enter the appropriate exclusion zone, the airguns will be powered-down
(or shut-down, if necessary) immediately. NMFS also assumes that marine
mammals exposed to levels exceeding 160 dB re: 1 [micro]Pa may
experience Level B harassment.
Table 1 summarizes the predicted distances at which sound levels
(160, 180, and 190 dB [rms]) are expected to be received from the 18
airgun array and a single airgun operating in deep water depths.
[[Page 17363]]
Table 1--Measured (Array) or Predicted (Single Airgun) Distances to Which Sound Levels >=190, 180, and 160 dB
re: 1 [mu]Pa (rms) Could Be Received in Deep Water During the Proposed Survey in the Northeast Atlantic Ocean,
June to July, 2013
----------------------------------------------------------------------------------------------------------------
Predicted RMS radii distances
Water depth (m)
Sound source and volume Tow depth (m) (m) -------------------------------
180 dB 160 dB
----------------------------------------------------------------------------------------------------------------
Single Bolt airgun (40 in\3\)................... 9 >1,000 m 100 m 388 m
(328.1 ft) (1,273 ft)
18 airguns (3,300 in\3\)........................ 9 >1,000 m 1,116 m 6,908 m
(3,661.4 ft) (22,664 ft)
----------------------------------------------------------------------------------------------------------------
Along with the airgun operations, two additional acoustical data
acquisition systems will be operated from the Langseth continuously
during the survey. The ocean floor will be mapped with the Kongsberg EM
122 multibeam echosounder and a Knudsen 320B sub-bottom profiler. These
sound sources will be operated continuously from the Langseth
throughout the cruise.
Multibeam Echosounder
The Langseth will operate a Kongsberg EM 122 multibeam echosounder
concurrently during airgun operations to map characteristics of the
ocean floor. The hull-mounted multibeam echosounder emits brief pulses
of sound (also called a ping) (10.5 to 13, usually 12 kHz) in a fan-
shaped beam that extends downward and to the sides of the ship. The
transmitting beamwidth is 1[deg] or 2[deg] fore-aft and 150[deg]
athwartship and the maximum source level is 242 dB re: 1 [mu]Pa.
Each ping consists of eight (in water greater than 1,000 m) or four
(less than 1,000 m) successive, fan-shaped transmissions, each
ensonifying a sector that extends 1[deg] fore-aft. Continuous-wave
pulses increase from 2 to 15 milliseconds (ms) long in water depths up
to 2,600 m (8,350.2 ft), and frequency modulated (FM) chirp pulses up
to 100 ms long are used in water greater than 2,600 m. The successive
transmissions span an overall cross-track angular extent of about
150[deg], with 2 ms gaps between the pulses for successive sectors (see
Table 1 of the IHA application).
Sub-Bottom Profiler
The Langseth will also operate a Knudsen Chirp 320B sub-bottom
continuously throughout the cruise simultaneously with the multibeam
echosounder to map and provide information about the sedimentary
features and bottom topography. The beam is transmitted as a 27[deg]
cone, which is directed downward by a 3.5 kHz transducer in the hull of
the Langseth. The maximum output is 1 kilowatt (kW), but in practice,
the output varies with water depth. The pulse interval is one second,
but a common mode of operation is to broadcast five pulses at one
second intervals followed by a 5-second pause.
Both the multibeam echosounder and sub-bottom profiler are operated
continuously during survey operations. Given the relatively shallow
water depths of the survey area (20 to 300 m [66 to 984 ft]), the
number of pings or transmissions would be reduced from 8 to 4, and the
pulse durations would be reduced from 100 ms to 2 to 15 ms for the
multibeam echosounder. Power levels of both instruments would be
reduced from maximum levels to account for water depth. Actual
operating parameters will be established at the time of the survey.
NMFS expects that acoustic stimuli resulting from the proposed
operation of the single airgun or the 18 airgun array has the potential
to harass marine mammals. NMFS does not expect that the movement of the
Langseth, during the conduct of the seismic survey, has the potential
to harass marine mammals because of the relatively slow operation speed
of the vessel (approximately 4.6 knots [kts]; 8.5 km/hr; 5.3 mph)
during seismic acquisition.
Dates, Duration, and Specified Geographic Region
The proposed survey would encompass the area between approximately
41.5 to 42.5[deg] North and approximately 11.5 to 17.5[deg] West in the
northeast Atlantic Ocean to the west of Spain. The cruise will be in
International Waters and in the Exclusive Economic Zone (EEZ) of Spain
in water depts. In the range from approximately 3,500 to greater than
5,000 m (see Figure 1 of the IHA application). The exact dates of the
proposed activities depend on logistics and weather conditions. The
Langseth would depart from Lisbon, Portugal or Vigo, Spain on June, 1,
2013 and spend approximately 1 day in transit to the proposed survey
area. The seismic survey is expected to take approximately 39 days,
with completion on approximately July 12, 2013. When the survey is
completed, the Langseth will then transit back to Lisbon, Portugal or
Vigo, Spain.
Description of the Marine Mammals in the Area of the Proposed Specified
Activity
Thirty-nine marine mammal species (36 cetaceans [whales, dolphins,
and porpoises]) (29 odontocetes and 7 mysticetes] and 3 pinnipeds
[seals and sea lions]) are known to or could occur in the eastern North
Atlantic study area. Several of these species are listed as endangered
under the U.S. Endangered Species Act of 1973 (ESA; 16 U.S.C. 1531 et
seq.), including the North Atlantic right (Eubalaena glacialis),
humpback (Megaptera novaeangliae), sei (Balaenoptera borealis), fin
(Balaenoptera physalus), blue (Balaenoptera musculus), and sperm
(Physeter macrocephalus) whales. Nine cetacean species, although
present in the wider eastern North Atlantic ocean, likely would not be
found near the proposed study area at approximately 42[deg] North
because their ranges generally do not extend south of approximately
45[deg] North in the northeastern Atlantic waters (i.e., Atlantic
white-sided dolphin [Lagenorhynchus acutus] and white-beaked dolphin
[Lagenorhynchus albirostris]), or their ranges in the northeast
Atlantic ocean generally do not extend north of approximately 20[deg]
North (Clymene dolphin [Stenella clymene]), 30[deg] North (Fraser's
dolphin [Lagenodelphis hosei]), 34[deg] North (spinner dolphin
[Stenella longirostris]), 35 [deg] North (melon-headed whale
[Peponocephala electra]), 37[deg] North (rough-toothed dolphin [Steno
bredandensis]), or 40[deg] North (Bryde's whale [Balaenoptera brydei]
and pantropical spotted dolphin [Stenella attenuata]). Although Spitz
et al. (2011) reported two strandings records of
[[Page 17364]]
melon-headed whales for the Bay of Biscay, this species will not be
discussed further, as it is unlikely to occur in the proposed survey
area.
The harbor porpoise (Phocoena phocoena) does not occur in deep
offshore waters. No harbor porpoise were detected visually or
acoustically during summer surveys off the continental shelf in the
Biscay Bay area during 1989 and 2007 (Lens, 1991; Basto d'Andrade,
2008; Anonymous, 2009). Pinniped species are also not known to occur in
the deep waters of the survey area.
General information on the taxonomy, ecology, distribution, and
movements, and acoustic capabilities of marine mammals are given in
sections 3.6.1 and 3.7.1 of the NSF/USGS PEIS. One of the qualitative
analysis areas defined in the PEIS is on the Mid-Atlantic Ridge, at
26[deg] North, 40[deg] West, approximately 2,800 km (1,511.9 nmi) from
the proposed survey area. The general distribution of mysticetes and
odontocetes in the North Atlantic Ocean is discussed in sections
3.6.3.4 and 3.7.3.4 of the NSF/USGS PEIS, respectively. The rest of
this section deals specifically with species distribution off the north
and west coast of the Iberian Peninsula.
Several systematic surveys have been conducted in the Bay of Biscay
area, which has been found to be one of the most productive areas and
the centre of highest cetacean diversity in the northeast Atlantic
Ocean (Hoyt, 2005). The second North Atlantic Sightings Survey (NASS)
occurred in waters off the continental shelf from the southern U.K. to
northern Spain in July to August, 1989 (Lens, 1991). The Cetacean
Offshore Distribution and Abundance in the European Atlantic (CODA)
included surveys from the U.K. to southern Spain during July, 2007
(Basto d'Andrade, 2008; Anonymous, 2009). Additional information is
available from coastal surveys off northwest Spain (e.g., Lopez et al.,
2003), and sighting records off western central (Brito et al., 2009)
and southern Portugal (Castor et al., 2010). Records from the Ocean
Biogeographic Information System (OBIS) database hosted by Rutgers and
Duke University (Read et al., 2009) were also included.
Table 2 (below) presents information on the abundance,
distribution, population status, conservation status, and population
trend of the species of marine mammals that may occur in the proposed
study area during June to July, 2013.
Table 2--The Habitat, Regional Abundance, and Conservation Status of Marine Mammals That May Occur in or Near the Proposed Seismic Survey Area in the
Northeast Atlantic Ocean
[See text and Table 3 in L-DEO's application for further details.]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Population estimate in the
Species Habitat North Atlantic ESA\1\ MMPA \2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Mysticetes:
North Atlantic right whale Pelagic, shelf and 396 \3\....................... EN............................ D.
(Eubalaena glacialis). coastal.
Humpback whale (Megaptera Mainly nearshore, 11,570 \4\.................... EN............................ D.
novaeangliae). banks.
Minke whale (Balaenoptera Pelagic and coastal 121,000 \5\................... NL............................ NC.
acutorostrata).
Sei whale (Balaenoptera Primarily offshore, 12,000 to 13,000 \6\.......... EN............................ D.
borealis). pelagic.
Fin whale (Balaenoptera Continental slope, 24,887 \7\.................... EN............................ D.
physalus). pelagic.
Blue whale (Balaenoptera Pelagic, shelf, 937 \8\....................... EN............................ D.
musculus). coastal.
Odontocetes:
Sperm whale (Physeter Pelagic, deep sea.. 13,190 \9\.................... EN............................ D.
macrocephalus).
Pygmy sperm whale (Kogia Deep waters off the 395 3 10...................... NL............................ NC.
breviceps). shelf.
Dwarf sperm whale (Kogia Deep waters off the NL............................ NC.
sima). shelf.
Cuvier's beaked whale Slope and Pelagic.. 6,992 \11\.................... NL............................ NC.
(Ziphius cavirostris). 100,000 \12\..................
Northern bottlenose whale Pelagic............ 40,000 \13\................... NL............................ NC.
(Hyperoodon ampullatus).
True's beaked whale Pelagic............ 6,992 \11\.................... NL............................ NC.
(Mesoplodon mirus).
Gervais' beaked whale Pelagic............ 6,992 \11\.................... NL............................ NC.
(Mesoplodon europaeus).
Sowerby's beaked whale Pelagic............ 6,992 \11\.................... NL............................ NC.
(Mesoplodon bidens).
Blainville's beaked whale Pelagic............ 6,992 \11\.................... NL............................ NC.
(Mesoplodon densirostris).
Bottlenose dolphin (Tursiops Coastal, oceanic, 19,295 \14\................... NL............................ NC D--Western North Atlantic
truncatus). shelf break. coastal.
Atlantic spotted dolphin Shelf, offshore.... 50,978 \3\.................... NL............................ NC.
(Stenella frontalis).
Striped dolphin (Stenella Off continental 67,414 \14\................... NL............................ NC.
coeruleoalba). shelf.
Short-beaked common dolphin Shelf, pelagic, 116,709 \14\.................. NL............................ NC.
(Delphinus delphis). seamounts.
Risso's dolphin (Grampus Deep water, 20,479 \3\.................... NL............................ NC.
griseus). seamounts.
Pygmy killer whale (Feresa Pelagic............ NA............................ NL............................ NC.
attenuata).
False killer whale (Pseudorca Pelagic............ NA............................ NL............................ NC.
crassidens).
[[Page 17365]]
Killer whale (Orcinus orca).. Pelagic, shelf, NA............................ NL EN--Southern resident...... NC D--Southern resident, AT1
coastal. transient.
Short-finned pilot whale Pelagic, shelf 780,000 \15\.................. NL............................ NC.
(Globicephala macrorhynchus). coastal.
Long-finned pilot whale Mostly pelagic..... NC............................ NC.
(Globicephala melas).
--------------------------------------------------------------------------------------------------------------------------------------------------------
NA = Not available or not assessed.
\1\ U.S. Endangered Species Act: EN = Endangered, T = Threatened, DL = Delisted, NL = Not listed.
\2\ U.S. Marine Mammal Protection Act: D = Depleted, NC = Not Classified.
\3\ Western North Atlantic, in U.S. and southern Canadian waters (Waring et al., 2012).
\4\ Likely negatively biased (Stevick et al., 2003).
\5\ Central and Northeast Atlantic (IWC, 2012).
\6\ North Atlantic (Cattanach et al., 1993).
\7\ Central and Northeast Atlantic (Vikingsson et al., 2009).
\8\ Central and Northeast Atlantic (Pike et al., 2009).
\9\ For the northeast Atlantic, Faroes-Iceland, and the U.S. east coast (Whitehead, 2002).
\10\ Both Kogia species.
\11\ For all beaked whales (Anonymous, 2009).
\12\ Worldwide estimate (Taylor et al., 2008).
\13\ Eastern North Atlantic (NAMMCO, 1995).
\14\ European Atlantic waters beyond the continental shelf (Anonymous, 2009).
\15\ Globicephala spp. combined, Central and Eastern North Atlantic (IWC, 2012).
Refer to sections 3 and 4 of L-DEO's application for detailed
information regarding the abundance and distribution, population
status, and life history and behavior of these other marine mammal
species and their occurrence in the proposed project area. The
application also presents how L-DEO calculated the estimated densities
for the marine mammals in the proposed survey area. NMFS has reviewed
these data and determined them to be the best available scientific
information for the purposes of the proposed IHA.
Potential Effects on Marine Mammals
Acoustic stimuli generated by the operation of the airguns, which
introduce sound into the marine environment, may have the potential to
cause Level B harassment of marine mammals in the proposed survey area.
The effects of sounds from airgun operations might include one or more
of the following: tolerance, masking of natural sounds, behavioral
disturbance, temporary or permanent hearing impairment, or non-auditory
physical or physiological effects (Richardson et al., 1995; Gordon et
al., 2004; Nowacek et al., 2007; Southall et al., 2007). Permanent
hearing impairment, in the unlikely event that it occurred, would
constitute injury, but temporary threshold shift (TTS) is not an injury
(Southall et al., 2007). Although the possibility cannot be entirely
excluded, it is unlikely that the proposed project would result in any
cases of temporary or permanent hearing impairment, or any significant
non-auditory physical or physiological effects. Based on the available
data and studies described here, some behavioral disturbance is
expected. A more comprehensive review of these issues can be found in
the ``Programmatic Environmental Impact Statement/Overseas
Environmental Impact Statement prepared for Marine Seismic Research
that is funded by the National Science Foundation and conducted by the
U.S. Geological Survey'' (NSF/USGS, 2011).
Tolerance
Richardson et al. (1995) defines tolerance as the occurrence of
marine mammals in areas where they are exposed to human activities or
man-made noise. In many cases, tolerance develops by the animal
habituating to the stimulus (i.e., the gradual waning of responses to a
repeated or ongoing stimulus) (Richardson, et al., 1995; Thorpe, 1963),
but because of ecological or physiological requirements, many marine
animals may need to remain in areas where they are exposed to chronic
stimuli (Richardson, et al., 1995).
Numerous studies have shown that pulsed sounds from airguns are
often readily detectable in the water at distances of many kilometers.
Several studies have shown that marine mammals at distances more than a
few kilometers from operating seismic vessels often show no apparent
response. That is often true even in cases when the pulsed sounds must
be readily audible to the animals based on measured received levels and
the hearing sensitivity of the marine mammal group. Although various
baleen whales and toothed whales, and (less frequently) pinnipeds have
been shown to react behaviorally to airgun pulses under some
conditions, at other times marine mammals of all three types have shown
no overt reactions. The relative responsiveness of baleen and toothed
whales are quite variable.
Masking
The term masking refers to the inability of a subject to recognize
the occurrence of an acoustic stimulus as a result of the interference
of another acoustic stimulus (Clark et al., 2009). Introduced
underwater sound may, through masking, reduce the effective
communication distance of a marine mammal species if the frequency of
the source is close to that used as a signal by the marine mammal, and
if the anthropogenic sound is present for a significant fraction of the
time (Richardson et al., 1995).
Masking effects of pulsed sounds (even from large arrays of
airguns) on marine mammal calls and other natural sounds are expected
to be limited. Because of the intermittent nature and low duty cycle of
seismic airgun pulses, animals can emit and receive sounds in the
relatively quiet intervals between pulses. However, in some situations,
reverberation occurs for much or the entire interval between pulses
(e.g., Simard et al., 2005; Clark and Gagnon, 2006) which could mask
calls. Some baleen and toothed whales are known to continue calling in
the presence of
[[Page 17366]]
seismic pulses, and their calls can usually be heard between the
seismic pulses (e.g., Richardson et al., 1986; McDonald et al., 1995;
Greene et al., 1999; Nieukirk et al., 2004; Smultea et al., 2004; Holst
et al., 2005a,b, 2006; and Dunn and Hernandez, 2009). However, Clark
and Gagnon (2006) reported that fin whales in the North Atlantic Ocean
went silent for an extended period starting soon after the onset of a
seismic survey in the area. Similarly, there has been one report that
sperm whales ceased calling when exposed to pulses from a very distant
seismic ship (Bowles et al., 1994). However, more recent studies found
that they continued calling in the presence of seismic pulses (Madsen
et al., 2002; Tyack et al., 2003; Smultea et al., 2004; Holst et al.,
2006; and Jochens et al., 2008). Dilorio and Clark (2009) found
evidence of increased calling by blue whales during operations by a
lower-energy seismic source (i.e., sparker). Dolphins and porpoises
commonly are heard calling while airguns are operating (e.g., Gordon et
al., 2004; Smultea et al., 2004; Holst et al., 2005a, b; and Potter et
al., 2007). The sounds important to small odontocetes are predominantly
at much higher frequencies than are the dominant components of airgun
sounds, thus limiting the potential for masking.
Marine mammals are thought to be able to compensate for masking by
adjusting their acoustic behavior through shifting call frequencies,
increasing call volume, and increasing vocalization rates. For example,
blue whales are found to increase call rates when exposed to noise from
seismic surveys in the St. Lawrence Estuary (Dilorio and Clark, 2009).
The North Atlantic right whales (Eubalaena glacialis) exposed to high
shipping noise increased call frequency (Parks et al., 2007), while
some humpback whales respond to low-frequency active sonar playbacks by
increasing song length (Miller et al., 2000). In general, NMFS expects
the masking effects of seismic pulses to be minor, given the normally
intermittent nature of seismic pulses.
Behavioral Disturbance
Marine mammals may behaviorally react to sound when exposed to
anthropogenic noise. Disturbance includes a variety of effects,
including subtle to conspicuous changes in behavior, movement, and
displacement. Reactions to sound, if any, depend on species, state of
maturity, experience, current activity, reproductive state, time of
day, and many other factors (Richardson et al., 1995; Wartzok et al.,
2004; Southall et al., 2007; Weilgart, 2007). These behavioral
reactions are often shown as: changing durations of surfacing and
dives, number of blows per surfacing, or moving direction and/or speed;
reduced/increased vocal activities; changing/cessation of certain
behavioral activities (such as socializing or feeding); visible startle
response or aggressive behavior (such as tail/fluke slapping or jaw
clapping); avoidance of areas where noise sources are located; and/or
flight responses (e.g., pinnipeds flushing into the water from haul-
outs or rookeries). If a marine mammal does react briefly to an
underwater sound by changing its behavior or moving a small distance,
the impacts of the change are unlikely to be significant to the
individual, let alone the stock or population. However, if a sound
source displaces marine mammals from an important feeding or breeding
area for a prolonged period, impacts on individuals and populations
could be significant (e.g., Lusseau and Bejder, 2007; Weilgart, 2007).
The biological significance of many of these behavioral
disturbances is difficult to predict, especially if the detected
disturbances appear minor. However, the consequences of behavioral
modification could be expected to be biologically significant if the
change affects growth, survival, and/or reproduction. Some of these
significant behavioral modifications include:
Change in diving/surfacing patterns (such as those thought
to be causing beaked whale stranding due to exposure to military mid-
frequency tactical sonar);
Habitat abandonment due to loss of desirable acoustic
environment; and
Cessation of feeding or social interaction.
The onset of behavioral disturbance from anthropogenic noise
depends on both external factors (characteristics of noise sources and
their paths) and the receiving animals (hearing, motivation,
experience, demography) and is also difficult to predict (Richardson et
al., 1995; Southall et al., 2007). Given the many uncertainties in
predicting the quantity and types of impacts of noise on marine
mammals, it is common practice to estimate how many mammals would be
present within a particular distance of industrial activities and/or
exposed to a particular level of sound. In most cases, this approach
likely overestimates the numbers of marine mammals that would be
affected in some biologically-important manner.
Baleen Whales--Baleen whales generally tend to avoid operating
airguns, but avoidance radii are quite variable (reviewed in Richardson
et al., 1995; Gordon et al., 2004). Whales are often reported to show
no overt reactions to pulses from large arrays of airguns at distances
beyond a few kilometers, even though the airgun pulses remain well
above ambient noise levels out to much longer distances. However,
baleen whales exposed to strong noise pulses from airguns often react
by deviating from their normal migration route and/or interrupting
their feeding and moving away. In the cases of migrating gray and
bowhead whales, the observed changes in behavior appeared to be of
little or no biological consequence to the animals (Richardson, et al.,
1995). They simply avoided the sound source by displacing their
migration route to varying degrees, but within the natural boundaries
of the migration corridors.
Studies of gray, bowhead, and humpback whales have shown that
seismic pulses with received levels of 160 to 170 dB re 1 [mu]Pa (rms)
seem to cause obvious avoidance behavior in a substantial fraction of
the animals exposed (Malme et al., 1986, 1988; Richardson et al.,
1995). In many areas, seismic pulses from large arrays of airguns
diminish to those levels at distances ranging from 4 to 15 km (2.2 to
8.1 nmi) from the source. A substantial proportion of the baleen whales
within those distances may show avoidance or other strong behavioral
reactions to the airgun array. Subtle behavioral changes sometimes
become evident at somewhat lower received levels, and studies have
shown that some species of baleen whales, notably bowhead, gray, and
humpback whales, at times, show strong avoidance at received levels
lower than 160 to 170 dB re 1 [mu]Pa (rms).
Researchers have studied the responses of humpback whales to
seismic surveys during migration, feeding during the summer months,
breeding while offshore from Angola, and wintering offshore from
Brazil. McCauley et al. (1998, 2000a) studied the responses of humpback
whales off western Australia to a full-scale seismic survey with a 16
airgun array (2,678 in\3\) and to a single airgun (20 in\3\) with
source level of 227 dB re 1 [micro]Pa (p-p). In the 1998 study, they
documented that avoidance reactions began at 5 to 8 km (2.7 to 4.3 nmi)
from the array, and that those reactions kept most pods approximately 3
to 4 km (1.6 to 2.2 nmi) from the operating seismic boat. In the 2000
study, they noted localized displacement during migration of 4 to 5 km
(2.2 to 2.7 nmi) by traveling pods and 7 to 12 km (3.8 to 6.5 nmi) by
more sensitive resting pods of cow-calf pairs. Avoidance distances with
respect to the
[[Page 17367]]
single airgun were smaller but consistent with the results from the
full array in terms of the received sound levels. The mean received
level for initial avoidance of an approaching airgun was 140 dB re 1
[mu]Pa (rms) for humpback pods containing females, and at the mean
closest point of approach distance the received level was 143 dB re 1
[mu]Pa (rms). The initial avoidance response generally occurred at
distances of 5 to 8 km (2.7 to 4.3 nmi) from the airgun array and 2 km
(1.1 nmi) from the single airgun. However, some individual humpback
whales, especially males, approached within distances of 100 to 400 m
(328 to 1,312 ft), where the maximum received level was 179 dB re 1
[mu]Pa (rms).
Data collected by observers during several seismic surveys in the
Northwest Atlantic showed that sighting rates of humpback whales were
significantly greater during non-seismic periods compared with periods
when a full array was operating (Moulton and Holst, 2010). In addition,
humpback whales were more likely to swim away and less likely to swim
towards a vessel during seismic vs. non-seismic periods (Moulton and
Holst, 2010).
Humpback whales on their summer feeding grounds in southeast Alaska
did not exhibit persistent avoidance when exposed to seismic pulses
from a 1.64-L (100 in\3\) airgun (Malme et al., 1985). Some humpbacks
seemed ``startled'' at received levels of 150 to 169 dB re 1 [mu]Pa.
Malme et al. (1985) concluded that there was no clear evidence of
avoidance, despite the possibility of subtle effects, at received
levels up to 172 dB re 1 [mu]Pa (rms). However, Moulton and Holst
(2010) reported that humpback whales monitored during seismic surveys
in the Northwest Atlantic had lower sighting rates and were most often
seen swimming away from the vessel during seismic periods compared with
periods when airguns were silent.
Studies have suggested that South Atlantic humpback whales
wintering off Brazil may be displaced or even strand upon exposure to
seismic surveys (Engel et al., 2004). The evidence for this was
circumstantial and subject to alternative explanations (IAGC, 2004).
Also, the evidence was not consistent with subsequent results from the
same area of Brazil (Parente et al., 2006), or with direct studies of
humpbacks exposed to seismic surveys in other areas and seasons. After
allowance for data from subsequent years, there was ``no observable
direct correlation'' between strandings and seismic surveys (IWC, 2007:
236).
Reactions of migrating and feeding (but not wintering) gray whales
to seismic surveys have been studied. Malme et al. (1986, 1988) studied
the responses of feeding eastern Pacific gray whales to pulses from a
single 100 in\3\ airgun off St. Lawrence Island in the northern Bering
Sea. They estimated, based on small sample sizes, that 50 percent of
feeding gray whales stopped feeding at an average received pressure
level of 173 dB re 1 [mu]Pa on an (approximate) rms basis, and that 10
percent of feeding whales interrupted feeding at received levels of 163
dB re 1 [mu]Pa (rms). Those findings were generally consistent with the
results of experiments conducted on larger numbers of gray whales that
were migrating along the California coast (Malme et al., 1984; Malme
and Miles, 1985), and western Pacific gray whales feeding off Sakhalin
Island, Russia (Wursig et al., 1999; Gailey et al., 2007; Johnson et
al., 2007; Yazvenko et al., 2007a, b), along with data on gray whales
off British Columbia (Bain and Williams, 2006).
Various species of Balaenoptera (blue, sei, fin, and minke whales)
have occasionally been seen in areas ensonified by airgun pulses
(Stone, 2003; MacLean and Haley, 2004; Stone and Tasker, 2006), and
calls from blue and fin whales have been localized in areas with airgun
operations (e.g., McDonald et al., 1995; Dunn and Hernandez, 2009;
Castellote et al., 2010). Sightings by observers on seismic vessels off
the United Kingdom from 1997 to 2000 suggest that, during times of good
sightability, sighting rates for mysticetes (mainly fin and sei whales)
were similar when large arrays of airguns were shooting vs. silent
(Stone, 2003; Stone and Tasker, 2006). However, these whales tended to
exhibit localized avoidance, remaining significantly further (on
average) from the airgun array during seismic operations compared with
non-seismic periods (Stone and Tasker, 2006). Castellote et al. (2010)
reported that singing fin whales in the Mediterranean moved away from
an operating airgun array.
Ship-based monitoring studies of baleen whales (including blue,
fin, sei, minke, and humpback whales) in the Northwest Atlantic found
that overall, this group had lower sighting rates during seismic vs.
non-seismic periods (Moulton and Holst, 2010). Baleen whales as a group
were also seen significantly farther from the vessel during seismic
compared with non-seismic periods, and they were more often seen to be
swimming away from the operating seismic vessel (Moulton and Holst,
2010). Blue and minke whales were initially sighted significantly
farther from the vessel during seismic operations compared to non-
seismic periods; the same trend was observed for fin whales (Moulton
and Holst, 2010). Minke whales were most often observed to be swimming
away from the vessel when seismic operations were underway (Moulton and
Holst, 2010).
Data on short-term reactions by cetaceans to impulsive noises are
not necessarily indicative of long-term or biologically significant
effects. It is not known whether impulsive sounds affect reproductive
rate or distribution and habitat use in subsequent days or years.
However, gray whales have continued to migrate annually along the west
coast of North America with substantial increases in the population
over recent years, despite intermittent seismic exploration (and much
ship traffic) in that area for decades (Appendix A in Malme et al.,
1984; Richardson et al., 1995; Allen and Angliss, 2010). The western
Pacific gray whale population did not seem affected by a seismic survey
in its feeding ground during a previous year (Johnson et al., 2007).
Similarly, bowhead whales have continued to travel to the eastern
Beaufort Sea each summer, and their numbers have increased notably,
despite seismic exploration in their summer and autumn range for many
years (Richardson et al., 1987; Allen and Angliss, 2010). The history
of coexistence between seismic surveys and baleen whales suggests that
brief exposures to sound pulses from any single seismic survey are
unlikely to result in prolonged effects.
Toothed Whales--Little systematic information is available about
reactions of toothed whales to noise pulses. Few studies similar to the
more extensive baleen whale/seismic pulse work summarized above have
been reported for toothed whales. However, there are recent systematic
studies on sperm whales (e.g., Gordon et al., 2006; Madsen et al.,
2006; Winsor and Mate, 2006; Jochens et al., 2008; Miller et al.,
2009). There is an increasing amount of information about responses of
various odontocetes to seismic surveys based on monitoring studies
(e.g., Stone, 2003; Smultea et al., 2004; Moulton and Miller, 2005;
Bain and Williams, 2006; Holst et al., 2006; Stone and Tasker, 2006;
Potter et al., 2007; Hauser et al., 2008; Holst and Smultea, 2008;
Weir, 2008; Barkaszi et al., 2009; Richardson et al., 2009; Moulton and
Holst, 2010).
Seismic operators and PSOs on seismic vessels regularly see
dolphins and other small toothed whales near
[[Page 17368]]
operating airgun arrays, but in general there is a tendency for most
delphinids to show some avoidance of operating seismic vessels (e.g.,
Goold, 1996a,b,c; Calambokidis and Osmek, 1998; Stone, 2003; Moulton
and Miller, 2005; Holst et al., 2006; Stone and Tasker, 2006; Weir,
2008; Richardson et al., 2009; Barkaszi et al., 2009; Moulton and
Holst, 2010). Some dolphins seem to be attracted to the seismic vessel
and floats, and some ride the bow wave of the seismic vessel even when
large arrays of airguns are firing (e.g., Moulton and Miller, 2005).
Nonetheless, small toothed whales more often tend to head away, or to
maintain a somewhat greater distance from the vessel, when a large
array of airguns is operating than when it is silent (e.g., Stone and
Tasker, 2006; Weir, 2008; Barry et al., 2010; Moulton and Holst, 2010).
In most cases, the avoidance radii for delphinids appear to be small,
on the order of one km or less, and some individuals show no apparent
avoidance.
Captive bottlenose dolphins (Tursiops truncatus) and beluga whales
exhibited changes in behavior when exposed to strong pulsed sounds
similar in duration to those typically used in seismic surveys
(Finneran et al., 2000, 2002, 2005). However, the animals tolerated
high received levels of sound before exhibiting aversive behaviors.
Results for porpoises depend on species. The limited available data
suggest that harbor porpoises show stronger avoidance of seismic
operations than do Dall's porpoises (Stone, 2003; MacLean and Koski,
2005; Bain and Williams, 2006; Stone and Tasker, 2006). Dall's
porpoises seem relatively tolerant of airgun operations (MacLean and
Koski, 2005; Bain and Williams, 2006), although they too have been
observed to avoid large arrays of operating airguns (Calambokidis and
Osmek, 1998; Bain and Williams, 2006). This apparent difference in
responsiveness of these two porpoise species is consistent with their
relative responsiveness to boat traffic and some other acoustic sources
(Richardson et al., 1995; Southall et al., 2007).
Most studies of sperm whales exposed to airgun sounds indicate that
the sperm whale shows considerable tolerance of airgun pulses (e.g.,
Stone, 2003; Moulton et al., 2005, 2006a; Stone and Tasker, 2006; Weir,
2008). In most cases the whales do not show strong avoidance, and they
continue to call. However, controlled exposure experiments in the Gulf
of Mexico indicate that foraging behavior was altered upon exposure to
airgun sound (Jochens et al., 2008; Miller et al., 2009; Tyack, 2009).
There are almost no specific data on the behavioral reactions of
beaked whales to seismic surveys. However, some northern bottlenose
whales (Hyperoodon ampullatus) remained in the general area and
continued to produce high-frequency clicks when exposed to sound pulses
from distant seismic surveys (Gosselin and Lawson, 2004; Laurinolli and
Cochrane, 2005; Simard et al., 2005). Most beaked whales tend to avoid
approaching vessels of other types (e.g., Wursig et al., 1998). They
may also dive for an extended period when approached by a vessel (e.g.,
Kasuya, 1986), although it is uncertain how much longer such dives may
be as compared to dives by undisturbed beaked whales, which also are
often quite long (Baird et al., 2006; Tyack et al., 2006). Based on a
single observation, Aguilar-Soto et al. (2006) suggested that foraging
efficiency of Cuvier's beaked whales may be reduced by close approach
of vessels. In any event, it is likely that most beaked whales would
also show strong avoidance of an approaching seismic vessel, although
this has not been documented explicitly. In fact, Moulton and Holst
(2010) reported 15 sightings of beaked whales during seismic studies in
the Northwest Atlantic; seven of those sightings were made at times
when at least one airgun was operating. There was little evidence to
indicate that beaked whale behavior was affected by airgun operations;
sighting rates and distances were similar during seismic and non-
seismic periods (Moulton and Holst, 2010).
There are indications that some beaked whales may strand when naval
exercises involving mid-frequency sonar operation are ongoing nearby
(e.g., Simmonds and Lopez-Jurado, 1991; Frantzis, 1998; NOAA and USN,
2001; Jepson et al., 2003; Hildebrand, 2005; Barlow and Gisiner, 2006;
see also the ``Stranding and Mortality'' section in this notice). These
strandings are apparently a disturbance response, although auditory or
other injuries or other physiological effects may also be involved.
Whether beaked whales would ever react similarly to seismic surveys is
unknown. Seismic survey sounds are quite different from those of the
sonar in operation during the above-cited incidents.
Odontocete reactions to large arrays of airguns are variable and,
at least for delphinids and Dall's porpoises, seem to be confined to a
smaller radius than has been observed for the more responsive of some
mysticetes. However, other data suggest that some odontocete species,
including harbor porpoises, may be more responsive than might be
expected given their poor low-frequency hearing. Reactions at longer
distances may be particularly likely when sound propagation conditions
are conducive to transmission of the higher frequency components of
airgun sound to the animals' location (DeRuiter et al., 2006; Goold and
Coates, 2006; Tyack et al., 2006; Potter et al., 2007).
Hearing Impairment and Other Physical Effects
Exposure to high intensity sound for a sufficient duration may
result in auditory effects such as a noise-induced threshold shift--an
increase in the auditory threshold after exposure to noise (Finneran,
Carder, Schlundt, and Ridgway, 2005). Factors that influence the amount
of threshold shift include the amplitude, duration, frequency content,
temporal pattern, and energy distribution of noise exposure. The
magnitude of hearing threshold shift normally decreases over time
following cessation of the noise exposure. The amount of threshold
shift just after exposure is called the initial threshold shift. If the
threshold shift eventually returns to zero (i.e., the threshold returns
to the pre-exposure value), it is called temporary threshold shift
(TTS) (Southall et al., 2007).
Researchers have studied TTS in certain captive odontocetes and
pinnipeds exposed to strong sounds (reviewed in Southall et al., 2007).
However, there has been no specific documentation of TTS let alone
permanent hearing damage, i.e., permanent threshold shift (PTS), in
free-ranging marine mammals exposed to sequences of airgun pulses
during realistic field conditions.
Temporary Threshold Shift--TTS is the mildest form of hearing
impairment that can occur during exposure to a strong sound (Kryter,
1985). While experiencing TTS, the hearing threshold rises and a sound
must be stronger in order to be heard. At least in terrestrial mammals,
TTS can last from minutes or hours to (in cases of strong TTS) days.
For sound exposures at or somewhat above the TTS threshold, hearing
sensitivity in both terrestrial and marine mammals recovers rapidly
after exposure to the noise ends. Few data on sound levels and
durations necessary to elicit mild TTS have been obtained for marine
mammals, and none of the published data concern TTS elicited by
exposure to multiple pulses of sound. Available data on TTS in marine
mammals are summarized in Southall et al. (2007). Table 1 (above)
presents the estimated distances from the Langseth's airguns at which
the received energy level (per pulse, flat-weighted) would be
[[Page 17369]]
expected to be greater than or equal to 180 or 190 dB re 1 [mu]Pa
(rms).
To avoid the potential for injury (i.e., Level A harassment), NMFS
(1995, 2000) concluded that cetaceans and pinnipeds should not be
exposed to pulsed underwater noise at received levels exceeding 180 and
190 dB re 1 [mu]Pa (rms), respectively. NMFS believes that to avoid the
potential for Level A harassment, cetaceans and pinnipeds should not be
exposed to pulsed underwater noise at received levels exceeding 180 and
190 dB re 1 [mu]Pa (rms), respectively. The established 180 and 190 dB
(rms) criteria are not considered to be the levels above which TTS
might occur. Rather, they are the received levels above which, in the
view of a panel of bioacoustics specialists convened by NMFS before TTS
measurements for marine mammals started to become available, one could
not be certain that there would be no injurious effects, auditory or
otherwise, to marine mammals. NMFS also assumes that cetaceans and
pinnipeds exposed to levels exceeding 160 dB re 1 [mu]Pa (rms) may
experience Level B harassment.
For toothed whales, researchers have derived TTS information for
odontocetes from studies on the bottlenose dolphin and beluga. The
experiments show that exposure to a single impulse at a received level
of 207 kPa (or 30 psi, p-p), which is equivalent to 228 dB re 1 Pa (p-
p), resulted in a 7 and 6 dB TTS in the beluga whale at 0.4 and 30 kHz,
respectively. Thresholds returned to within 2 dB of the pre-exposure
level within 4 minutes of the exposure (Finneran et al., 2002). For the
one harbor porpoise tested, the received level of airgun sound that
elicited onset of TTS was lower (Lucke et al., 2009). If these results
from a single animal are representative, it is inappropriate to assume
that onset of TTS occurs at similar received levels in all odontocetes
(cf. Southall et al., 2007). Some cetaceans apparently can incur TTS at
considerably lower sound exposures than are necessary to elicit TTS in
the beluga or bottlenose dolphin.
For baleen whales, there are no data, direct or indirect, on levels
or properties of sound that are required to induce TTS. The frequencies
to which baleen whales are most sensitive are assumed to be lower than
those to which odontocetes are most sensitive, and natural background
noise levels at those low frequencies tend to be higher. As a result,
auditory thresholds of baleen whales within their frequency band of
best hearing are believed to be higher (less sensitive) than are those
of odontocetes at their best frequencies (Clark and Ellison, 2004).
From this, it is suspected that received levels causing TTS onset may
also be higher in baleen whales than those of odontocetes (Southall et
al., 2007).
Permanent Threshold Shift--When PTS occurs, there is physical
damage to the sound receptors in the ear. In severe cases, there can be
total or partial deafness, whereas in other cases, the animal has an
impaired ability to hear sounds in specific frequency ranges (Kryter,
1985). There is no specific evidence that exposure to pulses of airgun
sound can cause PTS in any marine mammal, even with large arrays of
airguns. However, given the possibility that mammals close to an airgun
array might incur at least mild TTS, there has been further speculation
about the possibility that some individuals occurring very close to
airguns might incur PTS (e.g., Richardson et al., 1995, p. 372ff;
Gedamke et al., 2008). Single or occasional occurrences of mild TTS are
not indicative of permanent auditory damage, but repeated or (in some
cases) single exposures to a level well above that causing TTS onset
might elicit PTS.
Relationships between TTS and PTS thresholds have not been studied
in marine mammals, but are assumed to be similar to those in humans and
other terrestrial mammals (Southall et al., 2007). PTS might occur at a
received sound level at least several dBs above that inducing mild TTS
if the animal were exposed to strong sound pulses with rapid rise
times. Based on data from terrestrial mammals, a precautionary
assumption is that the PTS threshold for impulse sounds (such as airgun
pulses as received close to the source) is at least 6 dB higher than
the TTS threshold on a peak-pressure basis, and probably greater than 6
dB (Southall et al., 2007).
Given the higher level of sound necessary to cause PTS as compared
with TTS, it is considerably less likely that PTS would occur. Baleen
whales generally avoid the immediate area around operating seismic
vessels, as do some other marine mammals. Some pinnipeds show avoidance
reactions to airguns, but their avoidance reactions are generally not
as strong or consistent as those of cetaceans, and occasionally they
seem to be attracted to operating seismic vessels (NMFS, 2010).
Stranding and Mortality--When a living or dead marine mammal swims
or floats onto shore and becomes ``beached'' or incapable of returning
to sea, the event is termed a ``stranding'' (Geraci et al., 1999;
Perrin and Geraci, 2002; Geraci and Lounsbury, 2005; NMFS, 2007). The
legal definition for a stranding under the MMPA is that ``(A) a marine
mammal is dead and is (i) on a beach or shore of the United States; or
(ii) in waters under the jurisdiction of the United States (including
any navigable waters); or (B) a marine mammal is alive and is (i) on a
beach or shore of the United States and is unable to return to the
water; (ii) on a beach or shore of the United States and, although able
to return to the water is in need of apparent medical attention; or
(iii) in the waters under the jurisdiction of the United States
(including any navigable waters), but is unable to return to its
natural habitat under its own power or without assistance.''
Marine mammals are known to strand for a variety of reasons, such
as infectious agents, biotoxicosis, starvation, fishery interaction,
ship strike, unusual oceanographic or weather events, sound exposure,
or combinations of these stressors sustained concurrently or in series.
However, the cause or causes of most strandings are unknown (Geraci et
al., 1976; Eaton, 1979; Odell et al., 1980; Best, 1982). Numerous
studies suggest that the physiology, behavior, habitat relationships,
age, or condition of cetaceans may cause them to strand or might pre-
dispose them to strand when exposed to another phenomenon. These
suggestions are consistent with the conclusions of numerous other
studies that have demonstrated that combinations of dissimilar
stressors commonly combine to kill an animal or dramatically reduce its
fitness, even though one exposure without the other does not produce
the same result (Chroussos, 2000; Creel, 2005; DeVries et al., 2003;
Fair and Becker, 2000; Foley et al., 2001; Moberg, 2000; Relyea, 2005a,
2005b; Romero, 2004; Sih et al., 2004).
Strandings Associated with Military Active Sonar--Several sources
have published lists of mass stranding events of cetaceans in an
attempt to identify relationships between those stranding events and
military active sonar (Hildebrand, 2004; IWC, 2005; Taylor et al.,
2004). For example, based on a review of stranding records between 1960
and 1995, the International Whaling Commission (2005) identified ten
mass stranding events and concluded that, out of eight stranding events
reported from the mid-1980s to the summer of 2003, seven had been
coincident with the use of mid-frequency active sonar and most involved
beaked whales.
Over the past 12 years, there have been five stranding events
coincident with military mid-frequency active
[[Page 17370]]
sonar use in which exposure to sonar is believed to have been a
contributing factor to strandings: Greece (1996); the Bahamas (2000);
Madeir (2000); Canary Islands (2002); and Spain (2006). Refer to Cox et
al. (2006) for a summary of common features shared by the strandings
events in Greece (1996), Bahamas (2000), Madeira (2000), and Canary
Islands (2002); and Fernandez et al., (2005) for an additional summary
of the Canary Islands 2002 stranding event.
Potential for Stranding from Seismic Surveys--Marine mammals close
to underwater detonations of high explosives can be killed or severely
injured, and the auditory organs are especially susceptible to injury
(Ketten et al., 1993; Ketten, 1995). However, explosives are no longer
used in marine waters for commercial seismic surveys or (with rare
exceptions) for seismic research. These methods have been replaced
entirely by airguns or related non-explosive pulse generators. Airgun
pulses are less energetic and have slower rise times, and there is no
specific evidence that they can cause serious injury, death, or
stranding even in the case of large airgun arrays. However, the
association of strandings of beaked whales with naval exercises
involving mid-frequency active sonar (non-pulse sound) and, in one
case, the co-occurrence of an L-DEO seismic survey (Malakoff, 2002; Cox
et al., 2006), has raised the possibility that beaked whales exposed to
strong ``pulsed'' sounds could also be susceptible to injury and/or
behavioral reactions that can lead to stranding (e.g., Hildebrand,
2005; Southall et al., 2007).
Specific sound-related processes that lead to strandings and
mortality are not well documented, but may include:
(1) Swimming in avoidance of a sound into shallow water;
(2) A change in behavior (such as a change in diving behavior) that
might contribute to tissue damage, gas bubble formation, hypoxia,
cardiac arrhythmia, hypertensive hemorrhage or other forms of trauma;
(3) A physiological change such as a vestibular response leading to
a behavioral change or stress-induced hemorrhagic diathesis, leading in
turn to tissue damage; and
(4) Tissue damage directly from sound exposure, such as through
acoustically-mediated bubble formation and growth or acoustic resonance
of tissues.
Some of these mechanisms are unlikely to apply in the case of
impulse sounds. However, there are indications that gas-bubble disease
(analogous to ``the bends''), induced in supersaturated tissue by a
behavioral response to acoustic exposure, could be a pathologic
mechanism for the strandings and mortality of some deep-diving
cetaceans exposed to sonar. The evidence for this remains
circumstantial and associated with exposure to naval mid-frequency
sonar, not seismic surveys (Cox et al., 2006; Southall et al., 2007).
Seismic pulses and mid-frequency sonar signals are quite different,
and some mechanisms by which sonar sounds have been hypothesized to
affect beaked whales are unlikely to apply to airgun pulses. Sounds
produced by airgun arrays are broadband impulses with most of the
energy below one kHz. Typical military mid-frequency sonar emits non-
impulse sounds at frequencies of 2 to 10 kHz, generally with a
relatively narrow bandwidth at any one time. A further difference
between seismic surveys and naval exercises is that naval exercises can
involve sound sources on more than one vessel. Thus, it is not
appropriate to expect that the same to marine mammals will result from
military sonar and seismic surveys. However, evidence that sonar
signals can, in special circumstances, lead (at least indirectly) to
physical damage and mortality (e.g., Balcomb and Claridge, 2001; NOAA
and USN, 2001; Jepson et al., 2003; Fern[aacute]ndez et al., 2004,
2005; Hildebrand 2005; Cox et al., 2006) suggests that caution is
warranted when dealing with exposure of marine mammals to any high-
intensity sound.
There is no conclusive evidence of cetacean strandings or deaths at
sea as a result of exposure to seismic surveys, but a few cases of
strandings in the general area where a seismic survey was ongoing have
led to speculation concerning a possible link between seismic surveys
and strandings. Suggestions that there was a link between seismic
surveys and strandings of humpback whales in Brazil (Engel et al.,
2004) were not well founded (IAGC, 2004; IWC, 2007). In September,
2002, there was a stranding of two Cuvier's beaked whales in the Gulf
of California, Mexico, when the L-DEO vessel R/V Maurice Ewing was
operating a 20 airgun (8,490 in\3\) array in the general area. The link
between the stranding and the seismic surveys was inconclusive and not
based on any physical evidence (Hogarth, 2002; Yoder, 2002).
Nonetheless, the Gulf of California incident plus the beaked whale
strandings near naval exercises involving use of mid-frequency sonar
suggests a need for caution in conducting seismic surveys in areas
occupied by beaked whales until more is known about effects of seismic
surveys on those species (Hildebrand, 2005). No injuries of beaked
whales are anticipated during the proposed study because of:
(1) The high likelihood that any beaked whales nearby would avoid
the approaching vessel before being exposed to high sound levels, and
(2) Differences between the sound sources operated by L-DEO and
those involved in the naval exercises associated with strandings.
Non-auditory Physiological Effects--Non-auditory physiological
effects or injuries that theoretically might occur in marine mammals
exposed to strong underwater sound include stress, neurological
effects, bubble formation, resonance, and other types of organ or
tissue damage (Cox et al., 2006; Southall et al., 2007). Studies
examining such effects are limited. However, resonance effects (Gentry,
2002) and direct noise-induced bubble formations (Crum et al., 2005)
are implausible in the case of exposure to an impulsive broadband
source like an airgun array. If seismic surveys disrupt diving patterns
of deep-diving species, this might perhaps result in bubble formation
and a form of the bends, as speculated to occur in beaked whales
exposed to sonar. However, there is no specific evidence of this upon
exposure to airgun pulses.
In general, very little is known about the potential for seismic
survey sounds (or other types of strong underwater sounds) to cause
non-auditory physical effects in marine mammals. Such effects, if they
occur at all, would presumably be limited to short distances and to
activities that extend over a prolonged period. The available data do
not allow identification of a specific exposure level above which non-
auditory effects can be expected (Southall et al., 2007), or any
meaningful quantitative predictions of the numbers (if any) of marine
mammals that might be affected in those ways. Marine mammals that show
behavioral avoidance of seismic vessels, including most baleen whales,
some odontocetes, and some pinnipeds, are especially unlikely to incur
non-auditory physical effects.
Potential Effects of Other Acoustic Devices
Multibeam Echosounder
L-DEO will operate the Kongsberg EM 122 multibeam echosounder from
the source vessel during the planned study. Sounds from the multibeam
echosounder are very short pulses, occurring for 2 to 15 ms once every
5 to 20 s, depending on water depth. Most of the energy in the sound
pulses emitted by this multibeam echosounder is at frequencies near 12
kHz, and the
[[Page 17371]]
maximum source level is 242 dB re 1 [mu]Pa (rms). The beam is narrow (1
to 2[deg]) in fore-aft extent and wide (150[deg]) in the cross-track
extent. Each ping consists of eight (in water greater than 1,000 m
deep) or four (in water less than 1,000 m deep) successive fan-shaped
transmissions (segments) at different cross-track angles. Any given
mammal at depth near the trackline would be in the main beam for only
one or two of the nine segments. Also, marine mammals that encounter
the Kongsberg EM 122 are unlikely to be subjected to repeated pulses
because of the narrow fore-aft width of the beam and will receive only
limited amounts of pulse energy because of the short pulses. Animals
close to the ship (where the beam is narrowest) are especially unlikely
to be ensonified for more than one 2 to 15 ms pulse (or two pulses if
in the overlap area). Similarly, Kremser et al. (2005) noted that the
probability of a cetacean swimming through the area of exposure when a
multibeam echosounder emits a pulse is small. The animal would have to
pass the transducer at close range and be swimming at speeds similar to
the vessel in order to receive the multiple pulses that might result in
sufficient exposure to cause TTS.
Navy sonars that have been linked to avoidance reactions and
stranding of cetaceans: (1) Generally have longer pulse duration than
the Kongsberg EM 122; and (2) are often directed close to horizontally
versus more downward for the multibeam echosounder. The area of
possible influence of the multibeam echosounder is much smaller--a
narrow band below the source vessel. Also, the duration of exposure for
a given marine mammal can be much longer for naval sonar. During L-
DEO's operations, the individual pulses will be very short, and a given
mammal would not receive many of the downward-directed pulses as the
vessel passes by. Possible effects of a multibeam echosounder on marine
mammals are described below.
Masking--Marine mammal communications will not be masked
appreciably by the multibeam echosounder signals given the low duty
cycle of the echosounder and the brief period when an individual mammal
is likely to be within its beam. Furthermore, in the case of baleen
whales, the multibeam echosounder signals (12 kHz) do not overlap with
the predominant frequencies in the calls, which would avoid any
significant masking.
Behavioral Responses--Behavioral reactions of free-ranging marine
mammals to sonars, echosounders, and other sound sources appear to vary
by species and circumstance. Observed reactions have included silencing
and dispersal by sperm whales (Watkins et al., 1985), increased
vocalizations and no dispersal by pilot whales (Rendell and Gordon,
1999), and the previously-mentioned beachings by beaked whales. During
exposure to a 21 to 25 kHz ``whale-finding'' sonar with a source level
of 215 dB re 1 [mu]Pa, gray whales reacted by orienting slightly away
from the source and being deflected from their course by approximately
200 m (656.2 ft) (Frankel, 2005). When a 38 kHz echosounder and a 150
kHz acoustic Doppler current profiler were transmitting during studies
in the Eastern Tropical Pacific, baleen whales showed no significant
responses, while spotted and spinner dolphins were detected slightly
more often and beaked whales less often during visual surveys
(Gerrodette and Pettis, 2005).
Captive bottlenose dolphins and a beluga whale exhibited changes in
behavior when exposed to 1 s tonal signals at frequencies similar to
those that will be emitted by the multibeam echosounder used by L-DEO,
and to shorter broadband pulsed signals. Behavioral changes typically
involved what appeared to be deliberate attempts to avoid the sound
exposure (Schlundt et al., 2000; Finneran et al., 2002; Finneran and
Schlundt, 2004). The relevance of those data to free-ranging
odontocetes is uncertain, and in any case, the test sounds were quite
different in duration as compared with those from a multibeam
echosounder.
Hearing Impairment and Other Physical Effects--Given recent
stranding events that have been associated with the operation of naval
sonar, there is concern that mid-frequency sonar sounds can cause
serious impacts to marine mammals (see above). However, the multibeam
echosounder proposed for use by L-DEO is quite different than sonar
used for Navy operations. Pulse duration of the multibeam echosounder
is very short relative to the naval sonar. Also, at any given location,
an individual marine mammal would be in the beam of the multibeam
echosounder for much less time given the generally downward orientation
of the beam and its narrow fore-aft beamwidth; Navy sonar often uses
near-horizontally-directed sound. Those factors would all reduce the
sound energy received from the multibeam echosounder rather drastically
relative to that from naval sonar.
NMFS believes that the brief exposure of marine mammals to one
pulse, or small numbers of signals, from the multibeam echosounder is
not likely to result in the harassment of marine mammals.
Sub-Bottom Profiler
L-DEO will also operate a sub-bottom profiler from the source
vessel during the proposed survey. Sounds from the sub-bottom profiler
are very short pulses, occurring for 1 to 4 ms once every second. Most
of the energy in the sound pulses emitted by the sub-bottom profiler is
at 3.5 kHz, and the beam is directed downward. The sub-bottom profiler
on the Langseth has a maximum source level of 204 dB re 1 [mu]Pa.
Kremser et al. (2005) noted that the probability of a cetacean swimming
through the area of exposure when a bottom profiler emits a pulse is
small--even for a sub-bottom profiler more powerful than that on the
Langseth. If the animal was in the area, it would have to pass the
transducer at close range in order to be subjected to sound levels that
could cause TTS.
Masking--Marine mammal communications will not be masked
appreciably by the sub-bottom profiler signals given the directionality
of the signal and the brief period when an individual mammal is likely
to be within its beam. Furthermore, in the case of most baleen whales,
the sub-bottom profiler signals do not overlap with the predominant
frequencies in the calls, which would avoid significant masking.
Behavioral Responses--Marine mammal behavioral reactions to other
pulsed sound sources are discussed above, and responses to the sub-
bottom profiler are likely to be similar to those for other pulsed
sources if received at the same levels. However, the pulsed signals
from the sub-bottom profiler are considerably weaker than those from
the multibeam echosounder. Therefore, behavioral responses are not
expected unless marine mammals are very close to the source.
Hearing Impairment and Other Physical Effects--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 near the source. The sub-bottom profiler is
usually operated simultaneously with other higher-power acoustic
sources, including airguns. Many marine mammals will move away in
response to the approaching higher-power sources or the vessel itself
before the mammals would be close enough for there to be any
possibility of effects from the less intense sounds from the sub-bottom
profiler.
[[Page 17372]]
Vessel Movement and Collisions
Vessel movement in the vicinity of marine mammals has the potential
to result in either a behavioral response or a direct physical
interaction. Both scenarios are discussed below in this section.
Behavioral Responses to Vessel Movement--There are limited data
concerning marine mammal behavioral responses to vessel traffic and
vessel noise, and a lack of consensus among scientists with respect to
what these responses mean or whether they result in short-term or long-
term adverse effects. In those cases where there is a busy shipping
lane or where there is a large amount of vessel traffic, marine mammals
(especially low frequency specialists) may experience acoustic masking
(Hildebrand, 2005) if they are present in the area (e.g., killer whales
in Puget Sound; Foote et al., 2004; Holt et al., 2008). In cases where
vessels actively approach marine mammals (e.g., whale watching or
dolphin watching boats), scientists have documented that animals
exhibit altered behavior such as increased swimming speed, erratic
movement, and active avoidance behavior (Bursk, 1983; Acevedo, 1991;
Baker and MacGibbon, 1991; Trites and Bain, 2000; Williams et al.,
2002; Constantine et al., 2003), reduced blow interval (Ritcher et al.,
2003), disruption of normal social behaviors (Lusseau, 2003, 2006), and
the shift of behavioral activities which may increase energetic costs
(Constantine et al., 2003, 2004). A detailed review of marine mammal
reactions to ships and boats is available in Richardson et al., (1995).
For each of the marine mammal taxonomy groups, Richardson et al.,
(1995) provides the following assessment regarding reactions to vessel
traffic:
Toothed whales--``In summary, toothed whales sometimes show no
avoidance reaction to vessels, or even approach them. However,
avoidance can occur, especially in response to vessels of types used to
chase or hunt the animals. This may cause temporary displacement, but
we know of no clear evidence that toothed whales have abandoned
significant parts of their range because of vessel traffic.''
Baleen whales--``When baleen whales receive low-level sounds from
distant or stationary vessels, the sounds often seem to be ignored.
Some whales approach the sources of these sounds. When vessels approach
whales slowly and non-aggressively, whales often exhibit slow and
inconspicuous avoidance maneuvers. In response to strong or rapidly
changing vessel noise, baleen whales often interrupt their normal
behavior and swim rapidly away. Avoidance is especially strong when a
boat heads directly toward the whale.''
Behavioral responses to stimuli are complex and influenced to
varying degrees by a number of factors, such as species, behavioral
contexts, geographical regions, source characteristics (moving or
stationary, speed, direction, etc.), prior experience of the animal and
physical status of the animal. For example, studies have shown that
beluga whales' reaction varied when exposed to vessel noise and
traffic. In some cases, beluga whales exhibited rapid swimming from
ice-breaking vessels up to 80 km (43.2 nmi) away, and showed changes in
surfacing, breathing, diving, and group composition in the Canadian
high Arctic where vessel traffic is rare (Finley et al., 1990). In
other cases, beluga whales were more tolerant of vessels, but responded
differentially to certain vessels and operating characteristics by
reducing their calling rates (especially older animals) in the St.
Lawrence River where vessel traffic is common (Blane and Jaakson,
1994). In Bristol Bay, Alaska, beluga whales continued to feed when
surrounded by fishing vessels and resisted dispersal even when
purposefully harassed (Fish and Vania, 1971).
In reviewing more than 25 years of whale observation data, Watkins
(1986) concluded that whale reactions to vessel traffic were ``modified
by their previous experience and current activity: habituation often
occurred rapidly, attention to other stimuli or preoccupation with
other activities sometimes overcame their interest or wariness of
stimuli.'' Watkins noticed that over the years of exposure to ships in
the Cape Cod area, minke whales changed from frequent positive interest
(e.g., approaching vessels) to generally uninterested reactions; fin
whales changed from mostly negative (e.g., avoidance) to uninterested
reactions; fin whales changed from mostly negative (e.g., avoidance) to
uninterested reactions; right whales apparently continued the same
variety of responses (negative, uninterested, and positive responses)
with little change; and humpbacks dramatically changed from mixed
responses that were often negative to reactions that were often
strongly positive. Watkins (1986) summarized that ``whales near shore,
even in regions with low vessel traffic, generally have become less
wary of boats and their noises, and they have appeared to be less
easily disturbed than previously. In particular locations with intense
shipping and repeated approaches by boats (such as the whale-watching
areas of Stellwagen Bank), more and more whales had positive reactions
to familiar vessels, and they also occasionally approached other boats
and yachts in the same ways.''
Although the radiated sound from the Langseth and support vessels
will be audible to marine mammals over a large distance, it is unlikely
that marine mammals will respond behaviorally (in a manner that NMFS
would consider harassment under the MMPA) to low-level distant shipping
noise as the animals in the area are likely to be habituated to such
noises (Nowacek et al., 2004). In light of these facts, NMFS does not
expect the Langseth's movements to result in Level B harassment.
Vessel Strike--Ship strikes of cetaceans can cause major wounds,
which may lead to the death of the animal. An animal at the surface
could be struck directly by a vessel, a surfacing animal could hit the
bottom of a vessel, or an animal just below the surface could be cut by
a vessel's propeller. The severity of injuries typically depends on the
size and speed of the vessel (Knowlton and Kraus, 2001; Laist et al.,
2001; Vanderlaan and Taggart, 2007).
The most vulnerable marine mammals are those that spend extended
periods of time at the surface in order to restore oxygen levels within
their tissues after deep dives (e.g., the sperm whale). In addition,
some baleen whales, such as the North Atlantic right whale, seem
generally unresponsive to vessel sound, making them more susceptible to
vessel collisions (Nowacek et al., 2004). These species are primarily
large, slow moving whales. Smaller marine mammals (e.g., bottlenose
dolphin) move quickly through the water column and are often seen
riding the bow wave of large ships. Marine mammal responses to vessels
may include avoidance and changes in dive pattern (NRC, 2003).
An examination of all known ship strikes from all shipping sources
(civilian and military) indicates vessel speed is a principal factor in
whether a vessel strike results in death (Knowlton and Kraus, 2001;
Laist et al., 2001; Jensen and Silber, 2003; Vanderlaan and Taggart,
2007). In assessing records in which vessel speed was known, Laist et
al. (2001) found a direct relationship between the occurrence of a
whale strike and the speed of the vessel involved in the collision. The
authors concluded that most deaths occurred when a vessel was traveling
in excess of 13 kts (24.1 km/hr, 14.9 mph).
[[Page 17373]]
L-DEO's proposed operation of one source vessel and a support
vessel for the proposed survey is relatively small in scale compared to
the number of commercial ships transiting at higher speeds in the same
area on an annual basis. The probability of vessel and marine mammal
interactions occurring during the proposed survey is unlikely due to
the Langseth's and Poseidon's slow operational speed, which is
typically 4.6 kts (8.5 km/hr, 5.3 mph). Outside of seismic operations,
the Langseth's cruising speed would be approximately 10 kts (18.5 km/
hr, 11.5 mph), which is generally below the speed at which studies have
noted reported increases of marine mammal injury or death (Laist et
al., 2001).
As a final point, the Langseth has a number of other advantages for
avoiding ship strikes as compared to most commercial merchant vessels,
including the following: the Langseth's bridge offers good visibility
to visually monitor for marine mammal presence; PSOs posted during
operations scan the ocean for marine mammals and must report visual
alerts of marine mammal presence to crew; and the PSOs receive
extensive training that covers the fundamentals of visual observing for
marine mammals and information about marine mammals and their
identification at sea.
Entanglement
Entanglement can occur if wildlife becomes immobilized in survey
lines, cables, nets, or other equipment that is moving through the
water column. The proposed seismic survey would require towing
approximately 6.4 km\2\ (1.9 nmi\2\) of equipment and cables. This
large of an array carries the risk of entanglement for marine mammals.
Wildlife, especially slow moving individuals, such as large whales,
have a low probability of becoming entangled due to slow speed of the
survey vessel and onboard monitoring efforts. The NSF has no recorded
cases of entanglement of marine mammals during any of their 160,934 km
(86,897.4 nmi) of seismic surveys. In May, 2011, there was one recorded
entanglement of an olive ridley sea turtle (Lepidochelys olivacea) in
the Langseth's barovanes after the conclusion of a seismic survey off
Costa Rica. There have cases of baleen whales, mostly gray whales
(Heyning, 1990), becoming entangled in fishing lines. The probability
for entanglement of marine mammals is considered not significant
because of the vessel speed and the monitoring efforts onboard the
survey vessel.
The potential effects to marine mammals described in this section
of the document do not take into consideration the proposed monitoring
and mitigation measures described later in this document (see the
``Proposed Mitigation'' and ``Proposed Monitoring and Reporting''
sections) which, as noted, are designed to effect the least practicable
impact on affected marine mammal species and stocks.
Anticipated Effects on Marine Mammal Habitat
The proposed seismic survey is not anticipated to have any
permanent impact on habitats used by the marine mammals in the proposed
survey area, including the food sources they use (i.e. fish and
invertebrates). Additionally, no physical damage to any habitat is
anticipated as a result of conducting the proposed seismic survey.
While it is anticipated that the specified activity may result in
marine mammals avoiding certain areas due to temporary ensonification,
this impact to habitat is temporary and was considered in further
detail earlier in this document, as behavioral modification. The main
impact associated with the proposed activity will be temporarily
elevated noise levels and the associated direct effects on marine
mammals in any particular area of the approximately 6,437 km\2\
proposed project area, previously discussed in this notice. The next
section discusses the potential impacts of anthropogenic sound sources
on common marine mammal prey in the proposed survey area (i.e., fish
and invertebrates).
Anticipated Effects on Fish
One reason for the adoption of airguns as the standard energy
source for marine seismic surveys is that, unlike explosives, they have
not been associated with large-scale fish kills. However, existing
information on the impacts of seismic surveys on marine fish and
invertebrate populations is limited. There are three types of potential
effects of exposure to seismic surveys: (1) Pathological, (2)
physiological, and (3) behavioral. Pathological effects involve lethal
and temporary or permanent sub-lethal injury. Physiological effects
involve temporary and permanent primary and secondary stress responses,
such as changes in levels of enzymes and proteins. Behavioral effects
refer to temporary and (if they occur) permanent changes in exhibited
behavior (e.g., startle and avoidance behavior). The three categories
are interrelated in complex ways. For example, it is possible that
certain physiological and behavioral changes could potentially lead to
an ultimate pathological effect on individuals (i.e., mortality).
The specific received sound levels at which permanent adverse
effects to fish potentially could occur are little studied and largely
unknown. Furthermore, the available information on the impacts of
seismic surveys on marine fish is from studies of individuals or
portions of a population; there have been no studies at the population
scale. The studies of individual fish have often been on caged fish
that were exposed to airgun pulses in situations not representative of
an actual seismic survey. Thus, available information provides limited
insight on possible real-world effects at the ocean or population
scale. This makes drawing conclusions about impacts on fish problematic
because, ultimately, the most important issues concern effects on
marine fish populations, their viability, and their availability to
fisheries.
Hastings and Popper (2005), Popper (2009), and Popper and Hastings
(2009a,b) provided recent critical reviews of the known effects of
sound on fish. The following sections provide a general synopsis of the
available information on the effects of exposure to seismic and other
anthropogenic sound as relevant to fish. The information comprises
results from scientific studies of varying degrees of rigor plus some
anecdotal information. Some of the data sources may have serious
shortcomings in methods, analysis, interpretation, and reproducibility
that must be considered when interpreting their results (see Hastings
and Popper, 2005). Potential adverse effects of the program's sound
sources on marine fish are noted.
Pathological Effects--The potential for pathological damage to
hearing structures in fish depends on the energy level of the received
sound and the physiology and hearing capability of the species in
question. For a given sound to result in hearing loss, the sound must
exceed, by some substantial amount, the hearing threshold of the fish
for that sound (Popper, 2005). The consequences of temporary or
permanent hearing loss in individual fish on a fish population are
unknown; however, they likely depend on the number of individuals
affected and whether critical behaviors involving sound (e.g., predator
avoidance, prey capture, orientation and navigation, reproduction,
etc.) are adversely affected.
Little is known about the mechanisms and characteristics of damage
to fish that may be inflicted by exposure to seismic survey sounds. Few
data have been presented in the peer-reviewed
[[Page 17374]]
scientific literature. As far as L-DEO and NMFS know, there are only
two papers with proper experimental methods, controls, and careful
pathological investigation implicating sounds produced by actual
seismic survey airguns in causing adverse anatomical effects. One such
study indicated anatomical damage, and the second indicated TTS in fish
hearing. The anatomical case is McCauley et al. (2003), who found that
exposure to airgun sound caused observable anatomical damage to the
auditory maculae of pink snapper (Pagrus auratus). This damage in the
ears had not been repaired in fish sacrificed and examined almost two
months after exposure. On the other hand, Popper et al. (2005)
documented only TTS (as determined by auditory brainstem response) in
two of three fish species from the Mackenzie River Delta. This study
found that broad whitefish (Coregonus nasus) exposed to five airgun
shots were not significantly different from those of controls. During
both studies, the repetitive exposure to sound was greater than would
have occurred during a typical seismic survey. However, the substantial
low-frequency energy produced by the airguns (less than 400 Hz in the
study by McCauley et al. [2003] and less than approximately 200 Hz in
Popper et al. [2005]) likely did not propagate to the fish because the
water in the study areas was very shallow (approximately nine m in the
former case and less than two m in the latter). Water depth sets a
lower limit on the lowest sound frequency that will propagate (the
``cutoff frequency'') at about one-quarter wavelength (Urick, 1983;
Rogers and Cox, 1988).
Wardle et al. (2001) suggested that in water, acute injury and
death of organisms exposed to seismic energy depends primarily on two
features of the sound source: (1) The received peak pressure, and (2)
the time required for the pressure to rise and decay. Generally, as
received pressure increases, the period for the pressure to rise and
decay decreases, and the chance of acute pathological effects
increases. According to Buchanan et al. (2004), for the types of
seismic airguns and arrays involved with the proposed program, the
pathological (mortality) zone for fish would be expected to be within a
few meters of the seismic source. Numerous other studies provide
examples of no fish mortality upon exposure to seismic sources (Falk
and Lawrence, 1973; Holliday et al., 1987; La Bella et al., 1996;
Santulli et al., 1999; McCauley et al., 2000a,b, 2003; Bjarti, 2002;
Thomsen, 2002; Hassel et al., 2003; Popper et al., 2005; Boeger et al.,
2006).
An experiment of the effects of a single 700 in\3\ airgun was
conducted in Lake Meade, Nevada (USGS, 1999). The data were used in an
Environmental Assessment of the effects of a marine reflection survey
of the Lake Meade fault system by the National Park Service (Paulson et
al., 1993, in USGS, 1999). The airgun was suspended 3.5 m (11.5 ft)
above a school of threadfin shad in Lake Meade and was fired three
successive times at a 30 second interval. Neither surface inspection
nor diver observations of the water column and bottom found any dead
fish.
Some studies have reported, some equivocally, that mortality of
fish, fish eggs, or larvae can occur close to seismic sources
(Kostyuchenko, 1973; Dalen and Knutsen, 1986; Booman et al., 1996;
Dalen et al., 1996). Some of the reports claimed seismic effects from
treatments quite different from actual seismic survey sounds or even
reasonable surrogates. However, Payne et al. (2009) reported no
statistical differences in mortality/morbidity between control and
exposed groups of capelin eggs or monkfish larvae. Saetre and Ona
(1996) applied a `worst-case scenario' mathematical model to
investigate the effects of seismic energy on fish eggs and larvae. They
concluded that mortality rates caused by exposure to seismic surveys
are so low, as compared to natural mortality rates, that the impact of
seismic surveying on recruitment to a fish stock must be regarded as
insignificant.
Physiological Effects--Physiological effects refer to cellular and/
or biochemical responses of fish to acoustic stress. Such stress
potentially could affect fish populations by increasing mortality or
reducing reproductive success. Primary and secondary stress responses
of fish after exposure to seismic survey sound appear to be temporary
in all studies done to date (Sverdrup et al., 1994; Santulli et al.,
1999; McCauley et al., 2000a,b). The periods necessary for the
biochemical changes to return to normal are variable and depend on
numerous aspects of the biology of the species and of the sound
stimulus.
Behavioral Effects--Behavioral effects include changes in the
distribution, migration, mating, and catchability of fish populations.
Studies investigating the possible effects of sound (including seismic
survey sound) on fish behavior have been conducted on both uncaged and
caged individuals (e.g., Chapman and Hawkins, 1969; Pearson et al.,
1992; Santulli et al., 1999; Wardle et al., 2001; Hassel et al., 2003).
Typically, in these studies fish exhibited a sharp startle response at
the onset of a sound followed by habituation and a return to normal
behavior after the sound ceased.
The Minerals Management Service (MMS, 2005) assessed the effects of
a proposed seismic survey in Cook Inlet. The seismic survey proposed
using three vessels, each towing two, four-airgun arrays ranging from
1,500 to 2,500 in\3\. MMS noted that the impact to fish populations in
the survey area and adjacent waters would likely be very low and
temporary. MMS also concluded that seismic surveys may displace the
pelagic fishes from the area temporarily when airguns are in use.
However, fishes displaced and avoiding the airgun noise are likely to
backfill the survey area in minutes to hours after cessation of seismic
testing. Fishes not dispersing from the airgun noise (e.g., demersal
species) may startle and move short distances to avoid airgun
emissions.
In general, any adverse effects on fish behavior or fisheries
attributable to seismic testing may depend on the species in question
and the nature of the fishery (season, duration, fishing method). They
may also depend on the age of the fish, its motivational state, its
size, and numerous other factors that are difficult, if not impossible,
to quantify at this point, given such limited data on effects of
airguns on fish, particularly under realistic at-sea conditions.
Anticipated Effects on Invertebrates
The existing body of information on the impacts of seismic survey
sound on marine invertebrates is very limited. However, there is some
unpublished and very limited evidence of the potential for adverse
effects on invertebrates, thereby justifying further discussion and
analysis of this issue. The three types of potential effects of
exposure to seismic surveys on marine invertebrates are pathological,
physiological, and behavioral. Based on the physical structure of their
sensory organs, marine invertebrates appear to be specialized to
respond to particle displacement components of an impinging sound field
and not to the pressure component (Popper et al., 2001).
The only information available on the impacts of seismic surveys on
marine invertebrates involves studies of individuals; there have been
no studies at the population scale. Thus, available information
provides limited insight on possible real-world effects at the regional
or ocean scale. The most important aspect of potential impacts concerns
how exposure to seismic
[[Page 17375]]
survey sound ultimately affects invertebrate populations and their
viability, including availability to fisheries.
Literature reviews of the effects of seismic and other underwater
sound on invertebrates were provided by Moriyasu et al. (2004) and
Payne et al. (2008). The following sections provide a synopsis of
available information on the effects of exposure to seismic survey
sound on species of decapod crustaceans and cephalopods, the two
taxonomic groups of invertebrates on which most such studies have been
conducted. The available information is from studies with variable
degrees of scientific soundness and from anecdotal information. A more
detailed review of the literature on the effects of seismic survey
sound on invertebrates is provided in Appendix D of the NSF/USGS PEIS.
Pathological Effects--In water, lethal and sub-lethal injury to
organisms exposed to seismic survey sound appears to depend on at least
two features of the sound source: (1) The received peak pressure; and
(2) the time required for the pressure to rise and decay. Generally, as
received pressure increases, the period for the pressure to rise and
decay decreases, and the chance of acute pathological effects
increases. For the type of airgun array planned for the proposed
program, the pathological (mortality) zone for crustaceans and
cephalopods is expected to be within a few meters of the seismic
source, at most; however, very few specific data are available on
levels of seismic signals that might damage these animals. This premise
is based on the peak pressure and rise/decay time characteristics of
seismic airgun arrays currently in use around the world.
Some studies have suggested that seismic survey sound has a limited
pathological impact on early developmental stages of crustaceans
(Pearson et al., 1994; Christian et al., 2003; DFO, 2004). However, the
impacts appear to be either temporary or insignificant compared to what
occurs under natural conditions. Controlled field experiments on adult
crustaceans (Christian et al., 2003, 2004; DFO, 2004) and adult
cephalopods (McCauley et al., 2000a,b) exposed to seismic survey sound
have not resulted in any significant pathological impacts on the
animals. It has been suggested that exposure to commercial seismic
survey activities has injured giant squid (Guerra et al., 2004), but
the article provides little evidence to support this claim. Tenera
Environmental (2011b) reported that Norris and Mohl (1983, summarized
in Mariyasu et al., 2004) observed lethal effects in squid (Loligo
vulgaris) at levels of 246 to 252 dB after 3 to 11 minutes.
Andre et al. (2011) exposed four species of cephalopods (Loligo
vulgaris, Sepia officinalis, Octopus vulgaris, and Ilex coindetii),
primarily cuttlefish, to two hours of continuous 50 to 400 Hz
sinusoidal wave sweeps at 1575 dB re 1 [mu]Pa while captive
in relatively small tanks. They reported morphological and
ultrastructural evidence of massive acoustic trauma (i.e., permanent
and substantial alterations [lesions] of statocyst sensory hair cells)
to the exposed animals that increased in severity with time, suggesting
that cephalopods are particularly sensitive to low frequency sound. The
received SPL was reported as 1575 dB re 1 [mu]Pa, with peak
levels at 175 dB re 1 [mu]Pa. As in the McCauley et al. (2003) paper on
sensory hair cell damage in pink snapper as a result of exposure to
seismic sound, the cephalopods were subjected to higher sound levels
than they would be under natural conditions, and they were unable to
swim away from the sound source.
Physiological Effects--Physiological effects refer mainly to
biochemical responses by marine invertebrates to acoustic stress. Such
stress potentially could affect invertebrate populations by increasing
mortality or reducing reproductive success. Primary and secondary
stress responses (i.e., changes in haemolymph levels of enzymes,
proteins, etc.) of crustaceans have been noted several days or months
after exposure to seismic survey sounds (Payne et al., 2007). It was
noted however, than no behavioral impacts were exhibited by crustaceans
(Christian et al., 2003, 2004; DFO, 2004). The periods necessary for
these biochemical changes to return to normal are variable and depend
on numerous aspects of the biology of the species and of the sound
stimulus.
Behavioral Effects--There is increasing interest in assessing the
possible direct and indirect effects of seismic and other sounds on
invertebrate behavior, particularly in relation to the consequences for
fisheries. Changes in behavior could potentially affect such aspects as
reproductive success, distribution, susceptibility to predation, and
catchability by fisheries. Studies investigating the possible
behavioral effects of exposure to seismic survey sound on crustaceans
and cephalopods have been conducted on both uncaged and caged animals.
In some cases, invertebrates exhibited startle responses (e.g., squid
in McCauley et al., 2000a,b). In other cases, no behavioral impacts
were noted (e.g., crustaceans in Christian et al., 2003, 2004; DFO
2004). There have been anecdotal reports of reduced catch rates of
shrimp shortly after exposure to seismic surveys; however, other
studies have not observed any significant changes in shrimp catch rate
(Andriguetto-Filho et al., 2005). Similarly, Parry and Gason (2006) did
not find any evidence that lobster catch rates were affected by seismic
surveys. Any adverse effects on crustacean and cephalopod behavior or
fisheries attributable to seismic survey sound depend on the species in
question and the nature of the fishery (season, duration, fishing
method).
Proposed Mitigation
In order to issue an Incidental Take Authorization (ITA) under
section 101(a)(5)(D) of the MMPA, NMFS must set forth the permissible
methods of taking pursuant to such activity, and other means of
effecting the least practicable impact on such species or stock and its
habitat, paying particular attention to rookeries, mating grounds, and
areas of similar significance, and the availability of such species or
stock for taking for certain subsistence uses.
L-DEO has reviewed the following source documents and have
incorporated a suite of appropriate mitigation measures into their
project description.
(1) Protocols used during previous NSF and USGS-funded seismic
research cruises as approved by NMFS and detailed in the recently
completed ``Final Programmatic Environmental Impact Statement/Overseas
Environmental Impact Statement for Marine Seismic Research Funded by
the National Science Foundation or Conducted by the U.S. Geological
Survey;''
(2) Previous IHA applications and IHAs approved and authorized by
NMFS; and
(3) Recommended best practices in Richardson et al. (1995), Pierson
et al. (1998), and Weir and Dolman, (2007).
To reduce the potential for disturbance from acoustic stimuli
associated with the activities, L-DEO and/or its designees have
proposed to implement the following mitigation measures for marine
mammals:
(1) Planning Phase;
(2) Proposed exclusion zones around the airgun(s);
(3) Power-down procedures;
(4) Shut-down procedures;
(5) Ramp-up procedures; and
(6) Special procedures for situations or species of concern.
[[Page 17376]]
Planning Phase--Mitigation of potential impacts from the proposed
activities begins during the planning phases of the proposed
activities. Part of the considerations was whether thy research
objectives could be met with a smaller source than the full, 36-airgun
array (6,600 in\3\) used on the Langseth, and it was decided that the
scientific objectives could be met using two 18-airgun arrays,
operating in ``flip-flop'' mode, and towed at a depth of approximately
9 m. Thus, the source volume would not exceed 3,300 in\3\ at any time.
The PIs worked with L-DEO and NSF to identify potential time periods to
carry out the survey taking into consideration key factors such as
environmental conditions (i.e., the seasonal presence of marine mammals
and other protected species), weather conditions, equipment, and
optimal timing for other proposed seismic surveys using the Langseth.
Most marine mammal species are expected to occur in the area year-
round, so altering the timing of the proposed project likely would
result in no net benefits for those species.
Proposed Exclusion Zones--L-DEO use radii to designate exclusion
and buffer zones and to estimate take for marine mammals. Table 1
(presented earlier in this document) shows the distances at which one
would expect marine mammal exposures to received sound levels (160 and
180/190 dB) from the 18 airgun array and a single airgun. (The 180 dB
and 190 dB level shut-down criteria are applicable to cetaceans and
pinnipeds, respectively, as specified by NMFS [2000].) L-DEO used these
levels to establish the exclusion and buffer zones.
If the PSVO detects marine mammal(s) within or about to enter the
appropriate exclusion zone, the Langseth crew will immediately power-
down the airgun array, or perform a shut-down if necessary (see ``Shut-
down Procedures''). Table 1 summarizes the calculated distances at
which sound levels (160 and 180 dB [rms]) are expected to be received
from the 18 airgun array operating in and the single airgun operating
in deep water depths. Received sound levels have been calculated by L-
DEO, in relation to distance and direction from the airguns, for the 18
airgun array and for the single 1900LL 40 in\3\ airgun, which will be
used during power-downs.
If the PSVO detects marine mammal(s) within or about to enter the
appropriate exclusion zone, the airguns will be powered-down (or shut-
down, if necessary) immediately.
Power-down Procedures--A power-down involves decreasing the number
of airguns in use to one airgun, such that the radius of the 180 dB
zone is decreased to the extent that the observed marine mammal(s) are
no longer in or about to enter the exclusion zone for the full airgun
array. A power-down of the airgun array can also occur when the vessel
is moving from the end of one seismic trackline to the start of the
next trackline. During a power-down for mitigation, L-DEO will operate
one airgun. The continued operation of one airgun is intended to (a)
alert marine mammals to the presence of the seismic vessel in the area;
and, (b) retain the option of initiating a ramp-up to full operations
under poor visibility conditions. In contrast, a shut-down occurs when
all airgun activity is suspended.
If the PSVO detects a marine mammal outside the exclusion zone and
is likely to enter the exclusion zone, L-DEO will power-down the
airguns to reduce the size of the 180 dB exclusion zone before the
animal is within the exclusion zone. Likewise, if a mammal is already
within the exclusion zone, when first detected L-DEO will power-down
the airguns immediately. During a power-down of the airgun array, L-DEO
will operate the single 40 in\3\ airgun, which has a smaller exclusion
zone. If the PSVO detects a marine mammal within or near the smaller
exclusion zone around that single airgun (see Table 1), L-DEO will
shut-down the airgun (see next section).
Resuming Airgun Operations After a Power-down--Following a power-
down, the Langseth will not resume full airgun activity until the
marine mammal has cleared the 180 or 190 dB exclusion zone (see Table
1). The PSO will consider the animal to have cleared the exclusion zone
if:
The observer has visually observed the animal leave the
exclusion zone, or
An observer has not sighted the animal within the
exclusion zone for 15 minutes for species with shorter dive durations
(i.e., small odontocetes or pinnipeds), or 30 minutes for species with
longer dive durations (i.e., mysticetes and large odontocetes,
including sperm, pygmy sperm, dwarf sperm, and beaked whales); or
The vessel has transited outside the original 180 dB
exclusion zone after an 8 minute period minute wait period.
The Langseth crew will resume operating the airguns at full power
after 15 minutes of sighting any species with short dive durations
(i.e., small odontocetes or pinnipeds). Likewise, the crew will resume
airgun operations at full power after 30 minutes of sighting any
species with longer dive durations (i.e., mysticetes and large
odontocetes, including sperm, pygmy sperm, dwarf sperm, and beaked
whales).
Because the vessel has transited away from the vicinity of the
original sighting during the 8 minute period, implementing ramp-up
procedures for the full array after an extended power-down (i.e.,
transiting for an additional 35 minutes from the location of initial
sighting) would not meaningfully increase the effectiveness of
observing marine mammals approaching or entering the exclusion zone for
the full source level and would not further minimize the potential for
take. The Langseth's PSOs are continually monitoring the exclusion zone
for the full source level while the mitigation airgun is firing. On
average, PSOs can observe to the horizon (10 km or 5.4 nmi) from the
height of the Langseth's observation deck and should be able to state
with a reasonable degree of confidence whether a marine mammal would be
encountered within this distance before resuming airgun operations at
full power.
Shut-down Procedures--L-DEO will shut-down the operating airgun(s)
if a marine mammal is seen within or approaching the exclusion zone for
the single airgun. L-DEO will implement a shut-down:
(1) If an animal enters the exclusion zone of the single airgun
after L-DEO has initiated a power-down; or
(2) If an animal is initially seen within the exclusion zone of the
single airgun when more than one airgun (typically the full airgun
array) is operating (and it is not practical or adequate to reduce
exposure to less than 180 dB [rms]).
Considering the conservation status for the North Atlantic right
whale, the airguns will be shut-down immediately in the unlikely event
that this species is observed, regardless of the distance from the
Langseth. Ramp-up will only begin if the North Atlantic right whale has
not been seen for 30 minutes.
Resuming Airgun Operations After a Shut-down--Following a shut-down
in excess of 8 minutes, the Langseth crew will initiate a ramp-up with
the smallest airgun in the array (40 in\3\). The crew will turn on
additional airguns in a sequence such that the source level of the
array will increase in steps not exceeding 6 dB per five-minute period
over a total duration of approximately 30 minutes. During ramp-up, the
PSOs will monitor the exclusion zone, and if he/she sights a marine
mammal, the Langseth crew will implement a power-down or shut-down as
though the full airgun array were operational.
During periods of active seismic operations, there are occasions
when the Langseth crew will need to temporarily
[[Page 17377]]
shut-down the airguns due to equipment failure or for maintenance. In
this case, if the airguns are inactive longer than eight minutes, the
crew will follow ramp-up procedures for a shut-down described earlier
and the PSOs will monitor the full exclusion zone and will implement a
power-down or shut-down if necessary.
If the full exclusion zone is not visible to the PSO for at least
30 minutes prior to the start of operations in either daylight or
nighttime, the Langseth crew will not commence ramp-up unless at least
one airgun (40 in\3\ or similar) has been operating during the
interruption of seismic survey operations. Given these provisions, it
is likely that the vessel's crew will not ramp-up the airgun array from
a complete shut-down at night or in thick fog, because the outer part
of the zone for that array will not be visible during those conditions.
If one airgun has operated during a power-down period, ramp-up to
full power will be permissible at night or in poor visibility, on the
assumption that marine mammals will be alerted to the approaching
seismic vessel by the sounds from the single airgun and could move
away. The vessel's crew will not initiate ramp-up of the airguns if a
marine mammal is sighted within or near the applicable exclusion zones
during the day or close to the vessel at night.
Ramp-up Procedures--Ramp-up of an airgun array provides a gradual
increase in sound levels, and involves a step-wise increase in the
number and total volume of airguns firing until the full volume of the
airgun array is achieved. The purpose of a ramp-up is to ``warn''
marine mammals in the vicinity of the airguns, and to provide the time
for them to leave the area and thus avoid any potential injury or
impairment of their hearing abilities. L-DEO will follow a ramp-up
procedure when the airgun array begins operating after an 8 minute
period without airgun operations or when a power-down or shut down has
exceeded that period. L-DEO has used similar periods (approximately 8
to 10 min) during previous L-DEO surveys.
Ramp-up will begin with the smallest airgun in the array (40
in\3\). Airguns will be added in a sequence such that the source level
of the array will increase in steps not exceeding six dB per five
minute period over a total duration of approximately 35 minutes. During
ramp-up, the PSOs will monitor the exclusion zone, and if marine
mammals are sighted, L-DEO will implement a power-down or shut-down as
though the full airgun array were operational.
If the complete exclusion zone has not been visible for at least 30
minutes prior to the start of operations in either daylight or
nighttime, L-DEO will not commence the ramp-up unless at least one
airgun (40 in\3\ or similar) has been operating during the interruption
of seismic survey operations. Given these provisions, it is likely that
the airgun array will not be ramped-up from a complete shut-down at
night or in thick fog, because the outer part of the exclusion zone for
that array will not be visible during those conditions. If one airgun
has operated during a power-down period, ramp-up to full power will be
permissible at night or in poor visibility, on the assumption that
marine mammals will be alerted to the approaching seismic vessel by the
sounds from the single airgun and could move away. L-DEO will not
initiate a ramp-up of the airguns if a marine mammal is sighted within
or near the applicable exclusion zones.
Use of a Small-Volume Airgun During Turns and Maintenance
Throughout the seismic survey, particularly during turning
movements, and short-duration equipment maintenance activities, L-DEO
will employ the use of a small-volume airgun (i.e., 40 in\3\
``mitigation airgun'') to deter marine mammals from being within the
immediate area of the seismic operations. The mitigation airgun would
be operated at approximately one shot per minute and would not be
operated for longer than three hours in duration (turns may last two to
three hours for the proposed project).
During turns or brief transits (e.g., less than three hours)
between seismic tracklines, one mitigation airgun will continue
operating. The ramp-up procedure will still be followed when increasing
the source levels from one airgun to the full airgun array. However,
keeping one airgun firing will avoid the prohibition of a ``cold
start'' during darkness or other periods of poor visibility. Through
use of this approach, seismic operations may resume without the 30
minute observation period of the full exclusion zone required for a
``cold start,'' and without ramp-up if operating with the mitigation
airgun for under 8 minutes, or with ramp-up if operating with the
mitigation airgun over 8 minutes. PSOs will be on duty whenever the
airguns are firing during daylight, during the 30 minute periods prior
to ramp-ups.
Special Procedures for Situations or Species of Concern--It is
unlikely that a North Atlantic right whale would be encountered, but if
so, the airguns will be shut-down immediately if one is sighted at any
distance from the vessel because of its rarity and conservation status.
The airgun array shall not resume firing until 30 minutes after the
last documented whale visual sighting. Concentrations of humpback, sei,
fin, blue, and/or sperm whales will be avoided if possible (i.e.,
exposing concentrations of animals to 160 dB), and the array will be
powered-down if necessary. For purposes of this proposed survey, a
concentration or group of whales will consist of three or more
individuals visually sighted that do not appear to be traveling (e.g.,
feeding, socializing, etc.).
NMFS has carefully evaluated the applicant's proposed mitigation
measures and has considered a range of other measures in the context of
ensuring that NMFS prescribes the means of effecting the least
practicable adverse impact on the affected marine mammal species and
stocks and their habitat. NMFS's evaluation of potential measures
included consideration of the following factors in relation to one
another:
(1) The manner in which, and the degree to which, the successful
implementation of the measure is expected to minimize adverse impacts
to marine mammals;
(2) The proven or likely efficacy of the specific measure to
minimize adverse impacts as planned; and
(3) The practicability of the measure for applicant implementation.
Proposed Monitoring and Reporting
In order to issue an ITA for an activity, section 101(a)(5)(D) of
the MMPA states that NMFS must set forth ``requirements pertaining to
the monitoring and reporting of such taking.'' The MMPA implementing
regulations at 50 CFR 216.104(a)(13) indicate that requests for IHAs
must include the suggested means of accomplishing the necessary
monitoring and reporting that will result in increased knowledge of the
species and of the level of taking or impacts on populations of marine
mammals that are expected to be present in the action area.
Proposed Monitoring
L-DEO proposes to sponsor marine mammal monitoring during the
proposed project, in order to implement the proposed mitigation
measures that require real-time monitoring, and to satisfy the
anticipated monitoring requirements of the IHA. L-DEO's proposed
``Monitoring Plan'' is described below this section. The monitoring
work described here has
[[Page 17378]]
been planned as a self-contained project independent of any other
related monitoring projects that may be occurring simultaneously in the
same region. L-DEO is prepared to discuss coordination of their
monitoring program with any related work that might be done by other
groups insofar as this is practical and desirable.
Vessel-Based Visual Monitoring
PSVOs will be based aboard the seismic source vessel and will watch
for marine mammals near the vessel during daytime airgun operations and
during any ramp-ups of the airguns at night. PSVOs will also watch for
marine mammals near the seismic vessel for at least 30 minutes prior to
the start of airgun operations after an extended shut-down (i.e.,
greater than approximately 8 minutes for this proposed cruise). When
feasible, PSVOs will conduct observations during daytime periods when
the seismic system is not operating (such as during transits) for
comparison of sighting rates and behavior with and without airgun
operations and between acquisition periods. Based on PSVO observations,
the airguns will be powered-down or shut-down when marine mammals are
observed within or about to enter a designated exclusion zone.
During seismic operations in the northeast Atlantic Ocean off of
Spain, at least five PSOs (four PSVOs and one PSAO) will be based
aboard the Langseth. L-DEO will appoint the PSOs with NMFS's
concurrence. Observations will take place during ongoing daytime
operations and nighttime ramp-ups of the airguns. During the majority
of seismic operations, two PSVOs will be on duty from the observation
tower (i.e., the best available vantage point on the source vessel) to
monitor marine mammals near the seismic vessel. Use of two simultaneous
PSVOs will increase the effectiveness of detecting animals near the
source vessel. However, during meal times and bathroom breaks, it is
sometimes difficult to have two PSVOs on effort, but at least one PSVO
will be on duty. PSVO(s) will be on duty in shifts no longer than 4
hours in duration.
Two PSVOs will also be on visual watch during all daytime ramp-ups
of the seismic airguns. A third PSAO will monitor the PAM equipment 24
hours a day to detect vocalizing marine mammals present in the action
area. In summary, a typical daytime cruise would have scheduled two
PSVOs on duty from the observation tower, and a third PSAO on PAM.
Other crew will also be instructed to assist in detecting marine
mammals and implementing mitigation requirements (if practical). Before
the start of the seismic survey, the crew will be given additional
instruction on how to do so.
The Langseth is a suitable platform for marine mammal observations.
When stationed on the observation platform, the eye level will be
approximately 21.5 m (70.5 ft) above sea level, and the PSVO will have
a good view around the entire vessel. During daytime, the PSVO(s) will
scan the area around the vessel systematically with reticle binoculars
(e.g., 7 x 50 Fujinon), Big-eye binoculars (25 x 150), and with the
naked eye. During darkness, night vision devices will be available (ITT
F500 Series Generation 3 binocular--image intensifier or equivalent),
when required. Laser range-finding binoculars (Leica LRF 1200 laser
rangefinder or equivalent) will be available to assist with distance
estimation. Those are useful in training observers to estimate
distances visually, but are generally not useful in measuring distances
to animals directly; that is done primarily with the reticles in the
binoculars.
When marine mammals are detected within or about to enter the
designated exclusion zone, the airguns will immediately be powered-down
or shut-down if necessary. The PSVO(s) will continue to maintain watch
to determine when the animal(s) are outside the exclusion zone by
visual confirmation. Airgun operations will not resume until the animal
is confirmed to have left the exclusion zone, or if not observed after
15 minutes for species with shorter dive durations (small odontocetes
and pinnipeds) or 30 minutes for species with longer dive durations
(mysticetes and large odontocetes, including sperm, pygmy sperm, dwarf
sperm, killer, and beaked whales).
Vessel-Based Passive Acoustic Monitoring
Vessel-based, towed PAM will complement the visual monitoring
program, when practicable. Visual monitoring typically is not effective
during periods of poor visibility or at night, and even with good
visibility, is unable to detect marine mammals when they are below the
surface or beyond visual range. PAM can be used in addition to visual
observations to improve detection, identification, and localization of
cetaceans. The PAM will serve to alert visual observers (if on duty)
when vocalizing cetaceans are detected. It is only useful when marine
mammals call, but it does not depend on good visibility. It will be
monitored in real time so that the PSVOs can be advised when cetaceans
are detected.
The PAM system consists of hardware (i.e., hydrophones) and
software. The ``wet end'' of the system consists of a towed hydrophone
array that is connected to the vessel by a tow cable. The tow cable is
250 m (820.2 ft) long, and the hydrophones are fitted in the last 10 m
(32.8 ft) of cable. A depth gauge is attached to the free end of the
cable, and the cable is typically towed at depths less than 20 m (65.6
ft). The array will be deployed from a winch located on the back deck.
A deck cable will connect from the winch to the main computer
laboratory where the acoustic station, signal conditioning, and
processing system will be located. The acoustic signals received by the
hydrophones are amplified, digitized, and then processed by the
Pamguard software. The system can detect marine mammal vocalizations at
frequencies up to 250 kHz.
One PSAO, an expert bioacoustician (in addition to the four PSVOs)
with primary responsibility for PAM, will be onboard the Langseth. The
towed hydrophones will ideally be monitored by the PSAO 24 hours per
day while at the proposed seismic survey area during airgun operations,
and during most periods when the Langseth is underway while the airguns
are not operating. However, PAM may not be possible if damage occurs to
the array or back-up systems during operations. The primary PAM
streamer on the Langseth is a digital hydrophone streamer. Should the
digital streamer fail, back-up systems should include an analog spare
streamer and a hull-mounted hydrophone. One PSAO will monitor the
acoustic detection system by listening to the signals from two channels
via headphones and/or speakers and watching the real-time
spectrographic display for frequency ranges produced by cetaceans. The
PSAO monitoring the acoustical data will be on shift for one to six
hours at a time. All PSOs are expected to rotate through the PAM
position, although the expert PSAO (most experienced) will be on PAM
duty more frequently.
When a vocalization is detected while visual observations (during
daylight) are in progress, the PSAO will contact the PSVO immediately,
to alert him/her to the presence of cetaceans (if they have not already
been seen), and to allow a power-down or shut-down to be initiated, if
required. When bearings (primary and mirror-image) to calling
cetacean(s) are determined, the bearings will be relayed to the PSVO(s)
to help him/her sight the calling animal. During non-daylight hours,
when a cetacean is detected by acoustic monitoring and may be close to
the source vessel, the
[[Page 17379]]
Langseth crew will be notified immediately so that the proper
mitigation measure may be implemented.
The information regarding the call will be entered into a database.
Data entry will include an acoustic encounter identification number,
whether it was linked with a visual sighting, date, time when first and
last heard and whenever any additional information was recorded,
position and water depth when first detected, bearing if determinable,
species or species group (e.g., unidentified dolphin, sperm whale),
types and nature of sounds heard (e.g., clicks, continuous, sporadic,
whistles, creaks, burst pulses, strength of signal, etc.), and any
other notable information. The acoustic detection can also be recorded
for further analysis.
PSO Data and Documentation
PSVOs will record data to estimate the numbers of marine mammals
exposed to various received sound levels and to document apparent
disturbance reactions or lack thereof. Data will be used to estimate
numbers of animals potentially `taken' by harassment. They will also
provide information needed to order a power-down or shut-down of the
airguns when a marine mammal is within or near the exclusion zone.
Observations will also be made during daytime periods when the Langseth
is underway without seismic operations. There will also be
opportunities to collect baseline biological data during the transits
to, from, and through the study area.
When a 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 the airguns or vessel (e.g., none, avoidance,
approach, paralleling, etc.), and behavioral pace.
2. Time, location, heading, speed, activity of the vessel, sea
state, visibility, 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 observations and ramp-ups, power-downs, or shut-downs will be
recorded in a standardized format. The PSOs will record this
information onto datasheets. During periods between watches and periods
when operations are suspended, those data will be entered into a laptop
computer running a custom computer database. The accuracy of the data
entry will be verified by computerized data validity 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, and 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.
5. Data on the behavior and movement patterns of marine mammals
seen at times with and without seismic activity.
L-DEO will submit a comprehensive report to NMFS and NSF within 90
days after the end of the cruise. The report will describe the
operations that were conducted and sightings of marine mammals near the
operations. The report will provide full documentation of methods,
results, and interpretation pertaining to all monitoring. The 90-day
report will summarize the dates and locations of seismic operations,
and all marine mammal sightings (i.e., dates, times, locations,
activities, associated seismic survey activities, and associated PAM
detections). The report will minimally include:
Summaries of monitoring effort--total hours, total
distances, and distribution of marine mammals through the study period
accounting for Beaufort sea state and other factors affecting
visibility and detectability of marine mammals;
Analyses of the effects of various factors influencing
detectability of marine mammals including Beaufort sea state, number of
PSOs, and fog/glare;
Species composition, occurrence, and distribution of
marine mammals sightings including date, water depth, numbers, age/
size/gender, and group sizes; and analyses of the effects of seismic
operations;
Sighting rates of marine mammals during periods with and
without airgun activities (and other variables that could affect
detectability);
Initial sighting distances versus airgun activity state;
Closest point of approach versus airgun activity state;
Observed behaviors and types of movements versus airgun
activity state;
Numbers of sightings/individuals seen versus airgun
activity state; and
Distribution around the source vessel versus airgun
activity state.
The report will also include estimates of the number and nature of
exposures that could result in ``takes'' of marine mammals by
harassment or in other ways. After the report is considered final, it
will be publicly available on the NMFS and NSF Web sites at: http://www.nmfs.noaa.gov/pr/permits/incidental.htm#iha and http://www.nsf.gov/geo/oce/encomp/index.jsp.
In the unanticipated event that the specified activity clearly
causes the take of a marine mammal in a manner not permitted by the
authorization (if issued), such as an injury, serious injury, or
mortality (e.g., ship-strike, gear interaction, and/or entanglement),
the L-DEO shall immediately cease the specified activities and
immediately report the incident to the Incidental Take Program
Supervisor, Permits and Conservation Division, Office of Protected
Resources, NMFS, at 301-427-8401 and/or by email to
[email protected] and [email protected]. The report must
include the following information:
Time, date, and location (latitude/longitude) of the incident;
Name and type of vessel involved;
Vessel's speed during and leading up to the incident;
Description of the incident;
Status of all sound source used in the 24 hours preceding
the incident;
Water depth;
Environmental conditions (e.g., wind speed and direction,
Beaufort sea state, cloud cover, and visibility);
Description of all marine mammal observations in the 24
hours preceding the incident;
Species identification or description of animal(s)
involved;
Fate of the animal(s); and
Photographs or video footage of the animal(s) (if
equipment is available).
L-DEO shall not resume its activities until NMFS is able to review
the circumstances of the prohibited take. NMFS shall work with L-DEO to
determine what is necessary to minimize the likelihood of further
prohibited take and ensure MMPA compliance. The L-DEO may not resume
their activities until notified by NMFS via letter, email, or
telephone.
In the event that L-DEO discovers an injured or dead marine mammal,
and
[[Page 17380]]
the lead PSO determines that the cause of the injury or death is
unknown and the death is relatively recent (i.e., in less than a
moderate state of decomposition as NMFS describes in the next
paragraph), the L-DEO will immediately report the incident to the
Incidental Take Program Supervisor, Permits and Conservation Division,
Office of Protected Resources, at 301-427-8401 and/or by email to
[email protected] and [email protected]. The report must
include the same information identified in the paragraph above this
section. Activities may continue while NMFS reviews the circumstances
of the incident. NMFS will work with the L-DEO to determine whether
modifications in the activities are appropriate.
In the event that L-DEO discovers an injured or dead marine mammal,
and the lead PSO determines that the injury or death is not associated
with or related to the authorized activities (e.g., previously wounded
animal, carcass with moderate to advanced decomposition, or scavenger
damage), the L-DEO would report the incident to the Incidental Take
Program Supervisor, Permits and Conservation Division, Office or
Protected Resources, at 301-427-8401 and/or by email to
[email protected] and [email protected], within 24 hours
of the discovery. The L-DEO would provide photographs or video footage
(if available) or other documentation of the stranded animal sighting
to NMFS.
Estimated Take by Incidental Harassment
Except with respect to certain activities not pertinent here, 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 [Level A harassment]; 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 [Level B harassment].
Level B harassment is anticipated and proposed to be authorized as
a result of the proposed marine seismic survey in the northeast
Atlantic Ocean. Acoustic stimuli (i.e., increased underwater sound)
generated during the operation of the seismic airgun array are expected
to result in the behavioral disturbance of some marine mammals. There
is no evidence that the planned activities could result in injury,
serious injury, or mortality for which L-DEO seeks the IHA. The
required mitigation and monitoring measures will minimize any potential
risk for injury, serious injury, or mortality.
The following sections describe L-DEO's methods to estimate take by
incidental harassment and present the applicant's estimates of the
numbers of marine mammals that could be affected during the proposed
seismic program in the northeast Atlantic Ocean. The estimates are
based on a consideration of the number of marine mammals that could be
harassed by seismic operations with the 18 airgun array to be used. The
size of the proposed 2D and 3D seismic survey area in 2013 is
approximately 5,834 km (3,150.1 nmi), as depicted in Figure 1 of the
IHA application.
L-DEO assumes that, during simultaneous operations of the airgun
array and the other sources, any marine mammals close enough to be
affected by the multibeam echosounder and sub-bottom profiler would
already be affected by the airguns. However, whether or not the airguns
are operating simultaneously with the other sources, marine mammals are
expected to exhibit no more than short-term and inconsequential
responses to the multibeam echosounder and sub-bottom profiler given
their characteristics (e.g., narrow, downward-directed beam) and other
considerations described previously. Such reactions are not considered
to constitute ``taking'' (NMFS, 2001). Therefore, L-DEO provided no
additional allowance for animals that could be affected by sound
sources other than airguns.
L-DEO used densities presented in the CODA final report for surveys
off northwest Spain in 2007 (Anonymous, 2009; Macleod et al., 2009) to
estimate how many animals could be exposed during the proposed survey.
The density reported for ``unidentified large whale'' was allocated to
the humpback whale because there are a number of sightings of humpback
whales off northwest Spain, although it wasn't sighted in the CODA
surveys and most other large whales were. Macleod et al. (2008) didn't
provide densities for beaked whale species, only ``beaked whales,''
therefore the density for beaked whales was allocated to Cuvier's
beaked whale, as this was the most numerous species of beaked whale
sighted during surveys off northwest Spain (see Basto d'Anstrade,
2008). Also, the CODA report (Anonymous, 2008) discussed two predicted
high-density areas for beaked whales, in the most north-westerly
section (Sowerby's beaked whale and northern bottlenose whale) and the
most south-easterly section, the Gulf of Biscay (Cuvier's beaked
whale). Except for beaked whales and bottlenose dolphins, all reported
densities were corrected for trackline detection probability
([fnof][0]) and availability (g[0]) biases by the authors of the CODA
report. L-DEO chose not to correct the other densities, [fnof](0) and
g(0) are specific to the location and cetacean habitat. Although there
is some uncertainty about the representativeness of the data and
assumptions used in the calculations below, the approach used here is
believed to be the best available approach. The CODA surveys were in
July, 2007 (versus June to mid-July, 2013 for the proposed seismic
survey), and CODA survey block 3, the closest to the proposed offshore
survey area, includes waters closer to shore and is somewhat farther
north (43 to 45[deg] versus 42[deg] North) and extends west to the
north of Spain towards the Bay of Biscay.
The estimated numbers of individuals potentially exposed presented
below are based on the 160 dB (rms) criterion currently used for all
cetaceans. It is assumed that marine mammals exposed to airgun sounds
that strong could change their behavior sufficiently to be considered
``taken by harassment.'' Table 3 shows the density estimates calculated
as described above and the estimates of the number of different
individual marine mammals that potentially could be exposed to greater
than or equal to 160 dB (rms) during the seismic survey if no animals
moved away from the survey vessel. The requested take authorization is
given in the far right column of Table 3. For species for which
densities were not calculated as described above, but for which there
were Ocean Biogeographic Information System (OBIS) sightings around the
Azores, L-DEO has included a requested take authorization for the mean
group size for the species.
It should be noted that the following estimates of exposures to
various sound levels assume that the proposed survey would be
completed; in fact, the esonified areas calculated using the planned
number of line-kilometers have been increased by 25% to accommodate
turns, lines that may need to be repeated, equipment testing, etc. As
typical during offshore ship surveys, inclement weather and equipment
malfunctions are likely to cause delays and may limit the number of
useful line-kilometers of seismic operations that can be undertaken.
Also, any marine mammal sightings within or near the designated
exclusion zones would result in shut-down of seismic operations as a
mitigation measure. Thus, the following estimates of the numbers of
marine mammals potentially exposed to 160 dB
[[Page 17381]]
(rms) sounds are precautionary and probably overestimate the actual
numbers of marine mammals that could be involved. These estimates
assume that there would be no weather, equipment, or mitigation delays,
which is highly unlikely.
The number of different individuals that could be exposed to airgun
sounds with received levels greater than or equal to 160 dB (rms) on
one or more occasions can be estimated by considering the total marine
area that would be within the 160 dB (rms) radius around the operating
seismic source on at least one occasion, along with the expected
density of animals in the area. The number of possible exposures
(including repeated exposures of the same individuals) can be estimated
by considering the total marine area that would be within the 160 dB
radius around the operating airguns, including areas of overlap. During
the proposed survey, the transect lines are closely spaced relative to
the 160 dB distance. Thus, the area including overlap is 8.2 times the
area excluding overlap, so a marine mammal that stayed in the survey
area during the entire survey could be exposed approximately 8 times,
on average. However, it is unlikely that a particular animal would stay
in the area during the entire survey. The numbers of different
individuals potentially exposed to greater than or equal to 160 dB
(rms) were calculated by multiplying the expected species density times
the anticipated area to be ensonified to that level during airgun
operations excluding overlap. The area expected to be ensonified was
determined by entering the planned survey lines into a MapInfo GIS,
using the GIS to identify the relevant areas by ``drawing'' the
applicable 160 dB buffer zone (see Table 1) around each seismic line,
and then calculating the total area within the buffer zone.
Table 3--Estimated Densities of Marine Mammal Species and Estimates of Possible Numbers of Marine Mammals
Exposed to Sound Levels >=160 dB During L-DEO's Proposed Seismic Survey in the Northeast Atlantic Ocean (in the
Deep Galicia Basin West of Spain), June to July, 2013
----------------------------------------------------------------------------------------------------------------
Calculated take
authorization
[i.e., estimated Requested take Approximate
Reported/ number of authorization percentage of
estimated individuals with additional estimated of
Species density (/km \2\) levels >= 160 dB increase to population
re 1 [micro]Pa] group size) (requested take)
(includes 25% \1\
contingency)
----------------------------------------------------------------------------------------------------------------
Mysticetes:
North Atlantic right whale.......... 0 0 0 0
Humpback whale...................... 0.001 8 8 0.07 (0.07)
Minke whale......................... 0 0 3 0 (<0.01)
Sei whale........................... 0.002 16 16 0.13 (0.13)
Fin whale........................... 0.019 153 153 0.62 (0.62)
Blue whale.......................... 0 0 2 0 (0.21)
Odontocetes:
Sperm whale......................... 0.003 24 24 0.18 (0.18)
Kogia spp. (Pygmy and dwarf sperm 0 0 0 0 (0)
whale).............................
Cuvier's beaked whale............... 0.004 32 32 0.46 (0.46)
Northern bottlenose whale........... 0 0 4 0 (0.01)
Mesoplodon spp. (i.e., True's, 0 0 7 0 (0.1)
Gervais', Sowerby's, and
Blainville's beaked whale..........
Bottlenose dolphin.................. 0.005 40 40 0.21 (0.21)
Atlantic spotted dolphin............ 0 0 0 0 (0)
Striped dolphin..................... 0.047 378 378 0.56 (0.56)
Short-beaked common dolphin......... 0.077 620 620 0.53 (0.53)
Risso's dolphin..................... 0 0 4 0 (0.02)
Pygmy killer whale.................. 0 0 0 NA (NA)
False killer whale.................. 0 0 10 NA (NA)
Killer whale........................ 0 0 5 NA (NA)
Short-finned pilot whale............ 0 0 5 0 (<0.01)
Long-finned pilot whale............. 0.001 8 8 <0.001 (<0.01)
----------------------------------------------------------------------------------------------------------------
NA = Not available or not assessed.
\1\ Stock sizes are best populations from NMFS Stock Assessment Reports (see Table 2 above).
\2\ Requested take authorization was increased to group size for species for which densities were not available
but that have been sighted near the proposed survey area.
Applying the approach described above, approximately 6,437 km\2\
(1,876.7 nmi\2\) (approximately 8,046 km\2\ [2,345.8 nmi\2\] including
the 25% contingency) would be within the 160 dB isopleth on one or more
occasions during the proposed survey. Because this approach does not
allow for turnover in the marine mammal populations in the area during
the course of the survey, the actual number of individuals exposed may
be underestimated, although the conservative (i.e., probably
overestimated) line-kilometer distances used to calculate the area may
offset this. Also, the approach assumes that no cetaceans would move
away or toward the trackline as the Langseth approaches in response to
increasing sound levels before the levels reach 160 dB (rms). Another
way of interpreting the estimates that follow is that they represent
the number of individuals that are expected (in the absence of a
seismic program) to occur in the waters that would be exposed to
greater than or equal to 160 dB (rms).
The estimate of the number of individual cetaceans by species that
could be exposed to seismic sounds with received levels greater than or
equal to 160 dB re 1 [mu]Pa (rms) during
[[Page 17382]]
the proposed survey is (with 25% contingency) as follows: 8 humpback,
16 sei, 153 fin, and 24 sperm, which would represent 0.07, 0.13, 0.61,
and 0.18% of the affected regional populations, respectively. In
addition, 43 beaked whales, (including 32 Cuvier's, 4 northern
bottlenose, and 7 Mesoplodon beaked whales) could be taken by Level B
harassment during the proposed seismic survey, which would represent
0.46, 0.01, and 0.1% of the regional populations. Most of the cetaceans
potentially taken by Level B harassment are delphinids; bottlenose,
striped, and short-beaked common, dolphins, are estimated to be the
most common delphinid species in the area, with estimates of 40, 378,
and 620, which would represent 0.21, 0.56, and 0.53% of the regional
populations, respectively.
Encouraging and Coordinating Research
L-DEO and NSF will coordinate the planned marine mammal monitoring
program associated with the seismic survey with other parties that may
have interest in this area. L-DEO and NSF will coordinate with
applicable U.S. agencies (e.g., NMFS), and will comply with their
requirements.
Negligible Impact and Small Numbers Analyses and Determinations
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.'' In making a negligible impact determination,
NMFS evaluated factors such as:
(1) The number of anticipated injuries, serious injuries, or
mortalities;
(2) The number, nature, and intensity, and duration of Level B
harassment (all relatively limited); and
(3) The context in which the takes occur (i.e., impacts to areas of
significance, impacts to local populations, and cumulative impacts when
taking into account successive/contemporaneous actions when added to
baseline data);
(4) The status of stock or species of marine mammals (i.e.,
depleted, not depleted, decreasing, increasing, stable, impact relative
to the size of the population);
(5) Impacts on habitat affecting rates of recruitment/survival; and
(6) The effectiveness of monitoring and mitigation measures.
As described above and based on the following factors, the
specified activities associated with the marine seismic survey are not
likely to cause PTS, or other non-auditory injury, serious injury, or
death. The factors include:
(1) The likelihood that, given sufficient notice through relatively
slow ship speed, marine mammals are expected to move away from a noise
source that is annoying prior to its becoming potentially injurious;
(2) The potential for temporary or permanent hearing impairment is
relatively low and would likely be avoided through the implementation
of the power-down and shut-down measures;
No injuries, serious injuries, or mortalities are anticipated to
occur as a result of L-DEO's planned marine seismic survey, and none
are proposed to be authorized by NMFS. Table 3 of this document
outlines the number of requested Level B harassment takes that are
anticipated as a result of these activities. Further, the seismic
surveys will not take place in areas of significance for marine mammal
feeding, resting, breeding, or calving and will not adversely impact
marine mammal habitat.
Many animals perform vital functions, such as feeding, resting,
traveling, and socializing, on a diel cycle (i.e., 24 hr cycle).
Behavioral reactions to noise exposure (such as disruption of critical
life functions, displacement, or avoidance of important habitat) are
more likely to be significant if they last more than one diel cycle or
recur on subsequent days (Southall et al., 2007). While seismic
operations are anticipated to occur on consecutive days, the estimated
duration of the survey would last no more than 39 days. Additionally,
the seismic survey will be increasing sound levels in the marine
environment in a relatively small area surrounding the vessel (compared
to the range of the animals), which is constantly travelling over
distances, and some animals may only be exposed to and harassed by
sound for shorter less than day.
As mentioned previously, NMFS estimates that 20 species of marine
mammals under its jurisdiction could be potentially affected by Level B
harassment over the course of the IHA. The population estimates for the
marine mammal species that may be taken by Level B harassment were
provided in Table 3 of this document.
NMFS's practice has been to apply the 160 dB re 1 [micro]Pa (rms)
received level threshold for underwater impulse sound levels to
determine whether take by Level B harassment occurs. Southall et al.
(2007) provide a severity scale for ranking observed behavioral
responses of both free-ranging marine mammals and laboratory subjects
to various types of anthropogenic sound (see Table 4 in Southall et al.
[2007]).
NMFS has preliminarily determined, provided that the aforementioned
mitigation and monitoring measures are implemented, the impact of
conducting a marine seismic survey in the northeast Atlantic Ocean,
June to July, 2013, may result, at worst, in a modification in behavior
and/or low-level physiological effects (Level B harassment) of certain
species of marine mammals.
While behavioral modifications, including temporarily vacating the
area during the operation of the airgun(s), may be made by these
species to avoid the resultant acoustic disturbance, the availability
of alternate areas within these areas for species and the short and
sporadic duration of the research activities, have led NMFS to
preliminary determine that the taking by Level B harassment from the
specified activity will have a negligible impact on the affected
species in the specified geographic region. Due to the nature, degree,
and context of Level B (behavioral) harassment anticipated and
described (see ``Potential Effects on Marine Mammals'' section above)
in this notice, the activity is not expected to impact rates of annual
recruitment or survival for any affected species or stock, particularly
given the NMFS and the applicant's proposal to implement a mitigation
and monitoring plans to minimize impacts to marine mammals.
The requested take estimates represent a small number relative to
the affected species or stock size (i.e., all are less than 1%). See
Table 3 for the requested authorized take number of marine mammals.
Impact on Availability of Affected Species or Stock for Taking for
Subsistence Uses
Section 101(a)(5)(D) of the MMPA also requires NMFS to determine
that the authorization will not have an unmitigable adverse effect on
the availability of marine mammal species or stocks for subsistence
use. There are no relevant subsistence uses of marine mammals in the
study area (in the northeast Atlantic Ocean) that implicate MMPA
section 101(a)(5)(D).
Endangered Species Act
Of the species of marine mammals that may occur in the proposed
survey area, several are listed as endangered under the ESA, including
the North Atlantic right, humpback, sei, fin, blue, and sperm whales.
L-DEO did not request take of endangered North Atlantic right whales
due to the low
[[Page 17383]]
likelihood of encountering this species during the cruise. Under
section 7 of the ESA, NSF has initiated formal consultation with the
NMFS, Office of Protected Resources, Endangered Species Act Interagency
Cooperation Division, on this proposed seismic survey. NMFS's Office of
Protected Resources, Permits and Conservation Division, has initiated
formal consultation under section 7 of the ESA with NMFS's Office of
Protected Resources, Endangered Species Act Interagency Cooperation
Division, to obtain a Biological Opinion evaluating the effects of
issuing the IHA on threatened and endangered marine mammals and, if
appropriate, authorizing incidental take. NMFS will conclude formal
section 7 consultation prior to making a determination on whether or
not to issue the IHA. If the IHA is issued, NSF and L-DEO, in addition
to the mitigation and monitoring requirements included in the IHA, will
be required to comply with the Terms and Conditions of the Incidental
Take Statement corresponding to NMFS's Biological Opinion issued to
both NSF and NMFS's Office of Protected Resources.
National Environmental Policy Act
With L-DEO's complete application, NSF and L-DEO provided NMFS a
draft ``Environmental Analysis of a Marine Geophysical Survey by the R/
V Marcus G. Langseth in the Northeast Atlantic Ocean, June-July 2013,''
prepared by LGL Ltd., Environmental Research Associates, on behalf of
NSF and L-DEO. The EA analyzes the direct, indirect, and cumulative
environmental impacts of the proposed specified activities on marine
mammals including those listed as threatened or endangered under the
ESA. Prior to making a final decision on the IHA application, NMFS,
after review and evaluation of the NSF EA for consistency with the
regulations published by the Council of Environmental Quality (CEQ) and
NOAA Administrative Order 216-6, Environmental Review Procedures for
Implementing the National Environmental Policy Act, will prepare an
independent EA and make a decision of whether or not to issue a Finding
of No Significant Impact (FONSI).
Proposed Authorization
NMFS proposes to issue an IHA to L-DEO for conducting a marine
seismic survey in the northeast Atlantic Ocean, provided the previously
mentioned mitigation, monitoring, and reporting requirements are
incorporated. The duration of the IHA would not exceed one year from
the date of its issuance.
Information Solicited
NMFS requests interested persons to submit comments and information
concerning this proposed project and NMFS's preliminary determination
of issuing an IHA (see ADDRESSES). Concurrent with the publication of
this notice in the Federal Register, NMFS is forwarding copies of this
application to the Marine Mammal Commission and its Committee of
Scientific Advisors.
Dated: March 18, 2013.
Helen M. Golde,
Acting Director, Office of Protected Resources, National Marine
Fisheries Service.
[FR Doc. 2013-06504 Filed 3-20-13; 8:45 am]
BILLING CODE 3510-22-P