[Federal Register Volume 78, Number 30 (Wednesday, February 13, 2013)]
[Notices]
[Pages 10137-10160]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2013-03321]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XC238


Takes of Marine Mammals Incidental to Specified Activities; 
Marine Geophysical Survey on the Mid-Atlantic Ridge in the Atlantic 
Ocean, April 2013, Through June 2013

AGENCY: National Marine Fisheries Service, National Oceanic and 
Atmospheric Administration (NOAA), Commerce.

ACTION: Notice; proposed incidental harassment authorization; request 
for comments.

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SUMMARY: We have received an application from the Lamont-Doherty Earth 
Observatory (Observatory), in collaboration with the National Science 
Foundation (Foundation), for an Incidental Harassment Authorization to 
take marine mammals, by harassment, incidental to conducting a marine 
geophysical (seismic) survey on the Mid-Atlantic Ridge in the north 
Atlantic Ocean in international waters, from April 2013 through May 
2013. Per the Marine Mammal Protection Act, we are requesting comments 
on our proposal to issue an Incidental Harassment Authorization to the 
Observatory and the Foundation to incidentally harass by Level B 
harassment only, 28 species of marine mammals during the 20-day seismic 
survey.

DATES: Comments and information must be received no later than March 
15, 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 20910-3225. The mailbox address for 
providing email comments is [email protected]. Please include 0648-
XC238 in the subject line. We are not responsible for email comments 
sent to other addresses other than the one provided here. Comments sent 
via email to [email protected], including all attachments, must not 
exceed a 10-megabyte file size.
    All submitted comments are a part of the public record and we will 
post 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.
    To obtain an electronic copy of the application, write to the 
previously mentioned address, telephone the contact listed here (see 
FOR FURTHER INFORMATION CONTACT), or visit the internet at: http://www.nmfs.noaa.gov/pr/permits/incidental.htm#applications.
    The following associated documents are also available at the same 
internet address:
    The Foundation's draft environmental analysis titled, ``Marine 
geophysical survey by the R/V MARCUS G. LANGSETH on the mid-Atlantic 
Ridge, April-May 2013,'' for their federal action of funding the 
Observatory's seismic survey. LGL Ltd., Environmental Research 
Associates (LGL), prepared this analysis on behalf of the Foundation 
pursuant to Executive Order 12114: Environmental Effects Abroad of 
Major Federal Actions. The Foundation's environmental analysis 
evaluates the effects of the proposed seismic survey on the human 
environment including impacts to marine mammals. We will prepare a 
separate National Environmental Policy Act (NEPA: 42 U.S.C. 4321 et 
seq.) analysis to evaluate the environmental effects related to the 
scope of our federal action which is the proposed issuance of an 
incidental take authorization to the Observatory and the Foundation. We 
plan to incorporate the Foundation's environmental analysis, in whole 
or part, by reference, into our NEPA document as that analysis provides 
a detailed description of the planned survey and its anticipated 
effects on marine mammals. This notice and the referenced document 
present detailed information on the scope of our federal action under 
NEPA (i.e., potential impacts to marine mammals from

[[Page 10138]]

issuing the proposed IHA including measures for mitigation, and 
monitoring) and we will consider comments submitted in response to this 
notice as we prepare our NEPA analysis.
    The public can view documents cited in this notice by appointment, 
during regular business hours, at the aforementioned address.

FOR FURTHER INFORMATION CONTACT: Jeannine Cody, National Marine 
Fisheries Service, Office of Protected Resources, (301) 427-8401.

SUPPLEMENTARY INFORMATION:

Background

    Section 101(a)(5)(D) of the Marine Mammal Protection Act of 1972, 
as amended (MMPA; 16 U.S.C. 1361 et seq.) directs the Secretary of 
Commerce 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, after notice of a proposed authorization to the 
public for review and public comment: (1) We make certain findings; and 
(2) the taking is limited to harassment.
    We shall grant authorization for the incidental taking of small 
numbers of marine mammals if we find 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 taking. We have 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.''
    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 
our 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, we must either issue or deny the 
authorization and must publish a notice in the Federal Register within 
30 days of our determination to 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

    We received an application from the Observatory on December 7, 
2012, requesting that we issue an Incidental Harassment Authorization 
(Authorization) for the take, by Level B harassment only, of small 
numbers of marine mammals incidental to conducting a marine seismic 
survey in the north Atlantic Ocean in international waters from April 
8, 2013, through May 13, 2013. We received a revised application from 
the Observatory on December 23, 2012 and January 17, 2013, which 
reflected updates to the mitigation safety zones, incidental take 
requests for marine mammals, and information on marine protected areas. 
Upon receipt of additional information, we determined the application 
complete and adequate on January 18, 2013.
    Project Purpose--The Observatory plans to conduct a two-dimensional 
(2-D) seismic survey on the Mid-Atlantic Ridge in the north Atlantic 
Ocean. Specifically, the proposed survey would image the Rainbow massif 
to determine the characteristics of the magma body that supplies heat 
to the Rainbow hydrothermal field; determine the distribution of the 
different rock types that form the Rainbow massif; document large- and 
small-scale faults in the vicinity and investigate their role in 
controlling hydrothermal fluid discharge.
    Vessel--The Observatory plans to use one source vessel, the R/V 
Marcus G. LANGSETH (LANGSETH), a seismic airgun array, a single 
hydrophone streamer, and ocean bottom seismometers (seismometers) to 
conduct the seismic survey. In addition to the operations of the 
seismic airgun array and hydrophone streamer, and the seismometers, the 
Observatory intends to operate a multibeam echosounder and a sub-bottom 
profiler continuously throughout the proposed survey.
    Marine Mammal Take--Acoustic stimuli (i.e., increased underwater 
sound) generated during the operation of the seismic airgun arrays, may 
have the potential to cause behavioral disturbance for marine mammals 
in the survey area. This is the principal means of marine mammal take 
associated with these activities and the Observatory requested an 
authorization to take 28 species of marine mammals by Level B 
harassment.
    In the Observatory's application, they did not request 
authorization to take marine mammals by Level A Harassment because 
their environmental analyses estimate that marine mammals would not be 
exposed to levels of sound likely to result in Level A harassment (we 
refer the reader to Appendix B of the Foundation's NEPA document 
titled, ``2011 Final Programmatic Environmental Impact Statement/
Overseas Environmental Impact Statement (2011 PEIS) for Marine Seismic 
Research funded by the National Science Foundation or Conducted by the 
U.S. Geological Survey,'' (NSF/USGS, 2011) at http://www.nsf.gov/geo/oce/envcomp/usgs-nsf-marine-seismic-research/nsf-usgs-final-eis-oeis-with-appendices.pdf for details). Consequently, the Observatory's 
request for take by Level A harassment is zero animals for any species.
    We do not expect that the use of the multibeam echosounder, the 
sub-bottom profiler, or the ocean bottom seismometer would result in 
the take of marine mammals and will discuss our reasoning later in this 
notice. Also, we do not expect take to result from a collision with the 
LANGSETH during seismic acquisition activities because the vessel moves 
at a relatively slow speed (approximately 8.3 kilometers per hour (km/
h); 5.2 miles per hour (mph); 4.5 knots (kts)), for a relatively short 
period of time (approximately 20 operational days). It is likely that 
any marine mammal would be able to avoid the vessel during seismic 
acquisition activities. The Observatory has no recorded cases of a 
vessel strike with a marine mammal during the conduct of over eight 
years of seismic surveys covering over 160,934 km (86,897.4 nmi) of 
transect lines.

Description of the Proposed Specified Activities

Survey Details

    The Observatory's proposed seismic survey on the Mid-Atlantic Ridge 
in the north Atlantic Ocean would commence

[[Page 10139]]

on April 8, 2013, and end on May 13, 2013. The LANGSETH would depart 
from St. George's, Bermuda, on April 8, 2013, and transit to the 
proposed survey area in international waters approximately 300 km 
(186.4 miles (mi)) offshore of Pico and Faial Islands in the Azores. At 
the conclusion of the proposed survey activities, the LANGSETH would 
arrive in Ponta Delgada, Azores on May 13, 2012. The proposed study 
area would encompass an area on the Mid-Atlantic Ridge bounded by the 
following coordinates: Approximately 35.5 to 36.5[deg] North by 33.5 to 
34.5[deg] West.
    Some minor deviation from these dates is possible, depending on 
logistics, weather conditions, and the need to repeat some lines if 
data quality is substandard. Therefore, we propose to issue an 
authorization that is effective from April 8, 2013, to June 24, 2013.
    Typically, 2-D surveys acquire data along single track lines with 
wide intervals; cover large areas; provide a coarse sampled subsurface 
image; and project less acoustic energy into the environment than other 
types of seismic surveys. During the survey, the LANGSETH would deploy 
an 36-airgun array as an energy source, an 8-kilometer (km)-long (3.7 
mi-long) hydrophone streamer, and 46 seismometers. The seismometers are 
portable, self-contained passive receiver systems designed to sit on 
the seafloor and record seismic signals generated primarily by airguns 
and earthquakes.
    The LANGSETH would transect approximately 2,582 km (1.6 mi) of 
transect lines which are spaced 1 to 2 meters (m) (3.2 to 6.6 feet 
(ft)) apart from one another (see Figure 1 in the Observatory's 
application). As the LANGSETH tows the airgun array along the transect 
lines, the hydrophone streamer would receive the returning acoustic 
signals and transfer the data to the vessel's onboard processing 
system. The seismometers also record and store the returning signals 
for later analysis. The LANGSETH would retrieve the seismometers at the 
conclusion of the survey.
    The proposed study (e.g., equipment testing, startup, line changes, 
repeat coverage of any areas, and equipment recovery) would require 
approximately 20 days. At the proposed survey area, the LANGSETH would 
conduct seismic acquisition activities in a grid pattern using the 
seismometers as a receiver over a total of approximately 1,680 km 
(1,044 mi) of survey lines and would also conduct seismic acquisition 
activities in multichannel seismic (MCS) mode using the 8-km (3.7 mi) 
streamer as the receiver over a total of approximately 900 km (559 mi). 
The seismic lines are over water depths of approximately 900 to 3,000 m 
(2,952 ft to 1.9 mi). Approximately 2,565 km (1,594 mi) of the survey 
effort would occur in depths greater than 1,000 m (3,280 ft). The 
remaining effort (17 km; 10.5 mi) would occur in water depths of 100 to 
1,000 m (328 to 3,280 ft).
    The proposed data acquisition would include approximately 480 hours 
of airgun operations (i.e., 20 days over 24 hours), with airgun 
discharges occurring on either a 3.25 minute interval with the 
seismometers or a 16-second interval for the MCS seismic portion. The 
Observatory would conduct all planned seismic activities with on-board 
assistance by the scientists who have proposed the study, Drs. J.P. 
Canales and R. Sohn of Woods Hole Oceanographic Institution and Dr. R. 
Dunn of the University of Hawaii. The vessel is self-contained and the 
crew would live aboard the vessel for the entire cruise.

Vessel Specifications

R/V LANGSETH

    The LANGSETH, owned by the Foundation and operated by the 
Observatory, is a seismic research vessel with a quiet propulsion 
system that avoids interference with the seismic signals emanating from 
the airgun array. The vessel is 71.5 m (235 ft) long; has a beam of 
17.0 m (56 ft); a maximum draft of 5.9 m (19 ft); and a gross tonnage 
of 3,834 pounds. Its two 3,550 horsepower (hp) Bergen BRG-6 diesel 
engines drive two propellers. 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 cruising speed of the vessel outside of seismic 
operations is 18.5 km/h (11.5 mph; 10 kts).
    The LANGSETH would tow the 36-airgun array, as well as the 
hydrophone streamer during the first and last surveys, along 
predetermined lines. When the LANGSETH is towing the airgun array and 
the hydrophone streamer, the turning rate of the vessel is limited to 
five degrees per minute. Thus, the maneuverability of the vessel is 
limited during operations with the streamer.
    The vessel also has an observation tower from which protected 
species visual observers (observer) would watch for marine mammals 
before and during the proposed seismic acquisition operations. When 
stationed on the observation platform, the observer's eye level would 
be approximately 21.5 m (71 ft) above sea level providing the observer 
an unobstructed view around the entire vessel.

Acoustic Source Specifications

Seismic Airguns

    The LANGSETH would deploy an 36-airgun array, with a total volume 
of approximately 6,600 cubic inches (in\3\). The airguns are 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. The 
dominant frequency components range from zero to 188 Hertz (Hz). The 
array configuration consists of four identical linear strings, with 10 
airguns on each string; the first and last airguns would be spaced 16 m 
(52 ft) apart. Of the 10 airguns, nine would fire simultaneously while 
the tenth airgun would serve as a spare in case of failure of one of 
the other airguns. The LANGSETH would distribute the array across an 
area of approximately 24 x 16 m (78.7 x 52.5 ft) and would tow the 
array approximately 30 m (98.4 ft) behind the vessel at a tow depth of 
12 m (39.4 ft) (see Figure 2-11, page 2-25 in the Foundation's 2011 
PEIS) (NSF/USGS, 2011). During firing, the airguns would emit a brief 
(approximately 0.1 s) pulse of sound; during the intervening periods of 
operations, the airguns are silent.

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 ([micro]Pa), where 1 pascal (Pa) is 
the pressure resulting from a force of one newton exerted over an area 
of one square meter. We express sound pressure level as the ratio of a 
measured sound pressure and a reference level. The commonly used 
reference pressure level in underwater acoustics is 1 [micro]Pa, and 
the units for sound pressure levels are dB re: 1 [mu]Pa. Sound pressure 
level (in decibels (dB)) = 20 log (pressure/reference pressure).
    Sound pressure level is an instantaneous measurement and can be 
expressed as the peak, the peak-peak (p-p), or the root mean square. 
Root mean square, 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 sound pressure level in this document refer to the root mean square 
unless otherwise noted. Sound

[[Page 10140]]

pressure level 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 array on the LANGSETH is 
236 to 265 dB re: 1 [micro]Pa(p-p) and the root mean square 
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). However, the difference between root mean square 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, the Observatory predicted the received sound levels in 
relation to distance and direction from the 36-airgun array and the 
single Bolt 1900LL 40-in\3\ airgun.
    Appendix H of the Foundation's PEIS (NSF/USGS, 2011) provides a 
detailed description of the modeling for marine seismic source arrays 
for species mitigation. These are the source levels applicable to 
downward propagation. The effective source levels for horizontal 
propagation are lower than those for downward propagation because of 
the directional nature of the sound from the airgun array. We refer the 
reader to the Observatory's authorization application and the 
Foundation's PEIS for additional information.

Predicted Sound Levels for the Airguns

    The Observatory has developed a model (Diebold et al., 2010) that 
predicts received sound levels as a function of distance from the 
airguns for the 36-airgun array and the single 40-in\3\ airgun. Their 
modeling approach uses ray tracing (i.e., a graphical representation of 
the effects of refracting sound waves) for the direct wave traveling 
from the array to the receiver and its associated source ghost 
(reflection at the air-water interface in the vicinity of the array), 
in a constant-velocity half-space (infinite homogeneous ocean layer, 
unbounded by a seafloor).
    Additionally, Tolstoy et al., (2009) reported results for 
propagation measurements of pulses from the LANGSETH's 36-airgun 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 Observatory used the results from their algorithm for acoustic 
modeling (Diebold et al., 2010) to calculate the exclusion zones for 
the 36-airgun array and the single airgun. These values designate 
mitigation zones used during power downs or shutdowns for marine 
mammals. The Observatory uses the mitigation zones to estimate take 
(described in greater detail in Chapter 7 of the application) for 
marine mammals.
    Comparison of the Tolstoy et al. (2009) calibration study with the 
Observatory's model (Diebold et al., 2010) for the LANGSETH's 36-airgun 
array indicated that the Observatory's model represents the actual 
received levels, within the first few kilometers and the locations of 
the predicted exclusions zones. Thus, the comparison of results from 
the Tolstoy et al. (2009) calibration study with the Observatory's 
model (Diebold et al., 2010) at short ranges for the same array tow 
depth are in good agreement (see Figures 12 and 14 in Diebold et al., 
2010). As a consequence, isopleths falling within this domain can be 
predicted reliably by the Observatory's model.
    In contrast, for actual received levels at longer distances, the 
Observatory found that their model (Diebold et al., 2010) was a more 
robust tool for estimating mitigation radii in deep water as it did not 
overestimate the received sound levels at a given distance. To estimate 
mitigation radii in intermediate water depths, the Observatory applied 
a correction factor (multiplication) of 1.5 to the deep water 
mitigation radii. We refer the reader to Appendix H of the Foundation's 
PEIS (NSF/USGS, 2011) for a detailed description of the modeling for 
marine seismic source arrays for species mitigation.
    Table 1 summarizes the predicted distances at which one would 
expect to receive three sound levels (160-, 180-, and 190-dB) from the 
36-airgun array and a single airgun. To avoid the potential for injury 
or permanent physiological damage (Level A harassment), serious injury, 
or mortality we have concluded that cetaceans and pinnipeds should not 
be exposed to pulsed underwater noise at received levels exceeding 180 
dB re: 1 [mu]Pa and 190 dB re: 1 [mu]Pa, respectively (NMFS, 1995, 
2000). The 180-dB and 190-dB level shutdown criteria are applicable to 
cetaceans and pinnipeds, respectively, specified by us (NMFS, 1995, 
2000). Thus the Observatory used these received sound levels to 
establish the mitigation zones. We also assume that marine mammals 
exposed to levels exceeding 160 dB re: 1 [micro]Pa may experience Level 
B harassment.

 Table 1--Modeled Distances to Which Sound Levels Greater Than or Equal to 160 and 180 dB re: 1 [micro]Pa Could
  Be Received During the Proposed Survey Over the Mid-Atlantic Ridge in the North Atlantic Ocean, During April
                                               Through June, 2013
----------------------------------------------------------------------------------------------------------------
                                                                                                Predicted RMS
                                                                 Tow depth    Water depth     distances\1\ (m)
                   Source and volume (in\3\)                        (m)           (m)      ---------------------
                                                                                              160 dB     180 dB
----------------------------------------------------------------------------------------------------------------
Single Bolt airgun (40 in\3\).................................          12         > 1,000        388        100
                                                                              100 to 1,000        582        100
36-Airgun Array (6,600 in\3\).................................          12         > 1,000      6,908      1,116
                                                                              100 to 1,000     10,362      1,674
----------------------------------------------------------------------------------------------------------------
\1\ Diebold, J.B., M. Tolstoy, L. Doermann, S.L. Nooner, S.C. Webb, and T.J. Crone. 2010. R/V Marcus G. Langseth
  seismic source: Modeling and calibration. Geochem. Geophys. Geosyst.


[[Page 10141]]

Ocean Bottom Seismometers

    The Observatory proposes to place 46 seismometers on the sea floor 
prior to the initiation of the seismic survey. Each seismometer is 
approximately 0.9 m (2.9 ft) high with a maximum diameter of 97 
centimeters (cm) (3.1 ft). An anchor, made of a rolled steel bar grate 
which measures approximately 7 by 91 by 91.5 cm (3 by 36 by 36 inches) 
and weighs 45 kilograms (99 pounds) would anchor the seismometer to the 
seafloor.
    After the Observatory completes the proposed seismic survey, an 
acoustic signal would trigger the release of each of the 46 
seismometers from the ocean floor. The LANGSETH's acoustic release 
transponder, located on the vessel, communicates with the seismometer 
at a frequency of 9 to13 kilohertz (kHz). The maximum source level of 
the release signal is 242 dB re: 1 [mu]Pa with an 8-millisecond pulse 
length. The received signal activates the seismometer's double burn-
wire release assembly which then releases the seismometer from the 
anchor. The seismometer then floats to the ocean surface for retrieval 
by the LANGSETH. The steel grate anchors from each of the seismometers 
would remain on the seafloor.
    The LANGSETH crew would deploy the seismometers one-by-one from the 
stern of the vessel while onboard protected species observers will 
alert them to the presence of marine mammals and recommend ceasing 
deploying or recovering the seismometers to avoid potential 
entanglement with marine mammal. Thus, entanglement of marine mammals 
is highly unlikely.
    Although placement of the seismometers is dispersed over 
approximately1,500 square km (km\2\) (579 square mi (mi\2\) of seafloor 
habitat and may disturb benthic invertebrates, we and the Observatory 
expect these impacts to be localized and short-term because of natural 
sedimentation processes and the natural sinking of the anchors from 
their own weight resulting in no long-term habitat impacts. Also, the 
deep water habitat potentially affected by the placement of the 
seismometers is not designated as a marine protected area.

Multibeam Echosounder

    The LANGSETH would operate a Kongsberg EM 122 multibeam echosounder 
concurrently during airgun operations to map characteristics of the 
ocean floor. The hull-mounted echosounder emits brief pulses of sound 
(also called a ping) (10.5 to 13.0 kHz) in a fan-shaped beam that 
extends downward and to the sides of the ship. The transmitting 
beamwidth is 1 or 2[deg] fore-aft and 150[deg] athwartship and the 
maximum source level is 242 dB re: 1 [mu]Pa.
    For deep-water operations, each ping consists of eight (in water 
greater than 1,000 m; 3,280 ft) or four (less than 1,000 m; 3,280 ft) 
successive, fan-shaped transmissions, from two to 15 milliseconds (ms) 
in duration and each ensonifying a sector that extends 1[deg] fore-aft. 
Continuous wave pulses increase from 2 to 15 ms long in water depths up 
to 2,600 m (8,530 ft). The echosounder uses frequency-modulated chirp 
pulses up to 100-ms long in water greater than 2,600 m (8,530 ft). The 
successive transmissions span an overall cross-track angular extent of 
about 150[deg], with 2-ms gaps between the pulses for successive 
sectors.

Sub-Bottom Profiler

    The LANGSETH would also operate a Knudsen Chirp 3260 sub-bottom 
profiler concurrently during airgun and echosounder operations to 
provide information about the sedimentary features and bottom 
topography. The profiler is capable of reaching depths of 10,000 m (6.2 
mi). The dominant frequency component is 3.5 kHz and a hull-mounted 
transducer on the vessel directs the beam downward in a 27[ordm] cone. 
The power output is 10 kilowatts (kW), but the actual maximum radiated 
power is three kilowatts or 222 dB re: 1 [micro]Pa. The ping duration 
is up to 64 ms with a pulse interval of one second, but a common mode 
of operation is to broadcast five pulses at 1-s intervals followed by a 
5-s pause.
    We expect that acoustic stimuli resulting from the proposed 
operation of the single airgun or the 36-airgun array has the potential 
to harass marine mammals, incidental to the conduct of the proposed 
seismic survey. We assume that during simultaneous operations of the 
airgun array and the other sources, any marine mammals close enough to 
be affected by the echosounder and sub-bottom profiler would already be 
affected by the airguns. We also expect these disturbances to result in 
a temporary modification in behavior and/or low-level physiological 
effects (Level B harassment) of small numbers of certain species of 
marine mammals.
    We do 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 
(4.6 kts; 8.5 km/hr; 5.3 mph) during seismic acquisition.

Description of the Marine Mammals in the Area of the Proposed Specified 
Activity

    Twenty-eight marine mammal species under our jurisdiction may occur 
in the proposed survey area, including seven mysticetes (baleen 
whales), and 21 odontocetes (toothed cetaceans) during April through 
May, 2013. Six of these species are listed as endangered under the 
Endangered Species Act of 1973 (ESA; 16 U.S.C. 1531 et seq.), 
including: the blue (Balaenoptera musculus), fin (Balaenoptera 
physalus), humpback (Megaptera novaeangliae), north Atlantic right 
(Eubalaena glacialis), sei (Balaenoptera borealis), and sperm (Physeter 
macrocephalus) whales.
    Based on the best available data, the Observatory does not expect 
to encounter the following species because of these species rare and/or 
extralimital occurrence in the survey area. They include the: Atlantic 
white-sided dolphin (Lagenorhynchus acutus), white-beaked dolphin 
(Lagenorhynchus albirostris), harbor porpoise (Phocoena phocoena), 
Clymene dolphin (Stenella clymene), Fraser's dolphin (Lagenodelphis 
hosei), spinner dolphin (Stenella longirostris), melon-headed whale 
(Peponocephala electra), Atlantic humpback dolphin (Souza teuszii), 
long-beaked common dolphin (Delphinus capensis), and any pinniped 
species. Accordingly, we did not consider these species in greater 
detail and the proposed authorization would only address requested take 
authorizations for the 28 species.
    Of these 28 species, the most common marine mammals in the survey 
area would be the: short-beaked common dolphin (Delphinus delphis), 
striped dolphin (Stenella coeruleoalba), and short-finned pilot whale 
(Globicephala macrorhynchus).
    Table 2 presents information on the abundance, distribution, and 
conservation status of the marine mammals that may occur in the 
proposed survey area during April through June, 2013.

[[Page 10142]]



  Table 2--Abundance Estimates, Mean Density, and ESA Status of Marine
Mammals That May Occur in the Proposed Seismic Survey Area Over the Mid-
 Atlantic Ridge in the North Atlantic Ocean, During April Through June,
                                  2013.
   [See text and Table 2 in the Observatory's application for further
                                details]
------------------------------------------------------------------------
                                                           Estimated
                                Abundance in     ESA   Density  (/100 km \2\)
                               Atlantic Ocean                 \b\
------------------------------------------------------------------------
Mysticetes:
    North Atlantic right      396 \1\........  EN                   0
     whale.
    Humpback whale..........  11,570 \2\.....  EN                   0
    Minke whale.............  121,000 \3\....  NL                   0
    Bryde's whale...........  Not available..  NL                   0.19
    Sei whale...............  12-13,000 \4\..  EN                   0.19
    Fin whale...............  24,887 \5\.....  EN                   4.46
    Blue whale..............  937 \6\........  EN                   1.49
Odontocetes:
    Sperm whale.............  13,190 \7\.....  EN                   3.71
    Pygmy sperm whale.......  395 \1\........  NL                   0
    Dwarf sperm whale.......  395 \1\........  NL                   0
    Cuvier's beaked whale...  3,513 \1,8\....  NL                   0
    Mesoplodon spp..........  3,513 \1,8\....  NL                   7.04
    True's beaked whale.....  3,513 \1,8\....  NL                   7.04
    Gervais beaked whale....  3,513 \1,8\....  NL                   7.04
    Sowerby's beaked whale..  3,513 \1,8\....  NL                   7.04
    Blainville's beaked       3,513 \1,8\....  NL                   7.04
     whale.
    Northern bottlenose       40,000 \9\.....  NL                   0
     whale.
    Rough-toothed dolphin...  Not available..  NL                   0
    Common bottlenose         81,588 \10\....  NL                   8.35
     dolphin.
    Pantropical spotted       4,439 \1\......  NL                   0
     dolphin.
    Atlantic spotted dolphin  50,978 \1\.....  NL                  20.03
    Striped dolphin.........  94,462 \1\.....  NL                 185.50
    Short-beaked common       120,741 \4\....  NL                 379.52
     dolphin.
    Risso's dolphin.........  20,479 \4\.....  NL                   3.83
    Pygmy killer whale......  Not available..  NL                   0
    False killer whale......  Not available..  NL                   1.17
    Killer whale............  Not available..  NL                   0
    Long-finned pilot whale.   12,619,\1\      NL                   0
                               780,000 \11\.
    Short-finned pilot whale  24,674,\1\       NL                 120.96
                               780,000 \11\.
------------------------------------------------------------------------
\a\ ESA status codes: NL--not listed under the ESA; EN--Endangered; T--
  Threatened
\b\ The Observatory used Waring et al., 2008 to calculate density from
  sightings, effort, mean group sizes, and values for f(0) for the
  southern part of the survey area.
\1\ Western North Atlantic, in U.S. and southern Canadian waters (Waring
  et al., 2012)
\2\ Likely negatively biased (Stevick et al., 2003)
\3\ Central and Northeast Atlantic (IWC, 2012)
\4\ North Atlantic (Cattanach et al., 1993)
\5\ Central and Northeast Atlantic (V[iacute]kingsson et al., 2009)
\6\ Central and Northeast Atlantic (Pike et al., 2009).
\7\ For the northeast Atlantic, Faroes-Iceland, and the U.S. east coast
  (Whitehead, 2002).
\8\ Ziphius and Mesoplodon spp. combined
\9\ Eastern North Atlantic (NAMMCO, 1995)
\10\ Offshore, Western North Atlantic (Waring et al., 2012)
\11\ Globicephala sp. combined, Central and Eastern North Atlantic (IWC,
  2012)

    Refer to Section 4 of the Observatory's application and Sections 
3.6.3.4 and 3.7.3.4 of the 2011 PEIS (NSF/USGS, 2011) for detailed 
information regarding the abundance and distribution, population 
status, and life history and behavior of these species and their 
occurrence in the proposed project area. We have reviewed these data 
and determined them to be the best available scientific information for 
the purposes of the proposed incidental harassment authorization.

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 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 is not 
an injury (Southall et al., 2007). Although we cannot exclude the 
possibility entirely, 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, we expect some 
behavioral disturbance, but we expect the disturbance to be localized. 
We refer the reader to a more comprehensive review of these issues in 
the 2011 PEIS (NSF/USGS, 2011).

Tolerance

    Studies on marine mammals' tolerance to sound in the natural 
environment are relatively rare. Richardson et al. (1995) defined

[[Page 10143]]

tolerance as the occurrence of marine mammals in areas where they are 
exposed to human activities or manmade 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 (Stone, 2003; Stone and Tasker, 2006; Moulton et al. 
2005, 2006a; Weir 2008a for sperm whales), (MacLean and Koski, 2005; 
Bain and Williams, 2006 for Dall's porpoises). 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).
    We expect that the masking effects of pulsed sounds (even from 
large arrays of airguns) on marine mammal calls and other natural 
sounds will be limited, although there are very few specific data on 
this. 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. We understand that some baleen and toothed whales continue 
calling in the presence of seismic pulses, and that some researchers 
have heard these calls 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 northeast Pacific 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 have 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). Several studies have reported hearing dolphins and 
porpoises calling while airguns were 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 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, we expect that the masking effects of seismic pulses 
would 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 industrial sound. In most cases, this 
approach likely overestimates the numbers of marine mammals that would 
be affected in some biologically-important manner.
    The sound criteria used to estimate how many marine mammals might 
be

[[Page 10144]]

disturbed to some biologically-important degree by a seismic program 
are based primarily on behavioral observations of a few species. 
Scientists have conducted detailed studies on humpback, gray, bowhead 
(Balaena mysticetus), and sperm whales. There are less detailed data 
available for some other species of baleen whales and small toothed 
whales, but for many species there are no data on responses to marine 
seismic surveys.
    Baleen Whales--Baleen whales generally tend to avoid operating 
airguns, but avoidance radii are quite variable (reviewed in Richardson 
et al., 1995). 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 from the area. 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 
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 [micro]Pa 
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 four to 15 km (2.5 
to 9.3 mi) 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 
summarized in Appendix B(5) of the Foundation's Assessment have shown 
that some species of baleen whales, notably bowhead and humpback 
whales, at times show strong avoidance at received levels lower than 
160-170 dB re: 1 [micro]Pa.
    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, 20-in\3\ airgun with source 
level of 227 dB re: 1 [micro]Pa (p-p). In the 1998 study, the 
researchers documented that avoidance reactions began at five to eight 
km (3.1 to 4.9 mi) from the array, and that those reactions kept most 
pods approximately three to four km (1.9 to 2.5 mi) from the operating 
seismic boat. In the 2000 study, McCauley et al. noted localized 
displacement during migration of four to five km (2.5 to 3.1 mi) by 
traveling pods and seven to 12 km (4.3 to 7.5 mi) by more sensitive 
resting pods of cow-calf pairs. Avoidance distances with respect to the 
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 
[micro]Pa for humpback pods containing females, and at the mean closest 
point of approach distance, the received level was 143 dB re: 1 
[micro]Pa. The initial avoidance response generally occurred at 
distances of five to eight km (3.1 to 4.9 mi) from the airgun array and 
two km (1.2 mi) 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 [micro]Pa.
    Data collected by observers during several seismic surveys in the 
northwest Atlantic Ocean 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 versus 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 re: 1 [mu]Pa. 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.
    Other 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). Although, 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).
    A few studies have documented reactions of migrating and feeding 
(but not wintering) gray whales to seismic surveys. 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) root 
mean square basis, and that 10 percent of feeding whales interrupted 
feeding at received levels of 163 dB re: 1 [micro]Pa. 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).
    Observers have seen various species of Balaenoptera (blue, sei, 
fin, and minke whales) in areas ensonified by airgun pulses (Stone, 
2003; MacLean and Haley, 2004; Stone and Tasker, 2006), and have 
localized calls from blue and fin whales 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) 
observed

[[Page 10145]]

localized avoidance by fin whales during seismic airgun events in the 
western Mediterranean Sea and adjacent Atlantic waters from 2006-2009 
and reported that singing fin whales moved away from an operating 
airgun array for a time period that extended beyond the duration of the 
airgun activity.
    Ship-based monitoring studies of baleen whales (including blue, 
fin, sei, minke, and whales) in the northwest Atlantic found that 
overall, this group had lower sighting rates during seismic versus 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, 2011). The western 
Pacific gray whale population did not appear 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, 2011). 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--There is little systematic information available 
about reactions of toothed whales to noise pulses. There are few 
studies on toothed whales similar to the more extensive baleen whale/
seismic pulse work summarized earlier in this notice. 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 protected species observers (observers) on 
seismic vessels regularly see dolphins and other small toothed whales 
near 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 
(Delphinapterus leucas) 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 (Phocoena phocoena) 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 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 (Ziphius cavirostris) 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 increasing indications that some beaked whales tend to 
strand when naval exercises involving mid-frequency sonar operation are 
underway

[[Page 10146]]

within the vicinity of the animals (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 types of 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 the 
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 et 
al., 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 (Southall et al., 2007).
    Researchers have studied temporary threshold shift in certain 
captive odontocetes and pinnipeds exposed to strong sounds (reviewed in 
Southall et al., 2007). However, there has been no specific 
documentation of temporary threshold shift let alone permanent hearing 
damage, (i.e., permanent threshold shift, in free-ranging marine 
mammals exposed to sequences of airgun pulses during realistic field 
conditions).
    Temporary Threshold Shift--This is the mildest form of hearing 
impairment that can occur during exposure to a strong sound (Kryter, 
1985). While experiencing temporary threshold shift, the hearing 
threshold rises and a sound must be stronger in order to be heard. At 
least in terrestrial mammals, temporary threshold shift can last from 
minutes or hours to (in cases of strong shifts) days. For sound 
exposures at or somewhat above the temporary threshold shift threshold, 
hearing sensitivity in both terrestrial and marine mammals recovers 
rapidly after exposure to the noise ends. There are few data on sound 
levels and durations necessary to elicit mild temporary threshold shift 
for marine mammals, and none of the published data focus on temporary 
threshold shift elicited by exposure to multiple pulses of sound. 
Southall et al. (2007) summarizes available data on temporary threshold 
shift in marine mammals. Table 1 (introduced earlier in this document) 
presents the estimated distances from the LANGSETH's airguns at which 
the received energy level (per pulse, flat-weighted) would be greater 
than or equal to 180 or 190 dB re: 1 [micro]Pa.
    To avoid the potential for Level A harassment, serious injury or 
mortality we (NMFS 1995, 2000) concluded that cetaceans should not be 
exposed to pulsed underwater noise at received levels exceeding 180 dB 
re: 1 [mu]Pa. We do not consider the established 180 criterion to be 
the level above which temporary threshold shift might occur. Rather, it 
is a received level above which, in the view of a panel of bioacoustics 
specialists convened by us before temporary threshold shift 
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. We also assume that cetaceans exposed to 
levels exceeding 160 dB re: 1 [mu]Pa may experience Level B harassment.
    For toothed whales, researchers have derived temporary threshold 
shift 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 kilopascals (or 30 psi, p-p), which 
is equivalent to 228 dB re: 1 Pa (p-p), resulted in a 7 and 6 dB 
temporary threshold shift in the beluga whale at 0.4 and 30 kHz, 
respectively. Thresholds returned to within 2 dB of the pre-exposure 
level within four minutes of the exposure (Finneran et al., 2002). For 
the one harbor porpoise tested, the received level of airgun sound that 
elicited onset of temporary threshold shift was lower (Lucke et al., 
2009). If these results from a single animal are representative, it is 
inappropriate to assume that onset of temporary threshold shift occurs 
at similar received levels in all odontocetes (cf. Southall et al., 
2007). Some cetaceans apparently can incur temporary threshold shift at 
considerably lower sound exposures than are necessary to elicit 
temporary threshold shift 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 temporary threshold 
shift. 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, one could suspect that received 
levels causing temporary threshold shift onset may also be higher in 
baleen whales (Southall et al., 2007).
    In pinnipeds, researchers have not measured temporary threshold 
shift thresholds associated with exposure to brief pulses (single or 
multiple) of underwater sound. Initial evidence from more prolonged 
(non-pulse) exposures suggested that some pinnipeds (harbor seals in 
particular) incur temporary threshold shift at somewhat lower received 
levels than do small odontocetes exposed for similar durations (Kastak 
et al., 1999, 2005; Ketten et al., 2001). The indirectly estimated 
temporary threshold shift threshold for pulsed sounds (in sound 
pressure level) would be approximately 181 to 186 dB re: 1 [mu]Pa 
(Southall et al., 2007), or a series of pulses for which the highest 
sound exposure level values are a few decibels lower.
    Permanent Threshold Shift--When permanent threshold shift 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 permanent threshold shift 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 temporary threshold shift, there has been further speculation 
about the

[[Page 10147]]

possibility that some individuals occurring very close to airguns might 
incur permanent threshold shift (e.g., Richardson et al., 1995, p. 
372ff; Gedamke et al., 2008). Single or occasional occurrences of mild 
temporary threshold shift are not indicative of permanent auditory 
damage, but repeated or (in some cases) single exposures to a level 
well above that causing temporary threshold shift onset might elicit 
permanent threshold shift.
    Relationships between temporary and permanent threshold shift 
thresholds have not been studied in marine mammals, but are assumed to 
be similar to those in humans and other terrestrial mammals. Permanent 
threshold shift might occur at a received sound level at least several 
decibels above that inducing mild temporary threshold shift 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 permanent threshold shift threshold for impulse sounds (such as 
airgun pulses as received close to the source) is at least six decibels 
higher than the temporary threshold shift 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 permanent 
threshold shift as compared with temporary threshold shift, it is 
considerably less likely that permanent threshold shift would occur. 
Baleen whales generally avoid the immediate area around operating 
seismic vessels, as do some other marine mammals.

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 sonar use in which 
exposure to sonar is believed to have been a contributing factor to 
strandings: Greece (1996); the Bahamas (2000); Madeira (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 and, in one case, the 
co-occurrence of a Lamont-Doherty's seismic survey (Malakoff, 2002; Cox 
et al., 2006), has raised the possibility that beaked whales exposed to 
strong ``pulsed'' sounds may be especially 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 increasing 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. However, 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 
from one another, 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

[[Page 10148]]

sounds at frequencies of two 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 assume 
that there is a direct correlation between the potential effects of 
military sonar on marine mammals and those caused by seismic surveys 
using airguns. 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, 
two Cuvier's beaked whales stranded in the Gulf of California, Mexico 
while Lamont-Doherty's R/V Maurice Ewing had been 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).
    We anticipate no injuries of beaked whales during the proposed 
study because of:
    (1) The 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 the LANGSETH 
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 
and some odontocetes, are especially unlikely to incur non-auditory 
physical effects.

Potential Effects of Other Acoustic Devices

Multibeam Echosounder
    The Observatory would 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 two 
to 15 ms once every five to 20 s, depending on water depth. Most of the 
energy in the sound pulses emitted by this echosounder is at 
frequencies near 12 kHz, and the maximum source level is 242 dB re: 1 
[mu]Pa. 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 (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 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 vessel (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 an 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 temporary threshold 
shift.
    Navy sonars 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 echosounder. The area of possible influence of the 
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 the Observatory'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 
the animal. The following section outlines possible effects of an 
echosounder on marine mammals.
    Masking--Marine mammal communications would not be masked 
appreciably by the echosounder's 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 echosounder's 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 (Globicephala melas) 
(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 (Frankel, 2005). When a 38-kHz

[[Page 10149]]

echosounder and a 150-kHz acoustic Doppler current profiler were 
transmitting during studies in the eastern tropical Pacific Ocean, 
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 would be emitted by the Observatory's echosounder, 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 an 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 echosounder 
proposed for use by the LANGSETH is quite different than sonar used for 
navy operations. The echosounder's pulse duration is very short 
relative to the naval sonar. Also, at any given location, an individual 
marine mammal would be in the echosounder's beam 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 echosounder relative to that from naval sonar.
    Based upon the best available science, we believe that the brief 
exposure of marine mammals to one pulse, or small numbers of signals, 
from the echosounder is not likely to result in the harassment of 
marine mammals.

Sub-Bottom Profiler

    The Observatory would also operate a sub-bottom profiler from the 
source vessel during the proposed survey. The profiler's sounds are 
very short pulses, occurring for one to four ms once every second. Most 
of the energy in the sound pulses emitted by the 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 222 dB re: 1 [micro]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 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 and in order to be subjected to sound levels that could cause 
temporary threshold shift.
    Masking--Marine mammal communications would not be masked 
appreciably by the profiler's 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 
profiler's 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 profiler 
are likely to be similar to those for other pulsed sources if received 
at the same levels. However, the pulsed signals from the profiler are 
considerably weaker than those from the 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 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 profiler operates 
simultaneously with other higher-power acoustic sources. Many marine 
mammals would 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 profiler

Potential Effects of 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 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 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' reactions varied when exposed to vessel noise and 
traffic. In some cases, naive beluga whales exhibited rapid swimming 
from ice-breaking vessels up to 80 km (49.7 mi) away, and showed 
changes in

[[Page 10150]]

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; 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 would be audible to 
marine mammals over a large distance, it is unlikely that animals would 
respond behaviorally (in a manner that we would consider MMPA 
harassment) 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, we do 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 24.1 km/h (14.9 mph;13 kts).
    The Observatory's proposed operation of one vessel for the proposed 
survey is relatively small in scale compared to the number of 
commercial ships transiting at higher speeds in the same areas on an 
annual basis. The probability of vessel and marine mammal interactions 
occurring during the proposed survey is unlikely due to the LANGSETH's 
slow operational speed, which is typically 4.6 kts (8.5 km/h; 5.3 mph). 
Outside of seismic operations, the LANGSETH's cruising speed would be 
approximately 11.5 mph (18.5 km/h; 10 kts) 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; observers posted during 
operations scan the ocean for marine mammals and must report visual 
alerts of marine mammal presence to crew; and the observers 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 8.0 km (4.9 mi) 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 Observatory has no recorded 
cases of entanglement of marine mammals during the conduct of over 8 
years of seismic surveys covering over 160,934 km (86,897.4 nmi) of 
transect lines.
    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 
adverse 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

[[Page 10151]]

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 reversible and was considered 
in further detail earlier in this document, as behavioral modification. 
The main impact associated with the proposed activity would be 
temporarily elevated noise levels and the associated direct effects on 
marine mammals, 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 
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.
    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 scientific literature. As 
far as the Observatory, and we 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 temporary threshold shift 
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 temporary threshold shift (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 9 m in the former case and less than 2 m in the 
latter). Water depth sets a lower limit on the lowest sound frequency 
that will propagate (i.e., 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). They suspended the airgun 3.5 m (11.5 ft) 
above a school of threadfin shad in Lake Meade and 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.
    For a proposed seismic survey in Southern California, USGS (1999) 
conducted a review of the literature on the effects of airguns on fish 
and fisheries. They reported a 1991 study of the Bay Area Fault system 
from the continental shelf to the Sacramento River, using a 10 airgun 
(5,828 in\3\) array. Brezzina and Associates were hired by USGS to 
monitor the effects of the surveys, and concluded that airgun 
operations were not responsible for the

[[Page 10152]]

death of any of the fish carcasses observed, and the airgun profiling 
did not appear to alter the feeding behavior of sea lions, seals, or 
pelicans observed feeding during the seismic surveys.
    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, Alaska. The seismic survey 
proposed using three vessels, each towing two, four-airgun arrays 
ranging from 1,500 to 2,500 in\3\. The Minerals Management Service 
noted that the impact to fish populations in the survey area and 
adjacent waters would likely be very low and temporary and 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 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 in Appendix E of the 2011 PEIS (NSF/USGS, 
2011).
    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 cephalopod species (Loligo 
vulgaris, Sepia officinalis, Octopus vulgaris, and Ilex coindetii) to 
two hours of continuous sound from 50 to 400 Hz at 157  5 
dB re: 1 [mu]Pa. They reported lesions to the sensory hair cells of the 
statocysts of the exposed animals that

[[Page 10153]]

increased in severity with time, suggesting that cephalopods are 
particularly sensitive to low-frequency sound. The received sound 
pressure level was 157  5 dB re: 1 [micro]Pa, with peak 
levels at 175 dB re 1 [micro]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 under section 
101(a)(5)(D) of the MMPA, we must set forth the permissible methods of 
taking pursuant to such activity, and other means of effecting the 
least practicable adverse 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.
    The Observatory has reviewed the following source documents and 
have incorporated a suite of proposed mitigation measures into their 
project description.
    (1) Protocols used during previous Foundation and Observatory-
funded seismic research cruises as approved by us and detailed in the 
Foundation's 2011 PEIS;
    (2) Previous incidental harassment authorizations applications and 
authorizations that we have approved and authorized; 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, the Observatory, and/or its designees 
have proposed to implement the following mitigation measures for marine 
mammals:
    (1) Vessel-based visual mitigation monitoring;
    (2) Proposed exclusion zones;
    (3) Power down procedures;
    (4) Shutdown procedures;
    (5) Ramp-up procedures; and
    (6) Speed and course alterations.

Vessel-Based Visual Mitigation Monitoring

    The Observatory would position observers aboard the seismic source 
vessel to watch for marine mammals near the vessel during daytime 
airgun operations and during any start-ups at night. Observers would 
also watch for marine mammals near the seismic vessel for at least 30 
minutes prior to the start of airgun operations after an extended 
shutdown (i.e., greater than approximately eight minutes for this 
proposed cruise). When feasible, the observers would conduct 
observations during daytime periods when the seismic system is not 
operating for comparison of sighting rates and behavior with and 
without airgun operations and between acquisition periods. Based on the 
observations, the LANGSETH would power down or shutdown the airguns 
when marine mammals are observed within or about to enter a designated 
180-dB exclusion zone.
    During seismic operations, at least four protected species 
observers would be aboard the LANGSETH. The Observatory would appoint 
the observers with our concurrence and they would conduct observations 
during ongoing daytime operations and nighttime ramp-ups of the airgun 
array. During the majority of seismic operations, two observers would 
be on duty from the observation tower to monitor marine mammals near 
the seismic vessel. Using two observers would increase the 
effectiveness of detecting animals near the source vessel. However, 
during mealtimes and bathroom breaks, it is sometimes difficult to have 
two observers on effort, but at least one observer would be on watch 
during bathroom breaks and mealtimes. Observers would be on duty in 
shifts of no longer than four hours in duration.
    Two observers on the LANGSETH would also be on visual watch during 
all nighttime ramp-ups of the seismic airguns. A third observer would 
monitor the passive acoustic monitoring 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 observers 
(visual) on duty from the observation tower, and an observer (acoustic) 
on the passive acoustic monitoring system. Before the start of the 
seismic survey, the Observatory would instruct the vessel's crew to 
assist in detecting marine mammals and implementing mitigation 
requirements.
    The LANGSETH is a suitable platform for marine mammal observations. 
When stationed on the observation platform, the eye level would be 
approximately 21.5 m (70.5 ft) above sea level, and the observer would 
have a good view around the entire vessel. During daytime, the 
observers would 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 
would 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) would 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;

[[Page 10154]]

that is done primarily with the reticles in the binoculars.
    When the observers see marine mammals within or about to enter the 
designated exclusion zone, the LANGSETH would immediately power down or 
shutdown the airguns. The observer(s) would continue to maintain watch 
to determine when the animal(s) are outside the exclusion zone by 
visual confirmation. Airgun operations would not resume until the 
observer has confirmed that the animal has left the 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).
    Proposed Exclusion Zones--The Observatory would use safety radii to 
designate exclusion zones and to estimate take for marine mammals. 
Table 1 (presented earlier in this document) shows the distances at 
which one would expect to receive three sound levels (160- and 180-dB) 
from the 36-airgun array and a single airgun. The 180-dB level shutdown 
criteria are applicable to cetaceans as specified by us (2000). The 
Observatory used these levels to establish the exclusion zones.
    If the protected species visual observer detects marine mammal(s) 
within or about to enter the appropriate exclusion zone, the LANGSETH 
crew would immediately power down the airgun array, or perform a 
shutdown if necessary (see Shut-down Procedures).
    Power Down Procedures-A power down involves decreasing the number 
of airguns in use such that the radius of the 180-dB zone is smaller to 
the extent that marine mammals are no longer within or about to enter 
the exclusion zone. A power down of the airgun array can also occur 
when the vessel is moving from one seismic line to another. During a 
power down for mitigation, the LANGSETH would operate one airgun (40 
in\3\). The continued operation of one airgun is intended to alert 
marine mammals to the presence of the seismic vessel in the area. A 
shutdown occurs when the LANGSETH suspends all airgun activity.
    If the observer detects a marine mammal outside the exclusion zone 
and the animal is likely to enter the zone, the crew would power down 
the airguns to reduce the size of the 180-dB exclusion zone before the 
animal enters that zone. Likewise, if a mammal is already within the 
zone when first detected, the crew would power-down the airguns 
immediately. During a power down of the airgun array, the crew would 
operate a single 40-in\3\ airgun which has a smaller exclusion zone. If 
the observer detects a marine mammal within or near the smaller 
exclusion zone around the airgun (Table 1), the crew would shut down 
the single airgun (see next section).
    Resuming Airgun Operations After a Power Down--Following a power-
down, the LANGSETH crew would not resume full airgun activity until the 
marine mammal has cleared the 180-dB exclusion zone (see Table 1). The 
observers would 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 LANGSETH crew would 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 would 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).
    We estimate that the LANGSETH would transit outside the original 
180-dB exclusion zone after an 8-minute wait period. This period is 
based on the 180-dB exclusion zone for the 36-airgun array towed at a 
depth of 12 m (39.4 ft) in relation to the average speed of the 
LANGSETH while operating the airguns (8.5 km/h; 5.3 mph). 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 
observers are continually monitoring the exclusion zone for the full 
source level while the mitigation airgun is firing. On average, 
observers can observe to the horizon (10 km; 6.2 mi) from the height of 
the LANGSETH's observation deck and should be able to say with a 
reasonable degree of confidence whether a marine mammal would be 
encountered within this distance before resuming airgun operations at 
full power.
    Shutdown Procedures--The LANGSETH crew would shutdown the operating 
airgun(s) if a marine mammal is seen within or approaching the 
exclusion zone for the single airgun. The crew would implement a 
shutdown:
    (1) If an animal enters the exclusion zone of the single airgun 
after the crew 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.
    Considering the conservation status for north Pacific right whales, 
the LANGSETH crew would shutdown the airgun(s) immediately in the 
unlikely event that this species is observed, regardless of the 
distance from the vessel. The LANGSETH would only begin ramp-up would 
only if the north Pacific right whale has not been seen for 30 minutes.
    Resuming Airgun Operations After a Shutdown--Following a shutdown 
in excess of eight minutes, the LANGSETH crew would initiate a ramp-up 
with the smallest airgun in the array (40-in\3\). The crew would turn 
on additional airguns in a sequence such that the source level of the 
array would increase in steps not exceeding 6 dB per five-minute period 
over a total duration of approximately 30 minutes. During ramp-up, the 
observers would monitor the exclusion zone, and if he/she sights a 
marine mammal, the LANGSETH crew would implement a power down or 
shutdown as though the full airgun array were operational.
    During periods of active seismic operations, there are occasions 
when the LANGSETH crew would need to temporarily 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 would follow 
ramp-up procedures for a shutdown described earlier and the observers 
would monitor the full exclusion zone and would implement a power down 
or shutdown if necessary.
    If the full exclusion zone is not visible to the observer for at 
least 30 minutes prior to the start of operations in either daylight or 
nighttime, the LANGSETH crew would 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 would not ramp up the airgun array 
from a complete shutdown at night or in thick fog, because the outer 
part of the zone

[[Page 10155]]

for that array would not be visible during those conditions.
    If one airgun has operated during a power down period, ramp-up to 
full power would be permissible at night or in poor visibility, on the 
assumption that marine mammals would be alerted to the approaching 
seismic vessel by the sounds from the single airgun and could move 
away. The vessel's crew would not initiate a 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. The Observatory would follow a 
ramp-up procedure when the airgun array begins operating after an 8 
minute period without airgun operations or when shut down has exceeded 
that period. The Observatory has used similar waiting periods 
(approximately eight to 10 minutes) during previous seismic surveys.
    Ramp-up would begin with the smallest airgun in the array (40 
in\3\). The crew would add airguns in a sequence such that the source 
level of the array would increase in steps not exceeding six dB per 
five minute period over a total duration of approximately 30 to 35 
minutes. During ramp-up, the observers would monitor the exclusion 
zone, and if marine mammals are sighted, the Observatory would 
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, the Observatory would 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 crew would not ramp up the airgun array from a 
complete shut-down at night or in thick fog, because the outer part of 
the exclusion zone for that array would not be visible during those 
conditions. If one airgun has operated during a power-down period, 
ramp-up to full power would be permissible at night or in poor 
visibility, on the assumption that marine mammals would be alerted to 
the approaching seismic vessel by the sounds from the single airgun and 
could move away. The Observatory would not initiate a ramp-up of the 
airguns if a marine mammal is sighted within or near the applicable 
exclusion zones.

Speed and Course Alterations

    If during seismic data collection, the Observatory detects marine 
mammals outside the exclusion zone and, based on the animal's position 
and direction of travel, is likely to enter the exclusion zone, the 
LANGSETH would change speed and/or direction if this does not 
compromise operational safety. Due to the limited maneuverability of 
the primary survey vessel, altering speed and/or course can result in 
an extended period of time to realign onto the transect. However, if 
the animal(s) appear likely to enter the exclusion zone, the LANGSETH 
would undertake further mitigation actions, including a power down or 
shut down of the airguns.
    We have carefully evaluated the applicant's proposed mitigation 
measures and have considered a range of other measures in the context 
of ensuring that we have prescribed the means of effecting the least 
practicable adverse impact on the affected marine mammal species and 
stocks and their habitat. Our 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, we expect that 
the successful implementation of the measure would 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 incidental take authorization for an activity, 
section 101(a)(5)(D) of the MMPA states that we must set forth 
``requirements pertaining to the monitoring and reporting of such 
taking.'' The Act's implementing regulations at 50 CFR 216.104 (a)(13) 
indicate that requests for an authorization must include the suggested 
means of accomplishing the necessary monitoring and reporting that 
would result in increased knowledge of the species and our expectations 
of the level of taking or impacts on populations of marine mammals 
present in the action area.

Proposed Monitoring

    The Observatory proposes to sponsor marine mammal monitoring during 
the present project to supplement the mitigation measures that require 
real-time monitoring, and to satisfy the monitoring requirements of the 
Incidental Harassment Authorization. The Observatory understands that 
this monitoring plan would be subject to review by us, and that we may 
require refinements to the plan. The Observatory planned the monitoring 
work as a self-contained project independent of any other related 
monitoring projects that may occur in the same regions at the same 
time. Further, the Observatory is prepared to discuss coordination of 
its monitoring program with any other related work that might be 
conducted by other groups working insofar as it is practical and 
desirable.

Vessel-Based Passive Acoustic Monitoring

    Passive acoustic monitoring would complement the visual mitigation 
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. Passive acoustical monitoring 
can be used in conjunction with visual observations to improve 
detection, identification, and localization of cetaceans. The passive 
acoustic monitoring would serve to alert visual observers (if on duty) 
when vocalizing cetaceans are detected. It is only useful when marine 
mammals call, but it can be effective either by day or by night, and 
does not depend on good visibility. The acoustic observer would monitor 
the system in real time so that he/she can advise the visual observers 
if they acoustic detect cetaceans.
    The passive acoustic monitoring 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 LANGSETH crew would deploy the array from a 
winch located on the back deck. A deck cable would connect the tow 
cable to the electronics unit in the main computer lab where the 
acoustic station, signal conditioning, and processing system would be 
located. The acoustic signals received by the hydrophones are 
amplified, digitized, and then processed by the Pamguard software. The 
system

[[Page 10156]]

can detect marine mammal vocalizations at frequencies up to 250 kHz.
    One acoustic observer, an expert bioacoustician with primary 
responsibility for the passive acoustic monitoring system would be 
aboard the LANGSETH in addition to the four visual observers. The 
acoustic observer would monitor the towed hydrophones 24 hours per day 
during airgun operations and during most periods when the LANGSETH is 
underway while the airguns are not operating. However, passive acoustic 
monitoring may not be possible if damage occurs to both the primary and 
back-up hydrophone arrays during operations. The primary passive 
acoustic monitoring 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 acoustic observer would 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 observer monitoring the 
acoustical data would be on shift for one to six hours at a time. The 
other observers would rotate as an acoustic observer, although the 
expert acoustician would be on passive acoustic monitoring duty more 
frequently.
    When the acoustic observer detects a vocalization while visual 
observations are in progress, the acoustic observer on duty would 
contact the visual observer immediately, to alert him/her to the 
presence of cetaceans (if they have not already been seen), so that the 
vessel's crew can initiate a power down or shutdown, if required. The 
observer would enter the information regarding the call into a 
database. Data entry would 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.

Observer Data and Documentation

    Observers would record data to estimate the numbers of marine 
mammals exposed to various received sound levels and to document 
apparent disturbance reactions or lack thereof. They would use the data 
to estimate numbers of animals potentially `taken' by harassment (as 
defined in the MMPA). 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.
    When an observer makes a sighting, they will record the following 
information:
    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 observer will record the data listed under (2) 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.
    Observers will record all observations and power downs or shutdowns 
in a standardized format and will enter data into an electronic 
database. The observers will verify the accuracy of the data entry by 
computerized data validity checks as the data are entered and by 
subsequent manual checking of the database. These procedures will allow 
the preparation of initial summaries of data 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 
shutdown).
    2. Information needed to estimate the number of marine mammals 
potentially taken by harassment, which the Observatory must report to 
the Office of Protected Resources.
    3. Data on the occurrence, distribution, and activities of marine 
mammals and turtles in the area where the Observatory would conduct the 
seismic study.
    4. Information to compare the distance and distribution of marine 
mammals and turtles relative to the source vessel at times with and 
without seismic activity.
    5. Data on the behavior and movement patterns of marine mammals 
detected during non-active and active seismic operations.

Proposed Reporting

    The Observatory would submit a report to us and to the Foundation 
within 90 days after the end of the cruise. The report would describe 
the operations that were conducted and sightings of marine mammals and 
turtles near the operations. The report would provide full 
documentation of methods, results, and interpretation pertaining to all 
monitoring. The 90-day report would summarize the dates and locations 
of seismic operations, and all marine mammal sightings (dates, times, 
locations, activities, associated seismic survey activities). The 
report would also include estimates of the number and nature of 
exposures that could result in ``takes'' of marine mammals by 
harassment or in other ways.
    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 Observatory 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 use 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 the animal(s) 
involved;
     Fate of the animal(s); and
     Photographs or video footage of the animal(s) (if 
equipment is available).
    The Observatory shall not resume its activities until we are able 
to review the circumstances of the prohibited take. We shall work with 
the Observatory to determine what is necessary to minimize the 
likelihood of further prohibited take and ensure MMPA compliance. The 
Observatory may not resume their activities until notified by us via 
letter, email, or telephone.
    In the event that the Observatory discovers an injured or dead 
marine

[[Page 10157]]

mammal, and the lead visual observer 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 we describe in the next 
paragraph), the Observatory 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 we review the circumstances of the 
incident. We would work with the Observatory to determine whether 
modifications in the activities are appropriate.
    In the event that the Observatory discovers an injured or dead 
marine mammal, and the lead visual observer 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 Observatory would 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], 
within 24 hours of the discovery. The Observatory would provide 
photographs or video footage (if available) or other documentation of 
the stranded animal sighting to us.

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].
    We propose to authorize take by Level B harassment for the proposed 
seismic survey. Acoustic stimuli (i.e., increased underwater sound) 
generated during the operation of the seismic airgun array may have the 
potential to result in the behavioral disturbance of some marine 
mammals. There is no evidence that planned activities could result in 
serious injury or mortality within the specified geographic area for 
the requested authorization. The required mitigation and monitoring 
measures would minimize any potential risk for serious injury or 
mortality.
    The following sections describe the Observatory's methods to 
estimate take by incidental harassment and present their estimates of 
the numbers of marine mammals that could be affected during the 
proposed seismic program. The estimates are based on a consideration of 
the number of marine mammals that could be harassed by seismic 
operations with the 36-airgun array during approximately 5,572 km\2\ 
(2,151 mi\2\) of transect lines on the Mid-Atlantic Ridge in the north 
Atlantic Ocean, as depicted in Figure 1 of the application.
    We assume that during simultaneous operations of the airgun array 
and the other sources, any marine mammals close enough to be affected 
by the 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, we expect that the marine 
mammals would exhibit no more than short-term and inconsequential 
responses to the echosounder and profiler given their characteristics 
(e.g., narrow downward-directed beam) and other considerations 
described previously. Based on the best available information, we do 
not consider that these reactions constitute a ``take'' (NMFS, 2001). 
Therefore, the Observatory did not provide any additional allowance for 
animals that could be affected by sound sources other than the airguns.
    Ensonified Area Calculations--Because the Observatory assumes that 
the LANGSETH may need repeat some tracklines, accommodate the turning 
of the vessel, address equipment malfunctions, or conduct equipment 
testing to complete the survey; they have increased the proposed number 
of line-kilometers for the seismic operations by 25 percent (i.e., 
contingency lines).
    Density Information--The Observatory based the density estimates on 
information calculated from sightings, effort, mean group sizes, and 
values for f(0) for the southern part of the survey area in Waring et 
al. (2008), which extends from the Azores at approximately 38[deg] N to 
53[deg] N. The allocated densities calculated for undifferentiated 
``common/striped dolphins'' to common and striped dolphins in 
proportion to the calculated densities of the two species. The density 
calculated for ``unidentified dolphin'' was allocated to bottlenose, 
Atlantic spotted, and Risso's dolphins, species that could occur in the 
proposed survey area based on their presence in the Azores, in 
proportion to the number of sightings in the OBIS database for those 
species around the Azores. The density calculated for ``unidentified 
small whale'' was allocated to the false killer whale, the one small 
whale species that could occur in the proposed survey area based on its 
presence in the Azores. The four ``long-finned/short-finned pilot 
whales'' sighted in the southern part of the survey area by Waring et 
al. (2008) were assumed to be short-finned pilot whales based on OBIS 
sightings around the Azores. The density calculated for the one ``sei/
Bryde's whale'' sighting in the southern part of the survey area was 
allocated to sei and Bryde's whales in equal proportions. The authors' 
calculated value of f(0) for the sei whale was used for calculating 
densities of Bryde's, fin, and blue whales, and that for ``small 
Delphinidae'' was used for calculating densities of Mesoplodon spp., 
dolphins, the false killer whale, and the short-finned pilot whale. 
Because the survey effort in the southern stratum of Waring et al. 
(2008) is limited (1,047 km; 650 mi), the survey area is north of the 
proposed seismic area (38-52[deg] N versus 36-36.5[deg] N), and the 
survey was conducted during a somewhat different season (June versus 
April-May), there is some uncertainty about the representativeness of 
the data and the assumptions used in the calculations.
    Exposure Estimation--The Observatory estimated the number of 
different individuals that could be exposed to airgun sounds with 
received levels greater than or equal to 160 dB re: 1 [micro]Pa on one 
or more occasions by considering the total marine area that would be 
within the 160-dB radius around the operating airgun array on at least 
one occasion and the expected density of marine mammals. The number of 
possible exposures (including repeat 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, excluding areas 
of overlap. Some individuals may be exposed multiple times since the 
survey tracklines are spaced close together, however, it is unlikely 
that a particular animal would stay in the area during the entire 
survey.
    The number of different individuals potentially exposed to received 
levels greater than or equal to 160 re: 1 [micro]Pa (rms) was 
calculated by multiplying:
    (1) The expected species density (in number/km\2\), times
    (2) The anticipated area to be ensonified to that level during 
airgun operations (5,571 km\2\; (2,151 mi\2\).

[[Page 10158]]

    The Observatory's estimates of exposures to various sound levels 
assume that the proposed surveys would be carried out in full (i.e., 
approximately 20 days of seismic airgun operations), however, the 
ensonified areas calculated using the planned number of line-kilometers 
have been increased by 25 percent to accommodate lines that may need to 
be repeated, equipment testing, account for repeat exposure, etc. As is 
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.

  Table 3--Estimates of the Possible Numbers of Marine Mammals Exposed to Sound Levels Greater Than or Equal to
 160 dB re: 1 [mu]Pa During the Proposed Seismic Survey Over the Mid-Atlantic Ridge in the North Atlantic Ocean,
                                         During April Through June, 2013
----------------------------------------------------------------------------------------------------------------
                                           Estimated number of
                                           individuals exposed    Requested  or                       Approx.
                 Species                      to sound levels     adjusted take      Regional       percent of
                                              >=160 dB re: 1      authorization   population \3\     regional
                                               [micro]Pa\1\            \2\                        population \3\
----------------------------------------------------------------------------------------------------------------
Mysticetes:
    North Atlantic right whale...........                    0                 0               0               0
    Humpback whale.......................                    0             \4\ 2               0               0
    Minke whale..........................                    0             \4\ 3               0               0
    Bryde's whale........................                    1                 1             N/A             N/A
    Sei whale............................                    1                 1          13,000            0.01
    Fin whale............................                   25                25          24,887            0.10
    Blue whale...........................                    8                 8             937            0.89
Odontocetes                                ...................                21  ..............            0.16
    Sperm whale..........................                   21  ................          13,190  ..............
    Pygmy sperm whale....................                    0                 0             395               0
    Dwarf sperm whale....................                    0                 0             395               0
    Cuvier's beaked whale................                    0             \4\ 7           3,513             0.2
    Mesoplodon spp.......................  ...................  ................  ..............  ..............
    True's beaked whale..................  ...................  ................  ..............  ..............
    Gervais beaked whale.................                   39                39  ..............            1.12
    Sowerby's beaked whale...............  ...................  ................  ..............  ..............
    Blainville's beaked whale............  ...................  ................           3,502  ..............
    Northern bottlenose whale............                    0             \4\ 4         ~40,000               0
    Rough-toothed dolphin................                    0                 0             N/A               0
    Common bottlenose dolphin............                   47                47          81,588            0.06
    Pantropical spotted dolphin..........                    0                 0           4,439               0
    Atlantic spotted dolphin.............                  112               112          50,978            0.22
    Striped dolphin......................                1,034             1,034          94,462            1.09
    Short-beaked common dolphin..........                2,115             2,115         120,741            1.75
    Risso's dolphin......................                   21                21          20,479            0.10
    Pygmy killer whale...................                    0                 0             N/A               0
    False killer whale...................                    7                 7             N/A             N/A
    Killer whale.........................                    0             \4\ 5             N/A               0
    Long-finned pilot whale..............                    0                 0         780,000               0
    Short-finned pilot whale.............                  674               674         780,000            0.09
----------------------------------------------------------------------------------------------------------------
N/A = Not Available.
\1\ Estimates are based on densities in Table 2 and an ensonified area of (5,571 km\2\; (2,151 mi\2\)
\2\ Requested or adjusted take includes a 25 percent contingency for repeated exposures due to the overlap of
  parallel survey tracks.
\3\ Regional population size estimates are from Table 2.
\4\ Requested take authorization increased to group size for species for which densities were not calculated but
  for which there were OBIS sightings around the Azores.

Encouraging and Coordinating Research

    The Observatory would coordinate the planned marine mammal 
monitoring program associated with the seismic survey on the Mid-
Atlantic Ridge in the north Atlantic Ocean with other parties that may 
have interest in the area and/or may be conducting marine mammal 
studies in the same region during the seismic surveys.

Negligible Impact and Small Numbers Analysis and Determination

    We have 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, 
we consider:
    (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.
    For reasons stated previously in this document and based on the 
following factors, the specified activities associated with the marine 
seismic surveys are not likely to cause permanent threshold shift, or 
other non-auditory injury, serious injury, or death. They include:

[[Page 10159]]

    (1) The likelihood that, given sufficient notice through relatively 
slow ship speed, we expect marine mammals 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 that we would likely avoid this impact through the 
incorporation of the required monitoring and mitigation measures 
(including power-downs and shutdowns); and
    (3) The likelihood that marine mammal detection ability by trained 
visual observers is high at close proximity to the vessel.
    We do not anticipate that any injuries, serious injuries, or 
mortalities would occur as a result of the Observatory's planned marine 
seismic surveys, and we do not propose to authorize injury, serious 
injury or mortality for this survey. We anticipate only behavioral 
disturbance to occur during the conduct of the survey activities.
    Table 4 in this document outlines the number of requested Level B 
harassment takes that we anticipate as a result of these activities. 
Due to the nature, degree, and context of Level B (behavioral) 
harassment anticipated and described (see ``Potential Effects on Marine 
Mammals'' section in this notice), we do not expect the activity to 
impact rates of recruitment or survival for any affected species or 
stock.
    Further, the seismic surveys would not take place in areas of 
significance for marine mammal feeding, resting, breeding, or calving 
and would 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 hour 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 we anticipate 
that the seismic operations would occur on consecutive days, the 
estimated duration of the survey would last no more than 20 days. 
Additionally, the seismic survey would 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.
    Of the 28 marine mammal species under our jurisdiction that are 
known to occur or likely to occur in the study area, six of these 
species are listed as endangered under the ESA, including: The blue, 
fin, humpback, north Atlantic right, sei, and sperm whales. These 
species are also categorized as depleted under the MMPA. With the 
exception of the north Atlantic right whale, the Observatory has 
requested authorized take for these listed species.
    As mentioned previously, we estimate that 28 species of marine 
mammals under our jurisdiction could be potentially affected by Level B 
harassment over the course of the proposed authorization. For each 
species, these take numbers are small (most estimates are less than or 
equal to two percent) relative to the regional or overall population 
size and we have provided the regional population estimates for the 
marine mammal species that may be taken by Level B harassment in Table 
4 in this document.
    Our practice has been to apply the 160 dB re: 1 [micro]Pa received 
level threshold for underwater impulse sound levels to determine 
whether take by Level B harassment occurs. Southall et al. (2007) 
provides 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]).
    We have preliminarily determined, provided that the aforementioned 
mitigation and monitoring measures are implemented, that the impact of 
conducting a proposed survey on the Mid-Atlantic Ridge in the north 
Atlantic Ocean in international waters, from April 2013 through June 
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 these species may make behavioral modifications, including 
temporarily vacating the area during the operation of the airgun(s) to 
avoid the resultant acoustic disturbance, the availability of alternate 
areas within these areas and the short and sporadic duration of the 
research activities, have led us to preliminary determine that this 
action would have a negligible impact on the species in the specified 
geographic region.
    Based on the analysis contained herein of the likely effects of the 
specified activity on marine mammals and their habitat, and taking into 
consideration the implementation of the mitigation and monitoring 
measures, we preliminarily find that the Observatory's planned research 
activities would result in the incidental take of small numbers of 
marine mammals, by Level B harassment only, and that the required 
measures mitigate impacts to affected species or stocks of marine 
mammals to the lowest level practicable.

Impact on Availability of Affected Species or Stock for Taking for 
Subsistence Uses

    Section 101(a)(5)(D) of the Marine Mammal Protection Act also 
requires us to determine that the authorization would 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 (on the Mid-Atlantic Ridge in the 
north Atlantic Ocean in international waters) that implicate section 
101(a)(5)(D) of the Marine Mammal Protection Act.

Endangered Species Act

    Of the species of marine mammals that may occur in the proposed 
survey area, several are listed as endangered under the Endangered 
Species Act, including the blue, fin, humpback, north Atlantic right, 
sei, and sperm whales. The Observatory did not request take of 
endangered north Atlantic right whales because of the low likelihood of 
encountering these species during the cruise.
    Under section 7 of the Act, the Foundation has initiated formal 
consultation with the Service's, Office of Protected Resources, 
Endangered Species Act Interagency Cooperation Division, on this 
proposed seismic survey. We (i.e., National Marine Fisheries Service, 
Office of Protected Resources, Permits and Conservation Division), have 
also initiated formal consultation under section 7 of the Act with the 
Endangered Species Act Interagency Cooperation Division to obtain a 
Biological Opinion (Opinion) evaluating the effects of issuing an 
incidental harassment authorization for threatened and endangered 
marine mammals and, if appropriate, authorizing incidental take. Both 
agencies would conclude the formal section 7 consultation (with a 
single Biological Opinion for the Foundation's Division of Ocean 
Sciences and NMFS' Office of Protected Resources, Permits and 
Conservation Division federal actions) prior to making a determination 
on whether or not to issue the authorization. If we issue the take 
authorization, the Foundation and the Observatory must comply with the 
mandatory Terms and Conditions of the Opinion's Incidental Take 
Statement which would incorporate the mitigation and monitoring 
requirements included

[[Page 10160]]

in the Incidental Harassment Authorization.

National Environmental Policy Act (NEPA)

    To meet our NEPA requirements for the issuance of an IHA to the 
Observatory, we intend to prepare an Environmental Assessment (EA) 
titled ``Issuance of an Incidental Harassment Authorization to the 
Lamont-Doherty Earth Observatory to Take Marine Mammals by Harassment 
Incidental to a Marine Geophysical on the Mid-Atlantic Ridge in the 
north Atlantic Ocean, from April 2013 through June 2013.'' This EA 
would incorporate as appropriate the Foundation's Environmental 
Analysis Pursuant To Executive Order 12114 (NSF, 2010) titled, ``Marine 
geophysical survey by the R/V MARCUS G. Langseth on the mid-Atlantic 
Ridge, April-May 2013,'' by reference pursuant to 40 CFR 1502.21 and 
NOAA Administrative Order (NAO) 216-6 Sec.  5.09(d). Prior to making a 
final decision on the IHA application, we would decide whether or not 
to issue a Finding of No Significant Impact (FONSI).
    The Foundation's environmental analysis is available for review at 
the addresses set forth earlier in this notice. This notice and the 
documents it references provide all relevant environmental information 
related to our proposal to issue the IHA. We invite the public's 
comment and will consider any comments related to environmental effects 
related to the proposed issuance of the IHA submitted in response to 
this as we conduct and finalize our NEPA analysis.

Proposed Authorization

    As a result of these preliminary determinations, we propose to 
authorize the take of marine mammals incidental to the Observatory's 
proposed marine seismic surveys on the Mid-Atlantic Ridge in the north 
Atlantic Ocean from April 2013, through June 2013, provided the 
previously mentioned mitigation, monitoring, and reporting requirements 
are incorporated. The duration of the incidental harassment 
authorization would not exceed one year from the date of its issuance.

Information Solicited

    We request interested persons to submit comments and information 
concerning this proposed project and our preliminary determination of 
issuing a take authorization (see ADDRESSES). Concurrent with the 
publication of this notice in the Federal Register, we will forward 
copies of this application to the Marine Mammal Commission and its 
Committee of Scientific Advisors.

    Dated: February 6, 2013.
Matthew J. Brookhart,
Acting Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. 2013-03321 Filed 2-12-13; 8:45 am]
BILLING CODE 3510-22-P