[Federal Register Volume 78, Number 150 (Monday, August 5, 2013)]
[Notices]
[Pages 47496-47526]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2013-18822]



[[Page 47495]]

Vol. 78

Monday,

No. 150

August 5, 2013

Part II





Department of Commerce





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National Oceanic and Atmospheric Administration





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 Takes of Marine Mammals Incidental to Specified Activities; Taking 
Marine Mammals Incidental to Marine Seismic Survey in the Chukchi Sea, 
Alaska; Notice

  Federal Register / Vol. 78 , No. 150 / Monday, August 5, 2013 / 
Notices  

[[Page 47496]]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XC562


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to Marine Seismic Survey in the 
Chukchi Sea, Alaska

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

ACTION: Notice; issuance of an incidental take authorization.

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SUMMARY: In accordance with the Marine Mammal Protection Act (MMPA) 
regulations, notification is hereby given that NMFS has issued an 
Incidental Harassment Authorization (IHA) to Shell Gulf of Mexico Inc. 
(Shell) to take, by harassment, small numbers of 13 species of marine 
mammals incidental to a marine survey program in the Chukchi Sea, 
Alaska, during the 2013 Arctic open-water season. Pursuant to the 
Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its 
proposal to issue an IHA to Shell to take, by Level B harassment, 13 
species of marine mammals during the specified activity.

DATES: Effective July 1, 2013, through October 31, 2013.

ADDRESSES: Inquiry for information on the incidental take authorization 
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. A 
copy of the application containing a list of the references used in 
this document, NMFS' Environmental Assessment (EA), Finding of No 
Significant Impact (FONSI), and the IHA may be obtained by writing to 
the address specified above, telephoning the contact listed below (see 
FOR FURTHER INFORMATION CONTACT), or visiting the Internet at: http://www.nmfs.noaa.gov/pr/permits/incidental.htm#applications.
    Documents cited in this notice may be viewed, by appointment, 
during regular business hours, at the aforementioned address.

FOR FURTHER INFORMATION CONTACT: Shane Guan, Office of Protected 
Resources, NMFS, (301) 427-8401 or Brad Smith, NMFS, Alaska Region, 
(907) 271-3023.

SUPPLEMENTARY INFORMATION: 

Background

    Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.) 
direct the Secretary of Commerce to allow, upon request, the 
incidental, but not intentional, taking of small numbers of marine 
mammals by U.S. citizens who engage in a specified activity (other than 
commercial fishing) within a specified geographical region if certain 
findings are made and either regulations are issued or, if the taking 
is limited to harassment, a notice of a proposed authorization is 
provided to the public for review.
    Authorization for incidental takings shall be granted if NMFS finds 
that the taking will have a negligible impact on the species or 
stock(s), will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for subsistence uses (where 
relevant), and if the permissible methods of taking and requirements 
pertaining to the mitigation, monitoring and reporting of such takings 
are set forth. NMFS has defined ``negligible impact'' in 50 CFR 216.103 
as ``...an impact resulting from the specified activity that cannot be 
reasonably expected to, and is not reasonably likely to, adversely 
affect the species or stock through effects on annual rates of 
recruitment or survival.''
    Section 101(a)(5)(D) of the MMPA established an expedited process 
by which citizens of the U.S. can apply for an authorization to 
incidentally take small numbers of marine mammals by harassment. 
Section 101(a)(5)(D) establishes a 45-day time limit for NMFS review of 
an application followed by a 30-day public notice and comment period on 
any proposed authorizations for the incidental harassment of marine 
mammals. Within 45 days of the close of the comment period, NMFS must 
either issue or deny 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

    NMFS received an application on January 2, 2013, from Shell for the 
taking, by harassment, of marine mammals incidental to a marine surveys 
program in the Beaufort and Chukchi seas, Alaska, during the open-water 
season of 2013. Subsequently, Shell revised its proposed marine surveys 
program and limited its activities to the Chukchi Sea, and resubmitted 
an IHA application on March 25, 2013. Based on NMFS comments, Shell 
further revised its IHA application and submitted its final IHA 
application on April 2, 2013.

Description of the Specified Activity

    Shell plans to complete a marine surveys program and conduct its 
equipment recovery and maintenance activity, during the 2013 open-water 
season in the Chukchi Sea. A total of three vessels would be utilized 
for the proposed open-water activities: the marine surveys would be 
conducted from a single vessel, a second vessel would be used for 
equipment recovery and maintenance activity at Burger A, and a third 
vessel may be used to provide logistical support to either and/or both 
operations. Overall, Shell's 2013 open-water marine surveys program 
includes the following three components:
     Chukchi Sea Offshore Ice Gouge Surveys;
     Chukchi Sea Offshore Site Clearance and Shallow Hazards 
Survey; and
     Equipment Recovery and Maintenance
    Detailed locations of these activities are shown in Figures 1-1 
through 1-3 of Shell's IHA application.
    Ice and weather conditions will influence when and where the open-
water marine surveys will be conducted. For initial planning purposes, 
Shell states that the offshore marine surveys and equipment recovery 
and maintenance would be conducted within the time frame of July 
through October 2013.

Chukchi Sea Offshore Ice Gouge Surveys

    Ice gouge information is required for the design of potential 
pipelines and pipeline trenching and installation equipment. Ice gouges 
are created by ice keels that project from the bottom of ice, and gouge 
the seafloor sediment as the ice moves with the wind or currents. Ice 
gouge features can be mapped and surveyed, and by surveying the same 
locations from year to year, new gouges can be identified and the rate 
of ice gouging can be estimated. The resulting ice gouge information 
would assist Shell in predicting the probability, frequency, 
orientation, and depth of future ice gouges.
    Shell plans to conduct ice gouge surveys along approximately 621 mi

[[Page 47497]]

(1,000 km) of tracklines in the Chukchi Sea in 2013, within the area 
denoted in Figure 1-1 of the IHA application. These surveys will: (a) 
Resurvey selected tracklines for ice gouge features to determine the 
rate or frequency of new ice gouges; and (b) map seafloor topography 
and characterize the upper 34 ft (10 m) of the seabed (seafloor and 
sub-seafloor) using acoustic methods. The ice gouge surveys will be 
conducted using the conventional survey method where the acoustic 
instrumentation will be towed behind the survey vessel. These acoustic 
instrumentation includes dual-frequency side scan sonar, single-beam 
bathymetric sonar, multi-beam bathymetric sonar, shallow sub-bottom 
profiler, and magnetometer.
    Due to the low intensity and high frequency acoustic sources being 
used for the proposed ice gouge surveys, this activity is not expected 
to result in takes of marine mammals.

Chukchi Sea Site Clearance and Shallow Hazards Surveys

    The proposed site clearance and shallow hazards surveys are to 
gather data on: (1) Bathymetry, (2) seabed topography and other seabed 
characteristics (e.g., ice gouges), (3) potential shallow geohazards 
(e.g., shallow faults and shallow gas zones), and (4) the presence of 
any possible archeological features (prehistoric or historic, e.g., 
middens, shipwrecks). Marine surveys for site clearance and shallow 
hazard surveys can be accomplished by one vessel with acoustic sources.
    Shell plans to conduct site clearance and shallow hazards surveys 
along approximately 3,200 kilometers (km) of tracklines in the Chukchi 
Sea in 2013 (see Figure 1-2 of the IHA application). These surveys 
would characterize the upper 1,000 meters (m) (3,128 feet [ft]) of the 
seabed and sub seafloor topography and measure water depths of 
potential exploratory drilling locations using acoustic methods. The 
site clearance and shallow hazard surveys would be conducted using the 
conventional survey method where the acoustic instrumentation will be 
towed behind the survey vessel. The acoustic instrumentation used in 
site clearance and shallow hazards surveys is largely the same as those 
for the offshore ice gouge surveys, but also includes a 4 x 10 cubic 
inch (in\3\) airgun array.

Equipment Recovery and Maintenance

    Shell's proposed equipment recovery and maintenance activities 
would occur at the Burger A well site in the Chukchi Sea (see Figure 1-
3 of the IHA application). The equipment recovery and maintenance 
activity would be accomplished by one vessel operating in dynamic 
positioning (DP) mode for an extended period over the drilling site. 
The vessel may be resupplied during the activity by vessel or aircraft.
    Work would be conducted subsea within the mudline cellar (MLC; ~ 20 
ft wide by 40 ft. deep excavation dug for the Burger A wellhead during 
2012 drilling at this well site) with a suite of Remotely Operated 
Vehicles (ROV) and divers that would recover equipment left sub-mudline 
on the well head during the 2012 open water drilling season. The survey 
vessel would be dynamically positioned at the well site for up to ~28 
days while subsurface equipment recovery and maintenance occurs, 
however Shell anticipates this work being accomplished in less than 28 
days. During this planned work scope the state and integrity of the 
well would not be changed since no form of entry will be made into the 
well.

Acoustic Equipment and Vessels Planned to be Used

    For the proposed site clearance and shallow hazards surveys, Shell 
plans to use the same 4 x 10 in\3\ airgun array configuration that was 
used during site clearance and shallow hazards surveys in the Chukchi 
Sea in 2008 and 2009. Measurements during these two years occurred at 
three locations: Honeyguide (west of the Crackerjack prospect), 
Crackerjack, and Burger. The distances to various threshold radii from 
those measurements are shown in Table 1. The 160 dB (rms) re 1 
[micro]Pa radius that was measured at the Burger location was the 
largest of the three sites.

     Table 1--Measured distances in (Meters) to Received Sound Levels From a 4 x 10\3\ Airgun Array at Three
                                      Locations in the Alaskan Chukchi Sea
----------------------------------------------------------------------------------------------------------------
                                                           Received Sound Level (dB re 1 [micro]Pa rms)
                    Location                     ---------------------------------------------------------------
                                                        190             180             160             120
----------------------------------------------------------------------------------------------------------------
Honeyguide......................................              41             100             600          22,000
Crackerjack.....................................              50             160           1,400          24,000
Burger..........................................              39             150           1,800          31,000
----------------------------------------------------------------------------------------------------------------

    Sound source characteristics that would be used during the site 
clearance and shallow hazard surveys and ice gouge surveys include 
single-beam bathymetric sonar, multi-beam bathymetric sonar, dual 
frequency side-scan sonar, shallow sub-bottom profiler, and an ultra-
short baseline acoustic positioning system. Representative source 
characteristics of these acoustic instrumentation were measured during 
Statoil's 2011 marine survey program in the Chukchi Sea (Warner and 
McCrodan 2011), and are listed in Table 2.

   Table 2--Source Characteristics and Distances to 160 dB (rms) re 1 [micro]Pa Sound Levels From Acoustic Instrumentation Measured in the Chukchi Sea
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                                                           Center                                      Nominal Source
         Instrument type                 Model            Frequency       Frequency      Beam Width    Level (dB re 1  In-beam 160 dB   Out-of-beam 160
                                                            (kHz)        Range (kHz)                   [micro]Pa rms)   Distance (m)      dB Distance
--------------------------------------------------------------------------------------------------------------------------------------------------------
Single-beam sonar...............  Simrad EA502.......          12 kHz        8-20 kHz        <10[deg]           218.0              40  40 m.
Multi-beam bathymetric sonar....  Kongsberg EM2040...         220 kHz         200-240         <2[deg]           187.4               0  0 m.
Side-scan sonar.................  GeoAcoustics 159D..             110         100-120         <2[deg]           211.5             230  NA.
Sub-bottom profiler.............  Kongsberg SBP300...             3-7             3-7         15[deg]           195.9              30  3 m.

[[Page 47498]]

 
Ultra-short baseline acoustic     SonarDyne Ranger                 27           20-30              NA           215.1              47  8 m.
 positioning system.               Pro.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    For Shell's equipment recovery and maintenance at the Burger A well 
site where drilling took place in 2012, a vessel would be deployed at 
or near the well site using dynamic positioning thrusters while 
remotely operated vehicles or divers are used to perform the required 
activities. Sounds produced by the vessel while in dynamic positioning 
mode would be non-impulsive in nature and are thus evaluated at the 
>=120 dB (rms) re 1 [mu]Pa.
    In 2011, Statoil conducted geotechnical coring operations in the 
Chukchi Sea using the vessel Fugro Synergy. Measurements were taken 
using bottom founded recorders at 50 m (164 ft), 100 m (328 ft), and 1 
km (0.6 mi) away from the borehole while the vessel was in dynamic 
positioning mode (Warner and McCrodan 2011). Sound levels measured at 
the recorder 1 km (0.6 mi) away ranged from 119 dB (rms) to 129 dB 
(rms) re 1 [mu]Pa. A propagation curve fit to the data and encompassing 
90 percent of all measured values during the period of strongest sound 
emissions estimated sound levels would drop below 120 dB (rms) re 1 
[mu]Pa at 2.3 km (1.4 mi).
    Acoustic measurements of the Nordica in dynamic positioning mode 
while supporting Shell's 2012 drilling operation in the Chukchi Sea 
were made from multiple recorders deployed to monitor sounds from the 
overall drilling operation. Distances to these recorders ranged from 
1.3 km (0.8 mi) to 7.9 km (4.9 mi) and maximum sound pressure levels 
ranged from 112.7 dB (rms) to 129.9 dB (rms) re 1 [mu]Pa. Preliminary 
analyses of these data indicate the maximum 120 dB (rms) re 1 [mu]Pa 
distance was approximately 4 km (2.5 mi) from the vessel. These same 
recorders measured sounds produced by the Tor Viking II while it 
operated near the Discoverer drill rig in 2012. The nature of the 
operations conducted by the Tor Viking II during the reported 
measurement periods varied and included activities such as anchor 
handling, circling, and possibly holding position using dynamic 
positioning thrusters. Distances to the 120 dB (rms) re 1 [mu]Pa level 
were estimated at 10 km (6 mi), 13 km (8 mi), and 25 km (15.5 mi) 
during these various measurement periods.
    The vessel from which equipment recovery and maintenance would be 
conducted has not yet been determined. Under most circumstances, sounds 
from dynamic positioning thrusters are expected to be well below 120 dB 
(rms) re 1 [mu]Pa at distances greater than 10 km (6 mi). However, 
since some of the activities conducted by the Tor Viking II at the 
Burger A well site in 2012 may have included dynamic positioning, the 
13 km (8 mi) distance has been selected as the estimated >=120 dB (rms) 
re 1 [mu]Pa distance used in the calculations of potential Level B 
harassment below. A circle with a radius of 13 km (8 mi) results in an 
estimated area of 531 km\2\ (205 mi\2\) that may be exposed to 
continuous sounds >=120 dB (rms) re 1 [mu]Pa.

Comments and Responses

    A notice of NMFS' proposal to issue an IHA to Shell was published 
in the Federal Register on May 14, 2012 (78 FR 28412). That notice 
described, in detail, Shell's proposed activity, the marine mammal 
species that may be affected by the activity, and the anticipated 
effects on marine mammals and the availability of marine mammals for 
subsistence uses. During the 30-day public comment period, NMFS 
received comment letters from the following: the Marine Mammal 
Commission (Commission); the Alaska Eskimo Whaling Commission (AEWC); 
the Alaska Wilderness League (AWL), Center for Biological Diversity, 
Earthjustice, Greenpeace, Natural Resources Defense Council, Northern 
Alaska Environmental Center, Sierra Club, and the Wilderness Society 
(collectively ``AWL''), Bureau of Ocean Energy Management (BOEM), and 
one private citizen.
    Any comments specific to Shell's application that address the 
statutory and regulatory requirements or findings NMFS must make to 
issue an IHA are addressed in this section of the Federal Register 
notice.
    MMPA Concerns:
    Comment 1: The Commission recommends that NMFS continue to include 
proposed incidental harassment authorization language at the end of 
Federal Register notices but ensure that the language is consistent 
with that referenced in the main body of the Federal Register notice.
    Response: NMFS agrees that this is a good recommendation and plans 
to include proposed incidental harassment authorization language at the 
end of Federal Register notices for Arctic oil and gas IHAs. NMFS will 
also try to ensure that the language is consistent with that referenced 
in the main body of the Federal Register notice.
    Comment 2: The Commission recommends that NMFS require Shell to 
revise its take estimates to include Level B harassment takes 
associated with its ice gouge survey. In addition, AWL states that NMFS 
has not justified its decision to remove entirely Shell's ice gouge 
surveys from the ambit of the MMPA.
    Response: NMFS does not agree with the Commission's recommendation 
and AWL's statement. As stated in the Federal Register notice for the 
proposed IHA and explained in Shell's IHA application, due to the low 
intensity and high frequency acoustic sources being used for the ice 
gouge surveys, this activity is not expected to result in takes of 
marine mammals. The acoustic equipment proposed to be used in the ice 
gouge survey includes single-beam bathymetric sonar, multi-beam 
bathymetric sonar, dual frequency side-scan sonar, and shallow sub-
bottom profiler. Representative instruments of these types were 
measured during Statoil's 2011 site survey program in the Chukchi Sea. 
Operating frequencies, beam widths, and distances to 160 dB re 1 [mu]Pa 
for these high frequency instruments are summarized in Table 2. Due to 
the rapid attenuation of these higher frequency sounds and the narrow 
beam-widths where most of the sound energy is present, the impact from 
operating these instruments is not expected to be any greater than the 
operation of the vessel itself. Therefore, NMFS does not believe use of 
these

[[Page 47499]]

instruments would cause takes of marine mammals as defined under the 
MMPA.
    Impacts Analysis:
    Comment 3: The AEWC states that it wants to emphasize the growing 
importance of the fall bowhead whale hunt for Barrow and the Chukchi 
Sea communities. The AEWC states that it is concerned about NMFS' 
statement in the Federal Register notice for the proposed IHA that the 
subsistence hunt of the bowhead whales in Chukchi Sea communities 
``takes place almost exclusively in the spring[hellip]'' The AEWC 
points out that its Chukchi Sea communities are increasingly being 
forced to look to fall hunting opportunities as ice conditions in the 
spring are making it more dangerous and difficult to meet its quotas. 
The AEWC states that this spring only 11 whales were taken: four in 
Savoonga, two in Gambell, and five in Pt. Hope. No whales were taken in 
Barrow. The AEWC asks NMFS to discuss the growing importance of the 
fall hunt for the communities.
    Response: NMFS appreciates the additional information clarifying 
the role of the fall bowhead whale hunt in subsistence harvest 
activities. NMFS' analyses provided in the Federal Register notice for 
the proposed IHA was based on historical data as the most recent data 
from the same season may not be available at the time of analysis. NMFS 
has incorporated this information into the subsistence impact analysis 
in this document.
    Comment 4: The BOEM states that there is an incorrect statement on 
page 28422 of the Federal Register notice for the proposed IHA where it 
states ``During the survey period most marine mammals are expected to 
be dispersed throughout the area, except during the peak of the bowhead 
whale migration through the Chukchi Seas, which occurs from late August 
into October.'' BOEM comments that NMFS use of the word ``peak'' is 
problematic. BOEM further states that ``the bowhead migration occurs in 
surges of groups moving from Canadian waters to the Alaskan Beaufort 
Sea beginning in August. Some bowheads are sporadically present in the 
proposed ancillary activity area from July 6 to December 25, but the 
bowhead migration begins to enter the activity area during late August, 
and more through the activity area as late November 26, per tagged 
whale data and aerial survey data. There would be few bowheads in the 
vicinity of the ancillary activities during July and August, the 
proposed period when much of the activity is proposed.''
    Response: NMFS revised the sentence to ``During the survey period 
most marine mammals are expected to be dispersed throughout the area, 
with most of the bowhead whales migration through the Chukchi Sea 
between late August and late November.''
    Comment 5: The AWL states that there are large gaps in basic 
scientific information about both the Chukchi Sea ecosystem and marine 
mammal responses to noise, and that these gaps prevent adequate 
analysis of the potential impacts of Shell's proposed seismic survey on 
wildlife. The AWL concludes that the gaps in information preclude 
defensible small numbers and negligible impact findings under the MMPA, 
constrain the designing of adequate mitigation measures, and undermine 
assessment of the potential effects of the proposed surveying pursuant 
to NEPA.
    Response: Although NMFS agrees that it would be desirable to obtain 
additional information about both the Chukchi Sea ecosystem and marine 
mammal responses to noise in general, NMFS believes it has sufficient 
information to support its analysis of the potential impacts of Shell's 
proposed marine surveys on wildlife. As required by the MMPA 
implementing regulations at 50 CFR 216.102(a), NMFS has used the best 
scientific information available in assessing the level of take and 
whether the impacts would be negligible. The Federal Register notice 
for the proposed IHA, NMFS EA for the issuance of IHAs to take marine 
mammals incidental to open-water marine and seismic surveys in 2013, 
and this document all provide detailed analysis using the best 
available scientific information that enables NMFS to make the required 
determinations. In addition, the required monitoring and mitigation 
measures prescribed in the IHA NMFS issued to Shell will further reduce 
any potential impacts of the proposed marine surveys on marine mammals.
    Comment 6: The AWL states that NMFS may not issue the IHA because 
it has not negated the possibility of serious injury from Shell's 
airguns. Further, the AWL noted that 18 years ago, NMFS once stated 
that permanent hearing loss qualifies as serious injury (60 FR 28381, 
May 31, 1995). A private citizen further states that the marine survey 
is ``massive deadly'' to marine mammals.
    Response: NMFS does not agree with the private citizen and AWL's 
assessment. In fact, NMFS was able to make a preliminary determination 
in the Federal Register for the proposed IHA to Shell to take marine 
mammals incidental to its open-water marine surveys. In addition, NMFS' 
preliminary determination states that the potential effects would be 
Level B behavioral harassment by small numbers of marine mammals in the 
project vicinity, and no injury, serious injury, or mortality is 
expected.
    Concerning the AWL's comments on NMFS 1995 proposed rule to 
implement the process to apply for and obtain an IHA, NMFS stated that 
authorizations for harassment involving the ``potential to injure'' 
would be limited to only those that may involve non-serious injury (60 
FR 28379; May 31, 1995). While the Federal Register notice cited by the 
commenters states that NMFS considered PTS to be a serious injury (60 
FR 28379; May 31, 1995), our understanding of anthropogenic sound and 
the way it impacts marine mammals has evolved since 1995, and NMFS no 
longer considers PTS to be a serious injury. NMFS has defined ``serious 
injury'' in 50 CFR 216.3 as ``...any injury that will likely result in 
mortality.'' There are no data that suggest that PTS would be likely to 
result in mortality, especially the limited degree of PTS that could 
hypothetically be incurred through exposure of marine mammals to 
seismic airguns at the level and for the duration that are likely to 
occur in this action.
    Further, as stated several times in this document and previous 
Federal Register notices for seismic activities, there is no empirical 
evidence that exposure to pulses of airgun sound can cause PTS in any 
marine mammal, even with large arrays of airguns (see Southall et al. 
2007). PTS is thought to occur several decibels above that inducing 
mild temporary threshold shift (TTS), the mildest form of hearing 
impairment (a non-injurious effect). NMFS concluded that cetaceans and 
pinnipeds should not be exposed to pulsed underwater noise at received 
levels exceeding, respectively, 180 and 190 dB re 1 [mu]Pa (rms). The 
established 180- and 190-dB re 1 [mu]Pa (rms) criteria are the received 
levels above which, in the view of a panel of bioacoustics specialists 
convened by NMFS before TTS measurements for marine mammals started to 
become available, one could not be certain that there would be no 
injurious effects, auditory or otherwise, to marine mammals. 
Additionally, NMFS has required monitoring and mitigation measures to 
negate the possibility of marine mammals being seriously injured or 
killed as a result of Shell's activities. In the proposed IHA, NMFS 
determined that Shell's activities are unlikely to even result in TTS. 
Based on this determination and the

[[Page 47500]]

explanation provided here, PTS is also not expected. Therefore, an IHA 
is appropriate.
    Comment 7: The Commission requests NMFS use species-specific 
maximum density estimates as a basis for estimating the expected number 
of takes.
    Response: To provide some allowance for the uncertainties, Shell 
calculated both ``maximum estimates'' as well as ``average estimates'' 
of the numbers of marine mammals that could potentially be affected. 
For a few marine mammal species, several density estimates were 
available, and in those cases the mean and maximum estimates were 
determined from the survey data. In other cases, no applicable estimate 
(or perhaps a single estimate) was available, so adjustments were used 
to arrive at ``average'' and ``maximum'' estimates. The species-
specific estimation of these numbers is provided in the Federal 
Register notice for the proposed IHA. NMFS has determined that the 
average density data of marine mammal populations will be used to 
calculate estimated take numbers because these numbers are based on 
surveys and monitoring of marine mammals in the vicinity of the 
proposed project area. For several species whose average densities are 
too low to yield a take number due to extra-limital distribution in the 
vicinity of the proposed Chukchi Sea survey area, but whose chance 
occurrence has been documented in the past, such as killer whales, 
narwhales, and harbor porpoises, NMFS allotted a few numbers of these 
species to allow unexpected takes of these species.
    Comment 8: The Commission requests NMFS require Shell to (1) 
estimate the numbers of marine mammals taken in the ice gouge survey 
and (2) base that estimate on the 120-dB re 1 [micro]Pa threshold 
rather than the 160-dB re 1 [micro]Pa threshold. For the second part of 
this comment, the Commission attached its comments to NMFS regarding 
NMFS Southwest Fisheries Science Center (SWFSC) fisheries research 
activities and outlined reasons that acoustic sources used in ice gouge 
surveys have temporal and spectral characteristics that suggest a lower 
threshold would be more precautionary.
    Response: For the Commission's first comment regarding potential 
take of marine mammals in ice gouge survey, please refer to Response to 
Comment 2. As stated in that Response, NMFS does not believe that 
marine mammals would be taken as a result of the ice gouge survey.
    Regarding the Commission's second comment, NMFS does not agree with 
the Commission's statement that acoustic sources used in ice gouge 
surveys have temporal and spectral characteristics that suggest a lower 
threshold is appropriate. Continuous sounds are those whose sound 
pressure level remains above that of the ambient sound, with negligibly 
small fluctuations in level (NIOSH, 1998; ANSI, 2005), while 
intermittent sounds are defined as sounds with interrupted levels of 
low or no sound (NIOSH, 1998). Thus, echosounder signals are not 
continuous sounds but rather intermittent sounds. Intermittent sounds 
can further be defined as either impulsive or non-impulsive. Impulsive 
sounds have been defined as sounds which are typically transient, brief 
(< 1 sec), broadband, and consist of a high peak pressure with rapid 
rise time and rapid decay (ANSI, 1986; NIOSH, 1998). Echosounder 
signals also have durations that are typically very brief (< 1 sec), 
with temporal characteristics that more closely resemble those of 
impulsive sounds than non-impulsive sounds, which typically have more 
gradual rise times and longer decays (ANSI, 1995; NIOSH, 1998). With 
regard to behavioral thresholds, we therefore consider the temporal and 
spectral characteristics of echosounder signals to more closely 
resemble those of an impulse sound than a continuous sound.
    The Commission suggests that, for certain sources considered here, 
the interval between pulses would not be discernible to the animal, 
thus rendering them effectively continuous. However, an echosounder's 
``rapid staccato'' of pulse trains is emitted in a similar fashion as 
odontocete echolocation click trains. Research indicates that marine 
mammals, in general, have extremely fine auditory temporal resolution 
and can detect each signal separately (e.g., Au et al., 1988; Dolphin 
et al., 1995; Supin and Popov, 1995; Mooney et al., 2009), especially 
for species with echolocation capabilities. Therefore, it is highly 
unlikely that marine mammals would perceive echosounder signals as 
being continuous.
    In conclusion, echosounder signals are intermittent rather than 
continuous signals, and the fine temporal resolution of the marine 
mammal auditory system allows them to perceive these sounds as such. 
Further, the physical characteristics of these signals indicate a 
greater similarity to the way that intermittent, impulsive sounds are 
received. Therefore, the 160-dB threshold (typically associated with 
impulsive sources) is more appropriate than the 120-dB threshold 
(typically associated with continuous sources) for estimating takes by 
behavioral harassment incidental to use of such sources.
    Finally, we agree with the Commission's recommendation to revise 
existing acoustic criteria and thresholds as necessary to specify 
threshold levels that would be more appropriate for a wider range of 
sound sources, and are currently in the process of producing such 
revisions. In particular, NMFS recognizes the importance of context 
(e.g., behavioral state of the animals, distance) in behavioral 
responses. The current behavioral categorization (i.e., impulse vs. 
continuous) does not account for context and is not appropriate for all 
sound sources. Thus, updated NOAA Acoustic Guidance (http://www.nmfs.noaa.gov/pr/acoustics/guidelines.htm) will more appropriately 
categorize behavioral harassment criteria by activity type.
    Comment 9: The Commission requests NMFS consult with experts in the 
field of sound propagation and marine mammal hearing to revise the 
acoustic criteria and thresholds as necessary to specify threshold 
levels that would be more appropriate for a wider range of sound 
sources, including shallow penetration subbottom profilers, 
echosounders, and side-scan sonar.
    Response: NMFS is in the process of developing revised acoustic 
criteria and thresholds to for a variety of sources. The revised 
acoustic criteria will be peer-reviewed and made available for public 
comment. Until that process is complete, it is not appropriate to apply 
the new criteria and thresholds in any incidental take authorization. 
Instead, NMFS will continue its longstanding practice of considering 
specific modifications to the acoustic criteria and thresholds 
currently employed for incidental take authorizations only after 
providing the public with an opportunity for review and comment and 
responding to the comments.
    Comment 10: The Commission requests NMFS require Shell to calculate 
the size of the Level A and B harassment zones for the ice gouge 
survey, using the 120-dB re 1 [micro]Pa isopleth for the shallow 
penetration sub-bottom profiler as the basis for determining the 
distance to the Level B disturbance zone.
    Response: As noted in the Federal Register notice for the proposed 
IHA, a level A harassment zone for the ice gouge survey either does not 
exist or is expected to be in close proximity of the survey vessel. The 
sizes of the Level B harassment zones (received level at 160 dB re 1 
[micro]Pa) for the ice gouge survey for various sources are listed in 
Table 2 of the Federal Register notice for the proposed IHA as well as 
in this

[[Page 47501]]

document. NMFS does not agree with the Commission that it is 
appropriate to use the 120-dB re 1 [micro]Pa isopleth for the shallow 
penetration sub-bottom profiler (as well as other acoustic equipment 
used in the ice gouge survey) as the basis for determining the distance 
to the Level B disturbance zone, with reasons given in Response to 
Comment 8 above.
    Comment 11: The AWL claims that NMFS underestimated the number of 
animals that would be harassed from Shell's surveying because it 
calculates harassment from Shell's proposed surveying based on the 
exposure of marine mammals to impulsive sounds at or above 160 dB. The 
AWL states that this uniform approach to harassment does not take into 
account known reactions of marine mammals in the Arctic to levels of 
noise well below 160 dB. Without citing specific research, the AWL 
claims that ``for harbor porpoises, behavioral changes, including 
exclusion from an area, can occur at received levels from 90-110 dB 
[near ambient level] or lower,'' and beluga whales ``are known to alter 
their migration paths in response to ice breaker noise at received 
levels as low as 80 dB [quiet ambient level].'' The AWL further 
appointed out that NMFS acknowledged the potential for behavioral 
disturbance to belugas at distances of 10-20 km and bowhead whales 
react to sound level lower than 160 dB.
    Response: NMFS does not agree with AWL's assessment on acoustic 
effects of marine mammals. First, the AWL did not provide a reference 
on harbor porpoise behavioral responses and exclusion from an area to 
received levels at 90-110 dB or lower, which is near the ambient noise 
level. Second, for the beluga whale example at quiet ambient level, 
although also not supported by a reference, such a deviation could be 
attributed to noise exposure to continuous sound (icebreaker), rather 
than exposure to seismic impulses. Additionally, as Shell does not 
intend to use icebreakers during its operations, statements regarding 
beluga reactions to icebreaker noise are not relevant to this activity. 
Concerning the behavioral disturbance by belugas at distances of 10-20 
km, there was no mention of received level, so it is irrelevant to the 
AWL's argument concerning 160 dB received noise levels.
    Although some studies have shown bowhead responses to received 
seismic impulses under 160 dB re 1 [micro]Pa, the best information 
available to date results from the 1998 aerial survey (as supplemented 
by data from earlier years) as reported in Miller et al. (1999). In 
1998, bowhead whales below the water surface at a distance of 20 km 
(12.4 mi) from an airgun array received pulses of about 117-135 dB re 1 
[mu]Pa rms, depending upon propagation. Corresponding levels at 30 km 
(18.6 mi) were about 107-126 dB re 1 [micro]Pa rms. Miller et al. 
(1999) surmise that deflection may have begun about 35 km (21.7 mi) to 
the east of the seismic operations, but did not provide SPL 
measurements to that distance and noted that sound propagation has not 
been studied as extensively eastward in the alongshore direction, as it 
has northward, in the offshore direction. Therefore, while this single 
year of data analysis indicates that bowhead whales may make minor 
deflections in swimming direction at a distance of 30-35 km (18.6-21.7 
mi), there is no indication that the SPL where deflection first begins 
is at 120 dB; it could be at another SPL lower or higher than 120 dB. 
Miller et al. (1999) also note that the received levels at 20-30 km 
(12.4-18.6 mi) were considerably lower in 1998 than have previously 
been shown to elicit avoidance in bowheads exposed to seismic pulses. 
However, the seismic airgun array used in 1998 was larger than the ones 
used in 1996 and 1997. Therefore, NMFS believes that it cannot 
scientifically support adopting any single SPL value below 160 dB and 
apply it across the board for all species and in all circumstances. 
Second, as stated in the past, NMFS does not believe that minor course 
corrections during a migration will always equate to ``take'' under the 
MMPA. This conclusion is based on controlled exposure experiments 
conducted on migrating gray whales exposed to the U.S. Navy's low 
frequency sonar (LFA) sources (Tyack 2009). When the source was placed 
in the middle of the migratory corridor, the whales were observed 
deflecting around the source during their migration. However, such 
minor deflection is considered not to be biologically significant. To 
show the contextual nature of this minor behavioral modification, 
recent monitoring studies of Canadian seismic operations indicate that 
when, not migrating, but involved in feeding, bowhead whales do not 
move away from a noise source at an SPL of 160 dB. Therefore, while 
bowheads may avoid an area of 20 km (12.4 mi) around a noise source, 
when that determination requires a post-survey computer analysis to 
find that bowheads have made a 1 or 2 degree course change, NMFS 
believes that does not rise to a level of a ``take.'' NMFS therefore 
continues to estimate ``takings'' under the MMPA from impulse noises, 
such as seismic, as being at a distance of 160 dB (re 1 [micro]Pa). 
Although it is possible that marine mammals could react to any sound 
levels detectable above the ambient noise level within the animals' 
respective frequency response range, this does not mean that such 
animals would react in a biologically significant way. According to 
experts on marine mammal behavior, the degree of reaction which 
constitutes a ``take,'' i.e., a reaction deemed to be potentially 
biologically significant or that could potentially disrupt the 
migration, breathing, nursing, breeding, feeding, or sheltering, etc., 
of a marine mammal is complex and context specific, and it depends on 
several variables in addition to the received level of the sound by the 
animals. These additional variables include, but are not limited to, 
other source characteristics (such as frequency range, duty cycle, 
continuous vs. impulse vs. intermittent sounds, duration, moving vs. 
stationary sources, etc.); specific species, populations, and/or 
stocks; prior experience of the animals (naive vs. previously exposed); 
habituation or sensitization of the sound by the animals; and behavior 
context (whether the animal perceives the sound as predatory or simply 
annoyance), etc. (Southall et al. 2007).
    Currently NMFS is working on revising its noise exposure criteria 
based on the best and most recent scientific information. These 
criteria will be used to develop methodologies to calculate behavioral 
responses of marine mammals exposed to sound associated with seismic 
surveys (primary source is airguns). Nevertheless, at the current stage 
and until the updated criteria are available (i.e., undergone full 
evaluation including internal review, peer review, and public comment), 
NMFS will continue to use the 160-dB threshold for determining the 
level of take of marine mammals by Level B harassment for impulse noise 
(such as from airguns).
    Comment 12: The AWL states that NMFS should examine more closely 
the effects of noise from dynamic positioning. The AWL states that 
considering that the vessel that would be conducting the operations has 
not yet been identified, NMFS must follow the precautionary principle 
and base take estimates on the 25 km 120-dB distance.
    Response: NMFS provided a detailed analysis and evaluation on the 
potential effects of noise from dynamic positioning on the marine 
environment in the Federal Register notice for the proposed IHA and EA, 
as well as in this document. As stated in the analysis, several choices 
for acoustic modeling of dynamic positioning are available based on 
prior measurements of vessels

[[Page 47502]]

conducting such activities. The loudest noise source seemed to be the 
Tor Viking II during Shell's 2012 drilling operations in the Chukchi 
Sea; the 120 dB re 1 [micro]Pa received levels from the Tor Viking were 
measured at 10 km (6 mi), 13 km (8 mi), and 25 km (15.5 mi) during 
these various measurement periods. Nevertheless, various activities 
other than the dynamic positioning operation were being performed at 
the time measurements were conducted, such as anchor handling and 
cycling. Therefore, NMFS does not consider that the largest radius 
represents the most accurate Level B harassment zone since for Shell's 
proposed 2013 marine surveys, the supporting vessel during equipment 
recovery and maintenance activities would only be engaged in dynamic 
position while supporting diving operations. Therefore, radius of 13 km 
(8 mi) was chosen as the zone for Level B behavioral harassment prior 
to SSV tests being conducted.
    Comment 13: AWL argues that the effects of ice gouge surveying 
should be considered. AWL states that NMFS' dismissal of potential 
effects based on marine mammal hearing is not adequately supported. 
Citing a comment letter by David E. Bain submitted to NMFS in 2010, the 
AWL argues that NMFS' approach fails to take into consideration the 
fact that (1) juvenile whales, based on their smaller size, likely hear 
sounds of higher frequencies than adults of the same species; (2) that 
sound sources contain frequencies beyond the ``normal'' frequency in 
the form of undertones, overtones, distortion, or noise; (3) NMFS 
failed to consider the ``beat frequency'', that when a source 
simultaneously emits sound of more than one frequency, it will also 
emit energy at the difference between the two frequencies; (4) NMFS 
fails to take into account the fact that information about hearing 
abilities of bowhead whales is based on estimates since bowheads have 
not been the subject of direct testing and there is inherent 
uncertainty in these estimates; and (5) the Federal Register notice 
does not address the fact that toothed whales are sensitive to high-
frequency sounds including those over 100 kHz.
    Response: NMFS considered the potential effects of Shell's proposed 
ice gouge surveys in the Chukchi Sea in its Federal Register for the 
proposed IHA. As stated in the notice as well as the EA, the reason 
NMFS does not think take of marine mammals is likely from ice gouge 
surveys is because the active acoustic devices being used in these 
surveys are either in the frequency range above 180 kHz, which is 
beyond marine mammals functional hearing range, or with low source 
levels. In addition, due to their high-frequency nature, there is much 
absorption during sound propagation, which weakens much of the acoustic 
intensity within a relatively short range. NMFS has addressed Dr. 
Bain's comment letter concerning his above five points in the Federal 
Register for the issuance of an IHA to Shell in 2010 (75 FR 49710; 
August 13, 2010), and the following is the summary.
    Although it is possible that juvenile animals could have better 
hearing at high-frequency ranges similar to humans, the overall 
sensitivity that defines hearing is believed to be more related to 
different hearing groups (see Southall et al. 2007) than to animals' 
age groups. Therefore, it is incorrect to assume that juvenile whales 
hear sounds of higher frequencies because of their small size, 
regardless of species and functional hearing groups. In addition, the 
reason that juvenile animals (including humans) have slightly better 
high-frequency hearing is related to age rather than size (the 
principle behind it is a biological phenomenon called presbycusis, or 
aging ear).
    Regarding point (2) concerning ``normal'' frequency, which was not 
defined in the comment, NMFS assumes that Dr. Bain refers to the 
frequenc(ies) outside the manufactures' specifications for their 
acoustic devices. Although these outlier noises could be a concern for 
high-frequency acoustic sources, especially if the frequencies are 
within the sensitive hearing range of marine mammals, NMFS does not 
believe these noises have high acoustic intensities in most cases. 
Nevertheless, NMFS requested that Shell have these acoustic devices 
measured at the SSV tests. The SSV reports from Shell's 2010 90-day 
monitoring report provided a detailed description of the acoustic 
characteristics of the acoustic devices used in ice gouge surveys, and 
none of the equipment has significant sidebands that could affect 
marine mammals. Please refer to Shell's 2010 90-day monitoring report 
for detailed descriptions of the acoustic equipment used in ice gouge 
surveys (Reiser et al. 2011).
    In regards to point (3), in order to produce ``beat frequency,'' 
not only do the two sources have to be very close to each other, they 
also have to be perfectly synchronized. In the case of Shell's high-
frequency sonar, these two interfering frequencies will need to be 
produced by one device to use the non-linearity of water to 
purposefully generate the different frequency between two high 
frequencies. Even so, it is a very inefficient way to generate the beat 
frequency, with only a low percentage of the original intensity with 
very narrow beamwidth. Therefore, NMFS does not consider this to be an 
issue of concern.
    NMFS is aware that no direct measurements of hearing exist for 
bowhead and other baleen whales, and theories regarding their sensory 
capabilities are consequently speculative (for a detailed assessment by 
species using the limited available information, see Erbe 2002). In 
these species, hearing sensitivity has been estimated from behavioral 
responses (or lack thereof) to sounds at various frequencies, 
vocalization frequencies they use most, body size, ambient noise levels 
at the frequencies they use most, and cochlear morphometry and 
anatomical modeling (Richardson et al. 1995; Wartzok and Ketten 1999; 
Houser et al. 2001; Erbe 2002; Clark and Ellison 2004; Ketten et al. 
2007). Though detailed information is lacking on the species level, the 
combined information strongly suggests that mysticetes are likely most 
sensitive to sound from perhaps tens of Hz to ~10 kHz (Southall et al. 
2007). Although hearing ranges for toothed whales (mid- and high-
frequency cetaceans) fall between 100s Hz to over 100 kHz, their most 
sensitive frequency lies between 10 to 90 kHz, and sensitivity falls 
sharply above 100 kHz.
    Mitigation:
    Comment 14: AEWC requested that NMFS incorporate the following 
provisions of the 2013 CAA as binding mitigation measures in the IHA 
issued to Shell: Section 202(a) and (c): Com-Center General 
Communications Scheme; Section 204: Standardized Log Books; Section 
302: Barge and Transit Vessel Operations; Section 402: Sound Signature 
Tests; Section 501: General provisions for Avoiding Interference with 
Bowhead Whales or Subsistence Whale Hunting Activities; Section 502(b): 
Limitations on Geophysical Activity in the Chukchi Sea; Section 505: 
Termination of Operations and Transit Through the Bering Strait; and 
Title VI, Sections 601 and 602: Late Season Seismic Operations.
    Response: NMFS has incorporated the above provisions of the 2013 
CAA into the IHA issued to Shell, as these measures will help ensure 
there is no unmitigable adverse impact on the availability of affected 
species or stock(s) for subsistence uses.
    Comment 15: The Commission requests NMFS require Shell to not 
initiate or continue seismic activities if (1) an aggregation of 
bowhead whales or gray whales (12 or more whales of any age/sex class 
that appear to be engaged

[[Page 47503]]

in a non-migratory, significant biological behavior (e.g., feeding, 
socializing)) is observed within the 160-dB re 1 [micro]Pa zone or (2) 
a female-calf pair is observed within the 120-dB re 1 [micro]Pa zone.
    Response: NMFS did not propose the suspension of seismic activities 
for an aggregation of bowhead whales or gray whales (12 or more whales 
of any age/sex class) within the Level B harassment zone of 160 dB 
because the size of the zone is very small (1,800 m radius), and it is 
not likely an aggregation of 12 whales could occur in such a small 
zone. In addition, given the seismic vessel would be moving at a speed 
of 4--5 knots, and assuming the whales would be relatively stationary, 
the exposure of such aggregation of whales to received levels above 160 
dB re 1 [micro]Pa would be less than 13 minutes. Nevertheless, NMFS has 
worked with Shell to include in the IHA the Commission's recommendation 
that Shell not initiate or continue seismic activities if an 
aggregation of bowhead or gray whales (12 or more whales of any age/sex 
class that appear to be engaged in a non-migratory, significant 
biological behavior) is observed within the 160-dB re 1 [micro]Pa 
isopleth.
    However, NMFS does not agree with the Commission's recommendation 
that suspension of seismic activities is warranted for a female-calf 
pair within the 120-dB re 1 [micro]Pa zone when the animals are not 
likely to be harassed. Although it has been suggested that female 
baleen whales with calves ``show a heightened response to noise and 
disturbance,'' there is no evidence that such ``heightened response'' 
is biologically significant orconstitutes a ``take'' under the MMPA. 
Additionally, in the Chukchi Sea, the migratory corridor for bowhead 
whales is wider and more open, thus the 120-dB ensonified zone would be 
unlikely to impede bowhead whale migration. The animals would be able 
to swim around the ensonified area.
    Comment 16: The AWL states NMFS should include provisions in the 
IHA that restrict Shell's operations based on geographic location, and/
or time of year, such as restrict activity in certain areas, including 
subsistence use areas, areas of high productivity or diversity; areas 
that are important for feeding, migration, or other parts of the life 
history of species; or areas of biogenic habitat, structure-forming 
habitat, or habitat for endangered or threatened species.
    Response: While processing the proposed IHA, NMFS has worked with 
Shell and conducted extensive analysis on the areas where Shell's 
proposed open-water marine surveys would occur. The areas Shell 
proposed to have its proposed marine surveys are analyzed in the 
proposed IHA process, during the section 7 consultation under the ESA, 
as well as under the NEPA analysis for preparing the EA. However, NMFS 
did not find that further restriction is needed given that no areas of 
high productivity or diversity, areas that are important for feeding 
and migration, or critical habitat for endangered or threatened species 
were found. Nevertheless, time and area certain restrictions are 
included in the IHA to minimize potential impacts on subsistence 
activities which are consistent with the CAA Shell has signed. These 
time and area restrictions are:
     Vessels transitting east of Bullen Point to the Canadian 
border should remain at least five miles offshore during transit along 
the coast, provided ice and sea condition allow,
     Vessels should remain as far offshore as weather and ice 
conditions allow, and at least five miles offshore during transit,
     From August 31 to October 31 vessels in the Chukchi Sea or 
Beaufort Sea shall remain at least 20 miles offshore of the coast of 
Alaska from Icy Cape in the Chukchi Sea to Pitt Point on the east side 
of Smith Bay in the Beaufort Sea whether in transit or engaging in 
activities in support of oil and gas operations unless ice conditions 
or an emergency that threatens the safety of the vessel or crew 
prevents compliance with this requirement,
     Beginning September 15, and ending with the close of the 
fall bowhead whale hunt, if Wainwright, Pt. Lay, or Pt. Hope intend to 
whale in the Chukchi Sea, no more than two geophysical activities 
employing geophysical equipment will occur at any one time in the 
Chukchi Sea. During the fall bowhead whale hunt, geophysical equipment 
will not be used within 30 miles of any point along the Chukchi Sea 
coastline. Industry participants will contact the Whaling Captains' 
Associations of each villages to determine if a village is prepared to 
whale and will notify the AEWC of any response, and
     All Industry participant vessels shall complete operations 
in time to allow such vessels to complete transit through the Bering 
Strait to a point south of 59 degrees North latitude no later than 
November 15, 2013.
    Comment 17: The AWL states that NMFS should examine imposing 
requirements for the use of new technology that could reduce the 
footprint of seismic exploration. The AWL cited an expert conference in 
February in Silver Spring, Maryland, by NMFS on alternative 
technologies for offshore energy production and requested that NMFS 
consider (1) mandating the use of marine vibroseis or other 
technologies in some or all of the survey area; (2) mandating the 
testing of marine vibroseis in a pilot area, precedent to a decision to 
permit seismic activity, with an obligation to accrue data on 
environmental impacts; (3) deferring the permitting of surveys in part 
or all of the survey area until effective mitigative technologies, such 
as marine vibroseis, become available; (4) providing incentives for 
Shell's use of these technologies as was done for passive acoustic 
monitoring systems; and (5) exacting funds from Shell to support 
accelerated mitigation research in this area.
    Response: First, the February workshop (not an ``expert 
conference'') in Silver Spring, Maryland, titled Quieting Technologies 
for Reducing Noise during Seismic Surveying and Pile Driving, was 
convened by BOEM, not NMFS. The goals of the workshop, as stated in the 
Web site of the workshop, were to (1) review and examine recent 
developments (existing, emerging, and potential) in quieting 
technologies for seismic surveying, whether proposed or in development; 
(2) identify the requirements for operation and limitations for using 
these technologies; (3) evaluate data quality and cost-effectiveness of 
these technologies as compared to that from existing marine acoustic 
technologies; (4) identify the acoustic characteristics of new 
technologies in varying environments compared to that from existing 
technologies; (5) examine potential environmental impacts from these 
technologies; (6) identify which technologies, if any, provide the most 
promise for full or partial traditional use and specify the conditions 
that might warrant their use (e.g., specific limitations to water 
depth, use in Marine Protected Areas, etc.); and (7) identify next 
steps, if appropriate, for the further development of these 
technologies, including potential incentives for field testing. Most of 
these technologies are still in research and development stages and 
have not been field tested. The workshop provided a forum for 
discussion and evaluation of such technologies, including vibroseis. 
NMFS supports and encourages both the development and use of 
technologies that will reduce impacts to marine mammals and other 
marine species. These alternative technologies will likely be adopted 
for use to replace some subset of future seismic survey

[[Page 47504]]

activities once their development is further along and their 
environmental impacts, especially as compared to seismic airguns, are 
better understood. . However, NMFS does not believe it can currently 
mandate the use of such technologies.
    Monitoring:
    Comment 18: The Commission requests NMFS require Shell to conduct 
sound source verification (SSV) for the ice gouge survey at varying 
depths. The Commission reasons that it is particularly important for 
the ice gouge survey because it would be conducted in relatively 
shallow nearshore waters where propagation models are of limited 
utility and bottom topography is more influential in these cases.
    Response: NMFS does not agree with the Commission's assessment that 
propagation models are of limited utility in areas of relatively 
shallow waters where ice gouge surveys are proposed. Nevertheless, SSV 
tests will be performed to confirm the modeled sound propagation 
provided in the Federal Register notice for the proposed IHA. However, 
since the difference of water depth in the proposed ice gouge survey 
area is relatively small (between 12 and 42 m), NMFS does not believe 
SSV at varying water depth increments is necessary to yield meaningful 
differences in propagation distances.
    Comment 19: The Commission requests NMFS only authorize an in-
season adjustment in the size of the exclusion and/or disturbance zones 
if the size(s) of the estimated zones are determined to be inadequate. 
The Commission states that the purpose of SSV is to ensure protection 
of marine mammals, and one way to reduce risk to marine mammals would 
be to only allow expansion of the exclusion and/or disturbance zones.
    Response: NMFS does not agree with the Commission's recommendation. 
While may seem to be more protective to increase the exclusion zone if 
the effectiveness of visual-based marine mammal monitoring remains the 
same regardless of the size of the zone, the actual result may not be 
so. For example, when the SSV suggests that the exclusion and/or 
disturbance zones are smaller than the ones modeled and monitoring 
still focus on the larger modeled zones, it is likely that the 
effectiveness of marine mammal monitoring could be reduced as the area 
to be monitored would be larger than necessary. In addition, larger 
than realistic exclusion zones would cause unnecessary power-down and 
shutdowns, which could increase the total duration of the marine 
surveys, and causes unnecessary impacts to the marine environment.
    Comment 20: The Commission requests NMFS require Shell to deploy a 
sufficient number of trained and experienced, NMFS-approved vessel-
based observers on the ice gouge survey vessel to ensure adequate 
monitoring of the Level A and B harassment zones during daylight hours 
throughout the entire survey period.
    Response: As stated in the Federal Register notice for the proposed 
IHA, the level A harassment zone for the ice gouge survey either does 
not exist or is expected in close proximity of the survey vessel. 
Nevertheless, Shell is required to deploy a sufficient number of 
trained and experienced, NMFS-approved vessel-based protected species 
observers (PSOs) on the ice gouge survey vessel to ensure adequate 
monitoring of marine mammals during daylight hours throughout the 
entire survey period.
    Comment 21: The Commission requests NMFS require Shell to monitor 
for marine mammals 30 minutes before, during, and 30 minutes after 
survey operations and other activities have ceased.
    Response: Shell is required to monitor for marine mammals 30 
minutes before, during, and 30 minutes after survey operations and 
other activities have ceased.
    Comment 22: The Commission requests NMFS encourage Shell to deploy 
additional protected species observers to (1) increase the probability 
of detecting all marine mammals in or approaching the Level A and B 
harassment zones and (2) assist in the collection of data on 
activities, behaviors, and movements of marine mammals around the 
source.
    Response: NMFS agrees that an adequate number of PSOs is critical 
to ensure complete coverage in visual monitoring and implementing 
mitigation measures. While it is reasonable to conclude that additional 
PSOs would increase detection capability to a certain degree, the 
number of PSOs that can be stationed on vessels is limited by the 
available berth spaces. Shell plans to have 4 to 5 PSOs aboard the 
survey vessel and will have 100% monitoring coverage during all periods 
of survey operations in daylight. In addition, each PSO is limited to 
maximum of 4 consecutive hours per watch and maximum of 12 hours of 
watch time per day. NMFS believes that the number of PSOs onboard is 
adequate given the limited space available on the survey vessel.
    Comment 23: The Commission requests NMFS require Shell to report 
the preliminary results of its in-situ sound source and sound 
propagation measurements within five days.
    Response: NMFS requires Shell to report the preliminary results of 
the in-situ SSV tests within five days of completing the tests, 
followed by a report in 14 days. This will allow Shell to review the 
initial results and to catch any error that might be overlooked during 
the initial five-day reporting.
    Comment 24: The AWL states that the proposed IHA's mitigation 
measures rely on visual monitoring of exclusion zones to keep marine 
mammals from encountering potentially injurious levels of noise. Citing 
the example of ION Geophysical's 90-day monitoring report, the AWL 
points out the difficulty of monitoring these zones at distances 
greater than 2.2 miles. The AWL further states that the Open-water peer 
review panel reviewing Shell's proposed activities also noted serious 
limitations of visual monitoring, and quoting that ``the ability to 
sight animals declines with distance, and disturbance of animals beyond 
sighting distance may go undetected,'' and ``observations become less 
efficient to the point of being completely ineffective as sighting 
conditions deteriorate (e.g., nighttime, high sea state, precipitation 
or fog.'' The AWL further quotes ION's 90-day report as saying ``nights 
with fog, no ambient light, or heavy seas made observations nearly 
impossible.''
    Response: NMFS recognizes the limitations of visual monitoring as 
distance increases. However, Shell's proposed open-water marine survey 
would employ a small airgun array of 40 in\3\, and the modeled 180- and 
190-dB exclusion zones are expected to be at 160 and 50 m from the 
source, respectively. Therefore, NMFS believes that at these short 
distances, vessel-based visual monitoring is effective. In fact, to 
address AWL's concern regarding the proposed mitigation measures 
depending on visual monitoring of the exclusion zone, the peer-review 
panel provided detailed analysis in its final report regarding Shell's 
use of vessel-based protected species observation as the primary 
monitoring element for the proposed marine surveys. The panel states 
that it ``sees this as appropriate, given the composition of the 
operations and expected spatial scale of influence, and finds the above 
objectives [ensuring disturbance to marine mammals and subsistence 
hunts is minimized and all permit stipulations are followed, 
documenting the effects of the proposed survey activities on marine 
mammals, and collecting baseline data on the occurrence and 
distribution of marine

[[Page 47505]]

mammals in the study area] as largely appropriate and achievable.''
    In addition, NMFS recognizes the limitations of visual monitoring 
in darkness and other inclement weather conditions. Therefore, in the 
IHA to Shell, NMFS requires that no seismic airgun can be ramped up 
when the entire exclusion zones are not visible. However, Shell's 
operations will occur in an area where periods of darkness do not begin 
until early September. Beginning in early September, there will be 
approximately 1-3 hours of darkness each day, with periods of darkness 
increasing by about 30 min each day. By the end of the survey period, 
there will be approximately 8 hours of darkness each day. These 
conditions provide MMOs favorable monitoring conditions for most of the 
time.
    Comment 25: Citing ION's error in its initial exclusion zone 
measurements, the AWL states that sound measurements used to estimate 
the size of safety radii from which animals should be excluded can 
easily be miscalculated.
    Response: Although NMFS recognizes the error made by ION's 
contractor during the sound source verification measurement and the 
radius of the 180-dB exclusion was estimated less than it would be, 
NMFS does not agree with AWL's speculation that sound measurements used 
to estimate the size of exclusion zones can be ``easily 
miscalculated.'' The ION incident was not due to miscalculation. It was 
due to an human error in data handling and is preventable. NMFS has 
subsequently discussed this with ION and its contractor to make sure 
that rigorous checks and verification are performed to ensure no error 
in data handling.
    Subsistence Issues:
    Comment 26: The Commission recommends that NMFS encourage the 
development of a Conflict Avoidance Agreement (CAA) for Shell's 
proposed activities that involves all potentially affected communities 
and co-management organizations and that accounts for potential adverse 
impacts on all marine mammal species taken for subsistence purposes 
including, but not limited to, bowhead whales.
    Response: As stated in the Federal Register notice for the proposed 
IHA, NMFS encouraged Shell to negotiate and sign a CAA to ensure that 
its proposed activities would not have unmitigable impacts to 
subsistence use of marine mammal in the proposed action area. Shell has 
signed the 2013 CAA, and is commended by the AEWC for engaging with 
AEWC in the negotiations and committing to ongoing work with the local 
community to ensure the protection of the subsistence traditions.
    Comment 27: The AEWC expresses its concerns that Shell's Plan of 
Cooperation (POC) was not completed before NMFS made a preliminary 
determination in the Federal Register for the proposed IHA. The AEWC 
recommends that in the future the POC should be completed and submitted 
to NMFS along with the IHA application or that NMFS adopt and 
incorporate the signed CAA.
    Response: Regulations at 50 CFR 216.104(a)(12) require applicants 
for IHAs in Arctic waters to submit a Plan of Cooperation (POC), which, 
among other things, requires the applicant to meet with affected 
subsistence communities to discuss the proposed activities. NMFS 
received a draft POC at the time from Shell while analyzing its 
proposed marine survey activities. However, Shell subsequently revised 
its proposed survey and limited its activities to only the Chukchi Sea, 
as opposed to both the Beaufort and Chukchi Seas as previously planned. 
Additional meetings were planned by Shell and the native communities to 
clarifying the project modification, which delayed the completion of 
the POC. Nevertheless, NMFS believes that it had adequate information 
from the draft POC to conduct the analyses and make a preliminary 
determination. Should a significant issue develop after the publication 
of the Federal Register notice for the proposed IHA, the final IHA 
would not be issued until such issues are resolved. NMFS received the 
final POC from Shell on June 17, 2013, describing in details the 
stakeholder meetings and the outcomes.
    NEPA Concern:
    Comment 28: AWL states that NMFS should not proceed with 
authorizations for individual projects like Shell's surveying until its 
programmatic EIS is complete. AWL supports its statement by quoting 
C.F.R. 1506.1(c): ``While work on a required program environmental 
impact statement is in progress and the action is not covered by an 
existing program statement, agencies shall not undertake in the interim 
any major Federal action covered by the program which may significantly 
affect the quality of the human environment.''
    Response: NMFS does not agree with the AWL statement. The AWL 
misunderstood the C.F.R. language, where it clearly states that 
``agencies shall not undertake in the interim any major Federal actions 
covered by the program which may significantly affect the quality of 
the human environment,'' in which case a FONSI could not be issued. In 
regard to the Shell's proposed open-water marine surveys, NMFS has 
prepared an EA and issued a FONSI.
    While the analysis contained in the Final EIS will apply more 
broadly to Arctic oil and gas operations, NMFS' issuance of an IHA to 
Shell for the taking of several species of marine mammals incidental to 
conducting its open-water marine survey in the Chukchi Sea in 2013, as 
analyzed in the EA, is not expected to significantly affect the quality 
of the human environment. Shell's surveys are not expected to 
significantly affect the quality of the human environment because of 
the limited duration and scope of operations.
    Comment 29: The AWL states that NMFS must conduct a site-specific 
NEPA analysis of this action that considers meaningful alternatives. In 
preparing an EIS, agencies must ``rigorously explore and objectively 
evaluate all reasonable alternatives'' to the proposed action. Agencies 
must identify and assess those alternatives that would ``avoid or 
minimize adverse effects of [proposed] actions upon the quality of the 
human environment.'' The AWL further states that the discussion of 
alternatives ``is the heart of the [EIS],'' and the ``consideration of 
alternatives is critical to the goals of NEPA'' even where a proposed 
action does not trigger the EIS process. The AWL further states that 
meaningful alternatives would include a true no-action alternative that 
reflects that Shell cannot legally proceed in the absence of take 
authorization, and that NMFS should also consider alternatives that 
require the mitigation measures of time and/or area closures and the 
use of new technologies that may address some of the deficiencies in 
visual monitoring, and the alternatives to using the 160-dB threshold 
for impulse noise.
    Response: NMFS prepared an EA that includes an analysis of 
potential environmental effects associated with NMFS' issuance of an 
IHA to Shell to take marine mammals incidental to conducting its marine 
surveys in the Chukchi Sea during the 2013 open-water season. The EA 
contains detailed evaluation of all reasonable alternatives to the 
proposed action. The alternatives include a no-action alternative which 
assumes Shell, TGS, and SAE will not proceed with open-water marine and 
seismic surveys if take authorizations were not issued, and an 
additional alternative that call for the use of active acoustic 
monitoring and aerial surveys to supplement ship-based visual 
monitoring. All alternatives that would avoid or minimize adverse 
effects of the actions are discussed in the EA. Please

[[Page 47506]]

refer to NMFS EA for detailed information.
    Comment 30: The AWL states that NMFS should consider cumulative 
impacts of other oil and gas activities and other human activities 
planned for the Arctic Ocean in assessing Shell's proposed surveying.
    Response: NMFS prepared an EA to analyze and address cumulative 
impacts of other oil and gas activities planned for the Arctic Ocean. 
The oil and gas related activities in the U.S. Arctic in 2013 include 
this activity; TGS' proposed 2D seismic sruveys in the Chukchi Sea, and 
SAE's proposed 3D seismic survey in the Beaufort Sea. Seismic survey 
activities in the Canadian and Russian Arctic occur in different 
geophysical areas, therefore, they are not analyzed under the NMFS 2013 
EA. Other appropriate factors, such as Arctic warming, military 
activities, and noise contributions from community and commercial 
activities were also considered in NMFS' 2013 EA. Please refer to that 
document for further discussion of cumulative impacts.
    ESA Concern:
    Comment 31: The AWL states that although NMFS has completed a 
programmatic biological opinion for Arctic oil and gas activities, it 
must also thoroughly analyze the impacts of the specific activities 
authorized here including future impacts. The AWL further states that 
in order to comply with the ESA, this site-specific analysis must 
include an incidental take statement specifying the number and type of 
takes expected.
    Response: For the issuance of the IHA to Shell, NMFS' Permits and 
Conservation Division initiated consultation with NMFS Alaska Regional 
Office (AKRO) Protected Resources Division under section 7 of the ESA 
on the issuance of an IHA to Shell under section 101(a)(5)(D) of the 
MMPA for this activity. The consultation took into consideration the 
specific activities proposed to be authorized and all aspects of 
current and future impacts to the species. A Biological Opinion was 
issued on June 19, 2013, which concludes that issuance of the IHA is 
not likely to jeopardize the continued existence of the ESA-listed 
marine mammal species. In addition, analysis by NMFS AKRO showed that 
humpback whale will not be affected, therefore, no take was authorized. 
NMFS will issue an Incidental Take Statement under this Biological 
Opinion which contains reasonable and prudent measures with 
implementing terms and conditions to minimize the effects of take of 
listed species.
    Miscellaneous:
    Comment 32: The BOEM states that if there have been changes to 
Shell's proposed activities and schedule as provided for in the 
proposed IHA, subsequent to their planned village meetings during May, 
then BOEM needs to be advised of the changes so those changes can be 
considered in BOEM's NEPA analysis.
    Response: NMFS will coordinate with project applicants in the 
future to make sure BOEM is updated on any changes to the proposed 
activities and schedules.

Description of Marine Mammals in the Area of the Specified Activity

    The marine mammal species under NMFS jurisdiction most likely to 
occur in the seismic survey area include nine cetacean species, beluga 
whale (Delphinapterus leucas), harbor porpoise (Phocoena phocoena), 
killer whale (Orcinus orca), narwhal (Monodon monoceros), bowhead whale 
(Balaena mysticetus), gray whale (Eschrichtius robustus), minke whale 
(Balaenoptera acutorostrata), fin whale (B. physalus), and humpback 
whale (Megaptera novaeangliae), and four pinniped species, ringed 
(Phoca hispida), spotted (P. largha), bearded (Erignathus barbatus), 
and ribbon seals (Histriophoca fasciata).
    The bowhead, fin, and humpback whales are listed as ``endangered'', 
and the ringed and bearded seals are listed as ``threatened'' under the 
Endangered Species Act (ESA) and as depleted under the MMPA. Certain 
stocks or populations of gray and beluga whales and spotted seals are 
also listed under the ESA, however, none of those stocks or populations 
occur in the proposed activity area.
    Shell's application contains information on the status, 
distribution, seasonal distribution, and abundance of each of the 
species under NMFS jurisdiction mentioned in this document. Please 
refer to the application for that information (see ADDRESSES). 
Additional information can also be found in the NMFS Stock Assessment 
Reports (SAR). The Alaska 2012 SAR is available at: http://www.nmfs.noaa.gov/pr/sars/pdf/ak2012.pdf.

Potential Effects of the Specified Activity on Marine Mammals

    Operating active acoustic sources such as airgun arrays, pinger 
systems, and vessel activities have the potential for adverse effects 
on marine mammals.

Potential Effects of Airgun Sounds on Marine Mammals

    The effects of sounds from airgun pulses might include one or more 
of the following: tolerance, masking of natural sounds, behavioral 
disturbance, and temporary or permanent hearing impairment or non-
auditory effects (Richardson et al. 1995). As outlined in previous NMFS 
documents, the effects of noise on marine mammals are highly variable, 
and can be categorized as follows (based on Richardson et al. 1995):
(1) Behavioral Disturbance
    Marine mammals may behaviorally react to sound when exposed to 
anthropogenic noise. 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 water from haulouts or rookeries).
    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 reproduction. Some of these 
potential significant behavioral modifications include:
     Drastic 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
     Cease feeding or social interaction.
    For example, at the Guerreo Negro Lagoon in Baja California, 
Mexico, which is one of the important breeding grounds for Pacific gray 
whales, shipping and dredging associated with a salt works may have 
induced gray whales to abandon the area through most of the 1960s 
(Bryant et al. 1984). After these activities stopped, the lagoon was 
reoccupied, first by single whales and later by cow-calf pairs.
    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,

[[Page 47507]]

experience, demography) and is also difficult to predict (Southall et 
al. 2007).
    Currently NMFS uses 160 dB re 1 [mu]Pa (rms) at received level for 
impulse noises (such as airgun pulses) as the threshold for the onset 
of marine mammal behavioral harassment.
    In addition, behavioral disturbance is also expressed as the change 
in vocal activities of animals. For example, there is one recent 
summary report indicating that calling fin whales distributed in one 
part of the North Atlantic went silent for an extended period starting 
soon after the onset of a seismic survey in the area (Clark and Gagnon 
2006). It is not clear from that preliminary paper whether the whales 
ceased calling because of masking, or whether this was a behavioral 
response not directly involving masking (i.e., important biological 
signals for marine mammals being ``masked'' by anthropogenic noise; see 
below). Also, bowhead whales in the Beaufort Sea may decrease their 
call rates in response to seismic operations, although movement out of 
the area might also have contributed to the lower call detection rate 
(Blackwell et al. 2009a; 2009b). Some of the changes in marine mammal 
vocal communication are thought to be used to compensate for acoustic 
masking resulting from increased anthropogenic noise (see below). For 
example, blue whales are found to increase call rates when exposed to 
seismic survey noise in the St. Lawrence Estuary (Di Iorio and Clark 
2009). The North Atlantic right whales (Eubalaena glacialis) exposed to 
high shipping noise increase call frequency (Parks et al. 2007) and 
intensity (Parks et al. 2010), while some humpback whales respond to 
low-frequency active sonar playbacks by increasing song length (Miller 
el al. 2000). These behavioral responses could also have adverse 
effects on marine mammals.
    Mysticete: Baleen whales generally tend to avoid operating airguns, 
but avoidance radii are quite variable. Whales are often reported to 
show no overt reactions to airgun pulses at distances beyond a few 
kilometers, even though the airgun pulses remain well above ambient 
noise levels out to much longer distances (reviewed in Richardson et 
al. 1995; Gordon et al. 2004). However, studies done since the late 
1990s of migrating humpback and migrating bowhead whales show 
reactions, including avoidance, that sometimes extend to greater 
distances than documented earlier. Therefore, it appears that 
behavioral disturbance can vary greatly depending on context, and not 
just received levels alone. Avoidance distances often exceed the 
distances at which boat-based observers can see whales, so observations 
from the source vessel can be biased. Observations over broader areas 
may be needed to determine the range of potential effects of some 
large-source seismic surveys where effects on cetaceans may extend to 
considerable distances (Richardson et al. 1999; Moore and Angliss 
2006). Longer-range observations, when required, can sometimes be 
obtained via systematic aerial surveys or aircraft-based observations 
of behavior (e.g., Richardson et al. 1986, 1999; Miller et al. 1999, 
2005; Yazvenko et al. 2007a, 2007b) or by use of observers on one or 
more support vessels operating in coordination with the seismic vessel 
(e.g., Smultea et al. 2004; Johnson et al. 2007). However, the presence 
of other vessels near the source vessel can, at least at times, reduce 
sightability of cetaceans from the source vessel (Beland et al. 2009), 
thus complicating interpretation of sighting data.
    Some baleen whales show considerable tolerance of seismic pulses. 
However, when the pulses are strong enough, avoidance or other 
behavioral changes become evident. Because the responses become less 
obvious with diminishing received sound level, it has been difficult to 
determine the maximum distance (or minimum received sound level) at 
which reactions to seismic activity become evident and, hence, how many 
whales are affected.
    Studies of gray, bowhead, and humpback whales have determined that 
received levels of pulses in the 160-170 dB re 1 [mu]Pa (rms) range 
seem to cause obvious avoidance behavior in a substantial fraction of 
the animals exposed (McCauley et al. 1998, 1999, 2000). In many areas, 
seismic pulses diminish to these levels at distances ranging from 4-15 
km from the source. A substantial proportion of the baleen whales 
within such distances may show avoidance or other strong disturbance 
reactions to the operating airgun array. Some extreme examples 
including migrating bowhead whales avoiding considerably larger 
distances (20-30 km) and lower received sound levels (120-130 dB re 1 
[mu]Pa (rms)) when exposed to airguns from seismic surveys. Also, even 
in cases where there is no conspicuous avoidance or change in activity 
upon exposure to sound pulses from distant seismic operations, there 
are sometimes subtle changes in behavior (e.g., surfacing-respiration-
dive cycles) that are only evident through detailed statistical 
analysis (e.g., Richardson et al. 1986; Gailey et al. 2007).
    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 despite intermittent seismic exploration (and 
much ship traffic) in that area for decades (Appendix A in Malme et al. 
1984; Richardson et al. 1995), and there has been a substantial 
increase in the population over recent decades (Allen and Angliss 
2010). The western Pacific gray whale population did not seem affected 
by a seismic survey in its feeding ground during a prior year (Johnson 
et al. 2007). Similarly, bowhead whales have continued to travel to the 
eastern Beaufort Sea each summer despite seismic exploration in their 
summer and autumn range for many years (Richardson et al. 1987), and 
their numbers have increased notably (Allen and Angliss 2010). Bowheads 
also have been observed over periods of days or weeks in areas 
ensonified repeatedly by seismic pulses (Richardson et al. 1987; Harris 
et al. 2007). However, it is generally not known whether the same 
individual bowheads were involved in these repeated observations 
(within and between years) in strongly ensonified areas.
    Odontocete: Relatively little systematic information is available 
about reactions of toothed whales to airgun pulses. A few studies 
similar to the more extensive baleen whale/seismic pulse work 
summarized above have been reported for toothed whales. However, there 
are recent systematic data 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) and beluga whales (e.g., Miller et al. 2005). There is 
also 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; 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).
    Dolphins and porpoises are often seen by observers on active 
seismic vessels, occasionally at close distances (e.g., bow riding). 
Marine mammal monitoring data during seismic surveys often show that 
animal detection rates drop during the firing of seismic airguns, 
indicating that animals may be avoiding the vicinity of the seismic 
area (Smultea et

[[Page 47508]]

al. 2004; Holst et al. 2006; Hauser et al. 2008; Holst and Smultea 
2008; Richardson et al. 2009). Also, belugas summering in the Canadian 
Beaufort Sea showed larger-scale avoidance, tending to avoid waters out 
to 10-20 km from operating seismic vessels (Miller et al. 2005). In 
contrast, recent studies show little evidence of conspicuous reactions 
by sperm whales to airgun pulses, contrary to earlier indications 
(e.g., Gordon et al. 2006; Stone and Tasker 2006; Winsor and Mate 2006; 
Jochens et al. 2008), except the lower buzz (echolocation signals) 
rates that were detected during exposure of airgun pulses (Miller et 
al. 2009).
    There are almost no specific data on responses of beaked whales to 
seismic surveys, but it is likely that most if not all species show 
strong avoidance. There is increasing evidence that some beaked whales 
may strand after exposure to strong noise from tactical military mid-
frequency sonars. Whether they ever do so in response to seismic survey 
noise is unknown. Northern bottlenose whales seem to continue to call 
when exposed to pulses from distant seismic vessels.
    For delphinids, and possibly the Dall's porpoise, the available 
data suggest that a >=170 dB re 1 [mu]Pa (rms) disturbance criterion 
(rather than >=160 dB) would be appropriate. With a medium-to-large 
airgun array, received levels typically diminish to 170 dB within 1-4 
km, whereas levels typically remain above 160 dB out to 4-15 km (e.g., 
Tolstoy et al. 2009). Reaction distances for delphinids are more 
consistent with the typical 170 dB re 1 [mu]Pa (rms) distances. Stone 
(2003) and Stone and Tasker (2006) reported that all small odontocetes 
(including killer whales) observed during seismic surveys in UK waters 
remained significantly further from the source during periods of 
shooting on surveys with large volume airgun arrays than during periods 
without airgun shooting.
    Due to their relatively higher frequency hearing ranges when 
compared to mysticetes, odontocetes may have stronger responses to mid- 
and high-frequency sources such as sub-bottom profilers, side scan 
sonar, and echo sounders than mysticetes (Richardson et al. 1995; 
Southall et al. 2007).
    Pinnipeds: Few studies of the reactions of pinnipeds to noise from 
open-water seismic exploration have been published (for review of the 
early literature, see Richardson et al. 1995). However, pinnipeds have 
been observed during a number of seismic monitoring studies. Monitoring 
in the Beaufort Sea during 1996-2002 provided a substantial amount of 
information on avoidance responses (or lack thereof) and associated 
behavior. Additional monitoring of that type has been done in the 
Beaufort and Chukchi Seas in 2006--2009. Pinnipeds exposed to seismic 
surveys have also been observed during seismic surveys along the U.S. 
west coast. Also, there are data on the reactions of pinnipeds to 
various other related types of impulsive sounds.
    Early observations provided considerable evidence that pinnipeds 
are often quite tolerant of strong pulsed sounds. During seismic 
exploration off Nova Scotia, gray seals exposed to noise from airguns 
and linear explosive charges reportedly did not react strongly (J. 
Parsons in Greene et al. 1985). An airgun caused an initial startle 
reaction among South African fur seals but was ineffective in scaring 
them away from fishing gear. Pinnipeds in both water and air sometimes 
tolerate strong noise pulses from non-explosive and explosive scaring 
devices, especially if attracted to the area for feeding or 
reproduction (Mate and Harvey 1987; Reeves et al. 1996). Thus, 
pinnipeds are expected to be rather tolerant of, or to habituate to, 
repeated underwater sounds from distant seismic sources, at least when 
the animals are strongly attracted to the area.
    In summary, visual monitoring from seismic vessels has shown only 
slight (if any) avoidance of airguns by pinnipeds, and only slight (if 
any) changes in behavior. These studies show that many pinnipeds do not 
avoid the area within a few hundred meters of an operating airgun 
array. However, based on the studies with large sample size, or 
observations from a separate monitoring vessel, or radio telemetry, it 
is apparent that some phocid seals do show localized avoidance of 
operating airguns. The limited nature of this tendency for avoidance is 
a concern. It suggests that one cannot rely on pinnipeds to move away, 
or to move very far away, before received levels of sound from an 
approaching seismic survey vessel approach those that may cause hearing 
impairment.
(2) Masking
    Masking occurs when noise and signals (that animal utilizes) 
overlap at both spectral and temporal scales. Chronic exposure to 
elevated sound levels could cause masking at particular frequencies for 
marine mammals, which utilize sound for important biological functions. 
Masking can interfere with detection of acoustic signals used for 
orientation, communication, finding prey, and avoiding predators. 
Marine mammals that experience severe (high intensity and extended 
duration) acoustic masking could potentially suffer reduced fitness, 
which could lead to adverse effects on survival and reproduction.
    For the airgun noise generated from the proposed marine seismic 
survey, these are low frequency (under 1 kHz) pulses with extremely 
short durations (in the scale of milliseconds). Lower frequency man-
made noises are more likely to affect detection of communication calls 
and other potentially important natural sounds such as surf and prey 
noise. There is little concern regarding masking due to the brief 
duration of these pulses and relatively longer silence between airgun 
shots (9-12 seconds) near the noise source, however, at long distances 
(over tens of kilometers away) in deep water, due to multipath 
propagation and reverberation, the durations of airgun pulses can be 
``stretched'' to seconds with long decays (Madsen et al. 2006; Clark 
and Gagnon 2006). Therefore it could affect communication signals used 
by low frequency mysticetes when they occur near the noise band and 
thus reduce the communication space of animals (e.g., Clark et al. 
2009a, 2009b) and affect their vocal behavior (e.g., Foote et al. 2004; 
Holt et al. 2009). Further, in areas of shallow water, multipath 
propagation of airgun pulses could be more profound, thus affecting 
communication signals from marine mammals even at close distances. 
Average ambient noise in areas where received seismic noises are heard 
can be elevated. At long distances, however, the intensity of the noise 
is greatly reduced. Nevertheless, partial informational and energetic 
masking of different degrees could affect signal receiving in some 
marine mammals within the ensonified areas. Additional research will 
add to our understanding of these effects.
    Although masking effects of pulsed sounds on marine mammal calls 
and other natural sounds are expected to be limited, there are few 
specific studies on this. Some whales continue calling in the presence 
of seismic pulses and whale calls often can be heard between the 
seismic pulses (e.g., Richardson et al. 1986; McDonald et al. 1995; 
Greene et al. 1999a, 1999b; Nieukirk et al. 2004; Smultea et al. 2004; 
Holst et al. 2005a, 2005b, 2006; Dunn and Hernandez 2009).
    Among the odontocetes, 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 of sperm whales 
found that they continued calling in the presence of

[[Page 47509]]

seismic pulses (Madsen et al. 2002; Tyack et al. 2003; Smultea et al. 
2004; Holst et al. 2006; Jochens et al. 2008). Madsen et al. (2006) 
noted that airgun sounds would not be expected to mask sperm whale 
calls given the intermittent nature of airgun pulses. Dolphins and 
porpoises are also commonly heard calling while airguns are operating 
(Gordon et al. 2004; Smultea et al. 2004; Holst et al. 2005a, 2005b; 
Potter et al. 2007). Masking effects of seismic pulses are expected to 
be negligible in the case of the smaller odontocetes, given the 
intermittent nature of seismic pulses plus the fact that sounds 
important to them are predominantly at much higher frequencies than are 
the dominant components of airgun sounds.
    Pinnipeds have best hearing sensitivity and/or produce most of 
their sounds at frequencies higher than the dominant components of 
airgun sound, but there is some overlap in the frequencies of the 
airgun pulses and the calls. However, the intermittent nature of airgun 
pulses presumably reduces the potential for masking.
    Marine mammals are thought to be able to compensate for masking by 
adjusting their acoustic behavior such as shifting call frequencies, 
and increasing call volume and vocalization rates, as discussed earlier 
(e.g., Miller et al. 2000; Parks et al. 2007; Di Iorio and Clark 2009; 
Parks et al. 2010); the biological significance of these modifications 
is still unknown.
(3) Hearing Impairment
    Marine mammals exposed to high intensity sound repeatedly or for 
prolonged periods can experience hearing threshold shift (TS), which is 
the loss of hearing sensitivity at certain frequency ranges (Kastak et 
al. 1999; Schlundt et al. 2000; Finneran et al. 2002; 2005). TS can be 
permanent (PTS), in which case the loss of hearing sensitivity is 
unrecoverable, or temporary (TTS), in which case the animal's hearing 
threshold will recover over time (Southall et al. 2007). Marine mammals 
that experience TTS or PTS will have reduced sensitivity at the 
frequency band of the TS, which may affect their capability of 
communication, orientation, or prey detection. The degree of TS depends 
on the intensity of the received levels the animal is exposed to, and 
the frequency at which TS occurs depends on the frequency of the 
received noise. It has been shown that in most cases, TS occurs at the 
frequencies approximately one-octave above that of the received noise. 
Repeated noise exposure that leads to TTS could cause PTS. For 
transient sounds, the sound level necessary to cause TTS is inversely 
related to the duration of the sound.
    TTS:
    TTS is the mildest form of hearing impairment that can occur during 
exposure to a strong sound (Kryter 1985). While experiencing TTS, the 
hearing threshold rises and a sound must be stronger in order to be 
heard. It is a temporary phenomenon, and (especially when mild) is not 
considered to represent physical damage or ``injury'' (Southall et al. 
2007). Rather, the onset of TTS is an indicator that, if the animal is 
exposed to higher levels of that sound, physical damage is ultimately a 
possibility.
    The magnitude of TTS depends on the level and duration of noise 
exposure, and to some degree on frequency, among other considerations 
(Kryter 1985; Richardson et al. 1995; Southall et al. 2007). For sound 
exposures at or somewhat above the TTS threshold, hearing sensitivity 
recovers rapidly after exposure to the noise ends. In terrestrial 
mammals, TTS can last from minutes or hours to (in cases of strong TTS) 
days. Only a few data have been obtained on sound levels and durations 
necessary to elicit mild TTS in marine mammals (none in mysticetes), 
and none of the published data concern TTS elicited by exposure to 
multiple pulses of sound during operational seismic surveys (Southall 
et al. 2007).
    For toothed whales, experiments on a bottlenose dolphin (Tursiops 
truncates) and beluga whale showed that exposure to a single watergun 
impulse at a received level of 207 kPa (or 30 psi) peak-to-peak (p-p), 
which is equivalent to 228 dB re 1 [mu]Pa (p-p), resulted in a 7 and 6 
dB TTS in the beluga whale at 0.4 and 30 kHz, respectively. Thresholds 
returned to within 2 dB of the pre-exposure level within 4 minutes of 
the exposure (Finneran et al. 2002). No TTS was observed in the 
bottlenose dolphin.
    Finneran et al. (2005) further examined the effects of tone 
duration on TTS in bottlenose dolphins. Bottlenose dolphins were 
exposed to 3 kHz tones (non-impulsive) for periods of 1, 2, 4 or 8 
seconds (s), with hearing tested at 4.5 kHz. For 1-s exposures, TTS 
occurred with SELs of 197 dB, and for exposures >1 s, SEL >195 dB 
resulted in TTS (SEL is equivalent to energy flux, in dB re 1 
[mu]Pa\2\-s). At an SEL of 195 dB, the mean TTS (4 min after exposure) 
was 2.8 dB. Finneran et al. (2005) suggested that an SEL of 195 dB is 
the likely threshold for the onset of TTS in dolphins and belugas 
exposed to tones of durations 1-8 s (i.e., TTS onset occurs at a near-
constant SEL, independent of exposure duration). That implies that, at 
least for non-impulsive tones, a doubling of exposure time results in a 
3 dB lower TTS threshold.
    However, the assumption that, in marine mammals, the occurrence and 
magnitude of TTS is a function of cumulative acoustic energy (SEL) is 
probably an oversimplification. Kastak et al. (2005) reported 
preliminary evidence from pinnipeds that, for prolonged non-impulse 
noise, higher SELs were required to elicit a given TTS if exposure 
duration was short than if it was longer, i.e., the results were not 
fully consistent with an equal-energy model to predict TTS onset. 
Mooney et al. (2009a) showed this in a bottlenose dolphin exposed to 
octave-band non-impulse noise ranging from 4 to 8 kHz at SPLs of 130 to 
178 dB re 1 [mu]Pa for periods of 1.88 to 30 minutes (min). Higher SELs 
were required to induce a given TTS if exposure duration was short than 
if it was longer. Exposure of the aforementioned bottlenose dolphin to 
a sequence of brief sonar signals showed that, with those brief (but 
non-impulse) sounds, the received energy (SEL) necessary to elicit TTS 
was higher than was the case with exposure to the more prolonged 
octave-band noise (Mooney et al. 2009b). Those authors concluded that, 
when using (non-impulse) acoustic signals of duration ~0.5 s, SEL must 
be at least 210-214 dB re 1 [mu]Pa\2\-s to induce TTS in the bottlenose 
dolphin. The most recent studies conducted by Finneran et al. also 
support the notion that exposure duration has a more significant 
influence compared to SPL as the duration increases, and that TTS 
growth data are better represented as functions of SPL and duration 
rather than SEL alone (Finneran et al. 2010a, 2010b). In addition, 
Finneran et al. (2010b) conclude that when animals are exposed to 
intermittent noises, there is recovery of hearing during the quiet 
intervals between exposures through the accumulation of TTS across 
multiple exposures. Such findings suggest that when exposed to multiple 
seismic pulses, partial hearing recovery also occurs during the seismic 
pulse intervals.
    For baleen whales, there are no data, direct or indirect, on levels 
or properties of sound that are required to induce TTS. The frequencies 
to which baleen whales are most sensitive are lower than those to which 
odontocetes are most sensitive, and natural ambient noise levels at 
those low frequencies tend to be higher (Urick 1983). 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

[[Page 47510]]

at their best frequencies (Clark and Ellison 2004). From this, it is 
suspected that received levels causing TTS onset may also be higher in 
baleen whales. However, no cases of TTS are expected given the small 
size of the airguns proposed to be used and the strong likelihood that 
baleen whales (especially migrating bowheads) would avoid the 
approaching airguns (or vessel) before being exposed to levels high 
enough for there to be any possibility of TTS.
    In pinnipeds, TTS thresholds associated with exposure to brief 
pulses (single or multiple) of underwater sound have not been measured. 
Initial evidence from prolonged exposures suggested that some pinnipeds 
may incur TTS at somewhat lower received levels than do small 
odontocetes exposed for similar durations (Kastak et al. 1999; 2005). 
However, more recent indications are that TTS onset in the most 
sensitive pinniped species studied (harbor seal, which is closely 
related to the ringed seal) may occur at a similar SEL as in 
odontocetes (Kastak et al. 2004).
    Most cetaceans show some degree of avoidance of seismic vessels 
operating an airgun array (see above). It is unlikely that these 
cetaceans would be exposed to airgun pulses at a sufficiently high 
level for a sufficiently long period to cause more than mild TTS, given 
the relative movement of the vessel and the marine mammal. TTS would be 
more likely in any odontocetes that bow- or wake-ride or otherwise 
linger near the airguns. However, while bow- or wake-riding, 
odontocetes would be at the surface and thus not exposed to strong 
sound pulses given the pressure release and Lloyd Mirror effects at the 
surface. But if bow- or wake-riding animals were to dive intermittently 
near airguns, they would be exposed to strong sound pulses, possibly 
repeatedly.
    If some cetaceans did incur mild or moderate TTS through exposure 
to airgun sounds in this manner, this would very likely be a temporary 
and reversible phenomenon. However, even a temporary reduction in 
hearing sensitivity could be deleterious in the event that, during that 
period of reduced sensitivity, a marine mammal needed its full hearing 
sensitivity to detect approaching predators, or for some other reason.
    Some pinnipeds show avoidance reactions to airguns, but their 
avoidance reactions are generally not as strong or consistent as those 
of cetaceans. Pinnipeds occasionally seem to be attracted to operating 
seismic vessels. There are no specific data on TTS thresholds of 
pinnipeds exposed to single or multiple low-frequency pulses. However, 
given the indirect indications of a lower TTS threshold for the harbor 
seal than for odontocetes exposed to impulse sound (see above), it is 
possible that some pinnipeds close to a large airgun array could incur 
TTS.
    NMFS currently typically includes mitigation requirements to ensure 
that cetaceans and pinnipeds are not exposed to pulsed underwater noise 
at received levels exceeding, respectively, 180 and 190 dB re 1 
[micro]Pa (rms). The 180/190 dB acoustic criteria were taken from 
recommendations by an expert panel of the High Energy Seismic Survey 
(HESS) Team that performed an assessment on noise impacts by seismic 
airguns to marine mammals in 1997, although the HESS Team recommended a 
180-dB limit for pinnipeds in California (HESS 1999). The 180 and 190 
dB re 1 [mu]Pa (rms) levels have not been considered to be the levels 
above which TTS might occur. Rather, they were the received levels 
above which, in the view of a panel of bioacoustics specialists 
convened by NMFS before TTS measurements for marine mammals started to 
become available, one could not be certain that there would be no 
injurious effects, auditory or otherwise, to marine mammals. As 
summarized above, data that are now available imply that TTS is 
unlikely to occur in various odontocetes (and probably mysticetes as 
well) unless they are exposed to a sequence of several airgun pulses 
stronger than 190 dB re 1 [mu]Pa (rms). On the other hand, for the 
harbor seal, harbor porpoise, and perhaps some other species, TTS may 
occur upon exposure to one or more airgun pulses whose received level 
equals the NMFS ``do not exceed'' value of 190 dB re 1 [mu]Pa (rms). 
That criterion corresponds to a single-pulse SEL of 175-180 dB re 1 
[mu]Pa \2\-s in typical conditions, whereas TTS is suspected to be 
possible in harbor seals and harbor porpoises with a cumulative SEL of 
~171 and ~164 dB re 1 [mu]Pa \2\-s, respectively.
    It has been shown that most large whales and many smaller 
odontocetes (especially the harbor porpoise) show at least localized 
avoidance of ships and/or seismic operations. Even when avoidance is 
limited to the area within a few hundred meters of an airgun array, 
that should usually be sufficient to avoid TTS based on what is 
currently known about thresholds for TTS onset in cetaceans. In 
addition, ramping up airgun arrays, which is standard operational 
protocol for many seismic operators, may allow cetaceans near the 
airguns at the time of startup (if the sounds are aversive) to move 
away from the seismic source and to avoid being exposed to the full 
acoustic output of the airgun array. Thus, most baleen whales likely 
will not be exposed to high levels of airgun sounds provided the ramp-
up procedure is applied. Likewise, many odontocetes close to the 
trackline are likely to move away before the sounds from an approaching 
seismic vessel become sufficiently strong for there to be any potential 
for TTS or other hearing impairment. Hence, there is little potential 
for baleen whales or odontocetes that show avoidance of ships or 
airguns to be close enough to an airgun array to experience TTS. 
Nevertheless, even if marine mammals were to experience TTS, the 
magnitude of the TTS is expected to be mild and brief, only in a few 
decibels for minutes.
    PTS:
    When PTS occurs, there is physical damage to the sound receptors in 
the ear. In some 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). Physical damage to a mammal's 
hearing apparatus can occur if it is exposed to sound impulses that 
have very high peak pressures, especially if they have very short rise 
times. (Rise time is the interval required for sound pressure to 
increase from the baseline pressure to peak pressure.)
    There is no specific evidence that exposure to pulses of airgun 
sound can cause PTS in any marine mammal, even with large arrays of 
airguns. However, given the likelihood that some mammals close to an 
airgun array might incur at least mild TTS (see above), there has been 
further speculation about the possibility that some individuals 
occurring very close to airguns might incur PTS (e.g., Richardson et 
al. 1995; Gedamke et al. 2008). Single or occasional occurrences of 
mild TTS are not indicative of permanent auditory damage, but repeated 
or (in some cases) single exposures to a level well above that causing 
TTS onset might elicit PTS.
    Relationships between TTS and PTS thresholds have not been widely 
studied in marine mammals, but are assumed to be similar to those in 
humans and other terrestrial mammals (Southall et al. 2007). Based on 
data from terrestrial mammals, a precautionary assumption is that the 
PTS threshold for impulse sounds (such as airgun pulses as received 
close to the source) is at least 6 dB higher than the TTS threshold on 
a peak-pressure basis, and probably >6 dB higher (Southall et al. 
2007). The low-to-moderate levels of TTS that have been induced in 
captive odontocetes and pinnipeds during controlled studies of TTS have 
been confirmed to be temporary, with no measurable residual

[[Page 47511]]

PTS (Kastak et al. 1999; Schlundt et al. 2000; Finneran et al. 2002; 
2005; Nachtigall et al. 2003; 2004). However, very prolonged exposure 
to sound strong enough to elicit TTS, or shorter-term exposure to sound 
levels well above the TTS threshold, can cause PTS, at least in 
terrestrial mammals (Kryter 1985). In terrestrial mammals, the received 
sound level from a single non-impulsive sound exposure must be far 
above the TTS threshold for any risk of permanent hearing damage 
(Kryter 1994; Richardson et al. 1995; Southall et al. 2007). However, 
there is special concern about strong sounds whose pulses have very 
rapid rise times. In terrestrial mammals, there are situations when 
pulses with rapid rise times (e.g., from explosions) can result in PTS 
even though their peak levels are only a few dB higher than the level 
causing slight TTS. The rise time of airgun pulses is fast, but not as 
fast as that of an explosion.
    Some factors that contribute to onset of PTS, at least in 
terrestrial mammals, are as follows:
     Exposure to a single very intense sound,
     fast rise time from baseline to peak pressure,
     repetitive exposure to intense sounds that individually 
cause TTS but not PTS, and
     recurrent ear infections or (in captive animals) exposure 
to certain drugs.
    Cavanagh (2000) reviewed the thresholds used to define TTS and PTS. 
Based on this review and SACLANT (1998), it is reasonable to assume 
that PTS might occur at a received sound level 20 dB or more above that 
inducing mild TTS. However, for PTS to occur at a received level only 
20 dB above the TTS threshold, the animal probably would have to be 
exposed to a strong sound for an extended period, or to a strong sound 
with a rather rapid rise time.
    More recently, Southall et al. (2007) estimated that received 
levels would need to exceed the TTS threshold by at least 15 dB, on an 
SEL basis, for there to be risk of PTS. Thus, for cetaceans exposed to 
a sequence of sound pulses, they estimate that the PTS threshold might 
be an M-weighted SEL (for the sequence of received pulses) of ~198 dB 
re 1 [mu]Pa \2\-s. Additional assumptions had to be made to derive a 
corresponding estimate for pinnipeds, as the only available data on 
TTS-thresholds in pinnipeds pertained to nonimpulse sound (see above). 
Southall et al. (2007) estimated that the PTS threshold could be a 
cumulative SEL of ~186 dB re 1 [mu]Pa \2\-s in the case of a harbor 
seal exposed to impulse sound. The PTS threshold for the California sea 
lion and northern elephant seal would probably be higher given the 
higher TTS thresholds in those species. Southall et al. (2007) also 
note that, regardless of the SEL, there is concern about the 
possibility of PTS if a cetacean or pinniped received one or more 
pulses with peak pressure exceeding 230 or 218 dB re 1 [mu]Pa, 
respectively. Thus, PTS might be expected upon exposure of cetaceans to 
either SEL >=198 dB re 1 [mu]Pa \2\-s or peak pressure >=230 dB re 1 
[mu]Pa. Corresponding proposed dual criteria for pinnipeds (at least 
harbor seals) are >=186 dB SEL and >= 218 dB peak pressure (Southall et 
al. 2007). These estimates are all first approximations, given the 
limited underlying data, assumptions, species differences, and evidence 
that the ``equal energy'' model may not be entirely correct.
    Sound impulse duration, peak amplitude, rise time, number of 
pulses, and inter-pulse interval are the main factors thought to 
determine the onset and extent of PTS. Ketten (1994) has noted that the 
criteria for differentiating the sound pressure levels that result in 
PTS (or TTS) are location and species specific. PTS effects may also be 
influenced strongly by the health of the receiver's ear.
    As described above for TTS, in estimating the amount of sound 
energy required to elicit the onset of TTS (and PTS), it is assumed 
that the auditory effect of a given cumulative SEL from a series of 
pulses is the same as if that amount of sound energy were received as a 
single strong sound. There are no data from marine mammals concerning 
the occurrence or magnitude of a potential partial recovery effect 
between pulses. In deriving the estimates of PTS (and TTS) thresholds 
quoted here, Southall et al. (2007) made the precautionary assumption 
that no recovery would occur between pulses.
    It is unlikely that an odontocete would remain close enough to a 
large airgun array for sufficiently long to incur PTS. There is some 
concern about bowriding odontocetes, but for animals at or near the 
surface, auditory effects are reduced by Lloyd's mirror and surface 
release effects. The presence of the vessel between the airgun array 
and bow-riding odontocetes could also, in some but probably not all 
cases, reduce the levels received by bow-riding animals (e.g., Gabriele 
and Kipple 2009). The TTS (and thus PTS) thresholds of baleen whales 
are unknown but, as an interim measure, assumed to be no lower than 
those of odontocetes. Also, baleen whales generally avoid the immediate 
area around operating seismic vessels, so it is unlikely that a baleen 
whale could incur PTS from exposure to airgun pulses. The TTS (and thus 
PTS) thresholds of some pinnipeds (e.g., harbor seal) as well as the 
harbor porpoise may be lower (Kastak et al. 2005; Southall et al. 2007; 
Lucke et al. 2009). If so, TTS and potentially PTS may extend to a 
somewhat greater distance for those animals. Again, Lloyd's mirror and 
surface release effects will ameliorate the effects for animals at or 
near the surface.
(4) Non-auditory Physical Effects
    Non-auditory physical effects might occur in marine mammals exposed 
to strong underwater pulsed sound. Possible types of non-auditory 
physiological effects or injuries that theoretically might occur in 
mammals close to a strong sound source include neurological effects, 
bubble formation, and other types of organ or tissue damage. Some 
marine mammal species (i.e., beaked whales) may be especially 
susceptible to injury and/or stranding when exposed to intense sounds. 
However, there is no definitive evidence that any of these effects 
occur even for marine mammals in close proximity to large arrays of 
airguns, and beaked whales do not occur in the proposed project area. 
In addition, marine mammals that show behavioral avoidance of seismic 
vessels, including most baleen whales, some odontocetes (including 
belugas), and some pinnipeds, are especially unlikely to incur non-
auditory impairment or other physical effects.
    Therefore, it is unlikely that such effects would occur during 
Shell's proposed marine surveys given the brief duration of exposure, 
the small sound sources, and the planned monitoring and mitigation 
measures described later in this document.
    Additional non-auditory effects include elevated levels of stress 
response (Wright et al. 2007; Wright and Highfill 2007). Although not 
many studies have been done on noise-induced stress in marine mammals, 
extrapolation of information regarding stress responses in other 
species seems applicable because the responses are highly consistent 
among all species in which they have been examined to date (Wright et 
al. 2007). Therefore, it is reasonable to conclude that noise acts as a 
stressor to marine mammals. Furthermore, given that marine mammals will 
likely respond in a manner consistent with other species studied, 
repeated and prolonged exposures to stressors (including or induced by 
noise) could potentially be

[[Page 47512]]

problematic for marine mammals of all ages. Wright et al. (2007) state 
that a range of issues may arise from an extended stress response 
including, but not limited to, suppression of reproduction 
(physiologically and behaviorally), accelerated aging and sickness-like 
symptoms. However, as mentioned above, Shell's proposed activity is not 
expected to result in these severe effects due to the nature of the 
potential sound exposure.
(5) Stranding and Mortality
    Marine mammals close to underwater detonations can be killed or 
severely injured, and the auditory organs are especially susceptible to 
injury (Ketten et al. 1993; Ketten 1995). Airgun pulses are less 
energetic and their peak amplitudes have slower rise times, while 
stranding and mortality events would include other energy sources 
(acoustical or shock wave) far beyond just seismic airguns. To date, 
there is no evidence that serious injury, death, or stranding by marine 
mammals can occur from exposure to airgun pulses, even in the case of 
large airgun arrays.
    However, in numerous past IHA notices for seismic surveys, 
commenters have referenced two stranding events allegedly associated 
with seismic activities, one off Baja California and a second off 
Brazil. NMFS has addressed this concern several times, and, without new 
information, does not believe that this issue warrants further 
discussion. For information relevant to strandings of marine mammals, 
readers are encouraged to review NMFS' response to comments on this 
matter found in 69 FR 74906 (December 14, 2004), 71 FR 43112 (July 31, 
2006), 71 FR 50027 (August 24, 2006), and 71 FR 49418 (August 23, 
2006).
    It should be noted that strandings related to sound exposure have 
not been recorded for marine mammal species in the Chukchi or Beaufort 
seas. NMFS notes that in the Beaufort and Chukchi seas, aerial surveys 
have been conducted by BOEM (previously MMS) and industry during 
periods of industrial activity (and by BOEM during times with no 
activity). No strandings or marine mammals in distress have been 
observed during these surveys and none have been reported by North 
Slope Borough inhabitants. In addition, there are very few instances 
that seismic surveys in general have been linked to marine mammal 
strandings, other than those mentioned above. As a result, NMFS does 
not expect any marine mammals will incur serious injury or mortality in 
the Arctic Ocean or strand as a result of the proposed marine survey.

Potential Effects of Sonar Signals

    A variety of active acoustic instrumentation would be used during 
Shell's proposed marine surveys program. Source characteristics and 
propagation distances to 160 (rms) dB re 1 [mu]Pa by comparable 
instruments are listed in Table 2. In general, the potential effects of 
this equipment on marine mammals are similar to those from the airgun, 
except the magnitude of the impacts is expected to be much less due to 
the lower intensity and higher frequencies. In some cases, due to the 
fact that the operating frequencies of some of this equipment (e.g., 
Multi-beam bathymetric sonar: frequency at 220-240 kHz) are above the 
hearing ranges of marine mammals, they are not expected to have any 
impacts to marine mammals.

Vessel Sounds

    In addition to the noise generated from seismic airguns and active 
sonar systems, various types of vessels will be used in the operations, 
including source vessel and vessels used for equipment recovery and 
maintenance and logistic support. Sounds from boats and vessels have 
been reported extensively (Greene and Moore 1995; Blackwell and Greene 
2002; 2005; 2006). Numerous measurements of underwater vessel sound 
have been performed in support of recent industry activity in the 
Chukchi and Beaufort Seas. Results of these measurements were reported 
in various 90-day and comprehensive reports since 2007 (e.g., Aerts et 
al. 2008; Hauser et al. 2008; Brueggeman 2009; Ireland et al. 2009; 
O'Neill and McCrodan 2011; Chorney et al. 2011; McPherson and Warner 
2012). For example, Garner and Hannay (2009) estimated sound pressure 
levels of 100 dB at distances ranging from approximately 1.5 to 2.3 mi 
(2.4 to 3.7 km) from various types of barges. MacDonald et al. (2008) 
estimated higher underwater SPLs from the seismic vessel Gilavar of 120 
dB at approximately 13 mi (21 km) from the source, although the sound 
level was only 150 dB at 85 ft (26 m) from the vessel. Compared to 
airgun pulses, underwater sound from vessels is generally at relatively 
low frequencies. However, noise from the vessel during equipment 
recovery and maintenance while operating the DP system using thrusters 
as well as the primary propeller(s) could produce noise levels higher 
than during normal operation of the vessel. Measurements of a vessel in 
DP mode with an active bow thruster were made in the Chukchi Sea in 
2010 (Chorney et al. 2011). The resulting source level estimate was 
175.9 dB (rms) re 1 [mu]Pa-m. Acoustic measurements of the Nordica in 
DP mode while supporting Shell's 2012 drilling operation in the Chukchi 
Sea showed that the 120 dB re 1 [mu] Pa radius was at approximately 4 
km (2.5 mi) (Bisson et al. 2013).
    The primary sources of sounds from all vessel classes are propeller 
cavitation, propeller singing, and propulsion or other machinery. 
Propeller cavitation is usually the dominant noise source for vessels 
(Ross 1976). Propeller cavitation and singing are produced outside the 
hull, whereas propulsion or other machinery noise originates inside the 
hull. There are additional sounds produced by vessel activity, such as 
pumps, generators, flow noise from water passing over the hull, and 
bubbles breaking in the wake. Source levels from various vessels would 
be empirically measured before the start of marine surveys, and during 
equipment recovery and maintenance while operating the DP system.

Anticipated Effects on Habitat

    The primary potential impacts to marine mammals and other marine 
species are associated with elevated sound levels produced by airguns 
and vessels operating in the area. However, other potential impacts to 
the surrounding habitat from physical disturbance are also possible.
    With regard to fish as a prey source for cetaceans and pinnipeds, 
fish are known to hear and react to sounds and to use sound to 
communicate (Tavolga et al. 1981) and possibly avoid predators (Wilson 
and Dill 2002). Experiments have shown that fish can sense both the 
strength and direction of sound (Hawkins 1981). Primary factors 
determining whether a fish can sense a sound signal, and potentially 
react to it, are the frequency of the signal and the strength of the 
signal in relation to the natural background noise level.
    The level of sound at which a fish will react or alter its behavior 
is usually well above the detection level. Fish have been found to 
react to sounds when the sound level increased to about 20 dB above the 
detection level of 120 dB (Ona 1988); however, the response threshold 
can depend on the time of year and the fish's physiological condition 
(Engas et al. 1993). In general, fish react more strongly to pulses of 
sound rather than non-pulse signals (such as noise from vessels) 
(Blaxter et al. 1981), and a quicker alarm response is elicited when 
the sound signal intensity rises rapidly compared to sound rising more 
slowly to the same level.

[[Page 47513]]

    Investigations of fish behavior in relation to vessel noise (Olsen 
et al. 1983; Ona 1988; Ona and Godo 1990) have shown that fish react 
when the sound from the engines and propeller exceeds a certain level. 
Avoidance reactions have been observed in fish such as cod and herring 
when vessels approached close enough that received sound levels are 110 
dB to 130 dB (Nakken 1992; Olsen 1979; Ona and Godo 1990; Ona and 
Toresen 1988). However, other researchers have found that fish such as 
polar cod, herring, and capeline are often attracted to vessels 
(apparently by the noise) and swim toward the vessel (Rostad et al. 
2006). Typical sound source levels of vessel noise in the audible range 
for fish are 150 dB to 170 dB (Richardson et al. 1995).
    Further, during the seismic survey only a small fraction of the 
available habitat would be ensonified at any given time. Disturbance to 
fish species would be short-term and fish would return to their pre-
disturbance behavior once the seismic activity ceases (McCauley et al. 
2000a, 2000b; Santulli et al. 1999; Pearson et al. 1992). Thus, the 
proposed survey would have little, if any, impact on the abilities of 
marine mammals to feed in the area where seismic work is planned.
    Some mysticetes, including bowhead whales, feed on concentrations 
of zooplankton. Some feeding bowhead whales may occur in the Alaskan 
Beaufort Sea in July and August, and others feed intermittently during 
their westward migration in September and October (Richardson and 
Thomson [eds.] 2002; Lowry et al. 2004). A reaction by zooplankton to a 
seismic impulse would only be relevant to whales if it caused 
concentrations of zooplankton to scatter. Pressure changes of 
sufficient magnitude to cause that type of reaction would probably 
occur only very close to the source. Impacts on zooplankton behavior 
are predicted to be negligible, and that would translate into 
negligible impacts on feeding mysticetes. Thus, the proposed activity 
is not expected to have any habitat-related effects on prey species 
that could cause significant or long-term consequences for individual 
marine mammals or their populations.

Potential Impacts on Availability of Affected Species or Stock for 
Taking for Subsistence Uses

    Subsistence hunting is an essential aspect of Inupiat Native life, 
especially in rural coastal villages. The Inupiat participate in 
subsistence hunting activities in and around the Chukchi Sea. The 
animals taken for subsistence provide a significant portion of the food 
that will last the community through the year. Marine mammals represent 
on the order of 60-80% of the total subsistence harvest. Along with the 
nourishment necessary for survival, the subsistence activities 
strengthen bonds within the culture, provide a means for educating the 
young, provide supplies for artistic expression, and allow for 
important celebratory events.
    The communities closest to the project area are the villages of 
Wainwright and Barrow. Shell's proposed ice gouge surveys would occur 
offshore Wainwright but would be approximately 30 km from Barrow and 48 
km from Point Lay. The closest point for Shell's proposed site 
clearance and shallow hazards surveys and equipment recovery and 
maintenance activities would be approximately 120 km to Wainwright and 
150 km to Point Lay, and much farther away to Barrow.

Potential Impacts to Subsistence Uses

    NMFS has defined ``unmitigable adverse impact'' in 50 CFR 216.103 
as: ``[hellip]an impact resulting from the specified activity: (1) That 
is likely to reduce the availability of the species to a level 
insufficient for a harvest to meet subsistence needs by: (i) Causing 
the marine mammals to abandon or avoid hunting areas; (ii) Directly 
displacing subsistence users; or (iii) Placing physical barriers 
between the marine mammals and the subsistence hunters; and (2) That 
cannot be sufficiently mitigated by other measures to increase the 
availability of marine mammals to allow subsistence needs to be met.''
(1) Bowhead Whales
    Shell's planned surveys would have no or negligible effects on 
bowhead whale harvest activities. Noise and general activity associated 
with marine surveys and operation of vessels has the potential to 
harass bowhead whales. However, though temporary diversions of the swim 
path of migrating whales have been documented, the whales have 
generally been observed to resume their initial migratory route. The 
proposed open-water marine surveys and vessel noise could in some 
circumstances affect subsistence hunts by placing the animals further 
offshore or otherwise at a greater distance from villages thereby 
increasing the difficulty of the hunt or retrieval of the harvest, or 
creating a safety risk to the whalers. Residents of Barrow hunt 
bowheads during the spring and fall migration. Although bowhead hunts 
by residents of Wainwright, Point Lay and Point Hope used to take place 
mostly in the spring and were typically curtailed when ice begins to 
break up, the Chukchi Sea communities increasingly are being forced to 
look to fall hunting opportunities as ice conditions in the spring are 
making it more dangerous and difficult to meet the quotas. From 1974 
through 2009, bowhead harvests by these Chukchi Sea villages occurred 
only in the spring between early April and mid-June (Suydam and George, 
2012). A Wainwright whaling crew harvested the first fall bowhead in 90 
years or more on October 8, 2010, and again in October of 2011. Fall 
whaling by Chukchi Sea villages may occur in the future, particularly 
if bowhead quotas are not completely filled during the spring hunt, and 
fall weather is accommodating.
    During the survey period most marine mammals are expected to be 
dispersed throughout the area, except during the peak of the bowhead 
whale migration through the Chukchi Seas, which occurs from late August 
into October. Bowhead whales are expected to be in the Canadian 
Beaufort Sea during much of the time, and therefore are not expected to 
be affected by the proposed marine surveys and vessel noise prior to 
the start of the fall subsistence hunt. After the conclusion of the 
subsistence hunt, bowheads may travel in proximity to the survey area 
and hear sounds from sonar, high resolution profilers, and associated 
vessel sounds; and may be displaced by these activities.
(2) Beluga Whales
    Belugas typically do not represent a large proportion of the 
subsistence harvests by weight in the communities of Wainwright and 
Barrow, the nearest communities to Shell's planned 2013 activities in 
the Chukchi Sea. Barrow residents hunt beluga in the spring normally 
after the bowhead hunt) in leads between Point Barrow and Skull Cliffs 
in the Chukchi Sea primarily in April-June, and later in the summer 
(July-August) on both sides of the barrier island in Elson Lagoon/
Beaufort Sea (MMS 2008), but harvest rates indicate the hunts are not 
frequent. Wainwright residents hunt beluga in April-June in the spring 
lead system, but this hunt typically occurs only if there are no 
bowheads in the area. Communal hunts for beluga are conducted along the 
coastal lagoon system later in July-August.
    Belugas typically represent a much greater proportion of the 
subsistence harvest in Point Lay and Point Hope. Point Lay's primary 
beluga hunt occurs from mid-June through mid-July, but can sometimes 
continue into August if early success is not sufficient. Point Hope 
residents hunt beluga primarily in

[[Page 47514]]

the lead system during the spring (late March to early June) bowhead 
hunt, but also in open water along the coastline in July and August. 
Belugas are harvested in coastal waters near these villages, generally 
within a few miles from shore. The southern extent of Shell's proposed 
surveys is Icy Cape which lies over 30 miles (48 km) to the north of 
Point Lay, and therefore NMFS considers that the surveys would have no 
or negligible effect on beluga hunts.
    The survey vessel may be resupplied via another vessel from onshore 
support facilities and may traverse areas that are sometimes used for 
subsistence hunting of belugas. Disturbance associated with vessel and 
potential aircraft traffic could therefore potentially affect beluga 
hunts. However, all of the beluga hunt by Barrow residents in the 
Chukchi Sea, and much of the hunt by Wainwright residents would likely 
be completed before Shell activities would commence.
(3) Seals
    Seals are an important subsistence resource and ringed seals make 
up the bulk of the seal harvest. Most ringed and bearded seals are 
harvested in the winter or in the spring before Shell's 2013 activities 
would commence, but some harvest continues during open water and could 
possibly be affected by Shell's planned activities. Spotted seals are 
also harvested during the summer. Most seals are harvested in coastal 
waters, with available maps of recent and past subsistence use areas 
indicating seal harvests have occurred only within 30-40 mi (48-64 km) 
off the coastline. Shells planned offshore surveys, equipment recovery 
and maintenance would occur outside state waters and are not likely to 
have an impact on subsistence hunting for seals. Resupply vessel and 
air traffic between land and the operations vessels could potentially 
disturb seals and, therefore, subsistence hunts for seals, but any such 
effects would be minor due to the small number of supporting vessels 
and the fact that most seal hunting is done during the winter and 
spring.
    As stated earlier, the proposed seismic survey would take place 
between July and October. The closest extension of the proposed site 
clearance and shallow hazards surveys located approximately 120 km to 
Wainwright and 150 km to Point Lay, and much farther to Barrow. 
Potential impact from the planned activities is expected mainly from 
sounds generated by the vessel and during active airgun deployment. Due 
to the timing of the project and the distance from the surrounding 
communities, it is anticipated to have no effects on spring harvesting 
and little or no effects on the occasional summer harvest of beluga 
whale, subsistence seal hunts (ringed and spotted seals are primarily 
harvested in winter while bearded seals are hunted during July--
September in the Beaufort Sea), or the fall bowhead hunt.
    In addition, Shell has developed and proposes to implement a number 
of mitigation measures which include a proposed Marine Mammal 
Monitoring and Mitigation Plan (4MP), employment of subsistence 
advisors in the villages, and implementation of a Communications Plan 
(with operation of Communication Centers). Shell has prepared a Plan of 
Cooperation (POC) under 50 CFR 216.104 Article 12 of the MMPA to 
address potential impacts on subsistent seal hunting activities. Shell 
met with the Alaska Eskimo Whaling Commission (AEWC) and communities' 
Whaling Captains' Associations as part of the POC development, to 
establish avoidance guidelines and other mitigation measures to be 
followed where the proposed activities may have an impact on 
subsistence.
    Finally, to ensure that there will be no conflict from Shell's 
proposed open-water marine surveys and equipment recovery and 
maintenance to subsistence activities, Shell signed a Conflict 
Avoidance Agreement with the local subsistence communities. The CAA 
identifies what measures have been or will be taken to minimize adverse 
impacts of the planned activities on subsistence harvesting.

Mitigation Measures

    In order to issue an incidental take authorization under Section 
101(a)(5)(D) of the MMPA, NMFS must set forth the permissible methods 
of taking pursuant to such activity, and other means of effecting the 
least practicable adverse impact on such species or stock and its 
habitat, paying particular attention to rookeries, mating grounds, and 
areas of similar significance, and on the availability of such species 
or stock for taking for certain subsistence uses.
    For the Shell open-water marine surveys and equipment recovery and 
maintenance activities in the Chukchi Sea, NMFS is requiring Shell to 
implement the following mitigation measures to minimize the potential 
impacts to marine mammals in the project vicinity as a result of its 
survey activities. The primary purpose of these mitigation measures is 
to detect marine mammals within, or about to enter designated exclusion 
zones and to initiate immediate shutdown or power down of the 
airgun(s).
(1) Establishing Exclusion and Disturbance Zones
    Under current NMFS guidelines, the ``exclusion zone'' for marine 
mammal exposure to impulse sources is customarily defined as the area 
within which received sound levels are >=180 dB (rms) re 1 [mu]Pa for 
cetaceans and >=190 dB (rms) re 1 [mu]Pa for pinnipeds. These safety 
criteria are based on an assumption that SPL received at levels lower 
than these will not injure these animals or impair their hearing 
abilities, but that at higher levels might have some such effects. 
Disturbance or behavioral effects to marine mammals from underwater 
sound may occur after exposure to sound at distances greater than the 
exclusion zones (Richarcdson et al. 1995). Currently, NMFS uses 160 dB 
(rms) re 1 [mu]Pa as the threshold for Level B behavioral harassment 
from impulses noise, and 120 dB (rms) re 1 [mu]Pa for Level B 
behavioral harassment from non-impulse noise.
    Exclusion and disturbance radii for the sound levels produced by 
the 40 in \3\ array and the single mitigation airgun (10 cubic inches) 
to be used during the 2013 site clearance and shallow hazards survey 
activities were measured at the Honeyguide and Burger prospect areas a 
total of three separate times between 2008 and 2009. The largest radii 
from these measurements will be implemented at the commencement of 2013 
airgun operations to establish marine mammal exclusion zones used for 
mitigation (Table 3). Shell will conduct sound source measurements of 
the airgun array at the beginning of survey operations in 2013 to 
verify the size of the various marine mammal exclusion zones (see 
above). The acoustic data will be analyzed as quickly as reasonably 
practicable in the field and used to verify and adjust the marine 
mammal exclusion zone distances. The mitigation measures to be 
implemented at the 190 and 180 dB (rms) sound levels will include power 
downs and shut downs as described below.

[[Page 47515]]



    Table 3--Distances of the 190 and 180 dB (rms) re 1 [micro]Pa isolpeths (in m) To Be Used for Mitigation
    Purposes at the Beginning of 2013 Airgun Operations in the Chukchi Seal Until SSV Results Are Available.
----------------------------------------------------------------------------------------------------------------
Received levels (dB re 1 [mu]Pa rms)        4-Airgun array (40 in\3\)             Single airgun (10 in\3\)
----------------------------------------------------------------------------------------------------------------
                          190                                    50                                    23
                          180                                   160                                    52
----------------------------------------------------------------------------------------------------------------

(2) Vessel and Helicopter Related Mitigation Measures,
    This mitigation measure applies to all vessels that are part of the 
Chukchi Sea marine surveys and equipment recovery and maintenance 
activities, including crew transfer vessels.

 Avoid concentrations or groups of whales by all vessels under 
the direction of Shell. Operators of support vessels should, at all 
times, conduct their activities at the maximum distance possible from 
such concentrations of whales.
 Vessels in transit shall be operated at speeds necessary to 
ensure no physical contact with whales occurs. If any vessel approaches 
within 1.6 km (1 mi) of observed bowhead whales, except when providing 
emergency assistance to whalers or in other emergency situations, the 
vessel operator will take reasonable precautions to avoid potential 
interaction with the bowhead whales by taking one or more of the 
following actions, as appropriate:
[cir] Reducing vessel speed to less than 5 knots within 300 yards (900 
feet or 274 m) of the whale(s);
[cir] Steering around the whale(s) if possible;
[cir] Operating the vessel(s) in such a way as to avoid separating 
members of a group of whales from other members of the group;
[cir] Operating the vessel(s) to avoid causing a whale to make multiple 
changes in direction; and
[cir] Checking the waters immediately adjacent to the vessel(s) to 
ensure that no whales will be injured when the propellers are engaged.
     When weather conditions require, such as when visibility 
drops, adjust vessel speed accordingly to avoid the likelihood of 
injury to whales.
     In the event that any aircraft (such as helicopters) are 
used to support the planned survey, the mitigation measures below would 
apply:
[cir] Under no circumstances, other than an emergency, shall aircraft 
be operated at an altitude lower than 1,000 feet above sea level (ASL) 
when within 0.3 mile (0.5 km) of groups of whales.
[cir] Helicopters shall not hover or circle above or within 0.3 mile 
(0.5 km) of groups of whales.
(3) Mitigation Measures for Airgun Operations
    The primary role for airgun mitigation during the site clearance 
and shallow hazards surveys is to monitor marine mammals near the 
airgun array during all daylight airgun operations and during any 
nighttime start-up of the airguns. During the site clearance and 
shallow hazards surveys PSOs will monitor the pre-established exclusion 
zones for the presence of marine mammals. When marine mammals are 
observed within, or about to enter, designated exclusion zones, PSOs 
have the authority to call for immediate power down (or shutdown) of 
airgun operations as required by the situation. A summary of the 
procedures associated with each mitigation measure is provided below.

Ramp Up Procedure

    A 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 is achieved. The purpose 
of a ramp up (or ``soft start'') is to ``warn'' cetaceans and pinnipeds 
in the vicinity of the airguns and to provide time for them to leave 
the area and thus avoid any potential injury or impairment of their 
hearing abilities.
    During the shallow hazards survey program, the seismic operator 
will ramp up the airgun arrays slowly. Full ramp ups (i.e., from a cold 
start after a shut down, when no airguns have been firing) will begin 
by firing a single airgun in the array (i.e., the mitigation airgun). A 
full ramp up, after a shut down, will not begin until there has been a 
minimum of 30 min of observation of the exclusion zone by PSOs to 
assure that no marine mammals are present. The entire exclusion zone 
must be visible during the 30-minute lead-in to a full ramp up. If the 
entire exclusion zone is not visible, then ramp up from a cold start 
cannot begin. If a marine mammal(s) is sighted within the exclusion 
zone during the 30-minute watch prior to ramp up, ramp up will be 
delayed until the marine mammal(s) is sighted outside of the exclusion 
zone or the animal(s) is not sighted for at least 15-30 minutes: 15 
minutes for small odontocetes (harbor porpoise) and pinnipeds, or 30 
minutes for baleen whales and large odontocetes (including beluga and 
killer whales and narwhal).

Use of a Small-Volume Airgun During Turns and Transits

    Throughout the seismic survey, particularly during turning 
movements, and short transits, Shell will employ the use of a small-
volume airgun (i.e., 10 in\3\ ``mitigation airgun'') to deter marine 
mammals from being within the immediate area of the seismic operations. 
The mitigation airgun would be operated at approximately one shot per 
minute and would not be operated for longer than three hours in 
duration (turns may last two to three hours for the proposed project).
    During turns or brief transits (e.g., less than three hours) 
between seismic tracklines, one mitigation airgun will continue 
operating. The ramp-up procedure will still be followed when increasing 
the source levels from one airgun to the full airgun array. However, 
keeping one airgun firing will avoid the prohibition of a ``cold 
start'' during darkness or other periods of poor visibility. Through 
use of this approach, site clearance and shallow hazards surveys using 
the full array may resume without the 30 minute observation period of 
the full exclusion zone required for a ``cold start''. PSOs will be on 
duty whenever the airguns are firing during daylight, during the 30 
minute periods prior to ramp-ups.

Power-Down and Shut Down Procedures

    A power down is the immediate reduction in the number of operating 
energy sources from all firing to some smaller number (e.g., single 
mitigation airgun). A shut down is the immediate cessation of firing of 
all energy sources. The array will be immediately powered down whenever 
a marine mammal is sighted approaching close to or within the 
applicable exclusion zone of the full array, but is outside the 
applicable exclusion zone of the single mitigation source. If a marine 
mammal is sighted within or about to enter the applicable

[[Page 47516]]

exclusion zone of the single mitigation airgun, the entire array will 
be shut down (i.e., no sources firing).
    In addition, site clearance and shallow hazard surveys will not 
commence or will shut down if an aggregation of 12 or more bowhead 
whales or gray whales that appear to be engaged in a non-migratory, 
significant biological behavior (e.g., feeding, socializing) are 
observed during vessel monitoring within the 160-dB zone of 
disturbance.

Poor Visibility Conditions

    Shell plans to conduct 24-hour operations. PSOs will not be on duty 
during ongoing seismic operations during darkness, given the very 
limited effectiveness of visual observation at night (there will be no 
periods of darkness in the survey area until mid-August). The 
provisions associated with operations at night or in periods of poor 
visibility include the following:
     If during foggy conditions, heavy snow or rain, or 
darkness (which may be encountered starting in late August), the full 
180 dB exclusion zone is not visible, the airguns cannot commence a 
ramp-up procedure from a full shut-down.
     If one or more airguns have been operational before 
nightfall or before the onset of poor visibility conditions, they can 
remain operational throughout the night or poor visibility conditions. 
In this case ramp-up procedures can be initiated, even though the 
exclusion zone may not be visible, on the assumption that marine 
mammals will be alerted by the sounds from the single airgun and have 
moved away.
(4) Mitigation Measures for Subsistence Activities
    Regulations at 50 CFR 216.104(a)(12) require IHA applicants for 
activities that take place in Arctic waters to provide a Plan of 
Cooperation (POC) or information that identifies what measures have 
been taken and/or will be taken to minimize adverse effects on the 
availability of marine mammals for subsistence purposes.
    Shell has prepared a POC, which relies upon the Chukchi Sea 
Communication Plans to identify the measures that Shell has developed 
in consultation with North Slope subsistence communities and will 
implement during its planned 2013 activities to minimize any adverse 
effects on the availability of marine mammals for subsistence uses. In 
addition, the POC provides detailed Shell's communications and 
consultations with local subsistence communities concerning its planned 
2013 program, potential conflicts with subsistence activities, and 
means of resolving any such conflicts.
    The POC is the result of numerous meetings and consultations 
between Shell, affected subsistence communities and stakeholders, and 
federal agencies. The POC identifies and documents potential conflicts 
and associated measures that will be taken to minimize any adverse 
effects on the availability of marine mammals for subsistence use. 
Outcomes of POC meetings are typically included in updates attached to 
the POC as addenda and distributed to federal, state, and local 
agencies as well as local stakeholder groups that either adjudicate or 
influence mitigation approaches for Shell's open-water programs.
    Meetings for Shell's 2013 drilling and open-water marine surveys 
programs in the Beaufort and Chukchi Seas occurred in Kaktovik, Nuiqsut 
Barrow, Wainwright, and Point Lay, during October of 2012. Shell met 
with the marine mammal commissions and committees including the Alaska 
Eskimo Whaling Commission (AEWC), Eskimo Walrus Commission (EWC), 
Alaska Beluga Whale Committee (ABWC), Alaska Ice Seal Committee (AISC), 
and the Alaska Nanuuq Commission (ANC) on December 17 and 18, 2012 in a 
co-management meeting. In March 2013, Shell revised its 2013 program to 
suspend plans for drilling, delete the proposed geotechnical program 
entirely, and remove survey activities from the Beaufort Sea. As a 
result, Shell has revised the proposed open-water marine surveys 
program for 2013, thereby necessitating the additional community 
meetings that were held this spring in Chukchi Sea villages to present 
changes to the 2013 season. Shell conducted these POC meetings in 
Chukchi Sea villages May 20-29, 2013. Shell submitted a final POC to 
NMFS on June 17, 2013.
    Following the 2013 season, Shell intends to have a post-season co-
management meeting with the commissioners and committee heads to 
discuss results of mitigation measures and outcomes of the preceding 
season. The goal of the post-season meeting is to build upon the 
knowledge base, discuss successful or unsuccessful outcomes of 
mitigation measures, and possibly refine plans or mitigation measures 
if necessary.
    In addition, Shell signed the 2013 Conflict Avoidance Agreement 
(CAA) with the Alaska subsistence whaling communities to ensure no 
unmitigable impacts to subsistence whaling from its proposed open-water 
marine survey activities in the Chukchi Sea.

Mitigation Conclusions

    NMFS has carefully evaluated these mitigation measures and 
considered a range of other measures in the context of ensuring that 
NMFS prescribes the means of effecting the least practicable 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:
     The manner in which, and the degree to which, the 
successful implementation of the measure is expected to minimize 
adverse impacts to marine mammals;
     The proven or likely efficacy of the specific measure to 
minimize adverse impacts as planned; and
     the practicability of the measure for applicant 
implementation.
    Based on our evaluation of the applicant's proposed measures, as 
well as other measures considered by NMFS, NMFS has determined that the 
mitigation measures provide the means of effecting the least 
practicable impact on marine mammal species or stocks and their 
habitat, paying particular attention to rookeries, mating grounds, and 
areas of similar significance.

Monitoring and Reporting Measures

    In order to issue an ITA for an activity, Section 101(a)(5)(D) of 
the MMPA states that NMFS must set forth ``requirements pertaining to 
the monitoring and reporting of such taking''. The MMPA implementing 
regulations at 50 CFR 216.104(a)(13) indicate that requests for ITAs 
must include the suggested means of accomplishing the necessary 
monitoring and reporting that will result in increased knowledge of the 
species and of the level of taking or impacts on populations of marine 
mammals that are expected to be present in the proposed action area.

I. Monitoring Measures

    Monitoring will provide information on the numbers of marine 
mammals potentially affected by the exploration operations and 
facilitate real time mitigation to prevent injury of marine mammals by 
industrial sounds or activities. These goals will be accomplished in 
the Chukchi Sea during 2013 by conducting vessel-based monitoring from 
all ships with sound sources and an acoustic monitoring program to 
document underwater sounds and the vocalizations of marine mammals in 
the region. The following monitoring measures are required for Shell's 
2013 open-water marine surveys in the Chukchi Sea.

[[Page 47517]]

    Visual monitoring by Protected Species Observers (PSOs) during 
active marine survey operations, and periods when these surveys are not 
occurring, will provide information on the numbers of marine mammals 
potentially affected by these activities and facilitate real time 
mitigation to prevent impacts to marine mammals by industrial sounds or 
operations. Vessel-based PSOs onboard the survey vessel will record the 
numbers and species of marine mammals observed in the area and any 
observable reaction of marine mammals to the survey activities in the 
Chukchi Sea. Additionally, monitoring by PSOs aboard the vessel 
utilized for equipment recovery and maintenance activities at the 
Burger A well site will ensure that there are no interactions between 
marine mammals and these operations. PSOs aboard the vessel will 
monitor adjacent areas while the vessel operates from a stationary 
position in DP mode.
    The acoustics monitoring program will characterize the sounds 
produced by marine surveys and will document the potential reactions of 
marine mammals in the area to those sounds and activities. Recordings 
of ambient sound levels and vocalizations of marine mammals along the 
Chukchi Sea coast and offshore will also be used to interpret potential 
impacts to marine mammals around the marine survey and equipment 
recovery and maintenance activity, in addition to subsistence use areas 
closer to shore. Although these monitoring programs were designed 
primarily to understand the impacts of exploratory drilling in the 
Chukchi Sea they will also provide valuable information about the 
potential impacts of the 2013 marine surveys on marine mammals in the 
area.

Visual-Based Protected Species Observers (PSOs)

    The visual-based marine mammal monitoring will be implemented by a 
team of experienced PSOs, including both biologists and Inupiat 
personnel. PSOs will be stationed aboard the marine survey vessel and 
the vessel used to facilitate equipment recovery and maintenance work 
at the Burger A exploratory well site through the duration of the 
projects. The vessel-based marine mammal monitoring will provide the 
basis for real-time mitigation measures as discussed in the Mitigation 
Measures section. In addition, monitoring results of the vessel-based 
monitoring program will include the estimation of the number of 
``takes'' as stipulated in the IHA.
(1) Protected Species Observers
    Vessel-based monitoring for marine mammals will be done by trained 
PSOs throughout the period of survey activities. The observers will 
monitor the occurrence of marine mammals near the survey vessel during 
all daylight periods during operation, and during most daylight periods 
when operations are not occurring. PSO duties will include watching for 
and identifying marine mammals; recording their numbers, distances, and 
reactions to the survey operations; and documenting ``take by 
harassment''.
    A sufficient number of PSOs will be required onboard the survey 
vessel to meet the following criteria:
     100% monitoring coverage during all periods of survey 
operations in daylight;
     maximum of 4 consecutive hours on watch per PSO; and
     maximum of ~12 hours of watch time per day per PSO.
    PSO teams will consist of Inupiat observers and experienced field 
biologists. An experienced field crew leader will supervise the PSO 
team onboard the survey vessel. The total number of PSOs may decrease 
later in the season as the duration of daylight decreases.
(2) Observer Qualifications and Training
    Crew leaders and most PSOs will be individuals with experience as 
observers during recent seismic, site clearance and shallow hazards, 
and other monitoring projects in Alaska or other offshore areas in 
recent years.
    Biologist-observers will have previous marine mammal observation 
experience, and field crew leaders will be highly experienced with 
previous vessel-based marine mammal monitoring and mitigation projects. 
Resumes for those individuals will be provided to NMFS for review and 
acceptance of their qualifications. Inupiat observers will be 
experienced in the region and familiar with the marine mammals of the 
area. All observers will complete a NMFS-approved observer training 
course designed to familiarize individuals with monitoring and data 
collection procedures. A marine mammal observers' handbook, adapted for 
the specifics of the planned survey program will be prepared and 
distributed beforehand to all PSOs (see below).
    PSOs will complete a two or three-day training and refresher 
session on marine mammal monitoring, to be conducted shortly before the 
anticipated start of the 2013 open-water season. Any exceptions will 
have or receive equivalent experience or training. The training 
session(s) will be conducted by qualified marine mammalogists with 
extensive crew-leader experience during previous vessel-based seismic 
monitoring programs.
(3) PSO Handbook
    A PSO's Handbook will be prepared for Shell's 2013 vessel-based 
monitoring program. Handbooks contain maps, illustrations, and 
photographs, as well as text, and are intended to provide guidance and 
reference information to trained individuals who will participate as 
PSOs. The following topics will be covered in the PSO Handbook for the 
Shell project:
     Summary overview descriptions of the project, marine 
mammals and underwater noise, the marine mammal monitoring program 
(vessel roles, responsibilities), and the Marine Mammal Protection Act;
     Monitoring and mitigation objectives and procedures, 
including radii for exclusion zones;
     Responsibilities of staff and crew regarding the marine 
mammal monitoring plan;
     Instructions for ship crew regarding the marine mammal 
monitoring plan;
     Data recording procedures: codes and coding instructions, 
PSO coding mistakes, electronic database; navigational, marine 
physical, field data sheet;
     List of species that might be encountered: identification, 
natural history;
     Use of specialized field equipment (reticle binoculars, 
NVDs, etc.);
     Reticle binocular distance scale;
     Table of wind speed, Beaufort wind force, and sea state 
codes; and
     Data quality-assurance/quality-control, delivery, storage, 
and backup procedures.

Marine Mammal Observer Protocol

    The PSOs will watch for marine mammals from the best available 
vantage point on the survey vessels, typically the bridge. The PSOs 
will scan systematically with the unaided eye and 7 x 50 reticle 
binoculars, supplemented with 20 x 60 image-stabilized Zeiss Binoculars 
or Fujinon 25 x 150 ``Big-eye'' binoculars, and night-vision equipment 
when needed. Personnel on the bridge will assist the marine mammal 
observer(s) in watching for marine mammals.
    PSOs aboard the stationary vessel used to conduct equipment 
recovery and maintenance activity will focus their attention on areas 
immediately adjacent to the vessel and where active operations are 
occurring to ensure these areas are clear of marine mammals and

[[Page 47518]]

that there are no direct interactions between animals and equipment or 
project personnel. The observer(s) aboard the marine survey vessel will 
give particular attention to the areas within the marine mammal 
exclusion zones around the source vessel. These zones are the maximum 
distances within which received levels may exceed 180 dB (rms) re 1 
[mu]Pa (rms) for cetaceans, or 190 dB (rms) re 1 [mu]Pa for other 
marine mammals. Information to be recorded by PSOs will include the 
same types of information that were recorded during recent monitoring 
programs associated with Industry activity in the Arctic (e.g., Ireland 
et al. 2009; Reiser et al. 2010, 2011). When a mammal sighting is made, 
the following information about the sighting will be recorded:
     Species, group size, age/size/sex categories, behavior 
when first sighted and after initial sighting, heading, bearing and 
distance from observer, apparent reaction to activities (e.g., none, 
avoidance, approach, paralleling, etc.), closest point of approach, and 
pace.
     Time, location, speed, and activity of the vessel, sea 
state, ice cover, visibility, and sun glare.
     The positions of other vessel(s) in the vicinity of the 
observer location.
    Distances to nearby marine mammals will be estimated with 
binoculars (Fujinon 7 x 50 binoculars) containing a reticle to measure 
the vertical angle of the line of sight to the animal relative to the 
horizon. Observers may use a laser rangefinder to test and improve 
their abilities for visually estimating distances to objects in the 
water.
    When a marine mammal is seen approaching or within the exclusion 
zone applicable to that species, the marine survey crew will be 
notified immediately so that mitigation measures called for in the 
applicable authorization(s) can be implemented.
    Night-vision equipment (Generation 3 binocular image intensifiers 
or equivalent units) will be available for use when/if needed. Past 
experience with night-vision devices (NVDs) in the Chukchi Sea and 
elsewhere has indicated that NVDs are not nearly as effective as visual 
observation during daylight hours (e.g., Harris et al. 1997, 1998; 
Moulton and Lawson 2002).

Field Data-Recording, Verification, Handling, and Security

    PSOs will record their observations directly into computers running 
a custom designed software package. Paper datasheets will be available 
as backup if necessary. The accuracy of the data entry will be verified 
in the field by computerized validity checks as the data are entered, 
and by subsequent manual checking of the database printouts. These 
procedures will allow initial summaries of data to be prepared during 
and shortly after the field season, and will facilitate transfer of the 
data to statistical, graphical or other programs for further 
processing. Quality control of the data will be facilitated by (1) the 
start-of-season training session, (2) subsequent supervision by the 
onboard field crew leader, and (3) ongoing data checks during the field 
season.
    The data will be sent off of the ship to Anchorage each day (if 
possible) and backed up regularly onto CDs and/or USB disks, and stored 
at separate locations on the vessel. If possible, data sheets will be 
photocopied daily during the field season. Data will be secured further 
by having data sheets and backup data CDs carried back to the Anchorage 
office during crew rotations.

Passive Acoustic Monitoring

(1) Sound Source Measurements
    The objectives of the sound source measurements planned for 2013 
will be (1) to measure the distances at which broadband received levels 
reach 190, 180, 170, 160, and 120 dB (rms) re 1 [mu]Pa during marine 
surveys and equipment recovery and maintenance activity at the Burger A 
exploratory well site, and from vessels used during these activities. 
The measurements of airguns and other marine survey equipment will be 
made by an acoustics contractor at the beginning of the surveys. Data 
from survey equipment will be previewed in the field immediately after 
download from the hydrophone instruments. An initial sound source 
analysis will be supplied to NMFS and the vessel within 120 hours of 
completion of the measurements, if possible. The report will indicate 
the distances to sound levels based on fits of empirical transmission 
loss formulae to data in the endfire and broadside directions. A more 
detailed report will be provided to NMFS as part of the 90-day report 
following completion of the acoustic program.
(2) Long-Term Acoustic Monitoring
    Acoustic studies that were undertaken from 2006 through 2012 in the 
Chukchi Sea as part of the Joint Monitoring Program will be continued 
by Shell during its proposed open-water marine survey and equipment 
recovery and maintenance activity in 2013. The acoustic ``net'' array 
used during the 2006-2012 field seasons in the Chukchi Sea was designed 
to accomplish two main objectives. The first was to collect information 
on the occurrence and distribution of marine mammals (including beluga 
whale, bowhead whale, walrus and other species) that may be available 
to subsistence hunters near villages located on the Chukchi Sea coast 
and to document their relative abundance, habitat use, and migratory 
patterns. The second objective was to measure the ambient soundscape 
throughout the eastern Chukchi Sea and to record received levels of 
sounds from industry and other activities further offshore in the 
Chukchi Sea.
    The basic components of this effort consist of autonomous acoustic 
recorders deployed widely across the US Chukchi Sea through the open 
water season and then the winter season. These precisely calibrated 
systems will sample at 16 kHz with 24-bit resolution, and are capable 
of recording marine mammal sounds and making anthropogenic noise 
measurements. The net array configuration will include a regional array 
of 24 Autonomous Multichannel Acoustic Recorders (AMAR) deployed July-
October off the four main transect locations: Cape Lisburne, Point 
Hope, Wainwright and Barrow. These will be augmented by six AMARs 
deployed August 2013-August 2014 at Hanna Shoal. Six additional AMAR 
recorders will be deployed in a hexagonal geometry at 16 km from the 
nominal Burger A exploratory well location to monitor directional 
variations of equipment recovery/maintenance and support vessel sounds 
in addition to examining marine mammal vocalization patterns in the 
vicinity of these activities. One new recorder will be placed 32 km 
northwest of the Burger A well site to monitor for sound propagation 
toward the south side of Hanna Shoal, which acoustic and satellite tag 
monitoring has identified as frequented by walrus in August. Marine 
survey activities will occur in areas within the coverage of the net 
array. All of these offshore systems will capture marine survey and 
equipment recovery/maintenance sounds, where present, over large 
distances to help characterize the sound transmission properties in the 
Chukchi Sea. They will continue to provide a large amount of 
information related to marine mammal distributions in the Chukchi Sea.
    In early October, all of the regional recorders will be retrieved 
except for the six Hanna Shoal recorders, which will continue to record 
on a duty cycle until August 2014. An additional set of nine Aural 
winter recorders will be deployed at the same time at the same 
locations that were instrumented in winter 2012-2013. These recorders 
will sample at 16

[[Page 47519]]

kHz on a 17% duty cycle (40 minutes every 4 hours). The winter 
recorders deployed in previous years have provided important 
information about bowhead, beluga, walrus and several seal species 
migrations in fall and spring.

Monitoring Plan Peer Review

    The MMPA requires that monitoring plans be independently peer 
reviewed ``where the proposed activity may affect the availability of a 
species or stock for taking for subsistence uses'' (16 U.S.C. 
1371(a)(5)(D)(ii)(III)). Regarding this requirement, NMFS' implementing 
regulations state, ``Upon receipt of a complete monitoring plan, and at 
its discretion, [NMFS] will either submit the plan to members of a peer 
review panel for review or within 60 days of receipt of the proposed 
monitoring plan, schedule a workshop to review the plan'' (50 CFR 
216.108(d)).
    NMFS convened an independent peer review panel to review Shell's 
mitigation and monitoring plan in its IHA application for taking marine 
mammals incidental to the proposed open-water marine surveys and 
equipment recovery and maintenance in the Chukchi Sea during 2013. The 
panel met on January 8 and 9, 2013, and provided their final report to 
NMFS on March 5, 2013. The full panel report can be viewed at: http://www.nmfs.noaa.gov/pr/permits/incidental.htm#applications.
    NMFS provided the panel with Shell's monitoring and mitigation plan 
and asked the panel to address the following questions and issues for 
Shell's plan:
     Will the applicant's stated objectives effectively further 
the understanding of the impacts of their activities on marine mammals 
and otherwise accomplish the goals stated below? If not, how should the 
objectives be modified to better accomplish the goals above?
     Can the applicant achieve the stated objectives based on 
the methods described in the plan?
     Are there technical modifications to the proposed 
monitoring techniques and methodologies proposed by the applicant that 
should be considered to better accomplish their stated objectives?
     Are there techniques not proposed by the applicant (i.e., 
additional monitoring techniques or methodologies) that should be 
considered for inclusion in the applicant's monitoring program to 
better accomplish their stated objectives?
     What is the best way for an applicant to present their 
data and results (formatting, metrics, graphics, etc.) in the required 
reports that are to be submitted to NMFS (i.e., 90-day report and 
comprehensive report)?
    The peer review panel report contains recommendations that the 
panel members felt were applicable to the Shell's monitoring plans. 
Overall the panel feels that the proposed methods for visual monitoring 
are adequate and appropriate as the primary means of assessing the 
acute near-field impacts of the proposed marine surveys. The panel also 
cautions that there should be realistic expectations regarding the 
limitations of these surveys to provide scientific-level measurements 
of distribution and density, but in terms of meeting the monitoring 
requirements, the panel finds the proposed methods adequate and 
appreciate the improvements and modifications (e.g., in terms of PSO 
training, field data collection methods) made over the past few years. 
Nevertheless, the panel also provides several recommendations 
concerning improving night-time monitoring, passive acoustic 
monitoring, and data analysis and presentation.
    NMFS has reviewed the report and evaluated all recommendations made 
by the panel. NMFS has determined that there are several measures that 
Shell can incorporate into its 2013 open-water marine surveys and 
equipment recovery and maintenance program. Additionally, there are 
other recommendations that NMFS has determined would also result in 
better data collection, and could potentially be implemented by oil and 
gas industry applicants, but which likely could not be implemented for 
the 2013 open-water season due to time constrains for this season. 
While it may not be possible to implement those changes this year, NMFS 
believes that they are worthwhile and appropriate suggestions that may 
require a bit more time to implement, and Shell should consider 
incorporating them into future monitoring plans should Shell decide to 
apply for IHAs in the future.
    The following subsections lay out measures that NMFS recommends for 
implementation as part of the 2013 open-water marine surveys and 
equipment recovery and maintenance program by Shell (and incorporates 
into the IHA) and, separately, those that are recommended for future 
programs.

Included in the 2013 Monitoring Plan

    The peer review panel's report contains several recommendations 
regarding visual monitoring during low-visibility and presentation of 
data in reports, which NMFS agrees that Shell should incorporate and 
included in the IHA:
(1) Visual monitoring during low-visibility
     Shell should use the best available technology to improve 
detection capability during periods of fog and other types of inclement 
weather. Such technology might include night-vision goggles or 
binoculars as well as other instruments that incorporate infrared 
technology; presently the efficacy of these technologies appears 
limited but the panel and NMFS encourage continued consideration of 
their applicability as it continues to evolve.
(2) Data analysis and presentation
     Shell should apply appropriate statistical procedures for 
probability estimation of marine mammals missed, based on observational 
data acquired during some period of time before and after night or fog 
events.
     Shell should provide useful summaries and interpretations 
of results of the various elements of the monitoring results. A clear 
timeline and spatial (map) representation/summary of operations and 
important observations should be given. Any and all mitigation measures 
(e.g., vessel course deviations for animal avoidance, operational shut 
down) should be summarized. Additionally, an assessment of the efficacy 
of monitoring methods should be provided.
    In addition to these recommendations, Shell also agrees to produce 
a weekly GIS application that would be available on the web for 
regulators to view for every observation and mitigation measure 
implemented.

Recommendations to be Partially Implemented or Considered for Future 
Monitoring Plans

    In addition, the panelists recommended that:
     Shell should integrate the acoustic information from the 
net array to the greatest extent possible to assess the aggregate known 
activities, at least those from Shell operations but more broadly as 
possible, to assess patterns of marine mammal vocal activities and how 
that might be used to investigate potentially broader impacts from 
overlapping/interacting activities.
     Shell should consider integration of visual and acoustic 
data from the Chukchi monitoring program and the Joint Monitoring 
Program to produce estimates of bowhead, beluga, and walrus density 
using methods developed in the Density Estimation for Cetacean from 
Passive Acoustic Fixed Sensors (DECAF) project by the Center

[[Page 47520]]

for Research into Ecological and Environmental Modeling (CREEM) at the 
University of St. Andrews in Scotland.
    After discussion with Shell, NMFS decided not to implement these 
two recommendations in full during Shell's 2013 open-water marine 
surveys and equipment recovery and maintenance program because the 
systematic and comprehensive analyses of these acoustic datasets would 
require far more time and effort than what would be needed to assess 
marine mammal takes under the MMPA. However, Shell agrees that it will 
provide data from net arrays supported in part, or in whole, by Shell 
and will participate in the integration of acoustic arrays to assess 
the sound field of the lease areas in the Chukchi and Beaufort seas for 
the purposes of assessing patterns of marine mammal distribution and 
behavior and for assessing the impacts of multiple activities/factors. 
In addition, Shell will evaluate the potential of the DECAF project and 
efforts will be made to assess the applicability of the data collection 
infrastructure established in the Shell monitoring program to these and 
similar studies.

II. Reporting Measures

Sound Source Verification Reports

    A report on the preliminary results of the sound source 
verification measurements, including the measured 190, 180, 160, and 
120 dB (rms) radii of the airgun sources, will be submitted within 14 
days after collection of those measurements at the start of the field 
season. This report will specify the distances of the exclusion zones 
that were adopted for the survey.

Field Reports

    Throughout the survey program, PSOs will prepare a report each day 
or at such other intervals, summarizing the recent results of the 
monitoring program. The reports will summarize the species and numbers 
of marine mammals sighted. These reports will be provided to NMFS and 
to the survey operators.

Technical Reports

    The results of Shell's 2013 vessel-based monitoring, including 
estimates of ``take'' by harassment, will be presented in the ``90-
day'' and Final Technical reports. The Technical Reports should be 
submitted to NMFS within 90 days after the end of the seismic survey. 
The Technical Reports will include:
    (a) summaries of monitoring effort (e.g., total hours, total 
distances, and marine mammal distribution through the study period, 
accounting for sea state and other factors affecting visibility and 
detectability of marine mammals);
    (b) analyses of the effects of various factors influencing 
detectability of marine mammals (e.g., sea state, number of observers, 
and fog/glare);
    (c) species composition, occurrence, and distribution of marine 
mammal sightings, including date, water depth, numbers, age/size/gender 
categories (if determinable), group sizes, and ice cover;
    (d) To better assess impacts to marine mammals, data analysis 
should be separated into periods when a seismic airgun array (or a 
single mitigation airgun) is operating and when it is not. Final and 
comprehensive reports to NMFS should summarize and plot:
     Data for periods when a seismic array is active and when 
it is not; and
     The respective predicted received sound conditions over 
fairly large areas (tens of km) around operations;
    (e) sighting rates of marine mammals during periods with and 
without airgun activities (and other variables that could affect 
detectability), such as:
     Initial sighting distances versus airgun activity state;
     closest point of approach versus airgun activity state;
     observed behaviors and types of movements versus airgun 
activity state;
     numbers of sightings/individuals seen versus airgun 
activity state;
     distribution around the survey vessel versus airgun 
activity state; and
     estimates of take by harassment;
    (f) Reported results from all hypothesis tests should include 
estimates of the associated statistical power when practicable;
    (g) Estimate and report uncertainty in all take estimates. 
Uncertainty could be expressed by the presentation of confidence 
limits, a minimum-maximum, posterior probability distribution, etc.; 
the exact approach would be selected based on the sampling method and 
data available;
    (h) The report should clearly compare authorized takes to the level 
of actual estimated takes; and

Notification of Injured or Dead Marine Mammals

    In addition, NMFS would require Shell to notify NMFS' Office of 
Protected Resources and NMFS' Stranding Network within 48 hours of 
sighting an injured or dead marine mammal in the vicinity of marine 
survey operations. Shell shall provide NMFS with the species or 
description of the animal(s), the condition of the animal(s) (including 
carcass condition if the animal is dead), location, time of first 
discovery, observed behaviors (if alive), and photo or video (if 
available).
    In the event that an injured or dead marine mammal is found by 
Shell that is not in the vicinity of the proposed open-water marine 
survey program, Shell would report the same information as listed above 
as soon as operationally feasible to NMFS.

Estimated Take by Incidental Harassment

    Except with respect to certain activities not pertinent here, the 
MMPA defines ``harassment'' as: any act of pursuit, torment, or 
annoyance which (i) has the potential to injure a marine mammal or 
marine mammal stock in the wild [Level A harassment]; or (ii) has the 
potential to disturb a marine mammal or marine mammal stock in the wild 
by causing disruption of behavioral patterns, including, but not 
limited to, migration, breathing, nursing, breeding, feeding, or 
sheltering [Level B harassment]. Only take by Level B behavioral 
harassment is anticipated as a result of the proposed open water marine 
survey program. Anticipated impacts to marine mammals are associated 
with noise propagation from the survey airgun(s) used in the shallow 
hazards survey.
    The full suite of potential impacts to marine mammals was described 
in detail in the ``Potential Effects of the Specified Activity on 
Marine Mammals'' section found earlier in this document. The potential 
effects of sound from the proposed open water marine survey programs 
might include one or more of the following: masking of natural sounds; 
behavioral disturbance; non-auditory physical effects; and, at least in 
theory, temporary or permanent hearing impairment (Richardson et al. 
1995). As discussed earlier in this document, the most common impact 
will likely be from behavioral disturbance, including avoidance of the 
ensonified area or changes in speed, direction, and/or diving profile 
of the animal. For reasons discussed previously in this document, 
hearing impairment (TTS and PTS) is highly unlikely to occur based on 
the required mitigation and monitoring measures that would preclude 
marine mammals from being exposed to noise levels high enough to cause 
hearing impairment.
    For impulse sounds, such as those produced by airgun(s) used in the 
site clearance and shallow hazards surveys, NMFS uses the 160 dB (rms) 
re 1 [mu]Pa isopleth to indicate the onset of Level B harassment. For 
non-impulse sounds, such as those produced by vessel's DP thrusters 
during the proposed

[[Page 47521]]

equipment recovery and maintenance program, NMFS uses the 120 dB (rms) 
re 1 [mu]Pa isopleth to indicate the onset of Level B harassment. Shell 
provided calculations for both the 160- and 120-dB isopleths produced 
by these activities and then used those isopleths to estimate takes by 
harassment. NMFS used the calculations to make the necessary MMPA 
findings. Shell provided a full description of the methodology used to 
estimate takes by harassment in its IHA application, which is also 
provided in the following sections.

Basis for Estimating ``Take by Harassment''

    The estimated takes by harassment is calculated in this section by 
multiplying the expected densities of marine mammals that may occur 
near the planned activities by the area of water likely to be exposed 
to impulse sound levels of >=160 dB (rms) re 1 [mu]Pa and non-impulse 
sound levels >=120 dB (rms) re 1 [mu]Pa.
    Marine mammal occurrence near the operation is likely to vary by 
season and habitat, mostly related to the presence or absence of sea 
ice. Although current NMFS' noise exposure standards state that Level B 
harassment occurs at exposure levels >=160 dB (rms) re 1 [mu]Pa by 
impulse sources and exposure levels >=120 dB (rms) re 1 [mu]Pa by non-
impulse sources, there is no evidence that avoidance at these received 
sound levels would have significant biological effects on individual 
animals. Any changes in behavior caused by sounds at or near the 
specified received levels would likely fall within the normal variation 
in such activities that would occur in the absence of the planned 
operations. However, these received levels are currently used to set 
the threshold for Level B behavioral harassment.

Marine Mammal Density Estimates

    Marine mammal density estimates in the Chukchi Sea have been 
derived for two time periods, the summer period covering July and 
August, and the fall period including September and October. Animal 
densities encountered in the Chukchi Sea during both of these time 
periods will further depend on the habitat zone within which the 
operations are occurring: open water or ice margin. Vessel and 
equipment limitations will result in very little activity occurring in 
or near sea ice; however, if ice is present near the areas of activity 
some sounds produced by the activities may remain above disturbance 
threshold levels in ice margin habitats. Therefore, open water 
densities have been used to estimate potential ``take by harassment'' 
in 90 percent of the area expected to be ensonified above disturbance 
thresholds while ice margin densities have been used in the remaining 
10 percent of the ensonified area.
    For a few marine mammal species, several density estimates were 
available. In those cases, the mean and maximum estimates were 
determined from the reported densities or survey data. In other cases, 
no applicable estimate was available, so correction factors were used 
to arrive density estimates. These are described in detail in the 
following sections.
    Detectability bias, quantified in part by f(0), is associated with 
diminishing sightability with increasing lateral distance from the 
survey trackline. Availability bias, g(0), refers to the fact that 
there is <100 percent probability of sighting an animal that is present 
along the survey trackline.
    Nine cetacean and four pinniped species under NMFS jurisdiction are 
known to occur in the planned project area in the Chukchi Sea. Five of 
them (bowhead, fin, and humpback whales, and ringed and bearded seals) 
are listed as ``endangered'' or ``threatened'' under the ESA.
(1) Beluga Whale
    Summer densities of belugas in offshore waters are expected to be 
low, with somewhat higher densities in ice-margin and nearshore areas. 
Aerial surveys have recorded few belugas in the offshore Chukchi Sea 
during the summer months (Moore et al. 2000). Aerial surveys of the 
Chukchi Sea in 2008-2009 flown by the National Marine Mammal Laboratory 
(NMML) as part of the Chukchi Offshore Monitoring in Drilling Area 
(COMIDA) project have only reported 5 beluga sightings during >8,700 mi 
(>14,000 km) of on-transect effort, only 2 of which were offshore 
(COMIDA 2009). One of the three nearshore sightings was of a large 
group (~275 individuals on July 12, 2009) of migrating belugas along 
the coastline just north of Peard Bay. Additionally, only one beluga 
sighting was recorded during >49,710 mi (>80,000 km) of visual effort 
during good visibility conditions from industry vessels operating in 
the Chukchi Sea in September-October of 2006-2010 (Hartin et al. 2011). 
If belugas are present during the summer, they are more likely to occur 
in or near the ice edge or close to shore during their northward 
migration. Expected densities have previously been calculated from data 
in Moore et al. (2000). However, more recent data from COMIDA aerial 
surveys during 2008-2010 are now available (Clarke and Ferguson in 
prep.). Effort and sightings reported by Clarke and Ferguson (in prep.) 
were used to calculate the average open-water density estimate. Clarke 
and Ferguson (in prep) reported two on-transect beluga sightings (5 
individuals) during 11,985 km of on-transect effort in waters 36-50 m 
deep in the Chukchi Sea during July and August. The mean group size of 
these two sightings is 2.5. A f(0) value of 2.841 and g(0) value of 
0.58 from Harwood et al. (1996) were also used in the density 
calculation. Specific data on the relative abundance of beluga in open-
water versus ice-margin habitat during the summer in the Chukchi Sea is 
not available. However, belugas are commonly associated with ice, so an 
inflation factor of 4 was used to estimate the average ice-margin 
density from the open-water density. Very low densities observed from 
vessels operating in the Chukchi Sea during non-seismic periods and 
locations in July-August of 2006-2010 (0.0-0.0003/mi\2\, 0.0-0.0001/
km2; Hartin et al. 2011), also suggest the number of beluga whales 
likely to be present near the planned activities will not be large.
    In the fall, beluga whale densities offshore in the Chukchi Sea are 
expected to be somewhat higher than in the summer because individuals 
of the eastern Chukchi Sea stock and the Beaufort Sea stock will be 
migrating south to their wintering grounds in the Bering Sea (Allen and 
Angliss 2012). Densities derived from survey results in the northern 
Chukchi Sea in Clarke and Ferguson (in prep) were used as the average 
density for open-water fall season estimates. Clarke and Ferguson (in 
prep) reported 3 beluga sightings (6 individuals) during 10,036 km of 
on-transect effort in water depths 36-50 m. The mean group size of 
those three sightings is 2. A f(0) value of 2.841 and g(0) value of 
0.58 from Harwood et al. (1996) were used in the calculation. Moore et 
al. (2000) reported lower than expected beluga sighting rates in open-
water during fall surveys in the Beaufort and Chukchi seas, so an 
inflation value of 4 was used to estimate the average ice-margin 
density from the open-water density. Based on the few beluga sightings 
from vessels operating in the Chukchi Sea during non-seismic periods 
and locations in September-November of 2006-2010 (Hartin et al. 2011), 
the relatively low densities are consistent with what is likely to be 
observed from vessels during the planned operations.
(2) Bowhead Whale
    By July, most bowhead whales are northeast of the Chukchi Sea, 
within or

[[Page 47522]]

migrating toward their summer feeding grounds in the eastern Beaufort 
Sea. No bowheads were reported during 6,640 mi (10,686 km) of on-
transect effort in the Chukchi Sea by Moore et al. (2000). Aerial 
surveys in 2008-2010 by the NMML as part of the COMIDA project reported 
only 6 sightings during >16,020 mi (>25,781 km) of on-transect effort 
(Clarke and Ferguson in prep). Two of the six sightings were in waters 
<=35 m deep and the remaining four sightings were in waters 51-200 m 
deep. Bowhead whales were also rarely sighted in July-August of 2006-
2010 during aerial surveys of the Chukchi Sea coast (Thomas et al. 
2011). This is consistent with movements of tagged whales, all of which 
moved through the Chukchi Sea by early May 2009, and tended to travel 
relatively close to shore, especially in the northern Chukchi Sea. The 
estimate of bowhead whale density in the Chukchi Sea was calculated by 
assuming there was one bowhead sighting during the 7,447 mi (11,985 km) 
of survey effort in waters 36-50 m deep in the Chukchi Sea during July-
August reported in Clarke and Ferguson (in prep), although no bowheads 
were actually observed during those surveys. The mean group size from 
September-October sightings reported in Clarke and Ferguson (in prep) 
is 1.1, and this was also used in the calculation of summer densities. 
The group size value, along with a f(0) value of 2 and a g(0) value of 
0.07, both from Thomas et al. (2002) were used to estimate a summer 
density of bowhead whales. Bowheads are not expected to be encountered 
in higher densities near ice in the summer (Moore et al. 2000), so the 
same density estimates are used for open-water and ice-margin habitats. 
Densities from vessel based surveys in the Chukchi Sea during non-
seismic periods and locations in July-August of 2006-2010 (Hartin et 
al. 2011) ranged from 0.0005-0.0021/mi\2\ (0.0002-0.0008/km\2\).
    During the fall, bowhead whales that summered in the Beaufort Sea 
and Amundsen Gulf migrate west and south to their wintering grounds in 
the Bering Sea making it more likely that bowheads will be encountered 
in the Chukchi Sea at this time of year. Moore et al. (2000) reported 
34 bowhead sightings during 27,560 mi (44,354 km) of on-transect survey 
effort in the Chukchi Sea during September-October. Thomas et al. 
(2011) also reported increased sightings on coastal surveys of the 
Chukchi Sea during October and November of 2006-2010. GPS tagging of 
bowheads appear to show that migration routes through Chukchi Sea are 
more variable than through the Beaufort Sea (Quakenbush et al. 2010). 
Some of the routes taken by bowheads remain well north of the planned 
marine survey activities while others have passed near to or through 
the area. Kernel densities estimated from GPS locations of whales 
suggest that bowheads do not spend much time (e.g., feeding or resting) 
in the north-central Chukchi Sea near the area of planned activities 
(Quakenbush et al. 2010). Clarke and Ferguson (in prep) reported 14 
sightings (15 individuals) during 10,036 km of on transect aerial 
survey effort in 2008-2010. The mean group size of those sightings is 
1.1. The same f(0) and g(0) values that were used for the summer 
estimates above were used for the fall estimates. Moore et al. (2000) 
found that bowheads were detected more often than expected in 
association with ice in the Chukchi Sea in September-October, so a 
density of twice the average open-water density was used as the average 
ice-margin density. Densities from vessel based surveys in the Chukchi 
Sea during non-seismic periods and locations in September-November of 
2006-2010 (Hartin et al. 2011) ranged from 0.0008 to 0.0135/mi\2\ 
(0.0003-0.0052/km\2\). This suggests the densities used in the 
calculations are somewhat higher than are likely to be observed from 
vessels near the areas of planned operations.
(3) Gray Whale
    Gray whale densities are expected to be much higher in the summer 
months than during the fall. Moore et al. (2000) found the distribution 
of gray whales in the planned operational area was scattered and 
limited to nearshore areas where most whales were observed in water 
less than 114 ft (35 m) deep. Thomas et al. (2011) also reported 
substantial declines in the sighting rates of gray whales in the fall. 
The average open-water summer density was calculated from 2008-2010 
aerial survey effort and sightings in Clarke and Ferguson (in prep) for 
water depths 118-164 ft (36-50 m) including 54 sightings (73 
individuals) during 7,447 mi (11,985 km) of on-transect effort. The 
average group size of those sightings is 1.35. Correction factors f(0) 
= 2.49 (Forney and Barlow 1998) and g(0) = 0.30 (Forney and Barlow 
1998, Mallonee 1991) were also used in the density calculation. Gray 
whales are not commonly associated with sea ice, but may be present 
near it, so the same densities were used for ice-margin habitat as were 
derived for open-water habitat during both seasons. Densities from 
vessel based surveys in the Chukchi Sea during non-seismic periods and 
locations in July-August of 2006-2010 (Hartin et al. 2011) ranged from 
0.0021/mi\2\ to 0.0221/mi\2\ (0.0008/km\2\ to 0.0085/km\2\).
    In the fall, gray whales may be dispersed more widely through the 
northern Chukchi Sea (Moore et al. 2000), but overall densities are 
likely to be decreasing as the whales begin migrating south. A density 
calculated from effort and sightings (15 sightings [19 individuals] 
during 6,236 mi (10,036 km) of on-transect effort) in water 118-164 ft 
(36-50 m) deep during September-October reported by Clarke and Ferguson 
(in prep) was used as the average estimate for the Chukchi Sea during 
the fall period. The corresponding group size value of 1.26, along with 
the same f(0) and g(0) values described above were used in the 
calculation. Densities from vessel based surveys in the Chukchi Sea 
during non-seismic periods and locations in September-November of 2006-
2010 (Hartin et al. 2011) ranged from 0.0/mi\2\ to 0.0114/mi\2\ (0.0/
km\2\ to 0.0044/km\2\).
(4) Harbor Porpoise
    Harbor Porpoise densities were estimated from industry data 
collected during 2006-2010 activities in the Chukchi Sea. Prior to 
2006, no reliable estimates were available for the Chukchi Sea and 
harbor porpoise presence was expected to be very low and limited to 
nearshore regions. Observers on industry vessels in 2006-2010, however, 
recorded sightings throughout the Chukchi Sea during the summer and 
early fall months. Density estimates from 2006-2010 observations during 
non-seismic periods and locations in July-August ranged from 0.0034/
mi\2\ to 0.0075/mi\2\ (0.0013/km\2\ to 0.0029/km\2\) (Hartin et al. 
2011). The average density from the summer season of those three years 
(0.0057/mi\2\, 0.0022/km\2\) was used as the average open-water density 
estimate. Harbor porpoise are not expected to be present in higher 
numbers near ice, so the open-water densities were used for ice-margin 
habitat in both seasons. Harbor porpoise densities recorded during 
industry operations in the fall months of 2006-2010 were slightly lower 
and ranged from 0.0/mi\2\ to 0.0114/mi\2\ (0.0/km\2\ to 0.0044/km\2\). 
The average of those years (0.0055/mi\2\, 0.0021/km\2\) was again used 
as the average density estimate.
(5) Other Cetaceans
    The remaining five cetacean species that could be encountered in 
the Chukchi Sea during Shell's planned marine survey program include 
the humpback whale, killer whale, minke whale, fin whale, and narwhal. 
Although there is evidence of the occasional occurrence of these 
animals

[[Page 47523]]

in the Chukchi Sea, it is unlikely that more than a few individuals 
will be encountered during the planned marine survey activities. Clarke 
et al. (2011b) and Hartin et al. (2011) reported humpback whale 
sightings; George and Suydam (1998) reported killer whales; Brueggeman 
et al. (1990), Hartin et al. (2011) and COMIDA (2011) reported minke 
whales; and Clarke et al. (2011b) and Hartin et al. (2011) reported fin 
whales. Narwhal sightings in the Chukchi Sea have not been reported in 
recent literature, but subsistence hunters occasionally report 
observations near Barrow, and Reeves et al. (2002) indicated a small 
number of extralimital sightings in the Chukchi Sea.
(6) Ringed and Bearded Seals
    Ringed seal and bearded seals summer ice-margin densities were 
available in Bengtson et al. (2005) from spring surveys in the offshore 
pack ice zone of the northern Chukchi Sea. However, corrections for 
bearded seal availability, g(0), based on haulout and diving patterns 
were not available. Densities of ringed and bearded seals in open water 
are expected to be somewhat lower in the summer when preferred pack ice 
habitat may still be present in the Chukchi Sea. Average and maximum 
open-water densities have been estimated at \3/4\ of the ice margin 
densities during both seasons for both species. The fall density of 
ringed seals in the offshore Chukchi Sea has been estimated as \2/3\ 
the summer densities because ringed seals begin to reoccupy nearshore 
fast ice areas as it forms in the fall. Bearded seals may also begin to 
leave the Chukchi Sea in the fall, but less is known about their 
movement patterns so fall densities were left unchanged from summer 
densities. For comparison, the ringed seal density estimates calculated 
from data collected during summer 2006-2010 industry operations ranged 
from 0.0359/mi\2\ to 0.1206/mi\2\ (0.0138/km\2\ to 0.0464/km\2\) 
(Hartin et al. 2011). These estimates are lower than those made by 
Bengtson et al. (2005) which is not surprising given the different 
survey methods and timing.
(7) Spotted Seal
    Little information on spotted seal densities in offshore areas of 
the Chukchi Sea is available. Spotted seal densities in the summer were 
estimated by multiplying the ringed seal densities by 0.02. This was 
based on the ratio of the estimated Chukchi populations of the two 
species. Chukchi Sea spotted seal abundance was estimated by assuming 
that 8 percent of the Alaskan population of spotted seals is present in 
the Chukchi Sea during the summer and fall (Rugh et al. 1997), the 
Alaskan population of spotted seals is 59,214 (Allen and Angliss 2012), 
and that the population of ringed seals in the Alaskan Chukchi Sea is 
~208,000 animals (Bengtson et al. 2005). In the fall, spotted seals 
show increased use of coastal haulouts so densities were estimated to 
be \2/3\ of the summer densities.
(8) Ribbon Seals
    Four ribbon seal sightings were reported during industry vessel 
operations in the Chukchi Sea in 2006-2010 (Hartin et al. 2011). The 
resulting density estimate of 0.0013/mi\2\ (0.0007/km\2\) was used for 
both seasons and habitat zones.

Area Potentially Exposed to Sound Levels Above 160 dB During Site 
Clearance and Shallow Hazards Surveys

    As described earlier, Shell's proposed site clearance and shallow 
hazards surveys would occur in three survey areas of the Chukchi Sea 
Lease Area. These three survey areas are the Burger prospect (Survey 
Area 2), Crackerjack prospect (Survey Area 1), and an area northeast of 
Burger (Survey Area 3; Figure 1-2 of the IHA application). The precise 
survey sites within the survey areas at these prospects have not yet 
been determined, but there are five notional locations at Burger, three 
at Crackerjack, and one northeast of Burger. The five potential survey 
sites at Burger range in size from 23 km\2\ to 40 km\2\ (9 mi\2\ to 15 
mi\2\) while the three potential sites at Crackerjack range from 35 
km\2\ to 119 km\2\ (14 mi\2\ to 46 mi\2\). The single site northeast of 
Burger may be ~119 km\2\ (46 mi\2\).
    Shell plans to use the same 4 x 10 in\3\ airgun configuration that 
was used during site clearance and shallow hazards surveys in the 
Chukchi Sea in 2008 and 2009. Measurements during these two years 
occurred at three locations: Honeyguide (west of the Crackerjack 
prospect), Crackerjack, and Burger. The measurements showed that the 
Burger site had the largest radius from the source to the 160 dB (rms) 
re 1 [micro]Pa isopleths at 1,800 m. As a cautionary approach, the 
Burger site distance (1,800 m from the source) plus a 25 percent 
inflation factor (equaling 2,250 m) was used to estimate the total area 
that may be ensonified to 160 dB (rms) re 1 [micro]Pa by seismic sounds 
at all of the potential survey sites at any given time, which equals to 
15.9 km\2\.
    Shell's operations plan calls for site clearance and shallow 
hazards surveys to begin at the Burger prospect. Adding the 2.25 km 160 
dB (rms) radius to the perimeter of all five of the notional survey 
grids at that site results in a total area at Burger of 477 km\2\ being 
exposed to seismic sound >=160 dB (rms). This is approximately 40 
percent of the total area that may be exposed to seismic sounds during 
the survey activities and it has been attributed to the July-August 
period. Adding the 2.25 km 160 dB (rms) radius to the perimeter of the 
three notional survey areas at Crackerjack and the one northeast of 
Burger results in a total area of 826 km\2\ being potentially exposed 
to pulsed seismic sounds >=160 dB (rms). Since these areas would likely 
be surveyed after the Burger sites are completed they have been 
attributed to the September-October period. The total area potentially 
exposed is then 1,303 km\2\ (477 km\2\ + 826 km\2\).

Area Potentially Exposed to Sound Levels Above 120 dB During Equipment 
Recovery and Maintenance Program

    As described earlier, Shell's proposed equipment recovery and 
maintenance at the Burger A well site where drilling took place in 2012 
would involve a vessel engaging with DP thrusters while remotely 
operated vehicles or divers are used to perform the required work. 
Sounds produced by the vessel while in dynamic positioning mode will be 
non-impulse in nature and are thus evaluated at the >=120 dB (rms) 
level.
    The vessel from which equipment recovery and maintenance will be 
conducted has not yet been determined. Various sound measurements were 
conducted from vessels during DP operations and during drilling 
activities (which may include DP operations) in the Chukchi Sea in the 
past two years. Under most circumstances, sounds from dynamic 
positioning thrusters are expected to be well below 120 dB (rms) at 
distances greater than 10 km (6 mi). Among those measurements, the 
drilling activities conducted by the Tor Viking II at the Burger A well 
site in 2012 may have included dynamic positioning, and its distance of 
13 km (8 mi) was selected to model the 120 dB (rms) re 1 [micro]Pa 
isopleths for Shell's proposed 2013 equipment recovery and maintenance 
program. This yields to a 120 dB (rms) re 1 [micro]Pa ensonified zone 
of approximately 531 km\2\ (205 mi\2\).
    The equipment recovery and maintenance work at the well site may 
occur during either or both of the seasonal periods and may take place 
over as many as 28 days. Therefore, the entire area potentially exposed 
to continuous sounds >=120 dB (rms) from dynamic positioning thrusters 
has been applied to densities of marine mammals during both seasonal 
periods.

[[Page 47524]]

Potential Number of ``Take by Harassment''

    As stated earlier, the estimates of potential Level B takes of 
marine mammals by noise exposure are based on a consideration of the 
number of marine mammals that might be present during operations in the 
Chukchi Sea and the anticipated area exposed to those sound pressure 
levels (SPLs) above 160 dB re 1 [micro]Pa for impulse sources (seismic 
aregun during site clearance and shallow hazards surveys) and SPLs 
above 120 dB re 1 [micro]Pa for non-impulse sources (vessel's DP 
operation during equipment recovery and maintenance program).
    The number of individuals of each species potentially exposed to 
received levels was estimated by multiplying the anticipated area to be 
ensonified to the specified SPLs in each season (summer and fall) and 
habitat zone (open water and ice margin) to which a density applies, by 
the expected species density. The numbers of individuals potentially 
exposed were then summed for each species across the two seasons and 
habitat zones.
    An additional calculation was made that assumes the entire 
population of marine mammals within the 531 km\2\ (205 mi\2\) area 
exposed to non-pulsed sounds >=120 dB (rms) re 1 [micro]Pa during the 
equipment recovery and maintenance activity is different every day 
during that 28 day period. To do this, the 28 days were split evenly 
between the July-August and September-October periods (14 days in each 
period). The area ensonified by continuous sounds on each day was then 
multiplied by 14 before being multiplied by the appropriate species 
density within each season.
    Some of the animals estimated to be exposed, particularly migrating 
bowhead whales, might show avoidance reactions before being exposed to 
sounds at the specified threshold levels. Thus, these calculations 
actually estimate the number of individuals potentially exposed to the 
specified sounds levels that would occur if there were no avoidance of 
the area ensonified to that level.
    As described above, vessel and equipment limitations will result in 
very little activity occurring in or near sea ice; however, if ice is 
present near the areas of activity, some sounds produced by the 
activities may remain above disturbance threshold levels in ice margin 
habitats. Therefore, open water densities have been used to estimate 
potential ``take by harassment'' in 90 percent of the area expected to 
be ensonified above disturbance thresholds while ice margin densities 
have been used in the remaining 10 percent of the ensonified area. 
Species with an estimated average number of individuals exposed equal 
to zero are included below for completeness, but are not likely to be 
encountered.
    Numbers of marine mammals that might be present and potentially 
taken are summarized in Table 4 based on calculation described above.
    Some of the animals estimated to be exposed, particularly migrating 
bowhead whales, might show avoidance reactions before being exposed to 
>=160 dB (rms) re 1 [mu]Pa. Thus, these calculations actually estimate 
the number of individuals potentially exposed to specific SPLs, i.e., 
>=160 dB (rms) re 1 [mu]Pa for impulse noise and >=120 dB (rms) re 1 
[mu]Pa for non-impulse noise, that would occur if there were no 
avoidance of the area ensonified to that level.
    Because beluga whales may form groups, additional takes were added 
on top of the density-based take calculation in the event a large group 
is encountered during the survey. For marine mammal species that are 
rare and for which no density estimates are available in the vicinity 
of the proposed project area (such as humpback, fin, minke, and killer 
whales and narwhal), a small number of takes have been requested in 
case they are encountered (Table 4).

  Table 4--Estimates of the Possible Maximum Numbers of Marine Mammals
 Taken by Level B Harassment (Exposed to >=160 dB From Airgun Sound and
 =120 dB From Dynamic Positioning Operations) During Shell's
 Proposed Marine Survey and Equipment Recovery and Maintenance Activity
in the Chukchi Sea, July--October 2013, Including a Daily Multiplier for
     the Entire 28 Days Operational Period at the Burger A Well Site
------------------------------------------------------------------------
                                                  Level B      Percent
                    Species                        takes      population
------------------------------------------------------------------------
Bowhead whale.................................          209         1.98
Gray whale....................................          270         1.41
Fin whale.....................................           10         0.18
Humpback whale................................           10         1.07
Minke whale...................................           10         1.23
Beluga whale*.................................           53         1.43
Narwhal.......................................            4           NA
Killer whale..................................           10         3.18
Harbor porpoise...............................           35         0.07
Ringed seal...................................        5,096         2.44
Bearded seal..................................          178         0.07
Spotted seal..................................          102         0.17
Ribbon seal...................................           12         0.02
------------------------------------------------------------------------
* Additional takes were added in the event that a large group of beluga
  whales is encountered.

Estimated Take Conclusions

    Effects on marine mammals are generally expected to be restricted 
to avoidance of the area around the planned activities and short-term 
changes in behavior, falling within the MMPA definition of ``Level B 
harassment''.
    Cetaceans--The average estimates without a daily multiplier for the 
stationary operations suggest a total of 209 bowhead whales may be 
exposed to sounds at or above the specified levels. This number is 
approximately 1.98% of the BCB population of 10,545 assessed in 2001 
(Allen and Angliss 2011) and is assuming to be increasing at an annual 
growth rate of 3.4% (Zeh and Punt 2005), which is supported by a 2004 
population estimate of 12,631 by Koski et al. (2010). Including a daily 
multiplier brings the average estimate up to 209 individual bowhead 
whales with the daily multiplier (Table 4). The total estimated number 
of gray whales that may be exposed to sounds from the activities ranges 
up to 270 with the daily multiplier (Table 4). Fewer beluga whales and 
harbor porpoises are likely to be exposed to sounds during the 
activities. The small numbers of other whale species that may occur in 
the Chukchi Sea are unlikely to be present around the planned 
operations but chance encounters may occur. The few individuals would 
represent a very small proportion of their respective populations.
    Pinnipeds--Ringed seal is by far the most abundant species expected 
to be encountered during the planned operations. The best estimate of 
the numbers of ringed seals exposed to sounds at the specified received 
levels during the planned activities is 727 not including a daily 
multiplier, and 5,096 if a daily multiplier is included. Both of these 
numbers represent <3 percent of the estimated Alaska population. Fewer 
individuals of other pinniped species are estimated to be exposed to 
sounds at the specified received levels, also representing small 
proportions of their populations. Pinnipeds are unlikely to react to 
non-impulse sounds until received levels are much stronger than 120 dB 
(rms), so it is probable that a smaller number of these animals would 
actually be appreciably disturbed.

Negligible Impact and Small Numbers Analysis and Determination

    As a preliminary matter, we typically include our negligible impact 
and small numbers analyses and determinations under the same section 
heading of our Federal Register Notices. Despite co-locating these 
terms, we acknowledge

[[Page 47525]]

that negligible impact and small numbers are distinct standards under 
the MMPA and treat them as such. The analyses presented below do not 
conflate the two standards; instead, each standard has been considered 
independently and we have applied the relevant factors to inform our 
negligible impact and small numbers determinations.
    NMFS has defined ``negligible impact'' in 50 CFR 216.103 as ``. . . 
an impact resulting from the specified activity that cannot be 
reasonably expected to, and is not reasonably likely to, adversely 
affect the species or stock through effects on annual rates of 
recruitment or survival.'' In making a negligible impact determination, 
NMFS considers a variety of factors, including but not limited to: (1) 
the number of anticipated mortalities; (2) the number and nature of 
anticipated injuries; (3) the number, nature, intensity, and duration 
of Level B harassment; and (4) the context in which the takes occur.
    No injuries or mortalities are anticipated to occur as a result of 
Shell's proposed 2013 marine surveys and equipment recovery and 
maintenance program in the Chukchi Sea, and none are authorized. The 
proposed site clearance and shallow hazards surveys would use a very 
small 40 in\3\ airgun array, which have much less acoustic power 
outputs compared to conventional airgun arrays with displacement volume 
in the range of thousands of cubic inches. The modeled isopleths at 180 
dB, based on prior measurements for the same airgun array in the 
vicinity of the 2013 survey sites, is expected to be 160 m from the 
source at maximum. Source levels from vessel's DP thrusters during 
Shell's proposed equipment recovery and maintenance program are below 
180 dB re 1 [micro]Pa.
    In addition, animals in the area are not expected to incur hearing 
impairment (i.e., TTS or PTS) or non-auditory physiological effects. 
The modeled isopleths at 160 dB and 120 dB, based on prior 
measurements, are expected to be approximately 1.8 km and 13km from the 
airgun array and DP-operating vessel, respectively. Takes will be 
limited to Level B behavioral harassment. Although it is possible that 
some individuals of marine mammals may be exposed to sounds from the 
proposed site clearance and shallow hazard surveys and equipment 
recovery and maintenance activities more than once, the expanse of 
these multi-exposures are expected to be less extensive since either 
the animals or the vessels conducting the marine surveys will be moving 
constantly in and out of the survey areas.
    Most of the bowhead whales encountered will likely show overt 
disturbance (avoidance) only if they receive airgun sounds with levels 
>= 160 dB re 1 [mu]Pa. Odontocete reactions to seismic airgun pulses 
are usually assumed to be limited to shorter distances from the 
airgun(s) than are those of mysticetes, probably in part because 
odontocete low-frequency hearing is assumed to be less sensitive than 
that of mysticetes. However, at least when in the Canadian Beaufort Sea 
in summer, belugas appear to be fairly responsive to seismic energy, 
with few being sighted within 6-12 mi (10-20 km) of seismic vessels 
during aerial surveys (Miller et al. 2005). Belugas will likely occur 
in small numbers in the Chukchi Sea during the survey period and few 
will likely be affected by the survey activity.
    Although the stationary nature of the vessel that conducts 
equipment recovery and maintenance could affect different individuals 
of marine mammals during the operations, the relatively short period 
(28 days) of this activity precludes the take of large numbers of 
marine mammals. In addition, the noise levels generated from DP 
thrusters are much lower than the levels from the airgun array, and the 
modeled 120 dB isopleths is expected to be 13 km at the maximum, 
resulting an ensonified area of 531 km\2\.
    Taking into account the mitigation measures that are planned, 
effects on marine mammals are generally expected to be restricted to 
avoidance of a limited area around Shell's proposed open-water 
activities and short-term changes in behavior, falling within the MMPA 
definition of ``Level B harassment''. The many reported cases of 
apparent tolerance by cetaceans of seismic exploration, vessel traffic, 
and some other human activities show that co-existence is possible. 
Mitigation measures such as controlled vessel speed, dedicated marine 
mammal observers, non-pursuit, and shut downs or power downs when 
marine mammals are seen within defined ranges will further reduce 
short-term reactions and minimize any effects on hearing sensitivity. 
In all cases, the effects are expected to be short-term, with no 
lasting biological consequence.
    Of the thirteen marine mammal species likely to occur in the 
proposed marine survey area, bowhead, fin, and humpback whales and 
ringed and bearded seals are listed as endangered or threatened under 
the ESA. These species are also designated as ``depleted'' under the 
MMPA. Despite these designations, the Bering-Chukchi-Beaufort stock of 
bowheads has been increasing at a rate of 3.4 percent annually for 
nearly a decade (Allen and Angliss 2010). Additionally, during the 2001 
census, 121 calves were counted, which was the highest yet recorded. 
The calf count provides corroborating evidence for a healthy and 
increasing population (Allen and Angliss 2010). The occurrence of fin 
and humpback whales in the proposed marine survey areas is considered 
very rare. There is no critical habitat designated in the U.S. Arctic 
for the bowhead, fin, and humpback whales. The Alaska stock of bearded 
seals, part of the Beringia distinct population segment (DPS), and the 
Arctic stock of ringed seals, have recently been listed by NMFS as 
threatened under the ESA. None of the other species that may occur in 
the project area are listed as threatened or endangered under the ESA 
or designated as depleted under the MMPA.
    Potential impacts to marine mammal habitat were discussed 
previously in this document (see the ``Anticipated Effects on Habitat'' 
section). Although some disturbance is possible to food sources of 
marine mammals, the impacts are anticipated to be minor enough as to 
not affect rates of recruitment or survival of marine mammals in the 
area. Based on the vast size of the Arctic Ocean where feeding by 
marine mammals occurs versus the localized area of the marine survey 
activities, any missed feeding opportunities in the direct project area 
would be minor based on the fact that other feeding areas exist 
elsewhere.
    The authorized take represents 1.43% of the Eastern Chukchi Sea 
population of approximately 3,710 beluga whales, 3.18% of Aleutian 
Island and Bering Sea stock of approximately 314 killer whales, 0.07% 
of Bering Sea stock of approximately 48,215 harbor porpoises, 1.41% of 
the Eastern North Pacific stock of approximately 19,126 gray whales, 
1.98% of the Bering-Chukchi-Beaufort population of 10,545 bowhead 
whales, 1.07% of the Western North Pacific stock of approximately 938 
humpback whales, 0.18% of the Northeast Pacific stock of approximately 
5,700 fin whales, and 1.43% of the Alaska stock of approximately 810 
minke whales. The take estimates presented for ringed, bearded, 
spotted, and ribbon seals represent 2.44, 0.07, 0.17, and 0.02% of U.S. 
Arctic stocks of each species, respectively. The percentage of Level B 
behavioral take of 4 individual narwhals among its population is 
unknown as narwhal are not regularly sighted in the U.S. Chukchi Sea. 
Nevertheless, it is reasonable to believe that the number of narwhal 
estimated to be taken is a very

[[Page 47526]]

low percentage of its population. The mitigation and monitoring 
measures (described previously in this document) required under the IHA 
(if issued) are expected to reduce even further any potential 
disturbance to marine mammals.
    In addition, no important feeding and reproductive areas are known 
in the vicinity of the Shell's proposed marine surveys at the time the 
proposed surveys are to take place. No critical habitat of ESA-listed 
marine mammal species occurs in the Chukchi Sea.
    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, NMFS finds that Shell's proposed 2013 open-water marine 
surveys in the Chukchi Sea may result in the incidental take of small 
numbers of marine mammals, by Level B harassment only, and that the 
total taking from the marine surveys will have a negligible impact on 
the affected species or stocks.

Unmitigable Adverse Impact Analysis and Determination

    NMFS has determined that Shell's proposed 2013 open-water marine 
surveys in the Chukchi Sea will not have an unmitigable adverse impact 
on the availability of species or stocks for taking for subsistence 
uses. This determination is supported by information contained in this 
document and Shell's POC. Shell has adopted a spatial and temporal 
strategy for its Chukchi Sea open-water marine surveys that should 
minimize impacts to subsistence hunters. Due to the timing of the 
project and the distance from the surrounding communities (the proposed 
site clearance and shallow hazards surveys and equipment recovery and 
maintenance activities would be approximately 120 km to Wainwright and 
150 km to Point Lay), it is anticipated to have no effects on spring 
harvesting and little or no effects on the occasional summer harvest of 
beluga whale, subsistence seal hunts (ringed and spotted seals are 
primarily harvested in winter while bearded seals are hunted during 
July-September in the Beaufort Sea), or the fall bowhead hunt.

Endangered Species Act (ESA)

    The bowhead, fin, and humpback whales and ringed and bearded seals 
are the only marine mammal species currently listed as endangered or 
threatened under the ESA that could occur during Shell's proposed 
marine surveys during the Arctic open-water season. NMFS' Permits and 
Conservation Division consulted with NMFS' Alaska Regional Office 
Division of Protected Resources under section 7 of the ESA on the 
issuance of an IHA to Shell under section 101(a)(5)(D) of the MMPA for 
this activity. A Biological Opinion was issued on June 19, 2013, which 
concludes that issuance of the IHA is not likely to jeopardize the 
continued existence of the ESA-listed marine mammal species. NMFS will 
issue an Incidental Take Statement under this Biological Opinion which 
contains reasonable and prudent measures with implementing terms and 
conditions to minimize the effects of take of listed species.

National Environmental Policy Act (NEPA)

    NMFS prepared an EA that includes an analysis of potential 
environmental effects associated with NMFS' issuance of an IHA to Shell 
to take marine mammals incidental to conducting its marine surveys in 
the Chukchi Sea during the 2013 open-water season. NMFS has finalized 
the EA and prepared a FONSI for this action. Therefore, preparation of 
an EIS is not necessary.

Authorization

    As a result of these determinations, NMFS has issued an IHA to 
Shell to take marine mammals incidental to its 2013 marine survey in 
the Chukchi Sea, Alaska, provided the previously mentioned mitigation, 
monitoring, and reporting requirements are incorporated.

    Dated: July 30, 2013.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2013-18822 Filed 8-2-13; 8:45 am]
BILLING CODE 3510-22-P