Takes of Marine Mammals Incidental to Specified Activities; Marine Geophysical Survey in the Central-Western Bering Sea, August 2011, 49737-49751 [2011-20461]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 76, Number 155 (Thursday, August 11, 2011)]
[Notices]
[Pages 49737-49751]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-20461]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XA430


Takes of Marine Mammals Incidental to Specified Activities; 
Marine Geophysical Survey in the Central-Western Bering Sea, August 
2011

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

ACTION: Notice; issuance of an incidental take authorization (ITA).

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SUMMARY: In accordance with the Marine Mammal Protection Act (MMPA) 
regulation, notification is hereby given that NMFS has issued an 
Incidental Harassment Authorization (IHA) to the U.S. Geological Survey 
(USGS) to take marine mammals, by Level B harassment, incidental to 
conducting a marine geophysical survey in the central-western Bering 
Sea, August 2011.

DATES: Effective August 7 through October 1, 2011.

ADDRESSES: A copy of the IHA and application are available by writing 
to P. Michael Payne, Chief, Permits, Conservation and Education 
Division, Office of Protected Resources, National Marine Fisheries 
Service, 1315 East-West Highway, Silver Spring, MD 20910 or by 
telephoning the contacts listed here.
    A copy of the application containing a list of the references used 
in this document may be obtained by writing to the above address, 
telephoning the contact listed here (see FOR FURTHER INFORMATION 
CONTACT) or visiting the Internet at: https://www.nmfs.noaa.gov/pr/permits/incidental.htm#applications. The following associated documents 
are also available at the same Internet address: Environmental 
Assessment (EA), prepared by USGS. The NMFS Biological Opinion will be 
available online at: https://www.nmfs.noaa.gov/pr/consultation/opinions.htm. Documents cited in this notice may be viewed, by 
appointment, during regular business hours, at the aforementioned 
address.

FOR FURTHER INFORMATION CONTACT: Brian D. Hopper, 301-427-8401.

SUPPLEMENTARY INFORMATION:

Background

    Section 101(a)(5)(D) of the MMPA (16 U.S.C. 1371 (a)(5)(D)) directs 
the Secretary of Commerce (Secretary) to authorize, upon request, the 
incidental, but not intentional, taking of small numbers of marine 
mammals of a species or population stock, by United States citizens who 
engage in a specified activity (other than commercial fishing) within a 
specified geographical region if certain findings are made and, if the 
taking is limited to harassment, a notice of a proposed authorization 
is provided to the public for review.
    Authorization for the incidental taking of small numbers of marine 
mammals shall be granted if NMFS finds that the taking will have a 
negligible impact on the species or stock(s), and will not have an 
unmitigable adverse impact on the availability of the species or 
stock(s) for subsistence uses (where relevant). The authorization must 
set forth the permissible methods of taking, other means of effecting 
the least practicable adverse impact on the species or stock and its 
habitat, and requirements pertaining to the mitigation, monitoring and 
reporting of such takings. NMFS has defined ``negligible impact'' in 50 
CFR 216.103 as ``* * * an impact resulting from the specified activity 
that cannot be reasonably expected to, and is not reasonably likely to, 
adversely affect the species or stock through effects on annual rates 
of recruitment or survival.''
    Section 101(a)(5)(D) of the MMPA established an expedited process 
by which citizens of the United States can apply for an authorization 
to incidentally take small numbers of marine mammals by harassment. 
Section 101(a)(5)(D) of the MMPA establishes a 45-day time limit for 
NMFS's review of an application followed by a 30-day public notice and 
comment period on any proposed authorizations for the incidental 
harassment of small numbers of marine mammals. Within 45 days of the 
close of the public comment period, NMFS must either issue or deny the 
authorization. Except with respect to certain activities not pertinent 
here, the MMPA defines ``harassment'' as:

any act of pursuit, torment, or annoyance which (i) has the 
potential to injure a marine mammal or marine mammal stock in the 
wild [Level A harassment]; or (ii) has the potential to disturb a 
marine mammal or marine mammal stock in the wild by causing 
disruption of behavioral patterns, including, but not limited to, 
migration, breathing, nursing, breeding, feeding, or sheltering 
[Level B harassment].

16 U.S.C. 1362(18)

Summary of Request

    NMFS received an application on April 8, 2011, from USGS for the 
taking by harassment, of marine mammals, incidental to conducting a 
marine geophysical survey in the central-

[[Page 49738]]

western Bering Sea within the U.S. Exclusive Economic Zone (EEZ) and 
adjacent international waters in depths greater than 3,000 m (9,842 
ft). USGS plans to conduct the survey from approximately August 7 to 
September 1, 2011. On June 8, 2011, NMFS published a notice in the 
Federal Register (76 FR 33246) discussing the effects on marine mammals 
and making preliminary determinations regarding a proposed IHA. The 
notice initiated a 30 day public comment period, which closed on July 
8, 2011.
    USGS plans to use one source vessel, the R/V Marcus G. Langseth 
(Langseth) and a seismic airgun array to collect seismic reflection and 
refraction profiles to be used to delineate the U.S. Extended 
Continental Shelf (ECS) in the central-western Bering Sea. In addition 
to the operations of the seismic airgun array, USGS intends to operate 
a multibeam echosounder (MBES) and a sub-bottom profiler (SBP) 
continuously throughout the survey.
    Acoustic stimuli (i.e., increased underwater sound) generated 
during the operation of the seismic airgun array may have the potential 
to cause a short-term behavioral disturbance for marine mammals in the 
survey area. This is the principal means of marine mammal taking 
associated with these activities and USGS has requested an 
authorization to take 12 species of marine mammals by Level B 
harassment. Take is not expected to result from the use of the MBES or 
SBP, for reasons discussed in this notice; nor is take expected to 
result from collision with the vessel because it is a single vessel 
moving at a relatively slow speed during seismic acquisition within the 
survey, for a relatively short period of time (approximately 21 days). 
It is likely that any marine mammal would be able to avoid the vessel.

Description of the Specified Activity

    USGS plans to conduct the seismic survey in the central-western 
Bering Sea between approximately 350 and 800 kilometers (km) (189 and 
432 nautical miles (nmi)) offshore in the area 55[deg] to 58.5[deg] 
North, 177[deg] West to 175[deg] East. The survey will take place in 
the U.S. Exclusive Economic Zone (EEZ) and adjacent international 
waters in water depths greater than 3,000 meters (m) (9,842 feet (ft)). 
The project is scheduled to occur from approximately August 7 to 
September 1, 2011. Some minor deviation from these dates is possible, 
depending on logistics and weather.
    The seismic survey will collect seismic reflection and refraction 
profiles to be used to delineate the U.S. ECS in the Bering Sea. The 
ECS is the region beyond 200 nmi where a nation can show that it 
satisfies the conditions of Article 76 of the United Nations Convention 
on the Law of the Sea. One of the conditions in Article 76 is a 
function of sediment thickness. The seismic profiles are designed to 
identify the stratigraphic ``basement'' and to map the thickness of the 
overlying sediments. Acoustic velocities (required to convert measured 
travel times to true depth) will be measured directly using sonobuoys 
and ocean-bottom seismometers (OBSs), as well as by analysis of 
hydrophone streamer data. Acoustic velocity refers to the velocity of 
sound through sediments or crust.
    The survey will involve one source vessel, the Langseth. The 
Langseth will deploy an array of 36 airguns as an energy source. The 
receiving system will consist of one 8 km (4.3 nmi) long hydrophone 
streamer and/or five OBSs. As the airgun is towed along the survey 
lines, the hydrophone streamer will receive the returning acoustic 
signals and transfer the data to the on-board processing system. The 
OBSs record the returning acoustic signals internally for later 
analysis.
    The planned seismic survey will consist of approximately 2,240 km 
of transect lines in the central-western Bering Sea survey area, with 
an additional 140 km (75.6 nmi) of turns. During turns, the array will 
be powered-down to one 40 in\3\ airgun. All of the survey will take 
place in water deeper than 3,000 m (9,842 ft). A multi-channel seismic 
(MCS) survey using the hydrophone streamer will take place along 14 
lines. Following the MCS survey, 18 OBSs will be deployed and a 
refraction survey will take place along three of the 14 lines. If time 
permits, an additional 525 km of contingency lines will be added to the 
MCS survey. In addition to the the airgun array, a Kongsberg EM 122 
MBES and Knudsen 320B SBP will be operated from the Langseth 
continuously throughout the cruise. There will be additional seismic 
operations associated with equipment testing, start-up, and possible 
line changes or repeat coverage of any areas where initial data quality 
is sub-standard. In USGS's calculations, 25 percent has been added for 
those additional operations.
    All planned geophysical data acquisition activities will be 
conducted by Lamont-Doherty Earth Observatory (L-DEO), the Langseth's 
operator, with on-board assistance by the scientists who have planned 
the study. The Principal Investigators are Drs. Jonathan R. Childs and 
Ginger Barth of the USGS. The vessel will be self-contained, and the 
crew will live aboard the vessel for the entire cruise.

Description of the Dates, Duration, and Specified Geographic Region

    The survey will occur in the central-western Bering Sea between 
approximately 350 and 800 kilometers (km) (189 and 432 nautical miles 
(nmi)) offshore in the area 55[deg] to 58.5[deg] North, 177[deg] West 
to 175[deg] East. The seismic survey will take place in water depths 
greater than 3,000 m. The exact dates of the activities depend on 
logistics and weather conditions. The Langseth will depart from Dutch 
Harbor, Alaska on August 7, 2011, and return there on September 1, 
2011. Seismic operations will be carried out for an estimated 18 to 21 
days.
    NMFS outlined the purpose of the program in a previous notice for 
the proposed IHA (76 FR 33246, June 8, 2011). The activities to be 
conducted have not changed between the proposed IHA notice and this 
final notice announcing the issuance of the IHA. For a more detailed 
description of the authorized action, including vessel and acoustic 
source specifications, the reader should refer to the proposed IHA 
notice (76 FR 33246, June 8, 2011), the IHA application and associated 
documents referenced above this section.

Comments and Responses

    A notice of receipt of the USGS application and proposed IHA was 
published in the Federal Register on June 8, 2011 (76 FR 33246). During 
the 30-day public comment period, NMFS only received comments from the 
Marine Mammal Commission (Commission). The Commission's comments are 
online at: https://www.nmfs.noaa.gov/pr/permits/incidental.htm. 
Following are their comments and NMFS's responses:
    Comment 1: The Commission recommends that the NMFS require the USGS 
to re-estimate the proposed exclusion and buffer zones and associated 
takes of marine mammals using site-specific information.
    Response: In the water depths that the survey is to be conducted, 
site-specific source signature measurements are neither warranted nor 
practical. Site signature measurements are normally conducted 
commercially by shooting a test pattern over an ocean bottom instrument 
in shallow water. This method is neither practical nor valid in water 
depths as great as 3,000 m (9,842.5 ft). The alternative method of 
conducting site-specific attenuation measurements would require a 
second vessel, which is impractical both

[[Page 49739]]

logistically and financially. Sound propagation varies noticeably less 
between deep water sites than between shallow water sites (because of 
the reduced significance of bottom interaction), thus decreasing the 
importance of site-specific estimates.
    Based on these reasons, and the information provided by USGS in 
their IHA application and EA, NMFS is satisfied that the data supplied 
are sufficient for NMFS to conduct its analysis and make any 
determinations; therefore, no further effort is needed by the 
applicant. While exposures of marine mammals to acoustic stimuli are 
difficult to estimate, NMFS is confident that the levels of take 
authorized herein are estimated based upon the best available 
scientific information and estimation methodology. The 160 dB zone used 
to estimate exposure is appropriate and sufficient for purposes of 
supporting NMFS's analysis and determinations required under section 
101(a)(5)(D) of the MMPA and its implementing regulations. See NMFS's 
response to Comment 2 (below) for additional details.
    Comment 2: The Commission recommends that, if site-specific 
information is not used to estimate the proposed exclusion and buffer 
zones and associated takes of marine mammals, the USGS provide a 
detailed justification for the exclusion and buffer zones applicable to 
the proposed survey in the Bering Sea, which are based on either 
empirical data collected in the GOM or on modeling that uses 
measurements from the GOM, and explain the significance of any 
deviations in survey method, such as the proposed change in tow depth.
    Response: USGS has revised Appendix A in the EA to include 
information from the calibration study conducted on the Langseth in 
2007 and 2008. This information is now available in the final EA on 
USGS's Web site at https://walrus.wr.usgs.gov/EA/ECS_EA/ as well as on 
NSF's Web site at https://www.nsf.gov/geo/oce/envcomp/index.jsp. The 
revised Appendix A describes the L-DEO modeling process and compares 
the model results with empirical results of the 2007 to 2008 Langseth 
calibration experiment in shallow, intermediate, and deep water. The 
conclusions identified in Appendix A show that the model represents the 
actual produced levels, particularly within the first few kms, where 
the predicted exclusion zones (EZs, i.e., safety radii) lie. At greater 
distances, local oceanographic variations begin to take effect, and the 
model tends to over predict. Further, since the modeling matches the 
observed measurement data, the authors have concluded that the models 
can continue to be used for defining EZs, including for predicting 
mitigation radii for various tow depths. The data results from the 
studies were peer reviewed and the calibration results, viewed as 
conservative, were used to determine the cruise-specific EZs.
    At present, the L-DEO model does not account for site-specific 
environmental conditions. The calibration study of the L-DEO model 
predicted that using site-specific information may actually provide 
less conservative EZ radii at greater distances. The Draft Programmatic 
Environmental Impact Statement for Marine Seismic Research Funded by 
the National Science Foundation or Conducted by the U.S. Geological 
Survey (DPEIS) prepared pursuant to the National Environmental Policy 
Act (NEPA; 42 U.S.C. 4321 et seq.) did incorporate various site-
specific environmental conditions in the modeling of the Detailed 
Analysis Areas. The NEPA process associated with the DPEIS is still 
ongoing and the USGS and NSF have not yet issued a Record of Decision. 
Once the NEPA process for the PEIS has concluded, USGS and/or NSF will 
look at upcoming cruises on a site-specific basis for any impacts not 
already considered in the DPEIS.
    The IHA issued to USGS, under section 101(a)(5)(D) of the MMPA 
provides monitoring and mitigation requirements that will protect 
marine mammals from injury, serious injury, or mortality. USGS is 
required to comply with the IHA's requirements. These analyses are 
supported by extensive scientific research and data. NMFS is confident 
in the peer-reviewed results of the L-DEO seismic calibration studies 
which, although viewed as conservative, are used to determine cruise-
specific EZs and which factor into exposure estimates. NMFS has 
determined that these reviews are the best scientific data available 
for review of the IHA application and to support the necessary analyses 
and determinations under the MMPA, Endangered Species Act (ESA; 16 
U.S.C. 1531 et seq.) and NEPA.
    Based on NMFS's analysis of the likely effects of the specified 
activity on marine mammals and their habitat, NMFS has determined that 
the EZs identified in the IHA are appropriate for the survey and that 
additional field measurement is not necessary at this time. While 
exposures of marine mammals to acoustic stimuli are difficult to 
estimate, NMFS is confident that the levels of take authorized have 
been estimated based upon the best available scientific information and 
estimation methodology. The 160 dB zone used to estimate exposure is 
appropriate and sufficient for purposes of supporting NMFS's analysis 
and determinations required under section 101(a)(5)(D) of the MMPA and 
its implementing regulations.
    Comment 3: The Commission recommends that the NMFS specify in the 
authorization all conditions under which an 8 min period could be 
followed by a resumption of the airguns at full power.
    Response: In the instance of a power-down or shut-down based on the 
presence of a marine mammal in the EZ, USGS will restart the airgun 
array to the full operating source level (i.e., 36 airguns 6,600 in\3\) 
only if the PSVO visually observes the marine mammal exiting the EZ for 
the full source level within an 8 min period of the shut-down or power-
down. The 8 min period is based on the 180 dB radius for the 36 airgun 
subarray at a depth of 9 m in relation to the minimum planned speed of 
the Langseth while shooting (8.5 km/hr (4.6 kts)). In the event that a 
marine mammal would re-enter the EZ after reactivating the airguns, 
USGS would reinitiate a shut-down or power-down as required by the IHA.
    Should the airguns be inactive or powered-down for more than 8 min, 
and the PSVO does not observe the marine mammal leaving the EZ, then 
USGS must wait 15 min (for small odontocetes and pinnipeds) or 30 min 
(for mysticetes and large odontocetes) after the last sighting before 
USGS can initiate ramp-up procedures. However, ramp-up will not occur 
as long as a marine mammal is detected within the EZ, which provides 
more time for animals to leave the EZ, and accounts for the position, 
swim speed, and heading for marine mammals within the EZ.
    Finally, USGS may need to temporarily perform a shut-down due to 
equipment failure or maintenance. In this instance, USGS will restart 
the airgun array to the full source level within an 8 min period of the 
shut down only if the PSVOs do not observe marine mammals within the EZ 
for the full source level. If the airguns are inactive or powered-down 
for more than 8 min, USGS would follow the ramp-up procedures required 
by the IHA. USGS would restart the airguns beginning with the smallest 
airgun in the array and add airguns in a sequence such that the source 
level of the array does not exceed approximately 6 decibels (dB) per 5 
min period over a total duration of approximately 30 min. Again, the 
PSVOs would monitor the EZs for marine mammals during this time and

[[Page 49740]]

would initiate a power-down or a shut-down, as required by the IHA.
    Comment 4: The Commission recommends that the NMFS extend the 30 
min period following a marine mammal sighting in the EZ to cover the 
full dive times of all species likely to be encountered.
    Response: NMFS recognizes that several species of deep-diving 
cetaceans are capable of remaining underwater for more than 30 min 
(e.g., sperm whales, Cuvier's beaked whales, Baird's beaked whales); 
however, for the following reasons NMFS believes that 30 min is an 
adequate length for the monitoring period prior to the ramp-up of 
airguns:
    (1) Because the Langseth is required to monitor before ramp-up of 
the airgun array, the time of monitoring prior to start-up of any but 
the smallest array is effectively longer than 30 min (ramp-up will 
begin with the smallest airgun in the array and airguns will be added 
in sequence such that the source level of the array will increase in 
steps not exceeding approximately 6 dB per 5 min period over a total 
duration of 20 to 30 min;
    (2) In many cases PSVOs are observing during times when USGS is not 
operating the seismic airguns and would observe the area prior to the 
30 min observation period;
    (3) The majority of the species that may be exposed do not stay 
underwater more than 30 min; and
    (4) All else being equal and if deep-diving individuals happened to 
be in the area in the short time immediately prior to the pre-ramp-up 
monitoring, if an animal's maximum underwater dive time is 45 min, then 
there is only a one in three chance that the last random surfacing 
would occur prior to the beginning of the required 30 min monitoring 
period and that the animal would not be seen during that 30 min period.
    Finally, seismic vessels are moving continuously (because of the 
long, towed array and streamer) and NMFS believes that unless the 
animal submerges and follows at the speed of the vessel (highly 
unlikely, especially when considering that a significant part of their 
movements is vertical (deep-diving)), the vessel will be far beyond the 
length of the EZ radii within 30 min, and therefore it will be safe to 
start the airguns again.
    Under the MMPA, incidental take authorizations must include means 
of effecting the least practicable adverse impact on marine mammal 
species and their habitat. Monitoring and mitigation measures are 
designed to comply with this requirement. NMFS believes that the 
framework for visual monitoring will: (1) Be effective at spotting 
almost all species for which take is requested; and (2) that imposing 
additional requirements, such as those suggested by the Commission, 
would not meaningfully increase the effectiveness of observing marine 
mammals approaching or entering the EZs and thus further minimize the 
potential for take.
    Comment 5: The Commission recommends that the NMFS provide 
additional justification for its preliminary determination that the 
proposed monitoring program will be sufficient to detect, with a high 
level of confidence, all marine mammals within or entering the 
identified exclusion and buffer zones, which at a minimum should:
    (1) Identify those species that it believes can be detected with a 
high degree of confidence using visual monitoring only;
    (2) Describe detection probability as a function of distance from 
the vessel;
    (3) Describe changes in detection probability under various sea 
state and weather conditions and light levels; and
    (4) Explain how close to the vessel marine mammals must be for 
Protected Species Observers (PSOs) to achieve high nighttime detection 
rates.
    Response: NMFS believes that the planned monitoring program will be 
sufficient to detect (using visual monitoring and passive acoustic 
monitoring (PAM)), with reasonable certainty, marine mammals within or 
entering identified EZs. This monitoring, along with the required 
mitigation measures, will result in the least practicable adverse 
impact on the affected species or stocks and will result in a 
negligible impact on the affected species or stocks of marine mammals. 
Also, NMFS expects some animals to avoid areas around the airgun area 
ensonified at the level of the EZ.
    NMFS acknowledges that the detection probability for certain 
species of marine mammals varies depending on animal size and behavior 
as well as sea state and weather conditions and light levels. The 
detectability of marine mammals likely decreases in low light (i.e., 
darkness), higher Beaufort sea states and wind conditions, and poor 
weather (e.g., fog and/or rain). However, at present, NMFS views the 
combination of visual monitoring and PAM as the most effective 
monitoring and mitigation techniques available for detecting marine 
mammals within or entering the EZ. The final monitoring and mitigation 
measures are the most effective feasible measures and NMFS is not aware 
of any additional measures which could meaningfully increase the 
likelihood of detecting marine mammals in and around the EZ. Further, 
public comment has not revealed any additional monitoring or mitigation 
measures that could be feasibly implemented to increase the 
effectiveness of detection.
    USGS (the Federal funding agency for this survey), National Science 
Foundation (NSF), and L-DEO are receptive to incorporating proven 
technologies and techniques to enhance the current monitoring and 
mitigation program. Until proven technological advances are made, 
nighttime mitigation measures during operations include combinations of 
the use of Protected Species Visual Observers (PSVOs) for ramp-ups, 
PAM, night vision devices (NVDs), and continuous shooting of a 
mitigation airgun. Should the airgun array be powered-down, the 
operation of a single airgun would continue to serve as a sound source 
deterrent to marine mammals. In the event of a complete shut-down of 
the airgun array at night for mitigation or repairs, USGS suspends the 
data collection until one-half hour after nautical twilight-dawn (when 
PSVO's are able to clear the EZ). USGS will not activate the airguns 
until the entire EZ is visible for at least 30 min.
    In cooperation with NMFS, L-DEO will be conducting efficacy 
experiments of NVDs during a future Langseth cruise. In addition, in 
response to a recommendation from NMFS, L-DEO is evaluating the use of 
handheld forward-looking thermal imaging cameras to supplement 
nighttime monitoring and mitigation practices. During other low power 
seismic and seafloor mapping surveys, USGS successfully used these 
devices while conducting nighttime seismic operations.
    Comment 6: The Commission recommends that the NMFS consult with the 
funding agency (i.e., NSF) and individual applicants (e.g., USGS and L-
DEO) to develop, validate, and implement a monitoring program that 
provides a scientifically sound, reasonably accurate assessment of the 
types of marine mammal taking and the number of marine mammals taken.
    Response: Numerous studies have reported on the abundance and 
distribution of marine mammals inhabiting the Bering Sea, which 
overlaps with the seismic survey area, and USGS has incorporated this 
data into their analyses used to predict marine mammal take in their 
application. NMFS believes that USGS's current approach for estimating 
abundance in the survey area (prior to the survey) is the best 
available approach.

[[Page 49741]]

    There will be significant amounts of transit time during the 
cruise, and PSVOs will be on watch prior to and after the seismic 
portions of the survey, in addition to during the survey. The 
collection of this visual observational data by PSVOs may contribute to 
baseline data on marine mammals (presence/absence) and provide some 
generalized support for estimated take numbers, but it is unlikely that 
the information gathered from this single cruise alone would result in 
any statistically robust conclusions for any particular species because 
of the small number of animals typically observed.
    NMFS acknowledges the Commission's recommendations and is open to 
further coordination with the Commission, USGS (the Federal research 
funding agency for this cruise), NSF (the vessel owner), and L-DEO (the 
ship operator on behalf of NSF), to develop, validate, and implement a 
monitoring program that will provide or contribute towards a more 
scientifically sound and reasonably accurate assessment of the types of 
marine mammal taking and the number of marine mammals taken. However, 
the cruise's primary focus is marine geophysical research and the 
survey may be operationally limited due to considerations such as 
location, time, fuel, services, and other resources.
    Comment 7: The Commission recommends that NMFS require the 
applicant:
    (1) To report on the number of marine mammals that were detected 
acoustically and for which a power-down or shut-down of the airguns was 
initiated;
    (2) Specify if such animals also were detected visually; and
    (3) Compare the results from the two monitoring methods (visual 
versus acoustic) to help identify their respective strengths and 
weaknesses.
    Response: The IHA requires that PSAOs on the Langseth do and record 
the following when a marine mammal is detected by the PAM:
    (1) Notify the on-duty PSVO(s) immediately of a vocalizing marine 
mammal so a power-down or shut-down can be initiated, if required;
    (2) Enter the information regarding the vocalization into a 
database. The data to be entered include an acoustic encounter 
identification number, whether it was linked with a visual sighting, 
date, time when first and last heard and whenever any additional 
information was recorded, position, and water depth when first 
detected, bearing if determinable, species or species group (e.g., 
unidentified dolphin, sperm whale), types and nature of sounds heard 
(e.g., clicks, continuous, sporadic, whistles, creaks, burst pulses, 
strength of signal, etc.), and any other notable information.
    USGS reports on the number of acoustic detections made by the PAM 
system within the post-cruise monitoring reports as required by the 
IHA. The report also includes a description of any acoustic detections 
that were concurrent with visual sightings, which allows for a 
comparison of acoustic and visual detection methods for each cruise.
    The post-cruise monitoring reports also include the following 
information: the total operational effort in daylight (hrs), the total 
operational effort at night (hrs), the total number of hours of visual 
observations conducted, the total number of sightings, and the total 
number of hours of acoustic detections conducted.
    LGL Ltd., Environmental Research Associates (LGL), a contractor for 
USGS, has processed sighting and density data, and their publications 
can be viewed online at: https://www.lgl.com/index.php?option=com_content&view=article&id=69&Itemid=162&lang=en. Post-cruise monitoring 
reports are currently available on the NMFS's MMPA Incidental Take 
Program Web site and future reports will also be available on the NSF 
Web site should there be interest in further analysis of this data by 
the public.
    Comment 8: The Commission recommends that NMFS condition the 
authorization, if issued, to require the USGS to monitor, document, and 
report observations during all ramp-up procedures; this data will 
provide a stronger scientific basis for determining the effectiveness 
of and deciding when to implement this particular mitigation measure.
    Response: The IHA requires that PSVOs on the Langseth make 
observations for 30 min prior to ramp-up, during all ramp-ups, and 
during all daytime seismic operations and record the following 
information when a marine mammal is sighted:
    (1) Species, group size, age/size/sex categories (if determinable), 
behavior when first sighted and after initial sighting, heading (if 
consistent), bearing and distance from seismic vessel, sighting cue, 
apparent reaction of the airguns or vessel (e.g., none, avoidance, 
approach, paralleling, etc., and including responses to ramp-up), and 
behavioral pace; and
    (2) Time, location, heading, speed, activity of the vessel 
(including number of airguns operating and whether in state of ramp-up 
or power-down), Beaufort wind force and sea state, visibility, and sun 
glare.
    Comment 9: The Commission recommends that NMFS in collaboration 
with the NSF, analyze these data to determine the effectiveness of 
ramp-up procedures as a mitigation measure for geophysical surveys.
    Response: One of the primary purposes of monitoring is to result in 
``increased knowledge of the species'' and the effectiveness of 
monitoring and mitigation measures; the effectiveness of ramp-up as a 
mitigation measure and marine mammal reaction to ramp-up would be 
useful information in this regard. NMFS has asked USGS, NSF, and L-DEO 
to gather all data that could potentially provide information regarding 
the effectiveness of ramp-ups as a mitigation measure. However, 
considering the low numbers of marine mammal sightings and low numbers 
of ramp-ups, it is unlikely that the information will result in any 
statistically robust conclusions for this particular seismic survey. 
Over the long term, these requirements may provide information 
regarding the effectiveness of ramp-up as a mitigation measure, 
provided animals are detected during ramp up.

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

    Twenty marine mammal species (14 cetacean and 6 pinniped) are known 
to or could occur in the central-western Bering Sea. Several of these 
species are listed as endangered under the U.S. Endangered Species Act 
of 1973 (ESA; 16 U.S.C. 1531 et seq.), including the North Pacific 
right whale (Eubalaena japonica), bowhead (Balaena mysticetus), 
humpback (Megaptera novaeangliae), sei (Balaenoptera borealis), fin 
(Balaenoptera physalus), blue (Balaenoptera musculus), and sperm 
(Physeter macrocephalus) whales, as well as the western stock of 
Steller sea lions (Eumetopias jubatus). The eastern stock of Steller 
sea lions is listed as threatened.
    The marine mammals that occur in the survey area belong to three 
taxonomic groups: odontocetes (toothed cetaceans, such as dolphins), 
mysticetes (baleen whales), and pinnipeds (seals, sea lions, and 
walrus). Cetaceans and pinnipeds are the subject of the IHA application 
to NMFS. Walrus sightings are rare in the Bering Sea during the summer. 
The U.S. Fish and Wildlife Service (USFWS) manages the Pacific walrus 
and they are not considered further in this analysis; all others 
species are managed by NMFS. Coastal cetacean species (gray whales) 
likely

[[Page 49742]]

would not be encountered in the deep, offshore waters of the survey 
area.
    Table 1 presents information on the abundance, distribution, 
population status, conservation status, and density of the marine 
mammals that may occur in the survey area during August 2011.

 Table 1--The Habitat, Regional Abundance, and Conservation Status of Marine Mammals That May Occur in or Near the Seismic Survey Areas in the Central-
                               Western Bering Sea (See Text and Table 2 in USGS's Application and EA for Further Details)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                   Density (number/1,000
                                  Occurrence in/near                         Regional                                                     km\2\)
            Species                  survey area            Habitat          abundance         ESA \1\            MMPA \2\       -----------------------
                                                                                                                                   Best \3\     Max \4\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Mysticetes:
North Pacific right whale       Rare.................  Coastal, shelf,   Low hundreds \5\  EN              D                            0           0
 (Eubalaena japonica).                                  offshore.
Bowhead whale (Balaena          Uncommon.............  Pack ice,         12,631 \6\......  EN              D                            0           0
 mysticetus).                                           coastal.
Gray whale (Eschrichtius        Common...............  Coastal, shallow  NW Pacific:       DL/E \8\        NC D (Western                0.01        0.12
 robustus).                                             shelf.            19,126 NE                         populations)
                                                                          Pacific: ~100
                                                                          \7\.
Humpback whale (Megaptera       Common...............  Offshore,         20,800 \9\......  EN              D                            0.40        1.04
 novaeangliae).                                         nearshore in
                                                        winter.
Minke whale (Balaenoptera       Common...............  Nearshore,        25,000 \10\.....  NL              NC                           1.23        4.10
 acutorostrata).                                        offshore, ice.
Sei whale (Balaenoptera         Uncommon.............  Offshore, shelf.  7,260 to 12,620   EN              D                            0.05        0.58
 borealis).                                                               \11\.
Fin whale (Balaenoptera         Common...............  Offshore, deep    13,620 to 18,680  EN              D                            3.94       17.00
 physalus).                                             water.            \12\.
Blue whale (Balaneoptera        Rare.................  Offshore, shelf,  3,500 \13\......  EN              D                            0           0
 musculus).                                             coastal.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Odontocetes:
Sperm whale (Physeter           Uncommon.............  Offshore........  24,000 \14\.....  EN              D                            0.07        0.14
 macrocephalus).
Cuvier's beaked whale (Ziphius  Very rare............  Offshore........  20,000 \15\.....  NL              NC                           0           0
 cavirostris).
Baird's beaked whale            Rare.................  Offshore........  7,000 \16\......  NL              NC                           0.07        0.10
 (Berardius bairdii).
Stejneger's beaked whale        Uncommon.............  Offshore........  N.A.............  NL              NC                           0.04        0.12
 (Mesoplodon stejnegeri).
Pacific white-sided dolphin     Rare.................  Pelagic, shelf,   988,000 \17\....  NL              NC                           0.03        0.04
 (Lagenorhynchus obliquidens).                          coastal.
Killer whale (Orcinus orca)...  Common...............  Pelagic, shelf,   8,500 \18\......  NL              NC                           2.82        3.96
                                                        coastal.
Dall's porpoise (Phocoenoides   Common...............  Nearshore,        1,186,000 \19\..  NL              NC                           8.86       18.25
 dalli).                                                offshore.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pinnipeds:
Northern fur seal (Callorhinus  Common...............  Offshore and      1.1 million \20\  NL              D                           28.5        42.75
 ursinus).                                              coastal.
Steller sea lion (Eumetopias    Common...............  Coastal.........  58,334, 72,223    T \23\, EN      D                            2.70        4.05
 jubatus).                                                                \21\, 42,366      \23\
                                                                          \22\.
Spotted seal (Phoca largha)...  Uncommon.............  Ice.............  AK: ~59,214 \24\  NL              .....................        N.A.        N.A.
Ringed seal (Pusa hispida)....  Uncommon.............  Ice, landfast,    AK: 249,000 \24\  NL              NC                           N.A.        N.A.
                                                        pack.

[[Page 49743]]

 
Ribbon seal (Histriophoca       Common...............  Ice.............  Bering Sea:       NL              NC                          43.60       65.40
 fasciata).                                                               90,000-100,000
                                                                          \24\.
--------------------------------------------------------------------------------------------------------------------------------------------------------
N.A. Not available or not assessed.
\1\ U.S. Endangered Species Act: EN = Endangered, T = Threatened, NL = Not listed.
\2\ U.S. Marine Mammal Protection Act: D = Depleted, NC = Not Classified.
\3\ Best density estimate as listed in Table 3 of the application.
\4\ Maximum density estimate as listed in Table 3 of the application.
\5\ Western population (Brownell et al., 2001)
\6\ Based on 2003-2005 surveys (Koski et al., 2010).
\7\ Northwest (NW) Pacific (Allen and Angliss, 2010); Northeast (NE) Pacific (Reilly et al., 2008).
\8\ The western (Northeast Pacific) subpopulation is listed as Endangered.
\9\ North Pacific Ocean (Barlow et al., 2009).
\10\ Northwest Pacific (Buckland et al., 1992; IWC, 2010).
\11\ North Pacific (Tillman, 1977).
\12\ North Pacific (Ohsumi and Wada, 1974).
\13\ Eastern North Pacific (NMFS, 1998).
\14\ Eastern temperate North Pacific (Whitehead, 2002b).
\15\ Eastern Tropical Pacific (Wade and Gerrodette, 1993).
\16\ Western North Pacific (Reeves and Leatherwood, 1994; Kasuya, 2002).
\17\ North Pacific Ocean (Miyashita, 1993b).
\18\ Eastern Tropical Pacific (Ford, 2002).
\19\ North Pacific Ocean and Bering Sea (Houck and Jefferson, 1999).
\20\ North Pacific (Gelatt and Lowry, 2008).
\21\ Eastern U.S. Stock (Allen and Angliss, 2010).
\22\ Western U.S. Stock (Allen and Angliss, 2010).
\23\ Eastern stock is listed as threatened, and the western stock is listed as endangered.
\24\ Burns 1981.

    Refer to Section III of USGS's application for detailed information 
regarding the abundance and distribution, population status, and life 
history and behavior of these species and their occurrence in the 
project area. The application also presents how USGS calculated the 
estimated densities for the marine mammals in the survey area. NMFS has 
reviewed these data and determined them to be the best available 
scientific information for the purposes of the IHA.

Potential Effects on Marine Mammals

    Acoustic stimuli generated by the operation of the airguns, which 
introduce sound into the marine environment, may have the potential to 
cause Level B harassment of marine mammals in the survey area. The 
effects of sounds from airgun operations might include one or more of 
the following: tolerance, masking of natural sounds, behavioral 
disturbance, temporary or permanent hearing impairment, or non-auditory 
physical or physiological effects (Richardson et al., 1995; Gordon et 
al., 2004; Nowacek et al., 2007; Southall et al., 2007).
    Permanent hearing impairment, in the unlikely event that it 
occurred, would constitute injury, but temporary threshold shift (TTS) 
is not an injury (Southall et al., 2007). Although the possibility 
cannot be entirely excluded, it is unlikely that the project would 
result in any cases of temporary or permanent hearing impairment, or 
any significant non-auditory physical or physiological effects. Based 
on the available data and studies described here, some behavioral 
disturbance is expected, but NMFS expects the disturbance to be 
localized and short-term.
    The notice of the proposed IHA (76 FR 33246, June 8, 2011) included 
a discussion of the effects of sounds from airguns on mysticetes, 
odontocetes, and pinnipeds including tolerance, masking, behavioral 
disturbance, hearing impairment, and other non-auditory physical 
effects. NMFS refers the reader to USGS's application, and EA for 
additional information on the behavioral reactions (or lack thereof) by 
all types of marine mammals to seismic vessels.

Anticipated Effects on Marine Mammal Habitat

    NMFS included a detailed discussion of the potential effects of 
this action on marine mammal habitat, including physiological and 
behavioral effects on marine fish and invertebrates in the notice of 
the proposed IHA (76 FR 33246, June 8, 2011). While NMFS anticipates 
that the specified activity may result in marine mammals avoiding 
certain areas due to temporary ensonification, this impact to habitat 
is temporary and site-specific, which NMFS considered in greater detail 
in the notice of the proposed IHA (76 FR 33246, June 8, 2011) as 
behavioral modification. The main impact associated with the activity 
would be temporarily elevated noise levels and the associated direct 
effects on marine mammals.

Mitigation

    In order to issue an ITA under section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to such 
activity, and other means of effecting the least practicable adverse 
impact on such species or stock and its habitat, paying particular 
attention to rookeries, mating grounds, and areas of similar 
significance, and the availability of such species or stock for taking 
for certain subsistence uses.
    USGS based the mitigation measures to be implemented for the 
seismic survey on the following:
    (1) Protocols used during previous USGS and L-DEO seismic research 
cruises as approved by NMFS;
    (2) Previous IHA applications and IHAs approved and authorized by 
NMFS; and

[[Page 49744]]

    (3) Recommended best practices in Richardson et al. (1995), Pierson 
et al. (1998), and Weir and Dolman (2007).
    To reduce the potential for disturbance from acoustic stimuli 
associated with the activities, USGS and/or its designees will 
implement the following mitigation measures for marine mammals:
    (1) EZs;
    (2) Power-down procedures;
    (3) Shut-down procedures;
    (4) Ramp-up procedures; and
    (5) Special procedures for situations and species of concern.
    Planning Phase--In designing the seismic survey, USGS has 
considered potential environmental impacts including seasonal, 
biological, and weather factors; ship schedules; and equipment 
availability. Part of the considerations was whether the research 
objectives could be met with a smaller source; tests will be conducted 
to determine whether the two-string sub-array (3,300 in\3\) will be 
satisfactory to accomplish the geophysical objectives. If so, the 
smaller array will be used to minimize environmental impact. Also, the 
array will be powered-down to a single airgun during turns, and the 
array will be shut-down during OBS deployment and retrieval.
    EZs--Received sound levels have been determined by corrected 
empirical measurements for the 36 airgun array, and the L-DEO model was 
used to predict the EZs for the single 1900LL 40 in\3\ airgun, which 
will be used during power-downs. Results were recently reported for 
propagation measurements of pulses from the 36 airgun array in two 
water depths (approximately 1,600 m and 50 m (5,249 to 164 ft)) in the 
Gulf of Mexico (GOM) in 2007 to 2008 (Tolstoy et al., 2009). It would 
be prudent to use the empirical values that resulted to determine EZs 
for the airgun array. Results of the propagation measurements (Tolstoy 
et al., 2009) showed that radii around the airguns for various received 
levels varied with water depth. During the study, all survey effort 
will take place in deep (greater than 1,000 m) water, so propagation in 
shallow water is not relevant here. The depth of the array was 
different in the GOM calibration study (6 m (19.7 ft)) than in the 
survey (9 m); thus, correction factors have been applied to the 
distances reported by Tolstoy et al. (2009). The correction factors 
used were the ratios of the 160, 180, and 190 dB distances from the 
modeled results for the 6,600 in\3\ airgun array towed at 6 m versus 9 
m. Based on the propagation measurements and modeling, the distances 
from the source where sound levels are predicted to be 190, 180, and 
160 dB re 1 [micro]Pa (rms) were determined. The 180 and 190 dB radii 
are to 940 m and 400 m, respectively, as specified by NMFS (2000); 
these levels were used to establish the EZs.
    If the PSVO detects marine mammal(s) within or about to enter the 
appropriate EZ, the airguns will be powered-down (or shut-down, if 
necessary) immediately.
    Table 2 summarizes the predicted distances at which sound levels 
(160, 180, and 190 dB (rms)) are expected to be received from the 36 
airgun array and a single airgun operating in deep water depths.

  Table 2--Measured (Array) or Predicted (Single Airgun) Distances To Which Sound Levels >=190, 180, and 160 dB
  re: 1 [mu]Pa (rms) Could Be Received in Water Depths >1,000 m During the Survey in the Central-Western Bering
                                                Sea, August 2011
----------------------------------------------------------------------------------------------------------------
                                                                         Predicted RMS distances (m)
         Source and volume                Water depth      -----------------------------------------------------
                                                                 190 dB            180 dB            160 dB
----------------------------------------------------------------------------------------------------------------
Single Bolt airgun (40 in\3\)......  Deep >1,000 m........                12                40               385
4 Strings 36 airguns (6,600 in\3\).  Deep >1,000 m........               400               940             3,850
----------------------------------------------------------------------------------------------------------------

    Power-down Procedures--A power-down involves decreasing the number 
of airguns in use such that the radius of the 180 dB (or 190 dB) zone 
is decreased to the extent that marine mammals are no longer in or 
about to enter the EZ. A power-down of the airgun array can also occur 
when the vessel is moving from one seismic line to another. During a 
power-down for mitigation, USGS will operate one airgun. The continued 
operation of one airgun is intended to alert marine mammals to the 
presence of the seismic vessel in the area. In contrast, a shut-down 
occurs when the Langseth suspends all airgun activity.
    If the PSVO detects a marine mammal outside the EZ, but it is 
likely to enter the EZ, USGS will power-down the airguns before the 
animal is within the EZ. Likewise, if a mammal is already within the 
EZ, when first detected USGS will power-down the airguns immediately. 
During a power-down of the airgun array, USGS will also operate the 40 
in\3\ airgun. If a marine mammal is detected within or near the smaller 
EZ around that single airgun, USGS will shut-down the airgun (see next 
section).
    Following a power-down, USGS will not resume airgun activity until 
the marine mammal has cleared the EZ. USGS will consider the animal to 
have cleared the EZ if:
     A PSVO has visually observed the animal leave the EZ, or
     A PSVO has not sighted the animal within the EZ for 15 min 
for species with shorter dive durations (i.e., small odontocetes or 
pinnipeds), or 30 min for species with longer dive durations (i.e., 
mysticetes and large odontocetes, including sperm, pygmy sperm, dwarf 
sperm, killer, and beaked whales).
    During airgun operations following a power-down (or shut-down) 
whose duration has exceeded the time limits specified previously, USGS 
will ramp-up the airgun array gradually (see Shut-down and Ramp-up 
Procedures).
    Shut-down Procedures--USGS will shut down the operating airgun(s) 
if a marine mammal is seen within or approaching the EZ for the single 
airgun. USGS will implement a shut-down:
    (1) If an animal enters the EZ of the single airgun after USGS has 
initiated a power-down; or
    (2) If an animal is initially seen within the EZ of the single 
airgun when more than one airgun (typically the full airgun array) is 
operating.
    USGS will not resume airgun activity until the marine mammal has 
cleared the EZ, or until the PSVO is confident that the animal has left 
the vicinity of the vessel. Criteria for judging that the animal has 
cleared the EZ will be as described in the preceding section.
    Ramp-up Procedures--USGS will follow a ramp-up procedure when the 
airgun array begins operating after a specified period without airgun 
operations or when a power-down has exceeded that period. USGS proposes 
that, for the present cruise, this period would be approximately eight 
min. This period is based on the 180 dB radius (940 m) for the 36 
airgun array towed at a depth of 9 m in relation to the

[[Page 49745]]

minimum planned speed of the Langseth while shooting (7.4 km/hr). USGS 
and L-DEO have used similar periods (approximately 8 to 10 min) during 
previous L-DEO surveys.
    Ramp-up will begin with the smallest airgun in the array (40 
in\3\). Airguns will be added in a sequence such that the source level 
of the array will increase in steps not exceeding six dB per five min 
period over a total duration of approximately 35 min. During ramp-up, 
the PSOs will monitor the EZ, and if marine mammals are sighted, USGS 
will implement a power-down or shut-down as though the full airgun 
array were operational.
    If the complete EZ has not been visible for at least 30 min prior 
to the start of operations in either daylight or nighttime, USGS will 
not commence the ramp-up unless at least one airgun (40 in\3\ or 
similar) has been operating during the interruption of seismic survey 
operations. Given these provisions, it is likely that the airgun array 
will not be ramped-up from a complete shut-down at night or in thick 
fog, because the outer part of the EZ for that array will not be 
visible during those conditions. If one airgun has operated during a 
power-down period, ramp-up to full power will be permissible at night 
or in poor visibility, on the assumption that marine mammals will be 
alerted to the approaching seismic vessel by the sounds from the single 
airgun and could move away. USGS will not initiate a ramp-up of the 
airguns if a marine mammal is sighted within or near the applicable EZs 
during the day or close to the vessel at night.
    Special Procedures for Situations and Species of Concern--USGS will 
implement special mitigation procedures as follows:
     The airguns will be shut-down immediately if ESA-listed 
species for which no takes are being requested (i.e., North Pacific 
right and blue whales) are sighted at any distance from the vessel. 
Ramp-up will only begin if the whale has not been seen for 30 min.
     Concentrations of humpback, fin, and/or killer whales will 
be avoided if possible, and the array will be powered-down if 
necessary. For purposes of this survey, a concentration or group of 
whales will consist of three or more individuals visually sighted that 
do not appear to be traveling (e.g., feeding, socializing, etc.).
    NMFS has carefully evaluated the applicant's mitigation measures 
and has considered a range of other measures in the context of ensuring 
that NMFS prescribes the means of effecting the least practicable 
adverse impact on the affected marine mammal species and stocks and 
their habitat. NMFS's evaluation of potential measures included 
consideration of the following factors in relation to one another:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure is expected to minimize adverse impacts 
to marine mammals;
    (2) The proven or likely efficacy of the specific measure to 
minimize adverse impacts as planned; and
    (3) The practicability of the measure for applicant implementation.
    Based on NMFS's evaluation of the applicant's measures, as well as 
other measures considered by NMFS or recommended by the public, NMFS 
has determined that the mitigation measures provide the means of 
effecting the least practicable adverse impacts on marine mammal 
species or stocks and their habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance.

Monitoring and Reporting

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

Monitoring

    USGS would sponsor marine mammal monitoring during the present 
project, in order to implement the mitigation measures that require 
real-time monitoring, and to satisfy the anticipated monitoring 
requirements of the IHA. USGS's Monitoring Plan is described below this 
section. The monitoring work described here has been planned as a self-
contained project independent of any other related monitoring projects 
that may be occurring simultaneously in the same regions. USGS is 
prepared to discuss coordination of its monitoring program with any 
related work that might be done by other groups insofar as this is 
practical and desirable.

Vessel-Based Visual Monitoring

    USGS's PSVOs will be based aboard the seismic source vessel and 
will watch for marine mammals near the vessel during daytime airgun 
operations and during any ramp-ups at night. PSVOs will also watch for 
marine mammals near the seismic vessel for at least 30 min prior to the 
start of airgun operations after an extended shut-down.
    PSVOs will conduct observations during daytime periods when the 
seismic system is not operating for comparison of sighting rates and 
behavior with and without airgun operations and between acquisition 
periods. Based on PSVO observations, the airguns will be powered-down 
or shut-down when marine mammals are observed within or about to enter 
a designated EZ.
    During seismic operations in the central-western Bering Sea, at 
least four PSOs will be based aboard the Langseth. USGS will appoint 
the PSOs with NMFS's concurrence. Observations will take place during 
ongoing daytime operations and nighttime ramp-ups of the airguns. 
During the majority of seismic operations, two PSVOs will be on duty 
from the observation tower to monitor marine mammals near the seismic 
vessel. Use of two simultaneous PSVOs will increase the effectiveness 
of detecting animals near the source vessel. However, during meal times 
and bathroom breaks, it is sometimes difficult to have two PSVOs on 
effort, but at least one PSVO will be on duty. PSVO(s) will be on duty 
in shifts of duration no longer than 4 hr.
    Two PSVOs will also be on visual watch during all nighttime ramp-
ups of the seismic airguns. A third PSO (i.e., Protected Species 
Acoustic Observer (PSAO)) will monitor the PAM equipment 24 hours a day 
to detect vocalizing marine mammals present in the action area. In 
summary, a typical daytime cruise would have scheduled two PSVOs on 
duty from the observation tower, and a third PSAO on PAM. Other crew 
will also be instructed to assist in detecting marine mammals and 
implementing mitigation requirements (if practical). Before the start 
of the seismic survey, the crew will be given additional instruction on 
how to do so.
    The Langseth is a suitable platform for marine mammal observations. 
When stationed on the observation platform, the eye level will be 
approximately 21.5 m (70.5 ft) above sea level, and the PSVO will have 
a good view around the entire vessel. During daytime, the PSVOs will 
scan the area around the vessel systematically with reticle binoculars 
(e.g., 7 x 50 Fujinon), Big-eye binoculars (25 x 150), and with the 
naked eye. During darkness, NVDs will be available (ITT F500 Series 
Generation 3 binocular-image intensifier or equivalent), when required. 
Laser range-

[[Page 49746]]

finding binoculars (Leica LRF 1200 laser rangefinder or equivalent) 
will be available to assist with distance estimation. Those are useful 
in training observers to estimate distances visually, but are generally 
not useful in measuring distances to animals directly; that is done 
primarily with the reticles in the binoculars.
    When marine mammals are detected within or about to enter the 
designated EZ, the airguns will immediately be powered-down or shut-
down if necessary. The PSVO(s) will continue to maintain watch to 
determine when the animal(s) are outside the EZ by visual confirmation. 
Airgun operations will not resume until the animal is confirmed to have 
left the EZ, or if not observed after 15 min for species with shorter 
dive durations (small odontocetes and pinnipeds) or 30 min for species 
with longer dive durations (mysticetes and large odontocetes, including 
sperm, killer, and beaked whales).

PAM

    PAM will complement the visual monitoring program, when 
practicable. Visual monitoring typically is not effective during 
periods of poor visibility or at night, and even with good visibility, 
is unable to detect marine mammals when they are below the surface or 
beyond visual range.
    Besides the three PSVOs, an additional PSAO with primary 
responsibility for PAM will also be aboard the vessel. USGS can use 
acoustic monitoring in addition to visual observations to improve 
detection, identification, and localization of cetaceans. The acoustic 
monitoring will serve to alert visual observers (if on duty) when 
vocalizing cetaceans are detected. It is only useful when marine 
mammals call, but it can be effective either by day or by night, and 
does not depend on good visibility. It will be monitored in real time 
so that the PSVOs can be advised when cetaceans are detected. When 
bearings (primary and mirror-image) to calling cetacean(s) are 
determined, the bearings will be relayed to the visual observer to help 
him/her sight the calling animal(s).
    The PAM system consists of hardware (i.e., hydrophones) and 
software. The ``wet end'' of the system consists of a towed hydrophone 
array that is connected to the vessel by a cable. The array will be 
deployed from a winch located on the back deck. A deck cable will 
connect from the winch to the main computer laboratory where the 
acoustic station and signal conditioning and processing system will be 
located. The digitized signal and PAM system is monitored by PSAOs at a 
station in the main laboratory. The lead in from the hydrophone array 
is approximately 400 m (1,312 ft) long, the active section of the array 
is approximately 56 m (184 ft) long, and the hydrophone array is 
typically towed at depths of less than 20 m (66 ft).
    Ideally, the PSAO will monitor the towed hydrophones 24 hr per day 
at the seismic survey area during airgun operations, and during most 
periods when the Langseth is underway while the airguns are not 
operating. However, PAM may not be possible if damage occurs to both 
the primary and back-up hydrophone arrays during operations. The 
primary PAM streamer on the Langseth is a digital hydrophone streamer. 
Should the digital streamer fail, back-up systems should include an 
analog spare streamer and a hull-mounted hydrophone. Every effort would 
be made to have a working PAM system during the cruise. In the unlikely 
event that all three of these systems were to fail, USGS would continue 
science acquisition with the visual-based observer program. The PAM 
system is a supplementary enhancement to the visual monitoring program. 
If weather conditions were to prevent the use of PAM then conditions