Takes of Marine Mammals Incidental to Specified Activities; Navy Training Conducted at the Silver Strand Training Complex, San Diego Bay, 43238-43259 [2012-17972]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 77, Number 142 (Tuesday, July 24, 2012)]
[Notices]
[Pages 43238-43259]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2012-17972]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XZ14


Takes of Marine Mammals Incidental to Specified Activities; Navy 
Training Conducted at the Silver Strand Training Complex, San Diego Bay

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

ACTION: Notice of issuance of an incidental harassment authorization.

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SUMMARY: In accordance with provisions of the Marine Mammal Protection 
Act (MMPA) as amended, notification is hereby given that an Incidental 
Harassment Authorization (IHA) has been issued to the U.S. Navy (Navy) 
to take marine mammals, by harassment, incidental to conducting 
training exercises at the Silver Strand Training Complex (SSTC) in the 
vicinity of San Diego Bay, California.

DATES: This authorization is effective from July 18, 2012, until July 
17, 2013.

ADDRESSES: A copy of the application, IHA, and/or a list of references 
used in this document may be obtained by writing to P. Michael Payne, 
Chief, Permits and Conservation Division, Office of Protected 
Resources, National Marine Fisheries Service, 1315 East-West Highway, 
Silver Spring, MD 20910-3225.

FOR FURTHER INFORMATION CONTACT: Shane Guan, NMFS, (301) 427-8401, or 
Monica DeAngelis, NMFS, (562) 980-3232.

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 (Secretary) 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) if certain findings are made and regulations are 
issued or, if the taking is limited to harassment, 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 taking 
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.''
    The National Defense Authorization Act of 2004 (NDAA) (Public Law 
108-136) removed the ``small numbers'' and ``specified geographical 
region'' limitations and amended the definition of ``harassment'' as it 
applies to a ``military readiness activity'' to read as follows 
(Section 3(18)(B) of the MMPA):
    (i) Any act that injures or has the significant potential to injure 
a marine mammal or marine mammal stock in the wild [Level A 
Harassment]; or
    (ii) any act that disturbs or is likely to disturb a marine mammal 
or marine mammal stock in the wild by causing disruption of natural 
behavioral patterns, including, but not limited to,

[[Page 43239]]

migration, surfacing, nursing, breeding, feeding, or sheltering, to a 
point where such behavioral patterns are abandoned or significantly 
altered [Level B Harassment].
    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) 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.

Summary of Request

    NMFS received an application on March 3, 2010, and subsequently, a 
revised application on September 13, 2010, from the Navy for the 
taking, by harassment, of marine mammals incidental to conducting 
training exercises at the Navy's Silver Strand Training Complex (SSTC) 
in the vicinity of San Diego Bay, California. On October 19, 2010, NMFS 
published a Federal Register notice (75 FR 64276) requesting comments 
from the public concerning the Navy's proposed training activities 
along with NMFS' proposed IHA. However, on March 4, 2011, three long-
beaked common dolphins were found dead following the Navy's mine 
neutralization training exercise involving time-delayed firing devices 
(TDFDs) at SSTC, and were suspected to be killed by the detonation. In 
short, a TDFD device begins a countdown to a detonation event that 
cannot be stopped, for example, with a 10-min TDFD, once the detonation 
has been initiated, 10 minutes pass before the detonation occurs and 
the event cannot be cancelled during that 10 minutes. Subsequently, 
NMFS suspended the IHA process for SSTC and worked with the Navy to 
come up with more robust monitoring and mitigation measures to prevent 
such incidents. On July 22, 2011, the Navy submitted an addendum to its 
IHA application which includes additional information and additional 
mitigation and monitoring measures for its proposed mine neutralization 
training exercises using TDFDs at SSTC to ensure that the potential for 
injury or mortality is minimized. On March 30, 2012, NMFS published a 
supplemental Federal Register notice for the proposed IHA (77 FR 19231) 
with enhanced mitigation and monitoring measures for training exercises 
using TDFDs and additional information on marine mammal species in the 
vicinity of the STCC.
    Since there was no change made to the proposed activities, the 
description of the Navy's proposed SSTC training activities is not 
repeated here. Please refer to the Federal Register notices (75 FR 
64276; October 19, 2010; 77 FR 19231; March 30, 2012) for the proposed 
IHA and its modification.

Comments and Responses

    A notice of receipt and request for public comment on the 
application and proposed authorization, and for public comment on 
enhanced monitoring and mitigation measures for the use of TDFDs were 
published on October 19, 2010 (75 FR 64276) and on March 30, 2012 (77 
FR 19231). During the 30-day public comment periods, the Marine Mammal 
Commission (Commission) and a private citizen provided comments.

Comments from October 19, 2010, Federal Register Notice

    Comment 1: The Commission requests NMFS to require the Navy to 
revise density estimates and subsequent number of takes to reflect 
accurately the densities presented in the references or provide a 
reasoned explanation for the densities that were used. The Commission 
specifically points out that in general, the densities for California 
sea lions, harbor seals, and gray whales in Table 3-1 of the IHA 
application are inconsistent with Table 3.9-3 of the reference (DoN 
2008). In addition, the Commission points out that in the case of 
bottlenose dolphins, the reference (National Centers for Coastal Ocean 
Science 2005) does not explicitly provide density estimates for this 
species and should not be cited as a direct source for these estimates.
    Response: NMFS believes that the Navy's density estimates and 
subsequent number of takes used in the IHA application accurately 
reflect the densities presented in the references and are appropriate, 
although NMFS and the Navy concur that an error was made in Table 3-1 
of the IHA application regarding the sources of marine mammal 
densities. The Navy points out that marine mammal density data actually 
came from Carretta et al. (2000), rather than from the Southern 
California (SOCAL) Range Complex Environmental Impact Statement/
Overseas Environmental Impact Statement (EIS/OEIS) as stated in the IHA 
application. The title of the reference is ``Distribution and abundance 
of marine mammals at San Clemente Island and surrounding offshore 
waters: Results from aerial and ground surveys in 1998 and 1999'' 
(specifically from Table 5, page 22 of the document) and is coauthored 
by J. V. Carretta, M. S. Lowry, C. E. Stinchcomb, M. S. Lynn and R. E. 
Cosgrove, and was published by NMFS Southwest Fisheries Science Center 
(SWFSC) in La Jolla, California. The density values shown in Table 3-1 
were correctly used from Carretta et al. (2000) although rounded to two 
significant digits.
    Regarding pinniped density data, the Navy specifies that Carretta 
et al. (2000) represents one of the few systematic regional at-sea 
surveys for pinnipeds within Southern California. NMFS currently does 
not conduct pinniped at-sea assessments and instead relies on land 
based counts for its stock assessment reports, and there is no other 
published Southern California pinniped at-sea density information that 
the Navy or NMFS is aware of. Therefore, Carretta et al. (2000) is a 
considered the best available science for such data.
    Regarding gray whale density data, these were modified from 
Carretta el al. (2000) during 2006 when the Navy began to prepare the 
SSTC EIS and subsequent IHA application by NMFS SWFSC. This is 
reflective of the limited nature of transitory gray whale presence 
within the very nearshore habitat of SSTC.
    Bottlenose dolphin density information was derived from NMFS SWFSC 
sighting data for the coastal stock of this species. The data show 
estimated encounter rate in number of dolphins per kilometer (km) for 
distinct segments along the California coastline, including the coastal 
area of SSTC. The Navy used the encounter rates along the shore 
adjacent to SSTC and given as referenced within the IHA application 
that this stock is normally thought to reside within 1 km of the coast, 
used the NOAA values for density in km squared (0.202 individual per km 
x 1 km = 0.202 individual per km\2\).
    In addition, the Navy contacted the leading experts at NMFS SWFSC 
on the coastal stock of bottlenose dolphins in response to the 
Commission's comment, and these experts confirmed that there were no 
traditional NMFS DISTANCE methodology density estimates available for 
the coastal stock of bottlenose dolphins available from NMFS. While 
NMFS research continues on this stock, the primary tool is visual 
sighting and photographic comparison, with much data still unpublished. 
NMFS SWFSC confirmed that the stock, while likely of higher occurrence 
south of Point Conception, has a very fluid distribution from south of 
San Francisco to some unknown distance down the Baja peninsula. There 
are likely significant

[[Page 43240]]

variations daily, annually, and inter-annually influencing distribution 
along the coast that are as yet not fully understood but certainly 
linked to oceanographic conditions as they influence prey availability. 
The Navy states that based on discussion with other NMFS SWFSC experts, 
use of the National Centers for Coastal Ocean Science publication as a 
source of published values for density of the coastal stock of 
bottlenose dolphins was appropriate. This publication did list 
encounter rate (density) in a range from 0.202 to 0.311. The Navy in 
the SSTC IHA application selected the 0.202 value given the anticipated 
limited occurrence of coastal bottlenose dolphins within the small 
spatial extent (approximately 6.5 km of ocean-side shoreline) in which 
the SSTC training activities being sought for authorization occur. In 
addition, as pointed out by experts from the Scripps Institution of 
Oceanography (SIO), most of the current research on this stock is 
focused on coastal dolphins surveys from Point Loma north. There is no 
or limited recent effort near SSTC. Finally, for the coastal stock of 
bottlenose dolphins (and all marine mammal densities used) the Navy's 
modeling process assumes a constant presence and density of each stock 
or species specifically within the SSTC action area, when in reality as 
discussed at length in the IHA application and briefly above, there 
will be times when no marine mammals including bottlenose dolphins will 
be present. In conclusion, NMFS believes that given the uncertainties 
of dolphin distribution within SSTC, and the conservative assumptions 
used by the Navy's model (that dolphins are always present), the 0.202 
density value is justified within the context of the SSTC IHA 
application, and that the other densities discussed in this response 
(pinniped and gray whale) are also scientifically justified.
    Nevertheless, following the incident of common dolphin mortalities 
that resulted from the use of TDFDs during a training exercise, the 
Navy and NMFS reassessed the species distribution in the SSTC study 
area and included four additional dolphin species. These species 
include long-beaked common dolphins (Delphinus capensis), short-beaked 
common dolphin (D. delphis), Pacific white-sided dolphin 
(Lagenorhynchus obliquidens), and Risso's dolphin (Grampus griseus), 
and have been sighted in the vicinity of the SSTC training area, but 
much less frequently.
    Comment 2: The Commission requests NMFS require the Navy to conduct 
external peer review of marine mammal density estimates, the data upon 
which those estimates are based, and the manner in which those data are 
being used.
    Response: As discussed in detail in the Response to Comment 1, the 
marine mammal density data used in the SSTC IHA application and the 
Federal Register notice (75 FR 64276; October 19, 2010) for the 
proposed IHA were reviewed by NMFS Regional and Science Center experts 
as well as by scientists from SIO. These reviews support the 
reliability of the data being used in making take estimates.
    Comment 3: The Commission requests that NMFS only issue the IHA 
contingent upon a requirement that Navy first use location-specific 
environmental parameters to re-estimate safety zones and then use in-
situ measurements to verify, and if need be, refine the safety zones 
prior to or at the beginning of pile driving and removal.
    Response: During processing of the Navy's IHA application, and 
through the formal consultation between the Navy and NMFS Southwest 
Regional Office (SWRO) on Essential Fish Habitat, the Navy will be 
required to conduct an in-situ acoustic propagation measurement and 
monitoring for pile driving and removal during the first training 
deployment of the ELCAS at the SSTC. This acoustic measurement and 
monitoring will provide empirical field data on ELCAS pile driving and 
pile removal underwater source levels, and propagation specific to 
environmental conditions and ELCAS training at the SSTC. These values 
will be used to refine the safety zones prior to or at the beginning of 
pile driving and removal, and to inform subsequent consultations with 
NMFS in an adaptive management forum. Therefore, the Navy is already 
required to use location-specific environmental parameters to re-
estimate safety zones and then use in-situ measurements to verify, and 
if need be, refine the safety zones prior to or at the beginning of 
pile driving and removal.
    Comment 4: The Commission requests that before issuing the 
authorization, NMFS require Navy to use consistent methods for rounding 
fractional animals to whole numbers to determine takes from underwater 
detonations and pile driving and removal, and re-estimate marine mammal 
takes using the same methods for all proposed activities.
    Response: NMFS has reviewed the Navy's process for modeling and 
estimating numbers of marine mammals that could be exposed to sound 
from underwater explosions and pile driving related training activities 
at SSTC, and also discussed with the Navy the method by which the take 
numbers were calculated. Based on the review and discussion, NMFS 
believes that the Navy's modeling and calculation of marine mammal 
takes from underwater detonations and pile driving and removal are 
consistent and conservative. Specifically for the SSTC IHA application 
pile driving and removal calculations, the Navy elected to apply a 
conservative and over-predictive process of ``rounding up'' to the next 
whole number any fractional exposures to generate the largest possible 
exposure given variations in marine mammal densities as discussed in 
Response to Comment 1. NMFS believes that the Commission's comment is 
probably due to the lack of detailed description of the ELCAS take 
calculation in the Navy's IHA application and the Federal Register 
notice (75 FR 64276; October 19, 2010) for the proposed IHA. A detailed 
description along with a calculation example is provided later in this 
document.
    Comment 5: The Commission requested that NMFS require the Navy to 
monitor for at least 30 minutes before, during and at least 30 minutes 
after all underwater detonations and pile driving and pile removing 
activities.
    Response: The proposed mitigation measures in the Federal Register 
notice (75 FR 64276; October 19, 2010) for the proposed IHA already 
called for monitoring for marine species 30 minutes before underwater 
detonations, and 30 minutes after underwater detonations. Monitoring 
during the training event would be continuous. The only exception is 
for the much smaller charge weight shock wave action generator (SWAG) 
event (0.03 lbs) where the before and after monitoring period is 10 
minutes, due to its small zones of influence (60 yards or 55 m for TTS 
at 23 psi in warm season and 40 yards or 37 m in cold season; 20 yards 
or 18 m for TTS at 182 dB re 1 [mu]Pa\2\-sec in both warm and cold 
seasons). NMFS feels that 10 minutes is adequate given the very small 
charge weight, smaller zones for easy visual monitoring, and extremely 
unlikely injury or mortality from this kind of event.
    Enhanced monitoring measures concerning detonations that involve 
TDFDs are discussed below.
    The Navy originally proposed to monitor for 30 minutes prior to 
ELCAS pile driving or pile removal and monitoring through pile driving 
and removal activities, but not post-activity because there is little 
likelihood of marine species mortality or injury from pile driving and 
removal. However, NMFS agrees with the Commission that the Navy should 
conduct monitoring 30

[[Page 43241]]

minutes after ELCAS pile driving and removal to ensure that no marine 
mammals were injured or killed by these activities. NMFS believes that 
post pile driving and removal monitoring is warranted due to the large 
zones of influence for pile driving and removal and because marine 
mammals could be missed by visual monitors. Therefore, 30 minutes of 
post pile driving and removal monitoring is required in the IHA NMFS 
issued to the Navy, and the Navy has incorporated this requirement into 
its latest IHA application submitted on December 28, 2010.
    Comment 6: The Commission requests NMFS require the Navy to take 
steps to ensure that safety zones for pile driving and removal are 
clear of marine mammals for at least 30 minutes before activities can 
be resumed after a shutdown.
    Response: As it described in detail in the Federal Register notice 
(75 FR 64276; October 19, 2010) for the proposed IHA, isopleths 
corresponding to 180 dB re 1 [micro]Pa from impact pile driving are 46 
yards (42 m) from the source. The Navy proposes a safety zone (or 
mitigation zone in the Navy's IHA application) of 50 yards as a 
shutdown zone for marine mammal mitigation. NMFS believes that in such 
a small zone, visual monitoring can be easily and effectively conducted 
to ensure that marine mammals have cleared the area after a shutdown 
measure has been called. Therefore, it is unnecessary for the Navy to 
wait for 30 minutes before activities are resumed after a shutdown. In 
addition, the Navy states that imposing a 30 minute post-shutdown 
resumption time interval would have significant negative training 
impacts because there is only a small window allowed for ELCAS 
construction to meet training objectives.
    Therefore, NMFS does not agree with the Commission, nor considers 
it necessary, to impose a 30-minute post-shutdown waiting time to clear 
marine mammals.
    No safety zone would be established for pile removal since the 
isopleths corresponding to 180 dB re 1 [micro]Pa is at the source.
    Comment 7: Pending the outcome of an exploration of options to 
assess the efficacy of soft-starts during pile driving and removal, the 
Commission requests NMFS to require Navy to make observations during 
all soft starts to gather the data needed to analyze and report on the 
effectiveness of soft-starts as a mitigation measure.
    Response: The ``soft start'' provision associated with ELCAS pile 
driving is one of the mitigation measures required for this activity. 
Although the efficacy of soft starts has not been assessed, it is 
believed that by increasing the pile driving power incrementally 
instead of starting with full power, marine mammals that were missed 
during the 30-minute pre pile driving monitoring would leave the area 
and avoid receiving TTS or PTS. NMFS agrees with the Commission that an 
evaluation of efficacy is warranted. However, given the limited nature 
of actual pile driving, and overall low marine mammal densities and 
occurrence within parts of SSTC where ELCAS would be used, NMFS does 
not believe that mandating a soft start effectiveness analysis would be 
meaningful or provide enough verifiable data to make any sort of 
reliable, scientific conclusion based on the ELCAS pile driving. 
Nevertheless, NMFS will require the Navy to instruct potential ELCAS 
monitoring personnel to note any observations during the entire pile 
driving sequence, including ``soft start'' period, for later analysis.
    Comment 8: The Commission requests NMFS to condition the 
authorization, if issued, to require suspension of exercises if a 
marine mammal is seriously injured or killed and the injury or death 
could be associated with those exercises, and if additional measures 
are unlikely to reduce the risk of additional serious injuries or 
deaths to a very low level, require Navy to obtain the necessary 
authorization for such takings under MMPA.
    Response: Though NMFS largely agrees with the Commission, it should 
be noted that without detailed examination by an expert, it is usually 
not feasible to determine the cause of injury or mortality when an 
injured or dead marine mammal is sighted in the field. Therefore, NMFS 
has required in its IHA that if there is clear evidence that a marine 
mammal is injured or killed as a result of the proposed Navy training 
activities (e.g., instances in which it is clear that munitions 
explosions caused the injury or death) the Naval activities shall be 
immediately suspended and the situation immediately reported by 
personnel involved in the activity to the officer in charge of the 
training, who will follow Navy procedures for reporting the incident to 
NMFS through the Navy's chain-of-command.
    For any other sighting of injured or dead marine mammals in the 
vicinity of any of Navy's SSTC training activities utilizing underwater 
explosive detonations for which the cause of injury or mortality cannot 
be immediately determined, Navy personnel will ensure that NMFS 
(regional stranding coordinator) is notified immediately (or as soon as 
operational security allows). The Navy will provide NMFS with 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).
    Comment 9: The Commission requests NMFS ensure that discrepancies 
between the Navy's application and NMFS' Federal Register notice (75 FR 
64276; October 19, 2010) for the proposed IHA are corrected and 
addressed in the authorization.
    Response: During the SSTC IHA application review and process, the 
Navy made two updates to the original February 16, 2010, application to 
provide an enhanced description of training events, and reflect 
substantive content from discussion with NMFS. The first update was on 
September 1, 2010 and the second update on November 4, 2010. Both 
updates were integrated into the final review by NMFS when making the 
determination to issue the IHA. NMFS has therefore corrected and 
addressed all inconsistencies among different IHA application stages 
and NMFS' Federal Register notice (75 FR 64276; October 19, 2010) for 
the proposed IHA.

Comments from March 30, 2012, Federal Register Notice

    Comment 10: The Commission requests NMFS require the Navy to model 
the various proposed monitoring schemes to determine what portion of 
the associated buffer zone is being monitored at any given time and the 
probability that dolphins entering that buffer zone would be detected 
before they get too close to the detonation site.
    Response: In the fall of 2011, the Navy funded the Center for Naval 
Analysis (CNA) to examine this issue. CNA was asked to: (1) Analyze the 
Navy's mitigation approach (estimate the probability of marine mammals 
getting within the explosives safety zone without being detected, for 
various scenarios; (2) Determine what mathematical methods are 
appropriate for estimating the probabilities of mammals entering the 
various safety zones undetected; (3) Using the mathematical methods 
determined above, how effective are the Navy's mitigation procedures in 
protecting animals; and (4) Determine what are the effects of various 
factors such as: size of explosive charges, footprint of impact zones, 
travel speeds of various marine mammals, number and location of Navy 
observers.
    CNA validated that a geometric approach to the problem would help 
in

[[Page 43242]]

assessing the study questions outlined above, and its final conclusions 
on the Navy's proposed TDFD mitigations were:
     Explosive harm ranges for the charge sizes under 
consideration are driven by the 13 psi-ms acoustic impulse metric, 
corresponding to slight lung injury;
     Fuse delay and animal swim speeds strongly drive results 
regarding mitigation capability;
     Probability of detection of all animals (Pd):
    [ssquf] For TDFD mitigation ranges out to 1,000 yards, Pd would be 
close to 100% for 2-boats and 5-minute delay for charge weights up to 
20-lb net explosive weight (NEW);
    [ssquf] For TDFD mitigation ranges of 1,400/1,500 yards, likely Pd 
would be > 95-99% for 3-boats and 10-minute delay for charge weights up 
to 20-lb NEW.
     A three-boat effort is sufficient to cover most cases.
    In terms of how the CNA analysis relates to the SSTC training 
activities, please see Response to Comment 12.
    Comment 11: The Commission requests NMFS require the Navy to (1) 
measure empirically the propagation characteristics of the blast (i.e., 
impulse, peak pressure, and sound exposure level) from the 5-, 10-, and 
15- to 29-lb charges used in the proposed exercises; and (2) use that 
information to establish appropriately sized exclusion and buffer 
zones.
    Response: In 2002, the Navy conducted empirical measurements of 
underwater detonations at San Clemente Island and at the Silver Strand 
Training Complex in California. During these tests, 2 lb and 15 lb NEW 
charges were placed at 6 and 15 feet of water and peak pressures and 
energies were measured for both bottom placed detonations and 
detonations off the bottom. A finding was that, generally, single-
charge underwater detonations, empirically measured, were similar to or 
less than propagation model predictions. Based on SSTC modeling, many 
of the mitigation zones by NEW proposed in the Navy's original SSTC IHA 
application of February 2010 were much smaller than the zones proposed 
in the Navy's SSTC IHA application addendum of October 2011.
    As part of agreement on monitoring measures between NMFS and the 
Navy, the Navy will annually monitor a sub-set of SSTC underwater 
detonations with an additional boat containing marine mammal observers 
comprised of Navy scientists, contract scientists, and periodically 
NMFS scientists. The Navy will explore the value of adding field 
measurements during monitoring of a future mine neutralization event 
after evaluating the environmental variables affecting sound 
propagation in the area, such as shallow depths, seasonal temperature 
variation, bottom sediment composition, and other factors that would 
affect our confidence in the data collected. Further, the Navy states 
that if such data can be collected within existing programmed funding 
for SSTC monitoring (i.e., costs) and without impacts to training, the 
Navy will move forward in incorporating one-time propagation 
measurements into its monitoring program for SSTC underwater 
detonations training.
    Comment 12: The Commission requests NMFS require the Navy to re-
estimate the sizes of the buffer zones using the average swim speed of 
the fastest swimming marine mammal that inhabits the areas within and 
in the vicinity of SSTC where TDFSs would be used and for which taking 
authorization is being requested. The Commission states that animals 
swimming faster than 3 knots could easily be at increased risk. 
Providing peer-reviewed papers by Lockyer and Morris (1987), Mate et 
al. (1995), Ridoux et al. (1997), Rohr et al. (1998), and Rohr and Fish 
(2004), the Commission points out that many marine mammals are capable 
of swimming much faster than 4 knots, especially during short 
timeframes.
    Response: NMFS does not agree with the Commission's assessment that 
the sizes of the buffer zones be established based on average swim 
speed of the fastest swimming marine mammals. While the Commission 
quotes higher swim speeds, the behavioral context of the speeds should 
be considered. Just because an animal can go faster does not mean that 
it will. A better citation than one provided by the Commission (Rohr et 
al. 1998) is perhaps Rohr et al. (2006). Speeds reported are in terms 
of maximum for a captive long-beaked common dolphin, and for wild long-
beaked common dolphin evoked by low passes from an airplane recording 
their reaction (Rohr et al. 2006). Maximum speeds are energetically 
expensive for any organism and usually not maintained for long. 
Unpublished observations of marine mammals within the SSTC boat lanes 
during the Navy 2011 and 2012 surveys have documented mostly small 
groups of slow moving, milling coastal stock of bottlenose dolphins and 
California sea lions. The occurrence of more pelagic species (long-
beaked common dolphins, Pacific white-sided dolphins, Risso's dolphins, 
and short-beaked common dolphins) is predicted to be less likely and 
limited in duration. Navy included these species in the SSTC IHA 
application addendum as a conservative measure.
    Further expansion of the buffer zones is not warranted because: (1) 
The current buffer zones already incorporate an additional 
precautionary factor to account for swim speeds above 3 knots; and (2) 
buffer zones greater than 1,000 yards for events using 2 boats, and 
1,400/1,500 yards for events using 3 boats or 2 boats and 1 helicopter, 
cannot be monitored or supported by the Navy's exercising units.
    In terms of sizes of the mitigation zones, a maximum 1,400 and 
1,500 yard radius for larger charge or longer time TDFD training events 
are required, which is the maximum distance the Navy can confidently 
clear with 3 boats (or 2 boats and 1 helicopter). NMFS is satisfied 
that the mitigation zones proposed in the supplemental Federal Register 
notice for the proposed IHA (77 FR 19231; March 30, 2012) are 
justified, adequate, and protective of marine mammals. In addition to 
the buffer zone determination issue, there are also additional 
operational and training resources to consider. While larger mitigation 
zones increase distance from the detonation site, there must also be an 
ability to adequately survey a mitigation zone to ensure animals are 
spotted. Due to the type of small unit training being conducted at 
SSTC, there are limited surveillance assets available to monitor a 
given buffer zone during underwater detonations training. Scheduling 
additional observation boats and crews beyond what the Navy has 
proposed in the SSTC IHA application addendum involves coordination and 
availability of other unit(s) and will degrade overall training 
readiness. For instance, limited availability of boats and personnel do 
not allow for operation of 4 or more boats. If 4 boats were required, 
negative impacts to military readiness would result because Navy would 
be precluded from conducting events due to unavailable assets. 
Therefore, both NMFS and the Navy do not consider additional 
observation boats other than those designated a valid option during 
SSTC TDFD training events.
    Comment 13: The Commission requests NMFS to advise the Navy that it 
should seek authorization for serious injury and incidental mortality 
in addition to taking by harassment. The Commission states that the 
March 2011 SSTC incident indicates that the Navy's monitoring and 
mitigation measures used to protect marine mammals during these 
exercises were based on faulty assumptions and were simply not 
adequate.

[[Page 43243]]

    Response: Although it is true that the Navy's previous monitoring 
and mitigation measures were based on faulty assumptions and did not 
take TDFD into consideration, they have subsequently addressed the 
inadequacy and worked with NMFS to develop a series of more robust 
monitoring and mitigation measures to safeguard marine mammals from 
injury and mortality. The March 2011 SSTC incident is the only known 
mortality event ever documented from Navy underwater detonation 
training not only at SSTC, but also at all other areas in the Atlantic 
Ocean and Pacific Ocean where similar training has occurred over the 
past 30 years. Due to the low density and small zones of injury, the 
chance for injury and mortality is considered very low. In addition, 
the enhanced monitoring and mitigation measures discussed in Response 
to Comments above and in the supplemental Federal Register notice for 
the proposed IHA (77 FR 19231; March 30, 2012) should prevent any 
injury and mortality of marine mammals by underwater detonations 
training.
    Comment 14: One private citizen wrote against bombing.
    Response: Comments noted. However, this comment is irrelevant to 
the proposed issuance of an IHA to the Navy to take marine mammals 
incidental to its training exercises. Description of Marine Mammals in 
the Area of the Specified Activity.
    Common marine mammal species occurring regularly in the vicinity of 
the SSTC training area include the California sea lion (Zalophus 
californianus), Pacific harbor seal (Phoca vitulina richardsii), 
California coastal stock of bottlenose dolphin (Tursiops truncatus), 
and more infrequently gray whale (Eschrichtius robustus). Detailed 
descriptions of these species are provided in the Federal Register 
notice for the proposed IHA (75 FR 64276; October 19, 2010) and are not 
repeated here.
    In addition to these four common species, an additional four 
dolphin species: long-beaked common dolphin, short-beaked common 
dolphin, Pacific white-sided dolphin, and Risso's dolphin have been 
sighted in the vicinity of the SSTC training area, but much less 
frequently. None are listed as threatened or endangered under the 
Endangered Species Act (ESA). Detailed descriptions of these species 
are provided in the supplemental Federal Register notice for the 
proposed IHA (77 FR 19231; March 30, 2012) and are not repeated here.
    Further information on all the species can also be found in the 
NMFS Stock Assessment Reports (SAR). The Pacific 2011 SAR is available 
at: https://www.nmfs.noaa.gov/pr/pdfs/sars/po2011.pdf.

Potential Effects on Marine Mammals and Their Habitat

    Anticipated impacts resulting from the Navy's proposed SSTC 
training activities include disturbance from underwater detonation 
events and pile driving from the ELCAS events, if marine mammals are in 
the vicinity of these action areas.

Impacts from Anthropogenic Noise

    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). Since marine 
mammals depend on acoustic cues for vital biological functions, such as 
orientation, communication, finding prey, and avoiding predators, 
marine mammals that suffer from PTS or TTS will have reduced fitness in 
survival and reproduction, either permanently or temporarily. Repeated 
noise exposure that leads to TTS could cause PTS.
    Measured source levels from impact pile driving can be as high as 
214 dB re 1 [mu]Pa @ 1 m. Although no marine mammals have been shown to 
experience TTS or PTS as a result of being exposed to pile driving 
activities, experiments on a bottlenose dolphin (Tursiops truncates) 
and beluga whale (Delphinapterus leucas) 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. Although the source level of 
pile driving from one hammer strike is expected to be much lower than 
the single watergun impulse cited here, animals being exposed for a 
prolonged period to repeated hammer strikes could receive more noise 
exposure in terms of SEL than from the single watergun impulse 
(estimated at 188 dB re 1 [mu]Pa\2\-s) in the aforementioned experiment 
(Finneran et al. 2002).
    However, in order for marine mammals to experience TTS or PTS, the 
animals have to be close enough to be exposed to high intensity noise 
levels for a prolonged period of time. NMFS current standard mitigation 
for preventing injury from PTS and TTS is to require shutdown or power-
down of noise sources when a cetacean species is detected within the 
isopleths corresponding to SPL at received levels equal to or higher 
than 180 dB re 1 [mu]Pa (rms), or a pinniped species at 190 dB re 1 
[mu]Pa (rms). Based on the best scientific information available, these 
SPLs are far below the threshold that could cause TTS or the onset of 
PTS. Certain mitigation measures proposed by the Navy, discussed below, 
can effectively prevent the onset of TS in marine mammals, by 
establishing safety zones and monitoring safety zones during the 
training exercise.
    In addition, chronic exposure to excessive, though not high-
intensity, noise could cause masking at particular frequencies for 
marine mammals that utilize sound for vital biological functions. 
Masking could interfere with detection of acoustic signals such as 
communication calls, echolocation sounds, and environmental sounds 
important to marine mammals. Therefore, like TS, marine mammals whose 
acoustical sensors or environment are being masked are also impaired 
from maximizing their performance fitness in survival and reproduction.
    Masking occurs at the frequency band which the animals utilize. 
Therefore, since noise generated from the proposed underwater 
detonation and pile driving and removal is mostly concentrated at low 
frequency ranges, it may have less effect on high frequency 
echolocation sounds by dolphin species. However, 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. It may also affect communication signals when they occur near 
the noise band used by the animals and thus reduce the communication 
space of animals (e.g., Clark et al. 2009) and cause increased stress 
levels (e.g., Foote et al. 2004; Holt et al. 2009).
    Masking can potentially impact marine mammals at the individual, 
population, community, or even ecosystem levels (instead of individual 
levels caused by TS). Masking affects both senders and receivers of the 
signals and can potentially have long-term chronic effects on marine 
mammal species and populations in certain situations. Recent science 
suggests that low frequency ambient sound levels have increased by as 
much as 20 dB

[[Page 43244]]

(more than 3 times in terms of SPL) in the world's ocean from pre-
industrial periods, and most of these increases are from distant 
shipping (Hildebrand 2009). All anthropogenic noise sources, such as 
those from underwater explosions and pile driving, contribute to the 
elevated ambient noise levels and, thus intensify masking. However, 
single detonations are unlikely to contribute much to masking.
    Since all of the underwater detonation events and ELCAS events are 
planned in a very shallow water situation (wave length >> water depth), 
where low frequency propagation is not efficient, the noise generated 
from these activities is predominantly in the low frequency range and 
is not expected to contribute significantly to increased ocean ambient 
noise.
    Finally, exposure of marine mammals to certain sounds could lead to 
behavioral disturbance (Richardson et al. 1995). Behavioral responses 
to exposure to sound and explosions can range from no observable 
response to panic, flight and possibly more significant responses as 
discussed previously (Richardson et al. 1995; Southall et al. 2007). 
These responses include: 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) (Reviews by Richardson et al. 1995; Wartzok et al. 2003; Cox 
et al. 2006; Nowacek et al. 2007; Southall et al. 2007).
    The biological significance of many of these behavioral 
disturbances is difficult to predict, especially if the detected 
disturbances appear minor. However, the consequences of behavioral 
modification could be expected to be biologically significant if the 
change affects growth, survival, and reproduction. Some of these 
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, 
experience, demography) and is also difficult to predict (Southall et 
al. 2007).
    However, the proposed action area is not believed to be a prime 
habitat for marine mammals, nor is it considered an area frequented by 
marine mammals. Therefore, behavioral disturbances that could result 
from anthropogenic construction noise associated with the Navy's 
proposed training activities are expected to affect only a small number 
of marine mammals on an infrequent basis.

Impacts from Underwater Detonations at Close Range

    In addition to noise induced disturbances and harassment, marine 
mammals could be killed or injured by underwater explosions due to the 
impacts to air cavities, such as the lungs and bubbles in the 
intestines, from the shock wave (Elsayed 1997; Elsayed and Gorbunov 
2007). The criterion for mortality and non-auditory injury used in MMPA 
take authorization is the onset of extensive lung hemorrhage and slight 
lung injury or ear drum rupture, respectively (see Table 3). Extensive 
lung hemorrhage is considered debilitating and potentially fatal as a 
result of air embolism or suffocation. In the Incidental Harassment 
Authorization application, all marine mammals within the calculated 
radius for 1% probability of onset of extensive lung injury (i.e., 
onset of mortality) were counted as lethal exposures. The range at 
which 1% probability of onset of extensive lung hemorrhage is expected 
to occur is greater than the ranges at which 50% to 100% lethality 
would occur from closest proximity to the charge or from presence 
within the bulk cavitation region. (The region of bulk cavitation is an 
area near the surface above the detonation point in which the reflected 
shock wave creates a region of cavitation within which smaller animals 
would not be expected to survive). Because the range for onset of 
extensive lung hemorrhage for smaller animals exceeds the range for 
bulk cavitation and all more serious injuries, all smaller animals 
within the region of cavitation and all animals (regardless of body 
mass) with more serious injuries than onset of extensive lung 
hemorrhage are accounted for in the lethal exposures estimate. The 
calculated maximum ranges for onset of extensive lung hemorrhage depend 
upon animal body mass, with smaller animals having the greatest 
potential for impact, as well as water column temperature and density.
    However, due to the small detonation that would be used in the 
proposed SSTC training activities and the resulting small safety zones 
to be monitored and mitigated for marine mammals in the vicinity of the 
proposed action area, NMFS concluded it is unlikely that marine mammals 
would be killed or injured by underwater detonations.

Impact from Detonations with TDFDs

    As mentioned earlier, a TDFD begins a countdown to a detonation 
event with a time-delaying device, and there is no mechanism to stop 
(abort) the pre-set explosion once the device has been set. Therefore, 
in the absence of any additional mitigation, the potential danger 
exists in the scenario that during the brief period after the exclusion 
zone is cleared and before the charges are detonated, marine mammals 
could enter the exclusion zone and approach close enough to the 
explosive to be injured or killed upon detonation. Nevertheless, the 
anticipated level of impacts to marine mammals without any mitigation 
and monitoring measures, which is assessed solely based on the density 
and distribution of the animals within the vicinity of the action, 
remains the same as analyzed in the original proposed IHA (75 FR 64276; 
October 19, 2010).

Impact Criteria and Thresholds

    The effects of an at-sea explosion or pile driving on a marine 
mammal depends on many factors, including the size, type, and depth of 
both the animal and the explosive charge/pile being driven; the depth 
of the water column; the standoff distance between the charge/pile and 
the animal; and the sound propagation properties of the environment. 
Potential impacts can range from brief acoustic effects (such as 
behavioral disturbance), tactile perception, physical discomfort, 
slight injury of the internal organs and the auditory system, to death 
of the animal (Yelverton et al. 1973; O'Keeffe and Young 1984; DoN 
2001). Non-lethal injury includes slight injury to internal organs and 
the auditory system; however, delayed lethality can be a result of 
individual or cumulative sub-lethal injuries (DoN 2001). Short-term or 
immediate lethal injury would result from massive combined trauma to

[[Page 43245]]

internal organs as a direct result of proximity to the point of 
detonation or pile driving (DoN 2001).
    This section summarizes the marine mammal impact criteria used for 
the subsequent modeled calculations. Several standard acoustic metrics 
(Urick 1983) are used to describe the thresholds for predicting 
potential physical impacts from underwater pressure waves:
     Total energy flux density or Sound Exposure Level (SEL). 
For plane waves (as assumed here), SEL is the time integral of the 
instantaneous intensity, where the instantaneous intensity is defined 
as the squared acoustic pressure divided by the characteristic 
impedance of sea water. Thus, SEL is the instantaneous pressure 
amplitude squared, summed over the duration of the signal and has dB 
units referenced to 1 re [micro]Pa\2\-s.
     1/3-octave SEL. This is the SEL in a 1/3-octave frequency 
band. A 1/3-octave band has upper and lower frequency limits with a 
ratio of 21:3, creating bandwidth limits of about 23 percent of center 
frequency.
     Positive impulse. This is the time integral of the initial 
positive pressure pulse of an explosion or explosive-like wave form. 
Standard units are Pa-s, but psi-ms also are used.
     Peak pressure. This is the maximum positive amplitude of a 
pressure wave, dependent on charge mass and range. Units used here are 
psi, but other units of pressure, such as [micro]Pa and Bar, also are 
used.
1. Harassment Threshold for Sequential Underwater Detonations
    There may be rare occasions when sequential underwater detonations 
are part of a static location event. Sequential detonations are more 
than one detonation within a 24-hour period in a geographic location 
where harassment zones overlap. For sequential underwater detonations, 
accumulated energy over the entire training time is the natural 
extension for energy thresholds since energy accumulates with each 
subsequent shot.
    For sequential underwater detonations, the acoustic criterion for 
behavioral harassment is used to account for behavioral effects 
significant enough to be judged as harassment, but occurring at lower 
sound energy levels than those that may cause TTS. The behavioral 
harassment threshold is based on recent guidance from NMFS (NMFS 2009a; 
2009b) for the energy-based TTS threshold. The research on pure tone 
exposures reported in Schlundt et al. (2000) and Finneran and Schlundt 
(2004) provided the pure-tone threshold of 192 dB as the lowest TTS 
value. The resulting TTS threshold for explosives is 182 dB re 1 
[micro]Pa\2\-s in any \1/3\ octave band. As reported by Schlundt et al. 
(2000) and Finneran and Schlundt (2004), instances of altered behavior 
in the pure tone research generally began 5 dB lower than those causing 
TTS. The behavioral harassment threshold is therefore derived by 
subtracting 5 dB from the 182 dB re 1 [micro]Pa\2\-s in any \1/3\ 
octave band threshold, resulting in a 177 dB re 1 [mu]Pa\2\-s 
behavioral disturbance harassment threshold for multiple successive 
explosives (Table 3).
2. Criteria for ELCAS Pile Driving and Removal
    Since 1997, NMFS has been using generic sound exposure thresholds 
to determine when an activity in the ocean that produces impact sound 
(i.e., pile driving) results in potential take of marine mammals by 
harassment (70 FR 1871). Current NMFS criteria (70 FR 1871) regarding 
exposure of marine mammals to underwater sounds is that cetaceans 
exposed to sound pressure levels (SPLs) of 180 dB root mean squared 
(dBrms in units of dB re 1 [micro]Pa) or higher and 
pinnipeds exposed to 190 dBrms or higher are considered to 
have been taken by Level A (i.e., injurious) harassment. Marine mammals 
(cetaceans and pinnipeds) exposed to impulse sounds (e.g., impact pile 
driving) of 160 dBrms but below Level A thresholds (i.e., 
180 or 190 dB) are considered to have been taken by Level B behavioral 
harassment. Marine mammals (cetaceans and pinnipeds) exposed to non-
impulse noise (e.g., vibratory pile driving) at received levels of 120 
dB RMS or above are considered to have been taken by Level B behavioral 
harassment (Table 1).

   Table 1--Effects Criteria for Underwater Detonations and ELCAS Pile
                             Driving/Removal
------------------------------------------------------------------------
           Criterion             Criterion definition       Threshold
------------------------------------------------------------------------
                      Underwater Explosive Criteria
------------------------------------------------------------------------
Mortality.....................  Onset of severe lung    30.5 psi-ms
                                 injury (1%              (positive
                                 probability of          impulse)
                                 mortality).
Level A Harassment (Injury)...  Slight lung injury; or  13.0 psi-ms
                                                         (positive
                                                         impulse)
                                50% of marine mammals   205 dB re 1
                                 would experience ear    [mu]Pa\2\-s
                                 drum rupture; and 30%   (full spectrum
                                 exposed sustain PTS.    energy)
Level B Harassment............  TTS (dual criteria)...  23 psi (peak
                                                         pressure;
                                                         explosives
                                                         <2,000 lbs), or
                                                        182 dB re 1
                                                         [mu]Pa\2\-s
                                                         (peak \1/3\
                                                         octave band)
                                (sequential             177 dB re 1
                                 detonations only).      [mu]Pa\2\-s
------------------------------------------------------------------------
                      Pile Driving/Removal Criteria
------------------------------------------------------------------------
Level A Harassment............  Pinniped only: PTS      190 dBrms re 1
                                 caused by repeated      [mu]Pa
                                 exposure to received
                                 levels that cause TTS.
                                Cetacean only: PTS      180 dBrms re 1
                                 caused by repeated      [mu]Pa
                                 exposure to received
                                 levels that cause TTS.
Level B Behavioral Harassment.  Impulse noise:          160 dBrms re 1
                                 Behavioral              [mu]Pa
                                 modification of
                                 animals.
                                Non-impulse noise:      190 dBrms re 1
                                 Behavioral              [mu]Pa
                                 modification of
                                 animals.
------------------------------------------------------------------------

Assessing Harassment from Underwater Detonations

    Underwater detonations produced during SSTC training events 
represent a single, known source. Chemical explosives create a bubble 
of expanding gases as the material burns. The bubble can oscillate 
underwater or, depending on charge-size and depth, be vented to the 
surface in which case there is no bubble-oscillation with its 
associated low-frequency energy. Explosions

[[Page 43246]]

produce very brief, broadband pulses characterized by rapid rise-time, 
great zero-to-peak pressures, and intense sound, sometimes described as 
impulse. Close to the explosion, there is a very brief, great-pressure 
acoustic wave-front. The impulse's rapid onset time, in addition to 
great peak pressure, can cause auditory impacts, although the brevity 
of the impulse can include less SEL than expected to cause impacts. The 
transient impulse gradually decays in magnitude as it broadens in 
duration with range from the source. The waveform transforms to 
approximate a low-frequency, broadband signal with a continuous sound 
energy distribution across the spectrum. In addition, underwater 
explosions are relatively brief, transitory events when compared to the 
existing ambient noise within the San Diego Bay and at the SSTC.
    The impacts of an underwater explosion to a marine mammal are 
dependent upon multiple factors including the size, type, and depth of 
both the animal and the explosive. Depth of the water column and the 
distance from the charge to the animal also are determining factors as 
are boundary conditions that influence reflections and refraction of 
energy radiated from the source. The severity of physiological effects 
generally decreases with decreasing exposure (impulse, sound exposure 
level, or peak pressure) and/or increasing distance from the sound 
source. The same generalization is not applicable for behavioral 
effects, because they do not depend solely on sound exposure level. 
Potential impacts can range from brief acoustic effects, tactile 
perception, and physical discomfort to both lethal and non-lethal 
injuries. Disturbance of ongoing behaviors could occur as a result of 
non-injurious physiological responses to both the acoustic signature 
and shock wave from the underwater explosion. Non-lethal injury 
includes slight injury to internal organs and auditory system. The 
severity of physiological effects generally decreases with decreasing 
sound exposure and/or increasing distance from the sound source. 
Injuries to internal organs and the auditory system from shock waves 
and intense impulsive noise associated with explosions can be 
exacerbated by strong bottom-reflected pressure pulses in reverberant 
environments (Gaspin 1983; Ahroon et al. 1996). Nevertheless, the 
overall size of the explosives used at the SSTC is much smaller than 
those used during larger Fleet ship and aircraft training events.
    All underwater detonations proposed for SSTC were modeled as if 
they will be conducted in shallow water of 24 to 72 feet, including 
those that would normally be conducted in very shallow water (VSW) 
depths of zero to 24 feet. Modeling in deeper than actual water depths 
causes the modeled results to be more conservative (i.e., it 
overestimates propagation and potential exposures) than if the 
underwater detonations were modeled at their actual, representative 
depths when water depth is less than 24 feet.
    The Navy's underwater explosive effects simulation requires six 
major process components:
     A training event description including explosive type;
     Physical oceanographic and geoacoustic data for input into 
the acoustic propagation model representing seasonality of the planned 
operation;
     Biological data for the area including density (and 
multidimensional animal movement for those training events with 
multiple detonations);
     An acoustic propagation model suitable for the source type 
to predict impulse, energy, and peak pressure at ranges and depths from 
the source;
     The ability to collect acoustic and animal movement 
information to predict exposures for all animals during a training 
event (dosimeter record); and
     The ability for post-operation processing to evaluate the 
dosimeter exposure record and calculate exposure statistics for each 
species based on applicable thresholds.
    An impact model, such as the one used for the SSTC analysis, 
simulates the conditions present based on location(s), source(s), and 
species parameters by using combinations of embedded models (Mitchell 
et al. 2008). The software package used for SSTC consists of two main 
parts: an underwater noise model and bioacoustic impact model (Lazauski 
et al. 1999; Lazauski and Mitchell 2006; Lazauski and Mitchell 2008).
    Location-specific data characterize the physical and biological 
environments while exercise-specific data construct the training 
operations. The quantification process involves employment of modeling 
tools that yield numbers of exposures for each training operation.
    During modeling, the exposures are logged in a time-step manner by 
virtual dosimeters linked to each simulated animal. After the operation 
simulation, the logs are compared to exposure thresholds to produce raw 
exposure statistics. It is important to note that dosimeters only were 
used to determine exposures based on energy thresholds, not impulse or 
peak pressure thresholds. The analysis process uses quantitative 
methods and identifies immediate short-term impacts of the explosions 
based on assumptions inherent in modeling processes, criteria and 
thresholds used, and input data. The estimations should be viewed with 
caution, keeping in mind that they do not reflect measures taken to 
avoid these impacts (i.e., mitigations). Ultimately, the goals of this 
acoustic impact model were to predict acoustic propagation, estimate 
exposure levels, and reliably predict impacts.
    Predictive sound analysis software incorporates specific 
bathymetric and oceanographic data to create accurate sound field 
models for each source type. Oceanographic data such as the sound speed 
profiles, bathymetry, and seafloor properties directly affect the 
acoustic propagation model. Depending on location, seasonal variations, 
and the oceanic current flow, dynamic oceanographic attributes (e.g., 
sound speed profile) can change dramatically with time. The sound field 
model is embedded in the impact model as a core feature used to analyze 
sound and pressure fields associated with SSTC underwater detonations.
    The sound field model for SSTC detonations was the Reflection and 
Refraction in Multilayered Ocean/Ocean Bottoms with Shear Wave Effects 
(REFMS) model (version 6.03). The REFMS model calculates the combined 
reflected and refracted shock wave environment for underwater 
detonations using a single, generalized model based on linear wave 
propagation theory (Cagniard 1962; Britt 1986; Britt et al. 1991).
    The model outputs include positive impulse, sound exposure level 
(total and in 1/3-octave bands) at specific ranges and depths of 
receivers (i.e., marine mammals), and peak pressure. The shock wave 
consists of two parts, a very rapid onset ``impulsive'' rise to 
positive peak over-pressure followed by a reflected negative under-
pressure rarefaction wave. Propagation of shock waves and sound energy 
in the shallow-water environment is constrained by boundary conditions 
at the surface and seafloor.
    Multiple locations (in Boat Lanes and Echo area) and charge depths 
were used to determine the most realistic spatial and temporal 
distribution of detonation types associated with each training 
operation for a representative year. Additionally, the effect of sound 
on an animal depends on many factors including:
     Properties of the acoustic source(s): source level (SL), 
spectrum, duration, and duty cycle;

[[Page 43247]]

     Sound propagation loss from source to animal, as well as, 
reflection and refraction;
     Received sound exposure measured using well-defined 
metrics;
     Specific hearing;
     Exposure duration; and
     Masking effects of background and ambient noise.
    To estimate exposures sufficient to be considered injury or 
significantly disrupt behavior by affecting the ability of an 
individual animal to grow (e.g., feeding and energetics), survive 
(e.g., behavioral reactions leading to injury or death, such as 
stranding), reproduce (e.g., mating behaviors), and/or degrade habitat 
quality resulting in abandonment or avoidance of those areas, 
dosimeters were attached to the virtual animals during the simulation 
process. Propagation and received impulse, SEL, and peak pressure are a 
function of depth, as well as range, depending on the location of an 
animal in the simulation space.
    A detailed discussion of the computational process for the 
modeling, which ultimately generates two outcomes--the zones of 
influence (ZOIs) and marine mammal exposures, is presented in the 
Navy's IHA application.
    Severity of an effect often is related to the distance between the 
sound source and a marine mammal and is influenced by source 
characteristics (Richardson and Malme 1995). For SSTC, ZOIs were 
estimated for the different charge weights, charge depths, water 
depths, and seasons using the REFMS model as described previously. 
These ZOIs for SSTC underwater detonations by training event are shown 
in Table 2, which was updated from Table 4 in the Federal Register 
notice (75 FR 64276; October 19, 2010) for the proposed IHA. This 
change is merely a correction of erroneous table values. The Navy 
impact modeling used the correct propagation ZOIs and effects in their 
marine mammal exposure estimates, so the table change does not change 
any effects analysis presented in the Federal Register notice (75 FR 
64276; October 19, 2010) for the proposed IHA. One correction is 
changing the 23 psi table entry (for the Marine Mammal systems 29-lb 
NEW event) to 490 yards. Since the proposed mitigation zone is based on 
the maximum ZOI under the dual TTS criteria, this revision changed from 
the previous maximum of 470 yards to 490 yards, an addition of 20 
yards. In addition, Table 2 added a column that shows the ZOIs for sub-
TTS behavioral harassment.
    For single detonations, the ZOIs were calculated using the range 
associated with the onset of TTS based on the Navy REFMS model 
predictions.
BILLING CODE 3510-22-P

[[Page 43248]]

[GRAPHIC] [TIFF OMITTED] TN24JY12.000

BILLING CODE 3510-22-C
    For Multiple Successive Explosive events (i.e., sequential 
detonations), the ZOI calculation was based on the range to non-TTS 
behavior disruption. Calculating the zones of influence in terms of 
total SEL, 1/3-octave bands SEL, impulse, and peak pressure for 
sequential (10 sec timed) and multiple controlled detonations (>30 
minutes)

[[Page 43249]]

was slightly different than for the single detonations. For the 
sequential detonations, ZOI calculations considered spatial and 
temporal distribution of the detonations, as well as the effective 
accumulation of the resultant acoustic energy. To calculate the ZOI, 
sequential detonations were modeled such that explosion SEL were summed 
incoherently to predict zones while peak pressure was not.
    In summary, all ZOI radii were strongly influenced by charge size 
and placement in the water column, and only slightly by the 
environmental variables.

Very Shallow Water (VSW) Underwater Detonations Live-Fire Tests ZOI 
Determination

    Measurements of the propagated pressures during single-charge 
underwater detonation exercises in VSW at SSTC (and San Clemente 
Island) were conducted in 2002 as part of a study to evaluate existing 
underwater explosive propagation models for application to VSW 
conditions (unpublished, Naval Special Warfare Center/Anteon 
Corporation 2005, cited in the Navy's SSTC IHA Application). The direct 
measurements made in those tests provided an in-place characterization 
of pressure propagation for the training exercises as they are actually 
conducted at the SSTC. During the tests, 2 and 15 lbs charges of NEW 
explosives were detonated in 6 and 15 feet of water with charges laying 
on the bottom or two feet off the bottom at SSTC and San Clemente 
Island. At SSTC, swell conditions precluded detonations at the 6-foot 
depth. Peak-pressures (unfiltered) and energies--between 100 Hz and 41 
kHz--in 1/3-octave bands of highest energies from each detonation were 
measured in three locations relative to the charges: (1) 5-10 feet 
seaward of the charge, (2) 280-540 feet seaward, and (3) at about 1,000 
feet seaward. Underwater detonations of small 2 lb charges at SSTC were 
measured at a ``near range'' location within feet of the charge and at 
a ``single far range'' of 525 feet from the charge (unpublished, Naval 
Special Warfare Center/Anteon Corporation 2005, cited in the Navy's 
SSTC IHA Application 2010). In the tests, the position of single 
charges--on and 2 feet off the bottom--affected the propagated peak-
pressures. Off-bottom charges produced consistently greater peak-
pressures than on-bottom charges as measured at about 200, 500, and 
1,000 feet distances. Off-bottom 15 lb charges in 15 feet of water 
produced between 43-67% greater peak-pressures than on-bottom charges. 
Greater differences were found when detonations occurred in extremely 
shallow depths of 6 feet at San Clemente Island (unpublished, Naval 
Special Warfare Center/Anteon Corporation 2005, cited in the Navy's 
SSTC IHA Application 2010). Generally, measurements during single-
charge exercises produced empirical data that were predicted by the 
propagation models. At about 1,000 feet seaward, peak-pressure varied 
from 11-17 pounds psi at different depths, and energies between 100 Hz 
and 41 kHz in the 1/3-octave bands of highest energies varied from 
about 175-186 dB re 1 [mu]Pa\2\-s at different depths. From the 
measurements, it was determined that the range at which the criterion 
for onset-TTS would be expected to occur in small odontocetes matched 
the range predicted by a conservative model of propagation that assumed 
a boundary-less medium and equal sound velocity at all depths in the 
range--i.e., an ``iso-velocity'' model. Bottom and water-column 
conditions also influence pressure-wave propagation and dissipation of 
blast residues.
    In comparison, predictions made by the Navy's REFMS model (see 
above) were found to be unstable across the distances considered under 
the conditions of VSW with bottom or near bottom charge placement, 
reflective bottom, and a non-refractive water column (i.e., equal sound 
velocity at all depths). The source of instability in the REFMS 
predictions is most likely due to the nature of the VSW zone wherein 
the ratio of depth to range is very small--a known problem for the 
REFMS' predictive ray-tracing. Therefore, the determination of ZOIs 
within the VSW zones was based on the empirical propagation data and 
iso-velocity model predictions discussed above for charge-weights of 20 
lbs or less of NEW explosive on the bottom and for charge-weights of 
3.6 lbs or less off the bottom. For SSTC this range was determined to 
be a 1,200-foot (400-yard) radius out from the site of the detonation 
with the shoreward half of the implied circle being truncated by the 
shoreline and extremely shallow water immediately off shore.

Assessing ELCAS Pile Driving and Removal Impacts

    Noise associated with ELCAS training includes loud impulsive sounds 
derived from driving piles into the soft sandy substrate of the SSTC 
waters to temporarily support a causeway of linked pontoons. Two 
hammer-based methods will be used to install/remove ELCAS piles: impact 
pile driving for installation and vibratory driving for removal. The 
impact hammer is a large metal ram attached to a crane. A vertical 
support holds the pile in place and the ram is dropped or forced 
downward. The energy is then transferred to the pile which is driven 
into the seabed. The ram is typically lifted by a diesel power source.
    The methodology for analyzing potential impacts from ELCAS events 
is similar to that of analyzing explosives. The ELCAS analysis includes 
two steps used to calculate potential exposures:
     Estimate the zone of influence for Level A injurious and 
Level B behavioral exposures for both impact pile driving and vibratory 
pile removal using the practical spreading loss equation (CALTRANS 
2009).
     Estimate the number of species exposed using species 
density estimates and estimated zones of influence.
    The practical spreading loss equation is typically used to estimate 
the attenuation of underwater sound over distance. The formula for this 
propagation loss can be expressed as:
TL = F * log (D1/D2)

Where:

TL = transmission loss (the sound pressure level at distance D1 
minus the sound pressure level at distance D2 from the source, in 
dBrms re 1 [mu]Pa)
F = attenuation constant
D1 = distance at which the targeted transmission loss occurs
D2 = distance from which the transmission loss is calculated

    The attenuation constant (F) is a site-specific factor based on 
several conditions, including water depth, pile type, pile length, 
substrate type, and other factors. Measurements conducted by the 
California Department of Transportation (CADOT) and other consultants 
(Greeneridge Science) indicate that the attenuation constant (F) can 
vary from 5 to 30. Small-diameter steel H-type piles have been found to 
have high F values in the range of 20 to 30 near the pile (i.e., 
between 30-60 feet) (CALTRANS 2009). In the absence of empirically 
measured values at SSTC, NMFS and the Navy worked to set the F value 
for SSTC to be on the low (conservative, and more predictive) end of 
the small-diameter steel piles at F = 15, to indicate that the 
spreading loss is between the spherical (F = 20) and cylindrical (F = 
10).
    Actual noise source levels of ELCAS pile driving at SSTC depend on 
the type of hammer used, the size and material of the pile, and the 
substrate the piles are being driven into. Using known equipment, 
installation procedures, and applying certain constants derived from 
other west coast measured pile driving, predicted underwater sound 
levels from ELCAS pile driving can be calculated.

[[Page 43250]]

The ELCAS uses 24-inch diameter hollow steel piles, installed using a 
diesel impact hammer to drive the piles into the sandy on-shore and 
near-shore substrate at SSTC. For a dock repair project in Rodeo, 
California in San Francisco Bay, underwater sound pressure level (SPL) 
for a 24-inch steel pipe pile driven with a diesel impact hammer in 
less than 15 ft of water depth was measured at 189 dBrms re 
1 [mu]Pa from approximately 33 ft (11 yards) away. SPL for the same 
type and size pile also driven with a diesel impact hammer, but in 
greater than 36 ft of water depth, was measured to be 190 to 194 
dBrms during the Amoco Wharf repair project in Carquinez 
Straits, Martinez, California (CADOT 2009). The areas where these 
projects were conducted have a silty sand bottom with an underlying 
hard clay layer, which because of the extra effort required to drive 
into clay, would make these measured pile driving sound levels louder 
(more conservative) than they would if driving into SSTC's sandy 
substrate. Given the local bathymetry and smooth sloping sandy bottom 
at SSTC, ELCAS piles will generally be driven in water depths of 36 ft 
or less.
    Therefore, for the purposes of the Navy's SSTC ELCAS analysis, both 
the Rodeo repair project (189 dBrms) and the low end of the 
measured values of the Amoco Wharf repair projects (190 
dBrms) are considered to be reasonably representative of 
sound levels that would be expected during ELCAS pile driving at SSTC. 
For hollow steel piles of similar size as those proposed for the ELCAS 
(<24-in diameter) used in Washington State and California pile driving 
projects, the broadband frequency range of underwater sound was 
measured between 50 Hz to 10.5 kHz with highest energy at frequencies 
<1 to 3 kHz (CALTRANS 2009). Although frequencies over 10.5 kHz are 
likely present during these pile driving projects, they are generally 
not typically measured since field data has shown a decrease in SPL to 
less than 120 dB at frequencies greater than 10.5 kHz (Laughlin 2005; 
2007). It is anticipated that ELCAS pile driving would generate a 
similar sound spectra.
    For ELCAS training events, using an estimated SPL measurement of 
190 dBrms re 1 [mu]Pa at 11 yards as described above, the 
circular ZOIs surrounding a 24-inch steel diesel-driven ELCAS pile can 
be estimated via the practical spreading loss equation to have radii 
of:
     11 yards for Level A injurious harassment for pinnipeds 
(190 dBrms);
     46 yards for Level A injurious harassment for cetaceans 
(180 dBrms), and
     1,094 yards for the Level B behavioral harassment (160 
dBrms).
    It should be noted that ELCAS pier construction starts with piles 
being driven near the shore and extends offshore. Near the shore, the 
area of influence would be a semi-circle and towards the end of the 
ELCAS (approximately 1,200 feet or 400 yards from the shore) would be a 
full circle. The above calculated area of influence conservatively 
assumes that all ELCAS piles are driven offshore at SSTC, producing a 
circular zone of influence, and discounts the limited propagation from 
piles driven closer to shore.
    Noise levels derived from piles removed via vibratory extractor are 
different than those driven with an impact hammer. Steel pilings and a 
vibratory driver were used for pile driving at the Port of Oakland 
(CALTRANS 2009). Underwater SPLs during this project for a 24-inch 
steel pile in 36 ft of water depth at a distance of 11 yards (33 feet) 
from the source was field measured to be 160 dBrms. The area 
where this project was conducted (Oakland) has a harder substrate, 
which because of the extra effort required to drive and remove the 
pile, would make these measured pile driving sound levels louder (more 
conservative) than they would if driving and removing into and from 
SSTC's sandy substrate. Conservatively using this SPL measurement for 
SSTC and F = 15, the ZOIs for a 24-inch steel pile removed via a 
vibratory extractor out to different received SPLs can be estimated via 
the practical spreading loss equation to be:
     < 1 yard for Level A injurious harassment for pinnipeds 
(190 dBrms);
     One (1) yard for Level A injurious harassment for 
cetaceans (180 dBrms), and
     5,076 yards for Level B behavioral harassment (120 
dBrms).
    As discussed above, the calculated area of influence conservatively 
assumes that all ELCAS piles are driven and subsequently removed 
offshore at SSTC, producing a circular zone of influence.

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 Navy's proposed SSTC training activities, NMFS worked with 
the Navy and developed the following mitigation measures to minimize 
the potential impacts to marine mammals in the project vicinity as a 
result of the underwater detonations (including detonations with TDFDs) 
and ELCAS pile driving/removal events.

Mitigation Measures for Underwater Detonations

    (A) Mitigation and Monitoring Measures for Underwater Detonations 
in Very Shallow Water (VSW, water depth < 24 ft)

(1) Mitigation and Monitoring Measures for VSW Underwater Detonations 
Using Positive Control

    1. Underwater detonations using positive control (remote firing 
devices) will only be conducted during daylight.
    2. Easily visible anchored floats will be positioned on 700 yard 
radius of a roughly semi-circular zone (the shoreward half being 
bounded by shoreline and immediate off- shore water) around the 
detonation location for small explosive exercises at the SSTC. These 
mark the outer limits of the mitigation zone.
    3. For each VSW underwater detonation event, a safety-boat with a 
minimum of one observer is launched 30 or more minutes prior to 
detonation and moves through the area around the detonation site. The 
task of the safety observer is to exclude humans from coming into the 
area and to augment a shore observer's visual search of the mitigation 
zone for marine mammals. The safety-boat observer is in constant radio 
communication with the exercise coordinator and shore observer 
discussed below.
    4. A shore-based observer will also be deployed for VSW detonations 
in addition to boat based observers. The shore observer will indicate 
that the area is clear of marine mammals after 10 or more minutes of 
continuous observation with no marine mammals having been seen in the 
mitigation zone or moving toward it.
    5. At least 10 minutes prior to the planned initiation of the 
detonation event- sequence, the shore observer, on an elevated on-shore 
position, begins a continuous visual search with binoculars of the 
mitigation zone. At this time, the safety-boat observer informs the 
shore observer if any marine mammal has been seen in the zone and, 
together, both search the surface within and beyond the mitigation zone 
for marine mammals.
    6. The observers (boat and shore based) will indicate that the area 
is not

[[Page 43251]]

clear any time a marine mammal is sighted in the mitigation zone or 
moving toward it and, subsequently, indicate that the area is clear of 
marine mammals when the animal is out and moving away and no other 
marine mammals have been sited.
    7. Initiation of the detonation sequence will only begin on final 
receipt of an indication from the shore observer that the area is clear 
of marine mammals and will be postponed on receipt of an indication 
from any observer that the area is not clear of marine mammals.
    8. Following the detonation, visual monitoring of the mitigation 
zone continues for 30 minutes for the appearance of any marine mammal 
in the zone. Any marine mammal appearing in the area will be observed 
for signs of possible injury.
    9. Any marine mammal observed after a VSW underwater detonation 
either injured or exhibiting signs of distress will be reported via 
operational chain of command to Navy environmental representatives from 
U.S. Pacific Fleet, Environmental Office, San Diego Detachment. Using 
Marine Mammal Stranding communication trees and contact procedures 
established for the Southern California Range Complex, the Navy will 
report these events to the Stranding Coordinator of NMFS' Southwest 
Regional Office. These voice or email reports will contain the date and 
time of the sighting, location (or if precise latitude and longitude is 
not currently available, then the approximate location in reference to 
an established SSTC beach feature), species description (if known), and 
indication of the animal's status.

(2) Mitigation and Monitoring Measures for VSW Underwater Detonations 
Using Time-Delay (TDFD Only)

    1. Underwater detonations using timed delay devices will only be 
conducted during daylight.
    2. Time-delays longer than 10 minutes will not be used. The 
initiation of the device will not start until the mitigation area below 
is clear for a full 30 minutes prior to initiation of the timer.
    3. A mitigation zone will be established around each underwater 
detonation location as indicated in Table 3 (1,000 or 1,400 yards) 
based on charge weight and length of time delay used.

 Table 3--Updated Buffer Zone Radius (yd) for TDFDs Based on Size of Charge and Length of Time-Delay, with Additional Buffer Added to Account for Faster
                                                                       Swim Speeds
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                Time-delay
                                                --------------------------------------------------------------------------------------------------------
                                                       5 min             6 min             7 min            8 min            9 min            10 min
--------------------------------------------------------------------------------------------------------------------------------------------------------
Charge Size (lb NEW).........  5 lb............  1,000 yd........  1,000 yd........  1,000 yd........  1,000 yd.......  1,400 yd.......  1,400 yd
                               10 lb...........  1,000 yd........  1,000 yd........  1,000 yd........  1,400 yd.......  1,400 yd.......  1,400 yd
                               15-29 lb........  1,000 yd........  1,400 yd........  1,400 yd........  1,400 yd.......  1,500 yd.......  1,500 yd
--------------------------------------------------------------------------------------------------------------------------------------------------------

    4. VSW ranges 1,000 yds:
     For each VSW underwater detonation event with a mitigation 
zone of 1,000 yds, a safety boat with a minimum of one observer is 
launched 30 or more minutes prior to detonation and moves through the 
area around the detonation site at the seaward edge of the mitigation 
zone. The task of the boat is to exclude humans from coming into the 
area and to augment a shore observer's visual search of the mitigation 
zone for marine mammals. The safety-boat observer is in constant radio 
communication with the exercise coordinator and shore observer 
discussed below. To the best extent practical, boats will try to 
maintain a 10 knot search speed.
     A shore-based observer will also be deployed for VSW 
detonations in addition to boat based observers. At least 10 minutes 
prior to the planned initiation of the detonation event-sequence, the 
shore observer, on an elevated on-shore position, begins a continuous 
visual search with binoculars of the mitigation zone. At this time, the 
safety-boat observer informs the shore observer if any marine mammal 
has been seen in the zone and, together, both search the surface within 
and beyond the mitigation zone for marine mammals. The shore observer 
will indicate that the area is clear of marine mammals after 10 or more 
minutes of continuous observation with no marine mammals having been 
seen in the mitigation zone or moving toward it.
    5. VSW ranges larger than 1,400 yards:
     A minimum of 2 boats will be used to survey for marine 
mammals at mitigation ranges larger than 1,400 yards.
     When conducting the surveys within a mitigation zone 
>1,400 yds, boats will position themselves near the mid-point of the 
mitigation zone radius (but always outside the detonation plume radius/
human safety zone) and travel in a semi-circular pattern around the 
detonation location surveying both the inner (toward detonation site) 
and outer (away from detonation site) areas. When using 2 boats, each 
boat will be positioned on opposite sides of the detonation location, 
separated by 180 degrees. If using more than 2 boats, each boat will be 
positioned equidistant from one another (120 degrees separation for 3 
boats, 90 degrees separation for 4 boats, etc.). If available, aerial 
visual survey support from Navy helicopters can be utilized, so long as 
it will not jeopardize safety of flight. Helicopters will travel in a 
circular pattern around the detonation location.
    6. A mitigation zone will be surveyed from 30 minutes prior to the 
detonation and for 30 minutes after the detonation.
    7. Other personnel besides boat observers can also maintain 
situational awareness on the presence of marine mammals within the 
mitigation zone to the best extent practical given dive safety 
considerations.
    Divers placing the charges on mines will observe the immediate 
underwater area around a detonation site for marine mammals and report 
sightings to surface observers.
    8. If a marine mammal is sighted within an established mitigation 
zone or moving towards it, underwater detonation events will be 
suspended until the marine mammal has voluntarily left the area and the 
area is clear of marine mammals for at least 30 minutes.
    9. Immediately following the detonation, visual monitoring for 
affected marine mammals within the mitigation zone will continue for 30 
minutes.
    10. Any marine mammal observed after an underwater detonation 
either injured or exhibiting signs of distress will be reported via 
Navy operational chain of command to Navy

[[Page 43252]]

environmental representatives from U.S. Pacific Fleet, Environmental 
Office, San Diego Detachment. Using Marine Mammal Stranding 
communication trees and contact procedures established for the Southern 
California Range Complex, the Navy will report these events to the 
Stranding Coordinator of NMFS' Southwest Regional Office. These voice 
or email reports will contain the date and time of the sighting, 
location (or if precise latitude and longitude is not currently 
available, then the approximate location in reference to an established 
SSTC beach feature), species description (if known), and indication of 
the animal's status.
(B) Mitigation and Monitoring Measures for Underwater Detonations in 
Shallow Water (>24 Feet)

(1) Mitigation and Monitoring Measures for Underwater Detonations Using 
Positive Control (Except SWAG and Timed Detonations)

    1. Underwater detonations using positive control devices will only 
be conducted during daylight.
    2. A mitigation zone of 700 yards will be established around each 
underwater detonation point.
    3. A minimum of two boats, including but not limited to small 
zodiacs and 7-m Rigid Hulled Inflatable Boats (RHIB) will be deployed. 
One boat will act as an observer platform, while the other boat is 
typically the diver support boat.
    4. Two observers with binoculars on one small craft/boat will 
survey the detonation area and the mitigation zone for marine mammals 
from at least 30 minutes prior to commencement of the scheduled 
explosive event and until at least 30 minutes after detonation.
    5. In addition to the dedicated observers, all divers and boat 
operators engaged in detonation events can potentially monitor the area 
immediately surrounding the point of detonation for marine mammals.
    6. If a marine mammal is sighted within the 700 yard mitigation 
zone or moving towards it, underwater detonation events will be 
suspended until the marine mammal has voluntarily left the area and the 
area is clear of marine mammals for at least 30 minutes.
    7. Immediately following the detonation, visual monitoring for 
marine mammals within the mitigation zone will continue for 30 minutes. 
Any marine mammal observed after an underwater detonation either 
injured or exhibiting signs of distress will be reported to via Navy 
operational chain of command to Navy environmental representatives from 
U.S. Pacific Fleet, Environmental Office, San Diego Detachment. Using 
Marine Mammal Stranding communication trees and contact procedures 
established for the Southern California Range Complex, the Navy will 
report these events to the Stranding Coordinator of NMFS' Southwest 
Regional Office. These voice or email reports will contain the date and 
time of the sighting, location (or if precise latitude and longitude is 
not currently available, then the approximate location in reference to 
an established SSTC beach feature), species description (if known), and 
indication of the animals status.

(2) Mitigation and Monitoring Measures for Underwater Detonations Using 
Time-Delay (TDFD Detonations Only)

    1. Underwater detonations using timed delay devices will only be 
conducted during daylight.
    2. Time-delays longer than 10 minutes will not be used. The 
initiation of the device will not start until the mitigation area below 
is clear for a full 30 minutes prior to initiation of the timer.
    3. A mitigation zone will be established around each underwater 
detonation location as indicated in Table 3 based on charge weight and 
length of time-delay used. When conducting the surveys within a 
mitigation zone (either 1,000 or 1,400 yds), boats will position 
themselves near the mid-point of the mitigation zone radius (but always 
outside the detonation plume radius/human safety zone) and travel in a 
circular pattern around the detonation location surveying both the 
inner (toward detonation site) and outer (away from detonation site) 
areas.
    4. Shallow water TDFD detonations range 1,000 yds:
     A minimum of 2 boats will be used to survey for marine 
mammals at mitigation ranges of 1,000 yds.
     When using 2 boats, each boat will be positioned on 
opposite sides of the detonation location, separated by 180 degrees.
     Two observers in each of the boats will conduct continuous 
visual survey of the mitigation zone for the entire duration of a 
training event.
     To the best extent practical, boats will try to maintain a 
10 knot search speed. This search speed was added to ensure adequate 
coverage of the buffer zone during observation periods. While weather 
conditions and sea states may require slower speeds in some instances, 
10 knots is a prudent, safe, and executable speed that will allow for 
adequate surveillance. For a 1,000 yd radius buffer zone a boat 
travelling at 10 knots and 500 yds away from the detonation point would 
circle the detonation point 3.22 times during a 30 minute survey 
period. By using 2 boats, 6.44 circles around the detonation point 
would be completed in a 30 minute span.
    5. Shallow water TDFD detonations greater than 1,400 yds:
     A minimum of 3 boats or 2 boats and 1 helicopter will be 
used to survey for marine mammals at mitigation ranges of 1,400 yds.
     When using 3 (or more) boats, each boat will be positioned 
equidistant from one another (120 degrees separation for 3 boats, 90 
degrees separation for 4 boats, etc.).
     For a 1,400 yd radius mitigation zone, a 10 knot speed 
results in 2.3 circles for each of the three boats, or nearly 7 circles 
around the detonation point over a 30 minute span.
     If available, aerial visual survey support from Navy 
helicopters can be utilized, so long as it will not jeopardize safety 
of flight.
     Helicopters, if available, can be used in lieu of one of 
the boat requirements. Navy helicopter pilots are trained to conduct 
searches for relatively small objects in the water, such as a missing 
person. A helicopter search pattern is dictated by standard Navy 
protocols and accounts for multiple variables, such as the size and 
shape of the search area, size of the object being searched for, and 
local environmental conditions, among others.
    6. A mitigation zone will be surveyed from 30 minutes prior to the 
detonation and for 30 minutes after the detonation.
    7. Other personnel besides boat observers can also maintain 
situational awareness on the presence of marine mammals within the 
mitigation zone to the best extent practical given dive safety 
considerations.
    Divers placing the charges on mines will observe the immediate 
underwater area around a detonation site for marine mammals and report 
sightings to surface observers.
    8. If a marine mammal is sighted within an established mitigation 
zone or moving towards it, underwater detonation events will be 
suspended until the marine mammal has voluntarily left the area and the 
area is clear of marine mammals for at least 30 minutes.
    9. Immediately following the detonation, visual monitoring for 
affected marine mammals within the mitigation zone will continue for 30 
minutes.
    10. Any marine mammal observed after an underwater detonation 
either injured or exhibiting signs of distress

[[Page 43253]]

will be reported via Navy operational chain of command to Navy 
environmental representatives from U.S. Pacific Fleet, Environmental 
Office, San Diego Detachment or Pearl Harbor. Using Marine Mammal 
Stranding protocols and communication trees established for the 
Southern California and Hawaii Range Complexes, the Navy will report 
these events to the Stranding Coordinator of NMFS' Southwest or Pacific 
Islands Regional Office. These voice or email reports will contain the 
date and time of the sighting, location (or if precise latitude and 
longitude is not currently available, then the approximate location in 
reference to an established SSTC beach feature), species description 
(if known), and indication of the animal's status.

(3) Mitigation and Monitoring Measures for Underwater SWAG Detonations 
(SWAG Only)

    A modified set of mitigation measures would be implemented for SWAG 
detonations, which involve much smaller charges of 0.03 lbs NEW.
    1. Underwater detonations using SWAG will only be conducted during 
daylight.
    2. A mitigation zone of 60 yards will be established around each 
SWAG detonation site.
    3. A minimum of two boats, including but not limited to small 
zodiacs and 7-m Rigid Hulled Inflatable Boats (RHIB) will be deployed. 
One boat will act as an observer platform, while the other boat is 
typically the diver support boat.
    4. Two observers with binoculars on one small craft\boat will 
survey the detonation area and the mitigation zone for marine mammals 
from at least 10 minutes prior to commencement of the scheduled 
explosive event and until at least 10 minutes after detonation.
    5. In addition to the dedicated observers, all divers and boat 
operators engaged in detonation events can potentially monitor the area 
immediately surrounding the point of detonation for marine mammals.
    6. Divers and personnel in support boats would monitor for marine 
mammals out to the 60 yard mitigation zone for 10 minutes prior to any 
detonation.
    7. After the detonation, visual monitoring for marine mammals would 
continue for 10 minutes. Any marine mammal observed after an underwater 
detonation either injured or exhibiting signs of distress will be 
reported via Navy operational chain of command to Navy environmental 
representatives from U.S. Pacific Fleet, Environmental Office, San 
Diego Detachment. Using Marine Mammal Stranding communication trees and 
contact procedures established for the Southern California Range 
Complex, the Navy will report these events to the Stranding Coordinator 
of NMFS' Southwest Regional Office. These voice or email reports will 
contain the date and time of the sighting, location (or if precise 
latitude and longitude is not currently available, then the approximate 
location in reference to an established SSTC beach feature), species 
description (if known), and indication of the animal's status.

Mitigation for ELCAS Training at SSTC

    NMFS worked with the Navy and developed the below mitigation 
procedures for ELCAS pile driving and removal events along the 
oceanside Boat Lanes at the SSTC for marine mammal species.
    1. Safety Zone: A safety zone shall be established at 150 feet (50 
yards) from ELCAS pile driving or removal events. This safety zone is 
base on the predicted range to Level A harassment (180 
dBrms) for cetaceans during pile driving, and is being 
applied conservatively to both cetaceans and pinnipeds during pile 
driving and removal.
    2. If marine mammals are found within the 150-foot (50-yard) safety 
zone, pile driving or removal events shall be halted until the marine 
mammals have voluntarily left the mitigation zone.
    3. Monitoring for marine mammals shall be conducted within the zone 
of influence and take place at 30 minutes before, during, and 30 
minutes after pile driving and removal activities, including ramp-up 
periods. A minimum of one trained observer shall be placed on shore, on 
the ELCAS, or in a boat at the best vantage point(s) practicable to 
monitor for marine mammals.
    4. Monitoring observer(s) shall implement shut-down/delay 
procedures by calling for shut-down to the hammer operator when marine 
mammals are sighted within the safety zone. After a shut-down/delay, 
pile driving or removal shall not be resumed until the marine mammal 
within the safety zone is confirmed to have left the area or 30 minutes 
have passed without seeing the animal.
    5. Soft Start--ELCAS pile driving shall implement a soft start as 
part of normal construction procedures. The pile driver increases 
impact strength as resistance goes up. At first, the pile driver piston 
drops a few inches. As resistance goes up, the pile driver piston will 
drop from a higher distance thus providing more impact due to gravity. 
This will allow marine mammals in the project area to vacate or begin 
vacating the area minimizing potential harassment.
    NMFS has carefully evaluated these proposed mitigation measures. 
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, including consideration of personnel safety, and 
practicality of implementation.
    Based on our evaluation of these proposed measures, 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.

Emergency Shut-Down Related to Marine Mammal Injury and Mortality

    If there is clear evidence that a marine mammal is injured or 
killed as a result of the proposed Navy training activities (e.g., 
instances in which it is clear that munitions explosions caused the 
injury or death), the Naval activities shall be immediately suspended 
and the situation immediately reported by personnel involved in the 
activity to the officer in charge of the training, who will follow Navy 
procedures for reporting the incident to NMFS through the Navy's chain-
of-command.

Monitoring and Reporting Measures

Monitoring 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 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. The monitoring and reporting 
measures for the Navy's proposed SSTC training exercises are provided 
below.
    The SSTC Monitoring Program, proposed by the Navy as part of its 
IHA application, is focused on mitigation

[[Page 43254]]

based monitoring and presented more fully in Appendix A of the Navy's 
IHA application. Main monitoring techniques include use of civilian 
scientists as marine mammal observers during a sub-set of SSTC 
underwater detonation events to validate the Navy's pre and post event 
mitigation effectiveness, and observe marine mammal reaction, or lack 
of reaction to SSTC training events. Also, as stated in the Mitigation 
section, the Navy is required to conduct an acoustic monitoring project 
during the first field deployment of the ELCAS to the SSTC.
    Monitoring methods for the SSTC training exercise include:
     Marine Mammal Observers (MMO) at SSTC underwater 
detonations
     ELCAS underwater noise propagation monitoring project
     Leverage aerial monitoring from other Navy-funded 
monitoring
    NMFS has reviewed the Navy's SSTC Monitoring Program and worked 
with the Navy and developed the following monitoring measures for SSTC 
training activities.

I. Marine Mammal Observer at a Sub-set of SSTC Underwater Detonations

    Civilian scientists acting as MMOs shall be used to observe a sub-
set of the SSTC underwater detonation events. The goal of MMOs is two-
fold. One, to validate the suite of SSTC specific mitigation measures 
applicable to a sub-set of SSTC training events, and to observe marine 
mammal behavior in the vicinity of SSTC training events.
    MMOs shall be field-experienced observers that are either Navy 
biologists or contracted marine biologists. These civilian MMOs shall 
be placed either alongside existing Navy SSTC operators during a sub-
set of training events, or on a separate small boat viewing platform. 
Use of MMOs shall verify Navy mitigation efforts within the SSTC, offer 
an opportunity for more detailed species identification, provide an 
opportunity to bring animal protection awareness to Navy personnel at 
SSTC, and provide the opportunity for an experienced biologist to 
collect data on marine mammal behavior. Data collected by the MMOs is 
anticipated to integrate with a Navy-wide effort to assess Navy 
training impacts on marine mammals (DoN 2009). Events selected for MMO 
participation shall be an appropriate fit in terms of security, safety, 
logistics, and compatibility with Navy underwater detonation training.
    MMOs shall collect the same data currently being collected for more 
elaborate offshore ship-based observations including but not limited 
to:
    (1) location of sighting;
    (2) species;
    (3) number of individuals;
    (4) number of calves present;
    (5) duration of sighting;
    (6) behavior of marine animals sighted;
    (7) direction of travel;
    (8) environmental information associated with sighting event 
including Beaufort sea state, wave height, swell direction, wind 
direction, wind speed, glare, percentage of glare, percentage of cloud 
cover; and
    (9) when in relation to Navy training did the sighting occur 
[before, during or after the detonation(s)].
    The MMOs will not be part of the Navy's formal reporting chain of 
command during their data collection efforts. Exceptions shall be made 
if a marine mammal is observed by the MMO within the SSTC specific 
mitigation zones the Navy has formally proposed to the NMFS. The MMO 
shall inform any Navy operator of the sighting so that appropriate 
action may be taken by the Navy trainees.

II. ELCAS Visual Monitoring

    The Navy shall place monitoring personnel to note any observations 
during the entire pile driving sequence, including ``soft start'' 
period, for later analysis. This analysis could provide information 
regarding the effectiveness of prescribing soft start or ramp up as a 
mitigation measures for pile driving and removal. Information regarding 
species observed during pile driving and removal events (including soft 
start period) shall include:
    (1) location of sighting;
    (2) species;
    (3) number of individuals;
    (4) number of calves present;
    (5) duration of sighting;
    (6) behavior of marine animals sighted;
    (7) direction of travel;
    (8) environmental information associated with sighting event 
including Beaufort sea state, wave height, swell direction, wind 
direction, wind speed, glare, percentage of glare, percentage of cloud 
cover; and
    (9) when in relation to Navy training did the sighting occur 
(before, during or after the pile driving or removal).

III. ELCAS Acoustic Monitoring

    The Navy shall conduct underwater acoustic propagation monitoring 
during the first available ELCAS deployment at the SSTC. This acoustic 
monitoring would provide empirical field data on ELCAS pile driving and 
removal underwater source levels, and propagation specific to ELCAS 
training at the SSTC. These results shall be used to either confirm or 
refine the Navy's exposure predictions (source level, F value, 
exposures) described earlier.

IV. Leverage From Existing Navy-Funded Marine Mammal Research

    The Navy shall report results obtained annually from the Southern 
California Range Complex Monitoring Plan (DoN 2009) for areas pertinent 
to the SSTC. In the Navy's 2011 Letter of Authorization renewal 
application and subsequent Year 3 Southern California Monitoring Plan 
(DoN 2010), a new study area for aerial visual survey was created. This 
area would start at the shoreline of the oceanside Boat Lanes at SSTC 
and extend seaward to approximately 10 nm offshore. The goal of these 
aerial visual surveys is to document marine mammal occurrence within a 
given sub-area off Southern California. Significant surface area can be 
covered by a survey aircraft flying at 800 to 1,000 feet for 
approximately five hours. The use of both airplanes and helicopters as 
aerial platforms will be considered for the survey area off SSTC. Both 
aircraft type, in particular the helicopter, provide excellent 
platforms for documenting marine mammal behaviors and through digital 
photography and digital video.

Reporting Measures

    In order to issue an ITA for an activity, section 101(a)(5)(A) of 
the MMPA states that NMFS must set forth ``requirements pertaining to 
the monitoring and reporting of such taking.'' Effective reporting is 
critical both to compliance as well as ensuring that the most value is 
obtained from the required monitoring.

I. General Notification of Injured or Dead Marine Mammals

    Navy personnel shall ensure that NMFS (regional stranding 
coordinator) is notified immediately (or as soon as clearance 
procedures allow) if an injured or dead marine mammal is found during 
or shortly after, and in the vicinity of, any Navy training exercises 
involving underwater detonations or pile driving. The Navy shall 
provide NMFS with 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).

II. Final Report

    The Navy shall submit a final report to the Office of Protected 
Resources, NMFS, no later than 90 days after the expiration of the IHA. 
The report shall,

[[Page 43255]]

at a minimum, include the following marine mammal sighting information:
    (1) location of sighting;
    (2) species;
    (3) number of individuals;
    (4) number of calves present;
    (5) duration of sighting;
    (6) behavior of marine animals sighted;
    (7) direction of travel;
    (8) environmental information associated with sighting event 
including Beaufort sea state, wave height, swell direction, wind 
direction, wind speed, glare, percentage of glare, percentage of cloud 
cover; and
    (9) when in relation to Navy training did the sighting occur 
[before, during or after the detonation(s)].
    In addition, the Navy shall provide the information for all of its 
underwater detonation events and ELCAS events under the IHA. The 
information shall include: (1) Total number of each type of underwater 
detonation events conducted at the SSTC, and (2) total number of piles 
driven and extracted during the ELCAS exercise.
    The Navy shall submit to NMFS a draft report as described above and 
shall respond to NMFS comments within 3 months of receipt. The report 
will be considered final after the Navy has addressed NMFS' comments, 
or three months after the submittal of the draft if NMFS does not 
comment by then.

Estimated Take by Incidental Harassment

Estimated Marine Mammal Exposures From SSTC Underwater Detonations

    The quantitative exposure modeling methodology estimated numbers of 
individuals exposed to the effects of underwater detonations exceeding 
the thresholds used, as if no mitigation measures were employed.
    All estimated exposures are seasonal averages (mean) plus one 
standard deviation using \1/2\ of the yearly training tempo to 
represent each season. Taking this approach was an effort to be 
conservative (i.e., allow for an overestimate of exposure) when 
estimating exposures typical of training during a single year.
    Table 4 shows number of annual predicted exposures by species for 
all underwater detonation training within the SSTC. As stated 
previously, only events with sequential detonations were examined for 
non-TTS behavior disruption.

     Table 4--SSTC Modeled Estimates of Species Exposed to Underwater Detonations Without Implementation of
                                               Mitigation Measures
----------------------------------------------------------------------------------------------------------------
                                                                  Annual marine mammal exposure (all sources)
                                                             ---------------------------------------------------
                                                                Level B    Level B TTS    Level A     Mortality
                                                                behavior  --------------------------------------
                                                               (multiple
                                                               successive
                           Species                             explosive
                                                                 events    182 dB re 1  205 dB re 1
                                                                 only)     [mu]Pa\2\-s/ [mu]Pa\2\-s/ 30.5 psi-ms
                                                             -------------    23 psi    13.0 psi-ms
                                                              177 dB re 1
                                                                 [mu]Pa
----------------------------------------------------------------------------------------------------------------
Gray Whale:
    Warm....................................................  ...........  ...........  ...........  ...........
    Cold....................................................            0            0            0            0
Bottlenose Dolphin:
    Warm....................................................           30           43            0            0
    Cold....................................................           40           55            0            0
California Sea Lion:
    Warm....................................................            4            4            0            0
    Cold....................................................           40           51            0            0
Harbor Seal:
    Warm....................................................            0            0            0            0
    Cold....................................................            0            0            0            0
Long-beaked common dolphin:
    Warm....................................................           14           21            0            0
    Cold....................................................            7           10            0            0
Pacific white-sided dolphin:
    Warm....................................................            2            3            0            0
    Cold....................................................            3            4            0            0
Risso's dolphin:
    Warm....................................................            3            4            0            0
    Cold....................................................           11           15            0            0
Short-beaked common dolphin:
    Warm....................................................          123          177            0            0
    Cold....................................................           62           86            0            0
                                                             ---------------------------------------------------
        Total Annual Exposures..............................          453          626            0            0
----------------------------------------------------------------------------------------------------------------

    In summary, for all underwater detonations, the Navy's impact model 
predicted that no marine mammal mortality and/or Level A harassment 
(injury) would occur within the proposed action area. The mitigation 
requirements are expected to ensure that this is the case.
    For non-sequential (i.e., single detonation) training events, the 
Navy's impact model predicted a total of 626 annual exposures that 
could result in Level B harassment (TTS), which include annual 
exposures of 98 bottlenose dolphins, 55 California sea lions, 31 long-
beaked common dolphins, 7 Pacific white-sided dolphins, 19 Risso's 
dolphins, and 263 short-beaked common dolphins.

[[Page 43256]]

    For sequential (Multiple Successive Explosive events) training 
events, the Navy's impact model predicted a total of 453 annual 
exposures that could result in Level B behavioral harassment, which 
include annual exposures of 70 bottlenose dolphins, 44 California sea 
lions, 21 long-beaked common dolphins, 5 Pacific white-sided dolphins, 
14 Risso's dolphins, and 185 short-beaked common dolphins.

Estimated Marine Mammal Exposures From ELCAS Pile Driving and Removal

I. Pile Driving

    Using the marine mammal densities presented in the Navy's IHA 
application, the number of animals exposed to annual Level B harassment 
from ELCAS pile driving can be estimated. A couple of business rules 
and assumptions are used in this determination:
    1. Pile driving is estimated to occur 10 days per ELCAS training 
event, with up to four training exercises being conducted per year (40 
days per year). Given likely variable training schedules, an assumption 
was made that approximately 20 of these 40 days would occur during the 
warm water season, and 20 of the 40 days would occur during the cold 
water season.
    2. To be more conservative even to the point of over predicting 
likely exposures, the Navy asserts that during the calculation there 
can be no ``fractional'' exposures of marine mammals on a daily basis, 
and all exposure values are rounded up during the calculation.
    To estimate the potential ELCAS pile driving exposure, the 
following expression is used:
    Annual exposure = ZOI x warm season marine mammal density x warm 
season pile driving days + ZOI x cold season marine mammal density x 
cold season pile driving days, with ZOI = [pi] x R\2\, where R is the 
radius of the ZOI.
    An example showing the take calculation for bottlenose dolphins, 
with the conservative ``daily rounding up'' business rule (2 
above), is shown below:
    Daily exposure = [pi] x 0.999\2\ x 0.202 + [pi] x 0.999\2\ x 0.202 
= 0.6 + 0.6.
    When rounding up the daily exposure 0.6 dolphin to 1 dolphin; the 
annual exposure from warm season pile driving days (20 days) and cold 
season pile driving days (20 days) is:
    Annual exposure = 1 x 20 + 1 x 20 = 40
    Based on the assessment using the methodology discussed previously, 
applying the business rules and limitations described here, and without 
consideration of mitigation measures, the take estimate is that ELCAS 
pile driving is predicted to result in no Level A Harassments to any 
marine mammal (received SPL of 190 dBrms for pinnipeds and 
180 dBrms re 1 [mu]Pa for cetacean, respectively) but 40 
bottlenose dolphins, 20 California sea lions, and 80 short-beaked 
common dolphins by Level B behavioral harassment (Table 5).

II. Pile Removal

    The same approach is applied for take estimation from ELCAS pile 
removal.
    To estimate the potential ELCAS pile removal exposure, the 
following expression is used:
    Annual exposure = ZOI x warm season marine mammal density x warm 
season pile removal days + ZOI x cold season marine mammal density x 
cold season pile removal days, with ZOI = [pi] x R\2\, where R is the 
radius of the ZOI.
    An example showing the take calculation for bottlenose dolphins, 
with the conservative ``daily rounding up'' business rule for pile 
removal, is shown below:
    Daily exposure = [pi] x 4.64\2\ x 0.202 + [pi] x 4.64\2\ x 0.202 = 
13.7 + 13.7.
    When rounding up the daily exposure 13.7 dolphins to 14 dolphins; 
the annual exposure from warm season pile removal days (6 days) and 
cold season pile removal days (6 days) is:
    Annual exposure = 14 x 6 + 14 x 6 = 168
    Based on the assessment using the methodology discussed previously, 
applying the business rules and limitations described here, and without 
consideration of mitigation measures, the take estimate is that ELCAS 
pile removal is predicted to result in no Level A Harassments to any 
marine mammal (received SPL of 190 dBrms for pinnipeds and 
180 dBrms re 1 [mu]Pa for cetacean, respectively) but in 
Level B behavioral harassment of 168 bottlenose dolphins, 102 
California sea lions, 12 harbor seals, 6 gray whales, 54 long-beaked 
common dolphins, 12 Pacific white-sided dolphins, 30 Risso's dolphins, 
and 462 short-beaked common dolphins (Table 5).

 Table 5--Exposure Estimates from ELCAS Pile Driving and Removal Prior to Implementation of Mitigation Measures
----------------------------------------------------------------------------------------------------------------
                                                            Annual Marine Mammal Exposure (All Sources)
                                           ----------------------------------------------------------------------------
                                                                                           Level A  (Pinniped)
                                              Level B                             -------------------------------------
                  Species                     Behavior     Level B      Level A                   160     180
                                               (Non-       Behavior    (Cetacean)   120 dBrms    dBrms   dBrms
                                              Impulse)    (Impulse)                re 1 [mu]Pa   re 1    re 1
                                                                                                [mu]Pa  [mu]Pa
---------------------------------------------------------------------------------------------- ------------------------
Gray Whale:
    Installation..........................          N/A            0            0            0
    Removal...............................            6          N/A            0            0
Bottlenose Dolphin:
    Installation..........................          N/A           40            0            0
    Removal...............................          168          N/A            0            0
California Sea Lion:
    Installation..........................          N/A           20            0            0
    Removal...............................          102          N/A            0            0
Harbor Seal:
    Installation..........................          N/A            0            0            0
    Removal...............................           12          N/A            0            0
Long-beaked common dolphin:
    Installation..........................          N/A            0            0            0
    Removal...............................           54          N/A            0            0
Pacific white-sided dolphin:
    Installation..........................          N/A            0            0            0
    Removal...............................           12          N/A            0            0

[[Page 43257]]

 
Risso's dolphin:
    Installation..........................          N/A            0            0            0
    Removal...............................           30          N/A            0            0
Short-beaked common dolphin:
    Installation..........................          N/A           80            0            0
    Removal...............................          462          N/A            0            0
----------------------------------------------------------------------------------------------------------------
        Total Annual Exposures............          846          140            0            0
----------------------------------------------------------------------------------------------------------------

    In summary, for all underwater detonations and ELCAS pile driving 
activities, the Navy's impact model predicted that no mortality and/or 
Level A harassment (injury) would occur to marine mammal species and 
stocks within the proposed action area.

Potential Impacts to Marine Mammal Habitat

    The proposed training activities at SSTC will not result in any 
permanent impact on habitats used by marine mammals, and potentially 
short-term to minimum impact to the food sources such as forage fish. 
There are no known haul-out sites, foraging hotspots, or other ocean 
bottom structures of significant biological importance to harbor seals, 
California sea lions, or bottlenose dolphins within SSTC. Therefore, 
the main impact associated with the proposed activity will be 
temporarily elevated noise levels and the associated direct effects on 
marine mammals, as discussed previously.
    The primary source of effects to marine mammal habitat is exposures 
resulting from underwater detonation training and ELCAS pile driving 
and removal training events. Other sources that may affect marine 
mammal habitat include changes in transiting vessels, vessel strike, 
turbidity, and introduction of fuel, debris, ordnance, and chemical 
residues. However, each of these components was addressed in the SSTC 
Environmental Impact Statement (EIS) and it is the Navy's assertion 
that there would be no likely impacts to marine mammal habitats from 
these training events.
    The most likely impact to marine mammal habitat occurs from 
underwater detonation and pile driving and removal effects on likely 
marine mammal prey (i.e., fish) within SSTC.
    There are currently no well-established thresholds for estimating 
effects to fish from explosives other than mortality models. Fish that 
are located in the water column, in proximity to the source of 
detonation could be injured, killed, or disturbed by the impulsive 
sound and could leave the area temporarily. Continental Shelf Inc. 
(2004) summarized a few studies conducted to determine effects 
associated with removal of offshore structures (e.g., oil rigs) in the 
Gulf of Mexico. Their findings revealed that at very close range, 
underwater explosions are lethal to most fish species regardless of 
size, shape, or internal anatomy. In most situations, cause of death in 
fish has been massive organ and tissue damage and internal bleeding. At 
longer range, species with gas-filled swimbladders (e.g., snapper, cod, 
and striped bass) are more susceptible than those without swimbladders 
(e.g., flounders, eels).
    Studies also suggest that larger fish are generally less 
susceptible to death or injury than small fish. Moreover, elongated 
forms that are round in cross section are less at risk than deep-bodied 
forms. Orientation of fish relative to the shock wave may also affect 
the extent of injury. Open water pelagic fish (e.g., mackerel) seem to 
be less affected than reef fishes. The results of most studies are 
dependent upon specific biological, environmental, explosive, and data 
recording factors.
    The huge variation in fish populations, including numbers, species, 
sizes, and orientation and range from the detonation point, makes it 
very difficult to accurately predict mortalities at any specific site 
of detonation. All underwater detonations are of small scale (under 29 
lbs NEW), and the proposed training exercises would be conducted in 
several areas within the large SSTC Study Area over the seasons during 
the year. Most fish species experience a large number of natural 
mortalities, especially during early life-stages, and any small level 
of mortality caused by the SSTC training exercises involving explosives 
will likely be insignificant to the population as a whole.
    Therefore, potential impacts to marine mammal food resources within 
the SSTC are expected to be minimal given both the very geographic and 
spatially limited scope of most Navy at-sea activities including 
underwater detonations, and the high biological productivity of these 
resources. No short or long term effects to marine mammal food 
resources from Navy activities are anticipated within the SSTC Study 
Area.

Subsistence Harvest of Marine Mammals

    NMFS has determined that the Navy's proposed training activities at 
the SSTC would not have an unmitigable adverse impact on the 
availability of the affected species or stocks for subsistence use 
since there are no such uses in the specified area.

Negligible Impact and Small Numbers Analysis and Determination

    Pursuant to NMFS' regulations implementing the MMPA, an applicant 
is required to estimate the number of animals that will be ``taken'' by 
the specified activities (i.e., takes by harassment only, or takes by 
harassment, injury, and/or death). This estimate informs the analysis 
that NMFS must perform to determine whether the activity will have a 
``negligible impact'' on the species or stock. Level B (behavioral) 
harassment occurs at the level of the individual(s) and does not assume 
any resulting population-level consequences, though there are known 
avenues through which behavioral disturbance of individuals can result 
in population-level effects. A negligible

[[Page 43258]]

impact finding is based on the lack of likely adverse effects on annual 
rates of recruitment or survival (i.e., population-level effects). An 
estimate of the number of Level B harassment takes alone is not enough 
information on which to base an impact determination.
    In addition to considering estimates of the number of marine 
mammals that might be ``taken'' through behavioral harassment, NMFS 
considers other factors, such as the likely nature of any responses 
(their intensity, duration, etc.), the context of any responses 
(critical reproductive time or location, migration, etc.), as well as 
the number and nature of estimated Level A takes, the number of 
estimated mortalities, and effects on habitat.
    The Navy's specified activities have been described based on best 
estimates of the planned training exercises at SSTC action area. Some 
of the noises that would be generated as a result of the proposed 
underwater detonation and ELCAS pile driving activities, are high 
intensity. However, the explosives that the Navy plans to use in the 
proposed SSTC action area are all small detonators under 29 lbs NEW, 
which result in relatively small ZOIs. In addition, the locations where 
the proposed training activities are planned are shallow water areas 
which would effectively contain the spreading of explosive energy 
within the bottom boundary. Taking the above into account, along with 
the fact that NMFS anticipates no mortalities and injuries to result 
from the action, the fact that there are no specific areas of 
reproductive importance for marine mammals recognized within the SSTC 
area, the sections discussed below, and dependent upon the 
implementation of the proposed mitigation measures, NMFS has determined 
that Navy training exercises utilizing underwater detonations and ELCAS 
pile driving and removal will have a negligible impact on the affected 
marine mammal species and stocks present in the SSTC Study Area.
    NMFS' analysis of potential behavioral harassment, temporary 
threshold shifts, permanent threshold shifts, injury, and mortality to 
marine mammals as a result of the SSTC training activities was provided 
earlier in this document and is analyzed in more detail below.

Behavioral Harassment

    As discussed earlier, the Navy's proposed SSTC training activities 
would use small underwater explosives with maximum NEW of 29 lbs 16 
events per year in areas of small ZOIs that would mostly eliminate the 
likelihood of mortality and injury to marine mammals. In addition, 
these detonation events are widely dispersed in several designated 
sites within the SSTC Study Area. The probability that detonation 
events will overlap in time and space with marine mammals is low, 
particularly given the densities of marine mammals in the vicinity of 
SSTC Study Area and the implementation of monitoring and mitigation 
measures. Moreover, NMFS does not expect animals to experience repeat 
exposures to the same sound source as animals will likely move away 
from the source after being exposed. In addition, these isolated 
exposures, when received at distances of Level B behavioral harassment 
(i.e., 177 dB re 1 [mu]Pa\2\-s), are expected to cause brief startle 
reactions or short-term behavioral modification by the animals. These 
brief reactions and behavioral changes are expected to disappear when 
the exposures cease. Therefore, these levels of received impulse noise 
from detonation are not expected to affect annual rates or recruitment 
or survival.

TTS

    NMFS and the Navy have estimated that individuals of some species 
of marine mammals may sustain some level of temporary threshold shift 
TTS from underwater detonations. TTS can last from a few minutes to 
days, be of varying degree, and occur across various frequency 
bandwidths. The TTS sustained by an animal is primarily classified by 
three characteristics:
     Frequency--Available data (of mid-frequency hearing 
specialists exposed to mid to high frequency sounds- Southall et al. 
2007) suggest that most TTS occurs in the frequency range of the source 
up to one octave higher than the source (with the maximum TTS at \1/2\ 
octave above).
     Degree of the shift (i.e., how many dB is the sensitivity 
of the hearing reduced by)--generally, both the degree of TTS and the 
duration of TTS will be greater if the marine mammal is exposed to a 
higher level of energy (which would occur when the peak dB level is 
higher or the duration is longer). Since the impulse from detonation is 
extremely brief, an animal would have to approach very close to the 
detonation site to increase the received SEL. The threshold for the 
onset of TTS for detonations is a dual criteria: 182 dB re 1 [mu]Pa\2\-
s or 23 psi, which might be received at distances from 20--490 yards 
from the centers of detonation based on the types of NEW involved to 
receive the SEL that causes TTS compared to similar source level with 
longer durations (such as sonar signals).
     Duration of TTS (Recovery time)--Of all TTS laboratory 
studies, some using exposures of almost an hour in duration or up to 
SEL at 217 dB re 1 [mu]Pa\2\-s, almost all recovered within 1 day (or 
less, often in minutes), though in one study (Finneran et al. 2007), 
recovery took 4 days.
    Although the degree of TTS depends on the received noise levels and 
exposure time, all studies show that TTS is reversible and animals' 
sensitivity is expected to recover fully in minutes to hours based on 
the fact that the proposed underwater detonations are small in scale 
and isolated. Therefore, NMFS expects that TTS would not affect annual 
rates of recruitment or survival.

Acoustic Masking or Communication Impairment

    As discussed above, it is also possible that anthropogenic sound 
could result in masking of marine mammal communication and navigation 
signals. However, masking only occurs during the time of the signal 
(and potential secondary arrivals of indirect rays), versus TTS, which 
occurs continuously for its duration. Impulse sounds from underwater 
detonation and pile driving are brief and the majority of most animals' 
vocalizations would not be masked. Although impulse noises such as 
those from underwater explosives and impact pile driving tend to decay 
at distance, and thus become non-impulse, give the area of extremely 
shallow water (which effectively attenuates low frequency sound of 
these impulses) and the small NEW of explosives, the SPLs at these 
distances are expected to be barely above ambient level. Therefore, 
masking effects from underwater detonation are expected to be minimal 
and unlikely. If masking or communication impairment were to occur 
briefly, it would be in the frequency ranges below 100 Hz, which 
overlaps with some mysticete vocalizations; however, it would likely 
not mask the entirety of any particular vocalization or communication 
series because of the short impulse.

PTS, Injury, or Mortality

    The modeling for take estimates predict that no marine mammal would 
be taken by Level A harassment (injury, PTS included) or mortality due 
to the low power of the underwater detonation and the small ZOIs. 
Further, the mitigation measures have been designed to ensure that 
animals are detected in time to avoid injury or mortality when TDFDs 
are used, in consideration of swim speed.

[[Page 43259]]

    Based on these assessments, NMFS determined that approximately 6 
gray whales, 221 California sea lions, 12 harbor seals, 323 bottlenose 
dolphins, 106 long-beaked common dolphins, 24 Pacific white-sided 
dolphins, 63 Risso's dolphins, and 990 short-beaked common dolphins 
could be affected by Level B harassment (TTS and sub-TTS) as a result 
of the proposed SSTC training activities.
    Additionally, as discussed previously, the aforementioned take 
estimates do not account for the implementation of mitigation measures. 
With the implementation of mitigation and monitoring measures, NMFS 
expects that the takes would be reduced further. Coupled with the fact 
that these impacts will likely not occur in areas and times critical to 
reproduction, NMFS has determined that the total taking incidental to 
the Navy's proposed SSTC training activities would have a negligible 
impact on the marine mammal species and stocks present in the SSTC 
Study Area.

Endangered Species Act (ESA)

    No marine mammal species are listed as endangered or threatened 
under the ESA with confirmed or possible occurrence in the study area. 
Therefore, section 7 consultation under the ESA for NMFS's proposed 
issuance of an MMPA authorization is not warranted.

National Environmental Policy Act (NEPA)

    The Navy has prepared a Final Environmental Impact Statement (EIS) 
for the proposed SSTC training activities. The FEIS was released in 
January 2011 and it is available at https://www.silverstrandtrainingcomplexeis.com/EIS.aspx/. NMFS was a 
cooperating agency (as defined by the Council on Environmental Quality 
(40 CFR 1501.6)) in the preparation of the EIS. NMFS subsequently 
adopted the FEIS for the SSTC training activities.
    As a result of these determinations, NMFS has issued an IHA to the 
Navy to conduct training activities at the SSTC Study Area, provided 
the previously mentioned mitigation, monitoring, and reporting 
requirements are incorporated.

    Dated: July 18, 2012.
Wanda Cain,
Acting Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. 2012-17972 Filed 7-23-12; 8:45 am]
BILLING CODE 3510-22-P