Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to a Wharf Recapitalization Project, 52148-52166 [2013-20507]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 78, Number 163 (Thursday, August 22, 2013)]
[Notices]
[Pages 52148-52166]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2013-20507]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XC762


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to a Wharf Recapitalization Project

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

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

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SUMMARY: NMFS has received a request from the U.S. Navy (Navy) for 
authorization to take marine mammals incidental to construction 
activities as part of a wharf recapitalization project. Pursuant to the 
Marine Mammal Protection Act (MMPA), NMFS is requesting public comment 
on its proposal to issue an incidental harassment authorization (IHA) 
to the Navy to take, by harassment only, two species of marine mammal 
during the specified activity.

DATES: Comments and information must be received no later than 
September 23, 2013.

ADDRESSES: Comments on this proposal should be addressed to Michael 
Payne, Chief, Permits and Conservation Division, Office of Protected 
Resources, National Marine Fisheries Service. Physical comments should 
be sent to 1315 East-West Highway, Silver Spring, MD 20910 and 
electronic comments should be sent to ITP.Laws@noaa.gov.
    Instructions: Comments sent by any other method, to any other 
address or individual, or received after the end of the comment period, 
may not be considered. Comments received electronically, including all 
attachments, must not exceed a 25-megabyte file size. All comments 
received are a part of the public record. All personal identifying 
information (e.g., name, address) voluntarily submitted by the 
commenter may be publicly accessible. Do not submit confidential 
business information or otherwise sensitive or protected information. 
Attachments to electronic comments will be accepted in Microsoft Word, 
Excel, or Adobe PDF file formats only.

FOR FURTHER INFORMATION CONTACT: Ben Laws, Office of Protected 
Resources, NMFS, (301) 427-8401.

SUPPLEMENTARY INFORMATION: 

Availability

    A copy of the Navy's application and any supporting documents, as 
well as a list of the references cited in this document, may be 
obtained by visiting the internet at: https://www.nmfs.noaa.gov/pr/permits/incidental.htm. In the case of problems accessing these 
documents, please call the contact listed above.

National Environmental Policy Act

    The Navy has prepared a draft Environmental Assessment (Wharf C-2 
Recapitalization at Naval Station Mayport, FL) in accordance with the 
National Environmental Policy Act (NEPA) and the regulations published 
by the Council on Environmental Quality. It is posted at the 
aforementioned site. NMFS will independently evaluate the EA and 
determine whether or not to adopt it. We may prepare a separate NEPA 
analysis and incorporate relevant portions of Navy's EA by reference. 
Information in the Navy's application, EA, and this notice collectively 
provide the environmental information related to proposed issuance of 
this IHA for public review and comment. We will review all comments 
submitted in response to this notice as we complete the NEPA process, 
including a decision of whether to sign a Finding of No

[[Page 52149]]

Significant Impact (FONSI), prior to a final decision on the incidental 
take authorization request.

Background

    Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.) 
direct the Secretary of Commerce to allow, upon request by U.S. 
citizens who engage in a specified activity (other than commercial 
fishing) within a specified area, the incidental, but not intentional, 
taking of small numbers of marine mammals, providing that certain 
findings are made and the necessary prescriptions are established.
    The incidental taking of small numbers of marine mammals may be 
allowed only if NMFS (through authority delegated by the Secretary) 
finds that the total taking by the specified activity during the 
specified time period will (i) have a negligible impact on the species 
or stock(s) and (ii) not have an unmitigable adverse impact on the 
availability of the species or stock(s) for subsistence uses (where 
relevant). Further, the permissible methods of taking and requirements 
pertaining to the mitigation, monitoring and reporting of such taking 
must be set forth, either in specific regulations or in an 
authorization.
    The allowance of such incidental taking under section 101(a)(5)(A), 
by harassment, serious injury, death or a combination thereof, requires 
that regulations be established. Subsequently, a Letter of 
Authorization may be issued pursuant to the prescriptions established 
in such regulations, providing that the level of taking will be 
consistent with the findings made for the total taking allowable under 
the specific regulations. Under section 101(a)(5)(D), NMFS may 
authorize such incidental taking by harassment only, for periods of not 
more than 1 year, pursuant to requirements and conditions contained 
within an Incidental Harassment Authorization. The establishment of 
prescriptions through either specific regulations or an authorization 
requires notice and opportunity for public comment.
    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.'' Except with respect to certain activities 
not pertinent here, section 3(18) of the MMPA defines ``harassment'' 
as: `` . . . any act of pursuit, torment, or annoyance which (i) has 
the potential to injure a marine mammal or marine mammal stock in the 
wild; or (ii) has the potential to disturb a marine mammal or marine 
mammal stock in the wild by causing disruption of behavioral patterns, 
including, but not limited to, migration, breathing, nursing, breeding, 
feeding, or sheltering.'' The former is termed Level A harassment and 
the latter is termed Level B harassment.

Summary of Request

    On April 4, 2013, we received a request from the Navy for 
authorization of the taking, by Level B harassment only, of marine 
mammals incidental to pile driving in association with the Wharf C-2 
recapitalization project at Naval Station Mayport, Florida (NSM). That 
request was modified on May 9 and June 5, 2013, and a final version, 
which we deemed adequate and complete, was submitted on August 7, 2013. 
In-water work associated with the project is expected to be completed 
within the one-year timeframe of the proposed IHA (December 1, 2013 
through November 30, 2014). Two species of marine mammal are expected 
to be affected by the specified activities: bottlenose dolphin 
(Tursiops truncatus truncatus) and Atlantic spotted dolphin (Stenella 
frontalis). These species may occur year-round in the action area.
    Wharf C-2 is a single level, general purpose berthing wharf 
constructed in 1960. The wharf is one of NSM's two primary deep-draft 
berths and is one of the primary ordnance handling wharfs. The wharf is 
a diaphragm steel sheet pile cell structure with a concrete apron, 
partial concrete encasement of the piling and an asphalt paved deck. 
The wharf is currently in poor condition due to advanced deterioration 
of the steel sheeting and lack of corrosion protection, and this 
structural deterioration has resulted in the institution of load 
restrictions within 60 ft of the wharf face. The purpose of this 
project is to complete necessary repairs to Wharf C-2. Please refer to 
Appendix A of the Navy's application for photos of existing damage and 
deterioration at the wharf, and to Appendix B for a contractor 
schematic of the project plan.
    Effects to marine mammals from the specified activity are expected 
to result from underwater sound produced by vibratory and impact pile 
driving. In order to assess project impacts, the Navy used thresholds 
recommended by NMFS, outlined later in this document. The Navy assumed 
practical spreading loss and used empirically-measured source levels 
from representative pile driving events to estimate potential marine 
mammal exposures. Predicted exposures are described later in this 
document. The calculations predict that only Level B harassment would 
occur associated with pile driving activities, and required mitigation 
measures further ensure that no more than Level B harassment would 
occur.

Description of the Specified Activity

Specific Geographic Region and Duration

    NSM is located in northeastern Florida, at the mouth of the St. 
Johns River and adjacent to the Atlantic Ocean (see Figure 2-1 of the 
Navy's application). The St. Johns River is the longest river in 
Florida, with the final 35 mi flowing through the city of Jacksonville. 
This portion of the river is significant for commercial shipping and 
military use. At the mouth of the river, near the action area, the 
Atlantic Ocean is the dominant influence and typical salinities are 
above 30 ppm. Outside the river mouth, in nearshore waters, moderate 
oceanic currents tend to flow southward parallel to the coast. Sea 
surface temperatures range from around 16 [deg]C in winter to 28 [deg]C 
in summer.
    The specific action area consists of the NSM turning basin, an area 
of approximately 2,000 by 3,000 ft containing ship berthing facilities 
at sixteen locations along wharves around the basin perimeter. The 
basin was constructed during the early 1940s by dredging the eastern 
part of Ribault Bay (at the mouth of the St. Johns River), with dredge 
material from the basin used to fill parts of the bay and other low-
lying areas in order to elevate the land surface. The basin is 
currently maintained through regular dredging at a depth of 50 ft, with 
depths at the berths ranging from 30-50 ft. The turning basin, 
connected to the St. Johns River by a 500-ft-wide entrance channel, 
will largely contain sound produced by project activities, with the 
exception of sound propagating east into nearshore Atlantic waters 
through the entrance channel (see Figure 2-2 of the Navy's 
application). Wharf C-2 is located in the northeastern corner of the 
Mayport turning basin.
    The project is expected to require a maximum of 50 days of in-water 
vibratory pile driving work over a 12-month period. It is not expected 
that significant impact pile driving would be necessary, on the basis 
of expected subsurface driving conditions and past experience driving 
piles in the same location. However, twenty additional days of impact 
pile driving are included in the specified activity as a contingency, 
for a total of 70 days in-water pile driving considered over the 12-
month timeframe of the proposed IHA.

[[Page 52150]]

Description of Specified Activity

    In order to rehabilitate Wharf C-2, the Navy proposes to install a 
new steel king pile/sheet pile (SSP) bulkhead. An SSP system consists 
of large vertical king piles with paired steel sheet piles driven 
inbetween and connected to the ends of the king piles. The wall is 
anchored at the top with fill then placed behind the wall. Finally, a 
concrete cap is formed along the top and outside face of the wall to 
tie the entire structure together and provide a berthing surface for 
vessels. The new bulkhead will be designed for a 50-year service life. 
Please see Figures 1-1 through 1-4 and Table 1-1 in the Navy's 
application for project schematics, descriptive photographs, and 
further information about the pile types to be used. The project 
requires additional work (both in and out of water) that is not 
considered to have the potential for impacts to marine mammals; these 
project components are described in the Navy's EA.
    The project will require installation of approximately 120 single 
sheet piles and 119 king piles (all steel) to support the bulkhead 
wall, and fifty polymeric (plastic) fender piles. Vibratory 
installation of the steel piles will require approximately 45 days, 
with approximately 5 additional days needed for vibratory installation 
of the plastic piles. King piles are long I-shaped guide piles that 
provide the structural support for the bulkhead wall. Sheet piles, 
which form the actual wall, will be driven in pairs between the king 
piles. Once piles are in position, it is expected that less than 60 
seconds of vibratory driving would be required per pile to reach the 
required depth. Time interval between driving of each pile pair will 
vary, but is expected to be a minimum of several minutes due to time 
required for positioning, etc. One template consists of the combination 
of five king piles and four sheet pile pairs; it is expected that three 
such templates may be driven per day. Polymeric fender piles will be 
installed after completion of the bulkhead, at an expected rate of 
approximately ten piles per day.
    Impact pile driving is not expected to be required for most piles, 
but may be used as a contingency in cases when vibratory driving is not 
sufficient to reach the necessary depth. A similar project completed at 
an adjacent wharf required impact pile driving on only seven piles 
(over the course of two days). Impact pile driving, if it were 
required, could occur on the same day as vibratory pile driving, but 
driving rigs would not be operated simultaneously.

Description of Sound Sources and Distances to Thresholds

    Impacts from the specified activity on marine mammals are expected 
to result from the production of underwater sound; therefore, we 
provide a brief technical background on sound, the characteristics of 
certain sound types, and on metrics used in this proposal.

Background

    Sound travels in waves, the basic components of which are 
frequency, wavelength, velocity, and amplitude. Frequency is the number 
of pressure waves that pass by a reference point per unit of time and 
is measured in hertz (Hz) or cycles per second. Wavelength is the 
distance between two peaks of a sound wave; lower frequency sounds have 
longer wavelengths than higher frequency sounds, and attenuate 
(decrease) more rapidly in shallower water. Amplitude is the height of 
the sound pressure wave or the ``loudness'' of a sound and is typically 
measured using the decibel (dB) scale. A dB is the ratio between a 
measured pressure (with sound) and a reference pressure (sound at a 
constant pressure, established by scientific standards), and is a 
logarithmic unit that accounts for large variations in amplitude; 
therefore, relatively small changes in dB ratings correspond to large 
changes in sound pressure. When referring to sound pressure levels 
(SPLs; the sound force per unit area), sound is referenced in the 
context of underwater sound pressure to 1 microPascal ([mu]Pa). One 
pascal is the pressure resulting from a force of one newton exerted 
over an area of one square meter. The source level (SL) represents the 
sound level at a distance of 1 m from the source (referenced to 1 
[mu]Pa). The received level is the sound level at the listener's 
position.
    Root mean square (rms) is the quadratic mean sound pressure over 
the duration of an impulse. Rms is calculated by squaring all of the 
sound amplitudes, averaging the squares, and then taking the square 
root of the average (Urick, 1983). Rms accounts for both positive and 
negative values; squaring the pressures makes all values positive so 
that they may be accounted for in the summation of pressure levels 
(Hastings and Popper, 2005). This measurement is often used in the 
context of discussing behavioral effects, in part because behavioral 
effects, which often result from auditory cues, may be better expressed 
through averaged units than by peak pressures.
    When underwater objects vibrate or activity occurs, sound-pressure 
waves are created. These waves alternately compress and decompress the 
water as the sound wave travels. Underwater sound waves radiate in all 
directions away from the source (similar to ripples on the surface of a 
pond), except in cases where the source is directional. The 
compressions and decompressions associated with sound waves are 
detected as changes in pressure by aquatic life and man-made sound 
receptors such as hydrophones.

Ambient Sound

    Even in the absence of sound from the specified activity, the 
underwater environment is typically loud due to ambient sound. Ambient 
sound is defined as environmental background sound levels lacking a 
single source or point (Richardson et al., 1995), and the sound level 
of a region is defined by the total acoustical energy being generated 
by known and unknown sources. These sources may include physical (e.g., 
waves, earthquakes, ice, atmospheric sound), biological (e.g., sounds 
produced by marine mammals, fish, and invertebrates), and anthropogenic 
sound (e.g., vessels, dredging, aircraft, construction). A number of 
sources contribute to ambient sound, including the following 
(Richardson et al., 1995):
     Wind and waves: The complex interactions between wind and 
water surface, including processes such as breaking waves and wave-
induced bubble oscillations and cavitation, are a main source of 
naturally occurring ambient sound for frequencies between 200 Hz and 50 
kHz (Mitson, 1995). In general, ambient sound levels tend to increase 
with increasing wind speed and wave height. Surf sound becomes 
important near shore, with measurements collected at a distance of 8.5 
km from shore showing an increase of 10 dB in the 100 to 700 Hz band 
during heavy surf conditions.
     Precipitation: Sound from rain and hail impacting the 
water surface can become an important component of total sound at 
frequencies above 500 Hz, and possibly down to 100 Hz during quiet 
times.
     Biological: Marine mammals can contribute significantly to 
ambient sound levels, as can some fish and shrimp. The frequency band 
for biological contributions is from approximately 12 Hz to over 100 
kHz.
     Anthropogenic: Sources of ambient sound related to human 
activity include transportation (surface vessels and aircraft), 
dredging and construction, oil and gas drilling and production, seismic 
surveys, sonar, explosions, and ocean acoustic studies. Shipping sound 
typically dominates the total ambient sound for frequencies between 20 
and

[[Page 52151]]

300 Hz. In general, the frequencies of anthropogenic sounds are below 1 
kHz and, if higher frequency sound levels are created, they attenuate 
rapidly. Sound from identifiable anthropogenic sources other than the 
activity of interest (e.g., a passing vessel) is sometimes termed 
background sound, as opposed to ambient sound.
    The sum of the various natural and anthropogenic sound sources at 
any given location and time--which comprise ``ambient'' or 
``background'' sound--depends not only on the source levels (as 
determined by current weather conditions and levels of biological and 
shipping activity) but also on the ability of sound to propagate 
through the environment. In turn, sound propagation is dependent on the 
spatially and temporally varying properties of the water column and sea 
floor, and is frequency-dependent. As a result of the dependence on a 
large number of varying factors, ambient sound levels can be expected 
to vary widely over both coarse and fine spatial and temporal scales. 
Sound levels at a given frequency and location can vary by 10-20 dB 
from day to day (Richardson et al., 1995). The result is that, 
depending on the source type and its intensity, sound from the 
specified activity may be a negligible addition to the local 
environment or could form a distinctive signal that may affect marine 
mammals.
    The underwater acoustic environment in the Mayport turning basin is 
likely to be dominated by noise from day-to-day port and vessel 
activities. The basin is sheltered from most wave noise, but is a high-
use area for naval ships, tugboats, and security vessels. When 
underway, these sources can create noise between 20 Hz and 16 kHz 
(Lesage et al., 1999), with broadband noise levels up to 180 dB. While 
there are no current measurements of ambient noise levels in the 
turning basin, it is likely that levels within the basin periodically 
exceed the 120 dB threshold and, therefore, that the high levels of 
anthropogenic activity in the basin create an environment far different 
from quieter habitats where behavioral reactions to sounds around the 
120 dB threshold have been observed (e.g., Malme et al., 1984, 1988).

Sound Source Characteristics

    In-water construction activities associated with the project would 
include vibratory pile driving and possibly impact pile driving. The 
sounds produced by these activities fall into one of two sound types: 
pulsed and non-pulsed (defined in the following). The distinction 
between these two general sound types is important because they have 
differing potential to cause physical effects, particularly with regard 
to hearing (e.g., Ward, 1997 in Southall et al., 2007). Please see 
Southall et al., (2007) for an in-depth discussion of these concepts.
    Pulsed sound sources (e.g., explosions, gunshots, sonic booms, 
impact pile driving) produce signals that are brief (typically 
considered to be less than 1 sec), broadband, atonal transients (ANSI, 
1986; Harris, 1998; NIOSH, 1998; ISO, 2003; ANSI, 2005) and occur 
either as isolated events or repeated in some succession. Pulsed sounds 
are all characterized by a relatively rapid rise from ambient pressure 
to a maximal pressure value followed by a rapid decay period that may 
include a period of diminishing, oscillating maximal and minimal 
pressures, and generally have an increased capacity to induce physical 
injury as compared with sounds that lack these features.
    Non-pulsed sounds can be tonal, narrowband, or broadband, brief or 
prolonged, and may be either continuous or non-continuous (ANSI, 1995; 
NIOSH, 1998). Some of these non-pulsed sounds can be transient signals 
of short duration but without the essential properties of pulses (e.g., 
rapid rise time). Examples of non-pulsed sounds include those produced 
by vessels, aircraft, machinery operations such as drilling or 
dredging, vibratory pile driving, and active sonar systems. The 
duration of such sounds, as received at a distance, can be greatly 
extended in a highly reverberant environment.
    Impact hammers operate by repeatedly dropping a heavy piston onto a 
pile to drive the pile into the substrate. Sound generated by impact 
hammers is characterized by rapid rise times and high peak levels, a 
potentially injurious combination (Hastings and Popper, 2005). 
Vibratory hammers install piles by vibrating them and allowing the 
weight of the hammer to push them into the sediment. Vibratory hammers 
produce significantly less sound than impact hammers. Peak SPLs may be 
180 dB or greater, but are generally 10 to 20 dB lower than SPLs 
generated during impact pile driving of the same-sized pile (Oestman et 
al., 2009). Rise time is slower, reducing the probability and severity 
of injury, and sound energy is distributed over a greater amount of 
time (Nedwell and Edwards, 2002; Carlson et al., 2005).

Sound Thresholds

    NMFS currently uses acoustic exposure thresholds as important tools 
to help better characterize and quantify the effects of human-induced 
noise on marine mammals. These thresholds have predominantly been 
presented in the form of single received levels for particular source 
categories (e.g., impulse, continuous, or explosive) above which an 
exposed animal would be predicted to incur auditory injury or be 
behaviorally harassed. Current NMFS practice (in relation to the MMPA) 
regarding exposure of marine mammals to sound is that cetaceans and 
pinnipeds exposed to sound levels of 180 and 190 dB rms or above, 
respectively, are considered to have been taken by Level A (i.e., 
injurious) harassment, while behavioral harassment (Level B) is 
considered to have occurred when marine mammals are exposed to sounds 
at or above 120 dB rms for continuous sound (such as will be produced 
by vibratory pile driving) and 160 dB rms for pulsed sound (produced by 
impact pile driving), but below injurious thresholds. NMFS uses these 
levels as guidelines to estimate when harassment may occur.
    NMFS is in the process of revising these acoustic thresholds, with 
the first step being to identify new auditory injury criteria for all 
source types and new behavioral criteria for seismic activities 
(primarily airgun-type sources). For more information on that process, 
please visit https://www.nmfs.noaa.gov/pr/acoustics/guidelines.htm.

Distance to Sound Thresholds

    Pile driving generates underwater noise that can potentially result 
in disturbance to marine mammals in the project area. In order to 
estimate the distance at which sound produced by the specified activity 
would attenuate to relevant thresholds, one must, at minimum, be able 
to reasonably approximate source levels and transmission loss (TL), 
which is the decrease in acoustic intensity as an acoustic pressure 
wave propagates out from a source. In general, the sound pressure level 
(SPL) at some distance away from the source (e.g., driven pile) is 
governed by a measured source level, minus the TL of the energy as it 
dissipates with distance.
    The degree to which underwater sound propagates away from a sound 
source is dependent on a variety of factors, including source depth and 
frequency, receiver depth, water depth, bottom composition and 
topography, presence or absence of reflective or absorptive in-water 
structures, and oceanographic conditions such as temperature, current, 
and water chemistry. The general formula for

[[Page 52152]]

underwater TL neglects loss due to scattering and absorption, which is 
assumed to be zero here. Spherical spreading occurs in a perfectly 
unobstructed (free-field) environment not limited by depth or water 
surface, resulting in a 6 dB reduction in sound level for each doubling 
of distance from the source (20*log[range]). Cylindrical spreading 
occurs in an environment in which sound propagation is bounded by the 
water surface and sea bottom, resulting in a reduction of 3 dB in sound 
level for each doubling of distance from the source (10*log[range]). A 
practical spreading value of 15 (4.5 dB reduction in sound level for 
each doubling of distance) is often used under intermediate conditions, 
and is assumed here.
    Source level, or the intensity of pile driving sound, is greatly 
influenced by factors such as the type of piles, hammers, and the 
physical environment in which the activity takes place. A number of 
studies, primarily on the west coast, have measured sound produced 
during underwater pile driving projects. However, these data are 
largely for impact driving of steel pipe piles and concrete piles as 
well as vibratory driving of steel pipe piles. We know of no existing 
measurements for the specific pile types planned for use at NSM (i.e., 
king piles, paired sheet piles, plastic pipe piles), although some data 
exist for single sheet piles. It was therefore necessary to extrapolate 
from available data to determine reasonable source levels for this 
project.
    In order to determine reasonable SPLs and their associated effects 
on marine mammals that are likely to result from pile driving at NSM, 
the Navy first compared linear lengths (in terms of radiative surface 
length) of the pile types proposed for use with those for which 
measurements of underwater SPLs exist. For example, the total linear 
length of a king pile (with width of 17.87 in and height of 41.47 in) 
is equivalent to the circumference (i.e., linear length) of a 24-in 
diameter pipe pile. Please see Table 6-2 of the Navy's application for 
more detail on these comparisons. We recognize that these pile types 
may produce sound differently, given different radiative geometries, 
and that there may be differences in the frequency spectrum produced, 
but believe this to be the best available method of determining proxy 
source levels. We considered existing measurements from similar 
physical environments (sandy sediments and water depths greater than 15 
ft) for impact and vibratory driving of 24-in steel pipe piles and for 
steel sheet piles. These studies, largely conducted by the Washington 
State Department of Transportation and the California Department of 
Transportation, show values around 160 dB for vibratory driving of 24-
in pipe piles and around 162 dB for vibratory driving of sheet piles, 
and around 185-195 dB for impact driving of pipe piles (all measured at 
10 m). Please see Laughlin (2005); Oestman et al. (2009); and 
Illingworth and Rodkin, Inc. (2010) for more information. For vibratory 
driving, 163 dB (as the highest representative value; Oestman et al., 
2009) was selected as a proxy source value for both sheet piles and 
king piles. For impact driving of both sheet piles and king piles 
(should it be required), a proxy source value of 189 dB (Oestman et 
al., 2009) was selected for use in acoustic modeling based on 
similarity to the physical environment at NSM and because of the 
measurement location in mid-water column. No measurements are known to 
be available for vibratory driving of plastic polymer piles, so timber 
piles were considered as likely to be the most similar pile material. 
Although timber piles are typically installed via impact drivers, 
Laughlin (2011) reported a mean source measurement (at 16 m) for 
vibratory removal of timber piles. This value (150 dB) was selected as 
a proxy source value on the basis of similarity of materials between 
timber and polymer. No impact driving of polymer piles will occur. 
Please see Tables 6-3 and 6-4 in the Navy's application. All calculated 
distances to and the total area encompassed by the marine mammal sound 
thresholds are provided in Table 1.

Table 1--Calculated Distance(s) to and Area Encompassed by Underwater Marine Mammal Sound Thresholds During Pile
                                                  Installation
----------------------------------------------------------------------------------------------------------------
                                                                                     Distance       Area  (sq.
             Pile type                      Method               Threshold            (m)\1\          km)\2\
----------------------------------------------------------------------------------------------------------------
Steel (sheet and king piles)......  Vibratory............  Level A harassment                n/a               0
                                                            (180 dB).
                                                           Level B harassment              7,356             2.9
                                                            (120 dB).
                                    Impact...............  Level A harassment                 40           0.004
                                                            (180 dB).
                                                           Level B harassment                858            0.67
                                                            (160 dB).
Polymeric (plastic fender piles)..  Vibratory............  Level A harassment                n/a               0
                                                            (180 dB).
                                                           Level B harassment              1,585            0.88
                                                            (120 dB).
----------------------------------------------------------------------------------------------------------------
\1\ SPLs used for calculations were: 204 dB for impact driving, 178 dB for vibratory driving steel piles, and
  168 dB for vibratory driving plastic piles.
\2\ Areas presented take into account attenuation and/or shadowing by land. Calculated distances to relevant
  thresholds cannot be reached in most directions form source piles. Please see Figures 6-1 through 6-3 in the
  Navy's application.

    The Mayport turning basin does not represent open water, or free 
field, conditions. Therefore, sounds would attenuate as per the 
confines of the basin, and may only reach the full estimated distances 
to the harassment thresholds via the narrow, east-facing entrance 
channel. Distances shown in Table 1 are estimated for free-field 
conditions, but areas are calculated per the actual conditions of the 
action area. See Figures 6-1 through 6-3 of the Navy's application for 
a depiction of areas in which each underwater sound threshold is 
predicted to occur at the project area due to pile driving.

Description of Marine Mammals in the Area of the Specified Activity

    There are four marine mammal species which may inhabit or transit 
through the waters nearby NSM at the mouth of the St. Johns River and 
in nearby nearshore Atlantic waters. These include the bottlenose 
dolphin, Atlantic spotted dolphin, North Atlantic right whale 
(Eubalaena glacialis), and humpback whale (Megaptera novaeangliae). 
Multiple additional cetacean species occur in South Atlantic waters but 
would not be expected to occur in shallow nearshore waters of the 
action area. The right and humpback whales are both listed under the 
Endangered Species Act (ESA) as endangered. Table 2 lists the marine 
mammal species with expected potential for occurrence in the vicinity 
of NSM during the project timeframe.

[[Page 52153]]

Multiple stocks of bottlenose dolphins may be present in the action 
area, either seasonally or year-round, and are described further below. 
We first address the two large whale species that may occur in the 
action area.

                       Table 2--Marine Mammals Potentially Present in the Vicinity of NSM
----------------------------------------------------------------------------------------------------------------
                                     Stock abundance \1\    Relative occurrence
              Species                     (CV, Nmin)          in  action area          Season of occurrence
----------------------------------------------------------------------------------------------------------------
North Atlantic right whale Western  444 (n/a, 444).......  Rare inshore,         November to April.
 North Atlantic stock.                                      regular near/
                                                            offshore.
Humpback whale Gulf of Maine stock  823 (n/a, 823).......  Rare................  Fall-Spring.
Atlantic spotted dolphin Western    26,798 (0.66, 16,151)  Rare................  Year-round.
 North Atlantic stock.
Bottlenose dolphin Western North    81,588 (0.17, 70,775)  Rare................  Year-round.
 Atlantic offshore stock.
Bottlenose dolphin Western North    12,482 (0.32, 9,591).  Possibly common       January to March.
 Atlantic coastal, southern                                 (seasonal).
 migratory stock.
Bottlenose dolphin Western North    3,064 (0.24, 2,511)..  Possibly common.....  Year-round.
 Atlantic coastal, northern
 Florida stock.
Bottlenose dolphin Jacksonville     412 \2\ (0.06,         Possibly common.....  Year-round.
 Estuarine System stock.             unknown).
----------------------------------------------------------------------------------------------------------------
\1\ NMFS marine mammal stock assessment reports at: https://www.nmfs.noaa.gov/pr/sars/species.htm. CV is
  coefficient of variation; Nmin is the minimum estimate of stock abundance.
\2\ This abundance estimate is considered an overestimate because it includes non- and seasonally-resident
  animals.

    Right whales occur in sub-polar to temperate waters in all major 
ocean basins in the world with a clear migratory pattern, occurring in 
high latitudes in summer (feeding) and lower latitudes in winter 
(breeding). North Atlantic right whales exhibit extensive migratory 
patterns, traveling along the eastern seaboard from calving grounds off 
Georgia and northern Florida to northern feeding areas off of the 
northeast U.S. and Canada in March/April and returning in November/
December. Migrations are typically within 30 nmi of the coastline and 
in waters less than 160 ft deep. Although this migratory pattern is 
well-known, winter distribution for most of the population--the non-
calving portion--is poorly known, as many whales are not observed on 
the calving grounds. It is unknown where these animals spend the 
winter, although they may occur further offshore or may remain on 
foraging grounds during winter (Morano et al., 2012). During the winter 
calving period, right whales occur regularly in offshore waters of 
northeastern Florida. Critical habitat for right whales in the 
southeast (as identified under the ESA) is designated to protect 
calving grounds, and encompasses waters from the coast out to 15 nmi 
offshore from Mayport. More rarely, right whales have been observed 
entering the mouth of the St. Johns River for brief periods of time 
(Schweitzer and Zoodsma, 2011). Right whales are not present in the 
region outside of the winter calving season.
    Humpback whales are a cosmopolitan species that migrate seasonally 
between warm-water (tropical or sub-tropical) breeding and calving 
areas in winter months and cool-water (temperate to sub-Arctic/
Antarctic) feeding areas in summer months (Gendron and Urban, 1993). 
They tend to occupy shallow, coastal waters, although migrations are 
undertaken through deep, pelagic waters. In the North Atlantic, 
humpback whales are known to aggregate in six summer feeding areas 
representing relatively discrete subpopulations (Clapham and Mayo, 
1987), which share common wintering grounds in the Caribbean (and to a 
lesser extent off of West Africa) (Winn et al., 1975; Mattila et al., 
1994; Palsb[oslash]ll et al., 1997; Smith et al., 1999; Stevick et al., 
2003; Cerchio et al., 2010). These populations or aggregations range 
from the Gulf of Maine in the west to Norway in the east, and the 
migratory range includes the east coast of the U.S. and Canada. The 
only managed stock in U.S. waters is the Gulf of Maine feeding 
aggregation, although other stocks occur in Canadian waters (e.g., Gulf 
of St. Lawrence feeding aggregation), and it is possible that whales 
from other stocks could occur in U.S. waters. Significant numbers of 
whales do remain in mid- to high-latitude waters during the winter 
months (Clapham et al., 1993; Swingle et al., 1993), and there have 
been a number of humpback sightings in coastal waters of the 
southeastern U.S. during the winter (Wiley et al., 1995; Laerm et al., 
1997; Waring et al., 2013). According to Waring et al. (2013), it is 
unclear whether the increased numbers of sightings represent a 
distributional change, or are simply due to an increase in sighting 
effort and/or whale abundance. These factors aside, the humpback whale 
remains relatively rare in U.S. coastal waters south of the mid-
Atlantic region, and is considered rare to extralimital in the action 
area. Any occurrences in the region would be expected in fall, winter, 
and spring during migration, as whales are unlikely to occur so far 
south during the summer feeding season.
    Neither the humpback whale nor the right whale would occur within 
the turning basin, and only the right whale has been observed to occur 
as far inshore as the mouth of the St. Johns River. Therefore, the only 
potential for interaction with these species is likely to be within the 
narrow sliver of ensonified area expected to extend eastward from the 
entrance channel during vibratory driving of steel piles (see Figure 6-
1 of the application). As described above, humpback whales are 
considered rare in the region, and, when considering frequency of 
occurrence, size of ensonified area (approximately 2 km\2\), and 
duration (45 days), we consider the possibility for harassment of 
humpback whales to be discountable. For right whales, due to the 
greater potential for interaction during the calving season we 
considered available density information, including abundance data from 
NMFS surveys, as analyzed by the Navy to produce density estimates 
(NODES dataset; DoN, 2007); Duke University habitat modeling (Read et 
al., 2009); and global density estimates derived from relative 
environmental suitability modeling (Kaschner, 2004; Kaschner et al., 
2006), as presented in DoN (2012). All sources show low density 
estimates. The Navy used the Kaschner et al. (2006) modeling, as 
described in the Navy Marine Species Density Database (DoN, 2012), to 
produce a representative estimate for the specific action area. Density 
values for the inshore zone were uniform across seasons; seasonal 
distribution changes that may be expected for right whales are 
reflected further offshore from the Mayport turning basin. Use of this 
estimate (0.00005/km\2\) resulted in zero estimated exposures of right 
whales to sound produced by project activities.

[[Page 52154]]

Only a small portion of the affected area (0.19 km\2\; less than 5 
percent of total ZOI) falls in the offshore zone for which seasonal 
densities are available, and including that area with the highest 
yearly density (0.124/km\2\; Dec-Mar; NODES dataset) does not affect 
the zero-exposure prediction. Therefore, the humpback whale and right 
whale are excluded from further analysis and are not discussed further 
in this document.
    The following summarizes the population status and abundance of the 
remaining species. We have reviewed the Navy's species descriptions, 
including life history information, for accuracy and completeness and 
refer the reader to Sections 3 and 4 of the Navy's application, as well 
as to the Navy's Marine Resource Assessment for the Charleston/
Jacksonville Operating Area (DoN, 2008; available at https://portal.navfac.navy.mil/portal/page/portal/navfac/navfac_ww_pp/navfac_hq_pp/navfac_environmental/mra), instead of reprinting the 
information here. The following information is summarized largely from 
NMFS Stock Assessment Reports (https://www.nmfs.noaa.gov/pr/sars/).

Bottlenose Dolphin

    Bottlenose dolphins are found worldwide in tropical to temperate 
waters and can be found in all depths from estuarine inshore to deep 
offshore waters. Temperature appears to limit the range of the species, 
either directly, or indirectly, for example, through distribution of 
prey. Off North American coasts, common bottlenose dolphins are found 
where surface water temperatures range from about 10 [deg]C to 32 
[deg]C. In many regions, including the southeastern U.S., separate 
coastal and offshore populations are known. There is significant 
genetic, morphological, and hematological differentiation evident 
between the two ecotypes (e.g., Walker, 1981; Duffield et al., 1983; 
Duffield, 1987; Hoelzel et al., 1998), which correspond to shallow, 
warm water and deep, cold water. Both ecotypes have been shown to 
inhabit the western North Atlantic (Hersh and Duffield, 1990; Mead and 
Potter, 1995), where the deep-water ecotype tends to be larger and 
darker. In addition, several lines of evidence, including photo-
identification and genetic studies, support a distinction between 
dolphins inhabiting coastal waters near the shore and those present in 
the inshore waters of bays, sounds and estuaries. This complex 
differentiation of bottlenose dolphin populations is observed 
throughout the Atlantic and Gulf of Mexico coasts where bottlenose 
dolphins are found, although estuarine populations have not been fully 
defined.
    In the Mayport area, four stocks of bottlenose dolphins are 
currently managed, none of which are protected under the ESA. Of the 
four stocks--offshore, southern migratory coastal, northern Florida 
coastal, and Jacksonville estuarine system--only the latter three are 
likely to occur in the action area. Bottlenose dolphins typically occur 
in groups of 2-15 individuals (Shane et al., 1986; Kerr et al., 2005). 
Although significantly larger groups have also been reported, smaller 
groups are typical of shallow, confined waters. In addition, such 
waters typically support some degree of regional site fidelity and 
limited movement patterns (Shane et al., 1986; Wells et al., 1987). 
Observations made during recent marine mammal surveys conducted in the 
Mayport turning basin show bottlenose dolphins typically occurring 
individually or in pairs, or less frequently in larger groups. The 
maximum observed group size during these surveys is six, while the mode 
is one. Navy observations indicate that bottlenose dolphins rarely 
linger in a particular area in the turning basin, but rather appear to 
move purposefully through the basin and then leave, which likely 
reflects a lack of any regular foraging opportunities or habitat 
characteristics of any importance in the basin. Based on currently 
available information, it is not possible to determine which stock 
dolphins occurring in the action area may belong to. These stocks are 
described in greater detail below.
    Western North Atlantic Offshore--This stock, consisting of the 
deep-water ecotype or offshore form of bottlenose dolphin in the 
western North Atlantic, is distributed primarily along the outer 
continental shelf and continental slope, but has been documented to 
occur relatively close to shore (Waring et al., 2009a). The separation 
between offshore and coastal morphotypes varies depending on location 
and season, with the ranges overlapping to some degree south of Cape 
Hatteras. Based on genetic analysis, Torres et al. (2003) found a 
distributional break at 34 km from shore, with the offshore form found 
exclusively seaward of 34 km and in waters deeper than 34 m. Within 7.5 
km of shore, all animals were of the coastal morphotype. More recently, 
coastwide, systematic biopsy collection surveys were conducted during 
the summer and winter to evaluate the degree of spatial overlap between 
the two morphotypes. South of Cape Hatteras, spatial overlap was found 
although the probability of a sampled group being from the offshore 
morphotype increased with increasing depth, and the closest distance 
for offshore animals was 7.3 km from shore, in water depths of 13 m 
just south of Cape Lookout (Garrison et al., 2003). The maximum radial 
distance for the largest ZOI is approximately 7.4 km (Table 1); 
therefore, while possible, it is unlikely that any individuals of the 
offshore morphotype would be affected by project activities. In terms 
of water depth, the affected area is generally in the range of the 
shallower depth reported for offshore dolphins by Garrison et al. 
(2003), but is far shallower than the depths reported by Torres et al. 
(2003). South of Cape Lookout, the zone of spatial overlap between 
offshore and coastal ecotypes is generally considered to occur in water 
depths between 20-100 m (Waring et al., 2011), which is generally 
deeper than waters in the action area. This stock is thus excluded from 
further analysis.
    Western North Atlantic Coastal, Southern Migratory--The coastal 
morphotype of bottlenose dolphin is continuously distributed from the 
Gulf of Mexico to the Atlantic and north approximately to Long Island 
(Waring et al., 2011). On the Atlantic coast, Scott et al. (1988) 
hypothesized a single coastal stock, citing stranding patterns during a 
high mortality event in 1987-88 and observed density patterns. More 
recent studies demonstrate that there is instead a complex mosaic of 
stocks (Zolman, 2002; McLellan et al., 2003; Rosel et al., 2009). The 
coastal morphotype was managed by NMFS as a single stock until 2009, 
when it was split into five separate stocks, including northern and 
southern migratory stocks.
    According to the Scott et al. (1988) hypothesis, a single stock was 
thought to migrate seasonally between New Jersey (summer) and central 
Florida (winter). Instead, it was determined that a mix of resident and 
migratory stocks exists, with the migratory movements and spatial 
distribution of the southern migratory stock the most poorly understood 
of these. Stable isotope analysis and telemetry studies provide 
evidence for seasonal movements of dolphins between North Carolina and 
northern Florida (Knoff, 2004; Waring et al., 2011), and genetic 
analyses and tagging studies support differentiation of northern and 
southern migratory stocks (Rosel et al., 2009; Waring et al., 2011). 
Although there is significant uncertainty regarding the southern 
migratory stock's spatial movements, telemetry data indicates that the 
stock occupies waters of southern North Carolina (south of Cape 
Lookout) during the fall (October-December). In winter

[[Page 52155]]

months (January-March), the stock moves as far south as northern 
Florida where it overlaps spatially with the northern Florida coastal 
and Jacksonville estuarine system stocks. In spring (April-June), the 
stock returns north to waters of North Carolina, and is presumed to 
remain north of Cape Lookout during the summer months. Therefore, the 
potential exists for harassment of southern migratory dolphins, most 
likely during the winter only.
    Bottlenose dolphins are ubiquitous in coastal waters from the mid-
Atlantic through the Gulf of Mexico, and therefore interact with 
multiple coastal fisheries, including gillnet, trawl, and trap/pot 
fisheries. Stock-specific total fishery-related mortality and serious 
injury cannot be directly estimated because of the spatial overlap 
among stocks of bottlenose dolphins, as well as because of unobserved 
fisheries. The primary known source of fishery mortality for the 
southern migratory stock is the mid-Atlantic gillnet fishery, and the 
total estimated average annual fishery mortality (for all fisheries, 
based on data from 2004-08) for the stock ranges between a minimum of 
24 and a maximum of 55 animals per year (Waring et al., 2011). Between 
2004 and 2008, 588 bottlenose dolphins stranded along the Atlantic 
coast between Florida and Maryland that could potentially be assigned 
to the southern migratory stock, although the assignment of animals to 
a particular stock is impossible in some seasons and regions due to 
spatial overlap amongst stocks (Waring et al., 2011). Many of these 
animals exhibited some evidence of human interaction, such as line/net 
marks, gunshot wounds, or vessel strike. In addition, nearshore and 
estuarine habitats occupied by the coastal morphotype are adjacent to 
areas of high human population and some are highly industrialized. It 
should also be noted that stranding data underestimate the extent of 
fishery-related mortality and serious injury because not all of the 
marine mammals that die or are seriously injured in fishery 
interactions are discovered, reported or investigated, nor will all of 
those that are found necessarily show signs of entanglement or other 
fishery interaction. The level of technical expertise among stranding 
network personnel varies widely as does the ability to recognize signs 
of fishery interactions. Finally, multiple resident populations of 
bottlenose dolphins have been shown to have high concentrations of 
organic pollutants (e.g., Kuehl et al., 1991) and, despite little study 
of contaminant loads in migrating coastal dolphins, exposure to 
environmental pollutants and subsequent effects on population health is 
an area of concern and active research.
    The original, single stock of coastal dolphins recognized from 
1995-2001 was listed as depleted under the MMPA as a result of a 1987-
88 mortality event. That designation was retained when the single stock 
was split into multiple coastal stocks. Therefore, and as a result of 
the aforementioned factors, southern migratory dolphins are listed as 
depleted under the MMPA, and are also considered a strategic stock. The 
best abundance estimate for southern migratory dolphins is calculated 
from aerial surveys conducted in summer of 2002 (the least amount of 
stock overlap occurs during summer months). A more recent summer survey 
(2004) occurred during oceanographic conditions that resulted in 
significantly greater stock overlap. The resulting estimate of 12,842 
(CV = 0.32) is used to calculate a minimum population estimate of 9,591 
and potential biological removal (PBR) of 96 animals. Insufficient data 
exist to determine the population trends for this stock, and 
productivity rates are not known, although theoretical modeling shows 
that cetacean populations may not grow at rates much greater than 4 
percent given the constraints of their reproductive life history 
(Barlow et al., 1995).
    Western North Atlantic Coastal, Northern Florida--Please see above 
for description of the differences between coastal and offshore 
ecotypes and the delineation of coastal dolphins into management 
stocks. The northern Florida coastal stock is one of five stocks of 
coastal dolphins and one of three known resident stocks (other resident 
stocks include South Carolina/Georgia and central Florida dolphins). 
The spatial extent of these stocks, their potential seasonal movements, 
and their relationships with estuarine stocks are poorly understood. 
During summer months, when the migratory stocks are known to be in 
North Carolina waters and further north, bottlenose dolphins are still 
seen in coastal waters of South Carolina, Georgia and Florida, 
indicating the presence of additional stocks of coastal animals. 
Speakman et al. (2006) documented dolphins in coastal waters off 
Charleston, South Carolina, that are not known resident members of the 
estuarine stock, and genetic analyses indicate significant differences 
between coastal dolphins from northern Florida, Georgia and central 
South Carolina (NMFS, 2001; Rosel et al., 2009). The northern Florida 
stock is thought to be present from approximately the Georgia-Florida 
border south to 29.4[deg]N.
    The northern Florida coastal stock is susceptible to interactions 
with similar fisheries as those described above for the southern 
migratory stock, including gillnet, trawl, and trap/pot fisheries. No 
fisheries-related mortality attributable to this stock has been 
reported (according to 2004-08 data; Waring et al., 2011); however, 
many of these fisheries are not observed or have limited observer 
coverage and bottlenose dolphins are known to interact with these types 
of gear. From 2004-08, 78 stranded dolphins were recovered in northern 
Florida waters, although it was not possible to determine whether there 
was evidence of human interaction for the majority of these (Waring et 
al., 2011). The same concerns discussed above regarding underestimation 
of mortality hold for this stock and, as for southern migratory 
dolphins, pollutant loading is a concern.
    The single stock of coastal bottlenose dolphins recognized by NMFS 
until 2001 was listed as depleted under the MMPA. All five stocks of 
coastal bottlenose dolphin that were subsequently recognized retain 
that designation, and are also therefore considered strategic stocks. 
The best abundance estimate, derived from aerial surveys conducted in 
summer months of 2002 and 2004, is 3,064 (CV = 0.24). The abundance 
estimates from these two surveys differed by nearly an order of 
magnitude, perhaps reflecting variability in spatial distribution for 
coastal dolphins. The resulting minimum population estimate is 2,511, 
and the PBR is 25 individuals. There are insufficient data to determine 
population trends or net productivity rates for this stock.
    Jacksonville Estuarine System--Please see above for description of 
the differences between coastal and offshore ecotypes and the 
delineation of coastal dolphins into management stocks primarily 
inhabiting nearshore waters. The coastal morphotype of bottlenose 
dolphin is also resident to certain inshore estuarine waters (Caldwell, 
2001; Gubbins, 2002; Zolman, 2002; Gubbins et al., 2003). Multiple 
lines of evidence support demographic separation between coastal 
dolphins found in nearshore waters and those in estuarine waters, as 
well as between dolphins residing within estuaries along the Atlantic 
and Gulf coasts (e.g., Wells et al., 1987; Scott et al., 1990; Wells et 
al., 1996; Cortese, 2000; Zolman, 2002; Speakman, et al. 2006; Stolen 
et al., 2007; Balmer et al., 2008; Mazzoil et al., 2008). In 
particular, a study conducted near Jacksonville demonstrated

[[Page 52156]]

significant genetic differences between coastal and estuarine dolphins 
(Caldwell, 2001; Rosel et al., 2009). Despite evidence for genetic 
differentiation between estuarine and nearshore populations, the degree 
of spatial overlap between these populations remains unclear. Photo-
identification studies within estuaries demonstrate seasonal 
immigration and emigration and the presence of transient animals (e.g., 
Speakman et al., 2006). In addition, the degree of movement of resident 
estuarine animals into coastal waters on seasonal or shorter time 
scales is poorly understood (Waring et al., 2011).
    The Jacksonville estuarine system (JES) stock has been defined as 
separate primarily by the results of photo-identification and genetic 
studies. The stock range is considered to be bounded in the north by 
the Georgia-Florida border at Cumberland Sound, extending south to 
approximately Jacksonville Beach, Florida. This encompasses an area 
defined during a photo-identification study of bottlenose dolphin 
residency patterns in the area (Caldwell, 2001), and the borders are 
subject to change upon further study of dolphin residency patterns in 
estuarine waters of southern Georgia and northern/central Florida. The 
habitat is comprised of several large brackish rivers, including the 
St. Johns River, as well as tidal marshes and shallow riverine systems. 
Three behaviorally different communities were identified during 
Caldwell's (2001) study: the estuarine waters north (Northern) and 
south (Southern) of the St. Johns River and the coastal area, all of 
which differed in density, habitat fidelity and social affiliation 
patterns. The coastal dolphins are believed to be members of a coastal 
stock, however (Waring et al., 2009b). Although Northern and Southern 
members of the JES stock show strong site fidelity, members of both 
groups have been observed outside their preferred areas. Dolphins 
residing within estuaries south of Jacksonville Beach down to the 
northern boundary of the Indian River Lagoon Estuarine System (IRLES) 
stock are currently not included in any stock, as there are 
insufficient data to determine whether animals in this area exhibit 
affiliation to the JES stock, the IRLES stock, or are simply transient 
animals associated with coastal stocks. Further research is needed to 
establish affinities of dolphins in the area between the ranges, as 
currently understood, of the JES and IRLES stocks.
    The JES stock is susceptible to similar fisheries interactions as 
those described above for coastal stocks, although only trap/pot 
fisheries are likely to occur in estuarine waters frequented by the 
stock. Only one dolphin carcass bearing evidence of fisheries 
interaction was recovered during 2003-07 in the JES area (Waring et 
al., 2009b). An additional sixteen stranded dolphins were recovered 
during this time, but no determinations regarding human interactions 
could be made for the majority. The same concerns discussed above 
regarding underestimation of mortality hold for this stock and, as for 
stocks discussed above, pollutant loading is a concern. Although no 
contaminant analyses have yet been conducted in this area, the JES 
stock inhabits areas with significant drainage from industrial and 
urban sources, and as such is exposed to contaminants in runoff from 
these. In other estuarine areas where such analyses have been 
conducted, exposure to anthropogenic contaminants has been found to 
likely have an effect (Hansen et al. 2004; Schwacke et al., 2004; Reif 
et al., 2008).
    The original, single stock of coastal dolphins recognized from 
1995-2001 was listed as depleted under the MMPA as a result of a 1987-
88 mortality event. That designation was retained when the single stock 
was split into multiple coastal stocks. However, Scott et al. (1988) 
suggested that dolphins residing in the bays, sounds and estuaries 
adjacent to these coastal waters were not affected by the mortality 
event and these animals were explicitly excluded from the depleted 
listing (Waring et al., 2009b). Gubbins et al. (2003), using data from 
Caldwell (2001), estimated the stock size to be 412 (CV = 0.06). 
However, NMFS considers abundance unknown because this estimate likely 
includes an unknown number of non-resident and seasonally-resident 
dolphins. It nevertheless represents the best available information 
regarding stock size. The minimum population estimate and PBR are 
considered unknown, and there are insufficient data to determine 
population trends. Total human-caused mortality and serious injury for 
this stock is also unknown, but there are known to be significant 
interactions between estuarine bottlenose dolphins and crab pot 
fisheries in other areas (Burdett and McFee, 2004). Because the stock 
size is likely small, and relatively few mortalities and serious 
injuries would exceed PBR, the stock is considered to be a strategic 
stock (Waring et al., 2009b).

Atlantic Spotted Dolphin

    Atlantic spotted dolphins are distributed in tropical and warm 
temperate waters of the western North Atlantic predominantly over the 
continental shelf and upper slope, from southern New England through 
the Gulf of Mexico (Leatherwood et al., 1976). Spotted dolphins in the 
Atlantic Ocean and Gulf of Mexico are managed as separate stocks. The 
Atlantic spotted dolphin occurs in two forms which may be distinct sub-
species (Perrin et al., 1987; Rice, 1998); a larger, more heavily 
spotted form inhabits the continental shelf inside or near the 200-m 
isobath and is the only form that would be expected to occur in the 
action area. Although typically observed in deeper waters, spotted 
dolphins of the western North Atlantic stock do occur regularly in 
nearshore waters south of the Chesapeake Bay (Mullin and Fulling, 
2003). Specific data regarding seasonal occurrence in the region of 
activity is lacking, but higher numbers of individuals have been 
reported to occur in nearshore waters of the Gulf of Mexico from 
November to May, suggesting seasonal migration patterns (Griffin and 
Griffin, 2003).
    Atlantic spotted dolphins are not protected under the ESA or listed 
as depleted under the MMPA. The best abundance estimate of the western 
North Atlantic stock of Atlantic spotted dolphins is 26,798 (CV = 0.66) 
and the minimum population size of this stock is 16,151 individuals 
(Waring et al., 2013). This abundance estimate was generated from 
shipboard and aerial surveys conducted during June-August, 2011 (Palka, 
2012), and only includes data from northern U.S. waters. The aerial 
portion covered 5,313 km of trackline over waters shallower than the 
100-m depth contour, from north of New Jersey through the U.S. and 
Canadian Gulf of Maine and up to and including the lower Bay of Fundy. 
The shipboard portion covered 3,107 km of trackline in waters deeper 
than the 100-m depth contour out to and beyond the U.S. Exclusive 
Economic Zone. Additional survey effort was conducted in southern U.S. 
waters, from North Carolina to Florida, but data are currently being 
analyzed and are not included in this abundance estimate.
    The resulting PBR is calculated at 162 individuals. Total annual 
estimated average fishery-related mortality or serious injury to this 
stock during 2006-10 was 0.2 animals. An additional 19 animals were 
stranded during this period, but only one showed evidence of human 
interaction (Waring et al., 2013). These data likely underestimate the 
full extent of human-caused mortality. However, such mortality is 
nevertheless likely substantially less than the PBR; therefore, 
Atlantic spotted dolphins are not considered a strategic

[[Page 52157]]

stock under the MMPA. There are insufficient data to determine the 
population trends for this species because, prior to 1998, species of 
spotted dolphins were not differentiated during surveys (Waring et al., 
2013).

Potential Effects of the Specified Activity on Marine Mammals

    We have determined that pile driving, as outlined in the project 
description, has the potential to result in behavioral harassment of 
marine mammals that may be present in the project vicinity while 
construction activity is being conducted. In theory, impact pile 
driving could result in injury of marine mammals although, for reasons 
described later in this document, we do not believe such an outcome to 
be likely or even possible in some cases. The full range of potential 
effects of sound on marine mammals, and pile driving in particular, are 
described in this section.

Marine Mammal Hearing

    Effects on marine mammals anticipated from the specified activities 
would be expected to result primarily from exposure of animals to 
underwater sound. Hearing is the most important sensory modality for 
marine mammals, and exposure to sound can have deleterious effects. To 
appropriately assess these potential effects, it is necessary to 
understand the frequency ranges marine mammals are able to hear. 
Current data indicate that not all marine mammal species have equal 
hearing capabilities (Richardson et al., 1995; Wartzok and Ketten, 
1999). To reflect this, Southall et al. (2007) recommended that marine 
mammals be divided into functional hearing groups based on measured or 
estimated hearing ranges on the basis of available behavioral data, 
audiograms derived using auditory evoked potential techniques, 
anatomical modeling, and other data. The lower and/or upper frequencies 
for some of these functional hearing groups have been modified from 
those designated by Southall. The functional groups and the associated 
frequencies are indicated below (note that these frequency ranges do 
not necessarily correspond to the range of best hearing, which varies 
by species):
     Low-frequency cetaceans (mysticetes): functional hearing 
is estimated to occur between approximately 7 Hz and 30 kHz (extended 
from 22 kHz on the basis of data indicating some mysticetes can hear 
above 22 kHz; Au et al., 2006; Lucifredi and Stein, 2007; Ketten and 
Mountain, 2009; Tubelli et al., 2012);
     Mid-frequency cetaceans (larger toothed whales, beaked 
whales, and most delphinids): functional hearing is estimated to occur 
between approximately 150 Hz and 160 kHz;
     High-frequency cetaceans (porpoises, river dolphins, and 
members of the genera Kogia and Cephalorhynchus): functional hearing is 
estimated to occur between approximately 200 Hz and 180 kHz; and
     Pinnipeds in water: functional hearing is estimated to 
occur between approximately 75 Hz to 100 kHz for Phocidae (true seals) 
and between 100 Hz and 40 kHz for Otariidae (eared seals), with the 
greatest sensitivity between approximately 700 Hz and 20 kHz. The 
pinniped functional hearing group was modified from Southall et al. 
(2007) on the basis of data indicating that phocid species have 
consistently demonstrated an extended frequency range of hearing 
compared to otariids, especially in the higher frequency range 
(Hemil[auml] et al., 2006; Mulsow et al., 2011).
    Two cetacean species are expected to potentially be affected by the 
specified activity. The bottlenose and Atlantic spotted dolphins are 
classified as mid-frequency cetaceans (Southall et al., 2007).

Underwater Sound Effects

    Potential Effects of Pile Driving Sound--The effects of sounds from 
pile driving might result in one or more of the following: Temporary or 
permanent hearing impairment, non-auditory physical or physiological 
effects, behavioral disturbance, and masking (Richardson et al., 1995; 
Gordon et al., 2004; Nowacek et al., 2007; Southall et al., 2007). The 
effects of pile driving on marine mammals are dependent on several 
factors, including the size, type, and depth of the animal; the depth, 
intensity, and duration of the pile driving sound; the depth of the 
water column; the substrate of the habitat; the standoff distance 
between the pile and the animal; and the sound propagation properties 
of the environment. Impacts to marine mammals from pile driving 
activities are expected to result primarily from acoustic pathways. As 
such, the degree of effect is intrinsically related to the received 
level and duration of the sound exposure, which are in turn influenced 
by the distance between the animal and the source. The further away 
from the source, the less intense the exposure should be. The substrate 
and depth of the habitat affect the sound propagation properties of the 
environment. Shallow environments are typically more structurally 
complex, which leads to rapid sound attenuation. In addition, 
substrates that are soft (e.g., sand) would absorb or attenuate the 
sound more readily than hard substrates (e.g., rock) which may reflect 
the acoustic wave. Soft porous substrates would also likely require 
less time to drive the pile, and possibly less forceful equipment, 
which would ultimately decrease the intensity of the acoustic source.
    In the absence of mitigation, impacts to marine species may result 
from physiological and behavioral responses to both the type and 
strength of the acoustic signature (Viada et al., 2008). The type and 
severity of behavioral impacts are more difficult to define due to 
limited studies addressing the behavioral effects of impulsive sounds 
on marine mammals. Potential effects from impulsive sound sources can 
range in severity, ranging from effects such as behavioral disturbance, 
tactile perception, physical discomfort, slight injury of the internal 
organs and the auditory system, to mortality (Yelverton et al., 1973).
    Hearing Impairment and Other Physical Effects--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 not recoverable, or 
temporary (TTS), in which case the animal's hearing threshold would 
recover over time (Southall et al., 2007). Marine mammals depend on 
acoustic cues for vital biological functions, (e.g., orientation, 
communication, finding prey, avoiding predators); thus, TTS may result 
in reduced fitness in survival and reproduction. However, this depends 
on the frequency and duration of TTS, as well as the biological context 
in which it occurs. TTS of limited duration, occurring in a frequency 
range that does not coincide with that used for recognition of 
important acoustic cues, would have little to no effect on an animal's 
fitness. Repeated sound exposure that leads to TTS could cause PTS. 
PTS, in the unlikely event that it occurred, would constitute injury, 
but TTS is not considered injury (Southall et al., 2007). It is 
unlikely that the project would result in any cases of temporary or 
especially permanent hearing impairment or any significant non-auditory 
physical or physiological effects for reasons discussed later in this 
document. Some behavioral disturbance is expected, but it is likely 
that this would be localized and short-term because of the short 
project duration.
    Several aspects of the planned monitoring and mitigation measures 
for

[[Page 52158]]

this project (see the ``Proposed Mitigation'' and ``Proposed Monitoring 
and Reporting'' sections later in this document) are designed to detect 
marine mammals occurring near the pile driving to avoid exposing them 
to sound pulses that might, in theory, cause hearing impairment. In 
addition, many cetaceans are likely to show some avoidance of the area 
where received levels of pile driving sound are high enough that 
hearing impairment could potentially occur. In those cases, the 
avoidance responses of the animals themselves would reduce or (most 
likely) avoid any possibility of hearing impairment. Non-auditory 
physical effects may also occur in marine mammals exposed to strong 
underwater pulsed sound. It is especially unlikely that any effects of 
these types would occur during the present project given the brief 
duration of exposure for any given individual and the planned 
monitoring and mitigation measures. Perhaps most importantly, impact 
pile driving is planned only as a contingency for this project and it 
is possible that little to no impact pile driving would actually occur. 
The following subsections discuss in somewhat more detail the 
possibilities of TTS, PTS, and non-auditory physical effects.
    Temporary Threshold Shift--TTS is the mildest form of hearing 
impairment that can occur during exposure to a strong sound (Kryter, 
1985). While experiencing TTS, the hearing threshold rises, and a sound 
must be stronger in order to be heard. In terrestrial mammals, TTS can 
last from minutes or hours to days (in cases of strong TTS). For sound 
exposures at or somewhat above the TTS threshold, hearing sensitivity 
in both terrestrial and marine mammals recovers rapidly after exposure 
to the sound ends. Few data on sound levels and durations necessary to 
elicit mild TTS have been obtained for marine mammals, and none of the 
published data concern TTS elicited by exposure to multiple pulses of 
sound. Available data on TTS in marine mammals are summarized in 
Southall et al. (2007).
    Given the available data, the received level of a single pulse 
(with no frequency weighting) might need to be approximately 186 dB re 
1 [mu]Pa\2\-s (i.e., 186 dB sound exposure level [SEL] or approximately 
221-226 dB pk-pk) in order to produce brief, mild TTS. Exposure to 
several strong pulses that each have received levels near 190 dB re 1 
[mu]Pa rms (175-180 dB SEL) might result in cumulative exposure of 
approximately 186 dB SEL and thus slight TTS in a small odontocete, 
assuming the TTS threshold is (to a first approximation) a function of 
the total received pulse energy. Levels greater than or equal to 190 dB 
re 1 [mu]Pa rms are expected to be restricted to radii no more than 5 m 
(16 ft) from the pile driving. For an odontocete closer to the surface, 
the maximum radius with greater than or equal to 190 dB re 1 [mu]Pa rms 
would be smaller.
    The above TTS information for odontocetes is derived from studies 
on the bottlenose dolphin and beluga whale (Delphinapterus leucas). 
There is no published TTS information for other species of cetaceans. 
However, preliminary evidence from a harbor porpoise exposed to pulsed 
sound suggests that its TTS threshold may have been lower (Lucke et 
al., 2009). To avoid the potential for injury, NMFS has determined that 
cetaceans should not be exposed to pulsed underwater sound at received 
levels exceeding 180 dB re 1 [mu]Pa rms. As summarized above, data that 
are now available imply that TTS is unlikely to occur unless 
odontocetes are exposed to pile driving pulses stronger than 180 dB re 
1 [mu]Pa rms.
    Permanent Threshold Shift--When PTS occurs, there is physical 
damage to the sound receptors in the ear. In severe cases, there can be 
total or partial deafness, while in other cases the animal has an 
impaired ability to hear sounds in specific frequency ranges (Kryter, 
1985). There is no specific evidence that exposure to pulses of sound 
can cause PTS in any marine mammal. However, given the possibility that 
mammals close to pile driving activity might incur TTS, there has been 
further speculation about the possibility that some individuals 
occurring very close to pile driving might incur PTS. Single or 
occasional occurrences of mild TTS are not indicative of permanent 
auditory damage, but repeated or (in some cases) single exposures to a 
level well above that causing TTS onset might elicit PTS.
    Relationships between TTS and PTS thresholds have not been studied 
in marine mammals but are assumed to be similar to those in humans and 
other terrestrial mammals. PTS might occur at a received sound level at 
least several decibels above that inducing mild TTS if the animal were 
exposed to strong sound pulses with rapid rise time. Based on data from 
terrestrial mammals, a precautionary assumption is that the PTS 
threshold for impulse sounds (such as pile driving pulses as received 
close to the source) is at least 6 dB higher than the TTS threshold on 
a peak-pressure basis and probably greater than 6 dB (Southall et al., 
2007). On an SEL basis, Southall et al. (2007) estimated that received 
levels would need to exceed the TTS threshold by at least 15 dB for 
there to be risk of PTS. Thus, for cetaceans, Southall et al. (2007) 
estimate that the PTS threshold might be an M-weighted SEL (for the 
sequence of received pulses) of approximately 198 dB re 1 [mu]Pa\2\-s 
(15 dB higher than the TTS threshold for an impulse). Given the higher 
level of sound necessary to cause PTS as compared with TTS, it is 
considerably less likely that PTS could occur.
    Measured source levels from impact pile driving can be as high as 
214 dB re 1 [mu]Pa at 1 m. Although no marine mammals have been shown 
to experience TTS or PTS as a result of being exposed to pile driving 
activities, captive bottlenose dolphins and beluga whales exhibited 
changes in behavior when exposed to strong pulsed sounds (Finneran et 
al., 2000, 2002, 2005). The animals tolerated high received levels of 
sound before exhibiting aversive behaviors. Experiments on a beluga 
whale showed that exposure to a single watergun impulse at a received 
level of 207 kPa (30 psi) p-p, which is equivalent to 228 dB p-p re 1 
[mu]Pa, 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 four minutes of the exposure (Finneran et al., 
2002). 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 sound 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 sound levels for a 
prolonged period of time. Based on the best scientific information 
available, these SPLs are far below the thresholds that could cause TTS 
or the onset of PTS.
    Non-auditory Physiological Effects--Non-auditory physiological 
effects or injuries that theoretically might occur in marine mammals 
exposed to strong underwater sound include stress, neurological 
effects, bubble formation, resonance effects, and other types of organ 
or tissue damage (Cox et al., 2006; Southall et al., 2007). Studies 
examining such effects are limited. In general, little is known about 
the potential for pile driving to cause auditory impairment or other 
physical effects in marine mammals. Available data suggest that such 
effects, if they occur at all, would

[[Page 52159]]

presumably be limited to short distances from the sound source and to 
activities that extend over a prolonged period. The available data do 
not allow identification of a specific exposure level above which non-
auditory effects can be expected (Southall et al., 2007) or any 
meaningful quantitative predictions of the numbers (if any) of marine 
mammals that might be affected in those ways. Marine mammals that show 
behavioral avoidance of pile driving, including some odontocetes and 
some pinnipeds, are especially unlikely to incur auditory impairment or 
non-auditory physical effects.

Disturbance Reactions

    Disturbance includes a variety of effects, including subtle changes 
in behavior, more conspicuous changes in activities, and displacement. 
Behavioral responses to sound are highly variable and context-specific 
and reactions, if any, depend on species, state of maturity, 
experience, current activity, reproductive state, auditory sensitivity, 
time of day, and many other factors (Richardson et al., 1995; Wartzok 
et al., 2003; Southall et al., 2007).
    Habituation can occur when an animal's response to a stimulus wanes 
with repeated exposure, usually in the absence of unpleasant associated 
events (Wartzok et al., 2003). Animals are most likely to habituate to 
sounds that are predictable and unvarying. The opposite process is 
sensitization, when an unpleasant experience leads to subsequent 
responses, often in the form of avoidance, at a lower level of 
exposure. Behavioral state may affect the type of response as well. For 
example, animals that are resting may show greater behavioral change in 
response to disturbing sound levels than animals that are highly 
motivated to remain in an area for feeding (Richardson et al., 1995; 
NRC, 2003; Wartzok et al., 2003).
    Controlled experiments with captive marine mammals showed 
pronounced behavioral reactions, including avoidance of loud sound 
sources (Ridgway et al., 1997; Finneran et al., 2003). Observed 
responses of wild marine mammals to loud pulsed sound sources 
(typically seismic guns or acoustic harassment devices, but also 
including pile driving) have been varied but often consist of avoidance 
behavior or other behavioral changes suggesting discomfort (Morton and 
Symonds, 2002; Thorson and Reyff, 2006; see also Gordon et al., 2004; 
Wartzok et al., 2003; Nowacek et al., 2007). Responses to non-pulsed 
sources, such as vibratory pile installation, have not been documented 
as well as responses to pulsed sounds.
    With both types of pile driving, it is likely that the onset of 
pile driving could result in temporary, short term changes in an 
animal's typical behavior and/or avoidance of the affected area. These 
behavioral changes may include (Richardson et al., 1995): 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 sound sources are located; and/or flight responses (e.g., 
pinnipeds flushing into water from haul-outs or rookeries). Since pile 
driving would likely only occur for a few hours a day, over a short 
period of time, it is unlikely to result in permanent displacement. Any 
potential impacts from pile driving activities could be experienced by 
individual marine mammals, but would not be likely to cause population 
level impacts, or affect the long-term fitness of the species.
    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, or reproduction. Significant 
behavioral modifications that could potentially lead to effects on 
growth, survival, or reproduction include:
     Drastic changes in diving/surfacing patterns (such as 
those thought to be causing beaked whale stranding due to exposure to 
military mid-frequency tactical sonar);
     Habitat abandonment due to loss of desirable acoustic 
environment; and
     Cessation of feeding or social interaction.
    The onset of behavioral disturbance from anthropogenic sound 
depends on both external factors (characteristics of sound sources and 
their paths) and the specific characteristics of the receiving animals 
(hearing, motivation, experience, demography) and is difficult to 
predict (Southall et al., 2007).

Auditory Masking

    Natural and artificial sounds can disrupt behavior by masking, or 
interfering with, a marine mammal's ability to hear other sounds. 
Masking occurs when the receipt of a sound is interfered with by 
another coincident sound at similar frequencies and at similar or 
higher levels. Chronic exposure to excessive, though not high-
intensity, sound could cause masking at particular frequencies for 
marine mammals that utilize sound for vital biological functions. 
Masking can interfere with detection of acoustic signals such as 
communication calls, echolocation sounds, and environmental sounds 
important to marine mammals. Therefore, under certain circumstances, 
marine mammals whose acoustical sensors or environment are being 
severely masked could also be impaired from maximizing their 
performance fitness in survival and reproduction. If the coincident 
(masking) sound were man-made, it could be potentially harassing if it 
disrupted hearing-related behavior. It is important to distinguish TTS 
and PTS, which persist after the sound exposure, from masking, which 
occurs during the sound exposure. Because masking (without resulting in 
TS) is not associated with abnormal physiological function, it is not 
considered a physiological effect, but rather a potential behavioral 
effect.
    The frequency range of the potentially masking sound is important 
in determining any potential behavioral impacts. Because sound 
generated from in-water pile driving is mostly concentrated at low 
frequency ranges, it may have less effect on high frequency 
echolocation sounds made by porpoises. However, lower frequency man-
made sounds are more likely to affect detection of communication calls 
and other potentially important natural sounds such as surf and prey 
sound. It may also affect communication signals when they occur near 
the sound band 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 has the potential to impact species at population, 
community, or even ecosystem levels, as well as at individual levels. 
Masking affects both senders and receivers of the signals and can 
potentially have long-term chronic effects on marine mammal species and 
populations. Recent research suggests that low frequency ambient sound 
levels have increased by as much as 20 dB (more than three times in 
terms of SPL) in the world's ocean from pre-industrial periods, and 
that most of these increases are from distant shipping (Hildebrand, 
2009). All anthropogenic sound sources, such as those from vessel 
traffic, pile driving, and dredging activities, contribute to the 
elevated ambient sound levels, thus intensifying masking. However, much 
of the sound from the proposed activities is confined in an

[[Page 52160]]

area of inland waters (the Mayport turning basin and mouth of the St. 
Johns River) that is bounded by landmass; therefore, the sound 
generated is not expected to contribute significantly to increased 
ocean ambient sound.
    The most intense underwater sounds in the proposed action are those 
produced by impact pile driving. Given that the energy distribution of 
pile driving covers a broad frequency spectrum, sound from these 
sources would likely be within the audible range of marine mammals 
present in the project area. Impact pile driving activity is relatively 
short-term, with rapid pulses occurring for the duration of the driving 
event. The probability for impact pile driving resulting from this 
proposed action masking acoustic signals important to the behavior and 
survival of marine mammal species is likely to be discountable. 
Vibratory pile driving is also relatively short-term, with rapid 
oscillations occurring for the duration of the driving event, which is 
likely to be short for this project. It is possible that vibratory pile 
driving resulting from this proposed action may mask acoustic signals 
important to the behavior and survival of marine mammal species, but 
the short-term duration and limited affected area would result in 
insignificant impacts from masking. Any masking event that could 
possibly rise to Level B harassment under the MMPA would occur 
concurrently within the zones of behavioral harassment already 
estimated for vibratory and impact pile driving, and which have already 
been taken into account in the exposure analysis.

Anticipated Effects on Habitat

    The proposed activities at NSM would not result in permanent 
impacts to habitats used directly by marine mammals, but may have 
potential short-term impacts to food sources such as forage fish and 
may affect acoustic habitat (see masking discussion above). There are 
no known foraging hotspots or other ocean bottom structure of 
significant biological importance to marine mammals present in the 
marine waters in the vicinity of the project area. Therefore, the main 
impact issue associated with the proposed activity would be temporarily 
elevated sound levels and the associated direct effects on marine 
mammals, as discussed previously in this document. The most likely 
impact to marine mammal habitat occurs from pile driving effects on 
likely marine mammal prey (i.e., fish) near NSM and minor impacts to 
the immediate substrate during installation and removal of piles during 
the wharf construction project.

Pile Driving Effects on Potential Prey (Fish)

    Construction activities may produce both pulsed (i.e., impact pile 
driving) and continuous (i.e., vibratory pile driving) sounds. Fish 
react to sounds which are especially strong and/or intermittent low-
frequency sounds. Short duration, sharp sounds can cause overt or 
subtle changes in fish behavior and local distribution. Hastings and 
Popper (2005, 2009) and Hastin identified several studies that suggest 
fish may relocate to avoid certain areas of sound energy. Additional 
studies have documented effects of pile driving (or other types of 
sounds) on fish, although several are based on studies in support of 
large, multiyear bridge construction projects (e.g., Scholik and Yan, 
2001, 2002; Popper and Hastings, 2009). Sound pulses at received levels 
of 160 dB re 1 [mu]Pa may cause subtle changes in fish behavior. SPLs 
of 180 dB may cause noticeable changes in behavior (Pearson et al., 
1992; Skalski et al., 1992). SPLs of sufficient strength have been 
known to cause injury to fish and fish mortality. The most likely 
impact to fish from pile driving activities at the project area would 
be temporary behavioral avoidance of the area. The duration of fish 
avoidance of this area after pile driving stops is unknown, but a rapid 
return to normal recruitment, distribution and behavior is anticipated. 
In general, impacts to marine mammal prey species are expected to be 
minor and temporary due to the short timeframe for the project.

Pile Driving Effects on Potential Foraging Habitat

    The area likely impacted by the project is relatively small 
compared to the available habitat in nearshore and estuarine waters in 
the region. Avoidance by potential prey (i.e., fish) of the immediate 
area due to the temporary loss of this foraging habitat is also 
possible. The duration of fish avoidance of this area after pile 
driving stops is unknown, but a rapid return to normal recruitment, 
distribution and behavior is anticipated. Any behavioral avoidance by 
fish of the disturbed area would still leave significantly large areas 
of fish and marine mammal foraging habitat in the nearby vicinity.
    Given the short daily duration of sound associated with individual 
pile driving events and the relatively small areas being affected, pile 
driving activities associated with the proposed action are not likely 
to have a permanent, adverse effect on any fish habitat, or populations 
of fish species. Therefore, pile driving is not likely to have a 
permanent, adverse effect on marine mammal foraging habitat at the 
project area. The Mayport turning basin itself is a man-made basin with 
significant levels of industrial activity and regular dredging, and is 
unlikely to harbor significant amounts of forage fish.

Proposed Mitigation

    In order to issue an incidental take authorization (ITA) under 
section 101(a)(5)(D) of the MMPA, we must set forth the permissible 
methods of taking pursuant to such activity, and other means of 
effecting the least practicable 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 (where relevant).
    Measurements from proxy pile driving events were coupled with 
practical spreading loss to estimate zones of influence (ZOIs; see 
``Estimated Take by Incidental Harassment''); these values were used to 
develop mitigation measures for pile driving activities at NSM. The 
ZOIs effectively represent the mitigation zone that would be 
established around each pile to prevent Level A harassment to marine 
mammals, while providing estimates of the areas within which Level B 
harassment might occur. In addition to the specific measures described 
later in this section, the Navy would conduct briefings between 
construction supervisors and crews, marine mammal monitoring team, and 
Navy staff prior to the start of all pile driving activity, and when 
new personnel join the work, in order to explain responsibilities, 
communication procedures, marine mammal monitoring protocol, and 
operational procedures.

Monitoring and Shutdown for Pile Driving

    The following measures would apply to the Navy's mitigation through 
shutdown and disturbance zones:
    Shutdown Zone--For all pile driving and removal activities, the 
Navy will establish a shutdown zone intended to contain the area in 
which SPLs equal or exceed the 180 dB rms acoustic injury criteria. The 
purpose of a shutdown zone is to define an area within which shutdown 
of activity would occur upon sighting of a marine mammal (or in 
anticipation of an animal entering the defined area), thus preventing 
injury, serious injury, or death of marine mammals. Radial distances 
for

[[Page 52161]]

shutdown zones are shown in Table 1. However, for this project, a 
minimum shutdown zone of 15 m will be established during all pile 
driving activities, regardless of the estimated zone. Vibratory pile 
driving activities are not predicted to produce sound exceeding the 
Level A standard, but these precautionary measures are intended to 
prevent the already unlikely possibility of physical interaction with 
construction equipment and to further reduce any possibility of 
acoustic injury. For impact driving of steel piles, the radial distance 
of the shutdown would be established at 40 m (Table 1).
    Disturbance Zone--Disturbance zones are the areas in which SPLs 
equal or exceed 160 and 120 dB rms (for pulsed and non-pulsed sound, 
respectively). Disturbance zones provide utility for monitoring 
conducted for mitigation purposes (i.e., shutdown zone monitoring) by 
establishing monitoring protocols for areas adjacent to the shutdown 
zones. Monitoring of disturbance zones enables observers to be aware of 
and communicate the presence of marine mammals in the project area but 
outside the shutdown zone and thus prepare for potential shutdowns of 
activity. However, the primary purpose of disturbance zone monitoring 
is for documenting incidents of Level B harassment; disturbance zone 
monitoring is discussed in greater detail later (see ``Proposed 
Monitoring and Reporting''). Nominal radial distances for disturbance 
zones are shown in Table 1. Given the size of the disturbance zone for 
vibratory pile driving, it is impossible to guarantee that all animals 
would be observed or to make comprehensive observations of fine-scale 
behavioral reactions to sound, and only a portion of the zone (e.g., 
what may be reasonably observed by visual observers stationed within 
the turning basin) would be observed.
    In order to document observed incidences of harassment, monitors 
record all marine mammal observations, regardless of location. The 
observer's location, as well as the location of the pile being driven, 
is known from a GPS. The location of the animal is estimated as a 
distance from the observer, which is then compared to the location from 
the pile. If acoustic monitoring is being conducted for that pile, a 
received SPL may be estimated, or the received level may be estimated 
on the basis of past or subsequent acoustic monitoring. It may then be 
determined whether the animal was exposed to sound levels constituting 
incidental harassment in post-processing of observational and acoustic 
data, and a precise accounting of observed incidences of harassment 
created. Therefore, although the predicted distances to behavioral 
harassment thresholds are useful for estimating incidental harassment 
for purposes of authorizing levels of incidental take, actual take may 
be determined in part through the use of empirical data. That 
information may then be used to extrapolate observed takes to reach an 
approximate understanding of actual total takes.
    Monitoring Protocols--Monitoring would be conducted before, during, 
and after pile driving activities. In addition, observers shall record 
all incidences of marine mammal occurrence, regardless of distance from 
activity, and shall document any behavioral reactions in concert with 
distance from piles being driven. Observations made outside the 
shutdown zone will not result in shutdown; that pile segment would be 
completed without cessation, unless the animal approaches or enters the 
shutdown zone, at which point all pile driving activities would be 
halted. Please see the Monitoring Plan (available at https://www.nmfs.noaa.gov/pr/permits/incidental.htm), developed by the Navy in 
agreement with NMFS, for full details of the monitoring protocols. 
Monitoring will take place from 15 minutes prior to initiation through 
15 minutes post-completion of pile driving activities. Pile driving 
activities include the time to remove a single pile or series of piles, 
as long as the time elapsed between uses of the pile driving equipment 
is no more than 30 minutes.
    The following additional measures apply to visual monitoring:
    (1) Monitoring will be conducted by qualified observers, who will 
be placed at the best vantage point(s) practicable to monitor for 
marine mammals and implement shutdown/delay procedures when applicable 
by calling for the shutdown to the hammer operator. Qualified observers 
are trained biologists, with the following minimum qualifications:
     Visual acuity in both eyes (correction is permissible) 
sufficient for discernment of moving targets at the water's surface 
with ability to estimate target size and distance; use of binoculars 
may be necessary to correctly identify the target;
     Advanced education in biological science, wildlife 
management, mammalogy, or related fields (bachelor's degree or higher 
is required);
     Experience and ability to conduct field observations and 
collect data according to assigned protocols (this may include academic 
experience);
     Experience or training in the field identification of 
marine mammals, including the identification of behaviors;
     Sufficient training, orientation, or experience with the 
construction operation to provide for personal safety during 
observations;
     Writing skills sufficient to prepare a report of 
observations including but not limited to the number and species of 
marine mammals observed; dates and times when in-water construction 
activities were conducted; dates and times when in-water construction 
activities were suspended to avoid potential incidental injury from 
construction sound of marine mammals observed within a defined shutdown 
zone; and marine mammal behavior; and
     Ability to communicate orally, by radio or in person, with 
project personnel to provide real-time information on marine mammals 
observed in the area as necessary.
    (2) Prior to the start of pile driving activity, the shutdown zone 
will be monitored for 15 minutes to ensure that it is clear of marine 
mammals. Pile driving will only commence once observers have declared 
the shutdown zone clear of marine mammals; animals will be allowed to 
remain in the shutdown zone (i.e., must leave of their own volition) 
and their behavior will be monitored and documented. The shutdown zone 
may only be declared clear, and pile driving started, when the entire 
shutdown zone is visible (i.e., when not obscured by dark, rain, fog, 
etc.). In addition, if such conditions should arise during impact pile 
driving that is already underway, the activity would be halted.
    (3) If a marine mammal approaches or enters the shutdown zone 
during the course of pile driving operations, activity will be halted 
and delayed until either the animal has voluntarily left and been 
visually confirmed beyond the shutdown zone or 15 minutes have passed 
without re-detection of the animal. Monitoring will be conducted 
throughout the time required to drive a pile.

Soft Start

    The use of a soft-start procedure is believed to provide additional 
protection to marine mammals by warning or providing a chance to leave 
the area prior to the hammer operating at full capacity, and typically 
involves a requirement to initiate sound from vibratory hammers for 
fifteen seconds at reduced energy followed by a 30-second waiting 
period. This procedure is repeated two additional times. However, 
implementation of soft start for vibratory pile driving during previous

[[Page 52162]]

pile driving work conducted by the Navy at another location has led to 
equipment failure and serious human safety concerns. Therefore, 
vibratory soft start is not proposed as a mitigation measure for this 
project, as we have determined it not to be practicable. We have 
further determined this measure unnecessary to providing the means of 
effecting the least practicable impact on marine mammals and their 
habitat. Prior to issuing any further IHAs to the Navy for pile driving 
activities in 2014 and beyond, we plan to facilitate consultation 
between the Navy and other practitioners (e.g., Washington State 
Department of Transportation and/or the California Department of 
Transportation) in order to determine whether the potentially 
significant human safety issue is inherent to implementation of the 
measure or is due to operator error. For impact driving, soft start 
will be required, and contractors will provide an initial set of three 
strikes from the impact hammer at 40 percent energy, followed by a 30-
second waiting period, then two subsequent three-strike sets.
    We have carefully evaluated the applicant's proposed mitigation 
measures and considered a range of other measures in the context of 
ensuring that we prescribe the means of effecting the least practicable 
impact on the affected marine mammal species and stocks and their 
habitat. Our evaluation of potential measures included consideration of 
the following factors in relation to one another: (1) The manner in 
which, and the degree to which, the successful implementation of the 
measure is expected to minimize adverse impacts to marine mammals; (2) 
the proven or likely efficacy of the specific measure to minimize 
adverse impacts as planned; and (3) the practicability of the measure 
for applicant implementation.
    Based on our evaluation of the applicant's proposed measures, as 
well as any other potential measures that may be relevant to the 
specified activity, we have preliminarily determined that the proposed 
mitigation measures provide the means of effecting the least 
practicable impact on marine mammal species or stocks and their 
habitat, paying particular attention to rookeries, mating grounds, and 
areas of similar significance.

Proposed Monitoring and Reporting

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

Acoustic Monitoring

    The Navy has proposed a sound source level verification study 
during the specified activities. Data would be collected in order to 
estimate airborne and underwater source levels. Monitoring would 
include two underwater positions and one airborne monitoring position. 
These exact positions would be determined in the field during 
consultation with Navy personnel, subject to constraints related to 
logistics and security requirements. Underwater sound monitoring would 
include the measurement of peak and rms sound pressure levels during 
pile driving activities at Wharf C-2. Typical ambient levels would be 
measured during lulls in the pile installation and reported in terms of 
rms sound pressure levels. Frequency spectra would be provided for pile 
driving sounds.

Visual Marine Mammal Observations

    The Navy will collect sighting data and behavioral responses to 
construction for marine mammal species observed in the region of 
activity during the period of activity. All observers will be trained 
in marine mammal identification and behaviors and are required to have 
no other construction-related tasks while conducting monitoring. The 
Navy will monitor the shutdown zone and disturbance zone before, 
during, and after pile driving, with observers located at the best 
practicable vantage points. Based on our requirements, the Navy would 
implement the following procedures for pile driving:
     MMOs would be located at the best vantage point(s) in 
order to properly see the entire shutdown zone and as much of the 
disturbance zone as possible.
     During all observation periods, observers will use 
binoculars and the naked eye to search continuously for marine mammals.
     If the shutdown zones are obscured by fog or poor lighting 
conditions, pile driving at that location will not be initiated until 
that zone is visible. Should such conditions arise while impact driving 
is underway, the activity would be halted.
     The shutdown and disturbance zones around the pile will be 
monitored for the presence of marine mammals before, during, and after 
any pile driving or removal activity.
    Individuals implementing the monitoring protocol will assess its 
effectiveness using an adaptive approach. Monitoring biologists will 
use their best professional judgment throughout implementation and seek 
improvements to these methods when deemed appropriate. Any 
modifications to protocol will be coordinated between NMFS and the 
Navy.

Data Collection

    We require that observers use approved data forms. Among other 
pieces of information, the Navy will record detailed information about 
any implementation of shutdowns, including the distance of animals to 
the pile and description of specific actions that ensued and resulting 
behavior of the animal, if any. In addition, the Navy will attempt to 
distinguish between the number of individual animals taken and the 
number of incidences of take. We require that, at a minimum, the 
following information be collected on the sighting forms:
     Date and time that monitored activity begins or ends;
     Construction activities occurring during each observation 
period;
     Weather parameters (e.g., percent cover, visibility);
     Water conditions (e.g., sea state, tide state);
     Species, numbers, and, if possible, sex and age class of 
marine mammals;
     Description of any observable marine mammal behavior 
patterns, including bearing and direction of travel, and if possible, 
the correlation to SPLs;
     Distance from pile driving activities to marine mammals 
and distance from the marine mammals to the observation point;
     Locations of all marine mammal observations; and
     Other human activity in the area.

Reporting

    A draft report would be submitted to NMFS within 90 days of the 
completion of marine mammal monitoring. The report will include marine 
mammal observations pre-activity, during-activity, and post-activity 
during pile driving days, and will also provide descriptions of any 
adverse responses to construction activities by marine mammals and a 
complete description of all mitigation shutdowns and the results

[[Page 52163]]

of those actions and a refined take estimate based on the number of 
marine mammals observed during the course of construction. A final 
report would be prepared and submitted within 30 days following 
resolution of comments on the draft report. A technical report 
summarizing the acoustic monitoring data collected would be prepared 
within 75 days of completion of monitoring.

Estimated Take by Incidental Harassment

    With respect to the activities described here, the MMPA defines 
``harassment'' as: ``any act of pursuit, torment, or annoyance which 
(i) has the potential to injure a marine mammal or marine mammal stock 
in the wild [Level A harassment]; or (ii) has the potential to disturb 
a marine mammal or marine mammal stock in the wild by causing 
disruption of behavioral patterns, including, but not limited to, 
migration, breathing, nursing, breeding, feeding, or sheltering [Level 
B harassment].'' All anticipated takes would be by Level B harassment, 
involving temporary changes in behavior. The proposed mitigation and 
monitoring measures are expected to minimize the possibility of 
injurious or lethal takes such that take by Level A harassment, serious 
injury, or mortality is considered discountable. However, it is 
unlikely that injurious or lethal takes would occur even in the absence 
of the proposed mitigation and monitoring measures.
    If a marine mammal responds to a stimulus by changing its behavior 
(e.g., through relatively minor changes in locomotion direction/speed 
or vocalization behavior), the response may or may not constitute 
taking at the individual level, and is unlikely to affect the stock or 
the species as a whole. However, if a sound source displaces marine 
mammals from an important feeding or breeding area for a prolonged 
period, impacts on animals or on the stock or species could potentially 
be significant (Lusseau and Bejder, 2007; Weilgart, 2007). Given the 
many uncertainties in predicting the quantity and types of impacts of 
sound on marine mammals, it is common practice to estimate how many 
animals are likely to be present within a particular distance of a 
given activity, or exposed to a particular level of sound. This 
practice potentially overestimates the numbers of marine mammals taken. 
In addition, it is often difficult to distinguish between the 
individuals harassed and incidences of harassment. In particular, for 
stationary activities, it is more likely that some smaller number of 
individuals may accrue a number of incidences of harassment per 
individual than for each incidence to accrue to a new individual, 
especially if those individuals display some degree of residency or 
site fidelity and the impetus to use the site (e.g., because of 
foraging opportunities) is stronger than the deterrence presented by 
the harassing activity.
    The turning basin is not important habitat for marine mammals, as 
it is a man-made, semi-enclosed basin with frequent industrial activity 
and regular maintenance dredging. The small area of ensonification 
extending out of the turning basin into nearshore waters is also not 
believed to be of any particular importance, nor is it considered an 
area frequented by marine mammals. Bottlenose dolphins may be observed 
at any time of year in estuarine and nearshore waters of the action 
area, but sightings of other species are rare. Therefore, behavioral 
disturbances that could result from anthropogenic sound associated with 
these activities are expected to affect only a relatively small number 
of individual marine mammals, although those effects could be recurring 
over the life of the project if the same individuals remain in the 
project vicinity. The Navy has requested authorization for the 
incidental taking of small numbers of bottlenose dolphins and Atlantic 
spotted dolphins in the Mayport turning basin and associated nearshore 
waters that may be ensonified by project activities.

Marine Mammal Densities

    For all species, the best scientific information available was used 
to derive density estimates and the maximum appropriate density value 
for each species was used in the marine mammal take assessment 
calculation. Density values for the Atlantic spotted dolphin were 
derived from global density estimates produced by Sea Mammal Research 
Unit, Ltd. (SMRU), as presented in DoN (2012), and the highest seasonal 
density (spring; 0.6803/km\2\) was used for take estimation. Density 
for bottlenose dolphin is derived from site-specific surveys conducted 
by the Navy. Only bottlenose dolphins have been observed in the turning 
basin; it is not currently possible to identify observed individuals to 
stock. This survey effort consists of twelve half-day observation 
periods covering mornings and afternoons during December 10-13, 2012, 
and March 4-7, 2013. During each observation period, two observers (one 
at ground level and one positioned at a fourth-floor observation point) 
monitored for the presence of marine mammals in the turning basin 
(0.712 km\2\) and tracked their movements and behavior while inside the 
basin, with observations recorded for five-minute intervals every half-
hour. Morning sessions typically ran from 7:00-11:30 and afternoon 
sessions from 1:00 to 5:30. Most observations were of individuals or 
pairs (mode of 1) although a maximum group size of six was observed. It 
was assumed that the average observed group size (1.8) could occur in 
the action area each day, and was thus used to calculate a density of 
2.53/km\2\. For comparison, the maximum density value available from 
the NMSDD for bottlenose dolphins in inshore areas is significantly 
lower (winter, 0.217/km\2\, SMRU estimate) and would likely 
underestimate the occurrence of bottlenose dolphins in the turning 
basin.

Description of Take Calculation

    The take calculations presented here rely on the best data 
currently available for marine mammal populations in the vicinity of 
Mayport. The following assumptions are made when estimating potential 
incidences of take:
     All marine mammal individuals potentially available are 
assumed to be present within the relevant area, and thus incidentally 
taken;
     An individual can only be taken once during a 24-h period; 
and,
     There will be 50 total days of vibratory driving (45 days 
for steel piles and 5 days for plastic piles) and 20 days of impact 
pile driving.
     Exposures to sound levels above the relevant thresholds 
equate to take, as defined by the MMPA.
    The calculation for marine mammal takes is estimated by:

Exposure estimate = (n * ZOI) * days of total activity

Where:

n = density estimate used for each species/season
ZOI = sound threshold ZOI impact area; the area encompassed by all 
locations where the SPLs equal or exceed the threshold being 
evaluated

    n * ZOI produces an estimate of the abundance of animals that could 
be present in the area for exposure, and is rounded to the nearest 
whole number before multiplying by days of total activity.
    The ZOI impact area is the estimated range of impact to the sound 
criteria. The distances specified in Table 1 were used to calculate 
ZOIs around each pile. The ZOI impact area calculations took into 
consideration the possible affected area with attenuation due to the 
constraints of the basin. Because the basin restricts sound from 
propagating outward, with the exception of the east-

[[Page 52164]]

facing entrance channel, the radial distances to thresholds are not 
generally reached.
    While pile driving can occur any day, and the analysis is conducted 
on a per day basis, only a fraction of that time (typically a matter of 
hours on any given day) is actually spent pile driving. The exposure 
assessment methodology is an estimate of the numbers of individuals 
exposed to the effects of pile driving activities exceeding NMFS-
established thresholds. Of note in these exposure estimates, mitigation 
methods (i.e., visual monitoring and the use of shutdown zones; soft 
start for impact pile driving) were not quantified within the 
assessment and successful implementation of mitigation is not reflected 
in exposure estimates. In addition, equating exposure with response 
(i.e., a behavioral response meeting the definition of take under the 
MMPA) is simplistic and conservative assumption. For these reasons, 
results from this acoustic exposure assessment likely overestimate take 
estimates to some degree.

     Table 3--Number of Potential Incidental Takes of Marine Mammals Within Various Acoustic Threshold Zones
----------------------------------------------------------------------------------------------------------------
                                                                   Estimated incidences of take
                                                                                \1\
                Species                         Activity         --------------------------------      Total
                                                                      Level A         Level B
----------------------------------------------------------------------------------------------------------------
Bottlenose dolphin \2\................  Impact driving (steel                  0              40             365
                                         piles).
                                        Vibratory driving (steel               0             315
                                         piles).
                                        Vibratory driving                      0              10
                                         (plastic piles).
Atlantic spotted dolphin..............  Impact driving (steel                  0               0              95
                                         piles).
                                        Vibratory driving (steel               0              90
                                         piles).
                                        Vibratory driving                      0               5
                                         (plastic piles).
----------------------------------------------------------------------------------------------------------------
\1\ Acoustic injury threshold is 180 dB for cetaceans; behavioral harassment threshold applicable to impact pile
  driving is 160 dB and to vibratory driving is 120 dB.
\2\ It is impossible to estimate from available information which stock these takes may accrue to.

    Only bottlenose dolphins are likely to occur inside the turning 
basin; therefore, the estimates for spotted dolphin are likely 
overestimates because the ZOI areas include the turning basin. 
Bottlenose dolphins are likely to be exposed to sound levels that could 
cause behavioral harassment if they enter the turning basin while pile 
driving activity is occurring. Outside the turning basin, potential 
takes could occur if individuals of these species move through the 
ensonified area when pile driving is occurring. It is not possible to 
determine, from available information, how many of the estimated 
incidences of take for bottlenose dolphins may accrue to the different 
stocks that may occur in the action area. Similarly, animals observed 
in the ensonified areas will not be able to be identified to stock on 
the basis of visual observation.

Negligible Impact and Small Numbers Analyses and Preliminary 
Determinations

    NMFS has defined ``negligible impact'' in 50 CFR 216.103 as `` . . 
. an impact resulting from the specified activity that cannot be 
reasonably expected to, and is not reasonably likely to, adversely 
affect the species or stock through effects on annual rates of 
recruitment or survival.'' In making a negligible impact determination, 
we considers a variety of factors, including but not limited to: (1) 
The number of anticipated mortalities; (2) the number and nature of 
anticipated injuries; (3) the number, nature, intensity, and duration 
of Level B harassment; and (4) the context in which the take occurs.

Small Numbers Analysis

    The number of incidences of take authorized for Atlantic spotted 
dolphins is small relative to the relevant stock--less than one 
percent. As described previously, of the 365 incidences of behavioral 
harassment predicted to occur for bottlenose dolphin, we have no 
information allowing us to parse those predicted incidences amongst the 
three stocks of bottlenose dolphin that may occur in the ensonified 
area. Therefore, we assessed the total number of predicted incidences 
of take against the best abundance estimate for each stock, as though 
the total would occur for the stock in question. For two of the 
bottlenose dolphin stocks, the total predicted number of incidences of 
take authorized would be considered small--less than three percent for 
the southern migratory stock and less than twelve percent for the 
northern Florida coastal stock--even if each estimated taking occurred 
to a new individual. This is an extremely unlikely scenario as, for 
bottlenose dolphins in estuarine and nearshore waters, there is likely 
to be some overlap in individuals present day-to-day.
    The total number of authorized takes proposed for bottlenose 
dolphins, if assumed to accrue solely to new individuals of the JES 
stock, is higher relative to the total stock abundance, which is 
currently considered unknown. However, these numbers represent the 
estimated incidences of take, not the number of individuals taken. That 
is, it is highly likely that a relatively small subset of JES 
bottlenose dolphins would be harassed by project activities. JES 
bottlenose dolphins range from Cumberland Sound at the Georgia-Florida 
border south to approximately Palm Coast, Florida, an area spanning 
over 120 linear km of coastline and including habitat consisting of 
complex inshore and estuarine waterways. JES dolphins, divided by 
Caldwell (2001) into Northern and Southern groups, show strong site 
fidelity and, although members of both groups have been observed 
outside their preferred areas, it is likely that the majority of JES 
dolphins would not occur within waters ensonified by project 
activities. Further, although the largest area of ensonification is 
predicted to extend up to 7.5 km offshore from NSM, estuarine dolphins 
are generally considered as restricted to inshore waters and only 1-2 
km offshore. In summary, JES dolphins are (1) Known to form two groups 
and exhibit strong site fidelity (i.e., individuals do not generally 
range throughout the recognized overall JES stock range); (2) would not 
occur at all in a significant portion of the larger ZOI extending 
offshore from NSM; and (3) the specified activity will be stationary 
within an enclosed basin not recognized as an area of any special 
significance that would serve to attract or aggregate dolphins. We 
therefore believe that the estimated numbers of takes, were they to 
occur, likely represent repeated exposures of a much smaller number of 
bottlenose dolphins and that these

[[Page 52165]]

estimated incidences of take represent small numbers of bottlenose 
dolphins.

Negligible Impact Analysis

    Pile driving activities associated with the Navy's wharf project, 
as outlined previously, have the potential to disturb or displace 
marine mammals. Specifically, the specified activities may result in 
take, in the form of Level B harassment (behavioral disturbance) only, 
from underwater sounds generated from pile driving. Potential takes 
could occur if individuals of these species are present in the 
ensonified zone when pile driving is happening.
    No injury, serious injury, or mortality is anticipated given the 
likely methods of installation and measures designed to minimize the 
possibility of injury to marine mammals. The potential for these 
outcomes is minimized through the construction method and the 
implementation of the planned mitigation measures. Specifically, 
vibratory hammers will be the primary method of installation, and this 
activity does not have significant potential to cause injury to marine 
mammals due to the relatively low source levels produced (less than 180 
dB) and the lack of potentially injurious source characteristics. 
Impact pile driving produces short, sharp pulses with higher peak 
levels and much sharper rise time to reach those peaks. If impact 
driving is necessary, implementation of soft start and shutdown zones 
significantly reduces any possibility of injury. Given sufficient 
``notice'' through use of soft start (for impact driving), marine 
mammals are expected to move away from a sound source that is annoying 
prior to its becoming potentially injurious. Environmental conditions 
in the confined and protected Mayport turning basin mean that marine 
mammal detection ability by trained observers is high, enabling a high 
rate of success in implementation of shutdowns to avoid injury, serious 
injury, or mortality.
    Effects on individuals that are taken by Level B harassment, on the 
basis of reports in the literature as well as monitoring from other 
similar activities, will likely be limited to reactions such as 
increased swimming speeds, increased surfacing time, or decreased 
foraging (if such activity were occurring). Most likely, individuals 
will simply move away from the sound source and be temporarily 
displaced from the areas of pile driving, although even this reaction 
has been observed primarily only in association with impact pile 
driving. The pile driving activities analyzed here are similar to 
numerous other construction activities conducted in San Francisco Bay 
and in the Puget Sound region, which have taken place with no reported 
injuries or mortality to marine mammals, and no known long-term adverse 
consequences from behavioral harassment. Repeated exposures of 
individuals to levels of sound that may cause Level B harassment are 
unlikely to result in hearing impairment or to significantly disrupt 
foraging behavior. Thus, even repeated Level B harassment of some small 
subset of the overall stock is unlikely to result in any significant 
realized decrease in viability for bottlenose dolphins, and thus would 
not result in any adverse impact to the stock as a whole. Level B 
harassment will be reduced to the level of least practicable impact 
through use of mitigation measures described herein and, if sound 
produced by project activities is sufficiently disturbing, animals are 
likely to simply avoid the turning basin while the activity is 
occurring.
    In summary, this negligible impact analysis is founded on the 
following factors: (1) The possibility of injury, serious injury, or 
mortality may reasonably be considered discountable; (2) the 
anticipated incidences of Level B harassment consist of, at worst, 
temporary modifications in behavior; (3) the absence of any significant 
habitat within the project area, including known areas or features of 
special significance for foraging or reproduction; (4) the presumed 
efficacy of the proposed mitigation measures in reducing the effects of 
the specified activity to the level of least practicable impact. In 
addition, none of these stocks are listed under the ESA, although 
coastal bottlenose dolphins are considered depleted under the MMPA. In 
combination, we believe that these factors, as well as the available 
body of evidence from other similar activities, demonstrate that the 
potential effects of the specified activity will have only short-term 
effects on individuals. The specified activity is not expected to 
impact rates of recruitment or survival and will therefore not result 
in population-level impacts.

Preliminary Determinations

    The number of marine mammals actually incidentally harassed by the 
project will depend on the distribution and abundance of marine mammals 
in the vicinity of the survey activity. However, we find that the 
number of potential takings authorized (by level B harassment only), 
which we consider to be a conservative, maximum estimate, is small 
relative to the relevant regional stock or population numbers, and that 
the effect of the activity will be mitigated to the level of least 
practicable impact through implementation of the mitigation and 
monitoring measures described previously. Based on the analysis 
contained herein of the likely effects of the specified activity on 
marine mammals and their habitat, we preliminarily find that the total 
taking from the activity will have a negligible impact on the affected 
species or stocks.

Impact on Availability of Affected Species for Taking for Subsistence 
Uses

    There are no relevant subsistence uses of marine mammals implicated 
by this action. Therefore, we have determined that the total taking of 
affected species or stocks would not have an unmitigable adverse impact 
on the availability of such species or stocks for taking for 
subsistence purposes.

Endangered Species Act (ESA)

    There are no ESA-listed marine mammals expected to occur in the 
action area. Therefore, the Navy has not requested authorization of the 
incidental take of ESA-listed species and no such authorization is 
proposed for issuance; therefore, no consultation under the ESA is 
required.

National Environmental Policy Act (NEPA)

    The Navy has prepared a Draft Environmental Assessment (EA; Wharf 
C-2 Recapitalization at Naval Station Mayport, FL) in accordance with 
NEPA and the regulations published by the Council on Environmental 
Quality. We have posted it on the NMFS Web site (see SUPPLEMENTARY 
INFORMATION) concurrently with the publication of this proposed IHA. 
NMFS will independently evaluate the EA and determine whether or not to 
adopt it. We may prepare a separate NEPA analysis and incorporate 
relevant portions of the Navy's EA by reference. Information in the 
Navy's application, EA, and this notice collectively provide the 
environmental information related to proposed issuance of the IHA for 
public review and comment. We will review all comments submitted in 
response to this notice as we complete the NEPA process, including a 
decision of whether to sign a Finding of No Significant Impact (FONSI), 
prior to a final decision on the IHA request.

Proposed Authorization

    As a result of these preliminary determinations, we propose to 
authorize the take of marine mammals incidental to the Navy's wharf 
project, provided the previously mentioned mitigation, monitoring, and 
reporting requirements are incorporated.


[[Page 52166]]


    Dated: August 19, 2013.
Helen M. Golde,
Deputy Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. 2013-20507 Filed 8-21-13; 8:45 am]
BILLING CODE 3510-22-P