[Federal Register Volume 76, Number 245 (Wednesday, December 21, 2011)]
[Notices]
[Pages 79410-79439]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-32549]
[[Page 79409]]
Vol. 76
Wednesday,
No. 245
December 21, 2011
Part V
Department of Commerce
-----------------------------------------------------------------------
National Oceanic and Atmospheric Administration
-----------------------------------------------------------------------
Takes of Marine Mammals Incidental to Specified Activities; Taking
Marine Mammals; Notice
Federal Register / Vol. 76 , No. 245 / Wednesday, December 21, 2011 /
Notices
[[Page 79410]]
-----------------------------------------------------------------------
DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
RIN 0648-XA830
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to a Wharf Construction Project
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice; proposed incidental harassment authorization; request
for comments.
-----------------------------------------------------------------------
SUMMARY: NMFS has received an application from the U.S. Navy (Navy) for
an Incidental Harassment Authorization (IHA) to take marine mammals, by
harassment, incidental to construction activities as part of a wharf
construction project. Pursuant to the Marine Mammal Protection Act
(MMPA), NMFS is requesting comments on its proposal to issue an IHA to
the Navy to take, by Level B Harassment only, six species of marine
mammals during the specified activity.
DATES: Comments and information must be received no later than January
20, 2012.
ADDRESSES: Comments on the application should be addressed to Michael
Payne, Chief, Permits and Conservation Division, Office of Protected
Resources, National Marine Fisheries Service, 1315 East-West Highway,
Silver Spring, MD 20910-3225. The mailbox address for providing email
comments is [email protected]. NMFS is not responsible for email
comments sent to addresses other than the one provided here. Comments
sent via email, including all attachments, must not exceed a 10-
megabyte file size.
Instructions: All comments received are a part of the public record
and will generally be posted to http://www.nmfs.noaa.gov/pr/permits/incidental.htm without change. 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.
An electronic copy of the application containing a list of the
references used in this document may be obtained by writing to the
address specified above, telephoning the contact listed below (see FOR
FURTHER INFORMATION CONTACT), or visiting the Internet at: http://www.nmfs.noaa.gov/pr/permits/incidental.htm. Documents cited in this
notice may also be viewed, by appointment, during regular business
hours, at the aforementioned address.
FOR FURTHER INFORMATION CONTACT: Ben Laws, Office of Protected
Resources, NMFS, (301) 427-8401.
SUPPLEMENTARY INFORMATION:
Background
Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.)
direct the Secretary of Commerce to allow, upon request, the
incidental, but not intentional, taking of small numbers of marine
mammals by U.S. citizens who engage in a specified activity (other than
commercial fishing) within a specified geographical region if certain
findings are made and either regulations are issued or, if the taking
is limited to harassment, a notice of a proposed authorization is
provided to the public for review.
Authorization for incidental takings shall be granted if NMFS finds
that the taking will have a negligible impact on the species or
stock(s), will not have an unmitigable adverse impact on the
availability of the species or stock(s) for subsistence uses (where
relevant), and if the permissible methods of taking and requirements
pertaining to the mitigation, monitoring and reporting of such takings
are set forth. NMFS has defined ``negligible impact'' in 50 CFR 216.103
as ``* * * an impact resulting from the specified activity that cannot
be reasonably expected to, and is not reasonably likely to, adversely
affect the species or stock through effects on annual rates of
recruitment or survival.''
Section 101(a)(5)(D) of the MMPA established an expedited process
by which citizens of the U.S. can apply for an authorization to
incidentally take small numbers of marine mammals by harassment.
Section 101(a)(5)(D) establishes a 45-day time limit for NMFS review of
an application followed by a 30-day public notice and comment period on
any proposed authorizations for the incidental harassment of marine
mammals. Within 45 days of the close of the comment period, NMFS must
either issue or deny the authorization. Except with respect to certain
activities not pertinent here, the MMPA defines ``harassment'' as:
Any act of pursuit, torment, or annoyance which (i) has the
potential to injure a marine mammal or marine mammal stock in the
wild [Level A harassment]; or (ii) has the potential to disturb a
marine mammal or marine mammal stock in the wild by causing
disruption of behavioral patterns, including, but not limited to,
migration, breathing, nursing, breeding, feeding, or sheltering
[Level B harassment].
Summary of Request
NMFS received an application on May 25, 2011 from the Navy for the
taking of marine mammals incidental to pile driving and removal in
association with a wharf construction project in the Hood Canal at
Naval Base Kitsap in Bangor, WA (NBKB). The Navy submitted a revised
version of the application on August 11, 2011, and, responsive to
discussions with NMFS as well as new information about species in the
area, submitted a final version deemed adequate and complete by NMFS on
November 3, 2011. The wharf construction project is proposed to occur
over multiple years; however, this IHA would cover only the initial
year of the project, from July 16, 2012, through July 15, 2013. Pile
driving and removal activities would occur only within an approved in-
water work window from July 16-February 15. Six species of marine
mammals are known from the waters surrounding NBKB: Steller sea lions
(Eumetopias jubatus), California sea lions (Zalophus californianus),
harbor seals (Phoca vitulina), killer whales (Orcinus orca), Dall's
porpoises (Phocoenoides dalli), and harbor porpoises (Phocoena
phocoena). These species may occur year-round in the Hood Canal, with
the exception of the Steller sea lion, which is present only from fall
to late spring (October to mid-April), and the California sea lion,
which is only present from late summer to late spring (August to early
June). Additionally, while the Southern Resident killer whale (listed
as endangered under the Endangered Species Act [ESA]) is resident to
the inland waters of Washington and British Columbia, it has not been
observed in the Hood Canal in over 15 years and was therefore excluded
from further analysis.
NBKB provides berthing and support services for OHIO Class
ballistic missile submarines (SSBN), also known as TRIDENT submarines.
The Navy proposes to begin construction of the Explosive Handling Wharf
2 (EHW-2) facility at NBKB in order to support future program
requirements for TRIDENT submarines berthed at NBKB. The Navy states
that construction of EHW-2 is necessary because the existing EHW alone
will not be able to support future TRIDENT program requirements. Under
the proposed action--which includes only the portion of the project
that would be completed under this proposed 1-year IHA--a maximum of
195 pile driving days would occur. All piles would be driven with a
vibratory hammer for their initial embedment depths, while select piles
[[Page 79411]]
would be impact driven for their final 10-15 ft (3-4.6 m) for proofing,
as necessary. Proofing involves striking a driven pile with an impact
hammer to verify that it provides the required load-bearing capacity,
as indicated by the number of hammer blows per foot of pile
advancement. Sound attenuation measures (i.e., bubble curtain) would be
used during all impact hammer operations.
For pile driving activities, the Navy used NMFS-promulgated
thresholds for assessing pile driving and removal impacts (NMFS, 2005b,
2009), outlined later in this document. The Navy used recommended
spreading loss formulas (the practical spreading loss equation for
underwater sounds and the spherical spreading loss equation for
airborne sounds) and empirically-measured source levels from other 30-
66 in (0.8-1.7 m) diameter pile driving events to estimate potential
marine mammal exposures. Predicted exposures are outlined later in this
document. The calculations predict that no Level A harassments would
occur associated with pile driving or construction activities, and that
as many as 18,225 Level B harassments may occur during the wharf
construction project from sound produced by pile driving activity.
Description of the Specified Activity
NBKB is located on the Hood Canal approximately twenty miles (32
km) west of Seattle, Washington (see Figures 2-1 through 2-4 in the
Navy's application). NBKB provides berthing and support services for
OHIO Class ballistic missile submarines (SSBN), also known as TRIDENT
submarines. The Navy proposes to begin construction of the EHW-2
facility at NBKB in order to support future program requirements for
TRIDENT submarines berthed at NBKB. The Navy states that construction
of EHW-2 is necessary because the existing EHW alone will not be able
to support future TRIDENT program requirements. The proposed actions
with the potential to cause harassment of marine mammals within the
waterways adjacent to NBKB, under the MMPA, are vibratory and impact
pile driving operations, as well as vibratory removal of falsework
piles, associated with the wharf construction project. The proposed
activities that would be authorized by this IHA would occur between
July 16, 2012, and July 15, 2013. All in-water construction activities
within the Hood Canal are only permitted during July 16-February 15 in
order to protect spawning fish populations.
As part of the Navy's sea-based strategic deterrence mission, the
Navy Strategic Systems Programs directs research, development,
manufacturing, testing, evaluation, and operational support for the
TRIDENT Fleet Ballistic Missile program. Development of necessary
facilities for handling of explosive materials is part of these duties.
The EHW-2 would consist of two components: (1) The wharf proper (or
Operations Area), including the warping wharf; and (2) two access
trestles. Please see Figures 1-1 and 1-2 of the Navy's application for
conceptual and schematic representations of the proposed EHW-2. The
Operations Area would include a support building and wharf cover. A
warping wharf is a long, narrow wharf extension used to position
submarines prior to moving into the Operations Area. The access
trestles would allow vehicles to travel between the Operations Area and
the shore.
The wharf proper would lie approximately 600 ft (183 m) offshore at
water depths of 60-100 ft (18-30 m), and would consist of the main
wharf, a warping wharf, and lightning protection towers, all pile-
supported. It would include a slip (docking area) for submarines,
surrounded on three sides by operational wharf area. The main wharf
would include an operations support building providing office and
storage space and mechanical/electrical system component housing.
Additional facility support at the wharf would include heavy duty
cranes suspended from the cover, power utility booms, six large
lightning protection towers, and camels (operational platforms that
float next to a moored vessel).
The access trestles would connect the wharf to the shore. There
would be an entrance trestle and an exit trestle; these would be
combined over shallow water to reduce overwater area. The trestles
would be pile-supported on 24-in (0.6-m) steel pipe piles driven
approximately 30 ft (9 m) into the seafloor. Spacing between bents
(rows of piles) would be 25 ft (8 m). Concrete pile caps would be cast
in place and would support pre-cast concrete deck sections.
For the entire project, a total of up to 1,250 permanent piles
ranging in size between 24-48 in (0.6-1.2 m) in diameter would be
driven in-water to construct the wharf, with up to three vibratory rigs
and one impact driving rig operating simultaneously. Construction would
also involve temporary installation of up to 150 falsework piles used
as an aid to guide permanent piles to their proper locations. Falsework
piles, which would be removed upon installation of the permanent piles,
would likely be steel pipe piles and would be driven and removed using
a vibratory driver. It has not been determined exactly what parts or
how much of the project would be constructed during the first year;
however, a maximum of 195 days of pile driving would occur. The
analysis contained herein is based upon the maximum of 195 pile driving
days, rather than any specific number of piles driven, and assumes that
(1) all marine mammals available to be incidentally taken within the
relevant area would be; and (2) individual marine mammals may only be
incidentally taken once in a 24-h period--for purposes of authorizing
specified numbers of take--regardless of actual number of exposures in
that period. Table 1 summarizes the number and nature of piles required
for the entire project, rather than what subset of piles may be
expected to be driven during the first year of construction proposed
for this IHA.
------------------------------------------------------------------------
Feature Quantity
------------------------------------------------------------------------
Total number of permanent in-water piles.. Up to 1,250.
Size and number of main wharf piles....... 24-in: 140.
36-in (0.9-m): 157.
48-in: 263.
Size and number of warping wharf piles.... 24-in: 80.
36-in: 190.
Size and number of lightning tower piles.. 24-in: 40.
36-in: 90.
Size and number of trestle piles.......... 24-in: 57.
36-in: 233.
Falsework piles........................... Up to 150, 18- to 24-in.
Maximum pile driving duration............. 195 days (under 1-year IHA).
------------------------------------------------------------------------
Pile installation would utilize vibratory pile drivers to the
greatest extent possible, and the Navy anticipates that most piles
would be able to be vibratory driven to within several feet of the
required depth. Pile drivability is, to a large degree, a function of
soil conditions and the type of pile hammer. The soil conditions
encountered during geotechnical explorations at NBKB indicate existing
conditions generally consist of fill or sediment of very dense
glacially overridden soils. Recent experience at two other construction
locations along the NBKB waterfront indicates that most piles should be
able to be driven with a vibratory hammer to proper embedment depth.
However, difficulties during pile driving may be encountered as a
result of obstructions that may exist throughout the project area. Such
obstructions may consist of rocks or boulders within the glacially
overridden soils. If difficult driving conditions
[[Page 79412]]
occur, increased usage of an impact hammer would occur.
Unless difficult driving conditions are encountered, an impact
hammer will only be used to proof the load-bearing capacity of
approximately every fourth or fifth pile. The industry standard is to
proof every pile with an impact hammer; however, in an effort to reduce
blow counts from the impact hammer, the engineer of record has agreed
to only proof every fourth or fifth pile. A maximum of 200 strikes
would be required to proof each pile. Pile production rates are
dependent upon required embedment depths, the potential for
encountering difficult driving conditions, and the ability to drive
multiple piles without a need to relocate the driving rig. Under best-
case scenarios (i.e., shallow piles, driving in optimal conditions,
using multiple driving rigs), it may be possible to install enough
pilings with the vibratory hammer that proofing may be required for up
to five piles in a day. Under this likely scenario, with a single
impact hammer used to proof up to five piles per day at 200 strikes per
pile, it is estimated that up to a maximum of 1,000 strikes from an
impact hammer would be required per day.
If difficult subsurface driving conditions (i.e., cobble/boulder
zones) are encountered that cause refusal with the vibratory equipment,
it may be necessary to use an impact hammer to drive some piles for the
remaining portion of their required depth. The worst-case scenario is
that a pile would be driven for its entire length using an impact
hammer. Given the uncertainty regarding the types and quantities of
boulders or cobbles that may be encountered, and the depth at which
they may be encountered, the number of strikes necessary to drive a
pile its entire length could be approximately 1,000 to 2,000 strikes
per pile. The Navy estimates that a possible worst-case daily scenario
would require driving three piles full length (at a worst-case of 2,000
strikes per pile) after the piles have become hung on large boulders
early in the installation process, with proofing of an additional two
piles (at 200 strikes each) that were able to be installed primarily
via vibratory means. This worst-case scenario would therefore result in
a maximum of 6,400 strikes per day. All piles driven or struck with an
impact hammer would be surrounded by a bubble curtain or other sound
attenuation device over the full water column to minimize in-water
sound. Up to three vibratory rigs and one impact rig would be used at a
time. Pile production rate (number of piles driven per day) is affected
by many factors: size, type (vertical vs. angled), and location of
piles; weather; number of driver rigs operating; equipment reliability;
geotechnical (subsurface) conditions; and work stoppages for security
or environmental reasons (such as presence of marine mammals).
Pile driving would typically take place 6 days per week. The
allowable season for in-water work, including pile driving, at NBKB is
July 16 through February 15, which was established by the Washington
Department of Fish and Wildlife in coordination with NMFS and the U.S.
Fish and Wildlife Service (USFWS) to protect juvenile salmon. Impact
pile driving during the first half of the in-water work window (July 16
to September 15) would only occur between 2 hours after sunrise and 2
hours before sunset to protect breeding marbled murrelets (an ESA-
listed bird under the jurisdiction of USFWS). Between September 16 and
February 15, construction activities occurring in the water would occur
during daylight hours (sunrise to sunset). Other construction (not in-
water) may occur between 7 a.m. and 10 p.m., year-round.
The number of construction barges (derrick and material) on site at
any one time would vary between two and eight depending on the type of
construction taking place. The maximum number of eight barges would
likely be present at the beginning of construction, with multiple rigs
and their support barges required to complete the work at various areas
of the wharf. As pile installation progresses, the area will become
congested, limiting the space available to support the pile driving
rigs and barges. Also, as sections of the wharf are completed the need
for some of the rigs/barges will be reduced. As a result, fewer barges
would likely be necessary as the project progresses. Tug boats would
tow barges to and from the construction site and position the barges
for construction activity. Tug boats would leave the site once these
tasks were completed and so would not be on site for extended periods;
there would be no more than two tug boats on site at any one time. Up
to six smaller skiff-type boats would be on site performing various
functions in support of construction and monitoring requirements.
Operation of the EHW-2 would not result in an increase in boat
traffic along the NBKB waterfront. Rather, a portion of the ongoing
operations and boat traffic at the existing EHW and other facilities
within the Waterfront Restricted Area (e.g., Delta Pier and Marginal
Wharf) would be diverted to the EHW-2. The EHW-2 may be used as a
backup explosives handling facility for TRIDENT submarines currently
homeported at NBKB when there are no TRIDENT operations at the existing
EHW. The EHW-2 may also provide temporary berthing when no ordnance
handling operations are occurring at either wharf. No increase in boat
traffic would be required to achieve planned operations. The increase
in future operations at the waterfront would only require that boats
remain at an EHW longer when in port for maintenance and upgrades. The
overall level of traffic and activity along the NBKB waterfront would
not increase as a result of operating the EHW-2. Operation of the EHW-2
may require approximately twenty additional military and civilian
personnel. The EHW-2 would be staffed 24 hours per day, 7 days per
week. Maintenance of the EHW-2 would include routine inspections,
repair, and replacement of facility components as required. It would
not be necessary to replace piles during the design life of the EHW-2.
Fouling organisms would not be removed from piles.
Description of Sound Sources
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 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 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). It 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 SPLs (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 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
[[Page 79413]]
then taking the square root of the average (Urick, 1975). 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. Underwater sound levels (`ambient
sound') are comprised of multiple sources, including 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). Even in the
absence of anthropogenic sound, the sea is typically a loud
environment. A number of sources of sound are likely to occur within
Hood Canal, 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 noise for frequencies between 200 Hz and 50
kHz (Mitson, 1995). In general, ambient noise levels tend to increase
with increasing wind speed and wave height. Surf noise becomes
important near shore, with measurements collected at a distance of 8.5
km (5.3 mi) from shore showing an increase of 10 dB in the 100 to 700
Hz band during heavy surf conditions.
Precipitation noise: Noise from rain and hail impacting
the water surface can become an important component of total noise at
frequencies above 500 Hz, and possibly down to 100 Hz during quiet
times.
Biological noise: Marine mammals can contribute
significantly to ambient noise levels, as can some fish and shrimp. The
frequency band for biological contributions is from approximately 12 Hz
to over 100 kHz.
Anthropogenic noise: Sources of ambient noise 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 (Richardson et
al., 1995). Shipping noise typically dominates the total ambient noise
for frequencies between 20 and 300 Hz. In general, the frequencies of
anthropogenic sounds are below 1 kHz and, if higher frequency sound
levels are created, they will attenuate (decrease) rapidly (Richardson
et al., 1995). Known sound levels and frequency ranges associated with
anthropogenic sources similar to those that would be used for this
project are summarized in Table 2. Details of each of the sources are
described in the following text.
Table 2--Representative Sound Levels of Anthropogenic sources
----------------------------------------------------------------------------------------------------------------
Frequency Underwater sound level (dB
Sound source range (Hz) re 1 [mu]Pa) Reference
----------------------------------------------------------------------------------------------------------------
Small vessels............................ 250-1,000 151 dB rms at 1 m (3.3 ft). Richardson et al., 1995.
Tug docking gravel barge................. 200-1,000 149 dB rms at 100 m (328 Blackwell and Greene, 2002.
ft).
Vibratory driving of 72-in (1.8 m) steel 10-1,500 180 dB rms at 10 m (33 ft). Illingworth and Rodkin,
pipe pile. 2007.
Impact driving of 36-in steel pipe pile.. 10-1,500 195 dB rms at 10 m......... WSDOT, 2007.
Impact driving of 66-in cast-in-steel- 10-1,500 195 dB rms at 10 m......... Reviewed in Hastings and
shell pile. Popper, 2005.
----------------------------------------------------------------------------------------------------------------
In-water construction activities associated with the project would
include impact pile driving and vibratory pile driving and removal. The
sounds produced by these activities fall into one of two sound types:
pulsed and non-pulsed (defined in next paragraph). 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 sounds (e.g., explosions, gunshots, sonic booms, and impact
pile driving) are brief, broadband, atonal transients (ANSI, 1986;
Harris, 1998) 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
decay period that may include a period of diminishing, oscillating
maximal and minimal pressures. Pulsed sounds generally have an
increased capacity to induce physical injury as compared with sounds
that lack these features.
Non-pulse (intermittent or continuous sounds) can be tonal,
broadband, or both. Some of these non-pulse sounds can be transient
signals of short duration but without the essential properties of
pulses (e.g., rapid rise time). Examples of non-pulse 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 (Caltrans,
2009). Rise time is slower, reducing the probability and severity of
injury (USFWS, 2009), and sound energy is distributed over a greater
amount of time (Nedwell and Edwards, 2002; Carlson et al., 2001).
Ambient Sound
The underwater acoustic environment consists of ambient sound,
defined as environmental background sound levels
[[Page 79414]]
lacking a single source or point (Richardson et al., 1995). The ambient
underwater sound level of a region is defined by the total acoustical
energy being generated by known and unknown sources, including sounds
from both natural and anthropogenic sources. The sum of the various
natural and anthropogenic sound sources at any given location and time
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, the ambient sound levels at a given frequency and location can
vary by 10-20 dB from day to day (Richardson et al., 1995).
In the vicinity of the project area, the average broadband ambient
underwater sound levels were measured at 114 dB re 1[mu]Pa between 100
Hz and 20 kHz (Slater, 2009). Peak spectral sound from industrial
activity was noted below the 300 Hz frequency, with maximum levels of
110 dB re 1[mu]Pa noted in the 125 Hz band. In the 300 Hz to 5 kHz
range, average levels ranged between 83-99 dB re 1[mu]Pa. Wind-driven
wave sound dominated the background sound environment at approximately
5 kHz and above, and ambient sound levels flattened above 10 kHz.
Airborne sound levels at NBKB vary based on location but are
estimated to average around 65 dBA (A-weighted decibels) in the
residential and office park areas, with traffic sound ranging from 60-
80 dBA during daytime hours (Cavanaugh and Tocci, 1998). The highest
levels of airborne sound are produced along the waterfront and at the
ordnance handling areas, where estimated sound levels range from 70-90
dBA and may peak at 99 dBA for short durations. These higher sound
levels are produced by a combination of sound sources including heavy
trucks, forklifts, cranes, marine vessels, mechanized tools and
equipment, and other sound-generating industrial or military
activities.
Sound Attenuation Devices
Sound levels can be greatly reduced during impact pile driving
using sound attenuation devices. There are several types of sound
attenuation devices including bubble curtains, cofferdams, and
isolation casings (also called temporary noise attenuation piles
[TNAP]), and cushion blocks. Bubble curtains create a column of air
bubbles rising around a pile from the substrate to the water surface.
The air bubbles absorb and scatter sound waves emanating from the pile,
thereby reducing the sound energy. Bubble curtains may be confined or
unconfined. An unconfined bubble curtain may consist of a ring seated
on the substrate and emitting air bubbles from the bottom. An
unconfined bubble curtain may also consist of a stacked system, that
is, a series of multiple rings placed at the bottom and at various
elevations around the pile. Stacked systems may be more effective than
non-stacked systems in areas with high current and deep water
(Caltrans, 2009).
A confined bubble curtain contains the air bubbles within a
flexible or rigid sleeve made from plastic, cloth, or pipe. Confined
bubble curtains generally offer higher attenuation levels than
unconfined curtains because they may physically block sound waves and
they prevent air bubbles from migrating away from the pile. For this
reason, the confined bubble curtain is commonly used in areas with high
current velocity (Caltrans, 2009).
An isolation casing is a hollow pipe that surrounds the pile,
isolating it from the in-water work area. The casing is dewatered
before pile driving. This device provides levels of sound attenuation
similar to that of bubble curtains (Caltrans, 2009). Sound levels can
be reduced by 8 to 14 dB. Cushion blocks consist of materials (e.g.,
wood, nylon) placed atop piles during impact pile driving activities to
reduce source levels. Typically sound reduction can range from 4 to a
maximum of 26 dB.
Cofferdams are often used during construction for isolating the in-
water work area, but may also be used as a sound attenuation device.
Dewatered cofferdams may provide the highest levels of sound reduction
of any attenuation device; however, they do not eliminate underwater
sound because sound can be transmitted through the substrate (Caltrans,
2009). Cofferdams that are not dewatered provide very limited reduction
in sound levels.
Both environmental conditions and the characteristics of the sound
attenuation device may influence the effectiveness of the device.
According to Caltrans (2009):
In general, confined bubble curtains attain better sound
attenuation levels in areas of high current than unconfined bubble
curtains. If an unconfined device is used, high current velocity may
sweep bubbles away from the pile, resulting in reduced levels of sound
attenuation.
Softer substrates may allow for a better seal for the
device, preventing leakage of air bubbles and escape of sound waves.
This increases the effectiveness of the device. Softer substrates also
provide additional attenuation of sound traveling through the
substrate.
Flat bottom topography provides a better seal, enhancing
effectiveness of the sound attenuation device, whereas sloped or
undulating terrain reduces or eliminates its effectiveness.
Air bubbles must be close to the pile; otherwise, sound
may propagate into the water, reducing the effectiveness of the device.
Harder substrates may transmit ground-borne sound and
propagate it into the water column.
The literature presents a wide array of observed attenuation
results for bubble curtains (e.g., WSF, 2009; WSDOT, 2008; USFWS, 2009;
Caltrans, 2009). The variability in attenuation levels is due to
variation in design, as well as differences in site conditions and
difficulty in properly installing and operating in-water attenuation
devices. As a general rule, reductions of greater than 10 dB cannot be
reliably predicted (Caltrans, 2009).
Sound Thresholds
Since 1997, NMFS has used generic sound exposure thresholds to
determine when an activity in the ocean that produces sound might
result in impacts to a marine mammal such that a take by harassment
might occur (NMFS, 2005b). To date, no studies have been conducted that
examine impacts to marine mammals from pile driving sounds from which
empirical sound thresholds have been established. Current NMFS practice
regarding exposure of marine mammals to sound is that cetaceans and
pinnipeds exposed to impulsive sounds of 180 and 190 dB rms or above,
respectively, are considered to have been taken by Level A (i.e.,
injurious) harassment. Behavioral harassment (Level B) is considered to
have occurred when marine mammals are exposed to sounds at or above 160
dB rms for impulse sounds (e.g., impact pile driving) and 120 dB rms
for continuous sound (e.g., vibratory pile driving), but below
injurious thresholds. For airborne sound, pinniped disturbance from
haul-outs has been documented at 100 dB (unweighted) for pinnipeds in
general, and at 90 dB (unweighted) for harbor seals. NMFS uses these
levels as guidelines to estimate when harassment may occur.
Distance to Sound Thresholds
Underwater Sound Propagation Formula--Pile driving would generate
[[Page 79415]]
underwater noise that potentially could result in disturbance to marine
mammals in the project area. Transmission loss (TL) is the decrease in
acoustic intensity as an acoustic pressure wave propagates out from a
source. TL parameters vary with frequency, temperature, sea conditions,
current, source and receiver depth, water depth, water chemistry, and
bottom composition and topography. A practical sound propagation
modeling technique was used by the Navy to estimate the range from the
pile driving activity to various SPL thresholds in water. This model
follows a geometric propagation loss based on the distance from the
driven pile, resulting in a 4.5 dB reduction in level for each doubling
of distance from the source. In this model, the SPL at some distance
away from the source (e.g., driven pile) is governed by a measured
source level, minus the transmission loss of the energy as it
dissipates with distance. The formula for underwater TL is:
TL = 15 * log10(R1/R2), where
R1 = the distance of the modeled SPL from the driven
pile, and
R2 = the distance from the driven pile of the initial
measurement.
The degree to which underwater sound propagates away from a sound
source is dependent on a variety of factors, most notably by the water
bathymetry and presence or absence of reflective or absorptive
conditions including in-water structures and sediments. 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]). The propagation environment
along the NBKB waterfront conforms to neither spherical nor cylindrical
spreading; as the receiver moves away from the shoreline, the water
increases in depth, resulting in an expected propagation environment
that would lie between spherical and cylindrical spreading loss
conditions. Since there is no available data regarding propagation loss
along the NBKB waterfront, a practical spreading loss model was adopted
as the most likely approximation of the sound propagation environment.
Hydroacoustic monitoring results from the Navy's Test Pile Project (see
76 FR 38361; July 30, 2011) will be used, when available, to confirm
the validity of the practical spreading model for estimating acoustic
propagation in the project area. That project concluded on October 31,
2011.
Underwater Sound From Pile Driving--The intensity of pile driving
sounds is greatly influenced by factors such as the type of piles,
hammers, and the physical environment in which the activity takes
place. A large quantity of literature regarding SPLs recorded from pile
driving projects is available for consideration. In order to determine
reasonable SPLs and their associated affects on marine mammals that are
likely to result from pile driving at NBKB, studies with similar
properties to the proposed action were evaluated. Sound levels
associated with vibratory pile removal are assumed to be the same as
those during vibratory installation (Caltrans, 2007)--which is likely a
conservative assumption--and have been taken into consideration in the
modeling analysis. Overall, studies which met the following parameters
were considered: (1) Pile size and materials: Steel pipe piles (30-72
in diameter); (2) Hammer machinery: Vibratory and impact hammer; and
(3) Physical environment: shallow depth (less than 100 ft [30 m]).
Table 3--Underwater SPLs From Monitored Construction Activities Using Impact Hammers
----------------------------------------------------------------------------------------------------------------
Project and location Pile size and type Water depth Measured SPLs
----------------------------------------------------------------------------------------------------------------
Eagle Harbor Maintenance Facility, WA 30-in (0.8 m) steel 10 m (33 ft)........... 192 dB re 1 [micro]Pa
pipe pile. (rms) at 10 m (33 ft).
Friday Harbor Ferry Terminal, WA..... 30-in steel pipe pile.. 10 m................... 196 dB re 1 [micro]Pa
(rms) at 10 m.
Unknown, CA.......................... 36-in steel pipe pile.. 10 m................... 193 dB re 1 [micro]Pa
(rms) at 10 m.
Mukilteo Test Piles, WA.............. 36-in steel pipe pile.. 7.3 m (24 ft).......... 195 dB re 1 [micro]Pa
(rms) at 10 m.
Anacortes Ferry, WA.................. 36-in steel pipe pile.. 12.8 m (42 ft)......... 199 dB re 1 [micro]Pa
(rms) at 10 m.
Carderock Pier, NBKB, WA............. 42-in steel pipe pile.. 14-22 m (48-70 ft)..... 195 dB re 1 [micro]Pa
(rms) at 10 m.
Russian River, CA.................... 48-in steel pipe pile.. 2 m (6.6 ft)........... 195 dB re 1 [micro]Pa
(rms) at 10 m.
Unknown, CA.......................... 60-in cast-in-steel- 10 m................... 195 dB re 1 [micro]Pa
shell. (rms) at 10 m.
Richmond-San Rafael Bridge, CA....... 66-in steel pipe pile.. 4 m (13 ft)............ 195 dB re 1 [micro]Pa
(rms) at 10 m.
----------------------------------------------------------------------------------------------------------------
Sources: WSDOT, 2005, 2008; Caltrans, 2007; Reyff, 2005; JASCO, 2005; Laughlin, 2005; Navy, 2009.
The tables presented here detail representative pile driving SPLs
that have been recorded from similar construction activities in recent
years. Due to the similarity of these actions and the Navy's proposed
action, these values represent reasonable SPLs which could be
anticipated, and which were used in the acoustic modeling and analysis.
Table 3 represents SPLs that may be expected during pile installation
using an impact hammer. Table 4 represents SPLs that may be expected
during pile installation using a vibratory hammer.
Table 4--Underwater SPLs From Monitored Construction Activities Using Vibratory Hammers
----------------------------------------------------------------------------------------------------------------
Project and location Pile size and type Water depth Measured SPLs
----------------------------------------------------------------------------------------------------------------
Keystone Ferry Terminal, WA \1\...... 30-in (0.8 m) steel 5 m (15 ft)............ 164 dB re 1 [mu]Pa
pipe pile. (rms) at 10 m (33 ft).
Keystone Ferry Terminal, WA \1\...... 30-in steel pipe pile.. 8 m (28 ft)............ 165 dB re 1 [mu]Pa
(rms) at 10 m.
Vashon Ferry Terminal, WA \2\........ 30-in steel pipe pile.. 6 m (20 ft)............ 165 dB re 1 [mu]Pa
(rms) at 10 m.
Unknown, CA.......................... 36-in steel pipe pile.. 5 m.................... 170 dB re 1 [mu]Pa
(rms) at 10 m.
Unknown, CA.......................... 36-in steel pipe pile.. 5 m.................... 175 dB re 1 [mu]Pa
(rms) at 10 m.
Unknown, CA.......................... 72-in steel pipe pile.. 5 m.................... 170 dB re 1 [mu]Pa
(rms) at 10 m.
Unknown, CA.......................... 72-in steel pipe pile.. 5 m.................... 180 dB re 1 [mu]Pa
(rms) at 10 m.
----------------------------------------------------------------------------------------------------------------
Sources: Laughlin, 2010a; Laughlin, 2010b; Caltrans, 2007.
[[Page 79416]]
As described previously in this document, sound attenuation
measures, including bubble curtains, can be employed during impact pile
driving to reduce the high source pressures. For the wharf construction
project, the Navy intends to employ sound reduction techniques during
impact pile driving, including the use of sound attenuation systems
(e.g., bubble curtain). See ``Proposed Mitigation'', later in this
document, for more details on the impact reduction and mitigation
measures proposed. The calculations of the distances to the marine
mammal sound thresholds were calculated for impact installation with
the assumption of a 10 dB reduction in source levels from the use of
sound attenuation devices, and the Navy used the mitigated distances
for impact pile driving for all analysis in their application. The Navy
will analyze data from the Test Pile Program to confirm the level of
achieved sound attenuation from use of a bubble curtain or similar
device using site-specific conditions.
All calculated distances to and the total area encompassed by the
marine mammal sound thresholds are provided in Table 5. The Navy used
source values of 185 dB for impact driving (the mean SPL of the values
presented in Table 3, less 10 dB of sound attenuation from use of a
bubble curtain or similar device) and 180 dB for vibratory driving (the
worst-case value from Table 4). The 195 dB mean SPL of values presented
in Table 3 was considered appropriate because it matched values from
projects where larger-size pile was used and, in addition, matched the
value obtained from the Carderock project, which was located at the
NBKB waterfront and involved similar pile materials, water depth, and
bottom type. The maximum value from Table 4 of 180 dB was deemed
appropriate for vibratory driving because no data were available for
48-in and 60-in piles. As a result, the most conservative value was
selected. Under likely construction scenarios, up to three vibratory
drivers would operate simultaneously with one impact driver. Although
radial distance and area associated with the zone ensonified to 160 dB
(the behavioral harassment threshold for pulsed sounds, such as those
produced by impact driving) are presented in Table 5, this zone would
be subsumed by the 120 dB zone produced by vibratory driving. Thus,
behavioral harassment of marine mammals associated with impact driving
is not considered further here. Since the 160 dB threshold and the 120
dB threshold both indicate behavioral harassment, pile driving effects
in the two zones are equivalent. Although such a day is not planned, if
only the impact driver was operated on a given day, incidental take on
that day would likely be lower because the area ensonified to levels
producing Level B harassment would be smaller (although actual take
would be determined by the numbers of marine mammals in the area on
that day). The use of multiple vibratory rigs at the same time would
result in a small additive effect with regard to produced SPLs;
however, because the sound field produced by vibratory driving would be
truncated by land in the Hood Canal, no increase in actual sound field
produced would occur. There would be no overlap in the 190/180-dB sound
fields produced by rigs operating simultaneously.
Table 5--Calculated Distance(s) to and Area Encompassed by Underwater
Marine Mammal Sound Thresholds During Pile Installation
------------------------------------------------------------------------
Area, km\2\
Threshold Distance (mi\2\)
------------------------------------------------------------------------
Impact driving, pinniped injury 4.9 m (16.1 ft)... 0.0001
(190 dB).
Impact driving, cetacean injury 22 m (72.2 ft).... 0.002 (0.0008)
(180 dB).
Impact driving, disturbance (160 724 m (2,375 ft).. 1.65 (0.64)
dB)\2\.
Vibratory driving, pinniped 2.1 m (6.9 ft).... < 0.0001
injury (190 dB).
Vibratory driving, cetacean 10 m (32.8 ft).... 0.0003 (0.0001)
injury (180 dB).
Vibratory driving, disturbance 13,800 m (45,276 41.4 (15.98)
(120 dB). ft)\3\.
------------------------------------------------------------------------
\1\ SPLs used for calculations were: 185 dB for impact and 180 dB for
vibratory driving.
\2\ Area of 160-dB zone presented for reference. Estimated incidental
take calculated on basis of larger 120-dB zone.
\3\ Hood Canal average width at site is 2.4 km (1.5 mi), and is fetch
limited from N to S at 20.3 km (12.6 mi). Calculated range (over 222
km) is greater than actual sound propagation through Hood Canal due to
intervening land masses. 13.8 km (8.6 mi) is the greatest line-of-
sight distance from pile driving locations unimpeded by land masses,
which would block further propagation of sound.
Hood Canal does not represent open water, or free field,
conditions. Therefore, sounds would attenuate as they encounter land
masses or bends in the canal. As a result, the calculated distance and
areas of impact for the 120 dB threshold cannot actually be attained at
the project area. See Figure 6-1 of the Navy's application for a
depiction of the size of areas in which each underwater sound threshold
is predicted to occur at the project area due to pile driving.
Airborne Sound Propagation Formula--Pile driving can generate
airborne sound that could potentially result in disturbance to marine
mammals (specifically, pinnipeds) which are hauled out or at the
water's surface. As a result, the Navy analyzed the potential for
pinnipeds hauled out or swimming at the surface near NBKB to be exposed
to airborne SPLs that could result in Level B behavioral harassment.
The appropriate airborne sound threshold for behavioral disturbance for
all pinnipeds, except harbor seals, is 100 dB re 20 [micro]Pa rms
(unweighted). For harbor seals, the threshold is 90 dB re 20 [micro]Pa
rms (unweighted). A spherical spreading loss model, assuming average
atmospheric conditions, was used to estimate the distance to the 100 dB
and 90 dB re 20 [micro]Pa rms (unweighted) airborne thresholds. The
formula for calculating spherical spreading loss is:
TL = 20log(R1/R2)
TL = Transmission loss
R1 = the distance of the modeled SPL from the driven
pile, and
R2 = the distance from the driven pile of the initial
measurement.
Airborne Sound From Pile Installation--As was discussed for
underwater sound from pile driving, the intensity of pile driving
sounds is greatly influenced by factors such as the type of piles,
hammers, and the physical environment in which the activity takes
place. In order to determine reasonable airborne SPLs and their
associated effects on marine mammals that are likely to result from
pile driving at NBKB, studies with similar properties to the proposed
action, as described previously, were evaluated. Table 6 details
representative pile driving activities that have occurred in recent
years. Due to the similarity of these actions and the Navy's proposed
action, they represent reasonable SPLs which could be anticipated.
[[Page 79417]]
Table 6--Airborne SPLs From Similar Construction Activities
----------------------------------------------------------------------------------------------------------------
Project & location Pile size &type Method Water depth Measured SPLs
----------------------------------------------------------------------------------------------------------------
Northstar Island, AK \1\....... 42-in (1.1 m) Impact............. Approximately 12 m 97 dB re 20
steel pipe pile. (40 ft). [micro]Pa (rms)
at 160 m (525
ft).
Keystone Ferry Terminal, WA \3\ 30-in (0.8 m) Vibratory.......... Approximately 9 m 97 dB re 20
steel pipe pile. (30 ft). [micro]Pa (rms)
at 13 m (40 ft).
----------------------------------------------------------------------------------------------------------------
Sources: Blackwell et al., 2004; Laughlin, 2010b.
Based on in-situ recordings from similar construction activities,
the maximum airborne sound levels that would result from impact and
vibratory pile driving are estimated to be 97 dB rms re 20 [mu]Pa at
160 m and 97 dB rms re 20 [mu]Pa at 13 m, respectively (Blackwell et
al., 2004; Laughlin, 2010b). The distances to the airborne thresholds
were calculated with the airborne transmission loss formula presented
previously. The Navy has analyzed the combined sound field produced
under the multi-rig scenario and calculated the radial distances to the
90 and 100 dB airborne thresholds as 361 m (1,184 ft) and 114 m (374
ft), respectively, equating to areas of 0.41 km\2\ (0.16 mi\2\) and
0.04 km\2\ (0.02 mi\2\), respectively. These distances would be
significantly less for the vibratory driver alone, approximately 28 m
(92 ft) and 9 m (30 ft), respectively.
All airborne distances are less than those calculated for
underwater sound thresholds. Protective measures would be in place out
to the distances calculated for the underwater thresholds, and the
distances for the airborne thresholds would be covered fully by
mitigation and monitoring measures in place for underwater sound
thresholds. Construction sound associated with the project would not
extend beyond the buffer zone for underwater sound that would be
established to protect pinnipeds. No haul-outs or rookeries are located
within the airborne harassment radii. See Figure 6-2 of the Navy's
application for a depiction of the size of areas in which each airborne
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 six marine mammal species, three cetaceans and three
pinnipeds, which may inhabit or transit through the waters nearby NBKB
in the Hood Canal. These include the transient killer whale, harbor
porpoise, Dall's porpoise, Steller sea lion, California sea lion, and
the harbor seal. While the Southern Resident killer whale is resident
to the inland waters of Washington and British Columbia, it has not
been observed in the Hood Canal in over 15 years, and therefore was
excluded from further analysis. The Steller sea lion is the only marine
mammal that occurs within the Hood Canal which is listed under the ESA;
the Eastern DPS is listed as threatened. All marine mammal species are
protected under the MMPA. This section summarizes the population status
and abundance of these species, followed by detailed life history
information. Table 7 lists the marine mammal species that occur in the
vicinity of NBKB and their estimated densities within the project area
during the proposed timeframe. Daily maximum abundance data only is
presented for sea lions because sightings data have no defined survey
area.
Table 7--Marine Mammals Present in the Hood Canal in the Vicinity of NBKB
----------------------------------------------------------------------------------------------------------------
Density during
in-water work
Species Stock abundance \1\ Relative occurrence Season of season \3\
in Hood Canal occurrence (individuals/km
\2\)
----------------------------------------------------------------------------------------------------------------
Steller sea lion
Eastern U.S.DPS............. 58,334-72,223 \2\.. Occasional presence Fall to late \3\ 1.2
spring (Oct to
mid-April).
California sea lion
U.S. Stock.................. 238,000............ Common............. Fall to late \3\ 26.2
spring (Aug to
early June).
Harbor seal
WA inland waters stock...... 14,612 (CV = 0.15). Common............. Year-round; \4\ 1.31
resident species
in Hood Canal.
Killer whale
West Coast transient stock.. 354................ Rare to occasional Year-round........ \5\ 0.038
presence.
Dall's porpoise
CA/OR/WA stock.............. 42,000 (CV = 0.33). Rare to occasional Year-round........ \6\ 0.014
presence.
Harbor porpoise
WA inland waters stock...... 10,682 (CV = 0.38). Possible regular to Year-round........ \7\ 0.250
occasional
presence.
----------------------------------------------------------------------------------------------------------------
\1\ NMFS marine mammal stock assessment reports at: http://www.nmfs.noaa.gov/pr/sars/species.htm.
\2\ Range calculated on basis of total pup counts 2006-2009 and extrapolation factors derived from vital rate
parameters estimated for an increasing population.
\3\ Density for sea lions is not calculated due to the lack of a defined survey area for sightings data.
Abundance calculated as the average of the maximum number of individuals present during shore-based surveys at
NBKB waterfront during the in-water construction season.
\4\ Jeffries et al., 2003; Huber et al., 2001.
\5\ Density calculated as the maximum number of individuals present at a given time during occurrences of killer
whales at Hood Canal in 2003 and 2005 (London 2006) divided by the area of Hood Canal.
\6\ Density calculated from number of individuals observed in 18 vessel-based surveys of NBKB waterfront area
(Tannenbaum et al., 2009, 2011).
[[Page 79418]]
\7\ Density calculated from number of individuals observed during vessel-based surveys conducted during Test
Pile Program and corrected for detectability (Navy, in prep.).
Steller Sea Lion
Species Description--Steller sea lions are the largest members of
the Otariid (eared seal) family. Steller sea lions show marked sexual
dimorphism, in which adult males are noticeably larger and have
distinct coloration patterns from females. Males average approximately
1,500 lb (680 kg) and 10 ft (3 m) in length; females average about 700
lb (318 kg) and 8 ft (2.4 m) in length. Adult females have a tawny to
silver-colored pelt. Males are characterized by dark, dense fur around
their necks, giving a mane-like appearance, and light tawny coloring
over the rest of their body (NMFS, 2008a). Steller sea lions are
distributed mainly around the coasts to the outer continental shelf
along the North Pacific Ocean rim from northern Hokkaido, Japan through
the Kuril Islands and Okhotsk Sea, Aleutian Islands and central Bering
Sea, southern coast of Alaska and south to California. The population
is divided into the Western and the Eastern Distinct Population
Segments (DPSs) at 144[deg]W (Cape Suckling, Alaska). The Western DPS
includes Steller sea lions that reside in the central and western Gulf
of Alaska, Aleutian Islands, as well as those that inhabit coastal
waters and breed in Asia (e.g., Japan and Russia). The Eastern DPS
extends from California to Alaska, including the Gulf of Alaska.
Status--Steller sea lions were listed as threatened range-wide
under the ESA in 1990. After division into two stocks, the western
stock was listed as endangered under the ESA in 1997 and the eastern
stock remained classified as threatened. Animals found in the project
area are from the eastern stock (NMFS, 1997a; Loughlin, 2002; Angliss
and Outlaw, 2005). The eastern stock breeds in rookeries located in
southeast Alaska, British Columbia, Oregon, and California; there are
no rookeries located in Washington. A final revised species recovery
plan addresses both stocks (NMFS, 2008a).
Critical habitat was designated for Steller sea lions in 1993.
Critical habitat is associated with breeding and haul-out sites in
Alaska, California, and Oregon, and includes so-called `aquatic zones'
that extend 3,000 ft (0.9 km) seaward in state and federally managed
waters from the baseline or basepoint of each major rookery in Oregon
and California (NMFS, 2008a). Three major rookery sites in Oregon
(Rogue Reef, Pyramid Rock, and Long Brown Rock and Seal Rock on Orford
Reef at Cape Blanco) and three rookery sites in California (Ano Nuevo
I, Southeast Farallon I, and Sugarloaf Island and Cape Mendocino) are
designated critical habitat (NMFS, 1993). There is no designated
critical habitat within the project area.
Limiting factors for recovery of Steller sea lions include reduced
food availability, possibly resulting from competition with commercial
fisheries; incidental take and intentional kills during commercial fish
harvests; subsistence take; entanglement in marine debris; disease;
pollution; and harassment. The change in food availability, associated
with lowered nutritional status of females and consequent reduced
juvenile recruitment, may be the primary cause of the decline (60 FR
51968). Declines of this species in the early 1980s were associated
with exceedingly low juvenile survivorship, whereas declines in the
1990s were associated with disproportionately low fecundity (Holmes and
York, 2003). Steller sea lions are also sensitive to disturbance at
rookeries (during pupping and breeding) and haul-out sites.
The abundance of the Eastern DPS of Steller sea lions is increasing
throughout the northern portion of its range (Southeast Alaska and
British Columbia), and stable or increasing slowly in the central
portion (Oregon through central California). In the southern end of its
range (Channel Islands in southern California), it has declined
significantly since the late 1930s, and several rookeries and haul-outs
have been abandoned. Changes in ocean conditions (e.g., warmer
temperatures) may be contributing to habitat changes that favor
California sea lions over Steller sea lions in the southern portion of
the Steller's range (NMFS, 2007).
The eastern stock was estimated by NMFS in the Recovery Plan for
the Steller Sea Lion to number between 45,000 to 51,000 animals (NMFS,
2008a). This stock has been increasing approximately three percent per
year over the entire range since the late 1970s (NMFS, 2008a; Pitcher
et al., 2007). The most recent population estimate for the eastern
stock is a minimum of 52,847 individuals; this estimate is not
corrected for animals at sea. Actual population is estimated to be
within the range 58,334 to 72,223 (Allen and Angliss, 2010). The most
recent minimum count for Steller sea lions in Oregon and Washington was
5,813 in 2002 (Pitcher et al., 2007; Allen and Angliss, 2010).
The eastern U.S. stock of Steller sea lion is currently listed as
threatened under the ESA, and is therefore designated as depleted and
classified as a strategic stock under the MMPA. However, the eastern
stock of Steller sea lions has been considered a potential candidate
for removal from listing under the ESA by the Steller sea lion recovery
team and NMFS (NMFS, 2008), based on its annual rate of increase of
approximately three percent since the mid-1970s. Although the stock
size has increased, the status of this stock relative to its Optimum
Sustainable Population (OSP) size is unknown. The overall annual rate
of increase of 3.1 percent throughout most of the range (Oregon to
southeastern Alaska) of the eastern stock has been consistent and long-
term, and may indicate that this stock is reaching OSP size (Pitcher et
al., 2007).
Behavior and Ecology--Steller sea lions forage near shore and in
pelagic waters. They are capable of traveling long distances in a
season and can dive to approximately 1,300 ft (400 m) in depth. They
also use terrestrial habitat as haul-out sites for periods of rest,
molting, and as rookeries for mating and pupping during the breeding
season. At sea, they are often seen alone or in small groups, but may
gather in large rafts at the surface near rookeries and haul-outs.
Steller sea lions prefer the colder temperate to sub-arctic waters of
the North Pacific Ocean. Haul-outs and rookeries usually consist of
beaches (gravel, rocky or sand), ledges, and rocky reefs. In the Bering
and Okhotsk Seas, sea lions may also haul-out on sea ice, but this is
considered atypical behavior (NOAA, 2010a).
Steller sea lions are gregarious animals that often travel or haul
out in large groups of up to 45 individuals (Keple, 2002). At sea,
groups usually consist of female and subadult males; adult males are
usually solitary while at sea (Loughlin, 2002). In the Pacific
Northwest, breeding rookeries are located in British Columbia, Oregon,
and northern California. Steller sea lions form large rookeries during
late spring when adult males arrive and establish territories (Pitcher
and Calkins, 1981). Large males aggressively defend territories while
non-breeding males remain at peripheral sites or haul-outs. Females
arrive soon after and give birth. Most births occur from mid-May
through mid-July, and breeding takes
[[Page 79419]]
place shortly thereafter. Most pups are weaned within a year. Non-
breeding individuals may not return to rookeries during the breeding
season but remain at other coastal haul-outs (Scordino, 2006).
Steller sea lions are opportunistic predators, feeding primarily on
fish and cephalopods, and their diet varies geographically and
seasonally (Bigg, 1985; Merrick et al., 1997; Bredesen et al., 2006;
Guenette et al., 2006). Foraging habitat is primarily shallow,
nearshore and continental shelf waters; freshwater rivers; and also
deep waters (Reeves et al., 2008; Scordino, 2010). Steller sea lions
occupy major winter haul-out sites on the coast of Vancouver Island in
the Strait of Juan de Fuca and the Georgia Basin (Bigg, 1985; Olesiuk,
2008); the closest breeding rookery to the project area is at Carmanah
Point near the western entrance to the Strait of Juan de Fuca. There
are no known breeding rookeries in Washington (NMFS, 1992; Angliss and
Outlaw, 2005) but Eastern stock Steller sea lions are present year-
round along the outer coast of Washington at four major haul-out sites
(NMFS, 2008a). Both sexes are present in Washington waters; these
animals are likely immature or non-breeding adults from rookeries in
other areas (NMFS, 2008a). In Washington, Steller sea lions primarily
occur at haul-out sites along the outer coast from the Columbia River
to Cape Flattery. In inland waters, Steller sea lions use haul-out
sites along the Vancouver Island coastline of the Strait of Juan de
Fuca (Jeffries et al., 2000; COSEWIC, 2003; Olesiuk, 2008). Numbers
vary seasonally in Washington waters with peak numbers present during
the fall and winter months (Jeffries et al., 2000). The highest
breeding season Steller sea lion count at Washington haul-out sites was
847 individuals during the period from 1978 to 2001 (Pitcher et al.,
2007). Non-breeding season surveys of Washington haul-out sites
reported as many as 1,458 individuals between 1980 and 2001 (NMFS,
2008a).
Steller sea lions are occasionally present at the Toliva Shoals
haul-out site in south Puget Sound (Jeffries et al., 2000) and a rock
three miles south of Marrowstone Island (NMFS, 2010). Fifteen Steller
sea lions have been observed using this haul-out site. At NBKB, Steller
sea lions have been observed hauled out on submarines at Delta Pier on
several occasions from 2008 through 2011 during fall through spring
months (October to April) (Navy 2010). Other potential haul-out sites
may include isolated islands, rocky shorelines, jetties, buoys, rafts,
and floats (Jeffries et al., 2000). Steller sea lions likely utilize
foraging habitats in Hood Canal similar to those of the California sea
lion and harbor seal, which include marine nearshore and deeper water
habitats.
Acoustics--Like all pinnipeds, the Steller sea lion is amphibious;
while all foraging activity takes place in the water, breeding behavior
is carried out on land in coastal rookeries (Mulsow and Reichmuth
2008). On land, territorial male Steller sea lions regularly use loud,
relatively low-frequency calls/roars to establish breeding territories
(Schusterman et al., 1970; Loughlin et al., 1987). The calls of females
range from 0.03 to 3 kHz, with peak frequencies from 0.15 to 1 kHz;
typical duration is 1.0 to 1.5 sec (Campbell et al., 2002). Pups also
produce bleating sounds. Individually distinct vocalizations exchanged
between mothers and pups are thought to be the main modality by which
reunion occurs when mothers return to crowded rookeries following
foraging at sea (Mulsow and Reichmuth, 2008).
Mulsow and Reichmuth (2008) measured the unmasked airborne hearing
sensitivity of one male Steller sea lion. The range of best hearing
sensitivity was between 5 and 14 kHz. Maximum sensitivity was found at
10 kHz, where the subject had a mean threshold of 7 dB. The underwater
hearing threshold of a male Steller sea lion was significantly
different from that of a female. The peak sensitivity range for the
male was from 1 to 16 kHz, with maximum sensitivity (77 dB re: 1[mu]Pa-
m) at 1 kHz. The range of best hearing for the female was from 16 to
above 25 kHz, with maximum sensitivity (73 dB re: 1[mu]Pa-m) at 25 kHz.
However, because of the small number of animals tested, the findings
could not be attributed to either individual differences in sensitivity
or sexual dimorphism (Kastelein et al., 2005).
California Sea Lion
Species Description--California sea lions are members of the
Otariid family (eared seals). The species, Zalophus californianus,
includes three subspecies: Z. c. wollebaeki (in the Galapagos Islands),
Z. c. japonicus (in Japan, but now thought to be extinct), and Z. c.
californianus (found from southern Mexico to southwestern Canada;
referred to here as the California sea lion) (Carretta et al., 2007).
The California sea lion is sexually dimorphic. Males may reach 1,000 lb
(454 kg) and 8 ft (2.4 m) in length; females grow to 300 lb (136 kg)
and 6 ft (1.8 m) in length. Their color ranges from chocolate brown in
males to a lighter, golden brown in females. At around five years of
age, males develop a bony bump on top of the skull called a sagittal
crest. The crest is visible in the dog-like profile of male sea lion
heads, and hair around the crest gets lighter with age.
Status--The U.S. stock of California sea lions is estimated at
238,000 and the minimum population size of this stock is 141,842
individuals (Carretta et al., 2007). These numbers are from counts
during the 2001 breeding season of animals that were ashore at the four
major rookeries in southern California and at haul-out sites north to
the Oregon/California border. Sea lions that were at-sea or hauled-out
at other locations were not counted (Carretta et al., 2007). The stock
has likely reached its carrying capacity and, even though current total
human-caused mortality is unknown (due to a lack of observer coverage
in the California set gillnet fishery that historically has been the
largest source of human-caused mortalities), California sea lions are
not considered a strategic stock under the MMPA because total human-
caused mortality is still likely to be less than the potential
biological removal (PBR). An estimated 3,000 to 5,000 California sea
lions migrate to waters of Washington and British Columbia during the
non-breeding season from September to May (Jeffries et al., 2000). Peak
numbers of up to 1,000 California sea lions occur in Puget Sound
(including Hood Canal) during this time period (Jeffries et al., 2000).
Distribution--The geographic distribution of California sea lions
includes a breeding range from Baja California, Mexico to southern
California. During the summer, California sea lions breed on islands
from the Gulf of California to the Channel Islands and seldom travel
more than about 31 mi (50 km) from the islands (Bonnell et al., 1983).
The primary rookeries are located on the California Channel Islands of
San Miguel, San Nicolas, Santa Barbara, and San Clemente (Le Boeuf and
Bonnell, 1980; Bonnell and Dailey, 1993). Their distribution shifts to
the northwest in fall and to the southeast during winter and spring,
probably in response to changes in prey availability (Bonnell and Ford,
1987).
The non-breeding distribution extends from Baja California north to
Alaska for males, and encompasses the waters of California and Baja
California for females (Reeves et al., 2008; Maniscalco et al., 2004).
In the non-breeding season, an estimated 3,000-5,000 adult and sub-
adult males migrate northward along the coast to central and northern
California, Oregon,
[[Page 79420]]
Washington, and Vancouver Island from September to May (Jeffries et
al., 2000) and return south the following spring (Mate, 1975; Bonnell
et al., 1983). Along their migration, they are occasionally sighted
hundreds of miles offshore (Jefferson et al., 1993). Females and
juveniles tend to stay closer to the rookeries (Bonnell et al., 1983).
California sea lions are present in Hood Canal during much of the
year with the exception of mid-June through August, and occur regularly
in the vicinity of the project site, as observed during Navy waterfront
surveys conducted at NBKB from April 2008 through June 2010 (Navy,
2010). They are known to utilize man-made structures such as piers,
jetties, offshore buoys, log booms, and oil platforms (Riedman, 1990),
and are often seen rafted off of river mouths (Jeffries et al., 2000).
Although there are no regular California sea lion haul-outs known
within the Hood Canal (Jeffries et al., 2000), they are frequently
observed hauled out at several opportune areas at NBKB (e.g.,
submarines, floating security fence, barges). As many as 58 California
sea lions have been observed hauled out together at NBKB (Agness and
Tannenbaum, 2009a; Tannenbaum et al., 2009a; Walters, 2009). California
sea lions have also been observed swimming in the Hood Canal in the
vicinity of the project area on several occasions and likely forage in
both nearshore marine and inland marine deeper waters (DoN, 2001a).
Behavior and Ecology--California sea lions feed on a wide variety
of prey, including many species of fish and squid (Everitt et al.,
1981; Roffe and Mate, 1984; Antonelis et al., 1990; Lowry et al.,
1991). In the Puget Sound region, they feed primarily on fish such as
Pacific hake (Merluccius productus), walleye pollock (Theragra
chalcogramma), Pacific herring (Clupea pallasii), and spiny dogfish
(Squalus acanthias) (Calambokidis and Baird, 1994). In some locations
where salmon runs exist, California sea lions also feed on returning
adult and out-migrating juvenile salmonids (London, 2006). Sexual
maturity occurs at around four to five years of age for California sea
lions (Heath, 2002). California sea lions are gregarious during the
breeding season and social on land during other times.
Acoustics--On land, California sea lions make incessant, raucous
barking sounds; these have most of their energy at less than 2 kHz
(Schusterman et al., 1967). Males vary both the number and rhythm of
their barks depending on the social context; the barks appear to
control the movements and other behavior patterns of nearby
conspecifics (Schusterman, 1977). Females produce barks, squeals,
belches, and growls in the frequency range of 0.25-5 kHz, while pups
make bleating sounds at 0.25-6 kHz. California sea lions produce two
types of underwater sounds: clicks (or short-duration sound pulses) and
barks (Schusterman et al., 1966, 1967; Schusterman and Baillet, 1969).
All underwater sounds have most of their energy below 4 kHz
(Schusterman et al., 1967).
The range of maximal hearing sensitivity underwater is between 1-28
kHz (Schusterman et al., 1972). Functional underwater high frequency
hearing limits are between 35-40 kHz, with peak sensitivities from 15-
30 kHz (Schusterman et al., 1972). The California sea lion shows
relatively poor hearing at frequencies below 1 kHz (Kastak and
Schusterman, 1998). Peak hearing sensitivities in air are shifted to
lower frequencies; the effective upper hearing limit is approximately
36 kHz (Schusterman, 1974). The best range of sound detection is from
2-16 kHz (Schusterman, 1974). Kastak and Schusterman (2002) determined
that hearing sensitivity generally worsens with depth--hearing
thresholds were lower in shallow water, except at the highest frequency
tested (35 kHz), where this trend was reversed. Octave band sound
levels of 65-70 dB above the animal's threshold produced an average
temporary threshold shift (TTS; discussed later in ``Potential Effects
of the Specified Activity on Marine Mammals'') of 4.9 dB in the
California sea lion (Kastak et al., 1999).
Harbor Seal
Species Description--Harbor seals, which are members of the Phocid
family (true seals), inhabit coastal and estuarine waters and shoreline
areas from Baja California, Mexico to western Alaska. For management
purposes, differences in mean pupping date (i.e., birthing) (Temte,
1986), movement patterns (Jeffries, 1985; Brown, 1988), pollutant loads
(Calambokidis et al., 1985) and fishery interactions have led to the
recognition of three separate harbor seal stocks along the west coast
of the continental U.S. (Boveng, 1988). The three distinct stocks are:
(1) Inland waters of Washington (including Hood Canal, Puget Sound, and
the Strait of Juan de Fuca out to Cape Flattery), (2) outer coast of
Oregon and Washington, and (3) California (Carretta et al., 2007). The
inland waters of Washington stock is the only stock that is expected to
occur within the project area.
The average weight for adult seals is about 180 lb (82 kg) and
males are slightly larger than females. Male harbor seals weigh up to
245 lb (111 kg) and measure approximately 5 ft (1.5 m) in length. The
basic color of harbor seals' coat is gray and mottled but highly
variable, from dark with light color rings or spots to light with dark
markings (NMFS, 2008c).
Status--Estimated population numbers for the inland waters of
Washington, including the Hood Canal, Puget Sound, and the Strait of
Juan de Fuca out to Cape Flattery, are 14,612 individuals (Carretta et
al., 2007). The minimum population is 12,844 individuals. The harbor
seal is the only species of marine mammal that is consistently abundant
and considered resident in the Hood Canal (Jeffries et al., 2003). The
population of harbor seals in Hood Canal is a closed population,
meaning that they do not have much movement outside of Hood Canal
(London, 2006). The abundance of harbor seals in Hood canal has
stabilized, and the population may have reached its carrying capacity
in the mid-1990s with an approximate abundance of 1,000 harbor seals
(Jeffries et al., 2003).
Harbor seals are not considered to be depleted under the MMPA or
listed under the ESA. Human-caused mortality relative to PBR is
unknown, but it is considered to be small relative to the stock size.
Therefore, the Washington Inland Waters stock of harbor seals is not
classified as a strategic stock.
Distribution--Harbor seals are coastal species, rarely found more
than 12 mi (20 km) from shore, and frequently occupy bays, estuaries,
and inlets (Baird 2001). Individual seals have been observed several
miles upstream in coastal rivers. Ideal harbor seal habitat includes
haul-out sites, shelter during the breeding periods, and sufficient
food (Bjorge, 2002). Haul-out areas can include intertidal and subtidal
rock outcrops, sandbars, sandy beaches, peat banks in salt marshes, and
man-made structures such as log booms, docks, and recreational floats
(Wilson, 1978; Prescott, 1982; Schneider and Payne, 1983; Gilber and
Guldager, 1998; Jeffries et al., 2000). Human disturbance can affect
haul-out choice (Harris et al., 2003).
Harbor seals occur throughout Hood Canal and are seen relatively
commonly in the area. They are year-round, non-migratory residents, and
pup (i.e., give birth) in Hood Canal. Surveys in the Hood Canal from
the mid-1970s to 2000 show a fairly stable population between 600-1,200
seals (Jeffries et al., 2003). Harbor seals have been observed swimming
in the waters along NBKB in every month of surveys conducted from 2007-
2010 (Agness and Tannenbaum,
[[Page 79421]]
2009b; Tannenbaum et al., 2009b). On the NBKB waterfront, harbor seals
have not been observed hauling out in the intertidal zone, but have
been observed hauled-out on man-made structures such as the floating
security fence, buoys, barges, marine vessels, and logs (Agness and
Tannebaum, 2009a; Tannenbaum et al., 2009a). The main haul-out
locations for harbor seals in Hood Canal are located on river delta and
tidal exposed areas at Quilcene, Dosewallips, Duckabush, Hamma Hamma,
and Skokomish River mouths (see Figure 4-1 of the Navy's application),
with the closest haul-out area to the project area being ten miles (16
km) southwest of NBKB at Dosewallips River mouth, outside the potential
area of effect for this project (London, 2006).
Behavior and Ecology--Harbor seals are typically seen in small
groups resting on tidal reefs, boulders, mudflats, man-made structures,
and sandbars. Harbor seals are opportunistic feeders that adjust their
patterns to take advantage of locally and seasonally abundant prey
(Payne and Selzer 1989; Baird 2001; Bj[oslash]rge 2002). The harbor
seal diet consists of fish and invertebrates (Bigg, 1981; Roffe and
Mate, 1984; Orr et al., 2004). Although harbor seals in the Pacific
Northwest are common in inshore and estuarine waters, they primarily
feed at sea (Orr et al., 2004) during high tide. Researchers have found
that they complete both shallow and deep dives during hunting depending
on the availability of prey (Tollit et al., 1997). Their diet in Puget
Sound consists of many of the prey resources that are present in the
nearshore and deeper waters of NBKB, including hake, herring and adult
and out-migrating juvenile salmonids. Harbor seals in Hood Canal are
known to feed on returning adult salmon, including ESA-threatened
summer-run chum (Oncorhynchus keta). Over a 5-year study of harbor seal
predation in the Hood Canal, the average percent escapement of summer-
run chum consumed was eight percent (London, 2006).
Harbor seals mate at sea and females give birth during the spring
and summer, although the pupping season varies by latitude. In coastal
and inland regions of Washington, pups are born from April through
January. Pups are generally born earlier in the coastal areas and later
in the Puget Sound/Hood Canal region (Calambokidis and Jeffries, 1991;
Jeffries et al., 2000). Suckling harbor seal pups spend as much as
forty percent of their time in the water (Bowen et al., 1999).
Acoustics--In air, harbor seal males produce a variety of low-
frequency (less than 4 kHz) vocalizations, including snorts, grunts,
and growls. Male harbor seals produce communication sounds in the
frequency range of 100-1,000 Hz (Richardson et al., 1995). Pups make
individually unique calls for mother recognition that contain multiple
harmonics with main energy below 0.35 kHz (Bigg, 1981; Thomson and
Richardson, 1995). Harbor seals hear nearly as well in air as
underwater and had lower thresholds than California sea lions (Kastak
and Schusterman, 1998). Kastak and Schusterman (1998) reported airborne
low frequency (100 Hz) sound detection thresholds at 65.4 dB re 20
[mu]Pa for harbor seals. In air, they hear frequencies from 0.25-30 kHz
and are most sensitive from 6-16 kHz (Richardson, 1995; Terhune and
Turnbull, 1995; Wolski et al., 2003).
Adult males also produce underwater sounds during the breeding
season that typically range from 0.25-4 kHz (duration range: 0.1 s to
multiple seconds; Hanggi and Schusterman 1994). Hanggi and Schusteman
(1994) found that there is individual variation in the dominant
frequency range of sounds between different males, and Van Parijs et
al. (2003) reported oceanic, regional, population, and site-specific
variation that could be vocal dialects. In water, they hear frequencies
from 1-75 kHz (Southall et al., 2007) and can detect sound levels as
weak as 60-85 dB re 1 [mu]Pa within that band. They are most sensitive
at frequencies below 50 kHz; above 60 kHz sensitivity rapidly
decreases.
Killer Whale
Species Description--Killer whales are members of the Delphinid
family and are the most widely distributed cetacean species in the
world. Killer whales have a distinctive color pattern, with black
dorsal and white ventral portions. They also have a conspicuous white
patch above and behind the eye and a highly variable gray or white
saddle area behind the dorsal fin. The species shows considerable
sexual dimorphism. Adult males develop larger pectoral flippers, dorsal
fins, tail flukes, and girths than females. Male adult killer whales
can reach up to 32 ft (9.8 m) in length and weigh nearly 22,000 lb
(10,000 kg); females reach 28 ft (8.5 m) in length and weigh up to
16,500 lb (7,500 kg).
Based on appearance, feeding habits, vocalizations, social
structure, and distribution and movement patterns there are three types
of populations of killer whales (Wiles, 2004; NMFS, 2005). The three
distinct forms or types of killer whales recognized in the North
Pacific Ocean are: (1) Resident, (2) Transient, and (3) Offshore. The
resident and transient populations have been divided further into
different subpopulations based mainly on genetic analyses and
distribution; not enough is known about the offshore whales to divide
them into subpopulations (Wiles, 2004). Only transient killer whales
are known from the project area.
Transient killer whales occur throughout the eastern North Pacific,
and have primarily been studied in coastal waters. Their geographical
range overlaps that of the resident and offshore killer whales. The
dorsal fin of transient whales tends to be more erect (straighter at
the tip) than those of resident and offshore whales (Ford and Ellis,
1999; Ford et al., 2000). Saddle patch pigmentation of transient killer
whales is restricted to two patterns, and never has the large areas of
black pigmentation intruding into the white of the saddle patch that is
seen in resident and offshore types. Transient type whales are often
found in long-term stable social units that tend to be smaller than
resident social groups (e.g., fewer than ten whales); these social
units do not seem as permanent as matrilines are in resident type
whales. Transient killer whales feed nearly exclusively on marine
mammals (Ford and Ellis, 1999), whereas resident whales primarily eat
fish. Offshore whales are presumed to feed primarily on fish, and have
been documented feeding on sharks.
Within the transient type, association data (Ford et al., 1994;
Ford and Ellis, 1999; Matkin et al., 1999), acoustic data (Saulitis,
1993; Ford and Ellis, 1999) and genetic data (Hoelzel et al., 1998,
2002; Barrett-Lennard, 2000) confirms that three communities of
transient whales exist and represent three discrete populations: (1)
Gulf of Alaska, Aleutian Islands, and Bering Sea transients, (2) AT1
transients (Prince William Sound, AK; listed as depleted under the
MMPA), and (3) West Coast transients. Among the genetically distinct
assemblages of transient killer whales in the northeastern Pacific,
only the West Coast transient stock, which occurs from southern
California to southeastern Alaska, may occur in the project area.
Status--The West Coast transient stock is a trans-boundary stock,
with minimum counts for the population of transient killer whales
coming from various photographic datasets. Combining these counts of
cataloged transient whales gives a minimum number of 354 individuals
for the West Coast transient stock (Allen and Angliss,
[[Page 79422]]
2010). However, the number in Washington waters at any one time is
probably fewer than twenty individuals (Wiles, 2004). The West Coast
transient killer whale stock is not designated as depleted under the
MMPA or listed under the ESA. The estimated annual level of human-
caused mortality and serious injury does not exceed the PBR. Therefore,
the West Coast Transient stock of killer whales is not classified as a
strategic stock. Population trends and status of this stock relative to
its Optimum Sustainable Population (OSP) level are currently unknown.
Distribution--The geographical range of transient killer whales
includes the northeast Pacific, with preference for coastal waters of
southern Alaska and British Columbia (Krahn et al., 2002). Transient
killer whales in the eastern North Pacific spend most of their time
along the outer coast, but visit Hood Canal and the Puget Sound in
search of harbor seals, sea lions, and other prey. Transient occurrence
in inland waters appears to peak during August and September (Morton,
1990; Baird and Dill, 1995; Ford and Ellis, 1999) which is the peak
time for harbor seal pupping, weaning, and post-weaning (Baird and
Dill, 1995). In 2003 and 2005, small groups of transient killer whales
(eleven and six individuals, respectively) visited Hood Canal to feed
on harbor seals and remained in the area for significant periods of
time (59 and 172 days, respectively) between the months of January and
July.
Behavior and Ecology--Transient killer whales show greater
variability in habitat use, with some groups spending most of their
time foraging in shallow waters close to shore while others hunt almost
entirely in open water (Felleman et al., 1991; Baird and Dill, 1995;
Matkin and Saulitis, 1997). Transient killer whales feed on marine
mammals and some seabirds, but apparently no fish (Morton, 1990; Baird
and Dill, 1996; Ford et al., 1998; Ford and Ellis, 1999; Ford et al.,
2005). While present in Hood Canal in 2003 and 2005, transient killer
whales preyed on harbor seals in the subtidal zone of the nearshore
marine and inland marine deeper water habitats (London, 2006). Other
observations of foraging transient killer whales indicate they prefer
to forage on pinnipeds in shallow, protected waters (Heimlich-Boran,
1988; Saulitis et al., 2000). Transient killer whales travel in small,
matrilineal groups, but they typically contain fewer than ten animals
and their social organization generally is more flexible than that of
resident killer whales (Morton, 1990, Ford and Ellis, 1999). These
differences in social organization probably relate to differences in
foraging (Baird and Whitehead, 2000). There is no information on the
reproductive behavior of killer whales in this area.
Acoustics--Killer whales produce a wide variety of clicks and
whistles, but most of their sounds are pulsed, with frequencies ranging
from 0.5-25 kHz (dominant frequency range: 1-6 kHz) (Thomson and
Richardson, 1995; Richardson et al., 1995). Source levels of
echolocation signals range between 195-224 dB re 1 [mu]Pa-m peak-to-
peak (p-p), dominant frequencies range from 20-60 kHz, with durations
of about 0.1 s (Au et al., 2004). Source levels associated with social
sounds have been calculated to range between 131-168 dB re 1 [mu]Pa-m
and vary with vocalization type (Veirs, 2004).
Both behavioral and auditory brainstem response techniques indicate
killer whales can hear in a frequency range of 1-100 kHz and are most
sensitive at 20 kHz. This is one of the lowest maximum-sensitivity
frequencies known among toothed whales (Szymanski et al., 1999).
Dall's Porpoise
Species Description--Dall's porpoises are members of the Phocoenid
(porpoise) family and are common in the North Pacific Ocean. They can
reach a maximum length of just under 8 ft (2.4 m) and weigh up to 480
lb (218 kg). Males are slightly larger and thicker than females, which
reach lengths of just under 7 ft (2.1 m) long. The body of Dall's
porpoises is a very dark gray or black in coloration with variable
contrasting white thoracic panels and white `frosting' on the dorsal
fin and tail that distinguish them from other cetacean species. These
markings and colorations vary with geographic region and life stage,
with adults having more distinct patterns.
Based on NMFS stock assessment reports, Dall's porpoises within the
Pacific U.S. Exclusive Economic Zone are divided into two discrete,
noncontiguous areas: (1) waters off California, Oregon, and Washington,
and (2) Alaskan waters (Carretta et al., 2008). Only individuals from
the CA/OR/WA stock may occur within the project area.
Status--The NMFS population estimate, recently updated in 2010 for
the CA/OR/WA stock, is 42,000 (CV = 0.33) which is based on vessel line
transect surveys by Barlow (2010) and Forney (2007). The minimum
population is considered to be 32,106. Additional numbers of Dall's
porpoises occur in the inland waters of Washington, but the most recent
estimate was obtained in 1996 (900 animals; CV = 0.40; Calambokidis et
al., 1997) and is not included in the overall estimate of abundance for
this stock due to the need for more up-to-date information. Dall's
porpoise are not listed as depleted under the MMPA or listed under the
ESA. The average annual human-caused mortality is estimated to be less
than the PBR, and therefore the stock is not classified as a strategic
stock under the MMPA. The status of Dall's porpoises in California,
Oregon and Washington relative to OSP is not known, and there are
insufficient data to evaluate potential trends in abundance.
Distribution--The Dall's porpoise is found from northern Baja
California, Mexico, north to the northern Bering Sea and south to
southern Japan (Jefferson et al., 1993). The species is only common
between 32-62 [deg]N in the eastern North Pacific (Morejohn, 1979;
Houck and Jefferson, 1999). North-south movements in California,
Oregon, and Washington have been suggested. Dall's porpoises shift
their distribution southward during cooler-water periods (Forney and
Barlow, 1998). Norris and Prescott (1961) reported finding Dall's
porpoises in southern California waters only in the winter, generally
when the water temperature was less than 15 [deg]C (59[emsp14][deg]F).
Seasonal movements have also been noted off Oregon and Washington,
where higher densities of Dall's porpoises were sighted offshore in
winter and spring and inshore in summer and fall (Green et al., 1992).
In Washington, they are most abundant in offshore waters. They are
year-round residents in Washington (Green et al., 1992), but their
distribution is highly variable between years, likely due to changes in
oceanographic conditions (Forney and Barlow, 1998). Dall's porpoises
are observed throughout the year in the Puget Sound north of Seattle
(Osborne et al., 1998) and are seen occasionally in southern Puget
Sound. Dall's porpoises may also occasionally occur in Hood Canal
(Jeffries 2006, personal communication). Nearshore habitats used by
Dall's porpoises could include the marine habitats found in the inland
marine waters of the Hood Canal. A Dall's porpoise was observed in the
deeper water at NBKB in summer 2008 (Tannenbaum et al., 2009a).
Behavior and Ecology--Dall's porpoises can be opportunistic feeders
but primarily consume schooling forage fish. They are known to eat
squid, crustaceans, and fishes such as blackbelly eelpout (Lycodopsis
pacifica), herring, pollock, hake, and Pacific sandlance (Ammodytes
hexapterus) (Walker et al., 1998).
[[Page 79423]]
Groups of Dall's porpoises generally include fewer than ten individuals
and are fluid, probably aggregating for feeding (Jefferson, 1990, 1991;
Houck and Jefferson, 1999). Dall's porpoises become sexually mature at
three and a half to eight years of age (Houck and Jefferson, 1999) and
give birth to a single calf after ten to twelve months. Breeding and
calving typically occurs in the spring and summer (Angell and Balcomb,
1982). In the North Pacific, there is a strong summer calving peak from
early June through August (Ferrero and Walker, 1999), and a smaller
peak in March (Jefferson, 1989). Resident Dall's porpoises breed in
Puget Sound from August to September.
Acoustics--Only short duration pulsed sounds have been recorded for
Dall's porpoises (Houck and Jefferson, 1999); this species apparently
does not whistle often (Richardson et al., 1995). Dall's porpoises
produce short duration (50-1,500 [mu]s), high-frequency, narrow band
clicks, with peak energies between 120-160 kHz (Jefferson, 1988). There
is no published data on the hearing abilities of this species.
Harbor Porpoise
Species Description--Harbor porpoises belong to the Phocoenid
(porpoise) family and are found extensively along the Pacific U.S.
coast. Harbor porpoises are small, with males reaching average lengths
of approximately 5 ft (1.5 m); Females are slightly larger with an
average length of 5.5 ft (1.7 m). The average adult harbor porpoise
weighs between 135-170 lb (61-77 kg). Harbor porpoises have a dark grey
coloration on their backs, with their belly and throats white. They
have a dark grey chin patch and intermediate shades of grey along their
sides.
Recent preliminary genetic analyses of samples ranging from
Monterey, CA to Vancouver Island, BC indicate that there is small-scale
subdivision within the U.S. portion of this range (Chivers et al.,
2002). Although geographic structure exists along an almost continuous
distribution of harbor porpoises from California to Alaska, stock
boundaries are difficult to draw because any rigid line is generally
arbitrary from a biological perspective. Nevertheless, based on genetic
data and density discontinuities identified from aerial surveys, NMFS
identifies eight stocks in the Northeast Pacific Ocean. Pacific coast
harbor porpoise stocks include: (1) Monterey Bay, (2) San Francisco-
Russian River, (3) northern California/southern Oregon, (4) Oregon/
Washington coastal, (5) inland Washington, (6) Southeast Alaska, (7)
Gulf of Alaska, and (8) Bering Sea. Only individuals from the
Washington Inland Waters stock may occur in the project area.
Status--Aerial surveys of the inland waters of Washington and
southern British Columbia were conducted during August of 2002 and 2003
(J. Laake, unpubl. data). These aerial surveys included the Strait of
Juan de Fuca, San Juan Islands, Gulf Islands, and Strait of Georgia,
which includes waters inhabited by the Washington Inland Waters stock
of harbor porpoises as well as harbor porpoises from British Columbia.
An average of the 2002 and 2003 estimates of abundance in U.S. waters
resulted in an uncorrected abundance of 3,123 (CV= 0.10) harbor
porpoises in Washington inland waters (J. Laake, unpubl. data). When
corrected for availability and perception bias, the estimated abundance
for the Washington Inland Waters stock of harbor porpoise is 10,682 (CV
= 0.38) animals (Carretta et al., 2008). The minimum population
estimate is 7,841. Harbor porpoise are not listed as depleted under the
MMPA or listed under the ESA. Based on currently available data, the
total level of human-caused mortality is not known to exceed the PBR.
Therefore, the Washington Inland Waters harbor porpoise stock is not
classified as strategic. The status of this stock relative to its OSP
level and population trends is unknown. Although long-term harbor
porpoise sightings in southern Puget Sound have declined since the
1940s, sightings have increased in Puget Sound and northern Hood Canal
in recent years and are now considered to regularly occur year-round in
these waters (Calambokidis 2010, pers. comm). This may represent a
return to historical conditions, when harbor porpoises were considered
one of the most common cetaceans in Puget Sound (Scheffer and Slipp
1948).
Distribution--Harbor porpoises are generally found in cool
temperate to subarctic waters over the continental shelf in both the
North Atlantic and North Pacific (Read 1999). This species is seldom
found in waters warmer than 17 [deg]C (63[emsp14][deg]F; Read 1999) or
south of Point Conception (Hubbs 1960; Barlow and Hanan 1995). Harbor
porpoises can be found year-round primarily in the shallow coastal
waters of harbors, bays, and river mouths (Green et al., 1992). Along
the Pacific coast, harbor porpoises occur from Monterey Bay, California
to the Aleutian Islands and west to Japan (Reeves et al., 2002). Harbor
porpoises are known to occur in Puget Sound year round (Osmek et al.,
1996, 1998; Carretta et al., 2007), and harbor porpoise observations in
northern Hood Canal have increased in recent years (Calambokidis 2010,
pers. comm.). Prior to recent construction projects conducted by the
Navy at NBKB, harbor porpoises were considered as likely occurring only
occasionally in the project area. A single harbor porpoise had been
sighted in deeper water at NBKB during 2010 field observations (SAIC,
2010). However, while implementing monitoring plans for work conducted
from July-October, 2011, the Navy recorded multiple sightings of harbor
porpoise in the deeper waters of the project area. Following these
sightings, the Navy conducted dedicated line transect surveys,
recording multiple additional sightings of harbor porpoise, and have
revised local density estimates accordingly. The current density
estimates are based upon a small sample size of transect surveys, and
may be further revised as more information becomes available from
ongoing Navy survey efforts.
Behavior and Ecology--Harbor porpoises are non-social animals
usually seen in small groups of two to five animals. Little is known
about their social behavior. Harbor porpoises can be opportunistic
foragers but primarily consume schooling forage fish (Osmek et al.,
1996; Bowen and Siniff, 1999; Reeves et al., 2002). Along the coast of
Washington, harbor porpoises primarily feed on herring, market squid
(Loligo opalescens) and eulachon (Thaleichthys pacificus) (Gearin et
al., 1994). Females reach sexual maturity at three to four years of age
and may give birth every year for several years in a row. Calves are
born in late spring (Read, 1990; Read and Hohn, 1995). Dall's and
harbor porpoises appear to hybridize relatively frequently in the Puget
Sound area (Willis et al., 2004).
Acoustics--Harbor porpoise vocalizations include clicks and pulses
(Ketten, 1998), as well as whistle-like signals (Verboom and Kastelein
1995). The dominant frequency range is 110-150 kHz, with source levels
of 135-177 dB re 1 [mu]Pa-m (Ketten 1998). Echolocation signals include
one or two low-frequency components in the 1.4-2.5 kHz range (Verboom
and Kastelein 1995).
A behavioral audiogram of a harbor porpoise indicated the range of
best sensitivity is 8-32 kHz at levels between 45-50 dB re 1 [mu]Pa-m
(Andersen 1970); however, auditory-evoked potential studies showed a
much higher frequency of approximately 125-130 kHz (Bibikov 1992). The
auditory-evoked potential method suggests that the harbor porpoise
actually has two frequency ranges of best sensitivity. More recent
psycho-acoustic studies
[[Page 79424]]
found the range of best hearing to be 16-140 kHz, with a reduced
sensitivity around 64 kHz (Kastelein et al., 2002). Maximum sensitivity
occurs between 100-140 kHz (Kastelein et al., 2002).
Potential Effects of the Specified Activity on Marine Mammals
NMFS has determined that pile driving, as outlined in the project
description, has the potential to result in behavioral harassment of
Steller sea lions, California sea lions, harbor seals, harbor
porpoises, Dall's porpoises, and killer whales that may be swimming,
foraging, or resting in the project vicinity while pile driving is
being conducted. Pile driving could potentially harass those pinnipeds
that are in the water close to the project site, whether their heads
are above or below the surface.
Marine Mammal Hearing
The primary effect on marine mammals anticipated from the specified
activities would result from exposure of animals to underwater sound.
Exposure to sound can affect marine mammal hearing. When considering
the influence of various kinds of sound on the marine environment, it
is necessary to understand that different kinds of marine life are
sensitive to different frequencies of sound. Based on available
behavioral data, audiograms derived using auditory evoked potential
techniques, anatomical modeling, and other data, Southall et al. (2007)
designate functional hearing groups for marine mammals and estimate the
lower and upper frequencies of functional hearing of the groups. The
functional groups and the associated frequencies are indicated below
(though animals are less sensitive to sounds at the outer edge of their
functional range and most sensitive to sounds of frequencies within a
smaller range somewhere in the middle of their functional hearing
range):
Low frequency cetaceans (thirteen species of mysticetes):
Functional hearing is estimated to occur between approximately 7 Hz and
22 kHz;
Mid-frequency cetaceans (32 species of dolphins, six
species of larger toothed whales, and nineteen species of beaked and
bottlenose whales): Functional hearing is estimated to occur between
approximately 150 Hz and 160 kHz;
High frequency cetaceans (six species of true porpoises,
four species of river dolphins, two members of the genus Kogia, and
four dolphin species of the genus 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 and 75 kHz, with the greatest
sensitivity between approximately 700 Hz and 20 kHz.
As mentioned previously in this document, three pinniped and three
cetacean species are likely to occur in the proposed project area. Of
the three cetacean species likely to occur in the project area, two are
classified as high frequency cetaceans (Dall's and harbor porpoises)
and one is classified as a mid-frequency cetacean (killer whales)
(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 would be
expected to 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; O'Keefe and Young, 1984; DoN, 2001b).
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, either permanently or
temporarily. However, this depends on both 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 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
[[Page 79425]]
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. 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 (Tursiops truncatus) 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.
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 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.
Measured source levels from impact pile driving can be as high as
214 dB re 1 [mu]Pa at 1 m (3.3 ft). 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
[[Page 79426]]
that could cause TTS or the onset of PTS.
Disturbance Reactions
Disturbance includes a variety of effects, including subtle changes
in behavior, more conspicuous changes in activities, and displacement.
Reactions to sound, if any, depend on species, state of maturity,
experience, current activity, reproductive state, time of day, and many
other factors (Richardson et al., 1995; Wartzok et al., 2004; Southall
et al., 2007; Weilgart, 2007). Behavioral responses to sound are highly
variable and context specific. For each potential behavioral change,
the magnitude of the change ultimately determines the severity of the
response. A number of factors may influence an animal's response to
sound, including its previous experience, its auditory sensitivity, its
biological and social status (including age and sex), and its
behavioral state and activity at the time of exposure.
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., 2003/04). 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., 2003/04).
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; Caltrans, 2001, 2006; see also Gordon et al., 2004;
Wartzok et al., 2003/04; Nowacek et al., 2007). Responses to continuous
sound, 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). Pinnipeds
may increase their haul-out time, possibly to avoid in-water
disturbance (Caltrans 2001, 2006). 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, the
sum of sound from the proposed activities is confined in an area of
inland waters (Hood Canal) that is bounded by landmass; therefore, the
[[Page 79427]]
sound generated is not expected to contribute 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 Steller sea lions,
California sea lions, harbor seals, transient killer whales, harbor
porpoises, and Dall's porpoises. Impact pile driving activity is
relatively short-term, with rapid pulses occurring for approximately
fifteen minutes per pile. 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
negligible. Vibratory pile driving is also relatively short-term, with
rapid oscillations occurring for approximately one and a half hours per
pile. 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 a negligible impact 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.
Airborne Sound Effects
Marine mammals that occur in the project area could be exposed to
airborne sounds associated with pile driving that have the potential to
cause harassment, depending on their distance from pile driving
activities. Airborne pile driving sound would have less impact on
cetaceans than pinnipeds because sound from atmospheric sources does
not transmit well underwater (Richardson et al., 1995); thus, airborne
sound would only be an issue for hauled-out pinnipeds in the project
area. Most likely, airborne sound would cause behavioral responses
similar to those discussed above in relation to underwater sound. For
instance, anthropogenic sound could cause hauled-out pinnipeds to
exhibit changes in their normal behavior, such as reduction in
vocalizations, or cause them to temporarily abandon their habitat and
move further from the source. Studies by Blackwell et al. (2004) and
Moulton et al. (2005) indicate a tolerance or lack of response to
unweighted airborne sounds as high as 112 dB peak and 96 dB rms.
Anticipated Effects on Habitat
The proposed activities at NBKB would not result in permanent
impacts to habitats used directly by marine mammals, such as haul-out
sites, but may have potential short-term impacts to food sources such
as forage fish and salmonids. There are no rookeries or major haul-out
sites within 10 km (6.2 mi), foraging hotspots, or other ocean bottom
structure of significant biological importance to marine mammals that
may be 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
NBKB 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 would 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) 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 continuous
sounds) on fish, although several are based on studies in support of
large, multiyear bridge construction projects (Scholik and Yan, 2001,
2002; Govoni et al., 2003; Hawkins, 2005; Hastings, 1990, 2007; Popper
et al., 2006; 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 (Chapman and
Hawkins, 1969; Pearson et al., 1992; Skalski et al., 1992). SPLs of
sufficient strength have been known to cause injury to fish and fish
mortality (Caltrans, 2001; Longmuir and Lively, 2001). 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 wharf
construction project. However, adverse impacts may occur to a few
species of rockfish (bocaccio [Sebastes paucispinis], yelloweye [S.
ruberrimus] and canary [S. pinniger] rockfish) and salmon (chinook
[Oncorhynchus tshawytscha] and summer run chum) which may still be
present in the project area despite operating in a reduced work window
in an attempt to avoid important fish spawning time periods. Impacts to
these species could result from potential impacts to their eggs and
larvae.
Pile Driving Effects on Potential Foraging Habitat
In addition, the area likely impacted by the wharf construction
project is relatively small compared to the available habitat in the
Hood Canal. 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 Hood Canal and 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.
Proposed Mitigation
In order to issue an incidental take authorization (ITA) under
Section 101(a)(5)(D) of the MMPA, NMFS must, where applicable, 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).
The modeling results for zones of influence (ZOIs; see ``Estimated
Take by
[[Page 79428]]
Incidental Harassment'') were used to develop mitigation measures for
pile driving activities at NBKB. The ZOIs effectively represent the
mitigation zone that would be established around each pile to prevent
Level A harassment to marine mammals. While the ZOIs vary between the
different diameter piles and types of installation methods, the Navy is
proposing to establish mitigation zones for the maximum zone of
influence for all pile driving conducted in support of the wharf
construction project. In addition to the measures described later in
this section, the Navy would employ the following standard mitigation
measures:
(a) Conduct briefings between construction supervisors and crews,
marine mammal monitoring team, acoustical 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.
(b) Comply with applicable equipment sound standards of the U.S.
Environmental Protection Agency and ensure that all construction
equipment has sound control devices no less effective than those
provided on the original equipment.
(c) For in-water heavy machinery work other than pile driving
(using, e.g., standard barges, tug boats, barge-mounted excavators, or
clamshell equipment used to place or remove material), if a marine
mammal comes within 10 m (33 ft), operations shall cease and vessels
shall reduce speed to the minimum level required to maintain steerage
and safe working conditions. This type of work could include the
following activities: (1) Movement of the barge to the pile location;
(2) positioning of the pile on the substrate via a crane (i.e.,
stabbing the pile); (3) removal of the pile from the water column/
substrate via a crane (i.e., deadpull); or (4) the placement of sound
attenuation devices around the piles. For these activities, monitoring
would take place from 15 minutes prior to initiation until the action
is complete.
Shutdown and Buffer Zone
The following measures would apply to the Navy's mitigation through
shutdown and buffer zones:
(a) The Navy would implement a minimum shutdown zone of 25 m (82
ft) radius for cetaceans and 10 m for pinnipeds around all pile driving
activity. Shutdown zones typically include all areas where the
underwater SPLs are anticipated to equal or exceed the Level A (injury)
harassment criteria for marine mammals (180-dB isopleth for cetaceans;
190-dB isopleth for pinnipeds). In this case, pile driving sounds are
expected to attenuate below 180 dB at distances of 22 m (72 ft) or less
and below 190 dB at distances of 5 m (16 ft) or less, but the minimum
shutdown zones are intended to further avoid the risk of direct
interaction between marine mammals and the equipment.
(b) The calculated zone encompassing the full 120-dB buffer zone
for vibratory pile driving (an effective area of 41.4 km\2\ when
attenuation due to landmasses is accounted for) is so large as to make
monitoring impracticable. As described previously, the buffer zone
corresponding to the 160-dB harassment criterion for impact pile
driving would always be subsumed by the larger zone associated with
concurrently operating vibratory pile drivers. In order to conduct
monitoring additional to the monitoring conducted in support of the
shutdown zones, the Navy would establish an observation position within
the Waterfront Restricted Area, maximally distant from the pile driving
operations. Any marine mammal observations would be relayed to the
observers monitoring the shutdown zones and would be recorded as Level
B takes. The additional position would be able to monitor an effective
area of at least 500 m distance from the pile driving activity, and any
sighted animals would be recorded as takes. However, with such a large
action area, it is impossible to guarantee that all animals would be
observed or to make comprehensive observations of fine-scale behavioral
reactions to sound.
(c) The shutdown and buffer zones would be monitored throughout the
time required to drive a pile. If a marine mammal is observed within
the buffer zone, a take would be recorded and behaviors documented.
However, 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.
(d) All buffer and shutdown zones would initially be based on the
distances from the source that are predicted for each threshold level.
However, in-situ acoustic monitoring would be utilized to determine the
actual distances to these threshold zones, and the size of the shutdown
and buffer zones would be adjusted accordingly based on received SPLs.
Visual Monitoring
Monitoring would be conducted for a minimum 10 m or 25 m shutdown
zone (for pinnipeds and cetaceans, respectively) and an approximate 500
m (1,640 ft) buffer zone surrounding each pile for the presence of
marine mammals before, during, and after pile driving activities. The
buffer zone was set at the largest area practicable for the Navy to
maintain a monitoring presence over the duration of the activity.
Sightings occurring outside this area (within the predicted 41.4 km\2\
buffer zone predicted for the 120-dB isopleths) would still be recorded
and noted as a take, but detailed observations outside this zone would
not be possible, and it would be impossible for the Navy to account for
all individuals occurring in such a zone with any degree of certainty.
Monitoring would take place from 15 minutes prior to initiation through
30 minutes post-completion of pile driving activities.
The following additional measures would apply to visual monitoring:
(a) Monitoring would be conducted by qualified observers. A trained
observer would be placed from the best vantage point(s) practicable
(e.g., from a small boat, the pile driving barge, on shore, or any
other suitable location) to monitor for marine mammals and implement
shut-down or delay procedures when applicable by calling for the shut-
down to the hammer operator.
(b) Prior to the start of pile driving activity, the shut-down zone
would be monitored for 15 minutes to ensure that it is clear of marine
mammals. Pile driving would only commence once observers have declared
the shut-down zone clear of marine mammals; animals would be allowed to
remain in the buffer zone (i.e., must leave of their own volition) and
their behavior would be monitored and documented.
(c) If a marine mammal approaches or enters the shut-down zone
during the course of pile driving operations, pile driving would be
halted and delayed until either the animal has voluntarily left and
been visually confirmed beyond the shut-down zone or 15 minutes have
passed without re-detection of the animal.
Sound Attenuation Devices
Sound attenuation devices would be utilized during all impact pile
driving operations. Impact pile driving is only expected to be required
to proof, or drive the last 10-15 ft (3-4.6 m) of select piles. Past
experience has shown that proofing is rarely required at the project
location. The Navy plans to use a bubble curtain as mitigation for in-
water sound during construction activities. Bubble curtains absorb
sound, attenuate pressure waves, exclude marine life from work areas,
and control the
[[Page 79429]]
migration of debris, sediments and process fluids.
Acoustic Measurements
Acoustic measurements would be used to empirically verify the
proposed shut-down and buffer zones. For further detail regarding the
Navy's acoustic monitoring plan see ``Proposed Monitoring and
Reporting''.
Timing Restrictions
The Navy has set timing restrictions for pile driving activities to
avoid in-water work when ESA-listed fish populations are most likely to
be present. The in-water work window for avoiding negative impacts to
fish species is July 16-February 15. The initial months (July to
September) of the timing window overlap with times when Steller sea
lions are not expected to be present within the project area.
Soft Start
The use of a soft-start procedure is believed to provide additional
protection to marine mammals by warning, or providing marine mammals a
chance to leave the area prior to the hammer operating at full
capacity. The wharf construction project would utilize soft-start
techniques (ramp-up and dry fire) for impact and vibratory pile
driving. The soft-start requires contractors to initiate sound from
vibratory hammers for fifteen seconds at reduced energy followed by a
30-second waiting period. This procedure would be repeated two
additional times. For impact driving, contractors would be required to
provide an initial set of three strikes from the impact hammer at forty
percent energy, followed by a 30-second waiting period, then two
subsequent three strike sets.
Daylight Construction
Impact pile driving during the first half of the in-water work
window (July 16 to September 15) would only occur between 2 hours after
sunrise and 2 hours before sunset to protect breeding marbled
murrelets. Vibratory pile driving and other construction activities
occurring in the water between July 16 and September 15 could occur
during daylight hours (sunrise to sunset). Between September 16 and
February 15, construction activities occurring in the water would occur
during daylight hours (sunrise to sunset).
Mitigation Effectiveness
It should be recognized that although marine mammals would be
protected from Level A harassment by the utilization of a bubble
curtain and protected species observers (PSOs) monitoring the near-
field injury zones, mitigation may not be 100 percent effective at all
times in locating marine mammals in the buffer zone. The efficacy of
visual detection depends on several factors including the observer's
ability to detect the animal, the environmental conditions (visibility
and sea state), and monitoring platforms.
All observers utilized for mitigation activities would be
experienced biologists with training in marine mammal detection and
behavior. Due to their specialized training the Navy expects that
visual mitigation would be highly effective. Trained observers have
specific knowledge of marine mammal physiology, behavior, and life
history, which may improve their ability to detect individuals or help
determine if observed animals are exhibiting behavioral reactions to
construction activities.
The Puget Sound region, including the Hood Canal, only infrequently
experiences winds with velocities in excess of 25 kn (Morris et al.,
2008). The typically light winds afforded by the surrounding highlands
coupled with the fetch-limited environment of the Hood Canal result in
relatively calm wind and sea conditions throughout most of the year.
The wharf construction project site has a maximum fetch of 8.4 mi (13.5
km) to the north, and 4.2 mi (6.8 km) to the south, resulting in
maximum wave heights of from 2.85-5.1 ft (0.9-1.6 m) (Beaufort Sea
State (BSS) between two and four), even in extreme conditions (30 kt
winds) (CERC, 1984). Visual detection conditions are considered optimal
in BSS conditions of three or less, which align with the conditions
that should be expected for the wharf construction project at NBKB.
Habitat Mitigation
In addition to mitigation measures developed specifically for
marine mammals and described previously, the following compensatory
mitigation measures would be implemented to restore marine fish
habitats, and by extension to indirectly benefit marine mammals in the
project area. These measures were not developed in consultation with
NMFS, but are described here due to their potential benefit for marine
mammals.
Compensatory Mitigation--Compensatory Mitigation is the term given
to projects or plans undertaken to offset unavoidable adverse
environmental impacts which remain after all appropriate and
practicable avoidance and minimization has been achieved. Compensatory
Mitigation involves actions taken to offset unavoidable adverse impacts
to wetlands, streams, and other aquatic resources. For impacts
authorized under a Clean Water Act Section 404 permit, Compensatory
Mitigation is not considered until after all appropriate and
practicable steps have been taken to first avoid and then minimize
adverse impacts to the aquatic ecosystem pursuant to 40 CFR part 230
(i.e., the Clean Water Act Section 404(b)(1) Guidelines). Compensatory
Mitigation is required for permits authorized by the Clean Water Act
Section 404 and other Department of the Army permits.
The Compensatory Mitigation Rule establishes a hierarchy for
Compensatory Mitigation:
Mitigation Banks
In-Lieu Fee (ILF) Programs
Permittee-Responsible Mitigation
A preference for mitigation banks is established at present.
However, there are no established mitigation banks or ILF programs for
Kitsap County or the Hood Canal. Therefore, the Navy`s preference for
providing mitigation and complying with the Compensatory Mitigation
Rule is through the development of an ILF Program. The goal of the ILF
Program is to ensure no net loss of nearshore aquatic resource
functions by in-kind mitigation within Kitsap County and/or Hood Canal.
The Navy would partner with a qualified ILF sponsor that would be
responsible for preparing all documentation associated with
establishment of the program, including a prospectus, a credit/debit
calculation tool or instrument, mitigation plans, and other appropriate
documents. The ILF sponsor would be responsible for performing all of
the required functions of the program including fiscal management;
agreement(s) with entities that will purchase and hold mitigation sites
in conservation status in perpetuity; reporting; and contracting for
the design, construction, and monitoring for specific mitigation
projects.
The Navy anticipates that the Kitsap County Nearshore Habitat
Assessment and Restoration Prioritization Framework could provide an
assessment tool to identify and prioritize mitigation sites. As the ILF
program is developed for Kitsap County and/or Hood Canal, a more
detailed credit/debit calculation tool or instrument would be
developed. This information would be developed and reviewed in
conjunction with the development of the ILF program. Mitigation can
include protection, restoration, enhancement, and/or creation. The
mitigation strategy selected will be based on an assessment of type and
degree of disturbance at the
[[Page 79430]]
landscape, drift cell, and nearshore assessment unit (NAU) scales.
Priority would be given to mitigation strategies that augment
regional and local watershed plans and goals. Such strategies include,
but are not limited to, protection and restoration of critical resource
areas through acquisition or conservation easements, reconnecting
pocket estuaries to tidal fluxes, shoreline rehabilitation, removal of
fish migration barriers, stream restoration, and reforestation of
watersheds and marine/freshwater riparian zones.
Alternative Mitigation Strategies--In the event that an ILF program
is not established in Kitsap County in time for use as mitigation for
the proposed action, other mitigation options will be considered. As an
alternative to pursuing the development of an ILF program for Kitsap
County/and or Hood Canal, the Navy is currently assessing nearshore
permittee responsible mitigation opportunities within the Hood Canal
and Puget Sound with state and local agencies and tribes. The Navy
would identify appropriate in-kind mitigation sufficient in size to
ensure no net loss of aquatic resource functions. Strategies to effect
no net loss could include a combination of restoration, enhancement,
creation, and preservation of nearshore habitats. Potential nearshore
mitigation sites will take into consideration state and local watershed
management plans, property ownership, tribal usual and accustomed
areas, likelihood of success, ability to address multiple functions and
services both among and within aquatic habitat types, and the ability
to affect or improve regional aquatic resource conservation
initiatives. As with the proposed development of an ILF program, these
potential permittee-responsible mitigation projects would also be
reviewed in accordance with the Compensatory Mitigation Rule and would
be submitted for review and approval as part of the application
process. In the event that the Navy selects a permittee-responsible
mitigation as the Compensatory Mitigation strategy, a mitigation plan
would be submitted to the U.S. Army Corps of Engineers.
NMFS has carefully evaluated the applicant's proposed mitigation
measures and considered a range of other measures in the context of
ensuring that NMFS prescribes the means of effecting the least
practicable impact on the affected marine mammal species and stocks and
their habitat. Our evaluation of potential measures included
consideration of the following factors in relation to one another: (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, including
consideration of personnel safety, and practicality of implementation.
Based on our evaluation of the applicant's proposed measures, as
well as other measures considered by NMFS, NMFS has 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 NMFS must, where applicable, 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 would 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.
Acoustic Measurements
Within the first 30 days of pile driving, the Navy would capture a
representative acoustic sample of the major pile driving scenarios
under the modeled conditions (impact hammer and vibratory driving,
smaller [24-in to 36-in] and larger [48-in] piles, plumb and batter
piles). All measurements would be made with the sound attenuation
measures discussed previously in place. These acoustic measurements
would determine the actual distances to the following isopleths: 190 dB
re 1[mu]Pa rms, 180 dB re 1[mu]Pa rms, and 160 dB re 1[mu]Pa rms. The
Navy would also conduct underwater acoustic monitoring for vibratory
pile driving to determine the actual distance to the 120 dB re 1[mu]Pa
rms isopleth for marine mammal behavioral harassment relative to
background levels. Maximum sound pressure levels would also be
documented. Airborne acoustic monitoring would be conducted during
impact and vibratory pile driving to identify the actual distance to
the 90 dB re 20[mu]Pa rms, and 100 dB re 20[mu]Pa rms airborne
isopleths.
At a minimum, the methodology would include:
For underwater recordings, a stationary hydrophone system
with the ability to measure SPLs at mid-water depth and approximately 1
m from the bottom, (taking tidal changes into account) would be placed
at a distance of 10 m from the source. The hydrophone would be deployed
so as to maintain a constant distance of 10 m from the pile.
For airborne recordings, reference recordings would be
attempted at approximately 50 ft (15.2 m) from the source via a
stationary hydrophone. However, other distances may be utilized to
obtain better data if the pile driving signal cannot be isolated
clearly due to other sound sources (e.g., barges or generators).
Each hydrophone (underwater) and microphone (airborne)
would be calibrated prior to the start of the action and would be
checked at the beginning of each day of monitoring activity. Other
hydrophones and microphones would be placed at other distances and/or
depths and moved as necessary to determine the distance to the
thresholds for marine mammals (these include peak, rms, and SEL for
underwater sound, and unweighted for airborne sound).
Unweighted ambient conditions, both airborne and
underwater, would be measured and recorded for 30 to 60 s each hour,
every day for one week during the first 30 days of the construction
period to determine background sound levels. These measurements are
intended to capture ambient background sound during the timeframe of
construction, but in the absence of pile driving sound. Ambient sound
recordings would be edited for anomalous data to provide the best
possible baseline condition for background sound. Recording would be
made in the 10 Hz to 20 kHz range.
Airborne levels would be recorded as an unweighted time
series. The distance to marine mammal airborne sound disturbance
thresholds would be determined.
Sound levels associated with the soft-start techniques (on
a representative subset of piles) would also be measured.
Environmental data would be collected, such as wind speed
and direction, wave height, precipitation, presence and location of
other vessels, and types and locations of in-water construction
activities, as well as other factors that could contribute to
influencing the airborne and underwater sound levels (e.g., aircraft,
boats).
[[Page 79431]]
The construction contractor would supply the Navy and
other relevant monitoring personnel the substrate composition, hammer
model and size, hammer energy settings and any changes to those
settings during hammering of the piles being monitored, depth of the
pile being driven, and blows per foot for the piles monitored.
Post-analysis of underwater sound level signals would
include the average rms value across all pile strikes per pile, the
rise time, average duration of each pile strike, and number of strikes
per pile, as well as a frequency spectrum with mitigation, between 10
and 20,000 Hz, for up to eight successive strikes with similar sound
levels. Rms analyses would be completed for vibratory driving,
including presentation of representative frequency spectra.
Post-analysis of airborne sound would be presented in an
unweighted format, and would include presentation of the average rms
value across all pile strikes per pile, and the average rms value for
vibratory driving. Frequency spectra would be provided from 10 to
20,000 Hz for up to eight successive strikes with similar sound levels,
and would also be provided for representative vibratory driving.
Visual Marine Mammal Observations
The Navy would 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 would be trained
in marine mammal identification and behaviors. NMFS requires that the
observers have no other construction-related tasks while conducting
monitoring.
Methods of Monitoring--The Navy would monitor the shutdown zone and
buffer zone before, during, and after pile driving. There would, at all
times, be at least one observer stationed at an appropriate vantage
point to observe the shutdown zones associated with each operating
hammer. There would also at all times be at least one vessel-based
observer stationed within the WRA. In addition, at least one marine
mammal observer would be stationed on a vessel conducting acoustic
monitoring outside the WRA, for as long as such monitoring is
conducted. The Navy estimates that representative acoustic sampling may
occur in approximately 30 days. Based on NMFS requirements, the Marine
Mammal Monitoring Plan would include the following procedures for pile
driving:
(1) MMOs would be located at the best vantage point(s) in order to
properly see the entire shutdown zone and as much of the buffer zone as
possible. This may require the use of a small boat to monitor certain
areas while also monitoring from one or more land based vantage points.
(2) During all observation periods, observers would use binoculars
and the naked eye to search continuously for marine mammals.
(3) If the shut down or buffer zones are obscured by fog or poor
lighting conditions, pile driving at that location would not be
initiated until that zone is visible.
(4) The shut down and buffer zones around the pile would be
monitored for the presence of marine mammals before, during, and after
any pile driving or removal activity.
Pre-Activity Monitoring--The shutdown and buffer zones would be
monitored for 15 minutes prior to initiating the soft start for pile
driving. If marine mammal(s) are present within the shut down zone
prior to pile driving, or during the soft start, the start of pile
driving would be delayed until the animal(s) leave the shut down zone.
Pile driving would resume only after the PSO has determined, through
sighting or by waiting 15 minutes, that the animal(s) has moved outside
the shutdown zone.
During Activity Monitoring--The shutdown and buffer zones would
also be monitored throughout the time required to drive or remove a
pile. If a marine mammal is observed entering the buffer zone, a take
would be recorded and behaviors documented. However, that pile segment
would be completed without cessation, unless the animal enters or
approaches the shut down zone, at which point all pile driving
activities would be halted. Pile driving can only resume once the
animal has left the shutdown zone of its own volition or has not been
re-sighted for a period of 15 minutes.
Post-Activity Monitoring--Monitoring of the shutdown and buffer
zones would continue for 30 minutes following the completion of pile
driving.
Individuals implementing the monitoring protocol would assess its
effectiveness using an adaptive approach. Monitoring biologists would
use their best professional judgment throughout implementation and
would seek improvements to these methods when deemed appropriate. Any
modifications to protocol would be coordinated between the Navy and
NMFS.
Data Collection
NMFS requires that the PSOs use NMFS-approved sighting forms. In
addition to the following requirements, the Navy would note in their
behavioral observations whether an animal remains in the project area
following a Level B taking (which would not require cessation of
activity). This information would ideally make it possible to determine
whether individuals are taken (within the same day) by one or more
types of pile driving (i.e., impact and vibratory). NMFS requires that,
at a minimum, the following information be collected on the sighting
forms:
(1) Date and time that pile driving begins or ends;
(2) Construction activities occurring during each observation
period;
(3) Weather parameters identified in the acoustic monitoring (e.g.,
percent cover, visibility);
(4) Water conditions (e.g., sea state, tide state);
(5) Species, numbers, and, if possible, sex and age class of marine
mammals;
(6) Marine mammal behavior patterns observed, including bearing and
direction of travel, and if possible, the correlation to SPLs;
(7) Distance from pile driving activities to marine mammals and
distance from the marine mammals to the observation point;
(8) Locations of all marine mammal observations; and
(9) Other human activity in the area.
Reporting
A draft report would be submitted to NMFS within 60 days of the
completion of the first 30 days of acoustic measurements and marine
mammal monitoring. The results would be summarized in graphical form
and include summary statistics and time histories of impact sound
values for each pile. The report would also provide descriptions of any
problems encountered in deploying sound attenuating devices, any
adverse responses to construction activities by marine mammals, and
actions taken to solve these problems. A final report would be prepared
and submitted to NMFS within 30 days following receipt of comments on
the draft report from NMFS. Within 60 days of the end of the in-water
work period, a draft comprehensive report on all marine mammal
monitoring conducted under the proposed IHA would be submitted to NMFS.
The report would include marine mammal observations pre-activity,
during-activity, and post-activity during pile driving days. A final
report would be prepared and submitted to NMFS within 30 days following
receipt of comments on the draft report from NMFS. At a minimum, the
report would include:
(1) Date and time of activity;
[[Page 79432]]
(2) Water and weather conditions (e.g., sea state, tide state,
percent cover, visibility);
(3) Physical characteristics of the bottom substrate where piles
are driven;
(4) Description of the pile driving activity (e.g., size and type
of piles);
(5) A detailed description of the sound attenuation device,
including design specifications;
(6) The impact or vibratory hammer force used to drive or extract
the piles;
(7) A description of the monitoring equipment;
(8) The distance between hydrophone(s) and pile;
(9) The depth of the hydrophone(s);
(10) The depth of water in which the pile was driven;
(11) The depth into the substrate that the pile was driven;
(12) The ranges and means for peak, rms, and SELs for each pile;
(13) The results of the acoustic measurements, including the
frequency spectrum, peak and rms SPLs, and single-strike and cumulative
SEL with and without the attenuation system;
(14) The results of the airborne sound measurements (unweighted
levels);
(15) A description of any observable marine mammal behavior in the
immediate area and, if possible, the correlation to underwater sound
levels occurring at that time;
(16) Actions performed to minimize impacts to marine mammals;
(17) Times when pile driving is stopped due to presence of marine
mammals within shut down zones and time when pile driving resumes;
(18) Results, including the detectability of marine mammals,
species and numbers observed, sighting rates and distances, behavioral
reactions within and outside of shut down zones; and
(19) A refined take estimate based on the number of marine mammals
observed in the shut down and buffer zones.
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 remote. However, as noted earlier, it is
unlikely that injurious or lethal takes would occur even in the absence
of the planned mitigation and monitoring measures.
If a marine mammal responds to an underwater sound 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.
For example, during the past ten years, killer whales have been
observed within the project area twice. On the basis of that
information, an estimated amount of potential takes for killer whales
is presented here. However, while a pod of killer whales could
potentially visit again during the project timeframe, and thus be
taken, it is more likely that they would not.
The proposed project area is not believed to be particularly
important habitat for marine mammals, nor is it considered an area
frequented by marine mammals, although harbor seals are year-round
residents of Hood Canal and sea lions are known to haul-out on
submarines and other man-made objects at the NBKB waterfront (although
typically at a distance of a mile or greater from the project site).
Therefore, behavioral disturbances that could result from anthropogenic
sound associated with the proposed 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 is requesting authorization for the potential taking of
small numbers of Steller sea lions, California sea lions, harbor seals,
transient killer whales, Dall's porpoises, and harbor porpoises in the
Hood Canal that may result from pile driving during construction
activities associated with the wharf construction project described
previously in this document. The takes requested are expected to have
no more than a minor effect on individual animals and no effect at the
population level for these species. Any effects experienced by
individual marine mammals are anticipated to be limited to short-term
disturbance of normal behavior or temporary displacement of animals
near the source of the sound.
Marine Mammal Densities
For all species, the best scientific information available was used
to construct density estimates or estimate local abundance. Of
available information deemed suitable for use, the data that produced
the most conservative (i.e., highest) density or abundance estimate for
each species was used. For harbor seals, this involved published
literature describing harbor seal research conducted in Washington and
Oregon as well as more specific counts conducted in Hood Canal (Huber
et al., 2001; Jeffries et al., 2003). Killer whales are known from two
periods of occurrence (2003 and 2005) and are not known to
preferentially use any specific portion of the Hood Canal. Therefore,
density was calculated as the maximum number of individuals present at
a given time during those occurrences (London, 2006), divided by the
area of Hood Canal. The best information available for the remaining
species in Hood Canal came from surveys conducted by the Navy at the
NBKB waterfront or in the vicinity of the project area. These consist
of three discrete sets of survey effort, and are described here in
greater detail.
Beginning in April 2008, Navy personnel have recorded sightings of
marine mammals occurring at known haul-outs along the NBKB waterfront,
including docked submarines or other structures associated with NBKB
docks and piers and the nearshore pontoons of the floating security
fence. Sightings of marine mammals within the waters adjoining these
locations were also recorded. Sightings were attempted whenever
possible during a typical work week (i.e., Monday through Friday), but
inclement weather, holidays, or security constraints often precluded
surveys. These sightings took place frequently (average fourteen per
month) although without a formal survey protocol. During the surveys,
staff visited each of the above-mentioned locations and recorded
[[Page 79433]]
observations of marine mammals. Surveys were conducted using binoculars
and the naked eye from shoreline locations or the piers/wharves
themselves. Because these surveys consist of opportunistic sighting
data from shore-based observers, largely of hauled-out animals, there
is no associated survey area appropriate for use in calculating a
density from the abundance data. Thus, NMFS has not used these data to
derive a density but rather has used the absolute abundance to estimate
take. Data were compiled for the period from April 2008 through June
2010 for analysis in this proposed IHA, and these data provided the
basis for take estimation for Steller and California sea lions. Other
information, including sightings data from other Navy survey efforts at
NBKB, is available for these two species, but these data provide the
most conservative (i.e., highest) local abundance estimates (and thus
the highest estimates of potential take).
Vessel-based marine wildlife surveys were conducted according to
established survey protocols during July through September 2008 and
November through May 2009-10 (Tannenbaum et al., 2009, 2011). Eighteen
complete surveys of the nearshore area resulted in observations of four
marine mammal species (harbor seal, California sea lion, harbor
porpoise, and Dall's porpoise). These surveys operated along pre-
determined transects parallel to the shoreline from the nearshore out
to approximately 1,800 ft (549 m) from shoreline, at a spacing of 100
yd (91 m), and covered the entire NBKB waterfront (approximately 3.9
km\2\ per survey) at a speed of 5 kn or less. Two observers recorded
sightings of marine mammals both in the water and hauled out, including
date, time, species, number of individuals, age (juvenile, adult),
behavior (swimming, diving, hauled out, avoidance dive), and haul-out
location. Positions of marine mammals were obtained by recording
distance and bearing to the animal with a rangefinder and compass,
noting the concurrent location of the boat with GPS, and, subsequently,
analyzing these data to produce coordinates of the locations of all
animals detected. These surveys produced the information used to
estimate take for Dall's porpoise, as well as for harbor porpoise under
previous Navy actions at NBKB.
Recently, as part of the Test Pile Program, marine mammal
monitoring was conducted on construction days for mitigation purposes.
During those efforts, the Navy observed that harbor porpoises were more
common in deeper waters of Hood Canal than the previously described,
nearshore vessel-based surveys indicated. For that reason, the Navy
conducted vessel-based line transect surveys in Hood Canal on days
where no pile driving activities occurred in order to collect
additional density data for species present in Hood Canal. These
surveys were primarily conducted in September and detected three marine
mammal species (harbor seal, California sea lion, and harbor porpoise),
and included surveys conducted in both the main body of Hood Canal,
near the project area, and baseline surveys conducted for comparison in
Dabob Bay, an area of Hood Canal that is not affected by sound from
Navy actions at the NBKB waterfront (see Figures 2-1 and 4-1 in the
Navy's application). The surveys operated along pre-determined
transects that followed a double saw-tooth pattern to achieve uniform
coverage of the entire NBKB waterfront. The vessel traveled at a speed
of approximately 5 kn when transiting along the transect lines. Two
observers recorded sightings of marine mammals both in the water and
hauled out, including the date, time, species, number of individuals,
and behavior (swimming, diving, etc.). Positions of marine mammals were
obtained by recording the distance and bearing to the animal(s), noting
the concurrent location of the boat with GPS, and subsequently
analyzing these data to produce coordinates of the locations of all
animals detected. Sighting information for harbor porpoises was
corrected for detectability (g(0) = 0.54; Barlow, 1988; Calambokidis et
al., 1993; Carretta et al., 2001). Distance sampling methodologies were
used to estimate densities of animals for the data. Due to the recent
execution of these surveys, not all data have been processed. Due to
the unexpected abundance of harbor porpoises encountered during the
Test Pile Program, data for this species were processed first and are
available for use in this proposed IHA. All other species data may be
included in subsequent environmental compliance documents once all
post-processing is complete, but preliminary analysis indicates that
use of the previously described data would still provide the most
conservative take estimates for the other species.
The cetaceans, as well as the harbor seal, appear to range
throughout Hood Canal; therefore, the analysis in this proposed IHA
assumes that harbor seal, transient killer whale, harbor porpoise, and
Dall's porpoise are uniformly distributed in the project area. The
remaining species that occur in the project area, Steller sea lion and
California sea lion, do not appear to utilize most of Hood Canal. The
sea lions appear to be attracted to the man-made haul-out opportunities
along the NBKB waterfront while dispersing for foraging opportunities
elsewhere in Hood Canal. California sea lions were not reported during
aerial surveys of Hood Canal (Jeffries et al., 2000), and Steller sea
lions have only been documented at the NBKB waterfront.
Description of Take Calculation
The take calculations presented here rely on the best data
currently available for marine mammal populations in the Hood Canal, as
discussed in preceding sections. The formula was developed for
calculating take due to pile driving activity and applied to each
group-specific sound impact threshold. The formula is founded on the
following assumptions:
(a) All pilings to be installed would have a sound disturbance
distance equal to that of the piling that causes the greatest sound
disturbance (i.e., the piling furthest from shore);
(b) Mitigation measures (e.g., sound attenuation system) would be
utilized, as discussed previously;
(c) All marine mammal individuals potentially available are assumed
to be present within the relevant area, and thus incidentally taken;
and,
(d) An individual can only be taken once during a 24-h period.
The calculation for marine mammal takes is estimated by:
Take estimate = (n * ZOI) * days of total activity
Where:
n = density estimate used for each species/season
ZOI = sound threshold zone of influence (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 (actual) specified in Table 5 were used to
calculate ZOI around each pile. All impact pile driving take
calculations were based on the estimated threshold ranges using a
bubble curtain with 10 dB attenuation as a mitigation measure (see
``Underwater Sound from Piledriving''). The ZOI impact area took into
consideration the possible affected area of the Hood Canal from the
pile driving site furthest from shore with attenuation due to land
shadowing from bends in the canal. Because of the close
[[Page 79434]]
proximity of some of the piles to the shore, the narrowness of the
canal at the project area, and the maximum fetch, the ZOIs for each
threshold are not necessarily spherical and may be truncated.
For sea lions, as described previously, the surveys offering the
most conservative estimates of abundance do not have a defined survey
area and so are not suitable for deriving a density construct. Instead,
abundance is estimated on the basis of previously described
opportunistic sighting information at the NBKB waterfront, and it is
assumed that the total amount of animals known from NBKB haul-outs
would be `available' to be taken in a given pile driving day. Thus, for
these two species, take is estimated by multiplying abundance by days
of activity.
While pile driving can occur any day throughout the in-water work
window, and the analysis is conducted on a per day basis, only a
fraction of that time is actually spent pile driving. On days when pile
driving occurs, it could take place for thirty minutes, or up to
several hours. For each pile installed, vibratory pile driving is
expected to be no more than one hour. The impact driving portion of the
project is anticipated to take approximately fifteen minutes per pile
(for proofing). Based on the proposed action, the total pile driving
time from vibratory pile driving during installation would be a maximum
of 195 days (approximately the number of days available during the in-
water work window, when considering contractor work schedule). During
installation, there is the potential for the contractor to need to
utilize an impact hammer to proof a select number of piles, although
past repairs on the existing pier have never required the use of an
impact pile driver.
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 other than the use of a sound attenuation
device (i.e., visual monitoring and the use of shutdown zones) were not
quantified within the assessment and successful implementation of this
mitigation is not reflected in exposure estimates. Results from
acoustic impact exposure assessments should be regarded as conservative
estimates.
California Sea Lion
California sea lions are present in Hood Canal during much of the
year with the exception of mid-June through August. California sea
lions occur regularly in the vicinity of the project site from
September through mid-June, as determined by Navy waterfront surveys
conducted from April 2008 through June 2010 (Navy 2010; Table 8). With
regard to the range of this species in Hood Canal and the project area,
it is assumed on the basis of waterfront observations (Agness and
Tannenbaum, 2009; Tannenbaum et al., 2009, 2011) that the opportunity
to haul out on submarines docked at Delta Pier is a primary attractant
for California sea lions in Hood Canal, as they have rarely been
reported, either hauled out or swimming, elsewhere in Hood Canal
(Jeffries 2007, personal communication). Abundance is calculated as the
monthly average of the maximum number observed in a given month, as
opposed to the overall average (Table 8). For example, in the month of
May, the maximum number of animals observed on any one day was 25 in
2008, 33 in 2009, and 17 in 2010, providing a monthly average of the
maximum daily number observed of 25. This provides a conservative
overall daily abundance of 26.2 for the in-water work window, as
compared with an actual per survey abundance of 11.4 during the same
period.
In previous IHAs issued to the Navy for work at NBKB, NMFS has
calculated a density for California sea lions on the basis of the
maximum daily average number of animals for the period of activity and
the total project area (defined as 41.4 km\2\). This approach was
determined to be the most appropriate method of deriving a local
density for the species (see, e.g., 76 FR 6406). The method produced a
similar estimate of take as would be produced through the use of
abundance information and days of activity, because the density was
based on the same area as the larger ZOI associated with the 120-dB
harassment zone (i.e., 41.4 km\2\), described previously, but also
allowed for calculation of take estimate for different areas, as would
be encompassed by the 160-dB underwater harassment zone associated with
impact driving or harassment zones associated with airborne sound.
However, because the vibratory and impact pile drivers would be
operating simultaneously under the currently proposed action, the 160-
dB harassment zone associated with the impact driver would be at all
times subsumed by the 120-dB harassment zone associated with the
vibratory driver. In addition, because California sea lions are known
to haul-out only in the vicinity of Delta Pier, over one mile south of
the project area, they would not be subject to airborne sound that
would constitute harassment (i.e., within approximately 350 m of an
impact-driven pile). As such, NMFS has determined that it is
appropriate to discard the previously used density construct in favor
of simple abundance. This methodology conservatively uses the maximum
abundance (rather than mean) and assumes that all individuals would be
taken on any given day of activity. NMFS feels that this provides a
conservative estimate of the number of individuals that may be
incidentally taken by the Navy's proposed action while avoiding the
need to construct a density estimate from survey data with no defined
survey area. As described previously, sighting information from other
Navy survey effort that is more appropriate for estimating density
(i.e., with defined survey area) would produce a less conservative
(i.e., lower) estimate of take.
Table 8--California Sea Lion Sighting Information From NBKB, April 2008-June 2010
----------------------------------------------------------------------------------------------------------------
Number of
Month Number of surveys with Frequency of Abundance \2\
surveys animals present presence \1\
----------------------------------------------------------------------------------------------------------------
January........................... 25 15 0.60 24.0
February.......................... 28 24 0.86 31.0
March............................. 28 26 0.93 38.5
April............................. 38 27 0.71 36.3
May............................... 44 34 0.77 25.0
June.............................. 44 7 0.16 5.3
July.............................. 31 0 0 0
August............................ 29 1 0.03 0.5
September......................... 26 9 0.35 22.0
[[Page 79435]]
October........................... 26 22 0.85 45.5
November.......................... 22 22 1 54.0
December.......................... 24 14 0.58 32.5
-----------------------------------------------------------------------------
Total or average (in-water 211 107 0.53 26.2
work season only)............
----------------------------------------------------------------------------------------------------------------
Totals (number of surveys) and averages (frequency and abundance) presented for in-water work season (July-
February) only. Information from March-June presented for reference.
\1\ Frequency is the number of surveys with California sea lions present/number of surveys conducted.
\2\ Abundance is calculated as the monthly average of the maximum daily number observed in a given month.
The largest observed number of California sea lions hauled out
along the NBKB waterfront was 58 in a November survey. During the in-
water construction period (mid-July to mid-February) the largest daily
attendance average for each month ranged from 24 individuals to 54
individuals. The likelihood of California sea lions being present at
NBKB is greatest from October through May, when the frequency of
attendance in surveys was at least 0.58. Attendance along the NBKB
waterfront in November surveys (2008-09) was 100 percent. Additionally,
five navigational buoys near the entrance to Hood Canal were documented
as potential haul-outs, each capable of supporting three adult
California sea lions (Jeffries et al., 2000). Breeding rookeries are in
California; therefore, pups are not expected to be present in Hood
Canal (NMFS 2008b). Female California sea lions are rarely observed
north of the California/Oregon border; therefore, only adult and sub-
adult males are expected to be exposed to project impacts. Table 10
depicts the estimated number of behavioral harassments.
Steller Sea Lion
Steller sea lions were first documented at the NBKB waterfront in
November 2008, while hauled out on submarines at Delta Pier
(Bhuthimethee, 2008, pers. comm.; Navy, 2010) and have been
periodically observed since that time. Based on waterfront
observations, Steller sea lions appear to use available haul-outs
(typically in the vicinity of Delta Pier, approximately one mile south
of the project area) and habitat similarly to California sea lions,
although in lesser numbers. On occasions when Steller sea lions are
observed, they typically occur in mixed groups with California sea
lions also present, allowing observers to confirm their identifications
based on discrepancies in size and other physical characteristics.
Vessel-based survey effort in NBKB nearshore waters have not
detected any Steller sea lions (Agness and Tannenbaum, 2009; Tannenbaum
et al., 2009, 2011). Opportunistic sightings data provided by Navy
personnel since April 2008 have continued to document sightings of
Steller sea lions at Delta Pier from November through April (Table 9).
Steller sea lions have only been observed hauled out on submarines
docked at Delta Pier. Delta Pier and other docks at NBKB are not
accessible to pinnipeds due to the height above water, although the
smaller California sea lions and harbor seals are able to haul out on
pontoons that support the floating security barrier. One to two animals
are typically seen hauled out with California sea lions; the maximum
Steller sea lion group size seen at any given time was six individuals
in November 2009.
Table 9--Steller Sea Lion Sighting Information From NBKB, April 2008-June 2010
----------------------------------------------------------------------------------------------------------------
Number of
Month Number of surveys with Frequency of Abundance \2\
surveys animals present presence \1\
----------------------------------------------------------------------------------------------------------------
January........................... 25 4 0.16 1.0
February.......................... 28 1 0.04 0.5
March............................. 28 4 0.14 1.0
April............................. 38 5 0.13 1.3
May............................... 44 0 0 0
June.............................. 44 0 0 0
July.............................. 31 0 0 0
August............................ 29 0 0 0
September......................... 26 0 0 0
October........................... 26 0 0 \3\ 1.3
November.......................... 22 3 0.14 5.0
December.......................... 24 5 0.21 1.5
-----------------------------------------------------------------------------
Total or average (in-water 211 13 0.07 1.2
work season only)............
----------------------------------------------------------------------------------------------------------------
Totals (number of surveys) and averages (frequency and abundance) presented for in-water work season (July-
February) only. Information from March-June presented for reference.
\1\ Frequency is the number of surveys with Steller sea lions present/number of surveys conducted.
\2\ Abundance is calculated as the monthly average of the maximum daily number observed in a given month.
\3\ Abundance updated to include observations made in October 2011 during Navy's Test Pile Program. All other
information reflects only data from April 2008-June 2010.
[[Page 79436]]
Their frequency of occurrence by month has not exceeded 0.21 (in
December 2009), i.e., they were present in only 21 percent of surveys
that month. The time period from November through April coincides with
the time when Steller sea lions are frequently observed in Puget Sound.
Only adult and sub-adult males are likely to be present in the project
area during this time; female Steller sea lions have not been observed
in the project area. Since there are no known breeding rookeries in the
vicinity of the project site, Steller sea lion pups are not expected to
be present. By May, most Steller sea lions have left inland waters and
returned to their rookeries to mate. Although sub-adult individuals
(immature or pre-breeding animals) will occasionally remain in Puget
Sound over the summer, observational data (Table 9) have indicated that
Steller sea lions are present only from November through April and not
during the summer months. However, recent observational data available
from the Navy's Test Pile Program noted the presence of Steller sea
lions at NBKB in October for the first time. Up to four individuals
were sighted either hauled out at the submarines docked at Delta Pier
or swimming in the waters just adjacent to those haul-outs.
Local abundance information, rather than density, was used in
estimating take for Steller sea lions. Please see the discussion
provided previously for California sea lions. Steller sea lions are
known only from haul-outs over one mile from the project area, and
would not be subject to harassment from airborne sound. Table 10
depicts the number of estimated behavioral harassments.
Harbor Seal
Harbor seals are the most abundant marine mammal in Hood Canal,
where they can occur anywhere in Hood Canal waters year-round. The Navy
detected harbor seals during marine mammal boat surveys of the
waterfront area from July to September 2008 (Tannenbaum et al., 2009)
and November to May 2010 (Tannenbaum et al., 2011), as described
previously. Harbor seals were sighted during every survey and were
found in all marine habitats including nearshore waters and deeper
water, and hauled out on manmade objects such as piers and buoys.
During most of the year, all age and sex classes (except newborn pups)
could occur in the project area throughout the period of construction
activity. Since there are no known pupping sites in the vicinity of the
project area, harbor seal neonates are not expected to be present
during pile driving. Otherwise, during most of the year, all age and
sex classes could occur in the project area throughout the period of
construction activity. Harbor seal numbers increase from January
through April and then decrease from May through August as the harbor
seals move to adjacent bays on the outer coast of Washington for the
pupping season. From April through mid-July, female harbor seals haul
out on the outer coast of Washington at pupping sites to give birth.
The main haul-out locations for harbor seals in Hood Canal are located
on river delta and tidal exposed areas at Quilcene, Dosewallips,
Duckabush, Hamma Hamma, and Skokomish River mouths, with the closest
haul-out area to the project area being 10 mi (16 km) southwest of NBKB
at Dosewallips River mouth (London, 2006). Please see Figure 4-1 of the
Navy's application for a map of haul-out locations in relation to the
project area.
Jeffries et al. (2003) conducted aerial surveys of the harbor seal
population in Hood Canal in 1999 for the Washington Department of Fish
and Wildlife and reported 711 harbor seals hauled out. The authors
adjusted this abundance with a correction factor of 1.53 to account for
seals in the water, which were not counted, and estimated that there
were 1,088 harbor seals in Hood Canal. The correction factor (1.53) was
based on the proportion of time seals spend on land versus in the water
over the course of a day, and was derived by dividing one by the
percentage of time harbor seals spent on land. These data came from
tags (VHF transmitters) applied to harbor seals at six areas (Grays
Harbor, Tillamook Bay, Umpqua River, Gertrude Island, Protection/Smith
Islands, and Boundary Bay, BC) within two different harbor seal stocks
(the coastal stock and the inland waters of WA stock) over four survey
years. The Hood Canal population is part of the inland waters stock,
and while not specifically sampled, Jeffries et al. (2003) found the
VHF data to be broadly applicable to the entire stock. The tagging
research in 1991 and 1992 conducted by Huber et al. (2001) and Jeffries
et al. (2003) used the same methods for the 1999 and 2000 survey years.
These surveys indicated that approximately 35 percent of harbor seals
are in the water versus hauled out on a daily basis (Huber et al.,
2001; Jeffries et al., 2003). Exposures were calculated using a density
derived from the number of harbor seals that are present in the water
at any one time (35 percent of 1,088, or approximately 381
individuals), divided by the area of the Hood Canal (291 km\2\ [112
mi\2\]) and the formula presented previously.
NMFS recognizes that over the course of the day, while the
proportion of animals in the water may not vary significantly,
different individuals may enter and exit the water. However, fine-scale
data on harbor seal movements within the project area on time durations
of less than a day are not available. Previous monitoring experience
from Navy actions conducted from July-October 2011 in the same project
area has indicated that this density provides an appropriate estimate
of potential exposures. Data from those monitoring efforts are
currently in post-processing and are not available in report form at
this time. However, the density of harbor seals calculated in this
manner (1.3 animals/km\2\) is corroborated by results of the Navy's
vessel-based marine mammal surveys at NBKB in 2008 and 2009-10, in
which an average of five individual harbor seals per survey was
observed in the 3.9 km\2\ survey area (density = 1.3 animals/km\2\)
(Tannenbaum et al., 2009, 2011).
The Navy's waterfront surveys have found that it is extremely rare
for harbor seals to haul out in the vicinity of the project area,
although it has been known to occur. Therefore, in order to estimate
potential incidental take of harbor seals by airborne sound, NMFS has
considered that the entire in-water density, as described previously,
could potentially be available to be taken by airborne sound. This
calculation, using the density estimate as described above and the
maximum area estimated to be ensonified to 90 dB by airborne sound
(0.41 km\2\), results in a prediction that 0.5 seals could be exposed
per day. When rounded up to the nearest whole number, this gives the
result that up to one seal could haul-out within the 90-dB in-air
harassment zone per day of pile driving. NMFS feels that this is
extremely unlikely, based on past observations of the frequency with
which harbor seals haul-out on the floating security fence near the
project area, but that this is nevertheless an appropriate
precautionary approach. Table 10 depicts the number of estimated
behavioral harassments.
Killer Whales
Transient killer whales are uncommon visitors to Hood Canal.
Transients may be present in the Hood Canal anytime during the year and
traverse as far as the project site. Resident killer whales have not
been observed in Hood Canal, but transient pods (six to eleven
individuals per event) were observed in Hood Canal for
[[Page 79437]]
lengthy periods of time (59-172 days) in 2003 (January-March) and 2005
(February-June), feeding on harbor seals (London 2006).
These whales used the entire expanse of Hood Canal for feeding.
Subsequent aerial surveys suggest that there has not been a sharp
decline in the local seal population from these sustained feeding
events (London 2006). Based on this data, the density for transient
killer whales in the Hood Canal for January to June is 0.038/km\2\
(eleven individuals divided by the area of the Hood Canal [291 km\2\]).
Because the timeframe of known transient killer whale occurrence in
Hood Canal only partially overlaps the construction period (January to
mid-February), the days of total activity (or days of potential
exposure) portion of the formula presented previously is reduced to 45
for killer whales. Table 10 depicts the number of estimated behavioral
harassments.
Dall's Porpoise
Dall's porpoises may be present in the Hood Canal year-round and
could occur as far as the project site. Their use of inland Washington
waters, however, is mostly limited to the Strait of Juan de Fuca. The
Navy conducted vessel-based surveys of the waterfront area in 2008-10
(Tannenbaum et al., 2009, 2011). During one of the surveys a Dall's
porpoise was sighted in August in the deeper waters off Carlson Spit.
In the absence of an abundance estimate for the entire Hood Canal,
a density was derived from the waterfront survey by the number of
individuals seen divided by total number of kilometers of survey effort
(18 surveys with approximately 3.9 km\2\ [1.5 mi\2\] of effort each),
assuming strip transect surveys. In absence of any other survey data
for the Hood Canal, this density is assumed to be throughout the
project area. Exposures were calculated using the formula presented
previously. Table 10 depicts the number of estimated behavioral
harassments.
Harbor Porpoise
Harbor porpoises may be present in the Hood Canal year-round; their
presence had previously been considered rare. During waterfront surveys
of NBKB nearshore waters from 2008-10 only one harbor porpoise had been
seen in 18 surveys of 3.9 km\2\ each. However, during monitoring of
recent Navy actions at NBKB (test pile program and EHW-1 pile
replacement) several sightings indicated that their presence may be
more frequent in deeper waters of Hood Canal than had been believed on
the basis of existing survey data and anecdotal evidence. Subsequently,
the Navy conducted dedicated vessel-based line transect surveys on days
when no pile driving occurred (due to security, weather, etc.),
described previously in this document, with regular observations of
harbor porpoise groups. Sightings in the deeper waters of Hood Canal
ranged up to 11 individuals, with an average of approximately six
animals sighted per survey day (Navy, in prep.).
Sightings of harbor porpoises during these surveys were used to
generate a density for Hood Canal. Based on guidance from other line
transect surveys conducted for harbor porpoises using similar
monitoring parameters (e.g., boat speed, number of observers) (Barlow,
1988; Calambokidis et al., 1993; Caretta et al., 2001), the Navy
determined the effective strip width for the surveys to be one
kilometer, or a perpendicular distance of 500 m from the transect to
the left or right of the vessel. The effective strip width was set at
the distance at which the detection probability for harbor porpoises
was equivalent to one, which assumes that all individuals on a transect
are detected. Only sightings occurring within the effective strip width
were used in the density calculation. By multiplying the trackline
length of the surveys by the effective strip width, the total area
surveyed during the surveys was 259.01 km\2\. Thirty-five individual
harbor porpoises were sighted within this area, resulting in a density
of 0.135 animals per km\2\. To account for availability bias, or the
animals which are unavailable to be detected because they are
submerged, the Navy utilized a g(0) value of 0.54, derived from other
similar line transect surveys (Barlow, 1988; Calambokidis et al., 1993;
Carretta et al., 2001). This resulted in a density of 0.250 harbor
porpoises per km\2\. For comparison, 274.27 km\2\ of trackline survey
effort in nearby Dabob Bay produced a corrected density estimate of
0.203 harbor porpoises per km\2\. Exposures were calculated using the
formula described previously. Table 10 depicts the number of estimated
behavioral harassments.
Potential takes could occur if individuals of these species move
through the area on foraging trips when pile driving is occurring.
Individuals that are taken could exhibit behavioral changes such as
increased swimming speeds, increased surfacing time, or decreased
foraging. Most likely, individuals may move away from the sound source
and be temporarily displaced from the areas of pile driving. Potential
takes by disturbance would likely have a negligible short-term effect
on individuals and not result in population-level impacts.
Table 10--Number of Potential Incidental Takes of Marine Mammals Within Various Acoustic Threshold Zones
--------------------------------------------------------------------------------------------------------------------------------------------------------
Underwater Airborne
---------------------------------------------------------
Vibratory Total proposed
Species Density/Abundance Impact injury disturbance Impact authorized takes
threshold \1\ threshold (120 disturbance
dB) threshold \3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
California sea lion \2\................................. \4\ 26.2 0 5,070 0 5,070
Steller sea lion........................................ \4\1.2 0 195 0 195
Harbor seal............................................. 1.31 0 10,530 195 10,725
Killer whale............................................ 0.038 0 90 N/A 90
Dall's porpoise......................................... 0.014 0 195 N/A 195
Harbor porpoise......................................... 0.250 0 1,950 N/A 1,950
-----------------------------------------------------------------------------------------------
Total............................................... .................. 0 18,330 195 18,225
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Acoustic injury threshold for impact pile driving is 190 dB for pinnipeds and 180 dB for cetaceans.
\2\ The 160-dB acoustic harassment zone associated with impact pile driving would always be subsumed by the 120-dB harassment zone produced by vibratory
driving. Therefore, takes are not calculated separately for the two zones.
\3\ Acoustic disturbance threshold is 100 dB for sea lions and 90 dB for harbor seals. NMFS does not believe that sea lions would be available for
airborne acoustic harassment because they are known to haul-out only at locations well outside the zone in which airborne acoustic harassment could
occur.
[[Page 79438]]
\4\ Figures presented are abundance numbers, not density, and are calculated as the average of average daily maximum numbers per month. Abundance
numbers are rounded to the nearest whole number for take estimation.
Negligible Impact and Small Numbers Analysis and Preliminary
Determination
NMFS has defined ``negligible impact'' in 50 CFR 216.103 as ``* * *
an impact resulting from the specified activity that cannot be
reasonably expected to, and is not reasonably likely to, adversely
affect the species or stock through effects on annual rates of
recruitment or survival.'' In making a negligible impact determination,
NMFS considers a variety of factors, including but not limited to: (1)
The number of anticipated mortalities; (2) the number and nature of
anticipated injuries; (3) the number, nature, intensity, and duration
of Level B harassment; and (4) the context in which the take occurs.
Pile driving activities associated with the wharf construction
project, as outlined previously, have the potential to disturb or
displace marine mammals. Specifically, the proposed activities may
result in take, in the form of Level B harassment (behavioral
disturbance) only, from airborne or underwater sounds generated from
pile driving. No mortality, serious injury, or Level A harassment is
anticipated given the methods of installation and measures designed to
minimize the possibility of injury to marine mammals and Level B
harassment would be reduced to the level of least practicable adverse
impact. Specifically, vibratory hammers, which do not have significant
potential to cause injury to marine mammals due to the relatively low
source levels (less than 190 dB), would be the primary method of
installation. Also, no impact pile driving would occur without the use
of a sound attenuation system (e.g., bubble curtain), and pile driving
would either not start or be halted if marine mammals approach the
shut-down zone (described previously in this document). The pile
driving activities analyzed here are similar to other nearby
construction activities within the Hood Canal, including two recent
projects conducted by the Navy at the same location (test pile project
and EHW-1 pile replacement project) as well as work conducted in 2005
for the Hood Canal Bridge (SR-104) by the Washington Department of
Transportation, which have taken place with no reported injuries or
mortality to marine mammals.
The proposed numbers of authorized take for Steller and California
sea lions and for Dall's porpoises would be considered small relative
to the relevant stocks or populations (each less than two percent) even
if each estimated taking occurred to a new individual--an extremely
unlikely scenario. The proposed numbers of authorized take for harbor
seals, transient killer whales, and harbor porpoises are somewhat
higher relative to the total stocks. However, these numbers represent
the instances of take, not the number of individuals taken. That is, it
is likely that a relatively small subset of Hood Canal harbor seals,
which is itself a small subset of the regional stock, would be harassed
by project activities. While the available information and formula
estimate that as many as 10,725 exposures of harbor seals to stimuli
constituting Level B harassment could occur, that number represents
some portion of the approximately 1,088 harbor seals resident in Hood
Canal (approximately seven percent of the regional stock) that could
potentially be exposed to sound produced by pile driving activities on
multiple days during the project. No rookeries are present in the
project area, there are no haul-outs other than those provided
opportunistically by man-made objects, and the project area is not
known to provide foraging habitat of any special importance. 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 Hood Canal
harbor seals, and thus would not result in any adverse impact to the
stock as a whole. Similarly, for killer whales, the estimated number of
takes represents a single group of eleven whales that could potentially
be exposed to sound on multiple days, if present. In fact, if a group
of transient killer whales was present in the Hood Canal during the
project (which is in itself unlikely, as such groups have appeared only
twice since 2003), such a group would be able to simply leave the
project area and forage elsewhere in Hood Canal or Puget Sound if the
acoustic behavioral harassment caused by the project disturbed the
group to a sufficient degree. However, it is difficult to quantify such
a group's willingness to remain in the presence of behavioral
harassment or, alternatively, to depart the project area. As such, NMFS
proposes to authorize the take presented in Table 10, which represents
the take of a single pod (approximately 11) that might be taken
repeatedly over multiple days if they stayed in the area. The possible
repeated exposure of a small group of individuals to levels associated
with Level B harassment in this area is expected to have a negligible
impact on the stock.
For harbor porpoises, the situation relative to the regional stock
(where estimated take is approximately eighteen percent) is less clear
as little is known about their use of Hood Canal. Sightings information
from opportunistic waterfront surveys as well as designed surveys of
nearshore waters had previously indicated that harbor porpoises rarely
occurred in NBKB waters. In addition, although no systematic survey
work for harbor porpoises has occurred in Hood Canal, anecdotal
evidence and expert opinion received through personal communication had
confirmed that harbor porpoises were expected to occur infrequently and
in low numbers in the project area. Recent Navy surveys, described
previously in this document, have indicated that harbor porpoises are
present in greater numbers than had been believed. It is unclear from
the limited information available what relationship this occurrence,
recorded only during September-October, 2011, may hold to the regional
stock or whether similar usage of Hood Canal may be expected to recur
throughout the project timeframe. Nevertheless, the estimated take of
harbor porpoises is likely an overestimate (as it is based on
information that may not hold true throughout the project timeframe)
and should be considered to present a negligible impact on the stock.
Harbor porpoise sightings to date have occurred only at significant
distance from the project area (both inside and outside of the
predicted 120-dB zone).
NMFS has preliminarily determined that the impact of the previously
described wharf construction project may result, at worst, in a
temporary modification in behavior (Level B harassment) of small
numbers of marine mammals. No mortality or injuries are anticipated as
a result of the specified activity, and none are proposed to be
authorized. Additionally, animals in the area are not expected to incur
hearing impairment (i.e., TTS or PTS) or non-auditory physiological
effects. For pinnipeds, the absence of any major rookeries and only a
few isolated and opportunistic haul-out areas near or adjacent to the
project site means that potential takes by disturbance would
[[Page 79439]]
have an insignificant short-term effect on individuals and would not
result in population-level impacts. Similarly, for cetacean species the
absence of any known regular occurrence adjacent to the project site
means that potential takes by disturbance would have an insignificant
short-term effect on individuals and would not result in population-
level impacts. Due to the nature, degree, and context of behavioral
harassment anticipated, the activity is not expected to impact rates of
recruitment or survival.
For reasons stated previously in this document, the negligible
impact determination is also supported by the likelihood that, given
sufficient ``notice'' through mitigation measures including soft start,
marine mammals are expected to move away from a sound source that is
annoying prior to its becoming potentially injurious, and the
likelihood that marine mammal detection ability by trained observers is
high under the environmental conditions described for Hood Canal,
enabling the implementation of shut-downs to avoid injury, serious
injury, or mortality. As a result, no take by injury or death is
anticipated, and the potential for temporary or permanent hearing
impairment is very low and would be avoided through the incorporation
of the proposed mitigation measures.
While the number of marine mammals potentially incidentally
harassed would depend on the distribution and abundance of marine
mammals in the vicinity of the survey activity, the number of potential
harassment takings is estimated to be small relative to regional stock
or population number, and has been mitigated to the lowest level
practicable through incorporation of the proposed mitigation and
monitoring measures mentioned previously in this document. This
activity is expected to result in a negligible impact on the affected
species or stocks. The Eastern DPS of the Steller sea lion is listed as
threatened under the ESA; no other species for which take authorization
is requested are either ESA-listed or considered depleted under the
MMPA.
Based on the analysis contained herein of the likely effects of the
specified activity on marine mammals and their habitat, and taking into
consideration the implementation of the mitigation and monitoring
measures, NMFS preliminarily finds that the proposed wharf construction
project would result in the incidental take of small numbers of marine
mammal, by Level B harassment only, and that the total taking from the
activity would have a negligible impact on the affected species or
stocks.
Impact on Availability of Affected Species or Stock for Taking for
Subsistence Uses
No tribal subsistence hunts are held in the vicinity of the project
area; thus, temporary behavioral impacts to individual animals would
not affect any subsistence activity. Further, no population or stock
level impacts to marine mammals are anticipated or authorized. As a
result, no impacts to the availability of the species or stock to the
Pacific Northwest treaty tribes are expected as a result of the
proposed activities. Therefore, no relevant subsistence uses of marine
mammals are implicated by this action.
Endangered Species Act (ESA)
There is one ESA-listed marine mammal species with known occurrence
in the project area: The Eastern DPS of the Steller sea lion, listed as
threatened. Because of the potential presence of Steller sea lions, the
Navy engaged in a formal consultation with the NMFS Northwest Regional
Office under Section 7 of the ESA. The Biological Opinion associated
with that consultation concluded that the proposed action is not likely
to jeopardize the continued existence of the Steller sea lion. The
Steller sea lion does not have critical habitat in the action area.
National Environmental Policy Act (NEPA)
The Navy has prepared a preliminary final EIS. NMFS, which is a
cooperating agency in the preparation of that document, will review it
and the public comments received and subsequently either adopt it or
prepare its own NEPA document before making a determination on the
issuance of an IHA. The Navy EIS is available for public review at
www.nbkeis.com.
Proposed Authorization
As a result of these preliminary determinations, NMFS proposes to
authorize the take of marine mammals incidental to the Navy's wharf
construction project, provided the previously mentioned mitigation,
monitoring, and reporting requirements are incorporated.
Dated: December 14, 2011.
James H. Lecky
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2011-32549 Filed 12-20-11; 8:45 am]
BILLING CODE 3510-22-P