Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to a Pile Replacement Project, 6406-6430 [2011-2530]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 76, Number 24 (Friday, February 4, 2011)]
[Notices]
[Pages 6406-6430]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-2530]



[[Page 6406]]

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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XA116


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to a Pile Replacement Project

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

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

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SUMMARY: NMFS has received 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 pile 
replacement 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, five species of marine 
mammals during the specified activity.

DATES: Comments and information must be received no later than March 7, 
2011.

ADDRESSES: Comments on the application should be addressed to Michael 
Payne, Chief, Permits, Conservation and Education Division, Office of 
Protected Resources, National Marine Fisheries Service, 1315 East-West 
Highway, Silver Spring, MD 20910-3225. The mailbox address for 
providing e-mail comments is ITP.Laws@noaa.gov. NMFS is not responsible 
for e-mail comments sent to addresses other than the one provided here. 
Comments sent via e-mail, 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 https://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.
    A 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: https://www.nmfs.noaa.gov/pr/permits/incidental.htm. The Navy has prepared a 
draft Environmental Assessment (EA) titled ``Explosives Handling Wharf 
1 Pile Replacement Project, Naval Base Kitsap Bangor, Silverdale, WA''. 
This associated document, prepared in compliance with the National 
Environmental Policy Act (NEPA), is also available at the same Internet 
address. 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) 713-2289.

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 December 16, 2010 from the Navy for 
the taking of marine mammals incidental to pile driving and removal in 
association with a pile replacement project in the Hood Canal at Naval 
Base Kitsap in Bangor, WA (NBKB). This pile replacement project is 
proposed to occur between July 16, 2011 and July 15, 2013. This IHA 
would cover only the initial year of this project (July 16, 2011-July 
15, 2012), with a subsequent IHA necessary for completion. Pile driving 
and removal activities would occur only within a window from July 16-
October 31, with any required impact driving occurring only from July 
16-September 30. 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. Steller sea lions are present only from fall to late spring 
(November-June), outside of the project's pile driving and removal 
window (July 16-October 31). 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 decades and was 
therefore excluded from further analysis. Only the five species which 
may be present during the project's timeline may be exposed to sound 
pressure levels associated with vibratory and impulsive pile driving, 
or pneumatic chipping, and will be analyzed in detail in this document.
    The Navy proposes to complete necessary repairs and maintenance at 
the Explosive Handling Wharf 1 (EHW-1) facility at NBKB as 
part of a pile replacement project to restore and maintain the 
structural integrity of the wharf and ensure its continued 
functionality to support necessary operational requirements. The EHW-1

[[Page 6407]]

facility, constructed in 1977, has been compromised due to the 
deterioration of the wharf's existing piling sub-structure. Under the 
proposed action, ninety-six 24-in (0.6 m) diameter concrete piles, 
thirty-nine 12-in (0.3 m) diameter steel fender piles, and three 24-in 
diameter steel fender piles will be removed. In addition, a total of 
twenty-eight 30-in (0.8 m) diameter steel pipe piles will be installed 
and filled with concrete on the southwest corner of EHW-1. The proposed 
action will occur over a two year construction period scheduled to 
begin in July 2011, of which the first year would be authorized under 
this IHA. All piles will be driven with a vibratory hammer for their 
initial embedment depths, and select piles will be impact driven for 
their final 10-15 ft (3-4.6 m) for proofing, as necessary. ``Proofing'' 
involves driving a pile the last few feet into the substrate to 
determine the capacity of the pile. The capacity during proofing is 
established by measuring the resistance of the pile to a hammer that 
has a piston with a known weight and stroke (distance the hammer rises 
and falls) so that the energy on top of the pile can be calculated. The 
blow count in ``blows per inch'' is measured to verify resistance, and 
pile compression capacities are calculated using a known formula. Noise 
attenuation measures (i.e., bubble curtain) will be used during all 
impact hammer operations. Hydroacoustic monitoring will be performed to 
assess effectiveness of noise attenuation measures.
    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 24-
30 in (0.6-0.8 m) diameter pile driving and removal 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 2,488 Level B harassments may occur during the 
pile replacement project from underwater sound. No incidents of 
harassment were predicted from airborne sounds associated with pile 
driving. Some assumptions (e.g., marine mammal densities) used to 
estimate the exposures are conservative, and may overestimate the 
potential number of exposures and their severity.

Description of the Specified Activity

    NBKB is located on the Hood Canal approximately twenty miles (32 
km) west of Seattle, Washington (see Figures 1-1 and 1-2 in the Navy's 
application). NBKB provides berthing and support services to Navy 
submarines and other fleet assets. The entirety of NBKB, including the 
land areas and adjacent water areas in the Hood Canal, is restricted 
from general public access. The Navy proposes a pile replacement 
project to maintain the structural integrity of EHW-1 and ensure its 
continued functionality to support operational requirements of the 
TRIDENT submarine program. The proposed actions with the potential to 
cause harassment of marine mammals within the waterways adjacent to 
NBKB, under the MMPA, are vibratory and impulsive pile driving 
operations, and vibratory and pneumatic chipping removal operations, 
associated with the pile replacement project. The proposed activities 
that would be authorized by this IHA will occur between July 16, 2011 
and July 15, 2012. All in-water construction activities within the Hood 
Canal are only permitted during July 16-February 15 in order to protect 
spawning fish populations. The further restriction of in-water work 
window (July 16-October 31) proposed by the Navy avoids the possibility 
of incidental harassment of Steller sea lions. The Eastern Distinct 
Population Segment (DPS) of Steller sea lions, present in the Hood 
Canal outside of this further restriction of the in-water work window, 
is listed as threatened under the ESA. Impact pile driving would be 
further restricted to the period July 16-September 30, per ESA 
consultation with the U.S. Fish and Wildlife Service (USFWS).
    As part of the Navy's sea-based strategic deterrence mission, the 
Navy Strategic Systems Programs directs research, development, 
manufacturing, test, evaluation, and operational support for the 
TRIDENT Fleet Ballistic Missile program. Maintenance and development of 
necessary facilities for handling of explosive materials is part of 
these duties. The proposed action for this IHA request includes the 
removal of the fragmentation barrier, walkway, and 138 steel and 
concrete piles at EHW-1. Of the piles requiring removal, 96 are 24-in 
(0.6 m) diameter hollow pre-cast concrete piles which will be excised 
down to the mud line. An additional three 24-in steel fender piles, and 
thirty-nine 12-in (0.3 m) steel fender piles, will be extracted using a 
vibratory hammer. Also included in the repair work is the installation 
of 28 new 30-in (0.8 m) diameter steel pipe piles, the construction of 
new cast-in-place pile caps (concrete formwork may be located below 
Mean Higher High Water [MHHW]), the installation of the pre-stressed 
superstructure, the installation of five sled-mounted cathodic 
protection (CP) systems, and the installation or re-installation of 
related appurtenances. Sound propagation data will be collected through 
hydroacoustic monitoring during pile installation and removal to 
support environmental analyses for future repair work that may be 
necessary to maintain the EHW-1 facility. The presence of marine 
mammals will also be monitored during pile installation and removal.
    The EHW-1 pile replacement project has been designed to restore the 
structural integrity of the EHW-1 facility which has been compromised 
due to the deterioration of the wharf's existing piling sub-structure. 
Under the proposed action, ninety-six 24-in (0.6 m) diameter concrete 
piles, thirty-nine 12-in (0.3 m) steel fender piles, and three 24-in 
diameter steel fender piles will be removed. In addition, a total of 
twenty-eight 30-in (0.8 m) diameter steel pipe piles will be installed 
and filled with concrete on the southwest corner of EHW-1. The proposed 
action will occur over a two year construction period scheduled to 
begin in July 2011.
    The removal and installation of piles at EHW-1 is broken up into 
three components described in detail below and depicted in Figure 1-3 
of the Navy's application. The first component of this project would 
entail (see Section A on Figure 1-3 pf the Navy's application):
     The removal of one 24-in diameter steel fender pile and 
its associated fender system components at the outboard support. A 
fender pile, typically set beside slips or wharves, guides approaching 
vessels and is driven so as to yield slightly when struck in order to 
lessen the shock of contact. The fender system components attach the 
fender piles to the structure, and are above the water line.
     The installation of sixteen 30-in diameter hollow steel 
pipe piles (approximately 130 ft [40 m] long), with approximately 100 
ft (30 m) of the pile below the Mean Lower Low Water mark.
     The construction of two cast-in-place concrete pile caps. 
The pile caps would be situated on the tops of the steel piles located 
directly beneath the structure (see Figure 1-4 of the Navy's 
application for a diagram) and function as a load transfer mechanism 
between the superstructure and the piles.

[[Page 6408]]

Concrete formwork may be located below MHHW.
     The installation of three sled mounted passive CP systems. 
The passive CP system is a metallic rod or anode that is attached to a 
metal object to protect it from corrosion. The anode is composed of a 
more active metal than that on which it is mounted and is more easily 
oxidized, thus corroding first and acting as a barrier against 
corrosion for the object to which it is attached. This system would be 
banded to the steel piles to prevent metallic surfaces of the wharf 
from corroding due to the saline conditions in Hood Canal.
    The second component of this project would require (see Section B 
in Figure 1-3 of the Navy's application):
     The removal of two 24-in diameter steel fender piles at 
the main wharf and associated fender system components.
     The installation of twelve 30-in diameter hollow steel 
pipe piles (approximately 74-122 ft [23-37 m] long). The embedment 
depth of the piles would range from 30-50 ft (9-15 m).
     The construction of four concrete pile caps.
     The installation of a pre-stressed concrete 
superstructure. The superstructure is the pre-stressed concrete deck of 
the wharf found above, or supported by, the caps or sills, including 
the deck, girders, and stringers.
     The installation of two sled mounted passive CP systems.
     The installation or re-installation of related 
appurtenances, the associated parts of the superstructure that connect 
the superstructure to the piles. These pieces include components such 
as bolts, welded metal hangers and fittings, brackets, etc.
    The final component of this project would be (see Section C on 
Figure 1-3 of the Navy's application):
     The removal of the concrete fragmentation barrier and 
walkway, used to get from the Wharf Apron to the Outboard Support. 
These structures will likely be removed by cutting the concrete into 
sections (potentially three or four in total) using a saw, or other 
equipment, and removed using a crane. The crane will lift the sections 
from the existing piles and place them on a barge.
     The removal of the piles supporting the fragmentation 
barrier including:
    [cir] Thirty-nine 12-in diameter steel fender piles.
    [cir] Ninety-six 24-in diameter hollow pre-cast concrete piles cut 
to the mud line (includes 72 at fragmentation barrier, four at walkway, 
four at Bent 8 outboard support, and eight at Bents 9 and 10).
     Concrete piles would be removed with a pneumatic chipping 
hammer or another tool capable of cutting through concrete. A pneumatic 
chipping hammer is similar to an electric power tool, such as a 
jackhammer, but uses compressed air instead of electricity. The 
pneumatic chipping hammer consists of a steel piston that is 
reciprocated in a steel barrel by compressed air. On its forward stroke 
the piston strikes the end of the chisel. The piston reciprocates at a 
rate such that the chisel edge vibrates against the concrete with 
enough force to fragment or splinter the pile. The concrete debris 
would be captured using debris curtains/sheeting and removed from the 
project area.
    Pile removal and installation would occur between July 16 and 
October 31 during each year of construction, with all impact driving 
further restricted to July 16-September 30. The installation of the 
concrete pile caps and sled mounted passive CP systems is out-of-water 
work, on the tops of the piles themselves or attached to the wharf's 
superstructure. In a precautionary measure, these activities would 
nonetheless be limited to the in-water work window from July 16 to 
February 15--a window established to minimize impacts to fish.
    Vibratory driving would be the preferred method for all pile 
installation, and would be used for removal of all steel piles. During 
pile installation, depending on local site conditions, it may be 
necessary to drive some piles for the final few feet with an impact 
hammer. This technique, known as proofing, may be required due to 
substrate refusal. As a result of consultation with USFWS under the 
ESA, impact pile driving, if required for proofing, will not occur on 
more than five days for the duration of any pile driving window during 
the implementation of the project, and no more than one pile may be 
proofed in a given day. Furthermore, impact driving or proofing would 
be limited to fifteen minutes per pile (up to five piles total). Based 
on the Navy's experience with pile replacement during previous repair 
cycles at the EHW-1 facility, the Navy felt that this measure could be 
complied with. During previous repairs at EHW-1, no use of impact 
driving has been required to accomplish installation. All piles driven 
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 noise. Vibratory pile driving is restricted to the time period 
between July 16 and October 31, while impact driving would only be 
performed between July 16 and September 30. Non-pile driving, in-water 
work can be performed between July 16 and February 15. The Navy will 
monitor hydroacoustic levels, as well as the presence and behavior of 
marine mammals during pile installation and removal. Under the proposed 
action, twenty-eight 30-in steel piles would be installed and 138 
piles, steel and concrete, would be removed.
    The contractor estimates that steel pile installation and removal 
will occur at an average rate of two piles per day. For each pile 
installed, the driving time is expected to be no more than one hour for 
the vibratory portion of the project. The impact driving portion of the 
project, when required, is anticipated to take approximately fifteen 
minutes per pile, with a maximum of five piles per construction window 
permitted to be impact driven. Impact pile driving will not occur on 
more than five days for the duration of any pile driving window and no 
more than one pile will be proofed in a given day. Steel piles will be 
extracted using a vibratory hammer. Extraction is anticipated to take 
approximately thirty minutes per pile. Concrete piles will be removed 
using a pneumatic chipping hammer or other similar concrete demolition 
tool. It is estimated that concrete pile removal could occur at a rate 
of five piles per day maximum, but removal will more likely occur at a 
rate of three piles per day. It is expected to take approximately two 
hours to remove each concrete pile with a pneumatic chipping hammer.
    For steel piles, this results in a maximum of two hours of pile 
driving per pile or potentially four hours per day. For concrete piles, 
this results in a maximum of two hours of pneumatic chipping per pile, 
or potentially six hours per day. Therefore, while 108 days of in-water 
work time is proposed (July 16-October 31), only a fraction of the 
total work time per day will actually be spent pile driving. An average 
work day (two hours post-sunrise to two hours prior to sunset [civil]) 
ranges from six to twelve hours (for an average of approximately eight 
to nine hours), depending on the month. While it is anticipated that 
only four hours of pile driving would take place per day for steel 
piles, or six hours of pneumatic chipping for concrete piles, the Navy 
modeled potential impact as if the entire day could be spent pile 
driving to take into account deviations from the estimated times for 
pile installation and removal.
    Based on the proposed action, the total time from vibratory pile 
driving during steel pile installation would be approximately fourteen 
days (28 piles at

[[Page 6409]]

an average of two per day). The total time from impact pile driving 
during steel pile installation would be five days (five piles at one 
per day). The total time from vibratory pile driving during steel pile 
removal would be 21 days (42 piles at an average of two per day). The 
total time using a pneumatic chipping hammer during concrete pile 
removal would be 32 days (96 piles at an average of three per day).

Description of Noise Sources

    Underwater sound levels are comprised of multiple sources, 
including physical noise, biological noise, and anthropogenic noise. 
Physical noise includes waves at the surface, earthquakes, ice, and 
atmospheric noise. Biological noise includes sounds produced by marine 
mammals, fish, and invertebrates. Anthropogenic noise consists of 
vessels (small and large), dredging, aircraft overflights, and 
construction noise. Known noise levels and frequency ranges associated 
with anthropogenic sources similar to those that would be used for this 
project are summarized in Table 1. Details of each of the sources are 
described in the following text.

                          Table 1--Representative Noise Levels of Anthropogenic Sources
----------------------------------------------------------------------------------------------------------------
                                         Frequency     Underwater noise level (dB
            Noise source                range (Hz)           re 1 [micro]Pa)                  Reference
----------------------------------------------------------------------------------------------------------------
Small vessels.......................       250-1,000  151 dB root mean square       Richardson et al. 1995.
                                                       (rms) at 1 m (3.3 ft).
Tug docking gravel barge............       200-1,000  149 dB rms at 100 m (328 ft)  Blackwell and Greene 2002.
Vibratory driving of 30-in (0.8 m)          10-1,500  Approximately 168 dB rms at   WSDOT 2010a, 2010b.
 steel pipe pile.                                      10 m (33 ft).
Impact driving of 30-in steel pipe          10-1,500  Approximately 193 dB rms at   WSDOT 2005, 2008; CALTRANS
 pile.                                                 10 m.                         2007; Reyff 2005.
----------------------------------------------------------------------------------------------------------------

    In-water construction activities associated with the project would 
include impact pile driving and vibratory pile driving. The sounds 
produced by these activities fall into one of two sound types: Pulsed 
and non-pulsed. Impact pile driving produces pulsed sounds, while 
vibratory pile driving produces non-pulsed (or continuous) sounds. 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, seismic 
pile driving pulses, 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 
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.

Ambient Noise

    By definition, ambient noise is background noise, without a single 
source or point (Richardson et al. 1995). Ambient noise varies with 
location, season, time of day, and frequency. Ambient noise is 
continuous, but with much variability on time scales ranging from less 
than one second to one year (Richardson et al. 1995). Ambient 
underwater noise at the project area is widely variable over time due 
to a number of natural and anthropogenic sources. Sources of naturally 
occurring underwater noise include wind, waves, precipitation, and 
biological noise (e.g., shrimp, fish, cetaceans). There is also human-
generated noise from ship or boat traffic and other mechanical means 
(Urick 1983). Other sources of underwater noise at industrial 
waterfronts could come from cranes, generators, and other types of 
mechanized equipment on wharves or the adjacent shoreline.
    In the vicinity of the project area, the average broadband ambient 
underwater noise levels were measured at 114 dB re 1 [mu]Pa between 100 
Hz and 20 kHz (Slater 2009). Peak spectral noise 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 noise dominated the background noise environment at approximately 
5 kHz and above, and ambient noise levels flattened above 10 kHz.
    Airborne noise 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 noise ranging from 60-
80 dBA during daytime hours (Cavanaugh and Tocci 1998). The highest 
levels of airborne noise are produced along the waterfront and at the 
ordnance handling areas, where estimated noise levels range from 70-90 
dBA and may peak at 99 dBA for short durations. These higher noise 
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 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 noise 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

[[Page 6410]]

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 noise (e.g., vibratory pile driving), but 
below injurious thresholds. For airborne noise, 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 
underwater noise that potentially could result in disturbance to marine 
mammals transiting the project area. Transmission loss (TL) underwater 
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. The 
formula for transmission loss is:
    TL = B * log10(R) + C * R

where:
B = logarithmic (predominantly spreading) loss
C = linear (scattering and absorption) loss
R = range from source in meters

For all underwater calculations in this assessment, linear loss (C) was 
not used (i.e., C = 0) and transmission loss was calculated using only 
logarithmic spreading. Therefore, using practical spreading (B = 15), 
the revised formula for transmission loss is TL = 15 log10 
(R).
    Underwater Noise 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 sound pressure levels 
recorded from pile driving projects is available for consideration. In 
order to determine reasonable sound pressure levels 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 the same as those during vibratory installation (CALTRANS 
2007) and have been taken into consideration in the modeling analysis. 
There is a lack of empirical data regarding the acoustic output of 
chipping hammers. As a result, acoustic information for similar types 
of concrete breaking instruments, such as jackhammers and concrete 
saws, was also consulted. Overall, studies which met the following 
parameters were considered: (1) Pile size and materials: Installation--
steel pipe piles (30-in diameter); Removal--steel pipe piles (12 to 24-
in diameter); Removal--concrete piles (24-in diameter); (2) Hammer 
machinery: Installation (steel)--vibratory and impact hammer, Removal 
(steel)--vibratory hammer; Removal (concrete)--pneumatic chipping and/
or jackhammer; and (3) Physical environment--shallow depth (less than 
100 feet [30 m]).

        Table 2--Underwater Sound Pressure Levels From Similar In-Situ Monitored Construction Activities
----------------------------------------------------------------------------------------------------------------
                                                        Installation                           Measured sound
     Project and location        Pile size and type        method          Water depth        pressure levels
----------------------------------------------------------------------------------------------------------------
Eagle Harbor Maintenance       30-in (0.8 m) steel    Impact..........  10 m (33 ft).....  193 dB re 1 [mu]Pa
 Facility, WA \1\.              pipe pile.                                                  (rms) at 10 m (33
                                                                                            ft).
Richmond-San Rafael Bridge,    30-in steel pipe pile  Impact..........  4-5 m (13-16 ft).  190 dB re 1 [mu]Pa
 CA \2\.                                                                                    (rms) at 10 m.
Friday Harbor Ferry Terminal,  30-in steel pipe pile  Impact..........  10 m.............  196 dB re 1 [mu]Pa
 WA \3\.                                                                                    (rms) at 10 m.
Various projects \4\.........  30-in steel CISS \5\   Impact..........  Unknown..........  192 dB re 1 [mu]Pa
                                pile.                                                       (rms) at 10 m.
                                                                        Average..........  approximately 193 dB
                                                                                            re 1 [micro]Pa (rms)
                                                                                            at 10 m.
----------------------------------------------------------------------------------------------------------------
\1\ WSDOT 2008.
\2\ CALTRANS 2007.
\3\ WSDOT 2005.
\4\ Reyff 2005.
\5\ Cast-in-steel-shell.

    Tables presented here detail representative pile driving sound 
pressure levels that have been recorded from similar construction 
activities in recent years. Due to the similarity of these actions and 
the Navy's proposed action, they represent reasonable sound pressure 
levels which could be anticipated and these values were used in the 
acoustic modeling and analysis. Table 2 represents sound pressure 
levels (SPLs) that may be expected during the installation of the 30-in 
steel pipe piles using an impact hammer, should this be required. Table 
3 represents SPLs that may be expected during the installation of the 
30-in steel piles using a vibratory hammer. Table 4 represents SPLs 
that may be expected during the removal of the 12 to 24-in steel pipe 
piles and the 24-in concrete pilings.

        Table 3--Underwater Sound Pressure Levels From Similar In-Situ Monitored Construction Activities
----------------------------------------------------------------------------------------------------------------
                                                        Installation                           Measured sound
     Project and location        Pile size and type        method          Water depth        pressure levels
----------------------------------------------------------------------------------------------------------------
Keystone Ferry Terminal, WA    30-in (0.8 m) steel    Vibratory.......  5 m (15 ft)......  166 dB re 1 [micro]Pa
 \1\.                           pipe pile.                                                  (rms) at 10 m (33
                                                                                            ft).
Keystone Ferry Terminal, WA    30-in steel pipe pile  Vibratory.......  8 m (28 ft)......  171 dB re 1 [micro]Pa
 \1\.                                                                                       (rms) at 10 m.
Vashon Ferry Terminal, WA \2\  30-in steel pipe pile  Vibratory.......  10-12 m (36-40     165 dB re 1 [micro]Pa
                                                                         ft).               (rms) at 10 m.
                                                                       -----------------------------------------

[[Page 6411]]

 
                                                                        Average..........  approximately 168 dB
                                                                                            re 1 [micro]Pa (rms)
                                                                                            at 10 m.
----------------------------------------------------------------------------------------------------------------
\1\ WSDOT 2010a.
\2\ WSDOT 2010b.


     Table 4--Underwater Sound Pressure Levels for Pile Removal From Similar In-Situ Monitored Construction
                                                   Activities
----------------------------------------------------------------------------------------------------------------
                                                                                               Measured sound
     Project and location        Pile size and type    Removal method      Water depth        pressure levels
----------------------------------------------------------------------------------------------------------------
Unknown, CA \1\..............  24-in (0.6 m) steel    Vibratory.......  approximately 15   165 dB re 1 [micro]Pa
                                pipe pile.                               m (49 ft).         (rms) at 10 m (33
                                                                                            ft).
United Kingdom \2\...........  Unknown size \3\;      Jackhammer......  Unknown..........  161 dB re 1 [micro]Pa
                                concrete.                                                   (rms) at 1 m (3.3
                                                                                            ft).
----------------------------------------------------------------------------------------------------------------
\1\ CALTRANS 2007.
\2\ Nedwell and Howell 2004.
\3\ This is the only literature found for the underwater use of a jackhammer or pneumatic chipping tool. The
  size of the pile was not recorded. Since these tools operate to chip portions of concrete from the pile, sound
  output is not likely tied to the size of the pile itself as for impact and vibratory pile driving. Therefore,
  this data was found to be representative for this project.

    Several noise reduction measures can be employed during pile 
driving to reduce the high source pressures associated with impact pile 
driving. Among these is the use of bubble curtains, cofferdams, pile 
caps, or the use of vibratory installation. The efficacy of bubble 
curtains is dependent upon a variety of site-specific factors, 
including environmental conditions such as water current, sediment 
type, and bathymetry; the type and size of the pile; and the type and 
energy of the hammer. For the pile replacement project, the Navy 
intends to employ noise reduction techniques during impact pile 
driving, including the use of sound attenuation systems (e.g., bubble 
curtain). See ``Proposed Mitigation'' for more details on the impact 
reduction and mitigation measures proposed. The calculations of the 
distances to the marine mammal noise thresholds were calculated for 
impact installation with and without consideration for mitigation 
measures. Thorson and Reyff (2004) determined that a properly designed 
bubble curtain could provide a reduction of 5 to 20 dB. Based on 
information contained therein, distances calculated with consideration 
for mitigation assumed 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. All 
calculated distances to and the total area encompassed by the marine 
mammal noise thresholds are provided in Tables 5, 6, and 7. Calculated 
distance to thresholds using unmitigated impact driving is provided as 
reference; no unmitigated impact driving will occur. The USFWS has 
requested this as a measure to protect prey of the ESA-endangered 
marbled murrelet.

              Table 5--Calculated Distance(s) to and Area Encompassed by Underwater Marine Mammal Noise Thresholds During Pile Installation
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                             No mitigation, m    With mitigation, m    Area, km\2\ (mi
                      Group                                      Threshold                       (ft) \1\             (ft) \1\               \2\)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pinnipeds.......................................  Impact driving, injury (190 dB)........              16 (52)               4 (13)               0.000
Cetaceans.......................................  Impact driving, injury (180 dB)........             74 (243)              16 (52)        0.001 (0.000)
All.............................................  Impact driving, disturbance (160 dB)...        1,585 (5,200)          342 (1,122)        0.367 (0.142)
Pinnipeds.......................................  Vibratory driving, injury..............                   0                    0                0.000
Cetaceans.......................................  Vibratory driving, injury..............              2 (6.6)                   2                0.000
All.............................................  Vibratory driving, disturbance (120 dB)      15,849 (51,998)          \2\ 15,849     \2\ 789.1 (304.7)
--------------------------------------------------------------------------------------------------------------------------------------------------------
All sound levels expressed in dB re 1 [micro]Pa rms. Practical spreading loss (15 log, or 4.5 dB per doubling of distance) used for calculations.
\1\ Sound pressure levels used for calculations were: 193 dB re 1 [mu]Pa @ 10 m (33 ft) for impact and 168 dB re 1 [mu]Pa @ 10 m for vibratory.
\2\ Range calculated is greater than what would be realistic. 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).


Table 6--Calculated Distance(s) to and Area Encompassed by Underwater Marine Mammal Noise Thresholds During Pile
                                                     Removal
----------------------------------------------------------------------------------------------------------------
                                                                          Distance, m (ft)     Area, km \2\ (mi
                 Group                           Threshold \1\                  \2\                  \2\)
----------------------------------------------------------------------------------------------------------------
Pinnipeds.............................  Vibratory removal, injury (190                   0                0.000
                                         dB).
Cetaceans.............................  Vibratory removal, injury (180              1 (3.3)               0.000
                                         dB).
All...................................  Vibratory removal, disturbance   \3\ 10,000 (5,200)    \3\ 314.2 (121.3)
                                         (120 dB).
Pinnipeds.............................  Chipping hammer, injury (190                     0                0.000
                                         dB).
Cetaceans.............................  Chipping hammer, injury (180                     0                0.000
                                         dB).

[[Page 6412]]

 
All...................................  Chipping hammer, disturbance        \3\ 542 (1,778)    \3\ 0.929 (0.359)
                                         (120 dB).
----------------------------------------------------------------------------------------------------------------
All sound levels expressed in dB re 1 [mu]Pa rms. Practical spreading loss (15 log, or 4.5 dB per doubling of
  distance) used for calculations.
\1\ Specific criteria for pneumatic chipping hammers does not exist. These tools produce continuous sound
  similar to vibratory pile driving and therefore use the same criteria for the analysis of effects.
\2\ Sound pressure levels used for calculations were: 165 dB re 1 [mu]Pa @ 10 m (33 ft) for vibratory and 161 dB
  re 1 [mu]Pa @ 1 m for chipping hammer.
\3\ Range calculated is greater than what would be realistic. 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).

    The calculations presented in Tables 5 and 6 assumed a field free 
of obstruction, which is unrealistic, because Hood Canal does not 
represent open water conditions (free field). Therefore, sounds would 
attenuate as they encounter land masses or bends in the canal. As a 
result, some of the distances and areas of impact calculated cannot 
actually be attained at the project area. The actual distances to the 
behavioral disturbance thresholds for impact and vibratory pile driving 
and pneumatic chipping may be shorter than those calculated due to the 
irregular contour of the waterfront, the narrowness of the canal, and 
the maximum fetch (furthest distance sound waves travel without 
obstruction [i.e., line of sight]) at the project area. Table 7 shows 
the actual areas encompassed by the marine mammal thresholds during 
each stage of the EHW-1 pile replacement project. See Figures 6-1 
through 6-4 of the Navy's application for depictions of the areas of 
each underwater sound threshold that are predicted to occur at the 
project area due to pile driving, during each stage of the project.

   Table 7--Actual Area Encompassed by Underwater Marine Mammal Noise
                               Thresholds
------------------------------------------------------------------------
                                                       Area, km \2\ (mi
            Group                  Threshold \1\             \2\)
------------------------------------------------------------------------
Pinnipeds....................  Impact driving,                    0.000
                                injury (190 dB).
Cetaceans....................  Impact driving,             0.001 (0.000)
                                injury (180 dB).
All..........................  Impact driving,             0.287 (0.111)
                                disturbance (160
                                dB).
Pinnipeds....................  Vibratory driving,                 0.000
                                injury (190 dB).
Cetaceans....................  Vibratory driving,                 0.000
                                injury (180 dB).
All..........................  Vibratory driving,            40.3 (15.5)
                                disturbance (120
                                dB).
Pinnipeds....................  Vibratory removal,                 0.000
                                injury (190 dB).
Cetaceans....................  Vibratory removal,                 0.000
                                injury (180 dB).
All..........................  Vibratory removal,            35.9 (13.9)
                                disturbance (120
                                dB).
Pinnipeds....................  Chipping hammer,                   0.000
                                injury (190 dB).
Cetaceans....................  Chipping hammer,                   0.000
                                injury (180 dB).
All..........................  Chipping hammer,            0.608 (0.235)
                                disturbance (120
                                dB).
------------------------------------------------------------------------

     Airborne Sound Propagation Formula--Pile driving can generate 
airborne noise 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 sound pressure levels that could result in Level B 
behavioral harassment. The appropriate airborne noise threshold for 
behavioral disturbance for all pinnipeds, except harbor seals, is 100 
dB re 20 [mu]Pa rms (unweighted). For harbor seals, the threshold is 90 
dB re 20 [mu]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 [mu]Pa rms (unweighted) airborne 
thresholds. The formula for calculating spherical spreading loss is:
    TL = 20log r

where:
TL = Transmission loss
r = Distance from source to receiver

    *Spherical spreading results in a 6 dB decrease in sound pressure 
level per doubling of distance.
    Airborne Sound from Pile Installation and Removal--As was discussed 
for underwater noise 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 sound pressure levels 
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 8 
details representative pile driving and removal activities that have 
occurred in recent years. Due to the similarity of these actions and 
the Navy's proposed action, they represent reasonable sound pressure 
levels which could be anticipated.

         Table 8--Airborne Sound Pressure Levels From Similar In-Situ Monitored Construction Activities
----------------------------------------------------------------------------------------------------------------
                                                                                               Measured sound
     Project and location        Pile size and type        Method          Water depth        pressure levels
----------------------------------------------------------------------------------------------------------------
Northstar Island, AK \1\.....  42-in (1.1 m) steel    Impact..........  Approximately 12   97 dB re 20 [mu]Pa
                                pipe pile.                               m (40 ft).         (rms) at 160 m (525
                                                                                            ft).
Friday Harbor Ferry Terminal,  24-in (0.6 m) steel    Impact..........  Approximately 10   112 dB re 20 [mu]Pa
 WA \2\.                        pipe pile.                               m (33 ft).         (rms) at 49 m (160
                                                                                            ft).

[[Page 6413]]

 
Wahkiakum Ferry Terminal \3\.  18-in (0.5 m) steel    Vibratory         Approximately 3-4  87.5 dB re 20 [mu]Pa
                                pipe pile.             removal.          m (10-12 ft).      (rms) at 15 m (50
                                                                                            ft).
Keystone Ferry Terminal, WA    30-in (0.8 m) steel    Vibratory         Approximately 9 m  98 dB re 20 [mu]Pa
 \3\.                           pipe pile.             installation.     (30 ft).           (rms) at 11 m (36
                                                                                            ft).
Unknown \4\..................  Unknown \5\, Concrete  Chipping Hammer.  Unknown..........  92 dB re 20 [mu]Pa
                                                                                            (rms) at 10 m (33
                                                                                            ft).
----------------------------------------------------------------------------------------------------------------
\1\ Blackwell et al. 2004.
\2\ WSDOT 2005.
\3\ WSDOT 2010c.
\4\ Cheremisinoff 1996.
\5\ This is the only known data for airborne noise from use of a chipping hammer. The size of the pile was not
  recorded. However, since these tools operate to chip portions of concrete from the pile, sound outputs are not
  tied to the size of the pile. Therefore, this data was found to be representative for this project.
 

    Based on in-situ recordings from similar construction activities, 
the maximum airborne noise levels that would result from impact and 
vibratory pile driving are estimated to be 120 dB re 20 [mu]Pa (rms) at 
15 m (50 ft) and 98 dB re 20 [mu]Pa (rms) at 11 m (36 ft), respectively 
(Blackwell et al. 2004; WSDOT 2005, 2010c). Values for impact driving 
from the Northstar Island and Friday Harbor projects were averaged. The 
maximum airborne noise level that would result from vibratory removal 
and pneumatic chipping are estimated to be 92 dB re 20 [micro]Pa (rms) 
at 15 m (50 ft) and 92 dB re 20 [mu]Pa (rms) at 33 ft (10 m), 
respectively. The values from projects using vibratory hammers 
(Wahkiakum Ferry and Keystone Ferry) were averaged to obtain a 
representative value for vibratory removal. This is because the largest 
steel piles to be removed at EHW-1 are 24-in diameter; a representative 
value was obtained by averaging data from 30-in and 18-in diameter 
piles. The distances to the airborne thresholds were calculated with 
the airborne transmission loss formula presented previously. All 
calculated distances to and the total area encompassed by the airborne 
marine mammal noise thresholds are provided in Table 9.

  Table 9--Calculated Distances to and Area Encompassed by the Marine Mammal Noise Thresholds In-air From Pile
                                                     Driving
----------------------------------------------------------------------------------------------------------------
                                                                             Airborne behavioral disturbance
                                                                        ----------------------------------------
                 Species                             Threshold                                Area in km \2\ (mi
                                                                         Distance in m (ft)          \2\)
----------------------------------------------------------------------------------------------------------------
Pinnipeds (except harbor seal)...........  100 dB re 20 [mu]Pa rms                159 (522)        0.079 (0.031)
                                            (impact disturbance).
Harbor seal..............................  90 dB re 20 [mu]Pa rms               501 (1,643)        0.789 (0.305)
                                            (impact disturbance).
Pinnipeds (except harbor seal)...........  100 dB re 20 [mu]Pa rms                   9 (30)               0.000
                                            (vibratory disturbance;
                                            installation).
Harbor seal..............................  90 dB re 20 [mu]Pa rms                   29 (95)        0.029 (0.003)
                                            (vibratory disturbance;
                                            installation).
Pinnipeds (except harbor seal)...........  100 dB re 20 [mu]Pa rms                   7 (23)               0.000
                                            (vibratory disturbance;
                                            removal).
Harbor seal..............................  90 dB re 20 [mu]Pa rms                   20 (66)        0.001 (0.000)
                                            (vibratory disturbance;
                                            removal).
Pinnipeds (except harbor seal)...........  100 dB re 20 [mu]Pa rms                   4 (13)               0.000
                                            (pneumatic chipping).
Harbor seal..............................  90 dB re 20 [mu]Pa rms                   13 (43)        0.001 (0.000)
                                            (pneumatic chipping).
----------------------------------------------------------------------------------------------------------------
All SPLs are reported re 20 [mu]Pa rms (unweighted).

    All airborne distances are less than those calculated for 
underwater sound thresholds, with the exception of the behavioral 
disturbance distances from impact pile driving for harbor seals. This 
disturbance zone radius is 501 m, whereas the disturbance zone radius 
for underwater noise from impact driving (160-dB) is only 342 m (see 
Table 5). Therefore, the monitoring buffer zone for behavioral 
disturbance will be expanded to encompass this distance for harbor 
seals. For all other activities, protective measures are in place out 
to the distances calculated for the underwater thresholds, and the 
distances for the airborne thresholds will be covered fully by 
mitigation and monitoring measures in place for underwater sound 
thresholds. Aside from the aforementioned case, all construction noise 
associated with the project would not extend beyond the buffer zone for 
underwater sound that would be established to protect seals and sea 
lions. No haul-outs or rookeries are located within these radii. See 
figures 6-5 through 6-10 of the Navy's application for depictions of 
the actual distances for each airborne sound threshold that are 
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 decades, and therefore was excluded 
from further

[[Page 6414]]

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. As noted previously, and in Table 10, Steller sea 
lions are not present in the project area during the proposed project 
timeframe for pile driving (July 16-October 31). Steller sea lions will 
not be discussed in detail. 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 10 lists the marine mammal species that occur in the 
vicinity of NBKB and their estimated densities within the project area 
during the proposed timeframe.

                   Table 10--Marine Mammals Present in the Hood Canal in the Vicinity of NBKB
----------------------------------------------------------------------------------------------------------------
                                                                                                Density in warm
                                                                Relative         Season of         season \3\
           Species                 Stock abundance \1\        occurrence in      occurrence     (individuals/km
                                                               Hood Canal                             \2\)
----------------------------------------------------------------------------------------------------------------
Steller sea lion
Eastern U.S. DPS.............  50,464 \2\.................  Rare to           Fall to late               N/A
                                                             occasional use.   spring (Nov-
                                                                               mid April).
California sea lion
U.S. Stock...................  238,000....................  Common..........  Fall to late              \4\0.410
                                                                               spring (Aug-
                                                                               May).
Harbor seal
WA inland waters stock.......  14,612 (CV = 0.15).........  Common..........  Year-round;               \5\1.31
                                                                               resident
                                                                               species in
                                                                               Hood Canal.
Killer whale
West Coast transient stock...  314........................  Rare to           Year-round.....           \6\0.038
                                                             occasional use.
Dall's porpoise
CA/OR/WA stock...............  48,376 (CV = 0.24).........  Rare to           Year-round.....           \7\0.043
                                                             occasional use.
Harbor porpoise
WA inland waters stock.......  10,682 (CV = 0.38).........  Rare to           Year-round.....           \7\0.011
                                                             occasional use.
----------------------------------------------------------------------------------------------------------------
\1\ NMFS marine mammal stock assessment reports at: https://www.nmfs.noaa.gov/pr/sars/species.htm.
\2\ Average of a given range.
\3\ Warm season refers to the period from May-Oct.
\4\ DoN 2010a.
\5\ Jeffries et al. 2003; Huber et al. 2001.
\6\ London 2006.
\7\ Agness and Tannenbaum 2009a.

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.
    Population Abundance--The U.S. stock of California sea lions may 
occur in the marine waters nearby NBKB. The stock 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). 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 islan