Small Takes of Marine Mammals Incidental to Specified Activities; Cape Wind's High Resolution Survey in Nantucket Sound, MA, 56735-56742 [2011-23575]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 76, Number 178 (Wednesday, September 14, 2011)]
[Notices]
[Pages 56735-56742]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-23575]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XA408


Small Takes of Marine Mammals Incidental to Specified Activities; 
Cape Wind's High Resolution Survey in Nantucket Sound, MA

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

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

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SUMMARY: NMFS has received a complete and adequate application from 
Cape Wind Associates for an Incidental Harassment Authorization (IHA) 
to take marine mammals, by harassment, incidental to pre-construction 
high resolution survey activities. Pursuant to the Marine Mammal 
Protection Act (MMPA), NMFS is proposing to issue an IHA to Cape Wind 
Associates to incidentally harass, by Level B harassment, five species 
of marine mammals during the specified activity within Nantucket Sound 
and is requesting comments on its proposal.

DATES: Comments and information must be received no later than October 
14, 2011.

ADDRESSES: Comments on the application and this proposal 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.Magliocca@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 
(for example, name, address, etc.) 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. Documents cited in this 
notice may also be viewed, by appointment, during regular business 
hours, at the aforementioned address.

FOR FURTHER INFORMATION CONTACT: Michelle Magliocca, 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

[[Page 56736]]

commercial fishing) within a specific 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 United States can apply for an authorization 
to incidentally take small numbers of marine mammals by harassment. 
Section 101(a)(5)(D) establishes a 45-day time limit for NMFS review of 
an application followed by a 30-day public notice and comment period on 
any proposed authorizations for the incidental harassment of marine 
mammals. Within 45 days of the close of the comment period, NMFS must 
either issue or deny the authorization.
    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

    On April 26, 2011, NMFS received an application from Cape Wind 
Associates requesting an IHA for the take, by Level B harassment, of 
small numbers of minke whales, Atlantic white-sided dolphins, harbor 
porpoises, gray seals, and harbor seals, incidental to high resolution 
survey activities. Upon receipt of additional information, NMFS 
determined the application adequate and complete on August 5, 2011.
    Cape Wind Associates proposes to conduct a high resolution 
geophysical survey in Nantucket Sound, Massachusetts. The survey would 
satisfy the mitigation and monitoring requirements for ``cultural 
resources and geology'' in the environmental stipulations of the Bureau 
of Ocean Energy Management, Regulation and Enforcement's lease. This is 
part of a long-term Cape Wind energy project involving the future 
installation of 130 wind turbine generators. Because sounds from the 
survey equipment could harass marine mammals, NMFS is proposing to 
issue an IHA for take incidental to the high resolution geophysical 
survey.

Description of the Specified Activity

    Cape Wind Associates proposes to conduct a high resolution 
geophysical survey in order to acquire remote-sensing data around 
Horseshoe Shoal which would be used to characterize resources at or 
below the seafloor. The purpose of the survey would be to identify any 
submerged cultural resources that may be present and to generate 
additional data describing the geological environment within the survey 
area. This specific activity is part of a larger Cape Wind energy 
project, which involves the installation of 130 wind turbine generators 
on Horseshoe Shoal over a two-year period. The survey would collect 
data along predetermined track lines using a towed array of 
instrumentation, which would include a singlebeam depth sounder, side 
scan sonar, magnetometer, shallow-penetration subbottom profiler, 
multibeam depth sounder, and medium-penetration subbottom profiler. The 
proposed high resolution geophysical survey activities would not result 
in any disturbance to the sea floor. Cape Wind Associates also plans to 
conduct a geotechnical survey that is not expected to impact marine 
mammals; therefore, no incidental takes are being requested for this 
activity. In summary, the geotechnical survey would include the 
acquisition of soil borings and/or cone penetrometer tests at select 
wind turbine generator locations, as well as one vibracore at the 
planned location of each wind turbine generator. These aspects of the 
survey are not expected to generate sound pressure levels that would 
exceed marine mammal harassment thresholds, except for the area 
immediately adjacent to the core barrel. A 500-meter (m) exclusion zone 
would be in place and continuously monitored to prevent marine mammal 
harassment.
    Survey activities are necessary prior to construction of the wind 
turbine array and are scheduled to begin in the fall of 2011, 
continuing on a daily basis for up to five months. Survey vessels would 
operate during daytime hours only and Cape Wind Associates estimates 
that one survey vessel would cover about 17 NM of track line per day. 
Therefore, Cape Wind Associates conservatively estimates that survey 
activities would take 137 days. However, if more than one survey vessel 
is used, the survey duration would be considerably shorter.
    The high resolution geophysical survey would cover approximately 
110 square kilometers (km\2\) (42.5 square miles [mi\2\]). This area 
includes the future location of the wind turbine generators--an area 
about 8.4 km (5.2 mi) from Point Gammon, 17.7 km (11 mi) from Nantucket 
Island, and 8.9 km (5.5 mi) from Martha's Vineyard--and cables 
connecting the wind park to the mainland. The survey area within the 
wind park would be transited by survey vessels towing specialized 
equipment along primary track lines and perpendicular tie lines. 
Preliminary survey designs include primary track lines with north-south 
orientations and assume 30-m line spacing. Preliminary survey designs 
also call for tie lines to likely run in a west-east orientation 
covering targeted areas of the construction footprint where wind 
turbine generators would be located. The survey area along the 
interconnecting submarine cable route includes a 100-foot (ft) 
construction corridor covered by three track lines, as well as an 
anchor corridor north of the wind farm's area of potential effect. The 
total track line distance covered during the survey is estimated to be 
about 4,292 km (2,317 NM).
    Multiple survey vessels may operate within the survey area and 
would travel at about 3 knots during data acquisition and 15 knots 
during transit between the survey area and port. The survey vessels 
would acquire data continuously throughout the survey area during the 
day and terminate survey activities before dark, prior to returning to 
port. Given the slow speeds at which the survey vessels would operate, 
increase of vessel collision risk to marine mammals is expected to be 
negligible. Vessel sounds during survey activities would result from 
propeller cavitations, propeller singing, propulsion, flow noise from 
water dragging across the hull, and bubbles breaking in the wake. The 
dominant sound source from vessels would be from propeller cavitations; 
however, sounds resulting from survey vessel activity are considered to 
be no louder than the existing ambient sound levels and sound generated 
from regular shipping and boating activity in Nantucket Sound (MMS, 
2009).

[[Page 56737]]

    The dominant sources of sound during the proposed survey activities 
would be from the towed equipment used to gather seafloor data. Two of 
the seismic survey devices used during the high resolution geophysical 
survey emit sounds within the hearing range of marine mammals in 
Nantucket Sound: Shallow-penetration and medium-penetration subbottom 
profilers (known as a ``chirp'' and ``boomer,'' respectively). Cape 
Wind Associates would use a chirp to provide high resolution data of 
the upper 15 m (49 ft) of sea bottom. An EdgeTech 3000 Series or 
similar model would be used. The chirp would be towed near the center 
of the survey vessel directly adjacent to the gunwale of the boat, 
about 1 to 1.5 m (3 to 5 ft) beneath the water's surface. Sources such 
as the chirp are considered non-impulsive, intermittent sounds. The 
frequency range for this instrument is generally 2 to 16 kilohertz 
(kHz)--a range audible by all marine mammal species in Nantucket Sound. 
The estimated sound pressure level at the source would be 201 dB re 1 
[micro]Pa at 1 m with a typical pulse length of 32 milliseconds and a 
pulse repetition rate of 4 per second. Underwater sound levels from the 
chirp would dissipate to 180 dB (the Level A harassment threshold, 
described later) at 17 m (56 ft) and to 160 dB (the Level B harassment 
threshold) at 258 m (847 ft). This calculation is based on a practical 
spreading model which represents an intermediate condition between 
spherical and cylindrical spreading to estimate sound propagation. Cape 
Wind Associates would use a boomer to obtain deeper resolution of 
geologic layering that cannot be imaged by the chirp. An Applied 
Acoustics 200, 300, or similar model would be used. The boomer would be 
towed about 10 to 15 ft behind the survey vessel's stern at the water's 
surface. Unlike the chirp, the boomer emits an impulse sound, 
characterized by a relatively rapid rise-time to maximum pressure 
followed by a period of diminishing and oscillating pressures (Southall 
et al., 2007). The boomer has a broad frequency range of 0.5 to 20 
kHz--a range audible by all marine mammal species in Nantucket Sound. 
The estimated sound pressure level at the source would be 205 dB re 1 
[micro]Pa at 1 m with a short duration sound pulse of about 330 
milliseconds. Underwater sound levels from the boomer would dissipate 
to 180 dB at 30 m (98 ft) and to 160 dB at 444 m (1,457 ft). This 
calculation is also based on practical spreading.

Description of Marine Mammals in the Area of the Specified Activity

    Marine mammals with known occurrences in Nantucket Sound that could 
be harassed by high resolution geophysical survey activity in Nantucket 
Sound are listed in Table 1. These are the species for which take is 
being requested. In general, large whales do not frequent Nantucket 
Sound, but they are discussed below because some species have been 
reported near the project vicinity.

             Table 1--Marine Mammals That Could Be Impacted by Survey Activities in Nantucket Sound
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                                                                                           Time of year in New
             Common name                   Scientific name           MMPA status\1\              England
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                                         Whales and Dolphins (Cetaceans)
----------------------------------------------------------------------------------------------------------------
Minke whale..........................  Balaenoptera             N-D....................  April through October.
                                        actuorostrata.
Atlantic white-sided dolphin.........  Lagenorhynchus acutus..  N-D....................  October through
                                                                                          December.
Harbor porpoise......................  Phocoena phocoena......  N-D....................  Year-round (peak Sept-
                                                                                          Apr).
----------------------------------------------------------------------------------------------------------------
                                                Seals (Pinnipeds)
----------------------------------------------------------------------------------------------------------------
Gray seal............................  Halichoerus grypis.....  N-D....................  Year-round.
Harbor seal..........................  Phoca vitulina.........  N-D....................  October through April.
----------------------------------------------------------------------------------------------------------------
\1\N-D = non-depleted. None of the species are listed under the Endangered Species Act.

    Sightings data indicate that whales rarely visit Nantucket Sound 
and there are no sightings of large whales on Horseshoe Shoal. Since 
2002, no humpback whales (Megaptera novaeangilae) have been observed 
anywhere in Nantucket Sound and there are no documented occurrences of 
fin whales (Balaenoptera physalus) within Nantucket Sound. Right whales 
(Eubaelena glacialis) are considered rare in Nantucket Sound and have 
not been sighted on Horseshoe Shoal. All of the right whales observed 
in Nantucket Sound during 2010 quickly transited the area and there is 
no evidence of any persistent aggregations around the proposed project 
area. The best available science indicates that humpback whales, fin 
whales, and right whales--although present in the New England region--
are rare in Nantucket Sound and transient individuals may be 
occasionally found 20 km (12 mi) from the proposed project area; this 
is likely due to the shallow depths of Nantucket Sound and its location 
outside of the coastal migratory corridor.
    Likewise, sightings data shows no record of long-finned pilot 
whales, striped dolphins, Atlantic spotted dolphins, common dolphins, 
Risso's dolphins, Kogia species, harp seals, or hooded seals in 
Nantucket Sound, although these stocks exist in the New England region. 
Therefore, Cape Wind Associates is not requesting, nor is NMFS 
proposing, take for the aforementioned species.

Minke Whales

    In the North Atlantic, minke whales are found from Canada to the 
Gulf of Mexico and concentrated in New England waters, particularly in 
the spring and summer months. Minke whales found in Nantucket Sound are 
part of the Canadian East Coast stock, which runs from the Davis Strait 
down to the Gulf of Mexico. The best available abundance estimate for 
this stock is 8,987 individuals. Sightings data indicate that minke 
whales prefer shallower waters when in the Cape Cod vicinity, but 
depths significantly greater than Nantucket Sound. Sightings per unit 
effort estimates for Nantucket Sound are 0.1 to 5.9 minke whales per 
1,000 km of survey track for spring and summer. However, estimates may 
be biased due to heavier whale watching activities during those months. 
Minke whales are one of the most abundant whale species in the world 
and their population is considered stable throughout. The minke whale 
is not listed under the Endangered Species Act nor considered strategic 
under the MMPA.

Atlantic White-Sided Dolphin

    Atlantic white-sided dolphins are found in temperate and sub-polar 
waters of the North Atlantic, typically along the continental shelf and 
slope. In the

[[Page 56738]]

western North Atlantic, they are found from North Carolina to 
Greenland. During summer months, Atlantic white-sided dolphins move 
north and closer to shore. Atlantic white-sided dolphins are rare in 
Nantucket Sound, but are found in deeper waters around Massachusetts 
and Rhode Island. In 2007, the estimated population size of the Western 
North Atlantic stock was about 63,000 animals. There is insufficient 
data to determine population trends, but Atlantic white-sided dolphins 
are not listed under the Endangered Species Act, nor considered 
strategic under the MMPA.

Harbor Porpoises

    Harbor porpoises have a wide and discontinuous range that includes 
the North Atlantic and North Pacific. In the western North Atlantic, 
harbor porpoises are found from Greenland to Cape Hatteras, North 
Carolina. Harbor porpoises in U.S. waters are divided into 10 stocks, 
based on genetics, movement patterns, and management. Any harbor 
porpoises encountered during the proposed survey activities would be 
part of the Gulf of Maine/Bay of Fundy stock which has an estimated 
abundance of 89,504 animals and a minimum population estimate of 60,970 
(NMFS, 2009c). They congregate around the Gulf of Maine during summer 
months, but are otherwise dispersed along the east coast. No trend 
analyses exist for this species. Harbor porpoises are not listed under 
the Endangered Species Act nor considered strategic under the MMPA.

Gray Seals

    Gray seals inhabit temperate and sub-arctic waters. They are found 
from Maine to Long Island Sound, live on remote, exposed islands, 
shoals, and unstable sandbars, and are the second most common pinniped 
along the U.S. Atlantic coast. Three major populations exist in eastern 
Canada, northwestern Europe, and the Baltic Sea. The western North 
Atlantic stock is equivalent to the eastern Canada population and 
ranges from New York to Labrador. Pupping occurs on land or ice from 
late December through mid-February with peaks in mid-January. Muskeget 
Island (located between Martha's Vineyard and Nantucket Island) and 
Monomoy Island (at the eastern limit of Nantucket Sound) are the only 
gray seal breeding colonies in the U.S. and the southernmost gray seal 
breeding colonies in the world. These breeding colonies are about 24 km 
(13 NM) and 14 km (7 NM) from the proposed project site, respectively. 
Gray seals presently use the islands as areas to give birth and raise 
their pups. There is no defined migratory behavior for gray seals, so a 
large portion of the population may be present in Nantucket Sound year-
round. Some adults move north during spring and summer, out of 
Nantucket Sound to the waters off Maine and Canada, but others have 
been observed in high abundance in Chatham Harbor, MA and other areas 
of lower Cape Cod during this time.
    Incidental observations of seals were recorded during avian aerial 
surveys conducted independently by Cape Wind Associates and the 
Massachusetts Audubon Society. Between May 2002 and February 2004, Cape 
Wind Associates conducted about 46 aerial avian surveys in Nantucket 
Sound, with particular focus on Horseshoe Shoal. During this time, 
about 26,873 seals were observed throughout Nantucket Sound; about 56 
of these were observed within the proposed project area over the three-
year period. Current population numbers for the western North Atlantic 
stock are unknown, but are estimated at over 250,000 animals. Gray seal 
numbers are increasing in coastal waters between southern Massachusetts 
and eastern Long Island. Their abundance is likely increasing 
throughout the western Atlantic, but the rate of increase is unknown. 
Gray seals are not listed under the Endangered Species Act, nor 
considered strategic under the MMPA.

Harbor Seals

    Harbor seals, also known as common seals, are found throughout 
coastal waters of the Atlantic Ocean and considered the most abundant 
pinniped on the U.S. east coast. The best available estimate for the 
harbor seal population along the New England coast is 99,340 (NMFS, 
2009f). They are most common around coastal islands, ledges, and 
sandbars above 30[deg] N latitude and range from the Arctic down to 
Nantucket Sound. Harbor seals are seasonal visitors to Massachusetts; 
breeding and pupping occur through the spring and summer in Maine and 
Canada. Harbor seals typically over-winter in Massachusetts, but some 
remain in southern New England year-round. No pupping areas have been 
identified in southern New England. Extensive sand spits off Muskeget 
Island and neighboring Tuckernuck and Skiff Islands have been 
identified as preferred haul-out spots for large numbers of harbor 
seals.
    Harbor seal abundance estimates for Nantucket Sound are scarce. 
Barlas (1999) observed harbor seals on Cape Cod from October through 
April and saw abundance peak in March, with very few individuals using 
haul-out sites in Nantucket Sound. Waring (unpublished data, 2002) 
observed an increased abundance of harbor seals on Muskeget Island, 
Monomoy Island, and Tuckernuck Island in 1999 and 2000; however, harbor 
seals are not likely to be in the same area when gray seals are 
breeding.

Potential Effects on Marine Mammals

    Use of subbottom profilers on Horseshoe Shoal may temporarily 
impact marine mammal behavior within the survey area due to elevated 
in-water sound levels. Marine mammals are continually exposed to many 
sources of sound. Naturally occurring sounds such as lightning, rain, 
sub-sea earthquakes, and biological sounds (for example, snapping 
shrimp, whale songs) are widespread throughout the world's oceans. 
Marine mammals produce sounds in various contexts and use sound for 
various biological functions including, but not limited to, (1) Social 
interactions; (2) foraging; (3) orientation; and (4) predator 
detection. Interference with producing or receiving these sounds may 
result in adverse impacts. Audible distance, or received levels of 
sound depend on the nature of the sound source, ambient noise 
conditions, and the sensitivity of the receptor to the sound 
(Richardson et al., 1995). Type and significance of marine mammal 
reactions to sound are likely dependent on a variety of factors 
including, but not limited to, (1) The behavioral state of the animal 
(for example, feeding, traveling, etc.); (2) frequency of the sound; 
(3) distance between the animal and the source; and (4) the level of 
the sound relative to ambient conditions (Southall et al., 2007).
    For background, sound is a physical phenomenon consisting of minute 
vibrations that travel through a medium, such as air or water, and is 
generally characterized by several variables. Frequency describes the 
sound's pitch and is measured in hertz (Hz) or kilohertz (kHz), while 
sound level describes the sound's loudness and is measured in decibels 
(dB). Sound level increases or decreases exponentially with each dB of 
change. For example, 10 dB yields a sound level 10 times more intense 
than 1 dB, while 20 dB is 100 times more intense, and 30 dB is 1,000 
times more intense. Sound levels are compared to a reference sound 
pressure (micro-Pascal) to identify the medium. For air and water, 
these reference pressures are ``re: 20 [mu]Pa'' and ``re: 1 [mu]Pa,'' 
respectively. Root mean square (RMS) is the quadratic mean sound 
pressure over the duration of an impulse. RMS is calculated by squaring

[[Page 56739]]

all of the sound amplitudes, averaging the squares, and 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 rather than by peak pressures.
    Cetaceans are divided into three functional hearing groups: Low-
frequency, mid-frequency, and high-frequency. Minke whales are 
considered low-frequency cetaceans and their estimated auditory 
bandwidth (lower to upper frequency hearing cut-off) ranges from 7 Hz 
to 22 kHz. Atlantic white-sided dolphins are considered mid-frequency 
cetaceans and their estimated auditory bandwidth ranges from 150 Hz to 
160 kHz. Lastly, harbor porpoises are considered high-frequency 
cetaceans and their estimated auditory bandwidth ranges from 200 Hz to 
180 kHz. In contrast, pinnipeds are divided into two functional hearing 
groups: In water and in air. Pinnipeds in water have an estimated 
auditory bandwidth of 75 Hz to 75 kHz. There are no pinniped haul-outs 
close enough to the survey area to take in air auditory bandwidths into 
consideration.

Hearing Impairment

    Marine mammals may experience temporary or permanent hearing 
impairment when exposed to loud sounds. Hearing impairment is 
classified by temporary threshold shift (TTS) and permanent threshold 
shift (PTS). There are no empirical data for onset of PTS in any marine 
mammal; therefore, PTS-onset must be estimated from TTS-onset 
measurements and from the rate of TTS growth with increasing exposure 
levels above the level eliciting TTS-onset. PTS is presumed to be 
likely if the hearing threshold is reduced by >=40 dB (that is, 40 dB 
of TTS). PTS is considered auditory injury (Southall et al., 2007) and 
occurs in a specific frequency range and amount. Irreparable damage to 
the inner or outer cochlear hair cells may cause PTS; however, other 
mechanisms are also involved, such as exceeding the elastic limits of 
certain issues and membranes in the middle and inner ears and resultant 
changes in the chemical composition of the inner ear fluids (Southall 
et al., 2007). Due to proposed mitigation measures and source levels, 
NMFS does not expect marine mammals to be exposed to PTS levels during 
the proposed survey activities.

Temporary Threshold Shift (TTS)

    TTS is the mildest form of hearing impairment that can occur during 
exposure to a loud sound (Kryter, 1985). While experiencing TTS, the 
hearing threshold rises and a sound must be louder in order to be 
heard. TTS can last from minutes or hours to days, but is recoverable. 
TTS also occurs in specific frequency ranges; therefore, an animal 
might experience a temporary loss of hearing sensitivity only between 
the frequencies of 1 and 10 kHz, for example. The amount of change in 
hearing sensitivity is also variable and could be reduced by 6 dB or 30 
dB, for example. Recent literature highlights the inherent complexity 
of predicting TTS onset in marine mammals, as well as the importance of 
considering exposure duration when assessing potential impacts (Mooney 
et al., 2009a, 2009b; Kastak et al., 2007). Generally, with sound 
exposures of equal energy, quieter sounds (lower SPL) of longer 
duration were found to induce TTS onset more than louder sounds (higher 
SPL) of shorter duration (more similar to subbottom profilers). For 
intermittent sounds, less threshold shift will occur than from a 
continuous exposure with the same energy (some recovery will occur 
between intermittent exposures) (Kryter et al., 1966; Ward, 1997). For 
sound exposures at or somewhat above the TTS-onset threshold, hearing 
sensitivity recovers rapidly after exposure to the sound ends. Southall 
et al. (2007) considers a 6 dB TTS (that is, baseline thresholds are 
elevated by 6 dB) to be a sufficient definition of TTS-onset. NMFS 
considers TTS as Level B harassment that is mediated by physiological 
effects on the auditory system; however, NMFS does not consider TTS-
onset to be the lowest level at which Level B harassment may occur. 
Southall et al. (2007) summarizes underwater pinniped data from Kastak 
et al. (2005), indicating that a tested harbor seal showed a TTS of 
around 6 dB when exposed to a nonpulse noise at sound pressure level 
152 dB re: 1 [mu]Pa for 25 minutes. There is no information on species-
specific TTS for harbor porpoises, minke whales, Atlantic white-sided 
dolphins, or gray seals; published data on the onset of TTS are limited 
to the captive bottlenose dolphin and beluga (Finneran et al., 2000, 
2002b, 2005a; Schlundt et al., 2000; Nachtigall et al., 2003, 2004).

Behavioral Disturbance

    Behavioral responses to sound are highly variable and context-
specific. An animal's perception of and response to (in both nature and 
magnitude) an acoustic event can be influenced by prior experience, 
perceived proximity, bearing of the sound, familiarity of the sound, 
etc. (Southall et al., 2007). If a marine mammal does react briefly to 
an underwater sound by changing its behavior or moving a small 
distance, the impacts of the change are unlikely to be significant to 
the individual, let alone the stock or population. However, if a sound 
source displaces marine mammals from an important feeding or breeding 
area for a prolonged period, impacts on individuals and populations 
could be significant (e.g., Lusseau and Bejder, 2007; Weilgart, 2007). 
Given the many uncertainties in predicting the quantity and types of 
impacts of noise on marine mammals, it is common practice to estimate 
how many mammals would be present within a particular distance of 
activities and/or exposed to a particular level of sound. In most 
cases, this approach likely overestimates the numbers of marine mammals 
that would be affected in some biologically-important manner.
    The studies that address responses of low-frequency cetaceans (such 
as the minke whale) to non-pulse sounds include data gathered in the 
field and related to several types of sound sources (of varying 
similarity to chirps), including: Vessel noise, drilling and machinery 
playback, low-frequency M-sequences (sine wave with multiple phase 
reversals) playback, tactical low-frequency active sonar playback, 
drill ships, and non-pulse playbacks. These studies generally indicate 
no (or very limited) responses to received levels in the 90 to 120 dB 
re: 1[mu]Pa range and an increasing likelihood of avoidance and other 
behavioral effects in the 120 to 160 dB range. As mentioned earlier, 
though, contextual variables play a very important role in the reported 
responses and the severity of effects are not linear when compared to 
received level. Also, few of the laboratory or field datasets had 
common conditions, behavioral contexts, or sound sources, so it is not 
surprising that responses differ.
    The studies that address responses of mid-frequency cetaceans (such 
as Atlantic white-sided dolphins) to non-pulse sounds include data 
gathered both in the field and the laboratory and related to several 
different sound sources (of varying similarity to chirps) including: 
pingers, drilling playbacks, ship and ice-breaking noise, vessel noise, 
Acoustic harassment devices (AHDs), Acoustic Deterrent Devices (ADDs), 
mid-frequency active sonar, and non-pulse bands and tones. Southall et 
al. (2007) were unable to come to a clear

[[Page 56740]]

conclusion regarding the results of these studies. In some cases 
animals in the field showed significant responses to received levels 
between 90 and 120 dB, while in other cases these responses were not 
seen in the 120 to 150 dB range. The disparity in results was likely 
due to contextual variation and the differences between the results in 
the field and laboratory data (animals typically responded at lower 
levels in the field).
    The studies that address responses of high-frequency cetaceans 
(such as the harbor porpoise) to non-pulse sounds include data gathered 
both in the field and the laboratory and related to several different 
sound sources (of varying similarity to chirps), including: pingers, 
AHDs, and various laboratory non-pulse sounds. All of these data were 
collected from harbor porpoises. Southall et al. (2007) concluded that 
the existing data indicate that harbor porpoises are likely sensitive 
to a wide range of anthropogenic sounds at low received levels (around 
90 to 120 dB), at least for initial exposures. All recorded exposures 
above 140 dB induced profound and sustained avoidance behavior in wild 
harbor porpoises (Southall et al., 2007). Rapid habituation was noted 
in some but not all studies.
    The studies that address the responses of pinnipeds in water to 
non-pulse sounds include data gathered both in the field and the 
laboratory and related to several different sound sources (of varying 
similarity to chirps), including: AHDs, various non-pulse sounds used 
in underwater data communication, underwater drilling, and construction 
noise. Few studies exist with enough information to include them in the 
analysis. The limited data suggest that exposures to non-pulse sounds 
between 90 and 140 dB generally do not result in strong behavioral 
responses of pinnipeds in water, but no data exist at higher received 
levels (Southall et al., 2007).
    Southall et al. (2007) also addressed behavioral responses of 
marine mammals to impulse sounds. The studies that address the 
responses of low-frequency cetaceans to impulse sounds include data 
gathered in the field and related to two sound sources: airguns and 
explosions. The onset of significant behavioral disturbance varied 
between 120 and 160 dB, depending on species. The studies that address 
the responses of mid-frequency cetaceans to impulse sounds include data 
gathered both in the field and the laboratory and related to several 
different sound sources (of varying similarity to boomers), including: 
small explosives, airgun arrays, pulse sequences, and natural and 
artificial pulses. The data show no clear indication of increasing 
probability and severity of response with increasing received level. 
Behavioral responses seem to vary depending on species and stimuli. 
Data on behavioral responses of high-frequency cetaceans to multiple 
pulses is not available. Although individual elements of some non-pulse 
sources (such as pingers) could be considered pulses, it is believed 
that some mammalian auditory systems perceive them as non-pulse sounds 
(Southall et al., 2007).
    The studies that address the responses of pinnipeds in water to 
impulse sounds include data gathered in the field and related to 
several different sources (of varying similarity to boomers), 
including: small explosives, impact pile driving, and airgun arrays. 
Quantitative data on reactions of pinnipeds to impulse sounds is 
limited, but a general finding is that exposures in the 150 to 180 dB 
range generally have limited potential to induce avoidance behavior 
(Southall et al., 2007).
    Any impacts to marine mammal behavior are expected to be temporary. 
Animals may avoid the area around the survey vessels, thereby reducing 
exposure. Any disturbance to marine mammals is likely to be in the form 
of temporary avoidance or alteration of opportunistic foraging behavior 
near the survey location. In addition, because protected species 
observers would be monitoring a 500-m exclusion zone (much larger than 
the 30-m, 180-dB isopleth in which Level A harassment could occur), 
marine mammal injury or mortality is not anticipated. The protected 
species observers would be on watch to stop survey activities, a 
mitigation measure designed to prevent animals from being exposed to 
injurious level sounds. For these reasons, any changes to marine mammal 
behavior are expected to be temporary and result in a negligible impact 
to affected species and stocks.

Anticipated Effects on Marine Mammal Habitat

    There is no anticipated impact on marine mammal habitat from the 
proposed survey activities. The high resolution geophysical survey 
equipment would not come in contact with the seafloor and would not be 
a source of air or water pollution. Marine mammals may avoid the survey 
area temporarily due to ensonification, but survey activities are not 
expected to result in long-term abandonment of marine mammal habitat. A 
negligible area of seafloor would be temporarily disturbed during the 
collection of geotechnical data.
    Overall, the proposed activity is not expected to cause significant 
impacts on marine mammal habitat or marine mammal prey species in the 
proposed survey area. Therefore, NMFS has preliminarily determined 
impacts to marine mammal habitat are negligible.

Proposed Mitigation

    In order to issue an IHA 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 subsistence uses where relevant.
    Cape Wind Associates proposed, with NMFS' guidance, the following 
mitigation measures to help ensure the least practicable adverse impact 
on marine mammals:

Establishment of an Exclusion Zone

    During all survey activities involving the shallow-penetration and 
medium-penetration subbottom profilers, Cape Wind Associates would 
establish a 500-m radius exclusion zone around each survey vessel. This 
area would be monitored for marine mammals 60 minutes (as stipulated by 
the BOEMRE lease) prior to starting or restarting surveys, and during 
surveys, to ensure that no marine mammals are exposed to injurious 
levels of sound. Monitoring would also continue for 60 minutes after 
survey equipment has been turned off.

Shut Down and Delay Procedures

    If a protected species observer sees a marine mammal within or 
approaching the exclusion zone prior to the start of surveying, the 
observer would notify the appropriate individual who would then be 
required to delay surveying until the marine mammal moves outside of 
the exclusion zone or if the animal has not been resighted for 60 
minutes.

Soft-Start Procedures

    A ``soft-start'' technique would be used at the beginning of each 
survey to allow any marine mammal that may be in the immediate area to 
leave before the sound sources reach full energy.
    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

[[Page 56741]]

adverse 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, NMFS 
has preliminarily determined that the proposed mitigation measures 
provide the means of effecting the least practicable adverse impacts on 
marine mammals 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 IHA 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 incidental take authorizations must include 
the suggested means of accomplishing the necessary monitoring and 
reporting that will result in increased knowledge of the species and of 
the level of taking or impacts on populations of marine mammals that 
are expected to be present in the proposed action area.
    Cape Wind Associates must designate at least one biologically-
trained on-site individual, approved in advance by NMFS to monitor the 
area for marine mammals 60 minutes before, during, and 60 minutes after 
all survey activities and call for shut down if any marine mammal is 
observed within or approaching the designated 500-m exclusion zone. 
Should a marine mammal not included in an incidental take authorization 
be observed at any time within the 500-m exclusion zone, shut down and 
delay procedures would be followed. Cape Wind Associates would also 
provide additional monitoring efforts that would result in increased 
knowledge of marine mammal species in Nantucket Sound. At least one 
NMFS-approved protected species observer would conduct behavioral 
monitoring from the survey vessel at least twice a week to estimate 
take and evaluate the behavioral impacts that survey activities have on 
marine mammals outside of the 500-m exclusion zone. In addition, Cape 
Wind Associates would also send out an additional vessel with a NMFS-
approved protected species observer to collect data on species presence 
and behavior before surveys begin and once a month during survey 
activities.
    Protected species observers would be provided with the equipment 
necessary to effectively monitor for marine mammals (for example, high-
quality binoculars, compass, and range-finder) in order to determine if 
animals have entered into the harassment isopleths and to record 
species, behaviors, and responses to survey activity. These observers 
would be required to submit a report to NMFS within 120 days of 
expiration of the IHA or completion of surveying, whichever comes 
first. The report would include data from marine mammal sightings (for 
example, species, group size, behavior), any observed reactions to 
survey activities, distance between marine mammals and the vessel, and 
sound sources operating at time of sighting.

Estimated Take by Incidental Harassment

    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].
    Based on Cape Wind Associates' application and NMFS' subsequent 
analysis, the impact of the described survey activities may result in, 
at most, short-term modification of behavior by small numbers of marine 
mammals within the action area. Marine mammals may avoid the area or 
change their behavior at time of exposure.
    Current NMFS practice regarding exposure of marine mammals to 
anthropogenic sound is that in order to avoid the potential for injury 
of marine mammals (for example, PTS), cetaceans and pinnipeds should 
not be exposed to impulsive sounds of 180 and 190 dB re: 1 [mu]Pa or 
above, respectively. This level is considered precautionary as it is 
likely that more intense sounds would be required before injury would 
actually occur (Southall et al., 2007). Potential for behavioral 
harassment (Level B) is considered to have occurred when marine mammals 
are exposed to sounds at or above 160 dB re: 1 [mu]Pa for impulse 
sounds and 120 dB re: 1 [mu]Pa for non-pulse noise, but below the 
aforementioned thresholds. These levels are also considered 
precautionary.
    Cape Wind Associates estimated the number of potential takes 
resulting from survey activities by considering species density, the 
zone of influence, and duration of survey activities. More 
specifically, take estimates were calculated by multiplying the 
estimated species density values (n) measured in individuals per square 
kilometers, by the area of the zone of influence in square kilometers, 
times the total number of survey days (d = 137). The zone of influence 
was calculated as a function of the distance a survey vessel with 
deployed boomer would travel in one survey day and the area around the 
boomer where sound levels reach or exceed 160 dB.
    Estimated numbers of species potentially exposed to disturbing 
levels of sound from the boomer (the survey equipment with the largest 
160 dB isopleth) were calculated for minke whales, Atlantic white-sided 
dolphins, harbor porpoises, gray seals, and harbor seals. These 
estimates were calculated by multiplying the low and high end of the 
ranges of species density by the boomer's zone of influence and the 
number of days of survey operation. To be conservative, Cape Wind 
Associates is requesting incidental take based on the highest estimated 
possible species exposures to potentially disturbing levels of sound 
from the boomer. No marine mammals are expected to be exposed to 
injurious levels of sound in excess of 180 dB during survey activities. 
Cape Wind Associates is requesting, and NMFS is proposing, Level B 
harassment of 11 minke whales, 231 Atlantic white-sided dolphins, 138 
harbor porpoises, 398 gray seals, and 99 harbor seals. These numbers 
are conservative because the highest density estimates were used and 
mitigation measures (such as the 500-m exclusion zone, marine mammal 
monitoring, and ramp up procedures) were not considered. These numbers 
indicate the maximum number of animals expected to occur within the 
largest Level B harassment isopleth (444 m). Estimated and proposed 
level of take of each species is less than one percent of each affected 
stock and therefore is considered small in relation to the stock 
estimates previously set forth.

Negligible Impact and Small Numbers Analysis and Determination

    NMFS has defined ``negligible impact'' in 50 CFR 216.103 as ``* * * 
an impact resulting from the specified

[[Page 56742]]

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 number of factors which include, 
but are not limited to, number of anticipated injuries or mortalities 
(none of which would be authorized here), number, nature, intensity, 
and duration of Level B harassment, and the context in which takes 
occur (for instance, will the takes occur in an area or time of 
significance for marine mammals, or are takes occurring to a small, 
localized population?).
    As described above, marine mammals would not be exposed to 
activities or sound levels which would result in injury (for instance, 
PTS), serious injury, or mortality. Anticipated impacts of survey 
activities on marine mammals are temporary behavioral changes due to 
avoidance of the area. All marine mammals in the vicinity of survey 
operations would be transient as no breeding, calving, pupping, 
nursing, or haul-outs overlap with the survey area. The closest 
pinniped haul-outs are 23.5 km (12.7 NM) and 13.7 km (7.4 NM) away on 
Monomoy Island and Muskeget Island, respectively. Marine mammals 
approaching the survey area would likely be traveling or 
opportunistically foraging. The amount of take Cape Wind Associates 
requested, and NMFS proposes to authorize, is considered small (less 
than one percent) relative to the estimated populations of 8,987 minke 
whales, 63,368 Atlantic white-sided dolphins, 89,504 harbor porpoises, 
250,000 gray seals, and 99,340 harbor seals. No affected marine mammals 
are listed under the ESA or considered strategic under the MMPA. Marine 
mammals are expected to avoid the survey area, thereby reducing 
exposure and impacts. No disruption to reproductive behavior is 
anticipated and there is no anticipated effect on annual rates of 
recruitment or survival of affected marine mammals.
    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 determines that Cape Wind Associate's 
survey activities would result in the incidental take of small numbers 
of marine mammals, by Level B harassment, and that the total taking 
would have a negligible impact on the affected species or stocks.

Impact on Availability of Affected Species for Taking for Subsistence 
Uses

    There are no relevant subsistence uses of marine mammals implicated 
by this action.

Endangered Species Act (ESA)

    No marine mammal species listed under the ESA are anticipated to 
occur within the action area. Therefore, section 7 consultation under 
the ESA is not required.

National Environmental Policy Act (NEPA)

    In compliance with the National Environmental Policy Act of 1969 
(42 U.S.C. 4321 et seq.), as implemented by the regulations published 
by the Council on Environmental Quality (40 CFR parts 1500-1508), and 
NOAA Administrative Order 216-6, NMFS is preparing an Environmental 
Assessment (EA) to consider the direct, indirect, and cumulative 
effects to marine mammals and other applicable environmental resources 
resulting from issuance of a one-year IHA and the potential issuance of 
additional authorization for incidental harassment for the ongoing 
project. Upon completion, this EA will be available on the NMFS Web 
site listed in the beginning of this document.

    Dated: September 8, 2011.
James H. Lecky,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2011-23575 Filed 9-13-11; 8:45 am]
BILLING CODE 3510-22-P