Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Operation and Maintenance of a Liquefied Natural Gas Facility off Massachusetts, 24906-24926 [2010-10715]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 75, Number 87 (Thursday, May 6, 2010)]
[Notices]
[Pages 24906-24926]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-10715]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XW09


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to Operation and Maintenance of a 
Liquefied Natural Gas Facility off Massachusetts

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

ACTION:  Notice; proposed incidental harassment authorization; receipt 
of application for letter of authorization; request for comments.

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SUMMARY: NMFS has received an application from Neptune LNG LLC 
(Neptune) for an Incidental Harassment Authorization (IHA) to take 
marine mammals, by harassment, incidental to port commissioning and 
operations, including maintenance and repair activities, at its Neptune 
Deepwater Port. Pursuant to the Marine Mammal Protection Act (MMPA), 
NMFS is requesting comments on its proposal to issue an IHA to Neptune 
to take, by Level B harassment only, several species of marine mammals 
during the specified activity. NMFS is also requesting comments on its 
intent to promulgate regulations governing the take of marine mammals 
over a 5-year period incidental to the same activities described 
herein.

DATES:  Comments and information must be received no later than June 7, 
2010.

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. The mailbox address for providing 
email comments is PR1.0648-XW09@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 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.
    The Maritime Administration (MARAD) and U.S. Coast Guard (USCG) 
Final Environmental Impact Statement (Final EIS) on the Neptune LNG 
Deepwater Port License Application is available for viewing at https://www.regulations.gov by entering the search words ``Neptune LNG.''

FOR FURTHER INFORMATION CONTACT: Candace Nachman, Office of Protected 
Resources, NMFS, (301) 713 2289, ext 156.

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.

[[Page 24907]]

    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 14, 2009, from Neptune for 
the taking, by harassment, of marine mammals incidental to port 
commissioning and operations, including maintenance and repair 
activities, at its Neptune Deepwater Port (Port) facility in 
Massachusetts Bay. NMFS reviewed Neptune's application and identified a 
number of issues requiring further clarification. After addressing 
comments from NMFS, Neptune modified its application and submitted a 
revised application on March 11, 2010. The March 11, 2010, application 
is the one available for public comment (see ADDRESSES) and considered 
by NMFS for this proposed IHA and subsequent promulgation of 
regulations.
    NMFS issued a 1-year IHA to Neptune in June 2008 for the 
construction of the Port (73 FR 33400, June 12, 2008), which expired on 
June 30, 2009. NMFS issued a second 1-year IHA to Neptune for the 
completion of construction and beginning of Port operations on June 26, 
2009 (74 FR 31926, July 6, 2009). This IHA became effective on July 1, 
2009, and expires on June 30, 2010.
    During the period of this third IHA, Neptune intends to commission 
its second shuttle and regasification vessel (SRV) and conduct limited 
port operations. There is also a chance that some maintenance and 
repairs may need to be conducted on the Port facility. The Neptune Port 
is located approximately 22 mi (35 km) northeast of Boston, 
Massachusetts, in Federal waters approximately 260 ft (79 m) in depth. 
The purpose of the Port is the importation of liquefied natural gas 
(LNG) into the New England region. Take of marine mammals may occur 
during port operations from thruster use during maneuvering of the SRVs 
while docking and undocking, occasional weathervaning (turning of a 
vessel at anchor from one direction to another under the influence of 
wind or currents) at the port, and during thruster use of dynamic 
positioning (DP) maintenance vessels should a major repair be 
necessary. Neptune has requested an authorization to take 12 marine 
mammal species by Level B harassment. They are: North Atlantic right 
whale; humpback whale; fin whale; sei whale; minke whale; long-finned 
pilot whale; Atlantic white-sided dolphin; harbor porpoise; common 
dolphin; Risso's dolphin; bottlenose dolphin; and harbor seal. In the 
current IHA, NMFS also authorized take of killer whales and gray seals. 
NMFS has preliminarily determined that it would be appropriate to 
authorize take, by Level B harassment only, of these two species as 
well for port operations and maintenance.

Description of the Specified Activity

    On March 23, 2007, Neptune received a license to own, construct, 
and operate a deepwater port from MARAD. The Port, which will be 
located in Massachusetts Bay, will consist of a submerged buoy system 
to dock specifically designed LNG carriers approximately 22 mi (35 km) 
northeast of Boston, Massachusetts, in Federal waters approximately 260 
ft (79 m) in depth. The two buoys will be separated by a distance of 
approximately 2.1 mi (3.4 km). The locations of the Neptune Port and 
the associated pipeline are shown in Figure 2-1 in Neptune's 
application (see ADDRESSES).
    Neptune anticipates completion of construction and commissioning of 
its first SRV in late April or early May 2010. These activities will be 
completed under the current IHA. Between July 1, 2010, and June 30, 
2011, (the requested time period for this proposed IHA), Neptune plans 
to commission its second SRV and begin limited operations of the Port. 
Upon expiration of this third proposed IHA, Neptune has requested that 
NMFS promulgate regulations and subsequently issue annual Letters of 
Authorization to cover full port operations and any major repairs that 
may be necessary to the Port facility.
    Neptune will be capable of mooring LNG SRVs with a capacity of 
approximately 140,000 cubic meters (m\3\). Up to two SRVs will 
temporarily moor at the Port by means of a submerged unloading buoy 
system. Two separate buoys will allow natural gas to be delivered in a 
continuous flow, without interruption, by having a brief overlap 
between arriving and departing SRVs. The annual average throughput 
capacity will be around 500 million standard cubic feet per day 
(mmscfd) with an initial throughput of 400 mmscfd, and a peak capacity 
of approximately 750 mmscfd.
    The SRVs will be equipped to store, transport, and vaporize LNG and 
to odorize, meter and send out natural gas by means of two 16-in (40.6-
cm) flexible risers and one 24-in (61-cm) subsea flowline. These risers 
and flowline will lead to a 24-in (61-cm) gas transmission pipeline 
connecting the deepwater port to the existing 30-in (76.2-cm) Algonquin 
Hubline\SM\ (Hubline\SM\) located approximately 9 mi (14.5 km) west of 
the Neptune deepwater port location. The Port will have an expected 
operating life of approximately 25 years. Figure 1-1 of Neptune's 
application shows an isometric view of the Port (see ADDRESSES). The 
following subsections describe the operational activities for the Port.

Description of Port Operations

    During Neptune port operations, sound will be generated by the 
regasification of the LNG aboard the SRVs and the use of thrusters by 
vessels maneuvering and maintaining position at the port. Large 
construction-type DP vessels used for major repair of the subsea 
pipeline or unloading facility may be another potential sound source, 
although necessity for such a repair is unlikely. Of these potential 
operations and maintenance/repair sound sources, thruster use for DP is 
the most significant. The following text describes the activities that 
will occur at the port upon its commissioning.

[[Page 24908]]

(1) Vessel Activity
    The SRVs will approach the port using the Boston Harbor Traffic 
Separation Scheme (TSS), entering the TSS within the Great South 
Channel (GSC) and remaining in the TSS until they reach the Boston 
Harbor Precautionary Area. At the Boston Lighted Horn Buoy B (at the 
center of the Boston Harbor Precautionary Area), the SRV will be met by 
a pilot vessel and a support vessel. A pilot will board the SRV, and 
the support vessel will accompany the SRV to the port. SRVs carrying 
LNG typically travel at speeds up to 19.5 knots (36 km/hr); however, 
Neptune SRVs will reduce speed to 10 knots (18.5 km/hr) within the TSS 
year-round in the Off Race Point Seasonal Management Area (SMA) and to 
a maximum of 10 knots (18.5 km/hr) when traveling to and from the buoys 
once exiting the shipping lanes at the Boston Harbor Precautionary 
Area. In addition, Neptune is committed to reducing speed to 10 knots 
in the GSC SMA from April 1 to July 31.
    To supply a continuous flow of natural gas into the pipeline, about 
50 roundtrip SRV transits will take place each year on average (one 
transit every 3.65 days). As an SRV approaches the port, vessel speed 
will gradually be reduced. Upon arrival at the port, one of the 
submerged unloading buoys will be located and retrieved from its 
submerged position by means of a winch and recovery line. The SRV is 
designed for operation in harsh environments and can connect to the 
unloading buoy in up to 11.5 ft (3.5 m) significant wave heights and 
remain operational in up to 36 ft (11 m) significant wave heights 
providing high operational availability.
    The vessel's aft/forward thrusters will be used intermittently. 
Neptune SRVs will use both bow and stern thrusters when approaching the 
unloading buoy and when docking the buoy inside the Submerged Turret 
Loading (STL) compartment, as well as when releasing the buoy after the 
regasifying process is finished. The thrusters will be energized for up 
to 2 hours during the docking process and up to 1 hour during the 
undocking/release process. When energized, the thrusters will rotate at 
a constant RPM with the blades set at zero pitch. There will be little 
cavitation when the thruster propellers idle in this mode. The sound 
levels in this operating mode are expected to be approximately 8 
decibels (dB) less than at 100 percent load, based on measured data 
from other vessels.
    When the thrusters are engaged, the pitch of the blades will be 
adjusted in short bursts for the amount of thrust needed. These short 
bursts will cause cavitation and elevated sound levels. The maximum 
sound level with two thrusters operating at 100 percent load will be 
180 dB re 1 microPa at 1m. This is not the normal operating mode, but a 
worst-case scenario. Typically, thrusters are operated for only seconds 
at a time and not at continuous full loading. These thrusters will be 
engaged for no more than 20 minutes, in total, when docking at the 
buoy. The same applies for the undocking scenario.
    During normal conditions, the vessel will be allowed to weathervane 
on the single-point mooring system. However, aft thrusters may be used 
under certain conditions to maintain the vessel's heading into the wind 
when competing tides operate to push the vessel broadside to the wind. 
Neptune has assumed a total of 200 hr/yr operating under these 
conditions. In these circumstances, the ambient sound will already be 
high because of the wind and associated wave sound.
(2) Regasification System
    Once an SRV is connected to a buoy, the vaporization of LNG and 
send-out of natural gas can begin. Each SRV will be equipped with three 
vaporization units, each with the capacity to vaporize 250 mmscfd. 
Under normal operation, two units will be in service. The third 
vaporization unit will be on standby mode, though all three units could 
operate simultaneously.
(3) Maintenance and Repairs
    Routine maintenance activities typically are short in duration 
(several days or less) and require small vessels (less than 300 gross 
tons) to perform. Activities include attaching and detaching and/or 
cleaning the buoy pick up line to the STL buoy, performing surveys and 
inspections with a remotely operated vehicle, and cleaning or replacing 
parts (e.g., bulbs, batteries, etc.) on the floating navigation buoys. 
Every 7-10 years, Neptune will run an intelligent pig (a gauging/
cleaning device) down the pipeline to assess its condition. This 
particular activity will require several larger, construction-type 
vessels and several weeks to complete.
    Unplanned repairs can be either relatively minor, or in some cases, 
major, requiring several large, construction-type vessels and a 
mitigation program similar to that employed during the construction 
phase of the project. Minor repairs are typically shorter in duration 
and could include fixing flange or valve leaks, replacing faulty 
pressure transducers, or repairing a stuck valve. These kinds of 
repairs require one diver support vessel with three or four anchors to 
hold its position. Minor repairs could take from a few days to 1-2 
weeks depending on the nature of the problem.
    Major repairs are longer in duration and typically require large 
construction vessels similar to those used to install the pipeline and 
set the buoy and anchoring system. These vessels will typically 
mobilize from local ports or the Gulf of Mexico. Major repairs require 
upfront planning, equipment procurement, and mobilization of vessels 
and saturation divers. Examples of major repairs - although unlikely to 
occur - are damage to a riser or umbilical and their possible 
replacement, damage to the pipeline and manifolds, or anchor chain 
replacement. These types of repairs could take 1-4 weeks and possibly 
longer.

Operations Sound

    The acoustic effects of using the thrusters for maneuvering at the 
unloading buoys were modeled by JASCO Research Limited (2005). The 
analysis assumed the use of four thrusters (two bow, two stern) at 100 
percent power during all four seasons. The one-third (1/3)-octave band 
source levels for the thrusters ranged from 148.5 dB re 1 microPa at 1 
m at 2,000 Hertz (Hz) to 174.5 dB re 1 microPa at 1 m at 10 Hz. Figures 
1-2 through 1-5 in Neptune's application show the received sound level 
at 164-ft (50-m) depth at the south unloading buoy during each of the 
four seasons.
    The acoustic effects of operating the regasification system at the 
unloading buoys were also modeled by JASCO Research Limited (2005). In 
addition, supplemental analysis was performed to assess the potential 
underwater acoustic impacts of using the two aft thrusters after 
mooring for maintaining the heading of the vessel in situations when 
competing tides operate to push the vessel broadside to the wind. 
Additionally, Samsung performed an underwater noise study on the newly 
constructed SRV and an evaluation of these data was performed by JASCO 
Applied Sciences. Additional details of all the modeling analyses can 
be found in Appendices B and C of Neptune's application (see 
ADDRESSES). The loudest source of sound during operations at the port 
will be the use of thrusters for dynamic positioning.

Maintenance/Repair Sound

    Acoustic modeling originally performed to predict received levels 
of underwater sound that could result from the construction of Neptune 
also could

[[Page 24909]]

be applicable to major maintenance/repair during operations (see 
Appendices B and C in Neptune's application for a discussion of the 
acoustic modeling methodology employed). Activities considered to be 
potential sound sources during major maintenance/repair activities 
include excavation (jetting) of the flowline or main transmission 
pipeline routes and lowering of materials (pipe, anchors, and chains) 
to the sea floor. These analyses evaluated the potential impacts of 
construction of the flowline and pipeline using surrogate source levels 
for vessels that could be employed during Neptune's construction. One 
surrogate vessel used for modeling purposes was the Castoro II (and 
four accompanying vessels). Figures 1-6 and 1-7 in Neptune's 
application illustrate the worst-case received sound levels that would 
be associated with major maintenance/repair activities along the 
flowline between the two unloading buoys and along the pipeline route 
at the 164-ft (50-m) depth during the spring season if a vessel similar 
to the Castoro II were used.

Description of Marine Mammals in the Area of the Specified Activity

    Massachusetts Bay (as well as the entire Atlantic Ocean) hosts a 
diverse assemblage of marine mammals, including: North Atlantic right 
whale; blue whale; fin whale; sei whale; minke whale; humpback whale; 
killer whale; long-finned pilot whale; sperm whale; Atlantic white-
beaked dolphin; Atlantic white-sided dolphin; bottlenose dolphin; 
common dolphin; harbor porpoise; Risso's dolphin; striped dolphin; gray 
seal; harbor seal; harp seal; and hooded seal. Table 3-1 in Neptune's 
application outlines the marine mammal species that occur in 
Massachusetts Bay and the likelihood of occurrence of each species. Of 
the species listed here, the North Atlantic right, blue, fin, sei, 
humpback, and sperm whales are all listed as endangered under the 
Endangered Species Act (ESA) and as depleted under the MMPA. The 
northern coastal stock of bottlenose dolphins is considered depleted 
under the MMPA. Certain stocks or populations of killer whales are 
listed as endangered under the ESA or depleted under the MMPA; however, 
none of those stocks or populations occurs in the proposed activity 
area.
    Of these species, 14 are expected to occur in the area of Neptune's 
proposed operations. These species include: the North Atlantic right, 
humpback, fin, sei, minke, killer, and long-finned pilot whale; 
Atlantic white-sided, common, Risso's, and bottlenose dolphins; harbor 
porpoise; and harbor and gray seals. Neptune used information from the 
Cetacean and Turtle Assessment Program (CETAP; 1982) and the U.S. 
Navy's Marine Resource Assessment (MRA) for the Northeast Operating 
Areas (DoN, 2005) to estimate densities for the species in the area. 
Nonetheless, NMFS used the data on cetacean distribution within 
Massachusetts Bay, such as those published by the NCCOS (2006), to 
determine density estimates of several species of marine mammals in the 
vicinity of the project area. The explanation for those derivations and 
the actual density estimates are described later in this document (see 
the ``Estimated Take by Incidental Harassment'' section).
    Blue and sperm whales are not commonly found in Massachusetts Bay. 
The sperm whale is generally a deepwater animal, and its distribution 
off the northeastern U.S. is concentrated around the 13,280-ft (4,048-
m) depth contour, with sightings extending offshore beyond the 6,560-ft 
(2,000-m) depth contour. Sperm whales also can be seen in shallow water 
south of Cape Cod from May to November (Cetacean and Turtle Assessment 
Program, 1982). In the North Atlantic, blue whales are most commonly 
sighted in the waters off eastern Canada. Although they are rare in the 
shelf waters of the eastern U.S., occasional sightings of blue whales 
have been made off Cape Cod. Harp and hooded seals are seasonal 
visitors from much further north, seen mostly in the winter and early 
spring. Prior to 1990, harp and hooded seals were sighted only very 
occasionally in the Gulf of Maine, but recent sightings suggest 
increasing numbers of these species now visit these waters (Harris et 
al., 2001, 2002). Juveniles of a third seal species, the ringed seal, 
are seen on occasion as far south as Cape Cod in the winter, but this 
species is considered to be quite rare in these waters (Provincetown 
Center for Coastal Studies, 2005). Due to the rarity of these species 
in the proposed project area and the remote chance they would be 
affected by Neptune's proposed port operations, these species are not 
discussed further in this proposed IHA notice.
    In addition to the 16 cetacean species listed in Table 3-1 in 
Neptune's application, 10 other cetacean species have been recorded for 
Massachusetts as rare vagrants or from strandings (Cardoza et al., 
1999). The following six species of beaked whale are all pelagic and 
recorded mostly as strandings: the northern bottlenose whale; Cuvier's 
beaked whale; Sowerby's beaked whale; Blainville's beaked whale; 
Gervais' beaked whale; and True's beaked whale. Vagrants include the 
beluga whale, a northern species with rare vagrants reported as far 
south as Long Island (Katona et al., 1993); the pantropical spotted 
dolphin and false killer whale, which are primarily tropical species 
with rare sightings in Massachusetts waters (Cardoza et al., 1999); and 
the pygmy sperm whale, which is generally an offshore species that 
occasionally wanders inshore. Due to the rarity of these species in the 
proposed project area and the remote chance they would be affected by 
Neptune's proposed port operations, these species are not discussed 
further in this proposed IHA notice.
    Information on those species that may be impacted by this activity 
is provided in Neptune's application and sections 3.2.3 and 3.2.5 in 
the MARAD/USCG Final EIS on the Neptune LNG proposal (see ADDRESSES). 
Please refer to those documents for more information on these species. 
In addition, general information on these marine mammal species can 
also be found in the NMFS U.S. Atlantic and Gulf of Mexico Marine 
Mammal Stock Report (Waring et al., 2009), which is available at: 
https://www.nefsc.noaa.gov/publications/tm/tm213/. A brief summary on 
several commonly sighted marine mammal species distribution and 
abundance in the vicinity of the action area is provided below.

Humpback Whale

    The highest abundance for humpback whales is distributed primarily 
along a relatively narrow corridor following the 100-m (328 ft) isobath 
across the southern Gulf of Maine from the northwestern slope of 
Georges Bank, south to the GSC, and northward alongside Cape Cod to 
Stellwagen Bank and Jeffreys Ledge. The relative abundance of whales 
increases in the spring with the highest occurrence along the slope 
waters (between the 40- and 140-m, 131- and 459-ft, isobaths) off Cape 
Cod and Davis Bank, Stellwagen Basin and Tillies Basin and between the 
50- and 200-m (164- and 656-ft) isobaths along the inner slope of 
Georges Bank. High abundance was also estimated for the waters around 
Platts Bank. In the summer months, abundance increases markedly over 
the shallow waters (<50 m, or <164 ft) of Stellwagen Bank, the waters 
(100-200 m, 328-656 ft) between Platts Bank and Jeffreys Ledge, the 
steep slopes (between the 30- and 160-m isobaths, 98- and 525-ft 
isobaths) of Phelps and Davis Bank north of the GSC towards Cape Cod, 
and between the 50- and 100-m

[[Page 24910]]

(164- and 328-ft) isobath for almost the entire length of the steeply 
sloping northern edge of Georges Bank. This general distribution 
pattern persists in all seasons except winter when humpbacks remain at 
high abundance in only a few locations including Porpoise and Neddick 
Basins adjacent to Jeffreys Ledge, northern Stellwagen Bank and Tillies 
Basin, and the GSC. The best estimate of abundance for Gulf of Maine, 
formerly western North Atlantic, humpback whales is 847 animals (Waring 
et al., 2009). Current data suggest that the Gulf of Maine humpback 
whale stock is steadily increasing in size, which is consistent with an 
estimated average trend of 3.1 percent in the North Atlantic population 
overall for the period 1979-1993 (Stevick et al., 2003, cited in Waring 
et al., 2009).

Fin Whale

    Spatial patterns of habitat utilization by fin whales are very 
similar to those of humpback whales. Spring and summer high-use areas 
follow the 100-m (328 ft) isobath along the northern edge of Georges 
Bank (between the 50- and 200-m, 164- and 656-ft, isobaths), and 
northward from the GSC (between the 50- and 160-m, 164- and 525-ft, 
isobaths). Waters around Cashes Ledge, Platts Bank, and Jeffreys Ledge 
are all high-use areas in the summer months. Stellwagen Bank is a high-
use area for fin whales in all seasons, with highest abundance 
occurring over the southern Stellwagen Bank in the summer months. In 
fact, the southern portion of Stellwagen Bank National Marine Sanctuary 
(SBNMS) is used more frequently than the northern portion in all months 
except winter, when high abundance is recorded over the northern tip of 
Stellwagen Bank. In addition to Stellwagen Bank, high abundance in 
winter is estimated for Jeffreys Ledge and the adjacent Porpoise Basin 
(100- to 160-m, 328- to 525-ft, isobaths), as well as Georges Basin and 
northern Georges Bank. The best estimate of abundance for the western 
North Atlantic stock of fin whales is 2,269 (Waring et al., 2009). 
Currently, there are insufficient data to determine population trends 
for this species.

Minke Whale

    Like other piscivorus baleen whales, highest abundance for minke 
whale is strongly associated with regions between the 50- and 100-m 
(164- and 328-ft) isobaths, but with a slightly stronger preference for 
the shallower waters along the slopes of Davis Bank, Phelps Bank, GSC, 
and Georges Shoals on Georges Bank. Minke whales are sighted in SBNMS 
in all seasons, with highest abundance estimated for the shallow waters 
(approximately 40 m, 131 ft) over southern Stellwagen Bank in the 
summer and fall months. Platts Bank, Cashes Ledge, Jeffreys Ledge, and 
the adjacent basins (Neddick, Porpoise, and Scantium) also support high 
relative abundance. Very low densities of minke whales remain 
throughout most of the southern Gulf of Maine in winter. The best 
estimate of abundance for the Canadian East Coast stock, which occurs 
from the western half of the Davis Strait to the Gulf of Mexico, of 
minke whales is 3,312 animals (Waring et al., 2009). Currently, there 
are insufficient data to determine population trends for this species.

North Atlantic Right Whale

    North Atlantic right whales are generally distributed widely across 
the southern Gulf of Maine in spring with highest abundance located 
over the deeper waters (100- to 160-m, or 328- to 525-ft, isobaths) on 
the northern edge of the GSC and deep waters (100-300 m, 328-984 ft) 
parallel to the 100-m (328-ft) isobath of northern Georges Bank and 
Georges Basin. High abundance was also found in the shallowest waters 
(<30 m, <98 ft) of Cape Cod Bay (CCB), over Platts Bank and around 
Cashes Ledge. Lower relative abundance is estimated over deep-water 
basins including Wilkinson Basin, Rodgers Basin, and Franklin Basin. In 
the summer months, right whales move almost entirely away from the 
coast to deep waters over basins in the central Gulf of Maine 
(Wilkinson Basin, Cashes Basin between the 160- and 200-m, 525- and 
656-ft, isobaths) and north of Georges Bank (Rogers, Crowell, and 
Georges Basins). Highest abundance is found north of the 100-m (328-ft) 
isobath at the GSC and over the deep slope waters and basins along the 
northern edge of Georges Bank. The waters between Fippennies Ledge and 
Cashes Ledge are also estimated as high-use areas. In the fall months, 
right whales are sighted infrequently in the Gulf of Maine, with 
highest densities over Jeffreys Ledge and over deeper waters near 
Cashes Ledge and Wilkinson Basin. In winter, CCB, Scantum Basin, 
Jeffreys Ledge, and Cashes Ledge were the main high-use areas. Although 
SBNMS does not appear to support the highest abundance of right whales, 
sightings within SBNMS are reported for all four seasons, albeit at low 
relative abundance. Highest sighting within SBNMS occurs along the 
southern edge of the Bank.
    The western North Atlantic population size was estimated to be at 
least 345 individuals in 2005 based on a census of individual whales 
identified using photo-identification techniques (Waring et al., 2009). 
This value is a minimum and does not include animals that were alive 
prior to 2003 but not recorded in the individual sightings database as 
seen from December 1, 2003, to October 10, 2008. It also does not 
include calves known to be born during 2005 or any other individual 
whale seen during 2005 but not yet entered into the catalog (Waring et 
al., 2009). Examination of the minimum alive population index 
calculated from the individual sightings database, as it existed on 
October 10, 2008, for the years 1990-2005 suggests a positive trend in 
numbers. These data reveal a significant increase in the number of 
catalogued whales alive during this period but with significant 
variation due to apparent losses exceeding gains during 1998-1999. Mean 
growth rate for the period 1990-2005 was 1.8 percent (Waring et al., 
2009).

Long-finned Pilot Whale

    The long-finned pilot whale is more generally found along the edge 
of the continental shelf (a depth of 100 to 1,000 m, or 328 to 3,280 
ft), choosing areas of high relief or submerged banks in cold or 
temperate shoreline waters. This species is split into two subspecies: 
the Northern and Southern subspecies. The Southern subspecies is 
circumpolar with northern limits of Brazil and South Africa. The 
Northern subspecies, which could be encountered during operation of the 
Neptune Port facility, ranges from North Carolina to Greenland (Reeves 
et al., 2002; Wilson and Ruff, 1999). In the western North Atlantic, 
long-finned pilot whales are pelagic, occurring in especially high 
densities in winter and spring over the continental slope, then moving 
inshore and onto the shelf in summer and autumn following squid and 
mackerel populations (Reeves et al., 2002). They frequently travel into 
the central and northern Georges Bank, GSC, and Gulf of Maine areas 
during the summer and early fall (May and October; NOAA, 1993). 
According to the SAR, the best population estimate for the western 
North Atlantic stock of long-finned pilot whale is 31,139 individuals 
(Waring et al., 2009). Currently, there are insufficient data to 
determine population trends for the long-finned pilot whale.

Sei Whale

    The sei whale is the least likely of all the baleen whale species 
to occur near the Neptune Port. However, there were a couple of 
sightings in the general vicinity of the port facility during the 
construction phase (Neptune Marine

[[Page 24911]]

Mammal Monitoring Weekly Reports, 2008). The Nova Scotia stock of sei 
whales ranges from the continental shelf waters of the northeastern 
U.S. and extends northeastward to south of Newfoundland. The southern 
portion of the species range during spring and summer includes the 
northern portions of the U.S. Atlantic Exclusive Economic Zone: the 
Gulf of Maine and Georges Bank. Spring is the period of greatest 
abundance in U.S. waters, with sightings concentrated along the eastern 
margin of Georges Bank and into the Northeast Channel area and along 
the southwestern edge of Georges Bank in the area of Hydrographer 
Canyon (CETAP, 1982). The best estimate of abundance for this stock is 
386 animals (Waring et al., 2009). There are insufficient data to 
determine population trends for this species.

Atlantic White-sided Dolphin

    In spring, summer and fall, Atlantic white-sided dolphins are 
widespread throughout the southern Gulf of Maine, with the high-use 
areas widely located on either side of the 100-m (328-ft) isobath along 
the northern edge of Georges Bank, and north from the GSC to Stellwagen 
Bank, Jeffreys Ledge, Platts Bank, and Cashes Ledge. In spring, high-
use areas exist in the GSC, northern Georges Bank, the steeply sloping 
edge of Davis Bank, and Cape Cod, southern Stellwagen Bank, and the 
waters between Jeffreys Ledge and Platts Bank. In summer, there is a 
shift and expansion of habitat toward the east and northeast. High-use 
areas occur along most of the northern edge of Georges Bank between the 
50- and 200-m (164- and 656-ft) isobaths and northward from the GSC 
along the slopes of Davis Bank and Cape Cod. High sightings are also 
recorded over Truxton Swell, Wilkinson Basin, Cashes Ledge and the 
bathymetrically complex area northeast of Platts Bank. High sightings 
of white-sided dolphin are recorded within SBNMS in all seasons, with 
highest density in summer and most widespread distributions in spring 
located mainly over the southern end of Stellwagen Bank. In winter, 
high sightings were recorded at the northern tip of Stellwagen Bank and 
Tillies Basin.
    A comparison of spatial distribution patterns for all baleen whales 
and all porpoises and dolphins combined showed that both groups have 
very similar spatial patterns of high- and low-use areas. The baleen 
whales, whether piscivorus or planktivorous, are more concentrated than 
the dolphins and porpoises. They utilize a corridor that extends 
broadly along the most linear and steeply sloping edges in the southern 
Gulf of Maine indicated broadly by the 100 m (328 ft) isobath. 
Stellwagen Bank and Jeffreys Ledge support a high abundance of baleen 
whales throughout the year. Species richness maps indicate that high-
use areas for individual whales and dolphin species co-occurred, 
resulting in similar patterns of species richness primarily along the 
southern portion of the 100-m (328-ft) isobath extending northeast and 
northwest from the GSC. The southern edge of Stellwagen Bank and the 
waters around the northern tip of Cape Cod are also highlighted as 
supporting high cetacean species richness. Intermediate to high numbers 
of species are also calculated for the waters surrounding Jeffreys 
Ledge, the entire Stellwagen Bank, Platts Bank, Fippennies Ledge, and 
Cashes Ledge. The best estimate of abundance for the western North 
Atlantic stock of white-sided dolphins is 63,368 (Waring et al., 2009). 
A trend analysis has not been conducted for this species.

Killer Whale, Common Dolphin, Bottlenose Dolphin, Risso's Dolphin, and 
Harbor Porpoise

    Although these five species are some of the most widely distributed 
small cetacean species in the world (Jefferson et al., 1993), they are 
not commonly seen in the vicinity of the project area in Massachusetts 
Bay (Wiley et al., 1994; NCCOS, 2006; Northeast Gateway Marine Mammal 
Monitoring Weekly Reports, 2007; Neptune Marine Mammal Monitoring 
Weekly Reports, 2008). The total number of killer whales off the 
eastern U.S. coast is unknown, and present data are insufficient to 
calculate a minimum population estimate or to determine the population 
trends for this stock (Blaylock et al., 1995). The best estimate of 
abundance for the western North Atlantic stock of common dolphins is 
120,743 animals, and a trend analysis has not been conducted for this 
species (Waring et al., 2007). There are several stocks of bottlenose 
dolphins found along the eastern U.S. from Maine to Florida. The stock 
that may occur in the area of the Neptune Port is the western North 
Atlantic coastal northern migratory stock of bottlenose dolphins. The 
best estimate of abundance for this stock is 7,489 animals (Waring et 
al., 2009). There are insufficient data to determine the population 
trend for this stock. The best estimate of abundance for the western 
North Atlantic stock of Risso's dolphins is 20,479 animals (Waring et 
al., 2009). There are insufficient data to determine the population 
trend for this stock. The best estimate of abundance for the Gulf of 
Maine/Bay of Fundy stock of harbor porpoise is 89,054 animals (Waring 
et al., 2009). A trend analysis has not been conducted for this 
species.

Harbor and Gray Seals

    In the U.S. western North Atlantic, both harbor and gray seals are 
usually found from the coast of Maine south to southern New England and 
New York (Waring et al., 2007).
    Along the southern New England and New York coasts, harbor seals 
occur seasonally from September through late May (Schneider and Payne, 
1983). In recent years, their seasonal interval along the southern New 
England to New Jersey coasts has increased (deHart, 2002). In U.S. 
waters, harbor seal breeding and pupping normally occur in waters north 
of the New Hampshire/Maine border, although breeding has occurred as 
far south as Cape Cod in the early part of the 20th century (Temte et 
al., 1991; Katona et al., 1993). The best estimate of abundance for the 
western North Atlantic stock of harbor seals is 99,340 animals (Waring 
et al., 2009). Between 1981 and 2001, the uncorrected counts of seals 
increased from 10,543 to 38,014, an annual rate of 6.6 percent (Gilbert 
et al., 2005, cited in Waring et al., 2009).
    Although gray seals are often seen off the coast from New England 
to Labrador, within U.S. waters, only small numbers of gray seals have 
been observed pupping on several isolated islands along the Maine coast 
and in Nantucket-Vineyard Sound, Massachusetts (Katona et al., 1993; 
Rough, 1995). In the late 1990s, a year-round breeding population of 
approximately 400 gray seals was documented on outer Cape Cod and 
Muskeget Island (Waring et al., 2007). Depending on the model used, the 
minimum estimate for the Canadian gray seal population was estimated to 
range between 125,541 and 169,064 animals (Trzcinski et al., 2005, 
cited in Waring et al., 2009); however, present data are insufficient 
to calculate the minimum population estimate for U.S. waters. Waring et 
al. (2009) note that gray seal abundance in the U.S. Atlantic is likely 
increasing, but the rate of increase is unknown.

Brief Background on Marine Mammal Hearing

    When considering the influence of various kinds of sound on the 
marine environment, it is necessary to understand that different kinds 
of marine life are sensitive to different frequencies of sound. Based 
on available behavioral data, audiograms derived using auditory evoked 
potential

[[Page 24912]]

techniques, anatomical modeling, and other data, Southall et al. (2007) 
designate ``functional hearing groups'' for marine mammals and estimate 
the lower and upper frequencies of functional hearing of the groups. 
The functional groups and the associated frequencies are indicated 
below (though animals are less sensitive to sounds at the outer edge of 
their functional range and most sensitive to sounds of frequencies 
within a smaller range somewhere in the middle of their functional 
hearing range):
     Low frequency cetaceans (13 species of mysticetes): 
functional hearing is estimated to occur between approximately 7 Hz and 
22 kHz;
     Mid-frequency cetaceans (32 species of dolphins, six 
species of larger toothed whales, and 19 species of beaked and 
bottlenose whales): functional hearing is estimated to occur between 
approximately 150 Hz and 160 kHz;
     High frequency cetaceans (eight species of true porpoises, 
six species of river dolphins, Kogia, the franciscana, and four species 
of cephalorhynchids): functional hearing is estimated to occur between 
approximately 200 Hz and 180 kHz; and
     Pinnipeds in Water: functional hearing is estimated to 
occur between approximately 75 Hz and 75 kHz, with the greatest 
sensitivity between approximately 700 Hz and 20 kHz.
    As mentioned previously in this document, 14 marine mammal species 
(12 cetacean and two pinniped species) are likely to occur in the 
Neptune Port area. Of the 12 cetacean species likely to occur in 
Neptune's project area, five are classified as low frequency cetaceans 
(i.e., North Atlantic right, humpback, fin, minke, and sei whales), six 
are classified as mid-frequency cetaceans (i.e., killer and pilot 
whales and bottlenose, common, Risso's, and Atlantic white-sided 
dolphins), and one is classified as a high-frequency cetacean (i.e., 
harbor porpoise) (Southall et al., 2007).

Potential Effects of the Specified Activity on Marine Mammals

    Potential effects of Neptune's proposed port operations and 
maintenance/repair activities would most likely be acoustic in nature. 
LNG port operations and maintenance/repair activities introduce sound 
into the marine environment. Potential acoustic effects on marine 
mammals relate to sound produced by thrusters during maneuvering of the 
SRVs while docking and undocking, occasional weathervaning at the port, 
and during thruster use of DP maintenance vessels should a major repair 
be necessary. The potential effects of sound from the proposed 
activities associated with the Neptune Port might include one or more 
of the following: tolerance; masking of natural sounds; behavioral 
disturbance; non-auditory physical effects; and, at least in theory, 
temporary or permanent hearing impairment (Richardson et al., 1995). 
However, for reasons discussed later in this document, it is unlikely 
that there would be any cases of temporary, or especially permanent, 
hearing impairment resulting from these activities. As outlined in 
previous NMFS documents, the effects of noise on marine mammals are 
highly variable, and can be categorized as follows (based on Richardson 
et al., 1995):
    (1) The noise may be too weak to be heard at the location of the 
animal (i.e., lower than the prevailing ambient noise level, the 
hearing threshold of the animal at relevant frequencies, or both);
    (2) The noise may be audible but not strong enough to elicit any 
overt behavioral response;
    (3) The noise may elicit reactions of variable conspicuousness and 
variable relevance to the well being of the marine mammal; these can 
range from temporary alert responses to active avoidance reactions such 
as vacating an area at least until the noise event ceases but 
potentially for longer periods of time;
    (4) Upon repeated exposure, a marine mammal may exhibit diminishing 
responsiveness (habituation), or disturbance effects may persist; the 
latter is most likely with sounds that are highly variable in 
characteristics, infrequent, and unpredictable in occurrence, and 
associated with situations that a marine mammal perceives as a threat;
    (5) Any anthropogenic noise that is strong enough to be heard has 
the potential to reduce (mask) the ability of a marine mammal to hear 
natural sounds at similar frequencies, including calls from 
conspecifics, and underwater environmental sounds such as surf noise;
    (6) If mammals remain in an area because it is important for 
feeding, breeding, or some other biologically important purpose even 
though there is chronic exposure to noise, it is possible that there 
could be noise-induced physiological stress; this might in turn have 
negative effects on the well-being or reproduction of the animals 
involved; and
    (7) Very strong sounds have the potential to cause a temporary or 
permanent reduction in hearing sensitivity. In terrestrial mammals, and 
presumably marine mammals, received sound levels must far exceed the 
animal's hearing threshold for there to be any temporary threshold 
shift (TTS) in its hearing ability. For transient sounds, the sound 
level necessary to cause TTS is inversely related to the duration of 
the sound. Received sound levels must be even higher for there to be 
risk of permanent hearing impairment. In addition, intense acoustic or 
explosive events may cause trauma to tissues associated with organs 
vital for hearing, sound production, respiration and other functions. 
This trauma may include minor to severe hemorrhage.

Tolerance

    Numerous studies have shown that underwater sounds from industry 
activities are often readily detectable by marine mammals in the water 
at distances of many kilometers. Numerous studies have also shown that 
marine mammals at distances more than a few kilometers away often show 
no apparent response to industry activities of various types (Miller et 
al., 2005). This is often true even in cases when the sounds must be 
readily audible to the animals based on measured received levels and 
the hearing sensitivity of that mammal group. Although various baleen 
whales, toothed whales, and (less frequently) pinnipeds have been shown 
to react behaviorally to underwater sound such as airgun pulses or 
vessels under some conditions, at other times mammals of all three 
types have shown no overt reactions (e.g., Malme et al., 1986; 
Richardson et al., 1995; Madsen and Mohl, 2000; Croll et al., 2001; 
Jacobs and Terhune, 2002; Madsen et al., 2002; Miller et al., 2005). In 
general, pinnipeds and small odontocetes seem to be more tolerant of 
exposure to some types of underwater sound than are baleen whales. 
Richardson et al. (1995) found that vessel noise does not seem to 
strongly affect pinnipeds that are already in the water. Richardson et 
al. (1995) went on to explain that seals on haul-outs sometimes respond 
strongly to the presence of vessels and at other times appear to show 
considerable tolerance of vessels, and (Brueggeman et al., 1992; cited 
in Richardson et al., 1995) observed ringed seals hauled out on ice 
pans displaying short-term escape reactions when a ship approached 
within 0.25-0.5 mi (0.4-0.8 km).

Masking

    Masking is the obscuring of sounds of interest by other sounds, 
often at similar frequencies. Marine mammals are highly dependent on 
sound, and their ability to recognize sound signals amid

[[Page 24913]]

noise is important in communication, predator and prey detection, and, 
in the case of toothed whales, echolocation. Even in the absence of 
manmade sounds, the sea is usually noisy. Background ambient noise 
often interferes with or masks the ability of an animal to detect a 
sound signal even when that signal is above its absolute hearing 
threshold. Natural ambient noise includes contributions from wind, 
waves, precipitation, other animals, and (at frequencies above 30 kHz) 
thermal noise resulting from molecular agitation (Richardson et al., 
1995). Background noise also can include sounds from human activities. 
Masking of natural sounds can result when human activities produce high 
levels of background noise. Conversely, if the background level of 
underwater noise is high (e.g., on a day with strong wind and high 
waves), an anthropogenic noise source will not be detectable as far 
away as would be possible under quieter conditions and will itself be 
masked. Ambient noise is highly variable on continental shelves 
(Thompson, 1965; Myrberg, 1978; Chapman et al., 1998; Desharnais et 
al., 1999). This inevitably results in a high degree of variability in 
the range at which marine mammals can detect anthropogenic sounds.
    Although masking is a natural phenomenon to which marine mammals 
must adapt, the introduction of strong sounds into the sea at 
frequencies important to marine mammals increases the severity and 
frequency of occurrence of masking. For example, if a baleen whale is 
exposed to continuous low-frequency noise from an industrial source, 
this will reduce the size of the area around that whale within which it 
can hear the calls of another whale. In general, little is known about 
the importance to marine mammals of detecting sounds from conspecifics, 
predators, prey, or other natural sources. In the absence of much 
information about the importance of detecting these natural sounds, it 
is not possible to predict the impacts if mammals are unable to hear 
these sounds as often, or from as far away, because of masking by 
industrial noise (Richardson et al., 1995). In general, masking effects 
are expected to be less severe when sounds are transient than when they 
are continuous.
    Although some degree of masking is inevitable when high levels of 
manmade broadband sounds are introduced into the sea, marine mammals 
have evolved systems and behavior that function to reduce the impacts 
of masking. Structured signals, such as the echolocation click 
sequences of small toothed whales, may be readily detected even in the 
presence of strong background noise because their frequency content and 
temporal features usually differ strongly from those of the background 
noise (Au and Moore, 1988, 1990). The components of background noise 
that are similar in frequency to the sound signal in question primarily 
determine the degree of masking of that signal. Low-frequency 
industrial noise, such as shipping, has little or no masking effect on 
high frequency echolocation sounds. Redundancy and context can also 
facilitate detection of weak signals. These phenomena may help marine 
mammals detect weak sounds in the presence of natural or manmade noise. 
Most masking studies in marine mammals present the test signal and the 
masking noise from the same direction. The sound localization abilities 
of marine mammals suggest that, if signal and noise come from different 
directions, masking would not be as severe as the usual types of 
masking studies might suggest (Richardson et al., 1995). The dominant 
background noise may be highly directional if it comes from a 
particular anthropogenic source such as a ship or industrial site. 
Directional hearing may significantly reduce the masking effects of 
these noises by improving the effective signal-to-noise ratio. In the 
cases of high-frequency hearing by the bottlenose dolphin, beluga 
whale, and killer whale, empirical evidence confirms that masking 
depends strongly on the relative directions of arrival of sound signals 
and the masking noise (Penner et al., 1986; Dubrovskiy, 1990; Bain et 
al., 1993; Bain and Dahlheim, 1994). Toothed whales, and probably other 
marine mammals as well, have additional capabilities besides 
directional hearing that can facilitate detection of sounds in the 
presence of background noise. There is evidence that some toothed 
whales can shift the dominant frequencies of their echolocation signals 
from a frequency range with a lot of ambient noise toward frequencies 
with less noise (Au et al., 1974, 1985; Moore and Pawloski, 1990; 
Thomas and Turl, 1990; Romanenko and Kitain, 1992; Lesage et al., 
1999). A few marine mammal species are known to increase the source 
levels of their calls in the presence of elevated sound levels 
(Dahlheim, 1987; Au, 1993; Lesage et al., 1999; Terhune, 1999).
    These data demonstrating adaptations for reduced masking pertain 
mainly to the very high frequency echolocation signals of toothed 
whales. There is less information about the existence of corresponding 
mechanisms at moderate or low frequencies or in other types of marine 
mammals. For example, Zaitseva et al. (1980) found that, for the 
bottlenose dolphin, the angular separation between a sound source and a 
masking noise source had little effect on the degree of masking when 
the sound frequency was 18 kHz, in contrast to the pronounced effect at 
higher frequencies. Directional hearing has been demonstrated at 
frequencies as low as 0.5-2 kHz in several marine mammals, including 
killer whales (Richardson et al., 1995). This ability may be useful in 
reducing masking at these frequencies. In summary, high levels of noise 
generated by anthropogenic activities may act to mask the detection of 
weaker biologically important sounds by some marine mammals. This 
masking may be more prominent for lower frequencies. For higher 
frequencies, such as used in echolocation by toothed whales, several 
mechanisms are available that may allow them to reduce the effects of 
such masking.

Disturbance

    Disturbance can induce a variety of effects, such as subtle changes 
in behavior, more conspicuous dramatic changes in activities, and 
displacement. Disturbance is one of the main concerns of the potential 
impacts of manmade noise on marine mammals. For many species and 
situations, there is no detailed information about reactions to noise. 
While there are no specific studies available on the reactions of 
marine mammals to sounds produced by a LNG facility, information from 
studies of marine mammal reactions to other types of continuous and 
transient anthropogenic sound (e.g., drillships) are described here as 
a proxy.
    Behavioral reactions of marine mammals to sound are difficult to 
predict because they are dependent on numerous factors, including 
species, state of maturity, experience, current activity, reproductive 
state, time of day, and weather. If a marine mammal does react to an 
underwater sound by changing its behavior or moving a small distance, 
the impacts of that change may not be important to the individual, the 
stock, or the species as a whole. However, if a sound source displaces 
marine mammals from an important feeding or breeding area for a 
prolonged period, impacts on the animals could be important. Based on 
the literature reviewed in Richardson et al. (1995), it is apparent 
that most small and medium-sized toothed whales exposed to prolonged or 
repeated underwater sounds are unlikely to be displaced unless the 
overall received level is at

[[Page 24914]]

least 140 dB re 1 microPa (rms). The limited available data indicate 
that the sperm whale is sometimes, though not always, more responsive 
than other toothed whales. Baleen whales probably have better hearing 
sensitivities at lower sound frequencies, and in several studies have 
been shown to react to continuous sounds at received sound levels of 
approximately 120 dB re 1 microPa (rms). Toothed whales appear to 
exhibit a greater variety of reactions to manmade underwater noise than 
do baleen whales. Toothed whale reactions can vary from approaching 
vessels (e.g., to bow ride) to strong avoidance, while baleen whale 
reactions range from neutral (little or no change in behavior) to 
strong avoidance. In general, pinnipeds seem more tolerant of, or at 
least habituate more quickly to, potentially disturbing underwater 
noise than do cetaceans.
    Baleen Whales - Baleen whales sometimes show behavioral changes in 
response to received broadband drillship noises of 120 dB (rms) or 
greater. On their summer range in the Beaufort Sea, bowhead whales (a 
species closely related to the right whale) reacted to drillship noises 
within 4-8 km (2.5-5 mi) of the drillship at received levels 20 dB 
above ambient, or about 118 dB (Richardson et al., 1990). Reactions 
were stronger at the onset of the sound (Richardson et al., 1995). 
Migrating bowhead whales avoided an area with a radius of 10-20 km 
(6.2-12.4 mi) around drillships and their associated support vessels, 
corresponding to a received noise level around 115 dB (Greene, 1987; 
Koski and Johnson, 1987; Hall et al., 1994; Davies, 1997; Schick and 
Urban, 2000). For gray whales off California, the predicted reaction 
zone around a semi-submersible drill rig was less than 1 km (0.62 mi), 
at received levels of approximately 120 dB (Malme et al., 1983, 1984). 
Humpback whales showed no obvious avoidance response to broadband 
drillship noises at a received level of 116 dB (Malme et al., 1985).
    Reactions of baleen whales to boat noises include changes in 
swimming direction and speed, blow rate, and the frequency and kinds of 
vocalizations (Richardson et al., 1995). Baleen whales, especially 
minke whales, occasionally approach stationary or slow-moving boats, 
but more commonly avoid boats. Avoidance is strongest when boats 
approach directly or when vessel noise changes abruptly (Watkins, 1986; 
Beach and Weinrich, 1989). Humpback whales responded to boats at 
distances of at least 0.5-1 km (0.31-0.62 mi), and avoidance and other 
reactions have been noted in several areas at distances of several 
kilometers (Jurasz and Jurasz, 1979; Dean et al., 1985; Bauer, 1986; 
Bauer and Herman, 1986).
    During some activities and at some locations, humpbacks exhibit 
little or no reaction to boats (Watkins, 1986). Some baleen whales seem 
to show habituation to frequent boat traffic. Over 25 years of 
observations in Cape Cod waters, minke whales' reactions to boats 
changed from frequent positive interactions (i.e., reactions of 
apparent curiosity or reactions that appeared to provide some reward to 
the animal) to a general lack of interest (i.e., ignored the stimuli), 
while humpback whales reactions changed from being often negative to 
being often positive, and fin whales reactions changed from being 
mostly negative (i.e., sudden changes from activity to inactivity or a 
display of agonistic responses) to being mostly uninterested (Watkins, 
1986).
    North Atlantic right whales also display variable responses to 
boats. There may be an initial orientation away from a boat, followed 
by a lack of observable reaction (Atkins and Swartz, 1989). A slowly 
moving boat can approach a right whale, but an abrupt change in course 
or engine speed usually elicits a reaction (Goodyear, 1989; Mayo and 
Marx, 1990; Gaskin, 1991). When approached by a boat, right whale 
mothers will interpose themselves between the vessel and calf and will 
maintain a low profile (Richardson et al., 1995). In a long-term study 
of baleen whale reactions to boats, while other baleen whale species 
appeared to habituate to boat presence over the 25-year period, right 
whales continued to show either uninterested or negative reactions to 
boats with no change over time (Watkins, 1986).
    Biassoni et al. (2000) and Miller et al. (2000) reported behavioral 
observations for humpback whales exposed to a low-frequency sonar 
stimulus (160- to 330-Hz frequency band; 42-s tonal signal repeated 
every 6 min; source levels 170 to 200 dB) during playback experiments. 
Exposure to measured received levels ranging from 120 to 150 dB 
resulted in variability in humpback singing behavior. Croll et al. 
(2001) investigated responses of foraging fin and blue whales to the 
same low frequency active sonar stimulus off southern California. 
Playbacks and control intervals with no transmission were used to 
investigate behavior and distribution on time scales of several weeks 
and spatial scales of tens of kilometers. The general conclusion was 
that whales remained feeding within a region for which 12 to 30 percent 
of exposures exceeded 140 dB.
    Frankel and Clark (1998) conducted playback experiments with 
wintering humpback whales using a single speaker producing a low-
frequency ``M-sequence'' (sine wave with multiple-phase reversals) 
signal in the 60 to 90 Hz band with output of 172 dB at 1 m. For 11 
playbacks, exposures were between 120 and 130 dB re 1 microPa (rms) and 
included sufficient information regarding individual responses. During 
eight of the trials, there were no measurable differences in tracks or 
bearings relative to control conditions, whereas on three occasions, 
whales either moved slightly away from (n = 1) or towards (n = 2) the 
playback speaker during exposure. The presence of the source vessel 
itself had a greater effect than did the M-sequence playback.
    Finally, Nowacek et al. (2004) used controlled exposures to 
demonstrate behavioral reactions of northern right whales to various 
non-pulse sounds. Playback stimuli included ship noise, social sounds 
of conspecifics, and a complex, 18-min ``alert'' sound consisting of 
repetitions of three different artificial signals. Ten whales were 
tagged with calibrated instruments that measured received sound 
characteristics and concurrent animal movements in three dimensions. 
Five out of six exposed whales reacted strongly to alert signals at 
measured received levels between 130 and 150 dB (i.e., ceased foraging 
and swam rapidly to the surface). Two of these individuals were not 
exposed to ship noise, and the other four were exposed to both stimuli. 
These whales reacted mildly to conspecific signals. Seven whales, 
including the four exposed to the alert stimulus, had no measurable 
response to either ship sounds or actual vessel noise.
    Odontocetes - In reviewing responses of cetaceans with best hearing 
in mid-frequency ranges, which includes toothed whales, Southall et al. 
(2007) reported that combined field and laboratory data for mid-
frequency cetaceans exposed to non-pulse sounds did not lead to a clear 
conclusion about received levels coincident with various behavioral 
responses. In some settings, individuals in the field showed profound 
(significant) behavioral responses to exposures from 90 to 120 dB, 
while others failed to exhibit such responses for exposure to received 
levels from 120 to 150 dB. Contextual variables other than exposure 
received level, and probable species differences, are the likely 
reasons for this variability. Context, including the fact that captive 
subjects were often directly reinforced with food for tolerating noise 
exposure, may also explain why there was great

[[Page 24915]]

disparity in results from field and laboratory conditions-exposures in 
captive settings generally exceeded 170 dB before inducing behavioral 
responses.
    Dolphins and other toothed whales may show considerable tolerance 
of floating and bottom-founded drill rigs and their support vessels. 
Kapel (1979) reported many pilot whales within visual range of 
drillships and their support vessels off West Greenland. Beluga whales 
have been observed swimming within 100-150 m (328-492 ft) of an 
artificial island while drilling was underway (Fraker and Fraker, 1979, 
1981), and within 1,600 m (1 mi) of the drillship Explorer I while the 
vessel was engaged in active drilling (Fraker and Fraker, 1981). Some 
belugas in Bristol Bay