[Federal Register Volume 86, Number 212 (Friday, November 5, 2021)]
[Notices]
[Pages 61164-61181]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-24164]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648- XB546]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to the Falls Bridge Replacement 
Project in Blue Hill, Maine

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

ACTION: Notice; proposed incidental harassment authorization; request 
for comments on proposed authorization and possible renewal.

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SUMMARY: NMFS has received a request from the Maine Department of 
Transportation (MEDOT) for authorization to take marine mammals 
incidental to the Falls Bridge Replacement Project in Blue Hill, Maine. 
Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting 
comments on its proposal to issue an incidental harassment 
authorization (IHA) to incidentally take marine mammals during the 
specified activities. NMFS is also requesting comments on a possible 
one-year renewal that could be issued under certain circumstances and 
if all requirements are met, as described in Request for Public 
Comments at the end of this document. NMFS will consider public 
comments prior to making any final decision on the issuance of the 
requested MMPA authorizations and agency responses will be summarized 
in the final notice of our decision.

[[Page 61165]]


DATES: Comments and information must be received no later than December 
6, 2021.

ADDRESSES: Comments should be addressed to Jolie Harrison, Chief, 
Permits and Conservation Division, Office of Protected Resources, 
National Marine Fisheries Service and should be sent to 
[email protected].
    Instructions: NMFS is not responsible for comments sent by any 
other method, to any other address or individual, or received after the 
end of the comment period. Comments received electronically, including 
all attachments, must not exceed a 25-megabyte file size. Attachments 
to electronic comments will be accepted in Microsoft Word or Excel or 
Adobe PDF file formats only. All comments received are a part of the 
public record and will generally be posted online at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act without change. All personal identifying 
information (e.g., name, address) voluntarily submitted by the 
commenter may be publicly accessible. Do not submit confidential 
business information or otherwise sensitive or protected information.

FOR FURTHER INFORMATION CONTACT: Dwayne Meadows, Ph.D., Office of 
Protected Resources, NMFS, (301) 427-8401. Electronic copies of the 
application and supporting documents, as well as a list of the 
references cited in this document, may be obtained online at: https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act. In case of problems accessing these 
documents, please call the contact listed above.

SUPPLEMENTARY INFORMATION:

Background

    The MMPA prohibits the ``take'' of marine mammals, with certain 
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 
et seq.) direct the Secretary of Commerce (as delegated to NMFS) 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 incidental take authorization may be 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) and will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for taking for subsistence uses 
(where relevant). Further, NMFS must prescribe the permissible methods 
of taking and other ``means of effecting the least practicable adverse 
impact'' on the affected species or stocks and their habitat, paying 
particular attention to rookeries, mating grounds, and areas of similar 
significance, and on the availability of the species or stocks for 
taking for certain subsistence uses (referred to in shorthand as 
``mitigation''); and requirements pertaining to the mitigation, 
monitoring and reporting of the takings are set forth.
    The definitions of all applicable MMPA statutory terms cited above 
are included in the relevant sections below.

National Environmental Policy Act

    To comply with the National Environmental Policy Act of 1969 (NEPA; 
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A, 
NMFS must review our proposed action (i.e., the issuance of an IHA) 
with respect to potential impacts on the human environment.
    This action is consistent with categories of activities identified 
in Categorical Exclusion B4 (IHAs with no anticipated serious injury or 
mortality) of the Companion Manual for NOAA Administrative Order 216-
6A, which do not individually or cumulatively have the potential for 
significant impacts on the quality of the human environment and for 
which we have not identified any extraordinary circumstances that would 
preclude this categorical exclusion. Accordingly, NMFS has 
preliminarily determined that the issuance of the proposed IHA 
qualifies to be categorically excluded from further NEPA review.
    We will review all comments submitted in response to this document 
prior to concluding our NEPA process or making a final decision on the 
IHA request.

Summary of Request

    On October 7, 2021, NMFS received an application from MEDOT 
requesting an IHA to take small numbers of seven species (harbor seal 
(Phoca vitulina), gray seal (Halichoerus grypus), harp seal (Pagophilus 
groenlandicus), hooded seal (Cystophora cristata), harbor porpoise 
(Phocoena phocoena), Atlantic white-sided dolphin (Lagenorhynchus 
acutus) and common dolphin (Delphinus delphis)) of marine mammals 
incidental to pile driving and removal associated with the project. The 
application was deemed adequate and complete on October 20, 2021. 
MEDOT's request is for take of a small number of these species by Level 
B harassment and a small amount of Level A harassment take for harbor 
seals. Neither MEDOT nor NMFS expects serious injury or mortality to 
result from this activity and, therefore, an IHA is appropriate.

Description of Proposed Activity

Overview

    The purpose of the project is to address the structural deficiency 
of the Falls Bridge and improve public safety. In-water pile driving is 
needed to create temporary work trestles and support towers and a 
temporary bridge for vehicle traffic during construction. The work in 
this application involves the installation of up to 95 24-inch diameter 
steel piles and then the removal of all piles at the conclusion of the 
project. The project will take no more than 80 days of in-water pile 
work.
    The pile driving/removal can result in take of marine mammals from 
sound in the water which may result in behavioral harassment or 
auditory injury.

Dates and Duration

    The IHA is proposed to be effective for one year from July 1, 2022 
through June 30, 2023. Exact start dates may change depending on 
completion of contracting and other environmental compliance, but the 
IHA will be valid for one year.

Specific Geographic Region

    The project is located in the town of Blue Hill, Maine, 
approximately 28 miles (45 kilometers) southeast of Bangor. The Falls 
Bridge carries State Route 175 over the Salt Pond Outlet (Figure 1). 
The Falls Bridge provides the principal opening between the Salt Pond, 
a one square mile (2.59 square kilometer (km)) tidal estuary, and the 
Atlantic Ocean. With each tidal cycle a significant volume of water 
passes through the bridge opening, generating high flow velocities and 
a ``hydraulic jump'' during mid-tide periods that is colloquially 
referred to as the reversing falls. The reversing falls, the Falls 
Bridge itself, and the natural beauty of the area has caused the Falls 
Bridge to become a destination for sightseers, nature enthusiasts, and 
recreationists.
BILLING CODE 4910-81-P

[[Page 61166]]

[GRAPHIC] [TIFF OMITTED] TN05NO21.034

BILLING CODE 4910-81-C
    The Falls Bridge lies on the transition between an estuarine 
unconsolidated bottom subtidal system associated with the Salt Pond to 
the west, and a marine unconsolidated bottom subtidal system associated 
with Blue Hill Bay to the east. Where the transition occurs, 
immediately under the bridge and a few hundred feet into Blue Hill Bay, 
lies a small strip of marine intertidal rocky shore (bedrock 
dominated). Salinity in the area ranges from 25-35 parts per million, 
water depth is 0 to 50 feet (0 to 15.2 meters (m)), and water 
temperature ranges from 38 to 58 degrees Fahrenheit. Ongoing small 
vessel and recreation/commercial activities (e.g., lobster fishing, sea 
urchin harvest, sea duck hunting) in Blue Hill Bay likely result in 
elevated in-air and underwater sound conditions intermittently 
throughout the year. Background sound levels likely vary seasonally, 
with the greatest amount of in-air noise associated with the tourism 
during the summer months, and fishing/hunting activities during late 
fall and early winter months.

Detailed Description of Specific Activity

    The project consists of creating a temporary bridge for vehicle 
traffic during work on the Falls Bridge; this will require the 
installation (and then removal when the project is complete) of 15 24-
inch steel pipe piles. Work on the main bridge deck is not expected to 
incidentally harass marine mammals, however in order to facilitate that 
work, one or two large trestles (up to 100 foot by 125 foot (30.5 by 38 
m) long) would be placed in the water next to the bridge. These 
trestles would require the installation of up to 60 24-inch diameter

[[Page 61167]]

steel pipe piles. In addition to the temporary work trestles and 
temporary bridge, MEDOT anticipates the need for four temporary support 
towers during the demolition and removal of the existing bridge 
superstructure. The temporary support towers will be placed at the 
corners of the tied arch, approximately 20 feet in from the existing 
bridge abutments. Up to 5 24-inch steel pipe piles will be needed to 
support each of the temporary support towers, for a total of 20 24-inch 
steel pipe piles.
    In total then the project involves installation and removal of 95 
24-inch diameter steel pipe piles. It is expected that all 95 piles 
will be installed in rock sockets (holes) in the bedrock created by 
down-the-hole (DTH) equipment. Impact pile driving will be used to seat 
the piles and potentially drive them through softer substrates. For 
piles driven in the center of the channel under the bridge (mostly for 
the trestles), additional lateral stability may require the use of 
rebar tension anchors drilled deeper into the substrate in the center 
of the piles and connected to the piles once installed. This would be 
accomplished by using an 8-inch diameter DTH bit. It is expected that 
no more than 65 of the 95 piles would require these tension anchors. 
Once the work on the bridge is complete all 95 piles will be removed 
using a vibratory hammer.
    The DTH and impact hammer installation and vibratory extraction of 
the piles is expected to take up to 80 days of in-water work. These 
actions could produce underwater sound at levels that could result in 
the injury or behavioral harassment of marine mammal species.
    Proposed mitigation, monitoring, and reporting measures are 
described in detail later in this document (please see Proposed 
Mitigation and Proposed Monitoring and Reporting).

Description of Marine Mammals in the Area of Specified Activities

    Sections 3 and 4 of the application summarize available information 
regarding status and trends, distribution and habitat preferences, and 
behavior and life history, of the potentially affected species. 
Additional information regarding population trends and threats may be 
found in NMFS's Stock Assessment Reports (SARs; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and more general information about these species 
(e.g., physical and behavioral descriptions) may be found on NMFS's 
website (https://www.fisheries.noaa.gov/find-species).
    Table 1 lists all species with expected potential for occurrence in 
the project area and summarizes information related to the population 
or stock, including regulatory status under the MMPA and Endangered 
Species Act (ESA) and potential biological removal (PBR), where known. 
For taxonomy, we follow Committee on Taxonomy (2021). PBR is defined by 
the MMPA as the maximum number of animals, not including natural 
mortalities, that may be removed from a marine mammal stock while 
allowing that stock to reach or maintain its optimum sustainable 
population (as described in NMFS's SARs). While no mortality is 
anticipated or authorized here, PBR and annual serious injury and 
mortality from anthropogenic sources are included here as gross 
indicators of the status of the species and other threats.
    Marine mammal abundance estimates presented in this document 
represent the total number of individuals that make up a given stock or 
the total number estimated within a particular study or survey area. 
NMFS's stock abundance estimates for most species represent the total 
estimate of individuals within the geographic area, if known, that 
comprises that stock. For some species, this geographic area may extend 
beyond U.S. waters. All managed stocks in this region are assessed in 
NMFS's 2021 U.S. Atlantic Draft SARs (e.g., Hayes et al., 2021).

                    Table 1--Species That Spatially Co-Occur With the Activity to the Degree That Take Is Reasonably Likely To Occur
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                         ESA/MMPA status;    Stock abundance (CV,
             Common name                  Scientific name               Stock             strategic (Y/N)      Nmin, most recent       PBR     Annual M/
                                                                                                \1\          abundance survey) \2\               SI \3\
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                                                             Order Cetartiodactyla--Cetacea
                                            Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
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Family Delphinidae:
    Atlantic white-sided dolphin....  Lagenorhynchus acutus..  Western North Atlantic.  -, -; N             93,233 (0.71, 54,443,         544         26
                                                                                                             See SAR).
    Common dolphin..................  Delphinus delphis......  Western North Atlantic.  -, -; N             172,8974 (0.21,              1452        399
                                                                                                             145,216, 2016).
Family Phocoenidae (porpoises):
    Harbor porpoise.................  Phocoena phocoena......  Gulf of Maine/Bay of     -, -; N             95,543 (0.31; 74,034;         851        217
                                                                Fundy.                                       2016).
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                                                         Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Phocidae (earless seals):
    Harbor seal.....................  Phoca vitulina.........  Western North Atlantic.  -; N                61,336 (0.08; 57,637,       1,729        339
                                                                                                             2018).
    Gray seal \4\...................  Halichoerus grypus.....  Western North Atlantic.  -; N                27,300 (0.22, 22,785,       1,389      4,453
                                                                                                             2018).
    Harp seal.......................  Pagophilus               Western North Atlantic.  -; N                7,600,000 (UNK,           426,000    178,573
                                       groenlandicus.                                                        7,100,000, 2019).
    Hooded seal.....................  Cystophora cristata....  Western North Atlantic.  -; N                UNK (UNK, UNK, See            UNK      1,680
                                                                                                             SAR).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance.
\3\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
  commercial fisheries, ship strike). Annual Mortality/Serious Injury (M/SI) often cannot be determined precisely and is in some cases presented as a
  minimum value or range. A CV associated with estimated mortality due to commercial fisheries is presented in some cases.
\4\ The NMFS stock abundance estimate applies to U.S. population only, however the actual stock abundance is approximately 505,000. The PBR value is
  estimated for the U.S. population, while the M/SI estimate is provided for the entire gray seal stock (including animals in Canada).


[[Page 61168]]

    Harbor seal, gray seal, harbor porpoise, Atlantic white-sided 
dolphin and common dolphin spatially co-occur with the activity to the 
degree that take is reasonably likely to occur, and we have proposed 
authorizing take of these species. Harp seal and hooded seal are rare 
in the project area but could occur and we have proposed authorizing 
take of these species. All species that could potentially occur in the 
proposed survey areas are included in the MEDOT's IHA application (see 
application, Section 3). Humpback whale, North Atlantic right whale, 
minke whale, sei whale and fin whale could potentially occur in the 
area. However the spatial and temporal occurrence of these species is 
very rare, typically further offshore, the species are readily 
observed, and the applicant would shut down pile driving if they enter 
the project area (see Proposed Monitoring and Reporting section). Thus 
take is not expected to occur, and they are not discussed further.
    The best available data for marine mammal presence in the vicinity 
of the project is the result of monitoring surveys completed in 
preparation for the project. The Shaw Institute (formerly Marine and 
Environmental Research Institute) was contracted by MEDOT to provide 
baseline data on seasonal marine mammal observations near the Falls 
Bridge. Surveys took place on 74 days from June 27, 2017 to July 24, 
2018.

Atlantic White-Sided Dolphin

    White-sided dolphins occur in temperate and sub-polar waters of the 
North Atlantic, primarily in continental shelf waters to the 100-m 
depth contour from central West Greenland to North Carolina (Waring et 
al., 2019). The Gulf of Maine stock is most common in continental shelf 
waters from Hudson Canyon to Georges Bank, and in the Gulf of Maine and 
lower Bay of Fundy. Sighting data indicate seasonal shifts in 
distribution (Northridge et al., 1997). During January to May, low 
numbers of white-sided dolphins are found from Georges Bank to Jeffreys 
Ledge (off New Hampshire), with even lower numbers south of Georges 
Bank. From June through September, large numbers of white-sided 
dolphins are found from Georges Bank to the lower Bay of Fundy. From 
October to December, white-sided dolphins occur at intermediate 
densities from southern Georges Bank to southern Gulf of Maine (Payne 
and Heinemann, 1990). This species moves closer inshore in the summers 
and offshore in the winters.

Common Dolphin

    The common dolphin occurs world-wide in temperate to subtropical 
seas. In the North Atlantic, common dolphins commonly occur over the 
continental shelf between the 100-m and 2,000-m isobaths and over 
prominent underwater topography and east to the mid-Atlantic Ridge 
(Waring et al., 2019). This species is found between Cape Hatteras and 
Georges Bank from mid-January to May, although they migrate onto the 
northeast edge of Georges Bank in the fall where large aggregations 
occur (Kenney and Vigness-Raposa, 2009).

Harbor Porpoise

    The harbor porpoise is typically found in colder waters in the 
northern hemisphere. In the western North Atlantic Ocean, harbor 
porpoises range from Greenland to as far south as North Carolina (Barco 
and Swingle, 2014). They are commonly found in bays, estuaries, and 
harbors less than 200 meters deep (NOAA Fisheries, 2016c). Harbor 
porpoises in the United States are made up of the Gulf of Maine/Bay of 
Fundy stock. Gulf of Maine/Bay of Fundy stock are concentrated in the 
Gulf of Maine in the summer, but are widely dispersed from Maine to New 
Jersey in the winter. South of New Jersey, harbor porpoises occur at 
lower densities. Migrations to and from the Gulf of Maine do not follow 
a defined route (NOAA Fisheries, 2016c).
    In most areas, harbor porpoise occur in small groups of just a few 
individuals. There were 7 harbor porpoise sighted by the Shaw team 
(Shaw Institute, 2018).

Harbor Seal

    The harbor seal occurs in arctic and temperate coastal waters 
throughout the northern hemisphere, including on both the east and west 
coasts of the United States. On the east coast, harbor seals can be 
found from the Canadian Arctic down to Georgia (Blaylock, 1985). Harbor 
seals occur year-round in Canada and Maine and seasonally (September-
May) from southern New England to New Jersey (NOAA Fisheries, 2016d). 
The range of harbor seals appears to be shifting as they are regularly 
reported further south than they were historically.
    Harbor seals are central-place foragers (Orians and Pearson, 1979) 
and tend to exhibit strong site fidelity within season and across 
years, generally forage close to haulout sites, and repeatedly visit 
specific foraging areas (Suryan and Harvey, 1998; Thompson et al., 
1998). Harbor seals tend to forage at night and haul out during the day 
with a peak in the afternoon between 1 p.m. and 4 p.m. (London et al., 
2001).
    Harbor seals were the most common marine mammal observed by the 
Shaw team near Falls Bridge, making up 89 percent of the marine mammals 
observed (Shaw Institute, 2018).

Gray Seal

    The gray seal occurs on both coasts of the Northern Atlantic Ocean 
and are divided into three major populations (NOAA Fisheries 2016b). 
The western north Atlantic stock occurs in eastern Canada and the 
northeastern United States, occasionally as far south as North 
Carolina. Gray seals inhabit rocky coasts and islands, sandbars, ice 
shelves and icebergs (NOAA Fisheries 2016b). In the United States, gray 
seals congregate in the summer to give birth at four established 
colonies in Massachusetts and Maine (NOAA Fisheries 2016b). From 
September through May, they disperse and can be abundant as far south 
as New Jersey. The range of gray seals appears to be shifting as they 
are regularly being reported further south than they were historically 
(Rees et al. 2016). There was 1 gray seal observed by the Shaw team 
near the bridge (Shaw Institute 2018).

Harp Seal

    The harp seal is a highly migratory species, its range extending 
throughout the Arctic and North Atlantic Oceans. The world's harp seal 
population is separated into three stocks, based on associations with 
specific locations of breeding activities: (1) Off eastern Canada, (2) 
on the West Ice off eastern Greenland, and (3) in the White Sea off the 
coast of Russia. The largest stock, which includes two herds that breed 
either off the coast of Newfoundland/Labrador or near the Magdelan 
Islands in the Gulf of St. Lawrence, is equivalent to the western North 
Atlantic stock under the MMPA. The best estimate of abundance for 
western North Atlantic harp seals, based on the last survey (in 2012) 
is 7.4 million, with a minimum estimate of 6.9 million (Waring et al., 
2020). In U.S. waters, the species has an increasing presence since the 
1990s, evidenced by increasing numbers of sightings and strandings in 
the coastal waters between Maine and New Jersey (Waring et al., 2020). 
Harp seals that occur in the United States generally occur in New 
England waters from January through May (Waring et al., 2020).

Hooded Seal

    Hooded seals are generally found in deeper waters or on drifting 
pack ice.

[[Page 61169]]

The world population of hooded seals has been divided into three 
stocks, which coincide with specific breeding areas, as follows: (1) 
Northwest Atlantic, (2) Greenland Sea, and (3) White Sea (Waring et 
al., 2020). In the United States, they are considered members of the 
western North Atlantic stock and generally occur in New England waters 
from January through May and further south in the summer and fall 
seasons (Waring et al., 2019).The hooded seal is a highly migratory 
species, and its range can extend from the Canadian arctic to Puerto 
Rico. In U.S. waters, the species has an increasing presence in the 
coastal waters between Maine and Florida (Waring et al., 2019).
    Population abundance of hooded seals in the western North Atlantic 
is derived from pup production estimates, which are developed from 
whelping pack surveys. The most recent population estimate in the 
western North Atlantic was derived in 2005. There have been no recent 
surveys conducted or population estimates developed for this species. 
The 2005 best population estimate for hooded seals is 593,500 
individuals, with a minimum population estimate of 543,549 individuals 
(Waring et al., 2019). Currently, not enough data are available to 
determine what percentage of this estimate may represent the population 
within U.S. waters.

Marine Mammal Hearing

    Hearing is the most important sensory modality for marine mammals 
underwater, and exposure to anthropogenic sound can have deleterious 
effects. To appropriately assess the potential effects of exposure to 
sound, it is necessary to understand the frequency ranges marine 
mammals are able to hear. Current data indicate that not all marine 
mammal species have equal hearing capabilities (e.g., Richardson et 
al., 1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect 
this, Southall et al. (2007) recommended that marine mammals be divided 
into functional hearing groups based on directly measured or estimated 
hearing ranges on the basis of available behavioral response data, 
audiograms derived using auditory evoked potential techniques, 
anatomical modeling, and other data. Note that no direct measurements 
of hearing ability have been successfully completed for mysticetes 
(i.e., low-frequency cetaceans). Subsequently, NMFS (2018) described 
generalized hearing ranges for these marine mammal hearing groups. 
Generalized hearing ranges were chosen based on the approximately 65 
decibel (dB) threshold from the normalized composite audiograms, with 
the exception for lower limits for low-frequency cetaceans where the 
lower bound was deemed to be biologically implausible and the lower 
bound from Southall et al. (2007) retained. Marine mammal hearing 
groups and their associated hearing ranges are provided in Table 2.

                  Table 2--Marine Mammal Hearing Groups
                              [NMFS, 2018]
------------------------------------------------------------------------
            Hearing group                 Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen  7 Hz to 35 kHz.
 whales).
Mid-frequency (MF) cetaceans          150 Hz to 160 kHz.
 (dolphins, toothed whales, beaked
 whales, bottlenose whales).
High-frequency (HF) cetaceans (true   275 Hz to 160 kHz.
 porpoises, Kogia, river dolphins,
 cephalorhynchid, Lagenorhynchus
 cruciger & L. australis).
Phocid pinnipeds (PW) (underwater)    50 Hz to 86 kHz.
 (true seals).
Otariid pinnipeds (OW) (underwater)   60 Hz to 39 kHz.
 (sea lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
  composite (i.e., all species within the group), where individual
  species' hearing ranges are typically not as broad. Generalized
  hearing range chosen based on ~65 dB threshold from normalized
  composite audiogram, with the exception for lower limits for LF
  cetaceans (Southall et al., 2007) and PW pinniped (approximation).

    The pinniped functional hearing group was modified from Southall et 
al. (2007) on the basis of data indicating that phocid species have 
consistently demonstrated an extended frequency range of hearing 
compared to otariids, especially in the higher frequency range 
(Hemil[auml] et al., 2006; Kastelein et al., 2009; Reichmuth and Holt, 
2013).
    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2018) for a review of available information. 
The baleen whales are in the low-frequency hearing group, the dolphins 
are in the mid-frequency hearing group, harbor porpoises are in the 
high frequency hearing group, and the seals are in the phocid group.

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    This section includes a summary and discussion of the ways that 
components of the specified activity may impact marine mammals and 
their habitat. The Estimated Take section later in this document 
includes a quantitative analysis of the number of individuals that are 
expected to be taken by this activity. The Negligible Impact Analysis 
and Determination section considers the content of this section, the 
Estimated Take section, and the Proposed Mitigation section, to draw 
conclusions regarding the likely impacts of these activities on the 
reproductive success or survivorship of individuals and how those 
impacts on individuals are likely to impact marine mammal species or 
stocks.
    Acoustic effects on marine mammals during the specified activity 
can occur from impact and vibratory pile driving and removal and DTH. 
The effects of underwater noise from MEDOT's proposed activities have 
the potential to result in Level A or Level B harassment of marine 
mammals in the action area.

Description of Sound Sources

    The marine soundscape is comprised of both ambient and 
anthropogenic sounds. Ambient sound is defined as the all-encompassing 
sound in a given place and is usually a composite of sound from many 
sources both near and far (ANSI 1995). The sound level of an area is 
defined by the total acoustical energy being generated by known and 
unknown sources. These sources may include physical (e.g., waves, wind, 
precipitation, earthquakes, ice, atmospheric sound), biological (e.g., 
sounds produced by marine mammals, fish, and invertebrates), and 
anthropogenic sound (e.g., vessels, dredging, aircraft, construction).
    The sum of the various natural and anthropogenic sound sources at 
any given location and time--which comprise ``ambient'' or 
``background'' sound--depends not only on the source levels (as 
determined by current weather conditions and levels of

[[Page 61170]]

biological and shipping activity) but also on the ability of sound to 
propagate through the environment. In turn, sound propagation is 
dependent on the spatially and temporally varying properties of the 
water column and sea floor, and is frequency-dependent. As a result of 
the dependence on a large number of varying factors, ambient sound 
levels can be expected to vary widely over both coarse and fine spatial 
and temporal scales. Sound levels at a given frequency and location can 
vary by 10-20 dB from day to day (Richardson et al., 1995). The result 
is that, depending on the source type and its intensity, sound from the 
specified activity may be a negligible addition to the local 
environment or could form a distinctive signal that may affect marine 
mammals.
    In-water construction activities associated with the project would 
include impact and vibratory pile driving and removal and DTH. The 
sounds produced by these activities fall into one of two general sound 
types: Impulsive and non-impulsive. Impulsive sounds (e.g., explosions, 
gunshots, sonic booms, impact pile driving) are typically transient, 
brief (less than 1 second), broadband, and consist of high peak sound 
pressure with rapid rise time and rapid decay (ANSI, 1986; NIOSH, 1998; 
NMFS, 2018). Non-impulsive sounds (e.g., machinery operations such as 
drilling or dredging, vibratory pile driving, underwater chainsaws, 
pile clippers, and active sonar systems) can be broadband, narrowband 
or tonal, brief or prolonged (continuous or intermittent), and 
typically do not have the high peak sound pressure with raid rise/decay 
time that impulsive sounds do (ANSI 1995; NIOSH 1998; NMFS 2018). The 
distinction between these two sound types is important because they 
have differing potential to cause physical effects, particularly with 
regard to hearing (e.g., Ward 1997 in Southall et al., 2007).
    Three types of pile hammers would be used on this project: Impact, 
vibratory, and DTH. Impact hammers operate by repeatedly dropping and/
or pushing a heavy piston onto a pile to drive the pile into the 
substrate. Sound generated by impact hammers is characterized by rapid 
rise times and high peak levels, a potentially injurious combination 
(Hastings and Popper, 2005). Vibratory hammers install piles by 
vibrating them and allowing the weight of the hammer to push them into 
the sediment. Vibratory hammers produce significantly less sound than 
impact hammers. Peak Sound pressure Levels (SPLs) may be 180 dB or 
greater, but are generally 10 to 20 dB lower than SPLs generated during 
impact pile driving of the same-sized pile (Oestman et al., 2009). Rise 
time is slower, reducing the probability and severity of injury, and 
sound energy is distributed over a greater amount of time (Nedwell and 
Edwards, 2002; Carlson et al., 2005).
    A DTH hammer is essentially a drill bit that drills through the 
bedrock using a rotating function like a normal drill, in concert with 
a hammering mechanism operated by a pneumatic (or sometimes hydraulic) 
component integrated into to the DTH hammer to increase speed of 
progress through the substrate (i.e., it is similar to a ``hammer 
drill'' hand tool). Rock socketing involves using DTH equipment to 
create a hole in the bedrock inside which the pile is placed to give it 
lateral and longitudinal strength. Tension anchoring involves creating 
a smaller hole inside and deeper than the rock socket. A long piece of 
rebar is inserted in this hole, grouted or cemented in place, and then 
the top of the rebar is connected to the top of the pile to increase 
pile stability. The sounds produced by the DTH method contain both a 
continuous, non-impulsive component from the drilling action and an 
intermittent, impulsive component from the hammering effect. Therefore, 
we treat DTH systems as both intermittent, impulsive (for Level A 
thresholds) and continuous, non-impulsive (for Level B thresholds) 
sound source types simultaneously.
    The likely or possible impacts of MEDOT's proposed activity on 
marine mammals could involve both non-acoustic and acoustic stressors. 
Potential non-acoustic stressors could result from the physical 
presence of the equipment, vessels, and personnel; however, any impacts 
to marine mammals are expected to primarily be acoustic in nature. 
Acoustic stressors include effects of heavy equipment operation during 
pile installation and removal.

Acoustic Impacts

    The introduction of anthropogenic noise into the aquatic 
environment from pile driving equipment is the primary means by which 
marine mammals may be harassed from the MEDOT's specified activity. In 
general, animals exposed to natural or anthropogenic sound may 
experience physical and psychological effects, ranging in magnitude 
from none to severe (Southall et al., 2007). Generally, exposure to 
pile driving and removal and other construction noise has the potential 
to result in auditory threshold shifts and behavioral reactions (e.g., 
avoidance, temporary cessation of foraging and vocalizing, changes in 
dive behavior). Exposure to anthropogenic noise can also lead to non-
observable physiological responses such an increase in stress hormones. 
Additional noise in a marine mammal's habitat can mask acoustic cues 
used by marine mammals to carry out daily functions such as 
communication and predator and prey detection. The effects of pile 
driving and demolition noise on marine mammals are dependent on several 
factors, including, but not limited to, sound type (e.g., impulsive vs. 
non-impulsive), the species, age and sex class (e.g., adult male vs. 
mom with calf), duration of exposure, the distance between the pile and 
the animal, received levels, behavior at time of exposure, and previous 
history with exposure (Wartzok et al., 2004; Southall et al., 2007). 
Here we discuss physical auditory effects (threshold shifts) followed 
by behavioral effects and potential impacts on habitat.
    NMFS defines a noise-induced threshold shift (TS) as a change, 
usually an increase, in the threshold of audibility at a specified 
frequency or portion of an individual's hearing range above a 
previously established reference level (NMFS, 2018). The amount of 
threshold shift is customarily expressed in dB. A TS can be permanent 
or temporary. As described in NMFS (2018), there are numerous factors 
to consider when examining the consequence of TS, including, but not 
limited to, the signal temporal pattern (e.g., impulsive or non-
impulsive), likelihood an individual would be exposed for a long enough 
duration or to a high enough level to induce a TS, the magnitude of the 
TS, time to recovery (seconds to minutes or hours to days), the 
frequency range of the exposure (i.e., spectral content), the hearing 
and vocalization frequency range of the exposed species relative to the 
signal's frequency spectrum (i.e., how animal uses sound within the 
frequency band of the signal; e.g., Kastelein et al., 2014), and the 
overlap between the animal and the source (e.g., spatial, temporal, and 
spectral).
    Permanent Threshold Shift (PTS)--NMFS defines PTS as a permanent, 
irreversible increase in the threshold of audibility at a specified 
frequency or portion of an individual's hearing range above a 
previously established reference level (NMFS 2018). Available data from 
humans and other terrestrial mammals indicate that a 40 dB threshold 
shift approximates PTS onset (see Ward et al., 1958, 1959; Ward, 1960; 
Kryter et al., 1966; Miller, 1974; Ahroon et al., 1996; Henderson and 
Hu, 2008). PTS levels for marine mammals are

[[Page 61171]]

estimates, with the exception of a single study unintentionally 
inducing PTS in a harbor seal (Kastak et al., 2008), there are no 
empirical data measuring PTS in marine mammals, largely due to the fact 
that, for various ethical reasons, experiments involving anthropogenic 
noise exposure at levels inducing PTS are not typically pursued or 
authorized (NMFS, 2018).
    Temporary Threshold Shift (TTS)--A temporary, reversible increase 
in the threshold of audibility at a specified frequency or portion of 
an individual's hearing range above a previously established reference 
level (NMFS, 2018). Based on data from cetacean TTS measurements (see 
Southall et al., 2007), a TTS of 6 dB is considered the minimum 
threshold shift clearly larger than any day-to-day or session-to-
session variation in a subject's normal hearing ability (Schlundt et 
al., 2000; Finneran et al., 2000, 2002). As described in Finneran 
(2016), marine mammal studies have shown the amount of TTS increases 
with cumulative sound exposure level (SELcum) in an 
accelerating fashion: At low exposures with lower SELcum, 
the amount of TTS is typically small and the growth curves have shallow 
slopes. At exposures with higher SELcum, the growth curves 
become steeper and approach linear relationships with the noise SEL.
    Depending on the degree (elevation of threshold in dB), duration 
(i.e., recovery time), and frequency range of TTS, and the context in 
which it is experienced, TTS can have effects on marine mammals ranging 
from discountable to serious (similar to those discussed in auditory 
masking, below). For example, a marine mammal may be able to readily 
compensate for a brief, relatively small amount of TTS in a non-
critical frequency range that takes place during a time when the animal 
is traveling through the open ocean, where ambient noise is lower and 
there are not as many competing sounds present. Alternatively, a larger 
amount and longer duration of TTS sustained during time when 
communication is critical for successful mother/calf interactions could 
have more serious impacts. We note that reduced hearing sensitivity as 
a simple function of aging has been observed in marine mammals, as well 
as humans and other taxa (Southall et al., 2007), so we can infer that 
strategies exist for coping with this condition to some degree, though 
likely not without cost.
    Currently, TTS data only exist for four species of cetaceans 
(bottlenose dolphin, beluga whale (Delphinapterus leucas), harbor 
porpoise, and Yangtze finless porpoise (Neophocoena asiaeorientalis)) 
and five species of pinnipeds exposed to a limited number of sound 
sources (i.e., mostly tones and octave-band noise) in laboratory 
settings (Finneran, 2015). TTS was not observed in trained spotted 
(Phoca largha) and ringed (Pusa hispida) seals exposed to impulsive 
noise at levels matching previous predictions of TTS onset (Reichmuth 
et al., 2016). In general, harbor seals and harbor porpoises have a 
lower TTS onset than other measured pinniped or cetacean species 
(Finneran, 2015). The potential for TTS from impact pile driving 
exists. After exposure to playbacks of impact pile driving sounds (rate 
2760 strikes/hour) in captivity, mean TTS increased from 0 dB after 15 
minute exposure to 5 dB after 360 minute exposure; recovery occurred 
within 60 minutes (Kastelein et al., 2016). Additionally, the existing 
marine mammal TTS data come from a limited number of individuals within 
these species. No data are available on noise-induced hearing loss for 
mysticetes. For summaries of data on TTS in marine mammals or for 
further discussion of TTS onset thresholds, please see Southall et al. 
(2007), Finneran and Jenkins (2012), Finneran (2015), and Table 5 in 
NMFS (2018).
    Installing piles for this project requires impact pile driving and 
DTH. There would likely be pauses in activities producing the sound 
during each day. Given these pauses and that many marine mammals are 
likely moving through the action area and not remaining for extended 
periods of time, the potential for TS declines.
    Behavioral Harassment--Exposure to noise from pile driving and 
removal also has the potential to behaviorally disturb marine mammals. 
Available studies show wide variation in response to underwater sound; 
therefore, it is difficult to predict specifically how any given sound 
in a particular instance might affect marine mammals perceiving the 
signal. 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; NRC, 2005).
    Disturbance may result in changing durations of surfacing and 
dives, number of blows per surfacing, or moving direction and/or speed; 
reduced/increased vocal activities; changing/cessation of certain 
behavioral activities (such as socializing or feeding); visible startle 
response or aggressive behavior (such as tail/fluke slapping or jaw 
clapping); avoidance of areas where sound sources are located. 
Pinnipeds may increase their haul out time, possibly to avoid in-water 
disturbance (Thorson and Reyff, 2006). Behavioral responses to sound 
are highly variable and context-specific and any reactions depend on 
numerous intrinsic and extrinsic factors (e.g., species, state of 
maturity, experience, current activity, reproductive state, auditory 
sensitivity, time of day), as well as the interplay between factors 
(e.g., Richardson et al., 1995; Wartzok et al., 2004; Southall et al., 
2007; Weilgart, 2007; Archer et al., 2010). Behavioral reactions can 
vary not only among individuals but also within an individual, 
depending on previous experience with a sound source, context, and 
numerous other factors (Ellison et al., 2012), and can vary depending 
on characteristics associated with the sound source (e.g., whether it 
is moving or stationary, number of sources, distance from the source). 
In general, pinnipeds seem more tolerant of, or at least habituate more 
quickly to, potentially disturbing underwater sound than do cetaceans, 
and generally seem to be less responsive to exposure to industrial 
sound than most cetaceans. Please see Appendices B and C of Southall et 
al. (2007) for a review of studies involving marine mammal behavioral 
responses to sound.
    Disruption of feeding behavior can be difficult to correlate with 
anthropogenic sound exposure, so it is usually inferred by observed 
displacement from known foraging areas, the appearance of secondary 
indicators (e.g., bubble nets or sediment plumes), or changes in dive 
behavior. As for other types of behavioral response, the frequency, 
duration, and temporal pattern of signal presentation, as well as 
differences in species sensitivity, are likely contributing factors to 
differences in response in any given circumstance (e.g., Croll et al., 
2001; Nowacek et al., 2004; Madsen et al., 2006; Yazvenko et al., 
2007). A determination of whether foraging disruptions incur fitness 
consequences would require information on or estimates of the energetic 
requirements of the affected individuals and the relationship between 
prey availability, foraging effort and success, and the life history 
stage of the animal.
    In 2016, the Alaska Department of Transportation and Public 
Facilities (ADOT&PF) documented observations

[[Page 61172]]

of marine mammals during construction activities (i.e., pile driving) 
at the Kodiak Ferry Dock (see 80 FR 60636, October 7, 2015). In the 
marine mammal monitoring report for that project (ABR 2016), 1,281 
Steller sea lions were observed within the estimated Level B harassment 
zone during pile driving or drilling (i.e., documented as potential 
take by Level B harassment). Of these, 19 individuals demonstrated an 
alert behavior, 7 were fleeing, and 19 swam away from the project site. 
All other animals (98 percent) were engaged in activities such as 
milling, foraging, or fighting and did not change their behavior. In 
addition, two sea lions approached within 20 m of active vibratory pile 
driving activities. Three harbor seals were observed within the 
disturbance zone during pile driving activities; none of them displayed 
disturbance behaviors. Fifteen killer whales and three harbor porpoise 
were also observed within the Level B harassment zone during pile 
driving. The killer whales were travelling or milling while all harbor 
porpoises were travelling. No signs of disturbance were noted for 
either of these species. Given the similarities in species, activities 
and habitat, we expect similar behavioral responses of marine mammals 
to the MEDOT's specified activity. That is, disturbance, if any, is 
likely to be temporary and localized (e.g., small area movements).
    Stress responses--An animal's perception of a threat may be 
sufficient to trigger stress responses consisting of some combination 
of behavioral responses, autonomic nervous system responses, 
neuroendocrine responses, or immune responses (e.g., Seyle 1950; Moberg 
2000). In many cases, an animal's first and sometimes most economical 
(in terms of energetic costs) response is behavioral avoidance of the 
potential stressor. Autonomic nervous system responses to stress 
typically involve changes in heart rate, blood pressure, and 
gastrointestinal activity. These responses have a relatively short 
duration and may or may not have a significant long-term effect on an 
animal's fitness.
    Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that 
are affected by stress--including immune competence, reproduction, 
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been 
implicated in failed reproduction, altered metabolism, reduced immune 
competence, and behavioral disturbance (e.g., Moberg 1987; Blecha 
2000). Increases in the circulation of glucocorticoids are also equated 
with stress (Romano et al., 2004).
    The primary distinction between stress (which is adaptive and does 
not normally place an animal at risk) and ``distress'' is the cost of 
the response. During a stress response, an animal uses glycogen stores 
that can be quickly replenished once the stress is alleviated. In such 
circumstances, the cost of the stress response would not pose serious 
fitness consequences. However, when an animal does not have sufficient 
energy reserves to satisfy the energetic costs of a stress response, 
energy resources must be diverted from other functions. This state of 
distress will last until the animal replenishes its energetic reserves 
sufficient to restore normal function.
    Relationships between these physiological mechanisms, animal 
behavior, and the costs of stress responses are well-studied through 
controlled experiments and for both laboratory and free-ranging animals 
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003; 
Krausman et al., 2004; Lankford et al., 2005). Stress responses due to 
exposure to anthropogenic sounds or other stressors and their effects 
on marine mammals have also been reviewed (Fair and Becker 2000; Romano 
et al., 2002b) and, more rarely, studied in wild populations (e.g., 
Romano et al., 2002a). For example, Rolland et al. (2012) found that 
noise reduction from reduced ship traffic in the Bay of Fundy was 
associated with decreased stress in North Atlantic right whales. These 
and other studies lead to a reasonable expectation that some marine 
mammals will experience physiological stress responses upon exposure to 
acoustic stressors and that it is possible that some of these would be 
classified as ``distress.'' In addition, any animal experiencing TTS 
would likely also experience stress responses (NRC, 2003), however 
distress is an unlikely result of this project based on observations of 
marine mammals during previous, similar projects in the area.
    Masking--Sound can disrupt behavior through masking, or interfering 
with, an animal's ability to detect, recognize, or discriminate between 
acoustic signals of interest (e.g., those used for intraspecific 
communication and social interactions, prey detection, predator 
avoidance, navigation) (Richardson et al., 1995). Masking occurs when 
the receipt of a sound is interfered with by another coincident sound 
at similar frequencies and at similar or higher intensity, and may 
occur whether the sound is natural (e.g., snapping shrimp, wind, waves, 
precipitation) or anthropogenic (e.g., pile driving, shipping, sonar, 
seismic exploration) in origin. The ability of a noise source to mask 
biologically important sounds depends on the characteristics of both 
the noise source and the signal of interest (e.g., signal-to-noise 
ratio, temporal variability, direction), in relation to each other and 
to an animal's hearing abilities (e.g., sensitivity, frequency range, 
critical ratios, frequency discrimination, directional discrimination, 
age or TTS hearing loss), and existing ambient noise and propagation 
conditions. Masking of natural sounds can result when human activities 
produce high levels of background sound at frequencies important to 
marine mammals. Conversely, if the background level of underwater sound 
is high (e.g., on a day with strong wind and high waves), an 
anthropogenic sound source would not be detectable as far away as would 
be possible under quieter conditions and would itself be masked. The 
project area contains active commercial shipping, as well as numerous 
recreational and other commercial vessel and background sound levels in 
the area are already elevated.
    Airborne Acoustic Effects--Pinnipeds that occur near the project 
site could be exposed to airborne sounds associated with pile driving 
and removal that have the potential to cause behavioral harassment, 
depending on their distance from pile driving activities. Cetaceans are 
not expected to be exposed to airborne sounds that would result in 
harassment as defined under the MMPA.
    Airborne noise would primarily be an issue for pinnipeds that are 
swimming or hauled out near the project site within the range of noise 
levels elevated above the acoustic criteria. There are no known 
haulouts in the project vicinity. We recognize that pinnipeds in the 
water could be exposed to airborne sound that may result in behavioral 
harassment when looking with their heads above water. Most likely, 
airborne sound would cause behavioral responses similar to those 
discussed above in relation to underwater sound. For instance, 
anthropogenic sound could cause hauled out pinnipeds to exhibit changes 
in their normal behavior, such as reduction in vocalizations, or cause 
them to temporarily abandon the area and move further from the source. 
However, these animals would likely previously have been `taken' 
because of exposure to underwater sound above the behavioral harassment 
thresholds, which are generally larger than those associated

[[Page 61173]]

with airborne sound. Thus, the behavioral harassment of these animals 
is already accounted for in these estimates of potential take. 
Therefore, we do not believe that authorization of incidental take 
resulting from airborne sound for pinnipeds is warranted, and airborne 
sound is not discussed further here.

Marine Mammal Habitat Effects

    MEDOT's construction activities could have localized, temporary 
impacts on marine mammal habitat and their prey by increasing in-water 
sound pressure levels and slightly decreasing water quality. Increased 
noise levels may affect acoustic habitat (see masking discussion above) 
and adversely affect marine mammal prey in the vicinity of the project 
area (see discussion below). During DTH, impact and vibratory pile 
driving or removal, elevated levels of underwater noise would ensonify 
the project area where both fishes and mammals occur and could affect 
foraging success. Additionally, marine mammals may avoid the area 
during construction, however, displacement due to noise is expected to 
be temporary and is not expected to result in long-term effects to the 
individuals or populations. Construction activities are of short 
duration and would likely have temporary impacts on marine mammal 
habitat through increases in underwater and airborne sound.
    A temporary and localized increase in turbidity near the seafloor 
would occur in the immediate area surrounding the area where piles are 
installed or removed. In general, turbidity associated with pile 
installation is localized to about a 25-foot (7.6-m) radius around the 
pile (Everitt et al., 1980). The sediments of the project site are 
sandy and will settle out rapidly when disturbed. Cetaceans are not 
expected to be close enough to the pile driving areas to experience 
effects of turbidity, and any pinnipeds could avoid localized areas of 
turbidity. Local strong currents are anticipated to disburse any 
additional suspended sediments produced by project activities at 
moderate to rapid rates depending on tidal stage. Therefore, we expect 
the impact from increased turbidity levels to be discountable to marine 
mammals and do not discuss it further.

In-Water Construction Effects on Potential Foraging Habitat

    The area likely impacted by the project is relatively small 
compared to the available habitat. The project area does not include 
any Biologically Important Areas or other habitat of known importance. 
The area is highly influenced by anthropogenic activities. The total 
seafloor area affected by pile installation and removal is a small area 
compared to the vast foraging area available to marine mammals in the 
area. At best, the impact area provides marginal foraging habitat for 
marine mammals and fishes. Furthermore, pile driving and removal at the 
project site would not obstruct movements or migration of marine 
mammals.
    Avoidance by potential prey (i.e., fish) of the immediate area due 
to the temporary loss of this foraging habitat is also possible. The 
duration of fish avoidance of this area after pile driving stops is 
unknown, but a rapid return to normal recruitment, distribution and 
behavior is anticipated. Any behavioral avoidance by fish of the 
disturbed area would still leave significantly large areas of fish and 
marine mammal foraging habitat in the nearby vicinity.
    In-water Construction Effects on Potential Prey--Sound may affect 
marine mammals through impacts on the abundance, behavior, or 
distribution of prey species (e.g., crustaceans, cephalopods, fish, 
zooplankton). Marine mammal prey varies by species, season, and 
location. Here, we describe studies regarding the effects of noise on 
known marine mammal prey.
    Fish utilize the soundscape and components of sound in their 
environment to perform important functions such as foraging, predator 
avoidance, mating, and spawning (e.g., Zelick and Mann, 1999; Fay, 
2009). Depending on their hearing anatomy and peripheral sensory 
structures, which vary among species, fishes hear sounds using pressure 
and particle motion sensitivity capabilities and detect the motion of 
surrounding water (Fay et al., 2008). The potential effects of noise on 
fishes depends on the overlapping frequency range, distance from the 
sound source, water depth of exposure, and species-specific hearing 
sensitivity, anatomy, and physiology. Key impacts to fishes may include 
behavioral responses, hearing damage, barotrauma (pressure-related 
injuries), and mortality.
    Fish react to sounds which are especially strong and/or 
intermittent low-frequency sounds, and behavioral responses such as 
flight or avoidance are the most likely effects. Short duration, sharp 
sounds can cause overt or subtle changes in fish behavior and local 
distribution. The reaction of fish to noise depends on the 
physiological state of the fish, past exposures, motivation (e.g., 
feeding, spawning, migration), and other environmental factors. 
Hastings and Popper (2005) identified several studies that suggest fish 
may relocate to avoid certain areas of sound energy. Additional studies 
have documented effects of pile driving on fish; several are based on 
studies in support of large, multiyear bridge construction projects 
(e.g., Scholik and Yan, 2001, 2002; Popper and Hastings, 2009). Several 
studies have demonstrated that impulse sounds might affect the 
distribution and behavior of some fishes, potentially impacting 
foraging opportunities or increasing energetic costs (e.g., Fewtrell 
and McCauley, 2012; Pearson et al., 1992; Skalski et al., 1992; 
Santulli et al., 1999; Paxton et al., 2017). However, some studies have 
shown no or slight reaction to impulse sounds (e.g., Pena et al., 2013; 
Wardle et al., 2001; Jorgenson and Gyselman, 2009; Cott et al., 2012).
    SPLs of sufficient strength have been known to cause injury to fish 
and fish mortality. However, in most fish species, hair cells in the 
ear continuously regenerate and loss of auditory function likely is 
restored when damaged cells are replaced with new cells. Halvorsen et 
al. (2012a) showed that a TTS of 4-6 dB was recoverable within 24 hours 
for one species. Impacts would be most severe when the individual fish 
is close to the source and when the duration of exposure is long. 
Injury caused by barotrauma can range from slight to severe and can 
cause death, and is most likely for fish with swim bladders. Barotrauma 
injuries have been documented during controlled exposure to impact pile 
driving (Halvorsen et al., 2012b; Casper et al., 2013).
    The most likely impact to fish from pile driving and removal and 
construction activities at the project area would be temporary 
behavioral avoidance of the area. The duration of fish avoidance of 
this area after pile driving stops is unknown, but a rapid return to 
normal recruitment, distribution and behavior is anticipated.
    Construction activities, in the form of increased turbidity, have 
the potential to adversely affect forage fish in the project area. 
Forage fish form a significant prey base for many marine mammal species 
that occur in the project area. Increased turbidity is expected to 
occur in the immediate vicinity (on the order of 10 feet (3 m) or less) 
of construction activities. However, suspended sediments and 
particulates are expected to dissipate quickly within a single tidal 
cycle. Given the limited area affected and high tidal dilution rates 
any effects on forage fish are expected to be minor or negligible.
    In summary, given the short daily duration of sound associated with 
individual pile driving events and the relatively small areas being 
affected,

[[Page 61174]]

pile driving activities associated with the proposed action are not 
likely to have a permanent, adverse effect on any fish habitat, or 
populations of fish species. Any behavioral avoidance by fish of the 
disturbed area would still leave significantly large areas of fish and 
marine mammal foraging habitat in the nearby vicinity. Thus, we 
conclude that impacts of the specified activity are not likely to have 
more than short-term adverse effects on any prey habitat or populations 
of prey species. Further, any impacts to marine mammal habitat are not 
expected to result in significant or long-term consequences for 
individual marine mammals, or to contribute to adverse impacts on their 
populations.

Estimated Take

    This section provides an estimate of the number of incidental takes 
proposed for authorization through this IHA, which will inform both 
NMFS' consideration of ``small numbers'' and the negligible impact 
determination.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of the MMPA defines ``harassment'' as any act of 
pursuit, torment, or annoyance, which (i) has the potential to injure a 
marine mammal or marine mammal stock in the wild (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).
    Authorized takes would primarily be by Level B harassment, as use 
of the acoustic sources has the potential to result in disruption of 
behavioral patterns for individual marine mammals. There is also some 
potential for Level A harassment to result, primarily for phocids 
because predicted auditory injury zones are larger than for other 
groups and harbor seals are common. Auditory injury is unlikely to 
occur for other species/groups. The proposed mitigation and monitoring 
measures are expected to minimize the severity of the taking to the 
extent practicable. As described previously, no mortality is 
anticipated or proposed to be authorized for this activity. Below we 
describe how the take is estimated.
    Generally speaking, we estimate take by considering: (1) Acoustic 
thresholds above which marine mammals will be behaviorally harassed or 
incur some degree of permanent hearing impairment; (2) the area or 
volume of water that will be ensonified above these levels in a day; 
(3) the density or occurrence of marine mammals within these ensonified 
areas; and, (4) and the number of days of activities. We note that 
while these basic factors can contribute to a basic calculation to 
provide an initial prediction of takes, additional information that can 
qualitatively inform take estimates is also sometimes available (e.g., 
previous monitoring results or average group size). Due to the lack of 
marine mammal density data available for this location, NMFS relied on 
local occurrence data and group size to estimate take for some species. 
Below, we describe the factors considered here in more detail and 
present the proposed take estimate.

Acoustic Thresholds

    NMFS recommends the use of acoustic thresholds that identify the 
received level of underwater sound above which exposed marine mammals 
would be reasonably expected to be behaviorally harassed (equated to 
Level B harassment) or to incur PTS of some degree (equated to Level A 
harassment).
    Level B Harassment for non-explosive sources--Though significantly 
driven by received level, the onset of behavioral disturbance from 
anthropogenic noise exposure is also informed to varying degrees by 
other factors related to the source (e.g., frequency, predictability, 
duty cycle), the environment (e.g., bathymetry), and the receiving 
animals (hearing, motivation, experience, demography, behavioral 
context) and can be difficult to predict (Southall et al., 2007, 
Ellison et al., 2012). Based on what the available science indicates 
and the practical need to use a threshold based on a factor that is 
both predictable and measurable for most activities, NMFS uses a 
generalized acoustic threshold based on received level to estimate the 
onset of behavioral harassment. NMFS predicts that marine mammals are 
likely to be behaviorally harassed in a manner we consider Level B 
harassment when exposed to underwater anthropogenic noise above 
received levels of 120 dB re 1 microPascal ([mu]Pa) (root mean square 
(rms)) for continuous (e.g., vibratory pile-driving) and above 160 dB 
re 1 [mu]Pa (rms) for non-explosive impulsive (e.g., impact pile 
driving) or intermittent (e.g., scientific sonar) sources.
    MEDOT's proposed activity includes the use of continuous (vibratory 
hammer and DTH) and impulsive (impact pile-driving) sources, and 
therefore the 120 and 160 dB re 1 [mu]Pa (rms) thresholds are 
applicable.
    Level A harassment for non-explosive sources--NMFS' Technical 
Guidance for Assessing the Effects of Anthropogenic Sound on Marine 
Mammal Hearing (Version 2.0) (Technical Guidance, 2018) identifies dual 
criteria to assess auditory injury (Level A harassment) to five 
different marine mammal groups (based on hearing sensitivity) as a 
result of exposure to noise from two different types of sources 
(impulsive or non-impulsive). MEDOT's activity includes the use of 
impulsive (impact pile-driving and DTH) and non-impulsive (vibratory 
hammer and DTH) sources.
    These thresholds are provided in Table 3. The references, analysis, 
and methodology used in the development of the thresholds are described 
in NMFS 2018 Technical Guidance, which may be accessed at https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

                     Table 3--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
                                                     PTS onset acoustic thresholds * (received level)
             Hearing group              ------------------------------------------------------------------------
                                                  Impulsive                         Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans...........  Cell 1: Lpk,flat: 219 dB;   Cell 2: LE,LF,24h: 199 dB.
                                          LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans...........  Cell 3: Lpk,flat: 230 dB;   Cell 4: LE,MF,24h: 198 dB.
                                          LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans..........  Cell 5: Lpk,flat: 202 dB;   Cell 6: LE,HF,24h: 173 dB.
                                          LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater).....  Cell 7: Lpk,flat: 218 dB;   Cell 8: LE,PW,24h: 201 dB.
                                          LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater)....  Cell 9: Lpk,flat: 232 dB;   Cell 10: LE,OW,24h: 219 dB.
                                          LE,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for
  calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level
  thresholds associated with impulsive sounds, these thresholds should also be considered.

[[Page 61175]]

 
Note: Peak sound pressure (Lpk) has a reference value of 1 [mu]Pa, and cumulative sound exposure level (LE) has
  a reference value of 1[mu]Pa\2\s. In this Table, thresholds are abbreviated to reflect American National
  Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as incorporating
  frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript ``flat'' is
  being included to indicate peak sound pressure should be flat weighted or unweighted within the generalized
  hearing range. The subscript associated with cumulative sound exposure level thresholds indicates the
  designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds) and
  that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds could be
  exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible, it
  is valuable for action proponents to indicate the conditions under which these acoustic thresholds will be
  exceeded.

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that will feed into identifying the area ensonified above the 
acoustic thresholds, which include source levels and transmission loss 
coefficient.
    The sound field in the project area is the existing background 
noise plus additional construction noise from the proposed project. 
Marine mammals are expected to be affected via sound generated by the 
primary components of the project (i.e., impact and vibratory pile 
driving, and DTH).
    In order to calculate distances to the Level A harassment and Level 
B harassment sound thresholds for the methods and piles being used in 
this project, NMFS used acoustic monitoring data from other locations 
to develop source levels for the various pile types, sizes and methods 
(Table 4).

                  Table 4--Project Sound Source Levels
------------------------------------------------------------------------
                                    Estimated noise
             Method                   levels (dB)           Source
------------------------------------------------------------------------
DTH--24-inch impulsive (Level A)  154 SELss.........  Denes et al.
                                                       (2016).
DTH--8-inch impulsive (Level A).  144 SELss.........  Reyff (2020).
DTH--non-impulsive (Level B) All  166 dB RMS........  Denes et al.
 sizes.                                                (2016).
Impact--24-inch.................  203 Pk, 177 SEL...  Caltrans (2015).
Vibratory--24-inch..............  165 RMS...........  Caltrans (2015).
------------------------------------------------------------------------
Note: SEL = single strike sound exposure level; RMS = root mean square.

Level B Harassment Zones

    Transmission loss (TL) is the decrease in acoustic intensity as an 
acoustic pressure wave propagates out from a source. TL parameters vary 
with frequency, temperature, sea conditions, current, source and 
receiver depth, water depth, water chemistry, and bottom composition 
and topography. The general formula for underwater TL is:

TL = B * Log10 (R1/R2),

where

TL = transmission loss in dB
B = transmission loss coefficient; for practical spreading equals 15
R1 = the distance of the modeled SPL from the driven pile, and
R2 = the distance from the driven pile of the initial measurement

    The recommended TL coefficient for most nearshore environments is 
the practical spreading value of 15. This value results in an expected 
propagation environment that would lie between spherical and 
cylindrical spreading loss conditions, which is the most appropriate 
assumption for MEDOT's proposed activity in the absence of specific 
modelling.
    MEDOT determined underwater noise would fall below the behavioral 
effects threshold of 160 dB RMS for impact driving at 1,585 m and the 
120 dB rms threshold for vibratory driving at 10,000 m and all 
diameters of holes created by DTH at 11,660 m (Table 5). It should be 
noted that based on the bathymetry and geography of the project area, 
sound will not reach the full distance of the harassment isopleths in 
all directions (see Application Figures 6-3 and 6-4).

                         Table 5--Level A and Level B Isopleths (Meters) for Each Method
----------------------------------------------------------------------------------------------------------------
             Method                Piles per day        MF              HF            Phocid          Level B
----------------------------------------------------------------------------------------------------------------
DTH--24-inch....................               1               6             199              89          11,660
                                               2              10             315             142
                                               3              13             413             186
DTH--8-inch.....................               1               2              43              20
                                               2               2              68              31
                                               3               3              89              40
Impact--24-inch.................               1               1              35              16           1,585
                                               2               2              56              25
                                               3               3              73              33
Vibratory--24-inch..............               3               2              25              11          10,000
----------------------------------------------------------------------------------------------------------------

Level A Harassment Zones

    When the NMFS Technical Guidance (2016) was published, in 
recognition of the fact that ensonified area/volume could be more 
technically challenging to predict because of the duration component in 
the new thresholds, we developed a User Spreadsheet that includes tools 
to help predict a simple isopleth that can be used in conjunction with 
marine mammal density or occurrence to help predict takes. We note that 
because of some of the assumptions included in the methods used for 
these tools, we anticipate that isopleths produced are typically going 
to be overestimates of some degree, which may result in some degree of 
overestimate of take by Level A harassment. However, these tools offer 
the best way to predict appropriate isopleths when more sophisticated 
3D modeling methods are not available, and NMFS continues to develop 
ways to

[[Page 61176]]

quantitatively refine these tools, and will qualitatively address the 
output where appropriate. For stationary sources such as pile driving 
or removal and DTH using any of the methods discussed above, NMFS User 
Spreadsheet predicts the closest distance at which, if a marine mammal 
remained at that distance the whole duration of the activity, it would 
not incur PTS. We used the User Spreadsheet to determine the Level A 
harassment isopleths. Inputs used in the User Spreadsheet or models are 
reported in Table 6 and the resulting isopleths are reported in Table 5 
for each of the construction methods and scenarios.

                    Table 6--User Spreadsheet Inputs
------------------------------------------------------------------------
                                                            Strikes per
                 Method                    Piles per day      pile or
                                                          duration (min)
------------------------------------------------------------------------
DTH--24-inch............................             1-3          54,000
DTH--8-inch.............................             1-3          54,000
Impact--24-inch.........................             1-3              20
Vibratory--24-inch......................               3              30
------------------------------------------------------------------------

Marine Mammal Occurrence and Take Calculation and Estimation

    In this section we provide the information about the presence, 
density, or group dynamics of marine mammals that will inform the take 
calculations. Here we describe how the information provided above is 
brought together to produce a quantitative take estimate. The main 
information used to inform take calculations is the Shaw Institute 
(2018) monitoring study commissioned for this project and discussed 
above. Density of animals from that study was calculated for either 
side of the bridge and was applied to the size of the Level B 
harassment zones (see Application Section 6.3 for full details). A 
summary of proposed take is in Table 7.

Atlantic White-Sided Dolphin

    Density data for this species in the project vicinity do not exist 
as no Atlantic white-sided dolphin were seen in the Shaw Institute 
(2018) study. Atlantic white-sided dolphins do not generally occur in 
the shallow, inland bays and estuaries of Maine. However, some could 
occur in rare circumstances. To be precautionary, we propose to 
authorize take for two groups of 20 animals over the course of the 
project. Therefore, we propose to authorize 40 Level B harassment takes 
of Atlantic white-sided dolphins. No takes by Level A harassment are 
expected or proposed for authorization because we expect MEDOT will 
effectively shutdown for Atlantic white-sided dolphins at the full 
extent of the very small Level A harassment zones.

Common Dolphin

    Density data for this species in the project vicinity do not exist 
as no common dolphin were seen in the Shaw Institute (2018) study. 
Common dolphins do not generally occur in the shallow, inland bays and 
estuaries of Maine. However, some could occur in rare circumstances. As 
with Atlantic white-sided dolphins above, to be precautionary, we 
propose to authorize take for two groups of 20 animals over the course 
of the project. Therefore, we propose to authorize 40 Level B 
harassment takes of common dolphins. No takes by Level A harassment are 
expected or proposed for authorization because we expect MEDOT will 
effectively shutdown for common dolphins at the full extent of the very 
small Level A harassment zones.

Harbor Porpoise

    The peak month of observation from Shaw Institute (2018) was May 
when the equivalent of 40 harbor porpoise per day would be observed in 
the Level B harassment zone for DTH. With 80 days of in-water work for 
the project we estimate potential Level B harassment take events at 
3,200 for harbor porpoise. No takes by Level A harassment are expected 
or proposed for authorization because we expect MEDOT will effectively 
shutdown for harbor porpoises at the full extent of the small Level A 
harassment zones.

Harbor Seal

    The peak month of observation from Shaw Institute (2018) was August 
when the equivalent of 99 seals per day would be observed in the Level 
B harassment zone for DTH. With 80 days of in-water work for the 
project we estimate potential Level B harassment zone exposures for 
harbor seals at 7,920.
    Because of the larger size of the Level A harassment zones for 24-
inch DTH and the abundance of harbor seals, we propose to authorize 2 
of the above assumed 99 takes per day by Level A harassment for the 48 
days of possible DTH activity. Thus of the 7,920 assumed harbor seal 
exposures we propose to authorize 96 Level A harassment takes and 7,824 
Level B harassment takes.

Gray Seal

    The peak month of observation from Shaw Institute (2018) was July 
when the equivalent of 4 seals per day would be observed in the Level B 
harassment zone for DTH. With 80 days of in-water work for the project 
we estimate potential Level B harassment takes for gray seals at 320. 
No takes by Level A harassment are expected or proposed for 
authorization because we expect MEDOT will effectively shutdown for 
gray seals at the full extent of the small Level A harassment zones.

Harp Seal

    Density data for this species in the project vicinity do not exist 
as no harp seals were seen in the Shaw Institute (2018) study. Most 
sightings on record in Maine occur during the winter months when 
transient individuals extend their range south in search of food. To be 
precautionary, we propose to authorize 1 take per month of harp seals. 
The project has 80 days of in water work equivalent to 16 5-day work 
weeks or 4 months. Therefore, we propose to authorize 4 Level B 
harassment takes of harp seals. No takes by Level A harassment are 
expected or proposed for authorization because we expect MEDOT will 
effectively shutdown for harp seals at the full extent of the small 
Level A harassment zones.

Hooded Seal

    Density data for this species in the project vicinity also do not 
exist as no hooded seals were seen in the Shaw Institute (2018) study. 
Most sightings on record in Maine occur during the winter months when 
transient individuals extend their range south in search of food. As 
with harp seals, above, to be precautionary, we propose to authorize 1 
take per month of hooded seals. Therefore, we propose to authorize 4 
Level B harassment takes of hooded

[[Page 61177]]

seals. No takes by Level A harassment are expected or proposed for 
authorization because we expect MEDOT will effectively shutdown for 
hooded seals at the full extent of the small Level A harassment zones.

   Table 7--Proposed Authorized Amount of Taking, by Level A Harassment and Level B Harassment, by Species and
                                       Stock and Percent of Take by Stock
----------------------------------------------------------------------------------------------------------------
                                                                                                    Percent of
         Common name            Scientific name       Stock           Level A         Level B          stock
----------------------------------------------------------------------------------------------------------------
Harbor porpoise..............  Phocoena          Gulf Maine/Bay                0           3,200             3.3
                                phocoena.         of Fundy.
Atlantic white-sided dolphin.  Lagenorhynchus    Western North                 0              40            <0.1
                                acutus.           Atlantic.
Common dolphin...............  Delphinus         Western North                 0              40            <0.1
                                delphis.          Atlantic.
Harbor seal..................  Phoca vitulina..  Western North                96           7,824            12.8
                                                  Atlantic.
Gray seal....................  Halichoerus       Western North                 0             320            <0.1
                                grypus.           Atlantic.
Harp seal....................  Pagophilus        Western North                 0               4            <0.1
                                groenlandicus.    Atlantic.
Hooded seal..................  Cystophora        Western North                 0               4              NA
                                cristata.         Atlantic.
----------------------------------------------------------------------------------------------------------------
NA--not available as there is no official stock size estimate.

Proposed Mitigation

    In order to issue an IHA under section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to the 
activity, and other means of effecting the least practicable impact on 
the species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of the species or stock for taking for certain 
subsistence uses (latter not applicable for this action). NMFS 
regulations require applicants for incidental take authorizations to 
include information about the availability and feasibility (economic 
and technological) of equipment, methods, and manner of conducting the 
activity or other means of effecting the least practicable adverse 
impact upon the affected species or stocks and their habitat (50 CFR 
216.104(a)(11)).
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, we 
carefully consider two primary factors:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat. 
This considers the nature of the potential adverse impact being 
mitigated (likelihood, scope, range). It further considers the 
likelihood that the measure will be effective if implemented 
(probability of accomplishing the mitigating result if implemented as 
planned), the likelihood of effective implementation (probability 
implemented as planned); and
    (2) The practicability of the measures for applicant 
implementation, which may consider such things as cost, impact on 
operations, and, in the case of a military readiness activity, 
personnel safety, practicality of implementation, and impact on the 
effectiveness of the military readiness activity.
    The following mitigation measures are proposed in the IHA:
     Avoid direct physical interaction with marine mammals 
during construction activity. If a marine mammal comes within 10 m of 
such activity, operations must cease and vessels must reduce speed to 
the minimum level required to maintain steerage and safe working 
conditions;
     Conduct training between construction supervisors and 
crews and the marine mammal monitoring team and relevant MEDOT staff 
prior to the start of all pile driving and DTH activity and when new 
personnel join the work, so that responsibilities, communication 
procedures, monitoring protocols, and operational procedures are 
clearly understood;
     Pile driving activity must be halted upon observation of 
either a species for which incidental take is not authorized or a 
species for which incidental take has been authorized but the 
authorized number of takes has been met, entering or within the 
harassment zone;
     MEDOT will establish and implement the shutdown zones 
indicated in Table 8. The purpose of a shutdown zone is generally to 
define an area within which shutdown of the activity would occur upon 
sighting of a marine mammal (or in anticipation of an animal entering 
the defined area). Shutdown zones typically vary based on the activity 
type and marine mammal hearing group. To simplify implementation of 
shutdown zones MEDOT has proposed to implement shutdown zones for two 
groups of marine mammals, cetaceans and pinnipeds, with the shutdown 
zone in each group being the largest of the shutdown zones for any of 
the hearing groups contained within that group. MEDOT has also 
voluntarily proposed to increase shutdown sizes above those we would 
typically require in order to be precautionary and protective to marine 
mammals. They have proposed to round-up shutdown zone sizes to the next 
highest 50 m from the distances in Table 5. For comparison purposes, 
Table 8 shows both the minimum shutdown zones we would normally require 
and the shutdown zones MEDOT proposes to implement. NMFS proposes to 
include the latter in the requested IHA;
     Employ Protected Species Observers (PSOs) and establish 
monitoring locations as described in the Marine Mammal Monitoring Plan 
and Section 5 of the IHA. MEDOT must monitor the project area to the 
maximum extent possible based on the required number of PSOs, required 
monitoring locations, and environmental conditions. For all DTH, pile 
driving and removal at least one PSO must be used. The PSO will be 
stationed as close to the activity as possible;
     The placement of the PSOs during all pile driving and 
removal and DTH activities will ensure that the entire shutdown zone is 
visible during pile installation. Should environmental conditions 
deteriorate such that marine mammals within the entire shutdown zone 
will not be visible (e.g., fog, heavy rain), pile driving and removal 
must be delayed until the PSO is confident marine mammals within the 
shutdown zone could be detected;
     Monitoring must take place from 30 minutes prior to 
initiation of pile driving activity through 30 minutes post-completion 
of pile driving activity. Pre-start clearance monitoring must be 
conducted during periods of visibility sufficient for the lead PSO to 
determine the shutdown zones clear of marine mammals. Pile driving may 
commence

[[Page 61178]]

following 30 minutes of observation when the determination is made;
     If pile driving is delayed or halted due to the presence 
of a marine mammal, the activity may not commence or resume until 
either the animal has voluntarily exited and been visually confirmed 
beyond the shutdown zone or 15 minutes have passed without re-detection 
of the animal; and
     MEDOT must use soft start techniques when impact pile 
driving. Soft start requires contractors to provide an initial set of 
three strikes at reduced energy, followed by a 30-second waiting 
period, then two subsequent reduced-energy strike sets. A soft start 
must be implemented at the start of each day's impact pile driving and 
at any time following cessation of impact pile driving for a period of 
30 minutes or longer;

   Table 8--Minimum Required Shutdown Zones (Meters) by Hearing Group and Voluntary Planned Shutdown Zones for Cetaceans and Pinnipeds for Each Method
--------------------------------------------------------------------------------------------------------------------------------------------------------
                         Method                            Piles per day        MF              HF            Phocid         Cetacean        Pinniped
--------------------------------------------------------------------------------------------------------------------------------------------------------
DTH--24-inch............................................               1              10             200              90             200             100
                                                                       2              10             320             150             350             200
                                                                       3              20             420             190             450             200
DTH--8-inch.............................................               1              10              50              20             100              50
                                                                       2              10              70              40             100              50
                                                                       3              10              90              40             100              50
Impact--24-inch.........................................               1              10              40              20              50              50
                                                                       2              10              60              30             100              50
                                                                       3              10              80              40             100              50
Vibratory--24-inch......................................               3              10              30              20              50              50
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: First three columns are what NMFS would consider appropriate in this circumstance, and the last two are what the applicant has proposed and what
  NMFS proposes to include in the IHA.

    Based on our evaluation of the applicant's proposed measures, as 
well as other measures considered by NMFS, NMFS has preliminarily 
determined that the proposed mitigation measures provide the means 
effecting the least practicable impact on the affected 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 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 
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. Effective reporting is critical both to 
compliance as well as ensuring that the most value is obtained from the 
required monitoring.
    Monitoring and reporting requirements prescribed by NMFS should 
contribute to improved understanding of one or more of the following:
     Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density);
     Nature, scope, or context of likely marine mammal exposure 
to potential stressors/impacts (individual or cumulative, acute or 
chronic), through better understanding of: (1) Action or environment 
(e.g., source characterization, propagation, ambient noise); (2) 
affected species (e.g., life history, dive patterns); (3) co-occurrence 
of marine mammal species with the action; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas);
     Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
     How anticipated responses to stressors impact either: (1) 
Long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
     Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and
     Mitigation and monitoring effectiveness.

Visual Monitoring

     Monitoring must be conducted by qualified, NMFS-approved 
PSOs, in accordance with the following: PSOs must be independent (i.e., 
not construction personnel) and have no other assigned tasks during 
monitoring periods. At least one PSO must have prior experience 
performing the duties of a PSO during construction activity pursuant to 
a NMFS-issued incidental take authorization. Other PSOs may substitute 
other relevant experience, education (degree in biological science or 
related field), or training. PSOs must be approved by NMFS prior to 
beginning any activity subject to this IHA;
     PSOs must record all observations of marine mammals as 
described in the Section 5 of the IHA and the Marine Mammal Monitoring 
Plan, regardless of distance from the pile being driven or DTH 
activity. PSOs shall document any behavioral reactions in concert with 
distance from piles being driven or removed;
    PSOs must have the following additional qualifications:
     Ability to conduct field observations and collect data 
according to assigned protocols;
     Experience or training in the field identification of 
marine mammals, including the identification of behaviors;
     Sufficient training, orientation, or experience with the 
construction operation to provide for personal safety during 
observations;
     Writing skills sufficient to prepare a report of 
observations including but not limited to the number and species of 
marine mammals observed; dates and times when in-water construction 
activities were conducted; dates, times, and reason for implementation 
of mitigation (or why mitigation was not implemented when required); 
and marine mammal behavior; and
     Ability to communicate orally, by radio or in person, with 
project

[[Page 61179]]

personnel to provide real-time information on marine mammals observed 
in the area as necessary;
     MEDOT must establish the following monitoring locations. 
For all pile driving and DTH activities, a minimum of one PSO must be 
assigned to the active pile driving or DTH location to monitor the 
shutdown zones and as much of the Level A and Level B harassment zones 
as possible. When a vibratory hammer or DTH is used a second PSO must 
be located in the Level B harassment zone at one of two shoreline 
stations east of the bridge (see map in application Figure 13-1).

Reporting

    A draft marine mammal monitoring report will be submitted to NMFS 
within 90 days after the completion of pile driving and removal 
activities, or 60 days prior to a requested date of issuance of any 
future IHAs for projects at the same location, whichever comes first. 
The report will include an overall description of work completed, a 
narrative regarding marine mammal sightings, and associated PSO data 
sheets. Specifically, the report must include:
     Dates and times (begin and end) of all marine mammal 
monitoring;
     Construction activities occurring during each daily 
observation period, including the number and type of piles driven or 
removed and by what method (i.e., impact or cutting) and the total 
equipment duration for cutting for each pile or total number of strikes 
for each pile (impact driving);
     PSO locations during marine mammal monitoring;
     Environmental conditions during monitoring periods (at 
beginning and end of PSO shift and whenever conditions change 
significantly), including Beaufort sea state and any other relevant 
weather conditions including cloud cover, fog, sun glare, and overall 
visibility to the horizon, and estimated observable distance;
     Upon observation of a marine mammal, the following 
information: Name of PSO who sighted the animal(s) and PSO location and 
activity at time of sighting; Time of sighting; Identification of the 
animal(s) (e.g., genus/species, lowest possible taxonomic level, or 
unidentified), PSO confidence in identification, and the composition of 
the group if there is a mix of species; Distance and bearing of each 
marine mammal observed relative to the pile being driven for each 
sighting (if pile driving was occurring at time of sighting); Estimated 
number of animals (min/max/best estimate); Estimated number of animals 
by cohort (adults, juveniles, neonates, group composition, etc.); 
Animal's closest point of approach and estimated time spent within the 
harassment zone; Description of any marine mammal behavioral 
observations (e.g., observed behaviors such as feeding or traveling), 
including an assessment of behavioral responses thought to have 
resulted from the activity (e.g., no response or changes in behavioral 
state such as ceasing feeding, changing direction, flushing, or 
breaching);
     Number of marine mammals detected within the harassment 
zones, by species; and
     Detailed information about any implementation of any 
mitigation triggered (e.g., shutdowns and delays), a description of 
specific actions that ensued, and resulting changes in behavior of the 
animal(s), if any.
    If no comments are received from NMFS within 30 days, the draft 
final report will constitute the final report. If comments are 
received, a final report addressing NMFS comments must be submitted 
within 30 days after receipt of comments.

Reporting Injured or Dead Marine Mammals

    In the event that personnel involved in the construction activities 
discover an injured or dead marine mammal, the IHA-holder must 
immediately cease the specified activities and report the incident to 
the Office of Protected Resources (OPR) 
([email protected]), NMFS and to Greater Atlantic 
Regional Stranding Coordinator as soon as feasible. If the death or 
injury was clearly caused by the specified activity, MEDOT must 
immediately cease the specified activities until NMFS is able to review 
the circumstances of the incident and determine what, if any, 
additional measures are appropriate to ensure compliance with the terms 
of the IHA. The IHA-holder must not resume their activities until 
notified by NMFS. The report must include the following information:
     Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
     Species identification (if known) or description of the 
animal(s) involved;
     Condition of the animal(s) (including carcass condition if 
the animal is dead);
     Observed behaviors of the animal(s), if alive;
     If available, photographs or video footage of the 
animal(s); and
     General circumstances under which the animal was 
discovered.

Negligible Impact Analysis and Determination

    NMFS has defined negligible impact 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 (50 CFR 216.103). A 
negligible impact finding is based on the lack of likely adverse 
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough 
information on which to base an impact determination. In addition to 
considering estimates of the number of marine mammals that might be 
``taken'' through harassment, NMFS considers other factors, such as the 
likely nature of any responses (e.g., intensity, duration), the context 
of any responses (e.g., critical reproductive time or location, 
migration), as well as effects on habitat, and the likely effectiveness 
of the mitigation. We also assess the number, intensity, and context of 
estimated takes by evaluating this information relative to population 
status. Consistent with the 1989 preamble for NMFS's implementing 
regulations (54 FR 40338; September 29, 1989), the impacts from other 
past and ongoing anthropogenic activities are incorporated into this 
analysis via their impacts on the environmental baseline (e.g., as 
reflected in the regulatory status of the species, population size and 
growth rate where known, ongoing sources of human-caused mortality, or 
ambient noise levels).
    Pile driving and removal and DTH activities have the potential to 
disturb or displace marine mammals. Specifically, the project 
activities may result in take, in the form of Level B harassment from 
underwater sounds generated from pile driving and removal and DTH for 
all species and a small amount of Level A harassment take for harbor 
seals. Potential takes could occur if individuals are present in the 
ensonified zone when these activities are underway.
    To avoid repetition, the discussion of our analyses applies to all 
the species listed in Table 7, given that the anticipated effects of 
this activity on these different marine mammal stocks are expected to 
be similar. There is little information about the nature or severity of 
the impacts, or the size, status, or structure of any of these species 
or stocks that would lead to a different analysis for this activity.
    The takes from Level A and Level B harassment would be due to 
potential

[[Page 61180]]

behavioral disturbance, TTS, and PTS. No serious injury or mortality is 
anticipated given the nature of the activity and measures designed to 
minimize the possibility of injury to marine mammals. The potential for 
harassment is minimized through the construction method and the 
implementation of the planned mitigation measures (see Proposed 
Mitigation section).
    Many of the Level A harassment zones identified in Table 7 are 
based upon an animal exposed to pile driving or DTH multiple piles per 
day. Considering the short duration to impact drive or DTH each pile 
and breaks between pile installations (to reset equipment and move pile 
into place), this means an animal would have to remain within the area 
estimated to be ensonified above the Level A harassment threshold for 
multiple hours. This is highly unlikely given marine mammal movement 
throughout the area. If an animal was exposed to accumulated sound 
energy, the resulting PTS would likely be small (e.g., PTS onset) at 
lower frequencies where pile driving energy is concentrated, and 
unlikely to result in impacts to individual fitness, reproduction, or 
survival.
    The nature of the pile driving project precludes the likelihood of 
serious injury or mortality. For all species and stocks, take would 
occur within a limited, confined area (adjacent to the Falls Bridge) of 
the stock's range. Level A and Level B harassment will be reduced to 
the level of least practicable adverse impact through use of mitigation 
measures described herein. Further the amount of take proposed to be 
authorized is small when compared to stock abundance.
    Behavioral responses of marine mammals to pile driving at the 
project site, if any, are expected to be mild and temporary. Marine 
mammals within the Level B harassment zone may not show any visual cues 
they are disturbed by activities (as noted during modification to the 
Kodiak Ferry Dock) or could become alert, avoid the area, leave the 
area, or display other mild responses that are not observable such as 
changes in vocalization patterns. Given the short duration of noise-
generating activities per day, any harassment would be temporary. There 
are no other areas or times of known biological importance for any of 
the affected species.
    In addition, it is unlikely that minor noise effects in a small, 
localized area of habitat would have any effect on the stocks' ability 
to recover. In combination, we believe that these factors, as well as 
the available body of evidence from other similar activities, 
demonstrate that the potential effects of the specified activities will 
have only minor, short-term effects on individuals. The specified 
activities are not expected to impact rates of recruitment or survival 
and will therefore not result in population-level impacts.
    In summary and as described above, the following factors primarily 
support our preliminary determination that the impacts resulting from 
this activity are not expected to adversely affect the species or stock 
through effects on annual rates of recruitment or survival:
     No mortality is anticipated or authorized;
     Authorized Level A harassment of harbor seals would be 
very small amounts and of low degree;
     No important habitat areas have been identified within the 
project area;
     For all species, the project is a very small and 
peripheral part of their range;
     MEDOT would implement mitigation measures such as soft-
starts, and shut downs.
    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 proposed monitoring and 
mitigation measures, NMFS preliminarily finds that the total marine 
mammal take from the proposed activity will have a negligible impact on 
all affected marine mammal species or stocks.

Small Numbers

    As noted above, only small numbers of incidental take may be 
authorized under section 101(a)(5)(D) of the MMPA for specified 
activities other than military readiness activities. The MMPA does not 
define small numbers and so, in practice, where estimated numbers are 
available, NMFS compares the number of individuals taken to the most 
appropriate estimation of abundance of the relevant species or stock in 
our determination of whether an authorization is limited to small 
numbers of marine mammals. When the predicted number of individuals to 
be taken is fewer than one third of the species or stock abundance, the 
take is considered to be of small numbers. Additionally, other 
qualitative factors may be considered in the analysis, such as the 
temporal or spatial scale of the activities.
    The amount of take NMFS proposes to authorize is below one third of 
the estimated stock abundance for all species and stocks (in fact, take 
of individuals is less than 10 percent of the abundance of the affected 
stocks except for harbor seals where take is 12.8 percent, see Table 
7). This is likely a conservative estimate because they assume all 
takes are of different individual animals which is likely not the case. 
Some individuals may return multiple times in a day, but PSOs would 
count them as separate takes if they cannot be individually identified.
    In summary and as described above, the following factors primarily 
support our preliminary determination regarding the incidental take of 
small numbers of a species or stock:
     The take of marine mammal stocks authorized for take 
comprises less than 10 percent of any stock abundance (with the 
exception of harbor seals); and
     Many of the takes would be repeats of the same animal and 
it is likely that a number of individual animals could be taken 10 or 
more times.
    Based on the analysis contained herein of the proposed activity 
(including the proposed mitigation and monitoring measures) and the 
anticipated take of marine mammals, NMFS preliminarily finds that small 
numbers of marine mammals will be taken relative to the population size 
of the affected species or stocks.

Unmitigable Adverse Impact Analysis and Determination

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

Endangered Species Act

    Section 7(a)(2) of the ESA (16 U.S.C. 1531 et seq.) requires that 
each Federal agency insure that any action it authorizes, funds, or 
carries out is not likely to jeopardize the continued existence of any 
endangered or threatened species or result in the destruction or 
adverse modification of designated critical habitat. To ensure ESA 
compliance for the issuance of IHAs, NMFS consults internally whenever 
we propose to authorize take for endangered or threatened species.
    No incidental take of ESA-listed species is proposed for 
authorization or expected to result from this activity. Therefore, NMFS 
has determined that formal consultation under section 7 of the ESA is 
not required for this action.

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
issue an IHA to the MEDOT to conduct the Falls Bridge Replacement 
Project in

[[Page 61181]]

Blue Hill, Maine from July 1, 2022 through June 30, 2023, provided the 
previously mentioned mitigation, monitoring, and reporting requirements 
are incorporated. A draft of the proposed IHA can be found at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act.

Request for Public Comments

    We request comment on our analyses, the proposed authorization, and 
any other aspect of this notice of proposed IHA for the proposed Falls 
Bridge Replacement Project. We also request at this time comment on the 
potential renewal of this proposed IHA as described in the paragraph 
below. Please include with your comments any supporting data or 
literature citations to help inform decisions on the request for this 
IHA or a subsequent Renewal IHA.
    On a case-by-case basis, NMFS may issue a one-time 1 year Renewal 
IHA following notice to the public providing an additional 15 days for 
public comments when (1) up to another year of identical, or nearly 
identical, activities as described in the Description of Proposed 
Activity section of this notice is planned or (2) the activities as 
described in the Description of Proposed Activity section of this 
notice would not be completed by the time the IHA expires and a Renewal 
would allow for completion of the activities beyond that described in 
the Dates and Duration section of this notice, provided all of the 
following conditions are met:
     A request for renewal is received no later than 60 days 
prior to the needed Renewal IHA effective date (recognizing that 
Renewal IHA expiration date cannot extend beyond one year from 
expiration of the initial IHA);
     The request for renewal must include the following:
    (1) An explanation that the activities to be conducted under the 
requested Renewal IHA are identical to the activities analyzed under 
the initial IHA, are a subset of the activities, or include changes so 
minor (e.g., reduction in pile size) that the changes do not affect the 
previous analyses, mitigation and monitoring requirements, or take 
estimates (with the exception of reducing the type or amount of take); 
and
    (2) A preliminary monitoring report showing the results of the 
required monitoring to date and an explanation showing that the 
monitoring results do not indicate impacts of a scale or nature not 
previously analyzed or authorized; and
     Upon review of the request for Renewal, the status of the 
affected species or stocks, and any other pertinent information, NMFS 
determines that there are no more than minor changes in the activities, 
the mitigation and monitoring measures will remain the same and 
appropriate, and the findings in the initial IHA remain valid.

    Dated: November 1, 2021.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2021-24164 Filed 11-4-21; 8:45 am]
BILLING CODE 3510-22-P