Notice2022-13605
Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Tillamook South Jetty Repairs in Tillamook Bay, Oregon
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
June 27, 2022
Issuing agencies
Commerce DepartmentNational Oceanic and Atmospheric Administration
Abstract
NMFS has received a request from the U.S. Army Corps of Engineers (USACE)--Portland District (Corps) for authorization to take marine mammals incidental to 2 years of activity associated with Tillamook South Jetty Repairs in Tillamook Bay, Oregon. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to issue two one-year incidental harassment authorizations (IHAs) to incidentally take marine mammals during the specified activities. NMFS is also requesting comments on a possible one-time, one-year renewal for each IHA 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 notice. NMFS will consider public comments prior to making any final decision on the issuance of the requested MMPA authorization and agency responses will be summarized in the final notice of our decision.
Full Text
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<title>Federal Register, Volume 87 Issue 122 (Monday, June 27, 2022)</title>
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[Federal Register Volume 87, Number 122 (Monday, June 27, 2022)]
[Notices]
[Pages 38116-38141]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2022-13605]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XC074]
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to Tillamook South Jetty Repairs in
Tillamook Bay, Oregon
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice; proposed incidental harassment authorizations; request
for comments on proposed authorizations and possible renewals.
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SUMMARY: NMFS has received a request from the U.S. Army Corps of
Engineers (USACE)--Portland District (Corps) for authorization to take
marine mammals incidental to 2 years of activity associated with
Tillamook South Jetty Repairs in Tillamook Bay, Oregon. Pursuant to the
Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its
proposal to issue two one-year incidental harassment authorizations
(IHAs) to incidentally take marine mammals during the specified
activities. NMFS is also requesting comments on a possible one-time,
one-year renewal for each IHA 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 notice. NMFS will consider
public comments prior to making any final decision on the issuance of
the requested MMPA authorization and agency responses will be
summarized in the final notice of our decision.
DATES: Comments and information must be received no later than July 27,
2022.
ADDRESSES: Comments should be addressed to Jolie Harrison, Chief,
Permits and Conservation Division, Office of Protected Resources,
National Marine Fisheries Service and should be submitted via email to
<a href="/cdn-cgi/l/email-protection#064f5256287463687f727f7569686b69697463466869676728616970"><span class="__cf_email__" data-cfemail="2d64797d035f48435459545e42434042425f486d43424c4c034a425b">[email protected]</span></a>.
Instructions: NMFS is not responsible for comments sent by any
other method,
[[Page 38117]]
to any other address or individual, or received after the end of the
comment period. Comments, including all attachments, must not exceed a
25-megabyte file size. All comments received are a part of the public
record and will generally be posted online at <a href="http://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act">www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act</a> 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: Reny Tyson Moore, 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: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities</a>. 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 proposed or, if the taking is limited to harassment, a notice of a
proposed IHA is provided to the public for review.
Authorization for incidental takings shall be granted if NMFS finds
that the taking will have a negligible impact on the species or
stock(s) 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 actions (i.e., the issuance of two IHAs)
with respect to potential impacts on the human environment.
These actions are 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 IHAs qualifies to be categorically excluded from further NEPA
review.
We will review all comments submitted in response to this notice
prior to concluding our NEPA process or making a final decision on the
IHA requests.
Summary of Request
On February 11, 2022, NMFS received a request from the Corps for
two one-year IHAs to take marine mammals incidental to repairs of the
Tillamook South Jetty in Tillamook Bay, Oregon. The application was
deemed adequate and complete on May 23, 2022. The Corps' request is for
take of five species of marine mammals by Level B harassment and, for a
subset of these species (i.e., harbor seals (Phoca vitulina richardii),
northern elephant seals (Mirounga angustriostris), and harbor porpoises
(Phocoena phocoena)), take by Level A harassment. Neither the Corps nor
NMFS expect serious injury or mortality to result from this activity
and, therefore, IHAs are appropriate.
Description of Proposed Activity
Overview
The Corps constructed, and continues to maintain, two jetties at
the entrance of Tillamook Bay, Oregon to provide reliable navigation
into and out of the bay. A Major Maintenance Report (MMR) was completed
in 2003 to evaluate wave damage to the jetties and provide design for
necessary repairs. Some repairs to the North Jetty were completed in
2010, and further repairs to the North Jetty root and trunk began in
January 2022. The Tillamook South Jetty Repairs Project (i.e., the
``proposed activities'') would complete critical repairs to the South
Jetty, as described in the MMR, with a focus on rebuilding the South
Jetty head. Work would consist of repairs to the existing structures
within the original jetty footprints (i.e., trunk repairs and the
construction of a 100-foot cap to repair the South Jetty Head), with
options to facilitate land- and water-based stone transport, storage,
and placement operations. A temporary material offload facility (MOF),
which would be approximately 15 meters (m) (50 feet (ft)) by 30 m (100
ft), would be constructed to transfer jetty rock from barges to shore
at the South Jetty.
The two IHAs requested by the Corps would be associated with the
construction (Year 1 IHA) and removal (Year 2 IHA) of the temporary
MOF. Construction of the MOF would involve vibratory (preferred) and/or
impact pile driving of up to 10 12-inch H piles, 24 24-inch timber or
steel pipe piles, and 250 24-inch steel sheets (type NZ, AZ, PZ, or
SCZ), and is anticipated to occur during the first year of the project
(November 1, 2022 through October 31, 2023). Removal of the MOF would
involve vibratory extraction of all installed piles and sheets and is
anticipated to occur between November 1, 2024 and October 31, 2025. The
Corps proposed work windows are between November and February and
between July and August each year to adhere to terms and conditions
outlined in the U.S. Fish and Wildlife Service (USFWS) Biological
Opinion (BiOp) to minimize potential take of the Western snowy plover
(WSP), currently listed as threatened under the Endangered Species Act
(ESA). Sounds resulting from pile installation and removal from these
proposed activities may result in the incidental take of marine mammals
by Level A and Level B harassment.
Dates and Duration
Completion of the South Jetty repairs is anticipated to take
multiple construction seasons. The primary in-water sound effects would
be associated with construction (Year 1 IHA) and deconstruction (Year 2
IHA) of a MOF at Kincheloe Point. MOF construction/deconstruction would
only occur during the aforementioned work windows and when weather
conditions would not restrict watercraft operations or compromise crew
safety. The Corps anticipates commencing work in the autumn of 2022.
Construction of the
[[Page 38118]]
MOF is anticipated to take 20 to 23 days and to occur between November
1, 2022 and February 15, 2023 or between July 1, 2023 and August 31,
2023. Deconstruction of the MOF is estimated to take 13 days and is
anticipated to occur between November 1, 2024 and February 15, 2025 or
between July 1, 2025 and August 31, 2025. The Corps plans to conduct
pile driving only during daylight hours (from sunrise to sunset).
Specific Geographic Region
Tillamook Bay is located on the Oregon Coast near the city of
Garibaldi in Tillamook County, Oregon (Figure 1). The Bay is protected
from the open ocean by shoals and a sandbar called the Bayocean
Peninsula. It is generally very shallow, with depths ranging from 0.3
to 2.1 m (1 to 7 ft) throughout most of the Bay, but reaching depths of
up to 10 m (32 ft) in the South, Main, and Bay City Channels. The
sediment in Tillamook Bay consists primarily of sand or mud, and there
are several sea grass beds present in the region. Tillamook Bay
provides a safe harbor for the water-dependent economies of local and
state entities. It is the third largest bay in Oregon and sustains
significant biological and economic resources. The proposed activities
would be located on the Bayocean Split, Tillamook County, Oregon
(Tillamook Bay, River Mile 1; Section 18, 19, and 20 of Township 1N,
Range 10W; Latitude: 45.565500, Longitude: -123.948983).
[GRAPHIC] [TIFF OMITTED] TN27JN22.001
The Port of Garibaldi is located approximately 3.2 kilometers (km)
(2 miles (mi)) east of the entrance to Tillamook Bay and contains a
lumber mill, seafood processing plants, marine repair shops, a
commercial and charter fishing marina, and a public boat launch. The
United States Coast Guard (USCG) Station Tillamook Bay is also located
at the Port of Garibaldi; operations include towing vessels and
assisting recreational and commercial boaters throughout the year with
five search and rescue boats. The U.S. Highway 101 corridor is adjacent
to Tillamook Bay, passing through the coastal cities of Bay City,
Garibaldi, and Barview closest to the South Jetty (see Figure 1-1 in
the Corps' application). The nearest residences to the proposed
activity area are located in Barview, approximately 610 m (2,000 ft)
away on the opposite side of the entrance channel.
Detailed Description of Specific Activity
The purpose of the proposed activities is to protect the structural
integrity of the Tillamook South Jetty and to improve navigation
conditions at the channel entrance through major maintenance repair
activities. As with most jetties along the Oregon coast, the Tillamook
South Jetty was constructed to facilitate safe navigation and support a
more stable entrance channel at the mouth of Tillamook Bay. It was
[[Page 38119]]
constructed in phases between 1969 and 1979 to a final length of 2,046
m (8,025 ft). The South Jetty currently has a total length that is
approximately 320 m (1,050 ft) shorter than the authorized footprint,
and the head is severely damaged with an estimated recession rate of
approximately 8.5 m (28 ft) per year. As with the Tillamook North
Jetty, there has also been erosion of the jetty trunk. No repairs have
occurred since the original construction. The 2003 MMR report and
subsequent 2014 Corps inspection recommended several repair actions
that are the basis for the proposed construction activities. Repair
activities would consist of two main components at the South Jetty:
trunk repairs and construction of a 30 m (100-ft) cap to repair the
South Jetty head.
In addition to stone placement at the South Jetty head and trunk,
related construction activities associated with these repairs,
specifically the delivery and storage of new stone, include the
construction of a temporary MOF near Kincheloe Point; channel dredging
to maintain access to MOF; roadway improvements and possible turnouts
along Bayocean Dike Road; and utilization of two upland staging and
stockpiling areas: one primary staging area adjacent to the South Jetty
trunk and a smaller staging area near the MOF. The Contractor will
ultimately decide on the means and methods for construction, within
these constraints and the conditions outlined in the proposed IHAs.
Given uncertainty about which features will be implemented to
facilitate site access, the Corps' application assumes a temporary MOF,
which requires pile driving, would be constructed to accommodate barge
operations. The proposed activities also include removal and site
restoration for each of the temporary construction features upon
project completion. As discussed in further detail below, NMFS assumes
that take of marine mammals is likely to result only from pile driving
activities conducted as part of the MOF construction/removal and not
from activities related to the delivery, storage, or placement of jetty
stone.
Construction Staging Areas
Jetty repairs and associated construction elements require areas
for equipment and supply staging and storage, parking areas, access
roads, scales, general yard requirements, and jetty stone stockpile
areas. There would be one primary staging area adjacent to the South
Jetty trunk and a smaller staging area near the MOF (Figure 1).
Temporary erosion controls would be put in place before any alteration
of the sites. An Erosion and Sediment Control Plan (ESCP) would outline
facilities and Best Management Practices (BMPs) that would be
implemented and installed prior to any ground-disturbing activities on
the project site, including mobilization. These erosion controls would
prevent pollution caused by surveying or construction operations and
ensure sediment-laden water do not leave the project site, enter
Tillamook Bay, or impact aquatic and terrestrial wildlife.
Ocean barging is anticipated to be the primary method of material
and equipment transport; however, Bayocean Dike Road (Figure 1) would
be used to access the staging areas and work sites. Prior to
construction, the road would be improved to facilitate the necessary
level of construction traffic. Specific details and locations of road
improvement actions would depend on the condition of the road at the
start of construction, however any improvements or alterations would
avoid wetlands and waters of the U.S. to the maximum extent
practicable. Roadway improvements would also avoid any locations
identified as having significant cultural resources.
There are no known pinnipeds haul-outs on the sites proposed for
these staging areas or near the proposed access roads (see Description
of Marine Mammals in the Area of Specified Activities). Therefore,
upland activities related to the development of the staging areas and
access roads are not anticipated to impact any marine mammal species,
and are not considered further in our analysis.
Temporary Material Offloading Facility
A temporary MOF is needed to transfer jetty rock from barges to
shore at the South Jetty. The MOF would provide moorage for barges and
a structure for crane support. The preferred location of the MOF is on
the south side of Kincheloe Point, on the site of a former staging area
(Figure 1). Detailed design of the MOF would be completed closer to the
time of construction. The discussion below is based on general
assumptions about likely design elements. These assumptions represent a
conservative scenario for purposes of analysis.
The offloading platform could require the use of an anchor line
moorage or dolphins. The platform would be approximately 15 m (50 ft)
by 30 m (100 ft) and would be constructed using a sheet pile perimeter
wall, installed using a vibratory hammer. A maximum of 24, 24-inch
timber or steel piles would be installed as mooring dolphins, up to 10,
12-inch steel H-piles will be installed for support, and up to 250, 24-
inch steel sheets (type NZ, AZ, PZ, or SCZ) would be driven for the
perimeter wall. The maximum pile diameter would be 24 inches, and caps
(or other deterrence devices) would be installed on each pile to
discourage birds from perching. The platform would be constructed
within the confines of the perimeter wall by filling in the area with
backfill. The H-piles would be shoreward of installed sheets and most
likely driven into the fill material with very little water, if any. A
contractor would be limited by these general constraints, but the final
MOF design would be per their discretion, largely based on site
conditions, material availability, and cost. The MOF would be sited to
avoid direct impacts to eelgrass during construction. In-water noise
incidental to vibratory and impact pile driving of the MOF is
anticipated to result in Level A harassment and/or Level B harassment.
Vibratory hammers are the preferred method of pile installation.
However, impact driving may be required for steel pipe piles if
vibratory means prove infeasible (impact pile driving would not be
required for any other pile type). For any impact driving of steel
piles, a confined bubble curtain will be used to reduce in-water sound.
Pile driving to construct the MOF is anticipated to take 20 (vibratory
installation methods only) to 23 (vibratory and impact installation
methods) days over the course of a month (Table 1) and would occur
under the first IHA (Year 1). Multiple piles would not be driven
concurrently. Vibratory hammers would be used to remove the temporary
MOF and is anticipated to take an additional 13 days over the course of
a month (Table 1). Deconstruction would occur under the second IHA
(Year 2).
[[Page 38120]]
Table 1--Summary of Pile Details and Estimated Effort Required for the Construction and Deconstruction of the Temporary MOF
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Production rate (piles/day) Range of
Potential ----------------------------------------- installation days Range of
Number of Vibratory Vibratory removal impact anticipated \1\ vibratory
Pile type Size sheets/ installation duration per pile/ strikes ---------------------- removal
piles duration per pile/ sheet (minutes) per pile, Installation Installation Removal Vibratory days
sheet (minutes) if needed (vibratory) (impact) (vibratory) Vibratory and anticipated
only impact \1\
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AZ Steel Sheet \2\................. 24-inch........ 250 10................. 3.................. ......... 25 ............ 50 10-12 10-12 5-7
Timber or Steel Pile............... 24-inch........ 24 15................. 5.................. 533 8 4 12 3-6 6-9 2-4
H-Pile............................. 12-inch........ 10 10................. 3.................. ......... 10 ............ 10 1-2 1-2 1-2
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Project totals 284 49.83 hours........ 16.17 hours........ ......... ............ ............ ........... 14-20 17-23 8-13
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\1\ The minimum days of installation and removal are based on the expected production rates. The maximum days of installation and removal are estimated assuming built in contingency days,
which have been added into the construction schedule, are needed.
\2\ Or comparable.
Dredging
In order to allow fully loaded barges to access the MOF, dredging
would occur prior to the construction of the platform. Based on the
conditions at the preferred MOF location, it is conservatively
estimated that no more than 5,000 cubic yards of material would be
dredged. The barge route from the main channel to the MOF will be sited
to avoid potential adverse effects to eelgrass to the maximum extent
practicable. The area dredged would include the area adjacent to the
shore where the barge would be moored (see Figure 1-4 in the Corps'
application). Sandy dredged material removed to facilitate barge access
would be placed in the Primary Staging Area as indicated in Figure 1-3
in the Corps' application and used to fill depressions and create
better habitat for WSP post construction.
The scope and duration of dredging would be limited to the minimum
area and amount of time needed to achieve project purposes. Initial MOF
dredging would take approximately one week to complete, and will occur
between July 15 and March 15 to avoid the peak timing for juvenile coho
salmon outmigration. Ongoing maintenance will occur as needed. Only
mechanical dredging would be permissible, and dredges would be operated
to limit dredge spillover.
The Corps will work to meet state water quality standards. To
minimize water turbidity and the potential for entrainment of organisms
during dredging for the MOF, the clamshell bucket or head of the dredge
would remain on the bottom to the greatest extent possible and only be
raised 1 m (3 ft) off the bottom when necessary for dredge operations.
Turbidity levels will be monitored via visual observations to identify
any adverse detectable change in water quality. A hand-held turbidity
meter will be deployed and used during MOF dredging and fill
activities. No more than 10 percent cumulative increase in natural
stream turbidities may be allowed, as measured relative to a control
point immediately upstream of the turbidity causing activity. However,
limited duration activities necessary to address an emergency or to
accommodate essential dredging, construction, or other legitimate
activities and which cause the standard to be exceeded may occur
provided all practicable turbidity control techniques have been
applied. See Oregon Administrative Rules (OAR) 340-041-0036.
While dredging may produce underwater noise above the relevant
harassment threshold (i.e., between 150 and 180 dB; Clark et al., 2002;
Miles et al., 1986), the noise produced by dredging is similar to other
common on-and in-water industrial activities typically occurring in the
area. Additionally, dredging will only occur in a relatively small and
confined area of Tillamook Bay over a short duration of time (i.e., 5
days), limiting the potential for impacts. Therefore, incidental takes
of marine mammals are not anticipated or proposed to be authorized for
dredging activities, and this activity is not considered further in our
analysis.
South Jetty Maintenance and Repairs
Significant repairs are proposed along the South Jetty, where the
majority of work would occur from STA 70+00 westward. These stations
are enumerated in 30 m (100-ft) increments such that STA 71+00 would be
30 m (100 ft) seaward from STA 70+00. Additional repairs to the jetty
trunk between Stations 43+00 and 49+00 are also planned. The jetty cap
will be from STA 77+00 to 77+75 to elevation + 5.5 m (18 ft) relative
to North American Vertical Datum of 1988 (NAVD88). From the final head
station centerline, the end of the jetty will be built out in a 6 m (20
ft) radius to elevation + 5.5 m (18 ft) NAVD88. The crest width of the
jetty cap would be 12 m (40 ft). The crest width of the jetty trunk
would be 9 m (30 ft) with a target crest elevation of + 5.5 m (18 ft)
NAVD88. The average stone density would be approximately 180 pounds
(lbs)/ft\3\, and the total quantity of stone required for the proposed
activities is estimated at 31,000 cubic yards (~76,000 tons). Stone
placement at the South Jetty would take just under 150 working days.
While placement of jetty stone could produce noise, NMFS has
determined that sounds produced from this action would not exceed
marine mammal thresholds beyond 10 m (33 ft) from the source in the
water and beyond 100 m (328 ft) from the source in the air (86 FR
22151; April 27, 2021). There are no known pinniped haul-outs or other
known important marine mammal habitats within the vicinity of the South
Jetty (see Description of Marine Mammals in the Area of Specified
Activities) limiting the potential for impacts from stone placement.
Therefore, incidental takes of marine mammals are not anticipated or
proposed to be authorized for jetty stone placement, and are not
considered further in our analysis.
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. NMFS
fully considered all of this information, and we refer the reader to
these descriptions, incorporated here by reference, instead
[[Page 38121]]
of reprinting the information. Additional information regarding
population trends and threats may be found in NMFS' Stock Assessment
Reports (SARs; <a href="http://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a>) and more general
information about these species (e.g., physical and behavioral
descriptions) may be found on NMFS' website (<a href="https://www.fisheries.noaa.gov/find-species">https://www.fisheries.noaa.gov/find-species</a>).
Table 2 lists all species or stocks for which take is expected and
proposed to be authorized for these activities, and summarizes
information related to the population or stock, including regulatory
status under the MMPA and ESA and potential biological removal (PBR),
where known. 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' SARs). While no
serious injury or 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' 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' U.S. Pacific SARs (e.g., Carretta et al. 2021) or Alaska SARs
(e.g., Muto et al. 2020). All values presented in Table 2 are the most
recent available at the time of publication and are available in the
2020 SARs (Carretta et al. 2021, Muto et al., 2020) and draft 2021 SARs
(available online at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports">https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports</a>).
Table 2--Species Likely Impacted by the Specified Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
Stock abundance Nbest,
ESA/MMPA status; (CV, Nmin, most recent Annual M/
Common name Scientific name MMPA stock strategic (Y/N) abundance survey) \2\ PBR SI \3\
\1\
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Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Phocoenidae (porpoises):
Harbor Porpoise................. Phocoena phocoena...... Northern OR/WA Coast... -,-, N 21,487 (0.44; 15,123; 151 >=3.0
2011).
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Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and
sea lions):
California sea lion............. Zalophus californianus. U.S.................... -,-, N 257,606 (N/A.; 14,011 >320
233,515; 2014).
Steller sea lion................ Eumetopias jubatus..... Eastern................ -,-, N 43,201 (N/A; 43,201; 2,592 112
2017).
Family Phocidae (earless seals):
Harbor seal..................... Phoca vitulina OR/CA Coastal.......... -, N 24,732 (0.12; N/A; UND 10.6
richardii. 1999).
Northern elephant seal.......... Mirounga angustirostris California Breeding.... -,-, N 187,386 (N/A; 85,369; 5,122 5.3
2013).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a> assessments.CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable (N.A.).
\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 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.
As indicated above, all 5 species (with 5 managed stocks) in Table
2 temporally and spatially co-occur with the activity to the degree
that take is reasonably likely to occur. All species (26 marine mammal
species and 27 marine mammal stocks) that could potentially occur in
the proposed survey areas are included in Table 3-3 of the Corps'
application. The majority of the species listed in the Corps' table are
unlikely to occur in the project vicinity. For example, numerous
cetaceans (i.e., sei whale, Balaenoptera borealis borealis; fin whale,
Balaenoptera physalus physalus; Risso's dolphin, Grampus griseus;
common bottlenose dolphin, Tursiops truncatus truncatus; striped
dolphin, Stenella coeruleoalba; common dolphin, Delphinus delphis;
short-finned pilot whale, Globicephala macrorhynchus; Baird's beaked
whale, Berardius bairdii; Mesoplodont beaked whale, Mesoplodon spp.;
Cuvier's beaked whale, Ziphius cavirostris; pygmy sperm whale, Kogia
breviceps; dwarf sperm whale, Kogia sima; sperm whale, Physeter
macrocephalus) are only encountered at the continental slope (>20 km/12
mi offshore) or in deeper waters offshore and would not be affected by
construction activities. Other species may occur closer nearshore but
are rare or infrequent seasonal inhabitants off the Oregon coast (i.e.,
minke whale, Balaenoptera acutorostrata scammoni; Pacific white-sided
dolphin, Lagenorhynchus obliquidens; Northern right-whale dolphin,
Lissodelphis borealis; killer whale, Orcinus orca (``Eastern North
Pacific Southern Resident Stock''); Dall's porpoise, Phocoenoides dalli
dalli). Given these considerations, the temporary duration of potential
pile driving, and noise isopleths that would not extend beyond the bay
entrance (please see Estimated Take), there is no reasonable
expectation for the proposed activities to affect the above species and
they will not be addressed further.
While ten marine mammal species could occur in the vicinity of the
proposed project activities (i.e., harbor seals; Northern elephant
seal; Steller sea lion; California sea lion; humpback whales, Megaptera
novaeangliae; fin whales, Balaenoptera physalus physalus; gray whales,
Eschrichtius robustus; blue whales, Balaenoptera musculus musculus;
killer whales, Orcinus orca; and harbor porpoises), Tillamook Bay is
relatively shallow and
[[Page 38122]]
noise resulting from the construction/deconstruction of the MOF would
be limited to the interior waters of the bay and would not extend to
coastal waters. Larger whales (e.g., humpback whales, fin whales, gray
whales, blue whales, killer whales) may transit the waters near the
coastline but are unlikely inhabitants of Tillamook Bay itself. In
reviewing OBIS-SEAMAP (2022) and records for all marine mammals
recorded within a 16 km (10 mi) radius of Tillamook Bay, only humpback
whales, gray whales, harbor porpoises, California sea lions, Steller
sea lions, and harbor seals were commonly reported. Killer whales have
only been seen on rare occasions (TinyFishTV, 2014; rempeetube, 2016;
Corey.c, 2017), and Dall's porpoise (and northern right whale dolphins
have been reported a bit further offshore (Halpin et al., 2009; OBIS-
SEAMAP, 2022). Gray whales and humpback whales have been observed in
the vicinity of Tillamook Bay, however, they are highly unlikely to
enter the relatively shallow waters of Tillamook Bay and be subject to
pile driving noise disturbance. Given these considerations, take of
these species (i.e., humpback whales, fin whales, gray whales, blue
whales, killer whales) is not expected to occur, and they are not
discussed further beyond the explanation provided here.
Harbor Porpoise
In the Pacific Ocean, harbor porpoise are found in coastal and
inland waters from Point Conception, California to Alaska and across to
Kamchatka and Japan (Gaskin, 1984). Six harbor porpoise stocks have
been designated off California/Oregon/Washington, based on genetic
analyses and density discontinuities identified from aerial surveys.
While harbor porpoise are rare within Tillamook Bay, if present,
animals likely belong to the Northern Oregon/Washington Coast stock,
which is delimited from Cape Flattery, Washington (located
approximately 320 km (198 mi) north of Tillamook Bay), to Lincoln City,
Oregon (located approximately 68 km (42 mi) south of Tillamook Bay)
(Carretta et al., 2022).
Entanglement is the primary cause of human-related injury and death
for harbor porpoises, however, estimated fishery mortality and serious
injury rates are well below PBR. Harbor porpoises are sensitive to
disturbance by a variety of anthropogenic sound sources, and the
limited range of several U.S. West Coast harbor porpoise stocks makes
them particularly vulnerable to potential impacts (see overview in
Forney et al., 2017).
Harbor porpoises on the Pacific Northwest coast of the United
States are typically found in waters roughly 100-200 m (328-656 ft)
deep (NOAA, 2013a; Holdman et al. 2018). They occur along the Oregon
coast year-around and may be slightly more abundant in summer and
exhibit diel or tidal movement patterns related to prey availability
(Holdman et al., 2018). Harbor porpoises have been detected within a 16
km (10 mi) radius of the Tillamook Bay entrance channel (Halpin et al.,
2009; OBIS-SEAMAP, 2022), and they could potentially occur in the
project vicinity during the proposed activities.
California Sea Lion
California sea lions are distributed along the North Pacific waters
from central Mexico to southeast Alaska, with breeding areas restricted
primarily to island areas off southern California (the Channel
Islands), Baja California, and in the Gulf of California (Carretta et
al., 2021). There are five genetically distinct geographic populations.
The population seen in Oregon is the Pacific Temperate population
(which comprises the U.S. stock managed by NMFS), which are commonly
seen in Oregon from September through May (ODFW, 2015).
The occurrence of the California sea lion along the Oregon coast is
seasonal with lowest abundance in Oregon in the summer months, from May
to September, as they migrate south to the Channel Islands in
California to breed. They are commonly found in Oregon haul-out sites
from September to May and during this period, adult and subadult males
have been observed in bays, estuaries, and offshore rocks along the
Oregon coast. In fact, a few males have been reported in Oregon waters
throughout the year (Mate, 1973). The population breeds in the
California Channel Islands and most females and young pups remain in
that region year-around (Mate, 1973).
The California sea lion stock has been growing steadily since the
1970s. The stock is estimated to be approximately 40 percent above its
maximum net productivity level (MNPL = 183,481 animals), and it is
therefore considered within the range of its optimum sustainable
population (OSP) size (Laake et al., 2018). The stock is also near its
estimated carrying capacity of 275,298 animals (Laake et al., 2018).
However, there remain many threats to California sea lions including
entanglement, intentional kills, harmful algal blooms, and climate
change. For example, for each 1 degree Celsius increase in sea surface
temperature (SST), the estimated odds of survival declined by 50
perfect for pups and yearlings, while negative SST anomalies resulted
in higher survival estimates (DeLong et al., 2017). Such declines in
survival are related to warm oceanographic conditions (e.g., El
Ni[ntilde]o) that limit prey availability to pregnant and lactating
females (DeLong et al., 2017). Changes in prey abundance and
distribution have been linked to warm-water anomalies in the California
Current that have impacted a wide range of marine taxa (Cavole et al.,
2016), including California sea lions. For example, between 2013 and
2017, NOAA declared an unusual mortality event (UME) for California sea
lions as high mortality of pup and juvenile age classes were documented
during this time. NOAA identified changes in the availability of sea
lion prey species, particularly sardines, as a contributing factor.
California sea lions may occur in the project vicinity, but there
have been no confirmed sightings in Tillamook Bay (Halpin et al., 2009;
OBIS-SEAMAP, 2022). The closest known haul out site is at Three Arch
Rock, which is approximately 23 km (14 mi) south of the proposed site
of the MOF.
Steller Sea lion
The Steller sea lion range extends along the Pacific Rim, from
northern Japan to central California. For management purposes, Steller
sea lions inhabiting U.S. waters have been divided into two DPS: the
Western U.S. and the Eastern U.S. Steller sea lions encountered off the
Oregon coast are part of the Eastern U.S. Stock, with rookeries in
California, Oregon, Washington, Southeast Alaska, and British Columbia
(Muto et al., 2021). The Western U.S. stock of Steller sea lions are
listed as endangered under the ESA and depleted and strategic under the
MMPA. The Eastern U.S. stock (including those living in Oregon) was de-
listed in 2013 following a population growth from 18,040 in 1979 to
70,174 in 2010 (an estimated annual growth of 4.18 percent) (NMFS,
2013). A population growth model indicates the eastern stock of Steller
sea lions increased at a rate of 4.25 percent per year (95 percent
confidence intervals of 3.77-4.72 percent) between 1987 and 2017 based
on an analysis of pup counts in California, Oregon, British Columbia,
and Southeast Alaska (Muto et al., 2021). This stock is likely within
its OSP; however, no determination of its status relative to OSP has
been made (Muto et al., 2021).
Off the Oregon coast, Steller sea lions have been observed ashore
from the Columbia River south to Rogue Reef and typically inhabit
offshore rocks and
[[Page 38123]]
islands. There are seven major haul-out sites noted in Oregon during
the breeding season, however, there are no known rookery sites near
Tillamook Bay (Pitcher et al., 2007). The closest known haul out site
is at Three Arch Rock, which is approximately 23 km (14 mi) south of
the proposed site of the MOF. Steller sea lions have been detected in
Tillamook Bay during marine mammal surveys (Pearson and Verts, 1970;
Halpin et al., 2009; Ford et al., 2013) and may occur in the vicinity
of the project.
Harbor Seal
Harbor seals inhabit coastal and estuarine waters off Baja
California, north along the western coasts of the continental U.S.,
British Columbia, and Southeast Alaska, west through the Gulf of Alaska
and Aleutian Islands, and in the Bering Sea north to Cape Newenham and
the Pribilof Islands (Caretta et al., 2021). Within U.S. west coast
waters, five stocks of harbor seals are recognized: (1) Southern Puget
Sound (south of the Tacoma Narrows Bridge); (2) Washington Northern
Inland Waters (including Puget Sound north of the Tacoma Narrows
Bridge, the San Juan Islands, and the Strait of Juan de Fuca); (3) Hood
Canal; (4) Oregon/Washington Coast; and (5) California. Seals
potentially affected by this activity would be part of the Oregon/
Washington Coast stock.
Harbor seals generally are non-migratory, with local movements
associated with tides, weather, season, food availability, and
reproduction (Scheffer and Slipp, 1944; Fisher, 1952; Bigg 1969, 1981).
Harbor seals do not make extensive pelagic migrations, though some long
distance movement of tagged animals in Alaska (900 km, 559 mi) and
along the U.S. west coast (up to 550 km, 342 mi) have been recorded
(Brown and Mate, 1983; Herder, 1986; Womble, 2012). Harbor seals have
displayed strong fidelity to haulout sites (Pitcher and Calkins, 1979;
Pitcher and McAllister, 1981).
Harbor seals were historically hunted in Oregon as a nuisance to
fishermen, however, their numbers have steadily increased since the
passage of the MMPA in 1972 (Harvey, 1987; Brown et al., 2005). While
harbor seals are still subject to incidental take from commercial
fisheries in the region, overall mortality is relatively low. However,
the most recent abundance estimate available for this stock dates to
1999 (Carretta et al., 2021).
Harbor seals are one of the most abundant pinnipeds in Oregon and
can typically be found in coastal marine and estuarine waters of the
Oregon coast throughout the year. On land, they can be found on
offshore rocks and islands, along shore, and on exposed flats in the
estuary (Harvey, 1987). There is one haul-out site roughly 1.5 km (0.9
mi) east of the proposed MOF that has been historically noted in
Tillamook Bay. This haul-out is located on an intertidal sand flat in
the middle of the bay (See Figure 4-1 in the Corps' application) and
highest utilization has been observed during the May/June reproductive
season (B.E. Wright, personal communication, February 12, 2021; ODFW,
2022). This is consistent with other findings noting harbor seals being
more abundant in Tillamook Bay during the summer pupping season (Brown
and Mate, 1983). There is also evidence that animals may move between
Netarts Bay, a prominent feeding site located approximately 15 km (9
mi) south of Tillamook Bay, and Tillamook Bay in the non-pupping season
(Brown and Mate, 1983). Therefore, harbor seals are expected to occur
in the vicinity of the project.
Northern Elephant Seal
The California Breeding Stock of Northern elephant seals breeds and
gives birth in California and makes extended foraging trips to areas
including coastal Oregon biannually during the fall and spring (Le
Boeuf et al., 2000). While both males and females may transit areas off
the Oregon coast, males seem to have focal forage areas near the
continental shelf break while females typically move further offshore
and feed opportunistically at numerous sites while in route (Le Beouf
et al., 2000).
Populations of northern elephant seals in the U.S. and Mexico have
recovered after being nearly hunted to extinction (Stewart et al.,
1994). Northern elephant seals underwent a severe population bottleneck
and loss of genetic diversity when the population was reduced to an
estimated 10-30 individuals (Hoelzel et al., 2002). Although movement
and genetic exchange continues between rookeries, most elephant seals
return to natal rookeries when they start breeding (Huber et al.,
1991). The California breeding population is now demographically
isolated from the Baja California population. No international
agreements exist for the joint management of this species by the U.S.
and Mexico. The California breeding population is considered to be a
separate stock (Carretta et al., 2022).
The population is currently susceptible to incidental take and
injury from gillnet and trawl fisheries operating offshore, however,
the human-caused mortality is still well below the estimated PBR level.
There have been no recorded sightings of northern elephant seals in
the immediate vicinity of Tillamook Bay, however, there have been
sightings toward Netarts Bay, located approximately 14 km (9 mi) south
of the Tillamook South Jetty, and further offshore (Halpin et al.,
2009; OBIS-SEAMAP, 2022). Therefore, northern elephant seals could
transit the area.
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. 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, 2019) recommended that marine mammals be divided into hearing
groups based on directly measured (behavioral or auditory evoked
potential techniques) or estimated hearing ranges (behavioral response
data, anatomical modeling, etc.). 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 3.
[[Page 38124]]
Table 3--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.
Potential Effects of Specified Activities on Marine Mammals and Their
Habitat
This section includes a 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 whether those impacts are reasonably
expected to, or reasonably likely to, adversely affect the species or
stock through effects on annual rates of recruitment or survival
Acoustic effects on marine mammals during the specified activity
can occur from impact and vibratory pile driving. The effects of
underwater noise from the Corps' proposed activities have the potential
to result in Level A and Level B harassment of marine mammals in the
action area.
Description of Sound Sources
This section contains a brief technical background on sound, on the
characteristics of certain sound types, and on metrics used in this
proposal inasmuch as the information is relevant to the specified
activity and to a discussion of the potential effects of the specified
activity on marine mammals found later in this document. For general
information on sound and its interaction with the marine environment,
please see, e.g., Au and Hastings (2008); Richardson et al. (1995);
Urick (1983).
Sound travels in waves, the basic components of which are
frequency, wavelength, velocity, and amplitude. Frequency is the number
of pressure waves that pass by a reference point per unit of time and
is measured in hertz (Hz) or cycles per second. Wavelength is the
distance between two peaks or corresponding points of a sound wave
(length of one cycle). Higher frequency sounds have shorter wavelengths
than lower frequency sounds, and typically attenuate (decrease) more
rapidly, except in certain cases in shallower water. Amplitude is the
height of the sound pressure wave or the ``loudness'' of a sound and is
typically described using the relative unit of the dB. A sound pressure
level (SPL) in dB is described as the ratio between a measured pressure
and a reference pressure (for underwater sound, this is 1 microPascal
([mu]Pa)), and is a logarithmic unit that accounts for large variations
in amplitude; therefore, a relatively small change in dB corresponds to
large changes in sound pressure. The source level represents the SPL
referenced at a distance of 1 m from the source (referenced to 1
[mu]Pa), while the received level is the SPL at the listener's position
(referenced to 1 [mu]Pa).
Root mean square (RMS) is the quadratic mean sound pressure over
the duration of an impulse. RMS is calculated by squaring all of the
sound amplitudes, averaging the squares, and then taking the square
root of the average (Urick, 1983). RMS accounts for both positive and
negative values; squaring the pressures makes all values positive so
that they may be accounted for in the summation of pressure levels
(Hastings and Popper, 2005). This measurement is often used in the
context of discussing behavioral effects, in part because behavioral
effects, which often result from auditory cues, may be better expressed
through averaged units than by peak pressures.
Sound exposure level (SEL; represented as dB referenced to 1
micropascal squared per second (re 1 [mu]Pa\2\-s)) represents the total
energy in a stated frequency band over a stated time interval or event,
and considers both intensity and duration of exposure. The per-pulse
SEL is calculated over the time window containing the entire pulse
(i.e., 100 percent of the acoustic energy). SEL is a cumulative metric;
it can be accumulated over a single pulse, or calculated over periods
containing multiple pulses. Cumulative SEL (SELcum) represents the
total energy accumulated by a receiver over a defined time window or
during an event. Peak sound pressure (also referred to as zero-to-peak
sound pressure or 0-pk) is the maximum instantaneous sound pressure
measurable in the water at a specified distance from the source, and is
represented in the same units as the RMS sound pressure.
When underwater objects vibrate or activity occurs, sound-pressure
waves are created. These waves alternately compress and decompress the
water as the sound wave travels. Underwater sound waves radiate in a
manner similar to ripples on the surface of a pond and may be either
directed in a beam or beams or may radiate in all directions
(omnidirectional sources), as is the case for sound produced by the
pile driving activity considered here. The compressions and
decompressions associated with sound waves are detected as changes in
pressure by aquatic life and man-made sound receptors such as
hydrophones.
Even in the absence of sound from the specified activity, the
underwater environment is typically loud due to
[[Page 38125]]
ambient sound, which 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 a region is defined by
the total acoustical energy being generated by known and unknown
sources. These sources may include physical (e.g., wind and waves,
earthquakes, ice, atmospheric sound), biological (e.g., sounds produced
by marine mammals, fish, and invertebrates), and anthropogenic (e.g.,
vessels, dredging, construction) sound. A number of sources contribute
to ambient sound, including wind and waves, which are a main source of
naturally occurring ambient sound for frequencies between 200 Hz and 50
kilohertz (kHz) (Mitson, 1995). In general, ambient sound levels tend
to increase with increasing wind speed and wave height. Precipitation
can become an important component of total sound at frequencies above
500 Hz, and possibly down to 100 Hz during quiet times. Marine mammals
can contribute significantly to ambient sound levels, as can some fish
and snapping shrimp. The frequency band for biological contributions is
from approximately 12 Hz to over 100 kHz. Sources of ambient sound
related to human activity include transportation (surface vessels),
dredging and construction, oil and gas drilling and production,
geophysical surveys, sonar, and explosions. Vessel noise typically
dominates the total ambient sound for frequencies between 20 and 300
Hz. In general, the frequencies of anthropogenic sounds are below 1 kHz
and, if higher frequency sound levels are created, they attenuate
rapidly.
A recent study of ambient ocean sound for Oregon's nearshore
environment observed maximum and minimum levels of 136 dB re 1 [mu]Pa
and 95 dB re 1 [mu]Pa, respectively, with an average level of 113 dB re
1 [mu]Pa over a period of one year (Haxel et al., 2011). This level
could vary given the presence of different recreational and commercial
vessels (e.g., up to 150 dB for small fishing vessels (Hildebrand,
2005), up to 186 dB for large vessels, 81 to 166 dB for empty tugs and
barges and up to 170 dB for loaded tugs and barges (Richardson et al.,
1995) within the frequencies between 20 and 5000 Hz), or other factors
(e.g., wind and waves, traffic noise along adjacent roadways, aquatic
animals, currents, etc.) as described above. No direct data on ambient
noise levels within Tillamook Bay are available; however, in-water
ambient noise levels are considered comparable to similar bays.
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 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 may
include impact pile driving, and vibratory pile driving and removal.
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., aircraft,
machinery operations such as drilling or dredging, vibratory pile
driving, 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 rapid 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).
Two types of hammers would be used on this project: impact and
vibratory. 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 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).
The likely or possible impacts of the Corps' proposed activities on
marine mammals could involve both non-acoustic and acoustic stressors.
Potential non-acoustic stressors could result from the physical
presence of the equipment and personnel; however, given there are no
known pinniped haul-out sites in the vicinity of the proposed site of
the MOF construction/deconstruction, visual and other non-acoustic
stressors would be limited, and 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 and removal is the primary means by which
marine mammals may be harassed from the Corps' specified activities. 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, 2019). In general, exposure
to pile driving 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 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)
[[Page 38126]]
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). When analyzing the auditory effects of noise exposure, it is
often helpful to broadly categorize sound as either impulsive or non-
impulsive. When considering auditory effects, vibratory pile driving is
considered a non-impulsive source while impact pile driving is treated
as an impulsive source.
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 et al., 2008). PTS levels for marine mammals are estimates,
as 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
(2015), marine mammal studies have shown the amount of TTS increases
with 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.
Relationships between TTS and PTS thresholds have not been studied
in marine mammals, and there is no PTS data for cetaceans, but such
relationships are assumed to be similar to those in humans and other
terrestrial mammals. PTS typically occurs at exposure levels at least
several decibels above (a 40-dB threshold shift approximates PTS onset;
e.g., Kryter et al., 1966; Miller, 1974) that inducing mild TTS (a 6-dB
threshold shift approximates TTS onset; e.g., Southall et al., 2007).
Based on data from terrestrial mammals, a precautionary assumption is
that the PTS thresholds for impulse sounds (such as impact pile driving
pulses as received close to the source) are at least 6 dB higher than
the TTS threshold on a peak-pressure basis and PTS cumulative sound
exposure level thresholds are 15 to 20 dB higher than TTS cumulative
sound exposure level thresholds (Southall et al., 2007). Given the
higher level of sound or longer exposure duration necessary to cause
PTS as compared with TTS, it is considerably less likely that PTS could
occur.
TTS is the mildest form of hearing impairment that can occur during
exposure to sound (Kryter, 1985). While experiencing TTS, the hearing
threshold rises, and a sound must be at a higher level in order to be
heard. In terrestrial and marine mammals, TTS can last from minutes or
hours to days (in cases of strong TTS). In many cases, hearing
sensitivity recovers rapidly after exposure to the sound ends.
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). 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).
Construction and deconstruction of the MOF, which is required to
repair the Tillamook South Jetty, requires a combination of impact pile
driving and vibratory pile driving. During this project, these
activities will not occur at the same time and there will be pauses in
activities producing the sound during each day. Given these pauses and
that many marine mammals are likely moving through the project area and
not remaining for extended periods of time, the potential for TTS
declines.
Behavioral Harassment--Exposure to noise from pile driving and
removal also has the potential to behaviorally disturb marine mammals.
Behavioral disturbance may include a variety of effects, including
subtle changes in behavior (e.g., minor or brief avoidance
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of an area or changes in vocalizations), more conspicuous changes in
similar behavioral activities, and more sustained and/or potentially
severe reactions, such as displacement from or abandonment of high-
quality habitat. Disturbance may result in changing durations of
surfacing and dives, changing direction and/or speed; reducing/
increasing vocal activities; changing/cessation of certain behavioral
activities (such as socializing or feeding); eliciting a visible
startle response or aggressive behavior (such as tail/fin 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., 2003; 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) and Gomez et al. (2016) for reviews of studies involving
marine mammal behavioral responses to sound.
Habituation can occur when an animal's response to a stimulus wanes
with repeated exposure, usually in the absence of unpleasant associated
events (Wartzok et al., 2003). Animals are most likely to habituate to
sounds that are predictable and unvarying. It is important to note that
habituation is appropriately considered as a ``progressive reduction in
response to stimuli that are perceived as neither aversive nor
beneficial,'' rather than as, more generally, moderation in response to
human disturbance (Bejder et al., 2009). The opposite process is
sensitization, when an unpleasant experience leads to subsequent
responses, often in the form of avoidance, at a lower level of
exposure.
As noted above, behavioral state may affect the type of response.
For example, animals that are resting may show greater behavioral
change in response to disturbing sound levels than animals that are
highly motivated to remain in an area for feeding (Richardson et al.,
1995; NRC, 2003; Wartzok et al., 2003). Controlled experiments with
captive marine mammals have showed pronounced behavioral reactions,
including avoidance of loud sound sources (Ridgway et al., 1997;
Finneran et al., 2003). Observed responses of wild marine mammals to
loud pulsed sound sources (typically seismic airguns or acoustic
harassment devices) have been varied but often consist of avoidance
behavior or other behavioral changes suggesting discomfort (Morton and
Symonds, 2002; see also Richardson et al., 1995; Nowacek et al., 2007).
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). However, there are broad categories of potential response, which
we describe in greater detail here, that include alteration of dive
behavior, alteration of foraging behavior, effects to breathing,
interference with or alteration of vocalization, avoidance, and flight.
Changes in dive behavior can vary widely and may consist of
increased or decreased dive times and surface intervals as well as
changes in the rates of ascent and descent during a dive (e.g., Frankel
and Clark, 2000; Costa et al., 2003; Ng and Leung, 2003; Nowacek et
al., 2004; Goldbogen et al., 2013a,b). Variations in dive behavior may
reflect interruptions in biologically significant activities (e.g.,
foraging) or they may be of little biological significance. The impact
of an alteration to dive behavior resulting from an acoustic exposure
depends on what the animal is doing at the time of the exposure and the
type and magnitude of the response.
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.
Variations in respiration naturally vary with different behaviors
and alterations to breathing rate as a function of acoustic exposure
can be expected to co-occur with other behavioral reactions, such as a
flight response or an alteration in diving. However, respiration rates
in and of themselves may be representative of annoyance or an acute
stress response. Various studies have shown that respiration rates may
either be unaffected or could increase, depending on the species and
signal characteristics, again highlighting the importance in
understanding species differences in the tolerance of underwater noise
when determining the potential for impacts resulting from anthropogenic
sound exposure (e.g., Kastelein et al., 2001, 2005, 2006; Gailey et
al., 2007).
Marine mammals vocalize for different purposes and across multiple
modes, such as whistling, echolocation click production, calling, and
singing. Changes in vocalization behavior in response to anthropogenic
noise can occur for any of these modes and may result from a need to
compete with an increase in background noise or may reflect increased
vigilance or a startle response. For example, in the presence of
potentially masking signals, humpback whales and killer whales have
been observed to increase the length of their songs (Miller et al.,
2000; Fristrup et al., 2003; Foote et al., 2004), while right whales
(Eubalaena glacialis) have been observed to shift the frequency content
of their calls upward while reducing the rate of calling in areas of
increased anthropogenic noise (Parks et al., 2007). In some cases,
animals may cease sound production during production of aversive
signals (Bowles et al., 1994).
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Avoidance is the displacement of an individual from an area or
migration path as a result of the presence of a sound or other
stressors, and is one of the most obvious manifestations of disturbance
in marine mammals (Richardson et al., 1995). For example, gray whales
are known to change direction--deflecting from customary migratory
paths--in order to avoid noise from seismic surveys (Malme et al.,
1984). Avoidance may be short-term, with animals returning to the area
once the noise has ceased (e.g., Bowles et al., 1994; Goold, 1996;
Stone et al., 2000; Morton and Symonds, 2002; Gailey et al., 2007).
Longer-term displacement is possible, however, which may lead to
changes in abundance or distribution patterns of the affected species
in the affected region if habituation to the presence of the sound does
not occur (e.g., Blackwell et al., 2004; Bejder et al., 2006; Teilmann
et al., 2006).
A flight response is a dramatic change in normal movement to a
directed and rapid movement away from the perceived location of a sound
source. The flight response differs from other avoidance responses in
the intensity of the response (e.g., directed movement, rate of
travel). Relatively little information on flight responses of marine
mammals to anthropogenic signals exist, although observations of flight
responses to the presence of predators have occurred (Connor and
Heithaus, 1996, Bowers et al., 2018). The result of a flight response
could range from brief, temporary exertion and displacement from the
area where the signal provokes flight to, in extreme cases, marine
mammal strandings (Evans and England, 2001). However, it should be
noted that response to a perceived predator does not necessarily invoke
flight (Ford and Reeves, 2008), and whether individuals are solitary or
in groups may influence the response.
Behavioral disturbance can also impact marine mammals in more
subtle ways. Increased vigilance may result in costs related to
diversion of focus and attention (i.e., when a response consists of
increased vigilance, it may come at the cost of decreased attention to
other critical behaviors such as foraging or resting). These effects
have generally not been demonstrated for marine mammals, but studies
involving fish and terrestrial animals have shown that increased
vigilance may substantially reduce feeding rates (e.g., Beauchamp and
Livoreil, 1997; Fritz et al., 2002; Purser and Radford, 2011). In
addition, chronic disturbance can cause population declines through
reduction of fitness (e.g., decline in body condition) and subsequent
reduction in reproductive success, survival, or both (e.g., Harrington
and Veitch, 1992; Daan et al., 1996; Bradshaw et al., 1998). However,
Ridgway et al. (2006) reported that increased vigilance in bottlenose
dolphins exposed to sound over a five-day period did not cause any
sleep deprivation or stress effects.
Many animals perform vital functions, such as feeding, resting,
traveling, and socializing, on a diel cycle (24-hour cycle). Disruption
of such functions resulting from reactions to stressors such as sound
exposure are more likely to be significant if they last more than one
diel cycle or recur on subsequent days (Southall et al., 2007).
Consequently, a behavioral response lasting less than one day and not
recurring on subsequent days is not considered particularly severe
unless it could directly affect reproduction or survival (Southall et
al., 2007). Note that there is a difference between multi-day
substantive behavioral reactions and multi-day anthropogenic
activities. For example, just because an activity lasts for multiple
days does not necessarily mean that individual animals are either
exposed to activity-related stressors for multiple days or, further,
exposed in a manner resulting in sustained multi-day substantive
behavioral responses.
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 construction projects.
Auditory Masking--Since many marine mammals rely on sound to find
prey, moderate social interactions, and facilitate mating (Tyack,
2008), noise from anthropogenic sound sources can interfere with these
functions, but only if the noise spectrum overlaps with the hearing
sensitivity of the marine mammal (Southall et al., 2007; Clark et al.,
2009; Hatch et al., 2012). Chronic exposure to excessive, though not
high-intensity, noise could cause masking at particular frequencies for
marine mammals that utilize sound for vital biological functions (Clark
et al., 2009). Acoustic masking is when other noises such as from human
sources interfere
[[Page 38129]]
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; Erbe et al., 2016).
Therefore, under certain circumstances, marine mammals whose acoustical
sensors or environment are being severely masked could also be impaired
from maximizing their performance fitness in survival and reproduction.
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.
Under certain circumstances, marine mammals experiencing
significant masking could also be impaired from maximizing their
performance fitness in survival and reproduction. Therefore, when the
coincident (masking) sound is man-made, it may be considered harassment
when disrupting or altering critical behaviors. It is important to
distinguish TTS and PTS, which persist after the sound exposure, from
masking, which occurs during the sound exposure. Because masking
(without resulting in TS) is not associated with abnormal physiological
function, it is not considered a physiological effect, but rather a
potential behavioral effect.
The frequency range of the potentially masking sound is important
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation
sounds produced by odontocetes but are more likely to affect detection
of mysticete communication calls and other potentially important
natural sounds such as those produced by surf and some prey species.
The masking of communication signals by anthropogenic noise may be
considered as a reduction in the communication space of animals (e.g.,
Clark et al., 2009) and may result in energetic or other costs as
animals change their vocalization behavior (e.g., Miller et al., 2000;
Foote et al., 2004; Parks et al., 2007; Di Iorio and Clark, 2009; Holt
et al., 2009). Masking can be reduced in situations where the signal
and noise come from different directions (Richardson et al., 1995),
through amplitude modulation of the signal, or through other
compensatory behaviors (Houser and Moore, 2014). Masking can be tested
directly in captive species (e.g., Erbe, 2008), but in wild populations
it must be either modeled or inferred from evidence of masking
compensation. There are few studies addressing real-world masking
sounds likely to be experienced by marine mammals in the wild (e.g.,
Branstetter et al., 2013).
Marine mammals in Tillamook Bay are exposed to anthropogenic noise
which may lead to some habituation, but is also a source of masking.
Vocalization changes may result from a need to compete with an increase
in background noise and include increasing the source level, modifying
the frequency, increasing the call repetition rate of vocalizations, or
ceasing to vocalize in the presence of increased noise (Hotchkin and
Parks, 2013).
Masking is more likely to occur in the presence of broadband,
relatively continuous noise sources. Energy distribution of pile
driving covers a broad frequency spectrum, and sound from pile driving
would be within the audible range of pinnipeds and cetaceans present in
the proposed action area. While some pile driving during the Corps'
activities may mask some acoustic signals that are relevant to the
daily behavior of marine mammals, the short-term duration and limited
areas affected make it very unlikely that survival would be affected.
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 these activities. 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. However, given that the closest known haul outs
are approximately 1.5 km (0.9 mi) away for harbor seals and
approximately 23 km (14 mi) or greater for California sea lions,
Steller sea lions, and northern elephant seals, the likelihood of
pinnipeds being exposed to airborne noise over the short duration of
intermittent pile driving and removal is low.
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
previously have been `taken' because of exposure to underwater sound
above the behavioral harassment thresholds, which are in all cases
larger than those associated 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
The Corps' proposed activities would not result in permanent
negative impacts to habitats used directly by marine mammals, but may
have potential short-term impacts to food sources such as forage fish
and may affect acoustic habitat (see masking discussion above). There
are no known foraging hotspots or other ocean bottom structure of
significant biological importance to marine mammals present in the
marine waters of the project area. The Corps' proposed activities in
Tillamook Bay could have localized, temporary impacts on marine mammal
habitat and their prey by increasing in-water sound pressure levels and
slightly decreasing water quality. During impact pile driving and
vibratory pile driving or removal, elevated levels of underwater noise
would ensonify a portion of Tillamook Bay 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. The proposed
construction activities are of short duration and would likely have
temporary impacts on marine mammal habitat through increases in
underwater and airborne sound.
Pile installation/removal may temporarily increase turbidity
resulting from suspended sediments. Any increases would be temporary,
localized, and minimal. In general, turbidity associated with pile
installation is localized to about a 7.6 m
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(25 ft) radius around the pile (Everitt et al., 1980). Cetaceans and
pinnipeds in Tillamook Bay are not expected to be close enough to the
project pile driving areas to experience effects of turbidity; however,
if they were they could avoid localized areas of turbidity. Therefore,
the impact from increased turbidity levels is expected to minimal for
marine mammals. Furthermore, pile driving and removal at the project
site would not obstruct movements or migration of marine mammals.
Potential Pile Driving Effects on Prey--Sound from pile driving 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 that are especially strong and/or intermittent
low-frequency sounds. Short duration, sharp sounds can cause overt or
subtle changes in fish behavior and local distribution. 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). More commonly, though, the impacts of noise on fish
are temporary.
SPLs of sufficient strength have been known to cause injury to fish
and fish mortality (summarized in Popper et al., 2014). 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
activities at the project area would be temporary behavioral avoidance
of the area. The duration of fish avoidance of this area after pile
driving stops is unknown, but a rapid return to normal recruitment,
distribution, and behavior is anticipated. In general, impacts to
marine mammal prey species are expected to be minor and temporary due
to the short timeframe of the project.
In summary, given the short daily duration of sound associated with
individual pile driving and the small area being affected relative to
available nearby habitat, 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 or other prey. 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 these IHAs, which will inform both
NMFS' consideration of ``small numbers'' and the negligible impact
determinations.
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 (i.e., pile driving and removal) has the
potential to result in disruption of behavioral patterns for individual
marine mammals. There is also some potential for auditory injury (Level
A harassment) to result, primarily for high frequency cetaceans and/or
phocids because predicted auditory injury zones are larger than for
otariids. Auditory injury is unlikely to occur for otariids. The
proposed mitigation and monitoring measures are expected to minimize
the severity of the taking to the extent practicable.
As described previously, no serious injury or mortality is
anticipated or proposed to be authorized for this activity. Below we
describe how the proposed take numbers are estimated.
For acoustic impacts, generally speaking, we estimate take by
considering: (1) acoustic thresholds above which NMFS believes the best
available science indicates 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) the number of days of activities. We note
that while these factors can contribute to a basic calculation to
provide an initial prediction of potential takes, additional
information that can qualitatively inform take estimates is also
sometimes available (e.g., previous monitoring results or average group
size). Below, we describe the factors considered here in more detail
and present the proposed take estimates.
[[Page 38131]]
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--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 or exposure context (e.g., frequency, predictability, duty
cycle, duration of the exposure, signal-to-noise ratio, distance to the
source), the environment (e.g., bathymetry, other noises in the area,
predators in the area), and the receiving animals (hearing, motivation,
experience, demography, life stage, depth) and can be difficult to
predict (e.g., Southall et al., 2007, 2021, Ellison et al., 2012).
Based on what the available science indicates and the practical need to
use a threshold based on a metric that is both predictable and
measurable for most activities, NMFS typically uses a generalized
acoustic threshold based on received level to estimate the onset of
behavioral harassment. NMFS generally predicts that marine mammals are
likely to be behaviorally harassed in a manner considered to be Level B
harassment when exposed to underwater anthropogenic noise above root-
mean-squared pressure received levels (RMS SPL) of 120 dB (referenced
to 1 micropascal (re 1 [mu]Pa)) for continuous (e.g., vibratory pile-
driving, drilling) and above RMS SPL 160 dB re 1 [mu]Pa for non-
explosive impulsive (e.g., seismic airguns) or intermittent (e.g.,
scientific sonar) sources.
The Corps' proposed activity includes the use of continuous
(vibratory pile driving/removal) and impulsive (impact pile driving)
sources, and therefore the RMS SPL thresholds of 120 and 160 dB re 1
[mu]Pa are applicable.
Level A harassment--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). The Corps'
proposed activity includes the use of impulsive (impact pile driving)
and non-impulsive (vibratory pile driving/removal) sources.
These thresholds are provided in the table below. The references,
analysis, and methodology used in the development of the thresholds are
described in NMFS' 2018 Technical Guidance, which may be accessed at:
<a href="http://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance">www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance</a>.
Table 4--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
PTS Onset Thresholds * (received level)
Hearing group ------------------------------------------------------------------------
Impulsive Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans........... Cell 1: Lp,0-pk,flat: 219 Cell 2: LE,p, LF,24h: 199 dB.
dB; LE,p, LF,24h: 1183 dB.
Mid-Frequency (MF) Cetaceans........... Cell 3: Lp,0-pk,flat: 230 Cell 4: LE,p, MF,24h: 198 dB.
dB; LE,p, MF,24h: 1185 dB.
High-Frequency (HF) Cetaceans.......... Cell 5: Lp,0-pk,flat: 202 Cell 6: LE,p, HF,24h: 173 dB.
dB; LE,p,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater)..... Cell 7: Lp,0-pk.flat: 218 Cell 8: LE,p,PW,24h: 201 dB.
dB; LE,p,PW,24h: 1185 dB.
Otariid Pinnipeds (OW) (Underwater).... Cell 9: Lp,0-pk,flat: 232 Cell 10: LE,p,OW,24h: 219 dB.
dB; LE,p,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric 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 are recommended for consideration.
Note: Peak sound pressure level (Lp,0-pk) has a reference value of 1 [micro]Pa, and weighted cumulative sound
exposure level (LE,p) has a reference value of 1[micro]Pa\2\s. In this Table, thresholds are abbreviated to be
more reflective of International Organization for Standardization standards (ISO 2017). The subscript ``flat''
is being included to indicate peak sound pressure are flat weighted or unweighted within the generalized
hearing range of marine mammals (i.e., 7 Hz to 160 kHz). 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 weighted
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 thresholds will be exceeded.
Ensonified Area
Here, we describe operational and environmental parameters of the
activity that are used in estimating the area ensonified above the
acoustic thresholds, including 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 pile driving, vibratory
pile driving, and vibratory pile removal).
Sound Source Levels of Proposed Activities--The intensity of pile
driving sounds is greatly influenced by factors such as the type of
piles, hammers, and the physical environment in which the activity
takes place. In order to 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 empirical data from sound source
verification (SSV) studies reported in Navy (2015) and CALTRANS (2020),
to develop source levels for the various pile types, sizes and methods
(Table 5). These proxies were chosen as they were obtained from SSV
studies on piles of comparable types and sizes and/or in comparable
environments (e.g., they had comparable water depths). Note that these
source levels represents the SPL referenced at a distance of 10 m from
the source. It is conservatively assumed that the Corps will use steel
instead of timber for the 24-inch pipe piles as the estimated proxy
values for steel are louder than timber (e.g., Greenbusch Group, 2018;
84 FR 61026, November 12, 2019). It is also conservatively assumed that
vibratory removal will produce comparable levels of in-water noise as
vibratory installation.
[[Page 38132]]
Table 5--Estimates of Underwater Sound Levels Generated During Vibratory and Impact Pile Installation, and
Vibratory Pile Removal
----------------------------------------------------------------------------------------------------------------
Source Source Source
Pile driving method Pile level (dB level (dB level (dB Reference
description peak) RMS) SEL)
----------------------------------------------------------------------------------------------------------------
Impact (attenuated \1\)..... 24-inch steel 198 184 173 CALTRANS (2020).
pipe pile.
Vibratory (installation and 24-inch steel 177 161 ........... Navy (2015).
removal; unattenuated). pipe pile. ........... 163 163 CALTRANS (2020).
24-inch AZ
steel sheets.
12-inch steel H- 165 150 147 CALTRANS (2020).
piles.
----------------------------------------------------------------------------------------------------------------
\1\ The estimated SPLs for 24-inch steel pipes assume a 5 dB reduction resulting from the use of a confined
bubble curtain system.
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:
B = transmission loss coefficient (assumed to be 15)
R1 = the distance of the modeled SPL from the driven pile, and
R2 = the distance from the driven pile of the initial measurement.
This formula neglects loss due to scattering and absorption, which
is assumed to be zero here. The degree to which underwater sound
propagates away from a sound source is dependent on a variety of
factors, most notably the water bathymetry and presence or absence of
reflective or absorptive conditions including in-water structures and
sediments. 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 the Corps' proposed construction activities
in the absence of specific modelling. All Level B harassment isopleths
are reported in Table 7 considering RMS SSLs for impact and vibratory
pile driving, respectively.
Level A Harassment Zones--The ensonified area associated with Level
A harassment is more technically challenging to predict due to the need
to account for a duration component. Therefore, NMFS developed an
optional User Spreadsheet tool to accompany the Technical Guidance that
can be used to relatively simply predict an isopleth distance for use
in conjunction with marine mammal density or occurrence to help predict
potential takes. We note that because of some of the assumptions
included in the methods underlying this optional tool, we anticipate
that the resulting isopleth estimates are typically going to be
overestimates of some degree, which may result in an overestimate of
potential take by Level A harassment. However, this optional tool
offers the best way to estimate isopleth distances when more
sophisticated modeling methods are not available or practical. For
stationary sources, such as vibratory and impact pile driving, the
optional User Spreadsheet tool predicts the distance at which, if a
marine mammal remained at that distance for the duration of the
activity, it would be expected to incur PTS. Inputs used in the
optional User Spreadsheet tool, and the resulting estimated isopleths,
are reported in Table 6.
Table 6--NMFS User Spreadsheet Inputs
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact pile Vibratory pile driving
driving --------------------------------------------------------------------------------------------------------
installation Installation Removal
--------------------------------------------------------------------------------------------------------------------------
24-inch steel 24-inch steel 24-inch AZ steel 12-inch steel H- 24-inch steel 24-inch AZ 12-inch steel H-
pipe pile pipe pile sheets piles pipe pile steel sheets piles
--------------------------------------------------------------------------------------------------------------------------------------------------------
Spreadsheet Tab Used......... E.1) Impact pile A.1) Non-Impul, A.1) Non-Impul, A.1) Non-Impul, A.1) Non-Impul, A.1) Non-Impul, A.1) Non-Impul,
driving. Stat, Cont. Stat, Cont. Stat, Cont. Stat, Cont. Stat, Cont. Stat, Cont.
Source Level (SPL)........... 173 dB SEL...... 161 dB RMS...... 163 dB RMS...... 150 dB RMS...... 161 dB RMS..... 163 dB RMS..... 150 dB RMS.
Transmission Loss Coefficient 15.............. 15.............. 15.............. 15.............. 15............. 15............. 15.
Weighting Factor Adjustment 2............... 2.5............. 2.5............. 2.5............. 2.5............ 2.5............ 2.5.
(kHz).
Number of strikes per pile... 533.............
Time to install/remove single ................ 15.............. 10.............. 10.............. 5.............. 3.............. 3.
pile (minutes).
Piles per day................ 4............... 8............... 25.............. 10.............. 12............. 50............. 10.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Table 7--Distances to Level A Harassment, by Hearing Group, and Level B Harassment Thresholds per Pile Type and Pile Driving Method
--------------------------------------------------------------------------------------------------------------------------------------------------------
Level A harassment distance (m) Level A Level B Level B
--------------------------------- harassment harassment harassment
Piles per areas distance areas
Activity Pile description day (km\2\) for (m) all (km\2\) for
HF PW OW all hearing hearing all hearing
groups groups \1\ groups \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact Installation (attenuated) \2\.... 24-inch steel pipe pile.... 4 424.5 190.7 13.8 <0.5 399 0.39
[[Page 38133]]
Vibratory Installation.................. 24-inch steel pipe pile.... 8 16.0 6.6 0.5 <0.1 5,412 20.14
24-inch AZ steel sheets.... 14 35.5 14.6 1.0 <0.1 7,357 27.01
12-inch steel H-piles...... 10 2.6 1.1 0.1 <0.1 1,000 1.84
Vibratory Removal....................... 24-inch steel pipe pile.... 12 10.1 4.2 0.3 <0.1 5,412 20.14
24-inch AZ steel sheets.... 50 25.3 10.4 0.7 <0.1 7,357 27.01
12-inch steel H-piles...... 10 1.2 0.5 0.0 <0.1 1,000 1.84
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Harassment areas have been truncated where appropriate to account for land masses.
\2\ Distances to Level A harassment, by hearing group, for impact pile driving were calculated based on SEL source levels as they resulted in larger,
thus more conservative, isopleths for calculating PTS onset than Peak source levels.
Marine Mammal Occurrence and Take Estimation
In this section we provide information about the occurrence of
marine mammals, including density or other relevant information, that
will inform the take calculations. We also describe how the information
provided above is synthesized to produce a quantitative estimate of the
take that is reasonably likely to occur and proposed for authorization.
In most cases, recent marine mammal counts, density estimates, or
abundance estimates were not available for Tillamook Bay. Thus,
information regarding marine mammal occurrence from proximal data
obtained from nearshore sightings and haul-out sites (e.g., Three Arch
Rock) is used to approximate local abundance in Tillamook Bay. When
proximal count estimates were available (i.e., for harbor seals,
Steller sea lions, and California sea lions), the Corps derived density
estimates with an assumption that surveys accounted for animals present
in the entirety of Tillamook Bay, an area roughly 37 km\2\ (Oregon
Coastal Atlas, 2022). The Corps multiplied marine mammal densities by
isopleth areas to estimate potential take associated with pile driving.
Given that marine mammal densities are likely not uniform in Tillamook
Bay, NMFS instead estimates potential take associated with pile driving
for these and the other marine mammal species assuming maximum daily
occurrence rates (based on the abovementioned nearby proximal count
estimates) multiplied by the total number of action days estimated per
activity. There may be 20 (vibratory pile driving only) to 23
(vibratory and impact pile driving) total days of noise exposure from
pile driving during the Corps' proposed activities in Year 1 and 13
(vibratory removal only) total days of noise exposure from pile driving
during the Corps' proposed activities in Year 2. Takes for Year one for
all species except harbor porpoises (see below) are estimated assuming
that both vibratory and impact pile driving will be necessary and thus
the maximum number of days of action days are required (i.e., 23 days).
Takes for Year two assume that 13 total action days are required. A
summary of take proposed for authorization is available in Tables 8 and
9.
Harbor Porpoises
There were multiple occurrences of 1-2 harbor porpoises detected in
the coastal waters just north of the Tillamook Bay entrance during June
and July of 1990 (Halpin et al., 2009; Ford et al., 2013). More
recently, aerial surveys have detected single animals near the
Tillamook Bay entrance in October 2011 and September 2012 (Adams et
al., 2014). Although there were no recorded harbor porpoise
observations within Tillamook Bay itself, the species is somewhat
cryptic and there is potentially low detection during aerial surveys.
Thus, NMFS estimates the daily harbor porpoise abundance within
Tillamook Bay to be 1 individual.
During Year 1, if impact pile driving is necessary for driving
steel piles, the Level A harassment distance for this activity for
harbor porpoises is larger than the Level B harassment distance (Table
7) and the proposed shutdown zone (see the Proposed Mitigation
section). Therefore, the Corps proposed that all harbor porpoises in
Tillamook Bay on days when impact pile driving occurs would be taken by
Level A harassment. NMFS concurs with this estimate and proposes to
authorize 9 instances of take by Level A harassment for harbor
porpoises in Year 1 during construction of the MOF (1 harbor porpoise
per day x 9 days of impact pile driving = 9 takes by Level A
harassment).
During Year 1, if vibratory and impact pile driving is required,
the Corps estimated that there could be 14 takes of harbor porpoises by
Level B harassment (1 harbor porpoise per day x 12 days vibratory
installing steel sheets = 12 takes by Level B harassment, and 1 harbor
porpoise per day x 2 days vibratory installing H piles = 2 takes by
Level B harassment, for a total of 14 takes by Level B harassment;
Table 1). If only vibratory pile driving is required, the Corps
estimated that 20 harbor porpoises may be taken by Level B harassment
(1 harbor porpoise per day x 20 total action days; Table 1). Therefore,
to be conservative, NMFS proposes to authorize 20 instances of take by
Level B harassment for harbor porpoises (the maximum estimate of
animals that may be taken by Level B harassment based on the two likely
scenarios) in Year 1 during construction of the MOF.
During Year 2, the Corps requested and NMFS proposes to authorize
13 instances of take by Level B harassment for harbor porpoises during
vibratory removal of the MOF (1 harbor porpoise per day x 13 total
action days; Table 1). No Level A harassment is anticipated to occur or
proposed to be authorized. Considering the small Level A harassment
zones (Table 7) in comparison to the required shutdown zones (see the
Proposed Mitigation section) it is unlikely that a harbor porpoise will
enter and remain within the area between the Level A harassment zone
and the shutdown zone for a duration long enough to be taken by Level A
harassment.
California Sea Lions
The estimate for daily California sea lion abundance (n = 11) is
based on coastal surveys conducted between 2002 and 2005 (Scordino,
2006). While pile driving will occur in winter or summer, the maximum
number of animals detected during any month (i.e., 11 sea lions in
April) at the Three Arch Rock haul out site, located approximately 23
[[Page 38134]]
km (14 mi) from the proposed site of the MOF, was used to estimate
daily occurrence by the Corps. Given the distance of this haul out site
from the proposed activities, the fact that pile driving is not
expected to occur in April due to timing constrictions, and the low
likelihood that all animals present at the Three Arch Rock would leave
and enter Tillamook Bay on a single day; the Corps' estimated that
approximately half of the individuals present at Three Arch Rock (6
California sea lions) could potentially enter Tillamook Bay during pile
driving and be subject to acoustic harassment. NMFS concurs and
estimates, based on the best available science, the daily California
sea lion abundance within Tillamook Bay to be 6 individuals.
During Year 1, NMFS proposes to authorize 138 instances of take by
Level B harassment for California sea lions during the construction of
the MOF (6 California sea lions per day x 23 total action days required
for impact and vibratory pile driving; Table 1). During Year 2, NMFS
proposes to authorize 78 instances of take by Level B harassment for
California sea lions during vibratory removal of the MOF (6 California
sea lions per day x 13 total action days; Table 1). Under either
scenario, Level A harassment is not anticipated or proposed to be
authorized for Year 1 or Year 2. Considering the small Level A
harassment zones (Table 1) in comparison to the required shutdown zones
(see the Proposed Mitigation section) it is unlikely that a California
sea lion will enter and remain within the area between the Level A
harassment zone and the shutdown zone for a duration long enough to be
taken by Level A harassment.
Steller Sea Lions
The Corps and NMFS are unaware of any recent data regarding Steller
sea lion abundance near Tillamook Bay. Therefore, seasonal Steller sea
lion abundance was estimated based on the maximum number of animals
detected (n = 38 for between November and February, and n = 58 between
July and August) at the Three Arch Rock haul out site during coastal
surveys between 2002 and 2005 (Scordino, 2006). Given that this haul
out site is roughly 23 km (14 mi) away from the proposed MOF, the Corps
conservatively estimated that half of the individuals present at Three
Arch Rock (19 Steller sea lions between November and February, and 29
Steller sea lions between July and August) could potentially disperse
throughout Tillamook Bay during pile driving and be subject to
harassment from the proposed activities. For the purposes of our take
estimation, NMFS conservatively assumes that the daily Steller sea lion
abundance in Tillamook Bay is equivalent to the largest seasonal
abundance that the Corps estimated would be present (i.e., we assume
that 29 individual Steller sea lions would be present each day in
Tillamook Bay).
During Year 1, NMFS proposes to authorize 667 instances of take by
Level B harassment for Steller sea lions during the construction of the
MOF (29 Steller sea lions per day x 23 total action days required for
impact and vibratory pile driving; Table 1). During Year 2, NMFS
proposes to authorize 377 instances of take by Level B harassment for
Steller sea lions during vibratory removal of the MOF (6 Steller sea
lions per day x 13 total action days; Table 1). Under either scenario,
Level A harassment is not anticipated or proposed to be authorized for
Year 1 or Year 2. The Level A harassment zones (Table 1) are smaller
than the required shutdown zones (see the Proposed Mitigation section),
therefore it is unlikely that a Steller sea lion will enter and remain
within the area between the Level A harassment zone and the shutdown
zone for a duration long enough to be taken by Level A harassment.
Harbor Seals
The latest (May 2014) pinniped aerial surveys conducted by the
Oregon Department of Fish and Wildlife (ODFW, 2022) estimated 220
harbor seals (pups and non-pups combined) within Tillamook Bay (B.E.
Wright, personal communication, February 12, 2021). After applying the
Huber et al. (2001) correction factor of 1.53, used to account for
likely imperfect detection during surveys, the adjusted number of
harbor seals that may have been present Tillamook Bay during the 2014
surveys is approximately 337 individuals. However, that estimate likely
overestimates the number of harbor seals present in the non-pupping
season. Therefore, the Corps used calculations from monthly surveys of
Tillamook Bay haul out sites between 1978 and 1981 carried out by Brown
and Mate (1983) to estimate the average proportion of animals present
during the Nov--Feb and Jul--Aug proposed construction windows
(relative to counts observed in May). Accounting for these proportions
(0.67 and 1.2, respectively), the Corps estimated that the 337 harbor
seals likely present in May 2014 would have equated to an average
abundance of 226 harbor seals between November and February and 404
harbor seals between July and August. For the purposes of our take
estimation, NMFS conservatively assumes that the daily harbor seal
abundance in Tillamook Bay is equivalent to the largest seasonal
abundance that the Corps estimated would be present (i.e., we assume
that 404 individual harbor seals would be present each day in Tillamook
Bay).
During Year 1, NMFS estimates that 9,292 total instances of take
for harbor seals would occur during the construction of the MOF (404
harbor seals per day x 23 total action days required for impact and
vibratory pile driving; Table 1). NMFS estimates that 3,636 of these
instances of take would be attributed to impact pile driving (404
harbor seals per day x 9 days impact pile driving) and the remaining
5,656 instances of take would be attributed to vibratory pile driving
(404 harbor seals per day x 14 days vibratory pile driving). During
impact pile driving, while a 100 m shutdown zone would be implemented
for harbor seals (see Table 10 in the Proposed Mitigation section), an
area of approximately 0.07 km\2\ would still be ensonified above the
Level A harassment threshold for phocids (Table 7). Given this
remaining Level A harassment area for phocids is 17.95 percent of the
Level B harassment area (0.39 km\2\), NMFS proposes to authorize 653
(17.95 percent) of the total instances of take attributed to impact
pile driving (i.e., 17.95 percent of 3,636 instances of take), as
instances of take by Level A harassment. NMFS proposes to authorize the
remaining 8,639 instances of take by Level B harassment.
During Year 2, NMFS proposes to authorize 5,252 instances of take
by Level B harassment for harbor seals during vibratory removal of the
MOF (404 harbor seals per day x 13 total action days; Table 1). No take
by Level A harassment is anticipated to occur or proposed to be
authorized. The Level A harassment zones (Table 1) are smaller than the
required shutdown zones (see the Proposed Mitigation section),
therefore it is unlikely that a harbor seal will enter and remain
within the area between the Level A harassment zone and the shutdown
zone for a duration long enough to be taken by Level A harassment
during MOF deconstruction.
Northern Elephant Seal
There were no recorded sightings of elephant seals within 16 km (10
mi) of Tillamook Bay within the OBIS-SEAMAP database (Halpin et al.,
2009; OBIS-SEAMAP, 2022) nor were any animals detected at the closest
haul out site (i.e., Three Arch Rock) during pinniped surveys between
2002 and 2005 (Scordino, 2006). In fact, the closest haul out site with
Northern elephant seal observations during
[[Page 38135]]
surveys was Cape Arago (Scordino 2006), roughly 6 km (4 mi) south of
Coos Bay and 256 km (159 mi) south of Tillamook Bay. Given the low
likelihood of occurrence within the project vicinity and the lack of
reported sightings within the bay (Halpin et al., 2009; OBIS-SEAMAP,
2022), the Corps conservatively estimated, and NMFS assumes, elephant
seal abundance within Tillamook Bay at 1 individual every other day.
During Year 1, the Corps estimated that 12 northern elephant seals
may be taken during the construction of the MOF (1 elephant seal every
other day x 23 total action days; Table 1). If impact pile driving is
necessary for driving steel piles, the Corps estimated that the total
take during the 9 days of impact pile driving would be 5 individuals (1
elephant seal every other day x 9 total action days; Table 1). While a
100 m shutdown zone would be implemented for northern elephant seals
during impact pile driving (see Table 10 in the Proposed Mitigation
section), an area of approximately 0.07 km\2\ would still be ensonified
above the Level A harassment threshold for phocids during this activity
(Table 7). Given this remaining Level A harassment area for phocids
(0.07 km\2\) is 17.95 percent of the Level B harassment area (0.39
km\2\), NMFS proposes to authorize 17.95 percent, or 1, instance of
take by Level A harassment for northern elephant seals during impact
pile driving (17.95 percent of the 12 total instances of take). We
propose that the remaining 11 instances of take be by Level B
harassment.
During Year 2, the Corps requested and we propose 7 instances of
Level B harassment take for northern elephant seals during vibratory
removal of the MOF (1 elephant seal every other day x 13 total action
days; Table 1). Level A harassment is not anticipated or proposed to be
authorized. The Level A harassment zones (Table 1) are smaller than the
required shutdown zones (see the Proposed Mitigation section),
therefore it is unlikely that a northern elephant seal will enter and
remain within the area between the Level A harassment zone and the
shutdown zone for a duration long enough to be taken by Level A
harassment during deconstruction of the MOF.
Table 8--Proposed Authorized Amount of Taking in Year 1
----------------------------------------------------------------------------------------------------------------
Percent of
Species Stock Level A Level B Total stock
----------------------------------------------------------------------------------------------------------------
Harbor porpoise............... Northern OR/WA 9 20 29 0.14
Coast.
California sea lion........... U.S............. 0 138 138 0.05
Steller sea lion.............. Eastern......... 0 667 667 1.54
Harbor seal................... OR/CA Coastal... 653 8,639 9,292 37.57
Northern elephant seal........ California 1 11 12 0.01
Breeding.
----------------------------------------------------------------------------------------------------------------
Table 9--Proposed Authorized Amount of Taking in Year 2
----------------------------------------------------------------------------------------------------------------
Percent of
Species Stock Level A Level B Total stock
----------------------------------------------------------------------------------------------------------------
Harbor porpoise............... Northern OR/WA 0 13 13 0.06
Coast.
California sea lion........... U.S............. 0 78 78 0.03
Steller sea lion.............. Eastern......... 0 337 337 0.78
Harbor seal................... OR/CA Coastal... 0 5,252 5,252 21.24
Northern elephant seal........ California 0 7 7 <0.01
Breeding.
----------------------------------------------------------------------------------------------------------------
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, NMFS
considers 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, and impact on
operations.
The Corps must employ the following standard mitigation measures,
as included in their application and the proposed IHAs:
<bullet> The Corps must conduct briefings between construction
supervisors and crews and the marine mammal monitoring team prior to
the start of all pile driving activity, and when new personnel join the
work, to ensure that responsibilities, communication procedures, marine
mammal monitoring protocols, and operational procedures are clearly
understood;
<bullet> For in-water work other than pile driving/removal (e.g.,
stone placement, use of barge-mounted excavators, or dredging), if a
marine mammal comes within 10 m (33 ft), operations shall cease. Should
a marine mammal come within 10 m (33ft) of a vessel in transit, the
boat operator would reduce vessel speed to the minimum level required
to maintain steerage and safe working conditions. If human safety is at
risk,
[[Page 38136]]
the in-water activity will be allowed to continue until it is safe to
stop;
<bullet> In-water work activities may only occur when PSOs can
effectively visually monitor for the presence of marine mammals, and
when the entire shutdown zone and adjacent waters are visible (e.g.,
including during daylight hours and when monitoring effectiveness is
not reduced due to rain, fog, snow, etc.).
<bullet> For all pile driving/removal activities, the Corps must
establish a minimum 15 m (49 ft) shutdown zone. The purpose of a
shutdown zone is generally to define an area within which shutdown of
activity would occur upon sighting of a marine mammal (or in
anticipation of an animal entering the defined area). Shutdown zones
will vary based on the type of driving/removal activity type and by
marine mammal hearing group (see Table 10). Here, shutdown zones are
larger than the calculated Level A harassment isopleth shown in Table
7, except for harbor porpoises, harbor seals, and northern elephant
seals during impact driving of 24-inch steel piles when a 100-m
shutdown zone will be visually monitored;
Table 10--Shutdown Zones During Project Activities
----------------------------------------------------------------------------------------------------------------
Distance (m)
Activity Pile description -----------------------------------------------
HF PW OW
----------------------------------------------------------------------------------------------------------------
Impact Installation (attenuated)...... 24-inch steel pipe pile. 100 100 15
Vibratory Installation................ 24-inch steel pipe pile. 50 15 15
24-inch AZ steel sheets. 50 15 15
12-inch steel H-piles... 15 15 15
Vibratory Removal..................... 24-inch steel pipe pile. 15 15 15
24-inch AZ steel sheets. 50 15 15
12-inch steel H-piles... 15 15 15
----------------------------------------------------------------------------------------------------------------
<bullet> The Corps must delay or shutdown all pile driving
activities should an animal approach or enter the appropriate shutdown
zone. The Corps may resume activities after one of the following
conditions have been met: (1) the animal is observed exiting the
shutdown zone; (2) the animal is thought to have exited the shutdown
zone based on a determination of its course, speed, and movement
relative to the pile driving location; or (3) the shutdown zone has
been clear from any additional sightings for 15 minutes;
<bullet> The Corps will employ PSOs trained in marine mammal
identification and behaviors to monitor marine mammal presence in the
action area, and must establish the following monitoring locations:
during vibratory driving, at least one PSO must be stationed on the
shoreline near the Port of Garibaldi to monitor as much of the Level B
harassment zone as possible, and another PSO must be stationed on the
shoreline adjacent to the proposed MOF site to monitor the shutdown
zone; during impact pile driving, two PSOs must be stationed on the
shoreline adjacent to the proposed MOF site to monitor the shutdown
zone. The Corps 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 pile driving and
removal at least two PSOs must be used;
<bullet> The placement of the PSOs during all pile driving and
removal activities will ensure that the entire Level A harassment and
shutdown zones are visible during pile installation and removal;
<bullet> Monitoring must take place from 30 minutes prior to
initiation of pile driving (i.e., pre-clearance monitoring) through 30
minutes post-completion of pile driving;
<bullet> If in-water work ceases for more than 30 minutes, the
Corps will conduct pre-clearance monitoring of both the Level B
harassment zone and shutdown zone;
<bullet> Pre-start clearance monitoring must be conducted during
periods of visibility sufficient for the lead PSO to determine that the
shutdown zones indicated in Table 10 are clear of marine mammals. Pile
driving may commence following 30 minutes of observation when the
determination is made that the shutdown zones are clear of marine
mammals;
<bullet> Marine mammals observed anywhere within visual range of
the PSO will be tracked relative to construction activities. If a
marine mammal is observed entering or within the shutdown zones
indicated in Table 10, pile driving must be delayed or halted. 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
(Table 10), or 15 minutes have passed without re-detection of the
animal;
<bullet> Vibratory hammers are the preferred method for installing
piles at the MOF. If impact hammers are required to install steel
piles, a confined bubble curtain must be used to minimize noise levels.
The bubble curtain must adhere by the following restrictions:
[cir] The bubble curtain must distribute air bubbles around 100
percent of the piling circumference for the full depth of the water
column;
[cir] The lowest bubble ring must be in contact with the substrate
for the full circumference of the ring, and the weights attached to the
bottom ring shall ensure 100 percent substrate contact. No parts of the
ring or other objects shall prevent full substrate contact; and
[cir] Air flow to the bubblers must be balanced around the
circumference of the pile;
<bullet> The Corps 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 thirty-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
thirty minutes or longer. Soft starts will not be used for vibratory
pile installation and removal. PSOs shall begin observing for marine
mammals 30 minutes before ``soft start'' or in-water pile installation
or removal begins;
<bullet> 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
[[Page 38137]]
number of takes has been met, entering or within the harassment zone;
Based on our evaluation of the applicant's proposed measures, NMFS
has preliminarily determined that the proposed mitigation measures
provide the means of effecting the least practicable 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 while
conducting the activities. 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:
<bullet> Occurrence of marine mammal species or stocks in the area
in which take is anticipated (e.g., presence, abundance, distribution,
density);
<bullet> 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);
<bullet> Individual marine mammal responses (behavioral or
physiological) to acoustic stressors (acute, chronic, or cumulative),
other stressors, or cumulative impacts from multiple stressors;
<bullet> How anticipated responses to stressors impact either: (1)
long-term fitness and survival of individual marine mammals; or (2)
populations, species, or stocks;
<bullet> Effects on marine mammal habitat (e.g., marine mammal prey
species, acoustic habitat, or other important physical components of
marine mammal habitat); and,
<bullet> Mitigation and monitoring effectiveness.
Visual Monitoring
Monitoring must be conducted by qualified, NMFS-approved PSOs, in
accordance with the following:
<bullet> 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 IHA. Other
PSOs may substitute other relevant experience, education (degree in
biological science or related field), or training for prior experience
performing the duties of a PSO during construction activity pursuant to
a NMFS-issued IHA. PSOs must be approved by NMFS prior to beginning any
activity subject to these IHAs; and
<bullet> PSOs would be placed at two vantage points as
aforementioned in the Proposed Mitigation section (see Figure 1-3 of
the Corps' IHA Application) to monitor for marine mammals and implement
shutdown/delay procedures when applicable by calling for the shutdown
to the hammer operator;
<bullet> PSOs would use a hand-held GPS device or rangefinder to
verify the required monitoring distance from the project site;
<bullet> PSOs would scan the waters within the Level A harassment
and Level B harassment zones using binoculars (10x42 or similar) or
spotting scopes (20-60 zoom or equivalent) and make visual observations
of marine mammals present; and
<bullet> PSOs must record all observations of marine mammals,
regardless of distance from the pile being driven. PSOs shall document
any behavioral reactions in concert with distance from piles being
driven or removed.
PSOs must have the following additional qualifications:
<bullet> Ability to conduct field observations and collect data
according to assigned protocols;
<bullet> Experience or training in the field identification of
marine mammals, including the identification of behaviors;
<bullet> Sufficient training, orientation, or experience with the
construction operation to provide for personal safety during
observations;
<bullet> 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
<bullet> Ability to communicate orally, by radio or in person, with
project personnel to provide real-time information on marine mammals
observed in the area as necessary;
Additionally, the Corps will have PSOs conduct one pinniped
monitoring count a week prior to construction and report the number of
marine mammals present within 500 m (1640 ft) of the Tillamook South
Jetty or MOF. Upon completion of jetty repairs, PSOs would conduct two
post-construction monitoring events, with one approximately 4 weeks
after construction, and another at 8 weeks post construction. These
post-construction marine mammal surveys would help to determine whether
marine mammal detections post-construction were comparable to surveys
conducted prior to construction.
Reporting
Draft marine mammal monitoring reports would be submitted to NMFS
within 90 days after the completion of pile driving (Year 1 IHA) and
removal activities (Year 2 IHA), or 60 days prior to a requested date
of issuance of any future IHAs for projects at the same location,
whichever comes first. The reports would include an overall description
of work completed, a narrative regarding marine mammal sightings, and
associated PSO data sheets. Specifically, the reports must include:
<bullet> Dates and times (begin and end) of all marine mammal
monitoring;
<bullet> 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 vibratory) and the total
equipment duration for vibratory installation and removal for each pile
or total number of strikes for each pile (impact driving);
<bullet> PSO locations during marine mammal monitoring;
<bullet> 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;
<bullet> 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
[[Page 38138]]
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, sex class,
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);
<bullet> Number of marine mammals detected within the harassment
zones and shutdown zones, by species;
<bullet> 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;
<bullet> Description of other human activity within each monitoring
period;
<bullet> Description of any deviation from initial proposal in pile
numbers, pile types, average driving times, etc.;
<bullet> Brief description of any impediments to obtaining reliable
observations during construction period; and
<bullet> Description of any impediments to complying with these
mitigation measures.
If no comments are received from NMFS within 30 days, the draft
final reports would constitute the final reports. 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) (<a href="/cdn-cgi/l/email-protection#1b4b4935524f4b35567475726f746972757c497e6b74696f685b75747a7a357c746d"><span class="__cf_email__" data-cfemail="db8b89f5928f8bf596b4b5b2afb4a9b2b5bc89beabb4a9afa89bb5b4babaf5bcb4ad">[email protected]</span></a>), NMFS and to the West Coast Regional Stranding
Coordinator as soon as feasible. If the death or injury was clearly
caused by the specified activity, the Corps 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 IHAs. The Corps
must not resume their activities until notified by NMFS. The report
must include the following information:
<bullet> Time, date, and location (latitude/longitude) of the first
discovery (and updated location information if known and applicable);
<bullet> Species identification (if known) or description of the
animal(s) involved;
<bullet> Condition of the animal(s) (including carcass condition if
the animal is dead);
<bullet> Observed behaviors of the animal(s), if alive;
<bullet> If available, photographs or video footage of the
animal(s); and
<bullet> 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 impacts or responses (e.g., intensity, duration),
the context of any impacts or responses (e.g., critical reproductive
time or location, foraging impacts affecting energetics), 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' 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 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).
To avoid repetition, the discussion of our analysis applies to all
the species listed in Table 2, 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.
Pile driving activities associated with the Corps' proposed
construction activities, as outlined previously, have the potential to
disturb or displace marine mammals. Specifically, the specified
activities may result in take, in the form of Level B harassment
(behavioral disturbance), and for some species, Level A harassment
incidental to underwater sounds generated from pile driving. Potential
takes could occur if individuals are present in zones ensonified above
the thresholds for Level B harassment and Level A harassment,
identified above, while activities are underway.
NMFS does not anticipate that serious injury or mortality would
occur as a result of the Corps' planned activity given the nature of
the activity, even in the absence of required mitigation. For all
species and stocks, take would occur within a limited, confined area
(adjacent to the project site) of the stock's range. Required
mitigation is expected to minimize the duration and intensity of the
authorized taking by Level A and Level B harassment. Further, the
amount of take proposed to be authorized is extremely small for 4 of
the 5 species when compared to stock abundance.
The primary method of installation will be vibratory pile driving.
Vibratory pile driving produces lower SPLs than impact pile driving.
The rise time of the sound produced by vibratory pile driving is
slower, reducing the probability and severity of injury. Impact pile
driving produces short, sharp pulses with higher peak levels and much
sharper rise time to reach those peaks. If impact pile driving is used,
implementation of soft start measures, a bubble curtain, and shutdown
zones will significantly reduce any possibility of injury. Given
sufficient notice through use of soft starts (for impact driving),
marine mammals are expected to move away from a sound source prior to
it becoming potentially injurious. The Corps will use two PSOs
stationed strategically to increase detectability of marine mammals
during pile installation and removal, enabling a high rate of success
in implementation of shutdowns to avoid injury for most
[[Page 38139]]
species. 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.
Additionally, and as noted previously, some subset of the
individuals that are behaviorally harassed could also simultaneously
incur some small degree of TTS for a short duration of time. Because of
the small degree anticipated, though, any TTS potentially incurred here
would not be expected to adversely impact individual fitness, let alone
annual rates of recruitment or survival.
Behavioral responses of marine mammals to pile driving and removal
in Tillamook Bay are expected to be mild, short term, and temporary.
Marine mammals within the Level B harassment zones may not show any
visual cues they are disturbed by activities or they could become
alert, avoid the area, leave the area, or display other mild responses
that are not observable such as changes in vocalization patterns or
increased haul out time (Thorson and Reyff, 2006). Given that pile
driving and removal would occur intermittently for only a short
duration (20-23 days in Year 1 and 13 days in Year 2), often on
nonconsecutive days, any harassment occurring would be temporary.
Additionally, many of the species present in the region would only be
present temporarily based on seasonal patterns or during transit
between other habitats. These temporarily present species would be
exposed to even smaller periods of noise-generating activity, further
decreasing the impacts.
Effects on individuals that are taken by Level B harassment, on the
basis of reports in the literature as well as monitoring from other
similar activities, will likely be limited to reactions such as
increased swimming speeds, increased surfacing time, or decreased
foraging (if such activity were occurring) (e.g., Thorson and Reyff,
2006). Most likely, individuals will simply move away from the sound
source and be temporarily displaced from the areas of pile driving,
although even this reaction has been observed primarily only in
association with impact pile driving, which will only be used if
necessary. The pile driving activities analyzed here are similar to, or
less impactful than, other construction activities conducted in Oregon,
which have taken place with no known long-term adverse consequences
from behavioral harassment. Level B harassment will be reduced to the
level of least practicable adverse impact through use of mitigation
measures described herein and, if sound produced by project activities
is sufficiently disturbing, animals are likely to simply avoid the area
while the activity is occurring.
The Corps' proposed activities are limited in scope spatially.
While precise impacts would not be known until the MOF has been
designed, based on an MOF built for a similar project (The Coos Bay
North Jetty Maintenance project, <a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-us-army-corps-engineers-north-jetty-maintenance-and-repairs">https://www.fisheries.noaa.gov/action/incidental-take-authorization-us-army-corps-engineers-north-jetty-maintenance-and-repairs</a>), it is estimated that temporary impacts below
the high tide line (HTL) would be limited to 0.14 acres or less. The
full extent of the MOF and associated access dredging would be
approximately 3.6 acres, with an additional 3.7 acres of upland
disturbance associated with the MOF staging area. For all species,
there are no known habitat areas of particular importance (e.g.,
Biologically Important Areas (BIAs), critical habitat, primary foraging
or calving habitat) in the project area that would be impacted by the
Corps' proposed activities. While takes may occur during important
feeding or breeding times, the project area represents a small portion
of available foraging and breeding habitat and impacts on marine mammal
feeding and breeding for all species should be minimal. In general,
cetaceans and pinnipeds are infrequent visitors near the site of the
proposed construction activities due to shallow waters in this region
further reducing the likelihood that cetaceans and pinnipeds will
approach and be present within the ensonified areas. Further, none of
the harassment isopleths block the entrance out of Tillamook Bay (see
Figures 6-1 and 6-2 in the Corps' application), thus marine mammals
could leave the bay and engage in foraging, social behavior or other
activities without being subject to Level A or Level B harassment.
The impact of harassment on harbor seals is difficult to assess
given the most recent abundance estimate available for this stock is
from 1999 (Table 2). We are aware that there is one haul-out site
located approximately 1.5 km (0.9 mi) east of the proposed construction
site on an intertidal sand flat in the middle of the bay (see Figure 4-
1 in the Corps' application) that has been historically noted in
Tillamook Bay. Given the Level B harassment distances for vibratory
installation and removal of 24-inch steel pipe piles and 24-inch AZ
steel sheets are larger than 1.5 km (0.9 mi) (see Table 7), we can
presume that some harbor seals will be repeatedly taken. In addition,
while no there are no known pinniped haul outs on Bayocean split,
harbor seals and other pinnipeds may be resting or hauled out on land
near the site of the MOF construction, jetty rocks, or nearby beaches.
Repeated, sequential exposure to pile driving noise over a long
duration could result in more severe impacts to individuals that could
affect a population; however, the limited number of non-consecutive
pile driving days for this project means that these types of impacts
are not anticipated.
The project also is not expected to have significant adverse
effects on affected marine mammal habitat. The project activities would
not modify existing marine mammal habitat for a significant amount of
time. Any impacts on marine mammal prey that would occur during the
Corps' planned activity would have, at most, short-term effects on
foraging of individual marine mammals, and likely no effect on the
populations of marine mammals as a whole. The activities may cause some
fish to leave the area of disturbance, thus temporarily impacting
marine mammal foraging opportunities in a limited portion of the
foraging range. However, because of the short duration of the
activities and the small area of the habitat that may be affected, the
impacts to marine mammal habitat are not expected to cause significant
or long-term negative consequences. Indirect effects on marine mammal
prey during the construction are expected to be minor, and these
effects are unlikely to cause substantial effects on marine mammals at
the individual level, with no expected effect on annual rates of
recruitment or survival.
In addition, it is unlikely that minor noise effects in a small,
localized area of habitat would have any effect on the stocks' annual
rates of recruitment or survival. 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 would have only minor, short-term effects on individuals.
The specified activities are not expected to impact rates of
recruitment or survival and would, 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 any of the species
or stocks through effects on annual rates of recruitment or survival:
<bullet> No serious injury or mortality is anticipated or
authorized;
[[Page 38140]]
<bullet> The number of total takes (by Level A and Level B
harassment) are less than 2 percent of the best available abundance
estimates for all but one stock;
<bullet> The Corps would implement mitigation measures including
soft-starts and shutdown zones to minimize the numbers of marine
mammals exposed to injurious levels of sound, and to ensure that take
by Level A harassment is, at most, a small degree of PTS;
<bullet> Take would not occur in places and/or times where take
would be more likely to accrue to impacts on reproduction or survival,
such as within BIAs, or other habitats critical to recruitment or
survival (e.g., rookery);
<bullet> Take would occur over a short timeframe (i.e.,
intermittently over up to 23 and 13 non-consecutive days in Year 1 and
Year 2, respectively). This short timeframe minimizes the probability
of multiple exposures on individuals, and any repeated exposures that
do occur are not expected to occur on sequential days, decreasing the
likelihood of physiological impacts caused by chronic stress or
sustained energetic impacts that might affect survival or reproductive
success;
<bullet> Any impacts to marine mammal habitat from pile driving
(including to prey sources as well as acoustic habitat, e.g., from
masking) are expected to be temporary and minimal; and
<bullet> Take would only occur within a small portion of Tillamook
Bay--a limited, confined area of any given stock's home range.
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, specific to both the
Year 1 and Year 2 proposed IHAs, 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 sections 101(a)(5)(A) and (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 but one species (in fact, take of
individuals is less than 2 percent of the abundance of the 4 of the 5
affected stocks, see Tables 8 and 9). This is likely a conservative
estimate because we 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.
There is no current estimate of abundance available for this harbor
seals (Carretta et al., 2021). In 1999, aerial surveys of harbor seals
in Oregon and Washington were conducted by the National Marine Mammal
Laboratory (NMLL) and the Oregon and Washington Departments of Fish and
Wildlife (ODFW and WDFD) during the pupping season. After applying a
correction factor to account for seals missed during aerial surveys
(Huber et al., 2001), they estimated that the population size of the
Oregon/Washington Coast Stock of harbor seals was 24,732 (CV = 0.12) in
1999. Historical and current trends of harbor seal abundance in Oregon
and Washington are unknown. Based on the analyses of Jeffries et al.
(2003) and Brown et al. (2005), both the Washington and Oregon portions
of this stock were reported as reaching carrying capacity. While the
proposed authorized take for harbor seals is 37.57 percent of the 1999
abundance estimate in Year 1 and 21.24 percent of this abundance in
Year 2, harbor seals are not known to make extensive migrations and are
known to display strong fidelity to haul out sites (Pitcher and
Calkins, 1979; Pitcher and McAllister, 1981). Therefore, we presume
that some of the harbor seals present in the action area will be
repeatedly taken and actual number of individuals exposed to Level A
and Level B harassment will be much lower. Further, we calculated
proposed take estimates of harbor seals assuming the maximum seasonal
abundance of individuals were present in Tillamook Bay during each
action day; however, work may occur during other times of the year when
harbor seal abundance is estimated to be lower, and thus the actual
number of individuals exposed to Level A and Level B harassment would
be lower. Lastly, take would occur in a small portion of Tillamook Bay
and it is unlikely that a third of the stock would be in these waters
during the short duration of the proposed activities.
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, specific
to both the Year 1 and Year 2 proposed IHAs, that small numbers of
marine mammals would 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 Endangered Species Act of 1973 (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 these activities. 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 two IHAs to the Corps incidental to conducting repairs of the
Tillamook South Jetty in Tillamook Bay, Oregon from November 1, 2022 to
October 31, 2023 (Year 1 IHA) and from November 1, 2024 to October 31,
2025 (Year 2 IHA), provided the previously mentioned mitigation,
monitoring, and reporting requirements are incorporated. Drafts of the
proposed IHAs can be found at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities</a>.
[[Page 38141]]
Request for Public Comments
We request comment on our analyses, the proposed authorizations,
and any other aspect of this notice of proposed IHAs for the proposed
construction activities. We also request comment on the potential
renewal of these proposed IHAs 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 these IHAs or a
subsequent renewal IHA.
On a case-by-case basis, NMFS may issue a one-time, one-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
Activities section of this notice is planned or (2) the activities as
described in the Description of Proposed Activities 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:
<bullet> A request for renewal is received no later than 60 days
prior to the needed renewal IHA effective date (recognizing that the
renewal IHA expiration date cannot extend beyond one year from
expiration of the initial IHA).
<bullet> 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).
(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.
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: June 21, 2022.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2022-13605 Filed 6-24-22; 8:45 am]
BILLING CODE 3510-22-P
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